JP5491462B2 - ELECTRODE COMPOSITE MATERIAL, ITS MANUFACTURING METHOD, AND LITHIUM ION BATTERY USING THE SAME - Google Patents

Description

 The present invention relates to a lithium nickel manganese oxide composite material, a method for producing the same, and a lithium ion battery employing the same.

In recent years, in order to improve the characteristics of the positive electrode active material of a lithium ion battery, generally, the surface of the particles of the positive electrode active material is coated with another material. For example, LiFePO ₄ particles are coated with a carbon layer to improve the conductivity of LiFePO ₄ . In another example, lithium cobalt oxide (LiCoO ₂ ) particles are coated with an AlPO ₄ layer as a modified layer of the LiCoO ₂ to increase the thermal stability of the lithium cobalt oxide (Non-patent Document 1 and Patent Document) 1).

A conventional method of coating the surface of positive electrode active material particles with an AlPO ₄ layer includes a first step of producing AlPO ₄ particles, a second step of dispersing the AlPO ₄ particles in water, and forming a dispersion liquid, By adding the positive electrode active material particles to the dispersion of AlPO _4, a third step in which small AlPO ₄ particles are adsorbed on the surface of the large positive electrode active material particles, water of the dispersion of the AlPO ₄ and the positive electrode active material And a heat treatment at 700 ° C. to form a final AlPO ₄ and positive electrode active material composite material.

However, since AlPO ₄ cannot be dissolved in water, when small particles of AlPO ₄ are dispersed in water, they aggregate together. In this case, if a large amount of positive electrode active material particles are added, the positive electrode active material particles previously added are added. Most of the agglomerated AlPO ₄ particles are adsorbed on the surface, and sufficient AlPO ₄ particles are not adsorbed on the surface of the positive electrode active material particles added thereafter. Therefore, when the addition amount of the positive electrode active material particles is large, a composite material of the positive electrode active material particles having a non-uniform adsorption amount with respect to the AlPO ₄ particles is obtained. Since the composite material has many defects, the method cannot be applied to large-scale industrial production. Referring to FIG. 21, in the positive electrode active material composite particle 20, the positive electrode active material particle 22 coated with the AlPO ₄ particle 24 also has AlPO _{4 on} the surface of the large particle 22 of the positive electrode active material from a microscopic viewpoint. Since it is distributed in the form of small particles 24, an AlPO ₄ layer having irregularities is formed on the surface of the positive electrode active material particles 22. As a result, the stability and cycle characteristics of the lithium ion battery using the composite material composed of the positive electrode active material particles 20 become insufficient.

“Correlation between AlPO4 nanoparticulate coating thickness on LiCoO2 method and thermal stability” J. Cho, Electrochimica Acta 48 (2003) 2807-2811

US Pat. No. 7,326,498

 Therefore, in order to solve the above-mentioned problems, the present invention is such that the electrode active material particles in the electrode composite material are all coated with the modified layer, and the surface of the electrode active material particles is coated with the uniform modified layer. The present invention provides a composite material for an electrode, a method for producing the same, and a lithium ion battery employing the composite material.

The electrode composite material of the present invention includes a plurality of electrode active material particles. The electrode active material particles are Li _x Ni _1-y L _y O ₂ particles. An aluminum phosphate layer is uniformly and continuously coated on the surface of each electrode active material particle.

The lithium ion battery of the present invention includes a positive electrode, a negative electrode, and a nonaqueous electrolytic solution disposed between the positive electrode and the negative electrode. The positive electrode includes a composite material for electrodes. The electrode composite material includes a plurality of electrode active material particles. The electrode active material particles are Li _x Ni _1-y L _y O ₂ (wherein x and y satisfy 0.1 ≦ x ≦ 1.1 and 0 ≦ y <1). An aluminum phosphate layer is uniformly and continuously coated on the surface of each of the electrode active material particles.

The method for producing an electrode composite material according to the present invention includes a first step of providing an aluminum nitrate solution, a plurality of electrode active material particles added to the aluminum nitrate solution to form a mixture, and the electrode active material particles include: A second step of Li _x Ni _1-y L _y O ₂ (where x and y satisfy 0.1 ≦ x ≦ 1.1, 0 ≦ y <1) particles, and a phosphate solution. A third step of joining the mixture and reacting the phosphate solution with the aluminum nitrate of the mixture to form an aluminum phosphate layer on the surface of the electrode active material particles; and the aluminum phosphate layer was coated And a fourth step of heat-treating the electrode active material particles.

 Compared with the prior art, the composite material for electrodes of the present invention is such that each electrode active material particle is uniformly coated with an aluminum phosphate layer as a modified layer, so that the solid and the solid are mixed. Can prevent non-uniform adsorption to each other. Therefore, the manufacturing method of the composite material for electrodes of the present invention can be applied to large-scale industrial production. In addition, since the surface of each electrode active material particle is uniformly and continuously coated with an aluminum phosphate layer, the lithium ion battery using the electrode composite material has excellent stability even at high temperatures. In addition, the cycle characteristics are sufficient.

