JP2011225450A - Element-substituted lithium-manganese composite oxide particle composition, method for producing the composition, and secondary battery using the composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lithium-manganese composite oxide particle composition which has a high energy density, has a high charge and discharge capacity, and is excellent in cycle characteristics when it is used as a positive electrode active material of a lithium-ion secondary battery, and to provide a method for producing the same.SOLUTION: The lithium-manganese composite oxide particle composition is a composite oxide represented by general formula (I) of LiMnCrMO, wherein M denotes at least one element selected from the group consisting of B, Mg, Al, Si, Sc, Ti, V, Fe, Co, Ni, Cu, Zn, Ga, Y, Zr, Nb, Mo, Ru, Sn, Sb, Hf, Ta, Pb and a rare earth element; x, y, a and b are the numbers which satisfy 0.8≤x≤1.2, 1.8≤y≤2.4, 0<a≤0.2, and 0.01≤b≤0.2. The composite oxide is composed of: a composite oxide having a monoclinic crystal system; or a mixture of a composite oxide having a monoclinic crystal system and a composite oxide having an orthorhombic crystal system. Here, the intensity ratio R defined by I (orthorhombic crystal)/I (monoclinic crystal) in X-ray diffraction is in the range of 0 to 0.3.

Description

  The present invention relates to a lithium manganese composite oxide particulate composition useful as a positive electrode active material for a lithium ion secondary battery and a method for producing the same, and further uses the lithium manganese composite oxide particulate composition as a positive electrode active material. The present invention relates to a lithium ion secondary battery.

Conventionally, lithium cobalt composite oxide (LiCoO ₂ ) having a theoretical capacity of 274 mAh / g has been used as a positive electrode active material for lithium ion secondary batteries. However, since lithium cobalt composite oxide uses cobalt as a raw material, the production cost is high and the resources are limited, so there is also anxiety in terms of supply. Therefore, 4V class LiMn ₂ O ₄ having a spinel structure has been proposed as a positive electrode active material as a lithium manganese composite oxide which is abundant in resources and which uses inexpensive manganese as a raw material. However, this composite oxide has the disadvantages that the theoretical capacity is as low as 148 mAh / g and the charge / discharge cycle performance is inferior.

Under such circumstances, tetragonal Li ₂ Mn ₂ O ₄ and orthorhombic or monoclinic LiMnO ₂ having the same theoretical capacity as lithium cobaltate (285 mAh / g) are alternative materials for lithium cobaltate. As a positive electrode material for lithium ion secondary batteries, it is expected.

LiMnO ₂ having a monoclinic structure is already known (see Patent Document 1). A composite oxide in which a part of the manganese atom of LiMnO ₂ having a monoclinic structure is substituted with a substitution element is already known (for example, see Patent Document 2). In addition, a composite oxide in which a part of lithium atoms of LiMnO ₂ having a monoclinic structure is substituted with a substitution element is already known (see, for example, Patent Document 3). Furthermore, composite oxides in which a part of lithium atoms and manganese atoms are each substituted with a substitute element are already known (see, for example, Patent Documents 4 and 5).

In lithium ion secondary batteries using such lithium manganese composite oxide as the positive electrode active material, capacity and cycle characteristics are improved compared to conventional manganese-based positive electrode active materials containing spinel-type LiMn ₂ O _4. However, there is a strong demand for further improvement of characteristics and cost reduction.

Japanese Patent Laid-Open No. 11-21128 JP 2000-294242 A Japanese Patent Laid-Open No. 11-317225 JP 11-317226 A JP 2000-133266 A

  The present invention has been made in order to solve the above-described problems in lithium manganese composite oxide as a positive electrode active material of a lithium ion secondary battery, and is used when used as a positive electrode active material of a lithium ion secondary battery. An object of the present invention is to provide a lithium manganese composite oxide particulate composition having a high energy density, a high charge / discharge capacity, and excellent cycle characteristics, and a method for producing the same.

  Another object of the present invention is to provide a high-performance and inexpensive lithium ion secondary battery using such a lithium manganese composite oxide particulate composition as a positive electrode active material.

According to the invention, the general formula (I)
Li _x Mn _1-ab Cr _a M _b O _y
(Wherein M is B, Mg, Al, Si, Sc, Ti, V, Fe, Co, Ni, Cu, Zn, Ga, Y, Zr, Nb, Mo, Ru, Sn, Sb, Hf, Ta, Represents at least one element selected from the group consisting of Pb and rare earth elements, and x, y, a and b are respectively
0.8 ≦ x ≦ 1.2,
1.8 ≦ y ≦ 2.
4, 0 <a ≦ 0.2,
0 ≦ b ≦ 0.2
It is a number that satisfies )
A composite oxide having a monoclinic crystal system, or a composite oxide having a monoclinic crystal system and an orthorhombic crystal composite crystal Lithium manganese composite oxidation characterized in that the intensity ratio R defined by I (orthorhombic) / I (monoclinic) in X-ray diffraction is in the range of 0 to 0.3 A particulate composition is provided. Hereinafter, this is referred to as a first lithium manganese composite oxide particulate composition according to the present invention.

According to the present invention, the general formula (II)
Li _x Mn _1-ab Cr _{a Mb} N _c O _y
(Wherein M is B, Mg, Al, Si, Sc, Ti, V, Fe, Co, Ni, Cu, Zn, Ga, Y, Zr, Nb, Mo, Ru, Sn, Sb, Hf, Ta, At least one element selected from the group consisting of Pb and rare earth elements, N represents at least one element selected from the group consisting of In and W, and x, y, a, b and c are respectively
0.8 ≦ x ≦ 1.2,
1.8 ≦ y ≦ 2.7,
0 <a ≦ 0.2,
0 ≦ b ≦ 0.2,
0 <c ≦ 0.2
It is a number that satisfies )
A composite oxide having a monoclinic crystal system, or a composite oxide having a monoclinic crystal system and an orthorhombic crystal composite crystal Lithium manganese composite oxidation characterized in that the intensity ratio R defined by I (orthorhombic) / I (monoclinic) in X-ray diffraction is in the range of 0 to 0.3 A particulate composition is provided. Hereinafter, this is referred to as a second lithium manganese composite oxide particulate composition according to the present invention.

  Furthermore, according to the present invention, a lithium compound, a trivalent manganese compound, a chromium compound, and a compound of element M (a compound of two or more elements among the compounds of three elements of manganese, chromium, and element M are solid solution compounds) The first lithium-manganese composite oxide comprising: a first step of obtaining a mixture by mixing, and a second step of firing the mixture in an inert gas atmosphere. A method for producing a particulate composition is provided.

  Also, a lithium compound, a trivalent manganese compound, a chromium compound, a compound of element M, and a compound of element N (a compound of two or more elements among the compounds of four elements of manganese, chromium, element M, and element N are The second lithium-manganese composite comprising: a first step of mixing a solid solution compound to obtain a mixture; and a second step of firing the mixture in an inert gas atmosphere. A method for producing an oxide particulate composition is provided.

  In addition to the above, according to the present invention, a lithium ion secondary battery comprising the above-described lithium manganese composite oxide particulate composition as a positive electrode active material in a lithium ion secondary battery comprising a positive electrode, a negative electrode, and an electrolyte. A battery is provided.

  According to the lithium ion secondary battery using the lithium manganese composite oxide particulate composition according to the present invention as the positive electrode active material, a high discharge capacity can be obtained and the discharge capacity for each cycle is stable.

It is sectional drawing which shows an example of a lithium ion secondary battery. 2 is an X-ray diffraction chart of lithium manganese composite oxide particulate compositions according to Example 2, Example 5 and Comparative Example 1. FIG. 1 is a graph showing discharge capacity per cycle of a lithium ion secondary battery using a lithium manganese composite oxide particulate composition according to the present invention as a positive electrode active material, and a lithium manganese composite oxide particulate composition according to a comparative example as a positive electrode; It shows with the discharge capacity for every cycle of the lithium ion secondary battery used as an active material.

