JP2001216968A - Positive electrode active material, its manufacturing method and nonaqueous secondary battery using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous secondary battery having a great electric capacity of >=100 mAh/g after 100 cycles and a less deteriorating capacity, that is, a capacity maintaining percentage of 90% or more is kept after 100 cycles, a positive electrode active material for the battery and its manufacturing method. SOLUTION: A composite oxide LixAlyMn3-x-y, where 1.0<x<=1.1, 0<y<0.02, 3.5<z<=4.5, having a spinel structure formed of Li, Mn, Al and O is used as the positive electrode active material for the nonaqueous secondary battery.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a positive electrode active material for a non-aqueous secondary battery, a method for producing the same, an electrode paste containing the positive electrode active material, a positive electrode prepared from the paste, and the positive electrode active material. It relates to a non-aqueous secondary battery.

[0002]

2. Description of the Related Art As a positive electrode active material for non-aqueous secondary batteries, high energy
LiCoO from the expectation of higher density_Two, LiNi
O_Two, LiMn_TwoO_FourIs being considered. However,
LiCoO _TwoCobalt is expensive and has resource constraints,
LiNiO_TwoHas problems such as difficulty in synthesis. So
Low cost, high performance lithium manganese oxide
Expectations for cathode active materials are high, and their development is ongoing.
You. However, spinel type LiMn_TwoO_FourThe positive electrode active material
The non-aqueous secondary battery used as the quality
Capacitance reduction occurs in a short period of time, expected from the composition of the positive electrode active material
The actual capacity is much smaller than the
There is a problem.

Japanese Patent Application Laid-Open No. 2-270268 discloses a composite oxide having a spinel structure in which the capacity is small even when charge and discharge are repeated by excessively adding Li to spinel type LiMn ₂ O _4. I have. However, in this case, Li
There is a problem in that the initial capacity is reduced due to excessive addition of. British Patent Publication No. 22221213A discloses a secondary battery having a large initial capacity using a spinel type LiMn ₂ O ₄ synthesized at a low temperature as a positive electrode active material. Since the surface area is large, there is a problem that the capacity decrease due to repetition of charge and discharge becomes large.

Japanese Patent Application Laid-Open No. 2-278661 discloses Li
In _{x M y Mn 2-y O} Z (M is selected from periodic table IIIa or IIIb elements), 0 <x ≦ 1,0 < y ≦ 1,4 ≦ Z <
It discloses that the positive electrode active material indicated by 4.5 has excellent cycle characteristics. However, since x ≦ 1, M
In the case of the oxide in which is Al, the capacity retention rate is at most 7
It remains at about 0%. Further, in this publication, when M is Y, the capacity retention rate of the secondary battery becomes close to 90%, but there is a problem that the discharge capacity becomes small because Y having a large atomic weight is added.

[0005] JP-A-5-21067 discloses LiM
n (the M elements other than hexavalent Mn from monovalent) _2-y M _y O ₄ by using as the positive electrode active material, there is disclosed a nonaqueous electrolyte battery excellent in cycle characteristics. However, this technique is also similar to the invention described in JP-A-2-278661,
Since Li is not excessive, the capacity retention of the secondary battery is low. JP-A-4-289662 discloses that Li _x A
In _{l y Mn 2-y O 4} , is a positive electrode active substance represented by the range of 0.85 <x ≦ 1.15 and 0.02 ≦ y ≦ 0.5,
It discloses that it has excellent overdischarge characteristics. But,
In the case of such a compound, since an electrochemically inactive Al compound is added so that y ≧ 0.02, there is a problem that the discharge capacity is reduced.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in non-aqueous secondary batteries.
The electric capacity after the lapse of 00 cycles is as large as 100 mAh / g or more, and the capacity retention rate after the lapse of 100 cycles is 9
It is an object of the present invention to provide a non-aqueous secondary battery which can be maintained at 0% or more and has a small decrease in capacity, a positive electrode active material for the battery, and a method for producing the same.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies on the above-mentioned problems, and as a result, have found that a composite oxide Li _x Al _y Mn having a spinel structure composed of Li, Mn, Al and O is provided.
_A non-aqueous secondary battery comprising a positive electrode active material having a composition formula in the range of 1.0 <x ≦ 1.1, 0 <y <0.02 and 3.5 <z ≦ 4.5 in _3-xy O _z It has been found that a non-aqueous secondary battery whose capacity is hardly reduced can be provided.

