JP2008071623A - Positive electrode active material for non-aqueous electrolyte secondary battery, and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a high battery capacity at high charging voltage and suppress deterioration of capacity at repeating charge and discharge by coating a desired metal oxide uniformly and firmly in performing surface reforming of a positive electrode active material for a non-aqueous electrolyte secondary battery. <P>SOLUTION: A metal hydroxide having mainly nickel (Ni) or manganese (Mn) is coated on compound oxide particles which at least contains lithium and cobalt as expressed, for example, in a chemical formula 1: Li<SB>(1+x)</SB>Co<SB>(1-y)</SB>M<SB>y</SB>O<SB>(2-z)</SB>(provided that, in the chemical formula 1, M is made of at least one kind or more of element selected from Mg, Al, B, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Mo, Sn, and W, x, y, and z is -0.01≤x≤0.10, 0≤y<0.50, -0.10≤z≤0.20) and of which the average particle size is 2.0 μm or more and 50 μm or less, and in which particles with particle size 0.5 μm or less are 0.5% or less, and is heated and dehydrated, thereby a coating layer is formed to manufacture a positive electrode active material for the non-aqueous electrolyte secondary battery. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

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

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

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

JP 62-90863 A

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

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

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

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

  However, even when the positive electrode active material improved as described above is used, when charging and discharging are repeated at a high charge voltage, capacity deterioration is caused and the battery life is shortened. In addition, when performing surface modification of a positive electrode active material mainly composed of lithium cobaltate, there is also a technical problem for uniformly and firmly depositing a desired metal oxide.

  Accordingly, an object of the present invention is to provide a positive electrode active material for a non-aqueous electrolyte secondary battery that can solve the above-described problems and can further improve chemical stability, and a method for producing the same.

  In order to solve the above-mentioned problems, a first invention of the present invention includes at least lithium (Li) and cobalt (Co), has an average particle size of 2.0 μm or more and 50 μm or less, and a particle size of 0.5 μm or less. The non-aqueous electrolyte 2 is characterized in that the composite oxide particles having a particle size of 0.5% or less are coated with a metal hydroxide mainly composed of nickel (Ni) or manganese (Mn) and dehydrated by heating. It is a manufacturing method of the positive electrode active material for secondary batteries.

In addition, it is preferable that the above-mentioned composite oxide particles have an average composition represented by Chemical Formula 1.
(Chemical formula 1)
_{Li (1 + x) Co (} 1-y) M y O (2-z)
(However, in chemical formula 1, M is magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), nickel. It consists of at least one element selected from (Ni), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), and tungsten (W), where x, y, and z are- (0.10 ≦ x ≦ 0.10, 0 ≦ y <0.50, −0.10 ≦ z ≦ 0.20)

  A second invention of the present invention includes at least lithium (Li) and cobalt (Co), having an average particle size of 2.0 μm to 50 μm and a particle size of 0.5 μm or less of 0.5% or less. It is a positive electrode active material for a non-aqueous electrolyte secondary battery, characterized in that a certain composite oxide particle is deposited with a metal hydroxide mainly composed of nickel (Ni) or manganese (Mn) and heated and dehydrated.

  In this invention, by providing a coating layer on the surface of the composite oxide particle, it is possible to suppress exposure of highly active lithium to the surface of the positive electrode active material. In addition, by reducing the content frequency of the composite oxide particles having a small particle diameter, the ratio of the coating layer that does not contribute to the battery capacity to the composite oxide particles can be reduced, and the composite oxide particles and the coating layer can be reduced. The concentration gradient due to interdiffusion of cobalt (Co) and nickel (Ni) and / or manganese (Mn), which should originally occur between the two, can be suppressed.

According to this invention, the chemical stability of the positive electrode active material for a non-aqueous electrolyte secondary battery can be further improved,
It is possible to realize a positive electrode active material for a non-aqueous electrolyte secondary battery and a method for producing the same, which can realize high charge voltage properties and high energy density properties associated therewith and have good charge / discharge cycle characteristics under high charge voltage conditions.

Embodiments of the present invention will be described below with reference to the drawings. In the nonaqueous electrolyte secondary battery of the following embodiment, the capacity ratio between the positive electrode and the negative electrode is set so that the charging potential of the positive electrode in a fully charged state becomes a high voltage of 4.35 V or more (Li / Li ⁺ ). ing.

