JP2008041570A - Cathode active material for nonaqueous electrolyte secondary battery, its manufacturing method, and nonaqueous electrolyte secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve chemical stability of a cathode active material for a nonaqueous electrolyte secondary battery by controlling aggregation of particles coated with metal hydroxide on their surface. <P>SOLUTION: The cathode active material for the nonaqueous electrolyte secondary battery comprises a composite oxide particle, a coating layer which is at least partially formed on the particle and made of oxide containing lithium(Li), and at least one of coating elements of nickel(Ni), or manganese(Mn), and a surface layer which is at least partially formed on the coating layer and made of oxide of at least one of silicon(Si), aluminum(Al), titanium(Ti), or zirconium(Zr). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a positive electrode active material for a non-aqueous electrolyte secondary battery, a method for producing the same, and a non-aqueous electrolyte secondary battery, for example, a non-water containing a composite oxide containing lithium (Li) and cobalt (Co). The present invention relates to a positive electrode active material for an electrolyte secondary battery, a method for producing the same, and a nonaqueous electrolyte secondary battery using the positive electrode active material for a nonaqueous electrolyte secondary battery.

  In recent years, with the widespread use of portable devices such as video cameras and notebook personal computers, the demand for small, high-capacity secondary batteries has increased. Currently used secondary batteries include nickel-cadmium batteries using an alkaline electrolyte, but the battery voltage is as low as about 1.2 V, and it is difficult to improve the energy density. For this reason, a lithium metal secondary battery using lithium metal having a specific gravity of 0.534, which is the lightest of the solid simple substance, the potential is extremely base, and the current capacity per unit weight is the largest among the metal negative electrode materials. It was done.

  However, in a secondary battery using lithium metal as a negative electrode, dendrite, which is dendritic lithium, is deposited on the surface of the negative electrode during charging, and grows by a charge / discharge cycle. The growth of the dendrite has problems such as deterioration of the cycle characteristics of the secondary battery, and further breaking through a diaphragm (separator) disposed so that the positive electrode and the negative electrode are not in contact with each other, thereby causing an internal short circuit.

  Thus, for example, as described in Patent Document 1, a secondary battery that repeats charging and discharging by using a carbonaceous material such as coke as a negative electrode and doping and dedoping alkali metal ions has been proposed. As a result, it has been found that the above-described problem of deterioration of the negative electrode due to repeated charge / discharge can be avoided.

JP 62-90863 A

  On the other hand, as positive electrode active materials, inorganic compounds such as transition metal oxides and transition metal chalcogens containing alkali metals are known as those capable of obtaining a battery voltage of around 4V. Among these, lithium composite oxides such as lithium cobaltate or lithium nickelate are most promising in terms of high potential, stability, and long life.

In particular, a positive electrode active material mainly composed of lithium cobaltate is a positive electrode active material exhibiting a high potential, and is expected to increase the energy density by increasing the charging voltage. However, there is a problem that the cycle characteristics deteriorate when the charging voltage is increased. Therefore, conventionally, a method of modifying the positive electrode active material by using a small amount of LiMn _1/3 Co _1/3 Ni _1/3 O ₂ or the like, or coating the surface with another material has been performed. .

By the way, the technique for modifying the positive electrode active material by the surface coating of the positive electrode active material described above has a problem of achieving high coverage. In order to solve this problem, various methods have been proposed. For example, it is confirmed that the method of depositing with a metal hydroxide is excellent in covering properties. As such a method, for example, Patent Document 2 discloses the surface of lithium nickelate (LiNiO ₂ ) particles. Discloses the deposition of cobalt (Co) and manganese (Mn) through its hydroxide deposition process. For example, Patent Document 3 discloses that a non-manganese metal is deposited on the surface of a lithium manganese composite oxide through a hydroxide deposition process.

JP-A-9-265985 JP-A-11-71114

  However, when heat treatment is performed after depositing a metal hydroxide on the composite oxide particles, there is a problem that sintering is likely to proceed between the particles and the particles are likely to be bound to each other. As a result, when mixed with a conductive agent or the like when producing the positive electrode, the bonded portion and particles are broken or cracked, the coating layer is peeled off, and the damaged surface of the particles is exposed. End up. Such a damaged surface is very active compared to the surface formed at the time of firing, and the deterioration reaction of the electrolytic solution and the positive electrode active material is likely to occur.

  Accordingly, an object of the present invention is to provide a positive electrode active material for a non-aqueous electrolyte secondary battery that can further improve chemical stability by suppressing binding between particles, a method for producing the same, and a high-performance material using the positive electrode active material. An object of the present invention is to provide a nonaqueous electrolyte secondary battery having excellent capacity and charge / discharge cycle characteristics.

In order to solve the above-described problem, the first invention
Composite oxide particles containing at least lithium (Li) and cobalt (Co);
A coating layer formed of an oxide provided on at least a part of the composite oxide particles and including lithium (Li) and at least one coating element of nickel (Ni) and manganese (Mn);
A surface layer made of an oxide of at least one element of silicon (Si), aluminum (Al), Ti (titanium), and zirconium (Zr), provided on at least a part of the coating layer;
A positive electrode active material for a non-aqueous electrolyte secondary battery.

In the first invention, the composite oxide particles preferably have an average composition represented by Chemical Formula 1 and Chemical Formula 2.
(Chemical formula 1)
_{Li (1 + W) Co (} 1-xy) Ma x Mb y O (2-z)
(In the chemical formula 1, Ma is Bi (bismuth) or Ga (gallium), Mb is vanadium (V), chromium (Cr), boron (B), manganese (Mn), iron (Fe), nickel (Ni), Copper (Cu), zinc (Zn), aluminum (Al), magnesium (Mg), titanium (Ti), zirconium (Zr), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), It is composed of at least one element selected from the group consisting of yttrium (Y) and tungsten (W), and w, x, y, and z are −0.10 ≦ w ≦ 0.10, 0.001 <x < 0.10, 0 ≦ y <0.40, −0.10 ≦ z ≦ 0.20)
(Chemical formula 2)
Li _{(1 + W)} Co _(1-xy) Mc _x Md _y O _(2-z)
(In the chemical formula 2, Mc is Mg (magnesium), Al (aluminum), Ti (titanium), Zr (zirconium), Md is vanadium (V), chromium (Cr), boron (B), manganese (Mn), From iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), yttrium (Y), tungsten (W) It is composed of at least one selected element, and w, x, y, and z are −0.10 ≦ w ≦ 0.10, 0.001 <x <0.10, 0 ≦ y <0.40, −0 .10 ≦ z ≦ 0.20)

  In 1st invention, it is preferable that the structural ratio of nickel (Ni) and manganese (Mn) in a coating layer exists in the range of 100: 0-30: 70 by molar ratio.

  In the first invention, the oxide of the coating layer contains 40 mol% or less of the total amount of nickel (Ni) and manganese (Mn), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), Vanadium (V), chromium (Cr), iron (Fe), cobalt (Co), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), It is preferable that the element is replaced with at least one metal element selected from the group consisting of tungsten (W), yttrium (Y), and zirconium (Zr).

  In 1st invention, it is preferable that the amount of deposition elements of a coating layer exists in the range of 0.5 mol% or more and 50 mol% or less with respect to the metal mol number of composite oxide particle.

  In 1st invention, it is preferable that the primary average particle diameter of the metal oxide particle which forms a coating layer is 1.0 nm or more and 100 nm or less.

  In 1st invention, it is preferable that the metal oxide particle which forms a coating layer is 0.01 mol% or more and 10 mol% or less with respect to the metal element of composite oxide particle.

  In 1st invention, it is preferable that the average particle diameter of the positive electrode active material for nonaqueous electrolyte secondary batteries exists in the range of 2.0 micrometers or more and 50 micrometers or less.

The second invention is
After forming a layer made of a hydroxide containing nickel (Ni) and / or manganese (Mn) on at least a part of the composite oxide particles containing at least lithium (Li) and cobalt (Co), the composite oxide Forming a hydroxide containing at least one of silicon (Si), aluminum (Al), Ti (titanium), and zirconium (Zr) on at least a part of the particles;
After forming a hydroxide containing at least one of silicon (Si), aluminum (Al), Ti (titanium), and zirconium (Zr), heat treatment is performed so that lithium oxide is added to at least a part of the composite oxide particles. Forming a coating layer made of an oxide containing (Li) and at least one of the coating elements of nickel (Ni) and manganese (Mn), and a surface layer made of an oxide containing magnesium (Mg); ,
It is a manufacturing method of the positive electrode active material characterized by having.

In the second invention, the composite oxide particles preferably have an average composition represented by Chemical Formula 1 or Chemical Formula 2.
(Chemical formula 1)
_{Li (1 + W) Co (} 1-xy) Ma x Mb y O (2-z)
(In the chemical formula 1, Ma is Bi (bismuth) or Ga (gallium), Mb is vanadium (V), chromium (Cr), boron (B), manganese (Mn), iron (Fe), nickel (Ni), Copper (Cu), zinc (Zn), aluminum (Al), magnesium (Mg), titanium (Ti), zirconium (Zr), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), It is composed of at least one element selected from the group consisting of yttrium (Y) and tungsten (W), and w, x, y, and z are −0.10 ≦ w ≦ 0.10, 0.001 <x < 0.10, 0 ≦ y <0.40, −0.10 ≦ z ≦ 0.20)
(Chemical formula 2)
Li _{(1 + W)} Co _(1-xy) Mc _x Md _y O _(2-z)
(In the chemical formula 2, Mc is Mg (magnesium), Al (aluminum), Ti (titanium), Zr (zirconium), Md is vanadium (V), chromium (Cr), boron (B), manganese (Mn), From iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), yttrium (Y), tungsten (W) It is composed of at least one selected element, and w, x, y, and z are −0.10 ≦ w ≦ 0.10, 0.001 <x <0.10, 0 ≦ y <0.40, −0 .10 ≦ z ≦ 0.20)

In the second invention, the deposition of a hydroxide containing nickel (Ni) and / or manganese (Mn)
It is preferable to carry out by adding the compound of nickel (Ni) and / or the compound of manganese (Mn) after dispersing the composite oxide particles in a solvent mainly composed of water having a pH of 12 or more.

  Furthermore, in the second invention, it is preferable that the solvent mainly composed of water contains lithium hydroxide.

  In 2nd invention, it is preferable that the structural ratio of nickel (Ni) and manganese (Mn) in a coating layer exists in the range of 100: 0-30: 70 by molar ratio.

  In the second invention, the oxide of the coating layer contains 40 mol% or less of the total amount of nickel (Ni) and manganese (Mn), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), Vanadium (V), chromium (Cr), iron (Fe), cobalt (Co), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), It is preferable that it is replaced with at least one metal element selected from the group consisting of tungsten (W), yttrium (Y), and zirconium (Zr).

  In 2nd invention, it is preferable that the amount of deposition elements of a coating layer exists in the range of 0.5 mol% or more and 50 mol% or less with respect to the metal mol number of composite oxide particle.

  In 2nd invention, it is preferable that the primary average particle diameter of the metal oxide particle which forms a coating layer is 1.0 nm or more and 100 nm or less.

  In 2nd invention, it is preferable that the metal oxide particle which forms a coating layer is 0.01 mol% or more and 10 mol% or less with respect to the metal element of composite oxide particle.

  In 2nd invention, it is preferable that the average particle diameter of the positive electrode active material for nonaqueous electrolyte secondary batteries exists in the range of 2.0 micrometers or more and 50 micrometers or less.

In the third invention, a layer made of a hydroxide containing nickel (Ni) and / or manganese (Mn) is formed on at least a part of the composite oxide particles containing at least lithium (Li) and cobalt (Co). And a process of
The surface of the composite oxide particle is coated with an oxide of at least one element selected from silicon (Si), aluminum (Al), Ti (titanium), and zirconium (Zr), and then subjected to heat treatment, thereby performing composite oxidation. At least part of the material particles, a coating layer made of an oxide containing lithium (Li) and at least one of nickel (Ni) and manganese (Mn), and silicon (Si), aluminum (Al ), Forming a surface layer made of an oxide of at least one element of Ti (titanium) and zirconium (Zr);
It is a manufacturing method of the positive electrode active material for nonaqueous electrolyte secondary batteries characterized by having.

The fourth invention is:
A positive electrode having a positive electrode active material for a non-aqueous electrolyte secondary battery, a negative electrode, and an electrolyte;
The positive electrode active material for non-aqueous electrolyte secondary batteries is
Composite oxide particles containing at least lithium (Li) and cobalt (Co);
A coating layer formed of an oxide provided on at least a part of the composite oxide particles and including lithium (Li) and at least one coating element of nickel (Ni) and manganese (Mn);
A surface layer made of an oxide of at least one element of silicon (Si), aluminum (Al), Ti (titanium), and zirconium (Zr), provided on at least a part of the coating layer;
It is a nonaqueous electrolyte secondary battery characterized by the above-mentioned.

  In this invention, since at least a part of the composite oxide particles includes a coating layer made of an oxide containing lithium (Li) and at least one of the coating elements of nickel (Ni) and manganese (Mn), High charge voltage characteristics and high energy density characteristics associated therewith can be realized, and it has good charge / discharge cycle characteristics under high charge voltage conditions.

  In the present invention, the composite oxide particles provided with a hydroxide containing at least one of nickel (Ni) and manganese (Mn) are provided with silicon (Si), aluminum (Al), Ti (titanium), By forming a hydroxide containing at least one kind of zirconium (Zr), binding between particles can be suppressed.

  According to this invention, the chemical stability of the positive electrode active material for a nonaqueous electrolyte secondary battery can be further improved. Moreover, the battery using this positive electrode active material for nonaqueous electrolyte secondary batteries can obtain a high capacity | capacitance, and can improve charging / discharging efficiency.

  Embodiments of the present invention will be described below with reference to the drawings. A positive electrode active material for a non-aqueous electrolyte secondary battery according to an embodiment of the present invention (hereinafter appropriately referred to as a positive electrode active material) includes lithium (Li), nickel (Ni), and at least part of the composite oxide particles. A coating layer made of an oxide containing at least one coating element of manganese (Mn) is provided, and at least a part of the coating layer includes silicon (Si), aluminum (Al), Ti (titanium), zirconium A surface layer made of an oxide of at least one element of (Zr) is provided.

First, the reason why the positive electrode active material is configured as described above will be described. The positive electrode active material mainly composed of lithium cobalt oxide (LiCoO ₂ ) can realize high charge voltage and high energy density accompanying it, but if the charge / discharge cycle at high capacity is repeated at high charge voltage, the capacity of There is a lot of decline. Since this cause is caused by the surface of the positive electrode active material particles, the necessity of surface treatment of the positive electrode active material has been pointed out.

  Therefore, various surface treatments have been proposed, but the surface is made of a material that can suppress or contribute to the capacity reduction from the viewpoint of eliminating the capacity reduction per volume or weight or minimizing the capacity reduction. By performing the treatment, it is possible to obtain a positive electrode active material that can realize high charge voltage properties and high energy density properties associated therewith, and is excellent in charge / discharge cycle characteristics at high charge voltages.

Accordingly, the inventors of the present application have made a intensive study, and although slightly inferior in the high charge voltage property and the high energy density property associated therewith, the positive electrode active material mainly composed of lithium cobaltate (LiCoO ₂ ) is used as lithium (Li). And providing a coating layer made of an oxide containing at least one of the coating elements of nickel (Ni) and manganese (Mn), has high charging voltage and high energy density associated therewith, and It has been found that a positive electrode active material having a high capacity and excellent charge / discharge cycle characteristics can be obtained under high charge voltage conditions.

