JP5741970B2 - Lithium composite compound particle powder and method for producing the same, non-aqueous electrolyte secondary battery - Google Patents

Description

  The present invention provides a positive electrode active material having a high capacity, excellent cycle characteristics and high temperature stability as a positive electrode active material of a secondary battery.

  In recent years, electronic devices such as AV devices and personal computers are rapidly becoming portable and cordless, and there is an increasing demand for secondary batteries having a small size, light weight, and high energy density as power sources for driving these devices. Under such circumstances, a lithium ion secondary battery having advantages such as a high charge / discharge voltage and a large charge / discharge capacity has attracted attention.

Conventionally, as a positive electrode active material useful for a high energy type lithium ion secondary battery having a voltage of 4 V class, spinel type structure LiMn ₂ O ₄ , rock salt type structure LiMnO ₂ , LiCoO ₂ , LiCo _1-X Ni _X O ₂ , LiNiO ₂ , olivine-type LiFePO 4, and the like are generally known. However, any positive electrode active material is required to further improve characteristics.

  That is, since a device that operates with a secondary battery such as a notebook computer becomes hot as it is used, it is required that the secondary battery has excellent charge / discharge cycle characteristics at high temperatures. Further, in the case of a high voltage, reaction with the electrolytic solution is likely to occur, and charge / discharge cycle characteristics are likely to be deteriorated.

  Therefore, a positive electrode active material excellent in charge / discharge cycle characteristics at a high temperature is required.

  Conventionally, in order to improve the characteristics of a secondary battery, an aluminum compound added to a non-aqueous electrolyte is known (Patent Document 1). In addition, halogenation of the lithium cobaltate particle surface (Patent Document 2), mixing of various raw materials and halides, and firing to contain a gradient of halogen in the particles to suppress reaction with the electrolyte Technology (Patent Documents 3 to 5), Technology of stabilizing the structure by suppressing the reaction with the electrolytic solution on the particle surface by surface-treating an oxide on the particle surface such as lithium cobaltate (Patent Document 6) ~ 8) are known respectively.

Japanese Patent Laid-Open No. 10-255837 JP-A-6-333565 JP 2007-95571 A JP 2000-149925 A JP 2000-203843 A JP 2001-28265 A JP 2002-151077 A JP 2002-151078 A

  A positive electrode active material that satisfies the above-mentioned properties is currently most demanded, but has not yet been obtained.

  That is, in Patent Document 1 (Japanese Patent Laid-Open No. 10-255837), a coating on the negative electrode is formed by adding a compound such as an oxide of aluminum to the electrolytic solution to suppress the deterioration of the negative electrode. Although described, it does not lead to suppression of dissolution and structural breakdown on the surface of the positive electrode, and thus it is difficult to say that high rate charge / discharge cycle characteristics at high voltage are sufficient.

  Further, in Patent Document 2 (Japanese Patent Laid-Open No. 6-333565), the surface of the lithium cobaltate particles is halogenated to inactivate the active groups on the surface, thereby suppressing the reaction with the electrolytic solution and improving the storage characteristics. Although it is described as improving, high rate charge / discharge because it is not sufficient to protect the particles from the electrolyte because it cannot perform uniform and reproducible surface treatment on any particle surface It is hard to say that the cycle characteristics are excellent.

  Further, in the above-mentioned Patent Documents 3 to 5 (JP 2007-95571 A, JP 2000-149925 A and JP 2000-203843 A), by firing together with halides during firing of various raw materials, Although it is described that halogen is contained in the particles in a gradient manner to suppress the reaction with the electrolytic solution, this method increases the halogen content and increases the oxygen substitution amount. It is difficult to say that the characteristics are sufficient because the original high capacity cannot be obtained.

  Further, in the aforementioned Patent Documents 6 to 8 (JP 2001-28265 A, JP 2002-151077 A and JP 2002-151078 A), the surface of the particles is subjected to a surface treatment with an oxide, Although it is said that the reaction with the electrolyte on the particle surface is suppressed, the structure is stabilized, and the cycle characteristics can be improved, this method can suppress the reaction with the electrolyte, but the crystal structure Therefore, the characteristics are insufficient to improve the high rate cycle characteristics at the intended high charge voltage.

  Therefore, the present invention has a technical problem to obtain a positive electrode active material that is excellent in initial discharge capacity and excellent in charge / discharge cycle characteristics at a high rate.

  The technical problem can be achieved by the present invention as follows.

