JPH0959023A - Lithium-manganese multiple oxide, its production and use thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject new multiple oxide of specified composition formula, hopeful of applications as a catalyst, adsorbent, dielectric or magnetic material as well as a battery material. SOLUTION: This Li-Mn multiple oxide is expressed by the composition formula Lix MnO4 ((x) satisfies the relationship: 5<=(x)<=7). When (x) is 6, the multiple oxide is the most stable and also easy to synthesize. This multiple oxide is obtained by mixing at least one kind of Li stock selected from metallic Li, Li oxide and Li sulfide with at least one kind of Mn stock selected from MnO, Mn2 O3 and α-type MnO2 at the molar ratio Li/Mn of (5:1) to (7:1) followed by baking in an atmosphere such as inert gas or hydrogen gas. This multiple oxide is of superstructural reverse fluorite type, and the Li sites in the crystal structure are linked to one another in a three-dimensional way, the Li atoms in the crystal are highly mobile and thus extremely rapid in diffusion, leading to anode-active substances and non-aqueous secondary batteries.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel lithium manganese composite oxide and a method for producing the same, and in particular, the lithium manganese composite oxide of the present invention is capable of charging and discharging a large capacity positive electrode active material and non-aqueous system. It can be usefully used as a secondary battery. Further, the novel lithium manganese oxide of the present invention,
In addition to battery materials, applications as catalysts, adsorbents, dielectrics, magnetic materials are also expected.

[0002]

2. Description of the Related Art Manganese oxides have been widely studied because their raw materials are inexpensive and they are used in various industrial applications. For example, manganese dioxide MnO ₂ is α type, β type, γ type, δ type.
It has many crystal structures such as type, ε type, η type, λ type, electrolytic type or ramsdellite type. Besides, Mn ₂ O ₃ and M
nO etc. exist. This is because Mn exists relatively stably in a wide range of valences from 2+ to 7+, and even if the valence is the same, its substantial ionic radius can be largely changed by the coordination number. Therefore, if another element is further added to form a compound of A-Mn-O ternary system, its kind becomes enormous, and there are several kinds of crystal forms for each compound.

Among these, A is Li and spinel type LiMn as a lithium-manganese oxide.
Several stable crystal structures are known, such as ₂ O ₄ , layered LiMnO ₂ and Li ₂ MnO ₃ . These are now widely studied as positive electrode active materials for lithium secondary batteries. In addition, LiCoO ₂ , LiNiO _{2 and the} like are currently widely used as other positive electrode active materials for lithium secondary batteries, but when operated as an actual battery, the capacity as the positive electrode is the theoretical capacity of these active materials. The current situation is that it is only close to half. Electrochemically, it is possible to obtain a capacity of about 70 to 80% of their theoretical capacity, but in that case the cycle performance becomes extremely poor, and a practical secondary battery cannot be constructed.

This is because LiCoO ₂ , LiNiO _{2 and the} like have a so-called layered structure, which is composed of a Li layer and a CoO layer or a NiO layer. If Li is excessively removed from the Li layer, the layered structure cannot be maintained, so the crystal structure itself. Is collapsed. Further, since the change in the lattice constant itself due to the insertion and desorption of Li is relatively large, expansion and contraction will be repeated as charging and discharging are repeated. This results in peeling of the active material from the current collector, which is also one of the reasons for lowering the capacity.

Further, LiCoO ₂ and LiNiO ₂ exist in the crystal in the states of Co ³⁺ and Ni ³⁺ . When these oxides are used as the positive electrode, Li is electrochemically extracted from the structure by charging, but at this time, both Ni and Co are oxidized from 3+ to 4+. The maximum oxidation number of both Co and Ni is 4+, and further oxidation cannot be performed. Therefore, even if all the Li can be electrochemically extracted by charging, the electric capacity is 1 electron. It cannot exceed the equivalent.

Further, these compounds are compounds having a so-called layered crystal structure, and the Li layer is a CoO ₂ layer or a Ni layer.
It is completely blocked by the O ₂ layer, which is considered to prevent smooth diffusion of Li. This is one of the reasons why it is difficult to charge and discharge with a large current. Furthermore, Co is a very expensive raw material and has a limited reserves.
The price of raw materials may rise in the future. This results in a significant increase in the cost of the battery itself. On the other hand, Ni is cheaper than Co, but
LiNiO ₂ needs to be fired in an oxygen stream, and as a result, the cost per unit weight does not differ much from that of LiCoO ₂ .

Therefore, as a positive electrode active material using Mn, which is a material cheaper than Ni and Co, a spinel type LiMn ₂ O ₄ or a composite oxide obtained by adding another element to LiMn ₂ O ₄ as described above is used. JP-A-4-14757 and JP-A-4-14757
It is described in JP-A-141954, JP-A-4-147573 and JP-A-6-227820. Since the spinel type LiMn ₂ O ₄ has Li located at the center of the tetrahedron and Mn located at the octahedral site sharing a ridge with each other, the structure is robust even if Li is electrochemically removed. Is maintained. Therefore, the change in lattice constant is small and the cycle characteristics are excellent.

However, when used as the positive electrode of a lithium secondary battery, the spinel type oxide has a problem that the electrolytic solution is easily decomposed because the potential is too high. As can be seen from the composition, Li: Mn is 1: 2.
Therefore, even if all Li can be used, there is a problem that its electric capacity is smaller than that of LiCoO ₂ and LiNiO ₂ .

As described above, each of the known oxides has problems, and it is desired to use a novel positive electrode active material in order to provide a lithium secondary battery having excellent characteristics and economical efficiency. The present invention has been made in view of the above problems, and an object thereof is to provide a positive electrode active material having a larger capacity than conventional positive electrode active materials by using inexpensive Mn as a raw material.

[0010]

DISCLOSURE OF THE INVENTION The inventors of the present invention have found that the lithium / metal molar ratio is 1 or more, that is, a lithium-rich compound containing an element whose valence of the metal can change by 1 or more. If is used as the positive electrode, the capacity is very large because lithium can escape from 1 equivalent or more, and even if 1 equivalent or more is removed, lithium still remains in the crystal structure, so that the crystal structure does not collapse, which is good. It was thought that a charge / discharge cycle could be performed and the above-mentioned problems could be overcome.