It is a figure which shows the structure of the positive electrode active material composite particle which concerns on this invention. It is a SEM photograph of the lithium cobaltate particle | grains coat | covered with the aluminum phosphate which concerns on Example 1 of this invention. It is a TEM photograph in case the micron marker of the lithium cobaltate particle | grains coat | covered with the aluminum phosphate which concerns on Example 1 of this invention is 20 nm. It is a SEM photograph in case the micron marker of the lithium cobalt oxide particle coat | covered with the aluminum phosphate which concerns on the comparative example 1 is 5 micrometers. It is a SEM photograph in case the micron marker of the lithium cobaltate particle | grains coat | covered with the aluminum phosphate which concerns on the comparative example 1 is 1 micrometer. It is a curve diagram which shows the charging / discharging cycle performance of the lithium ion battery which employ | adopted the lithium cobaltate particle | grains coat | covered with the aluminum phosphate which concerns on Examples 1-4 of this invention. Was adopted _LiNi 0.5 _Mn 1.5 _{O 4} that are not covered electrochemical experiments 6 _LiNi 0.5 _Mn 1.5 _{O 4} coated with aluminum phosphate and Comparative Examples electrochemical experiment 4 of the present invention It is a comparative comparison figure of the curve which shows the charging / discharging characteristic of a lithium ion battery. Showing charge-discharge characteristics of the _LiNi 1/3 _Co 1/3 lithium ion battery employing the _Mn 1/3 _{O 2} particles coated with aluminum phosphate of Example 9 was measured at the charging voltage of 4.2V of the present invention FIG. Showing charge-discharge characteristics of the _LiNi 1/3 _Co 1/3 lithium ion battery employing the _Mn 1/3 _{O 2} particles coated with aluminum phosphate of Example 9 was measured at the charging voltage of 4.3V of the present invention FIG. Showing charge-discharge characteristics of the _LiNi 1/3 _Co 1/3 lithium ion battery employing the _Mn 1/3 _{O 2} particles coated with aluminum phosphate of Example 9 was measured at the charging voltage of 4.4V of the present invention FIG. Showing charge-discharge characteristics of the _LiNi 1/3 _Co 1/3 lithium ion battery employing the _Mn 1/3 _{O 2} particles coated with aluminum phosphate of Example 9 was measured at the charging voltage of 4.5V of the present invention FIG. Showing charge-discharge characteristics of the _LiNi 1/3 _Co 1/3 lithium ion battery employing the _Mn 1/3 _{O 2} particles coated with aluminum phosphate of Example 9 was measured at the charging voltage of 4.6V of the present invention FIG. Showing charge-discharge characteristics of the _LiNi 1/3 _Co 1/3 lithium ion battery employing the _Mn 1/3 _{O 2} particles coated with aluminum phosphate of Example 9 was measured at the charging voltage of 4.7V of the present invention FIG. It is a curve diagram showing the charge and discharge characteristics of half-cells utilizing positive electrode active material comprising a positive active material composite and LiCoO ₂ which are not covered in the Comparative Example 1. The uncoated _LiNi 1/3 _Co 1/3 _Mn 1/3 _{O 2} lithium ion batteries particles employing a is a curve diagram showing charge-discharge characteristics measured at the charging voltage of 4.2 V. The uncoated _LiNi 1/3 _Co 1/3 _Mn 1/3 _{O 2} lithium ion batteries particles employing a is a curve diagram showing charge-discharge characteristics measured at the charging voltage of 4.3 V. The uncoated _LiNi 1/3 _Co 1/3 _Mn 1/3 _{O 2} lithium ion batteries particles employing a is a curve diagram showing charge-discharge characteristics measured at the charging voltage of 4.4 V. The uncoated _LiNi 1/3 _Co 1/3 _Mn 1/3 _{O 2} lithium ion batteries particles employing a is a curve diagram showing charge-discharge characteristics measured at the charging voltage of 4.5V. The uncoated _LiNi 1/3 _Co 1/3 _Mn 1/3 _{O 2} lithium ion batteries particles employing a is a curve diagram showing charge-discharge characteristics measured at the charging voltage of 4.6 V. The uncoated _LiNi 1/3 _Co 1/3 _Mn 1/3 _{O 2} lithium ion batteries particles employing a is a curve diagram showing charge-discharge characteristics measured at the charging voltage of 4.7V. It is a figure which shows the structure of the conventional positive electrode active material composite particle.

  Hereinafter, embodiments of the present invention will be described. The composite material for electrodes and the manufacturing method thereof will be described.

(1) Lithium-ion battery electrode composite material The electrode composite material of the present embodiment is composed of a plurality of electrode composite particles. Referring to FIG. 1, the electrode composite particle 10 includes a lithium ion battery electrode active material particle 12 and an aluminum phosphate layer 14. The aluminum phosphate layer 14 is coated on the surfaces of the lithium ion battery electrode active material particles 12. In the composite particle 10 for an electrode, the mass percentage of the aluminum phosphate layer 14 is 0.1% to 3%. The aluminum phosphate layer 14 has a thickness of 5 nm to 20 nm. The aluminum phosphate layer 14 is formed on the surface of the lithium ion battery electrode active material particles 12 by an in situ method. The aluminum phosphate layer 14 is a continuous thin film layer having a uniform thickness. The surfaces of all the lithium ion battery electrode active material particles 12 are uniformly and continuously covered with the aluminum phosphate layer 14. Interfacial diffusion may occur at the place where the lithium ion battery electrode active material particles 12 and the aluminum phosphate layer 14 are in contact with each other. In this case, the transition metal atoms of the lithium ion battery electrode active material particles 12 diffuse into the aluminum phosphate layer 14.

 Examples of the composite material for electrodes include the following (1) to (2).

(1) Positive electrode active material composite material As one example, the electrode composite material is a positive electrode active material composite material. In this case, the positive electrode active material composite particles 10 include positive electrode active material particles 12 and an aluminum phosphate layer 14.

 The positive electrode active material particles 12 may include a spinel type lithium manganese oxide, an olivine type lithium iron phosphate, and a bernetite type lithium manganese oxide (layered type lithium manganese oxide). Layered type lithium nickel oxide, layered type lithium cobalt oxide, layered type lithium nickel oxide type of layered lithium metal oxide (layered type lithium nickel oxide type) Consisting of one or several Kell manganese lithium cobalt oxide (layered type lithium nickel cobalt manganese oxide). The lithium transition metal oxide can be doped.

Formula of the spinel-type lithium manganese oxide _{is Li x Mn 2-k L k} O 4. Formula of the olivine-type lithium iron phosphate _is a _{Li x Fe 1-y L y} PO 4. Formula of the birnessite type lithium manganese oxide _{is Li x Mn 2-y L y} O 2. The general formula of the lithium nickel layered oxide is Li _x Ni _1-y L _y O ₂ . The general formula of the layered lithium cobaltate is Li _x Co _1-y L _y O ₂ . Formula of spinel-type lithium-nickel-manganese oxide _{is Li x Ni 0.5 + z-a} Mn 1.5-z-b L a R b O 4. The general formula of the layered lithium nickel manganese cobaltate is Li _x Ni _c Co _d Mn _e L _f O ₂ . The x, y, z, a, b, c, d, e, f, and k satisfy the following formulas 1 to 11, respectively.