That is, the present invention uses, as core particles, a composite oxide composed of a lithium-transition metal element (TM) having an average primary particle diameter of 0.1 μm or more and an average secondary particle diameter of 1 to 20 μm. A lithium composite compound particle powder having a surface treatment component containing at least fluorine and a metal element A (A is at least one element selected from Li, Mg, Al, Zn, Y) on the surface, The composite oxide composed of lithium-transition metal element (TM) as the core particle is a lithium composite compound having the following composition 1, the composition of the surface treatment component is an AFO compound, and is a core particle. The content of element A with respect to the composite oxide composed of lithium-transition metal element (TM) is 0.01 to 1.0 atomic%, and the surface of the lithium composite compound particle powder is time-of-flight secondary The cation intensity ratio (Li ₂ F ⁺ / Li ₃ O ⁺ ) when analyzed with an ion mass spectrometer is 1.0 to 100, and the ions of the transition metal element and the metal element (A) of the surface treatment component It is a lithium composite compound particle powder characterized by having an intensity ratio (A ⁺ / TM ⁺ ) to ions of 1.0 to 1000 and a powder pH of 11.5 or less (Invention 1).
(Composition 1)
Li _{1 + x} Mn _2-c M3 _c O ₄
M3: At least one element selected from Li, B, Mg, Al, Ti, Co, Ni, Zr, and Sn (0 ≦ x ≦ 0.3), (0 ≦ c ≦ 0.6)

  Further, the present invention provides an aqueous suspension containing a composite oxide composed of lithium-transition metal element (TM), which is a core particle, as a raw material for A element sulfate, nitrate, hydrochloride, oxalate or A Using an alkoxide of an element and a fluorine-containing solution as a neutralizing agent, the addition ratio of the metal salt of element A to fluorine is 1: After precipitating a surface treatment component containing at least element A and fluorine with k (valence of element A ≦ k ≦ valence of element × 2), in a temperature range of 300 to 700 ° C. in an oxygen atmosphere. It is a manufacturing method of the lithium composite compound particle powder of this invention 1 which heat-processes (this invention 2).

  Further, the present invention is a non-aqueous electrolyte secondary battery using a positive electrode containing a positive electrode active material made of the lithium composite compound particle powder according to the first invention (Invention 3).

  The lithium composite compound particle powder according to the present invention allows a surface treatment component having excellent acid resistance to be uniformly present on the particle surface, suppresses deterioration of the particle surface due to charging and cycling, and protects the particle surface from strong acid. In addition, it is suitable as a positive electrode active material for a secondary battery that can suppress the destruction of the crystal structure and has excellent cycle characteristics at a high rate by using a small amount of treatment.

  The configuration of the present invention will be described in more detail as follows.

  First, the lithium composite compound particle powder according to the present invention will be described.

  The lithium composite compound particle powder according to the present invention has a composite oxide composed of lithium-transition metal element (TM) as a core particle, and at least fluorine and a metal element A (A is Li, Mg, Al on the particle surface of the core particle). And at least one element selected from Ti, Zn, Zr, and Y) in the presence of a surface treatment component.

In the lithium composite compound particle powder according to the present invention, when the particle surface is analyzed using a time-of-flight secondary ion mass spectrometer to determine the amount of the surface treatment component, the cation intensity ratio (Li ₂ F ⁺ / Li ₃ O ⁺ ) Is 1.0 to 100, and the intensity ratio (A ⁺ / TM ⁺ ) between the ions of the transition metal element and the metal element (A) of the surface treatment component is 1.0 to 1000.

When the cation intensity ratio (Li ₂ F ⁺ / Li ₃ O ⁺ ) is less than 1.0, there is no surface treatment component sufficient to sufficiently protect the surface, so that the intended effect of the present invention is obtained. Absent. When it exceeds 100, since there are too many surface treatment components, the cycle characteristics at a high rate deteriorate. The cation strength ratio is preferably 1.0 to 80, more preferably 2.0 to 60.

When the intensity ratio (A ⁺ / TM ⁺ ) between the ions of the transition metal element (TM) and the metal element (A) of the surface treatment component is less than 1.0, the surface treatment is sufficient to sufficiently protect the surface. Since the component does not exist, the intended effect of the present invention cannot be obtained. If it exceeds 1000, there are too many surface treatment components, so that the cycle characteristics at a high rate deteriorate. The strength ratio (A ⁺ / TM ⁺ ) is preferably 1.0 to 500, more preferably 1.10 to 300, and still more preferably 1.20 to 100.

When the composite oxide composed of lithium-transition metal element (TM) as the core particle is a lithium cobalt-containing composite oxide as shown in composition 1, the strength ratio of A ⁺ / Co ⁺ is 1.0. -100 is preferable, More preferably, it is 1.25-95.

  In the present invention, the content of element A in the surface treatment component with respect to the composite oxide composed of lithium-transition metal element (TM) as the core particle is preferably 0.01 to 1.0 atomic%. When the ratio is less than 0.01 atomic%, there is no surface treatment component that can be sufficiently protected from the electrolytic solution, and thus the intended effect of the present invention cannot be obtained. When it exceeds 1.0 atomic%, the surface characteristics are too much, so that the cycle characteristics are deteriorated. The content of element A in the surface treatment component is more preferably 0.02 to 0.98 atomic%, and even more preferably 0.03 to 0.95 atomic%.

  The average secondary particle diameter of the composite oxide comprising lithium-transition metal element (TM) in the present invention is 1.0 to 20 μm. When the average secondary particle diameter is less than 1.0 μm, the filling density is lowered and the reactivity with the electrolytic solution is increased, which is not preferable. When the thickness exceeds 20 μm, the diffusion distance of lithium ions is extended, so that the conductivity is lowered and the cycle characteristics are deteriorated, so that the intended effect cannot be obtained.