As compounds satisfying these conditions, compounds having various compositions and structures are conceivable, but the inventors of the present invention have not reported the novel compound L.
It has been found that the superstructure inverted fluorite type compound represented by i _x MnO ₄ (5 ≦ x ≦ 7) is a very promising material.
Thus, according to the present invention, the composition formula is Li _x MnO 2.
There is provided a lithium-manganese composite oxide, characterized in that it is composed of ₄ (x is 5 ≦ x ≦ 7).

Furthermore, according to the present invention, metallic lithium, lithium oxide, lithium sulfide, lithium nitride, lithium fluoride, lithium chloride, lithium bromide, lithium iodide,
One selected from the group consisting of lithium hydroxide, lithium nitrate, lithium carbonate, lithium formate, lithium acetate, lithium benzoate, lithium citrate, lithium lactate, lithium oxalate, lithium pyruvate, lithium stearate and lithium tartrate. Alternatively, two or more kinds of lithium raw materials and MnO, Mn ₂ O ₃ , α-type MnO ₂ , β-type MnO
_2, gamma-type MnO _2, [delta] type MnO _2, epsilon-type MnO _2, eta-type MnO _2, lambda-type MnO _2, electrolytic MnO _2, ramsdellite _{MnO 2, MnOOOH, LiMnO 2,} LiM
Mixing one or more manganese raw materials selected from the group consisting of n ₂ O ₄ , Li ₂ MnO ₃ , and metallic manganese so that the molar ratio of lithium to manganese is 5: 1 to 7: 1. Then, by firing in an inert gas atmosphere, a hydrogen gas atmosphere, a hydrogen-inert gas atmosphere or an oxygen-inert gas mixed atmosphere, the composition formula Li _x MnO ₄ (x
Provides a lithium manganese composite oxide consisting of 5 ≦ x ≦ 7).

Further, according to the present invention, there is provided a positive electrode active material characterized by using the above-mentioned lithium manganese composite oxide. Furthermore, according to the present invention, a positive electrode containing the lithium manganese composite oxide as a positive electrode active material,
Provided is a non-aqueous secondary battery comprising a negative electrode made of a lithium metal or a carbon material capable of inserting and extracting lithium, and an ionic conductor.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of various experiments for carrying out the present invention, it was found that Li ₆ MnO ₄ exists most stably as a lithium-rich compound in the Li-Mn-O-based compound. . In addition, Li _X MnO ₄
It has been found that compounds having a Li: Mn ratio represented by (5 ≦ x ≦ 7) other than 6: 1 can also be present. In the following description, x = 6, that is, Li ₆ MnO ₄ will be described. This is because Li ₆ MnO ₄ exists most stably and is easy to synthesize, so that the description of the present invention can be simplified. However, the present invention is not limited to this composition.

The Li ₆ MnO ₄ of the present invention has a space group P42 /
belongs to nmc and Li at 8f and 4d sites and M at 2a sites
O is located at the n and 8g sites. The basic structure is shown in FIG. In FIG. 1, Li and Mn are present in the center of a tetrahedron having four oxygen atoms as vertices in the crystal structure,
It can be described as an inverted fluorite type superstructure. 1, A
Indicates lithium, and B indicates a tetrahedron having four oxygen atoms having Mn at the central position as vertices.

Generally, in order to have an inverted fluorite type structure, when A is a cation and B is an anion, the relation of A = 2B must be established. However, according to the present invention, Li ₆ MnO ₄
In the above, there are a total of seven Li ions as cations and one Mn ion, and four O ions as anions, and A <2B does not hold and A <2B holds. Therefore,
Although the atomic arrangement itself is an inverted fluorite type, it can be regarded as a novel compound having a very characteristic structure in which a part of its Li site is missing.

Li of the present invention₆MnO_FourAbout Cu
Powder X-ray circuit using a sealed X-ray tube as a target
X-ray diffraction pattern as shown in Fig. 2
Obtained. This pattern is based on previously reported Li₆
CoO_FourHas a pattern very similar to, but slightly
The lattice constants are different. In addition, powder X-ray simulation
Space group P42
Li belonging to / nmc ₆MnO_FourConfirmed to be
Was. Li₆MnO_FourX-ray diffraction pattern of 2θ = 1
8.5-19.0, 23.0-23.5, 26.5-2
7.0, 32.8 to 33.3, 35.5 to 36.0, 4
2.8-43.4, 45.0-45.5, 55.3-5
Each has a peak in the range of 5.8. Also that
The peak intensity ratio exists at 2θ = 23.0 to 23.5 °
When the peak intensity is defined as 100, 32 and
At 100, 20, 75, 75, 48, 21, 27, 38
is there.

The lithium manganese composite oxide of the present invention is
It has 6 Li for 1 Mn. Therefore, even if 1 or more Li is desorbed, 5 Li still remains.
Remain, and the crystal structure can be sufficiently maintained. Considering the crystal state at this time, even if Li ₆ MnO _{4 is changed} to Li ₅ MnO ₄ , only about 16% of Li existing in the crystal is lost, and the change in the lattice volume itself is LiCoO 4. Extremely small compared to ₂ .

Further, in the lithium-manganese composite oxide of the present invention, Mn is present in these crystals in the state of Mn ²⁺ . Since Mn can exist in an oxidation state of up to 6+, it is possible to carry out an insertion / desorption reaction of 1 equivalent or more of Li in the crystal structure. In each of the lithium manganese oxides of the present invention, Li and Mn are located in the center of a tetrahedron having oxygen as the apex, and the lithium / Mn atomic ratio is 6, which is very large.
Therefore, Li sites in the crystal structure are substantially three-dimensionally connected, and Li easily moves into the crystal structure.
For this reason, the diffusion of Li is extremely fast and is suitable for charging and discharging with a large current.

In the method for producing a lithium manganese composite oxide of the present invention, the manganese raw material is metallic manganese,
MnO, Mn ₂ O ₃ , MnO ₂ , MnOOH, LiMn
_{O 2, LiMn 2 O 4,} Li 2 MnO 3 and the like.
MnO ₂ includes α type, β type, γ type, δ type, ε type, η type, λ
Having a crystalline structure of electric field type, electric field type or ramsdellite type
Both nO ₂ can be used. Moreover, you may use these manganese raw materials 1 type or in combination of 2 or more types.
Here, since Mn exists in the state of Mn ²⁺ in Li ₆ MnO ₄ , it is preferable to use one that is Mn ²⁺ at the stage of the raw material. A particularly preferable manganese raw material is Mn.
O.

