JP2011113885A - Li-ni composite oxide particle powder for nonaqueous electrolyte secondary battery, method of manufacturing the same, and nonaqueous electrolyte secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide Li-Ni composite oxide particle powder large in discharge capacity and small in gas generation in high-temperature charging when used as a positive electrode active material of a nonaqueous electrolyte secondary battery. <P>SOLUTION: In relation to a Li-Ni composite oxide having a composition of Li<SB>x</SB>Ni<SB>1-y-z</SB>Co<SB>y</SB>M<SB>z</SB>Zr<SB>a</SB>Bi<SB>b</SB>Sb<SB>c</SB>O<SB>2</SB>, wherein 0.9≤x≤1.3, 0.1≤y≤0.35, 0<z≤0.35, 0≤a≤0.025, 0.0002≤b≤0.004, 0≤c≤0.002, 1.2≤b/c when c≠0, and M is at least one kind of an element selected from Al and Mn, in the Li-Ni composite oxide particle powder for the nonaqueous electrolyte secondary battery, the average primary particle diameter of primary particles constituting a secondary particle is 1-4 μm; and a surplus lithium hydroxide and lithium carbonate which are left during a baking reaction are removed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a Li—Ni composite oxide particle powder having a large charge / discharge capacity and a small gas generation amount when used as a positive electrode active material of a non-aqueous electrolyte secondary battery.

  In recent years, electronic devices such as AV devices and personal computers are rapidly becoming portable and cordless, and there is an increasing demand for secondary batteries having a small size, light weight, and high energy density as power sources for driving these devices. In recent years, in consideration of the global environment, electric vehicles and hybrid vehicles have been developed and put into practical use, and the demand for a lithium ion secondary battery having excellent storage characteristics as a large-scale application is increasing. Under such circumstances, a lithium ion secondary battery having advantages such as a large charge / discharge capacity and good storage characteristics has attracted attention.

Conventionally, as positive electrode active substances useful for high energy-type lithium ion secondary batteries having 4V-grade voltage, LiMn ₂ O ₄ of spinel structure, LiMnO ₂ having a zigzag layer structure, LiCoO ₂ of layered rock-salt structure, LiNiO _{2 and the} like are generally known, and lithium ion secondary batteries using LiNiO ₂ have attracted attention as batteries having a high charge / discharge capacity. However, since this material is inferior in thermal stability during charging and charge / discharge cycle durability, further improvement in characteristics is required.

That is, when LiNiO ₂ pulls out lithium, Ni ³⁺ becomes Ni ^{4+ and} yarn teller distortion occurs, and in the region where Li is pulled out 0.45, from hexagonal to monoclinic, and when further extracted, from monoclinic to hexagonal. And the crystal structure changes. Therefore, repeating the charge / discharge reaction makes the crystal structure unstable, the cycle characteristics deteriorate, and the reaction with the electrolyte solution due to oxygen release occurs, resulting in poor battery thermal stability and storage characteristics. there were. In order to solve this problem, research has been conducted on materials in which Co and Al are added to a part of Ni in LiNiO ₂ , but no material that has solved these problems has yet been obtained, and a more crystalline structure. A stable Li—Ni composite oxide is demanded.

  In addition, since the primary particle size of the Li-Ni composite oxide is small, in order to obtain a Li-Ni composite oxide with a high packing density, the physical properties should be set so that they form densely aggregated secondary particles. Need to control. However, the Li-Ni composite oxide formed with secondary particles has an increased surface area due to secondary particle destruction due to compression during electrode fabrication, and the reaction with the electrolyte is promoted during storage at high temperature charge state. The non-conductive film formed at the interface is characterized in that the resistance as a secondary battery increases. Therefore, in order to suppress gas generation during high-temperature storage, it is necessary to efficiently increase the primary particle size to such an extent that the discharge capacity does not decrease, thereby suppressing reaction with the electrolytic solution.

  That is, a Li—Ni composite oxide having a large discharge capacity and a small amount of gas generation during high-temperature charging is required as a positive electrode active material for a nonaqueous electrolyte secondary battery.

Conventionally, various improvements have been made to Li—Ni composite oxide powders in order to improve various properties such as increasing the primary particle size, stabilizing the crystal structure, and generating gas. For example, Bi, between the crystallite surfaces or crystallites of AMO ₂ (A represents one or more of Li and Na, and M represents one or more of Co, Ni, Fe, and Cr). A technique (Patent Document 1) in which at least one additive selected from Pb and B is present in the form of an oxide and the crystallite diameter is 2 μm or more, and part of Ni in the Li—Ni composite oxide is Co and A technique for stabilizing the crystal structure by substituting with one or more elements selected from various metal elements (Patent Document 2), selected from various metal elements on the surface of the Li-Ni composite oxide In addition, a technique for adhering one or more elements to suppress a reaction with an electrolytic solution (Patent Document 3) was selected from various metal elements having an average particle diameter of 1 μm or less on the surface of a Li—Ni composite oxide. At least one of oxide particles and carbon particles of one or more elements A technique for improving discharge rate characteristics by attaching a metal (Patent Document 4), a Li-Ni composite oxide, Sb, Bi, and a compound selected from these compounds and an oxide salt of a 16th element excluding oxygen A technique for suppressing an increase in impedance during a high-temperature charge / discharge cycle (Patent Document 5); primary particles of Li—Ni composite oxide containing one or more elements selected from various metal elements; 3 μm for suppressing the reactivity with the electrolytic solution (Patent Document 6), variously on the surface of the Li—Ni composite oxide containing one or more elements selected from various metal elements A technique (Patent Document 7) that suppresses the reaction with the electrolyte during charging / discharging at high temperature by attaching compound particles of one or more elements selected from metal elements, selected from various metal elements Containing one or more elements A technology for improving chemical properties in a high-temperature environment by increasing the concentration of metallic elements and halogen elements on the surface of Ni-Ni composite oxide with respect to Ni in the center of the secondary particles ( Patent Document 8), a technique for improving the bulk density of a Li—Ni composite oxide battery positive electrode by replacing Bi with Li—Ni composite oxide (Patent Document 9), and the like are known.

JP-A-8-055624 JP-A-8-78005 JP-A-8-279357 JP 2003-109599 A JP 2004-288501 A JP 2006-127955 A JP 2007-59142 A JP 2007-66745 A Japanese Patent Laid-Open No. 2005-50582

  As a positive electrode active material for a non-aqueous electrolyte secondary battery, a Li—Ni composite oxide that satisfies the above-mentioned characteristics is currently most demanded, but has not yet been obtained.

  That is, in Patent Document 1, Li is added to Bi, and a Li—Ni composite oxide having a primary particle size of 2 μm or more is obtained by baking at a baking temperature of 1000 ° C. or higher. It is presumed that the cation mixing of the Ni ions into the Li layer occurs and the discharge capacity decreases, and there is no description of the excess lithium existing at the particle interface. Insufficient to suppress.

