JP2012079598A - Nonaqueous electrolyte secondary battery and negative electrode active substance material for nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery that has high capacity and can suppress precipitation of lithium metal in charging, and to provide a negative electrode active material.SOLUTION: A nonaqueous electrolyte secondary battery of the present invention includes: a negative electrode 2 containing a negative electrode active material using a manganese oxide having a composition of MnO; a positive electrode 1; and a nonaqueous electrolyte 15 having lithium ion conductivity.

Description

  The present invention relates to a non-aqueous electrolyte secondary battery, and more particularly to a non-aqueous secondary battery using manganese oxide as a negative electrode active material and a negative electrode active material for a non-aqueous electrolyte secondary battery.

  With the development of various portable devices such as mobile phones and notebook personal computers, and transportation means such as hybrid cars and electric vehicles, development of high-performance secondary batteries is required.

Since secondary batteries currently in practical use can obtain a high energy density, they generally use an oxidation-reduction reaction of lithium ions. Specifically, as a positive electrode material, a layered compound represented by LiMO ₂ (M includes at least one of Co, Ni, Mn, and Fe) or LiM ₂ O ₄ having a spinel structure (M is a transition metal) ) And the like, and a carbon material such as graphite capable of occluding and releasing lithium is used as the negative electrode.

  In order to make a portable device smaller or to use it for a long time by one charge, it is required to increase the capacity of a lithium ion secondary battery. In addition, as the use of lithium ion secondary batteries for transportation, etc. expands, there is a demand for further improving safety.

However, graphite performs occlusion and release (insertion and desorption) of lithium at a potential of about 0.1 V with reference to the oxidation-reduction potential (Li / Li ⁺ ) of lithium. For this reason, when a lithium ion secondary battery using graphite as a negative electrode is charged at a low temperature or rapidly charged, metallic lithium may be deposited on the negative electrode surface due to a reaction overvoltage.

In order to prevent such lithium metal precipitation, titanium oxide having a spinel structure (Li _1.33 Ti _1.66 O ₄ , which can store and release lithium at a potential of about 1.5 V with respect to the oxidation-reduction potential of lithium is used. The use of LiTi ₂ O ₄ or the like) as a negative electrode active material has been studied (Patent Documents 1 and 2).

JP-A-6-275263 JP-A-7-85878

However, the amount of lithium occlusion per unit weight of the titanium oxide is smaller than that of graphite. For this reason, when titanium oxide is used as the negative electrode active material, the battery capacity of the lithium ion secondary battery is greatly reduced compared to the case where graphite is used as the negative electrode (the theoretical capacity is Li _1.33 Ti _1.66 O _4. 176 mAh / g for graphite and 372 mAh / g for graphite).

  Further, since the lithium occlusion / release potential at the negative electrode is increased, the deposition of metallic lithium due to a reaction overvoltage can be suppressed, but the battery voltage of the lithium ion secondary battery is decreased by the increase in the potential of the negative electrode.

  For this reason, when a titanium oxide was used for the negative electrode active material, there was a problem that the energy density of the entire lithium ion secondary battery would be significantly reduced.

  The present invention solves at least one of the problems of the prior art, and provides a non-aqueous electrolyte secondary battery and a negative electrode active material that have a high capacity and can suppress precipitation of lithium metal during charging. For the purpose.

The nonaqueous electrolyte secondary battery of the present invention includes a negative electrode including a negative electrode active material using a manganese oxide having a composition of Mn ₅ O ₈ , a positive electrode, and a nonaqueous electrolyte having lithium ion conductivity.

  In a preferred embodiment, the manganese oxide is obtained by heating γ-manganese oxyhydroxide under an inert atmosphere.

The nonaqueous electrolyte secondary battery according to the present invention includes a negative electrode using Mn ₅ O ₈ as a negative electrode active material, and the negative electrode occludes lithium at a potential of about 0.8 V based on the oxidation-reduction potential of lithium. For this reason, even if a reaction overvoltage occurs during low-temperature charging or rapid charging, metallic lithium is unlikely to deposit at the negative electrode. Moreover, the negative electrode using Mn ₅ O ₈ has a large amount of lithium occlusion per unit weight. Therefore, a high-capacity nonaqueous electrolyte secondary battery having high safety can be realized.