That is, the present invention relates to (1) Li, Mn,
A composite oxide having a spinel structure composed of Al and O has a value of 1.0 <x ≦ in Li _x Al _y Mn _3-xy O _z .
1.1, 0 <y <0.02, 3.5 <z ≦ 4.5, wherein the positive electrode active material for a non-aqueous secondary battery is characterized by:
(2) The lattice constant (Å) of the composite oxide having a spinel structure is smaller than −0.24x−0.28y + 8.481 and is −0.24x−0.72y + 8.481 or more. The positive electrode active material for a non-aqueous secondary battery according to 1, wherein (3) the composite oxide having a spinel structure has a crystallite size of 400 ° or more and 950 ° or less. Positive electrode active material for water secondary batteries,

(4) The positive electrode active material for a non-aqueous secondary battery as described in any one of (1) to (3) above, wherein the composite oxide having a spinel structure is a particle having an average particle diameter of 2 μm or less;
(5) The composite oxide having a spinel structure has a particle diameter of 3 μm.
1 to 3 above, which are granulated and fired particles of m to 50 μm.
The positive electrode active material for a non-aqueous secondary battery according to any one of the above,
(6) An electrode paste containing the positive electrode active material for a non-aqueous secondary battery according to any one of the above items 1 to 5, (7) the paste is a positive electrode active material or a granulated product thereof, and a conductivity imparting agent. The paste for an electrode according to the above 6, wherein the paste for an electrode contains a binder and a solvent.

(8) The total solid content of the positive electrode active material or the granulated material thereof, the conductivity-imparting agent and the binder in the paste is as follows:
The electrode paste according to the above item 7, which is in a range of 30% by mass to 70% by mass, and (9) the positive electrode active material for a non-aqueous secondary battery according to any one of the above items 1 to 5. Containing positive electrode, (10) lithium compound and specific surface area is 10m
^A manganese carbonate of not less than ² / g and not more than 100 m ² / g and an aluminum compound are mixed, and this is mixed at 350 ° C. to 680 ° C.
Baking reaction at the following temperature for 1 hour or more, then after crushing,
A method for producing a positive electrode active material for a non-aqueous secondary battery, wherein the product is heat-treated at a temperature of 730 ° C. or more and 900 ° C. or less, (11) the aluminum compound has a specific surface area of 50 m ^2.
The method for producing a positive electrode active material for a non-aqueous secondary battery according to the above item 10, wherein the compound is a compound having a concentration of not less than 200 g / g and not more than 200 m ² / g,

(12) Aluminum compound is aluminum oxide (alumina such as α, β, γ, δ, ζ, η, θ, κ, χ, ρ, etc.), Al (OH) ₃ , Al (NO ₃ ) ₃ , A
12. The positive electrode active material for a nonaqueous secondary battery according to the above item 10 or 11, which is at least one compound selected from the group consisting of l ₂ (SO ₄ ) ₃ (aluminite, etc.), aluminum acetate and hydrates thereof. (13) A negative electrode containing an active material capable of reversibly inserting and extracting lithium ions, a non-aqueous electrolyte or a polymer electrolyte, Li, Mn, Al and O
6. A non-aqueous secondary battery provided with a positive electrode containing a composite oxide active material having a spinel structure, comprising: the composite oxide as the positive electrode active material for a non-aqueous secondary battery according to any one of the above items 1 to 5. A non-aqueous secondary battery, characterized in that
4) The object is achieved by providing a non-aqueous secondary battery described in the above item 13, wherein the non-aqueous secondary battery is a coin-type battery or a cylindrical battery, a prismatic battery, or a polymer battery.

Hereinafter, the present invention will be described in detail. The present invention relates to a composite oxide positive electrode active material having a spinel structure composed of Li, Mn, Al and O, and relates to Li _x Al _y M
In n _3-xy O _z , the composition range of x is 1.0 <x ≦ 1.
Provided is a composite oxide in which the composition range of 1, y is 0 <y <0.02, and the composition range of z is 3.5 <z ≦ 4.5. The composition range is preferably 1.005 ≦ x ≦ 1.080, 0.
005 ≦ y ≦ 0.018, 3.7 <z ≦ 4.3,
The lattice constant L (Å) is L1 (x, y) = − 0.24x−0.28y + 8.
481, and L2 (x, y) = −
Those larger than the value represented by 0.24x−0.72y + 8.481 are preferable. That is, the lattice constant in the range shown in FIG. 1 is good.

Generally, when a solid solution is made of ceramics,
It is known that the lattice constant changes according to the Vegard rule.
ing. Li_xAl_yMn_3-xyO_zFor, in the crystal
Mn ³⁺Is distorted, so that the lattice constant is
Although it is not possible to measure,
When forming a solid solution, the lattice constant (Å) is L2 (x,
y) (−0.24x−0.72y + 8.48)
It was found that it was in the plane represented by 1). In contrast
When the solid solution of Al does not advance, the lattice
The number (Å) increases, and the relational expression (−−) of L1 (x, y)
0.24x-0.28y + 8.481) or more
Poor electrical characteristics when used as positive electrode of Li-ion battery
(See FIG. 1). Ever, like this
With a spinel structure with a wide range of lattice constants
Oxides have not been found previously.