  As a method of providing the coating layer on the composite oxide particles, a lithium (Li) compound, a nickel (Ni) compound and / or a manganese (Mn) compound are finely pulverized into fine particles, and the fine particles and the composite oxide particles By dry mixing, fine particles are deposited on the surface of the composite oxide particles, and further fired, so that lithium (Li) and at least one covering element of nickel (Ni) and manganese (Mn) There is a method of providing a coating layer made of an oxide containing a metal oxide on the surface of the composite oxide particles. In addition, a lithium (Li) compound and a nickel (Ni) compound and / or a manganese (Mn) compound are dissolved or mixed in a solvent and deposited on the surface of the composite oxide particles in a wet manner, followed by firing. A coating layer made of an oxide containing lithium (Li) and at least one coating element of nickel (Ni) and manganese (Mn) may be provided on the surface of the composite oxide particle. However, these methods yielded results in which a highly uniform coating could not be achieved.

  Therefore, the inventors of the present application have further studied diligently. As a result, nickel (Ni) and / or manganese (Mn) was deposited as a hydroxide, and this was heated and dehydrated to form a coating layer. It was found that highly uniform coating can be realized. In this deposition treatment, a nickel (Ni) compound and / or a manganese (Mn) compound is dissolved in a water-based solvent system, and then the composite oxide particles are dispersed in the solvent system. The basicity of the dispersion is increased by adding a base to the system, and a hydroxide containing nickel (Ni) and / or manganese (Mn) is precipitated on the surface of the composite oxide particles.

  Furthermore, the inventors of the present application have found that the uniformity of coating on the composite oxide particles can be further improved by performing this deposition treatment in a solvent system mainly composed of water having a pH of 12 or higher. That is, the metal composite oxide particles are dispersed in advance in a solvent system mainly composed of water having a pH of 12 or more, and a nickel (Ni) compound and / or a manganese (Mn) compound is added to the metal composite oxide. A hydroxide containing nickel (Ni) and / or manganese (Mn) is deposited on the surface of the product particles.

  Then, by this deposition treatment, the composite oxide particles coated with a hydroxide containing nickel (Ni) and / or manganese (Mn) are heated and dehydrated to form a coating layer on the surface of the composite oxide particles. . Thereby, the uniformity of the coating on the surface of the composite oxide particles can be improved.

  However, the inventors of the present application show that in the composite oxide particles coated with hydroxide containing nickel (Ni) and / or manganese (Mn), the ratio of nickel (Ni) is increased and the ratio of manganese (Mn) is decreased. Then, in the baking of the precursor to which lithium (Li) was added, the importance of the problem that the sintering between particles easily progressed was found.

  When the sintering between the particles proceeds, the problem described below occurs. In the formation of the positive electrode, it is necessary to increase the input amount of mechanical energy in the pulverization of the particles in order to uniformly mix the particles with the carbon particles as the binder and the conductive agent. Along with this, the positive electrode active material made of composite oxide particles provided with a coating layer is damaged or broken, and the total amount of defects as powder increases.

Note that the breakage or breakage occurs in the form of breakage of the connecting portion between the sintered particles, formation of cracks in the particles themselves, crushing of the particles themselves, peeling of the coating layer, and the like. In particular, in the composite oxide particles provided with the coating layer, the surface shape of the particles is not smooth and has irregularities on the surface as compared with particles such as a positive electrode active material mainly composed of lithium cobaltate (LiCoO ₂ ). There is a tendency. For this reason, when an external force is applied, it is considered that the slip between particles is poor, the external force is easily concentrated locally, and is easily damaged or destroyed.

  As a result, the surface where the coating layer is not provided is exposed. That is, a surface not provided with a coating layer that does not function to improve the charge / discharge cycle characteristics and an active new surface are exposed. Therefore, the high-capacity charge / discharge cycle characteristics deteriorate under high charge voltage conditions. The exposed surface is active and has a high surface energy as is well known. For this reason, the decomposition reaction of the electrolytic solution and the elution activity of the surface are extremely high as compared with the surface formed by normal firing.

  Accordingly, the inventors of the present application have made extensive studies for the purpose of improving the deterioration of the positive electrode function and improving the manufacturing process based on the sintering between particles, and water containing nickel (Ni) and / or manganese (Mn). Further, a hydroxide containing at least one of silicon (Si), aluminum (Al), Ti (titanium), and zirconium (Zr) is further deposited on the surface of the composite oxide particles to which the oxide is deposited. It was found that the progress of sintering can be improved. Along with this, it was found that particle breakage or destruction can be reduced. Further, by providing a surface layer composed of metal oxide fine particles, nickel (Ni) and / or manganese (Mn) constituting the coating layer is prevented from dissolving in the composite oxide particles, and nickel (Ni) and It was found that manganese (Mn) is retained on the surface of the composite oxide particles to increase the coating effect, and as a result, the cycle retention rate is also improved.

  Next, the composite oxide particles, the coating layer, and the surface layer will be described.

[Composite oxide particles]
The composite oxide particles contain at least lithium (Li) and cobalt (Co), and for example, the average composition is preferably represented by Chemical Formula 1 or Chemical Formula 2. By using such composite oxide particles, a high capacity and a high discharge potential can be obtained.

(Chemical formula 1)
_{Li (1 + W) Co (} 1-xy) Ma x Mb y O (2-z)
(In the chemical formula 1, Ma is Bi (bismuth) or Ga (gallium), Mb is vanadium (V), chromium (Cr), boron (B), manganese (Mn), iron (Fe), nickel (Ni), Copper (Cu), zinc (Zn), aluminum (Al), magnesium (Mg), titanium (Ti), zirconium (Zr), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), It is composed of at least one element selected from the group consisting of yttrium (Y) and tungsten (W), and w, x, y, and z are −0.10 ≦ w ≦ 0.10, 0.001 <x < 0.10, 0 ≦ y <0.40, −0.10 ≦ z ≦ 0.20)

(Chemical formula 2)
Li _{(1 + W)} Co _(1-xy) Mc _x Md _y O _(2-z)
(In the chemical formula 2, Mc is Mg (magnesium), Al (aluminum), Ti (titanium), Zr (zirconium), Md is vanadium (V), chromium (Cr), boron (B), manganese (Mn), From iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), yttrium (Y), tungsten (W) It is composed of at least one selected element, and w, x, y, and z are −0.10 ≦ w ≦ 0.10, 0.001 <x <0.10, 0 ≦ y <0.40, −0 .10 ≦ z ≦ 0.20)

  Here, in Chemical Formula 1 and Chemical Formula 2, the range of w is, for example, −0.10 ≦ w ≦ 0.10, more preferably −0.08 ≦ w ≦ 0.08, and still more preferably −0. 06 ≦ w ≦ 0.06. If the value decreases outside this range, the discharge capacity will decrease. Further, if the value is increased outside this range, it diffuses out of the particles and becomes an obstacle to the control of the basicity of the next treatment step, and finally, the harmful effect of promoting gelation during the kneading of the positive electrode paste. Cause.

  The range of x is, for example, 0.001 <x <0.10, 0.002 <x <0.08 is more preferable, and 0.003 <x <0.06 is more preferable. If the value decreases outside this range, the charge / discharge cycle characteristics at a high capacity under high charge voltage conditions may occur when a non-aqueous electrolyte secondary battery is finally produced due to factors in the process of positive electrode production and battery production. It will decline. On the other hand, when the value increases outside this range, the discharge capacity tends to decrease.

The range of y is, for example, 0 ≦ y <0.40, preferably 0 ≦ y <0.30, and more preferably 0 ≦ y <0.20. When it becomes larger than this range, the high charge voltage property of LiCoO ₂ and the high energy density property associated therewith are impaired.

  The range of z is, for example, −0.10 ≦ z ≦ 0.20, more preferably −0.08 ≦ z ≦ 0.18, and still more preferably −0.06 ≦ z ≦ 0.16. When the value decreases outside this range, and when the value increases outside this range, the discharge capacity tends to decrease.

  In the chemical formula 1, it is preferable that the addition amount x of bismuth (Bi) or gallium (Ga) used as Ma is smaller than the addition amount y of Mb in the formula. This is because bismuth (Bi) or gallium (Ga) is harder to dissolve in cobalt lithium oxide than Mb.

  Further, bismuth (Bi) or gallium (Ga) in Chemical Formula 1 and Mg (magnesium), Al (aluminum), Ti (titanium), and Zr (zirconium) in Chemical Formula 2 have a concentration gradient in the composite oxide particles. However, it is preferable that the solid solution is formed so that the concentration becomes substantially uniform.

  The composite oxide particles can be used as starting materials that are usually available as positive electrode active materials, but in some cases, the composite oxide particles may be used after pulverizing the secondary particles using a ball mill or a grinder. it can.

[Coating layer]
The coating layer is provided on at least a part of the composite oxide particles and is made of an oxide containing lithium (Li) and at least one coating element of nickel (Ni) and manganese (Mn). By providing this coating layer, it is possible to realize high charge voltage characteristics and high energy density characteristics associated therewith, and to improve charge / discharge cycle characteristics under high charge voltage conditions.

  The constituent ratio of nickel (Ni) and manganese (Mn) in the coating layer is preferably in the range of 100: 0 to 30:70, and in the range of 100: 0 to 40:60 in terms of molar ratio. Is more preferable. If the amount of manganese (Mn) increases beyond this range, the occlusion of lithium (Li) will decrease, eventually reducing the capacity of the positive electrode active material and increasing the electrical resistance when used in a battery. It is a factor. In addition, the range of the composition ratio of nickel (Ni) and manganese (Mn) is a range showing more effectiveness in suppressing the progress of sintering between particles in the firing of the precursor added with lithium (Li). is there.

  In addition, nickel (Ni) and manganese (Mn) in the oxide of the coating layer are replaced with magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), cobalt (Co), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), tungsten (W), yttrium (Y), zirconium It can be replaced with at least one metal element selected from the group consisting of (Zr).

  Thereby, the stability of the positive electrode active material and the diffusibility of lithium ions can be improved. The substitution amount of the selected metal element is, for example, 40 mol% or less of the total amount of nickel (Ni) and manganese (Mn) of the oxide of the coating layer, preferably 30 mol% or less, more preferably 20 mol%. % Or less. This is because if the substitution amount of the selected metal element is increased beyond this range, the occlusion of lithium (Li) is lowered and the capacity of the positive electrode active material is lowered.

  Further, the amount of the coating layer is, for example, 0.5 mol% or more and 50 mol% or less, preferably 1.0 mol% or more and 40 mol% or less, more preferably, with respect to the number of moles of the composite oxide particle metal. Is 2.0 mol% or more and 30 mol% or less. This is because when the coating weight of the metal oxide exceeds this range, the capacity of the positive electrode active material decreases. This is because when the coating weight of the metal oxide is lower than this range, the stability of the positive electrode active material is lowered.

[Surface layer]
The surface layer is provided on at least a part of the coating layer and is made of an oxide of at least one element selected from silicon (Si), aluminum (Al), Ti (titanium), and zirconium (Zr).

  As metal oxide fine particles comprising an oxide of at least one element of silicon (Si), aluminum (Al), Ti (titanium), and zirconium (Zr) used in the present invention, the primary average particle diameter is It is 1.0 nm or more and 100 nm or less, preferably 2.0 nm or more and 80 nm or less, and more preferably 5.0 nm or more and 50 nm or less. This is because when the primary average particle diameter of the metal oxide fine particles increases beyond this range, the adherence of the metal oxide fine particles to the composite oxide particles provided with the coating layer decreases. Moreover, when the primary average particle diameter of the metal oxide fine particles is lower than this range, it becomes difficult to obtain the sintering suppressing effect between the particles.

  The amount of the surface layer is such that, for example, the metal oxide particles are 0.01 mol% or more and 10 mol% or less, preferably 0.03 mol% or more and 8.0 mol% or less, more preferably 0 with respect to the metal element of the composite oxide particles. 0.05 mol% or more and 5.0 mol% or less. When the amount of the surface layer increases beyond this range, the discharge capacity tends to decrease. Moreover, if the amount of the surface layer is lower than this range, the effect of preventing sintering between particles and the effect of improving the charge / discharge cycle characteristics associated therewith tend to be reduced.

The amount of the surface layer is, for example, as silicon (Si), aluminum (Al), Ti (titanium), zirconium (Zr) as a deposition amount, and silicon (Si) ions per 1 m ² of the surface area of the deposition surface. At least one of aluminum (Al) ion, Ti (titanium) ion, and zirconium (Zr) ion is 1.0 × 10 ⁻⁵ mol or more and 1.0 × 10 ⁻² mol or less. Further, the deposition amount is preferably 3.0 × 10 ⁻⁵ mol or more and 5.0 × 10 ⁻³ mol or less, and more preferably 1.0 × 10 ⁻⁴ mol or more and 1.0 × 10 ⁻³ mol. mol or less. When the amount of the surface layer increases outside this range, the diffusion resistance of lithium ions increases and the capacity of the final positive electrode active material of the present invention decreases. On the other hand, when the amount of the surface layer decreases outside this range, the effect of preventing the sintering between particles and the effect of improving the charge / discharge cycle characteristics associated therewith tend to be reduced.

  The average particle diameter of the positive electrode active material configured as described above is preferably 2.0 μm or more and 50 μm or less. If the average particle size is less than 2.0 μm, it peels off when pressed during positive electrode fabrication, and the surface area of the active material increases, so it is necessary to increase the amount of conductive agent and binder added, and the unit weight This is because the per-energy density tends to decrease. On the other hand, if the average particle size exceeds 50 μm, the particles tend to penetrate the separator and cause a short circuit.

[Method for producing positive electrode active material]
Next, the manufacturing method of the positive electrode active material by one Embodiment of this invention is demonstrated. Hereinafter, the first manufacturing method and the second manufacturing method will be described.

<First manufacturing method>
In a first method for producing a positive electrode active material according to an embodiment of the present invention, a layer made of a hydroxide containing nickel (Ni) and / or manganese (Mn) is formed on at least a part of the composite oxide particles. A first step of forming a layer made of a hydroxide containing at least one of silicon (Si), aluminum (Al), Ti (titanium), and zirconium (Zr) on at least a part of the composite oxide particles; , After forming a hydroxide containing at least one of silicon (Si), aluminum (Al), Ti (titanium), and zirconium (Zr), heat treatment is performed on at least a part of the composite oxide particles. A coating layer made of an oxide containing lithium (Li) and at least one coating element of nickel (Ni) and manganese (Mn), and silicon (Si), Aluminum (Al), Ti (titanium) can be classified a second step of forming a surface layer made of oxide containing at least one of zirconium (Zr), to the.

(First step)
In the first step, a hydroxide containing nickel (Ni) and / or manganese (Mn) and water containing at least one of silicon (Si), aluminum (Al), Ti (titanium), and zirconium (Zr). An oxide deposition process is performed. In the first step, for example, first, the composite oxide particles are dispersed in a solvent system mainly composed of water in which a nickel (Ni) compound and / or a manganese (Mn) compound is dissolved. The basicity of the dispersion is increased by adding a base and the like, and a hydroxide containing nickel (Ni) and / or manganese (Mn) is precipitated on the surface of the composite oxide particles. The composite oxide particles are dispersed in a solvent mainly composed of basic water, and then a nickel (Ni) compound and / or a manganese (Mn) compound is added to the aqueous solution to obtain nickel (Ni ) And / or a hydroxide containing manganese (Mn) may be deposited.

