JP2012234772A - Lithium-transition metal-based compound powder for lithium secondary battery positive electrode material, and manufacturing method thereof, positive electrode for lithium secondary battery using the same, and lithium secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lithium-transition metal-based compound powder which makes it possible to provide a lithium secondary battery which has a high initial efficiency and a good rate characteristic when used as a lithium secondary battery positive electrode material.SOLUTION: The lithium-transition metal-based compound powder for lithium secondary battery positive electrode material comprises an oxide expressed by the general formula (1). The powder has Li holes and oxygen holes in a crystal structure, and a root mean square (RMS) of surface roughnesses of primary particles of the powder is 1.5 nm or less, which conforms to JIS B 0601:2001. xLiMO(1-x)LiNO(1), where x meets 0<x<1, M is at least one metal element having a mean oxidation number of 4, and N is at least one metal element having a mean oxidation number of 3.

Description

  The present invention relates to a lithium transition metal-based compound powder used as a lithium secondary battery positive electrode material, a method for producing the same, a positive electrode for a lithium secondary battery using the lithium transition metal-based compound powder, and the lithium secondary battery. The present invention relates to a lithium secondary battery including a positive electrode for use.

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.
Currently, as a positive electrode active material for a lithium secondary battery, for example, a lithium transition metal compound is used, and more specifically, a lithium manganese complex oxide or a layered lithium nickel complex oxide having a spinel structure A layered lithium cobalt composite oxide is used. In order to make the battery have a high energy density, a positive electrode active material having a larger amount of electricity stored per unit mass than these positive electrode active materials is required. A so-called solid solution positive electrode active material has been studied as a positive electrode active material having such a possibility. Among them, the solid solution of electrochemically inactive Li ₂ MnO ₃ and electrochemically active layered LiMO ₂ (where M is a transition metal such as Ni, Mn, Co, etc.) is 200 mAh / g. It is expected as a candidate for a high-capacity positive electrode active material that can exhibit a large electric capacity that exceeds that.

However, the solid solution positive electrode active material has a problem that the initial irreversible capacity is large and the rate characteristics (input / output characteristics) are poor. Under these circumstances, Non-Patent Document 1 describes a solid solution positive electrode active material (
After stirring in an aqueous NH ₄ ) ₂ SO ₄ solution, the surface is coated with (NH ₄ ) ₂ SO ₄ by removing water, and heat-treated at 300 ° C. to form Li ₂ SO ₄ on the surface, which is washed with water. It is described that the removal improves the rate characteristics without reducing the primary particle size by forming a spinel-like layer on the surface.

In Non-patent Document 2, the solid solution positive electrode active material is stirred in 0.1M HNO ₃ , filtered, washed with water, and dried at 100 ° C., but the initial irreversible capacity is reduced, but the rate characteristics are processed. It is described that it is inferior compared to before.
Further, in Patent Document 1, after the solid solution cathode active material is washed with water or treated in 0.1M HNO ₃ , it is reduced at 200 ° C. under NH ₃ gas flow, thereby increasing the initial efficiency (the first irreversible capacity is reduced). Decrease).

WO2004 / 097964

Denis Y. W. Yu, Katsunori Yanagida, and Hiroshi Nakamura, Journal of The Electrochemical Society, 157 (2010) A1177-A1182. S. -H. Kang, C.I. S. Johnson, J.M. T.A. Vaughey, K .; Amine, and M.M. M.M. Thackeray, Journal of The Electrochemical Society, 153 (2006) A1186-A1192

  As described above, with the need for higher capacity for batteries in recent years, utilization of a solid solution positive electrode active material that exhibits a high capacity at a low discharge rate is desired. However, rate characteristics with a large initial irreversible capacity are desired. There is a problem of poor input / output characteristics. Therefore, for example, Li vacancies can be obtained without increasing the oxidation number of the transition metal, which is a source of electrostatic repulsion, in the solid solution positive electrode active material material in order to further increase the capacity of the lithium secondary battery, improve the rate characteristics, etc. There is a strong demand for a device to increase the number of lithium ion insertion sites and improve diffusibility by introducing.

However, in Non-Patent Document 1, since Li vacancies and oxygen vacancies are introduced only on the particle surface, the crystal structure of the surface changes to spinel-like and the surface becomes rough. Therefore, it is expected that the lithium transition metal composite oxide is deteriorated, that is, the conduction path is cut off and the crystal structure phase transition easily occurs, and there is a concern that it may adversely affect long-term cycle characteristics.
In Non-Patent Document 2, strong acid treatment causes ion exchange of Li ⁺ and H ⁺ in the Li ₂ MnO ₃ domain and Li ₂ O desorption, and the initial irreversible capacity decreases, but the cycle characteristics and rate characteristics are It is described that it gets worse.

Furthermore, in Patent Document 1, after water washing or strong acid treatment, reduction efficiency at 200 ° C. under NH ₃ gas flow increases initial efficiency (decreases initial irreversible capacity), and discharge capacity at the same rate is Although it is described that they are comparable, the rate characteristics are not described. In the case of washing with water, the ion exchange between Li ⁺ and H ⁺ and the amount of Li ₂ O desorption estimated from the decrease in the charge capacity before the treatment are small. Since the remaining amount of H ⁺ is large, the rate characteristics are not expected to improve.

The present invention has been made in view of the above problems.
That is, the present invention provides a positive electrode material for a lithium secondary battery that can provide a lithium secondary battery with high initial efficiency and excellent rate characteristics, a positive electrode for a lithium secondary battery, and a lithium secondary battery using these. For the purpose.

As a result of intensive studies in view of the above problems, the present inventors have introduced Li vacancies and oxygen vacancies without roughening the surface of the primary particles, and preferably by reducing the remaining hydrogen ion content. The present invention was completed by finding that the initial efficiency of the solid solution positive electrode active material is improved and the rate characteristics are improved.
That is, the gist of the present invention is as follows.
(1) An oxide represented by the general formula (1), which has Li vacancies and oxygen vacancies in the crystal structure, and the root mean square roughness of the primary particle surface according to JIS B 0601: 2001 A lithium transition metal compound powder for a lithium secondary battery positive electrode material, wherein (RMS) is 1.5 nm or less.

xLi ₂ MO _3. (1-x) LiNO ₂ (1)
(Wherein, x is 0 <a number satisfying x <1, M is one or more kinds of metal elements number average oxidation is 4 ^+, N is 1 or more the number average oxidation is 3 ⁺ Metal element)
(2) After the lithium transition metal based compound powder was heat treated at pH ³ 5 in a solvent, 200 ° C.
The lithium transition metal-based compound powder for a lithium secondary battery positive electrode material according to (1), comprising a compound obtained by heat-treating at a temperature of not less than 900 ° C. and not more than 24 hours within 24 hours.
(3) the lithium transition metal based compound powder, after heat treatment at pH ³ 5 in a solvent, 200 ° C.
A lithium transition metal-based compound powder for a lithium secondary battery positive electrode material, comprising a compound obtained by heat treatment at a temperature of not less than 900 ° C. and not more than 24 hours.
(4) The lithium transition metal compound powder for a lithium secondary battery positive electrode material according to any one of (1) to (3), wherein the hydrogen ion content is 1000 wtppm or less. (5) The lithium secondary battery positive electrode material according to any one of (1) to (4), wherein the heat treatment in a solvent is performed in an aqueous solution at a room temperature to 350 ° C. Lithium transition metal compound powder.
(6) The lattice constants of the a-axis and c-axis of the lithium transition metal compound powder obtained in the space group R-3m (166) increase both before and after the heat treatment (1) to (5) The lithium transition metal-based compound powder for a lithium secondary battery positive electrode material according to any one of the above.
(7) A positive electrode active material layer containing the lithium transition metal compound powder for a lithium secondary battery positive electrode material according to any one of (1) to (6) and a binder is formed on a current collector. A positive electrode for a lithium secondary battery, comprising:
(8) A lithium secondary battery comprising a negative electrode capable of inserting and extracting lithium, a nonaqueous electrolyte containing a lithium salt, and a positive electrode capable of inserting and extracting lithium, wherein the lithium according to (7) A lithium secondary battery using a positive electrode for a secondary battery.
(9) The lithium transition metal based compound powder, after heat treatment at pH ³ 5 in a solvent, 200 ° C.
A method for producing a lithium transition metal compound powder for a positive electrode material for a lithium secondary battery, wherein the heat treatment is carried out at a temperature of from 900 ° C. to 900 ° C. within 24 hours.

_{xLi 2 MO 3 · (1-} x) LiNO 2 ··· (1)
(Wherein, x is 0 <a number satisfying x <1, M is one or more kinds of metal elements number average oxidation is 4 ^+, N is 1 or more the number average oxidation is 3 ⁺ Metal element)
(10) The method for producing a lithium transition metal-based compound powder for a lithium secondary battery positive electrode material according to (9), wherein the heat treatment is performed in an aqueous solution at room temperature or higher and 350 ° C. or lower.

  According to the present invention, a high-performance lithium secondary battery having high discharge capacity and initial charge / discharge efficiency and excellent rate characteristics can be stably and efficiently realized.