 0.1 ≦ x ≦ 1.1 (Formula 1)

 0 ≦ y <1 (Formula 2)

 0 ≦ z <1.5 (Formula 3)

 0 ≦ az <0.5 (Formula 4)

 0 ≦ b + z <1.5 (Formula 5)

 0 <c <1 (Formula 6)

 0 <d <1 (Formula 7)

 0 <e <1 (Formula 8)

 0 ≦ f ≦ 0.2 (Formula 9)

 c + d + e + f = 1 (Formula 10)

 0 ≦ k <2 (Formula 11)

 The L and R are composed of one or several kinds of alkali metal elements, alkaline earth metal elements, group 13 elements, group 14 elements, transition metal elements, and rare earth elements. L and R are nickel (Ni), chromium (Cr), cobalt (Co), vanadium (V), titanium (Ti), aluminum (Al), iron (Fe), gallium (Ga), neodymium (Nd). And one or several of magnesium (Mg) are preferable. In this case, z preferably satisfies the following formula 12.

 0 ≦ z <0.1 (Formula 12)

(2) Negative electrode active material composite material As another example, the composite material for an electrode is a negative electrode active material composite material. In this case, one negative electrode active material composite particle 10 includes negative electrode active material particles 12 and an aluminum phosphate layer 14.

The anode active material particles 12 may be made of one or several kinds of lithium titanate, graphite, acetylene black, organic pyrolytic carbon, and mesocarbon microbeads (MCMB). The lithium titanate is preferably spinel type lithium titanate doped or undoped. The general formula of undoped spinel type lithium titanate is Li ₄ Ti ₅ O ₁₂ . The general formula of the doped spinel type lithium titanate is Li _{(4-g) Ag} Ti ₅ O ₁₂ or Li ₄ A _h Ti _(5-h) O ₁₂ . Said g and h satisfy | fill the following formula | equation 13 and Formula 14, respectively.

 0 <g ≦ 0.33 (Formula 13)

 0 <h ≦ 0.5 (Formula 14)

 Said A consists of one or several kinds of alkali metal elements, alkaline earth metal elements, group 13 elements, group 14 elements, transition metal elements, and rare earth elements. The A is preferably composed of one or several kinds of Mn, Ni, Cr, Co, V, Ti, Al, Fe, Ga, Nd, and Mg.

In the present embodiment, the electrode active material particles 12 are made of layered lithium cobalt oxide (Li _x CoO ₂ ), birnessite-type lithium manganese oxide (Li _x MnO ₂ ), or olivine-type lithium iron phosphate (Li _x FePO ₄ ). Preferably the general formula is from LiNi _0.5 Mn _1.5 O ₄ , LiNi _0.8 Co _0.15 Al _0.05 O ₂ or LiNi _1/3 Co _1/3 Mn _1/3 O ₂ It is also preferable that The electrode active material particles 12 have a diameter of 100 nm to 100 μm, preferably 1 μm to 20 μm.

(2) Method for Producing Lithium Ion Battery Electrode Composite Material A method for producing an electrode composite material comprising the electrode composite particles 10 comprises providing an aluminum nitrate (Al (NO ₃ ) ₃ ) solution (S11), A step of forming a mixture by adding a plurality of electrode active material particles 12 to the aluminum nitrate solution (S12), and adding a phosphate solution to the mixture to react with Al (NO ₃ ) ₃ of the mixture. Forming an aluminum phosphate layer 14 on the surface of the electrode active material particles 12 (S13), heating the electrode active material particles 12 coated with the aluminum phosphate layer 14 (S14), including.

The aluminum nitrate solution includes a solvent and Al (NO ₃ ) ₃ dissolved in the solvent. The liquid phase solvent is preferably a solvent capable of decomposing Al (NO ₃ ) ₃ . Thus, in the solvent, decomposing the Al _{(NO 3)} 3 to ^{Al 3+} and ^{NO 3-.} The solvent is not limited to water, and may be a volatile organic solvent such as ethanol, acetone, chloroform, diethyl ether, dichloromethane and ethylidene chloride. However, when water is used as the solvent, there is a problem that the electrode active material particles 12 react with water and the performance of the electrode active material particles 12 deteriorates. Therefore, it is preferable to use an organic solvent such as ethanol as the solvent.

In step S12, since the electrode active material particles 12 are not dissolved in the aluminum nitrate solution, they are formed into a solid-liquid mixture. In the mixture, Al ³⁺ is adsorbed on the surface of the electrode active material particles 12 to form an atomic grade coating layer. The dose of the electrode active material particles 12 is controlled to such an extent that Al ³⁺ ions can sufficiently cover all the surfaces of the electrode active material particles 12. In this case, the mixture becomes a slurry. Therefore, the dose of the electrode active material particles 12 can be controlled by the form of the mixture. The volume ratio between the aluminum nitrate solution and the electrode active material particles 12 is preferably 1:10 to 1:40. Here, the diameter of the electrode active material particles 12 is preferably 20 μm. The dose of the aluminum nitrate solution is determined by the dose of the electrode active material particles 12 to be coated with the aluminum phosphate layer 14. In this embodiment, the mass percentage of the aluminum phosphate layer 14 in the composite particle for electrode 10 is 0.1% to 3%.