The first lithium manganese composite oxide particulate composition according to the present invention has the general formula (I)
Li _x Mn _1-ab Cr _a M _b O _y
(Wherein M is B, Mg, Al, Si, Sc, Ti, V, Fe, Co, Ni, Cu, Zn, Ga, Y, Zr, Nb, Mo, Ru, Sn, Sb, Hf, Ta, Represents at least one element selected from the group consisting of Pb and rare earth elements, and x, y, a and b are respectively
0.8 ≦ x ≦ 1.2,
1.8 ≦ y ≦ 2.
4, 0 <a ≦ 0.2,
0 ≦ b ≦ 0.2
It is a number that satisfies )
A composite oxide having a monoclinic crystal system, or a composite oxide having a monoclinic crystal system and an orthorhombic crystal composite crystal The intensity ratio R defined by I (orthorhombic) / I (monoclinic) in X-ray diffraction is in the range of 0 to 0.3.

  That is, the first lithium manganese composite oxide particulate composition according to the present invention is obtained by substituting some of the manganese atoms of the lithium manganese composite oxide with chromium (and element M).

The second lithium manganese composite oxide particulate composition according to the present invention has the general formula (II)
Li _x Mn _1-ab Cr _{a Mb} N _c O _y
(Wherein M is B, Mg, Al, Si, Sc, Ti, V, Fe, Co, Ni, Cu, Zn, Ga, Y, Zr, Nb, Mo, Ru, Sn, Sb, Hf, Ta, At least one element selected from the group consisting of Pb and rare earth elements, N represents at least one element selected from the group consisting of In and W, and x, y, a, b and c are respectively
0.8 ≦ x ≦ 1.2,
1.8 ≦ y ≦ 2.7,
0 <a ≦ 0.2,
0 ≦ b ≦ 0.2,
0 <c ≦ 0.2
It is a number that satisfies )
A composite oxide having a monoclinic crystal system, or a composite oxide having a monoclinic crystal system and an orthorhombic crystal composite crystal The intensity ratio R defined by I (orthorhombic) / I (monoclinic) in X-ray diffraction is in the range of 0 to 0.3.

  That is, the second lithium manganese composite oxide particulate composition according to the present invention is obtained by further substituting some of the manganese atoms of the first lithium manganese composite oxide particulate composition with the element N. .

According to the present invention, the first and second lithium manganese composite oxide particulate compositions are composed of “a composite oxide whose crystal system is monoclinic, or a compound oxide whose crystal system is monoclinic. "It is composed of a mixture of a complex oxide having an orthorhombic crystal system" means that the X-ray diffraction chart of the lithium manganese composite oxide particulate composition is JCPDS (Joint Committee Powder Diffraction at the present time). Standard), but monoclinic LiMnO ₂ described in, for example, JP-A-11-21128 and M. Tabuchi et al., J. Electrochem. Soc., Vol. 145, L49). Or a mixture of this and LiMnO ₂ which is an orthorhombic lithium manganese composite oxide.

  Furthermore, according to the present invention, the first and second lithium manganese composite oxide particulate compositions have an intensity ratio R defined by “I (orthogonal) / I (monoclinic) in X-ray diffraction”. "Is in the range of 0 to 0.3" means that in X-ray diffraction, the orthorhombic crystal has a diffraction intensity of the diffraction peak of the monoclinic (001) plane (hereinafter referred to as I (monoclinic)). The ratio R (that is, R = I (orthorhombic) / I (monoclinic)) of the diffraction intensity of the diffraction peak of the (010) plane (hereinafter referred to as I (orthogonal)) is 0 to 0.3. Means in the range of

  As described above, the intensity ratio R is defined as I (orthorhombic) / I (monoclinic), and the lithium manganese composite oxide particulate composition according to the present invention includes the first and second Also, the strength ratio R is in the range of 0 to 0.3. The higher the intensity ratio R, the higher the ratio of orthorhombic crystals in a mixture of a complex oxide whose crystal system is monoclinic and a complex oxide whose crystal system is orthorhombic. The lithium ion secondary battery used as the active material tends to have poor cycle characteristics and charge / discharge capacity. When the strength ratio R exceeds 0.3, the obtained lithium ion secondary battery does not have practically sufficient cycle characteristics. According to the invention, the intensity ratio R is preferably in the range of 0 to 0.2.

  In the present invention, in the first lithium manganese composite oxide particulate composition represented by the general formula (I) and the second lithium manganese composite oxide particulate composition represented by the general formula (II) , Chromium, element M, and element N are each an element that substitutes a part of a manganese atom (hereinafter referred to as a substituted element).

  That is, chromium is a first substitution element that substitutes a part of manganese atoms in the first and second lithium manganese composite oxide particulate compositions according to the present invention, and the element M is the first substitution element according to the present invention. And the second lithium-manganese composite oxide particulate composition, the second substitution element for substituting a part of the manganese atom, B, Mg, Al, Si, Sc, Ti, V, Fe, Co, Ni Cu, Zn, Ga, Y, Zr, Nb, Mo, Ru, Sn, Sb, Hf, Ta, Pb and at least one selected from the group consisting of rare earth elements. In the present invention, the rare earth element is preferably Ce, Pr, Nd and / or Eu.

  The third substitution element N is a third substitution element for substituting a part of manganese atoms in the second lithium manganese composite oxide particulate composition according to the present invention, and is selected from the group consisting of In and W. At least one kind.

According to the present invention, in the first lithium manganese composite oxide particulate composition, the ratio x of lithium atoms, the ratio y of oxygen atoms, and the ratio in which the first and second substitution elements substitute manganese atoms. a and b are respectively
0.8 ≦ x ≦ 1.2,
1.8 ≦ y ≦ 2.4,
0 <a ≦ 0.2,
0 ≦ b ≦ 0.2
It is the range which satisfies.

Further, according to the present invention, in the second lithium manganese composite oxide particulate composition, the lithium atom ratio x, the oxygen atom ratio y, and the first, second, and third substitution elements are manganese. The proportions a, b and c for substituting atoms are respectively
0.8 ≦ x ≦ 1.2,
1.8 ≦ y ≦ 2.7,
0 <a ≦ 0.2,
0 ≦ b ≦ 0.
20 <c ≦ 0.2
It is the range which satisfies.

In the first and second lithium manganese composite oxide particulate compositions according to the present invention, the first substitution element chromium is an element that controls the intensity ratio R, and is mainly monoclinic lithium manganese composite oxide particles. Is an essential element for obtaining a composition. The reason for this is not necessarily clear, but in the LiMnO ₂ crystal, the chromium atom occupies a part of the position occupied by the manganese atom. The orthorhombic crystal occupies the main crystal system, and the rest is considered to be unstable orthorhombic.

  According to the present invention, the substitution amount a (molar fraction) of manganese atoms by chromium is 0.2 or less in 1 mol of manganese atoms in the lithium manganese composite oxide composition. That is, the manganese substitution amount a by chromium is in a range satisfying 0 <a ≦ 0.2, and preferably in a range of 0.03 ≦ a ≦ 0.1. When the substitution amount of manganese atoms by chromium is too small, the cycle characteristics and charge / discharge capacity of a lithium ion secondary battery using the obtained lithium manganese composite oxide composition as a positive electrode active material are deteriorated. On the other hand, when the amount of substitution of manganese atoms by chromium is too large, the lithium ion secondary battery that exceeds the solid solubility limit and uses such a composite oxide as a positive electrode active material has a reduced discharge capacity.