Hereinafter, the present invention will be described in detail, but the present invention is not limited to the following description, and can be arbitrarily modified and implemented without departing from the gist of the present invention.
[1] Lithium transition metal compound powder for lithium secondary battery cathode material The lithium transition metal compound powder for lithium secondary battery cathode material of the present invention is an oxide represented by the general formula (1). In addition, the crystal structure has Li vacancies and oxygen vacancies, and the root mean square roughness (RMS) of the primary particle surface according to JIS B 0601: 2001 is 1.5 nm.
A lithium transition metal compound powder for a positive electrode material for a lithium secondary battery, characterized by:

_{xLi 2 MO 3 · (1-} x) LiNO 2 ··· (1)
(Wherein, x is 0 <a number satisfying x <1, M is one or more kinds of metal elements number average oxidation is 4 ^+, N is 1 or more the number average oxidation is 3 ⁺ Metal element)
<Lithium transition metal compound>
<Crystal structure>
Among the above-described crystal structures, the lithium transition metal compound powder of the present invention preferably has an olivine structure, a spinel structure, or a layered structure from the viewpoint of lithium ion diffusion. Among these, those having a layered structure or a spinel structure are preferred, and those having a layered structure are particularly preferred from the viewpoint of good solid conductivity and remarkable effects of the present invention.

  Further, foreign elements may be introduced into the lithium transition metal-based compound powder of the present invention. Different elements include B, Na, Mg, Al, K, Ca, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Ru, Rh, Pd, Ag, In, Sn, Sb. Te, Ba, Ta, Mo, W, Re, Os, Ir, Pt, Au, Pb, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu , Bi, N, F, Cl, Br, or I. 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 of the lithium transition metal compound, and may be a single element or compound on the particle surface or grain boundary. May be unevenly distributed.

The lithium transition metal compound having a structure that can be attributed to the layered structure referred to here is generally expressed as LiMeO ₂ (Me is a transition metal), and lithium in which a lithium layer, a transition metal layer, and an oxygen layer are laminated in a uniaxial direction. It has a structure equivalent to a transition metal oxide. As typical LiMeO ₂ , 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 to this, LiMnO ₂ called so-called layered Mn is an orthorhombic layered compound of the space group Pm2m, and Li ₂ MnO ₃ called so-called 213 phase is Li [Li _1/3 Mn _2/3 ] O. ₂ and a monoclinic space group C2 / m structure, but the Li layer and [Li _1/3 M
n _2/3 ] and a layered compound in which an oxygen layer is laminated.

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 explain in detail, the following description will be made assuming that the layered structure is an R (-3) m structure.
In the present invention, it has a layered structure
LiNi _a Mn _(1-a)) O _{2 has} a ratio of (1-3x) (1-y),
The ratio of Li [Li _1/3 Mn _2/3 ] O ₂ is 3x (1-y),
-It is a layered lithium transition metal composite oxide in which the proportion of LiCoO ₂ is assumed to be solid solution at y.

The lithium transition metal-based compound has a basic structure represented as follows.
[Li] ^(3a) [(Li _x Ni _{a (1-3x)} Mn _{(3a-1) x + 1-a} ) _(1-y) Co _y ] ^(3b) O ₂ (II)
Here, (3a) and (3b) represent different metal sites in the layered R (-3) m structure, respectively.
The x value is preferably 0.13 ≦ x ≦ 0.26, and when the Mn / Ni atomic ratio is in a range larger than 1, it was used as a lithium secondary battery designed to be charged at a high charging potential. In some cases, the charge / discharge capacity is improved. This is thought to be because the total amount of Li that can participate in charge / discharge is increased because the ratio of Li existing in the (3b) site also increases as a result of the increase in the Mn / Ni atomic ratio. Further, the y value is preferably 0 ≦ y ≦ 0.30. In consideration of the cost of raw materials, the LiCoO ₂ composition does not necessarily need to be dissolved, but the higher the y value, the better the rate characteristics of the battery. The a value is 0 ≦ a
Although an arbitrary value can be taken in the range of ≦ 1, it is desirable that 0.30 ≦ a ≦ 0.80. When a is less than 0.3, the discharge capacity of LiNi _a Mn _(1-a)) O ₂ decreases, and when a is 0.7 or more, LiNi _a Mn _(1-a)) O ₂ This is because the structural stability is impaired.

In the present invention, Li may be added in excess of z mol with respect to the composition of the formula (II) to be dissolved.
[Li] ^(3a) [Li _{z / (2 + z)} {(Li _x Ni _{a (1-3x)} Mn _{(3a-1) x + 1-a} ) _(1-y) Co _y } _{2 / (2 + z)} ] ^(3b)
O ₂ (I)
(However, 0.13 ≦ x ≦ 0.26, 0 ≦ y ≦ 0.30, 0.30 ≦ a ≦ 0.80, 0.02 (1-y) (1-3x) ≦ z ≦ 0.15 (1-y) (1-3x), and (3a) and (3b) represent different metal sites in the layered R (-3) m structure.)

In this case, in the layered lithium transition metal composite oxide expressed as LiMeO ₂ (Me is a transition metal), z mol of excess Li is dissolved in the transition metal site (3b site).
[Li] ^(3a) [Li _{z / (2 + z)} Me _{2 / (2 + z)} ] ^(3b) O ₂
It is expressed in the same way as that.

In order to obtain x, y, and z in the formula (I), each transition metal and Li are analyzed by an inductively coupled plasma emission spectrometer (ICP-AES) to obtain a ratio of Li / Ni / Mn / Co. It is calculated by the thing.
From a structural point of view, it is considered that both Li related to z and Li related to x are substituted by the same transition metal site. Here, the difference between Li related to x and Li related to z is whether or not the valence of Ni is greater than two (whether or not trivalent Ni is generated). That is, since x is a value linked with the Mn / Ni ratio (Mn rich degree), the Ni valence does not vary only by this x value, and Ni remains divalent. On the other hand, z can be regarded as Li that increases the Ni valence, and z is an index of the Ni valence (the ratio of Ni (III)).

<Root mean square roughness (RMC)>
The lithium transition metal-based compound powder of the present invention is characterized in that the root mean square roughness (RMC) of the primary particle surface according to JIS B 0601: 2001 is 1.5 nm or less. The upper limit of the root mean square roughness (RMC) is preferably 1 nm or less, more preferably 0.9 nm or less, and particularly preferably 0.8 nm or less. It is preferable that the root mean square roughness (RMC) is less than this upper limit because the surface is less damaged. Further, the lower limit is usually 0.1 nm or more, preferably 0.15 nm or more, more preferably 0.2 nm or more, and most preferably 0.3 nm or more. Exceeding this lower limit is preferable because the positive electrode material can be produced economically.

The provisions of JIS B 0601: 2001 are defined by the Japan Industrial Standards Committee.
The lithium transition metal-based compound powder of the present invention preferably has a hydrogen ion content of 1000 wtppm or less. More preferably, it is 900 wtppm or less, Most preferably, it is 850 wtppm or less. As a lower limit, it is 1 wtppm or more normally, Preferably it is 50 wtppm or more, More preferably, it is 100 wtppm or more. If the hydrogen ion content is too high, the diffusion of Li ions in the solid tends to be adversely affected. On the other hand, extremely strictly controlled storage conditions are required to reduce the hydrogen ion content to 1 wtppm or less.

The lithium transition metal-based compound powder of the present invention is preferably a compound obtained by heat treatment in a solvent having a pH of 5 or more, then separating from the solvent and heat-treating at a temperature of 500 ° C. or less for 24 hours. . According to the study by the present inventors, it is possible to efficiently form Li vacancies in the crystal structure without roughening the particle surface by using a neutral to alkaline solution and setting the treatment temperature higher than room temperature. it can. The lower limit of the initial pH of the treatment liquid is usually 5 or more, preferably 6 or more, more preferably 7 or more. Moreover, as an upper limit, it is 14 or less normally, Preferably it is 13 or less, More preferably, it is 11 or less. If the pH is too low, the particle surface tends to be rough, whereas if it is too high, Li vacancies tend not to be formed.

  The lower limit of the treatment temperature in the solvent is usually room temperature or higher, preferably 40 ° C. or higher, more preferably 50 ° C. or higher. Moreover, as an upper limit, it is 350 degrees C or less normally, Preferably it is 250 degrees C or less, More preferably, it is 200 degrees C or less. If the temperature is too low, Li vacancies are difficult to be formed. Conversely, if the temperature is too high, the pressure resistance required for the container becomes too high, which is economically undesirable. The treatment liquid may be an aqueous solution, an organic solvent such as alcohol or hydrocarbon, but is usually preferably an aqueous solution or alcohol. As a method for adjusting the pH, alkali hydroxide, ammonia, ammonium salt or the like can be used. Of these, ammonia water or ammonium salt is preferably used in order to prevent the introduction of different alkali metals or the like into the lithium nickel manganese composite oxide.