  The average primary particle diameter of the composite oxide comprising lithium-transition metal element (TM) in the present invention is 0.1 μm or more. When the average particle diameter is less than 0.1 μm, the crystallinity is poor and the cycle is deteriorated. On the other hand, if the average primary particle diameter exceeds 15 μm, the diffusion of lithium is inhibited, and this also causes cycle deterioration. That is, the average primary particle diameter is more preferably 0.1 to 15 μm.

  In the present invention, the fluorine is preferably segregated on the surface side of the lithium composite compound particles. When fluorine exists uniformly inside the particles, it is difficult to obtain the intended effect of the present invention.

  The powder pH of the lithium composite compound particle powder according to the present invention is preferably 11.5 or less. When the pH of the powder exceeds 11.5, the viscosity increases at the time of preparing the electrode, the uniformity is lost, and the intended effect cannot be obtained. Preferably it is 11.0 or less, More preferably, pH is 10.8 or less.

The BET specific surface area of the lithium composite compound particle powder according to the present invention is preferably 0.1 to 1.5 m ² / g. When the BET specific surface area value is less than 0.1 m ² / g, it is difficult to produce industrially. If it exceeds 1.5 m ² / g, the filling density is lowered and the reactivity with the electrolytic solution is increased.

  In the present invention, the composite oxide composed of lithium-transition metal element (TM) which is the core particle is a lithium manganese-containing composite oxide represented by composition 3. In addition, what is normally used for the positive electrode active material of a nonaqueous electrolyte secondary battery may be used. For example, a lithium cobalt-containing composite oxide as shown in composition 2, a lithium nickel-containing composite oxide as shown in composition 3, and a lithium iron-containing composite oxide as shown in composition 4.

(Composition 1)
Li _{1 + x} Mn _2-c M3 _c O ₄
M3: At least one element selected from Li, B, Mg, Al, Ti, Co, Ni, Zr, Sn (0 ≦ x ≦ 0.3), (0 ≦ c ≦ 0.6)

(Composition 2)
Li _{1 + x} Co _1-a M1 _a O ₂
M1: At least one element selected from Mg, Al, Ti, Mn, Ni, Zr, and Sn (−0.05 ≦ x ≦ 0.05), (0 ≦ a ≦ 0.3)

(Composition 3)
Li _{1 + x} Ni _1-b M2 _b O ₂
M2: At least one element selected from Mg, Al, Ti, Mn, Co, Zr, and Sn (−0.05 ≦ x ≦ 0.05), (0 ≦ b ≦ 0.7)

In the composition 3, when Co and Mn are used as the M2 element, the following composition formula (3-1) is preferable.
(Composition 3-1)
_{Li 1 + x Ni 1-b1} -b2 Co b1 Mn b2 O 2
(−0.05 ≦ x ≦ 0.20), (0 ≦ b1 ≦ 0.35, 0.1 ≦ b2 ≦ 0.5)

In the composition 3, when Co and Al are used as the M2 element, the following composition formula (3-2) is preferable.
(Composition 3-2)
Li _{1 + x} Ni _1-b1-b2 Co _b1 Al _b2 O ₂
(−0.05 ≦ x ≦ 0.15), (0.10 ≦ b1 ≦ 0.20, 0.01 ≦ b1 ≦ 0.10)

(Composition 4)
Li _{1 + x} Fe _1-d M4 _d PO ₄
M4: At least one element selected from Mg, Al, Mn, Co, Ni, Zr, and Sn (−0.05 ≦ x ≦ 0.05), (0 ≦ d ≦ 0.3)

  Of the surface treatment components, the metal element A is preferably at least one of Li, Al, Zn, Mg, and Y. Further, the composition of the surface treatment component is preferably an AFO compound.

  Next, a method for producing the lithium composite compound particle powder according to the present invention will be described.

  The lithium composite compound particle powder according to the present invention comprises an aqueous suspension containing a composite oxide composed of lithium-transition metal element (TM), which is a core particle, as a raw material for A element sulfate, nitrate, hydrochloride, Add oxalate or alkoxide of element A, and use fluorine-containing solution as neutralizing agent, and contain at least element A and fluorine on the particle surface of the composite oxide composed of lithium-transition metal element (TM) After the surface treatment component to be deposited is deposited, the surface treatment component is obtained by heat treatment in an oxygen atmosphere at a temperature range of 300 to 700 ° C.

  The lithium-cobalt-containing composite oxide, lithium-nickel-containing composite oxide, lithium-manganese-containing composite oxide, or lithium-iron-containing composite oxide, which is the core particle in the present invention, is obtained by a normal method. A solid phase method obtained by mixing and heating a compound and a cobalt compound, or a wet method for obtaining lithium cobaltate particles by reacting a lithium compound and a cobalt compound in a solution may be used.

  The elements M1 to M4 present in the composite oxide composed of a lithium-transition metal element are at least one element selected from Li, B, Mg, Al, Ti, Mn, Co, Ni, Zr, and Sn. is there. In the present invention, the elements M1 to M4 corresponding to the respective compositions 1 to 4 may be simultaneously present during the reaction of the composite oxide composed of the lithium-transition metal element.

