JP2002270171A - Positive electrode active material for non-aqueous electrolyte lithium secondary battery and producing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an environment-friendly positive electrode active material having battery characteristics superior in charge and discharge efficiency and a non-aqueous electrolyte lithium secondary battery with usage of it at a low cost. SOLUTION: This positive electrode active material for the non-aqueous electrolyte lithium secondary battery is constituted by a lithium ion complex oxide. The lithium iron complex oxide has an amorphous structure and the composition before initial charge is expressed in a following composition formula (1): Lix FeOy (1) In the formula, 0.65<=x<=1.00, and 1.83<=y<=2.05.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a positive electrode active material for a lithium secondary battery, and more particularly, to a positive electrode active material comprising a lithium iron composite oxide.

[0002]

2. Description of the Related Art In recent years, in order to solve environmental problems caused by exhaust gas, electric vehicles (EV) and hybrid vehicles (HE) have been developed.
The development of V) is strongly desired. As these power sources, lithium ion secondary batteries that are excellent in charge / discharge voltage, discharge capacity, and the like are expected.

As a positive electrode active material used in a lithium ion secondary battery, transition metal oxides such as LiNiO ₂ , LiCoO ₂ and LiMn ₂ O ₄ have been developed so far, such as mobile phones, camcorders, notebook computers and the like. As a power source for portable electronic devices.

[0004] However, EVs and HEVs require a large secondary battery, and there is a problem that the cost is high because Ni and Co are expensive. In addition, since they are toxic, they are not preferable from the viewpoint of environmental consideration.

[0005] For this reason, in the production of large secondary batteries, inexpensive and non-toxic lithium iron compounds are increasingly expected, and several types of structures of LiFeO ₂ have been confirmed so far.

[0006] For example, in J. Power Sources
 68 (1997) 711-715 includes LiCoO_TwoWhen
Monoclinic LiFeO having a similar structure_Two, And Li
MnO _TwoOrthorhombic LiFeO having the same structure as_TwoIs open
Shown, Powder and Powder Metallurgy 46 (1999)
689 has a tunnel type LiFeO_TwoIs disclosed.
These are all manufactured by the ion exchange method.
You. That is, α-FeOOH, γ-Fe
OOH and β-FeOOH, LiOH as exchange material
Using a monoclinic type by ion exchange at a suitable temperature,
Orthogonal type, tunnel type LiFeO_TwoAre manufactured.

[0007] However, whether or not to have various structures
Suggest that LiFeO _TwoIs easy to change structure
The discharge capacity is high due to structural changes due to charge and discharge.
There was a problem that it was greatly reduced.

[0008]

DISCLOSURE OF THE INVENTION The present invention has been completed in view of the above problems, and provides a positive electrode active material which is inexpensive, environmentally friendly and has excellent charge / discharge characteristics such as discharge capacity and cycle characteristics. The purpose is to do.

Another object of the present invention is to provide a non-aqueous electrolyte lithium ion secondary battery having the above characteristics and a method for producing the same.

[0010]

SUMMARY OF THE INVENTION The present invention has been completed by focusing on the fact that the above-mentioned problems can be solved by using a lithium-iron composite oxide having an amorphous structure and a controlled composition ratio as a positive electrode active material. It is. That is, the present invention is configured as follows for each claim.

The invention according to claim 1 is a positive electrode active material for a nonaqueous electrolyte lithium secondary battery comprising a lithium iron composite oxide, wherein the lithium iron composite oxide has an amorphous structure; The composition before the initial charge is the following composition formula (1):

[0012]

Embedded image

(Where, 0.65 ≦ x ≦ 1.00, 1.8
3 ≦ y ≦ 2.05).

According to a second aspect of the present invention, there is provided a semiconductor device comprising:
Atomic% or less is Ni, Ti, V, Cr, Mn, Co, C
The positive electrode active material according to claim 1, wherein the positive electrode active material is substituted with one or more elements selected from the group consisting of u, Al, and Mg.

According to a third aspect of the present invention, there is provided a positive electrode using the positive electrode active material according to the first or second aspect, and a negative electrode using a material capable of inserting and extracting lithium ions or metallic lithium. A non-aqueous electrolyte lithium secondary battery characterized in that:

The invention according to claim 4 provides a lithium compound, an iron compound and, if necessary, Ni, Ti, V, Cr,
A lithium-iron composite oxide having an amorphous structure is obtained by mixing and firing a metal compound containing one or more elements selected from the group consisting of Mn, Co, Cu, Al and Mg. This is a method for producing a positive electrode active material for a non-aqueous electrolyte lithium secondary battery.