  In Patent Document 2, the crystal structure is stabilized by substituting a part of Ni in the Li—Ni composite oxide with one or more elements selected from Co and various metal elements. There is no description about the size of primary particles of Li—Ni composite oxide and no description about excess lithium, and this technique alone is insufficient to suppress gas generation during high-temperature charge / discharge.

  Further, in Patent Documents 3, 4, 5, 7, and 8, one or more elements selected from various metal elements are attached to or attached to the surface of the Li—Ni composite oxide, or the surface metal elements. Although the reaction with the electrolyte is suppressed by increasing the amount, there is no description about the size of the primary particles and excess lithium present at the particle interface, and this technology alone suppresses gas generation during high-temperature charge / discharge. Not enough to

  In Patent Document 6, Ni-Co hydroxide or Ni-Co-Mn hydroxide particles that have been fired once are converted into oxides, and further selected from various metal elements in the form of chlorides or chloride oxides. Although the reactivity with electrolyte solution is suppressed by adding 1 or more types of elements and making primary particle | grains of Li-Ni complex oxide 1-3 micrometers, the hydroxide to be used is made into an oxide. In addition, it is assumed that there is a side reaction of the electrolyte due to residual chloride or chloride oxide, and there is no description of excess lithium existing at the particle interface. It is hard to say that it is enough to suppress the occurrence.

  Furthermore, the technique described in Patent Document 9 is a technique for improving the bulk density of the Li—Ni composite oxide battery positive electrode by substituting Bi for the Li—Ni composite oxide. The definition of primary particle size for improving generation is ambiguous, and it is possible to suppress reaction with the electrolyte at the interface of small primary particles that occurs when particles are destroyed by compression during electrode production only by Bi substitution. It is difficult to say that it is not sufficient as a method for obtaining a Li—Ni composite oxide with suppressed gas generation.

  Therefore, the present invention provides a technical problem of obtaining Li-Ni composite oxide particle powder having a large discharge capacity and low gas generation during high-temperature charging when used as a positive electrode active material of a non-aqueous electrolyte secondary battery. And

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

That is, in order to achieve the above object, the present invention provides a non-aqueous electrolyte secondary battery having a negative electrode and a positive electrode made of a material capable of occluding and releasing lithium metal or lithium ions. _{x Ni 1-y-z Co} y M z Zr a Bi b Sb c O 2 (0.9 ≦ x ≦ 1.3,0.1 ≦ y ≦ 0.35,0 <z ≦ 0.35,0 ≦ When a ≦ 0.025, 0.0002 ≦ b ≦ 0.004, 0 ≦ c ≦ 0.002, and c ≠ 0, 1.2 ≦ b / c, M is selected from Al and Mn Li—Ni composite oxide, which is at least one element), the primary particles constituting the secondary particles have an average primary particle diameter of 1 to 4 μm, and Li— for a non-aqueous electrolyte secondary battery Ni composite oxide particle powder (Invention 1).

  Further, in the present invention, 20 g of the Li—Ni composite oxide particle powder is stirred in 100 ml of water for 20 minutes, and then the supernatant liquid is filtered off and then titrated with 0.2 N hydrochloric acid to be obtained and eluted. The Li-Ni composite oxide particle powder for a non-aqueous electrolyte secondary battery according to the present invention 1, wherein the amount of lithium hydroxide is 0.25% or less and the amount of lithium carbonate is 0.15% or less (Invention 2).

  Further, the present invention relates to a nonaqueous electrolyte secondary battery using the Li—Ni composite oxide particle powder as a positive electrode active material and a negative electrode made of a material capable of occluding and releasing lithium metal or lithium ions. The Li-Ni composite oxide for a non-aqueous electrolyte secondary battery according to the present invention 1 or 2, wherein the amount of gas generated when stored at 85 ° C for 24 hours in a 2V charged state is 0.4 ml / g or less It is a particle powder (Invention 3).

  In addition, the present invention provides a Ni-Co hydroxide, at least one bismuth compound selected from an aluminum compound having an average primary particle size of 1 μm or less, a zirconium compound, a bismuth compound, and an antimony compound, a lithium compound, The non-aqueous electrolyte according to any one of the present invention 1 to 3, wherein the obtained mixture is fired, and then lithium hydroxide and lithium carbonate are removed in an acidic aqueous solution and fired again. It is a manufacturing method of the Li-Ni complex oxide particle powder for secondary batteries (this invention 4).

  In addition, the present invention provides a Ni—Co—Mn hydroxide, at least one kind containing at least a bismuth compound selected from an aluminum compound, a zirconium compound, a bismuth compound, and an antimony compound having an average primary particle size of 1 μm or less, lithium The mixture according to the present invention is calcined, the resulting mixture is calcined, lithium hydroxide and lithium carbonate are then removed in an acidic aqueous solution, and calcined again. It is a manufacturing method of the Li-Ni complex oxide particle powder for water electrolyte secondary batteries (this invention 5).

  In addition, the present invention uses a positive electrode containing a positive electrode active material comprising the Li—Ni composite oxide particle powder for a non-aqueous electrolyte secondary battery according to any one of the first to third aspects of the present invention. It is a water electrolyte secondary battery (Invention 6).

  In the Li—Ni composite oxide particle powder according to the present invention, since the average primary particle diameter of the primary particles constituting the secondary particles is 1 to 4 μm, the primary particle unit at the time of particle breakage due to compression at the time of electrode preparation Even if it is destroyed, the increase in the surface area can be suppressed, the reaction with the electrolyte solution at the particle interface can be suppressed, and the gas generation during high-temperature charge / discharge can be suppressed.

  In addition, the Li—Ni composite oxide particle powder according to the present invention was prepared by filtering 20 ml of the Li—Ni composite oxide particle powder in 100 ml of water for 20 minutes, filtering the supernatant, and then adding 0.2N hydrochloric acid. The amount of lithium hydroxide to be eluted is 0.25% or less and the amount of lithium carbonate is 0.15% or less, which is determined by titration with the use of an electrolyte, so that decomposition of the electrolyte by alkali during high-temperature charge / discharge is suppressed. Gas generation can be suppressed.

  Therefore, the Li—Ni composite oxide particle powder according to the present invention is suitable as a positive electrode active material for a non-aqueous electrolyte secondary battery.

2 is a SEM image of Li—Ni composite oxide particle powder obtained in Example 1. FIG. 3 is a SEM image of Li—Ni composite oxide particle powder obtained in Comparative Example 1. FIG. 2 is a powder X-ray diffraction pattern of Li—Ni composite oxide particle powders obtained in Examples 1, 9, and 17. FIG.

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

  First, the Li-Ni composite oxide particle powder for a non-aqueous electrolyte secondary battery according to the present invention will be described.