(A) is a perspective view which shows one Embodiment of the nonaqueous electrolyte secondary battery by this invention, (b) has shown the II cross section in (a). (C) has expanded and shown the cross-section of the electrode group of the nonaqueous electrolyte secondary battery shown in FIG. (A) is a figure which shows the powder X-ray diffraction pattern of (gamma) -manganese oxyhydroxide used in the Example, (b) is a figure which shows the powder X-ray diffraction pattern of (gamma) -manganese oxyhydroxide based on a database. . (A) is a diagram illustrating a powder X-ray diffraction pattern of Mn ₅ O ₈ synthesized in Example illustrates the (b) a powder X-ray diffraction pattern of Mn ₅ O ₈ by the database. It is a first time charge-and-discharge curve figure of the coin type battery of an example. It is a charging / discharging curve figure of the coin-type battery of an Example.

The inventor of the present application can occlude and release lithium at a potential higher than that of titanium oxide by 0.1 V or more with respect to the oxidation-reduction potential (Li / Li ⁺ ) of lithium. Possible negative electrode active material materials were investigated. As a result, the manganese oxide having the composition of Mn ₅ O ₈ meets these conditions, has a high capacity, and can suppress the precipitation of lithium metal during low-temperature charging or rapid charging. It was found that it is suitable for realizing a battery.

Manganese oxides such as LiMn ₂ O ₄ and Li ₂ MnO ₃ have been conventionally used as positive electrode active material materials. On the other hand, Mn ₅ O ₈ is a known substance, but its electrochemical characteristics are not known.

  Hereinafter, embodiments of a non-aqueous electrolyte secondary battery and a negative electrode active material for a non-aqueous electrolyte secondary battery according to the present invention will be described. Fig.1 (a) shows the perspective view of embodiment of the nonaqueous electrolyte secondary battery by this invention, (b) has shown the II cross section in (a). Moreover, FIG.1 (c) has expanded and shown the cross-section of the electrode group of a nonaqueous electrolyte secondary battery.

  As shown in FIGS. 1A and 1B, the lithium ion secondary battery of the present embodiment includes an electrode group 13, a battery case 14 that houses the electrode group 13, and a non-filled battery case 14. A water electrolyte 15. The positive electrode in the electrode group 13 is connected to the positive electrode lead 11, and the negative electrode in the electrode group is connected to the negative electrode lead 12. The positive electrode lead 11 and the negative electrode lead 12 are drawn out of the battery case 14.

  As shown in FIG. 1C, the electrode group 13 includes a positive electrode 1, a negative electrode 2, and a separator 3 provided between the positive electrode 2 and the negative electrode 2. The positive electrode 1 has a positive electrode current collector 1a and a positive electrode active material layer 1b provided on the surface of the positive electrode current collector 1a. On the other hand, the negative electrode 2 has a negative electrode current collector 2a and a negative electrode active material layer 2b provided on the surface of the negative electrode current collector 2a.

The positive electrode active material layer 1b includes a positive electrode active material that absorbs and releases lithium. Specifically, the positive electrode active material is composed of a transition metal oxide containing lithium. Examples of the transition metal oxide containing lithium include LiCoO ₂ , Li _x CoO ₂ , Li _x NiO ₂ , Li _x MnO ₂ , Li _x Co _y Ni _1-y O ₂ , and Li _x Co _y M _1-y O. _{z, Li x Ni 1-y} M y O z, Li x Mn 2 O 4, Li x Mn 2-y M y O 4 (M = Na, Mg, Sc, Y, Mn, Fe, Co, Ni, Cu , Zn, Al, Cr, Pb, Sb, B, x = 0 to 1.2, y = 0 to 0.9, z = 1.7 to 2.3).

Other than the above as the positive electrode active material, olivine type lithium phosphate represented by the general formula of LiMPO ₄ (M = V, Fe, Ni, Mn), Li ₂ MPO ₄ F (M = V, Fe, Ni, Mn) Lithium fluorophosphate represented by the general formula can also be used. Further, a part of these lithium-containing compounds may be substituted with a different element.

  A plurality of different materials may be mixed and used as the positive electrode active material. When the positive electrode active material is a powder, the average particle size of the powder is not particularly limited, but is preferably 0.1 μm or more and 30 μm or less. The positive electrode active material layer 1b usually has a thickness of about 50 μm to 200 μm, but the thickness is not particularly limited, and the positive electrode active material layer 1b may have a thickness of 0.1 μm to 50 μm.

