JP2002241131A - Lithium manganese multiple oxide powder for non- aqueous electrolyte secondary battery, and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a lithium manganese multiple oxide powder hardly generating a gas due to charging/discharging and having excellent charge/discharge property and cycle charge/discharge property, and to provide a manufacturing method therefor. SOLUTION: The lithium manganese multiple oxide powder is expressed by the formula, Li1+aMcMn2-a-cO4.LibXdBeOf, wherein M is aluminum and/or magnesium, X is a halogen element selected from fluorine, chlorine, bromine and iodine, B is boro, and 0<a<=0.1, 1.0<=b<=0.1, 0<a+b<=0.2, 0<c<=0.2, 0<d<=0.05, 0<e<=0.02 and 0<=f<0.1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lithium manganese composite oxide powder used as a positive electrode active material of a non-aqueous electrolyte secondary battery and a method for producing the same.

[0002]

2. Description of the Related Art A lithium ion secondary battery has a higher operating voltage than a conventional nickel cadmium secondary battery and the like.
It has a feature of high energy density and is widely used as a power source for electronic devices. LiCoO ₂ , LiMn are used as a positive electrode active material of this lithium ion secondary battery.
Lithium transition metal composite oxides represented by ₂ O ₄ are exemplified.

[0003] Among them, LiMn ₂ O ₄ has a large amount of manganese which is a constituent element as a resource, and therefore its raw material is easily available at low cost. Also, there is a feature that the load on the environment is small. Furthermore, even if all the Li ions in the crystal are desorbed by the deintercalation reaction, the crystal structure is stably present. Therefore, compared to LiCoO ₂ , L
A secondary battery using iMn ₂ O ₄ has little risk of heat generation and ignition in an overcharged state, and is excellent in safety.

However, LiMn ₂ O ₄ has a problem in that manganese ions are eluted into the electrolytic solution due to the crystal structure during charge and discharge. Manganese ions eluted in this electrolyte
Precipitates on the surface of the negative electrode, hinders insertion and desorption of lithium ions, and particularly causes a decrease in discharge capacity in cycle charge and discharge. Further, it is said that the eluted manganese ions promote the decomposition reaction of the ester compound in the electrolytic solution, and CO ₂ gas is generated by the decomposition, causing swelling of the battery. In recent years, a laminated secondary battery using an aluminum film for the exterior and an ultra-thin secondary battery in which the thickness of the exterior can is reduced have been released for mobile phones. In particular, when LiMn ₂ O ₄ is used for such a thin secondary battery,
The swelling of the battery is conspicuous and poses a problem. Further, the elution of manganese ions into the electrolytic solution appears remarkably at high temperatures. For this reason, LiMn ₂ O ₄ has a problem that the battery swells particularly at a high temperature and the charge / discharge characteristics, storage characteristics, and cycle charge / discharge characteristics are inferior.

In order to solve the above problems, LiM
There is known a technique in which another element is added to n ₂ O ₄ to stabilize the crystal structure, thereby suppressing elution of manganese ions and improving cycle charge / discharge characteristics and the like. For example, a technical report requiring the addition of a metal element or a transition metal element having an atomic number of 11 or more (Japanese Patent Laid-Open No. 11-171550)
And so on.

Further, the particle diameter of LiMn ₂ O ₄ is increased,
A technique has also been proposed in which the surface area is reduced to reduce the number of reactive sites with the electrolytic solution and to suppress the elution of manganese ions. For example, there is a technical report (JP-A-2000-12031) in which the average particle diameter and the specific surface area are specified.

[0007]

However, in the above-described technique of adding a metal element, the initial discharge capacity tends to decrease with the addition amount of the metal element, and the battery characteristics such as cycle charge / discharge characteristics and high temperature characteristics are reduced. There is a trade-off relationship with the initial discharge capacity.

Further, the above-mentioned LiMn having a large particle diameter is used.₂
O₄In the technology using, the particle size is usually increased in the manufacturing process.
Heat the raw material mixture at high temperature for a long time
Is used. In this method, LiMn₂O₄Powder
Increasing the proportion of coarse particles composed of secondary particles in the body
There is a direction. LiMn containing a large amount of coarse particles
₂O₄When powder is used, current is collected in the positive electrode plate manufacturing process.
Poor binding to the body and poor smoothness of the coating surface
I will. As a result, elution of manganese ions is suppressed.
Also, peeling of the coating film surface occurs. This allows the battery
Internal resistance increases, charging and discharging characteristics, storage characteristics, cycle charging
This leads to a decrease in discharge characteristics. Large particle size
Using a manganese compound as a raw material, large particles of LiMn₂
O ₄There is also a method of manufacturing. In this method, the raw material
Poor reactivity between cancer compounds and lithium compounds
Is uniform LiMn₂O₄Is difficult to obtain. others
Even for large particles, the crystal structure is not stable,
Pond characteristics cannot be improved sufficiently.