The composite oxide composed of lithium-transition metal element (TM) has a primary particle size of 0.1 μm or more, an average secondary particle size of 1 to 20 μm, a BET specific surface area value of 0.1 to 1.5 m ² / g, The Li / TM ratio is preferably 0.5 to 0.65 in the case of a spinel structure, and preferably 0.95 to 1.20 in cases other than the spinel structure.

  As the raw material for the A element, an A element sulfate, nitrate, hydrochloride, oxalate, or A element alkoxide can be used. For example, in the case of aluminum, aluminum sulfate, aluminum nitrate, sodium aluminate, or the like can be used.

  The amount of element A added is preferably 0.01 to 1.0 mol% with respect to the composite oxide composed of a lithium-transition metal element.

  After adding the element A raw material, a fluorine-containing solution is added to deposit a surface treatment component containing at least element A and fluorine on the particle surface of the composite oxide composed of lithium-transition metal element (TM). . As the fluorine-containing solution, ammonium fluoride, sodium fluoroacetate solution, allyl fluoride solution, or the like is used.

  The addition amount of the fluorine-containing solution is preferably such that the addition ratio of the metal salt of element A and fluorine is 1: k (valence of element A ≦ k ≦ valence of element A × 2). When the addition amount of the fluorine-containing solution is out of the above range, the intended effect of the present invention cannot be obtained.

  The pH of the aqueous suspension is adjusted by adding a raw material of element A and a fluorine-containing solution to an aqueous suspension containing a composite oxide composed of lithium-transition metal element (TM). A surface treatment component containing at least element A and fluorine is deposited on the particle surface of the complex oxide composed of the element (TM). The pH of the aqueous solution is preferably 6.0 to 10.0. When the pH of the aqueous solution is outside the above range, it is difficult to generate and adsorb the surface treatment component.

Components precipitated by adjusting the pH of an aqueous suspension by adding a raw material of element A and a fluorine-containing solution to an aqueous suspension containing a composite oxide composed of a lithium-transition metal element (TM) Although not particularly limited, for example, (NH ₄ ) AlF ₄ , (NH ₄ ) ₃ AlF _{6, and the} like are included.

  In order to stabilize the surface treatment component on the particle surface of the core particle, the surface treatment component is preferably chemically bonded to the core particle, and heat treatment is required for this purpose. The heat treatment temperature is preferably 300 to 700 ° C. When the temperature is lower than 300 ° C., hydroxide and hydrate remain, and when the temperature exceeds 700 ° C., the element A and fluorine atoms begin to infiltrate inside the particles, which is not preferable. A more preferable heat treatment temperature is 350 to 650 ° C. The holding time is preferably 1 to 5 hours. When it is shorter than 1 hour, the decomposition reaction is insufficient, and when it is longer than 5 hours, it is not preferable from the viewpoint of productivity and cost.

  The stable substance that binds to the core particles thus obtained and protects the surface preferably takes the form of a compound of element A, oxygen (O), and fluorine (F).

  As the atmosphere of the heat treatment, carbon dioxide gas is not preferable because it causes gas generation inside the battery, and heat treatment in an oxygen atmosphere is preferable in order to promote the formation of a stable AFO compound. .

  Next, a positive electrode using a positive electrode active material made of a lithium-containing composite oxide according to the present invention will be described.

  When a positive electrode is produced using the positive electrode active material in the present invention, a conductive agent and a binder are added and mixed according to a conventional method. As the conductive agent, acetylene black, carbon black, graphite and the like are preferable, and as the binder, polytetrafluoroethylene, polyvinylidene fluoride and the like are preferable.

  The secondary battery manufactured using the positive electrode active material in this invention is comprised from the said positive electrode, a negative electrode, and electrolyte.

  As the negative electrode active material, lithium metal, lithium / aluminum alloy, lithium / tin alloy, graphite, graphite, or the like can be used.

  In addition to the combination of ethylene carbonate and diethyl carbonate, an organic solvent containing at least one of carbonates such as propylene carbonate and dimethyl carbonate and ethers such as dimethoxyethane can be used as the solvent for the electrolytic solution.

  Further, as the electrolyte, in addition to lithium hexafluorophosphate, at least one lithium salt such as lithium perchlorate and lithium tetrafluoroborate can be dissolved in the above solvent and used.

<Action>
The most important point in the present invention is that the lithium composite compound particle powder according to the present invention has fluorine and metal element A (on the part of the particle surface of the composite oxide composed of lithium-transition metal element (TM) as core particles). A is a surface treatment component containing at least one element selected from Li, Mg, Al, Ti, Zn, Zr, and Y), thereby providing an initial discharge capacity as a secondary battery at a high charge voltage. The high-rate charge / discharge cycle characteristics are excellent.

  In the present invention, a fluorine-containing colloid of a fine metal element A is generated and adsorbed on the surface of the composite oxide particle composed of lithium-transition metal element (TM) by a wet reaction, and then heat-treated in an oxygen atmosphere. Thus, a thin surface treatment component containing fluorine and a compound of metal element A is formed on the particle surface, and a part of them is chemically combined with the particle surface of the composite oxide composed of lithium-transition metal element (TM). By bonding, the structure can be stabilized while protecting the particle surface.

