WO2015022858A1 - Electrolyte solution for lithium-air batteries - Google Patents

Electrolyte solution for lithium-air batteries Download PDF

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Publication number
WO2015022858A1
WO2015022858A1 PCT/JP2014/069971 JP2014069971W WO2015022858A1 WO 2015022858 A1 WO2015022858 A1 WO 2015022858A1 JP 2014069971 W JP2014069971 W JP 2014069971W WO 2015022858 A1 WO2015022858 A1 WO 2015022858A1
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Prior art keywords
lithium
electrolytic solution
halide salt
solution according
air battery
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PCT/JP2014/069971
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French (fr)
Japanese (ja)
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橋本　和仁
翔一 松田
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国立大学法人 東京大学
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M12/00—Hybrid cells; Manufacture thereof
    • H01M12/04—Hybrid cells; Manufacture thereof composed of a half-cell of the fuel-cell type and of a half-cell of the primary-cell type
    • H01M12/06—Hybrid cells; Manufacture thereof composed of a half-cell of the fuel-cell type and of a half-cell of the primary-cell type with one metallic and one gaseous electrode
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M12/00—Hybrid cells; Manufacture thereof
    • H01M12/04—Hybrid cells; Manufacture thereof composed of a half-cell of the fuel-cell type and of a half-cell of the primary-cell type
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M12/00—Hybrid cells; Manufacture thereof
    • H01M12/08—Hybrid cells; Manufacture thereof composed of a half-cell of a fuel-cell type and a half-cell of the secondary-cell type
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • H01M2300/0028—Organic electrolyte characterised by the solvent
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to an electrolyte for a lithium-air battery and a lithium-air battery containing the electrolyte.
  • Lithium-air batteries that use oxygen in the air as the positive electrode active material and lithium metal or the like as the negative electrode active material do not need to contain oxygen as the positive electrode active material in the battery and have a high energy density. It is expected as a power storage system in next-generation electric vehicles and solar / wind power generation facilities (for example, Patent Document 1).
  • the lithium-air battery has a mechanism that allows oxygen reduction (discharge) and oxygen generation (charge) at the positive electrode, and lithium dissolution (discharge) / deposition (charge) at the negative electrode, thereby enabling charge / discharge. Specifically, the following oxygen reduction reaction proceeds at the positive electrode.
  • the present invention uses a lithium-air battery electrolyte that can maintain a high discharge capacity even when undesirable lithium oxide is deposited on the surface of the positive electrode, and the electrolyte. It is an object of the present invention to provide a lithium-air battery.
  • the present inventors have found that the discharge capacity can be improved by adding a halide salt to the electrolytic solution, and the present invention has been completed.
  • the invention provides: (9) Lithium having a positive electrode containing oxygen as a positive electrode active material, a negative electrode containing a negative electrode active material capable of occluding and releasing lithium ions, and the electrolytic solution described in any one of (1) to (8) above -Air batteries; (10) The lithium-air battery according to (9), wherein the positive electrode includes an oxygen redox catalyst; (11) The lithium-air battery according to (9), wherein the negative electrode active material is metallic lithium, a lithium alloy, or a lithium metal oxide.
  • the present invention by adding a halide salt to the electrolytic solution, it is possible to affect the lithium oxide production process in the positive electrode and improve the conductivity of the lithium oxide. Thereby, the electric potential fall in the discharge reaction of a positive electrode is suppressed, and the improvement of the energy capacity of a battery is achieved. Therefore, the improvement in the energy density of the lithium air battery is beneficial in applications in secondary batteries such as automobile batteries and storage batteries.
  • FIG. 1 is a graph showing anion dependence of a discharge curve (chronopotentiometry) in a halide salt / LiTFSA / DME electrolyte.
  • FIG. 2 is a graph showing the cation dependence of a discharge curve (chronopotentiometry) in a halide salt / LiTFSA / DME electrolyte solution.
  • FIG. 3 is a graph showing the salt concentration dependence of the discharge curve (chronopotentiometry) in the halide salt / LiTFSA / DME electrolyte.
  • FIG. 4 is a graph showing a charge / discharge curve in the LiPF 6 / TEGDME electrolytic solution.
  • FIG. 5 is a graph showing a discharge curve (chronopotentiometry) in a LiPF 6 / TEGDME electrolyte and a Nyquist plot by impedance measurement.
  • the halide salt used in the electrolytic solution of the present invention can be a fluoride salt, a chloride salt, or a bromide salt, but is preferably a chloride salt.
  • the cation constituting the halide salt is preferably tetraalkylammonium, N-alkylpyridinium, or N, N-dialkylpyrrolidinium.
  • the alkyl can be a C 1 -C 10 alkyl, preferably C 1 -C 4 .
  • the cation is more preferably tetraethylammonium, N-butylpyridinium, or N-methyl-N-butylpyrrolidinium, and most preferably tetraethylammonium.
  • the halide salt is preferably tetraethylammonium chloride, N-butylpyridinium chloride, N-methyl-N-butylpyrrolidinium chloride, and most preferably tetraethylammonium chloride.
  • the concentration of the halide salt in the electrolytic solution of the present invention can be any concentration up to the saturation concentration as long as the effect of the present invention is obtained. Although it depends on the solvent to be used later, it is preferably 0.5 to 5 mM, more preferably 1 to 3 mM.
  • the non-aqueous solvent can be used for the solvent used in the electrolyte solution of this invention, Preferably it is an aprotic organic solvent.
  • the non-aqueous solvent include ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), ethyl carbonate, butylene carbonate, ⁇ -butyrolactone, sulfolane.
  • 1,2-dimethoxymethane, 1,2-dimethoxyethane (DME), tetraethyl glycol dimethyl ether (TEGDME), 1,3-dimethoxypropane, diethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, dimethyl sulfoxide (DMSO) Can be mentioned. Among these, one type may be used alone, or two or more types may be used in combination. However, it is not limited to these. In particular, 1,2-dimethoxyethane (DME) or tetraethyl glycol dimethyl ether (TEGDME) is preferred.
  • the non-aqueous solvent is preferably a solvent having high oxygen solubility from the viewpoint that dissolved oxygen can be efficiently used for the reaction.
  • a low-volatile liquid such as an ionic liquid such as N-methyl N-butylpyrrolidinium bis (trifluoromethanesulfonyl) imide, tetraethylammonium bistrifluoromethanesulfonylimide, or the like can be used.
  • It can also be used in the form of a non-aqueous gel electrolyte in which a polymer is added to the non-aqueous electrolyte and gelled. This can be obtained by adding a polymer such as polyethylene oxide (PEO), polyacrylonitrile (PAN), or polymethyl methacrylate (PMMA) to the electrolytic solution of the present invention and gelling.
  • PEO polyethylene oxide
  • PAN polyacrylonitrile
  • PMMA polymethyl methacrylate
  • the electrolytic solution of the present invention can contain a supporting electrolyte salt generally used in lithium-air batteries. Specifically, lithium that dissociates in the electrolytic solution and supplies lithium ions.
  • Salt The lithium salt.