As described above, a technique for resolving all the problems of battery swelling due to gas generation during charge / discharge, particularly at high temperatures, and charge / discharge characteristics, storage characteristics, and cycle charge / discharge characteristics, is not enough. It has not been established yet and has not yet reached the level of practical use. An object of the present invention has been made in view of the above circumstances. In other words, it is possible to produce a positive electrode coating surface with excellent binding properties to the current collector and good smoothness, and there is almost no generation of gas during charging and discharging, and charging and discharging characteristics, storage characteristics, and cycle charging and discharging characteristics Another object of the present invention is to provide a lithium manganese composite oxide powder having excellent battery characteristics, especially at high temperatures, and a method for producing the same.

[0010]

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, added a specific element to the cubic spinel-type lithium manganate, and added the composition ratio of each constituent element and the powder. By optimizing the specific surface area of the body and the particle size distribution characteristics of the powder, all of the charge and discharge characteristics, especially storage characteristics at high temperatures, cycle charge and discharge characteristics, and battery swelling due to gas generation during charge and discharge are all Find things that can be improved,
The present invention has been completed.

That is, the objects of the present invention are as follows:
This can be achieved by the configuration of (5). (1) In formula _{Li 1 + a M c Mn 2} -a-c O 4 · Li
_{b X d B e O f (} M is aluminum and / or magnesium, X is fluorine, chlorine, bromine, at least one halogen element selected from iodine, B is boron, 0 <a ≦
0.1, 0 ≦ b ≦ 0.1, 0 <a + b ≦ 0.2, 0 <c
≦ 0.2, 0 <d ≦ 0.05, 0 <e ≦ 0.02, 0 ≦
f <0.1), wherein the lithium manganese composite oxide powder is represented by the formula:

(2) Li _{1 + a} M _c Mn in the above general formula
_2-a-c O ₄ parts are cubic spinel-type lithium _{manganate, Li b X d B e O} f unit is characterized by an impurity phase consisting of one or more water-soluble compound The lithium manganese composite oxide powder according to the above (1).

(3) The specific surface area of the lithium manganese composite oxide powder is 0.3 m ² / g or more, and 1.2 m ² / g.
The lithium manganese composite oxide powder according to the above (1) or (2), wherein: Here, the specific surface area of the lithium manganese composite oxide powder of the present invention is preferably measured by a nitrogen gas adsorption method.

(4) The proportion of particles having a volume-based particle diameter of 50 μm or more in the lithium manganese composite oxide powder is as follows:
The lithium manganese composite oxide powder according to any one of (1) to (3), which is 10% by volume or less of all particles. The volume-based particle diameter of the lithium manganese composite oxide powder of the present invention is preferably measured by a laser diffraction scattering method.

(5) lithium compound, manganese compound,
The lithium manganese composite oxide powder according to any one of (1) to (4), wherein a raw material mixture obtained by mixing a boron compound, a halogen compound, and an aluminum compound and / or a magnesium compound is subjected to heat treatment. how to.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the lithium manganese composite oxide powder of the present invention and a method for producing the same will be described in detail. The lithium manganese composite oxide powder of the present invention contains 16
The powder is a powder mainly composed of cubic spinel-type lithium manganate crystals in which part of manganese occupying the octahedral site c is replaced with lithium and / or aluminum and / or magnesium, and further containing a halogen element and boron.

First, the cubic spinel-type lithium manganate constituting the lithium manganese composite oxide powder of the present invention will be described. By substituting a part of manganese in this crystal with aluminum and / or magnesium,
The swelling of the battery can be suppressed. Although the reason is not clear, it is presumed that the crystal structure is stabilized, the elution of manganese is suppressed, and the generation of CO ₂ gas due to the decomposition of the electrolytic solution is suppressed.

In the cubic spinel-type lithium manganate, lithium occupies the tetrahedral site 8a. However, if lithium is added in excess of the stoichiometric composition ratio,
Some of the excess lithium is in 16c where manganese is present.
It is known to occupy the octahedral site. By adding lithium in excess of the stoichiometric composition ratio, part of manganese can be replaced with lithium.

The cubic spinel type lithium manganate 1
When part of the manganese occupying the octahedral site of 6c is replaced with lithium in addition to aluminum or magnesium, the cycle charge / discharge characteristics are improved. Although the reason for this effect is not clear, the substitution of lithium with manganese reduces the lattice constant, shrinks the spinel structure, increases the ionic bonding force, and further stabilizes the crystal structure. It is thought to be.

However, the object of the present invention cannot be achieved only by partially replacing manganese with lithium and aluminum and / or magnesium. The following (1)-
There was the problem shown in (4). (1) The initial discharge capacity tends to decrease with the addition amount. (2) The particle diameter tends to be small and the specific surface area tends to increase with the amount of addition. (3) The cycle charge / discharge characteristics are not sufficiently improved. (4) The binding property with the current collector tends to be poor. Therefore, in the present invention, the above problem was solved by further adding boron and a halogen element and standardizing the specific surface area and the particle size distribution characteristics of the lithium manganese composite oxide powder.