In the step S13, the phosphate solution includes a liquid phase solvent such as water, and a phosphate dissolved in the liquid phase solvent. The phosphate includes monoammonium phosphate (NH ₄ H ₂ PO ₄ ), diammonium phosphate ((NH ₄ ) ₂ HPO ₄ ), ammonium phosphate ((NH ₄ ) ₃ PO ₄ ) and phosphoric acid (H ₃ PO ₄ ) or the like. The phosphate solution may be one or several kinds of phosphate ions (PO ₄ ³⁻ ), dihydrogen phosphate ions (H ₂ PO ₄ ⁻ ), and hydrogen phosphate ions (HPO ₄ ²⁻ ). Phosphate ions can be included. That is, the phosphate ion is obtained by decomposing from a phosphate. When the phosphate solution is added to a slurry mixture composed of the electrode active material particles 12 and the aluminum nitrate solution, the phosphate ions and Al ³⁺ ions adsorbed on the surfaces of the electrode active material particles 12 are used. Reacts on the surface of the electrode active material particles 12 to form a uniform aluminum phosphate layer on the surface of the electrode active material particles 12. In this embodiment, the phosphate solution is added drop by drop to the slurry mixture and the mixture is stirred at the same time. As a result, the phosphate ions and Al ³⁺ ions react uniformly with the surface of the electrode active material particles 12. The dose of the phosphate solution can be controlled by the amount of the electrode active material particles 12 to be coated with the aluminum phosphate layer 14.

In step S14, in order to adhere the aluminum phosphate layer 14 to the surface of the electrode active material particles 12, the electrode composite particles 10 in step S13 can be further heat-treated. Thereby, the reaction product such as the remaining solvent and ammonium nitrate (NH ₄ NO ₃ ) can be removed, and the lithium ion battery electrode active material particles 12 and the aluminum phosphate layer 14 are in contact with each other. Interfacial diffusion can occur. As a result, the transition metal atoms of the lithium ion battery electrode active material particles 12 diffuse into the aluminum phosphate layer 14. In step S14, the heat treatment temperature is 400 ° C. to 800 ° C., and the heat treatment time is 0.5 hour to 2 hours.

(3) Lithium ion battery The lithium ion battery of this embodiment contains a positive electrode, a negative electrode, and the nonaqueous electrolyte solution arrange | positioned between the said positive electrode and the said negative electrode. The negative electrode includes a negative electrode current collector and a negative electrode material layer disposed on the surface of the negative electrode current collector. The positive electrode includes a positive electrode current collector and a positive electrode material layer disposed on the surface of the positive electrode current collector.

The positive electrode material layer includes a positive electrode active material, a conductive agent, and an adhesive that are uniformly mixed. The positive electrode active material in the positive electrode material layer includes at least one of the positive electrode active material composite materials listed in (1) above. The negative electrode material layer includes a uniformly mixed negative electrode active material, a conductive agent, and an adhesive. The negative electrode active material in the negative electrode material layer contains at least one of the negative electrode active material composite materials listed in (2) above. The conductive agent is made of at least one of acetylene black, carbon fiber, carbon nanotube, and graphite. The adhesive is made of at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and styrene-butadiene rubber (SBR). The non-aqueous electrolyte is a solution formed by dissolving a solid film or a lithium salt in an organic solvent. The lithium _{salt, LiPF 6, LiBOB, LiBF 4} , LiSbF 6, LiAsF 6, LiClO 4, LiCF 3 SO 3, Li (CF 3 SO 2) 2 N, LiC 4 F 9 SO 3, LiSbF 6, LiAlO 4, It is at least one of LiAlCl ₄ , LiCl and LiI. The organic solvent is at least one of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and dimethyl carbonate (DMC). Furthermore, the lithium ion battery may include a porous film. The porous film is disposed between the positive electrode and the negative electrode in order to separate the positive electrode and the negative electrode. The porous film is made of polypropylene (PP) or polyethylene (PE). Further, the lithium ion battery may include an external sealing structure. Furthermore, the lithium ion battery may include a connection element. The connection element is installed to connect the current collector of the lithium ion battery to an external power supply device.

Example 1
Example 1 provides a positive electrode active material composite material. The positive electrode active material composite material is a composite material of lithium cobaltate and aluminum phosphate. The positive electrode active material composite material includes a plurality of lithium cobalt oxide (LiCoO ₂ ) particles and an aluminum phosphate layer coated on the surface of each lithium cobalt oxide particle. In the positive electrode active material composite material, the mass percentage of aluminum phosphate is 1%.

The manufacturing method of the positive electrode active material composite material of lithium cobaltate and aluminum phosphate includes providing an aluminum nitrate (Al (NO ₃ ) ₃ ) solution (S111), and adding lithium cobaltate particles to the aluminum nitrate solution. Forming a mixture (S121), adding a phosphate solution to the mixture and reacting with Al (NO ₃ ) ₃ of the mixture to form an aluminum phosphate layer on the surface of the lithium cobalt oxide particles. Forming (S131), and heating (S141) the electrode active material particles 12 coated with the aluminum phosphate layer.

In the step (S111), the aluminum nitrate solution is a solution formed by dissolving aluminum nitrate (Al (NO ₃ ) ₃ ) in ethanol. In the step (S121), 100 grams of lithium cobalt oxide particles are added to 30 ml of an aluminum nitrate solution having a concentration of 0.16 mol / L and stirred to form a slurry mixture. In step (S131), the phosphate solution is a _(NH4) 2 HPO ₄ solution. The (NH ₄ ) ₂ HPO ₄ solution is added dropwise to the slurry mixture. Thereafter, the mixture is stirred uniformly to cover all surfaces of the lithium cobalt oxide particles with the aluminum phosphate layer. In the step (S141), the heat treatment temperature is 400 ° C.

 2 and 3 are an SEM photograph and a TEM photograph of a positive electrode active material composite material of lithium cobaltate and aluminum phosphate obtained by the above production method. Referring to FIG. 2, the aluminum phosphate layer is uniformly coated on the surface of the lithium cobalt oxide particles. Referring to FIG. 3, the aluminum phosphate layer coated on the surface of the lithium cobalt oxide particles has a uniform thickness.

(Example 2)
This example provides a positive electrode active material composite material. The positive electrode active material composite material is a composite material of lithium cobaltate and aluminum phosphate. Compared with the positive electrode active material composite material according to Example 1, the positive electrode active material composite material according to this example has the following differences. In this example, in the step (S141), the lithium cobalt oxide and the aluminum phosphate are heat-treated at a temperature of 500 ° C. to form the positive electrode active material composite material.