According to a fifth aspect of the present invention, the molar ratio of the lithium compound to the iron compound is 0.65: 1 to 1: 1.
The method for producing a positive electrode active material for a non-aqueous electrolyte lithium secondary battery according to claim 4, wherein the ratio is 1: 1.

According to a sixth aspect of the present invention, in the method for producing a positive electrode active material for a non-aqueous electrolyte lithium secondary battery according to the fourth or fifth aspect, the sintering temperature is 600 ° C. or less. is there.

The invention according to claim 7 is characterized in that the sintering atmosphere comprises 5 to 40% by volume of oxygen and 60 to 95% by volume of an inert gas. A method for producing a positive electrode active material for a nonaqueous electrolyte lithium secondary battery according to any one of the preceding claims.

The invention according to claim 8 is characterized in that the lithium compound is selected from the group consisting of lithium oxide, lithium peroxide, lithium carbonate, lithium hydroxide, and lithium nitrate. 8. A method for producing a positive electrode active material for a non-aqueous electrolyte lithium secondary battery according to any one of items 7 to 7.

According to a ninth aspect of the present invention, the iron compound comprises ferrous oxide, ferric oxide, triiron tetroxide, and α-iron oxide.
The non-aqueous electrolyte lithium secondary battery according to any one of claims 4 to 8, wherein the lithium secondary battery is selected from the group consisting of iron oxohydroxide, β-oxohydroxide, and γ-oxohydroxide. This is a method for producing a positive electrode active material for use.

[0022]

According to the present invention configured as described above, the following effects can be obtained for each claim.

According to the first aspect of the present invention, the Li _x FeO _y having an amorphous structure has a preferable range of the amount x of Li and the amount _y of oxygen, thereby providing a large discharge capacity and excellent cycle characteristics. A positive electrode active material can be obtained. The positive electrode active material is particularly useful when used in an EV or HEV battery. In addition, since this positive electrode active material uses Fe, it can be manufactured at a lower cost than conventional positive electrode active materials using Mn, Ni, and Co, and has no environmental toxicity because it has no toxicity. Are better.

According to the second aspect of the present invention, Ni, Ti, V, Cr, Mn, Co,
By substituting with Cu, Al, or Mg, strain in the crystal can be reduced, and a positive electrode active material having more excellent discharge capacity and cycle characteristics can be obtained.

According to the third aspect of the invention, a non-aqueous electrolyte lithium secondary battery having the effects of the first or second aspect can be obtained.

According to the fourth aspect of the present invention, a positive electrode active material for a non-aqueous electrolyte lithium secondary battery having an amorphous structure can be obtained by firing.

According to the fifth aspect of the present invention, a positive electrode active material for a non-aqueous electrolyte lithium secondary battery having a suitable composition ratio is obtained by defining a molar mixing ratio of a lithium compound and an iron compound. be able to.

According to the present invention, the positive electrode active material for a lithium secondary battery having an amorphous structure is defined by specifying a firing temperature, an atmosphere during firing, a lithium compound, and an iron compound. Can be suitably produced.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION The first invention of the present application is a positive electrode active material used for a non-aqueous electrolyte secondary battery comprising a lithium iron composite oxide, wherein the composition before the initial charge has the following composition formula (1):

[0030]

Embedded image

(Where 0.65 ≦ x ≦ 1.00, 1.8
3 ≦ y ≦ 2.05), and has an amorphous structure. L
By defining the composition ratio and the structure of the positive electrode active material composed of i, Fe, and O within the above ranges, it is possible to obtain a positive electrode active material having excellent charge / discharge characteristics such as cycle characteristics. The amorphous structure can be measured using a commercially available device using known means such as X-ray crystal structure diffraction and powder X-ray diffraction. For example, an XRD apparatus of MXP18VAHF (manufactured by Mac Science Co., Ltd.) is used for X-ray crystal structure diffraction, and RIETAN94 can be used as a structure determination program. As a calculation method, a general Rietveld analysis can be used. The material composition can be measured using ICP (manufactured by Seiko Instruments Inc .: SPS-1700HVR) or the like.

The lithium iron composite oxide contains 30 atomic% or less of Fe, Ni, Ti, V, Cr, Mn, Co, Cu,
It is preferable to substitute one or more elements selected from the group consisting of Al and Mg. By substituting a part of Fe with these atoms, it is possible to reduce distortion in the crystal by the Jahn-Teller effect, thereby improving the charge / discharge characteristics. However, if the substitution is excessive, the influence of the substituted atoms becomes too strong, which may adversely affect the charge / discharge characteristics. Therefore, it is preferable to substitute 30 atom% or less.

