JP5428251B2 - Lithium transition metal compound powder, positive electrode for lithium secondary battery and lithium secondary battery using the same - Google Patents

Description

  The present invention relates to a lithium transition metal-based compound powder used as a positive electrode material for a lithium secondary battery, a method for producing the same, a spray-dried product obtained in the spraying process, and a lithium secondary metal using the lithium transition metal-based compound powder. The present invention relates to a positive electrode for a secondary battery and a lithium secondary battery including the positive electrode for a lithium secondary battery.

  Lithium secondary batteries are excellent in energy density and output density, and are effective in reducing the size and weight. Therefore, the demand for power supplies for portable devices such as notebook computers, mobile phones, and handy video cameras is growing rapidly. ing. Lithium secondary batteries are also attracting attention as power sources for electric vehicles and power load leveling, and in recent years, demand for power sources for hybrid electric vehicles is rapidly expanding. In particular, in electric vehicle applications, it is necessary to be excellent in low cost, safety, life (particularly under high temperature) and load characteristics, and improvements in materials are desired.

Among the materials constituting the lithium secondary battery, as the positive electrode active material, a substance having a function capable of desorbing and inserting lithium ions can be used. There are various types of these positive electrode active material materials, each having its own characteristics. In addition, a common problem for improving performance is to improve load characteristics, and improvements in materials are strongly desired.
Furthermore, there is a demand for a material with a good performance balance that is excellent in low cost, safety, and life (particularly under high temperatures).

  Currently, lithium manganese composite oxides having a spinel structure, layered lithium nickel composite oxides, layered lithium cobalt composite oxides, and the like have been put into practical use as positive electrode active material materials for lithium secondary batteries. All of the lithium secondary batteries using these lithium-containing composite oxides have advantages and disadvantages in terms of characteristics. That is, a lithium manganese composite oxide having a spinel structure is inexpensive and relatively easy to synthesize, and is excellent in safety when used as a battery, but has a low capacity and inferior high-temperature characteristics (cycle and storage). Layered lithium-nickel composite oxides have high capacity and excellent high-temperature characteristics, but are difficult to synthesize, have inferior safety when used as batteries, and have drawbacks such as requiring careful storage. Layered lithium cobalt-based composite oxides are widely used as power sources for portable devices because they are easy to synthesize and have an excellent balance of battery performance. However, they are not sufficient in safety and costly. It is a drawback.

  Under such circumstances, lithium nickel manganese cobalt-based composite oxides with a layered structure have been proposed as promising candidates for active material materials that can overcome or reduce the shortcomings of these positive electrode active material materials and are excellent in battery performance balance. Has been. Particularly, in recent years, demands for lowering costs, higher voltages, and increasing safety demands are promising as positive electrode active material materials that can meet any of the demands.

  However, the degree of cost reduction, higher voltage, and safety will vary depending on the composition ratio. Therefore, for further cost reduction, use with a higher upper limit voltage, and higher safety requirements. Therefore, it is necessary to select and use one having a limited composition range such as a manganese / nickel atomic ratio of approximately 1 or more, or a reduction in the cobalt ratio. However, a lithium secondary battery using a lithium nickel manganese cobalt based composite oxide having such a composition range as a positive electrode material has reduced load characteristics such as rate and output characteristics. It was necessary.

  Conventionally, the lithium nickel manganese cobalt-based composite oxide having a composition range in which the manganese / nickel atomic ratio and the cobalt ratio correspond to the values defined in the present invention are disclosed in Patent Documents 1 to 32 and Non-Patent Documents 1 to 73. ing.

  However, in Patent Documents 1 to 32 and Non-Patent Documents 1 to 73, there is no description focusing on additives that suppress the growth and sintering of active material particles during firing in the composition region defined by the present invention. The necessary conditions for improving the battery performance in the present invention are not satisfied, and it is extremely difficult to improve the battery performance indicated by the present invention only with these techniques.

  In addition, although there is no document describing “suppressing the growth and sintering of active material particles during firing” as indicated by the present invention, lithium nickel manganese cobalt based composite oxidation is aimed at improving the positive electrode active material. The following Patent Literatures 33 to 44 and Non-Patent Literature 74 are disclosed as known literatures in which compounds containing W, Mo, Nb, Ta, Re, or the like are added or replaced.

Patent Document 33 and Patent Document 34 disclose that lithium, nickel-based composite oxide having a layered structure uses W, Mo, Ta, and Nb as substitution elements for transition metal sites. Although it is described that the thermal stability in the state is improved, regarding the particle properties, only the values of the secondary particle size and specific surface area are described in the system using Nb, and there is no description regarding the primary particles.
By the way, in the raw material particle size adjustment stage, there is a description that the raw material is wet-ground by a wet bead mill until the particle size becomes 1 μm or less. However, at this pulverization level, fine primary particles cannot be obtained when fired. In addition, since the composition is mainly composed of Li and Ni, there is still a problem that an active material excellent in various property balances cannot be obtained.

  Patent Document 35 discloses the use of lithium nickel manganese cobalt niobium-based composite oxide. However, regarding the particle properties, there is no description about the size of the primary particles and the secondary particles except for the substantially spherical form, and in addition to not considering the control of the particle size, the Mn molar ratio in the transition metal is There was a problem that an active material having an extremely low property balance of 0.1 or less and still having an excellent property balance could not be obtained.

Patent Document 36 discloses that lithium nickel manganese cobalt based composite oxide containing W and Mo is used, and thereby, thermal stability in a charged state at a lower cost and higher capacity than LiCoO ₂ is disclosed. Is described as being excellent. However, according to the examples described herein, the Ni—Mn—Co composite oxide having an average particle diameter of about 10 μm, lithium hydroxide ground to 20 μm or less, and 1 to 20 μm tungsten trioxide or molybdenum trioxide. The raw material mixture of these particle sizes does not correspond to a fine and uniform mixture, and when this is fired, fine primary particles as in the present invention agglomerate. It was impossible to obtain a fired powder in the form of spherical secondary particles, and there was still a problem that an active material excellent in various property balances could not be obtained.

  Patent Document 37 discloses that in a lithium nickel manganese cobalt-based oxide having a layered structure, Ta, Nb is used as a substitution element for a transition metal site, and thus a usable voltage range is wide. It describes that the charge / discharge cycle durability is good and the capacity is high and the safety is high. However, the production method described here is a method in which nickel manganese cobalt coprecipitated powder, a lithium compound, and a compound of Ta or Nb are simply mixed and fired, and is not a production method that takes into account the control of the particle form, There is a problem that it is impossible to obtain a spherical secondary particle form in which fine primary particles are aggregated as in the present invention, and it is still impossible to obtain an active material excellent in various property balances.

  Patent Document 38 discloses an example in which W is substituted at a transition metal site in a lithium nickel manganese cobalt based composite oxide. However, the production method described here is not a production method that takes into account control of the particle form, in which raw material powders are simply mixed and fired, but a spherical secondary in which fine primary particles are aggregated as in the present invention. There is a problem that it is impossible to obtain a particle form, and it is still impossible to obtain an active material excellent in various property balances.

Patent Document 39 discloses that a monoclinic lithium manganese nickel-based composite oxide in which transition metal sites are substituted with Nb, Mo, W is used as a positive electrode active material. It is described that a lithium secondary battery with high energy density, high voltage, and high reliability can be provided. However, the production method described here is a production method in which the raw material compound is pulverized and mixed by a ball mill or the like and then fired, and the fine primary particles as in the present invention are aggregated. There is a problem that it is impossible to obtain a spherical secondary particle form, and it is still impossible to obtain an active material excellent in various property balances.

  Patent Document 40 discloses that a lithium-transition metal oxide particle having a layered structure has a compound having molybdenum and tungsten on at least the surface thereof, thereby providing excellent battery characteristics even in a more severe use environment. It is described that it has. However, according to the example described here, the positive electrode active material is a manufacturing method in which a precipitate containing Co, Ni, and Mn is subjected to heat treatment, and then mixed and fired with a lithium compound and a molybdenum compound. The effect of suppressing grain growth and sintering during firing is difficult to be exhibited, and fine primary particle morphology as in the present invention cannot be obtained, so that there is still a problem that excellent output characteristics cannot be obtained. .

  Patent Document 41 discloses a lithium nickel manganese cobalt molybdenum composite oxide having a layered structure. However, according to the examples described herein, after mixing lithium compounds and molybdenum compounds with Mn, Ni, Co coprecipitated hydroxides, that is, while mixing the powder particles while grinding, Since it is a manufacturing method to be fired, it is impossible to obtain a spherical secondary particle form in which fine primary particles are aggregated as in the present invention, and it is still impossible to obtain an active material excellent in various battery property balances was there.

  Patent Document 42 discloses an active material for a lithium secondary battery, which preferably has a surface layer containing Li and at least one element selected from the group consisting of Mo and W on the surface of lithium nickel cobalt manganese based composite oxide particles. Thus, it is described that the thermal stability is better than that of conventionally proposed positive electrode active materials without greatly degrading the high initial discharge capacity. However, since the manufacturing method described here is a manufacturing method in which Mo and W Li composite oxides are mixed with the positive electrode active material powder later and fired again, in the first place, when the positive electrode active material is fired In addition to not exhibiting the effect of suppressing grain growth and sintering, the surface of the positive electrode active material is simply covered with the Li composite oxide of Mo or W, which increases the resistance of the active material surface. There is still a problem that excellent output characteristics cannot be obtained.

  Patent Document 43 includes lithium composite oxide particles as positive electrode active material particles, at least part of secondary particles have cracks, and W, Nb, Ta, and Mo are formed on at least a surface layer portion of the active material particles. It is disclosed that these elements are distributed more in the surface layer than in the active material particles. Here, with respect to the particle properties, a part of the secondary particles have cracks, the median diameter is 1 to 30 μm, and the average primary particle diameter is generally 0.1 to 3.0 μm. However, each is only a description of a general range, and there is no description that defines the ratio between the primary particle size and the secondary particle size. Furthermore, according to the example described here, the lithium composite oxide particle is a manufacturing method in which an additional element is included in the surface layer portion by post-treatment (solution method, 400 ° C. annealing). In addition to not exhibiting the effect of suppressing grain growth and sintering during firing, the additive element-containing compound is simply coated on the surface of the positive electrode active material, the resistance of the active material surface becomes high, and still remains There was a problem that excellent output characteristics could not be obtained.

  Patent Document 44 describes that lithium nickel manganese cobalt composite oxide contains Mo or W. However, since the primary particle diameter is too large, 1 μm or more, there is still a problem that excellent output characteristics cannot be obtained. It was.

Non-Patent Document 74 discloses a LiNi _1/3 Mn _1/3 Mo _1/3 O ₂ composite oxide having a layered structure. However, since the Mo content is too high, there is still a problem that an active material excellent in various battery characteristic balances cannot be obtained.
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That is, an object of the present invention is to provide a lithium transition metal-based compound powder for a lithium secondary battery positive electrode material capable of achieving both improvement in load characteristics and higher density in use as a lithium secondary battery positive electrode material, and a method for producing the same And a spray-dried product obtained in the spray-drying step, a positive electrode for a lithium secondary battery using the lithium transition metal-based compound powder, and a lithium secondary battery provided with the positive electrode for the lithium secondary battery is there.

  In order to solve the problem of improving load characteristics such as rate and output characteristics, the inventors of the present invention have suppressed the grain growth and sintering while maintaining sufficiently high crystallinity at the stage of firing the active material. As a result of earnest examination, considering that it is important to obtain particles, especially in layered lithium nickel manganese cobalt based composite oxide, after adding a compound containing elements such as Mo and W, by firing at a temperature of a certain level or more, In addition to forming fine particles with high crystal growth and suppressed primary particle growth and sintering between particles, lithium transition metal compound powder consisting of a surface layer enriched with additive elements is obtained. As a result, the lithium secondary battery positive electrode material has both low cost, high voltage resistance, high safety, and improved load characteristics such as rate and output characteristics. It was capable.

However, in the case of the conventional manufacturing method, since the lithium raw material, the transition metal element and the additive element were simultaneously pulverized into a slurry, and this was subjected to spray drying and firing, secondary particles of the obtained active material powder were There was a problem that it was easy to collapse and only those having a low bulk density and electrode density could be obtained.
In order to solve these problems of powder physical properties, it is important to form secondary particles that have strong cohesion between primary particles and are difficult to break down from the time of the spray-dried product. By spray-drying the non-coexisting slurry, a target spray-dried secondary particle spray-dried body is obtained. By mixing and firing this spray-dried body and a lithium raw material, fine primary particles are not easily collapsed. Succeeded in forming secondary particles. As a result, it is possible to achieve both high bulk density and high electrode density in addition to low cost, high voltage resistance, high safety, improved load characteristics such as rate and output characteristics as a positive electrode material for lithium secondary batteries. It was a thing.

That is, the lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention is a crystal belonging to a layered structure mainly composed of a lithium transition metal compound having a function capable of inserting and removing lithium ions. A lithium transition metal compound powder comprising a structure, comprising a main component raw material of a lithium transition metal compound and a metal element having a valence of 5 or 6 (hereinafter “ The fine particles are calcined, and the primary particles are aggregated to form secondary particles. The median diameter A of the secondary particles and the average diameter (average) The ratio A / B with the primary particle diameter B) is in the range of 8 to 100, and in the powder X-ray diffraction measurement using CuKα rays, the diffraction angle 2θ is in the vicinity of 64.5 ° (110) diffraction peak FWHM (1 When set to 0), preferably represented by 0.01 ≦ FWHM (110) ≦ 0.5 (claim 1).

  The lithium transition metal compound powder for a lithium secondary battery positive electrode material preferably has an average primary particle size B of 0.05 μm or more and 0.9 μm or less (Claim 2).

In this lithium transition metal compound powder for a lithium secondary battery positive electrode material, primary particle crystals are preferably aggregated to form spherical secondary particles .

Also, a lithium secondary battery positive electrode material for a lithium transition metal based compound powder according to the present invention, the lithium transition metal-based compound as a main component a lithium transition metal based compound having insertion and elimination of possible features of lithium ions A fine and uniform mixture of the main component raw material and a compound composed of a metal element having a valence of 5 or 6 (hereinafter referred to as “additive”) is fired. The primary particle crystals having an average diameter (average primary particle diameter B) of 0.05 μm or more and 0.9 μm or less aggregate to form spherical secondary particles, and the median diameter A of the secondary particles and the average The ratio A / B with the primary particle diameter B is preferably in the range of 8 to 100 (claim 4 ).

に帰属する構造を含んで構成され、その格子定数が２．８７０Å≦ａ≦２．８９０Å、１４．２５０≦ｃ≦１４．３１０Åの範囲にあることが好ましい（請求項５）。 The lithium transition metal-based compound powder for a lithium secondary battery positive electrode material of the present invention has a crystal structure in a space group in powder X-ray diffraction measurement using CuKα rays.

The lattice constant is preferably in the range of 2.870 Å ≦ a ≦ 2.890 Å and 14.250 ≦ c ≦ 14.310 （(claim 5 ).

The lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention has a (110) diffraction peak having a diffraction angle 2θ of around 64.5 ° in powder X-ray diffraction measurement using CuKα rays. When the FWHM (110) is FWHM (110), 0.01 ≦ FWHM (110) ≦ 0.5 is preferable (Claim 6 ).

In addition, the lithium transition metal-based compound powder for a lithium secondary battery positive electrode material of the present invention has a diffraction angle 2θ of around 64 ° in a powder X-ray diffraction measurement using CuKα rays (018) diffraction peak, 64 The (110) diffraction peak present at around 5 ° and the (113) diffraction peak present at around 68 ° do not have a diffraction peak derived from a different phase on the higher angle side of each peak top, or are derived from a different phase. If having a diffraction peak integrated intensity ratio of heterogeneous phase peak to diffraction peak of the original crystalline phase, respectively, it is preferably in the range of less (claim 7).
0 ≦ I ₀₁₈ ^* / I ₀₁₈ ≦ 0.20
0 ≦ I ₁₁₀ ^* / I ₁₁₀ ≦ 0.25
0 ≦ I ₁₁₃ ^* / I ₁₁₃ ≦ 0.50
(Here, I ₀₁₈ , I ₁₁₀ , and I ₁₁₃ represent the integrated intensities of the diffraction peaks, respectively (018), (110), and (113), and I ₀₁₈ ^* , I ₁₁₀ ^* , and I ₁₁₃ ^* are (018 ), (110), (113) represents the integrated intensity of a diffraction peak derived from a different phase appearing at a higher angle than the peak top of the diffraction peak.)

Further, the lithium transition metal-based compound powder for a lithium secondary battery positive electrode material of the present invention is set to a refractive index of 1.24 by a laser diffraction / scattering type particle size distribution measuring device, and a particle diameter reference is a volume reference The median diameter A measured after 5 minutes of ultrasonic dispersion (output 30 W, frequency 22.5 kHz) is preferably 3 μm or more and 20 μm or less (claim 8 ).

The lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention preferably has a bulk density of 1.5 g / cm ³ or more and 2.4 g / cm ³ or less (claim 9 ).

In addition, the lithium transition metal compound powder for the positive electrode material of the lithium secondary battery of the present invention has a mercury intrusion amount of 0.4 cm ³ in a mercury intrusion curve by a mercury intrusion method at a pressure of 3.86 kPa to 413 MPa. / G or more and 1.0 cm ³ / g or less is preferable (claim 10 ).

In addition, the lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention has at least one main peak in which the pore distribution curve by the mercury intrusion method has a peak top at a pore radius of 300 nm or more and 1500 nm or less. And having a sub-peak having a peak top at a pore radius of 80 nm or more and less than 300 nm (claim 11 ).

In addition, the lithium transition metal-based compound powder for a lithium secondary battery positive electrode material of the present invention has a fine peak related to a main peak having a peak top at a pore radius of 300 nm to 1500 nm in a pore distribution curve by a mercury intrusion method. The pore volume is 0.2 cm ³ / g or more and 0.5 cm ³ / g or less, and the pore volume according to the sub-peak in which the peak top is present at a pore radius of 80 nm or more and less than 300 nm is 0.01 cm ³ / g or more. , Preferably 0.2 cm ³ / g or less (claim 12 ).

The lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention preferably has a BET specific surface area of 1 m ² / g or more and 5 m ² / g or less (claim 13 ).

In addition, the lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention has a volume resistivity of 1 × 10 ³ Ω · cm or more and 1 × 10 ⁶ Ω · cm or less when consolidated at a pressure of 40 MPa. (Claim 14 ).

Further, in the lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention, the additive contains an element (hereinafter referred to as “additive element”) and includes a crystal structure belonging to a layered structure. a main component composed of lithium nickel manganese cobalt-based composite oxide, and the additional element preferably has a continuous composition gradient structure present with a concentration gradient in the depth direction from the particle surface (claim 15) .

In the lithium transition metal-based compound powder for a lithium secondary battery positive electrode material of the present invention, the lithium transition metal-based compound is preferably represented by the following composition formula (I) (claim 16 ).
LiMO ₂ (I)
(However, in the above formula (I), M is an element composed of Li, Ni and Mn, or Li, Ni, Mn and Co, and the Mn / Ni molar ratio is 0.8 or more and 5 or less, (The Co / (Mn + Ni + Co) molar ratio is 0 or more and 0.35 or less, and the Li molar ratio in M is 0.001 or more and 0.2 or less.)