That is, when boron, which is a constituent element of the present invention, is heated in a manufacturing process together with a manganese compound, a lithium compound or the like as a raw material, it reacts with lithium to form a compound composed of lithium, boron and oxygen. . Since this compound acts as a flux (flux), the lithium manganese composite oxide promotes crystal growth and increases crystallinity. Further, since the sintering of the crystal particles proceeds, a lithium manganese composite oxide powder having a large particle diameter is obtained. In order to increase the particle diameter as in the prior art, there is no need to perform heat treatment at a high temperature for a long time, and it is not necessary to use a raw material having a large particle diameter.

Therefore, by adding boron to the constituent element, a lithium manganese composite oxide powder having excellent crystallinity, a large particle diameter, a small specific surface area, and free from coarse particles formed by secondary aggregation can be obtained. . As sintering progresses and the crystals become denser, the crystal structure stabilizes,
Cycle charge / discharge characteristics and storage characteristics are improved.

However, a sufficient effect cannot be obtained only by adding boron. The present invention is intended to achieve the object of the present invention by further adding a halogen element. Although the reason is not clear, when boron and a halogen element are given to the constituent elements, when the boron acts as a flux as described above, the halogen element segregates on the particle surface and has an effect of improving the particle properties. That is, by using both boron and a halogen element, a lithium manganese composite oxide powder having excellent crystallinity, a small specific surface area, containing no coarse particles, and being spherical thereon and having a uniform particle diameter can be obtained.

By making the powder spherical and having a uniform particle size, the mixing property with the conductive agent powder represented by the carbon material is improved when producing the positive electrode plate, and the internal resistance of the battery is reduced. For this reason, the charge and discharge characteristics, particularly the discharge capacity, are improved.
Also, when kneaded with a binder, the lithium manganese composite oxide powder of the present invention has excellent fluidity, easily entangles with the polymer of the binder, and has excellent binding properties. Furthermore, since it does not contain coarse particles and is spherical, the surface of the coating surface of the positive electrode is excellent in smoothness. As a result, the coating surface of the positive electrode plate has excellent binding properties and is difficult to peel off, and the surface is smooth and lithium ions enter and exit uniformly on the coating film surface during charge and discharge, so there is a marked improvement in cycle charge and discharge characteristics. Is obtained.

The effects obtained by adding the respective elements constituting the lithium manganese composite oxide powder of the present invention have been described above. In Table 1, ○ indicates an effect, Δ indicates almost no effect, and × indicates deterioration.

[0026]

[Table 1]

The above-mentioned constituent elements compensate for the respective disadvantages, and when used simultaneously, a remarkable synergistic effect can be obtained. This aims to achieve the object of the present invention,
The purpose cannot be achieved simply by adding the above elements. That is, the object can be achieved only by optimizing the composition ratio of each constituent element, the specific surface area of the powder, and the particle size distribution characteristics as described below.

The lithium manganese composite oxide powder of the present invention has the general formula Li _{1 + a Mc} Mn _{2 -ac} O ₄ .Li _b
Represented by X _d B _e O _f. In the general formula, M represents aluminum and / or magnesium, and X represents a halogen element.

Furthermore the lithium manganese composite oxide powder of the present invention, in the general formula _{Li 1+} a _M c Mn
And _{2-a-c O 4} cubic spinel-type lithium manganate represented _by, and a Li _b X _{d B} e _O soluble impurity phase represented by _f. That is, the boron and the halogen element contained in the lithium manganese composite oxide powder of the present invention do not form a solid solution in the crystals of the cubic spinel-type lithium manganate, but exist as an impurity phase. Lithium, a halogen element, boron, compounds containing oxygen as constituent elements include lithium oxide, boron oxide, lithium halide, boron halide, etc., all of which are water-soluble, and the impurity phase is lithium, a halogen element, It is composed of one or more water-soluble compounds containing boron and oxygen as constituent elements.

The composition ratio of each element constituting the lithium manganese composite oxide powder of the present invention is determined and calculated by the following method. The lithium manganese composite oxide powder is dissolved in nitric acid, and the content of each constituent element is quantified by a plasma emission spectroscopy (hereinafter, referred to as ICP) analysis method. The content of the lithium, boron and halogen elements in the impurity phase is such that the cubic spinel-type lithium manganate, which is the main component of the lithium manganese composite oxide powder of the present invention, is insoluble in pure water, Is determined using the fact that it consists of a water-soluble compound. Specifically, a predetermined amount of lithium manganese composite oxide powder is added to pure water and stirred. At this time, lithium, boron, and halogen elements eluted from the lithium manganese composite oxide powder into pure water are quantified, and the contents of each element constituting the impurity phase are determined.