A non-aqueous electrolyte lithium secondary battery including a positive electrode using the positive electrode active material having the above characteristics and a negative electrode using a material or metal lithium capable of inserting and extracting lithium ions has excellent discharge performance. It has capacity and cycle characteristics, can be manufactured at low cost, has excellent environmental adaptability, and is industrially very useful as a power source for EVs and HEVs.

In producing a positive electrode using the positive electrode active material according to the present invention, various known techniques can be used. For example, it can be manufactured by press-molding a positive electrode active material and a binder, performing heat treatment, and bringing the positive electrode current collector into close contact with the positive electrode current collector.
A conductive agent such as carbon black, graphite, and acetylene black may be added to the positive electrode. Alternatively, a method in which the positive electrode active material is mixed with a binder in a solvent to form a paste, the paste is coated on a positive electrode current collector, and then dried may be used. The mixing ratio of the positive electrode active material and the binder is preferably determined appropriately according to the shape of the electrode, and various known methods can be used for coating.

As the binder, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTF)
E) and the like, and as the solvent used in the method of coating as a paste, various polar solvents capable of dissolving the binder can be used. Specific examples include dimethylformamide, dimethylacetamide, methylformamide, N-methylpyrrolidone, and the like.

The negative electrode can be prepared by the same method. As the material capable of inserting and extracting lithium ions used at this time, various known materials used for non-aqueous electrolyte secondary batteries can be used. Specifically, coke, natural graphite, artificial graphite, non-graphitizable carbon, Li-Al alloy, wood alloy, fine-particle multi-component alloy, composite electrode of alloy and conductive polymer, metal oxide such as SnSiO ₃ , LiC
Metal nitride such as oN ₂ can be used.

As the current collector, various known materials can be used. Specific examples include SUS and aluminum as the positive electrode current collector, and stainless steel and copper as the negative electrode current collector.

In constructing the battery, an electrolyte is provided between the positive electrode and the negative electrode. As the electrolyte, an organic solvent electrolyte,
A polymer electrolyte, a solid electrolyte, or the like can be used.

Usually, an electrolyte salt is added to the electrolyte, and the electrolyte salt is LiN (CF ₃ SO ₂ ) ₂ or LiN (C ₂ F).
₅ SO ₂ ) ₂ , LiN (CF ₂ SO ₃ ) ₂ , LiCF ₃ SO ₃ ,
LiBF ₄ , LiPF ₆ , LiNH ₂ , LiF, LiC
1, LiBr, LiI, LiCN, LiClO ₄ , Li
NO ₃ , C ₆ H ₅ COOLi, LiClO ₄ , LiAsF ₆
And the like.

Examples of the organic solvent include carbonates, lactones, and ethers. Specific examples include ethylene carbonate, propylene carbonate, butylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, and 1,2-dimethoxy. Ethane, 1,2-diethoxyethane, tetrahydrofuran, 1,3-dioxolan, γ-butyrolactone, γ
-Solvents such as valerolactone, acetonitrile, diethyl ether, dimethyl sulfoxide, methyl formate, 2-methyltetrahydrofuran, 3-methyl-1,3-oxazolidine-2-one, sulfolane, ethyl acetate, methyl propionate alone or in combination of two or more These can be used in combination. The concentration of the electrolyte salt dissolved in these solvents is preferably 0.5 to 2.0 mol / liter.

Examples of the host polymer used as the polymer electrolyte include, but are not limited to, polyethylene oxide, polypropylene oxide, polyacrylonitrile, polyvinylidene fluoride, and the like. The polymer electrolyte may be an all-solid polymer electrolyte or a gel polymer electrolyte to which a plasticizer is added to make it viscous.

Examples of the solid electrolyte include, but are not limited to, lithium halides such as lithium iodide and derivatives thereof, lithium nitride, oxyacid-based materials, and sulfide-based materials.

A separator can be provided to prevent a short circuit between the positive electrode and the negative electrode. Various known materials can be used for the separator material, and examples thereof include a porous sheet made of polyethylene, polypropylene, and cellulose, and a nonwoven fabric.

The second invention of the present application is a method for producing a positive electrode active material for a non-aqueous electrolyte lithium secondary battery.