  A non-aqueous electrolyte secondary battery according to an embodiment of the present invention (hereinafter appropriately referred to as a positive electrode active material) is a metallic water mainly composed of nickel (Ni) or manganese (Mn) in at least a part of composite oxide particles. A coating layer made of an oxide is provided by depositing with an oxide and dehydrating by heating.

First, the reason why the positive electrode active material is configured as described above will be described. A positive electrode active material mainly composed of lithium cobalt oxide (LiCoO ₂ ) has a high charge voltage property and a high energy density property associated therewith. However, when a charge / discharge cycle at a high capacity is repeated at a high charge voltage, the capacity decreases. Not a few. Since this cause is caused by the surface of the positive electrode active material particles, the necessity of surface treatment of the positive electrode active material has been pointed out.

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

As a result of intensive studies, the inventors of the present application are slightly inferior in terms of high charging voltage and high energy density, but nickel (Ni) or manganese is used as a positive electrode active material mainly composed of lithium cobaltate (LiCoO ₂ ). By applying a metal hydroxide mainly composed of (Mn) and providing a coating layer made of oxide by heat dehydration, it has high charging voltage and high energy density, and high charge. It has been found that a positive electrode active material having a high capacity and excellent charge / discharge cycle characteristics can be obtained under voltage conditions.

  As a method of providing a coating layer on the composite oxide particles, lithium (Li) compound, nickel (Ni) compound and / or manganese (Mn) compound were finely pulverized on the surface of the composite oxide particles. A composite oxide particle comprising a coating layer made of an oxide containing lithium (Li) and at least one of a coating element of nickel (Ni) and manganese (Mn) is dry-mixed, deposited and fired as particles. Method of depositing on the surface, lithium (Li) compound, nickel (Ni) compound and / or manganese (Mn) compound dissolved or mixed in a solvent, and mixed oxide particle surface in wet A coating layer made of an oxide containing lithium (Li) and at least one of the coating elements of nickel (Ni) and manganese (Mn) is subjected to composite oxidation. We propose a method of providing the surface of the particles. However, with these methods, results were obtained in which highly uniform deposition could not be achieved.

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

  Furthermore, the inventors of the present application have made extensive studies, and the uniformity of deposition on the surface of the composite oxide particles is further improved by performing the above-described deposition treatment in a solvent system mainly composed of water having a pH of 12 or more. I found out that I can do it. In this deposition treatment, composite oxide particles are dispersed in advance in a solvent system mainly composed of water having a pH of 12 or more, and a nickel (Ni) compound and / or a manganese (Mn) compound is added to the dispersion solvent. A hydroxide containing nickel (Ni) and / or manganese (Mn) is deposited on the surface of the composite oxide particles.

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

  As a result of further investigation by the inventor, the presence of small particle diameter particles having extremely low particle diameters, particularly notably 0.5 μm or less, as the composite oxide particles is the effect of the present invention. And the reduction of its presence was found to be effective in achieving the effects of the present invention. That is, when the small particle size particle is present, the deposition ratio of the particle is relatively high with respect to the particle bulk volume, and the heat treatment in the manufacturing process of the present invention causes the internal cobalt and the coating particle to be coated. Due to the interdiffusion of the deposited nickel manganese, the concentration gradient that should originally occur becomes unclear, and in some cases, particles of almost uniform composition are formed, which does not meet the object of the present invention. I understood that. In the present invention, the presence of small particle size, particularly 0.5 μm or less, is 0.5% or less, preferably 0.3% or less, more preferably 0.1% of the composite oxide particles. It is effective to achieve the effect of the present invention.

  By using the positive electrode active material thus produced, the stability at a high charging voltage is high, and accordingly, a high energy density can be improved, and a high-capacity charging / discharging cycle under a high charging voltage condition can be achieved. A positive electrode active material having good repeatability could be obtained.

  Next, the composite oxide and the coating layer constituting the positive electrode active material according to one embodiment of the present invention will be described in detail.

[Composite oxide]
The composite oxide particles have, for example, an average composition represented by Chemical Formula 1. When the composite oxide particles have the average composition represented by Chemical Formula 1, high capacity and high discharge potential can be obtained, and electrochemical stability can be improved. The average composition of the composite oxide particles can be analyzed by atomic absorption analysis.