  The positive electrode active material layer 1b may include both a conductive agent and a binder in addition to the positive electrode active material, or may include only one of them. Alternatively, the positive electrode active material layer 1b does not contain either a conductive agent or a conductive agent, and may be composed of only the active material.

  The conductive agent used for the positive electrode active material layer 1 b may be any electron conductive material that does not cause a chemical change at the charge / discharge potential of the positive electrode 1. For example, conductive fibers such as graphites, carbon blacks, carbon fibers, and metal fibers, metal powders, conductive whiskers, conductive metal oxides, or organic conductive materials may be used alone. And may be used as a mixture. The addition amount of the conductive agent is not particularly limited, but is preferably 1 to 50% by weight, and particularly preferably 1 to 30% by weight with respect to the positive electrode material.

  The binder used for the positive electrode active material layer 1b may be either a thermoplastic resin or a thermosetting resin. Preferred binders include, for example, polyolefin resins such as polyethylene and polypropylene, fluororesins such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), hexafluoropropylene (HFP), and the like. Copolymer resin, polyacrylic acid or copolymer resin thereof.

  In addition to the conductive agent and the binder, fillers, dispersants, ionic conductors, pressure enhancers, and other various additives can be used. The filler may be any fibrous material that does not cause a chemical change in the lithium ion secondary battery.

  The material of the positive electrode current collector 1a may be any electronic conductor as long as it does not cause a chemical change at the charge / discharge potential of the positive electrode 1. For example, aluminum, stainless steel, titanium, carbon, conductive resin, or the like can be used. Further, it is desirable that the surface of the positive electrode current collector 1a be uneven by surface treatment. The shape may be any of film, sheet, net, punched material, lath body, porous body, foamed body, fiber group, nonwoven fabric shaped body, and the like in addition to the foil. The thickness is not particularly limited, but is generally 1 μm or more and 500 μm or less.

The negative electrode active material layer 2b includes a negative electrode active material using a manganese oxide having a composition of Mn ₅ O ₈ . Mn ₅ O ₈ is a monoclinic crystal having a layered structure and has a composition different from that of a lithium-containing manganese oxide used as a positive electrode active material of a nonaqueous electrolyte secondary battery.

As a result of detailed studies by the inventors of the present application, Mn ₅ O ₈ shows a battery capacity of about 300 mAh / g when used as a negative electrode, and in the state where lithium is released, the oxidation-reduction potential (Li / Li ⁺ ) of lithium. Is stored at a potential of about 0.8V. For this reason, according to the nonaqueous electrolyte secondary battery of the present embodiment, the capacity is high, and precipitation of lithium metal during low-temperature charging or rapid charging can be suppressed.

Mn ₅ O ₈ has a powder shape. Similar to the positive electrode active material, the average particle diameter of Mn ₅ O ₈ is not particularly limited, but is preferably 0.1 μm or more and 30 μm or less. The negative electrode active material layer 2b also usually has a thickness of about 50 μm to 200 μm, but the thickness is not particularly limited, and the negative electrode active material layer 2b may have a thickness of 0.1 μm to 50 μm.

  The negative electrode active material layer 2b may also contain both a conductive agent and a binder in addition to the negative electrode active material, or may contain only one of them. Alternatively, the positive electrode active material layer 1b does not contain either a conductive agent or a conductive agent, and may be composed of only the active material. A material used for the positive electrode active material layer 1b can be used for the conductive agent and the binder.

  In addition to the conductive agent and the binder, fillers, dispersants, ionic conductors, and other various additives can be used. The filler may be any fibrous material that does not cause a chemical change in the lithium ion secondary battery.

  The material of the negative electrode current collector 2a may be any electronic conductor that does not cause a chemical change at the charge / discharge potential of the negative electrode 2. For example, copper foil, nickel foil, stainless steel foil, etc. can be used.

  As the separator 3, a porous insulator that is chemically stable inside the battery is used. Specifically, a microporous film or nonwoven fabric of polyolefin resin such as polyethylene resin or polypropylene resin can be used. The microporous membrane or the nonwoven fabric may be a single layer or may have a multilayer structure. Preferably, it has a two-layer structure composed of a polyethylene resin layer and a polypropylene resin layer, or a three-layer structure composed of two polypropylene resin layers and a polyethylene resin layer disposed therebetween. The separator which has is used. These separators preferably have a shutdown function. Moreover, it is preferable that the thickness of the separator 3 is 10 micrometers or more and 30 micrometers or less, for example.