On the other hand, as the lithium raw material, lithium oxide, lithium peroxide, lithium sulfide, lithium nitride, lithium fluoride, lithium chloride, lithium bromide, lithium iodide, lithium hydroxide, lithium nitrate, lithium carbonate, lithium formate are used. , Lithium acetate, lithium benzoate,
Lithium citrate, lithium lactate, lithium oxalate,
Examples include lithium pyruvate, lithium stearate and lithium tartrate. You may use these lithium raw materials 1 type or in combination of 2 or more types.

The raw materials are preferably mixed such that the atomic ratio of Li and Mn is 6: 1. However, depending on the firing conditions and the raw materials, Li may sublime or evaporate during firing. 5: 1 to 1 other than Li: Mn = 6: 1
It can also be synthesized with a mixing ratio of 7: 1. When metallic manganese powder is used as the manganese raw material, in order to obtain Li ₆ MnO ₄ , the lithium raw material containing lithium and oxygen having the composition of Li ₆ MnO ₄ may be used. For example, the composition ratio can be determined for each of Li, Mn, and O, such as Mn + Li ₂ O ₂ + 2Li ₂ O → Li ₆ MnO ₄ .

Li ₆ MnO ₄ can be produced, for example, by pulverizing and mixing the above raw materials in an agate mortar, molding into pellets, and firing. Firing temperature is 3
The temperature is preferably 00 to 2000 ° C. It should be noted that if the temperature is too low, the reactivity is poor, and therefore a long period of firing is required to obtain a single phase. Conversely, if the temperature is too high, Li sublimation-
The scattering is severe and the manufacturing cost is high.
Therefore, a particularly preferable firing temperature is 600 ° C to 950 ° C.

The atmosphere during firing may be an inert gas atmosphere of 99.9% or more, a hydrogen gas atmosphere, a hydrogen-inert gas mixed gas stream or an oxygen-inert gas mixed gas stream. As the inert gas that can be used in the above atmosphere, He,
N ₂ , Ar, Ne, Kr and the like can be mentioned. These inert gases can be used alone or in combination of two or more.

In this inert gas atmosphere, 0.1%
As long as it is contained, H ₂ O, CO _{2 and the} like as impurities are not affected. Since it is preferable to synthesize Mn in the 2+ state as described above, it is preferable that the oxygen partial pressure is lower than that in the atmosphere when Li ₆ MnO ₄ is synthesized. The oxygen partial pressure is more preferably 1% or less in terms of volume fraction. This means that hydrogen gas atmosphere, hydrogen-
The same applies to the case of firing under an inert gas mixed gas stream or an oxygen-inert gas mixed gas stream.

Mn can have various valences, but Mn ²⁺ is M
If it is desired to reduce to the n ¹⁺ or Mn ⁰ state, a fairly high concentration of hydrogen partial pressure is required. For this reason, the mixing ratio of hydrogen and the inert gas under the hydrogen-inert gas mixed flow used in the present invention is 0.1% H ₂ -99.9% A, where A is the inert gas. Fifty
% H ₂ -50% A is preferred. However, if hydrogen is used at a high concentration, the degree of danger increases, so 0.5% H ₂ -99.5% A to 3% H ₂ -97% A is more preferable.

The above manufacturing method is applied to Li _X MnO ₄ (5 ≦ x
The same can be applied to compounds having a Li: Mn ratio represented by ≦ 7) other than 6: 1. The lithium manganese composite oxide produced as described above is preferably used as a positive electrode active material. Further, it can be used as a catalyst, an adsorbent, a dielectric, and a magnetic material.

Further, the lithium secondary battery using the lithium manganese composite oxide of the present invention comprises a positive electrode, a negative electrode and an ionic conductor. The positive electrode is formed by mixing a lithium manganese composite oxide powder as a positive electrode active material, a conductive agent, a binder, and optionally a solid electrolyte. A carbon material such as acetylene black or graphite powder, metal powder, conductive ceramics, or the like can be used as the conductive agent that can be used in the present invention, but is not limited thereto.

As the binder, polytetrafluoroethylene,
Fluorine-based polymers such as polyvinylidene fluoride and polyolefin-based polymers such as polyethylene and polypropylene can be used, but are not limited thereto. The mixing ratio of these materials forming the positive electrode is preferably 1 to 50 parts by weight of the conductive agent and 1 to 50 parts by weight of the binder with respect to 100 parts by weight of the lithium manganese oxide. If the amount of the conductive agent is less than 1% by weight, the resistance or polarization of the electrode increases and the capacity of the electrode decreases, so that a practical lithium secondary battery cannot be constructed. On the other hand, if the amount of the conductive agent is larger than 50 parts by weight, the amount of lithium manganese oxide in the electrode is decreased and the capacity is reduced, which is not preferable. If the amount of the binder is less than 1 part by weight, the binding ability will be lost and the electrode cannot be formed. On the other hand, if the amount of the binder is more than 30 parts by weight, the resistance or polarization of the electrode is increased and the amount of lithium manganese oxide in the electrode is decreased, so that the capacity is reduced, which is not practical.

The positive electrode may be formed by a method in which these mixtures are pressed onto a current collector or dissolved in a solvent such as N-methyl-2-pyrrolidone to form a slurry, which is applied to the current collector and dried. . Metal foil, metal mesh,
A conductor such as metal non-woven cloth can be used. The material and shape of the current collector are not limited to these. On the other hand, for the negative electrode in the non-aqueous secondary battery of the present invention, a lithium alloy such as metallic lithium or lithium aluminum can be used. Further, substances capable of inserting and releasing lithium ions, for example, conductive polymers such as polyacetylene, polythiophene, polyparaphenylene, pyrolytic carbon, pyrolytic carbon vapor-decomposed in the presence of a catalyst, pitch, coke, tar. Carbon obtained by firing carbon, cellulose, polymer such as phenol resin, graphite material such as natural graphite, artificial graphite, expanded graphite, and lithium ion insertion / desorption reaction WO
₂ , MoO _{2 and the} like. These may be used alone or as a mixture thereof. Further, the negative electrode is formed by pressing the current collector alone or a mixture thereof into a current collector or by dissolving it in a solvent such as N-methyl-2-pyrrolidone to form a slurry, coating the current collector and drying the slurry. Good.
A conductor such as a metal foil, a metal mesh, or a metal non-woven cloth can be used as the current collector. The material and shape of the current collector are not limited to these.