  In the present invention, the initial discharge capacity can be maintained by charging and discharging at a high charge voltage, as long as the initial discharge capacity of the original composite oxide composed of lithium-transition metal element (TM) is not lowered. The present inventor presumes that this is due to the fact that a compound composed of element A, oxygen, and fluorine is bonded to A.

  In the present invention, the high rate cycle characteristics can be improved at a high charge voltage by stabilizing a structural change accompanying charging / discharging of the particle surface while a part of the surface of the active material particle is coated with a stable substance. This is because the reaction with the electrolytic solution (oxidative decomposition) is suppressed and structural destruction is suppressed.

  A typical embodiment of the present invention is as follows.

  Powder X-ray diffraction (RIGAKU Cu-Kα 40 kV 40 mA) was used for identification of the product after the surface treatment and after firing. The lattice constant was calculated from each diffraction peak of the powder X-ray diffraction.

  In addition, a plasma emission analyzer (SEPS Electronics SPS4000) was used for elemental analysis.

  The powder pH was obtained by suspending 0.5 g of powder in 25 ml of distilled water and allowing to stand at room temperature to measure the pH value of the suspension.

The average secondary particle size is a volume-based average particle size measured by a wet laser method using a laser type particle size distribution analyzer LMS-30 [manufactured by Seishin Enterprise Co., Ltd.].
The average primary particle size was judged by a scanning electron microscope SEM.

The presence state of the particles to be coated or present is determined by scanning electron microscope SEM-EDX with energy dispersive X-ray analyzer [manufactured by Hitachi High-Technologies Corporation] and time-of-flight secondary ion mass spectrometer TOF-SIMS5 [ION-TOF Co., Ltd.] Observed]. The intensity ratio (A ⁺ / TM ⁺ ) is the intensity ratio based on the transition metal present in the largest amount in the core particle when a composite oxide composed of a plurality of types of transition metals is used as the core particle. When equimolar transition metals exist, the one having the maximum value in the intensity ratio (A ⁺ / TM ⁺ ) in the time-of-flight secondary ion mass spectrometer was used.

  The average primary particle diameter of the particles to be coated or present was observed and confirmed using a scanning electron microscope SEM-EDX with an energy dispersive X-ray analyzer [manufactured by Hitachi High-Technologies Corporation].

  The battery characteristics of the positive electrode active material were evaluated by preparing a positive electrode, a negative electrode, and an electrolytic solution by the following production method to produce a coin-type battery cell.

<Preparation of positive electrode>
A positive electrode active material, acetylene black as a conductive agent, and polyvinylidene fluoride as a binder are precisely weighed so that the weight ratio is 85: 10: 5, and thoroughly mixed in a mortar, and then N-methyl-2-pyrrolidone. The positive electrode mixture slurry was prepared by dispersing in the mixture. Next, this slurry was applied to an aluminum foil as a current collector with a film thickness of 150 μm, vacuum-dried at 150 ° C., and then punched into a disk shape of φ16 mm to obtain a positive electrode plate.

<Production of negative electrode>
A metal lithium foil was punched into a disk shape of φ16 mm to produce a negative electrode.

<Preparation of electrolyte>
An electrolyte solution was prepared by mixing 1 mol / liter of lithium hexafluorophosphate (LiPF ₆ ) as an electrolyte in a mixed solution of ethylene carbonate and diethyl carbonate in a volume ratio of 50:50.

<Assembly of coin-type battery cells>
Using a case made of SUS316 in a glove box in an argon atmosphere, a CR2032-type coin battery was manufactured by injecting an electrolyte solution through a polypropylene separator between the positive electrode and the negative electrode.

<Battery evaluation>
A charge / discharge test of a secondary battery was performed using the coin-type battery. As measurement conditions, at room temperature, the measurement rate is 1.0 C, and the cut-off voltage is 3.0 to 4.3 V for cobalt, manganese, and nickel, and 2.5 to 4.3 V for olivine. Charging / discharging was repeated between. When the rate is 1.0 C, charging and discharging is performed in a shorter time than when 0.2 C or the like (1 C is performed in 1 hour, 0.2 C is performed in 5 hours), and large. Charging / discharging is performed at current density.

Reference example 1
Tricobalt tetroxide containing Mg and Al and lithium carbonate were mixed at a predetermined ratio and kept in air at 990 ° C. for 8 hours to obtain a lithium-containing composite oxide (average primary particle diameter 5 μm, average secondary particles Diameter 15.3 μm). Using the obtained lithium-containing composite oxide, 100 g is suspended in 100 ml of a 0.020 mol / L aluminum nitrate solution. After holding for 30 minutes, 8 ml of a 1 mol / L ammonium fluoride solution was added so that the ratio of aluminum to fluorine was 1: 4 and held for 30 minutes. The temperature was raised to 80 ° C. and held for 12 hours, and then taken out and washed with water. Subsequently, it was dried at 110 ° C. for 12 hours, and then heat-treated at 400 ° C. for 5 hours in an oxygen atmosphere.
The Al concentration in the reaction solution of the surface treatment is 0.020 mol / l, the F concentration is 1.000 mol / l, and the A element reacts at a low concentration of 0.05 mol / l or less in the reaction solution. Went.