The composition of the Li—Ni composite oxide particle powder according to the present invention is Li _x Ni _1-yz Co _y M _z Zr _a Bi _b Sb _c O ₂ (0.9 ≦ x ≦ 1.3, 0.1 When ≦ y ≦ 0.35, 0 <z ≦ 0.35, 0 ≦ a ≦ 0.025, 0.0002 ≦ b ≦ 0.004, 0 ≦ c ≦ 0.002, and c ≠ 0, 2 ≦ b / c, where M is at least one element selected from Al and Mn.
When x is out of the above range, a high battery capacity Li—Ni composite oxide particle powder cannot be obtained. Preferably 0.98 ≦ x ≦ 1.10.
When y is smaller than 0.1, the yarn teller strain in which Ni ³⁺ becomes Ni ⁴⁺ cannot be suppressed, the charge / discharge efficiency in the initial charge / discharge cycle is lowered, and there are few merits of adding cobalt. When y is larger than 0.35, the cobalt content with a high metal cost increases, so the merit of the Li-Ni composite oxide is lower than that of LiCoO ₂ and the initial charge / discharge capacity is reduced. Becomes remarkable. Preferably 0.1 ≦ y ≦ 0.3, more preferably 0.15 ≦ y ≦ 0.25.
When z is larger than 0.35, the true density of the positive electrode active material is lowered, so that it is difficult to obtain a material with high filling properties, the charge / discharge capacity is remarkably lowered, and the charge / discharge capacity is high. The merit of the Li—Ni composite oxide is reduced. Al is preferably 0 <z ≦ 0.2, more preferably 0 <z ≦ 0.1, and Mn is preferably 0 <z ≦ 0.34, more preferably 0.1 ≦ z ≦ 0.1. 0.33.
When a is larger than 0.025, segregation of Zr to the interface of the primary particles occurs, and the surface resistance of lithium ions increases, so the initial discharge capacity decreases. Preferably 0 ≦ a ≦ 0.02, more preferably 0.001 ≦ a ≦ 0.02.
When b is smaller than 0.0002, the size of the primary particles becomes small, and when primary particles are broken due to compression during electrode production, small primary particles are generated, and the reaction with the electrolytic solution at the particle interface occurs. Become intense. When b is larger than 0.004, primary particles grow abnormally and the diffusion resistance of lithium ions increases, so the initial discharge capacity decreases. Preferably it is 0.0003 <= b <= 0.004, More preferably, it is 0.0004 <= b <= 0.003.
On the other hand, when c is larger than 0.002, the size of the primary particles becomes small due to the impurity effect, and small primary particles are generated at the time of particle breakage due to compression during electrode preparation, and electrolysis at the particle interface is caused. Reaction with liquid becomes intense. Preferably 0 ≦ c ≦ 0.001.
Furthermore, when c is not 0, when b / c is smaller than 1.2, the size of the primary particles becomes small, and small primary particles are generated in the case of particle breakage due to compression during electrode production, The reaction with the electrolyte at the particle interface becomes intense. Preferably 1.2 ≦ b / c ≦ 8.0, more preferably 1.3 ≦ b / c ≦ 6.0.

The BET specific surface area of the Li—Ni composite oxide particle powder according to the present invention is preferably 0.1 to 1.6 m ² / g. When the BET specific surface area value is less than 0.1 m ² / g, it is difficult to produce industrially. When it exceeds 1.6 m < ² > / g, since the fall with a packing density and the reactivity with electrolyte solution increase, it is unpreferable. A more preferable BET specific surface area is 0.3 to 1.0 m ² / g.

  The average primary particle diameter of the primary particles constituting the secondary particles of the Li—Ni composite oxide particles according to the present invention is 1 to 4 μm, and good high-temperature charge / discharge with less gas generation in the nonaqueous electrolyte secondary battery. Characteristics are obtained. When the average primary particle diameter exceeds 4 μm, the diffusion resistance of lithium ions becomes high, so that the initial discharge capacity decreases. When it is smaller than 1 μm, small primary particles are generated at the time of particle destruction due to compression during electrode production, and the reaction with the electrolyte at the particle interface becomes intense. A preferable average primary particle diameter is 1 to 3 μm.

  The average secondary particle diameter of the Li—Ni composite oxide particle powder according to the present invention is preferably 1.0 to 20 μm. An average secondary particle size of less than 1.0 μm is not preferable because a decrease in packing density and an increase in reactivity with the electrolytic solution. When it exceeds 20 μm, it is difficult to produce industrially. A more preferable average secondary particle size is 3.0 to 17.0 μm.

  The Li-Ni composite oxide particle powder according to the present invention is obtained by eluating 20 g of the powder after stirring for 20 minutes in 100 ml of water, and then titrating with 0.2 N hydrochloric acid after filtration. The amount of lithium hydroxide to be added is 0.25% or less and the amount of lithium carbonate is 0.15% or less, and good high-temperature charge / discharge characteristics with less gas generation can be obtained in the nonaqueous electrolyte secondary battery. When the elution amount of lithium hydroxide exceeds 0.25% and the elution amount of lithium carbonate exceeds 0.15%, decomposition of the electrolyte solution by alkali during high-temperature charge / discharge is accelerated, and gas generation becomes intense. More preferably, the elution amount of lithium hydroxide is 0.20% or less and the elution amount of lithium carbonate is 0.1% or less.

  The secondary particles of the Li—Ni composite oxide particles according to the present invention preferably have a secondary particle shape that is spherical and has few acute angles.

  Next, a method for producing the Li—Ni composite oxide particle powder according to the present invention will be described.

  The Li—Ni composite oxide particle powder according to the present invention includes Ni—Co hydroxide and at least a bismuth compound selected from an aluminum compound having an average primary particle size of 1 μm or less, a zirconium compound, a bismuth compound, and an antimony compound. It can be obtained by mixing one or more types and a lithium compound, firing the resulting mixture, removing lithium hydroxide and lithium carbonate in an acidic aqueous solution, and firing again.

  The Li—Ni composite oxide particle powder according to the present invention is at least selected from Ni—Co—Mn hydroxide, an aluminum compound having an average primary particle size of 1 μm or less, a zirconium compound, a bismuth compound, and an antimony compound. It can be obtained by mixing one or more kinds containing a bismuth compound and a lithium compound, firing the resulting mixture, removing lithium hydroxide and lithium carbonate in an acidic aqueous solution, and firing again.

  The Ni—Co hydroxide or Ni—Co—Mn hydroxide particle powder in the present invention contains 0.1 to 2.0 mol / l nickel sulfate and cobalt sulfate or nickel sulfate, cobalt sulfate, and manganese sulfate. A solution mixed so as to have a molar ratio and a 1.0 to 15.0 mol / l aqueous ammonia solution are simultaneously supplied to a stirred reaction tank at the same time, and at the same time the pH is adjusted to 10.0 to 12.0. Add 1-2.0 mol / l sodium hydroxide solution, and circulate the generated particles to the reaction tank while adjusting the concentration rate in the overflow tank connected to the overflow pipe. The reaction can be performed until the Ni—Co hydroxide concentration in the tank reaches 2 to 4 mol / l, and particle control by mechanical collision can be performed.