  According to the present invention, lithium manganese composite oxidation mainly composed of a monoclinic crystal obtained by substituting a part of manganese atoms with chromium (strength ratio R is in the range of 0 to 0.3). In the particulate composition, the cycle characteristics and capacity can be further improved by further substituting some of the manganese atoms with the second substitution element M. Therefore, the second substitution element M is also considered to contribute to the stabilization of the crystal structure of the obtained lithium manganese composite oxide and the improvement of the characteristics, like the first substitution element chromium.

  According to the present invention, among the second substitution elements M, in particular, when the lithium manganese composite oxide particulate composition using molybdenum is used as a positive electrode active material in a lithium ion secondary battery, There is an effect of stabilizing the discharge capacity in the high voltage region of the battery. That is, generally, in most cases, the discharge curve of a lithium ion secondary battery using lithium manganate as the positive electrode active material is a curve having a two-step flat portion in each of a region showing a voltage of 4V and a region showing a voltage of 3V. According to the present invention, a lithium manganese composite oxide particulate composition mainly composed of monoclinic crystals obtained by substituting a part of manganese atoms with chromium and molybdenum is used as a positive electrode in a lithium ion secondary battery. When used as an active material, the discharge capacity in the 4V region has little change even when charging and discharging are repeated.

  According to the present invention, the substitution amount b (molar fraction) of the second substitution element M is in the range of 0 to 0.2 out of 1 mol of manganese atoms in the lithium manganese composite oxide composition. That is, the substitution amount b of manganese atoms by the second substitution element M is in the range of 0 ≦ b ≦ 0.2, and preferably in the range of 0.01 ≦ b ≦ 0.1. When the substitution amount of manganese atoms by the second substitution element M is too large, the charge / discharge capacity of the lithium ion secondary battery using this as the positive electrode active material is lowered.

  In the second lithium manganese composite oxide particulate composition according to the present invention, at least one selected from the group consisting of In and W, in addition to chromium and the second substitution element M, a part of the manganese atom. The third substitution element N is substituted. This third substitution element N is a lithium manganese composite oxide mainly composed of monoclinic crystals obtained by substituting a part of manganese atoms with chromium (strength ratio R is in the range of 0 to 0.3). The particulate composition has an effect of stabilizing the initial discharge capacity of a lithium ion secondary battery using the positive electrode active material as the positive electrode active material. That is, for example, the cycle characteristics of the lithium ion secondary battery using the lithium manganese composite oxide particulate composition not containing the third substitution element N as a positive electrode active material show a tendency that the capacity is initially reduced. By substituting a part of the manganese atom with the third substitution element, such a decrease in capacity can be suppressed. Thus, the second lithium manganese composite oxide particulate composition according to the present invention is used as a positive electrode active material. Thus, a lithium ion secondary battery having stable cycle characteristics from the beginning of the battery can be obtained.

  According to the present invention, in the second lithium manganese composite oxide particulate composition, the substitution amount c (molar fraction) of the manganese atom by the third substitution element N is the manganese in the lithium manganese composite oxide composition. It is 0.2 or less in 1 mol of atoms. That is, the substitution amount c of manganese atoms by the third substitution element N is in the range of 0 <c ≦ 0.2, and preferably in the range of 0.01 ≦ c ≦ 0.05. When the amount of substitution of manganese atoms by the third substitution element N is too large, the solid solubility limit is exceeded, and the lithium ion secondary battery using such a composite oxide as the positive electrode active material has a reduced discharge capacity.

  In the first and second lithium manganese composite oxide compositions according to the present invention represented by the general formula (I) and the general formula (II), respectively, x is 1 stoichiometrically, Of course, there may be out of quantity. In the lithium manganese composite oxide particulate composition according to the present invention, x can be in the range of 0.8 ≦ x ≦ 1.2. Whether the amount of lithium is greater or less than the stoichiometric amount, it can be suitably used as a positive electrode active material for lithium ion secondary batteries.

  On the other hand, in the first lithium manganese composite oxide composition according to the present invention represented by the general formula (I), y is a value determined by the above-described values of x and b and the valence of the second substitution element M. The minimum and maximum values are determined as follows. That is, when x = 0.8, the valence of the second substitution element M is 2, and b = 0.2, the minimum value is obtained at y = 1.8, and x = 1.2, the second substitution element When the valence of the element M is 6 and b = 0.2, the maximum value is obtained at y = 2.4.

  In the second lithium manganese composite oxide composition according to the present invention represented by the general formula (II), y represents the values of x, b, and c described above, and the valence of the second substitution element M. The value is determined by the valence of the third substitution element N, and the minimum value and the maximum value are determined as follows. That is, when x = 0.8, the valence of the second substitution element M is 2, b = 0.2, the valence of the third substitution element N is 3, and c is arbitrary, y = 1.8. And when x = 1.2, the valence of the second substitution element M is 6, b = 0.2, the valence of the third substitution element N is 6, and c = 0.2, The maximum value is obtained at y = 2.7.

Next, the first and second lithium manganese composite oxide particulate compositions according to the present invention preferably have a specific surface area in the range of 0.1 to 6.0 m ² / g, 0.1 to ² . A range of 0 m ² / g is particularly preferable. Here, in this invention, a specific surface area points out the value calculated | required by the BET single point method using the automatic surface area measuring apparatus (The MONOSORBMS-15 by Yuasa Ionics company).

When the specific surface area of the lithium manganese composite oxide particulate composition is smaller than 0.1 m ² / g, a large amount of electricity can be taken out rapidly when used as a positive electrode active material of a lithium ion secondary battery. It may not be possible. On the other hand, when the specific surface area exceeds 6.0 m ² / g, the elution amount of manganese into the electrolytic solution in the lithium ion secondary battery becomes large, which may cause a problem of reduction in charge / discharge capacity (cycleability). There is.

  Moreover, the lithium manganese composite oxide particulate composition according to the present invention preferably has a tap density in the range of 1.4 to 2.4 g / cc. Here, in the present invention, the tap density means that 10 g of powder is collected in a 50 mL measuring cylinder, dropped 50 times vertically from a height of 50 mm onto a horizontal and flat hard rubber plate, and then tapped. The volume V (cc) is measured, and the value of 10 / V (g / cc) at that time is indicated.

  As the tap density of the lithium manganese composite oxide particulate composition is larger, there is an advantage that the amount of the positive electrode active material in the volume of the lithium ion secondary battery is increased and the charge / discharge capacity per volume can be increased. However, if only the tap density is to be increased, the lithium ion insertion / desorption reactivity may be sacrificed. In particular, according to the present invention, the tap density is preferably in the range of 1.6 to 2.2 g / cc.

  Furthermore, the lithium manganese composite oxide particulate composition according to the present invention has a secondary particle diameter in the range of 2 to 50 μm as observed by SEM (scanning electron micrograph) and a spherical particle shape. Is preferred. In the present invention, the particle diameter of one particle refers to the average value of the long and short diameters, and the average particle diameter is the average value of the particle diameters of 200 arbitrary particles in the SEM image.

  When the particle size of the lithium manganese composite oxide particulate composition is smaller than 2 μm, it leads to a decrease in tap density, and when used as a positive electrode active material of a lithium ion secondary battery, the filling amount per volume decreases. The charge / discharge capacity is lowered. On the other hand, when the particle diameter exceeds 50 μm, such particles may cause a short circuit by passing through a separator between positive and negative electrodes made of a polymer film such as polypropylene in a lithium ion secondary battery. In particular, according to the present invention, the particle size of the lithium manganese composite oxide particulate composition is preferably in the range of 2 to 50 μm, and most preferably in the range of 2 to 30 μm.

  In the present invention, the shape of the particulate composition being “spherical” does not have to be “spherical”, but may be generally “spherical”.

  In the first lithium manganese composite oxide particulate composition according to the present invention as described above, as the first step, a lithium compound, a trivalent manganese compound, a chromium compound and an element M compound (manganese, chromium and element M Of the three elemental compounds, the compound of two or more elements may be solid solution compounds) to obtain a mixture, and then, in the second step, the mixture is fired in an inert gas atmosphere Can be obtained.