(Chemical formula 1)
_{Li (1 + x) Co (} 1-y) M y O (2-z)
(However, in chemical formula 1, M is magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), nickel. It consists of at least one element selected from (Ni), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), and tungsten (W), where x, y, and z are- (0.10 ≦ x ≦ 0.10, 0 ≦ y <0.50, −0.10 ≦ z ≦ 0.20)

  Here, in Chemical Formula 1, the range of x is −0.10 ≦ x ≦ 0.10, more preferably −0.08 ≦ x ≦ 0.08, and still more preferably −0.06 ≦ x ≦ 0. .06. When the value decreases outside this range, the discharge capacity decreases, and when the value increases outside this range, it diffuses out of the particles, hindering control of the basicity of the next processing step, and finally Specifically, this causes a harmful effect of promoting gelation during the kneading of the positive electrode paste.

The range of y is 0 ≦ y <0.50, preferably 0 ≦ y <0.40, and more preferably 0 ≦ y <0.30. If it is larger than this range, the high charge voltage property and accompanying high energy density property of LiCoO ₂ are impaired, and the original object of the present invention cannot be achieved.

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

  As the composite oxide particles, for example, particles prepared by crushing secondary particles using a ball mill or a crusher can be used.

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

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

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

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

  Further, the amount of metal hydroxide mainly composed of nickel (Ni) or manganese (Mn) hydroxide is, for example, 0.5 wt% or more and 50 wt% or less with respect to the weight of the composite oxide particles. Preferably, it is 1.0 to 40% by weight, and more preferably 2.0 to 30% by weight. This is because if the metal oxide deposition weight increases beyond this range, the capacity of the positive electrode active material decreases. This is because if the metal oxide deposition weight decreases from this range, the stability of the positive electrode active material decreases.

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

  Next, an example of a method for producing a positive electrode active material according to an embodiment of the present invention will be described.

The composite oxide particles can be produced by various methods. For example, it is manufactured by mixing raw materials such as lithium carbonate (Li ₂ CO ₃ ) and cobalt carbonate (CoCO ₃ ) at a predetermined ratio, mixing and pulverizing with a ball mill, and firing in air or in an oxygen atmosphere. Can do. In addition to the materials described above, various carbonates, nitrates, oxalates, phosphates, oxides or hydroxides can be used as raw materials.

  The coating layer forming step includes a first step of forming a layer made of a metal hydroxide mainly composed of nickel (Ni) or manganese (Mn) on at least a part of the composite oxide particles, and a metal hydroxide An oxide containing lithium (Li) and at least one covering element of nickel (Ni) and manganese (Mn) in at least a part of the composite oxide particles by forming a layer to be heat-treated And a second step of forming a coating layer made of the same.

(First step)
In the first step, a hydroxide containing nickel (Ni) and / or manganese (Mn) is applied. In the first step, for example, first, the composite oxide particles are dispersed in a solvent system mainly composed of water in which a nickel (Ni) compound and / or a manganese (Mn) compound is dissolved. The basicity of the dispersion is increased by adding a base and the like, and a hydroxide containing nickel (Ni) and / or manganese (Mn) is precipitated on the surface of the composite oxide particles. The composite oxide particles are dispersed in a solvent mainly composed of basic water, and then a nickel (Ni) compound and / or a manganese (Mn) compound is added to the aqueous solution to obtain nickel (Ni). And / or a hydroxide containing manganese (Mn) may be deposited.

  Nickel (Ni) compound raw materials include nickel hydroxide, nickel carbonate, nickel nitrate, nickel fluoride, nickel chloride, nickel bromide, nickel iodide, nickel perchlorate, nickel bromate, nickel iodate, oxidation Inorganic compounds such as nickel, nickel peroxide, nickel sulfide, nickel sulfate, nickel hydrogen sulfate, nickel nitride, nickel nitrite, nickel phosphate and nickel thiocyanate, or organic compounds such as nickel oxalate and nickel acetate It can be used as it is or after being treated so that it can be dissolved in a solvent system with an acid or the like as required.

  Manganese (Mn) compounds include manganese hydroxide, manganese carbonate, manganese nitrate, manganese fluoride, manganese chloride, manganese bromide, manganese iodide, manganese chlorate, manganese perchlorate, manganese bromate. , Manganese iodate, manganese oxide, manganese phosphinate, manganese sulfide, manganese hydrogen sulfide, manganese nitrate, manganese hydrogen sulfate, manganese thiocyanate, manganese nitrite, manganese phosphate, manganese dihydrogen phosphate, manganese hydrogen carbonate, etc. An organic compound such as a manganese compound, or an organic compound such as manganese oxalate or manganese acetate can be used as it is or after being treated so that it can be dissolved in a solvent system with an acid or the like, if necessary.