Further, in the lithium transition metal-based compound powder for a lithium secondary battery positive electrode material of the present invention, the mixture is preferably fired at a firing temperature of 900 ° C. or higher in an oxygen-containing gas atmosphere. 17 ).

In addition, the lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention has a C value of 0.005 wt% or more and 0.1 wt% or less when the content carbon concentration is C (wt%). (Claim 18 ).

In the lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention, M in the composition formula (I) is preferably represented by the following formula (II) (claim 19 ).
_{M = Li z / (2 +} z) {(Ni (1 + y) / 2 Mn (1-y) / 2) 1-x Co x} 2 / (2 + z) ... (II)
(However, in the above formula (II),
0 ≦ x ≦ 0.1
−0.1 ≦ y ≦ 0.1,
(1-x) (0.05-0.98y) ≤z≤ (1-x) (0.20-0.88y)
It is. )

The lithium transition metal-based compound powder for a lithium secondary battery positive electrode material of the present invention is an oxide in which the additive contains at least one element selected from Mo, Nb, W, Ta, and Re. (Claim 20 ).

Moreover, in the lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention, the additive contains an element (hereinafter referred to as “additive element”), and the concentration of the additive element is the additive element. 0.01 mol% or more based on the total molar amount of constituent metal elements except Li, is preferably less than 2 mol% (claim 21).

Further, in the lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention, the additive contains an element (hereinafter referred to as “additive element”), Li in the surface portion of the primary particle and the addition The total atomic ratio of the additive elements with respect to the total of the metal elements other than the elements is preferably 5 times or more the total atomic ratio of the particles (claim 22 ).

Further, in the lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention, the additive contains an element (hereinafter referred to as “additive element”), Li on the outermost surface of the primary particle and the additive element The atomic ratio R ₀ of the total of the additive elements with respect to the total of other metal elements, and the atomic ratio R ₁₀ of the total of the additive elements with respect to the total of Li and metal elements other than the additive elements at a depth of 10 nm from the surface of the primary particles The ratio R ₀ / R ₁₀ is preferably 3 or more (claim 23 ).

In the lithium transition metal-based compound powder for a lithium secondary battery positive electrode material of the present invention, the additive contains an element (hereinafter referred to as “additive element”), and the additive element is deep from the particle surface. It is preferable to have a continuous composition gradient structure that exists with a concentration gradient that is nonlinear in the direction (claim 24 ).

In the lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention, the composition of the lithium transition metal compound is preferably represented by the following formula (III) (claim 25 ).
[L] _3a [Q] _3b [O ₂ ] _6c (III)
(However, in the above formula (III), L is an element containing at least Li, and Q is an element containing at least Ni, Mn and Co, or Li, Ni, Mn and Co,
0.4 ≦ Ni / (Mn + Ni + Co) molar ratio <0.7
0.1 <Mn / (Mn + Ni + Co) molar ratio ≦ 0.4
0.1 ≦ Co / (Mn + Ni + Co) molar ratio ≦ 0.3
And the Li molar ratio in Q is 0 or more and 0.05 or less.
The subscript next to [] represents a site in the crystal structure, the 3a site being the Li site, the 3b site being the transition metal site, and the 6c site being the oxygen site. )

In the lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention, Q in the formula (III) is preferably represented by the following formula (IV) (claim 26 ).
_{Q = Li r / (2 +} r) (Ni 1-p-q Mn p Co q) 2 / (2 + r) ... (IV)
(However, in the above formula (IV),
0.1 <p ≦ 0.4
0.15 ≦ q ≦ 0.25
0.001 ≦ r ≦ 0.1
It is. )

The positive electrode for a lithium secondary battery of the present invention preferably has a positive electrode active material layer containing the lithium transition metal-based compound powder of the present invention and a binder on a current collector (Claim 27 ). .

The lithium secondary battery of the present invention is a lithium secondary battery comprising a negative electrode capable of inserting and extracting lithium, a non-aqueous electrolyte containing a lithium salt, and a positive electrode capable of inserting and extracting lithium. it is preferable to use a positive electrode for lithium secondary battery of the present invention as (claim 28).

  When the lithium transition metal-based compound powder for a lithium secondary battery positive electrode material of the present invention is used as a lithium secondary battery positive electrode material, it is possible to achieve both improvement in load characteristics and higher density. For this reason, according to the present invention, a lithium secondary battery having high density and excellent output characteristics is provided.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail. However, the description of the constituent elements described below is an example (representative example) of an embodiment of the present invention, and the present invention is not limited to the gist of the present invention. The content of is not specified.

[Lithium Transition Metal Compound Powder of the Present Invention]
The lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention will be described below.

The lithium transition metal compound powder for lithium secondary battery positive electrode material of the present invention (hereinafter sometimes referred to as “positive electrode active material”) is the following (1) or (2).
(1) A lithium transition metal compound powder comprising a crystal structure belonging to a layered structure mainly composed of a lithium transition metal compound having a function capable of inserting and removing lithium ions, The primary particles are aggregated to form secondary particles, and the ratio A / B between the median diameter A and the average diameter (average primary particle diameter B) of the secondary particles is in the range of 8 to 100, and CuKα rays are In the powder X-ray diffraction measurement used, 0.01 ≦ FWHM (110) ≦ 0. 0 when the half-value width of the (110) diffraction peak having a diffraction angle 2θ of around 64.5 ° is FWHM (110). Lithium transition metal compound powder for a lithium secondary battery positive electrode material characterized by being represented by 5 (2) The main component is a lithium transition metal compound compound having a function capable of inserting and removing lithium ions. Lithium transition metal Compound powder, which is obtained by firing a fine and uniform mixture of the main component raw material and an additive that suppresses grain growth and sintering during firing, and has an average diameter (average primary particle diameter B ) Aggregates primary particle crystals of 0.05 μm or more and 0.9 μm or less to form spherical secondary particles, and the ratio A / B of the median diameter A to the average primary particle diameter B of the secondary particles is 8 to 100 Lithium transition metal-based compound powder for a lithium secondary battery positive electrode material

<Lithium transition metal compound>
In the present invention, the “lithium transition metal compound” is a compound having a structure capable of desorbing and inserting Li ions, such as sulfides, phosphate compounds, lithium transition metal composite oxides, etc. Is mentioned. Examples of sulfides include compounds having a two-dimensional layered structure such as TiS ₂ and MoS ₂ , and strong compounds represented by the general formula Me _x Mo ₆ S ₈ (Me is various transition metals including Pb, Ag, and Cu). Examples thereof include a sugar compound having a three-dimensional skeleton structure. Examples of the phosphate compound include those belonging to the olivine structure, and are generally represented by LiMePO ₄ (Me is at least one or more transition metals), specifically LiFePO ₄ , LiCoPO ₄ , LiNiPO ₄ , Examples include LiMnPO ₄ . Examples of the lithium transition metal composite oxide include spinel structures capable of three-dimensional diffusion and those belonging to a layered structure capable of two-dimensional diffusion of lithium ions. Those having a spinel structure are generally expressed as LiMe ₂ O ₄ (Me is at least one transition metal), specifically, LiMn ₂ O ₄ , LiCoMnO ₄ , LiNi _0.5 Mn _1.5 O. ₄ and CoLiVO ₄ . Those having a layered structure are generally expressed as LiMeO ₂ (Me is at least one or more transition metals), specifically, LiCoO ₂ , LiNiO ₂ , LiNi _1-x Co _x O ₂ , LiNi _{1-x. -y Co x Mn y O 2,} LiNi 0.5 Mn 0.5 O 2, Li 1.2 Cr 0.4 Mn 0.4 O 2, Li 1.2 Cr 0.4 Ti 0.4 O 2, Examples include LiMnO ₂ .

  The lithium transition metal-based compound powder of the present invention preferably includes a crystal structure belonging to an olivine structure, a spinel structure, or a layered structure from the viewpoint of lithium ion diffusion. Among these, those including a crystal structure belonging to a layered structure are particularly preferable.

<Average primary particle size B>
The average primary particle diameter (average primary particle diameter B) of the lithium transition metal-based compound powder of the present invention is usually 0.05 μm or more, preferably 0.1 μm or more, more preferably 0.15 μm or more, as the lower limit. Most preferably, it is 0.2 μm or more, and the upper limit is usually 0.9 μm or less, preferably 0.7 μm or less, more preferably 0.6 μm or less, and most preferably 0.5 μm or less. When the average primary particle diameter B exceeds the above upper limit, voids in the secondary particles are decreased or the specific surface area is decreased, so that there is a high possibility that the battery performance such as the rate characteristic and the output characteristic is deteriorated. there is a possibility. When the average primary particle diameter B is below the lower limit, there is a possibility that problems such as inferior reversibility of charge / discharge due to undeveloped crystals.

  In addition, the average primary particle diameter B in this invention is the average diameter of the primary particle observed with the scanning electron microscope (SEM), and about 10-30 primary particles are used using the SEM image of 30,000 times. It can be determined as an average value of the particle diameter.

<Secondary particle shape>
The lithium transition metal-based compound powder of the present invention is preferably formed by agglomerating primary particle crystals to form spherical secondary particles, and in particular, primary particle crystals are randomly aggregated to form spherical secondary particles. What formed the particle | grains is preferable. Whether or not the primary particle crystals are randomly aggregated can be observed in the cross-sectional SEM. Such a form indicates that the secondary particles have substantially no crystal anisotropy. As a result, in the secondary particles, the expansion and contraction of the crystals accompanying the insertion / release of lithium ions is relieved, the battery characteristics are excellent in cycle reversibility, and in combination with the effects of the substance provision of the present invention, it becomes a conventional product. In addition to further higher density, various battery characteristics have improved performance in a well-balanced manner.
In the present invention, “spherical” means secondary particles formed by agglomeration of primary particle crystals as shown in the SEM photograph of the lithium nickel manganese cobalt composite oxide powder obtained in Examples described later. The average value of the ratio [Lb / La] of the small diameter [Lb (μm)] at the midpoint in the direction perpendicular to the maximum diameter direction with respect to the maximum diameter [La (μm)] is 0.8 or more. Sure.

<Ratio A / B of median diameter A of secondary particles and average primary particle diameter B>
The ratio A / B between the median diameter A and the average primary particle diameter B of the secondary particles of the lithium transition metal-based compound powder of the present invention represents the tendency of the secondary particle size and the primary particle size of the positive electrode active material powder, The ratio A / B of 8 to 100 means that the powder characteristics such as bulk density and the battery characteristics such as rate are in good balance. If this ratio A / B is less than the above lower limit, it becomes difficult to form spherical secondary particles, so the powder filling property tends to be lowered, and if it exceeds the upper limit, the filling property of the primary particles forming the secondary particles becomes too high. The battery characteristics tend to deteriorate. For this reason, A / B is 8 or more, preferably 9 or more, more preferably 10 or more, and 100 or less, preferably 80 or less, more preferably 50 or less.

<Median diameter A and 90% integrated diameter ( _D90 )>
The median diameter (median diameter A of the secondary particles) of the lithium transition metal compound powder of the present invention is usually 3 μm or more, preferably 3.5 μm or more, more preferably 4 μm or more, still more preferably 4.5 μm or more, and most preferably Is 5 μm or more, usually 20 μm or less, preferably 15 μm or less, more preferably 12 μm or less, still more preferably 10 μm or less, and most preferably 8 μm or less. When the median diameter A is less than this lower limit, there is a possibility that a problem occurs in the coating property at the time of forming the positive electrode active material layer, and when it exceeds the upper limit, there is a possibility that the battery performance is lowered.

The 90% cumulative diameter (D ₉₀ ) of the secondary particles of the lithium transition metal-based compound powder of the present invention is usually 25 μm or less, preferably 18 μm or less, more preferably 15 μm or less, still more preferably 13 μm or less, most preferably. It is 10 μm or less, usually 4 μm or more, preferably 5 μm or more, more preferably 6 μm or more, and most preferably 7 μm or more. If the 90% cumulative diameter (D ₉₀ ) exceeds the above upper limit, the battery performance may be deteriorated, and if it is less than the lower limit, there is a possibility of causing a problem in the coating property when forming the positive electrode active material layer.

In the present invention, the median diameter A and the 90% cumulative diameter (D ₉₀ ) as the average particle diameter are set to a refractive index of 1.24 using a known laser diffraction / scattering particle size distribution measuring device, and the particle diameter reference Is measured on a volume basis. In the present invention, a 0.1 wt% sodium hexametaphosphate aqueous solution was used as a dispersion medium used in the measurement, and measurement was performed after 5 minutes of ultrasonic dispersion (output 30 W, frequency 22.5 kHz).

<Bulk density>
The bulk density of the lithium transition metal based compound powder of the present invention is usually 1.5 g / cm ³ or more, preferably 1.6 g / cm ³ or more, most preferably 1.7 g / cm ³ or more, and usually 2.4 g / cm ^3. cm ³ or less, preferably 2.2 g / cm ³ or less, more preferably 2.0 g / cm ³ or less, and most preferably 1.9 g / cm ³ or less. It is preferable for the bulk density to exceed this upper limit to improve the powder filling property and the electrode density, but the specific surface area is low and the voids in the particles may become too small, which may reduce the battery performance. If the bulk density is below this lower limit, the powder filling property and electrode preparation may be adversely affected.
In the present invention, the bulk density is 2 to 10 g of lithium transition metal compound powder in a 10 ml glass graduated cylinder and tapped 200 times with a stroke of about 20 mm (tap density) g / Obtained as cm ³ .

<Additives that suppress grain growth and sintering during firing>
In the present invention, “additive that suppresses grain growth and sintering during firing” refers to suppressing the growth of active material particles during high-temperature firing, suppressing sintering between primary particles or secondary particles, etc. And what has the effect of obtaining the secondary particle property which the highly crystalline and fine primary particle aggregated.

  For example, when producing a lithium nickel manganese cobalt based composite oxide powder having a composition region defined by the composition formula (I) described later, which is suitable for the present invention, an aggregate of solid powder raw materials is fired at a temperature of 900 ° C. or higher. Thereby, crystallinity develops and the positive electrode active material of a crystal structure favorable for battery performance can be obtained. However, on the other hand, since grain growth and sintering are also likely to proceed, the powder properties are undesirable for battery performance. In other words, it is extremely difficult to improve both of them at the same time, but by adding “additives that suppress grain growth and sintering during firing” and firing, this trade-off relationship can be overcome. It becomes possible to do.

In the present invention, the specific compound added as an additive that suppresses grain growth and sintering during firing is not clear as to the mechanism that exerts the effect of suppressing grain growth and sintering during firing. Since compounds composed of metal elements whose valences can be pentavalent or hexavalent exhibit a common effect, these are different from any of the cationic elements constituting the lithium transition metal-based compound. It is possible to stably take an expensive number state such as a valence, and as a result of being hardly dissolved by a solid-phase reaction, it is unevenly distributed on the surface or grain boundary of the lithium transition metal compound particles. Therefore, it is presumed that the mass transfer due to the contact between the positive electrode active material particles is inhibited, and the growth and sintering of the particles are suppressed.

  The type of additive is not particularly limited as long as it exhibits the above effects, but contains an element selected from elements such as Mo, W, Nb, Ta, and Re, which are stable in an expensive state. Compounds are preferred, and oxide materials are usually used.

Examples of additives that suppress grain growth and sintering during firing include MoO, MoO ₂ , MoO ₃ , MoO _x , Mo ₂ O ₃ , Mo ₂ O ₅ , Li ₂ MoO ₄ , WO, WO ₂ , _{WO 3, WO x, W 2} O 3, W 2 O 5, W 18 O 49, W 20 O 58, W 24 O 70, W 25 O 73, W 40 O 118, Li 2 WO 4, NbO, NbO 2 Nb ₂ O, Nb ₂ O ₅ , Nb ₄ O, Nb ₆ O, LiNbO ₃ , TaO, TaO ₂ , Ta ₂ O ₅ , LiTaO ₃ , ReO ₂ , ReO ₃ , Re ₂ O _{3 and the} like are preferable. the include _{WO 3, Li 2 WO 4,} LiNbO 3, Ta 2 O 5, LiTaO 3, ReO 3, and more preferably include _{WO 3, Li 2 WO 4,} ReO 3, and particularly preferably It can be mentioned _WO 3, _Li 2 _{WO 4.} These additives may be used individually by 1 type, and may use 2 or more types together.

  The range of the concentration of these additive-derived metal elements (hereinafter referred to as “additive elements”) in the lithium transition metal-based compound powder of the present invention is the sum of the additive metal elements and constituent metal elements excluding Li. 0.01 mol% or more, preferably 0.03 mol% or more, more preferably 0.04 mol% or more, particularly preferably 0.05 mol% or more, usually less than 2 mol%, preferably Is 1.8 mol% or less, more preferably 1.5 mol% or less, and particularly preferably 1.3 mol% or less. If the concentration of the additive element is below this lower limit, the above effects may not be obtained, and if it exceeds the upper limit, battery performance may be reduced.

<Other elements other than constituent elements and additive elements>
In the lithium transition metal-based compound powder of the present invention, a different element other than its constituent elements and additive elements (hereinafter sometimes simply referred to as “foreign element”) may be introduced. Different elements include B, Na, Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Co, Cu, Zn, Ga, Ge, Sr, Y, Zr, Ru, and Rh. , Pd, Ag, In, Sn, Sb, Te, Ba, Os, Ir, Pt, Au, Pb, Bi, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm , Yb, Lu, N, F, P, O, S, Cl, Br, and I, and particularly preferably B is selected. These foreign elements may be incorporated into the crystal structure of the lithium transition metal compound, or may not be incorporated into the crystal structure, and may be unevenly distributed as a simple substance or a compound on the particle surface or grain boundary. Good.

  When a foreign element is introduced, the content thereof is usually 0.001 mol% or more, preferably 0.01 mol% or more, more preferably 0, relative to the total molar amount of the constituent metal elements excluding the foreign element and Li. 0.1 mol% or more, most preferably 0.2 mol% or more, usually 20 mol% or less, preferably 15 mol% or less, more preferably 10 mol% or less, and most preferably 5 mol% or less.

<Presence form of additive element>
The lithium transition metal-based compound powder of the present invention is present in the surface portion of the primary particle in a concentration of an additive element, that is, preferably at least one element selected from Mo, W, Nb, Ta and Re. It is preferable. Specifically, the molar ratio of the total amount of additive elements to the total of metal elements other than Li and additive elements on the surface portion of the primary particles (that is, metal elements other than Li and the additive elements) is usually that of the entire particle. The atomic ratio is preferably 5 times or more. The lower limit of this ratio is preferably 7 times or more, more preferably 8 times or more, and particularly preferably 9 times or more. The upper limit is not particularly limited, but is preferably 150 times or less, more preferably 100 times or less, particularly preferably 50 times or less, and most preferably 30 times or less. If this ratio is too small, the effect of improving battery performance is small, while if too large, battery performance may be deteriorated.

  Analysis of the composition of the surface part of the primary particles of the lithium transition metal compound powder was performed by X-ray photoelectron spectroscopy (XPS), using monochromatic light AlKα as an X-ray source, an analysis area of 0.8 mm diameter, and an extraction angle of 65 °. Perform under the conditions of The range (depth) that can be analyzed varies depending on the composition of the primary particles, but is usually 10 nm or less. Therefore, in the present invention, the surface portion of the primary particles of the lithium transition metal-based compound powder indicates a measurable range under these conditions.