From the contents of the respective constituent elements of the lithium manganese composite oxide powder determined by the above method and the contents of the lithium, boron and halogen elements in the impurity phase in the powder,
Formula _{Li 1 + a M c Mn 2} -a-c O 4 · Li b X d
B _e O _f (M is Al and / or Mg, X is a halogen element) calculates the composition ratio of the respective elements in the. The composition ratio of lithium in the lithium manganese composite oxide powder (1 + a
+ B) from the composition ratio of lithium in the impurity phase in the powder (b)
Is defined as the composition ratio (1 + a) of lithium in the cubic spinel-type lithium manganate as the main component.

Next, the composition ratio of each constituent element will be described. Formula _Li 1 representing a lithium-manganese composite oxide powder of the present invention _{+ a M c Mn 2-a} -c O 4 · Li b X d B
In _e O _f, the total amount of aluminum or magnesium or aluminum and magnesium, is represented by a composition ratio c in the general formula, 0 <a range of c ≦ 0.2, preferably 0.05 ≦ c ≤ 0.15. As the amount of addition of aluminum and magnesium increases, the generation of gas decreases, and the swelling of the battery is suppressed. However, c>
In the case of 0.2, even if the amount of addition increases, the amount of generated gas is almost the same. In addition, a decrease in discharge capacity due to an increase in the amount of addition is notable, which is not preferable.

The lithium manganese composite oxide of the present invention
General formula Li representing powder_{1 + a}M_cMn_2-acO₄・
Li_bX_dB_eO_fIn the above, the composition ratio of lithium is
Represented by (1 + a) + b in the general formula, 0 <a + b
Satisfies ≦ 0.2. Where a is a cubic spinel manga
Of the lithium in the lithium phosphate crystals, LiMn₂O ₄
Lithium contained in excess of the stoichiometric composition represented by
Shows the composition ratio of the system. The composition ratio of lithium represented by a
Replaces some of the manganese that occupies the 16c octahedral site
0 <a ≦ 0.1, preferably
0.02 ≦ a ≦ 0.08. Aluminum, magne
Lithium occupies 16c octahedral site with lithium
Synergistic effect can be obtained by substituting part of manganese
As a result, cycle charge / discharge characteristics are improved. However, a> 0.
In the case of 1, even if the amount of addition increases, the amount of generated gas is almost the same.
In addition, the decrease in discharge capacity due to the
Is not preferred. The lithium manganese composite oxidation
Composition ratio of lithium in the general formula (1+
a) + b, b is a cubic spinel-type lithium manganate
Composition of lithium in the impurity phase existing outside the crystal of aluminum
Indicates a ratio, where 0 ≦ b ≦ 0.1.

The general formula _Li 1 representing a lithium-manganese composite oxide powder of the present invention _{+ a + b M c Mn 2} -a-c X d B
_{In e} O _{4 + f} , B represents boron, and e represents the composition ratio of boron. The composition ratio e of this boron is 0 <e ≦ 0.
02, preferably 0.001 ≦ e ≦ 0.01. This boron acts as a flux when the raw material compound is heat-treated, promotes crystal growth, and sintering proceeds. For this reason, as the amount of boron added increases, the lithium manganese composite oxide powder becomes better in crystallinity and becomes larger. As a result, cycle charge / discharge characteristics and storage characteristics are improved. However, when the amount of boron is e> 0.0 in the composition ratio in the formula,
In the case of 2, the cycle charge / discharge characteristics decrease as the amount of boron increases. Further, the generation of gas at the time of charge and discharge becomes remarkable, and the effect of suppressing the expansion of the battery is lost, which is not preferable.

The general formula Li _{1 + a Mc} Mn _2-ac O _4.
In _{Li b X d B e O f} , X represents fluorine, chlorine, bromine, at least one kind of halogen element selected from iodine, d represents the composition ratio thereof. The halogen element may be used alone or in combination of two or more of the above. Particularly, fluorine and chlorine are preferred. Halogen composition ratio d
Is in the range of 0 <d ≦ 0.05, preferably 0.0
01 ≦ d ≦ 0.03. The halogen element has an effect of turning the lithium manganese composite oxide powder into a spherical powder having a uniform particle size. When used together with boron, a lithium manganese composite oxide powder which is large and does not include coarse secondary particles, and is spherical and uniform in particle size is obtained. This results in excellent surface smoothness, low internal resistance,
In addition, a positive electrode coating surface having excellent binding properties can be formed, and charge / discharge characteristics and cycle charge / discharge characteristics are significantly improved. But d>
A value of 0.05 is not preferred because the cycle charge / discharge characteristics are almost constant and the discharge capacity is significantly reduced even when the amount of the halogen element is increased.