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

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

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

(Second step)
In the second step, the composite oxide particles deposited with the hydroxide mainly composed of nickel (Ni) or manganese (Mn) in the first step are separated from the solvent system mainly composed of water, and thereafter The hydroxide is dehydrated by heat treatment, and a coating layer made of an oxide mainly composed of nickel (Ni) or manganese (Mn) is formed on the surface of the composite oxide particles. Here, the heat treatment is preferably performed at a temperature of, for example, about 300 ° C. to 1000 ° C. in an oxidizing atmosphere such as air or pure oxygen.

  In addition, after separating the composite oxide particles subjected to the deposition treatment in the first step from the solvent system, if necessary, in order to adjust the amount of lithium, impregnation with an aqueous solution of a lithium compound, and then heat treatment May be performed.

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

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

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

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

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

  This secondary battery is a so-called cylindrical type, and is a wound electrode in which a strip-shaped positive electrode 2 and a strip-shaped negative electrode 3 are wound via a separator 4 inside a substantially hollow cylindrical battery can 1. The separator 20 is impregnated with an electrolytic solution.

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

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

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

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

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

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

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

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

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

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

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

In addition, inorganic compounds that do not contain lithium (Li), such as MnO ₂ , V ₂ O ₅ , V ₆ O ₁₃ , NiS, and MoS, can also be used for any of the positive and negative electrodes.

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

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

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

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

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

[Separator]
Below, the separator material which can be utilized for 1st Embodiment is demonstrated. As a separator material, it is possible to use those used in conventional batteries. Among these, it is particularly preferable to use a polyolefin microporous film that is excellent in short-circuit prevention effect and can improve battery safety by a shutdown effect. For example, a microporous film made of polyethylene or polypropylene resin is preferable.

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

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

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

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

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

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

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

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

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

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

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

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

  The positive electrode 42 includes a strip-shaped positive electrode current collector 42A and a positive electrode mixture layer 42B formed on both surfaces of the positive electrode current collector 42A. The positive electrode current collector 42A is a metal foil made of, for example, aluminum (Al).

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

  The negative electrode 43 includes a strip-shaped negative electrode current collector 43A and a negative electrode mixture layer 43B formed on both surfaces of the negative electrode current collector 43A. The negative electrode current collector 43A is made of, for example, a metal foil such as a copper (Cu) foil, a nickel foil, or a stainless steel foil.

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

  Since things other than the gel electrolyte layer 45 are the same as those in the first example described above, the gel electrolyte layer 45 will be described below.

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

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

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

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

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

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these examples.

<Example 1>
First, a method for manufacturing the positive electrode active material used in this example is described below.
Commercially available reagent lithium carbonate (Li ₂ CO ₃ ) 38.1 parts by weight, cobalt carbonate (CoCO ₃ ) 116.5 parts by weight, aluminum hydroxide (Al (OH) ₃ ) 7.8 parts by weight, magnesium carbonate 8.4 parts by weight of (MgCO ₃ ) are mixed well while being pulverized with a ball mill. The mixture was then calcined in air at 650 ° C. for 5 hours, and further kept in air at 950 ° C. for 20 hours, and then cooled to 150 ° C. at 7 ° C./min. Next, it was taken out at room temperature and pulverized to produce composite oxide particles. The average particle diameter of the composite oxide particles measured by the laser scattering method is 13 μm, the content frequency of the particles having a particle diameter of 0.5 μm or less measured by the particle size distribution measurement is 0.03%, and the composite oxide particles The average chemical composition analysis value was Li _1.03 Co _0.98 Al _0.01 Mg _0.01 O _2.02 .

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

Next, this dispersion was subjected to decantation washing, and 0.1 part by weight of a commercially available reagent ammonium molybdate ((NH ₄ ) ₂ MoO ₄ ) was dissolved in 1.0 part by weight of pure water and added thereto. Furthermore, decantation washing was performed, and after final filtration, the precursor sample was dried at 120 ° C.