  Furthermore, the lithium transition metal-based compound powder of the present invention preferably has a continuous composition gradient structure in which the additive element exists with a concentration gradient in the depth direction from the particle surface.

The composition of the lithium transition metal compound powder in the depth direction from the particle surface is determined by the Ar ion gun sputtering and the XPS measurement employed in the analysis of the composition of the surface part of the primary particle of the lithium transition metal compound powder. It is possible to analyze by performing alternately. Since atoms near the surface are removed by sputtering, the subsequent XPS measurement reflects the composition inside the particles before sputtering. Here, since it is difficult to accurately know the thickness of the surface layer removed by sputtering, the thickness of the SiO ₂ surface layer removed by performing sputtering of the SiO ₂ thin film under the same conditions is substituted. Therefore, in the present invention, the depth from the particle surface of the lithium transition metal-based compound powder indicates a depth estimated by this method.

Atomic ratio R of the total of the additive elements to the total of Li and metal elements other than the additive elements (that is, metal elements other than Li and additive elements) on the outermost surface of the primary particles of the lithium transition metal compound powder of the present invention ₀ and the proportion R ₀ of the total atomic ratio R ₁₀ of said additive element to the total of metal elements other than Li and the additive element in the depth 10nm from the particle surface (i.e., Li and the additive element, a metal element other than) / range of _{R 10} is usually 3 or more, preferably 3.2 or more, more preferably 3.5 or more, and most preferably 3.7 or more, usually 20 or less, preferably 10 or less, more preferably 8 or less Most preferably, it is 5 or less.

<Pore characteristics by mercury intrusion method>
The lithium transition metal-based compound powder for a lithium secondary battery positive electrode material of the present invention preferably satisfies a specific condition in measurement by a mercury intrusion method.

The mercury intrusion method employed in the evaluation of the lithium transition metal compound powder of the present invention will be described below.
The mercury intrusion method is a method for obtaining information such as specific surface area and pore size distribution from the relationship between pressure and the amount of mercury intruded into a pore of a sample such as porous particles while applying pressure. It is.

  Specifically, first, the container containing the sample is evacuated and filled with mercury. Mercury has a high surface tension, and as it is, mercury does not penetrate into the pores on the sample surface, but when pressure is applied to the mercury and the pressure is gradually increased, the pores increase in size from the smallest to the smallest. Gradually mercury enters the pores. If a change in the mercury liquid level (that is, the amount of mercury intruded into the pores) is detected while the pressure is continuously increased, a mercury intrusion curve representing the relationship between the pressure applied to the mercury and the amount of mercury intruded can be obtained. .

Here, assuming that the shape of the pore is cylindrical, the radius is r, the surface tension of mercury is δ, and the contact angle is θ, the size in the direction of extruding mercury from the pore is −2πrδ (cos θ). (If θ> 90 °, this value is positive). Moreover, since the magnitude of the force in the direction of pushing mercury into the pores under the pressure P is represented by πr ² P, the following formulas (1) and (2) are derived from the balance of these forces. It will be.

-2πrδ (cosθ) = πr ² P (1)
Pr = -2δ (cos θ) (2)

  In the case of mercury, values of surface tension δ = 480 dyn / cm and contact angle θ = 140 ° are generally used. When these values are used, the radius of the pore into which mercury is injected under the pressure P is expressed by the following formula (3).

  That is, since there is a correlation between the pressure P applied to mercury and the radius r of the pore into which mercury enters, the size of the pore radius of the sample and its volume are calculated based on the obtained mercury intrusion curve. A pore distribution curve representing the relationship can be obtained. For example, when the pressure P is changed from 0.1 MPa to 100 MPa, the pores in the range from about 7500 nm to about 7.5 nm can be measured.

Note that the approximate measurement limit of the pore radius by the mercury intrusion method is that the lower limit is about 2 nm or more and the upper limit is about 200 μm or less, and the pores in a relatively large range compared to the nitrogen adsorption method described later. It can be said that it is suitable for analysis of distribution.
Measurement by the mercury intrusion method can be performed using an apparatus such as a mercury porosimeter. Specific examples of the mercury porosimeter include an autopore manufactured by Micromeritics, a pore master manufactured by Quantachrome, and the like.

The lithium transition metal-based compound powder of the present invention has a mercury intrusion amount of 0.4 cm ³ / g or more and 1.0 cm ³ /1.0 when the pressure is increased from 3.86 kPa to 413 MPa in the mercury intrusion curve by the mercury intrusion method. g or less is preferable. Mercury intrusion volume is more preferably 0.45 cm ³ / g or more, more preferably 0.5 cm ³ / g or more, and most preferably 0.55 cm ³ / g or more, more preferably 0.9 cm ³ / g or less, More preferably, it is 0.8 cm < ³ > / g or less, Most preferably, it is 0.7 cm < ³ > / g or less. When the upper limit of this range is exceeded, the voids become excessive, and when the lithium transition metal-based compound powder of the present invention is used as a positive electrode material, the filling rate of the positive electrode active material into the positive electrode plate (positive electrode current collector) is lowered. As a result, the battery capacity is limited. On the other hand, if the lower limit of this range is not reached, voids between the particles become excessively small. Therefore, when a battery is produced using the lithium transition metal compound powder of the present invention as a positive electrode material, lithium diffusion between particles is inhibited. As a result, the load characteristics deteriorate.

The lithium transition metal-based compound powder of the present invention usually exhibits specific main peaks and sub-peaks described below when the pore distribution curve is measured by the mercury intrusion method described above.
In the present specification, the “pore distribution curve” refers to the total pore volume per unit weight (usually 1 g) of pores having a radius equal to or larger than the radius of the pores on the horizontal axis, The value obtained by differentiating the logarithm of the pore radius is plotted on the vertical axis, and is usually expressed as a graph connecting the plotted points. In particular, the pore distribution curve obtained by measuring the lithium transition metal-based compound powder of the present invention by mercury porosimetry is referred to as “the pore distribution curve according to the present invention” as appropriate in the following description.

In this specification, “main peak” refers to the largest peak among the peaks of the pore distribution curve, and “sub peak” refers to peaks other than the main peak of the pore distribution curve.
Further, in this specification, “peak top” refers to a point where the coordinate value of the vertical axis takes the largest value in each peak of the pore distribution curve.

<Main peak>
The main peak of the pore distribution curve according to the present invention has a peak top whose pore radius is usually 300 nm or more, preferably 350 nm or more, most preferably 400 nm or more, and usually 1500 nm or less, preferably 1200 nm or less. Preferably it exists in 1000 nm or less, More preferably, it is 980 nm or less, Most preferably, it exists in the range of 950 nm or less. When the upper limit of this range is exceeded, when a battery is made using the lithium transition metal compound powder of the present invention as a positive electrode material, lithium diffusion in the positive electrode material is hindered or the conductive path is insufficient, resulting in load characteristics. May be reduced. On the other hand, below the lower limit of this range, when a positive electrode is produced using the lithium transition metal compound powder of the present invention, the necessary amount of conductive material and binder increases, and the positive electrode plate (positive electrode current collector) increases. There is a possibility that the filling rate of the positive electrode active material into the body) is restricted, and the battery capacity is restricted. In addition, with the formation of fine particles, the mechanical properties of the coating film at the time of coating become hard or brittle, and there is a possibility that the coating film is likely to be peeled off during the winding process during battery assembly.

Moreover, the pore volume of the main peak having a peak top at a pore radius of 300 nm or more and 1500 nm or less, which the pore distribution curve according to the present invention has, is preferably usually 0.1 cm ³ / g or more, preferably 0.2 cm ³ / g or more, more preferably 0.24 cm ³ / g or more, most preferably 0.28 cm ³ / g or more and usually 0.5 cm ³ / g or less, preferably 0.45 cm ³ / g , more preferably 0.4 cm ³ / g or less, and most preferably not more than 0.35 cm ³ / g. When the upper limit of this range is exceeded, the voids become excessive, and when the lithium transition metal compound powder of the present invention is used as the positive electrode material, the filling rate of the positive electrode active material into the positive electrode plate becomes low, and the battery capacity is limited. There is a possibility of being. On the other hand, if the lower limit of the range is not reached, voids between the particles become too small. Therefore, when a battery is produced using the lithium transition metal compound powder of the present invention as a positive electrode material, lithium diffusion between secondary particles is caused. May be hindered and load characteristics may be reduced.

<Sub-peak>
The pore distribution curve according to the present invention may have a plurality of sub-peaks in addition to the main peak described above, and in particular, there may be sub-peaks in the pore radius range of 80 nm or more and less than 300 nm. preferable.

The pore volume of the sub-peak in which the pore distribution curve according to the present invention has a pore radius of 80 nm or more and a peak top is present at less than 300 nm is preferably 0.01 cm ³ / g or more, preferably 0.02 cm. ³ / g or more, more preferably 0.03 cm ³ / g or more, most preferably 0.04 cm ³ / g or more and usually 0.2 cm ³ / g or less, preferably 0.18 cm ³ / g or less, more preferably Is 0.15 cm ³ / g or less, most preferably 0.13 cm ³ / g or less. When the upper limit of this range is exceeded, the voids become excessive, and when the lithium transition metal compound powder of the present invention is used as the positive electrode material, the filling rate of the positive electrode active material into the positive electrode plate becomes low, and the battery capacity is limited. There is a possibility of being. On the other hand, if the lower limit of the range is not reached, voids between the particles become too small. Therefore, when a battery is produced using the lithium transition metal compound powder of the present invention as a positive electrode material, lithium diffusion between secondary particles is caused. May be hindered and load characteristics may be reduced.

<BET specific surface area>
The BET specific surface area of the lithium-lithium transition metal compound powder of the present invention is usually 1 m ² / g or more, preferably 1.1 m ² / g or more, more preferably 1.2 m ² / g or more, and most preferably 1. 3 m ² / g or more, usually 5 m ² / g or less, preferably 4 m ² / g or less, and most preferably 3.5 m ² / g or less. If the BET specific surface area is smaller than this range, the battery performance is likely to be lowered. If the BET specific surface area is larger, the bulk density is hardly increased, and there is a possibility that a problem is likely to occur in the coating property when the positive electrode active material layer is formed.

  The BET specific surface area can be measured by a known BET type powder specific surface area measuring device. In the present invention, an OMS Riken: AMS8000 type automatic powder specific surface area measuring device was used, nitrogen was used as an adsorption gas, and helium was used as a carrier gas. Specifically, the powder sample was heated and deaerated with a mixed gas at a temperature of 150 ° C., then cooled to liquid nitrogen temperature to adsorb the mixed gas, and then heated to room temperature with water to be adsorbed. Nitrogen gas was desorbed, the amount was detected by a heat conduction detector, and the specific surface area of the sample was calculated therefrom.

<Volume resistivity>
The volume resistivity value when the lithium transition metal-based compound powder of the present invention is compacted at a pressure of 40 MPa is preferably 1 × 10 ³ Ω · cm or more as a lower limit, and more preferably 5 × 10 ³ Ω · cm or more. More preferred is 1 × 10 ⁴ Ω · cm or more. The upper limit is preferably 1 × 10 ⁶ Ω · cm or less, more preferably ⁵ × 10 5 Ω · cm or less, more preferably less than 1 × 10 ⁵ Ω · cm. If this volume resistivity exceeds this upper limit, the load characteristics when used as a battery may be reduced. On the other hand, if the volume resistivity falls below this lower limit, the safety when used as a battery may be reduced.

  In the present invention, the volume resistivity of the lithium transition metal based compound powder is such that the four probe / ring electrode, the electrode spacing is 5.0 mm, the electrode radius is 1.0 mm, the sample radius is 12.5 mm, and the applied voltage limiter is 90 V. The volume resistivity measured in a state where the lithium transition metal-based compound powder is compacted at a pressure of 40 MPa. The volume resistivity can be measured, for example, by using a powder resistance measuring device (for example, Lorester GP powder resistance measuring system manufactured by Dia Instruments Co., Ltd.) with a powder probe unit on a powder under a predetermined pressure. It can be carried out.

（以下「層状Ｒ（−３）ｍ構造」と表記することがある。）に帰属される。 <Crystal structure>
The lithium transition metal-based compound powder of the present invention is preferably composed mainly of a lithium nickel manganese cobalt-based composite oxide including a crystal structure belonging to a layered structure.
Here, the layered structure will be described in more detail. As a typical crystal system having a layered structure, there are those belonging to the α-NaFeO ₂ type such as LiCoO ₂ and LiNiO ₂ , which are hexagonal and have a space group due to their symmetry.

(Hereinafter referred to as “layered R (−3) m structure”).

However, the layered LiMeO ₂ is not limited to the layered R (−3) m structure. In addition, LiMnO ₂ called so-called layered Mn is an orthorhombic layered compound having a space group Pm2m, and Li ₂ MnO ₃ called so-called 213 phase is Li [Li _1/3 Mn _2/3 ]. O ₂ , which is a monoclinic space group C2 / m structure, is also a layered compound in which a Li layer, a [Li _1/3 Mn _2/3 ] layer, and an oxygen layer are stacked.

<Composition>
The lithium transition metal compound powder of the present invention is preferably a lithium transition metal compound powder represented by the following composition formula (I).
LiMO ₂ (I)
However, M is an element composed of Li, Ni and Mn, or Li, Ni, Mn and Co, and the Mn / Ni molar ratio is usually 0.8 or more, preferably 0.82 or more, more preferably Is 0.85 or more, more preferably 0.88 or more, most preferably 0.9 or more, usually 5 or less, preferably 4 or less, more preferably 3 or less, still more preferably 2.5 or less, and most preferably 1. 5 or less. The Co / (Mn + Ni + Co) molar ratio is usually 0 or more, preferably 0.01 or more, more preferably 0.02 or more, still more preferably 0.03 or more, most preferably 0.05 or more, usually 0.35 or less, preferably Is 0.20 or less, more preferably 0.15 or less, still more preferably 0.10 or less, and most preferably 0.099 or less. The molar ratio of Li in M is 0.001 or more, preferably 0.01 or more, more preferably 0.02 or more, further preferably 0.03 or more, most preferably 0.05 or more, usually 0.2 or less, preferably Is 0.19 or less, more preferably 0.18 or less, still more preferably 0.17 or less, and most preferably 0.15 or less.

  In the above composition formula (I), the atomic ratio of the oxygen amount is described as 2 for convenience, but there may be some non-stoichiometry. In the case of non-stoichiometry, the atomic ratio of oxygen is usually in the range of 2 ± 0.2, preferably in the range of 2 ± 0.15, more preferably in the range of 2 ± 0.12, and even more preferably 2 ± 0.10. And particularly preferably in the range of 2 ± 0.05.

  In addition, the lithium transition metal-based compound powder of the present invention is preferably obtained by firing at a high temperature in an oxygen-containing gas atmosphere in order to increase the crystallinity of the positive electrode active material. In particular, in the lithium nickel manganese cobalt-based composite oxide having the composition represented by the above composition formula (I), the lower limit of the firing temperature is usually 900 ° C. or higher, preferably 920 ° C. or higher, more preferably 940 ° C. or higher, still more preferably. Is 950 ° C. or higher, most preferably 960 ° C. or higher, and the upper limit is usually 1200 ° C. or lower, preferably 1175 ° C. or lower, more preferably 1150 ° C. or lower, and most preferably 1125 ° C. or lower. If the firing temperature is too low, heterogeneous phases are mixed, and the lattice distortion increases without developing a crystal structure. Moreover, the specific surface area becomes too large. Conversely, if the firing temperature is too high, the primary particles grow excessively, sintering between the particles proceeds too much, and the specific surface area becomes too small.

<Contained carbon concentration C>
The carbon concentration C (wt%) value of the lithium transition metal compound powder of the present invention is usually 0.005 wt% or more, preferably 0.01 wt% or more, more preferably 0.015 wt% or more, most preferably It is preferably 0.02% by weight or more, usually 0.1% by weight or less, preferably 0.08% by weight or less, more preferably 0.07% by weight or less, and most preferably 0.06% by weight or less. If the lower limit is not reached, battery performance may be reduced. If the upper limit is exceeded, swelling due to gas generation when the battery is produced may increase or battery performance may be reduced.

In the present invention, the carbon concentration C of the lithium transition metal-based compound powder is determined by measurement by an oxygen gas combustion (high-frequency heating furnace type) infrared absorption method, as shown in the Examples section below.
In addition, the carbon component contained in the lithium transition metal compound powder obtained by the carbon analysis described later can be regarded as indicating information on the amount of carbonic acid compound, particularly lithium carbonate. This is due to the fact that the carbon amount determined by carbon analysis is assumed to be all derived from carbonate ions, and the carbonate ion concentration analyzed by ion chromatography generally agrees.

  On the other hand, when a composite treatment with conductive carbon is performed as a method for increasing the electron conductivity, a C amount exceeding the specified range may be detected, but such a treatment was performed. The C value in the case is not limited to the specified range.

<Preferred composition>
The lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention is particularly preferably one in which the atomic configuration at the M site in the composition formula (I) is represented by the following formula (II).
M = Li _{z / (2 + z)} {(Ni _{(1 + y) / 2} Mn _{(1-y) / 2} ) _1-x Co _x } _{2 / (2 + z)} (II)
(However, in the above formula (II),
0 ≦ x ≦ 0.1
−0.1 ≦ y ≦ 0.1,
(1-x) (0.05-0.98y) ≤z≤ (1-x) (0.20-0.88y)
It is. )

  In the above formula (II), the value of x is usually 0 or more, preferably 0.01 or more, more preferably 0.02 or more, still more preferably 0.03 or more, most preferably 0.04 or more, usually 0.1. Hereinafter, it is preferably 0.099 or less, and most preferably 0.098 or less.

  The value of y is usually −0.1 or more, preferably −0.05 or more, more preferably −0.03 or more, most preferably −0.02 or more, usually 0.1 or less, preferably 0.05 or less, More preferably, it is 0.03 or less, and most preferably 0.02 or less.

  The value of z is usually (1-x) (0.05-0.98y) or more, preferably (1-x) (0.06-0.98y) or more, more preferably (1-x) (0. 07-0.98y) or more, more preferably (1-x) (0.08-0.98y) or more, most preferably (1-x) (0.10-0.98y) or more, usually (1- x) (0.20-0.88y) or less, preferably (1-x) (0.18-0.88y) or less, more preferably (1-x) (0.17-0.88y), most Preferably, it is (1-x) (0.16-0.88y) or less. If z is below this lower limit, the conductivity will decrease, and if it exceeds the upper limit, the amount of substitution to transition metal sites will increase so much that the battery capacity will decrease, leading to a decrease in the performance of lithium secondary batteries using this. There is sex. On the other hand, if z is too large, the carbon dioxide absorbability of the active material powder increases, so that it becomes easy to absorb carbon dioxide in the atmosphere. As a result, it is estimated that the concentration of contained carbon increases.