  In the lithium transition metal-based compound powder of the present invention, the lattice constants of the a-axis and c-axis of the lithium transition metal-based compound powder obtained in the space group R-3m (166) may increase both before and after the heat treatment. preferable. More specifically, the lattice constant of the a axis is usually 2.84Å or more, preferably 2.85Å or more as a lower limit. Moreover, as an upper limit, it is 2.89 or less normally, Preferably it is 2.88 or less, More preferably, it is 2.87 or less. An a-axis lattice constant in this range is preferable because the balance between structural stability and rate characteristics is excellent. The lower limit of the increase in the a-axis lattice constant before and after heat treatment (Δa) is usually −0.015% or more, preferably 0% or more, more preferably 0.02% or more, and particularly preferably. It is 0.03% or more. Moreover, as an upper limit, it is 0.6% or less normally, Preferably it is 0.5% or less, More preferably, it is 0.4% or less, Most preferably, it is 0.3% or less. If Δa is within this range, it is preferable because the life is deteriorated due to disorder of the crystal structure and the capacity is well balanced.

  Furthermore, the lower limit of the c-axis lattice constant is usually 14 mm or more, preferably 14.1 mm or more, more preferably 14.2 mm or more, and particularly preferably 14.24 mm or more. Moreover, as an upper limit, it is 14.4 or less normally, Preferably it is 14.35 or less, More preferably, it is 14.32 or less, Especially preferably, it is 14.3 or less. A c-axis lattice constant in this range is preferable because the balance between structural stability and rate characteristics is excellent. The lower limit of the increase in the c-axis lattice constant before and after heat treatment (Δc) is usually 0.04% or more, preferably 0.05% or more, more preferably 0.06% or more, particularly preferably. Is 0.07% or more. Moreover, as an upper limit, it is 0.3% or less normally, Preferably it is 0.2% or less, More preferably, it is 0.19% or less. If Δc is within this range, it is preferable because the life is deteriorated due to the disorder of the crystal structure and the capacity is well balanced.

The ratio (Δa / Δc) of the change rate between Δa and Δc is usually −1 or more, preferably −0.8 or more, more preferably 0 or more, and particularly preferably 0.2 or more as a lower limit. Moreover, as an upper limit, it is 3 or less normally, Preferably it is 2 or less. If Δa / Δc is within this range, it is preferable because the diffusibility of Li ions in the solid is easily improved by defects.
<Li vacancies and oxygen vacancies>
The lithium transition metal-based compound powder of the present invention is characterized by having Li vacancies and oxygen vacancies in the crystal structure. Here, to confirm the introduction of Li vacancies and oxygen vacancies, compare the elemental analysis before and after the introduction of Li vacancies and oxygen vacancies into the crystal structure of the lithium transition metal compound. Thus, introduction of Li vacancies and oxygen vacancies can be confirmed by a decrease in the Li amount and the oxygen amount.

<BET specific surface area>
The lithium transition metal-based compound powder of the present invention has a BET specific surface area (SSA) of usually 1 m ² / g or more, preferably 1.2 m ² / g or more, more preferably 1.5 m ² / g or more, most preferably. Is 1.8 m ² / g or more, usually 20 m ² / g or less, preferably 16 m ² / g or less, more preferably 13 m ² / g or less, and most preferably 10 m ² / g or less. If the BET specific surface area is smaller than this range, the battery performance is likely to deteriorate, and if it is large, an undesirable side reaction in the battery may be promoted.

  The BET specific surface area can be measured by a known BET type powder specific surface area measuring device. In the present invention, measurement can be performed by a BET 5-point method using a continuous flow method using a Sysmex NOVA1200 fully automatic powder specific surface area measuring apparatus and using nitrogen as an adsorption gas. Specifically, a powder sample is heated and degassed with a mixed gas at a temperature of 150 ° C., then cooled to liquid nitrogen temperature to adsorb the gas, and then heated to room temperature to adsorb the adsorbed nitrogen gas. By desorbing and quantifying the amount, the specific surface area of the sample can be calculated.

<The bulk density>
The bulk density of the lithium transition metal compound powder of the present invention is usually 0.3 g / cc or more, preferably 0.4 g / cc or more, more preferably 0.5 g / cc or more, most preferably 0.7 g / cc or more. It is. Below this lower limit, powder filling properties and electrode preparation are adversely affected, and a positive electrode using this as an active material is not preferable because the capacity density per unit volume becomes too small. Further, the upper limit of the bulk density is usually 3 g / cc or less, preferably 2.8 g / cc or less, more preferably 2.6 g / cc or less. While it is preferable for the bulk density to exceed this upper limit, it is preferable for improving powder filling properties and electrode density. On the other hand, the specific surface area may become too low, which is not preferable because battery performance deteriorates.

In the present invention, the bulk density is 5 to 10 g of lithium transition metal compound powder in a 10 ml glass measuring cylinder and tapped 200 times with a stroke of about 20 mm (tap density) g / cc was determined.
<Average primary particle size>
The average primary particle size of the lithium transition metal compound powder of the present invention is usually 0.01 μm or more, preferably 0.03 μm or more, more preferably 0.05 μm or more, and usually 1 μm or less, preferably 0.5 μm or less. More preferably, it is 0.3 μm or less, and most preferably 0.2 μm or less. Since the present invention is intended for a positive electrode having a relatively small Li diffusion coefficient in a solid, exceeding the above upper limit is liable to cause problems such as an increase in Li diffusion resistance and a decrease in charge / discharge characteristics. On the other hand, when the above lower limit is exceeded, the surface area becomes too large, and an undesirable reaction in the battery may be promoted.

In addition, the average particle diameter of the primary particle in this invention is an average diameter observed with the scanning electron microscope (SEM), and it is about 10-30 primary using the SEM image of 30,000-100,000 times. It can obtain | require as an average value of the particle diameter of particle | grains.
<Median diameter of secondary particles and 90% cumulative diameter (D90)>
The median diameter of the secondary particles of the lithium transition metal compound powder of the present invention is usually 1 μm or more, preferably 2 μm or more, more preferably 3 μm or more, most preferably 5 μm or more, usually 20 μm or less, preferably 18 μm or less, more Preferably it is 16 micrometers or less, Most preferably, it is 15 micrometers or less. If the lower limit is exceeded, the secondary particles themselves become finer, and therefore there is a possibility that the effect of reducing the conductive material content according to the present invention may not be obtained effectively, and if the upper limit is exceeded, the particle strength decreases. Since the generation amount of crushed particles during kneading increases, it is not preferable.

The 90% cumulative diameter (D90) of the secondary particles of the lithium transition metal-based compound powder of the present invention is usually 30 μm or less, preferably 26 μm or less, more preferably 23 μm or less, most preferably 20 μm or less, and usually 5 μm or more. , Preferably 8 μm or more, more preferably 12 μm or more, and most preferably 15 μm or more. If the above upper limit is exceeded, battery performance may be deteriorated, and there may be a problem in applicability at the time of forming the positive electrode active material layer, and if it is below the lower limit, a high bulk density product may not be obtained.

The median diameter and the 90% cumulative diameter (D90) as the average particle diameter can be measured by setting a refractive index of 1.24 using a known laser diffraction / scattering particle size distribution measuring apparatus and using the particle diameter reference as a volume reference. As a dispersion medium used in the measurement, a 0.1% by weight sodium hexametaphosphate aqueous solution can be used.
<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. The lithium transition metal-based compound that is the subject of the present invention is considered to have a relatively slow diffusion of Li ions in the solid, and therefore has a large irreversible capacity and poor rate characteristics. The following two methods can be considered as means for improving the properties of the material.

1) A method of reducing the primary crystal diameter to shorten the diffusion distance in the solid 2) A method of improving the Li ion diffusion coefficient in the solid The present invention mainly relates to the second. More specifically, both lithium ion vacancies and oxygen ion vacancies are introduced into the solid to secure Li vacancies that promote lithium ion migration and introduce oxygen vacancies to widen the diffusion path. The lattice constant is increased.

[Method for producing lithium transition metal compound for positive electrode material of lithium secondary battery]
The method for producing a lithium transition metal compound for a lithium secondary battery positive electrode material of the present invention is not limited to a specific production method. For example, a nickel compound, a manganese compound, and a cobalt compound are dispersed in a liquid medium. The slurry may be spray-dried and / or pyrolyzed and then mixed with a lithium compound, and the mixture may be fired to produce or disperse or dissolve the nickel compound, manganese compound, cobalt compound, and lithium compound. The slurry or solution may be spray dried or spray pyrolyzed and fired as necessary.

