JP7143864B2 - Lithium composite oxide, power storage device, and method for producing lithium composite oxide - Google Patents

Description

This specification discloses a lithium composite oxide, an electric storage device, and a method for producing the lithium composite oxide.

Conventionally, as a positive electrode active material used in a lithium secondary battery, for example, a positive electrode active lithium-excess metal oxide having a composition Li _x My O ₂ (0.6≦ _y ≦0.85 and 0≦x+y≦2) has been used. has been proposed (see, for example, Patent Document 1). This oxide is said to be insensitive to cation disorder and to have high reversible capacity when used in lithium secondary batteries. Moreover, as a positive electrode active material used in lithium secondary batteries, for example, a lithium molybdenum composite oxide having a rock salt structure has been proposed (see, for example, Patent Document 2). It is said that this composite oxide has a good discharge capacity and a good discharge capacity maintenance rate because it has a rock salt structure, which is a metastable phase.

JP 2018-92958 A JP 2017-202954 A

In Patent Document 1 mentioned above, Li _1.233 Mo _0.467 Cr _0.3 O ₂ exhibits a discharge capacity exceeding 280 mAh/g. There was a problem that it is a large element and has a large practical limitation. Further, in Patent Document 2, a composite oxide positive electrode material containing lithium and molybdenum in the composition is produced by a mechanochemical method and exhibits a high discharge capacity exceeding 300 mAh / g. The discharge is performed under a low voltage condition of 0.0 V, and the actual discharge amount that can be practically used as a full cell is expected to be about 150 mAh/g. As described above, the above-mentioned literature states that the discharge capacity and the like are good, but it is still not sufficient, and further improvement has been desired. That is, a novel composite oxide that can further increase the discharge capacity has been desired.

The present disclosure has been made in view of such problems, and the main purpose thereof is to provide a novel lithium composite oxide, an electric storage device, and a method for producing a lithium composite oxide that can increase the discharge capacity.

As a result of intensive research to achieve the above-mentioned object, the present inventors have found that the lithium composite oxide having a random rock salt structure and containing fluorine can further increase the discharge capacity. We have completed the invention disclosed in this specification.

That is, the lithium composite oxide disclosed in the present specification is
A lithium composite oxide used as an electrode active material for an electricity storage device,
It contains lithium, metal elements and fluorine, and its XRD spectrum shows a peak pattern of random rock salt structure.

The electricity storage device disclosed herein is
a positive electrode having the lithium composite oxide described above as a positive electrode active material;
a negative electrode having a negative electrode active material;
an ion conducting medium interposed between the positive electrode and the negative electrode and conducting lithium ions;
is provided.

The method for producing a lithium composite oxide disclosed herein comprises
A method for producing a lithium composite oxide used as an electrode active material for an electricity storage device, comprising:
By mixing and pulverizing an orthorhombic lithium composite oxide and lithium fluoride, a fluorine-containing lithium composite oxide containing lithium, a metal element, and fluorine and having an XRD spectrum showing a peak pattern of a random rock salt structure is obtained. process,
includes.

INDUSTRIAL APPLICABILITY The present disclosure can provide a novel lithium composite oxide, an electric storage device, and a method for producing a lithium composite oxide that can increase the discharge capacity. The reason why such an effect is obtained is presumed as follows. For example, in a random rocksalt positive electrode material containing fluorine in its composition, Li can migrate three-dimensionally, unlike the layered positive electrode that has been practically used so far, and the electrons of the metal oxide cluster are transferred by the adjacency of F. It is presumed that the attraction improves the redox property and allows more Li ⁺ to be intercalated and deintercalated. It is speculated that such a capacity improvement effect is obtained when F is dissolved in the positive electrode material.

FIG. 2 is a schematic diagram showing an example of a configuration of an electricity storage device 20; XRD measurement results of the fluorine-containing lithium-manganese composite oxide of Experimental Example 1. FIG. 2 is a relational diagram between the F content and the lattice spacing d in Experimental Examples 1 to 11; STEM/EDX images of lithium composite oxides of Experimental Examples 1 and 9. FIG. 4 shows initial discharge curves of cells using the lithium composite oxides of Experimental Examples 1 and 8 as electrodes. FIG. 2 is a relational diagram between the F content in Experimental Examples 1 to 11 and the discharge capacity of a cell used as an electrode.