(Example 3)
This example provides a positive electrode active material composite material. The positive electrode active material composite material is a composite material of lithium cobaltate and aluminum phosphate. Compared with the positive electrode active material composite material according to Example 1, the positive electrode active material composite material according to this example has the following differences. In this example, in the step (S141), the lithium cobalt oxide and the aluminum phosphate are heat-treated at a temperature of 600 ° C., thereby forming the positive electrode active material composite material.

(Example 4)
This example provides a positive electrode active material composite material. The positive electrode active material composite material is a composite material of lithium cobaltate and aluminum phosphate. Compared with the positive electrode active material composite material according to Example 1, the positive electrode active material composite material according to this example has the following differences. In the positive electrode active material composite material, the mass percentage of aluminum phosphate is 1.5%. In this example, in the step (S141), the lithium cobalt oxide and the aluminum phosphate are heat-treated at a temperature of 600 ° C., thereby forming the positive electrode active material composite material.

(Example 5)
In this example, a positive electrode active material composite material is provided. The positive electrode active material composite material is a composite material of lithium manganate and aluminum phosphate (AlPO ₄ -LiMn ₂ O ₄ ). The positive electrode active material composite material includes a plurality of lithium manganate (LiMn ₂ O ₄ ) particles and an aluminum phosphate layer coated on the surface of each lithium manganate particle. Compared with the positive electrode active material composite material according to Example 3, the positive electrode active material composite material according to this example replaced the lithium cobalt oxide particles in the positive electrode active material composite material of Example 3 with lithium manganate particles. Is used. The method for producing the AlPO ₄ —LiMn ₂ O ₄ composite material is the same as the method for producing the AlPO ₄ —LiCoO ₂ composite material of Example 3.

(Example 6)
This example provides a positive electrode active material composite material. The positive electrode active material composite material is a composite material of spinel-type lithium nickel manganese oxide and aluminum phosphate (AlPO ₄ —LiNi _0.5 Mn _1.5 O ₄ ). The positive electrode active material composite material includes a plurality of spinel-type lithium nickel manganese oxide (LiNi _0.5 Mn _1.5 O ₄ ) particles and phosphoric acid coated on the surface of each spinel-type lithium nickel manganese oxide particle An aluminum layer. The manufacturing method of the AlPO ₄ —LiNi _0.5 Mn _1.5 O ₄ composite material is the same as the manufacturing method of the AlPO ₄ —LiCoO ₂ composite material. Compared with the positive electrode active material composite material according to Example 3, the positive electrode active material composite material according to this example replaces the lithium cobalt oxide particles in the positive electrode active material composite material of Example 3, and spinel lithium nickel. Manganese oxide particles are used. In the composite material of the spinel type lithium nickel manganese oxide and aluminum phosphate, the mass percentage of aluminum phosphate is 0.5%.

(Example 7)
This example provides a positive electrode active material composite material. The positive electrode active material composite material is a composite material of lithium nickel oxide and aluminum phosphate (AlPO ₄ -LiNiO ₂ ). The positive electrode active material composite material includes a plurality of lithium nickel oxide (LiNiO ₂ ) particles and an aluminum phosphate layer coated on the surface of each lithium nickel oxide particle. Manufacturing method of the AlPO ₄ -LiNiO ₂ composite material is the same as the manufacturing method of the AlPO ₄ -LiCoO ₂ composite material of Example 4. Compared with the positive electrode active material composite material according to Example 4, the positive electrode active material composite material according to this example replaces the lithium cobalt oxide particles in the positive electrode active material composite material of Example 4 with lithium nickel oxide. Use particles.

(Example 8)
This example provides a positive electrode active material composite material. The positive electrode active material composite material is a composite material of lithium nickel oxide doped with Al and Co and aluminum phosphate (AlPO ₄ -LiNi _0.8 Co _0.15 Al _0.05 O ₂ ). The positive electrode active material composite material includes a plurality of lithium nickel oxide (LiNi _0.8 Co _0.15 Al _0.05 O ₂ ) particles doped with Al and Co, and each LiNi _0.8 Co _0.15. An aluminum phosphate layer coated on the surface of Al _0.05 O ₂ particles. The manufacturing method of the AlPO ₄ —LiNi _0.8 Co _0.15 Al _0.05 O ₂ composite material is the same as the manufacturing method of the AlPO ₄ —LiCoO ₂ composite material of Example 4. Compared with the positive electrode active material composite material according to Example 4, the positive electrode active material composite material according to this example is replaced with LiCo _{0.8 in} the positive electrode active material composite material of Example 4 above. Co _0.15 Al _0.05 O ₂ particles are used.

Example 9
This example provides a positive electrode active material composite material. The positive electrode active material composite material is a composite material of lithium nickel cobalt manganese oxide and aluminum phosphate (AlPO ₄ -LiNi _1/3 Co _1/3 Mn _1/3 O ₂ ). The positive electrode active material composite material includes a plurality of lithium nickel cobalt manganese oxide (LiNi _1/3 Co _1/3 Mn _1/3 O ₂ ) particles and respective LiNi _1/3 Co _1/3 Mn _1/3 O. _An aluminum phosphate layer coated on the surface of the _two particles. The method for producing the AlPO ₄ —LiNi _1/3 Co _1/3 Mn _1/3 O ₂ composite material is the same as the method for producing the AlPO ₄ —LiCoO ₂ composite material of Example 3. Compared with the positive electrode active material composite material according to Example 3, the positive electrode active material composite material according to this example is replaced by LiNi _1/3 instead of the lithium cobalt oxide particles in the positive electrode active material composite material of Example 3. Co _1/3 Mn _1/3 O ₂ particles are used.

(Example 10)
This example provides a negative electrode active material composite material. The negative electrode active material composite material is a composite material of spinel type lithium titanate and aluminum phosphate (AlPO ₄ -Li ₄ Ti ₅ O ₁₂ ). The negative electrode active material composite material includes a plurality of spinel type lithium titanate (Li ₄ Ti ₅ O ₁₂ ) particles and an aluminum phosphate layer coated on the surface of each Li ₄ Ti ₅ O ₁₂ particle. Manufacturing method of the AlPO ₄ -Li ₄ Ti ₅ O ₁₂ composite material is the same as the manufacturing method of the AlPO ₄ -LiCoO ₂ composite material of Example 4. Compared with the positive electrode active material composite material according to Example 4, the negative electrode active material composite material according to this example replaced Li ₄ Ti _{5 in place of the} lithium cobalt oxide particles in the positive electrode active material composite material of Example 4. Utilize O ₁₂ particles. There is a possibility that the composite material of this example is in charge of the positive electrode active material composite material.