When the lattice constant is larger than the above range, the capacity is greatly reduced. To prevent this decrease in capacity, x
Must be greater than 1.1. In order to prevent a decrease in capacity, an attempt can be made to increase y to 0.02 or more. However, as a result, the discharge capacity is reduced, and the desired capacity is large and the capacity decrease is small. A positive electrode active material cannot be obtained. The crystallite size of the positive electrode active material is preferably from 400 ° to 950 °, and more preferably from 600 ° to 850 °. When the crystallite size is smaller than 400 °, the discharge capacity of the secondary battery decreases, and when the crystallite size is larger than 950 °, the deterioration of the discharge capacity in the charge / discharge cycle increases.

As a method for producing the positive electrode active material of the present invention, for example, a lithium compound, manganese carbonate having a specific surface area of 10 m ² / g or more and 100 m ² / g or less, and an aluminum compound are mixed, and the mixture is heated at 350 ° C. to 680 Calcination reaction for 1 hour or more at a temperature of
The positive electrode active material can be manufactured by performing a heat treatment at a temperature of 900 ° C. or lower. In particular, in the present production method, the raw material is preliminarily subjected to a firing reaction at a temperature of 350 ° C or more and 680 ° C or less, and then disintegrated to redisperse the unreacted material. Then, the reaction can be completed. In addition, by performing the firing process at a low temperature, the temperature can be increased from 730 ° C. to 900 ° C.
When sintering at a temperature of not more than ℃ C, Li sites in the crystal lattice
There is an advantage that crystallization can be performed without mixing of n. In the present invention, a composite oxidant for a positive electrode active material having excellent battery characteristics can be obtained by such a production method.

In the above production method, the lithium compound as a raw material is not particularly limited, and lithium carbonate, lithium hydroxide, lithium nitrate and the like are preferably used. Further, in the above manufacturing method, an aluminum compound of the raw material is not particularly limited, from the viewpoint of reactivity at a temperature of 350 ° C. or higher 680 ° C. or less and a specific surface area of 50 m ² / g or more 200 meters ² / g
Any of the following aluminum compounds may be used. Examples of such an aluminum compound include aluminum oxide (alumina such as α, β, γ, δ, ζ, η, θ, κ, χ, ρ, etc.), Al (OH) ₃ , Al (NO ₃ ) ₃ , Al ₂ (SO
₄ ) ₃ (aluminite, etc.), aluminum acetate and their hydrates. Preferably, aluminum oxide is used, particularly preferably alumina obtained from the gas phase process (eg γ-type).

Further, in the present invention, the Li _x Al _y
Mn _3-xy O _z (where 1.0 <x ≦ 1.1, 0 <y <
0.02, 3.5 <z ≦ 4.5. ) Is obtained by pulverizing the calcined product and then obtaining the obtained pulverized particles (this is a primary particle or a secondary particle obtained by assembling primary particles, the average particle diameter of which is 2 μm or less, Preferably 0.1 μm to 1.0 μm, more preferably 0.2 μm
The range is preferably 0.5 to 0.5 μm. ) Can be used as the positive electrode active material. In the present invention, dense granulated particles (particle size of 3) are obtained by adding and mixing a sintering accelerator (granulation accelerator) to the pulverized particles having the average particle diameter and granulating and firing.
μm to 50 μm, preferably 5 μm to 30 μm) may be used as the positive electrode active material. Here, the dense granulated particles mean that there are no or few voids between the primary particles of the oxide, and can be produced by the following method using a sintering accelerator.

The crushed and pulverized Li _x Al _y Mn _3-xy
O _z (where 1.0 <x ≦ 1.1, 0 <y <0.02,
It is in the range of 3.5 <z ≦ 4.5. The method for mixing the composite oxide particles represented by the formula (1) and the sintering promoting aid is not particularly limited, and for example, a medium stirring type pulverizer, a ball mill, a paint shaker, a mixing mixer, or the like can be used. The mixing method may be either a dry method or a wet method. When the composite oxide is crushed and pulverized, a sintering accelerator may be added and mixing may be performed at the same time.