The method for producing a lithium transition metal compound powder for a lithium secondary battery positive electrode material of the present invention will be described in detail below.
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 , 2Ni _{(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, nickel acetate, fatty acid nickel, nickel halide and the like Can be mentioned. Among these, Ni (NO ₃ ) ₂ .6H ₂ O, NiSO ₄ .6H ₂ O, and nickel acetate, which are highly soluble in water, are preferable. Ni (NO ₃ ) ₂ .6H ₂ O and nickel acetate are particularly preferred from the viewpoint that the primary particle size can be reduced in spray pyrolysis. 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, Mn (NO ₃ ) ₂ , MnSO ₄ , manganese acetate, manganese dicarboxylate, manganese citrate and manganese fatty acid, which have high solubility in water, are preferable. Mn (NO ₃ ) ₂ and manganese acetate are particularly preferable from the viewpoint that the primary particle size can be reduced in spray pyrolysis. 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, and the like. Among these, Co (NO3) ₂ · 6H ₂ O, Co (OCOCH ₃ ) ₂ · 4H ₂ O, CoCl ₂ , and Co (SO ₄ ) ₂ · 7H ₂ O, which are highly soluble in water, are preferable. From the viewpoint that the primary particle size can be reduced in spray pyrolysis, Co (NO ₃ ) ₂ .6H ₂ O and Co (OCOCH ₃ ) ₂ .4H ₂ O are particularly preferable. These cobalt compounds may be used individually by 1 type, and may use 2 or more types together.

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, alkyl lithium, etc. are mentioned. These lithium compounds may be used individually by 1 type, and may use 2 or more types together.

The method for mixing the raw materials is not particularly limited, and may be wet or dry. As a result, it is desirable that the mixed salt is completely dissolved. As the dispersion medium, either an organic solvent or water can be used, but it is preferable to use water. The solution in which the raw material salt is dissolved may be directly subjected to a drying and / or pyrolysis process, or converted to hydroxide, carbonate, etc. by a coprecipitation method in order to avoid the problem of exhaust gas treatment in the subsequent process. The mixed solution mixed with the Li raw material by washing with water or the like may be subjected to a drying and / or pyrolysis step.

The mixed solution is then subjected to a drying and / or pyrolysis step. The drying method is not particularly limited, but the spray pyrolysis method is preferable from the viewpoint of making primary particles fine and forming substantially spherical secondary particles efficiently.
The mixed powder thus obtained is then fired. 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 too much. Too much. The firing temperature is usually 800 ° C. or higher, preferably 900 ° C. or higher, more preferably 950 ° C. or higher, usually 1100 ° C. or lower, preferably 1075 ° C. or lower, more preferably 1050 ° C. or lower.

<Processing method>
As a method of introducing Li vacancies and oxygen vacancies in the crystal structure of the lithium nickel manganese based composite oxide powder, Li vacancies can be introduced without increasing the oxidation number of the transition metal, and Any method that does not roughen the particle surface may be used. More specifically, it is exemplified as follows.

First, a method for forming Li vacancies will be described. Usually, when lithium nickel manganese composite oxide powder is dispersed in pure water at room temperature, the aqueous solution exhibits alkalinity. From this, it is presumed that lithium ions on the surface of the lithium nickel manganese composite oxide powder are partially substituted with hydrogen ions. However, since the exchange amount is small at room temperature and is limited to the particle surface, the influence on the battery performance is very small. By making the dispersion acidic, more lithium ions can be exchanged or desorbed as Li ₂ O. On the other hand, it is known that the cycle life may be reduced or the rate characteristics may be reduced due to damage to the particle surface under acidic conditions. According to the study by the present inventors, it is possible to efficiently form Li vacancies in the crystal structure without roughening the particle surface by using a neutral to alkaline solution and setting the treatment temperature higher than room temperature. it can. The lower limit of the initial pH of the treatment liquid is usually 5 or more, preferably 6 or more, more preferably 7 or more. Also,
As an upper limit, it is 14 or less normally, Preferably it is 13 or less, More preferably, it is 11 or less. If the pH is too low, the particle surface tends to be rough, whereas if it is too high, Li vacancies tend not to be formed.

  The lower limit of the treatment temperature in the solvent is usually room temperature or higher, preferably 40 ° C. or higher, more preferably 50 ° C. or higher. Moreover, as an upper limit, it is 350 degrees C or less normally, Preferably it is 250 degrees C or less, More preferably, it is 200 degrees C or less. If the temperature is too low, Li vacancies are difficult to be formed. Conversely, if the temperature is too high, the pressure resistance required for the container becomes too high, which is economically undesirable. The treatment liquid may be an aqueous solution, an organic solvent such as alcohol or hydrocarbon, but is usually preferably an aqueous solution or alcohol. As a method for adjusting the pH, alkali hydroxide, ammonia, ammonium salt or the like can be used. Of these, ammonia water or ammonium salt is preferably used in order to prevent the introduction of different alkali metals or the like into the lithium nickel manganese composite oxide.

Next, a method for forming oxygen vacancies will be described. Some of the oxygen vacancies are formed by the elimination of Li ₂ O from the lithium nickel manganese composite oxide. In addition, it is considered that there are oxygen vacancies generated by Li ions in the crystal structure being exchanged with hydrogen ions and desorbed as H ₂ O by heat treatment. In other words, hydrogen ions remain in the crystal structure even after drying the solvent by exchanging Li ions / hydrogen ions in the solvent, but after removing the solvent, the hydrogen ions are converted to H ₂ O by heat treatment at 200 ° C. or higher. As a result of desorption, oxygen vacancies are formed in the crystal structure. The lower limit of the heat treatment temperature after removal of the solvent is usually 200 ° C. or higher, preferably 300 ° C. or higher, more preferably 350 ° C. or higher. As an upper limit, it is 900 degrees C or less normally, 600 degrees C or less normally, More preferably, it is 500 degrees C or less. If the heat treatment temperature is too low, the amount of remaining hydrogen ions is too large, and the rate characteristics tend to be lowered. On the other hand, if it is too high, Li vacancies and oxygen vacancies cannot exist stably, an impurity phase such as a spinel phase is generated, and battery characteristics tend to deteriorate.

By the above method, Li vacancies and oxygen vacancies can be efficiently produced without generating an impurity phase such as a spinel phase confirmed by Raman spectroscopy, XRD, or the like in both the bulk and the surface while maintaining the crystal structure. Can be formed.
The hydrogen ion contained in the lithium nickel manganese composite oxide of the present invention is usually 1000 ppm or less, more preferably 900 wtppm or less, and particularly preferably 850 wtppm or less. As a lower limit, it is 1 wtppm or more normally, Preferably it is 50 wtppm or more, More preferably, it is 100 wtppm or more. If the hydrogen ion content is too high, the diffusion of Li ions in the solid tends to be adversely affected. On the other hand, extremely strictly controlled storage conditions are required to reduce the hydrogen ion content to 1 wtppm or less.

[Current collector]
As the current collector, for example, a metal cylinder, a metal coil, a metal plate, a metal foil film, a carbon plate, a carbon thin film, a carbon cylinder, or the like is used. Among these, a metal foil film is particularly preferable because it is currently used in industrialized products. The metal thin film may be used in a suitable mesh shape.
The thickness of the metal foil film is not particularly limited, but is usually 1 μm or more, preferably 5 μm or more, more preferably 10 μm or more, and usually 100 μm or less, preferably 50 μm or less, more preferably 20 μm or less. In the case of a metal foil film thinner than the above range, the strength required as a current collector may be insufficient.

Specific examples of the metal used for the current collector include copper, nickel, stainless steel, iron, titanium, aluminum, and an aluminum alloy.
[Physical properties]
<Filling density>
The packing density of the positive electrode is not particularly limited, but is usually 0.1 g / cm ³ or more, preferably 0.5 g / cm ³ or more, and usually 5.0 g / cm ³ or less, preferably 4.0 g / cm ³ or less. is there. If the packing density of the positive electrode is below this range, it may be difficult to obtain a high-capacity battery. On the other hand, if it exceeds this range, the amount of pores in the positive electrode may decrease, and it may be difficult to obtain favorable battery characteristics. As the packing density of the positive electrode, a value obtained by dividing the weight of the positive electrode excluding the current collector by the positive electrode area and the positive electrode thickness is used.

<Porosity>
The porosity of the positive electrode is not particularly limited, but is usually 10% or more, preferably 20% or more, and usually 50% or less, preferably 40% or less. When the porosity of the positive electrode is lower than this range, there are few pores in the negative electrode, and the electrolyte does not easily penetrate, and it may be difficult to obtain preferable battery characteristics. On the other hand, if this range is exceeded, there may be many pores in the positive electrode and the positive electrode strength becomes too weak, making it difficult to obtain favorable battery characteristics. As the porosity of the positive electrode, a percentage obtained by dividing the total pore volume obtained by measuring the pore distribution with a mercury porosimeter of the positive electrode by the apparent volume of the positive electrode active material layer excluding the current collector is used.

<Conductive agent>
The positive electrode active material layer may include a conductive agent. The conductive agent may be any electron conductive material that does not cause a chemical change at the charge / discharge potential of the positive electrode active material to be used. For example, carbon blacks such as acetylene black, ketjen black, channel black, furnace black, lamp black and thermal black, carbon fibers, vapor grown carbon fibers (VGCF), conductive fibers such as metal fibers, fluorine Metal powders such as carbonized carbon and copper can be contained alone or as a mixture thereof. Of these conductive agents, acetylene black and VGCF are particularly preferable. These may be used individually by 1 type and may be used in combination of 2 or more type. Although the addition amount of a electrically conductive agent is not specifically limited, 1-30 mass% is preferable with respect to a negative electrode active material, and 1-15 mass% is especially preferable.