Furthermore, the ionic conductor in the non-aqueous secondary battery of the present invention includes, for example, an organic electrolyte solution, a polymer solid electrolyte,
An inorganic solid electrolyte, a molten salt or the like can be used. Of these, organic electrolytes are preferred. The organic electrolyte is composed of an organic solvent and an electrolyte. Examples of the organic solvent include esters such as propylene carbonate, ethylene carbonate, butylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, γ-butyrolactone, substituted hydrofurans such as tetrahydrofuran and 2-methyltetrahydrofuran, dioxolane, diethyl ether, dimethoxyethane. , Ethers such as diethoxyethane and methoxyethoxyethane, dimethylsulfoxide, sulfolane, methylsulfolane, acetonitrile, methyl formate, and methyl acetate. These organic solvents may be used alone or in combination of two or more.

Examples of the electrolyte include lithium salts such as lithium perchlorate, lithium borofluoride, lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium trifluoromethanesulfonate, lithium halides and lithium chloroaluminate. You may use these electrolytes individually or in combination of 2 or more types. The organic solvent and the electrolyte are not limited to the above. Further, it is preferable that the organic solvent and the electrolyte are dehydrated with active aluminum, metallic lithium or the like before use. The water content in the organic solvent and the electrolyte is preferably 1000 ppm or less,
It is more preferably 100 ppm. Further, instead of the dehydration step, a previously dehydrated electrolyte and / or solvent may be used.

The non-aqueous secondary battery according to the present invention can be constructed by bonding the positive electrode and the negative electrode to an external electrode, respectively, and further interposing the ionic conductor therebetween. If necessary, a separator such as porous polyethylene or porous polypropylene may be interposed together with the ionic conductor. The material and shape of the separator are not particularly limited. Further, it is preferable to carry out packing or hermetic sealing of polypropylene or polyethylene so that the external electrodes to which the positive electrode and the negative electrode are joined do not come into contact with each other. These battery manufacturing steps are preferably performed in an inert atmosphere such as argon or in extremely dry air in order to prevent entry of moisture.

The shape of the non-aqueous secondary battery of the present invention is not particularly limited, and examples thereof include a cylindrical type, a button type, and a square type. According to the above invention, the composition formula is Li _x MnO ₄ (x is 5).
There is provided a novel lithium-manganese composite oxide, characterized in that ≦ x ≦ 7). According to the production method of the present invention, metallic lithium, lithium oxide, lithium sulfide, lithium nitride, lithium fluoride, lithium chloride, lithium bromide, lithium iodide, lithium hydroxide, lithium nitrate, lithium carbonate, lithium formate, acetic acid. One or more lithium raw materials selected from the group consisting of lithium, lithium benzoate, lithium citrate, lithium lactate, lithium oxalate, lithium pyruvate, lithium stearate and lithium tartrate, and MnO and Mn ₂ O. ₃ ,
α-type MnO ₂ , β-type MnO ₂ , γ-type MnO ₂ , δ-type Mn
O _2, ε-type MnO _2, η-type MnO _2, λ-type MnO _2, electrolytic MnO _2, ramsdellite MnO _2, MnOOO
H, LiMnO ₂ , LiMn ₂ O ₄ , Li ₂ MnO ₃ ,
One or more manganese raw materials selected from the group consisting of metallic manganese are mixed so that the molar ratio of lithium to manganese is 5: 1 to 7: 1, and hydrogen gas is added in an inert gas atmosphere. By firing in an atmosphere, in a hydrogen-inert gas mixed atmosphere or in an oxygen-inert gas mixed atmosphere, a lithium manganese composite oxide having a composition formula Li _x MnO ₄ (x is 5 ≦ x ≦ 7) is formed. Therefore, the lithium manganese composite oxide can be easily produced.

The lithium manganese composite oxide of the present invention is
Since it has 7 to 5 Li for one Mn,
When used for the positive electrode active material and the non-aqueous secondary battery, even if one Li is desorbed, 6 to 4 Li still remain, and the crystal structure is sufficiently maintained. For example, Li
Even when Li was desorbed from ₆ MnO ₄ to Li ₅ MnO ₄ , only about 16% of the existing Li was released, and the change in the lattice volume itself was extremely small as compared with LiCoO ₂ .

Further, the lithium manganese composite oxidation of the present invention
The material takes the superstructure inverted fluorite type, and the Li site in the crystal structure is
They are connected in a substantially three-dimensional manner, and Li is included in the crystal structure.
Due to the ease of movement, the diffusion of Li is extremely fast, and with a large current
A positive electrode active material and a non-aqueous secondary battery capable of charging and discharging are obtained.
It is. Furthermore, the lithium manganese composite oxide of the present invention,
Mn is Mn in these crystals ²⁺Exists in the state of
Since Mn can exist up to 6+ oxidation states,
Insertion / desorption reaction of more than 1 equivalent of Li is possible from the unit structure
High-capacity positive electrode active material and non-aqueous secondary battery
Can be

In addition, since the lithium manganese composite oxide of the present invention uses Mn as a raw material, the raw material price is cheaper than Co and Ni, and the positive electrode active material and the non-aqueous electrolyte having high industrial value are high. The next battery is obtained.

[0038]

EXAMPLES Specific examples will be shown below, but the present invention is not limited thereto. Example 1 A positive electrode active material was synthesized by the following method.

First, MnO and Li₂O is an atom of Li and Mn
Agate by weighing so that the ratio is 5: 1, 6: 1, 7: 1
Mixing was performed in a mortar. This is 150k with a hydraulic press
g / cm²Is applied to a disk shape with a diameter of 8 mm and a thickness of 3 mm.
Pressure formed. The work of weighing-mixing-press forming up to here is
It was performed in dry air with a humidity of 1% or less. Like this
Place the resulting pellets on a porcelain boat in an electric furnace.
1% H₂-99% N ₂Gas was introduced. In the electric furnace
Atmosphere is 1% H₂-99% N₂Replaced by gas enough
After that, the temperature of the electric furnace is raised from room temperature to 950 ° C.,
React the pellet by holding it at 950 ° C for 3 hours.
I let you. 1% H during heating and holding time₂-99% N₂
The gas was flowed at a flow rate of 2 liters / minute. Predetermined retention time
After the lapse of time, lower the temperature of the electric furnace, and
The sample was taken out after reaching a temperature near the temperature. like this
All of the powders obtained in Step 1 had a gray color.