  Further, Ni—Co hydroxide or Ni—Co—Mn hydroxide particle powder is obtained by using a filter press, a vacuum filter, a filter thickener, or the like to remove the coexisting soluble salts generated during the reaction. It can be obtained by washing with water using 1 to 10 times as much water as the Co hydroxide or Ni-Co-Mn hydroxide slurry weight and drying.

The Ni—Co hydroxide or Ni—Co—Mn hydroxide particle powder in the present invention has an average primary particle diameter of 1 μm or less, an average secondary particle diameter of 2 to 30 μm, and a BET specific surface area of 1 to 15 m ² / g. It is preferable that

  The aluminum compound used in the present invention is preferably a hydroxide, and the zirconium compound, bismuth compound, and antimony compound are preferably oxides. The average primary particle diameter of the aluminum compound, zirconium compound, bismuth compound, and antimony compound is preferably 1 μm or less, and the average secondary particle diameter is preferably 5 μm or less, more preferably 2 μm or less.

  The addition amount of the aluminum compound is preferably 0 to 35%, more preferably 0 to 20%, and still more preferably the molar ratio in terms of Al with respect to the Ni—Co hydroxide or Ni—Co—Mn hydroxide. Is 2 to 10%. If it is less than 2%, the thermal stability is lowered, and if it exceeds 10%, the discharge capacity may be lowered.

  The addition amount of the bismuth compound is preferably 0.02 to 0.4% in terms of a molar ratio in terms of Bi with respect to Ni-Co hydroxide or Ni-Co-Mn hydroxide. When the amount is less than 0.02, the size of the primary particles becomes small. When the amount exceeds 0.4%, the primary particles grow abnormally and the discharge capacity decreases. More preferably, it is 0.03 to 0.4%.

  The addition amount of the zirconium compound is preferably 0 to 2.5%, more preferably 0.1 to 2% in terms of a molar ratio in terms of Zr with respect to the Ni—Co hydroxide or Ni—Co—Mn hydroxide. It is. When it exceeds 2.5%, the discharge capacity decreases. If it is less than 0.1%, gas generation during high-temperature charge / discharge may increase.

  The addition amount of the antimony compound is preferably 0 to 0.2% in terms of a molar ratio in terms of Sb with respect to Ni—Co hydroxide or Ni—Co—Mn hydroxide, and more preferably 0.0125 to 0. 2%. If it exceeds 0.2%, the size of the primary particles becomes small, and gas generation during high-temperature charge / discharge becomes intense. When it is less than 0.0125%, the primary particle size becomes non-uniform, and the effect of improving gas generation may be reduced.

  Mixing treatment of Ni-Co hydroxide or Ni-Co-Mn hydroxide with aluminum compound, zirconium compound, bismuth compound, antimony compound and lithium compound is either dry or wet as long as they can be mixed uniformly. But you can.

  The mixing ratio of the lithium compound is 0.9 to 1.3 with respect to the total number of moles of metal of Ni—Co hydroxide or Ni—Co—Mn hydroxide and aluminum compound, zirconium compound, bismuth compound, and antimony compound. It is preferable that it is 0.98 to 1.10.

  The lithium compound used is preferably lithium hydroxide when mixed with Ni-Co hydroxide, and may be either lithium hydroxide or lithium carbonate when mixed with Ni-Co-Mn hydroxide.

  Moreover, it is preferable that the average particle diameter of the lithium compound to be used is 50 micrometers or less, More preferably, it is 30 micrometers or less. When the average particle size of the lithium compound exceeds 50 μm, Ni—Co hydroxide or Ni—Co—Mn hydroxide and an aluminum compound, zirconium compound, bismuth compound, and antimony compound having an average primary particle size of 1 μm or less Mixing becomes uneven and it becomes difficult to obtain Li—Ni composite oxide particle powder having good crystallinity. In addition, the average particle diameter of the lithium compound was measured using a laser type particle size distribution measuring apparatus LMS-30 [manufactured by Seishin Enterprise Co., Ltd.].

The firing temperature of the mixture is preferably 650 ° C. to 980 ° C., depending on the type and amount of the substitution element. When the temperature is lower than 650 ° C., the reaction between Li and Ni does not proceed sufficiently, and the growth of primary particles of Li—Ni composite oxide particles becomes insufficient. In the composition of the Li—Ni composite oxide particles according to the present invention, when Ni / (Ni + Co + M) is 0.8 or more, when the firing temperature exceeds 800 ° C., Ni ³⁺ is reduced to Ni ²⁺ to form the Li phase. The layered structure cannot be maintained. When Ni / (Ni + Co + M) is less than 0.8, if it exceeds 980 ° C., Ni ³⁺ is reduced to Ni ²⁺ and mixed into the Li phase, and the layered structure cannot be maintained. The atmosphere during firing is preferably an oxidizing gas atmosphere, and more preferably the oxygen concentration in the atmosphere is 70% or more. The firing time is preferably 3 to 20 hours.

  In the present invention, the Li—Ni composite oxide obtained by firing is dispersed and stirred in an acidic solution such as sulfuric acid, phosphoric acid, nitric acid, hydrochloric acid, etc., so that excess lithium hydroxide and lithium carbonate remaining during the firing reaction are obtained. The Li—Ni composite oxide particle powder with a small amount of lithium hydroxide and a small amount of lithium carbonate can be obtained. Hereinafter, lithium hydroxide and lithium carbonate are referred to as excess lithium.

  The solution used for removing excess lithium is not particularly limited, but sulfuric acid is preferable in view of industrial productivity. The concentration of the sulfuric acid solution is preferably 1 / 100N to 1 / 10N. When it is thinner than 1/100 N, the elution of Al in the crystal increases when the excess lithium is removed, and the crystal structure is destroyed. When the amount exceeds 1/10 N, elution of Li in the crystal increases during the removal of excess lithium, and the crystal structure is destroyed.

Furthermore, it is preferable to fire the Li—Ni composite oxide from which excess lithium has been removed at 400 ° C. to 850 ° C. When the temperature is lower than 400 ° C., the refiring reaction between the lithium carbonate remaining during the removal of excess lithium and the Li—Ni composite oxide does not proceed, and the charge / discharge cycle characteristics deteriorate. In the composition of the Li—Ni composite oxide particles according to the present invention, when Ni / (Ni + Co + M) is 0.8 or more, Ni ³⁺ is reduced to Ni ²⁺ when the firing temperature exceeds 800 ° C. It mixes into the Li phase and the layered structure cannot be maintained. Even when Ni / (Ni + Co + M) is less than 0.8, when the firing temperature exceeds 850 ° C., Ni ³⁺ is reduced to Ni ²⁺ and mixed into the Li phase, and the layered structure cannot be maintained. The atmosphere during firing is preferably an oxidizing gas atmosphere, and more preferably the oxygen concentration in the atmosphere is 70% or more. The firing time is preferably 1 to 10 hours.