  In order to adjust the amount of lithium, 10 parts by weight of this precursor sample was impregnated with 2 parts by weight of a 2N LiOH aqueous solution and uniformly mixed and dried to obtain a calcined precursor. The calcined precursor was heated at a rate of 5 ° C./min using an electric furnace, held at 950 ° C. for 5 hours, and then cooled to 150 ° C. at 7 ° C./min to obtain a positive electrode active material.

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

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

  Further, 90 mol% of artificial graphite powder as a negative electrode active material and 10 mol% of polyvinylidene fluoride (PVdF) as a binder are mixed and dispersed in N-methyl-2-pyrrolidone which is a solvent, and then a strip having a thickness of 10 μm. It apply | coated on both surfaces of the negative electrode collector which consists of copper foils, it was made to dry, and it compression-molded with the roller press machine, the negative mix layer was formed, and the negative electrode was produced. Next, a negative electrode lead made of nickel was attached to the negative electrode current collector.

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

Thereafter, an electrolytic solution was injected into the battery can. In the electrolytic solution, LiPF ₆ as an electrolyte salt is dissolved at 1.0 mol / dm ³ in a solvent in which ethylene carbonate (EC) and diethyl carbonate (DEC) are mixed at a volume ratio of 1: 1. Was used. Further, the battery lid was caulked through a gasket to fix the safety valve mechanism, the heat sensitive resistance element, and the battery lid, and a cylindrical secondary battery having an outer diameter of 18 mm and a height of 65 mm was obtained.

<Example 2>
And ₍₂ CO ₃ Li) 38.1 parts by weight lithium carbonate commercially available reagents, cobalt carbonate (CoCO ₃₎ 113.0 parts by mass, and the aluminum hydroxide (Al (OH) ₃₎ 23.4 parts by weight, magnesium carbonate 16.9 parts by weight of (MgCO ₃ ) were mixed while being pulverized with a ball mill, and the mixture was calcined in air at 650 ° C. for 5 hours, and then calcined in air at 950 ° C. for 20 hours to obtain a composite oxide. Particles were made. The average particle diameter measured by the laser scattering method is 11 μm, the content frequency of particles having a particle diameter of 0.5 μm or less measured by particle size distribution measurement is 0.08%, and the average composition of the composite oxide particles is Li _1.03 Co _0.95 Al _0.03 Mg _0.02 O _2.02 .

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

Next, this dispersion was subjected to decantation washing, and 0.2 parts by weight of a commercially available reagent sodium molybdate (Na ₂ MoO ₄ ) was dissolved in 2.0 parts by weight of pure water and added thereto. Furthermore, decantation washing was performed, and after final filtration, the precursor sample was dried at 120 ° C.

  The precursor sample was heated at a rate of 5 ° C./min using an electric furnace, held at 950 ° C. for 5 hours, and then cooled to 150 ° C. at 7 ° C./min to obtain a positive electrode active material. Except for this, a cylindrical secondary battery was fabricated in the same manner as in Example 1.

<Example 3>
The composite oxide particles, and ₍₂ CO ₃ Li) 37.0 parts by weight of lithium carbonate commercially available reagents, cobalt carbonate (CoCO ₃₎ 113.0 parts by weight of aluminum hydroxide (Al (OH) ₃₎ 23.4 A cylindrical secondary battery was manufactured in the same manner as in Example 2 except that it was prepared by mixing 16.9 parts by mass of magnesium carbonate (MgCO ₃ ) and then heat-treated in air at 850 ° C. for 2 hours. Produced. In addition, by heat-treating the composite oxide particles, relatively fine particles dissolve in large particles, and the larger particles become larger and the content of fine particles decreases. The average particle size of the composite oxide particles measured by the laser scattering method is 7 μm, the content frequency of particles having a particle size of 0.5 μm or less measured by particle size distribution measurement is 0.3%, The average composition was Li _1.00 Co _0.95 Al _0.03 Mg _0.02 O _2.00 .

<Example 4>
The composite oxide particles produced in Example 2 were further pulverized twice, followed by pulverization, and then heat-treated in air at 850 ° C. for 10 hours. The average particle diameter of the composite oxide particles measured by a laser scattering method is 11 μm, the content frequency of particles having a particle diameter of 0.5 μm or less measured by particle size distribution measurement is 0.01%, The average composition was Li _1.03 Co _0.95 Al _0.03 Mg _0.02 O _2.02 .