First, an iron compound and a lithium compound, and if desired, Ni, Ti, V, Cr, Mn, Co, Cu,
Compounds such as nitrates, carbonates, hydroxides and oxides of metals such as Al and Mg (hereinafter referred to as "M metal") (hereinafter referred to as "M metal compounds") are mixed and fired to obtain lithium iron. Obtain a composite oxide.

The mixing ratio of lithium compound: iron compound is preferably 0.65: 1 to 1: 1 in molar ratio. By mixing in this range, a lithium iron composite oxide having a suitable composition ratio can be obtained.

As a mixing method, a method of dry-mixing or wet-mixing an iron compound, a lithium compound and an M metal compound, and a method of dry-mixing or wet-mixing an iron-M metal composite oxide synthesized from an iron compound and an M metal compound and a lithium compound are used. A method of mixing, a method of dry mixing or a wet mixing of the iron compound powder and the M metal compound, and the like can be given.

As the iron compound, ferrous oxide (Fe
O), ferric oxide (Fe ₂ O ₃ ), triiron tetroxide (Fe
₃ O ₄ ), α-iron oxyhydroxide (α-FeOOH), β-
Iron oxyhydroxide (β-FeOOH), γ-iron oxyhydroxide (γ-FeOOH), and the like can be used. The average particle size of the iron compound powder to be used is preferably 0.1 to 100 μm, and more preferably 20 μm or less. This is because, when the average particle size of the iron compound is large, the reaction between the iron compound and the lithium compound is remarkably slow, and a non-uniform product is easily generated.

Examples of the lithium compound include lithium oxide (Li ₂ O), lithium peroxide (Li ₂ O ₂ ), lithium carbonate (Li ₂ CO ₃ ), lithium hydroxide (LiOH), lithium nitrate (LiNO ₃ ) and the like. Can be used. Among them, lithium carbonate and lithium hydroxide are preferable, and the average particle diameter is 30 for the same reason as in the case of the iron compound.
It is desirable that it is not more than μm.

Thereafter, the mixture is fired. At this time, an amorphous structure is formed by adjusting the firing temperature.

The calcination must be carried out at an appropriate oxygen concentration, and an atmosphere composed of 5 to 40% by volume of oxygen and 60 to 95% by volume of an inert gas is preferable. At this time, the total volume ratio of oxygen and inert gas is 100% by volume. If the oxygen concentration is too high, oxygen more than necessary reacts, the valence of Fe becomes higher than necessary, and there is a possibility that a suitable amorphous structure may not be obtained. This is because the structure may not be formed. The inert gas is preferably argon, nitrogen, helium, or a mixed gas thereof. This is for preventing the reaction with the composition.

The firing temperature is preferably not higher than 600 ° C., more preferably lower than 400 ° C., because if the temperature is high, a structure other than an amorphous structure such as a single crystal structure may be formed. On the other hand, if the temperature is too low, the raw materials may not react.

The firing time is preferably 1 to 60 hours.
0-48 hours are more preferred. If the length is too short, the raw material may not react, and if the length is too long, a structure other than the amorphous structure may be generated. In addition, you may perform the multistage baking which changed the baking temperature as needed.

[0054]

EXAMPLES [Preparation of Positive Electrode Active Material] A predetermined amount of lithium oxide powder, ferrous oxide powder, and M metal oxide powder were weighed and mixed in a mortar. Heat treatment was performed at 300 ° C. for 48 hours in a mixed gas atmosphere of argon (80% by volume) and argon (80% by volume). The crystal structure of the obtained fired product was measured by X-ray diffraction measurement (XR
For D measurement, manufactured by Mac Science Corporation: MXP18V
AHF and RIETA N94 were used for the structure determination program). After cooling, the mixture was pulverized using a mortar to obtain a positive electrode active material having a composition (molar ratio) shown in Tables 1 to 3. The material composition was measured by ICP (SPS-1700HVR manufactured by Seiko Instruments Inc.). Coulometry was measured while purging with argon gas.

[Production of Battery and Measurement of Discharge Capacity] Preparation of positive electrode The obtained positive electrode active material and conductive material (acetylene black)
And a binder (PTFE powder) in a mass ratio of 80:16:
4 and mixed. This mixture is 2t / cm ^TwoWith press
Then, it was shaped into a disk having a diameter of 12 mm. Obtained molded product
Is heat-treated at 150 ° C for 16 hours, and the SUS thin plate is
As a positive electrode.