  As raw materials for the deposition treatment of hydroxide containing nickel (Ni), nickel compounds include nickel hydroxide, nickel carbonate, nickel nitrate, nickel fluoride, nickel chloride, nickel bromide, nickel iodide, perchloric acid Inorganic compounds such as nickel, nickel bromate, nickel iodate, nickel oxide, nickel peroxide, nickel sulfide, nickel sulfate, nickel hydrogen sulfate, nickel nitride, nickel nitrite, nickel phosphate, nickel thiocyanate, or Organic compounds such as nickel oxide and nickel acetate can be used, and one or more of these may be used.

  In addition, as a raw material for the deposition treatment of hydroxide containing manganese (Mn), manganese compounds include manganese hydroxide, manganese carbonate, manganese nitrate, manganese fluoride, manganese chloride, manganese bromide, manganese iodide, chlorine Manganese oxide, manganese perchlorate, manganese bromate, manganese iodate, manganese oxide, manganese phosphinate, manganese sulfide, manganese hydrogen sulfide, manganese nitrate, manganese hydrogen sulfate, manganese thiocyanate, manganese nitrite, manganese phosphate, phosphorus An inorganic compound such as manganese dihydrogen oxide and manganese hydrogen carbonate, or an organic compound such as manganese oxalate and manganese acetate can be used, and one or more of these may be used.

  Next, silicon (Si), aluminum (Al), Ti (titanium), zirconium (Zr) is formed on the surface of the composite oxide particles coated with hydroxide containing nickel (Ni) and / or manganese (Mn). A hydroxide containing at least one of the above is deposited. The deposition of a hydroxide containing at least one of silicon (Si), aluminum (Al), Ti (titanium), and zirconium (Zr) is performed by the hydroxide containing nickel (Ni) and / or manganese (Mn). It can be performed in the same manner as the deposition. That is, the composite oxide particles coated with a hydroxide containing nickel (Ni) and / or manganese (Mn) are at least one of silicon (Si), aluminum (Al), Ti (titanium), and zirconium (Zr). Disperse in a solvent system mainly composed of water in which a compound containing a seed is dissolved, and increase the basicity of the dispersion system by adding a base to the dispersion system, so that silicon (Si), aluminum (Al), Ti ( A hydroxide containing at least one of titanium) and zirconium (Zr) is deposited. The composite oxide particles coated with a hydroxide containing nickel (Ni) and / or manganese (Mn) are dispersed in a solvent mainly composed of basic water, and then silicon (Si ), Aluminum (Al), Ti (titanium), and a compound containing at least one of zirconium (Zr) may be added to precipitate the hydroxide.

  As a raw material for the deposition treatment of a hydroxide containing at least one of silicon (Si), aluminum (Al), Ti (titanium), and zirconium (Zr), for example, the following compounds can be used.

  As the silicon compound, hexafluorosilicate or ammonium hexafluorosilicate can be used, and one or more of these may be used.

  As the aluminum compound, sodium aluminate, potassium aluminate, aluminum oxalate, aluminum nitrate, aluminum sulfate and aluminum phosphate can be used, and one or more of these may be used.

  As the titanium compound, titanium trichloride, titanium tetrachloride and titanium sulfate can be used, and one or more of these may be used.

  As the zirconium compound, zirconium oxychloride octahydrate and zirconium nitrate can be used, and one or more of these may be used.

  In the first step, the pH of the above-described solvent system mainly composed of water is, for example, pH 12 or more, preferably pH 13 or more, and more preferably pH 14 or more. The higher the pH value of the water-based solvent system described above, the better the uniformity of the deposition of hydroxide containing nickel (Ni) and / or manganese (Mn), and the higher the reaction accuracy, There are advantages in improving productivity and quality by shortening the processing time. Further, the pH of the solvent system mainly composed of water is determined by the balance with the cost of the alkali used.

  The temperature of the treatment dispersion is, for example, 40 ° C. or higher, preferably 60 ° C. or higher, and more preferably 80 ° C. or higher. The higher the value of the temperature of the treatment dispersion, the better the uniformity of the deposition of the hydroxide containing nickel (Ni) and / or manganese (Mn), the higher the reaction rate, and the shorter the production time. There is an advantage of improvement in quality and quality. Although it is determined in consideration of the cost and productivity of the equipment, it can be performed at 100 ° C. or higher using an autoclave, and production by shortening the processing time by improving the uniformity of deposition and improving the reaction rate. From the point of view, it can be recommended.

  Further, in the first step, for example, in a solvent system mainly composed of water, a hydroxide containing nickel (Ni) and / or manganese (Mn) is formed on the surface of the composite oxide particles, and then water is added thereto. It is possible to remove the main solvent system and deposit a hydroxide containing at least one of silicon (Si), aluminum (Al), Ti (titanium), and zirconium (Zr). It is not limited to. For example, after forming a hydroxide containing nickel (Ni) and / or manganese (Mn) on the surface of the composite oxide particle, it is not separated from the water-based solvent system as it is. By adding a compound comprising silicon (Si), aluminum (Al), Ti (titanium), zirconium (Zr), at least silicon (Si), aluminum (Al), Ti (titanium), zirconium (Zr) It is also possible to deposit a hydroxide containing one species.

  Furthermore, the pH of a solvent system mainly composed of water can be reached by dissolving an alkali in the solvent system mainly composed of water. Examples of the alkali include lithium hydroxide, sodium hydroxide and potassium hydroxide, and mixtures thereof. Although these alkalis can be used as appropriate, it is excellent to use lithium hydroxide from the viewpoint of the purity and performance of the positive electrode active material according to one embodiment finally obtained. The advantage of using lithium hydroxide is that when the composite oxide particles in which a hydroxide containing nickel (Ni) and / or manganese (Mn) is formed are taken out from a solvent system mainly composed of water, This is because the amount of lithium in the positive electrode active material according to an embodiment finally obtained can be controlled by controlling the amount of the dispersion medium made of a solvent mainly composed of.

(Second step)
In the second step, the composite oxide particles deposited in the first step are separated from the solvent system mainly composed of water, and then the hydroxide is dehydrated by heat treatment, whereby the composite oxide particles And a coating layer made of an oxide containing lithium (Li) and at least one of nickel (Ni) and manganese (Mn), and silicon (Si), aluminum (Al), Ti (titanium) ) And a surface layer made of an oxide containing at least one of zirconium (Zr). Here, the heat treatment is preferably performed at a temperature of, for example, about 300 ° C. to 1000 ° C. in an oxidizing atmosphere such as air or pure oxygen. At this time, a hydroxide containing nickel (Ni) and / or manganese (Mn) and at least one of silicon (Si), aluminum (Al), Ti (titanium) and zirconium (Zr) Is applied, sintering between particles is suppressed, and binding between particles is suppressed.

  In addition, after separating the composite oxide particles subjected to the deposition treatment in the first step from the solvent system, the composite oxide particles are impregnated with an aqueous solution of a lithium compound to adjust the amount of lithium if necessary. Thereafter, heat treatment may be performed.

  Examples of lithium compounds include lithium hydroxide, lithium carbonate, lithium nitrate, lithium fluoride, lithium chloride, lithium bromide, lithium iodide, lithium chlorate, lithium perchlorate, lithium bromate, lithium iodate, and oxidation. Inorganic compounds such as lithium, lithium peroxide, lithium sulfide, lithium hydrogen sulfide, lithium sulfate, lithium hydrogen sulfate, lithium nitride, lithium azide, lithium nitrite, lithium phosphate, lithium dihydrogen phosphate, lithium hydrogen carbonate, Alternatively, an organic compound such as methyl lithium, vinyl lithium, isopropyl lithium, butyl lithium, phenyl lithium, lithium oxalate, or lithium acetate can be used.

  Further, after firing, the particle size may be adjusted by light pulverization or classification operation, if necessary.

<Second production method>
In a second method for producing a positive electrode active material according to an embodiment of the present invention, a layer made of a hydroxide containing nickel (Ni) and / or manganese (Mn) is formed on at least a part of the composite oxide particles, A first step of drying and at least a part of the dried composite oxide particles are made of an oxide containing at least one of silicon (Si), aluminum (Al), Ti (titanium), and zirconium (Zr). The second step of coating the metal oxide fine particles and the heat treatment after coating with the metal oxide particles, lithium (Li), nickel (Ni) and at least part of the composite oxide particles A coating layer made of an oxide containing at least one of the covering elements of manganese (Mn), and silicon (Si), aluminum (Al), Ti (titanium), and zirconium A third step of forming a surface layer made of oxide containing at least one of (Zr), can be divided into.

(First step)
In the first step, a hydroxide containing nickel (Ni) and / or manganese (Mn) is applied to the surface of the composite oxide particles. For the hydroxide deposition treatment, the same materials and methods as in the first production method can be used. Next, the composite oxide particles coated with hydroxide are separated from the solvent system mainly composed of water, and then dried in an environment of 120 ° C., for example.

(Second step)
In the second step, the composite oxide particles to which the hydroxide is deposited in the first step include at least one of silicon (Si), aluminum (Al), Ti (titanium), and zirconium (Zr). Metal oxide fine particles made of an oxide are added and mixed by dry stirring to coat the surface of the composite oxide particles with the metal oxide particles.

(Third step)
In the third step, the hydroxide is dehydrated by heat-treating the composite oxide particles coated with metal oxide particles after the hydroxide is deposited, and lithium (Li) is deposited on the surface of the composite oxide particles. And a coating layer made of an oxide containing at least one coating element of nickel (Ni) and manganese (Mn), and silicon (Si), aluminum (Al), Ti (titanium), zirconium (Zr) A surface layer made of an oxide containing at least one kind is formed. Here, the heat treatment is preferably performed at a temperature of, for example, about 300 ° C. to 1000 ° C. in an oxidizing atmosphere such as air or pure oxygen. At this time, a metal oxide containing at least one of silicon (Si), aluminum (Al), Ti (titanium), and zirconium (Zr) in a hydroxide containing nickel (Ni) and / or manganese (Mn). Since the particles are deposited, sintering between the particles is suppressed, and binding between the particles is suppressed.

  As in the first production method, the particle size may be adjusted by light pulverization or classification operation as necessary after firing.

  By using such a positive electrode active material, it is possible to obtain excellent stability under a high charging voltage, and accordingly, energy density can be improved, and high charge / discharge capacity can be obtained. In addition, a nonaqueous electrolyte secondary battery excellent in charge / discharge cycle characteristics at a high capacity can be obtained under a high charge voltage.

  Next, a non-aqueous electrolyte secondary battery using the positive electrode active material according to one embodiment of the present invention described above will be described.

(1) First Example of Nonaqueous Electrolyte Secondary Battery (1-1) Configuration of Nonaqueous Electrolyte Secondary Battery FIG. 1 is a nonaqueous electrolyte secondary battery using a positive electrode active material according to an embodiment of the present invention. The cross-sectional structure of is shown.

  In this secondary battery, the open circuit voltage in a fully charged state per pair of positive electrode and negative electrode is, for example, 4.25V or more and 4.65V or less.

  This secondary battery is a so-called cylindrical type, and is a wound electrode in which a strip-shaped positive electrode 2 and a strip-shaped negative electrode 3 are wound via a separator 4 inside a substantially hollow cylindrical battery can 1. It has a body 20.

  The battery can 1 is made of, for example, iron (Fe) plated with nickel (Ni), and has one end closed and the other end open. Inside the battery can 1, a pair of insulating plates 5 and 6 are arranged perpendicular to the winding peripheral surface so as to sandwich the winding electrode body 20.

  At the open end of the battery can 1, a battery lid 7, a safety valve mechanism 8 and a thermal resistance element (PTC element) 9 provided inside the battery lid 7 are interposed via a gasket 10. It is attached by caulking, and the inside of the battery can 1 is sealed. The battery lid 7 is made of, for example, the same material as the battery can 1. The safety valve mechanism 8 is electrically connected to the battery lid 7 via a heat sensitive resistance element 9, and the disk plate 11 is reversed when the internal pressure of the battery becomes a certain level or more due to internal short circuit or external heating. Thus, the electrical connection between the battery lid 7 and the wound electrode body 20 is cut off. When the temperature rises, the heat sensitive resistance element 9 limits the current by increasing the resistance value and prevents abnormal heat generation due to a large current. The gasket 10 is made of, for example, an insulating material, and asphalt is applied to the surface.

  The wound electrode body 20 is wound around, for example, the center pin 12. A positive electrode lead 13 made of, for example, aluminum (Al) or the like is connected to the positive electrode 2 of the spirally wound electrode body 20, and a negative electrode lead 14 made of, for example, nickel (Ni) or the like is connected to the negative electrode 3. The positive electrode lead 13 is electrically connected to the battery cover 7 by being welded to the safety valve mechanism 8, and the negative electrode lead 14 is welded and electrically connected to the battery can 1.

[Positive electrode]
FIG. 2 shows an enlarged part of the spirally wound electrode body 20 shown in FIG. As shown in FIG. 2, the positive electrode 2 includes, for example, a positive electrode current collector 2A having a pair of opposed surfaces, and a positive electrode mixture layer 2B provided on both surfaces of the positive electrode current collector 2A. In addition, you may make it have the area | region where the positive mix layer 2B was provided only in the single side | surface of 2 A of positive electrode collectors. The positive electrode current collector 2A is made of, for example, a metal foil such as an aluminum (Al) foil. The positive electrode mixture layer 2B includes, for example, a positive electrode active material, and may include a conductive agent such as graphite and a binder such as polyvinylidene fluoride as necessary. As the positive electrode active material, the positive electrode active material according to the above-described embodiment can be used.

[Negative electrode]
As shown in FIG. 2, the negative electrode 3 includes, for example, a negative electrode current collector 3A having a pair of opposed surfaces, and a negative electrode mixture layer 3B provided on both surfaces of the negative electrode current collector 3A. In addition, you may make it have the area | region in which the negative mix layer 3B was provided only in the single side | surface of 3 A of negative electrode collectors. The negative electrode current collector 3A is made of a metal foil such as a copper (Cu) foil. The negative electrode mixture layer 3B includes, for example, a negative electrode active material, and may include a binder such as polyvinylidene fluoride as necessary.

The negative electrode active material includes a negative electrode material capable of inserting and extracting lithium (Li) (hereinafter referred to as a negative electrode material capable of inserting and extracting lithium (Li) as appropriate). Examples of negative electrode materials capable of inserting and extracting lithium (Li) include carbon materials, metal compounds, oxides, sulfides, lithium nitrides such as LiN ₃ , lithium metals, metals that form alloys with lithium, and high Examples include molecular materials.

  Examples of the carbon material include non-graphitizable carbon, graphitizable carbon, graphite, pyrolytic carbons, cokes, glassy carbons, organic polymer compound fired bodies, carbon fibers, and activated carbon. Among these, examples of coke include pitch coke, needle coke, and petroleum coke. An organic polymer compound fired body is a carbonized material obtained by firing a polymer material such as a phenol resin or a furan resin at an appropriate temperature, and part of it is non-graphitizable carbon or graphitizable carbon. Some are classified as: Examples of the polymer material include polyacetylene and polypyrrole.