Further, a general formula Li _{1 + a Mc} Mn _2-ac O ₄ representing the lithium manganese composite oxide powder of the present invention.
In _{· Li b X d B e O} f, the oxygen composition ratio of the impurity phase (f) is calculated by the following formula (I). It is determined by the composition ratio of lithium, boron and halogen elements constituting the impurity phase, and 0 ≦ f <0.1.

Further, the lithium manganese composite oxide powder of the present invention can obtain more excellent battery characteristics by standardizing the specific surface area and the particle size distribution characteristics. That the specific surface area of the powder particles 0.3 m ² / g or more, 1.2 m ² /
g or less. More preferably 0.4
m ² / g or more, 0.9 m ² / g or more. Here, the lithium manganese composite oxide powder of the present invention is preferably measured by a nitrogen gas adsorption method. If the specific surface area of the powder particles is less than 0.3 m ² / g, the particle size is too large, and diffusion of lithium ions in the solid during charging and discharging does not easily proceed, and the discharge capacity decreases. On the other hand, when the particle size is 1.2 m ² / g or more, the particle size is small, so that the charge / discharge characteristics and cycle charge / discharge characteristics are not improved.

Further, the proportion of particles having a volume-based particle diameter of 50 μm or more in the lithium manganese composite oxide powder of the present invention is preferably 10% by volume or less of all the particles. As a result, a positive electrode coating surface having excellent smoothness can be obtained because it does not contain coarse particles composed of secondary aggregates.

Methods for measuring the particle size distribution of the powder include, for example, a sieving method, an image analysis method, a sedimentation method, a laser diffraction scattering method, and an electrical detection method. Each measurement method has advantages and disadvantages, and a method suitable for the purpose of measurement is used.
Among the methods for measuring the particle size of the powder particles, the laser diffraction scattering method has features such as easy measurement and reproducibility of the measurement result. It is preferable as a method for measuring the particle diameter.

The raw material mixture for producing the lithium manganese composite oxide powder of the present invention is obtained by mixing a lithium compound, a manganese compound, a boron compound, a halogen compound, and an aluminum compound and / or a magnesium compound. It is manufactured by subjecting this raw material mixture to heat treatment. The production method of the present invention will be described in detail below.

(Preparation of Raw Material Mixture)
The lithium compound to be used is Li₂CO₃, LiOH,
Li₂O, LiCl, LiNO₃, Li₂SO₄, Li
HCO₃, Li (CH₃COO) or the like is used. Homogeneously
From the point that heat treatment can be performed, Li₂CO₃Use
Is preferred. As the manganese compound, MnO
₂, MnCO₃, Mn₂O₃, Mn₃O ₄Etc. are used
However, there is no particular limitation.

As the magnesium compound, MgO, M
gCo ₃ , Mg (OH) ₂ , MgCl, MgSO ₄ , M
g (NO ₃ ) ₂ , Mg (CH ₃ COO) _{2 and the} like are used. As the aluminum compound, Al ₂ O ₃ ,
Al (NO ₃ ) ₃ , Al ₂ (SO ₄ ) ₃ , Al ₂ (CO
₃ ) ₃ , Al (CH ₃ COO) _{3 and the} like are used.

As the boron compound used in the present invention, B ₂ O ₃ (melting point: 460 ° C.) and H ₃ BO ₃ (decomposition temperature: 173 ° C.) are preferable. Examples of the compound containing a halogen element include NH ₄ F, NH ₄ Cl, NH ₄ Br, NH ₄ I,
LiF, LiCl, LiBr, LiI, MnF ₂ , Mn
Cl ₂ , MnBr ₂ , MnI _{2 and the} like are preferable. The above-mentioned lithium compound, manganese compound, boron compound, halogen compound, and aluminum compound and / or magnesium compound are mixed so that each constituent element has a predetermined composition ratio. At this time, the powdery compound may be mixed as it is, or may be mixed as a slurry using water or an organic solvent. The slurry mixture is dried to obtain a raw material mixture.

(Heat Treatment of Raw Material Mixture) The raw material mixture thus obtained is heated in air or a weakly oxidizing atmosphere.
A heat treatment is performed at a temperature of 400 to 1000 ° C. for 1 to 24 hours to synthesize a lithium manganese composite oxide powder. The temperature of the heat treatment is preferably from 700 to 900C, and the time of the heat treatment is preferably from 6 to 12 hours. Heat treatment temperature is 4
If the temperature is lower than 00 ° C., unreacted raw materials remain in the lithium manganese composite oxide powder, and sufficient characteristics for achieving the object of the present invention cannot be obtained. When heat treatment is performed at a temperature higher than 900 ° C., Li ₂ MnO ₃ or LiMnO _{3
2 and} other by-products are likely to be generated, resulting in a decrease in discharge capacity,
This causes a decrease in cycle charge / discharge characteristics and a decrease in operating voltage. If the time of the heat treatment is less than 1 hour, the diffusion reaction between the particles of the raw material mixture does not proceed, and the desired lithium manganese composite oxide powder cannot be obtained. Even if the heat treatment is performed for more than 24 hours, the diffusion reaction has already been completed, and there is no need to perform any further heat treatment.