<Example 5>
38.1 parts by weight of lithium carbonate (Li ₂ CO ₃ ) as a commercial reagent, 117.7 parts by weight of cobalt carbonate (CoCO ₃ ), and 7.8 parts by weight of aluminum hydroxide (Al (OH) ₃ ) were mixed. Except for the above, composite oxide particles were produced in the same manner as in Example 1. The average particle diameter of the composite oxide particles measured by a laser scattering method is 12 μm, the content frequency of particles having a particle diameter of 0.5 μm or less measured by particle size distribution measurement is 0.03%, and the composite oxide particles The average chemical composition analysis value was Li _1.03 Co _0.99 Al _0.01 O _2.02 .

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

  Next, the dispersion was washed by filtration and dried at 120 ° C. The composite oxide having a coating layer formed by adding 0.02 part by weight of aluminum oxide fine particles to 10 parts by weight of the composite oxide particles having a coating layer formed on the surface and performing dry stirring and mixing. A precursor sample having good fluidity was prepared by coating the surface of the particles with aluminum oxide fine particles to form a surface layer. The precursor sample was heated at a rate of 5 ° C./min using an electric furnace, held at 950 ° C. for 5 hours, and then cooled to 150 ° C. at 7 ° C./min to obtain a positive electrode active material. Except for this, a cylindrical secondary battery was fabricated in the same manner as in Example 1.

<Example 6>
The composite oxide particles are sufficiently mixed while 38.1 parts by weight of commercially available reagent lithium carbonate (Li ₂ CO ₃ ) and 116.5 parts by weight of cobalt carbonate (CoCO ₃ ) are pulverized with a ball mill. Next, a cylindrical secondary battery was prepared in the same manner as in Example 2 except that 45.6 parts by weight of titanium ethoxide ((C ₂ H ₅ O) ₄ Ti) was dissolved in anhydrous ethyl alcohol. Produced. The average particle diameter of the composite oxide particles measured by the laser scattering method is 15 μm, the content frequency of particles having a particle diameter of 0.5 μm or less measured by the particle size distribution measurement is 0.02%, and the composite oxidation The average chemical composition analysis value of the physical particles was Li _1.03 Co _0.98 Ti _0.02 O _2.02 .

<Comparative Example 1>
The composite oxide particles, and ₍₂ CO ₃ Li) 37.0 parts by weight of lithium carbonate commercially available reagents, cobalt carbonate (CoCO ₃₎ 113.0 parts by weight of aluminum hydroxide (Al (OH) ₃₎ 23.4 A cylindrical secondary battery was produced in the same manner as in Example 2 except that it was produced by mixing 1 part by mass with 16.9 parts by mass of magnesium carbonate (MgCO ₃ ). The average particle size of the composite oxide particles measured by the laser scattering method is 6 μm, and the content frequency of particles having a particle size of 0.5 μm or less measured by particle size distribution measurement is 0.6%. The average composition of the particles was Li _1.00 Co _0.95 Al _0.03 Mg _0.02 O _2.00 .

<Comparative example 2>
The composite oxide particles produced in Example 2 were further pulverized twice to proceed pulverization. The average particle size of the composite oxide particles measured by the laser scattering method is 10 μm, the content frequency of particles having a particle size of 0.5 μm or less measured by particle size distribution measurement is 0.7%, The average composition was Li _1.03 Co _0.95 Al _0.03 Mg _0.02 O _2.02 .

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

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

(B) Capacity maintenance rate For the cylindrical secondary battery whose initial capacity was determined as in (a), charge and discharge was performed up to 200 cycles under the same conditions, and the discharge capacity at the 200th cycle was measured. The capacity retention rate with respect to was calculated from {(discharge capacity at 200th cycle / initial capacity) × 100}.

  Table 1 below shows the results of the evaluation.

  As can be seen from Table 1, composite oxide particles containing 0.5% or less of particles having a particle size of 0.5 μm or less were deposited with a metal hydroxide mainly composed of nickel (Ni) or manganese (Mn). In addition, by using a positive electrode active material in which a coating layer is formed by heat dehydration, a positive electrode active material capable of achieving both a high initial capacity and a capacity retention rate can be obtained.

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

  In the first example of the non-aqueous electrolyte battery, the non-aqueous electrolyte secondary battery having an electrolyte as an electrolyte, and in the second example of the non-aqueous electrolyte battery, the non-aqueous electrolyte secondary having a gel electrolyte as an electrolyte. Although the battery has been described, it is not limited thereto.