<Binder>
As the binder, a polymer that is stable against a liquid solvent described later is preferable. For example, resin polymers such as polyethylene, polypropylene, polyethylene terephthalate, aromatic polyamide, cellulose, rubbery polymers such as styrene / butadiene rubber, isoprene rubber, butadiene rubber or ethylene / propylene rubber, styrene / butadiene / styrene block Polymers, hydrogenated products thereof, styrene / ethylene / butadiene / styrene copolymers, styrene / isoprene / styrene block copolymers and thermoplastic elastomeric polymers such as hydrogenated products, syndiotactic 1,2-polybutadiene , Ethylene / vinyl acetate copolymer, or soft resinous polymer such as propylene / α-olefin (carbon number 2 to 12) copolymer, polyvinylidene fluoride, polytetrafluoroethylene, or polytetrafluoroethylene / ethylene The fluoropolymer of the polymer such as, a polymer composition or the like having an ionic conductivity of alkali metal ions (especially lithium ions) can be mentioned. These may be used individually by 1 type and may be used in combination of 2 or more type.

  Examples of the polymer composition having ion conductivity include polyether polymer compounds such as polyethylene oxide and polypropylene oxide, crosslinked polymers of polyether compounds, polyepichlorohydrin, polyphosphazene, polysiloxane, and polyvinylpyrrolidone. , A polymer in which a lithium salt or an alkali metal salt mainly composed of lithium is combined with a polymer compound such as polyvinylidene carbonate or polyacrylonitrile, or a high dielectric such as propylene carbonate, ethylene carbonate, or γ-butyrolactone. A polymer in which an organic compound having a rate or an ion-dipole interaction force is blended can be used.

  Specifically, resin polymers such as polyethylene, polypropylene, polyethylene terephthalate, aromatic polyamide, or cellulose and derivatives thereof (for example, carboxymethylcellulose), styrene / butadiene rubber, isoprene rubber, butadiene rubber, or ethylene / propylene are usually used. Rubber-like polymers such as rubber, fluoropolymers such as polyvinylidene fluoride, polytetrafluoroethylene, or polytetrafluoroethylene / ethylene copolymers, polyether polymer compounds such as polyethylene oxide and polypropylene oxide, polyethers Examples include crosslinked polymers of the compound, preferably polyethylene, polypropylene, styrene / butadiene rubber, polyvinylidene fluoride, polytetrafluoroethylene, or polyethylene oxide. Is, more preferably, polyethylene, styrene-butadiene, polyvinylidene fluoride, or polytetrafluoroethylene. These are currently used industrially and are suitable because they are easy to handle.

The structure of this positive electrode is the current collector substrate in which the lithium transition metal compound of the present invention, the lithium transition metal compound A and / or the conductive agent, and the slurry in which the binder is dispersed in the dispersion are used. It is manufactured by a thin coating and drying process, followed by a pressing process for compacting to a predetermined thickness and density.
A water-based solvent or an organic solvent is used as a dispersion medium for preparing a positive electrode active material slurry when a positive electrode active material, a conductive agent and a binder used as necessary are mixed and applied onto a current collector. As the aqueous solvent, water is usually used, and additives such as alcohols such as ethanol and cyclic amides such as N-methylpyrrolidone may be added to water up to about 30% by mass or less. it can.

  As the organic solvent, usually, cyclic amides such as N-methylpyrrolidone, linear amides such as N, N-dimethylformamide and N, N-dimethylacetamide, and aromatic carbonization such as anisole, toluene and xylene Examples thereof include alcohols such as hydrogens, butanol and cyclohexanol, among which cyclic amides such as N-methylpyrrolidone, linear amides such as N, N-dimethylformamide and N, N-dimethylacetamide are preferable. .

  A positive electrode active material, a binder, and a conductive agent blended as necessary are mixed with these solvents to prepare a positive electrode active material slurry, and this is applied to the positive electrode current collector substrate to a predetermined thickness. Thus, the positive electrode active material layer is formed, and the upper limit of the concentration of the positive electrode active material in this positive electrode active material slurry is usually 70% by mass or less, preferably 55% by mass or less, and the lower limit is usually 30% by mass or more. , Preferably it is 40 mass% or more. If the concentration of the positive electrode active material exceeds this upper limit, the positive electrode active material in the positive electrode active material slurry tends to aggregate, and if it falls below the lower limit, the positive electrode active material tends to settle during storage of the positive electrode active material slurry.

Further, the upper limit of the concentration of the binder in the positive electrode active material slurry is usually 30% by mass or less, preferably 10% by mass or less, and the lower limit is usually 0.1% by mass or more, preferably 0.5% or more. . When the concentration of the binder exceeds the upper limit, the internal resistance of the positive electrode obtained is increased, and when the concentration is lower than the lower limit, the binding property of the positive electrode active material layer is deteriorated.
[3] Nonaqueous electrolyte secondary battery The nonaqueous electrolyte secondary battery of the present invention is a positive electrode and a negative electrode capable of occluding and releasing lithium ions, and a nonaqueous electrolyte secondary battery including an electrolyte. A transition metal compound is used.

The selection of members other than the positive electrode necessary for the battery configuration such as the negative electrode and the electrolyte constituting the nonaqueous electrolyte secondary battery of the present invention is not particularly limited. In the following, materials of members other than the positive electrode constituting the non-aqueous electrolyte secondary battery when the lithium transition metal compound of the present invention is used as the positive electrode will be exemplified, but the materials that can be used are limited to these specific examples. Is not to be done.
[Negative electrode]
The negative electrode is formed by forming an active material layer containing a negative electrode active material and an organic substance (binder) having a binding and thickening effect on a current collector substrate. Usually, the negative electrode active material and the binder are used. The slurry is dispersed in water or an organic solvent, and is applied by a thin coating and drying process on a current collector substrate, followed by a pressing process for compacting to a predetermined thickness and density.

<Negative electrode active material>
The negative electrode active material is not particularly limited as long as it has a function capable of inserting and extracting lithium. For example, lithium transition metal composite oxide materials such as lithium cobalt oxide, lithium nickel oxide, and lithium manganese oxide Transition metal oxide materials such as manganese dioxide; carbonaceous materials such as graphite fluoride can be used. Specifically, LiFeO ₂ , LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ and their non-stoichiometric compounds, MnO ₂ , TiS ₂ , FeS ₂ , Nb ₃ S ₄ , Mo ₃ S ₄ , CoS ₂ , V ₂ O ₅ , P ₂ O ₅ , CrO ₃ , V ₃ O ₃ , TeO ₂ , GeO ₂ , LiFePO ₄ , LiMnPO ₄ , LiNi _0.5 Mn _1.5 O _4, or the like can be used. These may be used individually by 1 type and may be used in combination of 2 or more type.

<Conductive agent>
A negative electrode conductive agent can be used for the negative electrode active material layer. The negative electrode conductive agent may be any electron conductive material that does not cause a chemical change at the charge / discharge potential of the negative electrode active material to be used. For example, graphite such as natural graphite (flaky graphite, etc.), artificial graphite, etc .; carbon blacks such as acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black; carbon fiber, metal fiber, etc. Conductive fibers of: Carbon fluorides; Metal powders such as aluminum; Conductive whiskers such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Organic conductive materials such as polyphenylene derivatives; Etc. can be included alone or as a mixture thereof. Among these conductive agents, artificial graphite, acetylene black and the like are particularly preferable. These may be used individually by 1 type and may be used in combination of 2 or more type.

Although the addition amount of a electrically conductive agent is not specifically limited, 1-50 mass% is preferable with respect to a negative electrode active material, and 1-30 mass% is especially preferable. In the case of carbon or graphite, 2 to 15% by mass is particularly preferable.
<Binder>
There is no restriction | limiting in particular as a binder used for formation of a negative electrode active material layer, Any of a thermoplastic resin and a thermosetting resin may be sufficient. For example, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), styrene butadiene rubber, tetrafluoroethylene-hexafluoroethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), Tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer (ETFE resin) , Polychlorotrifluoroethylene (PCTFE), vinylidene fluoride-pentafluoropropylene copolymer, propylene-tetrafluoroethylene copolymer, ethylene-chlorotrif Oroethylene copolymer (ECTFE), vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, vinylidene fluoride-perfluoromethyl vinyl ether-tetrafluoroethylene copolymer, ethylene-acrylic acid copolymer or (Na ⁺ ) ion crosslinked product, ethylene-methacrylic acid copolymer or (Na ⁺ ) ion crosslinked product of the material, ethylene-methyl acrylate copolymer, or (Na ⁺ ) ion crosslinked product of the material, ethylene-methacrylic acid Examples thereof include an acid methyl copolymer or a (Na ⁺ ) ion-crosslinked product of the above materials, and these materials can be used alone or as a mixture. Among these materials, more preferable materials are polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE).