(lithium composite oxide)
The lithium composite oxide of the present disclosure is used as an electrode active material for electrical storage devices. This lithium composite oxide contains lithium, a metal element, and fluorine, and its XRD spectrum shows a peak pattern of a random rock salt structure. The metal element M is, for example, one or more of Al, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga and Ge, and among these, Mn is more preferable. The random rock salt structure has four 2θ ranges in the XRD spectrum: 35 ° to 49 °, 42 ° to 48 °, 62 ° to 68 °, and 80 ° to 84 ° shows a peak pattern with diffraction peaks. In addition, since it has a random structure, the diffraction peak is relatively broad, the half width of the main peak at 2θ = 42 ° to 48 ° shows 1.5 ° or more, and the peak at 2θ = 62 ° to 68 ° shows a half width of 2° or more.

This lithium composite oxide may be represented by the general formula Li _1+x MO ₂ F _x . However, M is one or more of Al, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga and Ge, and 0≤x≤1. The F content x preferably satisfies 0.2≦x≦0.8, more preferably 0.4≦x≦0.6. A range of 0.2≦x≦0.8 is preferable because it more reliably exhibits a higher capacity. Moreover, this lithium composite oxide is preferably a fluorine-containing lithium composite oxide in which the metal element M is Mn. This fluorine-containing lithium composite oxide may be represented by the general formula Li _1+x MnO ₂ F _x .

In this lithium composite oxide, the lattice spacing d estimated from the diffraction peak present in the range of 42° or more and 48° or less in the XRD spectrum is 2.048 Å or more and 2.078 Å or less. good. Moreover, in this lithium composite oxide, it is more preferable that the lattice spacing d is in the range of 2.065 Å or less. This range is preferable because the capacity of the electricity storage device can be further increased. Furthermore, in the lithium composite oxide, the F content x represented by the general formula Li _1+x MO ₂ F _x satisfies 0.2≦x≦0.8, and the lattice spacing d is 2.065 Å or less. is more preferably in the range of Satisfying such a range is preferable because the capacity of the electricity storage device can be increased more reliably.

In this lithium composite oxide, it is preferable that Mn and F are uniformly distributed in the elemental distribution measured by STEM/EDX. A uniform distribution of F is preferable because carrier ions (for example, lithium ions) of the electric storage device are evenly absorbed and released in the composite oxide. The distribution of F shows a tendency to depend on the content x of F, although it depends on the mixing state of the raw materials. F can be more uniformly present.

This lithium composite oxide preferably has an initial capacity of 200 mAh/g or more when used as an electrode active material for an electricity storage device. More preferably, the initial capacity is greater, for example, 215 mAh/g or more, more preferably 230 mAh/g or more, even more preferably 270 mAh/g or more, and most preferably 300 mAh/g or more. This initial capacity can be adjusted depending on the content x of F, the randomness of the rock salt structure, and the like.

(Method for producing lithium composite oxide)
The production method of the present disclosure is a method for producing the above-described lithium composite oxide used as an electrode active material of an electricity storage device. This manufacturing method may include, for example, an adjustment step of adjusting the structure of the composite oxide. Also, this adjustment step may include a raw material preparation process and a mixed pulverization process. In this production method, an orthorhombic lithium composite oxide and lithium fluoride are mixed and pulverized to obtain a fluorine-containing lithium composite that contains lithium, a metal element, and fluorine, and whose XRD spectrum exhibits a peak pattern of a random rocksalt structure. An oxide may be obtained. In this production method, the ranges described for the above lithium composite oxide, such as the content x of F and the compounding ratio of the raw materials, can be appropriately adopted.