The sintering accelerator which can be used is the Li_xAl_y
Mn_3-xyO_z(However, 1.0 <x ≦ 1.1, 0 <y <
0.02, 3.5 <z ≦ 4.5. )
The crushed and crushed particles of the complex oxide particles are burned for granulation.
Any material can be used as long as it can be tied, more preferably 900 ° C.
Compounds that melt at the following temperatures, e.g.
Becomes an oxide or its oxide that can be melted at a temperature of 0 ° C
Solid precursor with lithium or manganese
Can react and melt into an oxide or its oxide
Any compound may be used. For example, sintering accelerators include B
Compounds containing elements such as i, B, W, Mo, Pb
Used in any combination of these compounds.
Or B_TwoO_ThreeAnd LiF compound
Or MnF _TwoCompounds that combine LiF and LiF are also used
It is. In particular, compounds containing the elements Bi, B, and W are sintered.
It is particularly preferable because the shrinkage effect is large.

For example, Bi compounds include bismuth trioxide, bismuth nitrate, bismuth benzoate, bismuth oxyacetate, bismuth oxycarbonate, bismuth citrate, bismuth hydroxide and the like. Examples of the B compound include boron trioxide, boron carbide, boron nitride, and boric acid. Examples of the W compound include tungsten dioxide and tungsten trioxide.

The amount of the sintering accelerator is 0.0001 in terms of the added metal element per mole of Mn in the composite oxide.
It is preferably in the range of -0.05 mol. If the amount of the added metal element is less than 0.0001 mol, there is no sintering shrinkage effect, and if it exceeds 0.05 mol, the initial capacity of the active material becomes too small. Preferred is 0.00
5 to 0.03 mol. The sintering accelerator may be used in a powder state or a liquid state dissolved in a solvent. When added in a powder state, the average particle size of the sintering accelerator is 50 μm.
m or less, more preferably 10 μm or less, and even more preferably 3 μm or less. The sintering promoting aid is preferably added before granulation / sintering, but the granulated material may be impregnated and sintered at a temperature at which the sintering promoting aid can be melted after granulation.

Next, the granulation method will be described. As the granulation method, spray granulation method using the sintering accelerator,
Examples of the method include a fluidized-granulation method, a compression-granulation method, and a stirring-granulation method. Agitation granulation and compression granulation are particularly preferred because the density of secondary particles increases and spray granulation results in a perfectly spherical granulated particle shape. Examples of the agitation granulator include a vertical granulator manufactured by Powrex Co., Ltd. and a Spartan Luzer manufactured by Fuji Paudal Co., Ltd., and examples of the compression granulator include Kurimoto Tekko Co., Ltd. Roller compactor MRCP-200 type.
Examples of the spray granulator include a mobile minor type spray dryer such as Ashizawaniro Atomizer Co., Ltd.

In the present invention, the size of the granulated particles used for the positive electrode is not particularly limited. If the average particle diameter of the granulated particles is too large, it may be lightly crushed and pulverized immediately after granulation or after sintering, classified and sized to obtain a desired particle size. In order to increase the granulation efficiency, an organic granulation aid may be added. Examples of the granulation aid include an acrylic resin, a copolymer of isobutylene and maleic anhydride, polyvinyl alcohol, polyethylene glycol, polyvinyl pyrrolidene, hydroxypropyl cellulose, methyl cellulose, corn starch, gelatin, lignin and the like.

The addition amount of the granulation auxiliary is Li _x Al _y
Mn _3-xy O _z (where 1.0 <x ≦ 1.1, 0 <y <
0.02, 3.5 <z ≦ 4.5. ) Is preferably 5 parts by weight or less, more preferably 2 parts by weight or less, based on 100 parts by weight of the composite oxide and the sintering accelerator.

Next, a method for firing the granulated particles will be described. The method of degreasing the granulated particles is performed by maintaining the granulated particles in a temperature range of 300 ° C. to 550 ° C. for 10 minutes or more in the air or in a gas atmosphere containing oxygen. The defatted granulated material preferably has a carbon residue of 0.1% or less. The degreased granulated particles are sintered by maintaining the temperature in a temperature range of 550 ° C. to 900 ° C. for 1 minute or more in air or an atmosphere containing oxygen. Also, in the firing of the particles of the granulated material without using the above-mentioned organic-based granulating aid, the sintering shrinkage is similarly performed in the air or in a gas atmosphere containing oxygen, and the secondary particles are densified. Can be.

Next, a method of using the positive electrode active material of the present invention as a positive electrode material of a non-aqueous secondary battery will be described. The positive electrode is prepared by kneading the positive electrode active material or its granulated material, a conductivity-imparting agent (conductive material), and a binder (binder) at a predetermined ratio with a paste solvent, and preparing an electrode paste. It is applied to the body, then dried and pressed by a roll press or the like to produce. Examples of the conductivity-imparting agent include carbon powder such as carbon black and graphite such as Vulcan XC-72 manufactured by Cabot, metal powder such as Al powder and Ag powder, and SnO _2.
And the like, and a mixture thereof.