  The non-aqueous electrolyte includes a non-aqueous solvent and an electrolyte. The non-aqueous solvent contains, for example, at least one of a cyclic carbonate and a chain carbonate as a main component, and preferably contains both. The cyclic carbonate is preferably at least one selected from ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate (BC). The chain carbonate is preferably at least one selected from dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and the like.

The electrolyte includes a supporting electrolyte containing lithium ions. For example, lithium salt with strong electron withdrawing property is included. More specifically, for example, LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , LiC (SO ₂ CF ₃ ) Including ₃ etc. These electrolytes may be used alone or in combination of two or more. Moreover, it is preferable that these electrolytes are melt | dissolving in the non-aqueous solvent mentioned above with the density | concentration of 0.5M or more and 1.5M or less.

  The non-aqueous electrolyte may contain a polymer material. For example, a polymer material that can gel a liquid material can be used. As the polymer material, those commonly used in this field can be used. Examples thereof include polyvinylidene fluoride, polyacrylonitrile, and polyethylene oxide.

The non-aqueous electrolyte secondary battery of the present embodiment can be manufactured by the same method as the conventional one except that Mn ₅ O ₈ is used as the negative electrode active material.

Mn ₅ O ₈ is obtained, for example, by heating commercially available γ-manganese oxyhydroxide (γ-MnOOH) in an inert (oxygen-free) atmosphere. Mn ₅ O ₈ that can be used as the negative electrode active material of the non-aqueous electrolyte secondary battery of the present embodiment may be synthesized by a method other than this method. As will be described below, a powder X-ray diffraction pattern can be used to identify Mn ₅ O ₈ .

A paste-like negative electrode mixture is prepared by kneading and dispersing Mn ₅ O ₈ , a binder, a conductive agent, and, if necessary, a thickener in a solvent. Next, a negative electrode mixture is applied to the surface of the negative electrode current collector, and then dried to produce an electrode 2 in which the negative electrode active material layer 2b is provided on the negative electrode current collector 2a. The positive electrode 1 is produced by the same method.

  As the thickener, carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein and the like are preferably used. The solvent is not particularly limited as long as the binder can be dissolved. When an organic binder is used, for example, N-methyl-2-pyrrolidone (NMP), N, N-dimethylformamide, tetrahydrofuran, dimethylacetamide, dimethyl sulfoxide, hexamethylsulfuramide, tetramethylurea, acetone An organic solvent such as methyl ethyl ketone can be used. These organic solvents may be used alone, or a mixed solvent obtained by mixing two or more of these may be used. When using an aqueous binder, it is preferable to use water or warm water as a solvent.

  Thereafter, the positive electrode 1 and the negative electrode 2 are arranged via the separator 3 and inserted into the case 14. By filling the case 14 with the nonaqueous electrolyte 15 and sealing the opening, a nonaqueous electrolyte secondary battery is obtained.

The nonaqueous electrolyte secondary battery of this embodiment includes a negative electrode including a negative electrode active material using Mn ₅ O ₈ . Mn ₅ O ₈ exhibits a battery capacity of about 300 mAh / g when used as a negative electrode, and occludes lithium at a potential of about 0.8 V to 1 V based on the oxidation-reduction potential (Li / Li ⁺ ) of lithium. . For this reason, according to the nonaqueous electrolyte secondary battery of the present embodiment, the capacity is high, and precipitation of lithium metal during low-temperature charging or rapid charging can be suppressed.

  In the present embodiment, the embodiment of the present invention has been described by taking a sheet-type lithium ion secondary battery as an example. However, the nonaqueous electrolyte secondary battery of the present embodiment may have other shapes. It may have a large shape used for a coin shape, a cylindrical shape, a square shape, an electric vehicle or the like.

  Further, the lithium ion secondary battery of the present embodiment can be suitably used for a portable information terminal, a portable electronic device, a small household power storage device, a motorcycle, an electric vehicle, a hybrid electric vehicle, etc., but is not limited thereto. It can also be used for other devices.

(Example)
Hereinafter, the result of producing a nonaqueous electrolyte secondary battery using Mn ₅ O ₈ as the negative electrode and measuring the battery characteristics will be described.