The lithium manganese composite oxide powder obtained by the above heat treatment may be pulverized with a grinder, a ball mill, a vibration mill or the like. Obtaining the lithium manganese composite oxide powder of the present invention in which the specific surface area is 0.3 to 1.2 m ² / g and the ratio of particles having a volume-based particle diameter of 50 μm or more is 10% or less of all particles by the above method. Can be.

[0046]

Hereinafter, embodiments of the present invention will be described.
The present invention is not limited to only specific examples. [Example 1] Lithium carbonate (L
i ₂ CO ₃ ), electrolytic manganese dioxide (MnO ₂ ), aluminum oxide (Al ₂ O ₃ ), boron oxide (B
₂ O ₃ ) and ammonium chloride (NH ₄ Cl). Here, a powder having a volume-based 50% diameter of 3 μm was used as electrolytic manganese dioxide. General formula Li _{1 + a} M _c Mn
_{2-a-c O 4 ·} Li b X d B e O f (M is Al and /
Alternatively, Mg and X represent a halogen element. ), L
The composition ratio of i is 1 + a + b = 1.08, and the composition ratio of Al is c =
The compounds as raw materials were weighed and dry-mixed so that the composition ratio of 0.10, Cl was d = 0.005, and the composition ratio of B was e = 0.005. The obtained raw material mixture was subjected to a heat treatment at 850 ° C. for 10 hours in an air atmosphere. Then, it is ground in a raikai mortar, and the specific surface area of the powder is 0.5 m ² /
g, the ratio of particles having a volume-based particle diameter of 50 μm or more is 0%.
Was obtained. The specific surface area and the particle size distribution of the lithium manganese composite oxide powder were measured by a method for evaluating a powder described later.

Example 2 Of the compounds used as raw materials, magnesium carbonate (MgCO 3) was used instead of aluminum oxide.
₃ ) is used and the composition ratio of Li is 1 + a + b = 1.14;
When the composition ratio of Mg is c = 0.01 and the composition ratio of Cl is d = 0.
005, except that the respective compounds as raw materials were weighed and mixed so that the composition ratio of boron becomes e = 0.005, and the specific surface area of the powder was 0.6 m ² / g in the same manner as in Example 1. A lithium manganese composite oxide powder having a volume-based particle diameter of 50% or more and a proportion of particles of 0% was obtained.

Example 3 Of the compounds used as raw materials, ammonium fluoride (NH ₄₎ was used instead of ammonium chloride.
Except for using F), a lithium manganese composite oxide powder having a specific surface area of 0.5 m ² / g and a proportion of particles having a volume-based particle diameter of 50 μm or more of 6% was obtained in the same manner as in Example 1. Was.

Example 4 The composition ratio of Al was c = 0.15.
In the same manner as in Example 1 except that aluminum oxide as a raw material is weighed and mixed so as to obtain a specific surface area of 0.1.
A lithium manganese composite oxide powder having a volume ratio of particles of 7 m ² / g and a volume-based particle diameter of 50 μm or more was 0% by volume was obtained.

Example 5 The procedure of Example 1 was repeated, except that boron oxide as a raw material was weighed and mixed so that the composition ratio of B became e = 0.01, and the specific surface area was 0.5 m. ² /
g, the ratio of particles having a volume-based particle diameter of 50 μm or more is 2
% Lithium manganese composite oxide powder was obtained.

Example 6 The composition ratio of Cl was d = 0.01.
5 in the same manner as in Example 1 except that ammonium chloride as a raw material was mixed so as to obtain a specific surface area of 0.5 m ^2.
/ G, the ratio of particles having a volume-based particle diameter of 50 μm or more is 6
% Lithium manganese composite oxide powder was obtained.

Example 7 The specific surface area was 0.7 m ² / g, and the volume-based particle diameter was the same as in Example 1, except that the 50% diameter based on volume of the electrolytic manganese dioxide as the raw material was 15 μm. Was 5% or more, and the ratio of particles was 5%.

Example 8 Of the compounds as raw materials,
Manganese oxide (Mn) instead of decomposed manganese dioxide
₂O₃)), Except that the ratio
0.7m surface area²/ G, volume-based particle size 50 μm or less
Lithium-manganese composite oxide powder with 0% of the particles above
The end was obtained.

Example 9 Of the compounds as raw materials,
Manganese oxide (Mn) instead of decomposed manganese dioxide
₃O₄)), Except that the ratio
0.4m surface area²/ G, volume-based particle size of 50 μm or less
Lithium manganese composite oxide powder with 3% of the above particles
The end was obtained.