  • the lithium salt is not particularly limited, and examples thereof include LiPF 6 , LiN (CF 3 SO 2 ) 2 (“LiTFSA”), LiN (C 2 F 5 SO 2 ) 2 (“LiBETI”), LiCF 3 SO 3 , LiC 4 F 9 SO 3 , LiC (CF 3 SO 2 ) 3 , LiN (CF 3 SO 2 ) (C 2 F 5 SO 2 ), LiN (CF 3 SO 2 ) (C 3 F 7 SO 2 ), LiN (CF 3 SO 2 ) (C 4 F 9 SO 2 ), LiN (SO 2 F) 2 , LiBF 4 , LiClO 4 , and any combination thereof.
  • the concentration range of the lithium salt in the electrolytic solution can be generally used, and can be appropriately adjusted by those skilled in the art.
  • the said electrolyte solution can also contain another component as needed for the purpose of the improvement of the function.
  • the other components include conventionally known overcharge inhibitors, dehydrating agents, deoxidizing agents, and property improving aids.
  • overcharge inhibitor examples include aromatic compounds such as biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, and dibenzofuran; 2-fluoro Partially fluorinated products of the above aromatic compounds such as biphenyl, o-cyclohexylfluorobenzene, p-cyclohexylfluorobenzene; fluorinated anisole such as 2,4-difluoroanisole, 2,5-difluoroanisole and 2,6-difluoroaniol Compounds.
  • An overcharge inhibitor may be used individually by 1 type, and may use 2 or more types together.
  • the content of the overcharge inhibitor in the electrolytic solution is preferably 0.01 to 5% by mass.
  • the overcharge inhibitor in the electrolytic solution it becomes easier to suppress the rupture / ignition of the secondary battery due to overcharge, and the secondary battery can be used more stably.
  • the dehydrating agent examples include molecular sieves, sodium sulfate, magnesium sulfate, calcium hydride, sodium hydride, potassium hydride, lithium aluminum hydride and the like.
  • a solvent obtained by performing rectification after dehydrating with the dehydrating agent can be used. Moreover, you may use the solvent which performed only the dehydration by the said dehydrating agent, without performing rectification.
  • the property improving aid examples include succinic anhydride, glutaric anhydride, maleic anhydride, citraconic anhydride, glutaconic anhydride, itaconic anhydride, diglycolic anhydride, cyclohexanedicarboxylic anhydride, cyclopentanetetracarboxylic acid Carboxylic anhydrides such as anhydrides and phenylsuccinic anhydrides; ethylene sulfite, 1,3-propane sultone, 1,4-butane sultone, methyl methanesulfonate, busulfan, sulfolane, sulfolene, dimethyl sulfone, diphenyl sulfone, methyl Sulfur-containing compounds such as phenylsulfone, dibutyl disulfide, dicyclohexyl disulfide, tetramethylthiuram monosulfide, N, N-dimethylmethanesul
  • Hydrocarbon compounds such as fluorobenzene, difluorobenzene, hexafluorobenzene, benzotrifluoride and the like can be mentioned.
  • These characteristic improvement aids may be used alone or in combination of two or more.
  • the content of the characteristic improving auxiliary in the electrolytic solution is preferably 0.01 to 5% by mass.
  • the positive electrode can be one that is normally used as a positive electrode of an air battery, includes a conductive material having a gap through which oxygen and lithium ions can move, and may contain a binder. Moreover, you may contain the catalyst which accelerates
  • conductive material for example, carbon materials, conductive fibers such as metal fibers, metal powders such as copper, silver, nickel, and aluminum, and organic conductive materials such as polyphenylene derivatives can be used.
  • carbon material graphite, soft carbon, hard carbon, carbon black, ketjen black, acetylene black, graphite, activated carbon, carbon nanotube, carbon fiber and the like can be used.
  • mesoporous carbon obtained by firing a synthetic resin containing an aromatic ring, petroleum pitch or the like can be used.
  • fluorine resins such as polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylenetetrafluoroethylene (ETFE), polyethylene, polypropylene, or the like can be preferably used.
  • the negative electrode current collector is not particularly limited as long as it has conductivity, but a rod-like body, a plate-like body, a foil-like body, a net-like body mainly composed of copper, nickel, aluminum, stainless steel or the like. Etc. can be used.
  • MnO 2 , Fe 2 O 3 , NiO, CuO, Pt, Co, or the like can be used as a catalyst for performing an oxygen redox reaction with high efficiency.
  • a porous body such as a mesh (grid) metal, a sponge (foamed) metal, a punched metal, or an expanded metal is used in order to increase the diffusion of oxygen.
  • the metal include copper, nickel, aluminum, and stainless steel.
  • the negative electrode in the lithium-air battery of the present invention is an electrode containing a negative electrode active material capable of electrochemically inserting and extracting lithium ions.
  • Examples of such a negative electrode active material include lithium metal or an alloy containing a lithium element, a metal oxide, and a metal nitride.
  • examples of the alloy having a lithium element include a lithium aluminum alloy, a lithium tin alloy, a lithium lead alloy, and a lithium silicon alloy.
  • the metal oxide having a lithium element can be, for example, lithium titanium oxide (Li 4 Ti 6 O 12, etc.) and the like.
  • examples of the metal nitride containing a lithium element include lithium cobalt nitride, lithium iron nitride, and lithium manganese nitride.
  • Carbonaceous materials such as natural graphite (graphite), highly oriented graphite (HOPG), and amorphous carbon can also be used. These negative electrode active materials may be used individually by 1 type, and may use 2 or more types together.
  • the negative electrode layer in the present invention may contain only the negative electrode active material, or may contain at least one of a conductive material and a binder in addition to the negative electrode active material.
  • a negative electrode active material has a foil shape
  • a negative electrode containing only the negative electrode active material can be obtained.
  • the negative electrode active material is in a powder form, a negative electrode having a negative electrode active material and a binder (binder) can be obtained.
  • a doctor blade method, a molding method using a pressure press, or the like can be used as a method for forming a negative electrode using a powdered negative electrode active material.
  • the same materials as the positive electrode can be used.
  • the separator used in the lithium-air battery of the present invention is not particularly limited as long as it has a function of electrically separating the positive electrode layer and the negative electrode layer.
  • PE polyethylene
  • a porous sheet made of a resin such as polypropylene (PP), polyester, cellulose, or polyamide, or a porous insulating material such as a nonwoven fabric such as a nonwoven fabric or a glass fiber nonwoven fabric.
  • the shape of the lithium-air battery of the present invention is not particularly limited as long as it can accommodate a positive electrode, a negative electrode, and an electrolyte solution.
  • a cylindrical shape, a coin shape, a flat plate shape, a laminate Examples include molds.
  • the battery housing case may be an open-air battery case or a sealed battery case.
  • the battery case In the case of a battery case that is open to the atmosphere, the battery case has a vent hole through which the atmosphere can enter and exit, and the atmosphere can contact the air electrode.
  • the battery case is a sealed battery case, it is preferable to provide a gas (air) supply pipe and a discharge pipe in the sealed battery case.
  • the gas to be supplied / exhausted is preferably a dry gas, in particular, preferably has a high oxygen concentration, and more preferably pure oxygen (99.99%).
  • the electrolyte solution and lithium-air battery of the present invention are suitable for use as a secondary battery, but use of a primary battery is not excluded.