  Next, the positive electrode using the positive electrode active material which consists of Li-Ni complex oxide particle powder concerning this invention is described.

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

  The secondary battery manufactured using the positive electrode active material according to the present invention includes the positive electrode, the negative electrode, and an electrolyte.

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

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

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

  The secondary battery manufactured using the positive electrode active material according to the present invention has an initial discharge capacity of about 160 to 195 mAh / g, and a gas generation amount after high-temperature storage measured by an evaluation method described later is 0.44 ml / g. The following excellent properties are shown.

<Action>
As the cause of gas generation at the time of high-temperature charge / discharge of the nonaqueous electrolyte secondary battery, the primary particles of the Li-Ni composite oxide are small, and small primary particles are generated at the time of particle destruction due to compression during electrode production, This is because the reaction with the electrolyte at the particle interface becomes intense. In order to solve the above-mentioned problems, it is important to increase the primary particles of the Li—Ni composite oxide and to reduce the excess lithium at the new interface that was generated when the particles were destroyed by the compression during electrode preparation. In other words, it is difficult to say that only the techniques listed in the prior art documents are sufficient to suppress gas generation during high-temperature charge / discharge.

  Therefore, in the present invention, by setting the average primary particle diameter of the primary particles constituting the secondary particles to 1 to 4 μm, a large increase in surface area is suppressed even when a new interface is exposed during compression and molding. It has been done. As a result, the reaction with the electrolytic solution during high-temperature charge / discharge is suppressed, and the amount of gas generated can be reduced.

  The Li—Ni composite oxide particles according to the present invention are obtained by titrating with 0.2N hydrochloric acid after filtering the supernatant after 20 g of the powder is stirred in 100 ml of water for 20 minutes. Since the amount of lithium hydroxide to be eluted is 0.25% or less and the amount of lithium carbonate is 0.15% or less, the decomposition reaction of the electrolytic solution by alkali during high-temperature charge / discharge is suppressed, and the amount of gas generation is reduced. It becomes possible to do.

  The Li—Ni composite oxide particle powder according to the present invention comprises at least a bismuth compound selected from an Ni—Co hydroxide and an aluminum compound having an average primary particle size of 1 μm or less, a zirconium compound, a bismuth compound, and an antimony compound. One or more types and a lithium compound are mixed and baked, and then the lithium hydroxide and lithium carbonate are removed in an acidic aqueous solution and baked again, whereby the reaction proceeds uniformly, and Li having high crystallinity -Ni composite oxide particle powder is obtained, and gas generation at high temperature charge / discharge can be suppressed while maintaining high discharge capacity and safety during charging.

  A typical embodiment of the present invention is as follows.

  The composition of the Li—Ni composite oxide particles according to the present invention was determined by dissolving the powder with an acid and measuring with “Plasma emission spectroscopic analyzer ICPS-7500 (Shimadzu Corporation)”.

  The average secondary particle diameter is a volume-based average particle diameter measured by a wet laser method using a laser particle size distribution analyzer LMS-30 [manufactured by Seishin Enterprise Co., Ltd.].

  The average primary particle diameter is the particle diameter of primary particles constituting secondary particles when observed using a scanning electron microscope SEM-EDX with an energy dispersive X-ray analyzer [manufactured by Hitachi High-Technologies Corporation].

The amount of lithium hydroxide and lithium carbonate, which are excess lithium, is obtained by adding 20 g of Li-Ni composite oxide particle powder to 100 ml of water and stirring for 20 minutes at room temperature. The obtained supernatant was titrated with 0.2N hydrochloric acid. On the pH curve that can be drawn by plotting the titration amount (ml) on the horizontal axis and the pH of the supernatant on the vertical axis, the two points with the largest slope are the first titration point and The second titration point was used, and each amount was calculated from the titration amount at those points using the following calculation formula.
Lithium hydroxide amount (%) = [(Titration to the second titration point: ml) −2 × {(Titration to the second titration point) − (Titration to the first titration point: ml)}] X (concentration of hydrochloric acid used for titration: mol / l) x (factor of hydrochloric acid used for titration) x (molecular weight of lithium hydroxide) x 2 x 100 / ((powder weight: g) x 1000)
Lithium carbonate amount (%) = {(Titration to the second titration point: ml) − (Titration to the first titration point: ml)} × (Concentration of hydrochloric acid used for titration: mol / l) × ( Factor of hydrochloric acid used for titration) × (molecular weight of lithium carbonate) × 2 × 100 / {(powder weight: g) × 1000}

  X-ray diffraction was performed under the conditions of Cu-Kα, 40 kV, and 40 mA using an X-ray diffractometer RINT-2000 [manufactured by Rigaku Corporation].

  Using the Li-Ni composite oxide particle powder, initial charge / discharge characteristics using a coin cell and high-temperature storage characteristics using a laminate cell were evaluated.

First, 90% by weight of Li—Ni composite oxide particle powder as a positive electrode active material, 3% by weight of acetylene black as a conductive material, 3% by weight of graphite KS-16, and polyvinylidene fluoride dissolved in N-methylpyrrolidone as a binder After mixing 4% by weight, it was applied to an Al metal foil and dried at 150 ° C. The sheet was punched to 16 mmφ, and then pressure-bonded at 1 t / cm ² to make the electrode thickness 50 μm. A CR2032-type coin cell was manufactured using a lithium mixed with 1 mol / l of LiPF ₆ dissolved in EC and DMC at a volume ratio of 1: 2 with a negative electrode made of metallic lithium punched to 16 mmφ.

The initial charge / discharge characteristics are as follows. In the above coin cell, after charging at room temperature to 0.2V / 0.2 mA / cm ² , discharge to 3.0V / 0.2 mA / cm ² and initial charge at that time The discharge capacity was measured.

  In addition, a laminate cell was fabricated by using the same electrode as in the evaluation of the initial charge / discharge characteristics and combining 4 sets of metal lithium having the same size as the 40 × 100 mm positive electrode so as to face each other.

  The high-temperature storage characteristic evaluation was performed by first charging and discharging at room temperature in the laminate cell, then charging to 4.2 V, and measuring the volume of the laminate cell at this voltage. Next, after storing the cell after measurement for 24 hours in an environment of 85 ° C., the volume of the laminate cell was measured again, and the amount of gas generation was evaluated from the volume change before and after high-temperature storage.

[Example 1]
An aqueous solution in which 2 mol / l nickel sulfate and cobalt sulfate were mixed so that Ni: Co = 84: 16 and a 5.0 mol / l ammonia aqueous solution were simultaneously supplied into the reaction vessel.
The reaction tank was always stirred with a blade-type stirrer, and at the same time, a 2 mol / l sodium hydroxide aqueous solution was automatically supplied so that the pH was 11.5 ± 0.5. The produced Ni—Co hydroxide is overflowed and concentrated in a concentration tank connected to the overflow pipe, and the concentrate is circulated to the reaction tank. The concentration of Ni—Co hydroxide in the reaction tank and the concentration tank is 4 mol. The reaction was continued for 40 hours until it reached / l.