Comparative Example 1 A specific surface area of 4.2 m ² / g and a volume-based particle diameter of 50 μm were obtained in the same manner as in Example 1 except that ammonium chloride and boron oxide were not used among the starting compounds. As a result, a lithium manganese composite oxide powder containing 0% of the above particles was obtained.

Comparative Example 2 Particles having a specific surface area of 0.7 m ² / g and a volume-based particle diameter of 50 μm or more were prepared in the same manner as in Example 1 except that ammonium chloride was not used among the starting compounds. Of 5% lithium manganese composite oxide powder was obtained.

[Comparative Example 3] In the same manner as in Example 1 except that boron oxide was not used among the starting compounds,
Specific surface area is 1.7 m ² / g, volume-based particle diameter is 50 μm
As a result, a lithium manganese composite oxide powder containing 0% of the above particles was obtained.

Comparative Example 4 The same procedures as in Example 3 were carried out except that ammonium chloride and boron oxide were not used among the starting compounds, and the specific surface area was 3.6 m ² / g and the volume-based particle diameter was 50 μm. A lithium manganese composite oxide powder having a ratio of the above particles of 15% was obtained.

The lithium manganese composite oxide powders obtained in Examples 1 to 9 and Comparative Examples 1 to 4 were subjected to composition analysis, specific surface area measurement and particle size distribution measurement by the following methods. In addition, a positive electrode plate and a test battery were prepared, and each evaluation was performed. (Composition analysis) First, a predetermined amount of lithium manganese composite oxide powder was dissolved in nitric acid, and the content of each constituent element was quantified by a plasma emission spectroscopy (hereinafter, referred to as ICP) analysis method. As a result of the measurement, the composition ratio of each constituent element of the lithium manganese composite oxide powder manufactured in this example was the same as the composition ratio of each constituent element when the compound as a raw material was weighed.

Next, the contents of Li, B and halogen elements in the impurity phase contained in the lithium manganese composite oxide powder of the present invention were determined by the following method. First, 5 g of lithium manganese composite oxide powder was added to 20 g of pure water, and the mixture was stirred for 1 hour with a magnetic stirrer. Next, after filtering the lithium manganese composite oxide powder, a predetermined amount of the supernatant aqueous solution was taken, and Li and B eluted in pure water were quantified by ICP analysis. The halogen element eluted in pure water was quantified with a spectrophotometer. The amounts of Li, B, and halogen elements eluted in the pure water were defined as the contents of the respective constituent elements of the impurity phase. The fact that the cubic spinel-type lithium manganate, which is the main component of the lithium manganese composite oxide powder of the present invention, is insoluble in pure water, whereas the impurity phase is water-soluble, The content of each constituent element was determined.

From the contents of the respective constituent elements of the lithium manganese composite oxide powder determined by the above method and the contents of Li, B and halogen in the impurity phase in the powder, the general formula Li
_{1 + a M c Mn 2-} a-c O 4 · Li b X d B e O
The composition ratio of each constituent element in _f (M is Al and / or Mg, X is a halogen element) was calculated. The value (1+) obtained by subtracting the composition ratio (b) of Li in the impurity phase from the composition ratio (1 + a + b) of Li in the lithium manganese composite oxide powder.
a) was defined as the composition ratio of Li in the cubic spinel-type lithium manganate as a main component. The composition ratio f of oxygen in the impurity phase was calculated by the following equation (I).

(Evaluation of Powder) The specific surface area of the obtained lithium manganese composite oxide powder was measured by a constant pressure BET adsorption method using nitrogen gas. The 50% diameter was determined by measuring the particle size distribution by a laser diffraction scattering method, obtaining an integrated distribution using an exponential logarithm of the particle diameter on a volume basis, and obtaining a particle diameter at which the integrated value becomes 0.5 in this integrated distribution. . The ratio of particles having a particle diameter of 50 μm or more was also determined from the volume-based integrated distribution.

(Preparation of Positive Electrode Plate and Evaluation of Coating Surface) 90 parts by weight of lithium manganese composite oxide powder as a positive electrode active material, 2.5 parts by weight of acetylene black powder as a conductive agent, and 2.5 parts by weight of carbon powder And 5 parts by weight of polyvinylidene fluoride were kneaded to prepare a paste, which was applied to an aluminum electrode plate by a doctor blade method and dried to obtain a positive electrode plate. The obtained positive electrode plate was cut into 5 cm ² , the weight of the electrode plate was measured, and the thickness of the positive electrode coating surface was measured with a film thickness gauge. Then, the density of the positive electrode coating surface was calculated.
Furthermore, visually observe the surface condition of the coating film surface,
The smoothness was evaluated.

(Preparation of Lithium Ion Secondary Battery) A positive electrode plate obtained by the above method, a lithium metal as a negative electrode, a porous propylene film as a separator, and ethylene carbonate: diethyl carbonate = 1: 1 (electrolyte) were used. 1 m of LiPF _{6 in} the mixed solvent (volume ratio)
A lithium ion secondary battery was manufactured using a solution dissolved at a concentration of ol / l. In this example, a positive electrode plate, a negative electrode plate, and a separator were formed into a thin sheet shape, and these were wound and stored in a battery case made of a metal laminated resin film to obtain a laminated battery.