  Among such negative electrode materials capable of inserting and extracting lithium (Li), those having a charge / discharge potential relatively close to lithium metal are preferable. This is because the lower the charge / discharge potential of the negative electrode 3, the easier it is to increase the energy density of the battery. Among these, a carbon material is preferable because a change in crystal structure that occurs during charge / discharge is very small, a high charge / discharge capacity can be obtained, and good cycle characteristics can be obtained. In particular, graphite is preferable because it has a high electrochemical equivalent and can provide a high energy density. Moreover, non-graphitizable carbon is preferable because excellent cycle characteristics can be obtained.

  Examples of the negative electrode material capable of inserting and extracting lithium (Li) include lithium metal alone, a metal element or metalloid element simple substance, alloy or compound capable of forming an alloy with lithium (Li). These are preferable because a high energy density can be obtained, and in particular, when used together with a carbon material, a high energy density can be obtained and excellent cycle characteristics can be obtained, and therefore, it is more preferable. Note that in this specification, alloys include those composed of one or more metal elements and one or more metalloid elements in addition to those composed of two or more metal elements. The structures include solid solutions, eutectics (eutectic mixtures), intermetallic compounds, or those in which two or more of them coexist.

Examples of such metal elements or metalloid elements include tin (Sn), lead (Pb), aluminum (Al), indium (In), silicon (Si), zinc (Zn), antimony (Sb), and bismuth. (Bi), cadmium (Cd), magnesium (Mg), boron (B), gallium (Ga), germanium (Ge), arsenic (As), silver (Ag), zirconium (Zr), yttrium (Y) or hafnium (Hf). These alloys or compounds, for example, those represented by the chemical formula Me _s Mf _t Li _u or a chemical formula Me _p Mg _q Mh _r,. In these chemical formulas, Me represents at least one of a metal element and a metalloid element capable of forming an alloy with lithium, Mf represents at least one of a metal element and a metalloid element other than lithium and Me, Mg represents at least one nonmetallic element, and Mh represents at least one metal element other than Me and metalloid elements. The values of s, t, u, p, q, and r are s> 0, t ≧ 0, u ≧ 0, p> 0, q> 0, and r ≧ 0, respectively.

  Among these, a simple substance, alloy or compound of Group 4B metal element or semimetal element in the short-period type periodic table is preferable, and silicon (Si) or tin (Sn), or an alloy or compound thereof is particularly preferable. These may be crystalline or amorphous.

In addition, inorganic compounds wo that do not contain lithium (Li), such as MnO ₂ , V ₂ O ₅ , V ₆ O ₁₃ , NiS, and MoS, can also be used.

[Electrolyte]
As the electrolytic solution, a nonaqueous electrolytic solution in which an electrolyte salt is dissolved in a nonaqueous solvent can be used. As the non-aqueous solvent, for example, it is preferable to contain at least one of ethylene carbonate and propylene carbonate. This is because the cycle characteristics can be improved. In particular, it is preferable to mix and contain ethylene carbonate and propylene carbonate because cycle characteristics can be further improved. The nonaqueous solvent preferably contains at least one of chain carbonates such as diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, or methyl propyl carbonate. This is because the cycle characteristics can be further improved.

  The non-aqueous solvent preferably further contains at least one of 2,4-difluoroanisole and vinylene carbonate. This is because 2,4-difluoroanisole can improve discharge capacity, and vinylene carbonate can further improve cycle characteristics. In particular, it is more preferable that they are mixed and contained because both the discharge capacity and the cycle characteristics can be improved.

  Non-aqueous solvents further include butylene carbonate, γ-butyrolactone, γ-valerolactone, those in which part or all of the hydrogen groups of these compounds are substituted with fluorine groups, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyl Tetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, methyl acetate, methyl propionate, acetonitrile, glutaronitrile, adiponitrile, methoxyacetonitrile, 3-methoxypropironitrile, N, N-dimethylformamide N-methylpyrrolidinone, N-methyloxazolidinone, N, N-dimethylimidazolidinone, nitromethane, nitroethane, sulfolane, dimethyl sulfoxide, or trimethyl phosphate may be included. Yes.

  Depending on the electrode to be combined, the reversibility of the electrode reaction may be improved by using a material in which part or all of the hydrogen atoms of the substance contained in the non-aqueous solvent group are substituted with fluorine atoms. Therefore, these substances can be used as appropriate.

Examples of the lithium salt that is an electrolyte salt include LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiClO ₄ , LiB (C ₆ H ₅ ) ₄ , LiCH ₃ SO ₃ , LiCF ₃ SO ₃ , LiN (SO ₂ CF ₃ ) _2. , LiC (SO ₂ CF ₃ ) ₃ , LiAlCl ₄ , LiSiF ₆ , LiCl, LiBF ₂ (ox), LiBOB, or LiBr are suitable, and any one or more of these are used in combination. be able to. Among them, LiPF ₆ is preferable because it can obtain high ion conductivity and can improve cycle characteristics.

[Separator]
Below, the separator material which can be utilized for one Embodiment is demonstrated. As a separator material, it is possible to use those used in conventional batteries. Among them, it is particularly preferable to use a polyolefin microporous film that is excellent in short-circuit preventing effect and can improve battery safety by a shutdown effect. For example, a microporous film made of polyethylene or polypropylene resin is preferable.

  Further, as the separator material, it is more preferable to use a laminate or mixture of polyethylene having a lower shutdown temperature and polypropylene having excellent oxidation resistance from the viewpoint of achieving both shutdown performance and float characteristics.

(1-2) Manufacturing Method of Nonaqueous Electrolyte Secondary Battery Next, a manufacturing method of the nonaqueous electrolyte secondary battery will be described. Hereinafter, a method for manufacturing a nonaqueous electrolyte secondary battery will be described by taking a cylindrical nonaqueous electrolyte secondary battery as an example.

  The positive electrode 2 is produced as described below. First, for example, a positive electrode active material, a conductive agent, and a binder are mixed to prepare a positive electrode mixture, and this positive electrode mixture is dispersed in a solvent such as N-methyl-2-pyrrolidone to form a positive electrode mixture. Use slurry.

  Next, after applying this positive electrode mixture slurry to the positive electrode current collector 2A and drying the solvent, the positive electrode mixture layer 2B is formed by compression molding with a roll press or the like, and the positive electrode 2 is produced.

  The negative electrode 3 is produced as described below. First, for example, a negative electrode active material and a binder are mixed to prepare a negative electrode mixture, and the negative electrode mixture is dispersed in a solvent such as N-methyl-2-pyrrolidone to obtain a negative electrode mixture slurry.

  Next, after applying this negative electrode mixture slurry to the negative electrode current collector 3A and drying the solvent, the negative electrode mixture layer 3B is formed by compression molding using a roll press or the like, and the negative electrode 3 is produced.

  Moreover, the negative electrode mixture layer 3B may be formed by, for example, a gas phase method, a liquid phase method, or a firing method, or a combination of two or more thereof. As the vapor phase method, for example, a physical deposition method or a chemical deposition method can be used. Specifically, a vacuum deposition method, a sputtering method, an ion plating method, a laser ablation method, a thermal CVD (Chemical Vapor Deposition), or the like. A chemical vapor deposition method) or a plasma CVD method can be used. As the liquid phase method, a known method such as electrolytic plating or electroless plating can be used. A known method can also be used for the firing method, and for example, an atmosphere firing method, a reaction firing method, or a hot press firing method can be used.

  Next, the positive electrode lead 13 is attached to the positive electrode current collector 2A by welding or the like, and the negative electrode lead 14 is attached to the negative electrode current collector 3A by welding or the like. Next, the positive electrode 2 and the negative electrode 3 are wound through the separator 4, and the tip of the positive electrode lead 13 is welded to the safety valve mechanism 8, and the tip of the negative electrode lead 14 is welded to the battery can 1. The rotated positive electrode 2 and negative electrode 3 are sandwiched between a pair of insulating plates 5 and 6 and stored in the battery can 1.

  Next, an electrolytic solution is injected into the battery can 1 and the separator 4 is impregnated with the electrolytic solution. Next, the battery lid 7, the safety valve mechanism 8, and the heat sensitive resistance element 9 are fixed to the opening end of the battery can 1 by caulking through the gasket 10. Thus, a nonaqueous electrolyte secondary battery is produced.

(2) Second Example of Nonaqueous Electrolyte Secondary Battery (2-1) Configuration of Nonaqueous Electrolyte Secondary Battery FIG. 3 is a nonaqueous electrolyte secondary battery using a positive electrode active material according to an embodiment of the present invention. The structure of is shown. As shown in FIG. 3, this non-aqueous electrolyte secondary battery is sealed by housing the battery element 30 in an exterior material 37 made of a moisture-proof laminate film and welding the periphery of the battery element 30. The battery element 30 is provided with a positive electrode lead 32 and a negative electrode lead 33, and these leads are sandwiched between outer packaging materials 37 and pulled out to the outside. A resin piece 34 and a resin piece 35 are coated on both surfaces of the positive electrode lead 32 and the negative electrode lead 33 in order to improve the adhesion to the exterior material 37.

[Exterior material]
The packaging material 37 has, for example, a stacked structure in which an adhesive layer, a metal layer, and a surface protective layer are sequentially stacked. The adhesive layer is made of a polymer film. Examples of the material constituting the polymer film include polypropylene (PP), polyethylene (PE), unstretched polypropylene (CPP), linear low density polyethylene (LLDPE), and low density. Examples thereof include polyethylene (LDPE). The metal layer is made of metal foil, and examples of the material constituting the metal foil include aluminum (Al). Moreover, as a material which comprises metal foil, it is also possible to use metals other than aluminum (Al), for example. Examples of the material constituting the surface protective layer include nylon (Ny) and polyethylene terephthalate (PET). The surface on the adhesive layer side is a storage surface on the side where the battery element 30 is stored.

[Battery element]
For example, as shown in FIG. 4, the battery element 30 includes a strip-shaped negative electrode 43 provided with a gel electrolyte layer 45 on both sides, a separator 44, and a strip-shaped positive electrode 42 provided with a gel electrolyte layer 45 on both sides. The battery element 30 is a wound type battery element 30 that is formed by laminating the separator 44 and wound in the longitudinal direction.

  The positive electrode 42 includes a strip-shaped positive electrode current collector 42A and a positive electrode mixture layer 42B formed on both surfaces of the positive electrode current collector 42A.

  One end of the positive electrode 42 in the longitudinal direction is provided with a positive electrode lead 32 connected by, for example, spot welding or ultrasonic welding. As a material of the positive electrode lead 32, for example, a metal such as aluminum can be used.

  The negative electrode 43 includes a strip-shaped negative electrode current collector 43A and a negative electrode mixture layer 43B formed on both surfaces of the negative electrode current collector 43A.

  Similarly to the positive electrode 42, the negative electrode lead 33 connected by, for example, spot welding or ultrasonic welding is also provided at one end portion of the negative electrode 43 in the longitudinal direction. As a material of the negative electrode lead 33, for example, copper (Cu), nickel (Ni) or the like can be used.

  The positive electrode current collector 42A, the positive electrode mixture layer 42B, the negative electrode current collector 43A, and the negative electrode mixture layer 43B are the same as in the first example.

  The gel electrolyte layer 45 includes an electrolytic solution and a polymer compound serving as a holding body that holds the electrolytic solution, and has a so-called gel shape. The gel electrolyte layer 45 is preferable because it can obtain high ionic conductivity and prevent battery leakage. The configuration of the electrolytic solution (that is, the liquid solvent and the electrolyte salt) is the same as that in the first embodiment.

  Examples of the polymer compound include polyacrylonitrile, polyvinylidene fluoride, a copolymer of vinylidene fluoride and hexafluoropropylene, polytetrafluoroethylene, polyhexafluoropropylene, polyethylene oxide, polypropylene oxide, polyphosphazene, and polysiloxane. , Polyvinyl acetate, polyvinyl alcohol, polymethyl methacrylate, polyacrylic acid, polymethacrylic acid, styrene-butadiene rubber, nitrile-butadiene rubber, polystyrene or polycarbonate. In particular, from the viewpoint of electrochemical stability, polyacrylonitrile, polyvinylidene fluoride, polyhexafluoropropylene, or polyethylene oxide is preferable.

(2-2) Method for Producing Nonaqueous Electrolyte Secondary Battery Next, a method for producing a nonaqueous electrolyte secondary battery using a positive electrode active material according to an embodiment of the present invention will be described. First, a precursor solution containing a solvent, an electrolyte salt, a polymer compound, and a mixed solvent is applied to each of the positive electrode 42 and the negative electrode 43, and the mixed solvent is volatilized to form the gel electrolyte layer 45. The positive lead 32 is attached to the end of the positive current collector in advance by welding, and the negative lead 33 is attached to the end of the negative current collector 43A by welding.

  Next, the positive electrode 42 and the negative electrode 43 on which the gel electrolyte layer 45 is formed are laminated through a separator 44 to form a laminated body, and then the laminated body is wound in the longitudinal direction to form a wound battery element. 30 is formed.

  Next, a recess 36 is formed by deep-drawing an exterior material 37 made of a laminate film, the battery element 30 is inserted into the recess 36, and an unprocessed portion of the exterior material 37 is folded back to the upper portion of the recess 36. The outer peripheral part of is thermally welded and sealed. Thus, a nonaqueous electrolyte secondary battery is produced.

Specific embodiments of the present invention will be described below with reference to examples, but the present invention is not limited thereto. Moreover, the following are used for the oxide particle which comprises the surface layer used in the following Examples.
Silicon oxide fine particles: Aerosil 200, manufactured by Nippon Aerosil Co., Ltd., average primary particle diameter (catalog value) of about 12 nm
Aluminum oxide fine particles: AEROXIDE Alu C, manufactured by Degussa, average primary particle size (catalog value) of about 13 nm
Zirconium oxide fine particles: NanoTek ZrO _2, Adachi New Industrial Co., Ltd., average primary particle size (catalog value) about 20~30nm
Titanium oxide fine particles: AEROXIDE TiO ₂ P25, manufactured by Nippon Aerosil Co., Ltd., average primary particle diameter (catalog value) of about 21 nm

<Sample 1-1 to Sample 1-27>
In Example 1, a non-aqueous electrolyte secondary battery is manufactured using a positive electrode active material using a composite oxide prepared by dissolving gallium (Ga) in lithium cobaltate.

<Sample 1-1>
First, 38.1 parts by weight of lithium carbonate (Li ₂ CO ₃ ), 117.7 parts by weight of cobalt carbonate (CoCO ₃ ), and gallium nitrate (Ga (NO ₃ ) ₃ .9H ₂ O) 4.2 Thoroughly mix the parts by weight with a ball mill. The mixture was then calcined in air at 650 ° C. for 5 hours, and further kept in air at 950 ° C. for 20 hours, and then cooled to 150 ° C. at 7 ° C./min. Next, it was taken out at room temperature and pulverized to produce composite oxide particles. The average particle diameter of this composite oxide particle measured by a laser scattering method was 12 μm, and the average chemical composition analysis value was Li _1.03 Co _0.99 Ga _0.01 O _2.02 .

20 parts by weight of such composite oxide particles were stirred and dispersed in 300 parts by weight of pure water at 80 ° C. for 1 hour. Thereto, and nickel nitrate _{(Ni (NO 3) 2 ·} 6H 2 O) 1.60 parts by weight of commercially available reagents, manganese nitrate commercial reagents and _{(Mn (NO 3) 2 ·} 6H 2 O) 1.65 parts by weight Further, 2N LiOH aqueous solution was added to pH 13 over 30 minutes, followed by stirring and dispersing at 80 ° C. for 3 hours, followed by cooling.