  After the reaction, the taken-out suspension was washed with water 10 times the weight of Ni—Co hydroxide using a filter press, dried, and Ni: Co = 84.2: 15. .8 hydroxide particles were obtained.

  Ni-Co hydroxide, aluminum hydroxide having an average primary particle size of 0.5 μm and an average secondary particle size of 1.5 μm, bismuth oxide having an average primary particle size of 0.5 μm and an average secondary particle size of 2 μm, Lithium hydroxide monohydrate having a lithium carbonate content of 0.3 wt% and an average particle size of 20 μm, whose particle size was adjusted by a pulverizer, was mixed so that the molar ratio was Li / (Ni + Co + Al + Bi) = 1.02.

This mixture was fired at 750 ° C. for 10 hours in an oxygen atmosphere and crushed. 1 kg of this Li-Ni composite oxide particle powder was suspended and stirred in a 1/50 N sulfuric acid solution for 10 minutes, then washed with 10 times more water, dried, and baked again at 700 ° C. for 2 hours in an oxygen atmosphere. Crushed. The chemical composition of the obtained fired product is Li _0.99 Ni _0.8 Co _0.15 Al _0.04 Bi _0.0005 O ₂ , the average secondary particle diameter is 15 μm, and the average primary particle diameter by SEM observation is It was 1.1 μm. An SEM photograph of this Li-Ni composite oxide particle powder is shown in FIG.

  After 20 g of this Li-Ni composite oxide particle powder was suspended and stirred in 100 ml of water for 10 minutes, the supernatant was filtered off, and the lithium hydroxide content and lithium carbonate content therein were evaluated using a titration method. As a result, the amount of lithium hydroxide was 0.22%, and the amount of lithium carbonate was 0.09%. Moreover, the discharge capacity of the cell using this Li-Ni complex oxide particle powder was 193 mAh / g, and the amount of gas generated after storage at 85 ° C. for 24 hours was 0.39 ml / g.

[Examples 2 to 8]
Performed in the same manner as in Example 1, the obtained Ni—Co hydroxide, aluminum hydroxide having an average primary particle size of 0.5 μm and an average secondary particle size of 1.5 μm, and an average primary particle size of 0.5 μm Bismuth oxide with an average secondary particle size of 2 μm, antimony oxide with an average primary particle size of 0.6 μm and an average secondary particle size of 2.3 μm, zirconium oxide with an average primary particle size of 0.5 μm and an average secondary particle size of 2 μm Li / (Ni + Co + Al + Bi + Sb + Zr) so that the lithium carbonate monohydrate having a lithium carbonate content of 0.3 wt% and an average particle diameter of 20 μm, which has been adjusted in particle size by a pulverizer, has a molar composition of a predetermined composition ratio. Except for mixing so as to be equal to 1.02, the same procedure as in Example 1 was performed to obtain Li—Ni—Co—Al—Zr—Bi—Sb composite oxide particle powders having different chemical compositions. The composition and production conditions of these materials are shown in Table 1, and the average primary particle diameter, lithium hydroxide amount, lithium carbonate amount, initial discharge capacity, and gas generation amount are shown in Table 2.

[Example 9]
An aqueous solution in which 2 mol / l nickel sulfate, cobalt sulfate, and manganese sulfate were mixed so that Ni: Co: Mn = 60: 20: 20 and an aqueous 5.0 mol / l ammonia solution were simultaneously supplied into the reaction vessel.
The reaction tank was always stirred with a blade-type stirrer, and at the same time, a 2 mol / l sodium hydroxide aqueous solution was automatically supplied so that the pH was 11.5 ± 0.5. The produced Ni—Co—Mn hydroxide is overflowed and concentrated in a concentration tank connected to the overflow pipe, and the concentrate is circulated to the reaction tank, and Ni—Co—Mn hydroxylation in the reaction tank and the concentration tank is obtained. The reaction was carried out for 40 hours until the product concentration reached 4 mol / l.

  After the reaction, the taken-out suspension was washed with water 10 times the weight of the Ni—Co—Mn hydroxide using a filter press, dried, and Ni: Co: Mn = 60. : Ni: Co-Mn hydroxide particles having an average secondary particle size of 20:20 of 9.5 μm were obtained.

  Ni—Co—Mn hydroxide, bismuth oxide having an average primary particle size of 0.5 μm and an average secondary particle size of 2 μm, and lithium carbonate were mixed in a molar ratio of Li / (Ni + Co + Mn) = 1.05. .

This mixture was fired at 890 ° C. for 5 hours in an oxygen atmosphere and crushed. 1 kg of this Li-Ni composite oxide particle powder was suspended and stirred in a 1/50 N sulfuric acid solution for 10 minutes, then washed with 10 times more water, dried, and baked again at 800 ° C. for 2 hours in an oxygen atmosphere. Crushed. The chemical composition of the obtained fired product is Li _1.03 Ni _0.60 Co _0.20 Mn _0.20 Bi _0.0005 O _{2 as} a result of ICP analysis, and the average secondary particle size is 9.5 μm, The average primary particle diameter by SEM observation was 1.3 μm.

  After 20 g of this Li-Ni composite oxide particle powder was suspended and stirred in 100 ml of water for 10 minutes, the supernatant was filtered off, and the lithium hydroxide content and lithium carbonate content therein were evaluated using a titration method. As a result, the amount of lithium hydroxide was 0.06%, and the amount of lithium carbonate was 0.05%. Moreover, the discharge capacity of the cell using this Li-Ni complex oxide particle powder was 177 mAh / g, and the amount of gas generated after storage at 85 ° C. for 24 hours was 0.31 ml / g.

[Examples 10 to 16]
Ni—Co—Mn hydroxide obtained in the same manner as in Example 9, bismuth oxide having an average primary particle size of 0.5 μm and an average secondary particle size of 2 μm, and an average primary particle size of 0.6 μm and an average Antimony oxide with a secondary particle size of 2.3 μm, zirconium oxide with an average primary particle size of 0.5 μm and an average secondary particle size of 2 μm, and lithium carbonate in a molar ratio of Li / ( Li-Ni-Co-Mn-Zr-Sb composite oxide particles having a different chemical composition were carried out in the same manner as in Example 9 except that Ni + Co + Mn-Zr-Bi-Sb) = 1.05. Got. The composition and production conditions of these materials are shown in Table 1, and the average primary particle diameter, lithium hydroxide amount, lithium carbonate amount, initial discharge capacity, and gas generation amount are shown in Table 2.