(Comparative Example 1)
Comparative Example 1 provides a positive electrode active material composite material formed by a conventional manufacturing method. In the conventional method for producing a positive electrode active material composite material, a plurality of aluminum phosphate particles are dispersed in water by mixing and stirring an aqueous solution of (NH ₄ ) ₂ HPO _{4 and} an aqueous solution of Al (NO ₃ ) _3. Forming a mixture (H11), adding LiCoO ₂ particles to the mixture, adhering the aluminum phosphate particles to the surface of the LiCoO ₂ particles (H12), and the LiCoO ₂ particles And filtering the mixed solution containing the composite particles having the aluminum phosphate particles attached to the surface and heat-treating the composite particles at 600 ° C. to form the positive electrode active material composite material of Comparative Example 1 (H13). 4 and 5, in the positive electrode active material composite material formed by the conventional manufacturing method, aluminum phosphate is aggregated on the surface of LiCoO ₂ particles in the form of particles.

(Comparative Example 2)
Comparative Example 2 provides a positive electrode active material composite material formed by a conventional manufacturing method. Compared with the positive electrode active material composite material according to Comparative Example 1, the positive electrode active material composite material according to this comparative example replaces the LiCoO ₂ particles in the positive electrode active material composite material of Comparative Example 1 with LiMn ₂ O ₄ particles. Use.

(Comparative Examples 3 and 4)
Comparative Examples 3 and 4 each provide a positive electrode active material composite material formed by a conventional manufacturing method. Positive active material composite according to Comparative Examples 3 and 4 is different from the positive electrode active material composite according to Comparative Example 1, as a substitute to the LiCoO ₂ particles in the positive electrode active material the composite material of Comparative Example 1, respectively LiNiO ₂ particles And LiNi _0.8 Co _0.15 Al _0.05 particles.

(Comparative Example 5)
Comparative Example 5 provides a negative electrode active material composite material formed by a conventional manufacturing method. Compared with the positive electrode active material composite material according to Comparative Example 1, the negative electrode active material composite material according to this Comparative Example is replaced with LiCoO ₂ particles in the positive electrode active material composite material of Comparative Example 1, and Li ₄ Ti ₅ O _12. Use particles.

(Electrochemical experiment 1)
The positive electrode active material composite material formed in Example 1 was mixed with acetylene black as a conductive agent and polyvinylidene fluoride as an adhesive at a mass ratio of 90: 5: 5, and then N-methyl-2- A suspension is formed in pyrrolidone (N-methylpyrrolidone, NMP). After apply | coating the said suspension liquid on the surface of aluminum foil, it dries at the temperature of 100 degreeC, A positive electrode is formed by removing NMP. The counter electrode is made of a lithium metal piece. Here, a half cell is assembled by using 1 mol / L LiPF ₆ / EC + DEC (1: 1) as an electrolyte and using a porous polypropylene film as a separator. The assembled half-cell is measured for charge / discharge characteristics at room temperature with a current of 0.5 C (C rate) and a voltage of 2.7 V to 4.5 V.

(Electrochemical experiments 2-4)
The conditions for measuring the charge / discharge characteristics of the electrochemical experiments 2 to 4 are the same as the conditions for measuring the charge / discharge characteristics of the electrochemical experiment 1. The half cells used in the electrochemical experiments 2 to 4 have the following differences from the half cells assembled in the electrochemical experiment 1. As the positive electrode active material composite material, the positive electrode active material composite materials of Examples 2 to 4 are used.

Referring to FIG. 6, the half cell using the positive electrode active material layer composed of composite particles in which the surface of the LiCoO ₂ particles of Examples 1 to 4 is uniformly coated with the aluminum phosphate layer is charged even at a high voltage. , Have high capacity and capacity retention (capacity maintenance ratio). Even when the half-cell has completed 50 charge / discharge cycles, its capacity retention rate is higher than 90%, and its specific capacity is 160 mAh / g to 175 mAh / g. In the method for producing a positive electrode active material composite material of Examples 1 to 4, the capacity of the half cell is improved as the temperature at which the composite particles are heated is increased. However, in the positive electrode active material composite material, even if the mass percentage of aluminum phosphate is changed to 1% to 1.5%, the influence on the capacity of the half-cell is small. The AlPO ₄ layer uniformly coated on all surfaces of the LiCoO ₂ particles improves the surface structure of the positive electrode active material particles, provides a reversible insertion / desorption platform for lithium ions, and These chemical reactions can be suppressed as a barrier layer between Co ⁴⁺ and the electrolytic solution. Thus, the AlPO ₄ layer improves the stability of LiCoO ₂ and enhances the cycle performance of the lithium ion battery.

(Electrochemical experiment 5)
The conditions for measuring the charge / discharge characteristics of the electrochemical experiment 5 are the same as the conditions for measuring the charge / discharge characteristics of the electrochemical experiment 1. The half-cell used in the electrochemical experiment 5 has the following differences from the half-cell assembled in the electrochemical experiment 1. The positive electrode active material composite material of Example 5 is used as the positive electrode active material composite material. The half-cell has a high capacity and capacity retention even at room temperature, for example, in a large temperature range of 15 ° C to 60 ° C. Even when the half-cell has finished 50 charge / discharge cycles at 55 ° C. with a current of 0.2 C (C rate) and a voltage of 3 V to 4.2 V, the capacity retention rate is higher than 90%. The specific capacity is 125 mAh / g.