In the raw material production process, an orthorhombic lithium composite oxide is produced while adjusting the firing conditions. In this treatment, LiMnO ₂ may be produced as the raw material lithium composite oxide. In this treatment, the raw material Li ₂ MnO ₃ is obtained by firing at a temperature of 800° C. to 1100° C. for 6 hours to 15 hours. LiMnO ₂ is prepared by mixing Li ₂ MnO ₃ and MnO in equimolar amounts and firing in an inert atmosphere (for example, in Ar) at a temperature of 900° C. or higher and 1100° C. or lower for 6 hours or more and 24 hours or less. Obtainable.

In the mixed pulverization treatment, the lithium composite oxide prepared above and LiF are blended at a predetermined ratio, and mixed and pulverized while adjusting the pulverization conditions. In this treatment, the general formula Li _1+x MO ₂ F _x (where M is one or more of Al, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga and Ge) Yes, and the raw materials are blended so as to satisfy 0≦x≦1. In the mixed pulverization treatment, the mixed pulverization may be performed for 2 hours or more and 40 hours or less. Mixing pulverization can be performed by, for example, a ball mill or a planetary ball mill, and is preferably performed by a planetary ball mill. In the planetary ball mill, the number of revolutions may be appropriately set according to the volume of the raw material. A range is more preferred. By performing such an adjustment step, the lithium composite oxide described above can be produced.

(storage device)
The power storage device of the present disclosure includes a positive electrode having a positive electrode active material, a negative electrode having a negative electrode active material, and an ion conducting medium interposed between the positive electrode and the negative electrode and conducting lithium ions. This electricity storage device has the lithium composite oxide described above as a positive electrode active material. In addition, the electric storage device includes a lithium secondary battery using metal lithium or a lithium alloy as a negative electrode active material, a lithium ion secondary battery having a negative electrode active material that absorbs and releases lithium ions, and a negative electrode that adsorbs and desorbs ions. A hybrid capacitor having an active material may also be used.

The positive electrode is prepared by mixing a positive electrode active material, a conductive material, and a binder, adding an appropriate solvent to make a paste-like positive electrode mixture, applying and drying it on the surface of a current collector, and optionally It may be formed by compression to increase its density. The conductive material contained in the positive electrode is not particularly limited as long as it is an electronically conductive material that does not adversely affect the battery performance of the positive electrode. , carbon black, ketjen black, carbon whisker, needle coke, carbon fiber, metals (copper, nickel, aluminum, silver, gold, etc.), or a mixture of two or more thereof can be used. Among these, carbon black and acetylene black are preferable as the conductive material from the viewpoint of electronic conductivity and coatability. The binder contained in the positive electrode plays a role of binding the active material particles and the conductive material particles. Alternatively, thermoplastic resins such as polypropylene and polyethylene, ethylene propylene diene monomer (EPDM) rubber, sulfonated EPDM rubber, natural butyl rubber (NBR) and the like can be used singly or as a mixture of two or more. Cellulose-based or styrene-butadiene rubber (SBR) aqueous dispersions, which are water-based binders, can also be used. Examples of solvents for dispersing the positive electrode active material, conductive material, and binder include N-methylpyrrolidone, dimethylformamide, dimethylacetamide, methylethylketone, cyclohexanone, methyl acetate, methyl acrylate, diethylenetriamine, and N,N-dimethylaminopropylamine. , ethylene oxide, and tetrahydrofuran can be used. Alternatively, a dispersant, a thickener, or the like may be added to water, and the active material may be slurried with a latex such as SBR. As the thickening agent, for example, polysaccharides such as carboxymethyl cellulose and methyl cellulose can be used singly or as a mixture of two or more. Application methods include, for example, roller coating such as applicator roll, screen coating, doctor blade method, spin coating, and bar coater, and any thickness and shape can be obtained using any of these methods. Current collectors include aluminum, titanium, stainless steel, nickel, iron, calcined carbon, conductive polymer, and conductive glass. The surface of which is treated with carbon, nickel, titanium, silver, or the like can be used. For these, it is also possible to oxidize the surface. Examples of the shape of the current collector include foil, film, sheet, net, punched or expanded, lath, porous, foam, and fiber group formations. The current collector used has a thickness of, for example, 1 to 500 μm.