  Similarly, the second lithium manganese composite oxide particulate composition according to the present invention includes a lithium compound, a trivalent manganese compound, a chromium compound, a compound of element M, and a compound of element N (manganese and chromium as a first step). And a compound of two or more elements among the compounds of four elements of element M and element N may be a solid solution compound) to obtain a mixture, and then, as a second step, It can be obtained by firing in an inert gas atmosphere.

  In the present invention, as described above, the reaction in which the mixture is baked in an inert gas atmosphere to obtain a lithium manganese composite oxide particulate composition is hereinafter referred to as a lithiation reaction.

  In the present invention, in the first step for producing the first and second lithium manganese composite oxide particulate compositions, as the lithium compound, the final lithium manganese composite oxide composition is used. If it gives, it will not specifically limit, For example, organic acid lithium, such as lithium acetate and lithium oxalate, and inorganic lithium salts, such as lithium hydroxide, lithium carbonate, and lithium nitrate, are used. However, among these, lithium hydroxide, lithium carbonate, or lithium nitrate is preferably used as the lithium compound from the viewpoints of price, operability, and the like.

  In the first step, the trivalent manganese compound is not particularly limited as long as it finally gives a target lithium manganese composite oxide composition. For example, manganese dioxide (particularly, Electrolytic manganese dioxide), manganese sesquioxide, manganese oxyhydroxide and the like are used. However, among these, manganese trioxide or manganese oxyhydroxide is preferably used from the viewpoints of price and availability.

  As already well known, the above-mentioned manganese sesquioxide is obtained by heating a manganese compound such as manganese dioxide, manganese carbonate, manganese sulfate or the like at a temperature of about 600 to 900 ° C. in the air or in an oxidizing atmosphere. be able to. Commercially available manganese sesquioxide can also be used.

The manganese oxyhydroxide is generally represented by MnOOH, but is precisely Mn ₂ O ₃ .H ₂ O. That is, manganese oxyhydroxide generally means manganese trioxide (Mn ₂ O ₃ ) having one molecule of water. However, in the present invention, the number of water molecules possessed by manganese trioxide is less than one molecule. It may also be more than one molecule.

  The manganese oxyhydroxide can be obtained by various methods as already known. For example, it can be obtained by neutralizing a compound having divalent manganese such as manganese nitrate, manganese chloride, and manganese sulfate with an alkali, and then oxidizing it with an oxidizing agent such as air, oxygen, or hydrogen peroxide. Further, for example, it can also be obtained by carbonating the aqueous solution of the divalent manganese compound, followed by alkali treatment, and finally oxidation treatment. Commercially available manganese oxyhydroxide can also be used.

  In the production of the lithium manganese composite oxide particulate composition according to the present invention, the chromium compound, the element M and the element N are also particularly limited as long as they finally give the target lithium manganese composite oxide composition. Appropriate ones are used.

  Accordingly, specific examples of the chromium compound include, for example, chromium oxide, chromium hydroxide, chromium nitrate, chromium sulfate, chromium acetate and the like, and specific examples of the element M compound include, for example, aluminum hydroxide, aluminum nitrate, aluminum sulfate. , Aluminum acetate, boric acid, magnesium hydroxide, magnesium carbonate, magnesium chloride, magnesium acetate, vanadium pentoxide, ammonium metavanadate, iron hydroxide, iron nitrate, iron sulfate, iron chloride, cobalt hydroxide, cobalt nitrate, cobalt sulfate , Cobalt chloride, nickel hydroxide, nickel nitrate, nickel sulfate, yttrium oxide, yttrium nitrate, molybdenum oxide, ruthenium chloride, tin oxide, tin chloride, antimony chloride, cerium oxide, cerium nitrate, praseodymium nitrate, neodymium chloride, europium acetate , Hafnium chloride, tantalum chloride, lead sulfate, lead acetate, lead chloride and the like, and specific examples of element N compounds include oxides such as indium oxide, indium sulfate, indium chloride, tungsten oxide, tungsten chloride, water Examples thereof include oxides, inorganic salts, and organic salts.

  As described above, according to the present invention, in the production of the first lithium manganese composite oxide particulate composition, in the first step, the lithium compound, the trivalent manganese compound, the chromium compound, and the element M compound (manganese And a compound of two or more elements among the compounds of three elements of chromium and element M may be a solid solution compound) to obtain a mixture. In the production of the second lithium manganese composite oxide particulate composition, in the first step, a lithium compound, a trivalent manganese compound, a chromium compound, an element M compound, and an element N compound (manganese and chromium and Of the four element compounds of element M and element N, a compound of two or more elements may be a solid solution compound.) To obtain a mixture.

Accordingly, in the production of the first and second lithium manganese composite oxide particulate compositions, various aspects are possible when the respective compounds are mixed in the first step. However, according to the present invention, in the production of the first lithium manganese composite oxide particulate composition, in particular, after mixing the trivalent manganese compound, the chromium compound and the element M compound, It is preferable to obtain a mixture by firing to obtain a solid solution oxide, which is mixed with a lithium compound. According to this aspect, a uniform solid solution oxide of trivalent manganese atoms, element Cr, and element M can be obtained. As such a solid solution oxide, for example, (Mn _1-ab Cr _a M _b ) ₂ O _y can be exemplified. Here, y is a value determined by the valence of the element M together with the value of b so that the solid solution oxide is electrically neutral.

Similarly, in the production of the second lithium manganese composite oxide particulate composition, among others, a trivalent manganese compound, a chromium compound, a compound of element M and a compound of element N are mixed and then fired in the atmosphere. Thus, a solid solution oxide is preferably mixed with a lithium compound to obtain a mixture. According to this aspect, a uniform solid solution oxide of trivalent manganese atom, element Cr, element M, and element N can be obtained. Such solid solution oxides, for example, can be exemplified _{(Mn 1-abc Cr a M} b N c) 2 O y and the like. Here, y is a value determined by the valences of the elements M and N together with the values of b and c so as to make the solid solution oxide electrically neutral.

  Hereinafter, the production of the first and second lithium manganese composite oxide particulate compositions will be described in common. The description in parentheses indicates the case of producing the second lithium manganese composite oxide particulate composition.

  The method for obtaining such a solid solution oxide of trivalent manganese atom, chromium, and element M (and element N) is not particularly limited. For example, a chromium compound (for example, nitrate, acetate, water) An aqueous solution of an element M compound (eg nitrate, acetate, hydroxide, etc.) and an element N compound (eg sulfate, chloride, oxide, etc.) with manganese carbonate. It can be obtained by evaporating to dryness with stirring, depositing the chromium compound and the element M compound (and the element N compound) on the surface of the manganese carbonate particles, and firing this in the air. it can.

  As another method, for example, manganese carbonate particles, a chromium compound, and an element M compound (and an element N compound) were mixed, and the compounds of these elements were deposited on the surfaces of the manganese carbonate particles. Thereafter, the particles can be obtained by firing at a high temperature to produce particles that have undergone excessive sintering, and then firing them again in an oxidizing atmosphere.

  Thus, after performing the 1st process and obtaining a mixture, as a 2nd process, this mixture is baked in inert gas atmosphere and lithiation reaction is performed, and the 1st or this invention is made. A second lithium manganese composite oxide particulate composition can be obtained.

  According to the present invention, in the second step, the above mixture is fired in an inert gas atmosphere so that the valence of trivalent manganese does not change due to oxidation or reduction reaction. In the second step, if the valence of trivalent manganese is changed by oxidation or reduction reaction, the lithium manganese composite oxide particulate composition according to the present invention cannot be obtained.

  As said inert gas, helium, nitrogen, argon etc. are used, for example, However, Nitrogen gas is used preferably from an economical viewpoint. However, any inert gas can be used as long as it forms an atmosphere that does not cause a change in the valence of the trivalent manganese.