1. Synthesis and identification of Mn ₅ O ₈ γ-manganese oxyhydroxide (γ-MnOOH, manufactured by Tosoh Corporation) was placed in a tubular furnace, and nitrogen was allowed to flow into the tubular furnace at a flow rate of 1 L / min at 10 ° C./min. The temperature in the tubular furnace was increased from room temperature of 25 ° C. to 400 ° C. at a rate of temperature increase. Then, after maintaining the furnace temperature at 400 ° C. for 4 hours, the heating was stopped and cooling was performed in a nitrogen flow until the temperature in the tubular furnace was 90 ° C. or lower.

  γ-manganese oxyhydroxide and the prepared material were identified by powder X-ray diffraction pattern. For measurement, “RINT2000” manufactured by Rigaku was used.

  The powder X-ray diffraction pattern of the γ-manganese oxyhydroxide used is shown in FIG. FIG. 2B shows a powder X-ray diffraction pattern (ICSD # 84948) of γ-manganese oxyhydroxide by ICSD (inorganic crystal structure database) provided by the Chemical Information Association.

FIG. 3A shows a powder X-ray diffraction pattern of the synthesized substance, and FIG. 3B shows a powder X-ray diffraction pattern (ICSD # 16956) of Mn ₅ O ₈ based on the ICSD database.

As can be seen by comparing FIGS. 2 (a) and 2 (b), the γ-manganese oxyhydroxide used for the synthesis of Mn ₅ O ₈ is in good agreement with the powder X-ray diffraction pattern of the database. It turns out that it is the gamma-manganese oxyhydroxide which hardly contains.

Further, since a strong peak near 26 ° seen in the powder X-ray diffraction pattern of FIG. 2A is hardly seen in the powder X-ray diffraction pattern of FIG. It turns out that manganese hydroxide is hardly contained. In the powder X-ray diffraction pattern of FIG. 3 (a), although the peak is slightly broad, the peak is seen at a position that is in good agreement with the peak seen in the powder X-ray diffraction pattern of the database of FIG. 3 (b). It is done. From these facts, it is understood that the obtained substance contains Mn ₅ O ₈ as a main component. Since the peak of the powder X-ray diffraction pattern in FIG. 3A is broad, it is considered that the synthesized substance has somewhat low crystallinity and some impurities are contained. From the XRD peak analysis, it is considered that the impurities are mainly Mn ₃ O ₄ .

2. Preparation and characteristics evaluation of nonaqueous electrolyte secondary battery A nonaqueous electrolyte secondary battery using metallic lithium as a counter electrode was prepared so that the characteristics of the negative electrode using Mn ₅ O ₈ could be easily evaluated.

First, 100 parts by weight of synthesized Mn ₅ O ₈ and 6.34 parts by weight of PVDF (manufactured by Kureha Chemical, trade name “KF polymer L # 7208”) were mixed to prepare a mixture. PVDF was used as a binder.

  The prepared mixture was applied to an electrolytic copper foil having a thickness of 15 μm and dried in a thermostatic bath at 80 ° C. for 3 hours. Thereafter, the electrolytic copper foil coated with the mixture was rolled using a rolling roller. The sheet-like mixture was separated from the electrolytic copper foil to produce an active material layer having a thickness of about 150 μm. Further, after drying in a vacuum drying furnace at 85 ° C. for 1 hour, the active material layer was punched into a circle having a diameter of 12.5 mm to produce an electrode. The weight of this electrode was 9.71 mg.

With an electrode produced using Mn ₅ O ₈ and 400 μm thick metal lithium (made by Honjo Metal), a polyethylene separator having a thickness of 16 μm (made by Asahi Kasei, trade name “9416G”) is sandwiched, It was placed in a CR2032-type coin cell. A non-aqueous electrolyte was prepared by dissolving LiPF ₆ at a concentration of 1 mol / l in a solvent in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 1: 1. A coin cell was filled with a nonaqueous electrolyte and sealed to complete a coin battery.

Li insertion into an active material mainly composed of Mn ₅ O ₈ under the condition that the produced coin battery is held in a constant temperature bath at 25 ° C., a constant current of 0.2 mA and a stop voltage is 0.01 V. (First charge) was performed. Next, after 20 minutes of rest time, Li was desorbed from the active material mainly composed of Mn ₅ O ₈ (initial discharge) under the condition of a constant current of 0.2 mA and a stop voltage of 1.8 V. Went. The charge / discharge characteristics at this time are shown in FIG.