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

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

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

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Battery can 2 ... Positive electrode 2A ... Positive electrode collector 2B ... Positive electrode mixture layer 3A ... Negative electrode collector 3B ... Negative electrode mixture layer 3 ... Negative electrode 4. .. Separator 5, 6 ... Insulating plate 7 ... Battery cover 8 ... Safety valve mechanism 9 ... Heat sensitive resistance element 10 ... Gasket 11 ... Disc plate 12 ... Center pin 13 .. Positive electrode lead 14 ... Negative electrode lead 20 ... Winding electrode body 30 ... Battery element 32 ... Positive electrode lead 33 ... Negative electrode lead 34, 35 ... Resin piece 35 ... Negative electrode lead 36 ... Recess 37 ... Exterior material 42 ... Positive electrode 42A ... Positive electrode current collector 42B ... Positive electrode mixture layer 43 ... Negative electrode 43A ... Negative electrode current collector 43B ... Negative electrode Mixture layer 44 ... Separator 45 ... Gel electrolyte layer

Claims (9)

  Composite oxide particles containing at least lithium (Li) and cobalt (Co), having an average particle size of 2.0 μm or more and 50 μm or less, and 0.5% or less of particles having a particle size of 0.5 μm or less are formed of nickel ( A method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery, comprising depositing with a metal hydroxide mainly comprising Ni) or manganese (Mn), followed by heat dehydration. 2. The method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1, wherein the composite oxide particles have an average composition represented by chemical formula (1).
(Chemical formula 1)
_{Li (1 + x) Co (} 1-y) M y O (2-z)
(However, in chemical formula 1, M is magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), nickel. It consists of at least one element selected from (Ni), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), and tungsten (W), where x, y, and z are- (0.10 ≦ x ≦ 0.10, 0 ≦ y <0.50, −0.10 ≦ z ≦ 0.20)   The non-aqueous electrolyte secondary according to claim 1, wherein the deposition of the metal hydroxide mainly composed of nickel (Ni) or manganese (Mn) is performed in a solvent system mainly composed of water having a pH of 12 or more. A method for producing a positive electrode active material for a battery.   In the deposition of the metal hydroxide mainly composed of nickel (Ni) or manganese (Mn), the composite oxide particles are dispersed in a solvent system mainly composed of water having a pH of 12 or more, and nickel (Ni) or 4. A compound of manganese (Mn) is added, and a metal hydroxide mainly composed of nickel (Ni) or manganese (Mn) is deposited on the surface of the composite oxide particles. A method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery.   5. The method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 4, wherein the solvent system mainly composed of water having a pH of 12 or more contains lithium hydroxide.   The constituent ratio of nickel (Ni) and manganese (Mn) of the metal hydroxide mainly composed of nickel (Ni) or manganese (Mn) is from 100: 0 to 30:70 in molar ratio. The manufacturing method of the positive electrode active material for nonaqueous electrolyte secondary batteries of Claim 1.   40 mol% or less of the total amount of nickel (Ni) or manganese (Mn) of the metal hydroxide mainly composed of nickel (Ni) or manganese (Mn), magnesium (Mg), aluminum (Al), boron (B ), Titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), cobalt (Co), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), tungsten (W The method for producing a positive electrode active material for a nonaqueous electrolyte secondary battery according to claim 1, wherein at least one metal element selected from   2. The deposition weight of the metal hydroxide mainly composed of nickel (Ni) or manganese (Mn) is 0.5% by weight to 50% by weight of the composite oxide particle weight. The manufacturing method of the positive electrode active material for nonaqueous electrolyte secondary batteries as described. Compound oxide particles having an average composition represented by the chemical formula 1 and having an average particle size of 2.0 μm or more and 50 μm or less and a particle size of 0.5 μm or less of 0.5% or less are mixed with nickel (Ni) or manganese (Mn A positive electrode active material for a non-aqueous electrolyte secondary battery, wherein the positive electrode active material is deposited with a metal hydroxide mainly composed of
(Chemical formula 1)
_{Li (1 + x) Co (} 1-y) M y O (2-z)
(However, in chemical formula 1, M is magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), nickel. It consists of at least one element selected from (Ni), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), and tungsten (W), where x, y, and z are- (0.10 ≦ x ≦ 0.10, 0 ≦ y <0.50, −0.10 ≦ z ≦ 0.20)

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