(Electrochemical experiment 6)
The conditions for measuring the charge / discharge characteristics of the electrochemical experiment 6 are the same as the conditions for measuring the charge / discharge characteristics of the electrochemical experiment 1. The half-cell used in the electrochemical experiment 6 has the following differences from the half-cell assembled in the electrochemical experiment 1. The positive electrode active material composite material of Example 6 is used as the positive electrode active material composite material. Even when the half-cell has completed 50 charge / discharge cycles at room temperature with a current of 0.2 C and a voltage of 3 V to 5 V, this capacity retention is higher than 95%, and this specific capacity is 138 mAh / g. It is. Even if the half-cell has completed 50 charge / discharge cycles at room temperature with a current of 1 C and a voltage of 3 V to 5 V, this capacity retention is higher than 95%, and this specific capacity is 132 mAh / g. .

(Electrochemical experiment 7)
The conditions for measuring the charge / discharge characteristics of the electrochemical experiment 7 are the same as the conditions for measuring the charge / discharge characteristics of the electrochemical experiment 1. The half-cell used in the electrochemical experiment 7 has the following differences from the half-cell assembled in the electrochemical experiment 1. The positive electrode active material composite material of Example 7 is used as the positive electrode active material composite material. Even when the half-cell has completed 50 charge / discharge cycles at room temperature with a current of 0.5 C and a voltage of 2.5 V to 4.5 V, this capacity retention is higher than 85%, and this specific capacity Is 150 mAh / g.

(Electrochemical experiment 8)
The conditions for measuring the charge / discharge characteristics of the electrochemical experiment 8 are the same as the conditions for measuring the charge / discharge characteristics of the electrochemical experiment 1. The half-cell used in the electrochemical experiment 8 has the following differences from the half-cell assembled in the electrochemical experiment 1. The positive electrode active material composite material of Example 8 is used as the positive electrode active material composite material. Even if the half-cell has completed 50 charge / discharge cycles at room temperature with a current of 0.5 C and a voltage of 3.75 V to 4.5 V, this capacity retention is higher than 91%, and this specific capacity Is 140 mAh / g.

(Electrochemical experiments 9-14)
The conditions for measuring the charge / discharge characteristics of the electrochemical experiments 9 to 14 are the same as the conditions for measuring the charge / discharge characteristics of the electrochemical experiment 1. The half-cell used in the electrochemical experiment 9 has the following differences from the half-cell assembled in the electrochemical experiment 1. The positive electrode active material composite material of Example 9 is used as the positive electrode active material composite material. The half-cell performs 100 charge / discharge cycles with a current of 1 C at room temperature. For charge / discharge voltage conditions and measurement results, refer to Table 1 and FIGS.

 Table 1 shows the results of measuring the charge / discharge characteristics of the half-cell at room temperature, 1 C current, and different charging voltages. In this case, the charge / discharge characteristics of the half-cell are good and its capacity retention is high. Furthermore, when the charging voltage is 4.6 V at a current of 1 C at room temperature, the capacity retention rate of the half-cell is 90.6%.

(Electrochemical experiment 15)
The conditions for measuring the charge / discharge characteristics of the electrochemical experiment 15 are the same as the conditions for measuring the charge / discharge characteristics of the electrochemical experiment 1. The half-cell used in the electrochemical experiment 15 has the following differences from the half-cell assembled in the electrochemical experiment 1. As the negative electrode active material composite material of the electrochemical experiment 1, the negative electrode active material composite material of Example 10 is used. The half-cell has a high capacity and capacity retention even at room temperature, for example in a large temperature range of 15 ° C. to 60 ° C. Even when the half-cell has finished 50 charge / discharge cycles at 55 ° C. with a current of 0.1 C and a voltage of 0.8 V to 3 V, this capacity retention is higher than 85%, and this specific capacity is 160 mAh / g.

(Comparative Example Electrochemical Experiment 1)
The half-cell used in the comparative example electrochemical experiment 1 is assembled under the same conditions as the half-cell used in the electrochemical experiment 1, and the charge / discharge characteristics are measured. The half-cell used in the comparative example electrochemical experiment 1 Compared to the half-cell assembled in electrochemical experiment 1, there are the following differences. The positive electrode active material is made of uncoated LiCoO ₂ .

(Comparative Example Electrochemical Experiment 2)
The half-cell used in Comparative Example Electrochemical Experiment 2 is assembled under the same conditions as the half-cell used in Electrochemical Experiment 1, and the charge / discharge characteristics are measured. The half-cell used in Comparative Example Electrochemical Experiment 2 is Compared to the half-cell assembled in electrochemical experiment 1, there are the following differences. The positive electrode active material is made of the positive electrode active material composite material of Comparative Example 1.

Referring to FIG. 14, the charge / discharge cycle characteristics of the half cell using the positive electrode active material composite material of Comparative Example 1 and the uncoated LiCoO ₂ positive electrode active material rapidly decrease. When the half-cell completes 50 charge / discharge cycles at room temperature with a current of 0.5 C and a voltage of 2.7 V to 4.5 V, these capacity retention rates are all lower than 85%. This, LiCoO ₂ that LiCoO ₂ or the covering layer that is not covered is not uniformly coated, for example with a high voltage, such as 4.5V, is caused by stability is poor. When charging the half-cell at a high charge voltage, LiCoO ₂ undergoes side reactions with the electrolyte solution, thus reducing the capacity of the half-cell.

(Comparative Example Electrochemical Experiment 3)
The half-cell used in Comparative Example Electrochemical Experiment 3 is assembled under the same conditions as the half-cell used in Electrochemical Experiment 5, and the charge / discharge characteristics are measured. The half-cell used in Comparative Example Electrochemical Experiment 3 is Compared to the half-cell assembled in electrochemical experiment 5, there are the following differences. The positive electrode active material is made of the positive electrode active material composite material of Comparative Example 2. The half-cell has a capacity retention of less than 85% after 50 charge / discharge cycles at 55 ° C. with a current of 0.2 C and a voltage of 3 V to 4.2 V.

(Comparative Electrochemical Experiment 4)
The half-cell used in Comparative Example Electrochemical Experiment 4 is assembled under the same conditions as the half-cell used in Electrochemical Experiment 6, and the charge / discharge characteristics are measured. Compared to the half-cell assembled in electrochemical experiment 6, there are the following differences. The positive electrode active material is made of uncoated LiNi _0.5 Mn _1.5 O ₄ . Referring to FIG. 7, the half-cell has a capacity retention of less than 85% after 50 charge / discharge cycles at room temperature with a current of 1 C and a voltage of 3 V to 5 V, and the specific capacity is 118 mAh / g.