The obtained lithium composite compound particle powder was subjected to composition analysis of the particle cross section, and it was confirmed that fluorine was present on the particle surface. Moreover, as a result of evaluation by a time-of-flight secondary ion mass spectrometer, the ratio of Li ₂ F ⁺ / Li ₃ O ⁺ is 8.701, and the ratio of Al + / Co + is 5.882, The presence of F and Al was confirmed.

Further, the lithium composite compound after the lithium-containing composite oxide and the surface treatment before suspension in a liquid, _AlF 2 O ^- component of the intensity, respectively 4.8 × ¹⁰ -4, 5.5 × ^{10 -3} and increased by the surface treatment, and it was confirmed that a complex oxide component composed of Al, O, and F was formed on the surface.

Reference example 2
In the same manner as in Reference Example 1, tricobalt tetroxide containing Mg and Al and lithium carbonate were mixed at a predetermined ratio, and kept in air at 990 ° C. for 8 hours to obtain a lithium-containing composite oxide. Using the obtained lithium-containing composite oxide, 100 g is suspended in 100 ml of a 0.005 mol / L lithium nitrate solution. After holding for 30 minutes, 2 ml of a 0.5 mol / L ammonium fluoride solution was added so that the ratio of lithium to fluorine was 1: 1.50, and the mixture was held for 30 minutes. When the temperature was raised to 80 ° C. and held for 12 hours, it was taken out, washed with water, and dried at 110 ° C. for 12 hours. Thereafter, heat treatment was performed at 400 ° C. for 5 hours in an oxygen atmosphere.

Reference example 3
In the same manner as in Reference Example 1, tricobalt tetroxide containing Mg and Al and lithium carbonate were mixed at a predetermined ratio, and kept in air at 990 ° C. for 8 hours to obtain a lithium-containing composite oxide. Using the obtained lithium-containing composite oxide, 100 g was suspended in 100 ml of a 0.04 mol / L aluminum sulfate solution. After maintaining for 30 minutes, 15 ml of a 1 mol / L ammonium fluoride solution was added so that the ratio of aluminum to fluorine was 1: 3.75 and maintained for 30 minutes. When the temperature was raised to 80 ° C. and held for 12 hours, it was taken out, washed with water, dried at 110 ° C. for 12 hours, and then heat-treated at 500 ° C. for 5 hours in an oxygen atmosphere.

Reference example 4
In the same manner as in Reference Example 1, tricobalt tetroxide containing Mg and Al and lithium carbonate were mixed at a predetermined ratio, and kept in air at 990 ° C. for 8 hours to obtain a lithium-containing composite oxide. Using the obtained lithium-containing composite oxide, 100 g was suspended in 100 ml of a 0.05 mol / L yttrium nitrate solution. After holding for 30 minutes, 23 ml of a 1 mol / L ammonium fluoride solution was added and held for 30 minutes so that the ratio of yttrium to fluorine was 1: 4.5. When the temperature was raised to 80 ° C. and held for 12 hours, it was taken out, washed with water, dried at 110 ° C. for 12 hours, and then heat-treated at 400 ° C. for 5 hours in an oxygen atmosphere.

Example 1
Trimanganese tetroxide containing Al and lithium carbonate were mixed at a predetermined ratio and kept in air at 900 ° C. for 8 hours to obtain a lithium-containing composite oxide (average primary particle size 2 μm, average secondary particle size 5 .7 μm). Using the obtained lithium-containing composite oxide, 100 g was suspended in 100 ml of 0.012 mol / L zinc sulfate solution. After holding for 30 minutes, 7 ml of a 0.5 mol / L ammonium fluoride solution was added so that the ratio of zinc to fluorine was 1: 3, and the mixture was held for 30 minutes. When the temperature was raised to 80 ° C. and held for 12 hours, it was taken out, washed with water, dried at 110 ° C. for 12 hours, and then heat-treated at 500 ° C. for 5 hours in an oxygen atmosphere.

Reference Example 5
In the same manner as in Reference Example 1, tricobalt tetroxide containing Mg and Al and lithium carbonate were mixed at a predetermined ratio, and kept in air at 990 ° C. for 8 hours to obtain a lithium-containing composite oxide. Using the obtained lithium-containing composite oxide, 100 g was suspended in 100 ml of a 0.015 mol / L zinc nitrate solution. After maintaining for 30 minutes, 10 ml of a 0.5 mol / L ammonium fluoride solution was added and maintained for 30 minutes so that the ratio of zinc to fluorine was 1: 3.4. When the temperature was raised to 80 ° C. and held for 12 hours, it was taken out and washed with water, and then heat treatment was performed at 550 ° C. for 5 hours in an oxygen atmosphere.