The binder generally includes polyvinylidene fluoride (PVDF), Teflon, ethylene-propylene-diene-copolymer (EPDM), styrene-butadiene rubber (SBR), carboxymethylcellulose (C
MC) is used. The solvent that can be used for the electrode paste may be any solvent that can dissolve or swell the binder, for example, aromatic solvents such as N-methyl-2-pyrrolidone (NMP), benzene, xylene, and toluene, methanol, and ethanol. And alcohols such as propanol and butanol, ketones such as methyl ethyl ketone, and ethers such as dioxane. NMP, xylene, toluene and the like are preferably used.

As the current collector, a known metal current collector such as a foil or a mesh made of aluminum, stainless steel (SUS), titanium, or the like is used. The ratio of the solid component of the electrode paste is determined in consideration of the characteristics and electric capacity of the active material of the present invention.
% By mass, preferably 60 to 90% by mass, the conductivity imparting agent is 49 to 4% by mass, preferably 39 to 4% by mass, and the binder (binder) is 1 to 46% by mass, preferably 1 to 36% by mass. used. The solvent amount of the electrode paste is arbitrarily determined from the applicability, and the solid content concentration is 30 to 70.
% By mass, preferably 40 to 60% by mass.

The negative electrode used in the non-aqueous secondary battery of the present invention is not particularly limited as long as it is an active material capable of inserting and extracting lithium ions reversibly.
A lithium alloy, a carbon material (including graphite), a metal chalcogen, or the like can be used. As the electrolyte salt in the non-aqueous electrolyte used in the non-aqueous secondary battery of the present invention, for example, L
iPF ₆ , LiBF ₄ , LiN (CF ₃ SO ₂ ) ₂ , LiA
sF ₆ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiI, L
iClO ₄ , LiSCN and the like are preferable, and the above-mentioned lithium salt containing fluorine is preferably used.

Alternatively, in the non-aqueous secondary battery of the present invention, a polymer solid electrolyte may be used instead of the non-aqueous electrolyte, and the material is not limited. Polymer solid electrolytes
Usually a solid polymer electrolyte containing an oligooxyethylene group or an oligopropyloxy group (abbreviated as SPE),
It is known that the ionic conductivity is about 10 ^-6 to 10 ^-3 S / cm (for example, Japanese Patent Application Laid-Open No. 4-211412). For example, this SPE includes polyethylene oxide or polypropylene oxide, or polyethylene, polypropylene, polyacrylonitrile, polybutadiene, polymethacrylates, polyacrylates, polystyrene, polyphosphazenes, polysiloxanes or polysilane, or polyfluoride. Examples include polymers in which an oligooxyethylene group or an oligopropyloxy group is chemically bonded to a base polymer such as vinylidene or polytetrafluoroethylene.

As the non-aqueous electrolyte for the non-aqueous secondary battery, at least one kind of the above-mentioned electrolyte containing lithium ions is used by dissolving it in the non-aqueous electrolyte. The non-aqueous solvent of the non-aqueous electrolyte solution can be used without limitation as long as it is chemically and electrochemically stable and aprotic. For example, dimethyl carbonate, propylene carbonate, ethylene carbonate, methyl ethyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, methyl butyl carbonate, diethyl carbonate, ethyl propyl carbonate, diisopropyl carbonate, dibutyl carbonate, 1,2-butylene carbonate, ethyl isopropyl carbonate, Carbonic esters such as ethyl butyl carbonate are exemplified. Oligoethers such as triethylene glycol methyl ether and tetraethylene glycol dimethyl ether; aliphatic esters such as methyl propionate and methyl formate; aromatic nitriles such as benzonitrile and tolunitrile; amides such as dimethylformamide; Sulfoxides such as sulfoxide,
Lactones such as γ-butyrolactone, sulfur compounds such as sulfolane, N-vinylpyrrolidone, N-methylpyrrolidone, and phosphoric esters can also be exemplified. Of these, carbonates, aliphatic esters, and ethers are preferred in the present invention.

Next, a method for evaluating the electrode characteristics will be described. The positive electrode, the negative electrode, the non-aqueous electrolyte or the polymer electrolyte, the separator (for example, polypropylene or another polyolefin containing polyethylene or a copolymer) used by the above method, and the negative electrode if necessary. For the purpose of preventing micro short circuit caused by dendrite generation, silica fiber filter paper QR-100 manufactured by Advantech Toyo Co., Ltd. is also used as a reinforcing material, and coin batteries (for example, 2016 type), cylindrical batteries, prismatic batteries, polymers Make a battery. Then, the battery is subjected to 100 charge / discharge cycle tests, for example, constant current / constant voltage charge-constant current discharge, charge / discharge rate 1C (2.
The charging is stopped after 5 hours), and the scanning is performed at a scanning voltage of 3.1 V to 4.3 V.