  • FIG. 1 shows a comparison of discharge curves obtained when the cation component of a halide salt is fixed to tetraethylammonium (TEA) and different anion components are used.
  • the halide salts used here are tetraethylammonium chloride (TEA-Cl), tetraethylammonium bromide (TEA-Br), and tetraethylammonium sulfonate (TEA-sulfo) as a comparative example, each having a concentration of 1 mM. is there.
  • the solvent is 1,2-dimethoxyethane (DME), and the lithium salt is LiTFSA. From the results of FIG. 1, it was found that the discharge capacity was most improved in the case of TEACl, which was about 330 mC.
  • FIG. 2 shows a comparison of discharge curves obtained when the anion component of the halide salt is fixed to chloride (Cl ⁇ ) and different cation components are used.
  • the halide salts used here are tetraethylammonium chloride (TEA-Cl), tetramethylammonium chloride (TMA-Cl), tetraamylammonium chloride (TAA-Cl), N-butylpyridinium chloride (BP-Cl), chloride N-methyl-N-butylpyrrolidinium (MBP-Cl), each having a concentration of 1 mM.
  • the solvent is 1,2-dimethoxyethane (DME), and the lithium salt is LiTFSA.
  • FIG. 3 shows the result of measuring the concentration dependence of TEA-Cl in which the most remarkable improvement in discharge capacity was observed.
  • the solvent is 1,2-dimethoxyethane (DME), and the lithium salt is LiTFSA. From FIG. 3, it was found that the discharge capacity was improved at 0.5 mM, and the greatest improvement was obtained at 1.0 mM.
  • FIG. 4 shows charging / discharging curves with and without addition of TEA-Cl.
  • the solvent tetraethyl glycol dimethyl ether (TEGDME), the lithium salt is LiPF 6.
  • TEGDME solvent tetraethyl glycol dimethyl ether
  • the TEA-Cl reduced the overvoltage in both charging and discharging. This is thought to be because the Li—O bond present on the positive electrode surface is weakened by the TEA cation during charging, while the Cl ⁇ anion acts on the desolvation of Li + ions during discharge. It is thought that this is because.
  • Impedance comparison As shown in FIG. 5, when TEA-Cl was added and when it was not added, impedance was compared when TEA-Cl was added and when TEA-Cl was added using Nyquist plot. The decrease in ion impedance at the time of addition indicates that the improvement in the discharge capacity is due to the fact that the electronic conductivity of Li 2 O 2 deposited on the positive electrode surface is increased by TEA-Cl.

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Abstract

[Problem] The present invention addresses the problem of providing: an electrolyte solution for lithium-air batteries, which is capable of maintaining high discharge capacity even in cases where an undesirable lithium oxide is deposited on the positive electrode surface; and a lithium-air battery which uses the electrolyte solution. [Solution] An electrolyte solution for lithium-air batteries, which contains a nonaqueous solvent and a halide salt; and a lithium-air battery which comprises the electrolyte solution.

Description

リチウム－空気電池用電解液Electrolyte for lithium-air battery
　本発明は、リチウム－空気電池用電解液及び当該電解液を含むリチウム－空気電池に関する。 The present invention relates to an electrolyte for a lithium-air battery and a lithium-air battery containing the electrolyte.
　空気中の酸素を正極活物質とし、リチウム金属等を負極活物質として用いるリチウム－空気電池は、正極活物質である酸素を電池内に内蔵する必要がなく、高いエネルギー密度を有することから、次世代電気自動車や太陽光・風力発電施設における蓄電システムとして期待されている（例えば、特許文献１）。 Lithium-air batteries that use oxygen in the air as the positive electrode active material and lithium metal or the like as the negative electrode active material do not need to contain oxygen as the positive electrode active material in the battery and have a high energy density. It is expected as a power storage system in next-generation electric vehicles and solar / wind power generation facilities (for example, Patent Document 1).
　リチウム－空気電池は、正極で酸素還元（放電）及び酸素発生（充電）、負極でリチウムの溶解（放電）・析出（充電）が起こり、充放電が可能となる仕組みである。具体的には、正極において以下のような酸素還元反応が進行する。
Figure JPOXMLDOC01-appb-M000001

The lithium-air battery has a mechanism that allows oxygen reduction (discharge) and oxygen generation (charge) at the positive electrode, and lithium dissolution (discharge) / deposition (charge) at the negative electrode, thereby enabling charge / discharge. Specifically, the following oxygen reduction reaction proceeds at the positive electrode.
Figure JPOXMLDOC01-appb-M000001

　しかしながら、放電反応において生成する絶縁性のリチウム酸化物が正極表面上に堆積し、電位の低下を引き起こし、その結果、エネルギー容量が理論値を大きく下回ってしまうという問題があった。 However, there is a problem that the insulating lithium oxide generated in the discharge reaction is deposited on the surface of the positive electrode, causing a decrease in potential, and as a result, the energy capacity is greatly lower than the theoretical value.
特開２００８－１１２７２４号公報JP 2008-1112724 A
　そこで、本発明は、上記問題点に鑑み、正極表面上に望ましくないリチウム酸化物が堆積した場合でも、高い放電容量を維持することができるリチウム－空気電池用電解液、及び当該電解液を用いたリチウム－空気電池を提供することを課題とするものである。 Therefore, in view of the above problems, the present invention uses a lithium-air battery electrolyte that can maintain a high discharge capacity even when undesirable lithium oxide is deposited on the surface of the positive electrode, and the electrolyte. It is an object of the present invention to provide a lithium-air battery.
　本発明者らは、上記課題を解決するべく鋭意検討を行った結果、電解液にハロゲン化物塩を添加することによって放電容量の向上が得られることを見出し、本発明を完成するに至った。 As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the discharge capacity can be improved by adding a halide salt to the electrolytic solution, and the present invention has been completed.
　すなわち、本発明は、一態様において、
（１）非水溶媒とハロゲン化物塩とを含むリチウム－空気電池用電解液；
（２）前記ハロゲン化物塩が、塩化物塩である、上記（１）に記載の電解液；
（３）ハロゲン化物塩を構成するカチオンが、テトラ（Ｃ１～Ｃ4）アンモニウム、Ｎ－アルキルピリジニウム、及びＮ，Ｎ－ジアルキルピロリジニウムよりなる群から選択される、上記（１）に記載の電解液；
（４）前記ハロゲン化物塩が、塩化テトラエチルアンモニウムである、上記（１）に記載の電解液；
（５）前記ハロゲン化物塩の濃度が、０．５～５ｍＭである、上記（１）～（４）のいずれか１に記載の電解液；
（６）前記ハロゲン化物塩の濃度が、１～３ｍＭである、上記（１）～（４）のいずれか１に記載の電解液；
（７）前記非水溶媒が、非プロトン性溶媒である、上記（１）～（６）のいずれか１に記載の電解液；
（８）前記非水溶媒が、１，２－ジメトキシエタン又はテトラエチルグリコールジメチルエーテルである、上記（１）～（６）のいずれか１に記載の電解液
に関する。 That is, the present invention in one aspect,
(1) Lithium-air battery electrolyte containing a non-aqueous solvent and a halide salt;
(2) The electrolyte solution according to (1), wherein the halide salt is a chloride salt;
(3) The cation constituting the halide salt is selected from the group consisting of tetra (C 1 -C 4 ) ammonium, N-alkylpyridinium, and N, N-dialkylpyrrolidinium, Electrolytes of
(4) The electrolytic solution according to (1), wherein the halide salt is tetraethylammonium chloride;
(5) The electrolytic solution according to any one of (1) to (4), wherein the concentration of the halide salt is 0.5 to 5 mM;
(6) The electrolytic solution according to any one of (1) to (4), wherein the concentration of the halide salt is 1 to 3 mM;
(7) The electrolyte solution according to any one of (1) to (6), wherein the non-aqueous solvent is an aprotic solvent;
(8) The electrolyte solution according to any one of (1) to (6), wherein the nonaqueous solvent is 1,2-dimethoxyethane or tetraethylglycol dimethyl ether.