The negative electrode may be formed by adhering the negative electrode active material and the current collector. A negative electrode material having a shape may be coated on the surface of a current collector, dried, and optionally compressed to increase the electrode density. Examples of negative electrode active materials include inorganic compounds such as lithium, lithium alloys and tin compounds, carbonaceous materials capable of intercalating and deintercalating lithium ions, composite oxides containing multiple elements, and conductive polymers. Examples of carbonaceous materials include cokes, vitreous carbons, graphites, non-graphitizable carbons, pyrolytic carbons, and carbon fibers. Among them, graphites such as artificial graphite and natural graphite have an operating potential close to that of metallic lithium, can be charged and discharged at a high operating voltage, and suppress self-discharge when lithium salt is used as a supporting salt. Moreover, the irreversible capacity during charging can be reduced, which is preferable. Examples of composite oxides include lithium-titanium composite oxides and lithium-vanadium composite oxides. Among them, carbonaceous materials are preferable as the negative electrode active material from the viewpoint of safety. As the conductive material, binder, solvent, and the like used for the negative electrode, those exemplified for the positive electrode can be used. The current collector of the negative electrode includes copper, nickel, stainless steel, titanium, aluminum, calcined carbon, conductive polymer, conductive glass, Al-Cd alloy, etc. For that purpose, for example, copper or the like whose surface is treated with carbon, nickel, titanium, silver, or the like can also be used. For these, it is also possible to oxidize the surface. A current collector having the same shape as that of the positive electrode can be used.

The ion-conducting medium may be a non-aqueous electrolytic solution containing a lithium-containing supporting salt and a non-aqueous solvent. Examples of the solvent for the non-aqueous electrolytic solution include carbonates, esters, ethers, nitriles, furans, sulfolanes, dioxolanes, and the like, and these can be used singly or in combination. Specifically, the carbonates include cyclic carbonates such as ethylene carbonate, propylene carbonate, vinylene carbonate, butylene carbonate, and chloroethylene carbonate, dimethyl carbonate, ethylmethyl carbonate, diethyl carbonate, ethyl-n-butyl carbonate, methyl-t -chain carbonates such as butyl carbonate, di-i-propyl carbonate and t-butyl-i-propyl carbonate, cyclic esters such as γ-butyl lactone and γ-valerolactone, methyl formate, methyl acetate, ethyl acetate, Chain esters such as methyl butyrate; ethers such as dimethoxyethane, ethoxymethoxyethane, and diethoxyethane; nitriles such as acetonitrile and benzonitrile; furans such as tetrahydrofuran and methyltetrahydrofuran; Dioxolanes such as sulfolanes, 1,3-dioxolane, methyldioxolane, and the like are included. Among these, a combination of cyclic carbonates and chain carbonates is preferred.

The supporting salt is, for example, _LiPF6 , _LiBF4 , _LiAsF6 , _LiCF3SO3 , LiN( _CF3SO2 ) ₂ , _{LiC ( CF3SO2} ) ₃ , _LiSbF6 , _LiSiF6 , _LiAlF4 , _LiSCN , LiClO ₄ , LiCl, LiF, LiBr, LiI, _LiAlCl4 and the like. Among them, from the group consisting of inorganic salts such as _LiPF6 , _LiBF4 , _LiAsF6 and LiClO4, and organic salts such as _{LiCF3SO3 ,} LiN _{( CF3SO2} ) ₂ and _{LiC ( CF3SO2} ) ₃ From the viewpoint of electrical properties, it is preferable to use one selected salt or a combination of two or more selected salts. The concentration of the supporting salt in the non-aqueous electrolytic solution is preferably 0.1 mol/L or more and 5 mol/L or less, more preferably 0.5 mol/L or more and 2 mol/L or less. When the supporting electrolyte is dissolved in a concentration of 0.1 mol/L or more, a sufficient current density can be obtained, and when it is 5 mol/L or less, the electrolytic solution can be made more stable.