  In the second step, the firing temperature of the mixture is in the range of 300 ° C to 1000 ° C, preferably in the range of 470 ° C to 900 ° C. When the firing temperature is lower than 300 ° C., the lithiation reaction is incomplete. On the other hand, when the firing temperature is higher than 1000 ° C., when primary particles of the obtained composite oxide particulate composition grow excessively and are used as a positive electrode active material of a lithium ion secondary battery, It becomes difficult for lithium to enter and exit, and it is difficult to obtain a battery having satisfactory characteristics.

  In the second step, the optimum value of the calcination temperature and the product, that is, the crystal phase of the lithium manganese composite oxide composition vary depending on the type of substitution element used. For example, when no substitution element is used, an orthorhombic complex oxide composition is formed in the entire temperature range of 470 ° C. to 900 ° C. When some of the manganese atoms are replaced with chromium atoms, only a monoclinic complex oxide composition is formed, or a monoclinic and orthorhombic complex oxide composition is formed, and the firing temperature The higher the is, the higher the monoclinic ratio.

  The lithium ion secondary battery according to the present invention uses the lithium manganese composite oxide particulate composition thus obtained as a positive electrode active material.

  An example of a lithium ion secondary battery using a non-aqueous electrolyte (organic electrolyte) is shown in FIG. The positive electrode 1 and the negative electrode 2 are accommodated in the battery container 4 so as to face each other via a separator 3 impregnated with a nonaqueous electrolyte solution. The positive electrode 1 is connected to a positive electrode lead wire 6 via a positive electrode current collector 5. The negative electrode 2 is connected to the negative electrode lead wire 8 via the negative electrode current collector 7, and chemical energy generated inside the battery is taken out from the lead wires 6 and 8 to the outside as electric energy. Configured to get.

  The lithium manganese composite oxide particulate composition according to the present invention is blended with a conductive agent, a binder, a filler and the like and kneaded to form a mixture (paste), which is, for example, a positive electrode made of a stainless mesh. It is applied to a current collector, pressure-bonded, and heated and dried under reduced pressure to form a positive electrode. However, if necessary, the mixture may be pressure-molded into an appropriate shape such as a disk, and heat treated under vacuum as necessary to form a positive electrode.

  The conductive agent is not particularly limited as long as it is an electron conductive material that does not cause a chemical change in the lithium ion secondary battery. Accordingly, examples of the conductive agent include conductive polymer materials such as natural graphite, artificial graphite, carbon black, ketjen black, carbon fiber, metal powder, metal fiber, and polyphenylene. These may be used alone or in combination of two or more. Although the compounding quantity of a electrically conductive agent is not specifically limited, Usually, it is the range of 1-50 weight% in the said mixture, Preferably, it is the range of 2-30 weight%.

  The binder is not particularly limited, and for example, starch, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, regenerated cellulose, diacetyl cellulose, polyvinyl chloride, polyvinyl pyrrolidone, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene , Ethylene-propylene-diene rubber (EPDM), sulfonated EPDM, styrene-butadiene rubber, polybutadiene, fluororubber, polyethylene oxide and the like. These may be used alone or in combination of two or more. The blending amount of the binder is not particularly limited, but usually in the above mixture, the range of 1 to 50% by weight is preferable, and the range of 2 to 30% by weight is particularly preferable.

  The said filler is mix | blended with a mixture as needed. As a filler, if it is a fibrous material which does not raise | generate a chemical change in a lithium ion secondary battery, it will not specifically limit, The conventionally known thing is used suitably. Accordingly, examples of such a filler include polyolefin resin fibers such as polypropylene resin and polyethylene resin, glass fibers, and carbon fibers. The blending amount of the filler is not particularly limited, but is usually in the range of 0 to 30% by weight in the above mixture.

  In the lithium ion secondary battery according to the present invention, the negative electrode material is not particularly limited as long as it is conventionally used in a lithium ion secondary battery. For example, metallic lithium, lithium alloy, lithium A carbon material capable of occluding and releasing ions is used.

  The positive electrode and the negative electrode are usually formed on a current collector. Although it does not specifically limit as this electrical power collector, Usually, stainless steel, its mesh, etc. are used.

In addition, the non-aqueous electrolyte may be any as long as it is conventionally known. For example, carbonates such as ethylene carbonate (EC), propylene carbonate, dimethyl carbonate (DMC), diethyl carbonate, Lithium perchlorate (LiClO ₄ ) or lithium hexafluorophosphate in organic solvents such as sulfolanes, lactones, ethers such as 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane, etc. there may be mentioned those obtained by dissolving dissociable lithium salts (LiPF ₆₎ or the like. As the separator, for example, a porous film made of a polyolefin resin such as polyethylene or polypropylene is used, but the separator is not limited thereto.

  The lithium ion secondary battery according to the present invention can be suitably used for portable electronic devices such as notebook computers, mobile phones, video movies, etc., as well as large batteries such as batteries mounted on mobile objects and household auxiliary power supplies. Application as is also possible.

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Example 1
Manganese carbonate (spherical, average particle size 10 μm) 105.75 g, chromium nitrate nonahydrate 20.01 g, cobalt sulfate heptahydrate 8.43 g (molar ratio Cr / (Mn + Cr + Co) = 0.05, molar ratio Co / (Mn + Cr + Co) = 0.03) was placed in a 500 mL capacity beaker, 250 mL of water was added, and the mixture was stirred and uniformly mixed and dispersed to obtain a slurry. The slurry was heated with stirring to evaporate the water to dryness, and then dried overnight in an electric dryer. The obtained lump was pulverized to obtain manganese carbonate particles having chromium nitrate and cobalt sulfate deposited on the surface. Next, manganese carbonate particles coated with chromium nitrate and cobalt sulfate are put in an alumina crucible in this way, fired in the atmosphere at 1150 ° C. for 4 hours, cooled, pulverized, and oxygenated. Baking was performed at 800 ° C. for 10 hours in an atmosphere to obtain a manganese oxide powder in which 5 mol% of chromium and 3 mol% of cobalt were substituted and dissolved with respect to manganese atoms. As a result of the X-ray diffraction measurement, it coincided with the peak pattern of manganese sesquioxide Mn ₂ O ₃ (JCPDS card No. 41-1442).

Next, 7.89 g of manganese dioxide powder in which chromium and cobalt are dissolved and 4.20 g of lithium hydroxide monohydrate are put in a mortar (molar ratio Li / (Mn + Cr + Co) = 1.00), and uniformly Mixed. The obtained mixture was put into an alumina crucible and calcined at 575 ° C. for 15 hours in a nitrogen atmosphere to replace lithium manganese oxide (LiMn _0.92 ) with 5 mol% chromium and 3 mol% cobalt substituted for manganese atoms. Cr _0.05 Co _0.03 O ₂ ) was obtained. This product was pulverized by a sample mill for about 20 seconds to deagglomerate the secondary particles to obtain a lithium manganese composite oxide particulate composition according to the present invention.

Example 2
Manganese carbonate (spherical, average particle size 10 μm) 105.75 g, chromium nitrate nonahydrate 20.01 g, nickel nitrate hexahydrate 8.72 g (molar ratio Cr / (Mn + Cr + Ni) = 0.05, molar ratio Ni / (Mn + Cr + Ni) = 0.03) was used in the same manner as in Example 1 to obtain manganese trioxide powder in which 5 mol% of chromium and 3 mol% of nickel were substituted and dissolved with respect to manganese atoms. 7.89 g of manganese trioxide powder in which chromium and nickel were dissolved and 4.20 g of lithium hydroxide monohydrate were put in a mortar (molar ratio Li / (Mn + Cr + Ni) = 1.00) and mixed uniformly. The obtained mixture was calcined at 575 ° C. for 15 hours in a nitrogen atmosphere, and lithium manganese composite oxide (LiMn _0.92 Cr _0.05 Ni _0.03 O _{2) in which} 5 mol% of chromium and 3 mol% of nickel were substituted with respect to manganese atoms. ) This product was pulverized by a sample mill for about 20 seconds to deagglomerate the secondary particles to obtain a lithium manganese composite oxide particulate composition according to the present invention.