別の態様において、本発明は、
（９）酸素を正極活物質とする正極と、リチウムイオンを吸蔵及び放出可能な負極活物質を含む負極と、上記（１）～（８）のいずれか１に記載の電解液とを有するリチウム－空気電池；
（１０）前記正極が酸素の酸化還元触媒を含む、上記（９）に記載のリチウム－空気電池；
（１１）前記負極活物質が、金属リチウム、リチウム合金、又はリチウム金属酸化物である、上記（９）に記載のリチウム－空気電池
に関する。 In another aspect, the invention provides:
(9) Lithium having a positive electrode containing oxygen as a positive electrode active material, a negative electrode containing a negative electrode active material capable of occluding and releasing lithium ions, and the electrolytic solution described in any one of (1) to (8) above -Air batteries;
(10) The lithium-air battery according to (9), wherein the positive electrode includes an oxygen redox catalyst;
(11) The lithium-air battery according to (9), wherein the negative electrode active material is metallic lithium, a lithium alloy, or a lithium metal oxide.
　本発明によれば、電解液にハロゲン化物塩を添加することで、正極におけるリチウム酸化物の生成プロセスに影響を与え、リチウム酸化物の伝導性を向上させることができる。これにより、正極の放電反応における電位低下を抑制し、電池のエネルギー容量の向上が達成できる。従って、リチウム空気電池のエネルギー密度向上によって、自動車用電池や蓄電池等の２次電池における応用において有益である。 According to the present invention, by adding a halide salt to the electrolytic solution, it is possible to affect the lithium oxide production process in the positive electrode and improve the conductivity of the lithium oxide. Thereby, the electric potential fall in the discharge reaction of a positive electrode is suppressed, and the improvement of the energy capacity of a battery is achieved. Therefore, the improvement in the energy density of the lithium air battery is beneficial in applications in secondary batteries such as automobile batteries and storage batteries.
図１は、ハロゲン化物塩／ＬｉＴＦＳＡ／ＤＭＥ電解液中における放電曲線（クロノポテンシオメトリー）のアニオン依存性を示すグラフである。FIG. 1 is a graph showing anion dependence of a discharge curve (chronopotentiometry) in a halide salt / LiTFSA / DME electrolyte. 図２は、ハロゲン化物塩／ＬｉＴＦＳＡ／ＤＭＥ電解液中における放電曲線（クロノポテンシオメトリー）のカチオン依存性を示すグラフである。FIG. 2 is a graph showing the cation dependence of a discharge curve (chronopotentiometry) in a halide salt / LiTFSA / DME electrolyte solution. 図３は、ハロゲン化物塩／ＬｉＴＦＳＡ／ＤＭＥ電解液中における放電曲線（クロノポテンシオメトリー）のハロゲン化物の塩濃度依存性を示すグラフである。FIG. 3 is a graph showing the salt concentration dependence of the discharge curve (chronopotentiometry) in the halide salt / LiTFSA / DME electrolyte. 図４は、ＬｉＰＦ６／ＴＥＧＤＭＥ電解液中における充放電曲線を示すグラフである。FIG. 4 is a graph showing a charge / discharge curve in the LiPF 6 / TEGDME electrolytic solution. 図５は、ＬｉＰＦ６／ＴＥＧＤＭＥ電解液中における放電曲線（クロノポテンシオメトリー）、及びインピーダンス測定によるナイキストプッロトを示すグラフである。FIG. 5 is a graph showing a discharge curve (chronopotentiometry) in a LiPF 6 / TEGDME electrolyte and a Nyquist plot by impedance measurement.
　以下、本発明の実施形態について説明する。本発明の範囲はこれらの説明に拘束されることはなく、以下の例示以外についても、本発明の趣旨を損なわない範囲で適宜変更し実施することができる。 Hereinafter, embodiments of the present invention will be described. The scope of the present invention is not limited to these descriptions, and other than the following examples, the scope of the present invention can be appropriately changed and implemented without departing from the spirit of the present invention.
１．電解液
（１）ハロゲン化物塩
　本発明の電解液において用いられるハロゲン化物塩は、フッ化物塩、塩化物塩、臭化物塩であることができるが、好ましくは塩化物塩である。当該ハロゲン化物塩を構成するカチオンは、好ましくは、テトラアルキルアンモニウム、Ｎ－アルキルピリジニウム、又はＮ，Ｎ－ジアルキルピロリジニウムである。ここで、アルキルは、Ｃ１～Ｃ10のアルキルであることができ、好ましくは、Ｃ１～Ｃ4である。例えば、当該カチオンは、より好ましくは、テトラエチルアンモニウム、Ｎ－ブチルピリジニウム、又はＮ－メチル－Ｎ－ブチルピロリジニウムであり、最も好ましくは、テトラエチルアンモニウムである。 1. Electrolytic Solution (1) Halide Salt The halide salt used in the electrolytic solution of the present invention can be a fluoride salt, a chloride salt, or a bromide salt, but is preferably a chloride salt. The cation constituting the halide salt is preferably tetraalkylammonium, N-alkylpyridinium, or N, N-dialkylpyrrolidinium. Here, the alkyl can be a C 1 -C 10 alkyl, preferably C 1 -C 4 . For example, the cation is more preferably tetraethylammonium, N-butylpyridinium, or N-methyl-N-butylpyrrolidinium, and most preferably tetraethylammonium.
　従って、具体的には、当該ハロゲン化物塩は、好ましくは、塩化テトラエチルアンモニウム、塩化Ｎ－ブチルピリジニウム、塩化Ｎ－メチル－Ｎ－ブチルピロリジニウムであり、最も好ましくは、塩化テトラエチルアンモニウムである。 Therefore, specifically, the halide salt is preferably tetraethylammonium chloride, N-butylpyridinium chloride, N-methyl-N-butylpyrrolidinium chloride, and most preferably tetraethylammonium chloride.
　本発明の電解液におけるハロゲン化物塩の濃度は、上記本発明の効果が得られる限り、飽和濃度までの任意の濃度であることができる。用いられる後述の溶媒にも依存するが、好ましくは０．５～５ｍＭであり、より好ましくは１～３ｍＭである。 The concentration of the halide salt in the electrolytic solution of the present invention can be any concentration up to the saturation concentration as long as the effect of the present invention is obtained. Although it depends on the solvent to be used later, it is preferably 0.5 to 5 mM, more preferably 1 to 3 mM.