[0033]

EXAMPLES The present invention will be described in more detail with reference to the following examples and comparative examples, but the present invention is not limited to these examples.

(Example 1) Production of positive electrode active material Manganese carbonate (BET specific surface area: 30 m ² / g)
492 mol and lithium carbonate (BET specific surface area: 1 m ²
/ G) of 0.128 mol and 0.0016 mol of aluminum oxide (BET specific surface area: 100 m ² / g) with a capacity of 0.10 mol.
After mixing for 1 hour in a 7 liter ball mill, the mixture was reacted in the atmosphere at a reaction temperature of 650 ° C. for 4 hours. After crushing this product in a ball mill for 1 hour,
At a heat treatment temperature of 20 hours.

The composition of the positive electrode active material is as follows:
Li was determined by flame photometry, Al by ICP, and Mn by potentiometric titration, and it was confirmed that the mixing ratio was not changed. The lattice constant is determined by the method of JBNelson and DPRiley (Pr
oc.Phys.Soc., 57, 160 (1945)). The crystallite size was measured from the X-ray diffraction peak of the (111) plane of lithium manganate under the following conditions, and calculated using the Scherrer equation. Assuming that the outer shape of the crystallite is cubic and does not have a size distribution, the value obtained by calculating the spread of the diffraction line according to the size of the crystallite from the half width was used. After grinding the single crystal silicon with a tungsten carbide sample mill,
A device constant calibration curve was prepared using the powder sieved to m or less as an external standard. However, the measurement device is a Rad-type goniometer manufactured by Rigaku Denki Co., Ltd., the continuous measurement is used as the measurement mode, and the analysis software uses the RINT2000 series RINT2000 series application software to analyze the crystallite size. Was. The measurement conditions were X-ray (CuKα ray),
Output 50kV, 180mA, slit width (3 places) is 1
/ 2 °, 1/2 °, 0.15mm, scan method is 2θ
/ Θ method, scan speed 1 ° / min, measurement range (2
θ) is 17 to 20 °, and the step is 0.004 °.
The accuracy of the crystallite size in this method was ± 30 °.

Next, a coin-type battery was manufactured using the positive electrode active material by the following method. The mass ratio of the positive electrode active material, the conductive agent carbon black and ethylene tetrafluoride dissolved (or swelled) in N-methyl-2-pyrrolidone is 8 by mass ratio.
The mixture was kneaded at a ratio of 0:10 to 10 and the paste was applied on a current collector made of aluminum expanded metal at 2 t / c.
Pressure molding was performed at m ² to obtain a positive electrode. On the other hand, a lithium foil having a predetermined thickness was used as a negative electrode. As an electrolytic solution, a solution obtained by dissolving LiPF ₆ at a concentration of 1 mol / liter in a mixed solution obtained by mixing ethylene carbonate and dimethyl carbonate at a volume ratio of 1: 2 was used. Using these positive and negative electrodes, a polypropylene separator and an electrolytic solution, a 2016 type coin-type battery was produced. Using the battery prepared by the above method, charge / discharge was repeated at a charge / discharge rate of 1 C and a voltage range of 4.2 V to 3.0 V, and a charge / discharge cycle test was performed. Table 1 summarizes the composition, lattice constant, crystal size, discharge capacity, and capacity retention of the composite oxide.

(Examples 2 to 14) Referring to Example 1, a cathode active material was produced in the same manner as in Example 1 except that the mixing ratio of manganese carbonate, lithium carbonate, and aluminum oxide was different. The crystallite size, discharge capacity, and capacity retention were investigated, and the results are summarized in Table 1.

Example 15 Lithium carbonate, manganese carbonate and 150 m ² / g vapor-phase alumina were mixed so that the molar ratio of Li / Mn / Al was 1.03: 1.957: 0.013. Mix in a ball mill and 650 ° C
Allowed to react for hours. 0.4 mass% of boron oxide was added to the obtained reaction powder, and the mixture was wet-pulverized with a ball mill using water as a dispersion medium to obtain an average particle diameter of 0.3 μm. After drying the slurry, Spartan Luzer RM manufactured by Fuji Paudal Co., Ltd.
Granulated with O-6H. 1.5 mass% of polyvinyl alcohol which was made into an aqueous solution as a granulating binder was added to the pulverized powder to perform granulation. Lightly pulverize the obtained granulated powder with a mixer.
It was crushed and sized to 20 μm by air classification. The sized granulated powder is held in the air at 500 ° C. for 2 hours and then degreased.
The mixture was fired at 0 ° C. for 30 minutes to obtain a composite oxide.