  An X-ray diffraction chart of this lithium manganese composite oxide particulate composition is shown in FIG. 2 (X-ray source is CuKα ray).

Example 3
Manganese carbonate (spherical, average particle size 10 μm) 105.75 g, chromium nitrate nonahydrate 20.01 g, ammonium molybdate tetrahydrate 5.30 g (molar ratio Cr / (Mn + Cr + Mo) = 0.05, molar ratio Mo /(Mn+Cr+Mo)=0.03) was used in the same manner as in Example 1 to obtain manganese trioxide powder in which 5 mol% of chromium and 3 mol% of molybdenum were substituted and dissolved with respect to manganese atoms. . The manganese trioxide powder 8.00g and lithium hydroxide monohydrate 4.20g (molar ratio Li / ((Mn + Cr + Mo) = 1.00)) in which chromium and molybdenum are dissolved are put in a mortar and mixed uniformly. The obtained mixture was calcined at 610 ° C. for 15 hours in a nitrogen atmosphere, and lithium manganese composite oxide (LiMn _0.92 Cr _0.05 Mo _0.03 O substituted with 5 mol% chromium and 3 mol% molybdenum with respect to manganese atoms). ₂₎ was obtained. the product was ground for about 20 seconds at a sample mill, by solving the aggregation of secondary particles mutually, and a lithium-manganese composite oxide particulate composition according to the invention.

Example 4
Manganese carbonate (spherical, average particle size 10 μm) 105.75 g, chromium nitrate nonahydrate 20.01 g and europium acetate 11.49 g (molar ratio Cr / (Mn + Cr + Eu) = 0.05, molar ratio Eu / (Mn + Cr + Eu) = 0.03) was used in the same manner as in Example 1 to obtain manganese trioxide powder in which 5 mol% of chromium and 3 mol% of europium were substituted and dissolved with respect to manganese atoms. 8.17 g of manganese dioxide powder containing chromium and europium as a solid solution and 4.20 g of lithium hydroxide monohydrate (molar ratio Li / (Mn + Cr + Eu) = 1.00) were put in a mortar and mixed uniformly. The obtained mixture was calcined at 610 ° C. for 15 hours in a nitrogen atmosphere, and lithium manganese composite oxide (LiMn _0.92 Cr _0.05 Eu _0.03 O _{2) in which} 5 mol% of chromium and 3 mol% of europium were substituted with respect to manganese atoms. ) This product was pulverized by a sample mill for about 20 seconds to deagglomerate the secondary particles to obtain a lithium manganese composite oxide particulate composition according to the present invention.

Example 5
Manganese carbonate (spherical, average particle size 10 μm) 105.75 g, chromium nitrate nonahydrate 20.01 g and tungsten oxide 4.64 g (molar ratio Cr / (Mn + Cr + W) = 0.05, molar ratio W / (Mn + Cr + W) = 0.02) was used in the same manner as in Example 1 to obtain manganese trioxide powder in which 5 mol% of chromium and 2 mol% of tungsten were substituted and dissolved with respect to manganese atoms. 8.14 g of manganese sesquioxide powder in which chromium and tungsten were dissolved and 4.20 g of lithium hydroxide monohydrate (molar ratio Li / ((Mn + Cr + W) = 1.00)) were put in a mortar and mixed uniformly. The obtained mixture was calcined at 610 ° C. for 15 hours in a nitrogen atmosphere, and lithium manganese composite oxide (LiMn _0.93 Cr _0.05 W _0.02 O substituted with 5 mol% of chromium and 2 mol% of tungsten with respect to manganese atoms). ₂₎ was obtained. the product was ground for about 20 seconds at a sample mill, by solving the aggregation of secondary particles mutually, and a lithium-manganese composite oxide particulate composition according to the invention.

  An X-ray diffraction chart of this lithium manganese composite oxide particulate composition is shown in FIG. 2 (X-ray source is CuKα ray).

Example 6
Manganese carbonate (spherical, particle size 10 μm) 105.75 g, chromium nitrate nonahydrate 20.01 g, tungsten oxide 4.64 g, aluminum nitrate nonahydrate 3.75 g (molar ratio Cr / (Mn + Cr + W + Al) = 0.05 Molar ratio W / (Mn + Cr + W + Al) = 0.02, molar ratio Al / (Mn + Cr + W + Al) = 0.01), and in the same manner as in Example 1, 5 mol% chromium and tungsten 2 with respect to manganese atoms Manganese sesquioxide powder in which mol% and 1 mol% of aluminum were substituted and dissolved was obtained. 8.11 g of manganese trioxide powder in which chromium, tungsten and aluminum are dissolved, and 4.20 g of lithium hydroxide monohydrate (molar ratio Li / (Mn + Cr + W + Al) = 1.00) are put in a mortar and mixed uniformly. did. The obtained mixture was calcined at 610 ° C. for 15 hours in a nitrogen atmosphere, and lithium manganese composite oxide (LiMn _0.92 Cr) in which 5 mol% of chromium, 2 mol% of tungsten and 1 mol% of aluminum were substituted with respect to manganese atoms. _0.05 W _0.02 Al _0.01 O ₂ ) was obtained. This product was pulverized by a sample mill for about 20 seconds to deagglomerate the secondary particles to obtain a lithium manganese composite oxide particulate composition according to the present invention.

Example 7
Manganese carbonate (spherical, average particle size 10 μm) 105.75 g, chromium nitrate nonahydrate 20.01 g, tungsten oxide 4.64 g, yttrium acetate tetrahydrate 3.38 g (molar ratio Cr / (Mn + Cr + W + Y) = 0. 05, molar ratio W / (Mn + Cr + W + Y) = 0.02, molar ratio Y / (Mn + Cr + W + Y) = 0.01) in the same manner as in Example 1, 5 mol% of chromium and tungsten 2 with respect to manganese atoms Manganese sesquioxide powder in which mol% and yttrium 1 mol% were substituted and dissolved was obtained. 8.17 g of manganese dioxide powder containing chromium, tungsten and yttrium in solid solution and 4.20 g of lithium hydroxide monohydrate (molar ratio Li / (Mn + Cr + W + Y) = 1.00) are put in a mortar and mixed uniformly. did. The obtained mixture was baked at 610 ° C. for 15 hours in a nitrogen atmosphere, and lithium manganese composite oxide (LiMn _0.92 Cr) in which 5 mol% of chromium, 2 mol% of tungsten and 1 mol% of yttrium were substituted with respect to manganese atoms. _0.05 W _0.02 Y _0.01 O ₂ ) was obtained. This product was pulverized by a sample mill for about 20 seconds to deagglomerate the secondary particles to obtain a lithium manganese composite oxide particulate composition according to the present invention.

Example 8
Manganese carbonate (spherical, average particle size 10 μm) 105.75 g, chromium nitrate nonahydrate 20.01 g, tungsten oxide 4.64 g, ammonium molybdate tetrahydrate 1.77 g (molar ratio Cr / (Mn + Cr + W + Mo) = 0 .05, molar ratio W / (Mn + Cr + W + Mo) = 0.02, molar ratio Mo / (Mn + Cr + W + Mo) = 0.01) in the same manner as in Example 1, 5 mol% chromium and tungsten with respect to manganese atoms A manganese trioxide powder in which 2 mol% and 1 mol% of molybdenum were substituted and dissolved was obtained. 8.18 g of manganese trioxide powder in which chromium, tungsten and molybdenum are dissolved and 4.20 g of lithium hydroxide monohydrate (molar ratio Li / (Mn + Cr + W + Mo) = 1.00) are put in a mortar and mixed uniformly. did. The obtained mixture was calcined at 610 ° C. for 15 hours in a nitrogen atmosphere, and lithium manganese composite oxide (LiMn _0.92 Cr) in which 5 mol% of chromium, 2 mol% of tungsten and 1 mol% of molybdenum were substituted with respect to manganese atoms. _0.05 W _0.02 Mo _0.01 O ₂ ) was obtained. This product was pulverized by a sample mill for about 20 seconds to deagglomerate the secondary particles to obtain a lithium manganese composite oxide particulate composition according to the present invention.