（２）溶媒
　本発明の電解液において用いられる溶媒は、非水溶媒を用いることができ、好ましくは非プロトン性有機溶媒である。非水溶媒としては、例えば、エチレンカーボネート（ＥＣ）、プロピレンカーボネート（ＰＣ）、ジメチルカーボネート（ＤＭＣ）、ジエチルカーボネート（ＤＥＣ）、エチルメチルカーボネート（ＥＭＣ）、エチルカーボネート、ブチレンカーボネート、γ－ブチロラクトン、スルホラン、１，２－ジメトキシメタン、１，２－ジメトキシエタン（ＤＭＥ）、テトラエチルグリコールジメチルエーテル（ＴＥＧＤＭＥ）、１，３－ジメトキシプロパン、ジエチルエーテル、テトラヒドロフラン、２－メチルテトラヒドロフラン、ジメチルスルフォキシド（ＤＭＳＯ）が挙げられる。これらのうち１種を単独で用いてもよく、２種以上を組み合わせて用いてもよい。ただし、これらに限定されるものではない。特に、１，２－ジメトキシエタン（ＤＭＥ）又はテトラエチルグリコールジメチルエーテル（ＴＥＧＤＭＥ）が好適である。 (2) Solvent The non-aqueous solvent can be used for the solvent used in the electrolyte solution of this invention, Preferably it is an aprotic organic solvent. Examples of the non-aqueous solvent include ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), ethyl carbonate, butylene carbonate, γ-butyrolactone, sulfolane. 1,2-dimethoxymethane, 1,2-dimethoxyethane (DME), tetraethyl glycol dimethyl ether (TEGDME), 1,3-dimethoxypropane, diethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, dimethyl sulfoxide (DMSO) Can be mentioned. Among these, one type may be used alone, or two or more types may be used in combination. However, it is not limited to these. In particular, 1,2-dimethoxyethane (DME) or tetraethyl glycol dimethyl ether (TEGDME) is preferred.
　なお、上記非水溶媒は、溶存した酸素を効率良く反応に用いることができるという観点から、酸素溶解性が高い溶媒であることが好ましい。また、例えば、Ｎ－メチルＮ－ブチルピロリジニウム　ビス（トリフルオロメタンスルホニル）イミド、テトラエチルアンモニウム　ビストリフルオロメタンスルフォニルイミド等の、イオン性液体等の低揮発性液体を用いることもできる。上記非水系電解液にポリマーを添加してゲル化させた非水ゲル電解質の形態で用いることもできる。これは、本発明の電解液に、ポリエチレンオキシド（ＰＥＯ）、ポリアクリルニトリル（ＰＡＮ）またはポリメチルメタクリレート（ＰＭＭＡ）等のポリマーを添加し、ゲル化することにより、得ることができる。 The non-aqueous solvent is preferably a solvent having high oxygen solubility from the viewpoint that dissolved oxygen can be efficiently used for the reaction. Further, for example, a low-volatile liquid such as an ionic liquid such as N-methyl N-butylpyrrolidinium bis (trifluoromethanesulfonyl) imide, tetraethylammonium bistrifluoromethanesulfonylimide, or the like can be used. It can also be used in the form of a non-aqueous gel electrolyte in which a polymer is added to the non-aqueous electrolyte and gelled. This can be obtained by adding a polymer such as polyethylene oxide (PEO), polyacrylonitrile (PAN), or polymethyl methacrylate (PMMA) to the electrolytic solution of the present invention and gelling.
（３）支持電解質
　本発明の電解液には、リチウム－空気電池において一般的に用いられる支持電解質塩を含むことができ、具体的には、電解液中で解離してリチウムイオンを供給するリチウム塩当該リチウム塩である。かかるリチウム塩としては、特に限定されるものではないが、例えば、ＬｉＰＦ６、ＬｉＮ（ＣＦ３ＳＯ２）２（「ＬｉＴＦＳＡ」）、ＬｉＮ（Ｃ２Ｆ５ＳＯ２）２（「ＬｉＢＥＴＩ」）、ＬｉＣＦ３ＳＯ３、ＬｉＣ４Ｆ９ＳＯ３、ＬｉＣ（ＣＦ３ＳＯ２）３、ＬｉＮ（ＣＦ３ＳＯ２）（Ｃ２Ｆ５ＳＯ２）、ＬｉＮ（ＣＦ３ＳＯ２）（Ｃ３Ｆ７ＳＯ２）、ＬｉＮ（ＣＦ３ＳＯ２）（Ｃ４Ｆ９ＳＯ２）、ＬｉＮ（ＳＯ２Ｆ）２、ＬｉＢＦ４、ＬｉＣｌＯ４、及びこれらの任意の組み合わせから選択されるものが挙げられる。 (3) Supporting Electrolyte The electrolytic solution of the present invention can contain a supporting electrolyte salt generally used in lithium-air batteries. Specifically, lithium that dissociates in the electrolytic solution and supplies lithium ions. Salt The lithium salt. The lithium salt is not particularly limited, and examples thereof include LiPF 6 , LiN (CF 3 SO 2 ) 2 (“LiTFSA”), LiN (C 2 F 5 SO 2 ) 2 (“LiBETI”), LiCF 3 SO 3 , LiC 4 F 9 SO 3 , LiC (CF 3 SO 2 ) 3 , LiN (CF 3 SO 2 ) (C 2 F 5 SO 2 ), LiN (CF 3 SO 2 ) (C 3 F 7 SO 2 ), LiN (CF 3 SO 2 ) (C 4 F 9 SO 2 ), LiN (SO 2 F) 2 , LiBF 4 , LiClO 4 , and any combination thereof.
　上記電解液中におけるリチウム塩の濃度範囲は、一般に用いられるものであることができ、当業者であれば適宜調整することができる。 The concentration range of the lithium salt in the electrolytic solution can be generally used, and can be appropriately adjusted by those skilled in the art.
（３）その他の成分
　また、上記電解液は、その機能の向上等の目的で、必要に応じて他の成分を含むこともできる。他の成分としては、例えば、従来公知の過充電防止剤、脱水剤、脱酸剤、特性改善助剤等が挙げられる。 (3) Other components Moreover, the said electrolyte solution can also contain another component as needed for the purpose of the improvement of the function. Examples of the other components include conventionally known overcharge inhibitors, dehydrating agents, deoxidizing agents, and property improving aids.
　過充電防止剤としては、例えば、ビフェニル、アルキルビフェニル、ターフェニル、ターフェニルの部分水素化体、シクロヘキシルベンゼン、ｔ－ブチルベンゼン、ｔ－アミルベンゼン、ジフェニルエーテル、ジベンゾフラン等の芳香族化合物；２－フルオロビフェニル、ｏ－シクロヘキシルフルオロベンゼン、ｐ－シクロヘキシルフルオロベンゼン等の前記芳香族化合物の部分フッ素化物；２，４－ジフルオロアニソール、２，５－ジフルオロアニソールおよび２，６－ジフルオロアニオール等の含フッ素アニソール化合物が挙げられる。過充電防止剤は、１種を単独で用いてもよく、２種以上を併用してもよい。 Examples of the overcharge inhibitor include aromatic compounds such as biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, and dibenzofuran; 2-fluoro Partially fluorinated products of the above aromatic compounds such as biphenyl, o-cyclohexylfluorobenzene, p-cyclohexylfluorobenzene; fluorinated anisole such as 2,4-difluoroanisole, 2,5-difluoroanisole and 2,6-difluoroaniol Compounds. An overcharge inhibitor may be used individually by 1 type, and may use 2 or more types together.