[Examples 17 to 24]
Using a mixed aqueous solution of 2 mol / l nickel sulfate, cobalt sulfate, and manganese sulfate such that Ni: Co: Mn = 50: 20: 30, the Ni—Co—Mn hydroxide particles were obtained, and the air atmosphere Then, after calcination for 5 hours at 950 ° C. and pulverization, 1 kg of this Li—Ni composite oxide particle powder is suspended and stirred in a 1/50 N sulfuric acid solution for 10 minutes, further washed with 10 times water and dried. Then, Li-Ni-Co-Mn-Zr-Sb having a different chemical composition was carried out in the same manner as in Example 9 and Examples 10-16 except that calcination was carried out at 800 ° C. for 2 hours in an air atmosphere. A composite oxide particle powder was obtained. The composition and production conditions of these materials are shown in Table 1, and the average primary particle diameter, lithium hydroxide amount, lithium carbonate amount, initial discharge capacity, and gas generation amount are shown in Table 2.

[Comparative Example 1]
Ni—Co hydroxide obtained in the same manner as in Example 1, aluminum hydroxide having an average primary particle size of 0.5 μm and an average secondary particle size of 1.5 μm, and carbonic acid whose particle size was adjusted in advance by a pulverizer A mixture obtained by mixing lithium hydroxide monohydrate having a lithium content of 0.3 wt% and an average particle diameter of 20 μm in a molar ratio of Li / (Ni + Co + Al) = 1.02 in an oxygen atmosphere at 750 ° C. After firing for 10 hours, the powder was crushed to obtain Li-Ni composite oxide particle powder. The obtained fired product has a chemical composition of Li _1.02 Ni _0.8 Co _0.15 Al _0.04 O ₂ , an average secondary particle size of 15 μm, and an average primary particle size by SEM observation of 0.7 μm. there were. An SEM photograph of the Li—Ni composite oxide particles is shown in FIG. After 20 g of this Li-Ni composite oxide particle powder was suspended and stirred in 100 ml of water for 10 minutes, the supernatant was filtered off, and the lithium hydroxide content and lithium carbonate content therein were evaluated using a titration method. As a result, the lithium hydroxide amount was 0.51% and the lithium carbonate amount was 0.38%. Moreover, the discharge capacity of the cell using this Li-Ni complex oxide particle powder was 192 mAh / g, and the amount of gas generated after storage at 85 ° C. for 24 hours was 1.88 ml / g.

[Comparative Example 2]
Ni—Co hydroxide obtained in the same manner as in Example 1, aluminum hydroxide having an average primary particle size of 0.5 μm and an average secondary particle size of 1.5 μm, and carbonic acid whose particle size was adjusted in advance by a pulverizer Except that lithium hydroxide monohydrate having a lithium content of 0.3 wt% and an average particle diameter of 20 μm was mixed in a molar ratio of Li / (Ni + Co + Al) = 1.02, the same as in Example 1 Thus, Li—Ni composite oxide particle powder was obtained. The chemical composition of the obtained fired product is Li _0.99 Ni _0.8 Co _0.15 Al _0.04 O ₂ , the average secondary particle size is 15 μm, and the average primary particle size by SEM observation is 0.7 μm. there were. After 20 g of this Li-Ni composite oxide particle powder was suspended and stirred in 100 ml of water for 10 minutes, the supernatant was filtered off, and the lithium hydroxide content and lithium carbonate content therein were evaluated using a titration method. As a result, the amount of lithium hydroxide was 0.28%, and the amount of lithium carbonate was 0.16%. Moreover, the discharge capacity of the cell using this Li-Ni complex oxide particle powder was 193 mAh / g, and the amount of gas generated after storage at 85 ° C. for 24 hours was 0.45 ml / g.

[Comparative Examples 3 to 7]
Performed in the same manner as in Example 1, the obtained Ni—Co hydroxide, aluminum hydroxide having an average primary particle size of 0.5 μm and an average secondary particle size of 1.5 μm, and an average primary particle size of 0.5 μm Bismuth oxide with an average secondary particle size of 2 μm, antimony oxide with an average primary particle size of 0.6 μm and an average secondary particle size of 2.3 μm, zirconium oxide with an average primary particle size of 0.5 μm and an average secondary particle size of 2 μm Li / (Ni + Co + Al + Bi + Sb + Zr) so that the lithium carbonate monohydrate having a lithium carbonate content of 0.3 wt% and an average particle diameter of 20 μm, which has been adjusted in particle size by a pulverizer, has a molar composition of a predetermined composition ratio. Except for mixing so as to be equal to 1.02, the same procedure as in Example 1 was performed to obtain Li—Ni—Co—Al—Zr—Bi—Sb composite oxide particle powders having different chemical compositions. Table 3 shows the composition and production conditions of these materials, and Table 4 shows the average primary particle diameter, lithium hydroxide amount, lithium carbonate amount, initial discharge capacity, and gas generation amount.

[Comparative Example 8]
A mixture obtained by mixing Ni—Co—Mn hydroxide obtained in the same manner as in Example 9 and lithium carbonate so as to have a molar ratio of Li / (Ni + Co + Mn) = 1.05 was 890 ° C. in an oxygen atmosphere. And then pulverized to obtain Li—Ni composite oxide particle powder. The obtained fired product has a chemical composition of Li _1.05 Ni _0.60 Co _0.20 Mn _0.20 O ₂ , an average secondary particle size of 15 μm, and an average primary particle size by SEM observation of 0.7 μm. there were.

  After 20 g of this Li-Ni composite oxide particle powder was suspended and stirred in 100 ml of water for 10 minutes, the supernatant was filtered off, and the lithium hydroxide content and lithium carbonate content therein were evaluated using a titration method. As a result, the amount of lithium hydroxide was 0.27% and the amount of lithium carbonate was 0.17%. Further, the discharge capacity of the cell using this Li—Ni composite oxide particle powder was 177 mAh / g, and the gas generation amount after storage at 85 ° C. for 24 hours was 0.74 ml / g.

[Comparative Example 9]
Similar to Example 9, except that Ni—Co—Mn hydroxide obtained in the same manner as in Example 9 and lithium carbonate were mixed so that the molar ratio was Li / (Ni + Co + Mn) = 1.05. To obtain Li—Ni composite oxide particle powder. The obtained fired product has a chemical composition of Li _1.05 Ni _0.60 Co _0.20 Mn _0.20 O ₂ , an average secondary particle size of 15 μm, and an average primary particle size by SEM observation of 0.7 μm. there were.

  After 20 g of this Li-Ni composite oxide particle powder was suspended and stirred in 100 ml of water for 10 minutes, the supernatant was filtered off, and the lithium hydroxide content and lithium carbonate content therein were evaluated using a titration method. As a result, the amount of lithium hydroxide was 0.06%, and the amount of lithium carbonate was 0.07%. Further, the discharge capacity of the cell using this Li—Ni composite oxide particle powder was 177 mAh / g, and the gas generation amount after storage at 85 ° C. for 24 hours was 0.44 ml / g.