<Other additives>
In addition to the conductive agent described above, the negative electrode active material layer may further contain a filler, a dispersant, an ionic conductor, a pressure enhancer, and other various additives. Any filler can be used as long as it is a fibrous material that does not cause a chemical change in the constructed battery. Usually, olefin polymers such as polypropylene and polyethylene, and fibers such as glass and carbon are used. Although the addition amount of a filler is not specifically limited, 0-30 mass% is preferable as content in an active material layer.

<Solvent>
For the preparation of the negative electrode active material slurry, an aqueous solvent or an organic solvent is used as a dispersion medium. As the aqueous solvent, water is usually used, and additives such as alcohols such as ethanol and cyclic amides such as N-methylpyrrolidone may be added to water up to about 30% by mass or less. it can. As the organic solvent, usually, cyclic amides such as N-methylpyrrolidone, linear amides such as N, N-dimethylformamide and N, N-dimethylacetamide, and aromatic carbonization such as anisole, toluene and xylene Examples thereof include alcohols such as hydrogens, butanol and cyclohexanol, among which cyclic amides such as N-methylpyrrolidone, linear amides such as N, N-dimethylformamide and N, N-dimethylacetamide are preferable. .

A negative electrode active material, a binder as a binder, an organic substance having a thickening effect, a negative electrode conductive agent blended as necessary, and other fillers are mixed in these solvents to prepare a negative electrode active material slurry, The negative electrode active material layer is formed by applying this to the negative electrode current collector substrate so as to have a predetermined thickness.
The upper limit of the concentration of the negative electrode active material in the negative electrode active material slurry is usually 70% by mass or less, preferably 55% by mass or less, and the lower limit is usually 30% by mass or more, preferably 40% by mass or more. When the concentration of the negative electrode active material exceeds this upper limit, the negative electrode active material in the negative electrode active material slurry tends to aggregate, and when the concentration is lower than the lower limit, the negative electrode active material tends to settle during storage of the negative electrode active material slurry.

The upper limit of the binder concentration in the negative electrode active material slurry is usually 30% by mass or less, preferably 10% by mass or less, and the lower limit is usually 0.1% by mass or more, preferably 0.5% or more. . When the concentration of the binder exceeds the upper limit, the internal resistance of the negative electrode obtained increases, and when the concentration is lower than the lower limit, the binding property of the negative electrode active material layer may be inferior.
<Current collector>
As the negative electrode current collector, for example, a valve metal or an alloy thereof that forms a passive film on the surface by anodic oxidation in an electrolytic solution is preferably used. Examples of the valve metal include metals belonging to Groups 4, 5, and 13 of the periodic table and alloys thereof. Specifically, Al, Ti, Zr, Hf, Nb, Ta and alloys containing these metals can be exemplified, and Al, Ti, Ta and alloys containing these metals can be preferably used. . In particular, Al and its alloys are desirable because of their light weight and high energy density. The thickness of the positive electrode current collector is not particularly limited, but is usually about 1 to 50 μm.

[Electrolytes]
Any electrolyte such as an electrolytic solution or a solid electrolyte can be used as the electrolyte. Here, the electrolyte refers to all ionic conductors, and both the electrolytic solution and the solid electrolyte are included in the electrolyte.
As the electrolytic solution, for example, a solution obtained by dissolving a solute in a non-aqueous solvent can be used. As the solute, an alkali metal salt, a quaternary ammonium salt, or the like can be used. Specifically, LiClO ₄ , LiPF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (CF ₃ CF ₂ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ), LiC (CF ₃ SO ₂ ) _{3 and the} like are preferably used. One kind of these solutes may be selected and used, or two or more kinds may be mixed and used. The content of these solutes in the electrolytic solution is preferably 0.2 mol / L or more, particularly 0.5 mol / L or more, and 2 mol / L or less, particularly 1.5 mol / L or less.

  Examples of the non-aqueous solvent include cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate and vinylene carbonate, cyclic ester compounds such as γ-butyrolactone; chain ethers such as 1,2-dimethoxyethane; crown ethers, 2- Cyclic ethers such as methyltetrahydrofuran, 1,2-dimethyltetrahydrofuran, 1,3-dioxolane, and tetrahydrofuran; chain carbonates such as diethyl carbonate, ethyl methyl carbonate, and dimethyl carbonate can be used. Among these, a nonaqueous solvent containing a cyclic carbonate and a chain carbonate is preferable.

One type of these solvents may be selected and used, or two or more types may be mixed and used.
The nonaqueous electrolytic solution according to the present invention may contain various auxiliary agents such as a cyclic carbonate having an unsaturated bond in the molecule, a conventionally known overcharge inhibitor, a deoxidizer, and a dehydrator.
Examples of the cyclic carbonate having an unsaturated bond in the molecule include vinylene carbonate compounds, vinyl ethylene carbonate compounds, methylene ethylene carbonate compounds, and the like.

Examples of the vinylene carbonate compounds include vinylene carbonate, methyl vinylene carbonate, ethyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, 4,5-diethyl vinylene carbonate, fluoro vinylene carbonate, trifluoromethyl vinylene carbonate, and the like.
Examples of the vinyl ethylene carbonate compound include vinyl ethylene carbonate, 4-methyl-4-vinyl ethylene carbonate, 4-ethyl-4-vinyl ethylene carbonate, 4-n-propyl-4-vinyl ethylene carbonate, 5-methyl- Examples include 4-vinylethylene carbonate, 4,4-divinylethylene carbonate, 4,5-divinylethylene carbonate, and the like.

Examples of the methylene ethylene carbonate compound include methylene ethylene carbonate, 4,4-dimethyl-5-methylene ethylene carbonate, 4,4-diethyl-5-methylene ethylene carbonate, and the like.
Of these, vinylene carbonate and vinyl ethylene carbonate are preferable, and vinylene carbonate is particularly preferable.

These may be used individually by 1 type, or may use 2 or more types together.
When the non-aqueous electrolyte contains a cyclic carbonate compound having an unsaturated bond in the molecule, the proportion in the non-aqueous electrolyte is usually 0.01% by mass or more, preferably 0.1% by mass or more, particularly Preferably it is 0.3 mass% or more, Most preferably, it is 0.5 mass% or more, Usually 8 mass% or less, Preferably it is 4 mass% or less, Most preferably, it is 3 mass% or less.

  By including in the electrolyte a cyclic carbonate having an unsaturated bond in the molecule, the cycle characteristics of the battery can be improved. Although the reason is not clear, it is presumed that a stable protective film can be formed on the surface of the negative electrode. However, when the content is small, this property is not sufficiently improved. However, if the content is too large, the gas generation amount tends to increase during high-temperature storage, so the content in the electrolyte is preferably in the above range.

  Examples of the overcharge inhibitor include aromatic compounds such as biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, and dibenzofuran; 2-fluoro Partially fluorinated products of the above aromatic compounds such as biphenyl, o-cyclohexylfluorobenzene, p-cyclohexylfluorobenzene; fluorine-containing compounds such as 2,4-difluoroanisole and 2,5-difluoroanisole; Anisole compounds and the like can be mentioned.

These may be used alone or in combination of two or more.
The ratio of the overcharge inhibitor in the non-aqueous electrolyte is usually 0.1 to 5% by mass. By containing an overcharge preventing agent, rupture / ignition of the battery can be suppressed during overcharge or the like.
Examples of other auxiliaries include carbonate compounds such as fluoroethylene carbonate, trifluoropropylene carbonate, phenylethylene carbonate, erythritan carbonate, spiro-bis-dimethylene carbonate, methoxyethyl-methyl carbonate; succinic anhydride, anhydrous glutar Carboxylic acid anhydrides such as acid, maleic anhydride, citraconic anhydride, glutaconic anhydride, itaconic anhydride, diglycolic anhydride, cyclohexanedicarboxylic anhydride, cyclopentanetetracarboxylic dianhydride, phenylsuccinic anhydride; Ethylene sulfite, 1,3-propane sultone, 1,4-butane sultone, methyl methanesulfonate, busulfan, sulfolane, sulfolene, dimethyl sulfone, tetramethylthiuram monosulfide Sulfur-containing compounds such as N, N-dimethylmethanesulfonamide and N, N-diethylmethanesulfonamide; 1-methyl-2-pyrrolidinone, 1-methyl-2-piperidone, 3-methyl-2-oxazolidinone, 1,3 -Nitrogen-containing compounds such as dimethyl-2-imidazolidinone and N-methylsuccinimide; hydrocarbon compounds such as heptane, octane and cycloheptane; fluorine-containing compounds such as fluorobenzene, difluorobenzene, hexafluorobenzene and benzotrifluoride An aromatic compound etc. are mentioned.