　電解液が過充電防止剤を含有する場合、電解液中の過充電防止剤の含有量は、０．０１～５質量％であることが好ましい。電解液に過充電防止剤を０．１質量％以上含有させることにより、過充電による二次電池の破裂・発火を抑制することがさらに容易になり、二次電池をより安定に使用できる。 When the electrolytic solution contains an overcharge inhibitor, the content of the overcharge inhibitor in the electrolytic solution is preferably 0.01 to 5% by mass. By containing 0.1% by mass or more of the overcharge inhibitor in the electrolytic solution, it becomes easier to suppress the rupture / ignition of the secondary battery due to overcharge, and the secondary battery can be used more stably.
　脱水剤としては、例えば、モレキュラーシーブス、芒硝、硫酸マグネシウム、水素化カルシウム、水素化ナトリウム、水素化カリウム、水素化リチウムアルミニウム等が挙げられる。本発明の電解液に用いる溶媒は、前記脱水剤で脱水を行った後に精留を行ったものを使用することもできる。また、精留を行わずに前記脱水剤による脱水のみを行った溶媒を使用してもよい。 Examples of the dehydrating agent include molecular sieves, sodium sulfate, magnesium sulfate, calcium hydride, sodium hydride, potassium hydride, lithium aluminum hydride and the like. As the solvent used in the electrolytic solution of the present invention, a solvent obtained by performing rectification after dehydrating with the dehydrating agent can be used. Moreover, you may use the solvent which performed only the dehydration by the said dehydrating agent, without performing rectification.
　特性改善助剤としては、例えば、無水コハク酸、無水グルタル酸、無水マレイン酸、無水シトラコン酸、無水グルタコン酸、無水イタコン酸、無水ジグリコール酸、シクロヘキサンジカルボン酸無水物、シクロペンタンテトラカルボン酸二無水物、フェニルコハク酸無水物等のカルボン酸無水物；エチレンサルファイト、１，３－プロパンスルトン、１，４－ブタンスルトン、メタンスルホン酸メチル、ブスルファン、スルホラン、スルホレン、ジメチルスルホン、ジフェニルスルホン、メチルフェニルスルホン、ジブチルジスルフィド、ジシクロヘキシルジスルフィド、テトラメチルチウラムモノスルフィド、Ｎ，Ｎ－ジメチルメタンスルホンアミド、Ｎ，Ｎ－ジエチルメタンスルホンアミド等の含硫黄化合物；１－メチル－２－ピロリジノン、１－メチル－２－ピペリドン、３－メチル－２－オキサゾリジノン、１，３－ジメチル－２－イミダゾリジノン、Ｎ－メチルスクシイミド等の含窒素化合物；ヘプタン、オクタン、シクロヘプタン等の炭化水素化合物；フルオロベンゼン、ジフルオロベンゼン、ヘキサフルオロベンゼン、ベンゾトリフルオライド等の含フッ素芳香族化合物が挙げられる。これら特性改善助剤は、１種を単独で用いてもよく、２種以上を併用してもよい。電解液が特性改善助剤を含有する場合、電解液中の特性改善助剤の含有量は、０．０１～５質量％であることが好ましい。 Examples of the property improving aid include succinic anhydride, glutaric anhydride, maleic anhydride, citraconic anhydride, glutaconic anhydride, itaconic anhydride, diglycolic anhydride, cyclohexanedicarboxylic anhydride, cyclopentanetetracarboxylic acid Carboxylic anhydrides such as anhydrides and phenylsuccinic anhydrides; ethylene sulfite, 1,3-propane sultone, 1,4-butane sultone, methyl methanesulfonate, busulfan, sulfolane, sulfolene, dimethyl sulfone, diphenyl sulfone, methyl Sulfur-containing compounds such as phenylsulfone, dibutyl disulfide, dicyclohexyl disulfide, tetramethylthiuram monosulfide, N, N-dimethylmethanesulfonamide, N, N-diethylmethanesulfonamide; 1-methyl-2-pyrrole Non-containing compounds such as 1-methyl-2-piperidone, 3-methyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone, N-methylsuccinimide; heptane, octane, cycloheptane, etc. Hydrocarbon compounds; fluorine-containing aromatic compounds such as fluorobenzene, difluorobenzene, hexafluorobenzene, benzotrifluoride and the like can be mentioned. These characteristic improvement aids may be used alone or in combination of two or more. When the electrolytic solution contains a characteristic improving aid, the content of the characteristic improving auxiliary in the electrolytic solution is preferably 0.01 to 5% by mass.
２．リチウム－空気電池
（１）正極
　本発明のリチウム－空気電池の正極では、正極活物質として酸素が使用される。当該正極は、空気電池の正極として通常用いられるものであることができ、酸素及びリチウムイオンが移動できる空隙を有する導電性材料を含み、結着剤を含有してもよい。また、酸素の酸化還元反応を促進する触媒を含有してもよい。 2. Lithium-Air Battery (1) Positive Electrode In the positive electrode of the lithium-air battery of the present invention, oxygen is used as the positive electrode active material. The positive electrode can be one that is normally used as a positive electrode of an air battery, includes a conductive material having a gap through which oxygen and lithium ions can move, and may contain a binder. Moreover, you may contain the catalyst which accelerates | stimulates the oxidation-reduction reaction of oxygen.
　導電性材料としては、例えば、炭素材料、金属繊維等の導電性繊維、銅、銀、ニッケル、アルミニウム等の金属粉末、ポリフェニレン誘導体等の有機導電性材料を使用することができる。炭素材料として、黒鉛、ソフトカーボン、ハードカーボン、カーボンブラック、ケッチェンブラック、アセチレンブラック、グラファイト、活性炭、カーボンナノチューブ、カーボンファイバー等を使用することができる。また、芳香環を含む合成樹脂、石油ピッチ等を焼成して得られたメソポーラスカーボンを使用することもできる As the conductive material, for example, carbon materials, conductive fibers such as metal fibers, metal powders such as copper, silver, nickel, and aluminum, and organic conductive materials such as polyphenylene derivatives can be used. As the carbon material, graphite, soft carbon, hard carbon, carbon black, ketjen black, acetylene black, graphite, activated carbon, carbon nanotube, carbon fiber and the like can be used. Also, mesoporous carbon obtained by firing a synthetic resin containing an aromatic ring, petroleum pitch or the like can be used.