  As shown in FIG. 4, the initial charge is performed at about 0.1 V to 0.3 V with reference to the oxidation-reduction potential of lithium. Since the first charge after the first charge did not release all the charged charges, an irreversible capacity was observed in the fabricated electrode.

  Next, for a coin battery charged under the same conditions as the first charge, a 0.2 mA constant current discharge was performed 11 times under a discharge stop condition where the continuous discharge time was 1 hour and the stop voltage was 1.8 V. Carried out. A 20-minute discharge pause was performed between each discharge. Next, a 0.2 mA constant current charge was carried out 11 times under a charge stop condition where the continuous charge time was 1 hour and the cut voltage was 0.1V. There was a 20 minute charge pause between each charge.

A summary of these charge / discharge characteristics is shown in FIG. In the figure, the lower horizontal axis indicates the capacity of the coin battery, and the upper horizontal axis indicates the capacity per unit weight of Mn ₅ O ₈ . The vertical axis indicates the battery voltage.

As shown in FIG. 5, it was found that the produced electrode was charged and discharged between 0.1 V and 1.8 V with reference to the oxidation-reduction potential of lithium. Moreover, the charge / discharge capacity per unit weight of Mn ₅ O ₈ was 250 to 300 mAh / g. Therefore, it can be seen that when a non-aqueous electrolyte secondary battery including a negative electrode using Mn ₅ O ₈ is manufactured, the battery capacity is increased as compared with the case where titanium oxide is used as the negative electrode active material.

Further, the lower curve in FIG. 5 shows a curve when lithium is inserted into the manufactured electrode. As shown in FIG. 5, the produced electrode occludes and releases lithium at an average potential of about 0.8 V to 1.0 V with reference to the oxidation-reduction potential of lithium. Therefore, it can be seen that the electrode active material using Mn ₅ O ₈ is suitable as a negative electrode material for a lithium ion secondary battery. That is, in an actual non-aqueous electrolyte secondary battery using Mn ₅ O ₈ as a negative electrode, even if a reaction overvoltage of about 0.5 V occurs due to low temperature charge or rapid charge, for example, the potential at which the negative electrode begins to occlude lithium Is higher than the reaction overvoltage and can suppress the deposition of metallic lithium in the negative electrode. Further, since the potential at which lithium starts to be occluded is lower than 1V, the battery voltage can be kept high.

  The present invention is applicable to various non-aqueous electrolyte secondary batteries, and in particular, has a high capacity used for portable information terminals, portable electronic devices, small household electric power storage devices, motorcycles, electric vehicles, hybrid electric vehicles, and the like. The nonaqueous electrolyte secondary battery is suitably used.

DESCRIPTION OF SYMBOLS 1 Positive electrode 1a Positive electrode collector 1b Positive electrode active material layer 2 Negative electrode 2a Negative electrode collector 2b Negative electrode active material layer 3 Separator 11 Positive electrode lead 12 Negative electrode lead 13 Electrode group 14 Battery case 15 Electrolytic solution

Claims (6)

A negative electrode including a negative electrode active material using a manganese oxide having a composition of Mn ₅ O ₈ ;
A positive electrode;
A non-aqueous electrolyte secondary battery comprising a non-aqueous electrolyte having lithium ion conductivity. The non-aqueous electrolyte secondary battery according to claim 1, wherein the positive electrode includes a positive electrode active material composed of a transition metal oxide containing lithium. The non-aqueous electrolyte is
A non-aqueous solvent containing at least one of a cyclic carbonate and a chain carbonate;
The nonaqueous electrolyte secondary battery according to claim 1, further comprising a supporting electrolyte containing lithium ions.   The non-aqueous electrolyte secondary battery according to any one of claims 1 to 3, wherein the manganese oxide is obtained by heating γ-manganese oxyhydroxide in an inert atmosphere. A negative electrode active material for a non-aqueous electrolyte secondary battery using a manganese oxide having a composition of Mn ₅ O ₈ .   The said manganese oxide is a negative electrode active material for nonaqueous electrolyte secondary batteries of Claim 5 obtained by heating (gamma) -manganese oxyhydroxide in inert atmosphere.

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