Reference Example 6
Lithium hydroxide was mixed with a hydroxide composed of cobalt, nickel, and aluminum at a predetermined ratio, and calcined at 750 ° C. for 20 hours in an oxygen atmosphere to obtain a lithium-containing composite oxide (average primary particle size 0.5 μm, Average secondary particle size 17 μm). Using the obtained lithium-containing composite oxide, 100 g was suspended in 100 ml of a 0.10 mol / L aqueous solution of aluminum chloride. After holding for 30 minutes, 27 ml of a 1.5 mol / L ammonium fluoride solution was added so that the ratio of aluminum to fluorine was 1: 4, and the mixture was held for 30 minutes. When the temperature was raised to 80 ° C. and held for 12 hours, it was taken out, washed with water, and dried. Thereafter, heat treatment was performed at 400 ° C. for 5 hours in an oxygen atmosphere.

Reference Example 7
Lithium carbonate was mixed with a hydroxide composed of cobalt, nickel, and manganese at a predetermined ratio, and calcined at 950 ° C. for 20 hours in an oxygen atmosphere to obtain a lithium-containing composite oxide (average primary particle size 0.5 μm, average Secondary particle diameter 10 μm). As shown in Table 1, the resulting lithium-containing composite was added to a suspension in which an ammonium fluoride solution was mixed so that the ratio of aluminum to fluorine was 1: 3 in 100 ml of a 0.025 mol / L aluminum nitrate solution. Oxide was added and held for 30 minutes. When the temperature was raised to 80 ° C. and held for 12 hours, it was taken out, washed with water, dried at 110 ° C. for 12 hours, and then heat-treated at 500 ° C. for 5 hours in an oxygen atmosphere.

Reference Example 8
Li _1.01 Fe was added to a suspension in which an ammonium fluoride solution was mixed so that the ratio of magnesium to fluorine was 1: 3.7 in 100 ml of magnesium nitrate solution at a ratio of 0.030 mol / L shown in Table 1. _0.98 Mn _0.02 PO ₄ powder was added and held for 30 minutes. When the temperature was raised to 80 ° C. and held for 12 hours, it was taken out, washed with water, dried at 110 ° C. for 12 hours, and then heat-treated at 400 ° C. for 5 hours in an oxygen atmosphere.

Comparative Example 1
This is a lithium-containing composite oxide obtained by mixing Mg and Al-containing tricobalt tetroxide and lithium carbonate at a predetermined ratio and holding in air at 990 ° C. for 8 hours. It is not.

Comparative Example 2
This is a lithium-containing composite oxide obtained by mixing trimanganese tetroxide containing Al and lithium carbonate at a predetermined ratio and keeping them in air at 900 ° C. for 8 hours, and the surface treatment of Example 1 is not performed. Is.

Comparative Example 3
A lithium-containing composite oxide obtained by mixing lithium hydroxide with a hydroxide composed of cobalt, nickel, and aluminum at a predetermined ratio and firing at 750 ° C. for 20 hours in an oxygen atmosphere. It is something that has not been done.

Comparative Example 4
In the same manner as in Reference Example 1, tricobalt tetroxide containing Mg and Al and lithium carbonate were mixed at a predetermined ratio, and kept in air at 990 ° C. for 8 hours to obtain a lithium-containing composite oxide. Using the resulting lithium-containing composite oxide, 100 g was suspended in 100 ml of a 0.02 mol / L sodium aluminate solution as shown in Table 1. After adjusting the pH with sulfuric acid, the powder was filtered and washed, and then heat-treated at 800 ° C. for 5 hours in air.

Comparative Example 5
In the same manner as in Reference Example 1, tricobalt tetroxide containing Mg and Al and lithium carbonate were mixed at a predetermined ratio, and kept in air at 990 ° C. for 8 hours to obtain a lithium-containing composite oxide. Using the obtained lithium-containing composite oxide, 100 g was suspended in 100 ml of a 0.01 mol / L aluminum nitrate solution as shown in Table 1. After holding for 30 minutes, an ammonium fluoride solution was added so that the ratio of aluminum to fluorine was 1: 2, and the mixture was held for 30 minutes. When it was kept at 30 ° C. and kept for 12 hours, it was taken out, washed with water, dried at 110 ° C. for 12 hours, and then heat-treated at 400 ° C. for 5 hours in a nitrogen atmosphere.

Comparative Example 6
In the same manner as in Reference Example 1, tricobalt tetroxide containing Mg and Al and lithium carbonate were mixed at a predetermined ratio, and kept in air at 990 ° C. for 8 hours to obtain a lithium-containing composite oxide. Using the obtained lithium-containing composite oxide, 100 g was suspended in 100 ml of a 0.12 mol / L aluminum nitrate solution as shown in Table 1. After holding for 30 minutes, an ammonium fluoride solution was added so that the ratio of aluminum to fluorine was 1: 2.90, and the mixture was held for 30 minutes. When the temperature was raised to 80 ° C. and held for 12 hours, it was taken out, washed with water, and dried at 110 ° C. for 12 hours. Thereafter, heat treatment was performed at 500 ° C. for 5 hours in an oxygen atmosphere.