(Evaluation of Expansion Rate of Battery) A laminate type battery was charged at 60 ° C. with a constant current of 0.5 C at a constant current up to 4.3 V, and then charged and discharged at a current density of 1.0 C up to 3.0 V. Cycled. The expansion rate (%) of the battery due to the generation of gas was determined from the following equation (II). Here, 1.
0C is a current density at which charging or discharging is completed in one hour.

(Evaluation of Cycle Charge / Discharge Characteristics) The prepared laminated battery was charged at 60 ° C. at a charge density of 0.5 C to 4.3.
After charging at a constant current to V, charging and discharging at 1.0 C to 2.75 V were performed for 300 cycles, and the capacity maintenance ratio (%) at the 300th cycle was determined from the following equation (III).

Table 2 shows the composition ratio and powder characteristics obtained by ICP analysis. Table 3 shows the results of the electrode plate evaluation and the battery characteristics. The mark x in the electrode plate evaluation in Table 3 indicates that the surface of the coating film surface is not smooth and has cracks.

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[Table 2]

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[Table 3]

In Tables 2 and 3, Comparative Example 1 does not contain boron and halogen elements and has a large specific surface area.
For this reason, when kneading with the binder, the viscosity of the slurry increases, the coating surface of the produced positive electrode plate is not smooth, and the density of the electrode plate is low due to poor powder filling. Comparative Example 4 also did not contain a halogen element, had a large specific surface area, and contained 15% by volume of coarse particles larger than 50 μm. For this reason, the produced positive electrode plate had a non-smooth coating film surface, and particularly cracks were observed. Comparative Examples 1 and 4
Since it does not contain boron and has poor crystallinity, the initial discharge capacity is low. Further, the expansion rate of the battery is high, and the decrease in discharge capacity due to cycle charge / discharge is large.

Comparative Example 2 contains boron in addition to aluminum, and has a smaller specific surface area than Comparative Examples 1 and 4. Further, with the improvement of the crystallinity, the initial discharge capacity was increased as compared with Comparative Examples 1 and 4. In Comparative Example 3, chlorine was contained in addition to aluminum, the particle shape was improved, the packing density of powder was improved, and the electrode density of the positive electrode plate was improved as compared with Comparative Examples 1 and 4.

However, Comparative Examples 1 to 4 cannot satisfy all of the smoothness of the coating surface of the positive electrode plate, charge / discharge characteristics, suppression of battery swelling, and cycle charge / discharge characteristics. As shown in Examples 1 to 6, the object of the present invention can be achieved for the first time with the lithium manganese composite oxide powder of the present invention.

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As described above, by using the lithium manganese composite oxide powder of the present invention, it is possible to produce a positive electrode coating surface having excellent binding property to a current collector and good smoothness, In particular, excellent swelling of the battery at high temperatures and excellent cycle charge / discharge characteristics were all achieved. Further, a lithium manganese composite oxide powder having excellent battery characteristics can be provided by the production method of the present invention.

Claims (5)

[Claims] 1. A lithium transition metal composite oxide used in a non-aqueous electrolyte secondary battery, comprising a general formula Li _{1 + a Mc} M
_{n 2-a-c O 4} · Li b X d B e O f (M is aluminum and / or magnesium, X is fluorine, chlorine, bromine, at least one halogen element selected from iodine, B is boron, 0 <a ≦ 0.1, 0 ≦ b ≦ 0.1, 0
<A + b ≦ 0.2, 0 <c ≦ 0.2, 0 <d ≦ 0.0
5, 0 <e ≦ 0.02, 0 ≦ f <0.1), characterized in that the lithium manganese composite oxide powder. 2. The method according to claim 1, wherein Li _{1 + a} M _c Mn
_2-a-c O ₄ parts are cubic spinel-type lithium _{manganate, Li b X d B e O} f unit is characterized by an impurity phase consisting of one or more water-soluble compound The lithium manganese composite oxide powder according to claim 1. 3. A ratio of the lithium manganese composite oxide powder.
Surface area is 0.3m ²/ G or more, 1.2m²/ G or less
The lithium according to claim 1 or 2, wherein
Manganese composite oxide powder. 4. The lithium according to claim 1, wherein a ratio of particles having a volume-based particle diameter of 50 μm or more of the lithium manganese composite oxide powder is 10% by volume or less of all particles. Manganese composite oxide powder. 5. The method according to claim 1, wherein a raw material mixture obtained by mixing a lithium compound, a manganese compound, a boron compound, a halogen compound, and an aluminum compound and / or a magnesium compound is subjected to heat treatment. A method for producing a lithium manganese composite oxide powder.