The starting composition is an atomic ratio of Li to Mn of 5: 1,
6: 1 and 7: 1 are Aa1, Aa2 and Aa respectively
3, the composition after sintering is Li_FiveMnO_Four,
Li ₆MnO_Four, Li₇MnO_FourMet. Aa1 powder
The final X-ray diffraction pattern is shown in FIG. As an X-ray source,
Measured at output of 2kW using target Cu enclosure tube
Was done. X-ray diffraction of Aa1, Aa2, Aa3
The patterns are 2θ = 18.5 to 19.0 and 23.
0-23.5, 26.5-27.0, 32.8-33.
3, 35.5-36.0, 42.8-43.4, 45.
0 to 45.5 and 55.3 to 55.8, respectively.
Had an ark.

When the peak intensity existing at 2θ = 23.0 to 23.5 ° is defined as 100, the peak intensity ratios are 30 to 100, 100, 15 to 25 and 45 to 5, respectively.
75, 45-75, 18-50, 20-30, 20-3
It was 0 to 25 to 50. As a result of powder X-ray simulation and powder X-ray structural analysis, space group P42 / nm
The best agreement with the result when the process was c
1, Aa2 and Aa3 are Li ₅ MnO ₄ and Li ₆ respectively.
It was confirmed to be MnO ₄ and Li ₇ MnO ₄ . Example 2 A sample was prepared using exactly the same procedure as in Example 1 except that the firing temperature was set to 600 ° C. Starting composition is Li and M
The atomic ratios of n of 5: 1, 6: 1, and 7: 1 are referred to as Ab1, Ab2, and Ab3, respectively. The X-ray diffraction pattern of the powder of Ab2 is shown in FIG. The X-ray diffraction measurement was performed under the same conditions as in Example 1.

The X-ray diffraction patterns of Ab1, Ab2 and Ab3 are 2θ = 18.5 to 19.0 and 2 respectively.
3.0 to 23.5, 26.5 to 27.0, 32.8 to 3
3.3, 35.5-36.0, 42.8-43.4, 4
It had peaks in the ranges of 5.0 to 45.5 and 55.5 to 55.8, respectively. Further, 2θ = 23.0 to 23.
When the peak intensity existing at 5 ° C is defined as 100,
The peak intensity ratio is 30 to 100, 100, 1 respectively.
5-25, 45-75, 45-75, 18-50, 20
-30, 20-30, 25-50.

As a result of the powder X-ray simulation and the powder X-ray structural analysis, the results best agree with the results when assuming that the space group is P42 / nmc, Ab1, Ab2,
Ab3 is Li ₅ MnO ₄ , Li ₆ MnO ₄ , L
It was confirmed to be i ₇ MnO ₄ .

Example 3 A sample was prepared using exactly the same procedure as in Example 1 except that the firing atmosphere was 100% H ₂ . Starting composition is L
The atomic ratios of i: Mn of 5: 1, 6: 1, and 7: 1 are referred to as Ac1, Ac2, and Ac3, respectively.

The X-ray analysis pattern of the Ac3 powder is shown in FIG. The X-ray analysis measurement was performed under the same conditions as in Example 1.
The X-ray analysis patterns of Ac1, Ac2, and Ac3 are all 2θ = 18.5 to 19.0, 23.0 to 23.
5, 26.5-27.0, 32.8-33.3, 35.
5-36.0, 42.8-43.4, 45.0-45.
It had a peak in the range of 5, 55.3 to 55.8, respectively. Further, when the peak intensity existing at 2θ = 23.0 to 23.5 ° C. is defined as 100, the peak intensity ratios are 30 to 100, 100, 15 to 25 and 45, respectively.
~ 75, 18-50, 20-30, 20-30, 25-
It was 50.

As a result of the powder X-ray simulation and the powder X-ray structural analysis, the results best agree with the results assuming that the space group is P42 / nmc, Ac1, Ac2,
Ac3 is Li ₅ MnO ₄ , Li ₆ MnO ₄ and L, respectively.
It was confirmed to be i ₇ MnO ₄ .

Example 4 A sample was prepared using exactly the same procedure as in Example 1 except that the firing atmosphere was 100% Ar. Starting composition is L
The atomic ratios of i and Mn of 5: 1, 6: 1 and 7: 1 are Ad1, Ad2 and Ad3, respectively.

The X-ray analysis pattern of this powder is shown in FIG. The X-ray diffraction measurement was performed under the same conditions as in Example 1. A
The X-ray diffraction patterns of d1, Ad2 and Ad3 are 2θ = 18.5 to 19.0, 23.0 to 23.
5, 26.5-27.0, 32.8-33.3, 35.
5-36.0, 42.8-43.4, 45.0-45.
It had a peak in the range of 5, 55.3 to 55.8, respectively. Further, when the peak intensity existing at 2θ = 23.0 to 23.5 ° C. is defined as 100, the peak intensity ratios are 30 to 100, 100, 15 to 25 and 45, respectively.
~ 75, 45-75, 18-50, 20-30, 20-20
It was 30, 25-50.

As a result of the powder X-ray simulation and the powder X-ray structural analysis, the results best agree with the results assuming that the space group is P42 / nmc, Ad1, Ad2,
Ad3 is Li ₅ MnO ₄ , Li ₆ MnO ₄ and L, respectively.
It was confirmed to be i ₇ MnO ₄ .

Example 5 Example 1 except that the firing atmosphere was 1% O ₂ -99% N _2.
The sample was prepared using exactly the same procedure as. Ae, Ae2, and Ae3 having a starting composition of Li: Mn in an atomic ratio of 5: 1, 6: 1, and 7: 1 are referred to as Ae1, Ae2, and Ae3.

The X-ray diffraction measurement was carried out under the same conditions as in Example 1. The X-ray diffraction patterns of Ae1, Ae2, and Ae3 are 2θ = 18.5 to 19.0 and 23.0 to
23.5, 26.5 to 27.0, 32.8 to 33.3,
35.5-36.0, 42.8-43.4, 45.0-
There were peaks in the ranges of 45.5 and 55.3 to 55.8, respectively. When the peak intensity existing at 2θ = 23.0 to 23.5 ° is defined as 100, the peak intensity ratios are 30 to 100, 100, and 15 to 2, respectively.
5, 45-75, 45-75, 18-50, 20-3
It was 0, 20-30, 25-50.

As a result of the powder X-ray simulation and the powder X-ray structural analysis, the results best agree with the results assuming that the space group is P42 / nmc, and Ae1, Ae2,
Ae3 is Li ₅ MnO ₄ , Li ₆ MnO ₄ , L
It was found to be i ₇ MnO ₄ .