These may be used alone or in combination of two or more.
The ratio of these auxiliaries in the nonaqueous electrolytic solution is usually 0.1 to 5% by mass. By containing these auxiliaries, capacity maintenance characteristics and cycle characteristics after high-temperature storage can be improved.
Further, the non-aqueous electrolyte solution may include an organic polymer compound in the electrolyte solution, and may be a solid electrolyte such as a gel, rubber, or solid sheet. In this case, specific examples of the organic polymer compound include polyether polymer compounds such as polyethylene oxide and polypropylene oxide; crosslinked polymers of polyether polymer compounds; vinyl alcohol polymers such as polyvinyl alcohol and polyvinyl butyral. Compound: insolubilized product of vinyl alcohol polymer compound; polyepichlorohydrin; polyphosphazene; polysiloxane; vinyl polymer compound such as polyvinylpyrrolidone, polyvinylidene carbonate, polyacrylonitrile; poly (ω-methoxyoligooxyethylene methacrylate), Examples thereof include polymer copolymers such as poly (ω-methoxyoligooxyethylene methacrylate-co-methyl methacrylate).

[Other components]
In addition to the electrolyte, the negative electrode, and the positive electrode, an outer can, a separator, a gasket, a sealing plate, a cell case, and the like can be used for the non-aqueous electrolyte secondary battery as necessary.
The material and shape of the separator are not particularly limited. The separator is separated so that the positive electrode and the negative electrode do not come into physical contact, and preferably has high ion permeability and low electrical resistance. The separator is preferably selected from materials that are stable with respect to the electrolyte and excellent in liquid retention. Specific examples include porous sheets or nonwoven fabrics made from polyolefins such as polyethylene and polypropylene.

[Shape of non-aqueous electrolyte secondary battery]
The shape of the nonaqueous electrolyte secondary battery of the present invention is not particularly limited. For example, a cylinder type in which a sheet electrode and a separator are spiral, a cylinder type having an inside-out structure in which a pellet electrode and a separator are combined, a pellet electrode and a separator It can be made into the coin type etc. which were laminated | stacked.

[Method for producing non-aqueous electrolyte secondary battery]
The method for producing the nonaqueous electrolyte secondary battery of the present invention having at least an electrolyte, a negative electrode, and a positive electrode is not particularly limited, and can be appropriately selected from commonly employed methods. An example of the method for producing the nonaqueous electrolyte secondary battery of the present invention is as follows: a negative electrode is placed on an outer can, an electrolytic solution and a separator are provided thereon, and a positive electrode is placed so as to face the negative electrode; A method of assembling the battery by caulking with a sealing plate is mentioned.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these Examples, unless the summary is 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.

<Composition (Li / Ni / Mn / Co)>
It was determined by ICP-AES analysis.
<Li vacancies and oxygen vacancies>
Li vacancies and oxygen vacancies are reduced by comparing the elemental analysis before and after the introduction of Li vacancies and oxygen vacancies into the crystal structure of the lithium transition metal-based compound. Can be confirmed.

<Confirmation of crystal phase and calculation of lattice constant>
It calculated | required by the powder X-ray-diffraction measurement using the CuK alpha ray described below. As initial values for refinement of the lattice constant, parameters of hexagonal R-3m (No. 166) were used for the crystal system and space group, and LiNiO ₂ [PDF: 9-63] was used for the lattice constant. The lattice constant, sample eccentricity, and intensity weighting parameters were refined, and the zero shift and angle weighting parameters were not refined. The peak position was calculated by the profile fitting method (Peason-VII function).

-Actual XRD measurement (example, comparative example) is measured in the variable slit mode, and variable → fixed data conversion is performed.-Variable → fixed conversion is intensity (fixed) = intensity (variable) / sin θ calculation According to formula (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
Soller Slit (0.04 rad)
Gonio radius: 243mm
(Measurement condition)
X-ray output (CuKα): 40 kV, 30 mA
Scanning axis: θ / 2θ
Scanning range (2θ): 10.0-155.0 °
Measurement mode: Continuous
Reading width: 0.016 °
Counting time: 99.7 sec
<Calculation of RMS>
The sample was observed with AFM (Nanoscope III manufactured by Beco) in room temperature and air.

Observation was performed using a Si cantilever (NCH manufactured by Nanoworld). The surface roughness was defined as the least mean square (RMS) value, and was obtained with an application program attached to the apparatus.
In the process of obtaining the surface roughness, the curvature reflecting the entire shape unrelated to the surface roughness was removed by performing a third-order flattening process on the trimmed image. The trimming range was set to a range sufficiently smaller than the primary particle diameter (about 50-30% in length) in order to eliminate the influence of the primary particle outer shape as much as possible.

<BET specific surface area measurement conditions>
The BET specific surface area (SSA) was measured under a reduced pressure (degree of vacuum 5 × 10 −) with respect to the positive electrode material (lithium transition metal compound) powder using a specific surface area measuring device “NOVA1200” (manufactured by Yuasa Ionics Co., Ltd.). 4 Torr or less) After preliminary drying at 150 ° C. for 1 hour, the relative pressure of nitrogen to atmospheric pressure is 0.01, 0.02, 0.04, 0.07, 0.10 Using the adjusted high purity nitrogen gas (5N8), the value measured by the nitrogen adsorption BET 5-point method was used.

<Measurement of hydrogen ion content>
Measured by an inert gas melting-infrared absorption method using a TCH-600 type (nitrogen oxygen hydrogen analyzer) manufactured by LECO.
[Comparative Example 1]
<Method for producing lithium transition metal compound>
Weigh Li ₂ CO ₃ , Ni (OH) ₂ , Mn ₃ O ₄ , and CoOOH so that the molar ratio of Li: Ni: Mn: Co = 0.715: 0.264: 0.195: 0.150 After mixing, pure water was added to prepare a slurry. While stirring this slurry, the solid content in the slurry was pulverized to a median diameter of 0.49 μm using a circulating medium agitation type wet pulverizer.

Next, this slurry (solid content 38% by weight) was spray-dried using a two-fluid nozzle type spray dryer (Okawara Kako Co., Ltd .: LT-8 type). At this time, air was used as the dry gas, the dry gas introduction amount was 60 L / min, and the slurry supply amount was 11 g / min. The drying inlet temperature was 150 ° C. About 5 g of particulate powder obtained by spray drying with a spray dryer is charged into an alumina crucible, pre-baked at 850 ° C. for 4 hours in an air atmosphere, and then finally fired at 1050 ° C. for 8 hours (heating rate 5 ° C. / min). By crushing, a lithium nickel manganese cobalt composite oxide having a composition of 0.4Li ₂ MnO ₃ .0.6Li _0.91 Ni _0.45 Mn _0.31 Co _0.25 O ₂ was obtained. In addition, the result of the composition analysis about Li and oxygen is shown in Table-1.

<Method for producing positive electrode for lithium secondary battery>
To 150 mg of the positive electrode material (lithium transition metal compound) powder produced by the above method, 40 mg of carbon black (“DENKA BLACK POWDER” manufactured by Denki Kagaku Kogyo Co., Ltd.) was added as a conductive additive and mixed in a mortar. To this mixture, 10 mg of PTFE (“6-J” manufactured by Mitsui DuPont Fluorochemical Co., Ltd.) as a binder was further added and further mixed in a mortar. The obtained mixture containing the binder was stretched and then punched out to a diameter of 9 mmφ to obtain a positive electrode. Here, the weight of the positive electrode was adjusted to be in the range of 6.5 to 7.5 mg.

This positive electrode was vacuum-dried at 120 ° C. for 14 hours to obtain a positive electrode for evaluation.
<Method for producing lithium secondary battery>
The obtained positive electrode was placed on an aluminum mesh, and 1 mol / L-LiPF using a mixed liquid of ethylene carbonate (EC) / dimethyl carbonate (DMC) / ethyl methyl carbonate (EMC) = 3/3/4 (volume ratio) as a solvent. _A CR2032 type coin battery (lithium secondary battery) was prepared in a dry room (dew point -60 ° C. or lower) using ₆ electrolytes, a polypropylene separator as a separator, and a lithium metal foil as a counter electrode.

<Rate characteristics evaluation>
Charge to 4.8V against the lithium counter electrode at a current density of 1 / 15C (calculated assuming 200mAh / g as 1C), and further charge to a current value of 1 / 50C at a constant voltage of 4.8V. After lithium was desorbed from the inside, discharging was performed to 2.0 V with respect to the lithium counter electrode at a current density of 1/15 C, 1/2 C, or 1 C to obtain a discharge capacity. The results are shown in Table-1.

In the table, a and c are the lattice constants of the lithium transition metal compound, Δa and Δc are the rate of change of the lattice constant, and Δa / Δc is the ratio of the rate of change.
[Comparative Example 2]
After 1.5 g of the lithium nickel manganese cobalt composite oxide obtained in Comparative Example 1 was dispersed in 150 ml of a 0.1 N aqueous nitric acid solution, the mixture was stirred at room temperature for 4 hours. After filtering and washing with water, the powder obtained by drying at 200 ° C. was heat-treated in the atmosphere at 400 ° C. for 5 hours. Evaluation was conducted in the same manner as in Comparative Example 1 using this powder. The results are shown in Table-1.