Comparative Example 7
The same treatment as in Comparative Example 6 was performed except that the heat treatment was changed to a treatment for 5 hours at 500 ° C. under a nitrogen atmosphere.

Comparative Example 8
The surface-treated dried product obtained in Reference Example 6 was heat-treated at 400 ° C. for 5 hours in a nitrogen atmosphere.

Comparative Example 9
The surface-treated dried product obtained in Reference Example 6 was heat-treated at 800 ° C. for 5 hours in an oxygen atmosphere.

Comparative Example 10
Trimanganese tetroxide containing Al and lithium carbonate were mixed at a predetermined ratio and kept in air at 900 ° C. for 8 hours to obtain a lithium-containing composite oxide. Using the obtained lithium-containing composite oxide, 100 g was suspended in 100 ml of a 0.20 mol / L zinc nitrate solution as shown in Table 1. After holding for 30 minutes, an ammonium fluoride solution was added so that the ratio of zinc to fluorine was 1: 3, and the mixture was held for 30 minutes. When the temperature was raised to 80 ° C. and held for 12 hours, it was taken out, washed with water, dried at 110 ° C. for 12 hours, and then annealed at 400 ° C. for 5 hours in an oxygen atmosphere.

Comparative Example 11
Tricobalt tetroxide containing Mg and Al and lithium carbonate were mixed at a predetermined ratio and kept in air at 990 ° C. for 8 hours to obtain a lithium-containing composite oxide. 0.25 mol% LiF was added and mixed with respect to the obtained lithium containing complex oxide, and it heat-processed at 350 degreeC in the air.

Comparative Example 12
Lithium hydroxide and lithium fluoride are mixed with a hydroxide composed of cobalt, nickel, and aluminum so that Li _1.05 Ni _0.85 Co _0.10 Al _0.05 O _1.9989 F _0.0022 is obtained. And calcining at 750 ° C. for 20 hours in an oxygen atmosphere to obtain a lithium-containing composite oxide.

  Tables 1 and 2 show characteristics of the obtained positive electrode active material and battery characteristics of the coin-type battery.

  The battery characteristics of the coin battery produced using the lithium composite compound particle powder according to the present invention are at a level where the capacity retention rate after 30 cycles at a high rate (1C) in the coin battery is higher than the initial discharge capacity. . For example, Reference Examples 1 to 5 using a cobalt-based material exhibit a high capacity retention rate with respect to Comparative Examples 1, 4 to 7, and 11.

  By using the lithium composite compound particle powder according to the present invention, it is possible to obtain a nonaqueous electrolyte secondary battery that maintains an initial discharge capacity as a secondary battery and has improved high-temperature characteristics.

It is a cycle characteristic of a secondary battery using the lithium composite compound particle powder obtained in Reference Example 1 and Comparative Example 1. It is the cycle characteristic which is the cycle characteristic of the secondary battery using the lithium composite compound particle powder obtained in Example 1 and Comparative Example 2.

Claims (3)

A composite oxide composed of lithium-transition metal element (TM) having an average primary particle size of 0.1 μm or more and an average secondary particle size of 1 to 20 μm is used as a core particle, and at least fluorine and metal are present on the particle surface of the core particle. A lithium composite compound particle powder in which a surface treatment component containing an element A (A is at least one element selected from Li, Mg, Al, Zn, and Y) is present, transition composite oxide of a metal element (TM) is a lithium composite compound having the following composition 1, composition of the surface treatment component is the a-F- O of compound, lithium is the core particles - transition metal element ( The content of element A with respect to the composite oxide comprising TM) is 0.01 to 1.0 atomic%, and the surface of the lithium composite compound particle powder is subjected to a time-of-flight secondary ion mass spectrometer. When analyzed, the intensity ratio between the ion of the cation intensity ratio ^{_{(Li 2 F + / Li 3}} O +) is a metal element ion and the surface treatment component of the transition metal element as well as a 1.0 to 100 (A) (A ⁺ / TM ⁺ ) is 1.0 to 1000, and the powder pH is 11.5 or less.
(Composition 1)
Li _{1 + x} Mn _2-c M3 _c O ₄
M3: At least one element selected from Li, B, Mg, Al, Ti, Co, Ni, Zr, and Sn (0 ≦ x ≦ 0.3), (0 ≦ c ≦ 0.6) While using an element A sulfate, nitrate, hydrochloride, oxalate, or element A alkoxide as an A raw material in an aqueous suspension containing a composite oxide composed of lithium-transition metal element (TM) as a core particle Using a fluorine-containing solution as a neutralizing agent, the addition ratio of the metal salt of element A to fluorine is 1: k (valence of element A) on the particle surface of the composite oxide composed of lithium-transition metal element (TM). 2. A surface treatment component containing at least an A element and fluorine satisfying a number ≦ k ≦ A element valence × 2) is deposited, and then heat-treated at 300 to 700 ° C. in an oxygen atmosphere. The manufacturing method of lithium composite compound particle powder of description. A non-aqueous electrolyte secondary battery using a positive electrode containing a positive electrode active material comprising the lithium composite compound particle powder according to claim 1.

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