The power storage device of the present disclosure may include a separator between the negative electrode and the positive electrode. The separator is not particularly limited as long as it has a composition that can withstand the range of use of the electricity storage device. is mentioned. These may be used alone, or may be used in combination.

The shape of the electricity storage device of the present disclosure is not particularly limited, and examples thereof include coin-shaped, button-shaped, sheet-shaped, laminated, cylindrical, flat, and rectangular shapes. Also, a plurality of such power storage devices may be connected in series and applied to a large-sized device such as an electric vehicle. FIG. 1 is a schematic diagram showing an example of an electricity storage device 20 of this embodiment. This power storage device 20 includes a positive electrode sheet 23 having a positive electrode mixture 22 formed on a current collector 21 , a negative electrode sheet 26 having a negative electrode mixture 25 formed on the surface of a current collector 24 , a positive electrode sheet 23 and a negative electrode sheet 26 . and a non-aqueous electrolytic solution 29 filling between the positive electrode sheet 23 and the negative electrode sheet 26 . In this electricity storage device 20, a separator 28 is sandwiched between a positive electrode sheet 23 and a negative electrode sheet 26, which are wound and inserted into a cylindrical case 32, and connected to a positive electrode terminal 34 connected to the positive electrode sheet 23 and a negative electrode sheet 26. and a negative electrode terminal 36 are provided. The positive electrode mixture 22 contains, as a positive electrode active material, a composite oxide containing lithium, a metal element, and fluorine and exhibiting a peak pattern of a random rocksalt structure in the XRD spectrum.

The lithium composite oxide, the method for producing the same, and the electric storage device according to the present embodiment, which have been described in detail above, can provide a novel device capable of increasing the discharge capacity. The reason why such an effect is obtained is presumed as follows. For example, in a random rocksalt positive electrode material containing fluorine in its composition, Li can migrate three-dimensionally, unlike the layered positive electrode that has been practically used so far, and the electrons of the metal oxide cluster are transferred by the adjacency of F. It is presumed that the attraction improves the redox property and allows more Li ⁺ to be intercalated and deintercalated. It is speculated that such a capacity improvement effect is obtained when F is dissolved in the positive electrode material.

It goes without saying that the present disclosure is not limited to the above-described embodiments, and can be implemented in various forms as long as they fall within the technical scope of the present disclosure.

Hereinafter, examples of specifically producing the lithium composite oxide and the electricity storage device of the present disclosure will be described as experimental examples. Experimental Examples 1 to 7 correspond to Examples, and Experimental Examples 8 to 11 correspond to Reference Examples.

(Preparation of synthetic raw materials)
After orthorhombic LiMnO ₂ and LiF were mixed in an agate bowl, the mixture was sealed in a zirconia pot under an Ar atmosphere and pulverized in a planetary ball mill to obtain a fluorine-containing lithium-manganese composite oxide. . Synthesis conditions were two synthesis conditions A and B with different ball mill pots, types of balls, and different processing times. The synthesis conditions are shown below.
(Synthesis condition A)
Pot: 500 mL zirconia pot Ball: 5 mm diameter zirconia ball Number of revolutions: 560 rpm
Processing time: 28h
(Synthesis condition B)
Pot: 80 mL zirconia pot Ball: 10 mm diameter zirconia ball Number of revolutions: 600 rpm
Processing time: 5h

(Experimental Examples 1 to 4)
Fluorine-containing lithium-manganese composite oxide produced under synthesis conditions A by blending raw materials such that x in general formula Li _1+x MnO ₂ F _x is 0.5, 0.8, 1.0, or 0.2 were designated as Experimental Examples 1 to 4, respectively.

(Experimental Examples 5 to 7, 9, 10)
Fluorine-containing lithium produced under synthesis conditions B by blending raw materials such that x in the general formula Li _1+x MnO ₂ F _x is 0.5, 0.8, 0.2, 1.2, and 1.0 Manganese composite oxides were designated as Experimental Examples 5 to 7, 9, and 10, respectively.