  In the composition range of the above formula (II), the closer the z value is to the lower limit that is a constant ratio, the lower the rate characteristics and output characteristics as a battery, and the lower the z value is to the upper limit, Although the rate characteristics and output characteristics of the battery are improved, there is a tendency for the capacity to decrease. In addition, the lower the y value, that is, the smaller the manganese / nickel atomic ratio, the higher the capacity is obtained at a lower charging voltage. However, the cycle characteristics and safety of batteries set at a higher charging voltage tend to be reduced. As the value is closer to the upper limit, the cycle characteristics and safety of the battery set at a higher charge voltage are improved, while the discharge capacity, rate characteristics, and output characteristics tend to decrease. In addition, the closer the x value is to the lower limit, the lower the load characteristics such as rate characteristics and output characteristics when the battery is used. Conversely, the closer the x value is to the upper limit, the rate characteristics when the battery is used. However, if this upper limit is exceeded, the cycle characteristics and safety when set at a high charge voltage are reduced, and the raw material cost is increased. Setting the composition parameters x, y, and z within a specified range is an important component of the present invention.

Here, the chemical meaning of the Li composition (z and x) in the lithium nickel manganese cobalt composite oxide, which is a preferred composition of the lithium transition metal compound powder of the present invention, will be described in more detail below.
As described above, the layered structure is not necessarily limited to the R (-3) m structure, but is preferably one that can be attributed to the R (-3) m structure from the viewpoint of electrochemical performance.
In order to obtain x, y, and z in the composition formula of the lithium nickel manganese cobalt based composite oxide, each transition metal and Li are analyzed with an inductively coupled plasma emission spectrometer (ICP-AES), and Li / Ni / Calculated by determining the ratio of Mn / Co.

  From a structural point of view, it is considered that Li related to z is substituted for the same transition metal site. Here, due to Li related to z, the average valence of Ni becomes larger than divalent (trivalent Ni is generated) by the principle of charge neutrality. Since z raises the Ni average valence, it becomes an index of the Ni valence (the ratio of Ni (III)).

となる。この計算結果は、Ｎｉ価数はｚのみで決まるのではなく、ｘ及びｙの関数となっていることを意味している。ｚ＝０かつｙ＝０であれば、ｘの値に関係なくＮｉ価数は２価のままである。ｚが負の値になる場合は、活物質中に含まれるＬｉ量が化学量論量より不足していることを意味し、あまり大きな負の値を有するものは本発明の効果が出ない可能性がある。一方、同じｚ値であっても、Ｎｉリッチ（ｙ値が大きい）及び／又はＣｏリッチ（ｘ値が大きい）な組成ほどＮｉ価数は高くなるということを意味し、電池に用いた場合、レート特性や出力特性が高くなるが、反面、容量低下しやすくなる結果となる。このことから、ｚ値の上限と下限はｘ及びｙの関数として規定するのがより好ましいと言える。 From the above composition formula, when calculating the Ni valence (m) accompanying the change of z, the Co valence is trivalent and the Mn valence is tetravalent,

It becomes. This calculation result means that the Ni valence is not determined only by z but is a function of x and y. If z = 0 and y = 0, the Ni valence remains divalent regardless of the value of x. When z is a negative value, it means that the amount of Li contained in the active material is less than the stoichiometric amount, and those having a very large negative value may not have the effect of the present invention. There is sex. On the other hand, even if the z value is the same, it means that the Ni valence becomes higher as the composition is rich in Ni (large y value) and / or rich in Co (large x value). The rate characteristics and output characteristics are improved, but on the other hand, the capacity tends to decrease. From this, it can be said that it is more preferable to define the upper and lower limits of the z value as a function of x and y.

  In addition, when the x value is in the range of 0 ≦ x ≦ 0.1 and the amount of Co is small, in addition to reducing the cost, it was used as a lithium secondary battery designed to be charged at a high charging potential. In some cases, charge / discharge capacity, cycle characteristics, and safety are improved.

<Lattice constant>
In the present invention, the lithium nickel manganese cobalt based composite oxide powder having a composition satisfying the composition formulas (I) and (II) has a crystal structure including a layered R (-3) m structure, and its lattice The constants are preferably in the range of 2.870 Å ≦ a ≦ 2.890 Å and 14.250 ≦ c ≦ 14.310 Å. In the present invention, the crystal structure and lattice constant can be obtained by powder X-ray diffraction measurement using CuKα rays.

  In the present invention, the lattice constant a (Å) is usually 2.870Å ≦ a ≦ 2.890Å, preferably 2.873Å ≦ a ≦ 2.888, more preferably 2.875Å ≦ a ≦ 2.885Å, particularly preferably. Is 2.877Å ≦ a ≦ 2.883Å, and the lattice constant c (Å) is usually 14.250 ≦ c ≦ 14.310Å, preferably 14.260 ≦ c ≦ 14.305Å, more preferably 14.265 ≦. c ≦ 14.300cm, particularly preferably 14.270 ≦ c ≦ 14.295cm.

<Powder X-ray diffraction peak>
In the present invention, the lithium nickel manganese cobalt based composite oxide powder having a composition satisfying the composition formulas (I) and (II) has a diffraction angle 2θ of 64.5 in a powder X-ray diffraction pattern using CuKα rays. When the half-value width of the (110) diffraction peak existing in the vicinity of ° is FWHM (110), it is preferably in the range of 0.01 ≦ FWHM (110) ≦ 0.5.
In general, the half width of an X-ray diffraction peak is used as a measure of crystallinity. From the correlation between crystallinity and battery performance, the half width of a (110) diffraction peak having a diffraction angle 2θ of around 64.5 ° is used. If the value is within the above specified range, good battery performance is exhibited.

  In the present invention, the FWHM (110) is usually 0.01 or more, preferably 0.05 or more, more preferably 0.10 or more, still more preferably 0.12 or more, most preferably 0.14 or more, 0.5 or less. , More preferably 0.45 or less, and most preferably 0.4 or less.

In the present invention, the lithium nickel manganese cobalt composite oxide powder having a composition satisfying the composition formulas (I) and (II) has a diffraction angle 2θ of 64 in powder X-ray diffraction measurement using CuKα rays. In the (018) diffraction peak existing at around 0 °, the (110) diffraction peak around 64.5 °, and the (113) diffraction peak around 68 °, a different phase is present on the higher angle side than the peak top. In the case where the diffraction peak derived from the original phase does not exist or the diffraction peak derived from the different phase is present, the integrated intensity ratio of the different phase peak to the diffraction peak of the original crystal phase is preferably in the following range.
0 ≦ I ₀₁₈ ^* / I ₀₁₈ ≦ 0.20
0 ≦ I ₁₁₀ ^* / I ₁₁₀ ≦ 0.25
0 ≦ I ₁₁₃ ^* / I ₁₁₃ ≦ 0.50
(Here, I ₀₁₈ , I ₁₁₀ , and I ₁₁₃ represent the integrated intensities of the diffraction peaks, respectively (018), (110), and (113), and I ₀₁₈ ^* , I ₁₁₀ ^* , and I ₁₁₃ ^* are (018 ), (110), (113) represents the integrated intensity of a diffraction peak derived from a different phase appearing at a higher angle than the peak top of the diffraction peak.)

By the way, although the details of the causative substance of the diffraction peak derived from this heterogeneous phase are not clear, when a heterogeneous phase is included, the capacity, rate characteristics, cycle characteristics, etc. when it is made into a battery are lowered. For this reason, the diffraction peak may have a diffraction peak that does not adversely affect the battery performance of the present invention, but is preferably a ratio in the above range, and the diffraction peak derived from a different phase with respect to each diffraction peak. The integrated intensity ratio is usually I ₀₁₈ ^* / I ₀₁₈ ≦ 0.20, I ₁₁₀ ^* / I ₁₁₀ ≦ 0.25, I ₁₁₃ ^* / I ₁₁₃ ≦ 0.50, preferably I ₀₁₈ ^* / I ₀₁₈ ≦ 0. 18, I ₁₁₀ ^* / I ₁₁₀ ≦ 0.20, I ₁₁₃ ^* / I ₁₁₃ ≦ 0.45, more preferably I ₀₁₈ ^* / I ₀₁₈ ≦ 0.16, I ₁₁₀ ^* / I ₁₁₀ ≦ 0.15, I ₁₁₃ ^* / _{I 113} ≦ 0.40, more preferably ^{_{I 018 * / I 018 ≦ 0.14}} , I 110 * / I 110 ≦ 0.13, an _{I 113 * / I 113 ≦ 0.38} , It is particularly preferred is also preferably no diffraction peaks derived from heterogeneous phases.

<Composition of lithium transition metal compound>
The lithium transition metal compound according to the present invention preferably has a composition represented by the following formula (III), and Q in the formula (III) is particularly preferably represented by the following formula (IV).

[L] _3a [Q] _3b [O ₂ ] _6c (III)
(However, in the above formula (III), L is an element containing at least Li, and Q is an element containing at least Ni, Mn and Co, or Li, Ni, Mn and Co,
0.4 ≦ Ni / (Mn + Ni + Co) molar ratio <0.7
0.1 <Mn / (Mn + Ni + Co) molar ratio ≦ 0.4
0.1 ≦ Co / (Mn + Ni + Co) molar ratio ≦ 0.3
And the Li molar ratio in Q is 0 or more and 0.05 or less.
The subscript next to [] represents a site in the crystal structure, the 3a site being the Li site, the 3b site being the transition metal site, and the 6c site being the oxygen site. )

_{Q = Li r / (2 +} r) (Ni 1-p-q Mn p Co q) 2 / (2 + r) ... (IV)
(However, in the above formula (IV),
0.1 <p ≦ 0.4
0.15 ≦ q ≦ 0.25
0.001 ≦ r ≦ 0.1
It is. )

  In the formula (III), L is an element containing at least Ni, Mn and Co, or Li. Examples of elements other than Li include metal elements such as Ni, Mn, and Co.

  Q is an element composed of at least Ni, Mn and Co, or Li, Ni, Mn and Co, and the Ni / (Mn + Ni + Co) molar ratio is 0.4 or more, preferably 0.42 or more, more preferably 0.45 or more, most preferably 0.48 or more, usually less than 0.7, preferably 0.68 or less, more preferably 0.65 or less, and most preferably 0.62 or less.

  Mn / (Mn + Ni + Co) molar ratio is greater than 0.1, preferably 0.12 or more, more preferably 0.15 or more, most preferably 0.18 or more, usually 0.4 or less, preferably 0.38 or less, More preferably, it is 0.35 or less, and most preferably 0.32 or less.

  Co / (Mn + Ni + Co) molar ratio is 0.1 or more, preferably 0.12 or more, more preferably 0.15 or more, most preferably 0.18 or more, usually 0.3 or less, preferably 0.30, and more preferably Is 0.28 or less, more preferably 0.25 or less, and most preferably 0.22 or less.

  Li molar ratio in Q is 0 or more, preferably 0.001 or more, more preferably 0.005 or more, further preferably 0.01 or more, most preferably 0.02 or more, usually 0.05 or less, preferably 0. 0.045 or less, more preferably 0.04 or less, further preferably 0.035 or less, and most preferably 0.03 or less.

  If the composition is out of the above range, the intended effect of the present invention may not be easily obtained.

  In the above formula (III), the atomic ratio of the oxygen amount is described as 2 for convenience, but there may be some non-stoichiometry. In the case of non-stoichiometry, the atomic ratio of oxygen is usually in the range of 2 ± 0.2, preferably in the range of 2 ± 0.15, more preferably in the range of 2 ± 0.12, and even more preferably 2 ± 0.10. And particularly preferably in the range of 2 ± 0.05.

  In the above formula (IV), the value of p is usually larger than 0.1, preferably 0.15 or more, more preferably 0.2 or more, still more preferably 0.25 or more, most preferably 0.28 or more. In general, it is 0.4 or less, preferably 0.38 or less, more preferably 0.36 or less, still more preferably 0.34 or less, and most preferably 0.32 or less.

  The value of q is usually 0.15 or more, preferably 0.16 or more, most preferably 0.18 or more, usually 0.25 or less, preferably 0.24 or less, more preferably 0.23 or less, most preferably 0. .22 or less.

  The value of r is usually 0.001 or more, preferably 0.01 or more, more preferably 0.02 or more, further preferably 0.03 or more, most preferably 0.04 or more, usually 0.1 or less, preferably 0. 0.09 or less, more preferably 0.08 or less, and most preferably 0.075 or less. If the lower limit is not reached, the conductivity decreases, and if the upper limit is exceeded, the amount of substitution to the transition metal site becomes too large and the battery capacity becomes low. is there. On the other hand, if r is too large, the carbon dioxide absorbability of the active material powder increases, and it becomes easier to absorb carbon dioxide in the atmosphere. As a result, it is estimated that the concentration of contained carbon increases.

  In the composition range of the above formula (IV), as the r value is closer to the lower limit, which is a constant ratio, the battery tends to have lower rate characteristics and output characteristics. Conversely, as the r value is closer to the upper limit, Although the rate characteristics and output characteristics of the battery are improved, there is a tendency for the capacity to decrease. Moreover, although the capacity | capacitance is expressed as the p value is closer to the lower limit, the chemical stability and safety tend to decrease. Conversely, as the p value is closer to the upper limit, the chemical stability and safety are lower. While improving, the capacity tends to decrease. In addition, the closer the q value is to the lower limit, the lower the rate characteristics and output characteristics tend to be. Conversely, the closer the q value is to the upper limit, the higher the rate characteristics and output characteristics. Cycle characteristics and safety are reduced, and raw material costs are increased. It is an important component of the present invention that the composition parameters p, q, and r are within a specified range.

Here, the chemical meaning of excess Li (r) in the preferred composition of the lithium transition metal-based compound powder of the present invention will be described in more detail below.
As described above, the layered structure is not necessarily limited to the layered R (-3) m structure, but it is preferable from the viewpoint of electrochemical performance that it can belong to the layered R (-3) m structure.
In order to obtain p, q, and r in the composition formula of the lithium transition metal compound, each transition metal and Li are analyzed with an inductively coupled plasma emission spectrometer (ICP-AES), and Li / Ni / Mn / Co It is calculated by calculating the ratio of.

From a structural point of view, it is considered that Li related to r is substituted with the same transition metal site (3b). Here, the Li related to r increases the average valence of Ni on the principle of charge neutrality (trivalent Ni is generated). That is, since r increases the Ni average valence, it is an index of the Ni valence (the ratio of Ni (III)).

  From the above composition formula, when calculating the Ni valence (m) accompanying the change of r, the Co valence is trivalent and the Mn valence is tetravalent,

It becomes. This calculation result means that the Ni valence is not determined only by r but is a function of p and q. When p = r, that is, when the amount of Mn is equal to the amount of excess Li, it is suggested that the Ni valence becomes trivalent regardless of the q value (Co amount). When the r value (excess Li amount) is 0 and p (Mn amount) = 1−pq (Ni amount), the Ni valence is divalent. This means that even when the r value is the same, the Ni valence becomes higher as the composition is richer in Ni (1-pq value is larger) and / or Mn poor (lower p value), and used in the battery. In this case, the rate characteristic and the output characteristic are improved, but on the other hand, the capacity tends to decrease.

  In addition, when the q value is 0.15 ≦ q ≦ 0.25 and the amount of Co is in an appropriate range, the charge / discharge capacity and rate characteristics are improved, and the battery has an excellent battery performance balance. Is preferable.

<Reason why the lithium transition metal-based compound powder of the present invention provides the above effects>
The reason why the lithium transition metal-based compound powder of the present invention brings about the above-described effect is considered as follows.
That is, the lithium transition metal-based compound powder of the present invention has a high bulk density and a moderate void inside the secondary particles because the refined highly crystalline primary particles aggregate to form spherical secondary particles. Therefore, when a battery is produced using this, in addition to being able to increase the contact area between the surface of the positive electrode active material and the electrolyte, the additive element is concentrated on the particle surface, and Because it has a specific continuous composition gradient structure with a concentration gradient in the depth direction, resistance reduction at the active material-electrolyte interface and lithium diffusion inside the particles are improved, electrode density and load characteristics Is estimated to have been improved to a practical level.

[Method for Producing Lithium Transition Metal-Based Compound Powder for Lithium Secondary Battery Positive Electrode Material of the Present Invention]
Below, the manufacturing method of the lithium transition metal type compound powder for lithium secondary battery positive electrode materials of this invention is demonstrated.

  The method for producing the lithium transition metal compound powder of the present invention is not limited to a specific production method, but at least one selected from V, Cr, Mn, Fe, Co, Ni, and Cu. Of the transition metal compound and an additive that suppresses grain growth and sintering during firing are pulverized in a liquid medium to obtain a slurry in which these are uniformly dispersed, and the obtained slurry is sprayed. A spray drying step for drying, a mixed powder preparation step for mixing the obtained spray dried body (hereinafter sometimes referred to as “spray dried body of the present invention”) and a lithium compound, and the obtained mixed powder It is suitably produced by the method for producing a lithium transition metal compound powder for a lithium secondary battery positive electrode material according to the present invention, which comprises a firing step of firing and a step of classifying the obtained fired body.

  For example, a lithium nickel manganese cobalt-based composite oxide powder will be described as an example. A nickel compound, a manganese compound, a cobalt compound, and an additive that suppresses grain growth and sintering during firing are pulverized in a liquid medium. A spray-dried product obtained by spray-drying a slurry in which these are uniformly dispersed is mixed with a lithium compound, and the resulting mixed powder is fired in an oxygen-containing gas atmosphere and then classified and manufactured. be able to.

  Hereinafter, the method for producing a lithium transition metal-based compound powder of the present invention will be described in detail, taking as an example the method for producing a lithium nickel manganese cobalt-based composite oxide powder that is a preferred embodiment of the present invention.

<Slurry preparation process>
Among the raw material compounds used in the preparation of the slurry for producing lithium nickel manganese cobalt based composite oxide powder by the method of the present invention, the nickel compounds include Ni (OH) ₂ , NiO, NiOOH, NiCO ₃ , 2NiCO. _{3 · 3Ni (OH) 2 ·} 4H 2 O, NiC 2 O 4 · 2H 2 O, Ni (NO 3) 2 · 6H 2 O, NiSO 4, NiSO 4 · 6H 2 O, fatty nickel, nickel halide and the like Can be mentioned. Among these, Ni (OH) ₂ , NiO, NiOOH, NiCO ₃ , 2NiCO ₃ .3Ni (OH) ₂ .4H ₂ O, NiC are used in that no harmful substances such as SO _X and NO _X are generated during the firing process. Nickel compounds such as ₂ O ₄ .2H ₂ O are preferred. Further, from the viewpoint that it can be obtained as an industrial raw material at a low cost, and from the viewpoint of high reactivity, Ni (OH) ₂ , NiO, NiOOH, NiCO ₃ , and further generation of decomposition gas during firing, spray-dried powder Ni (OH) ₂ , NiOOH, and NiCO ₃ are particularly preferable from the viewpoint of easily forming voids in the secondary particles. These nickel compounds may be used individually by 1 type, and may use 2 or more types together.

In addition, manganese compounds such as Mn ₂ O ₃ , MnO ₂ , Mn ₃ O ₄ , manganese oxide, MnCO ₃ , Mn (NO ₃ ) ₂ , MnSO ₄ , manganese acetate, manganese dicarboxylate, manganese citrate, fatty acid manganese And manganese salts such as oxyhydroxide, manganese chloride and the like. Among these manganese compounds, MnO ₂ , Mn ₂ O ₃ , Mn ₃ O ₄ , and MnCO ₃ do not generate gases such as SO _X and NO _X during firing, and can be obtained at low cost as industrial raw materials. Therefore, it is preferable. These manganese compounds may be used individually by 1 type, and may use 2 or more types together.