Next, the dispersion was washed by filtration and dried at 120 ° C. The analysis result of the metal mole content ratio of the composite oxide particles having a coating layer formed on the obtained surface was Li _1.00 Co _0.95 Ga _0.01 Ni _0.02 Mn _0.02 . By adding 0.01 parts by weight of silicon oxide fine particles to 10 parts by weight of the obtained composite oxide particles having a coating layer and performing dry stirring and mixing, silicon oxide is formed on the surface of the composite oxide particles on which the coating layer is formed. A precursor sample having good fluidity was prepared by coating fine particles to form a surface layer.

  In order to adjust the amount of lithium, this precursor sample was impregnated with 2 parts by weight of a 2N LiOH aqueous solution and uniformly mixed and dried to obtain a calcined precursor. The calcined precursor was heated at a rate of 5 ° C./min using an electric furnace, held at 950 ° C. for 5 hours, and then cooled to 150 ° C. at 7 ° C./min to obtain a positive electrode active material.

  Using the above positive electrode active material, a cylindrical secondary battery was produced as described below.

  First, 86 mol% of the prepared positive electrode active material powder, 10 mol% of graphite as a conductive agent, and 4 mol% of polyvinylidene fluoride (PVdF) as a binder are mixed, and N-methyl-2-pyrrolidone (NMP) as a solvent is mixed. Then, it was applied to both sides of a positive electrode current collector made of a strip-shaped aluminum foil having a thickness of 20 μm, dried, and compression-molded by a roller press to form a positive electrode mixture layer to produce a positive electrode. At that time, the positive electrode active material powder was sufficiently pulverized by a pulverizer so as to pass through a 70 μm aperture sieve. Moreover, the space | gap of the positive mix layer was adjusted so that it might become 26% by volume ratio. Next, a positive electrode lead made of aluminum was attached to the positive electrode current collector.

  Further, 90 mol% of artificial graphite powder as a negative electrode active material and 10 mol% of polyvinylidene fluoride as a binder were mixed and dispersed in N-methyl-2-pyrrolidone as a solvent, and then from a 10 μm-thick strip copper foil The negative electrode current collector was coated on both sides and dried, and compression molded with a roller press to form a negative electrode mixture layer to produce a negative electrode. Next, a negative electrode lead made of nickel was attached to the negative electrode current collector.

  The belt-like positive electrode and the belt-like negative electrode produced as described above were laminated via a separator made of a porous polyolefin film and wound many times to produce a spiral wound electrode body. Next, this wound electrode body was accommodated in an iron battery can, and a pair of insulating plates were disposed on both the upper and lower surfaces of the wound electrode body. Next, the positive electrode lead is led out from the positive electrode current collector and welded to a safety valve mechanism that ensures electrical communication with the battery lid, and the negative electrode lead is led out from the negative electrode current collector and welded to the bottom of the battery can did.

Thereafter, an electrolytic solution was injected into the battery can. As the electrolytic solution, a solution obtained by dissolving LiPF ₆ as an electrolyte salt to 1.0 mol / l in a solvent in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 1: 1 was used. Further, the battery can was caulked through a gasket to fix the safety valve mechanism, the heat sensitive resistance element, and the battery lid, and a cylindrical secondary battery having an outer diameter of 18 mm and a height of 65 mm was obtained.

<Sample 1-2>
20 parts by weight of the composite oxide particles prepared in Sample 1-1 were stirred and dispersed in 300 parts by weight of a 2N LiOH aqueous solution at 80 ° C. for 2 hours. Next, 1.60 parts by weight of nickel nitrate (Ni (NO ₃ ) ₂ .6H ₂ O) as a commercially available reagent and 1.65 parts by weight of manganese nitrate (Mn (NO ₃ ) ₂ .6H ₂ O) as a commercially available reagent Was added to the solution in which the above composite oxide was dispersed over 30 minutes, and then stirred and dispersed for 3 hours and allowed to cool.

  Next, the dispersion was washed by filtration and dried at 120 ° C. The composite oxide having a coating layer formed by adding 0.02 part by weight of aluminum oxide fine particles to 10 parts by weight of the composite oxide particles having a coating layer formed on the surface and performing dry stirring and mixing. A precursor sample having good fluidity was prepared by coating the surface of the particles with aluminum oxide fine particles to form a surface layer. This precursor sample was heated at a rate of 5 ° C. per minute using an electric furnace, held at 950 ° C. for 5 hours, and then cooled to 150 ° C. at 77 ° C. per minute to obtain a positive electrode active material. Other than this, a cylindrical secondary battery was fabricated in the same manner as Sample 1-1.

<Sample 1-3>
A cylindrical secondary battery was produced in the same manner as Sample 1-2, except that a portion of the strip-like positive electrode produced by compression with a roller press was collected and the compression was further repeated twice with the roller press under the same conditions. did.

<Sample 1-4>
By adding 0.01 parts by weight of zirconium oxide fine particles to 10 parts by weight of the composite oxide particles provided with the coating layer and performing dry stirring and mixing, the zirconium oxide fine particles are formed on the surface of the composite oxide particles on which the coating layer is formed. A positive electrode active material was obtained as a surface layer by coating. Other than this, a cylindrical secondary battery was fabricated in the same manner as Sample 1-1.

<Sample 1-5>
By adding 0.03 parts by weight of titanium oxide fine particles to 10 parts by weight of the composite oxide particles provided with the coating layer and performing dry stirring and mixing, the titanium oxide fine particles are formed on the surface of the composite oxide particles on which the coating layer is formed. A positive electrode active material was obtained as a surface layer by coating. Other than this, a cylindrical secondary battery was fabricated in the same manner as Sample 1-1.

<Sample 1-6>
Nickel nitrate (Ni (NO ₃ ) ₂ · 6H ₂ O) 3.20 parts by weight, manganese nitrate (Mn (NO ₃ ) ₂ · 6H ₂ O) 3.30 parts by weight are added, and pure water is added to add 20 parts by weight. A composite oxide particle having a coating layer was prepared by adding the solution over a period of 1 hour to a solution in which the composite oxide was dispersed, and then 10 parts by weight of the composite oxide particle provided with the coating layer Sample 1 except that 0.03 part by weight of titanium oxide fine particles were added and dry stirring and mixing were performed to coat the surface of the composite oxide particles on which the coating layer was formed with titanium oxide fine particles. In the same manner as in Example 2, a cylindrical secondary battery was produced.

<Sample 1-7>
Add 2.40 parts by weight of nickel nitrate and 0.83 parts by weight of manganese nitrate, prepare pure water to make 10 parts by weight, and add over 30 minutes to the solution in which the complex oxide is dispersed. A cylindrical secondary battery was produced in the same manner as Sample 1-2, except that composite oxide particles having a coating layer were produced by the above and a positive electrode active material produced without providing a surface layer was used.

<Sample 1-8>
Same as Sample 1-7 except that 0.01 parts by weight of silicon oxide fine particles were added to 10 parts by weight of composite oxide particles having a coating layer, and a positive electrode active material prepared by forming a surface layer by dry stirring and mixing was used. Thus, a cylindrical secondary battery was produced.

<Sample 1-9>
Same as Sample 1-7 except that 0.02 part by weight of aluminum oxide fine particles was added to 10 parts by weight of composite oxide particles having a coating layer, and a positive electrode active material prepared by forming a surface layer by dry stirring and mixing was used. Thus, a cylindrical secondary battery was produced.

<Sample 1-10>
Similar to Sample 1-7, except that a positive electrode active material prepared by adding 0.03 part by weight of titanium oxide fine particles to 10 parts by weight of composite oxide particles having a coating layer and forming a surface layer by dry stirring and mixing was used. Thus, a cylindrical secondary battery was produced.

<Sample 1-11>
Same as Sample 1-7 except that 0.01 parts by weight of zirconium oxide fine particles were added to 10 parts by weight of composite oxide particles having a coating layer, and a positive electrode active material prepared by forming a surface layer by dry stirring and mixing was used. Thus, a cylindrical secondary battery was produced.

<Sample 1-12>
The composite oxide particles were mixed with 38.1 parts by weight of commercially available reagent lithium carbonate (Li ₂ CO ₃ ), 117.7 parts by weight of cobalt carbonate (CoCO ₃ ), and gallium nitrate (Ga (NO ₃ ) ₃ .9H ₂ O. ) A positive electrode active material composed of composite oxide particles in which only a coating layer was formed and no surface layer was prepared by the same method as Sample 1-1 except that 4.2 parts by weight were mixed. The average particle diameter of this composite oxide particle measured by a laser scattering method was 12 μm, and the average chemical composition analysis value was Li _1.03 Co _0.997 Ga _0.003 O _2.02 . A cylindrical secondary battery was produced in the same manner as Sample 1-1 except that this positive electrode active material was used.

<Sample 1-13>
Similar to Sample 1-12 except that 0.01 parts by weight of silicon oxide fine particles were added to 10 parts by weight of composite oxide particles having a coating layer, and a positive electrode active material prepared by forming a surface layer by dry stirring and mixing was used. Thus, a cylindrical secondary battery was produced.

<Sample 1-14>
Same as Sample 1-12 except that 0.02 part by weight of aluminum oxide fine particles was added to 10 parts by weight of composite oxide particles having a coating layer, and a positive electrode active material prepared by forming a surface layer by dry stirring and mixing was used. Thus, a cylindrical secondary battery was produced.

<Sample 1-15>
Similar to Sample 1-12 except that 0.03 part by weight of titanium oxide fine particles were added to 10 parts by weight of composite oxide particles having a coating layer, and a positive electrode active material prepared by forming a surface layer by dry stirring and mixing was used. Thus, a cylindrical secondary battery was produced.

<Sample 1-16>
Similar to Sample 1-12 except that 0.01 parts by weight of zirconium oxide fine particles were added to 10 parts by weight of composite oxide particles having a coating layer, and a positive electrode active material prepared by forming a surface layer by dry stirring and mixing was used. Thus, a cylindrical secondary battery was produced.

<Sample 1-17>
The composite oxide particles were mixed with 38.1 parts by weight of commercially available reagent lithium carbonate (Li ₂ CO ₃ ), 116.5 parts by weight of cobalt carbonate (CoCO ₃ ), and gallium nitrate (Ga (NO ₃ ) ₃ .9H ₂ O. ) Sample 1-2, except that 0.42 parts by weight, 0.78 parts by weight of aluminum hydroxide (Al (OH) ₃ ), and 0.84 parts by weight of magnesium carbonate (MgCO ₃ ) were mixed. A positive electrode active material composed of composite oxide particles in which only a coating layer was formed and no surface layer was produced by the same method. The average particle diameter of the composite oxide particles measured by a laser scattering method was 13 μm, and the average chemical composition analysis value was Li _1.03 Co _0.979 Ga _0.001 Al _0.01 Mg _0.01 O _2.02 . A cylindrical secondary battery was produced in the same manner as Sample 1-1 except that this positive electrode active material was used.

<Sample 1-18>
Similar to Sample 1-17 except that 0.01 parts by weight of silicon oxide fine particles were added to 10 parts by weight of composite oxide particles having a coating layer, and a positive electrode active material prepared by forming a surface layer by dry stirring and mixing was used. Thus, a cylindrical secondary battery was produced.

<Sample 1-19>
Similar to Sample 1-17 except that 0.05 parts by weight of aluminum oxide fine particles were added to 10 parts by weight of composite oxide particles having a coating layer, and a positive electrode active material prepared by forming a surface layer by dry stirring and mixing was used. Thus, a cylindrical secondary battery was produced.

<Sample 1-20>
Similar to Sample 1-17, except that a positive electrode active material prepared by adding 0.03 part by weight of titanium oxide fine particles to 10 parts by weight of composite oxide particles having a coating layer and forming a surface layer by dry stirring and mixing was used. Thus, a cylindrical secondary battery was produced.

<Sample 1-21>
Same as Sample 1-17 except that 0.01 parts by weight of zirconium oxide fine particles were added to 10 parts by weight of composite oxide particles having a coating layer, and a positive electrode active material prepared by forming a surface layer by dry stirring and mixing was used. Thus, a cylindrical secondary battery was produced.

<Sample 1-22>
The composite oxide particles were the same as Sample 1-1 except that 38.1 parts by weight of a commercially available reagent, lithium carbonate (Li ₂ CO ₃ ), and 118.9 parts by weight of cobalt carbonate (CoCO ₃ ) were mixed. Composite oxide particles were prepared by the method described above. The composite oxide particles were measured by a laser scattering method. The average particle diameter was 12 μm, and the average chemical composition analysis value was Li _1.03 CoO _2.02 . Similar to Sample 1-2, except that the lithium cobaltate particles were used to form a coating layer and a surface layer made of aluminum oxide by the same method as Sample 1-2, and then the positive electrode active material obtained by firing was used. Thus, a cylindrical secondary battery was produced.

<Sample 1-23>
A cylindrical secondary battery was produced in the same manner as Sample 1-22, except that a portion of the belt-like positive electrode produced by compression with a roller press was collected and compression was repeated twice more with the roller press under the same conditions. did.

<Sample 1-24>
A cylindrical secondary battery was fabricated in the same manner as Sample 1-22, except that a positive electrode active material without a coating layer was used.

<Sample 1-25>
The composite oxide particles were mixed with 38.1 parts by weight of commercially available lithium carbonate (Li ₂ CO ₃ ), 112.9 parts by weight of cobalt carbonate (CoCO ₃ ), and gallium nitrate (Ga (NO ₃ ) ₃ .9H ₂ O. ) A positive electrode active material composed of composite oxide particles in which only the coating layer was formed and no surface layer was prepared by the same method as Sample 1-2, except that 21.0 parts by weight were mixed. The average particle diameter of the composite oxide particles measured by a laser scattering method was 12 μm, and the average chemical composition analysis value was Li _1.03 Co _0.95 Ga _0.05 O _2.02 . A cylindrical secondary battery was produced in the same manner as Sample 1-1 except that this positive electrode active material was used.

<Sample 1-26>
In a solution obtained by stirring and dispersing 20 parts by weight of composite oxide particles in pure water, 0.64 part by weight of commercially available nickel nitrate (Ni (NO ₃ ) ₂ .6H ₂ O) and manganese nitrate (Mn (Mn ( A cylindrical secondary battery was fabricated in the same manner as Sample 1-1 except that 2.64 parts by weight of NO ₃ ) ₂ · 6H ₂ O) was added to form a coating layer and no surface layer was provided.

<Sample 1-27>
Sample 1-26 was used except that 0.02 part by weight of aluminum oxide fine particles was added to 10 parts by weight of composite oxide particles having a coating layer and a surface layer was formed by dry stirring and mixing. Similarly, a cylindrical secondary battery was produced.

[Evaluation of cylindrical secondary battery]
(A) Initial Capacity The cylindrical secondary battery produced as described above was charged and discharged at an environmental temperature of 45 ° C., and the discharge capacity at the first cycle was determined as the initial capacity.

  Charging is performed at a constant current of 1000 mA until the battery voltage reaches 4.40 V, and then charged at a constant voltage of 4.40 V until the total charging time is 2.5 hours. went. Further, the discharge was performed at a constant current of 800 mA until the battery voltage reached 2.75V.

(B) Capacity maintenance rate For the cylindrical secondary battery whose initial capacity was determined as in (a), charge and discharge was performed up to 200 cycles under the same conditions, and the discharge capacity at the 200th cycle was measured. The capacity maintenance rate was calculated.

  Table 1 below shows the results of the evaluation.