(Experimental Examples 8 and 11)
A lithium-manganese composite oxide prepared under Synthesis Condition A by blending raw materials so as to satisfy the general formula LiMnO ₂ (x=0) was designated as Experimental Example 8. A lithium-manganese composite oxide prepared under Synthesis Condition B was designated as Experimental Example 11 by blending raw materials so as to satisfy the general formula LiMnO ₂ (x=0).

(STEM/EDX measurement)
Scanning transmission electron microscope (STEM) observation/energy dispersive X-ray (EDX) measurement of the obtained lithium-manganese composite oxide was performed. A measurement sample was prepared by dispersing the active material in methanol and dropping it onto a Cu microgrid. The measurement was performed using STEM (JEM-2100F manufactured by JEOL Ltd.) and EDX (manufactured by Thermo Co.) at an acceleration voltage of 200 kV.

(X-ray diffraction measurement)
A powder X-ray diffraction measurement was performed on the sample. The measurement was carried out using an X-ray diffractometer (Ultima IV manufactured by Rigaku Co., Ltd.) using CuKα rays (wavelength: 1.54051 Å) as radiation. Measurement was performed by setting the applied voltage to 50 kV and the current to 40 mA. Further, the measurements were recorded at a scanning speed of 5°/min in the angle range of 2θ from 10° to 100°. Further, the lattice spacing d (Å) was estimated from the diffraction peak present in the range of 2θ from 42° to 48° (near 45°) by calculation according to Bragg's condition.

(Preparation of bipolar evaluation cell)
The obtained sample was used as a positive electrode active material, the active material was 70% by mass as a mixture ratio, Ketjenblack (ECP-600 manufactured by Mitsubishi Chemical) was 25% by mass as a conductive material, and polytetrafluoroethylene (PTFE) was used as a binder. , F-104 manufactured by Daikin Industries, Ltd.) was weighed at 5% by mass, pulverized with a mixer, and mixed. The resulting dry compound material was formed into a circular pellet with a diameter of 10 mm, placed on an Al expanded metal and pressed to obtain a positive electrode. A bipolar evaluation cell was prepared by using a lithium metal foil (thickness of 300 μm) as a negative electrode and sandwiching a polyethylene separator (E20MMS manufactured by Tonen Chemical Co., Ltd.) impregnated with a non-aqueous electrolytic solution between both electrodes. For the non-aqueous electrolyte, _LiPF6 was dissolved at a concentration of 1 M in a mixed solvent of ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) at a volume ratio of 30/40/30. I used something else.

(Charging and discharging test)
Using the above bipolar evaluation cell, constant-current and constant-voltage charging/discharging measurements were performed at a current value of 20 mA/g in a temperature environment of 20° C. in a potential range of 5.0 V to 2.0 V based on the lithium reference potential.

(Results and discussion)
Table 1 summarizes the evaluation results of Experimental Examples 1 to 11. Table 1 summarizes the F content x, the synthesis conditions, the presence or absence of bias in the elemental distribution of Mn and F, the lattice spacing d (Å), and the discharge capacity of Experimental Examples 1 to 11. 2 is the result of X-ray diffraction measurement of the fluorine-containing lithium-manganese composite oxide of Experimental Example 1. FIG. FIG. 3 is a diagram showing the relationship between the F content and the lattice spacing d in Experimental Examples 1-11. FIG. 4 shows STEM/EDX images of the lithium composite oxides of Experimental Example 1 (FIG. 4A) and Experimental Example 9 (FIG. 4B). FIG. 5 shows initial discharge curves of cells using the lithium composite oxides of Experimental Examples 1 and 8 as electrodes. FIG. 6 is a diagram showing the relationship between the F content in Experimental Examples 1 to 11 and the discharge capacity of the cell used as the electrode.

As shown in FIG. 2, in Experimental Example 1, the crystal structure was found to be a random rock salt structure. It was also found that the crystal structures of Experimental Examples 2 to 11 were also random rock salt structures. Moreover, as shown in FIG. 3 and Table 2, the lattice spacing d depends on the F content, and showed a tendency that the lattice spacing d decreases as the F content increases. Under synthesis condition A, the lattice spacing d of the fluorine-containing lithium-manganese composite oxide was in the range of 2.065 Å or less. Further, under synthesis condition B, the fluorine-containing lithium-manganese composite oxide had a lattice spacing d of 2.080 Å or less.