Pure water was added to the obtained composite oxide to form a slurry having a solid content of 20%, and the resulting mixture was subjected to ultrasonic treatment for 5 minutes, followed by washing 10 times until the supernatant was removed. And dried. The solution was charged into an aqueous solution containing 5 mol% of nitric acid with respect to the obtained composite oxide having a spinel structure, and after confirming that the pH of the aqueous solution became constant around neutrality, filtration and washing were performed to 100 ° C. And vacuum dried. And it heat-processed at 300 degreeC for 4 hours, and obtained the positive electrode active material of this invention. The obtained positive electrode active material was subjected to battery evaluation in the same manner as in Example 1. Table 1 summarizes the results of the composition, lattice constant, crystallite size, discharge capacity, and capacity retention of the composite oxide.

[0040]

[Table 1]

Comparative Examples 1 to 10 A positive electrode active material was produced in the same manner as in Example 1 except that the mixing ratio of manganese carbonate, lithium carbonate, and aluminum oxide was different. The crystallite size, discharge capacity, and capacity retention were examined, and the results are summarized in Table 2.

(Comparative Examples 11 and 12) Referring to Example 1,
A positive electrode active material was produced in the same manner as in Example 1 except that the firing temperature was different, and the lattice constant, crystallite size, discharge capacity,
The capacity retention was examined, and the results are summarized in Table 2.

Comparative Example 13 A positive electrode active material was produced in the same manner as in Example 1 except that manganese carbonate having a BET specific surface area of 8 m ² / g was used as a manganese raw material. , Crystallite size, discharge capacity, and capacity retention ratio were examined, and the results are summarized in Table 2.

(Comparative Example 14) With reference to Example 1, except that electrolytic manganese dioxide having a BET specific surface area of 15 m ² / g was used as a manganese raw material, the lattice constant and crystallite of the positive electrode active material were changed in the same manner as in Example 1. The size, discharge capacity, and capacity retention were examined, and the results are summarized in Table 2.

(Comparative Example 15) With reference to Example 1, except that electrolytic manganese dioxide having a BET specific surface area of 80 m ² / g was used as a manganese raw material, the lattice constant and crystallite of the positive electrode active material were changed in the same manner as in Example 1. The size, discharge capacity, and capacity retention were examined, and the results are summarized in Table 2.

(Comparative Example 16) With reference to Example 1, the same procedure as in Example 1 was carried out except that manganese trioxide having a BET specific surface area of 5 m ² / g was used as a manganese raw material. The size, discharge capacity, and capacity retention were examined, and the results are summarized in Table 2.

Comparative Example 17 Referring to Example 1, except that aluminum oxide having a BET specific surface area of 10 m ² / g was used as an aluminum raw material, the lattice constant and crystallite size of the positive electrode active material were changed in the same manner as in Example 1. , Discharge capacity and capacity retention rate were examined, and the results are summarized in Table 2.

(Comparative Example 18) Referring to Example 1, except that aluminum oxide having a BET specific surface area of 10 m ² / g was used as an aluminum raw material, the lattice constant and crystallite size of the positive electrode active material were changed in the same manner as in Example 12. , Discharge capacity and capacity retention rate were examined, and the results are summarized in Table 2.

Comparative Example 19 A positive electrode active material was produced in the same manner as in Example 1 except that the mixing ratio of manganese carbonate, lithium carbonate, and aluminum oxide was different.
The lattice constant, crystallite size, discharge capacity, and capacity retention were examined, and the results are summarized in Table 2. However, in this comparative example, aluminum oxide was not added.

[0050]

[Table 2]

The above Examples 1 to 15 and Comparative Examples 1 to
As the results obtained in step 19, X, Y, lattice constant (Å), crystallite size (Å), and crystallite size (Ｌｉ) in Li _X Al _Y Mn _3-XY O _Z
Table 1 or Table 2 summarizes the initial discharge capacity (mAh / g), the discharge capacity after 100 cycles (mAh / g), and the capacity retention rate after 100 cycles. The amount of oxygen indicating the composition ratio Z is difficult to accurately analyze and has oxygen vacancies, but is usually in the range of 3.5 <z ≦ 4.5. The capacity retention rate was determined from the calculation of (discharge capacity after 100 cycles / discharge capacity in initial cycle) × 100.

[0052]

The present invention comprises conventional Li, Mn, Al and O.
Complex oxide Li having spinel structure _xAl_yMn_3-xy
O_zIn the production of
It is necessary to add a large amount of l, and as a result, a secondary battery is manufactured.
The disadvantage is that the initial capacity of the battery when
However, the positive electrode active material of the present invention has an Al addition ratio of 0 <y <
By setting it in the low concentration range of 0.02,
Was found to progress unexpectedly.