  As can be seen from Table 1, to the composite oxide particles composed of lithium cobaltate in which gallium (Ga) represented by Chemical Formula 1 is dissolved, lithium (Li), nickel (Ni), and manganese (Mn) By using a positive electrode active material provided with a coating layer made of an oxide containing at least one and having a surface layer containing at least one of silicon oxide, aluminum oxide, zirconium oxide, and titanium oxide, a high initial capacity and capacity retention rate Can be manufactured.

  Further, for example, as can be seen by comparing Sample 1-7 with Sample 1-8 to Sample 1-11, in the composite oxide particles having a coating layer produced under the same conditions, silicon oxide, aluminum oxide, zirconium oxide When the surface layer made of any of titanium oxide is provided, the initial capacity and the capacity retention rate are improved as compared with the case where the surface layer is not provided.

  Further, as can be seen by comparing Sample 1-9 and Sample 1-27, in the composite oxide particles having the surface layer produced under the same conditions, when the coating layer is provided, compared with the case where the coating layer is not provided. Thus, the initial capacity and capacity retention rate are improved.

<Sample 2-1 to Sample 2-24>
In Example 2, a non-aqueous electrolyte secondary battery is manufactured using a positive electrode active material using a composite oxide prepared by dissolving bismuth (Bi) in lithium cobaltate.

<Sample 2-1>
First, 38.1 parts by weight of a commercially available reagent, lithium carbonate (Li ₂ CO ₃ ), 118.3 parts by weight of cobalt carbonate (CoCO ₃ ), and 1.27 parts by weight of bismuth carbonate ((BiO) ₂ CO ₃ ) Mix thoroughly while grinding with a ball mill. The mixture was then calcined in air at 650 ° C. for 5 hours, and further kept in air at 950 ° C. for 20 hours, and then cooled to 150 ° C. at 7 ° C./min. Next, it was taken out at room temperature and pulverized to produce composite oxide particles. The average particle diameter of this composite oxide particle measured by a laser scattering method was 11 μm, and the average chemical composition analysis value was Li _1.03 Co _0.995 Bi _0.005 O _2.02 .

  The composite oxide particles were provided with a coating layer and a surface layer made of silicon oxide fine particles by the same method as in Sample 1-1 to produce a positive electrode active material, and a cylindrical secondary battery was produced using this. .

<Sample 2-2>
A cathode active material is prepared by providing a composite layer similar to sample 2-1 with a coating layer and a surface layer made of aluminum oxide fine particles by the same method as in sample 1-2, and using this, a cylindrical secondary material is produced. A battery was produced.

<Sample 2-3>
A cylindrical secondary battery was produced in the same manner as Sample 2-2, except that a portion of the belt-like positive electrode produced by compression with a roller press was collected and compression was repeated twice more with the roller press under the same conditions. did.

<Sample 2-4>
By adding 0.01 parts by weight of zirconium oxide fine particles to 10 parts by weight of the composite oxide particles provided with the coating layer and performing dry stirring and mixing, the zirconium oxide fine particles are formed on the surface of the composite oxide particles on which the coating layer is formed. A positive electrode active material was obtained as a surface layer by coating. Other than this, a cylindrical secondary battery was fabricated in the same manner as Sample 2-1.

<Sample 2-5>
By adding 0.03 parts by weight of titanium oxide fine particles to 10 parts by weight of the composite oxide particles provided with the coating layer and performing dry stirring and mixing, the titanium oxide fine particles are formed on the surface of the composite oxide particles on which the coating layer is formed. A positive electrode active material was obtained as a surface layer by coating. Other than this, a cylindrical secondary battery was fabricated in the same manner as Sample 2-1.

<Sample 2-6>
Add 3.20 parts by weight of nickel nitrate and 3.30 parts by weight of manganese nitrate, prepare pure water to make 20 parts by weight, and add over 1 hour to the solution in which the composite oxide is dispersed. The composite oxide particles having a coating layer are prepared by the above, 0.03 parts by weight of titanium oxide fine particles are added to 10 parts by weight of the composite oxide particles provided with the coating layer, and dry stirring and mixing are performed. A cylindrical secondary battery was produced in the same manner as in Sample 2-2, except that the surface of the composite oxide particle formed with titanium oxide fine particles was coated to form a surface layer.

<Sample 2-7>
The composite oxide particles, and ₍₂ CO ₃ Li) 38.1 parts by weight of lithium carbonate commercially available reagents, cobalt carbonate (CoCO ₃₎ 115.3 parts by weight, bismuth carbonate _{((BiO) 2 CO 3)} 2.55 A coating layer is formed by the same method as Sample 2-2 except that 0.78 parts by weight of aluminum hydroxide (Al (OH) ₃ ) and 0.84 parts by weight of magnesium carbonate (MgCO ₃ ) are mixed. Thus prepared composite oxide particles were produced. The average particle diameter of the composite oxide particles measured by a laser scattering method was 12 μm, and the average chemical composition analysis value was Li _1.03 Co _0.97 Al _0.01 Mg _0.01 Bi _0.01 O _2.02 . Sample 2-2 except that 0.05 part by weight of aluminum oxide fine particles was added to 10 parts by weight of the composite oxide particles having the coating layer, and a positive electrode active material produced by forming a surface layer by dry stirring and mixing was used. In the same manner, a cylindrical secondary battery was produced.

<Sample 2-8>
The composite oxide particles, and ₍₂ CO ₃ Li) 38.1 parts by weight of lithium carbonate commercially available reagents, cobalt carbonate (CoCO ₃₎ 115.3 parts by weight, bismuth carbonate _{((BiO) 2 CO 3)} 1.28 Only the coating layer was formed by the same method as Sample 2-1, except that 0.78 parts by weight of aluminum hydroxide (Al (OH) ₃ ) and 0.84 parts by weight of magnesium carbonate (MgCO ₃ ) were mixed. A positive electrode active material made of composite oxide particles formed and having no surface layer was produced. The average particle diameter of the composite oxide particles measured by a laser scattering method was 12 μm, and the average chemical composition analysis value was Li _1.03 Co _0.975 Al _0.01 Mg _0.01 Bi _0.005 O _2.02 . A cylindrical secondary battery was produced in the same manner as in Sample 2-1, except that this positive electrode active material was used.

<Sample 2-9>
Similar to Sample 2-8 except that 0.01 parts by weight of silicon oxide fine particles were added to 10 parts by weight of composite oxide particles having a coating layer, and a positive electrode active material prepared by forming a surface layer by dry stirring and mixing was used. Thus, a cylindrical secondary battery was produced.

<Sample 2-10>
Similar to Sample 2-8 except that 0.02 part by weight of aluminum oxide fine particles was added to 10 parts by weight of composite oxide particles having a coating layer, and a positive electrode active material prepared by forming a surface layer by dry stirring and mixing was used. Thus, a cylindrical secondary battery was produced.

<Sample 2-11>
Similar to Sample 2-8, except that 0.03 part by weight of titanium oxide fine particles were added to 10 parts by weight of composite oxide particles having a coating layer, and a positive electrode active material prepared by forming a surface layer by dry stirring and mixing was used. Thus, a cylindrical secondary battery was produced.

<Sample 2-12>
Same as Sample 2-8 except that 0.01 parts by weight of zirconium oxide fine particles were added to 10 parts by weight of composite oxide particles having a coating layer, and a positive electrode active material prepared by forming a surface layer by dry stirring and mixing was used. Thus, a cylindrical secondary battery was produced.

<Sample 2-13>
2.60 parts by weight of nickel nitrate and 0.70 part by weight of manganese nitrate are added, and a solution is prepared by adding pure water to 10 parts by weight, and added to the solution in which the composite oxide is dispersed over 30 minutes. A cylindrical secondary battery was produced in the same manner as in Sample 2-2, except that composite oxide particles having a coating layer were produced by the above, and a positive electrode active material produced without providing a surface layer was used.

<Sample 2-14>
Similar to Sample 2-13, except that 0.01 parts by weight of silicon oxide fine particles were added to 10 parts by weight of composite oxide particles having a coating layer, and a positive electrode active material prepared by forming a surface layer by dry stirring and mixing was used. Thus, a cylindrical secondary battery was produced.

<Sample 2-15>
Except for using a positive electrode active material prepared by adding 0.02 part by weight of aluminum oxide fine particles to 10 parts by weight of composite oxide particles having a coating layer and forming a surface layer by dry stirring and mixing, the same as 2-13 Thus, a cylindrical secondary battery was produced.

<Sample 2-16>
Except for using a positive electrode active material prepared by adding 0.03 part by weight of titanium oxide fine particles to 10 parts by weight of composite oxide particles having a coating layer and forming a surface layer by dry stirring and mixing, the same as 2-13 Thus, a cylindrical secondary battery was produced.

<Sample 2-17>
Except for using a positive electrode active material prepared by adding 0.01 parts by weight of zirconium oxide fine particles to 10 parts by weight of composite oxide particles having a coating layer, and forming a surface layer by dry stirring and mixing, the same as 2-13 was performed. Thus, a cylindrical secondary battery was produced.

<Sample 2-18>
The composite oxide particles were prepared in the same manner as in Sample 2-2 except that 38.1 parts by weight of commercially available lithium carbonate (Li ₂ CO ₃ ) and 118.9 parts by weight of cobalt carbonate (CoCO ₃ ) were mixed. Composite oxide particles were produced. The composite oxide particles were measured by a laser scattering method. The average particle diameter was 12 μm, and the average chemical composition analysis value was Li _1.03 CoO _2.02 . Similar to Sample 1-2, except that the lithium cobaltate particles were used to form a coating layer and a surface layer made of aluminum oxide by the same method as Sample 1-2, and then the positive electrode active material obtained by firing was used. Thus, a cylindrical secondary battery was produced.

<Sample 2-19>
A cylindrical secondary battery was produced in the same manner as Sample 2-18, except that a portion of the belt-like positive electrode produced by compression with a roller press was collected and the compression was repeated twice more with the roller press under the same conditions. did.

<Sample 2-20>
A cylindrical secondary battery was produced in the same manner as Sample 2-18, except that the positive electrode active material produced without providing the coating layer and the surface layer was used.

<Sample 2-21>
A cylindrical secondary battery was produced in the same manner as Sample 2-1, except that a positive electrode active material produced without providing a surface layer was used.

<Sample 2-22>
Manganese nitrate (Mn (NO ₃ ) ₂ · 6H ₂ O) 6.6 parts by weight was added, and pure water was added to prepare a solution with 20 parts by weight. A composite secondary battery having a coating layer is prepared by adding a cylindrical secondary battery in the same manner as in Sample 2-2 except that a positive electrode active material prepared without providing a surface layer is used. Produced.

<Sample 2-23>
A cylindrical secondary battery was produced in the same manner as Sample 2-8, except that a positive electrode active material produced without providing a coating layer was used.

<Sample 2-24>
The composite oxide particles, and ₍₂ CO ₃ Li) 38.1 parts by weight of lithium carbonate commercially available reagents, cobalt carbonate (CoCO ₃₎ 89.1 parts by weight, bismuth carbonate _{((BiO) 2 CO 3)} 63.8 Composite oxide particles were produced in the same manner as in Sample 2-1, except that the parts by weight were mixed. The average particle diameter of this composite oxide particle measured by a laser scattering method was 11 μm, and the average chemical composition analysis value was Li _1.03 Co _0.75 Bi _0.25 O _2.02 . Cylindrical type 2 was prepared in the same manner as Sample 2-1, except that this composite oxide particle was used and a positive electrode active material prepared by firing without providing a coating layer and a surface layer by the same method as Sample 1-1 was used. A secondary battery was produced.

[Evaluation of cylindrical secondary battery]
(A) Initial capacity and (b) capacity maintenance rate were evaluated using the same method as the evaluation of Sample 1-1 to Sample 1-27.

  Table 2 below shows the results of the evaluation.

  As can be seen from Table 2, to the composite oxide particles composed of lithium cobaltate in which bismuth (Bi) is dissolved as shown in Chemical Formula 1, lithium (Li), nickel (Ni), and manganese (Mn) High initial capacity and capacity can be maintained by using a positive electrode active material provided with a coating layer made of an oxide containing at least one of the above and a surface layer containing at least one of silicon oxide, aluminum oxide, zirconium oxide and titanium oxide. A secondary battery in which the rate is compatible can be manufactured.

<Sample 3-1 to Sample 3-57>
In Example 2, a positive electrode active using a composite oxide prepared by dissolving at least one selected from magnesium (Mg), aluminum (Al), titanium (Ti), and zirconium (Zr) in lithium cobaltate. A non-aqueous electrolyte secondary battery is produced using the substance.

<Sample 3-1>
First, lithium carbonate (Li ₂ CO ₃₎ 38.1 parts by weight of commercially available reagents, cobalt carbonate (CoCO ₃₎ 116.5 parts by weight aluminum hydroxide (Al (OH) ₃₎ 7.8 parts by weight, 8.4 parts by weight of magnesium carbonate (MgCO ₃ ) are mixed well while being pulverized with a ball mill. The mixture was then calcined in air at 650 ° C. for 5 hours, and further kept in air at 950 ° C. for 20 hours, and then cooled to 150 ° C. at 7 ° C./min. Next, it was taken out at room temperature and pulverized to produce composite oxide particles. The average particle diameter of this composite oxide particle measured by a laser scattering method was 13 μm, and the average chemical composition analysis value was Li _1.03 Co _0.98 Al _0.01 Mg _0.01 O _2.02 .

  The composite oxide particles were provided with a coating layer and a surface layer made of silicon oxide fine particles by the same method as in Sample 1-1 to produce a positive electrode active material, and a cylindrical secondary battery was produced using this. .

<Sample 3-2>
Sample 3-1 except that 0.01 parts by weight of aluminum oxide fine particles were added to 10 parts by weight of composite oxide particles having a coating layer and a surface layer was formed by dry stirring and mixing. Similarly, a cylindrical secondary battery was produced.

<Sample 3-3>
Sample 3-1 except that 0.01 parts by weight of titanium oxide fine particles were added to 10 parts by weight of composite oxide particles having a coating layer and a surface layer was formed by dry stirring and mixing. Similarly, a cylindrical secondary battery was produced.

<Sample 3-4>
Sample 3-1 except that 0.01 parts by weight of zirconium oxide fine particles were added to 10 parts by weight of composite oxide particles having a coating layer and a surface layer was formed by dry stirring and mixing. Similarly, a cylindrical secondary battery was produced.

<Sample 3-5>
When the coating layer is provided on the composite oxide particles, 2.56 parts by weight of nickel nitrate (Ni (NO ₃ ) ₂ .6H ₂ O) as a commercial reagent with respect to 20 parts by weight of the composite oxide particles, and manganese nitrate as a commercial reagent A cylindrical secondary battery was fabricated in the same manner as Sample 3-1, except that 0.32 parts by weight of (Mn (NO ₃ ) ₂ .6H ₂ O) was added.

<Sample 3-6>
Sample 3-5 except that 0.01 parts by weight of aluminum oxide fine particles were added to 10 parts by weight of the composite oxide particles having a coating layer and a surface layer was formed by dry stirring and mixing. Similarly, a cylindrical secondary battery was produced.

<Sample 3-7>
Sample 3-5 except that a positive electrode active material prepared by adding 0.01 parts by weight of titanium oxide fine particles to 10 parts by weight of composite oxide particles having a coating layer and forming a surface layer by dry stirring and mixing was used. Similarly, a cylindrical secondary battery was produced.