Example 6 Example 1 except that MnOOH and Li ₂ O ₂ were used as raw materials.
The sample was prepared using exactly the same procedure as. Af1, Af2, and Af3 having a starting composition of Li: Mn at an atomic ratio of 5: 1, 6: 1, and 7: 1 are designated as Af1, Af2, and Af3, respectively. The X-ray diffraction measurement was performed under the same conditions as in Example 1. Af1, Af
X-ray diffraction patterns of 2 and Af3 are both 2θ
= 18.5 to 19.0, 23.0 to 23.5, 26.5
.About.27.0, 32.8 to 33.3, 35.5 to 36.
0, 42.8 to 43.4, 45.0 to 45.5, 55.
Each had a peak in the range of 3 to 55.8. When the peak intensity existing at 2θ = 23.0 to 23.5 ° is defined as 100, the peak intensity ratios are 30 to 100, 100, 15 to 25, 45 to 75, and 4, respectively.
5 to 75, 18 to 50, 20 to 30, 20 to 30, 25
It was ~ 50.

As a result of the powder X-ray simulation and the powder X-ray structural diffraction, the results are in the best agreement with the results assuming that the space group is P42 / nmc, Af1, Af2,
Af3 is Li ₅ MnO ₄ , Li ₆ MnO ₄ , L
It was confirmed to be i ₇ MnO ₄ .

[0055] EXAMPLE 7 raw material Mn and Li ₂ O and Li ₂ O ₂ in a molar ratio of _{Ag1: Mn: Li 2 O:} Li 2 O 2 = 1: 1: 5 Ag2: Mn: Li 2 O: Li 2 O ₂ = 1: 2: 1 Ag 3: Mn: Li ₂ O: Li ₂ O ₂ = 1: 3: 0.5 using the same procedure as in Example 1, except that a mixture was used. Adjustments were made.

Diffraction measurement was performed under the same conditions as in Example 1. The X-ray diffraction patterns of Ag1, Ag2, and Ag3 are all 2θ = 18.5 to 19.0, 23.0 to 23.5,
26.5-27.0, 32.8-33.3, 35.5
36.0, 42.8 to 43.4, 45.0 to 45.5,
Each had a peak in the range of 55.3 to 55.8. Moreover, when the peak intensity existing in 2θ = 23.0 to 23.5 ° is defined as 100, the peak intensity ratios are 30 to 100, 100, 15 to 25, and 45 to 7, respectively.
5, 45-75, 18-50, 20-30, 20-3
It was 0 to 25 to 50.

As a result of the powder X-ray simulation and the powder X-ray structural analysis, the results best agree with the results assuming that the space group is P42 / nmc, Ag1, Ag2,
Ag3 is Li ₅ MnO ₄ , Li ₆ MnO ₄ and L, respectively.
It was confirmed to be i ₇ MnO ₄ .

Comparative Example 1 A sample was prepared by using the same procedure as in Example 1 except that the firing temperature was 500 ° C. Starting composition is Li and M
Those having an atomic ratio of n of 5: 1, 6: 1, and 7: 1 are designated as Ba1, Ba2, and Ba3, respectively.

The X-ray diffraction pattern of this powder is shown in FIG. The X-ray diffraction measurement was performed under the same conditions as in Example 1. As a result of powder X-ray simulation and powder X-ray structural analysis, it was confirmed that the mixture was a mixture of Li ₂ O and MnO as raw materials.

Comparative Example 2 A sample was prepared by using the same procedure as in Example 1 except that the firing temperature was 1250 ° C. The starting compositions having an atomic ratio of Li and Mn of 5: 1, 6: 1 and 7: 1 are designated as Bb1, Bb2 and Bb3, respectively.

The X-ray diffraction pattern of this powder is shown in FIG. The X-ray diffraction measurement was performed under the same conditions as in Example 1. As a result of powder X-ray simulation and powder X-ray structural analysis, it was confirmed to be a mixture of LiMn ₂ O ₄ and Li ₂ O.

Comparative Example 3 A sample was prepared using exactly the same procedure as in Example 1 except that the firing atmosphere was 2% O ₂ -98% N ₂ . The starting compositions having an atomic ratio of Li to Mn of 5: 1, 6: 1 and 7: 1 are designated as Bc1, Bc2 and Bc3, respectively.

The X-ray diffraction pattern of this powder is shown in FIG. The X-ray diffraction measurement was performed under the same conditions as in Example 1. As a result of powder X-ray simulation and powder X-ray structural analysis, it was confirmed to be a mixture of LiMn ₂ O ₄ and Li ₂ O.

Comparative Example 4 The starting composition of Example 1 was 4.9 in terms of atomic ratio of Li and Mn:
The samples were prepared using exactly the same procedure except that the ratio was 1, 7.1: 1. The atomic ratio of Li and Mn is 4.9: 1,
7.1: 1 is referred to as Bd1 and Bd2, respectively.

The X-ray diffraction pattern of this powder is shown in FIG. The X-ray diffraction measurement was performed under the same conditions as in Example 1. As a result of powder X-ray simulation and powder X-ray structural analysis, it was confirmed to be a mixture of Li ₆ MnO ₄ , Li ₂ O and MnO.

Embodiment 8 FIG. 11 is a schematic view of a three-pole battery which is an embodiment of the present invention. In FIG. 11, 10 is an ionic conductor, 11 is a negative electrode, and 11
a is a lead, 12 is a counter electrode, 13 is a positive electrode, 14 is a tube, 14
a is an opening, 15 is a glass cell, and 16 is a lid.

About 10% by weight of acetylene black was mixed as a conductive agent with the powder obtained by crushing Aa1, Aa2 and Aa3 of Example 1 in a mortar, and then about 10% by weight of Teflon resin powder was mixed as a binder. did. This was shaped into a pellet by a tablet molding machine, and was pressed onto a metal mesh to obtain a positive electrode 13. As the negative electrode 11 and the counter electrode 12, a metal lithium sheet pressure-bonded to a Ni mesh was used. As the ion conductor 10, 50% by volume of ethylene carbonate-5
A solution prepared by dissolving 1 mol / liter of LiClO ₄ in 0% by volume of diethylene carbonate was used. The positive electrode 13, the negative electrode 11, and the ionic conductor 10 were incorporated into a container glass cell 15 and a charge / discharge test was conducted. The above work was performed in an Ar dry box.