[Example 1]
After 1.5 g of lithium nickel manganese cobalt composite oxide obtained in Comparative Example 1 was dispersed in 150 ml of ion exchange water having a pH of about 6, it was transferred to an autoclave and kept at 160 ° C. for 24 hours. After filtration and washing with water, it was dried at 200 ° C. overnight. The obtained powder was heat-treated at 400 ° C. for 5 hours. Using this powder, the positive electrode and coin battery were prepared and evaluated in the same manner as in Example 1, and the results are shown in Table 1. In addition, the result of the composition analysis about Li and oxygen is shown in Table-1.

[Example 2]
1.5 g of lithium nickel manganese cobalt composite oxide obtained in Comparative Example 1 was dispersed in 150 ml of ion-exchanged water adjusted to pH 8 with aqueous ammonia, then transferred to an autoclave and maintained at 120 ° C. for 24 hours. After filtration and washing with water, it was dried at 200 ° C. overnight. Using this powder, the positive electrode and coin battery were prepared and evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[Example 3]
In Example 3, heat treatment was further performed at 400 ° C. for 5 hours. Using this powder, the positive electrode and coin battery were prepared and evaluated in the same manner as in Example 1, and the results are shown in Table 1.
[Example 4]
1.5 g of the lithium nickel manganese cobalt composite oxide obtained in Comparative Example 1 was dispersed in 150 ml of ion exchange water whose pH was adjusted to 8 with aqueous ammonia, then transferred to an autoclave and maintained at 160 ° C. for 24 hours. After filtration and washing with water, it was dried at 200 ° C. overnight. The obtained powder was heat-treated at 400 ° C. for 5 hours. Using this powder, the positive electrode and coin battery were prepared and evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[Example 5]
In Example 4, heat treatment was further performed at 400 ° C. for 5 hours. Using this powder, the positive electrode and coin battery were prepared and evaluated in the same manner as in Example 1, and the results are shown in Table 1.
[Comparative Example 3]
LiNO ₃ : Ni (NO ₃ ) ₂ .6H ₂ O: Mn (NO ₃ ) ₂ .6H ₂ O is weighed to a molar ratio of 0.1667: 0.2500: 0.5833 and dissolved in water. It was set as 1M aqueous solution. The _Li 2 WO ₄ in this respect the lithium-nickel-manganese composite oxide formed after firing, was added so as to be 2 wt%. Using this as a raw material solution, spray pyrolysis was performed at 900 ° C. and a residence time of 1 second using a high temperature gas direct heating type spray pyrolysis apparatus to obtain a composite oxide precursor. The obtained complex oxide precursor was charged into an alumina crucible, pre-baked at 700 ° C. for 4 hours under air flow, and then finally fired at 1000 ° C. for 4 hours (heating rate 5 ° C./min). Crushing to obtain a lithium nickel manganese composite oxide powder. Using this powder, a positive electrode and a coin battery were prepared and evaluated in the same manner as in Example 1, and the results are shown in Table 2. In the table, a and c are the lattice constants of the lithium transition metal compound, Δa and Δc are the rate of change of the lattice constant, and Δa / Δc is the ratio of the rate of change.

[Example 6]
After 1.5 g of the lithium nickel manganese composite oxide obtained in Comparative Example 3 was dispersed in 150 ml of ion exchange water having a pH of about 6, it was transferred to an autoclave and maintained at 120 ° C. for 24 hours. After filtration and washing with water, it was dried at 200 ° C. overnight. The obtained powder was heat-treated at 400 ° C. for 5 hours. Using this powder, a positive electrode and a coin battery were prepared and evaluated in the same manner as in Example 1, and the results are shown in Table 2.

[Example 7]
After 1.5 g of the lithium nickel manganese composite oxide obtained in Comparative Example 3 was dispersed in 150 ml of ion-exchanged water whose pH was adjusted to 8 with aqueous ammonia, it was transferred to an autoclave and maintained at 120 ° C. for 24 hours. After filtration and washing with water, it was dried at 200 ° C. overnight. Using this powder, a positive electrode and a coin battery were prepared and evaluated in the same manner as in Example 1, and the results are shown in Table 2.

[Example 8]
In Example 7, heat treatment was further performed at 300 ° C. for 5 hours. Using this powder, a positive electrode and a coin battery were prepared and evaluated in the same manner as in Example 1, and the results are shown in Table 2.
[Example 9]
In Example 7, heat treatment was further performed at 400 ° C. for 5 hours. Using this powder, a positive electrode and a coin battery were prepared and evaluated in the same manner as in Example 1, and the results are shown in Table 2.

[Example 10]
1.5 g of the lithium nickel manganese composite oxide obtained in Comparative Example 3 was dispersed in 150 ml of ion exchange water adjusted to pH 9 with aqueous ammonia, then transferred to an autoclave and maintained at 120 ° C. for 24 hours. After filtration and washing with water, it was dried at 200 ° C. overnight. Using this powder, a positive electrode and a coin battery were prepared and evaluated in the same manner as in Example 1, and the results are shown in Table 2.

[Example 11]
In Example 10, heat treatment was further performed at 400 ° C. for 5 hours. Using this powder, the positive electrode and coin battery were prepared and evaluated in the same manner as in Example 1, and the results are shown in Table 1.
[Example 12]
After 1.5 g of the lithium nickel manganese composite oxide obtained in Comparative Example 3 was dispersed in 150 ml of ion-exchanged water whose pH was adjusted to 8 with aqueous ammonia, it was transferred to an autoclave and maintained at 80 ° C. for 24 hours. After filtration and washing with water, the film was dried at 200 ° C. overnight, and further heat-treated at 400 ° C. for 5 hours. Using this powder, a positive electrode and a coin battery were prepared and evaluated in the same manner as in Example 1, and the results are shown in Table 2.

From these examples, it can be seen that the discharge capacity tends to increase as the lattice constant increases. Furthermore, it can be seen from Table 1 that the discharge capacity tends to increase as the hydrogen ion content decreases. Moreover, since the compositional analysis value of Li amount and oxygen amount of Table-1 is decreasing, it turns out that Li vacancy and oxygen vacancy are introduced by hydrothermal treatment.
From Table-1 and Table-2, the treatment under acidic conditions such as dilute nitric acid increases both the specific surface area and RMS, and the active material surface is roughened. In contrast, hydrothermal treatment using ion-exchanged water or an alkaline solution has a small increase in surface area, small RMS, and little damage to the particle surface. Therefore, the initial charging efficiency is improved, and it can be seen that the present invention is effective in improving battery characteristics.

Claims (10)

The oxide represented by the general formula (1), which has Li vacancies and oxygen vacancies in the crystal structure, and the root mean square roughness (RMS) of the primary particle surface according to JIS B 0601: 2001 Lithium transition metal compound powder for a lithium secondary battery positive electrode material, characterized in that is 1.5 nm or less.
xLi ₂ MO _3. (1-x) LiNO ₂ (1)
(Wherein, x is 0 <a number satisfying x <1, M is one or more kinds of metal elements number average oxidation is 4 ^+, N is 1 or more the number average oxidation is 3 ⁺ Metal element) Claim the lithium transition metal based compound powder, after heat treatment at pH ³ 5 in a solvent, characterized by comprising the compound obtained by heat treating within 24 hours at a temperature of 900 ° C. 200 ° C. or more degrees 2. A lithium transition metal compound powder for a lithium secondary battery positive electrode material according to 1. Lithium transition metal based compound powder, after heat treatment at pH ³ 5 in a solvent, characterized by comprising the compound obtained by heat treating within 24 hours at a temperature of 900 ° C. 200 ° C. of two or more Lithium transition metal compound powder for secondary battery positive electrode material.   The lithium transition metal-based compound powder for a lithium secondary battery positive electrode material according to any one of claims 1 to 3, wherein the hydrogen ion content is 1000 wtppm or less.   The lithium transition metal compound for a lithium secondary battery positive electrode material according to any one of claims 1 to 4, wherein the heat treatment in a solvent is performed in an aqueous solution at room temperature or higher and 350 ° C or lower. powder.   The a-axis and c-axis lattice constants of the lithium transition metal-based compound powder obtained by the space group R-3m (166) both increase before and after the heat treatment. The lithium transition metal type compound powder for a lithium secondary battery positive electrode material described in the item.   It has the positive electrode active material layer containing the lithium transition metal type compound powder for lithium secondary battery positive electrode materials of any one of Claims 1-6, and a binder on a collector, A positive electrode for a lithium secondary battery.   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 7 is used as the positive electrode. A lithium secondary battery using a positive electrode for a battery. The lithium transition metal based compound powder, after heat treatment at pH ³ 5 in a solvent, the lithium transition for a lithium secondary battery positive electrode material, characterized in that the heat treatment within 24 hours at a temperature of 900 ° C. 200 ° C. or more degrees Method for producing metal compound powder.
_{xLi 2 MO 3 · (1-} x) LiNO 2 ··· (1)
(Wherein, x is 0 <a number satisfying x <1, M is one or more kinds of metal elements number average oxidation is 4 ^+, N is 1 or more the number average oxidation is 3 ⁺ Metal element)   The method for producing a lithium transition metal compound powder for a lithium secondary battery positive electrode material according to claim 9, wherein the heat treatment is performed in an aqueous solution at room temperature or higher and 350 ° C or lower.