Further, as the cobalt compound, Co (OH) ₂ , CoOOH, CoO, Co ₂ O ₃ , Co ₃ O ₄ , Co (OCOCH ₃ ) ₂ .4H ₂ O, CoCl ₂ , Co (NO ₃ ) ₂ .6H ₂ O, Co (SO ₄ ) ₂ · 7H ₂ O, CoCO _{3 and the} like. Among them, Co (OH) ₂ , CoOOH, CoO, Co ₂ O ₃ , Co ₃ O ₄ , and CoCO ₃ are preferable, and more preferably, from the viewpoint that no harmful substances such as SO _X and NO _X are generated during the firing process. Co (OH) ₂ and CoOOH are industrially inexpensively available and highly reactive. In addition, Co (OH) ₂ , CoOOH, and CoCO ₃ are particularly preferable from the viewpoint of easily forming voids in the secondary particles of the spray-dried powder due to generation of decomposition gas during firing. These cobalt compounds may be used individually by 1 type, and may use 2 or more types together.

  In addition to the Ni, Mn, and Co raw material compounds described above, it is possible to use one or more compounds for the purpose of introducing other elements by performing substitution of other elements.

  As described above, the additive for suppressing grain growth and sintering during firing is not particularly limited as long as it exhibits the desired effect, but Mo and W are stable in an expensive state. A compound containing an element selected from elements such as Nb, Ta, and Re is preferable, and an oxide material is usually used.

Examples of additives that suppress grain growth and sintering during firing include MoO, MoO ₂ , MoO ₃ , MoO _x , Mo ₂ O ₃ , Mo ₂ O ₅ , Li ₂ MoO ₄ , WO, WO ₂ , _{WO 3, WO x, W 2} O 3, W 2 O 5, W 18 O 49, W 20 O 58, W 24 O 70, W 25 O 73, W 40 O 118, Li 2 WO 4, NbO, NbO 2 Nb ₂ O, Nb ₂ O ₅ , Nb ₄ O, Nb ₆ O, LiNbO ₃ , TaO, TaO ₂ , Ta ₂ O ₅ , LiTaO ₃ , ReO ₂ , ReO ₃ , Re ₂ O _{3 and the} like are preferable. Includes MoO ₃ , Li ₂ MoO ₄ , WO ₃ , Li ₂ WO ₄ , LiNbO ₃ , Ta ₂ O ₅ , LiTaO ₃ , ReO ₃ , and particularly preferably WO ₃ , Li ₂ WO ₄ , R eO ₃ may be mentioned. These additives may be used individually by 1 type, and may use 2 or more types together.

  Further, as described above, the range of the amount of these additives added is such that the concentration of the additive element in the obtained lithium nickel manganese cobalt based composite oxide powder is that of the constituent metal element excluding the additive element and Li. 0.01 mol% or more, preferably 0.03 mol% or more, more preferably 0.04 mol% or more, particularly preferably 0.05 mol% or more, usually less than 2 mol%, based on the total mol amount, The amount is preferably 1.8 mol% or less, more preferably 1.5 mol% or less, and particularly preferably 1.3 mol% or less. If the lower limit is not reached, the above effects may not be obtained. If the upper limit is exceeded, battery performance may be reduced.

  Here, a slurry in which a nickel compound, a manganese compound, and a cobalt compound, an additive that suppresses grain growth and sintering during firing, and other foreign elements that are used as necessary are dispersed in a liquid medium. When preparing, the target Ni / Mn / Co / added element / foreign element molar ratio can be controlled by adjusting the mixing ratio of each compound.

The method for mixing the raw materials is not particularly limited, and may be wet or dry. For example, a method using an apparatus such as a ball mill, a vibration mill, or a bead mill can be used. Wet mixing in which the raw material compound is mixed in a liquid medium such as water or alcohol is preferable because more uniform mixing is possible and the reactivity of the mixture can be increased in the firing step.
The mixing time varies depending on the mixing method, but it is sufficient that the raw materials are uniformly mixed at the particle level. For example, a ball mill (wet or dry) usually takes about 1 to 2 days, and a bead mill (wet continuous method) has a residence time. Is usually about 0.1 to 6 hours.

In the raw material mixing stage, it is preferable that the raw material is pulverized in parallel. As the degree of pulverization, the particle diameter of the raw material particles after pulverization is an index, but the average particle diameter (median diameter) is usually 0.4 μm or less, preferably 0.3 μm or less, more preferably 0.25 μm or less, most preferably Preferably, it is 0.2 μm or less. If the average particle size of the pulverized raw material particles is too large, the reactivity in the firing process is lowered, and the composition is difficult to homogenize. However, making particles smaller than necessary leads to an increase in the cost of pulverization, so that the average particle size is usually 0.01 μm or more, preferably 0.02 μm or more, more preferably 0.05 μm or more. It ’s fine. A means for realizing such a degree of pulverization is not particularly limited, but a wet pulverization method is preferable. Specific examples include dyno mill.

  In the present invention, the median diameter of the pulverized particles in the slurry was measured with a known laser diffraction / scattering type particle size distribution measuring apparatus with a refractive index of 1.24 and a particle diameter standard set as a volume standard. Is. In the present invention, a 0.1 wt% sodium hexametaphosphate aqueous solution was used as a dispersion medium used in the measurement, and measurement was performed after 5 minutes of ultrasonic dispersion (output 30 W, frequency 22.5 kHz). The median diameter of the spray-dried powder described later is the same as that except that the measurement was performed after ultrasonic dispersion for 0, 1, 3, and 5 minutes, respectively.

<Spray drying process>
After the wet mixing, it is then usually subjected to a drying process. The drying method is not particularly limited, but spray drying is preferable from the viewpoints of uniformity of the generated particulate matter, powder flowability, powder handling performance, and efficient production of dry particles.

<Spray-dried powder>
In the method for producing lithium transition metal-based compound powder such as lithium nickel manganese cobalt-based composite oxide powder of the present invention, the slurry obtained by wet-grinding the raw material compound and the additive is spray-dried, A powder obtained by agglomerating primary particles to form spherical secondary particles is obtained. The spray-dried powder formed by agglomerating primary particles to form spherical secondary particles is a shape feature of the spray-dried powder of the present invention. Examples of the shape confirmation method include SEM observation and cross-sectional SEM observation.

  The median diameter of a powder obtained by spray drying which is also a firing precursor of a lithium transition metal compound powder such as the lithium nickel manganese cobalt composite oxide powder of the present invention (in this case, a value measured without ultrasonic dispersion) ) Is usually 23 μm or less, more preferably 18 μm or less, still more preferably 13 μm or less, and most preferably 11 μm or less. However, since it tends to be difficult to obtain a too small particle size, it is usually 3 μm or more, preferably 4 μm or more, more preferably 5 μm or more. In the case of producing a particulate material by the spray drying method, the particle size can be controlled by appropriately selecting the spray format, the pressurized gas flow supply rate, the slurry supply rate, the drying temperature, and the like. Further, the upper limit of the median diameter of the spray-dried particles when measured after applying ultrasonic dispersion “Ultra Sonic” (output 30 W, frequency 22.5 kHz) for 5 minutes is usually 20 μm or less, preferably 15 μm or less. Preferably, it is 10 μm or less, most preferably 8 μm or less, and the lower limit is usually 3 μm or more, preferably 3.5 μm or more, more preferably 4 μm or more, and most preferably 4.5 μm or more. In the case of producing a particulate material by the spray drying method, the particle size can be controlled by appropriately selecting the spray format, the pressurized gas flow supply rate, the slurry supply rate, the drying temperature, and the like.

  That is, for example, a nickel compound, a manganese compound, a cobalt compound, and a slurry in which an additive that suppresses grain growth and sintering during firing is dispersed in a liquid medium is spray-dried. When the mixture is fired and classified to produce lithium transition metal-based compound powder such as lithium nickel manganese cobalt-based composite oxide powder, the slurry viscosity during spray drying is V (cp), and the slurry supply amount is When S (L / min) and gas supply amount are G (L / min), the slurry viscosity V is 50 cp ≦ V ≦ 4000 cp, and the gas-liquid ratio G / S is 500 ≦ G / S. Spray drying is performed under the condition of ≦ 10000.

  If the slurry viscosity V (cp) is too low, the primary particles may aggregate to make it difficult to obtain a powder formed of secondary particles. If the slurry viscosity is too high, the supply pump may fail or the nozzle may be blocked. There is a fear. Therefore, the slurry viscosity V (cp) is usually 50 cp or more as a lower limit, preferably 100 cp or more, more preferably 300 cp or more, most preferably 500 cp, and the upper limit is usually 4000 cp or less, preferably 3500 cp or less. Is 3000 cp or less, most preferably 2500 cp or less.

  Further, when the gas-liquid ratio G / S is less than the above lower limit, the secondary particle size is likely to be coarsened or the drying property is liable to be lowered, and when it exceeds the upper limit, the productivity may be lowered. Therefore, the gas-liquid ratio G / S is usually 500 or more as a lower limit, preferably 1000 or more, more preferably 1500 or more, most preferably 1800 or more, and the upper limit is usually 10,000 or less, preferably 9000 or less, Preferably it is 8000 or less, most preferably 7500 or less.

  The slurry supply amount S and the gas supply amount G are appropriately set according to the viscosity of the slurry used for spray drying, the specifications of the spray drying apparatus used, and the like.

  In the method of the present invention, the above-mentioned gas-liquid ratio G / S is satisfied by controlling the slurry supply amount and gas supply amount that meet the above-mentioned slurry viscosity V (cp) and that are suitable for the specifications of the spray drying apparatus to be used. Spray drying may be performed within a range, and other conditions are appropriately set according to the type of apparatus to be used, but it is preferable to select the following conditions.

  That is, spray drying of the slurry is usually 50 ° C. or higher, preferably 70 ° C. or higher, more preferably 120 ° C. or higher, most preferably 140 ° C. or higher, usually 300 ° C. or lower, preferably 250 ° C. or lower, more preferably 200 ° C. It is preferable to carry out the reaction at a temperature of ℃ or less, most preferably 180 ℃ or less. If this temperature is too high, the resulting granulated particles may have a lot of hollow structures, which may reduce the packing density of the powder. On the other hand, if it is too low, problems such as powder sticking and blockage due to moisture condensation at the powder outlet may occur.

In addition, the spray-dried powder of the present invention is characterized by a strong cohesion between primary particles, and this indicates the degree of change in median diameter accompanying ultrasonic dispersion in the spray-dried body of the present invention. Can be confirmed. For example, when expressed by the difference ΔD ₅₀ between the median diameter (μm) measured without ultrasonic dispersion and the median diameter (μm) measured after 5 minutes of ultrasonic dispersion, the lower limit is usually 0 μm or more, The upper limit is usually 3 μm or less, preferably 2.5 μm or less, more preferably 2 μm or less. Lithium transition metal compound particles fired using spray-dried particles having a ΔD ₅₀ greater than the above value have a weak cohesion between primary particles and are liable to collapse, resulting in a decrease in bulk density and poor coating properties. There is a risk that problems such as

The bulk density of the spray-dried powder of the present invention is usually 0.1 g / cm ³ or more, preferably 0.3 g / cm ³ or more, more preferably 0.5 g / cm ³ or more, and most preferably 0.7 g / cm ^3. cm ³ or more, and usually 1.7 g / cm ³ or less, preferably 1.6 g / cm ³ or less, more preferably 1.5 g / cm ³ or less, and most preferably 1.4 g / cm ³ or less. . If the bulk density is less than this lower limit, there is a possibility of adversely affecting the powder filling property and powder handling, and exceeding this upper limit is preferable for powder filling property and powder handling, while the specific surface area is small. It may become too low, and the reactivity in a baking process may fall.

In addition, when the spray-dried body of the present invention has a small specific surface area, the reactivity between the raw material compounds is reduced in the next firing step. As described above, the starting material is pulverized before spray-drying, etc. The specific surface area is preferably as high as possible by the means. On the other hand, an excessive increase in specific surface area is not only industrially disadvantageous but also may result in failure to obtain a lithium transition metal compound such as the lithium nickel manganese cobalt composite oxide of the present invention. Therefore, the spray-dried powder thus obtained has a BET specific surface area of usually 50 m ² / g or more, preferably 60 m ² / g or more, more preferably 70 m ² / g or more, and most preferably 80 m ² / g or more. In general, it is preferably 200 m ² / g or less, preferably 150 m ² / g or less, more preferably 120 m ² / g or less, and most preferably 100 m ² / g or less.

<Mixed powder preparation process>
The spray-dried product obtained in the spray-drying process is then mixed with the lithium compound raw material. Although there is no restriction | limiting in particular in the mixing method of the lithium compound to spray-dried particle, It is preferable to use the powder mixing apparatus generally used for industrial use. The atmosphere in the system to be mixed is preferably an inert gas atmosphere in order to prevent carbon dioxide absorption in the air.

As a lithium compound mixed with the granulated particles obtained by spray drying, as the lithium compound, Li ₂ CO ₃ , LiNO ₃ , LiNO ₂ , LiOH, LiOH · H ₂ O, LiH, LiF, LiCl, LiBr, LiI , CH ₃ OOLi, Li ₂ O, Li ₂ SO ₄ , dicarboxylic acid Li, citrate Li, fatty acid Li, alkyllithium and the like. Among these lithium compounds, lithium compounds containing no nitrogen atom, sulfur atom, or halogen atom are preferable because they do not generate harmful substances such as SO _x and NO _x during the firing treatment. Taking these points into consideration, Li ₂ CO ₃ , LiOH, and LiOH.H ₂ O are particularly preferable. Li ₂ CO is easy to handle and relatively inexpensive. ₃ is preferred. These lithium compounds may be used individually by 1 type, and may use 2 or more types together.

  As the particle size of such a lithium compound, the average particle size is usually 500 μm or less, preferably 100 μm or less in order to improve the mixing property with the spray-dried product obtained by spray drying and to improve battery performance. More preferably, it is 50 μm or less, and most preferably 20 μm or less. On the other hand, those having a too small particle size have an average particle size of usually 0.01 μm or more, preferably 0.1 μm or more, more preferably 0.2 μm or more, and most preferably 0 because of low stability in the atmosphere. .5 μm or more.

  The average particle size of the lithium compound is measured by a known laser diffraction / scattering particle size distribution measuring device with the particle size reference as the volume reference. In the present invention, ethyl alcohol was used as a dispersion medium used in the measurement, and measurement was performed after 5 minutes of ultrasonic dispersion (output 30 W, frequency 22.5 kHz).

  In this mixed powder preparation process, when mixing the lithium compound raw material and the spray-dried body, the target Li / (Ni + Mn + Co) molar ratio is controlled by adjusting the mixing ratio of Li and (Ni + Mn + Co). Can do.

<Baking process>
The mixed powder thus obtained is then fired. Here, in the present invention, the “mixed powder” refers to a lithium transition metal compound such as a lithium nickel manganese cobalt composite oxide before firing obtained by mixing the spray-dried powder and a lithium compound raw material. Mean precursor.

  This firing condition depends on the composition and the lithium compound raw material used, but as a tendency, if the firing temperature is too high, the primary particles grow excessively, the sintering between the particles proceeds too much, and the specific surface area is small. Too much. On the other hand, if it is too low, heterogeneous phases are mixed, and the lattice distortion increases without developing the crystal structure. Moreover, the specific surface area becomes too large. Therefore, the firing temperature is usually 700 ° C. or higher and 1300 ° C. or lower. However, in the production of the lithium nickel manganese cobalt composite oxide powder having the composition represented by the composition formula (I), the firing temperature is usually 900 ° C. or higher. Preferably it is 920 ° C or higher, more preferably 940 ° C or higher, more preferably 950 ° C or higher, most preferably 960 ° C or higher, usually 1200 ° C or lower, preferably 1175 ° C or lower, more preferably 1150 ° C or lower, most preferably 1125 ° C. or lower. In the production of the lithium nickel manganese cobalt based composite oxide powder having the composition represented by the composition formulas (I) and (II), the temperature is usually preferably 900 ° C. or higher, more preferably 950 ° C. or higher, and still more preferably 970. C. or higher, most preferably 990 ° C. or higher, usually 1200 ° C. or lower, preferably 1175 ° C. or lower, more preferably 1150 ° C. or lower, most preferably 1125 ° C. or lower.

  For firing, for example, a box furnace, a tubular furnace, a tunnel furnace, a rotary kiln or the like can be used. The firing process is usually divided into three parts: temperature increase, maximum temperature retention, and temperature decrease. The second maximum temperature holding portion is not necessarily limited to one time, and may include two or more stages depending on the purpose, which means that aggregation is eliminated to the extent that secondary particles are not destroyed. The temperature raising, maximum temperature holding, and temperature lowering steps may be repeated twice or more with a crushing step or a crushing step meaning crushing to primary particles or even fine powder.

  In the temperature raising step, the temperature in the furnace is usually raised at a temperature raising rate of 1 ° C./min to 10 ° C./min. Even if this rate of temperature rise is too slow, it takes time and is industrially disadvantageous. However, if it is too fast, the furnace temperature does not follow the set temperature depending on the furnace. The rate of temperature rise is preferably 2 ° C./min or more, more preferably 3 ° C./min or more, preferably 7 ° C./min or less, more preferably 5 ° C./min or less.

  Although the holding time in the maximum temperature holding step varies depending on the temperature, it is usually 30 minutes or more, preferably 1 hour or more, more preferably 3 hours or more, most preferably 5 hours or more within the above-mentioned temperature range, and 50 Time or less, preferably 25 hours or less, more preferably 20 hours or less, and most preferably 15 hours or less. If the firing time is too short, it becomes difficult to obtain a lithium transition metal-based compound powder with good crystallinity, and it is not practical to be too long. If the firing time is too long, it will be disadvantageous because it will be necessary to crush afterwards or it will be difficult to crush.

  In the temperature lowering step, the temperature in the furnace is normally decreased at a temperature decreasing rate of 0.1 ° C./min to 10 ° C./min. If the temperature lowering rate is too slow, it takes time and is industrially disadvantageous, but if it is too fast, the uniformity of the target product tends to be lost or the deterioration of the container tends to be accelerated. The temperature lowering rate is preferably 1 ° C./min or more, more preferably 3 ° C./min or more, preferably 7 ° C./min or less, more preferably 5 ° C./min or less.

Since the firing atmosphere has an appropriate oxygen partial pressure region depending on the composition of the lithium transition metal-based compound powder to be obtained, appropriate various gas atmospheres for satisfying the oxygen partial pressure region are used. Examples of the gas atmosphere include oxygen, air, nitrogen, argon, hydrogen, carbon dioxide, and a mixed gas thereof. An oxygen-containing gas atmosphere such as air can be used for the lithium nickel manganese cobalt based composite oxide powder specifically implemented in the present invention. Usually, the atmosphere has an oxygen concentration of 1% by volume or more, preferably 10% by volume or more, more preferably 15% by volume or more, and 100% by volume or less, preferably 50% by volume or less, more preferably 25% by volume or less.

<Classification process>
The fired powder thus obtained is then classified. For classification, for example, vibration classification using a sieve shaker, classification using centrifugal force, suction classification, or the like can be used.