FIG. 12 shows changes in potential when charging and discharging were performed with a constant current of Aa2, and Table 1 shows capacities of Aa1, Aa2, and Aa3 during discharging. About 160mA at the first charge
A very large capacity of h / g is obtained, and the potential is also very flat. This capacity corresponds to the capacity when one Li is completely removed from Li ₆ MnO ₄ . The potential of the discharge gradually decreased, and a discharge capacity of about 160 mAh / g was obtained.

[0069]

[Table 1]

From Table 1, it was found that the battery of Example 8 had a large capacity and high charge / discharge efficiency.

Example 9 Aa1, Aa2, and Aa3 of Example 1 were ground in a mortar and mixed with about 1% by weight of acetylene black as a conductive agent, and then about 50% by weight of Teflon resin powder was mixed. It was mixed as a binder. This was shaped into pellets with a tablet molding machine, and was pressed onto a metal mesh to obtain a positive electrode.

A metallic lithium sheet Ni is used for the negative electrode and the counter electrode.
What was crimped to the mesh was used. As the ionic conductor, one obtained by dissolving 1 mol / liter of LiPF ₆ in 50 vol% propylene carbonate-50 vol% tetrahydrofuran was used. The positive electrode, the negative electrode, and the ionic conductor were incorporated into a glass cell similar to that used in Example 8, and a charge / discharge test was performed.

Table 2 shows the change in capacity during charging / discharging when charging / discharging was performed at a constant current.

[0074]

[Table 2]

From Table 2, it was found that the battery of Example 9 had a large capacity and high charge / discharge efficiency.

Example 10 FIG. 13 is a schematic view of a coin battery which is an example of the present invention. In FIG. 13, 1 is a positive electrode can, 2 is a positive electrode current collector, 3 is a positive electrode, 4 is a negative electrode can, 5 is a negative electrode current collector, 6 is a negative electrode, 7 is a separator, and 8 is a packing.

Approximately 50% by weight of acetylene black was mixed as a conductive agent with the powder obtained by crushing each of Aa1, Aa2 and Aa3 of Example 1 in a mortar, and then about 1% by weight of Teflon resin powder was used as a binder. Mixed. This was shaped into a pellet by a tablet molding machine, and was pressed onto a metal mesh to obtain a positive electrode 3. Next, about 1% by weight of Teflon resin powder was mixed as a binder for the negative electrode 6, and the mixture was shaped into pellets by a tablet molding machine and pressed onto a metal mesh. As the ionic conductor, one obtained by dissolving 0.5 mol / liter of LiPF ₆ in 10 vol% propylene carbonate-90 vol% tetrahydrofuran was used.
The positive electrode 3, the negative electrode 6 and the ionic conductor were incorporated into a coin cell and a charge / discharge test was conducted. The above work was performed in an Ar dry box. Table 3 shows the change in capacity during charge and discharge.

[0078]

[Table 3]

From Table 3, it was found that the battery of Example 10 had a large capacity and high charge / discharge efficiency.

[0080]

According to the present invention, the composition formula is Li _x Mn.
It is possible to provide a novel lithium-manganese composite oxide characterized by comprising O ₄ (x is 5 ≦ x ≦ 7). According to the production method of the present invention, metallic lithium, lithium oxide, lithium sulfide, lithium nitride, lithium fluoride, lithium chloride, lithium bromide, lithium iodide, lithium hydroxide, lithium nitrate, lithium carbonate, lithium formate, acetic acid. One or more lithium raw materials selected from the group consisting of lithium, lithium benzoate, lithium citrate, lithium lactate, lithium oxalate, lithium pyruvate, lithium stearate and lithium tartrate, and MnO and Mn ₂ O. ₃ , α-type MnO ₂ , β-type Mn
O ₂ , γ-type MnO ₂ , δ-type MnO ₂ , ε-type MnO ₂ , η
Type MnO _2, λ-type MnO _2, electrolytic MnO _2, ramsdellite _{MnO 2, MnOOOH, LiMnO 2,} Li
Mn ₂ O ₄ , Li ₂ MnO ₃ , and one or more manganese raw materials selected from the group consisting of metallic manganese,
Mix the lithium and manganese in a molar ratio of 5: 1 to 7: 1, and in an inert gas atmosphere or a hydrogen gas atmosphere,
By firing in a hydrogen-inert gas mixed atmosphere or an oxygen-inert gas mixed atmosphere, the composition formula Li _x MnO 2
_{Since the} lithium-manganese composite oxide composed of ₄ (x is 5 ≦ x ≦ 7) is formed, the lithium-manganese composite oxide can be easily manufactured.

The lithium manganese composite oxide of the present invention is
Since it has 7 to 5 Li for one Mn,
When used in the positive electrode active material and the non-aqueous secondary battery, even if one or more Li are desorbed, it is still 6 to 4 Li.
Remain, and the crystal structure can be sufficiently maintained. For example, from Li ₆ MnO ₄ to Li ₅ MnO ₄ Li
In the case of desorption, only about 16% of the existing Li has escaped, and the change in the lattice volume itself is LiCo.
It is extremely small compared to O _{2 and the} like.

Further, the lithium manganese composite oxidation of the present invention
The material takes the superstructure inverted fluorite type, and the Li site in the crystal structure is
They are connected in a substantially three-dimensional manner, and Li is included in the crystal structure.
Due to the ease of movement, the diffusion of Li is extremely fast, and with a large current
To obtain a positive electrode active material and a non-aqueous secondary battery that can be charged and discharged
be able to. Furthermore, the lithium manganese composite acid of the present invention
In the crystals, Mn is Mn in these crystals. ²⁺Exists in the state of
And Mn can exist up to 6+ oxidation states
For the purpose of inserting / desorbing more than 1 equivalent of Li from the unit structure,
Reaction is possible and conventional LiCoO 2₂, LiNiO₂
And LiMn₂O_FourLarge capacity positive electrode active material
An aqueous secondary battery can be obtained.

Further, since the lithium manganese composite oxide of the present invention uses Mn as a raw material, the raw material price is lower than Co and Ni, and the positive electrode active material and the non-aqueous secondary oxide having high industrial value are high. The next battery can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram of a basic structure of Li ₆ MnO ₄ in the present invention.

FIG. 2 is an X-ray diffraction pattern of Li ₆ MnO ₄ in the present invention.

FIG. 3 shows Li ₅ MnO ₄ (A of Example 1 of the present invention.
It is an X-ray diffraction pattern of a1).