<Sample 3-8>
Sample 3-5 except that a positive electrode active material prepared by adding 0.01 parts by weight of zirconium oxide fine particles to 10 parts by weight of composite oxide particles having a coating layer and forming a surface layer by dry stirring and mixing was used. Similarly, a cylindrical secondary battery was produced.

<Sample 3-9>
Sample 3 except that 3.20 parts by weight of commercially available nickel nitrate (Ni (NO ₃ ) ₂ .6H ₂ O) was added to 20 parts by weight of the composite oxide particles when the coating layer was provided on the composite oxide particles. A cylindrical secondary battery was produced in the same manner as in Example-1.

<Sample 3-10>
Sample 3-9 except that 0.01 parts by weight of aluminum oxide fine particles were added to 10 parts by weight of composite oxide particles having a coating layer, and a positive electrode active material prepared by forming a surface layer by dry stirring and mixing was used. Similarly, a cylindrical secondary battery was produced.

<Sample 3-11>
Sample 3-9 except that 0.01 parts by weight of titanium oxide fine particles were added to 10 parts by weight of composite oxide particles having a coating layer, and a positive electrode active material prepared by forming a surface layer by dry stirring and mixing was used. Similarly, a cylindrical secondary battery was produced.

<Sample 3-12>
Sample 3-9 except that 0.01 parts by weight of zirconium oxide fine particles were added to 10 parts by weight of the composite oxide particles having a coating layer and a surface layer was formed by dry stirring and mixing. Similarly, a cylindrical secondary battery was produced.

<Sample 3-13>
The composite oxide particles were sufficiently mixed with 38.1 parts by weight of commercially available lithium carbonate (Li ₂ CO ₃ ) and 116.5 parts by weight of cobalt carbonate (CoCO ₃ ) while being pulverized with a ball mill. 45.6 parts by weight of ethoxide ((C ₂ H ₅ O) ₄ Ti) is dissolved and added to anhydrous ethyl alcohol and mixed. The mixture is fired under the same conditions as in Sample 1-1, pulverized and combined. Oxide particles were prepared. The average particle diameter of this composite oxide particle measured by a laser scattering method was 15 μm, and the average chemical composition analysis value was Li _1.03 Co _0.98 Ti _0.02 O _2.02 .

  Cylindrical cylinders as in Sample 1-1, except that a positive electrode active material prepared by providing a coating layer and a surface layer composed of silicon oxide fine particles by the same method as Sample 1-1 was used for such composite oxide particles. A type secondary battery was produced.

<Sample 3-14>
Sample 3-13 except that 0.01 parts by weight of aluminum oxide fine particles were added to 10 parts by weight of composite oxide particles having a coating layer and a surface layer was formed by dry stirring and mixing. Similarly, a cylindrical secondary battery was produced.

<Sample 3-15>
Sample 3-13 except that 0.01 parts by weight of titanium oxide fine particles were added to 10 parts by weight of composite oxide particles having a coating layer and a surface layer was formed by dry stirring and mixing. Similarly, a cylindrical secondary battery was produced.

<Sample 3-16>
Sample 3-13 except that 0.01 parts by weight of zirconium oxide fine particles were added to 10 parts by weight of composite oxide particles having a coating layer, and a surface active layer was formed by dry stirring and mixing. Similarly, a cylindrical secondary battery was produced.

<Sample 3-17>
When the coating layer is provided on the composite oxide particles, 2.56 parts by weight of nickel nitrate (Ni (NO ₃ ) ₂ .6H ₂ O) as a commercial reagent with respect to 20 parts by weight of the composite oxide particles, and manganese nitrate as a commercial reagent A cylindrical secondary battery was fabricated in the same manner as Sample 3-13, except that 0.32 parts by weight of (Mn (NO ₃ ) ₂ .6H ₂ O) was added.

<Sample 3-18>
Sample 3-17 except that 0.01 parts by weight of aluminum oxide fine particles were added to 10 parts by weight of composite oxide particles having a coating layer, and a positive electrode active material prepared by forming a surface layer by dry stirring and mixing was used. Similarly, a cylindrical secondary battery was produced.

<Sample 3-19>
Sample 3-17 except that 0.01 parts by weight of titanium oxide fine particles were added to 10 parts by weight of composite oxide particles having a coating layer, and a positive electrode active material prepared by forming a surface layer by dry stirring and mixing was used. Similarly, a cylindrical secondary battery was produced.

<Sample 3-20>
Sample 3-17 except that 0.01 parts by weight of zirconium oxide fine particles were added to 10 parts by weight of composite oxide particles having a coating layer, and a positive electrode active material prepared by forming a surface layer by dry stirring and mixing was used. Similarly, a cylindrical secondary battery was produced.

<Sample 3-21>
Sample 3 except that 3.20 parts by weight of commercially available nickel nitrate (Ni (NO ₃ ) ₂ .6H ₂ O) was added to 20 parts by weight of the composite oxide particles when the coating layer was provided on the composite oxide particles. A cylindrical secondary battery was produced in the same manner as in -13.

<Sample 3-22>
Sample 3-21 except that 0.01 parts by weight of aluminum oxide fine particles were added to 10 parts by weight of composite oxide particles having a coating layer and a surface layer was formed by dry stirring and mixing. Similarly, a cylindrical secondary battery was produced.

<Sample 3-23>
Sample 3-21 except that 0.01 parts by weight of titanium oxide fine particles were added to 10 parts by weight of composite oxide particles having a coating layer and a surface layer was formed by dry stirring and mixing. Similarly, a cylindrical secondary battery was produced.

<Sample 3-24>
Sample 3-21 except that 0.01 parts by weight of zirconium oxide fine particles were added to 10 parts by weight of composite oxide particles having a coating layer and a surface layer was formed by dry stirring and mixing. Similarly, a cylindrical secondary battery was produced.

<Sample 3-25>
The composite oxide particles were mixed thoroughly with 38.1 parts by weight of commercially available lithium carbonate (Li ₂ CO ₃ ) and 116.5 parts by weight of cobalt carbonate (CoCO ₃ ) while being pulverized with a ball mill. 45.6 parts by weight of ethoxide ((C ₂ H ₅ O) ₄ Zr) is dissolved and added to anhydrous ethyl alcohol and mixed. This mixture is fired under the same conditions as in Sample 1-1, pulverized and combined. Oxide particles were prepared. The average particle diameter of this composite oxide particle measured by a laser scattering method was 13 μm, and the average chemical composition analysis value was Li _1.03 Co _0.98 Zr _0.02 O _2.02 .

  Cylindrical cylinders as in Sample 1-1, except that a positive electrode active material prepared by providing a coating layer and a surface layer composed of silicon oxide fine particles by the same method as Sample 1-1 was used for such composite oxide particles. A type secondary battery was produced.

<Sample 3-26>
Sample 3-25 except that 0.01 parts by weight of aluminum oxide fine particles were added to 10 parts by weight of composite oxide particles having a coating layer and a surface layer was formed by dry stirring and mixing. Similarly, a cylindrical secondary battery was produced.

<Sample 3-27>
Sample 3-25 and sample 3-25 except that 0.01 parts by weight of titanium oxide fine particles were added to 10 parts by weight of composite oxide particles having a coating layer and a surface layer was formed by dry stirring and mixing. Similarly, a cylindrical secondary battery was produced.

<Sample 3-28>
Sample 3-25 except that 0.01 parts by weight of zirconium oxide fine particles were added to 10 parts by weight of composite oxide particles having a coating layer, and a positive electrode active material prepared by forming a surface layer by dry stirring and mixing was used. Similarly, a cylindrical secondary battery was produced.

<Sample 3-29>
When the coating layer is provided on the composite oxide particles, 2.56 parts by weight of nickel nitrate (Ni (NO ₃ ) ₂ .6H ₂ O) as a commercial reagent with respect to 20 parts by weight of the composite oxide particles, and manganese nitrate as a commercial reagent A cylindrical secondary battery was fabricated in the same manner as Sample 3-25, except that 0.32 parts by weight of (Mn (NO ₃ ) ₂ .6H ₂ O) was added.

<Sample 3-30>
Sample 3-29 except that a positive electrode active material prepared by adding 0.01 parts by weight of aluminum oxide fine particles to 10 parts by weight of composite oxide particles having a coating layer and forming a surface layer by dry stirring and mixing was used. Similarly, a cylindrical secondary battery was produced.

<Sample 3-31>
Sample 3-29 except that 0.01 parts by weight of titanium oxide fine particles were added to 10 parts by weight of composite oxide particles having a coating layer, and a positive electrode active material prepared by forming a surface layer by dry stirring and mixing was used. Similarly, a cylindrical secondary battery was produced.

<Sample 3-32>
Sample 3-29 except that 0.01 parts by weight of zirconium oxide fine particles were added to 10 parts by weight of composite oxide particles having a coating layer, and a positive electrode active material prepared by forming a surface layer by dry stirring and mixing was used. Similarly, a cylindrical secondary battery was produced.

<Sample 3-33>
Sample 3 except that 3.20 parts by weight of commercially available nickel nitrate (Ni (NO ₃ ) ₂ .6H ₂ O) was added to 20 parts by weight of the composite oxide particles when the coating layer was provided on the composite oxide particles. A cylindrical secondary battery was produced in the same manner as -25.

<Sample 3-34>
Sample 3-33, except that a positive electrode active material prepared by adding 0.01 parts by weight of aluminum oxide fine particles to 10 parts by weight of composite oxide particles having a coating layer and forming a surface layer by dry stirring and mixing was used. Similarly, a cylindrical secondary battery was produced.

<Sample 3-35>
Sample 3-33 except that 0.01 parts by weight of titanium oxide fine particles were added to 10 parts by weight of composite oxide particles having a coating layer, and a positive electrode active material prepared by forming a surface layer by dry stirring and mixing was used. Similarly, a cylindrical secondary battery was produced.

<Sample 3-36>
Sample 3-33 except that a positive electrode active material prepared by adding 0.01 parts by weight of zirconium oxide fine particles to 10 parts by weight of composite oxide particles having a coating layer and forming a surface layer by dry stirring and mixing was used. Similarly, a cylindrical secondary battery was produced.

<Sample 3-37>
Commercially available reagent lithium carbonate (Li ₂ CO ₃ ) 38.1 parts by weight, cobalt carbonate (CoCO ₃ ) 113.0 parts by weight, aluminum hydroxide (Al (OH) ₃ ) 23.4 parts by weight, magnesium carbonate 16.9 parts by weight of (MgCO ₃ ) is thoroughly mixed while being pulverized by a ball mill. The mixture was then calcined in air at 650 ° C. for 5 hours, and further kept in air at 950 ° C. for 20 hours, and then cooled to 150 ° C. at 7 ° C./min. Next, it was taken out at room temperature and pulverized to produce composite oxide particles. The average particle diameter of the composite oxide particles measured by a laser scattering method was 13 μm, and the average chemical composition analysis value was Li _1.03 Co _0.95 Al _0.03 Mg _0.02 O _2.02 .

  The composite oxide particles were provided with a coating layer and a surface layer composed of aluminum oxide fine particles by the same method as in Sample 1-2 to produce a positive electrode active material, and a cylindrical secondary battery was produced using this. .

<Sample 3-38>
A cylindrical secondary battery was produced in the same manner as Sample 3-37, except that a portion of the belt-like positive electrode produced by compression with a roller press was collected, and the compression was repeated twice more with the roller press under the same conditions. did.

<Sample 3-39>
When the coating layer was formed, the same method as in Sample 1-2 was used, except that 0.03 part by weight of titanium oxide fine particles were added to 10 parts by weight of the composite oxide particles on which the coating layer was formed. Similarly, a cylindrical secondary battery was produced.

<Sample 3-40>
A cylindrical secondary battery was produced in the same manner as in Sample 3-26 except that the same method as in Sample 1-2 was used when forming the coating layer.

<Sample 3-41>
Add nickel nitrate (Ni (NO ₃ ) ₂ · 6H ₂ O) 3.20 parts by weight, manganese nitrate (Mn (NO ₃ ) ₂ · 6H ₂ O) 3.30 parts by weight, add pure water to add 10 weights A cylindrical secondary battery was produced in the same manner as Sample 3-37, except that the coating layer was formed by adding the solution in a part and adding it to the solution in which the composite oxide was dispersed over 30 minutes.

<Sample 3-42>
Add nickel nitrate (Ni (NO ₃ ) ₂ · 6H ₂ O) 3.20 parts by weight, manganese nitrate (Mn (NO ₃ ) ₂ · 6H ₂ O) 3.30 parts by weight, add pure water to add 10 weights 0.02 parts by weight of aluminum oxide fine particles were added to 10 parts by weight of the composite oxide particles having a coating layer formed by adding the solution over 30 minutes to the solution in which the composite oxide was dispersed. A cylindrical secondary battery was produced in the same manner as Sample 3-39, except that a positive electrode active material produced by forming a surface layer by dry stirring and mixing was used.

<Sample 3-43>
Add nickel nitrate (Ni (NO ₃ ) ₂ · 6H ₂ O) 3.20 parts by weight, manganese nitrate (Mn (NO ₃ ) ₂ · 6H ₂ O) 3.30 parts by weight, add pure water to add 10 weights 0.02 parts by weight of aluminum oxide fine particles were added to 10 parts by weight of the composite oxide particles having a coating layer formed by adding the solution over 30 minutes to the solution in which the composite oxide was dispersed. A cylindrical secondary battery was produced in the same manner as Sample 3-40, except that a positive electrode active material produced by forming a surface layer by dry stirring and mixing was used.

<Sample 3-44>
Add nickel nitrate (Ni (NO ₃ ) ₂ · 6H ₂ O) 0.64 parts by weight, manganese nitrate (Mn (NO ₃ ) ₂ · 6H ₂ O) 0.66 parts by weight, add pure water to add 10 weights A cylindrical secondary battery was produced in the same manner as Sample 3-41, except that the coating layer was formed by adding the solution in a part and adding it to the solution in which the complex oxide was dispersed over 30 minutes.

<Sample 3-45>
Add nickel nitrate (Ni (NO ₃ ) ₂ · 6H ₂ O) 0.64 parts by weight, manganese nitrate (Mn (NO ₃ ) ₂ · 6H ₂ O) 0.66 parts by weight, add pure water to add 10 weights A cylindrical secondary battery was produced in the same manner as Sample 3-42, except that the coating layer was formed by adding the solution in a part and adding it to the solution in which the complex oxide was dispersed over 30 minutes.

<Sample 3-46>
Add nickel nitrate (Ni (NO ₃ ) ₂ · 6H ₂ O) 0.64 parts by weight, manganese nitrate (Mn (NO ₃ ) ₂ · 6H ₂ O) 0.66 parts by weight, add pure water to add 10 weights A cylindrical secondary battery was produced in the same manner as Sample 3-43, except that a coating layer was formed by preparing a part solution and adding it to the solution in which the composite oxide was dispersed over 30 minutes.

<Sample 3-47>
A cylindrical secondary battery was fabricated in the same manner as Sample 3-44, except that the amount of aluminum oxide fine particles added was 0.01 parts by weight.

<Sample 3-48>
A cylindrical secondary battery was produced in the same manner as Sample 3-45 except that the amount of aluminum oxide fine particles added was 0.01 parts by weight.

<Sample 3-49>
A cylindrical secondary battery was fabricated in the same manner as Sample 3-46 except that the amount of aluminum oxide fine particles added was 0.01 parts by weight.