  According to the lithium transition metal-based compound powder of the present invention such as lithium nickel manganese cobalt-based composite oxide powder thus obtained, the bulk density is high, the capacity is high, and load characteristics such as rate and output are achieved. Provided is a positive electrode material for lithium secondary batteries having an excellent performance balance.

[Positive electrode for lithium secondary battery]
The positive electrode for a lithium secondary battery of the present invention is obtained by forming a positive electrode active material layer containing a lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention and a binder on a current collector. It is. Here, as the positive electrode material, only one kind of the lithium transition metal compound powder of the present invention may be used, or two or more kinds may be mixed and used, or the lithium transition metal compound of the present invention may be used. You may mix and use 1 or more types of powder, and 1 or more types of the other positive electrode active material powder. When the lithium transition metal-based compound powder of the present invention is used in combination with the other positive electrode active material, the lithium transition metal-based compound of the present invention is used in order to obtain a sufficient effect by the lithium transition metal-based compound powder of the present invention. The ratio of the lithium transition metal based compound powder of the present invention to the total of the compound powder and the other positive electrode active material is preferably 15% by weight or more, and preferably 30% by weight or more. Is more preferable, and most preferably 50% by weight or more.

  The positive electrode active material layer is usually formed by mixing a positive electrode material, a binder, and a conductive material and a thickener, which are used if necessary, in a dry form into a sheet shape, and then pressing the positive electrode current collector on the positive electrode current collector. Alternatively, these materials are dissolved or dispersed in a liquid medium to form a slurry, which is applied to the positive electrode current collector and dried.

  As the material for the positive electrode current collector, metal materials such as aluminum, stainless steel, nickel plating, titanium, and tantalum, and carbon materials such as carbon cloth and carbon paper are usually used. Of these, metal materials are preferable, and aluminum is particularly preferable. As for the shape, in the case of a metal material, a metal foil, a metal cylinder, a metal coil, a metal plate, a metal thin film, an expanded metal, a punch metal, a foam metal, etc., and in the case of a carbon material, a carbon plate, a carbon thin film, a carbon cylinder Etc. Among these, metal thin films are preferable because they are currently used in industrialized products. In addition, you may form a thin film suitably in mesh shape.

  When a thin film is used as the positive electrode current collector, its thickness is arbitrary, but it is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and usually 100 mm or less, preferably 1 mm or less, more preferably 50 μm or less. The range of is preferable. If it is thinner than the above range, the strength required for the current collector may be insufficient. On the other hand, if it is thicker than the above range, the handleability may be impaired.

  The binder used in the production of the positive electrode active material layer is not particularly limited, and in the case of a coating method, any material that is stable with respect to the liquid medium used during electrode production may be used. Specific examples include polyethylene, Resin polymers such as polypropylene, polyethylene terephthalate, polymethyl methacrylate, aromatic polyamide, cellulose, nitrocellulose, SBR (styrene butadiene rubber), NBR (acrylonitrile butadiene rubber), fluorine rubber, isoprene rubber, butadiene rubber, ethylene・ Rubber polymers such as propylene rubber, styrene / butadiene / styrene block copolymers and hydrogenated products thereof, EPDM (ethylene / propylene / diene terpolymers), styrene / ethylene / butadiene / ethylene copolymers, Styrene / isoprene styrene bromide Copolymer and its hydrogenated thermoplastic elastomeric polymer, syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene / vinyl acetate copolymer, propylene / α-olefin copolymer, etc. Fluorine polymers such as soft resinous polymers, polyvinylidene fluoride, polytetrafluoroethylene, fluorinated polyvinylidene fluoride, polytetrafluoroethylene / ethylene copolymers, ion conductivity of alkali metal ions (especially lithium ions) And a polymer composition having the same. In addition, these substances may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.

  The ratio of the binder in the positive electrode active material layer is usually 0.1% by weight or more, preferably 1% by weight or more, more preferably 5% by weight or more, and usually 80% by weight or less, preferably 60% by weight or less. More preferably, it is 40% by weight or less, and most preferably 10% by weight or less. If the proportion of the binder is too low, the positive electrode active material cannot be sufficiently retained and the positive electrode has insufficient mechanical strength, which may deteriorate battery performance such as cycle characteristics. Battery capacity and conductivity may be reduced.

  The positive electrode active material layer usually contains a conductive material in order to increase conductivity. There are no particular restrictions on the type, but specific examples include metal materials such as copper and nickel, graphite such as natural graphite and artificial graphite, carbon black such as acetylene black, and amorphous carbon such as needle coke. And carbon materials. In addition, these substances may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios. The proportion of the conductive material in the positive electrode active material layer is usually 0.01% by weight or more, preferably 0.1% by weight or more, more preferably 1% by weight or more, and usually 50% by weight or less, preferably 30%. % By weight or less, more preferably 20% by weight or less. If the proportion of the conductive material is too low, the conductivity may be insufficient, and conversely if it is too high, the battery capacity may be reduced.

  As a liquid medium for forming a slurry, it is possible to dissolve or disperse a lithium transition metal compound powder as a positive electrode material, a binder, and a conductive material and a thickener used as necessary. If it is a solvent, there is no restriction | limiting in particular in the kind, You may use either an aqueous solvent or an organic solvent. Examples of the aqueous solvent include water and alcohol. Examples of the organic solvent include N-methylpyrrolidone (NMP), dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, N , N-dimethylaminopropylamine, ethylene oxide, tetrahydrofuran (THF), toluene, acetone, dimethyl ether, dimethylacetamide, hexamethylphosphalamide, dimethyl sulfoxide, benzene, xylene, quinoline, pyridine, methylnaphthalene, hexane, etc. be able to. In particular, when an aqueous solvent is used, a dispersant is added together with the thickener, and a slurry such as SBR is slurried. In addition, these solvents may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  The content of the lithium transition metal-based compound powder of the present invention as the positive electrode material in the positive electrode active material layer is usually 10% by weight or more, preferably 30% by weight or more, more preferably 50% by weight or more, and usually 99%. .9% by weight or less, preferably 99% by weight or less. If the proportion of the lithium transition metal compound powder in the positive electrode active material layer is too large, the strength of the positive electrode tends to be insufficient, and if it is too small, the capacity may be insufficient.

  The thickness of the positive electrode active material layer is usually about 10 to 200 μm.

The positive electrode active material layer obtained by coating and drying is preferably consolidated by a roller press or the like in order to increase the packing density of the positive electrode active material.
Thus, the positive electrode for a lithium secondary battery of the present invention can be adjusted.

[Lithium secondary battery]
The lithium secondary battery of the present invention includes a positive electrode for a lithium secondary battery according to the present invention that can occlude and release lithium, a negative electrode that can occlude and release lithium, and a non-aqueous electrolyte that uses a lithium salt as an electrolytic salt. Prepare. Further, a separator for holding a nonaqueous electrolyte may be provided between the positive electrode and the negative electrode. In order to effectively prevent a short circuit due to contact between the positive electrode and the negative electrode, it is desirable to interpose a separator in this way.

<Negative electrode>
The negative electrode is usually configured by forming a negative electrode active material layer on a negative electrode current collector, similarly to the positive electrode.
As a material of the negative electrode current collector, a metal material such as copper, nickel, stainless steel, nickel-plated steel, or a carbon material such as carbon cloth or carbon paper is used. Among these, in the case of a metal material, a metal foil, a metal cylinder, a metal coil, a metal plate, a metal thin film, etc., and in the case of a carbon material, a carbon plate, a carbon thin film, a carbon cylinder, etc. are mentioned. Among these, metal thin films are preferable because they are currently used in industrialized products. In addition, you may form a thin film suitably in mesh shape. When a metal thin film is used as the negative electrode current collector, the preferred thickness range is the same as the range described above for the positive electrode current collector.

  The negative electrode active material layer includes a negative electrode active material. The negative electrode active material is not particularly limited as long as it can electrochemically occlude and release lithium ions, but it can usually occlude and release lithium from the viewpoint of high safety. A carbon material is used.

  Although there is no restriction | limiting in particular as a carbon material, Graphite (graphite), such as artificial graphite and natural graphite, and the thermal decomposition thing of organic substance on various thermal decomposition conditions are mentioned. Examples of pyrolysis products of organic matter include coal-based coke, petroleum-based coke, coal-based pitch carbide, petroleum-based pitch carbide, or carbide obtained by oxidizing these pitches, needle coke, pitch coke, phenol resin, crystalline cellulose, etc. And carbon materials obtained by partially graphitizing these, furnace black, acetylene black, pitch-based carbon fibers, and the like. Among them, graphite is preferable, and particularly preferable is artificial graphite, purified natural graphite, or graphite material containing pitch in these graphites, which is manufactured by subjecting easy-graphite pitch obtained from various raw materials to high-temperature heat treatment. Therefore, those subjected to various surface treatments are mainly used. One of these carbon materials may be used alone, or two or more thereof may be used in combination.

When a graphite material is used as the negative electrode active material, the d value (interlayer distance: d ₀₀₂ ) of the lattice plane (002 plane) determined by X-ray diffraction by the Gakushin method is usually 0.335 nm or more, and usually 0.34 nm. In the following, it is preferable that the thickness is 0.337 nm or less.

  Further, the ash content of the graphite material is usually 1% by weight or less, particularly 0.5% by weight or less, and particularly preferably 0.1% by weight or less, based on the weight of the graphite material.

Furthermore, the crystallite size (L _c ) of the graphite material determined by X-ray diffraction by the Gakushin method is usually 30 nm or more, preferably 50 nm or more, particularly preferably 100 nm or more.

  The median diameter of the graphite material determined by the laser diffraction / scattering method is usually 1 μm or more, especially 3 μm or more, more preferably 5 μm or more, especially 7 μm or more, and usually 100 μm or less, especially 50 μm or less, more preferably 40 μm or less, especially 40 μm or less. It is preferable that it is 30 micrometers or less.

Moreover, the BET specific surface area of the graphite material is usually 0.5 m ² / g or more, preferably 0.7 m ² / g or more, more preferably 1.0 m ² / g or more, and further preferably 1.5 m ² / g. or more, and usually 25.0 m ² / g or less, preferably 20.0 m ² / g, more preferably 15.0 m ² / g or less, still more preferably 10.0 m ² / g or less.

Further, when performing Raman spectroscopy using argon laser light for graphite material, and strength _{I A} of the peak PA detected in the range of 1580～1620Cm ^-1, is detected in the range of 1350 ^-1 intensity ratio _I a / _{I B} of the intensity _{I B} of a peak _{P B} is what is preferably 0 to 0.5. Further, the half width of the peak _{P A} is preferably 26cm ^-1 or less, 25 cm ^-1 or less is more preferable.

In addition to the above-mentioned various carbon materials, it can also be used as a negative electrode active material of other materials capable of inserting and extracting lithium. Specific examples of negative electrode active materials other than carbon materials include metal oxides such as tin oxide and silicon oxide, nitrides such as Li _2.6 Co _0.4 N, and lithium alloys such as lithium alone and lithium aluminum alloys. Can be mentioned. One of these materials other than the carbon material may be used alone, or two or more thereof may be used in combination. Moreover, you may use in combination with the above-mentioned carbon material.

As in the case of the positive electrode active material layer, the negative electrode active material layer is usually prepared by slurrying the above-described negative electrode active material, a binder, and optionally a conductive material and a thickener in a liquid medium. It can manufacture by apply | coating to a negative electrode electrical power collector, and drying. As the liquid medium, the binder, the thickener, the conductive material and the like that form the slurry, the same materials as those described above for the positive electrode active material layer can be used.

<Nonaqueous electrolyte>
As the non-aqueous electrolyte, for example, known organic electrolytes, polymer solid electrolytes, gel electrolytes, inorganic solid electrolytes, and the like can be used. Among them, organic electrolytes are preferable. The organic electrolytic solution is configured by dissolving a solute (electrolyte) in an organic solvent.

  Here, the type of the organic solvent is not particularly limited. For example, carbonates, ethers, ketones, sulfolane compounds, lactones, nitriles, chlorinated hydrocarbons, ethers, amines, esters, amides. A phosphoric acid ester compound or the like can be used. Typical examples include dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propylene carbonate, ethylene carbonate, vinylene carbonate, vinyl ethylene carbonate, tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 4-methyl-2- Pentanone, 1,2-dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone, 1,3-dioxolane, 4-methyl-1,3-dioxolane, diethyl ether, sulfolane, methylsulfolane, acetonitrile, propionitrile Benzonitrile, butyronitrile, valeronitrile, 1,2-dichloroethane, dimethylformamide, dimethyl sulfoxide, trimethyl phosphate, triethyl phosphate, etc. Et compounds, hydrogen atoms may be partially substituted with a halogen atom. Moreover, these single or 2 or more types of mixed solvents can be used.

  The organic solvent described above preferably contains a high dielectric constant solvent in order to dissociate the electrolytic salt. Here, the high dielectric constant solvent means a compound having a relative dielectric constant of 20 or more at 25 ° C. Among the high dielectric constant solvents, it is preferable that ethylene carbonate, propylene carbonate, and compounds in which hydrogen atoms thereof are substituted with other elements such as halogen or alkyl groups are contained in the electrolytic solution. The proportion of the high dielectric constant solvent in the electrolyte is preferably 20% by weight or more, more preferably 25% by weight or more, and most preferably 30% by weight or more. If the content of the high dielectric constant solvent is less than the above range, desired battery characteristics may not be obtained.

In addition, in the organic electrolyte, a gas such as CO ₂ , N ₂ O, CO, and SO ₂ , vinylene carbonate, polysulfide S _x ^{2−, and the} like that enables efficient charge and discharge of lithium ions on the negative electrode surface You may add the additive which forms a film in arbitrary ratios. Among these additives, vinylene carbonate is particularly preferable.

  Furthermore, an additive that exhibits an effect of improving cycle life and output characteristics, such as lithium difluorophosphate, may be added to the organic electrolyte at an arbitrary ratio.

The type of the electrolytic salt is not particularly limited, and any conventionally known solute can be used. Specific examples include LiClO ₄ , LiAsF ₆ , LiPF ₆ , LiBF ₄ , LiB (C ₆ H ₅ ) ₄ , LiBOB, LiCl, LiBr, CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , LiC (SO ₂ CF ₃ ) ₃ , LiN (SO ₃ CF ₃ ) _{2 and the} like. Any one of these electrolytic salts may be used alone, or two or more thereof may be used in any combination and ratio.

  The lithium salt of the electrolytic salt is usually contained in the electrolytic solution so as to have a concentration of 0.5 mol / L to 1.5 mol / L. Even if the lithium salt concentration in the electrolytic solution is less than 0.5 mol / L or more than 1.5 mol / L, the electric conductivity may be lowered, and the battery characteristics may be adversely affected. The lower limit of this concentration is preferably 0.75 mol / L or more and the upper limit is 1.25 mol / L or less.

Even when a polymer solid electrolyte is used, the type thereof is not particularly limited, and any known crystalline / amorphous inorganic substance can be used as the solid electrolyte. Examples of the crystalline inorganic solid electrolyte include LiI, Li ₃ N, Li _{1 + x} J _x Ti _2-x (PO ₄ ) ₃ (J = Al, Sc, Y, La), Li _0.5-3x RE _{0. .5 + x} TiO ₃ (RE = La, Pr, Nd, Sm) and the like. Examples of the amorphous inorganic solid electrolyte include oxide glasses such as 4.9LiI-34.1Li ₂ O-61B ₂ O ₅ and 33.3Li ₂ O-66.7SiO ₂ . Any one of these may be used alone, or two or more may be used in any combination and ratio.

<Separator>
When the above-described organic electrolyte is used as the electrolyte, a separator is interposed between the positive electrode and the negative electrode in order to prevent a short circuit between the electrodes. The material and shape of the separator are not particularly limited, but those that are stable with respect to the organic electrolyte used, have excellent liquid retention properties, and can reliably prevent short-circuiting between electrodes are preferable. Preferable examples include microporous films, sheets, nonwoven fabrics and the like made of various polymer materials. Specific examples of the polymer material include polyolefin polymers such as nylon, cellulose acetate, nitrocellulose, polysulfone, polyacrylonitrile, polyvinylidene fluoride, polypropylene, polyethylene, and polybutene. In particular, from the viewpoint of chemical and electrochemical stability, which is an important factor for separators, polyolefin polymers are preferable. From the viewpoint of self-occluding temperature, which is one of the purposes of use of separators in batteries, polyethylene is preferred. Is particularly desirable.

  When using a separator made of polyethylene, it is preferable to use ultra-high molecular weight polyethylene from the viewpoint of maintaining high-temperature shape, and the lower limit of the molecular weight is preferably 500,000, more preferably 1,000,000, and most preferably 1,500,000. On the other hand, the upper limit of the molecular weight is preferably 5 million, more preferably 4 million, and most preferably 3 million. This is because if the molecular weight is too large, the fluidity becomes too low, and the pores of the separator may not close when heated.

<Battery shape>
The lithium secondary battery of the present invention is manufactured by assembling the above-described positive electrode for a lithium secondary battery of the present invention, a negative electrode, an electrolyte, and a separator used as necessary into an appropriate shape. Furthermore, other components such as an outer case can be used as necessary.

  The shape of the lithium secondary battery of the present invention is not particularly limited, and can be appropriately selected from various commonly employed shapes according to the application. Examples of commonly used shapes include a cylinder type with a sheet electrode and separator in a spiral shape, a cylinder type with an inside-out structure combining a pellet electrode and a separator, and a coin type with stacked pellet electrodes and a separator. Can be mentioned. The method for assembling the battery is not particularly limited, and can be appropriately selected from various commonly used methods according to the shape of the target battery.

  The general embodiment of the lithium secondary battery of the present invention has been described above. However, the lithium secondary battery of the present invention is not limited to the above-described embodiment, and various modifications are possible as long as the gist thereof is not exceeded. Can be implemented.

  The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples as long as the gist of the present invention is not exceeded.

[Measurement method of physical properties]
The physical properties and the like of lithium transition metal-based compound powders produced in each Example and Comparative Example described below were measured as follows.

<Average primary particle size>
It calculated | required from the SEM image of 30,000 times.

<Secondary particle size>
The median diameter and 90% cumulative diameter (D ₉₀ ) as the average particle diameter are set to a refractive index of 1.24 using a known laser diffraction / scattering particle size distribution measuring device (LA-920, manufactured by Horiba, Ltd.) The particle diameter standard was measured using the volume standard. Moreover, 0.1 weight% sodium hexametaphosphate aqueous solution was used as a dispersion medium, and it measured after ultrasonic dispersion (output 30W, frequency 22.5kHz) for 0 minute and 5 minutes.

<Bulk density>
4 to 10 g of the sample powder was put into a 10 ml glass graduated cylinder, and the powder packing density when tapped 200 times with a stroke of about 20 mm was obtained.

<Measurement of various physical properties by mercury intrusion method>
As a measuring device by the mercury intrusion method, Autopore III9420 manufactured by Micromeritics was used. Moreover, as measurement conditions of the mercury intrusion method, measurement was performed while increasing the pressure from 3.86 kPa to 413 MPa at room temperature. The mercury surface tension value was 480 dyn / cm, and the contact angle value was 141.3 °.

<Specific surface area>
Obtained by BET method.