FIG. 4 shows Li ₆ MnO ₄ (A in Example 2 of the present invention.
It is an X-ray diffraction pattern of b2).

FIG. 5: Li ₇ MnO ₄ (A of Example 3 of the present invention
It is an X-ray diffraction pattern of c2).

FIG. 6 Li ₅ MnO ₄ (A of Example 4 of the present invention
d1), Li ₆ MnO ₄ (Ad2), Li ₇ MnO
_{4 is} an X-ray diffraction pattern of ₄ (Ad3).

FIG. 7 shows Ba1, Ba2, and B of Comparative Example 1 in the present invention.
It is an X-ray diffraction pattern of a3.

FIG. 8 is a comparative example 2 of the present invention Bb1, Bb2, B
It is an X-ray diffraction pattern of b3.

9 is a comparative example 3 of the present invention Bc1, Bc2, B
It is an X-ray diffraction pattern of c3.

FIG. 10 is an X-ray diffraction pattern of Bd1 and Bd2 of Comparative Example 4 of the present invention.

FIG. 11 is a schematic view of a triode battery of Example 8 of the present invention.

FIG. 12 is a diagram showing changes in potential during charge / discharge of Aa2 in Example 8 of the present invention.

FIG. 13 is a schematic view of a coin battery of Example 8 of the present invention.

[Explanation of symbols]

1 Positive electrode can 2 Positive electrode current collector 3 Positive electrode 4 Negative electrode can 5 Negative electrode current collector 6 Negative electrode 7 Separator 8 Packing 10 Ion conductor 11 Negative electrode 11a Lead 12 Counter electrode 13 Positive electrode 14 Tube 14a Opening 15 Glass cell 16 Lid A Lithium B MnO ₄ tetrahedron

Claims (18)

[Claims] 1. The composition formula is Li _x MnO ₄ (x is 5 ≦ x
<7) A lithium-manganese composite oxide, characterized in that 2. The lithium manganese composite oxide according to claim 1, wherein Li _x MnO ₄ has an inverted fluorite type superstructure in which a part of Li is deficient. 3. Li _x MnO ₄ has a space group P42 / nm.
The lithium manganese composite oxide according to claim 1, which has a structure belonging to c. 4. Li _x MnO ₄ has an X-ray diffraction pattern using CuKα rays of at least 2θ = 18.5.
.About.19.0, 23.0 to 23.5, 26.5 to 27.
0, 32.8 to 33.3, 35.5 to 36.0, 42.
8-43.4, 45.0-45.5, 55.3-55.
The lithium manganese composite oxide according to any one of claims 1 to 3, which has a peak in the range of 8, respectively. 5. Li _x MnO ₄ has an X-ray diffraction pattern using CuKα rays of at least 2θ = 18.5.
.About.19.0, 23.0 to 23.5, 26.5 to 27.
0, 32.8 to 33.3, 35.5 to 36.0, 42.
8-43.4, 45.0-45.5, 55.3-55.
8 has respective peaks in the range of 8 and 2θ = 23.0 to 2
When the intensity of the peak existing at 3.5 is defined as 100, the intensity in the above range is 30 to 100, 100,
15-25, 45-75, 45-75, 18-50, 2
The lithium manganese composite oxide according to any one of claims 1 to 4, which is defined by 0 to 30 and 25 to 50. 6. The lithium manganese composite oxide according to claim 1, wherein Li _x MnO ₄ is Li ₆ MnO ₄ . 7. Metal lithium, lithium oxide, lithium sulfide
Um, lithium nitride, lithium fluoride, lithium chloride,
Lithium bromide, lithium iodide, lithium hydroxide, nitric acid
Lithium, lithium carbonate, lithium formate, lithium acetate
, Lithium benzoate, Lithium citrate, Lithium lactate
, Lithium oxalate, lithium pyruvate, steari
Selected from the group consisting of lithium phosphate and lithium tartrate
One or more lithium raw materials, MnO, and Mn
₂O_Three, Α type MnO₂, Β-type MnO₂, Γ-type MnO₂,
δ type MnO₂, Ε-type MnO₂, Η type MnO₂, Λ type Mn
O ₂, Electrolytic type MnO₂, Ramsdellite type MnO₂, M
nOOOH, LiMnO₂, LiMn₂O_Four, Li₂M
nO_Three, A metal selected from the group consisting of manganese and
Is a mixture of two or more manganese raw materials
Mix in a molar ratio of 5: 1 to 7: 1 and mix with an inert gas.
Hydrogen atmosphere, hydrogen-inert gas mixture
Baking in an atmosphere or an oxygen-inert gas mixed atmosphere
Therefore, the composition formula Li_xMnO_Four(X is 5 ≦ x ≦ 7)
Forming a lithium manganese composite oxide consisting of
A method for producing a lithium-manganese composite oxide, which is characterized. 8. The manganese raw material is MnO.
The manufacturing method as described. 9. The method according to claim 7, wherein the manganese raw material is metallic manganese, and the lithium raw material is Li ₂ O or Li ₂ O ₂ . 10. The inert gas selected from the group consisting of nitrogen, helium, neon, argon and krypton.
The method according to any one of claims 7 to 9, wherein the gas is one kind or two or more kinds of gas. 11. The inert gas selected from the group consisting of nitrogen, helium, neon, argon and krypton.
It is composed of two or more kinds of gases and has a volume fraction of oxygen of 0.
It is 01 to 1%, The manufacturing method as described in any one of Claims 7-9. 12. The inert gas selected from the group consisting of nitrogen, helium, neon, argon and krypton.
One or two or more kinds of gases, and the volume fraction of hydrogen is 0.
It is 1-100%, The manufacturing method as described in any one of Claims 7-9. 13. The method according to claim 12, wherein the volume fraction of hydrogen is 0.5 to 3%. 14. The manufacturing method according to claim 7, wherein the firing is performed at a temperature in the range of 300 to 2000 ° C. 15. The manufacturing method according to claim 14, wherein the firing is performed at a temperature in the range of 600 to 950 ° C. 16. A positive electrode active material comprising the lithium manganese composite oxide according to claim 1. 17. A positive electrode containing the lithium manganese composite oxide according to claim 1 as a positive electrode active material, and a negative electrode made of a lithium metal or a carbon material capable of inserting and extracting lithium.
A non-aqueous secondary battery comprising an ionic conductor. 18. The non-aqueous secondary battery according to claim 17, wherein the ionic conductor is a non-aqueous electrolyte.