When the composition range is 1.0 <x ≦ 1.1,0
Li _x A in the range of <y <0.02, 3.5 <z ≦ 4.5
In the composite oxide having a l _y Mn _3-xy O _z structure, the lattice constant (Å) is, L1 (x, y) = - 0.24x-
0.22y + 8.481, smaller than the value represented by L2
A value larger than the value represented by (x, y) =-0.24x-0.72y + 8.481 is preferable. In the above composition range, when a solid solution is completely formed, the lattice constant (Å) is expressed by the relational expression (−0.24x−) of L2 (x, y).
(0.72y + 8.481) for the first time. In the present invention, by using the positive electrode active material in a non-aqueous secondary battery, compared to a battery using a conventional manganese oxide-based battery, the capacity is hardly reduced at high capacity, and a highly practical non-aqueous secondary battery is used. It has been found that a battery can be obtained.

[Brief description of the drawings]

FIG. 1 shows a range of lattice constants effective in the present invention.

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 4G048 AA04 AB01 AC06 AD03 AD06 AE05 AE07 5H029 AJ03 AJ05 AK03 AL04 AL06 AL07 AL12 AM00 AM03 AM04 AM16 BJ02 BJ03 HJ01 HJ02 HJ05 HJ07 HJ13 HJ14 5H050 AA07 CB07 DA09CB09 DA18 FA19 GA02 GA10 HA01 HA02 HA05 HA07 HA13 HA14

Claims (14)

[Claims] 1. A composite oxide having a spinel structure composed of Li, Mn, Al and O is composed of Li _x Al _y Mn _{3 -xy} O _z, wherein 1.0 <x ≦ 1.1 and 0 <y <0. .02,3.
A cathode active material for a non-aqueous secondary battery, wherein 5 <z ≦ 4.5. 2. The composite oxide having a spinel structure has a lattice constant (Å) smaller than -0.24x-0.28y + 8.481 and at least -0.24x-0.72y + 8.481 or more. The positive electrode active material for a non-aqueous secondary battery according to claim 1. 3. The positive electrode active material for a non-aqueous secondary battery according to claim 1, wherein the composite oxide having a spinel structure has a crystallite size of 400 ° or more and 950 ° or less. 4. The positive electrode active material for a non-aqueous secondary battery according to claim 1, wherein the composite oxide having a spinel structure is a particle having an average particle diameter of 2 μm or less. 5. The positive electrode active material for a non-aqueous secondary battery according to claim 1, wherein the composite oxide having a spinel structure is granulated and calcined particles having a particle diameter of 3 μm to 50 μm. . 6. An electrode paste containing the positive electrode active material for a non-aqueous secondary battery according to claim 1. 7. A paste comprising: a positive electrode active material or a granulated product thereof;
The electrode paste according to claim 6, comprising a conductivity imparting agent, a binder, and a solvent. 8. A positive electrode active material or a granulated product thereof in a paste,
The electrode paste according to claim 7, wherein the total solid content of the conductivity-imparting agent and the binder is in a range of 30% by mass to 70% by mass. 9. A positive electrode comprising the positive electrode active material for a non-aqueous secondary battery according to claim 1. 10. A lithium compound having a specific surface area of 10 m ^2.
/ G or more and 100 m ² / g or less of manganese carbonate and an aluminum compound, and mixed at 350 ° C. to 680 ° C.
Baking reaction at the following temperature for 1 hour or more, then after crushing,
A method for producing a positive electrode active material for a non-aqueous secondary battery, comprising heating the product at a temperature of 730 ° C or more and 900 ° C or less. 11. An aluminum compound having a specific surface area of 50 m
The method for producing a positive electrode active material for a nonaqueous secondary battery according to claim 10, characterized in that the ² / g or more 200 meters ² / g or less of compound. 12. An aluminum compound comprising aluminum oxide (alumina such as α, β, γ, δ, ζ, η, θ, κ, χ, ρ, etc.), Al (OH) ₃ , Al (NO ₃ ) ₃ , Al ₂ (S
The positive electrode active material for a non-aqueous secondary battery according to claim 10, wherein the positive electrode active material is at least one compound selected from the group consisting of O ₄ ) ₃ (aluminite), aluminum acetate, and hydrates thereof. Production method. 13. An active material comprising a negative electrode containing an active material capable of reversibly storing and releasing lithium ions, a nonaqueous electrolyte or a polymer electrolyte, and a composite oxide having a spinel structure comprising Li, Mn, Al and O. A non-aqueous secondary battery comprising a positive electrode comprising: a non-aqueous secondary battery, wherein the composite oxide is the positive electrode active material for a non-aqueous secondary battery according to any one of claims 1 to 5. Next battery. 14. A non-aqueous secondary battery according to claim 13, wherein the non-aqueous secondary battery is a coin battery, a cylindrical battery, a prismatic battery, or a polymer battery.