<Volume resistivity>
Using a powder resistivity measuring device (Dia Instruments: Lorester GP powder low-efficiency measurement system PD-41), the sample weight was 2 g, and a powder probe unit (four probe / ring electrode, electrode spacing 5.0 mm) The electrode resistivity is 1.0 mm, the sample radius is 12.5 mm, and the applied voltage limiter is 90 V. The volume resistivity [Ω · cm] of the powder under various pressures is measured, and the volume resistivity under a pressure of 40 MPa is measured. The values were compared.

<Composition (Li / Ni / Mn / Co)>
It was determined by ICP-AES analysis.

<Quantification of additive element (W) and foreign element (B)>
It was determined by ICP-AES analysis.

<Composition analysis of primary particle surface by X-ray photoelectron spectroscopy (XPS)>
(XPS measurement)
The measurement was performed under the following conditions using an X-ray photoelectron spectrometer “ESCA-5700” manufactured by Physical Electronics.
X-ray source: Monochromatic AlKα
Analysis area: 0.8mm diameter Extraction angle: 65 °
Quantitative method: B1s, Mn2p _1/2 , Co2p _3/2 , Ni2p _3/2 , W4f area of each peak is corrected with a sensitivity coefficient.
(Surface sputtering)
Ion species: Ar
Acceleration voltage: 3 kV
Ion current: 6.6 nA
Sputtering rate: 2.29 nm / min (in terms of SiO ₂ )

<Contained carbon concentration C>
An EMIA-520 carbon sulfur analyzer manufactured by HORIBA, Ltd. was used. A sample of several tens to 100 mg was weighed into an air-baked magnetic crucible, a combustion aid was added, and carbon was extracted by combustion in a high-frequency heating furnace in an oxygen stream. CO ₂ in the combustion gas was quantified by non-dispersive infrared absorption spectrophotometry. For sensitivity calibration, 150-15 low alloy steel No. 1 (C guaranteed value: 0.469% by weight) manufactured by Japan Iron and Steel Federation was used.

<Confirmation of crystal phase (layered structure), measurement of half-width FWHM (110) (018) (110) (113) Confirmation of presence / absence of heterophase peak in diffraction peak, and integral intensity of heterophase peak / original crystal phase peak and Calculation of integral intensity ratio>
It calculated | required by the powder X-ray-diffraction measurement using the CuK (alpha) ray described below. Profile fitting was performed on the (018), (110), and (113) diffraction peaks derived from the hexagonal system R-3m (No. 166) observed in each sample, and integrated intensity, integrated intensity ratio, and the like were calculated.
・ For calculation of half width and area, use diffraction pattern when measured in fixed slit mode of concentration method ・ For actual XRD measurement (example, comparative example), measure in variable slit mode, variable → fixed Data conversion is performed.-Conversion from variable to fixed is based on the formula of intensity (fixed) = intensity (variable) / sin θ (powder X-ray diffraction measurement device specification)
Device name: X'Pert Pro MPD manufactured by PANallytical, Netherlands
Optical system: Concentrated optical system (optical system specification)
Incident side: Enclosed X-ray tube (CuKα)
Soller Slit (0.04 rad)
Divergence Slit (Variable Slit)
Sample stage: Rotating sample stage (Spinner)
Light receiving side: Semiconductor array detector (X'Celerator)
Ni-filter
Gonio radius: 243mm
(Measurement condition)
X-ray output (CuKα): 40 kV, 30 mA
Scanning axis: θ / 2θ
Scanning range (2θ): 10.0-75.0 °
Measurement mode: Continuous
Reading width: 0.015 °
Counting time: 99.7 sec
Automatic variable slit (Automatic-DS: 10 mm (irradiation width))
Lateral divergence mask: 10 mm (irradiation width)

<Lattice constant>
From the diffraction measurement results, a lattice constant refinement calculation was performed. The peak position was calculated by a profile fitting method (Peason-VII function). As initial values, parameters of hexagonal system / R (−3) m [166] were used for the crystal system / space group, and LiNiO ₂ [PDF: 9-63] was used for the lattice constant. The lattice constant and sample eccentricity parameter were refined, and the zero shift parameter was not refined. As analysis software, Materials Data Inc. JADE (v7.5.2 Japanese version) manufactured by the company was used.

<Median diameter of pulverized particles in slurry>
Using a known laser diffraction / scattering particle size distribution measuring device, the refractive index was set to 1.24, and the particle diameter standard was measured as the volume standard. Further, a 0.1 wt% aqueous solution of sodium hexametaphosphate was used as a dispersion medium, and measurement was performed after 5 minutes of ultrasonic dispersion (output 30 W, frequency 22.5 kHz).

<Median Diameter as Average Particle Diameter of Raw Material Li ₂ CO ₃ Powder>
Using a known laser diffraction / scattering particle size distribution measuring apparatus (LA-920, manufactured by Horiba, Ltd.), the refractive index was set to 1.24, and the particle diameter standard was measured as a volume standard. Further, ethyl alcohol was used as a dispersion medium, and measurement was performed after ultrasonic dispersion for 5 minutes (output 30 W, frequency 22.5 kHz).

<Physical properties of particulate powder obtained by spray drying>
The form was confirmed by SEM observation and cross-sectional SEM observation. The median diameter as the average particle diameter was measured with a known laser diffraction / scattering particle size distribution measuring apparatus (LA-920, manufactured by Horiba, Ltd.) with a refractive index of 1.24 and a particle diameter standard as a volume standard. . Further, a 0.1 wt% sodium hexametaphosphate aqueous solution was used as a dispersion medium, and measurement was performed after 0 minutes, 1 minute, 3 minutes, and 5 minutes of ultrasonic dispersion (output 30 W, frequency 22.5 kHz). The specific surface area was determined by the BET method. The bulk density was determined as the powder packing density when 4 to 10 g of the sample powder was put in a 10 ml glass graduated cylinder and tapped 200 times with a stroke of about 20 mm.

[Production of Lithium Transition Metal Compound Powder (Examples and Comparative Examples)]
Example 1
Ni (OH) ₂ , Mn ₃ O ₄ , CoOOH, WO ₃ are weighed so as to have a molar ratio of Ni: Mn: Co: W = 0.45: 0.45: 0.10: 0.01, After mixing, pure water was added thereto to prepare a slurry. While the slurry was stirred, the solid content in the slurry was pulverized to a median diameter of 0.21 μm using a circulating medium agitation type wet pulverizer (Shinmaru Enterprises Co., Ltd .: Dino Mill KDLA type).
Next, this slurry (solid content 13 wt%, viscosity 1640 cp) was spray-dried using a two-fluid nozzle type spray dryer (Okawara Kako Co., Ltd .: LT-8 type). Air was used as the drying gas at this time, the drying gas introduction amount G was 45 L / min, and the slurry introduction amount S was 11 × 10 ⁻³ mL / min (gas-liquid ratio G / S = 4091). The drying inlet temperature was 150 ° C. Li ₂ CO ₃ powder with a median diameter of 9 μm is added to the particulate powder obtained by spray drying with a spray dryer so that the Li / (Ni + Mn + Co) molar ratio is 1.12. Mixed. About 15 g of this mixed powder is charged in an alumina crucible, fired at 900 ° C. for 6 hours under an air flow of 1 L / min (temperature raising / lowering rate 3.33 ° C./min.), And then classified using a 45 μm sieve. And lithium nickel manganese cobalt composite oxide powder (x = 0.099, y) having a layered structure with a composition of Li (Li _0.056 Ni _0.424 Mn _0.427 Co _0.093 ) O ₂ = -0.003, z = 0.118). In this lithium nickel manganese cobalt composite oxide powder, when the total molar ratio of (Ni, Mn, Co) was 1, the W molar ratio was 1.05 mol%. Furthermore, the atomic ratio of W on the surface of primary particles (W / (Ni + Mn + Co)) was 6.7 times the atomic ratio of W (tungsten) for the entire particle (W / (Ni + Mn + Co)). The lithium nickel manganese cobalt composite oxide powder has an average primary particle diameter of 0.2 μm, a median diameter of 5.0 μm, a 90% cumulative diameter (D ₉₀ ) of 7.4 μm, and a bulk density of 1.7 g / cm ³ , the BET specific surface area was 3.3 m ² / g, the volume resistivity was 6.3 × 10 ⁴ Ω · cm, and the contained carbon concentration C was 0.054% by weight.

(Example 2)
Lithium nickel manganese having a layered structure with a composition of Li (Li _0.063 Ni _0.421 Mn _0.423 Co _0.093 ) O ₂ in the same manner as in Example 1 except that the firing temperature was 950 ° C. A cobalt composite oxide powder (x = 0.099, y = −0.003, z = 0.134) was obtained. In this lithium nickel manganese cobalt composite oxide powder, when the total molar ratio of (Ni, Mn, Co) was 1, the W molar ratio was 1.04 mol%. Further, the atomic ratio of W on the surface of primary particles (W / (Ni + Mn + Co)) was 6.5 times the atomic ratio of W (tungsten) of the whole particle (W / (Ni + Mn + Co)). The lithium nickel manganese cobalt composite oxide powder has an average primary particle diameter of 0.2 μm, a median diameter of 5.1 μm, a 90% cumulative diameter (D ₉₀ ) of 7.6 μm, and a bulk density of 1.7 g / cm ³ , the BET specific surface area was 2.2 m ² / g, the volume resistivity was 4.8 × 10 ⁴ Ω · cm, and the carbon content C was 0.040 wt%.

(Example 3)
Lithium nickel manganese having a layered structure with a composition of Li (Li _0.062 Ni _0.421 Mn _0.424 Co _0.093 ) O ₂ in the same manner as in Example 1 except that the firing temperature was 1000 ° C. Cobalt composite oxide powder (x = 0.099, y = −0.003, z = 0.133) was obtained. In this lithium nickel manganese cobalt composite oxide powder, when the total molar ratio of (Ni, Mn, Co) was 1, the W molar ratio was 1.03 mol%. Furthermore, the atomic ratio of W (W / (Ni + Mn + Co)) on the surface of the primary particles was 8.8 times the atomic ratio of W (tungsten) of the whole particle (W / (Ni + Mn + Co)). Further, the total atomic ratio R ₀ of W to the total of (Ni, Mn, Co) on the outermost surface of the particle, and the total atomic ratio R of W to the total of (Ni, Mn, Co) at a depth of 10 nm from the particle surface. the ratio of the _{10 R} 0 _{/ R 10} was 4.3. The lithium nickel manganese cobalt composite oxide powder has an average primary particle size of 0.3 μm, a median size of 5.0 μm, a 90% cumulative diameter (D ₉₀ ) of 7.5 μm, and a bulk density of 1.7 g / cm ^3. The BET specific surface area was 1.7 m ² / g, the volume resistivity was 9.7 × 10 ⁴ Ω · cm, and the carbon concentration C was 0.037% by weight.

Example 4
Lithium nickel manganese cobalt having a layered structure with a composition of Li (Li _0.048 Ni _0.428 Mn _0.430 Co _0.094 ) O ₂ in the same manner as in Example 1 except that the firing temperature was 1050 ° C. A composite oxide powder (x = 0.099, y = −0.003, z = 0.100) was obtained. In this lithium nickel manganese cobalt composite oxide powder, when the total molar ratio of (Ni, Mn, Co) was 1, the W molar ratio was 1.03 mol%. Furthermore, the atomic ratio of W (W / (Ni + Mn + Co)) on the surface of the primary particles was 13 times the atomic ratio of W (tungsten) of the whole particle (W / (Ni + Mn + Co)). The lithium nickel manganese cobalt composite oxide powder has an average primary particle size of 0.5 μm, a median size of 5.1 μm, a 90% cumulative diameter (D ₉₀ ) of 7.5 μm, and a bulk density of 1.7 g / cm ^3. The BET specific surface area was 1.3 m ² / g, the volume resistivity was 8.0 × 10 ⁴ Ω · cm, and the carbon concentration C was 0.033 wt%.

(Example 5)
Ni (OH) ₂ , Mn ₃ O ₄ , CoOOH, H ₃ BO ₃ , WO ₃ are mixed with Ni: Mn: Co: B: W = 0.45: 0.45: 0.10: 0.0025: 0. After weighing and mixing to a molar ratio of 01, pure water was added thereto to prepare a slurry. While stirring this slurry, the solid content in the slurry was pulverized to a median diameter of 0.23 μm using a circulating medium agitation type wet pulverizer (Shinmaru Enterprises Co., Ltd .: Dino Mill KDLA type).
Next, this slurry (solid content 14% by weight, viscosity 2090 cp) was spray-dried using a two-fluid nozzle type spray dryer (Okawara Kako Co., Ltd .: LT-8 type). Air was used as the drying gas at this time, the drying gas introduction amount G was 45 L / min, and the slurry introduction amount S was 11 × 10 ⁻³ mL / min (gas-liquid ratio G / S = 4091). The drying inlet temperature was 150 ° C. Li ₂ CO ₃ powder with a median diameter of 9 μm is added to the particulate powder obtained by spray drying with a spray dryer so that the Li / (Ni + Mn + Co) molar ratio is 1.12. Mixed. About 15 g of this mixed powder is charged in an alumina crucible, fired at 900 ° C. for 6 hours under an air flow of 1 L / min (temperature raising / lowering rate 3.33 ° C./min.), And then classified using a 45 μm sieve. And a lithium nickel manganese cobalt composite oxide powder (x = 0.098, y) having a layered structure with a composition of Li (Li _0.058 Ni _0.423 Mn _0.427 Co _0.092 ) O ₂ = −0.004, z = 0.122). In this lithium nickel manganese cobalt composite oxide powder, when the total molar ratio of (Ni, Mn, Co) is 1, the molar ratios of B and W are 0.22 mol% and 1.03 mol%, respectively. there were. Further, the atomic ratio of B (B / (Ni + Mn + Co)) on the surface of the primary particle is 24 times the atomic ratio of B (boron) of the whole particle (B / (Ni + Mn + Co)), and the W (tungsten) of the whole particle. The atomic ratio (W / (Ni + Mn + Co)) of W on the primary particle surface was 7.0 times the atomic ratio (W / (Ni + Mn + Co)). Further, in the particle outermost surface (Ni, Mn, Co) and the atomic ratio _{R 0} of W relative to the total of, at a depth of 10nm from the particle surface (Ni, Mn, Co) to the total atomic ratio _{R 10} of W to the sum of The ratio R ₀ / R ₁₀ was 3.8. The lithium nickel manganese cobalt composite oxide powder has an average primary particle diameter of 0.2 μm, a median diameter of 5.2 μm, a 90% cumulative diameter (D ₉₀ ) of 7.9 μm, and a bulk density of 1.6 g / cm ^3. The BET specific surface area was 2.8 m ² / g, the volume resistivity was 1.5 × 10 ⁵ Ω · cm, and the contained carbon concentration C was 0.054% by weight .

( Comparative Example 3)
Ni (OH) ₂ , Mn ₃ O ₄ , and Co (OH) ₂ were weighed and mixed so as to have a molar ratio of Ni: Mn: Co = 0.45: 0.45: 0.10. Pure water was added to the slurry to prepare a slurry. While stirring the slurry, the solid content in the slurry was pulverized to a median diameter of 0.13 μm using a circulating medium agitation type wet pulverizer.
Next, this slurry (solid content 11% by weight, viscosity 1490 cp) was spray-dried using a two-fluid nozzle type spray dryer (Okawara Kako Co., Ltd .: LT-8 type). Air was used as the dry gas at this time, the dry gas introduction amount G was 45 L / min, and the slurry introduction amount S was 11 × 10 ⁻³ L / min (gas-liquid ratio G / S = 4091). The drying inlet temperature was 150 ° C.
LiOH powder pulverized to a median diameter of 20 μm or less was added to and mixed with the particulate powder obtained by spray drying as described above. About 13.1 g of this mixed powder was placed in an alumina crucible, fired at 1000 ° C. for 6 hours under air flow (temperature raising / lowering rate 3.33 ° C./min.), And then subjected to vibration classification using a 45 μm sieve. And a lithium nickel manganese cobalt composite oxide powder (x = 0.998, y = 0) having a layered structure with a composition of Li (Li _0.053 Ni _0.433 Mn _0.421 Co _0.093 ) O ₂ 0.013, z = 0.113). The lithium nickel manganese cobalt based composite oxide powder has an average primary particle size of 0.7 μm, a median diameter of 4.8 μm, a 90% cumulative diameter (D ₉₀ ) of 7.0 μm, and a bulk density of 1.6 g / cm. ³ , the BET specific surface area was 1.2 m ² / g, the volume resistivity was 1.7 × 10 ⁴ Ω · cm, and the contained carbon concentration C was 0.028 wt%.

  Tables 1, 2, 3, and 4 show the compositions and physical property values of the lithium transition metal compound powders produced in the above Examples and Comparative Examples. Table 5 shows the powder properties of the spray-dried body, which is a firing precursor.

Further, respectively Example 3, 5 depth direction of the concentration distribution curve from the surface of the additive elements in the lithium nickel manganese cobalt composite oxide produced in (XPS analysis), in 1 to 2, Example 1 5 and the pore distribution curve of a lithium nickel manganese cobalt composite oxide powder produced in Comparative example 3, FIG. 3 to 8 respectively 9 to the SEM image (photograph) (magnification × 10,000) 14 respectively to respectively show powder X-ray diffraction pattern in Figure 15-20.

[Production and evaluation of batteries]
Using the lithium nickel manganese cobalt composite oxide powders produced in Examples 1 to 5 and Comparative Example 3 described above as positive electrode materials (positive electrode active materials), lithium secondary batteries were produced by the following method and evaluated. went.

(1) Rate test:
A mortar obtained by weighing 75% by weight of each of the lithium nickel manganese cobalt composite oxide powders produced in Examples 1 to 5 and Comparative Example 3 , 20% by weight of acetylene black, and 5% by weight of polytetrafluoroethylene powder. Were mixed thoroughly and made into a thin sheet, and punched out using a 9 mmφ punch. At this time, the total weight was adjusted to about 8 mg. This was pressure-bonded to an aluminum expanded metal to obtain a 9 mmφ positive electrode.

This 9 mmφ positive electrode is used as a test electrode, a lithium metal plate is used as a counter electrode, and LiPF ₆ is added to a solvent of EC (ethylene carbonate): DMC (dimethyl carbonate): EMC (ethyl methyl carbonate) = 3: 3: 4 (volume ratio). Using an electrolytic solution dissolved at 1 mol / L, a coin-type cell was assembled using a porous polyethylene film having a thickness of 25 μm as a separator.

The obtained coin-type cell was subjected to a constant current constant voltage charge of 0.2 mA / cm ² at an upper limit voltage of 4.2 V and a constant current discharge test of 0.2 mA / cm ² at a lower limit voltage of 3.0 V in the first cycle. In the second cycle, a constant current constant voltage charge of 0.5 mA / cm ² at an upper limit voltage of 4.2 V and a constant current discharge test of 0.2 mA / cm ² at a lower limit voltage of 3.0 V were conducted. the cycle, constant current charge of 0.5 mA / cm ^2, was constant current discharge test of 11 mA / cm ^2.
At this time, the 0.1 C discharge capacity (mAh / g) (initial discharge capacity) in the first cycle and the 0.1 C discharge capacity (mAh / g) (third discharge capacity) in the third cycle were examined, and the results are shown. This is shown in FIG.

As an acceptance criterion for the examples, the initial discharge capacity in the first cycle was set to 145 mAh / g or more, and the high rate discharge capacity at 11 mA / cm ² in the third cycle was set to 102 mAh / g or more.