　結着剤としては、例えば、ポリフッ化ビニリデン（ＰＶＤＦ）、ポリテトラフルオロエチレン（ＰＴＦＥ）、エチレンテトラフルオロエチレン（ＥＴＦＥ）等のフッ素系樹脂、或いは、ポリエチレン、ポリプロピレンなどを好ましく用いることができる。負極集電体としては、導電性を有するものであれば特に限定されるものではないが、銅、ニッケル、アルミニウム、ステンレススチール等を主体とする棒状体、板状体、箔状体、網状体等を使用することができる。 As the binder, for example, fluorine resins such as polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylenetetrafluoroethylene (ETFE), polyethylene, polypropylene, or the like can be preferably used. The negative electrode current collector is not particularly limited as long as it has conductivity, but a rod-like body, a plate-like body, a foil-like body, a net-like body mainly composed of copper, nickel, aluminum, stainless steel or the like. Etc. can be used.
　酸素の酸化還元反応を高率良く行うための触媒として、ＭｎＯ2、Ｆｅ2Ｏ3、ＮｉＯ、ＣｕＯ、Ｐｔ、Ｃｏ等を用いることができる。正極集電体としては、酸素の拡散を高めるため、メッシュ（グリッド）状金属、スポンジ状（発泡）金属、パンチドメタル、エクスパンディドメタル等の多孔体が使用される。金属は、例えば、銅、ニッケル、アルミニウム、ステンレススチール等である。 MnO 2 , Fe 2 O 3 , NiO, CuO, Pt, Co, or the like can be used as a catalyst for performing an oxygen redox reaction with high efficiency. As the positive electrode current collector, a porous body such as a mesh (grid) metal, a sponge (foamed) metal, a punched metal, or an expanded metal is used in order to increase the diffusion of oxygen. Examples of the metal include copper, nickel, aluminum, and stainless steel.
（２）負極
　本発明のリチウム－空気電池における負極は、電気化学的にリチウムイオンを吸蔵・放出できる負極活物質を含む電極である。 (2) Negative Electrode The negative electrode in the lithium-air battery of the present invention is an electrode containing a negative electrode active material capable of electrochemically inserting and extracting lithium ions.
　このような負極活物質としては、リチウム金属、又はリチウム元素を含む合金、金属酸化物、金属窒化物等を挙げることができる。例えば、リチウム元素を有する合金としては、例えばリチウムアルミニウム合金、リチウムスズ合金、リチウム鉛合金、リチウムケイ素合金等を挙げることができる。また、リチウム元素を有する金属酸化物としては、例えばリチウムチタン酸化物（Ｌｉ４Ｔｉ６Ｏ１２等）等を挙げることができる。また、リチウム元素を含有する金属窒化物としては、例えばリチウムコバルト窒化物、リチウム鉄窒化物、リチウムマンガン窒化物等を挙げることができる。また、天然グラファイト（黒鉛）、高配向性グラファイト（Ｈｉｇｈｌｙ　Ｏｒｉｅｎｔｅｄ　Ｐｙｒｏｌｙｔｉｃ　Ｇｒａｐｈｉｔｅ；ＨＯＰＧ）、非晶質炭素等の炭素質材料を用いることもできる。これら負極活物質は、１種を単独で用いてもよく、２種以上を併用してもよい。 Examples of such a negative electrode active material include lithium metal or an alloy containing a lithium element, a metal oxide, and a metal nitride. For example, examples of the alloy having a lithium element include a lithium aluminum alloy, a lithium tin alloy, a lithium lead alloy, and a lithium silicon alloy. The metal oxide having a lithium element can be, for example, lithium titanium oxide (Li 4 Ti 6 O 12, etc.) and the like. Examples of the metal nitride containing a lithium element include lithium cobalt nitride, lithium iron nitride, and lithium manganese nitride. Carbonaceous materials such as natural graphite (graphite), highly oriented graphite (HOPG), and amorphous carbon can also be used. These negative electrode active materials may be used individually by 1 type, and may use 2 or more types together.
　また、本発明における負極層は、負極活物質のみを含有するものであっても良く、負極活物質の他に、導電性材料および結着材の少なくとも一方を含有するものであっても良い。例えば、負極活物質が箔状である場合は、負極活物質のみを含有する負極とすることができる。一方、負極活物質が粉末状である場合は、負極活物質および結着材（バインダ）を有する負極とすることができる。粉末状の負極活物質を用いて負極を形成する方法としては、ドクターブレード法や圧着プレスによる成型方法等を用いることができる。 The negative electrode layer in the present invention may contain only the negative electrode active material, or may contain at least one of a conductive material and a binder in addition to the negative electrode active material. For example, when the negative electrode active material has a foil shape, a negative electrode containing only the negative electrode active material can be obtained. On the other hand, when the negative electrode active material is in a powder form, a negative electrode having a negative electrode active material and a binder (binder) can be obtained. As a method for forming a negative electrode using a powdered negative electrode active material, a doctor blade method, a molding method using a pressure press, or the like can be used.
　導電性材料及び結着剤（バインダ）としては、上記正極と同様のものを用いることができる。 As the conductive material and the binder, the same materials as the positive electrode can be used.
（３）セパレータ
　本発明のリチウム－空気電池において用いられるセパレータとしては、正極層と負極層とを電気的に分離する機能を有するものであれば特に限定されるものではないが、例えばポリエチレン（ＰＥ）、ポリプロピレン（ＰＰ）、ポリエステル、セルロース、ポリアミド等の樹脂からなる多孔質シートや、不織布、ガラス繊維不織布等の不織布等の多孔質絶縁材料等を挙げることができる。 (3) Separator The separator used in the lithium-air battery of the present invention is not particularly limited as long as it has a function of electrically separating the positive electrode layer and the negative electrode layer. For example, polyethylene (PE ), A porous sheet made of a resin such as polypropylene (PP), polyester, cellulose, or polyamide, or a porous insulating material such as a nonwoven fabric such as a nonwoven fabric or a glass fiber nonwoven fabric.
（４）形状等
　本発明のリチウム－空気電池の形状は、正極、負極、及び電解液を収納することができれば特に限定されるものではないが、例えば、円筒型、コイン型、平板型、ラミネート型等を挙げることができる。 (4) Shape, etc. The shape of the lithium-air battery of the present invention is not particularly limited as long as it can accommodate a positive electrode, a negative electrode, and an electrolyte solution. For example, a cylindrical shape, a coin shape, a flat plate shape, a laminate Examples include molds.
　また、電池を収納するケースは、大気開放型の電池ケースであっても良く、密閉型の電池ケースであっても良い。なお、大気開放型の電池ケースである場合は、大気が出入りできる通風口を有し、大気が上記空気極と接触可能な電池ケースである。一方、電池ケースが密閉型電池ケースとしては、密閉型電池ケースに、気体（空気）の供給管および排出管を設けることが好ましい。この場合、供給・排出する気体は、乾燥気体であることが好ましく、なかでも、酸素濃度が高いことが好ましく、純酸素（９９．９９％）であることがより好ましい。また、放電時には酸素濃度を高くし、充電時には酸素濃度を低くすることが好ましい。 In addition, the battery housing case may be an open-air battery case or a sealed battery case. In the case of a battery case that is open to the atmosphere, the battery case has a vent hole through which the atmosphere can enter and exit, and the atmosphere can contact the air electrode. On the other hand, when the battery case is a sealed battery case, it is preferable to provide a gas (air) supply pipe and a discharge pipe in the sealed battery case. In this case, the gas to be supplied / exhausted is preferably a dry gas, in particular, preferably has a high oxygen concentration, and more preferably pure oxygen (99.99%). In addition, it is preferable to increase the oxygen concentration during discharging and decrease the oxygen concentration during charging.