(Comparative Example Electrochemical Experiment 5)
The half-cell used in Comparative Example Electrochemical Experiment 5 is assembled under the same conditions as the half-cell used in Electrochemical Experiment 7, and the charge / discharge characteristics are measured. The half-cell used in Comparative Example Electrochemical Experiment 5 is Compared to the half-cell assembled in electrochemical experiment 7, there are the following differences. The positive electrode active material is made of the positive electrode active material composite material of Comparative Example 4. When the half-cell has completed 50 charge / discharge cycles at room temperature with a current of 0.5 C and a voltage of 2.5 V to 4.5 V, this capacity retention becomes lower than 85%.

(Comparative Example Electrochemical Experiment 6)
The half cell used for the comparative example electrochemical experiment 6 is assembled under the same conditions as the half cell used for the electrochemical experiment 8, and the charge / discharge characteristics are measured. Compared to the half-cell assembled in electrochemical experiment 8, there are the following differences. The positive electrode active material is made of the positive electrode active material composite material of Comparative Example 5. When the half-cell has completed 50 charge / discharge cycles at room temperature with a current of 0.5 C and a voltage of 3.75 V to 4.5 V, the capacity retention is lower than 85%.

(Comparative Example Electrochemical Experiments 7 to 12)
The half-cells used in comparative electrochemical experiments 7-12 are assembled under the same conditions as the half-cells used in electrochemical experiments 9-14, and the charge / discharge characteristics are measured. The half battery used has the following differences from the half batteries assembled in the electrochemical experiments 9-14. The positive electrode active material is made of uncoated LiNi _1/3 Co _1/3 Mn _1/3 O ₂ . The half-cell performs 100 charge / discharge cycles at room temperature with a current of 1C. Refer to Table 2 and FIGS. 15 to 20 for the charge / discharge voltage conditions and the measurement results.

Referring to FIGS. 15-20, the half-cells of Comparative Electrochemical Experiments 7-12 have a charge voltage of 1 C at room temperature when the charge voltage is measured at a low voltage such as 4.4 V, 4.5 V, for example. After completing 100 charge / discharge cycles with current, this capacity retention can all be kept above 78%. However, when the charging voltage of the half battery rises to 4.6V or 4.7V, the capacity of the half battery is significantly reduced. Furthermore, after completing 70 charge / discharge cycles, the capacity of the half-cell is significantly reduced. This is because uncoated LiNi _1/3 Co _1/3 Mn _1/3 O ₂ increases the resistance of the battery at a high voltage and reduces the reversible insertion / extraction of lithium ions, This is because the charge / discharge capacity of the battery is reduced.

When comparing FIGS. 15 to 20 of the measurement results of the half-cells of the comparative electrochemical experiments 7 to 12 with FIGS. 8 to 13 of the measurement results of the half-cells of the electrochemical experiments 9 to 14, the uniform AlPO was obtained under the same measurement conditions. The charge / discharge cycle curve of a half-cell using a positive electrode active material composed of LiNi _1/3 Co _1/3 Mn _1/3 O ₂ particles coated with _four layers is uncoated LiNi _1/3 Co _{1 /} It is smoother than the charge / discharge cycle curve of a half cell using a positive electrode active material made of ₃ Mn _1/3 O ₂ particles.

(Comparative Example Electrochemical Experiment 13)
The half-cell used for the comparative example electrochemical experiment 13 is assembled under the same conditions as the half-cell used for the electrochemical experiment 15, and the charge / discharge characteristics are measured. Compared to the half-cell assembled in electrochemical experiment 15, there are the following differences. The negative electrode active material is made of the composite material of Comparative Example 6. When the half-cell completes 50 charge / discharge cycles at 55 ° C. with a current of 0.1 C and a voltage of 0.8 V to 3 V, this capacity retention becomes lower than 85%.

10 Composite Particles for Electrode 12 Active Material Particles for Electrode 14 Aluminum Phosphate Layer

Claims (3)

A first step of providing an aluminum nitrate solution;
A plurality of electrode active material particles are added to the aluminum nitrate solution to form a mixture, and the electrode active material particles are Li _x Ni _1-y L _y O ₂ (wherein x and y are 0.1 ≦ 0.1). a second step which is a particle satisfying x ≦ 1.1 and 0 ≦ y <1;
When the phosphate solution to the mixture obtaining pressurized dropwise to stirring the mixture at the same time, the phosphate solution in Al ³⁺ ions adsorbed on the surface of the electrode active material particles with the phosphate ions wherein the mixture And a third step of forming an aluminum phosphate layer on the surface of the electrode active material particles,
A fourth step of heat-treating the electrode active material particles coated with the aluminum phosphate layer;
Including
Said L is nickel (Ni), chromium (Cr), cobalt (Co), vanadium (V), titanium (Ti), aluminum (Al), iron (Fe), gallium (Ga), neodymium (Nd), and The manufacturing method of the composite material for electrodes characterized by consisting of 1 type or several types of magnesium (Mg). A composite material for an electrode formed by the method for producing a composite material for an electrode according to claim 1 , comprising a plurality of active material particles for an electrode,
The electrode active material particles are Li _x Ni _1-y L _y O ₂ (wherein x and y satisfy 0.1 ≦ x ≦ 1.1 and 0 ≦ y <1),
The surface of each of the electrode active material particles is uniformly and continuously coated with an aluminum phosphate layer,
Said L is nickel (Ni), chromium (Cr), cobalt (Co), vanadium (V), titanium (Ti), aluminum (Al), iron (Fe), gallium (Ga), neodymium (Nd), and An electrode composite material comprising one or several kinds of magnesium (Mg). A lithium ion battery comprising a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, and a nonaqueous electrolyte,
The lithium ion battery, wherein the positive electrode includes the electrode composite material according to claim 2 .