(2) Low temperature load characteristic test and high temperature cycle test:
In a mortar, the lithium nickel manganese cobalt composite oxide powders prepared in Examples 1 to 5 and Comparative Example 3 were weighed in a ratio of 75% by weight, acetylene black 20% by weight, and polytetrafluoroethylene powder 5% by weight. Thoroughly mixed and made into a thin sheet was punched out using a 12 mmφ punch. At this time, the total weight was adjusted to about 18 mg. This was pressure-bonded to an aluminum expanded metal to obtain a 12 mmφ positive electrode.

  Using the results of charge and discharge in the first cycle in the rate test of (1), the initial charge capacity per unit weight of the positive electrode active material is Qs (C) [mAh / g], and the initial discharge capacity is Qs (D) [mAh / g].

Graphite powder having an average particle size of 8 to 10 μm (d ₀₀₂ = 3.35 Å) was used as the negative electrode active material, and polyvinylidene fluoride was used as the binder, and these were weighed at a weight ratio of 92.5: 7.5. Were mixed in an N-methylpyrrolidone solution to obtain a negative electrode mixture slurry. This slurry was applied to one side of a 20 μm thick copper foil, dried to evaporate the solvent, punched to 12 mmφ, and pressed at 0.5 ton / cm ² (49 MPa) to form a negative electrode. At this time, the amount of the negative electrode active material on the electrode was adjusted to be about 5 to 12 mg.

A test in which a negative electrode is used as a test electrode, a battery cell is assembled using lithium metal as a counter electrode, and lithium ions are occluded in the negative electrode by a constant current-constant voltage method (cut current 0.05 mA) of 0.2 mA / cm ² -3 mV. The initial occlusion capacity per unit weight of the negative electrode active material when performing at a lower limit of 0 V was Q _f [mAh / g].

The positive electrode and the negative electrode were combined, a test battery was assembled using a coin cell, and the battery performance was evaluated. That is, the above-described positive electrode prepared is placed on the positive electrode can of the coin cell, a porous polyethylene film having a thickness of 25 μm is placed thereon as a separator, pressed with a polypropylene gasket, and then EC ( An electrolytic solution in which LiPF ₆ was dissolved at a rate of 1 mol / L in a solvent of ethylene carbonate): DMC (dimethyl carbonate): EMC (ethyl methyl carbonate) = 3: 3: 4 (volume ratio) was added to the can. After fully infiltrating the separator, the above-described negative electrode was placed, a negative electrode can was placed and sealed, and a coin-type lithium secondary battery was produced. At this time, the balance between the weight of the positive electrode active material and the weight of the negative electrode active material was set so as to satisfy the following expression.
Positive electrode active material weight [g] / Negative electrode active material weight [g]
= (Q _f [mAh / g] /1.2) Qs (C) [mAh / g]

In order to measure the low temperature load characteristics of the battery thus obtained, the 1 hour rate current value of the battery, that is, 1C, was set as shown in the following equation, and the following tests were performed.
1C [mA] = Qs (D) × positive electrode active material weight [g] / hour [h]

First, a constant current 0.2C charge / discharge cycle and a constant current 1C charge / discharge cycle were performed at room temperature. The upper limit of charging was 4.1 V, and the lower limit voltage was 3.0 V. Next, when a coin cell adjusted to a charging depth of 40% is held in a low temperature atmosphere of −30 ° C. for 1 hour or longer by 1/3 C constant current charging / discharging and then discharged for 10 seconds at a constant current of 0.5 C [mA]. Assuming that the voltage after 10 seconds is V [mV] and the voltage before discharge is V ₀ [mV], the resistance value R [Ω] is calculated from the following equation as ΔV = V−V ₀ .
R [Ω] = ΔV [mV] /0.5C [mA]

Next, a constant current 0.2C charge / discharge cycle was conducted at a high temperature of 60 ° C., followed by a constant current 1C charge / discharge cycle 100. The upper limit of charging was 4.1 V, and the lower limit voltage was 3.0 V.
At this time, the ratio of the discharge capacity Qh (100) at the 100th cycle of 1C charge / discharge at 60 ° C. was calculated as the high-temperature cycle capacity retention ratio P by the following formula, and the high-temperature characteristics of the batteries were compared with this value.
P [%] = {Qh (100) / Qh (1)} × 100

Table 6 shows the low temperature resistance value and the high temperature cycle capacity retention rate of the batteries using the lithium nickel manganese cobalt composite oxide powders produced in Examples 1 to 5 and Comparative Example 3 as the positive electrode materials, respectively. The smaller the resistance value, the better the low temperature load characteristics, and the higher the maintenance ratio, the better the high temperature cycle characteristics. In addition, the low temperature resistance value was set to 400Ω or less, the low temperature resistance value after the high temperature cycle test was set to 500Ω or less, and the high temperature cycle capacity maintenance rate was set to 78% or more as acceptance criteria for the examples.

  From Table 6, it can be seen that according to the lithium nickel manganese cobalt based composite oxide powder for a lithium secondary battery positive electrode material of the present invention, a lithium secondary battery excellent in load characteristics can be realized.

  The use of the lithium secondary battery of the present invention is not particularly limited, and can be used for various known uses. Specific examples include notebook computers, pen input computers, mobile computers, electronic book players, mobile phones, mobile faxes, mobile copy, mobile printers, headphone stereos, video movies, LCD TVs, handy cleaners, portable CDs, minidiscs, and transceivers. Electronic notebooks, calculators, memory cards, portable tape recorders, radios, backup power supplies, motors, lighting equipment, toys, game machines, watches, strobes, cameras, automobile power sources, and the like.

6 is a graph showing a W concentration distribution curve from the particle surface to the depth direction of the lithium nickel manganese cobalt composite oxide produced in Example 3. FIG. It is a graph which shows the B and W density | concentration distribution curve from the particle | grain surface of the lithium nickel manganese cobalt complex oxide manufactured in Example 5 to the depth direction. 2 is a graph showing a pore distribution curve of lithium nickel manganese cobalt composite oxide powder produced in Example 1. FIG. 4 is a graph showing a pore distribution curve of lithium nickel manganese cobalt composite oxide powder produced in Example 2. FIG. 4 is a graph showing a pore distribution curve of lithium nickel manganese cobalt composite oxide powder produced in Example 3. FIG. 6 is a graph showing a pore distribution curve of lithium nickel manganese cobalt composite oxide powder produced in Example 4. FIG. 6 is a graph showing a pore distribution curve of a powder of lithium nickel manganese cobalt composite oxide produced in Example 5. FIG. 6 is a graph showing a pore distribution curve of a powder of lithium nickel manganese cobalt composite oxide produced in Comparative Example 3. FIG. 2 is an SEM image (photograph) (magnification × 10,000) of the lithium nickel manganese cobalt composite oxide produced in Example 1. FIG. 4 is a SEM image (photograph) (magnification × 10,000) of the lithium nickel manganese cobalt composite oxide produced in Example 2. FIG. 4 is a SEM image (photograph) (magnification × 10,000) of the lithium nickel manganese cobalt composite oxide produced in Example 3. FIG. 4 is an SEM image (photograph) (magnification × 10,000) of the lithium nickel manganese cobalt composite oxide produced in Example 4. FIG. 6 is an SEM image (photograph) (magnification × 10,000) of the lithium nickel manganese cobalt composite oxide produced in Example 5. FIG. 4 is an SEM image (photograph) (magnification × 10,000) of the lithium nickel manganese cobalt composite oxide produced in Comparative Example 3. FIG. 2 is a graph showing an XRD pattern of a lithium nickel manganese cobalt composite oxide produced in Example 1. FIG. 3 is a graph showing an XRD pattern of a lithium nickel manganese cobalt composite oxide produced in Example 2. FIG. 4 is a graph showing an XRD pattern of a lithium nickel manganese cobalt composite oxide produced in Example 3. 6 is a graph showing an XRD pattern of a lithium nickel manganese cobalt composite oxide produced in Example 4. 6 is a graph showing an XRD pattern of a lithium nickel manganese cobalt composite oxide produced in Example 5. FIG. 6 is a graph showing an XRD pattern of a lithium nickel manganese cobalt composite oxide produced in Comparative Example 3.

Claims (28)

A lithium transition metal compound powder comprising a crystal structure belonging to a layered structure composed mainly of a lithium transition metal compound having a function capable of inserting and removing lithium ions,
A fine and uniform mixture of a main component raw material of a lithium transition metal compound and a compound (hereinafter referred to as “additive”) composed of a metal element having a valence of 5 or 6 can be fired. And
The primary particles are aggregated to form secondary particles, and the ratio A / B between the median diameter A and the average diameter (average primary particle diameter B) of the secondary particles is in the range of 8 to 100, and CuKα rays are In the powder X-ray diffraction measurement used, 0.01 ≦ FWHM (110) ≦ 0. 0 when the half-value width of the (110) diffraction peak having a diffraction angle 2θ of around 64.5 ° is FWHM (110). A lithium transition metal compound powder for a lithium secondary battery positive electrode material, wherein   2. The lithium transition metal-based compound powder for a lithium secondary battery positive electrode material according to claim 1, wherein the average primary particle diameter B is 0.05 μm or more and 0.9 μm or less.   3. The lithium transition metal compound powder for a lithium secondary battery positive electrode material according to claim 1, wherein primary particle crystals are aggregated to form spherical secondary particles. 4.   Lithium transition metal compound powder comprising a lithium transition metal compound having a function capable of inserting and removing lithium ions as a main component, wherein the main component material and the valence are pentavalent or hexavalent. A fine and uniform mixture of a compound composed of a possible metal element (hereinafter referred to as “additive”) is fired, and the average diameter (average primary particle diameter B) is 0.05 μm or more and 0.00. Primary particle crystals of 9 μm or less aggregate to form spherical secondary particles, and the ratio A / B between the median diameter A and the average primary particle diameter B of the secondary particles is in the range of 8-100. A lithium transition metal compound powder for a positive electrode material for a lithium secondary battery. In powder X-ray diffraction measurement using CuKα rays, the crystal structure is a space group.

5. The structure according to claim 1, wherein the lattice constant is in the range of 2.870Å ≦ a ≦ 2.890２５０ and 14.250 ≦ c ≦ 14.310Å. 2. Lithium transition metal compound powder for lithium secondary battery positive electrode material according to item 1.   In powder X-ray diffraction measurement using CuKα rays, 0.01 ≦ FWHM (110), where FWHM (110) is the half width of the (110) diffraction peak where the diffraction angle 2θ is around 64.5 °. The lithium transition metal-based compound powder for a lithium secondary battery positive electrode material according to claim 4 or 5, wherein ≦ 0.5 is expressed. In powder X-ray diffraction measurement using CuKα rays, a diffraction angle 2θ is present at a diffraction peak near 64 ° (018), a (110) diffraction peak near 64.5 °, and around 68 ° ( 113) When the diffraction peak does not have a diffraction peak derived from a different phase or has a diffraction peak derived from a different phase on a higher angle side than each peak top, the integrated intensity ratio of the different phase peak to the diffraction peak of the original crystal phase The lithium transition metal compound powder for a lithium secondary battery positive electrode material according to any one of claims 1 to 6, wherein each of is in the following range.
0 ≦ I ₀₁₈ ^* / I ₀₁₈ ≦ 0.20
0 ≦ I ₁₁₀ ^* / I ₁₁₀ ≦ 0.25
0 ≦ I ₁₁₃ ^* / I ₁₁₃ ≦ 0.50
(Here, I ₀₁₈ , I ₁₁₀ , and I ₁₁₃ represent the integrated intensities of the diffraction peaks, respectively (018), (110), and (113), and I ₀₁₈ ^* , I ₁₁₀ ^* , and I ₁₁₃ ^* are (018 ), (110), (113) represents the integrated intensity of a diffraction peak derived from a different phase appearing at a higher angle than the peak top of the diffraction peak.)   The median diameter measured after 5 minutes of ultrasonic dispersion (output 30 W, frequency 22.5 kHz) using a laser diffraction / scattering particle size distribution analyzer with a refractive index of 1.24 and a particle size standard as a volume standard. The lithium transition metal compound powder for a lithium secondary battery positive electrode material according to any one of claims 1 to 7, wherein A is 3 µm or more and 20 µm or less. 9. The lithium transition metal compound for a lithium secondary battery positive electrode material according to claim 1, wherein the bulk density is 1.5 g / cm ³ or more and 2.4 g / cm ³ or less. powder. 2. The mercury intrusion curve according to the mercury intrusion method has a mercury intrusion amount of 0.4 cm ³ / g or more and 1.0 cm ³ / g or less when the pressure is increased from 3.86 kPa to 413 MPa. The lithium transition metal compound powder for a lithium secondary battery positive electrode material according to any one of Items 9 to 9.   A sub-peak in which the pore distribution curve by the mercury intrusion method has at least one main peak having a peak top at a pore radius of 300 nm or more and 1500 nm or less, and a peak top at a pore radius of 80 nm or more and less than 300 nm. 11. The lithium transition metal-based compound powder for a lithium secondary battery positive electrode material according to claim 1, comprising: In the pore distribution curve by the mercury intrusion method, the pore volume related to the main peak having a peak top at a pore radius of 300 nm or more and 1500 nm or less is 0.2 cm ³ / g or more and 0.5 cm ³ / g or less, The pore volume according to a sub-peak in which a peak top is present at a pore radius of 80 nm or more and less than 300 nm is 0.01 cm ³ / g or more and 0.2 cm ³ / g or less. The lithium transition metal-based compound powder for a lithium secondary battery positive electrode material according to any one of the above items. 13. The lithium transition metal-based compound powder for a lithium secondary battery positive electrode material according to claim 1, wherein the BET specific surface area is 1 m ² / g or more and 5 m ² / g or less. 14. The lithium according to claim 1, which has a volume resistivity of 1 × 10 ³ Ω · cm or more and 1 × 10 ⁶ Ω · cm or less when consolidated at a pressure of 40 MPa. Lithium transition metal compound powder for secondary battery positive electrode material.   The additive contains an element (hereinafter referred to as “additive element”), the main component is a lithium nickel manganese cobalt composite oxide including a crystal structure belonging to a layered structure, and the additive element is: The lithium transition metal system for a lithium secondary battery positive electrode material according to any one of claims 1 to 14, wherein the lithium transition metal system has a continuous composition gradient structure with a concentration gradient in the depth direction from the particle surface. Compound powder. The lithium transition metal-based compound powder for a lithium secondary battery positive electrode material according to any one of claims 1 to 15, wherein the lithium transition metal-based compound is represented by the following composition formula (I).
LiMO ₂ (I)
(However, in the above formula (I), M is an element composed of Li, Ni and Mn, or Li, Ni, Mn and Co, and the Mn / Ni molar ratio is 0.8 or more and 5 or less, (The Co / (Mn + Ni + Co) molar ratio is 0 or more and 0.35 or less, and the Li molar ratio in M is 0.001 or more and 0.2 or less.)   The lithium transition for a lithium secondary battery positive electrode material according to any one of claims 1 to 16, wherein the mixture is fired at a firing temperature of 900 ° C or higher in an oxygen-containing gas atmosphere. Metal compound powder.   18. The lithium according to claim 1, wherein the C value is 0.005 wt% or more and 0.1 wt% or less when the carbon content is C (wt%). Lithium transition metal compound powder for secondary battery positive electrode material. The lithium transition metal compound for a lithium secondary battery positive electrode material according to any one of claims 16 to 18, wherein M in the composition formula (I) is represented by the following formula (II): powder.
_{M = Li z / (2 +} z) {(Ni (1 + y) / 2 Mn (1-y) / 2) 1-x Co x} 2 / (2 + z) ... (II)
(However, in the above formula (II),
0 ≦ x ≦ 0.1
−0.1 ≦ y ≦ 0.1,
(1-x) (0.05-0.98y) ≤z≤ (1-x) (0.20-0.88y)
It is. )   The lithium according to any one of claims 1 to 19, wherein the additive is an oxide containing at least one element selected from Mo, Nb, W, Ta, and Re. Lithium transition metal compound powder for secondary battery positive electrode material.   The additive contains an element (hereinafter referred to as “additive element”), and the concentration of the additive element is 0.01 mol% or more based on the total molar amount of the constituent metal elements excluding the additive element and Li. The lithium transition metal compound powder for a lithium secondary battery positive electrode material according to any one of claims 1 to 20, wherein the powder is less than 2 mol%.   The additive contains an element (hereinafter referred to as “additive element”), and the atomic ratio of the total of the additive element to the total of Li and the metal elements other than the additive element in the surface part of the primary particles is The lithium transition metal-based compound powder for a lithium secondary battery positive electrode material according to any one of claims 1 to 21, wherein the atomic ratio is 5 times or more of the atomic ratio. The additive contains an element (hereinafter referred to as “additive element”), the atomic ratio R ₀ of the total of the additive element to the total of Li and the metal elements other than the additive element on the outermost surface of the primary particle, The ratio R ₀ / R ₁₀ of the total atomic ratio R ₁₀ of the additive element to the total of Li and a metal element other than the additive element at a depth of 10 nm from the surface is 3 or more. 23. The lithium transition metal compound powder for a lithium secondary battery positive electrode material according to any one of items 1 to 22.   The additive contains an element (hereinafter referred to as “additive element”), and the additive element has a continuous composition gradient structure in which there exists a non-linear concentration gradient in the depth direction from the particle surface. The lithium transition metal-based compound powder for a lithium secondary battery positive electrode material according to any one of claims 1 to 23. The lithium transition metal compound powder for a lithium secondary battery positive electrode material according to any one of claims 1 to 24, wherein the composition of the lithium transition metal compound is represented by the following formula (III).
[L] _3a [Q] _3b [O ₂ ] _6c (III)
(However, in the above formula (III), L is an element containing at least Li, and Q is an element containing at least Ni, Mn and Co, or Li, Ni, Mn and Co,
0.4 ≦ Ni / (Mn + Ni + Co) molar ratio <0.7
0.1 <Mn / (Mn + Ni + Co) molar ratio ≦ 0.4
0.1 ≦ Co / (Mn + Ni + Co) molar ratio ≦ 0.3
And the Li molar ratio in Q is 0 or more and 0.05 or less.
The subscript next to [] represents a site in the crystal structure, the 3a site being the Li site, the 3b site being the transition metal site, and the 6c site being the oxygen site. ) 26. The lithium transition metal-based compound powder for a lithium secondary battery positive electrode material according to claim 25, wherein Q in the formula (III) is represented by the following formula (IV).
_{Q = Li r / (2 +} r) (Ni 1-p-q Mn p Co q) 2 / (2 + r) ... (IV)
(However, in the above formula (IV),
0.1 <p ≦ 0.4
0.15 ≦ q ≦ 0.25
0.001 ≦ r ≦ 0.1
It is. )   A positive electrode active material layer containing the lithium transition metal-based compound powder for a lithium secondary battery positive electrode material according to any one of claims 1 to 26 and a binder, on a current collector, Positive electrode for lithium secondary battery. 28. A lithium secondary battery comprising a negative electrode capable of inserting and extracting lithium, a non-aqueous electrolyte containing a lithium salt, and a positive electrode capable of inserting and extracting lithium, wherein the lithium secondary battery according to claim 27 is used as the positive electrode. A lithium secondary battery using a positive electrode for a battery.

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