Example 9
Manganese carbonate (spherical, average particle size 10 μm) 105.75 g, chromium nitrate nonahydrate 20.01 g and indium oxide 2.78 g (molar ratio Cr / (Mn + Cr + In) = 0.05, molar ratio In / (Mn + Cr + In) = 0.02) was used in the same manner as in Example 1 to obtain manganese trioxide powder in which 5 mol% of chromium and 2 mol% of indium were substituted and dissolved with respect to manganese atoms. 8.00 g of manganese sesquioxide powder in which chromium and indium were dissolved and 4.20 g of lithium hydroxide monohydrate (molar ratio Li / (Mn + Cr + In) = 1.00) were put in a mortar and mixed uniformly. The obtained mixture was calcined at 610 ° C. for 15 hours in a nitrogen atmosphere, and lithium manganese composite oxide (LiMn _0.93 Cr _0.05 In _0.02 O _{2) in which} 5 mol% of chromium and 2 mol% of indium were substituted with respect to manganese atoms. ) This product was pulverized by a sample mill for about 20 seconds to deagglomerate the secondary particles to obtain a lithium manganese composite oxide particulate composition according to the present invention.

Example 10
Manganese carbonate (spherical, average particle size 10 μm) 105.75 g, chromium nitrate nonahydrate 20.01 g, indium oxide 2.78 g, ammonium vanadate 1.17 g (molar ratio Cr / (Mn + Cr + In + V) = 0.05, mol Using the ratio In / (Mn + Cr + In + V) = 0.02 and the molar ratio V / (Mn + Cr + In + V) = 0.01), in the same manner as in Example 1, 5 mol% chromium and 2 mol% indium with respect to manganese atoms And manganese trioxide powder in which 1 mol% of vanadium was substituted and dissolved. Into a mortar, 8.00 g of manganese trioxide powder in which chromium, indium and vanadium are dissolved and 4.20 g of lithium hydroxide monohydrate (molar ratio Li / (Mn + Cr + In + V) = 1.00) are put in a mortar. Mixed. The obtained mixture was calcined at 610 ° C. for 15 hours in a nitrogen atmosphere, and lithium manganese composite oxide (LiMn _0.92 Cr) in which 5 mol% of chromium, 2 mol% of indium and 1 mol% of vanadium were substituted with respect to manganese atoms. _0.05 In _0.02 V _0.01 O ₂ ) was obtained. This product was pulverized by a sample mill for about 20 seconds to deagglomerate the secondary particles to obtain a lithium manganese composite oxide particulate composition according to the present invention.

Example 11
Manganese carbonate (spherical, average particle size 10 μm) 105.75 g, chromium nitrate nonahydrate 20.01 g, indium oxide 2.78 g, nickel nitrate hexahydrate 2.91 g (molar ratio Cr / (Mn + Cr + In + Ni) = 0. 05, molar ratio In / (Mn + Cr + In + Ni) = 0.02, molar ratio Ni / (Mn + Cr + In + Ni) = 0.01), in the same manner as in Example 1, 5 mol% chromium and indium with respect to manganese atoms Manganese sesquioxide in which 2 mol% and 1 mol% of nickel were substituted and dissolved was obtained. 8.00 g of manganese trioxide in which chromium, indium and nickel were dissolved and 4.20 g of lithium hydroxide monohydrate (molar ratio Li / (Mn + Cr + In + Ni) = 1.00) were put in a mortar and mixed uniformly. The obtained mixture was calcined at 610 ° C. for 15 hours in a nitrogen atmosphere, and lithium manganese composite oxide (LiMn _0.92 Cr) in which 5 mol% of chromium, 2 mol% of indium and 1 mol% of nickel were substituted with respect to manganese atoms. _0.05 In _0.02 Ni _0.01 O ₂ ) was obtained. This product was pulverized by a sample mill for about 20 seconds to deagglomerate the secondary particles to obtain a lithium manganese composite oxide particulate composition according to the present invention.

Example 12
Manganese carbonate (spherical, average particle size 10 μm) 105.75 g, chromium nitrate nonahydrate 20.01 g, indium oxide 2.78 g, ammonium molybdate tetrahydrate 1.78 g (molar ratio Cr / (Mn + Cr + In + Mo) = 0) .05, molar ratio In / (Mn + Cr + In + Mo) = 0.02, molar ratio Mo / (Mn + Cr + In + Mo) = 0.01), and in the same manner as in Example 1, 5 mol% of chromium with respect to manganese atoms A manganese trioxide powder in which 2 mol% of indium and 1 mol% of molybdenum were substituted and dissolved was obtained. Put 8.04 g of manganese trioxide powder in which chromium, indium and molybdenum are dissolved and 4.20 g of lithium hydroxide monohydrate (molar ratio Li / (Mn + Cr + In + Mo) = 1.00) into a mortar and mix uniformly. did. The obtained mixture was calcined at 610 ° C. for 15 hours in a nitrogen atmosphere, and lithium manganese composite oxide (LiMn _0.92 Cr) in which 5 mol% of chromium, 2 mol% of indium and 1 mol% of molybdenum were substituted with respect to manganese atoms. _0.05 In _0.02 Mo _0.01 O ₂ ) was obtained. This product was pulverized by a sample mill for about 20 seconds to deagglomerate the secondary particles to obtain a lithium manganese composite oxide particulate composition according to the present invention.

Example 13
Manganese carbonate (spherical, average particle size 10 μm) 105.75 g, chromium nitrate nonahydrate 20.01 g, indium oxide 2.78 g, tungsten oxide 2.32 g (molar ratio Cr / (Mn + Cr + In + W) = 0.05, molar ratio In / (Mn + Cr + In + W) = 0.02, molar ratio W / (Mn + Cr + In + W) = 0.01), in the same manner as in Example 1, 5 mol% of chromium and 2 mol% of indium with respect to manganese atoms Manganese sesquioxide powder in which 1 mol% of tungsten was substituted and dissolved was obtained. 8.13 g of manganese sesquioxide powder in which chromium, indium and tungsten are dissolved and 4.20 g of lithium hydroxide monohydrate (molar ratio Li / (Mn + Cr + In + W) = 1.00) are put in a mortar and mixed uniformly. did. The obtained mixture was calcined at 610 ° C. for 15 hours in a nitrogen atmosphere, and lithium manganese composite oxide (LiMn _0.92 Cr) in which 5 mol% of chromium, 2 mol% of indium and 1 mol% of tungsten were substituted with respect to manganese atoms. _0.05 In _0.02 W _0.01 O ₂ ) was obtained. This product was pulverized by a sample mill for about 20 seconds to deagglomerate the secondary particles to obtain a lithium manganese composite oxide particulate composition according to the present invention.

Comparative Example 1
Manganese carbonate (spherical, average particle size 10 μm) 114.95 g was put in an alumina crucible, calcined in air at 1150 ° C. for 4 hours, cooled, and the resulting mass was pulverized, and further in an oxygen atmosphere, 800 Firing at 10 ° C. for 10 hours gave a manganese trioxide powder. 7.89 g of this manganese dioxide powder and 4.20 g of lithium hydroxide monohydrate (molar ratio Li / Mn = 1.00) were put in a mortar and mixed uniformly, and then the mixture was mixed at 15 ° C. at 575 ° C. in a nitrogen atmosphere. After firing for a time, a lithium manganese composite oxide (LiMnO ₂ ) was obtained. This product was pulverized by a sample mill for about 20 seconds, and secondary particles were agglomerated to obtain a lithium manganese composite oxide particulate composition according to a comparative example.