2. Production of Negative Electrode A disc-shaped lithium metal having a diameter of 12 mm and a mesh-shaped negative electrode current collector made of stainless steel were pressed to form a negative electrode.

3. Production of Battery After the lead was taken out from each of the positive electrode and the negative electrode, an element was made to face each other with a separator therebetween, and this element was sandwiched between two PTFE plates while being pressed by a spring.
An electrolyte was injected, and the side surfaces of the element were covered with a PTFE plate and sealed to obtain a sealed nonaqueous solvent battery. The battery was manufactured in an argon atmosphere.

As the electrolytic solution, a solution prepared by dissolving LiPF ₆ at a concentration of 1 mol / l in a mixed solvent of ethylene carbonate and diethyl carbonate at a volume ratio of 1: 1 was used. Was used.

[Evaluation] Using the above sealed non-aqueous solvent battery, charging and discharging were repeated at a constant current of 30 mA / g from 4.5 V to 1.5 V at an ambient temperature of 25 ° C. The discharge capacity at the 100th cycle was determined. The results are shown in Tables 1 to 3.

<Examples 1 to 4> By adjusting the added lithium oxide powder, the amount x of Li in Li _x FeO _y was 0.65 to 0.65.
Various fired products of 1.00 were obtained. The fired product obtained is X
A line diffraction measurement showed almost no peak, suggesting that the sample was amorphous. Table 1 and FIG. 1 show the results of measuring the initial discharge capacity and the capacity at the 100th cycle for these.

<Comparative Examples 1-3> By adjusting the added lithium oxide powder, the amount x of Li in Li _x FeO _y was 0.55,
Various fired products of 1.10 and 1.22 were obtained. When the obtained fired product was subjected to X-ray diffraction measurement, almost no peak was confirmed, suggesting that the fired product was amorphous. Table 1 and FIG. 1 show the results of measuring the initial discharge capacity and the capacity at the 100th cycle for these.

[0062]

[Table 1]

As shown in Table 1, 0.65 ≦ x ≦ 1.00
In the region, the initial discharge capacity exceeded 130 mAh / g, and the capacity at the 100th cycle was also 120 mAh / g or more, showing excellent capacity and cycle characteristics as compared with the comparative example. Especially when x = 0.85, the initial discharge capacity is 139 mA.
h / g, discharge capacity at the 100th cycle is 131 m
Ah / g and a capacity retention at the 100th cycle of 94% showed extremely excellent cycle characteristics.

<Examples 5 to 13> By adjusting the lithium oxide powder to be added, the amount x of Li in Li _x (Fe _1-a Ni _a ) O _y was 0.65, 0.85, 1.00, and the amount of Ni a is 0.0
Various fired products of 0, 0.15, and 0.30 were obtained. When the obtained fired product was subjected to X-ray diffraction measurement, almost no peak was confirmed, suggesting that the fired product was amorphous. Table 2 and FIG. 2 show the results of measuring the initial discharge capacity and the capacity at the 100th cycle for these.

[0065] By adjusting the lithium oxide powder <Comparative Example 4-6> _{added, Li x (Fe 1-a} Ni a) O y in Li amount x
Are 0.65, 0.85, 1.00 and the Ni amount a is 0.40
Were obtained. When the obtained fired product was subjected to X-ray diffraction measurement, almost no peak was confirmed, suggesting that the fired product was amorphous. Table 2 and FIG. 2 show the results of measuring the initial discharge capacity and the capacity at the 100th cycle for these.

[0066]

[Table 2]

As shown in Table 2, 0.65 ≦ x ≦ 1.0
In the region of 0, 0 ≦ a ≦ 0.3, the initial discharge capacity is 120
mAh / g, and the capacity at the 100th cycle is also 1
It was 20 mAh / g or more, showing excellent capacity and cycle characteristics as compared with the comparative example. In particular, x = 0.85, a =
At 0.15, the initial discharge capacity was 152 mAh / g,
The discharge capacity at the 00th cycle was 136 mAh / g, showing very excellent charge / discharge characteristics. When a = 0.4, both the initial discharge capacity and the cycle characteristics sharply decreased.

<Examples 14 to 21> By adjusting the added lithium oxide powder, the amount x of Li in Li _x (Fe _{1 -a} M _a ) O _y was 1.00, and M metal (Ti, V, Cr, Mn) was used. , Co,
Various calcination products having Cu, Al, or Mg) amount a of 0.30 were obtained. When the obtained fired product was subjected to X-ray diffraction measurement, almost no peak was confirmed, suggesting that the fired product was amorphous. For these, the initial discharge capacity and 100
The results of measuring the capacity at the cycle are shown in Table 3 and FIG.