<Sample 3-50>
Except that 38.1 parts by weight of a commercial reagent lithium carbonate (Li ₂ CO ₃ ) and 118.9 parts by weight of cobalt carbonate (CoCO ₃ ) were mixed to produce composite oxide particles, the same as Sample 3-37 was performed. Thus, a cylindrical secondary battery was produced. The average particle size measured with this composite oxide particles by a laser scattering method is 12 [mu] m, the average chemical composition analysis values were Li _1.03 CoO _2.02.

<Sample 3-51>
A cylindrical secondary battery was produced in the same manner as Sample 3-50, except that a portion of the belt-like positive electrode produced by compression with a roller press was collected and compression was repeated twice more with the roller press under the same conditions. did.

<Sample 3-52>
A cylindrical secondary battery was produced in the same manner as Sample 3-50 except that the coating layer was not provided.

<Sample 3-53>
A cylindrical secondary battery was produced in the same manner as Sample 3-50 except that the coating layer and the surface layer were not provided.

<Sample 3-54>
A cylindrical secondary battery was fabricated in the same manner as Sample 3-50, except that the amount of cobalt carbonate (CoCO ₃ ) was 118.0 parts by weight and the coating layer and the surface layer were not provided. The average particle size measured with this composite oxide particles by a laser scattering method is 13 .mu.m, the average chemical composition analysis values were Li _1.03 CoO _2.02.

<Sample 3-55>
A cylindrical secondary battery was produced in the same manner as Sample 3-13 except that the coating layer and the surface layer were not provided.

<Sample 3-56>
A cylindrical secondary battery was produced in the same manner as Sample 3-25 except that the coating layer and the surface layer were not provided.

<Sample 3-57>
When providing the coating layer on the composite oxide particles, the amount of nickel nitrate (Ni (NO ₃ ) ₂ .6H ₂ O) added is 1.32 parts by weight, and the composite oxide particles having the coating layer are oxidized to 10 parts by weight. A cylindrical secondary battery was produced in the same manner as Sample 3-37 except that 0.01 parts by weight of aluminum fine particles were added and a positive electrode active material produced by forming a surface layer by dry stirring and mixing was used.

[Evaluation of cylindrical secondary battery]
(A) Initial capacity and (b) capacity maintenance rate were evaluated using the same method as the evaluation of Sample 1-1 to Sample 1-27.

(C) AC resistance In the cylindrical secondary batteries of Example 3-4 and Example 3-8 and Comparative Example 3-4 and Comparative Example 3-8, charging and discharging were performed using the same method as the measurement of the initial capacity. After 20 cycles, SOD (State of Discharge) —100%, that is, AC resistance when full charge was evaluated.

  Tables 3 to 5 below show the results of evaluation of the initial capacity and capacity retention rate.

  FIG. 5 shows the AC resistance when SOD is 100%. In FIG. 5, reference numeral 51 indicates the measurement result of sample 3-4, reference numeral 52 indicates the measurement result of sample 3-8, reference numeral 53 indicates the measurement result of sample 3-53, and reference numeral 54 indicates the sample. The measurement result of 3-57 is shown, Z ′ (a) is the real part (resistance component) of the impedance, and Z ″ (b) is the imaginary part (reactance component) of the impedance. In this graph, the larger the arc of the graph, the greater the internal resistance of the battery.

  As can be seen from Tables 3 to 5, lithium cobalt oxide in which at least one selected from magnesium (Mg), aluminum (Al), titanium (Ti), and zirconium (Zr) represented by Chemical Formula 2 is dissolved. A coating layer made of an oxide containing lithium (Li) and at least one of nickel (Ni) and manganese (Mn) is provided on the composite oxide particles made of silicon oxide, aluminum oxide, zirconium oxide, titanium oxide. By using a positive electrode active material provided with a surface layer containing at least one of the above, a secondary battery having both a high initial capacity and a capacity retention rate can be produced.

  From the above results, it is understood that a secondary battery having high battery characteristics can be produced by using a positive electrode active material in which both a coating layer and a surface layer are formed on the composite oxide particles.

  The present invention is not limited to the above-described embodiments of the present invention, and various modifications and applications are possible without departing from the spirit of the present invention. For example, the shape is not particularly limited. A square shape, a coin shape, a button shape, or the like may be used.

  In the first example, a non-aqueous electrolyte secondary battery having an electrolyte as an electrolyte has been described. In the second example, a non-aqueous electrolyte secondary battery having a gel electrolyte as an electrolyte has been described, but the present invention is not limited thereto. It is not a thing.

  For example, as the electrolyte, in addition to the above-described ones, a polymer solid electrolyte using an ion conductive polymer or an inorganic solid electrolyte using an ion conductive inorganic material can be used. It may be used in combination with the electrolyte. Examples of the polymer compound that can be used for the polymer solid electrolyte include polyether, polyester, polyphosphazene, and polysiloxane. Examples of the inorganic solid electrolyte include ion conductive ceramics, ion conductive crystals, and ion conductive glass.

  Furthermore, for example, a conventional nonaqueous solvent-based electrolytic solution is used as the electrolytic solution of the nonaqueous electrolyte secondary battery without any particular limitation. Among these, the electrolyte solution of a secondary battery comprising a non-aqueous electrolyte solution containing an alkali metal salt includes propylene carbonate, ethylene carbonate, γ-butyrolactone, N-methylpyrrolidone, acetonitrile, N, N-dimethylformamide, dimethylsulfate. For example, foxoxide, tetrahydrofuran, 1,3-dioxolane, methyl formate, sulfolane, oxazolidone, thionyl chloride, 1,2-dimethoxyethane, diethylene carbonate, and derivatives and mixtures thereof are preferably used. The electrolyte contained in the electrolyte includes alkali metal, especially calcium halide, perchlorate, thiocyanate, borofluoride, phosphofluoride, arsenic fluoride, aluminum fluoride, trifluoromethyl sulfate, etc. Is preferably used.

It is a schematic sectional drawing of the 1st example of the nonaqueous electrolyte secondary battery using the positive electrode active material by one Embodiment of this invention. FIG. 2 is an enlarged sectional view of a part of a wound electrode body shown in FIG. 1. It is the schematic of the 2nd example of the nonaqueous electrolyte secondary battery using the positive electrode active material by one Embodiment of this invention. FIG. 4 is an enlarged cross section of a part of the battery element shown in FIG. 3. It is a graph which shows the measurement result of the alternating current resistance of a secondary battery.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Battery can 2 ... Positive electrode 2A ... Positive electrode collector 2B ... Positive electrode mixture layer 3 .... Negative electrode 3A ... Negative electrode collector 3B ... Negative electrode mixture Layer 4... Separator 5, 6. ..Center pin 13 ... Positive lead 14 ... Negative lead 20 ... Wound electrode body 30 ... Battery element 32 ... Positive lead 33 ... Negative lead 34, 35 ... Resin 35 ... Negative electrode lead 36 ... Recess 37 ... Exterior material 42 ... Positive electrode 42A ... Positive electrode current collector 42B ... Positive electrode mixture layer 43 ... Negative electrode 43A ... Negative electrode current collector 43B ...・ Negative electrode mixture layer 44 ... Separator 45 ... Gel electrolyte layer

Claims (20)

Composite oxide particles containing at least lithium (Li) and cobalt (Co);
A coating layer made of an oxide provided on at least a part of the composite oxide particles and including lithium (Li) and at least one coating element of nickel (Ni) and manganese (Mn);
A surface layer made of an oxide of at least one element of silicon (Si), aluminum (Al), Ti (titanium), and zirconium (Zr), provided on at least a part of the coating layer;
A positive electrode active material for a nonaqueous electrolyte secondary battery. 2. The positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1, wherein the composite oxide particles have an average composition represented by Chemical Formula 1 or Chemical Formula 2. 3.
(Chemical formula 1)
_{Li (1 + W) Co (} 1-xy) Ma x Mb y O (2-z)
(In the chemical formula 1, Ma is Bi (bismuth) or Ga (gallium), Mb is vanadium (V), chromium (Cr), boron (B), manganese (Mn), iron (Fe), nickel (Ni), Copper (Cu), zinc (Zn), aluminum (Al), magnesium (Mg), titanium (Ti), zirconium (Zr), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), It is composed of at least one element selected from the group consisting of yttrium (Y) and tungsten (W), and w, x, y, and z are −0.10 ≦ w ≦ 0.10, 0.001 <x < 0.10, 0 ≦ y <0.40, −0.10 ≦ z ≦ 0.20)
(Chemical formula 2)
Li _{(1 + W)} Co _(1-xy) Mc _x Md _y O _(2-z)
(In the chemical formula 2, Mc is Mg (magnesium), Al (aluminum), Ti (titanium), Zr (zirconium), Md is vanadium (V), chromium (Cr), boron (B), manganese (Mn), From iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), yttrium (Y), tungsten (W) It is composed of at least one selected element, and w, x, y, and z are −0.10 ≦ w ≦ 0.10, 0.001 <x <0.10, 0 ≦ y <0.40, −0 .10 ≦ z ≦ 0.20) 2. The non-aqueous electrolyte 2 according to claim 1, wherein the composition ratio of the nickel (Ni) and the manganese (Mn) in the coating layer is in a range of 100: 0 to 30:70 in terms of molar ratio. Positive electrode active material for secondary battery. The oxide of the coating layer comprises 40 mol% or less of the total amount of nickel (Ni) and manganese (Mn), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V ), Chromium (Cr), iron (Fe), cobalt (Co), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), tungsten (W 2) a positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1, wherein the positive electrode active material is replaced with at least one metal element selected from the group consisting of yttrium (Y) and zirconium (Zr). . 2. The nonaqueous electrolyte secondary according to claim 1, wherein the amount of deposited element of the coating layer is in the range of 0.5 mol% or more and 50 mol% or less with respect to the number of moles of metal of the composite oxide particles. Positive electrode active material for batteries.   2. The positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1, wherein a primary average particle diameter of the metal oxide particles forming the coating layer is 1.0 nm or more and 100 nm or less. 2. The non-aqueous electrolyte secondary battery according to claim 1, wherein the metal oxide particles forming the coating layer are 0.01 mol% or more and 10 mol% or less with respect to the metal element of the composite oxide particles. Positive electrode active material. 2. The positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1, wherein an average particle diameter is in a range of 2.0 μm to 50 μm. After forming a layer made of a hydroxide containing nickel (Ni) and / or manganese (Mn) on at least a part of the composite oxide particles containing at least lithium (Li) and cobalt (Co), the composite oxide Forming a hydroxide of at least one element of silicon (Si), aluminum (Al), Ti (titanium), and zirconium (Zr) on at least a part of the product particles;
The composite oxide is formed by forming a hydroxide of at least one element of the silicon (Si), the aluminum (Al), the Ti (titanium), and the zirconium (Zr), followed by heat treatment. A coating layer made of an oxide containing lithium (Li) and at least one coating element of nickel (Ni) and manganese (Mn) on at least a part of the particles, and silicon (Si) and aluminum (Al) Forming a surface layer made of an oxide of at least one element of Ti (titanium) and zirconium (Zr);
The manufacturing method of the positive electrode active material for nonaqueous electrolyte secondary batteries characterized by having. The method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 9, wherein the composite oxide particles have an average composition represented by chemical formula 1 or chemical formula 2.
(Chemical formula 1)
_{Li (1 + W) Co (} 1-xy) Ma x Mb y O (2-z)
(In the chemical formula 1, Ma is Bi (bismuth) or Ga (gallium), Mb is vanadium (V), chromium (Cr), boron (B), manganese (Mn), iron (Fe), nickel (Ni), Copper (Cu), zinc (Zn), aluminum (Al), magnesium (Mg), titanium (Ti), zirconium (Zr), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), It is composed of at least one element selected from the group consisting of yttrium (Y) and tungsten (W), and w, x, y, and z are −0.10 ≦ w ≦ 0.10, 0.001 <x < 0.10, 0 ≦ y <0.40, −0.10 ≦ z ≦ 0.20)
(Chemical formula 2)
Li _{(1 + W)} Co _(1-xy) Mc _x Md _y O _(2-z)
(In the chemical formula 2, Mc is Mg (magnesium), Al (aluminum), Ti (titanium), Zr (zirconium), Md is vanadium (V), chromium (Cr), boron (B), manganese (Mn), From iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), yttrium (Y), tungsten (W) It is composed of at least one selected element, and w, x, y, and z are −0.10 ≦ w ≦ 0.10, 0.001 <x <0.10, 0 ≦ y <0.40, −0 .10 ≦ z ≦ 0.20) The deposition of the hydroxide containing nickel (Ni) and / or manganese (Mn)
10. The composite oxide particles according to claim 9, wherein the composite oxide particles are dispersed in a water-based solvent having a pH of 12 or more, and then a nickel (Ni) compound and / or a manganese (Mn) compound is added. A method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery. 12. The method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 11, wherein the water-based solvent contains lithium hydroxide. 10. The non-aqueous electrolyte 2 according to claim 9, wherein a composition ratio of the nickel (Ni) and the manganese (Mn) in the coating layer is in a range of 100: 0 to 30:70 in terms of molar ratio. A method for producing a positive electrode active material for a secondary battery. The oxide of the coating layer comprises 40 mol% or less of the total amount of nickel (Ni) and manganese (Mn), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V ), Chromium (Cr), iron (Fe), cobalt (Co), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), tungsten (W ), At least one metal element selected from the group consisting of yttrium (Y) and zirconium (Zr), and a positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 9 Manufacturing method. 10. The nonaqueous electrolyte secondary according to claim 9, wherein the amount of deposited element of the coating layer is in the range of 0.5 mol% or more and 50 mol% or less with respect to the number of moles of metal of the composite oxide particles. A method for producing a positive electrode active material for a battery. The method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 9, wherein the primary average particle diameter of the metal oxide particles forming the coating layer is 1.0 nm or more and 100 nm or less. 10. The non-aqueous electrolyte secondary battery according to claim 9, wherein the metal oxide particles forming the coating layer are 0.01 mol% or more and 10 mol% or less with respect to the metal element of the composite oxide particles. A method for producing a positive electrode active material. The positive electrode active material for a nonaqueous electrolyte secondary battery according to claim 9, wherein the positive electrode active material for the nonaqueous electrolyte secondary battery has an average particle size in the range of 2.0 µm to 50 µm. Method. Forming a layer made of a hydroxide containing nickel (Ni) and / or manganese (Mn) on at least a part of the composite oxide particles containing at least lithium (Li) and cobalt (Co);
The surface of the composite oxide particle is coated with an oxide of at least one element selected from silicon (Si), aluminum (Al), Ti (titanium), and zirconium (Zr), and then heat-treated, A coating layer made of an oxide containing lithium (Li) and at least one coating element of nickel (Ni) and manganese (Mn) on at least part of the composite oxide particles, and silicon (Si), aluminum Forming a surface layer made of an oxide of at least one element selected from (Al), Ti (titanium), and zirconium (Zr);
The manufacturing method of the positive electrode active material for nonaqueous electrolyte secondary batteries characterized by having. A positive electrode having a positive electrode active material for a non-aqueous electrolyte secondary battery, a negative electrode, and an electrolyte;
The positive electrode active material for a non-aqueous electrolyte secondary battery is
Composite oxide particles containing at least lithium (Li) and cobalt (Co);
A coating layer made of an oxide provided on at least a part of the composite oxide particles and including lithium (Li) and at least one coating element of nickel (Ni) and manganese (Mn);
A surface layer made of an oxide of at least one element of silicon (Si), aluminum (Al), Ti (titanium), and zirconium (Zr), provided on at least a part of the coating layer;
A non-aqueous electrolyte secondary battery comprising:

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