  An X-ray diffraction chart of this lithium manganese composite oxide is shown in FIG. 2 (X-ray source is CuKα ray).

Comparative Example 2
Manganese carbonate (spherical, average particle size 10 μm) 111.50 g and nickel nitrate hexahydrate 8.72 g (molar ratio Ni / (Mn + Ni) = 0.03) were used in the same manner as in Example 1 to produce manganese atoms. On the other hand, manganese trioxide powder in which 3 mol% of nickel was substituted and dissolved was obtained. 7.91 g of manganese trioxide powder in which nickel is dissolved and 4.20 g of lithium hydroxide monohydrate (molar ratio Li / (Mn + Ni) = 1.00) are put in a mortar and mixed uniformly, and then nitrogen is added. Firing was performed at 575 ° C. for 15 hours in an atmosphere to obtain a lithium manganese composite oxide (LiMn _0.97 Ni _0.03 O ₂ ) in which 3 mol% of nickel was substituted with respect to manganese atoms. This product was pulverized by a sample mill for about 20 seconds, and secondary particles were agglomerated to obtain a lithium manganese composite oxide particulate composition according to a comparative example.

Comparative Example 3
Manganese carbonate (spherical, average particle size 10 μm) 111.50 g and ammonium molybdate tetrahydrate 5.30 g (molar ratio Mo / (Mn + Mo) = 0.03) were used in the same manner as in Example 1 to produce manganese. A manganese sesquioxide powder in which 3 mol% of molybdenum was substituted and dissolved with respect to the atoms was obtained. After 8.02 g of manganese trioxide powder in which molybdenum is dissolved and 4.20 g of lithium hydroxide monohydrate (molar ratio Li / (Mn + Mo) = 1.00) are put in a mortar and mixed uniformly, nitrogen is added. Firing was performed at 610 ° C. for 15 hours in an atmosphere to obtain a lithium manganese composite oxide (LiMn _0.97 Ni _0.03 O ₂ ) in which 3 mol% of molybdenum was substituted with respect to manganese atoms. This product was pulverized by a sample mill for about 20 seconds, and secondary particles were agglomerated to obtain a lithium manganese composite oxide particulate composition according to a comparative example.

Table 1 shows the substitution element species in each of the lithium manganese composite oxide compositions according to Examples 1 to 13 and Comparative Examples 1 to 3, the substitution amount, the lithium stoichiometric ratio, and the firing temperature. Table 2 shows the crystal phase, strength ratio R, tap density, specific surface area, and SEM average particle diameter of each lithium manganese composite oxide composition. Here, the intensity ratio R is the intensity ratio I (orthogonal) / I (monoclinic) in the X-ray diffraction chart, that is, the (010) plane of LiMnO ₂ (JCPDS card No. 35-0749) and LiMnO. ₂ (001) plane intensity ratio of (M. Tabuchi et al., J. Electrochem. Soc., Vol. 145, L49). Identification of the crystal phase was performed using a powder X-ray diffractometer (RAD2C manufactured by Rigaku Corporation, X-ray source CuKα ray).

Example 14
A lithium ion secondary battery for testing was prepared using each of the lithium manganese composite oxide particulate compositions obtained in Example 2, Example 5, Example 9 and Comparative Example 1 as a positive electrode active material. The characteristics were evaluated.

  That is, each active material was uniformly mixed with acetylene black (conductive aid) and polytetrafluoroethylene resin (binder) in a mortar to prepare a mixture. This was punched out into a disk with a diameter of 16 mm with a pressure press and vacuum dried to obtain a positive electrode. A metal lithium foil was used as the negative electrode, and a polypropylene resin film (trade name Celgard) was used as the separator. The electrolytic solution was prepared by dissolving lithium perchlorate at a concentration of 1 mol / L in an EC / DMC (1/1) mixture, and this was impregnated into a separator. These components were assembled into a lithium ion secondary battery for a charge / discharge test as shown in FIG.

Each battery assembled in this way was subjected to a charge / discharge test. The charge / discharge conditions were a current density of 0.2 mA / cm ² , a cut-off voltage of an upper limit of 4.3V, and a lower limit of 2.0V. FIG. 3 shows the transition of the discharge capacity, that is, the cycle characteristics.

  The lithium ion secondary battery using the lithium-manganese composite oxide particulate composition according to the present invention as the positive electrode active material maintains a high discharge capacity with almost no change in the initial capacity even after 20 cycles. is doing. In particular, the lithium ion secondary battery using the lithium manganese composite oxide particulate composition according to Example 5 as the positive electrode active material has a stable initial discharge capacity.

1: Positive electrode 2: Negative electrode 3: Separator 4: Battery container 5: Positive electrode current collector 6: Positive electrode lead wire 7: Negative electrode current collector 8: Negative electrode lead wire

Claims (9)

Formula (I)
Li _x Mn _1-ab Cr _a M _b O _y
(Wherein M is B, Mg, Al, Si, Sc, Ti, V, Fe, Co, Ni, Cu, Zn, Ga, Y, Zr, Nb, Mo, Ru, Sn, Sb, Hf, Ta, Represents at least one element selected from the group consisting of Pb and rare earth elements, and x, y, a and b are respectively
0.8 ≦ x ≦ 1.2,
1.8 ≦ y ≦ 2.4,
0 <a ≦ 0.2,
0.01 ≦ b ≦ 0.2
It is a number that satisfies )
A composite oxide having a monoclinic crystal system, or a composite oxide having a monoclinic crystal system and an orthorhombic crystal composite crystal Lithium manganese composite oxidation characterized in that the intensity ratio R defined by I (orthorhombic) / I (monoclinic) in X-ray diffraction is in the range of 0 to 0.3 A particulate composition. In the composite oxide represented by the general formula (I), x, y, a and b are each
0.8 ≦ x ≦ 1.2,
1.8 ≦ y ≦ 2.4,
0.03 ≦ a ≦ 0.1,
0.01 ≦ b ≦ 0.1
The lithium manganese composite oxide particulate composition according to claim 1, wherein   The lithium manganese composite oxide particulate composition according to claim 1 or 2, wherein M is at least one element selected from the group consisting of Al, V, Co, Ni, Y, Mo, and Eu. The lithium manganese composite oxide particulate composition according to any one of claims 1 to 3, which has a specific surface area of 0.1 to 6.0 m ² / g.   The lithium manganese composite oxide particulate composition according to any one of claims 1 to 3, wherein the tap density is 1.4 to 2.4 g / cc.   The lithium manganese composite oxide particulate composition according to any one of claims 1 to 3, wherein the particle diameter of the secondary particles by SEM observation is in the range of 2 to 50 µm, and the shape of the particles is spherical.   A lithium compound, a trivalent manganese compound, a chromium compound, and a compound of element M (a compound of two or more elements among the compounds of three elements of manganese, chromium, and element M may be a solid solution compound). The lithium manganese composite oxide particle according to any one of claims 1 to 6, comprising a first step of mixing to obtain a mixture and a second step of firing the mixture in an inert gas atmosphere. A method for producing a composition.   The lithium compound is at least one selected from the group consisting of lithium hydroxide, lithium carbonate and lithium nitrate, the trivalent manganese compound is manganese trioxide or manganese oxyhydroxide, and the solid solution compound is an oxide. 8. A process for producing a lithium manganese composite oxide particulate composition according to 7.   In the lithium ion secondary battery provided with the positive electrode, the negative electrode, and the electrolyte, the lithium ion secondary battery which uses the lithium manganese complex oxide particulate composition in any one of Claim 1 to 6 as a positive electrode active material.

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