<Comparative Examples 7 to 14> The amount x of Li in Li _x (Fe _{1 -a} M _a ) O _{y was} adjusted by adjusting the lithium oxide powder to be added.
Is 1.00 and M metal (Ti, V, Cr, Mn, Co, C
Various fired products having an amount a of u, Al, or Mg) of 0.40 were obtained. When the obtained fired product was subjected to X-ray diffraction measurement, almost no peak was confirmed, suggesting that the fired product was amorphous. Table 3 shows the results of measuring the initial discharge capacity and the capacity at the 100th cycle for these.

[0070]

[Table 3]

As shown in Table 3, in the range of 0 ≦ a ≦ 0.3, the initial discharge capacity exceeded 130 mAh / g,
The capacity at the 00th cycle is also 120 mAh / g or more,
Excellent capacity and cycle characteristics were shown as compared with the comparative example. When a = 0.4, both the initial discharge capacity and the cycle characteristics sharply decreased.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the amount x of Li in Li _x FeO _y and the initial discharge capacity and the discharge capacity at the 100th cycle.

FIG. 2 shows the relationship between the Ni amount a, the initial discharge capacity, and 100 when the Li amount x in Li _x (Fe _1-a Ni _a ) O _y is changed.
It is a graph which shows the relationship with the discharge capacity of the cycle.

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (reference) H01M 10/40 H01M 10/40 Z F term (reference) 4G002 AA06 AA10 AB01 AE05 4G048 AA04 AA05 AB05 AC06 AD06 AE05 5H029 AJ03 AJ05 AJ14 AK03 AL12 AM03 AM05 AM07 CJ02 CJ08 CJ28 DJ18 HJ01 HJ02 HJ14 5H050 AA07 AA08 AA17 AA19 BA16 BA17 CA07 CB12 FA20 GA02 GA10 GA27 HA01 HA02 HA14

Claims (9)

[Claims] 1. A positive electrode active material for a non-aqueous electrolyte lithium secondary battery comprising a lithium iron composite oxide, wherein the lithium iron composite oxide has an amorphous structure, and the composition before initial charging is as follows: Composition formula (1): (Where 0.65 ≦ x ≦ 1.00, 1.83 ≦ y ≦ 2.
The positive electrode active material is represented by the following formula: 2. The method according to claim 1, wherein 30 atomic% or less of the Fe is Ni, T
The positive electrode active material according to claim 1, wherein the positive electrode active material is substituted with one or more elements selected from the group consisting of i, V, Cr, Mn, Co, Cu, Al, and Mg. 3. A non-electrode comprising: a positive electrode using the positive electrode active material according to claim 1; and a negative electrode using a material capable of inserting and extracting lithium ions or metallic lithium. Water electrolyte lithium secondary battery. 4. A lithium compound, an iron compound and, if necessary, Ni, Ti, V, Cr, Mn, Co, Cu, Al
And a metal compound containing one or more elements selected from the group consisting of Mg and Mg, followed by firing to obtain a lithium iron composite oxide having an amorphous structure. A method for producing a positive electrode active material for a battery. 5. The positive electrode active material for a non-aqueous electrolyte lithium secondary battery according to claim 4, wherein a molar mixing ratio of the lithium compound and the iron compound is 0.65: 1 to 1: 1. The method of manufacturing the substance. 6. The method for producing a positive electrode active material for a non-aqueous electrolyte lithium secondary battery according to claim 4, wherein the firing temperature is 600 ° C. or lower. 7. The sintering atmosphere according to claim 4, wherein the sintering atmosphere comprises 5 to 40% by volume of oxygen and 60 to 95% by volume of an inert gas. A method for producing a positive electrode active material for a non-aqueous electrolyte lithium secondary battery. 8. The lithium compound, wherein the lithium compound is lithium oxide,
The positive electrode active material for a non-aqueous electrolyte lithium secondary battery according to any one of claims 4 to 7, wherein the positive electrode active material is selected from the group consisting of lithium peroxide, lithium carbonate, lithium hydroxide, and lithium nitrate. Manufacturing method. 9. The iron compound is selected from the group consisting of ferrous oxide, ferric oxide, ferric oxide, and α-oxohydroxide, β-oxohydroxide, and γ-oxohydroxide. The method for producing a positive electrode active material for a nonaqueous electrolyte lithium secondary battery according to any one of claims 4 to 8, wherein the method is selected.