As shown in FIG. 4A, in Experimental Example 1, Mn and F were not biased in distribution, and F was uniformly dispersed. Also, in Experimental Examples 2 to 7, there was no bias in distribution. On the other hand, as shown in FIG. 4B, in Experimental Example 9, it was found that Mn and F have a biased distribution, and that there is a region where F is segregated. Furthermore, even in Experimental Example 10, the distributions of Mn and F were slightly biased. That is, from the viewpoint of uniform distribution of F, it was found that the content x of F in the general formula Li _1+x MnO ₂ F _x is preferably 1.0 or less, more preferably 0.8 or less. .

As shown in FIG. 5 and Table 1, it was found that Experimental Example 1 had a larger capacity than Experimental Example 8. It was found that Experimental Examples 1 to 7 exhibited capacities of 200 mAh/g or more, and further 215 mAh/g or more, showing larger capacities than Experimental Examples 8 and 11 containing no F. Moreover, in Experimental Examples 9 and 10, in which the F content was high, segregation of F occurred, and it was found that the capacity decreased. Further, as shown in FIG. 6, in the general formula Li _1+x MnO ₂ F _x , the F content x is preferably in the range of 0.2 ≤ x ≤ 1.0 from the viewpoint of increasing the capacity, and 0.2 ≤ It was found that the range of x≤0.8 is more preferable, and the range of 0.4≤x≤0.6 is even more preferable.

It goes without saying that the present disclosure is by no means limited to the above-described embodiments, and can be embodied in various forms as long as they fall within the technical scope of the present disclosure.

INDUSTRIAL APPLICABILITY The lithium composite oxide, the electric storage device, and the method for producing the lithium composite oxide disclosed in the present specification can be used in the technical field of secondary batteries.

20 power storage device 21 current collector 22 positive electrode mixture 23 positive electrode sheet 24 current collector 25 negative electrode mixture 26 negative electrode sheet 28 separator 29 non-aqueous electrolytic solution 32 cylindrical case 34 positive electrode terminal 36 Negative terminal.

Claims (7)

A lithium composite oxide used as an electrode active material for an electricity storage device,
containing lithium, metal elements and fluorine, the XRD spectrum showing a peak pattern of random rock salt structure,
A lithium composite oxide represented by the general formula Li _1+x MO ₂ F _x (where M is Mn and satisfies 0.2≦x≦0.8) . 2. The lithium composite oxide according to claim 1 , wherein the lattice spacing d estimated from the diffraction peak present in the range of 42° or more and 48° or less of 2θ in the XRD spectrum is in the range of 2.048 Å or more and 2.078 Å or less. thing. 3. The lithium composite oxide according to claim 2 , wherein said lattice spacing d is in the range of 2.065 Å or less. The lithium composite oxide according to any one of claims 1 to 3 , wherein Mn and F are uniformly distributed in the elemental distribution measured by STEM/EDX. A positive electrode having the lithium composite oxide according to any one of claims 1 to 4 as a positive electrode active material;
a negative electrode having a negative electrode active material;
an ion conducting medium interposed between the positive electrode and the negative electrode and conducting lithium ions;
A storage device with The positive electrode has an initial discharge capacity of 200 mAh/g or more,
The electricity storage device according to claim 5 . A method for producing a lithium composite oxide used as an electrode active material for an electricity storage device, comprising:
By mixing and pulverizing an orthorhombic lithium composite oxide and lithium fluoride, a fluorine-containing lithium composite oxide containing lithium, a metal element, and fluorine and having an XRD spectrum showing a peak pattern of a random rock salt structure is obtained. a process , including
In the adjustment step, raw materials are mixed so as to satisfy the general formula Li _1+x MO ₂ F _x (where M is Mn and satisfies 0.2≦x≦0.8) to produce a lithium composite oxide. Method.

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