[Comparative Examples 10-14]
Ni—Co—Mn hydroxide obtained in the same manner as in Example 9, bismuth oxide having an average primary particle size of 0.5 μm and an average secondary particle size of 2 μm, an average primary particle size of 0.6 μm and an average of 2 Li / (Ni + Co + Mn) at a molar ratio of antimony oxide having a secondary particle size of 2.3 μm, zirconium oxide having an average primary particle size of 0.5 μm and an average secondary particle size of 2 μm, and lithium carbonate so as to have a predetermined composition ratio. -Zr-Bi-Sb) = 1.05 Except for mixing, Li-Ni-Co-Mn-Zr-Sb composite oxide particles having different chemical compositions were performed in the same manner as in Example 9. Obtained. Table 3 shows the composition and production conditions of these materials, and Table 4 shows the average primary particle diameter, lithium hydroxide amount, lithium carbonate amount, initial discharge capacity, and gas generation amount.

[Comparative Examples 15 to 21]
Using a mixed aqueous solution of 2 mol / l nickel sulfate, cobalt sulfate, and manganese sulfate such that Ni: Co: Mn = 50: 20: 30, the Ni—Co—Mn hydroxide particles were obtained, and the air atmosphere Then, after calcination for 5 hours at 950 ° C. and pulverization, 1 kg of this Li—Ni composite oxide particle powder is suspended and stirred in a 1/50 N sulfuric acid solution for 10 minutes, further washed with 10 times water and dried. The Li—Ni—Co—Mn—Zr—Sb composite oxide particles having different chemical compositions were obtained in the same manner as in Comparative Examples 8 to 14 except that calcination was performed again at 800 ° C. for 2 hours in an air atmosphere. A powder was obtained. Table 3 shows the composition and production conditions of these materials, and Table 4 shows the average primary particle diameter, lithium hydroxide amount, lithium carbonate amount, initial discharge capacity, and gas generation amount.

The Li—Ni composite oxide particle powders obtained in Examples 1 to 24 have a primary particle constituting the secondary particles having an average primary particle diameter of 1 μm or more, and a new particle interface due to particle breakage due to compression during electrode production. Is an excellent positive electrode material in which the generation of gas is suppressed, the reactivity with the electrolyte in a high temperature environment is suppressed, and the gas generation is improved.
In addition, the Li—Ni composite oxide particle powder according to the present invention has a lithium hydroxide content of 0.25% or less when 20 g of the powder is suspended and stirred in 100 ml of water for 10 minutes. The amount is 0.15% or less, and is an excellent positive electrode material in which the decomposition reaction of the electrolytic solution by the alkali component in a high temperature environment is suppressed and gas generation is improved.
Furthermore, in a non-aqueous electrolyte secondary battery using Li—Ni composite oxide particle powder as a positive electrode active material, the amount of gas generated after storage at 85 ° C. for 24 hours is 0.4 ml / g or less, under a high temperature environment. It can be said that this is an excellent positive electrode material in which the reactivity with the electrolyte is suppressed and gas generation is improved.

  Next, FIG. 3 shows a powder X-ray diffraction pattern of the Li—Ni composite oxide particles obtained in Examples 1, 9, and 17.

  As can be seen from the figure, no peak due to by-products is observed in any of the examples, and it has a layered structure in which the solid solution is uniformly formed.

  From the above results, the Li-Ni composite oxide particle powder according to the present invention is effective as a positive electrode active material for a non-aqueous electrolyte secondary battery having a large charge / discharge capacity and a small amount of gas generation and excellent high-temperature charge / discharge characteristics. It was confirmed.

  One kind containing at least a bismuth compound selected from an Ni-Co hydroxide or Ni-Co-Mn hydroxide according to the present invention and an aluminum compound, zirconium compound, bismuth compound, and antimony compound having an average primary particle size of 1 μm or less By using a Li-Ni composite oxide particle powder obtained by mixing the above mixture with a lithium compound and calcining the obtained mixture, the charge / discharge capacity is large and the amount of gas generated is small and the high temperature charge / discharge characteristics are excellent. A water electrolyte secondary battery can be obtained.

Claims (6)

Composition _{Li x Ni 1-y-z} Co y M z Zr a Bi b Sb c O 2 (0.9 ≦ x ≦ 1.3,0.1 ≦ y ≦ 0.35,0 <z ≦ 0.35 , 0 ≦ a ≦ 0.025, 0.0002 ≦ b ≦ 0.004, 0 ≦ c ≦ 0.002, and c ≠ 0, 1.2 ≦ b / c, M is selected from Al and Mn A non-aqueous electrolyte secondary battery characterized in that, in the Li—Ni composite oxide which is at least one selected element), the primary particles constituting the secondary particles have an average primary particle diameter of 1 to 4 μm. Li-Ni composite oxide particle powder for use. The amount of lithium hydroxide eluted is determined by titrating with 0.2 N hydrochloric acid after filtering the supernatant after stirring 20 g of the Li-Ni composite oxide particle powder in 100 ml of water for 20 minutes. The Li-Ni composite oxide particle powder for a non-aqueous electrolyte secondary battery according to claim 1, wherein the powder is 0.25% or less and the amount of lithium carbonate is 0.15% or less. In the non-aqueous electrolyte secondary battery using the above Li-Ni composite oxide particle powder as a positive electrode active material and using a negative electrode made of a material capable of occluding and releasing lithium metal or lithium ions, it is 85 ° C in a 4.2 V charged state 3. The Li—Ni composite oxide particle powder for a non-aqueous electrolyte secondary battery according to claim 1, wherein a gas generation amount when stored for 24 hours is 0.4 ml / g or less. It is obtained by mixing a lithium compound with at least one bismuth compound selected from Ni-Co hydroxide, an aluminum compound having an average primary particle size of 1 μm or less, a zirconium compound, a bismuth compound, and an antimony compound, and a lithium compound. The lithium-hydride for non-aqueous electrolyte secondary battery according to any one of claims 1 to 3, wherein the mixture is baked, and then lithium hydroxide and lithium carbonate are removed in an acidic aqueous solution and baked again. Manufacturing method of Ni composite oxide particle powder. Mixing a lithium compound with at least one bismuth compound selected from Ni-Co-Mn hydroxide, an aluminum compound having an average primary particle size of 1 μm or less, a zirconium compound, a bismuth compound, and an antimony compound, The obtained mixture is fired, then lithium hydroxide and lithium carbonate are removed in an acidic aqueous solution, and fired again. The non-aqueous electrolyte secondary battery according to any one of claims 1 to 3, The manufacturing method of Li-Ni complex oxide particle powder. A nonaqueous electrolyte secondary battery comprising a positive electrode containing a positive electrode active material comprising the Li-Ni composite oxide particle powder for a nonaqueous electrolyte secondary battery according to any one of claims 1 to 3.