　なお、本発明の電解液及びリチウム－空気電池は、二次電池としての用途に好適ではあるが、一次電池として用いることを除外するものではない。 The electrolyte solution and lithium-air battery of the present invention are suitable for use as a secondary battery, but use of a primary battery is not excluded.
　以下、実施例により本発明をさらに詳細に説明するが、本発明はこれらによって限定されるものではない。 Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.
１．放電容量の評価（充放電試験）
　種々のハロゲン化物塩を含む電解液を用いて、黒鉛電極における単極電位を測定し、充放電挙動の比較を行った。測定は、作用極にグラッシーカーボン電極（直径約１cｍ）、対極及び参照電極に金属リチウムを備え３極式電気化学セルを用いて、充放電測定装置（ＢｉｏＬｏｇｉｃ社製、ＶＭＰ－３）により行った。温度は２５℃である。 1. Evaluation of discharge capacity (charge / discharge test)
Using electrolytes containing various halide salts, the monopolar potential at the graphite electrode was measured and the charge / discharge behavior was compared. The measurement was performed with a charge / discharge measuring device (BioMPic, VMP-3) using a tripolar electrochemical cell equipped with a glassy carbon electrode (diameter: about 1 cm) as a working electrode and metallic lithium as a counter electrode and a reference electrode. . The temperature is 25 ° C.
　図１に、ハロゲン化物塩のカチオン成分をテトラエチルアンモニウム（ＴＥＡ）に固定し、異なるアニオン成分を用いた場合に得られた放電曲線を比較して示す。ここで用いたハロゲン化物塩は、塩化テトラエチルアンモニウム（ＴＥＡ－Ｃｌ）、臭化テトラエチルアンモニウム（ＴＥＡ－Ｂｒ）、及び比較例としてスルホン酸テトラエチルアンモニウム（ＴＥＡ－ｓｕｌｆｏ）であり、それぞれ濃度は、１ｍＭである。溶媒は１，２－ジメトキシエタン（ＤＭＥ）、リチウム塩はＬｉＴＦＳＡである。図１の結果から、ＴＥＡＣｌの場合に約３３０ｍＣとなり、最も放電容量の向上が得られることが分かった。 FIG. 1 shows a comparison of discharge curves obtained when the cation component of a halide salt is fixed to tetraethylammonium (TEA) and different anion components are used. The halide salts used here are tetraethylammonium chloride (TEA-Cl), tetraethylammonium bromide (TEA-Br), and tetraethylammonium sulfonate (TEA-sulfo) as a comparative example, each having a concentration of 1 mM. is there. The solvent is 1,2-dimethoxyethane (DME), and the lithium salt is LiTFSA. From the results of FIG. 1, it was found that the discharge capacity was most improved in the case of TEACl, which was about 330 mC.
　一方、図２は、ハロゲン化物塩のアニオン成分をクロライド（Ｃｌ－）に固定し、異なるカチオン成分を用いた場合に得られた放電曲線を比較して示す。ここで用いたハロゲン化物塩は、塩化テトラエチルアンモニウム（ＴＥＡ－Ｃｌ）、塩化テトラメチルアンモニウム（ＴＭＡ－Ｃｌ）、塩化テトラアミルアンモニウム（ＴＡＡ－Ｃｌ）、塩化Ｎ－ブチルピリジニウム（ＢＰ－Ｃｌ）、塩化Ｎ－メチル－Ｎ－ブチルピロリジニウム（ＭＢＰ－Ｃｌ）であり、それぞれ濃度は１ｍＭである。溶媒は１，２－ジメトキシエタン（ＤＭＥ）、リチウム塩はＬｉＴＦＳＡである。図２の結果から、ＴＥＡ－Ｃｌ場合に最も放電容量の向上が得られることが分かった（約３３０ｍＣ）。ＢＰ－Ｃｌ（約１６０ｍＣ）とＭＢＰ－Ｃｌ（約１５０ｍＣ）でも良好な放電容量の向上が見られたが、ＴＡＡ－Ｃｌでは放電容量は変化しなかった。 On the other hand, FIG. 2 shows a comparison of discharge curves obtained when the anion component of the halide salt is fixed to chloride (Cl − ) and different cation components are used. The halide salts used here are tetraethylammonium chloride (TEA-Cl), tetramethylammonium chloride (TMA-Cl), tetraamylammonium chloride (TAA-Cl), N-butylpyridinium chloride (BP-Cl), chloride N-methyl-N-butylpyrrolidinium (MBP-Cl), each having a concentration of 1 mM. The solvent is 1,2-dimethoxyethane (DME), and the lithium salt is LiTFSA. From the results of FIG. 2, it was found that the discharge capacity was most improved in the case of TEA-Cl (about 330 mC). BP-Cl (about 160 mC) and MBP-Cl (about 150 mC) also showed a good improvement in discharge capacity, but TAA-Cl did not change the discharge capacity.
　次いで、最も顕著な放電容量の向上が観測されたＴＥＡ－Ｃｌについて、濃度依存性を測定した結果を図３に示す。溶媒は１，２－ジメトキシエタン（ＤＭＥ）、リチウム塩はＬｉＴＦＳＡである。図３より、０．５ｍＭで放電容量の向上が得られ、１．０ｍＭで最も大きな向上が得られることが分かった。 Next, FIG. 3 shows the result of measuring the concentration dependence of TEA-Cl in which the most remarkable improvement in discharge capacity was observed. The solvent is 1,2-dimethoxyethane (DME), and the lithium salt is LiTFSA. From FIG. 3, it was found that the discharge capacity was improved at 0.5 mM, and the greatest improvement was obtained at 1.0 mM.
２．充放電時の過電圧の検討
　ＴＥＡ－Ｃｌ添加時及び非添加時における充放電曲線を図４に示す。溶媒はテトラエチルグリコールジメチルエーテル（ＴＥＧＤＭＥ）、リチウム塩はＬｉＰＦ６である。図４に示すように、ＴＥＡ－Ｃｌによって、充電及び放電のいずれにおいても過電圧の減少が得られた。これは、充電時においては、ＴＥＡカチオンによって正極表面に存在するＬｉ－Ｏ結合が弱められるためと考えられ、一方、放電時においては、Ｃｌ－アニオンがＬｉ＋イオンの脱溶媒和に作用しているためであると考えられる。 2. Examination of overvoltage during charging / discharging FIG. 4 shows charging / discharging curves with and without addition of TEA-Cl. The solvent tetraethyl glycol dimethyl ether (TEGDME), the lithium salt is LiPF 6. As shown in FIG. 4, the TEA-Cl reduced the overvoltage in both charging and discharging. This is thought to be because the Li—O bond present on the positive electrode surface is weakened by the TEA cation during charging, while the Cl − anion acts on the desolvation of Li + ions during discharge. It is thought that this is because.
３．インピーダンスの比較
　図５に示すように、ＴＥＡ－Ｃｌ添加時及び非添加時について、ナイキストプッロト（Ｎｙｑｕｉｓｔ　ｐｌｏｔ）によりＴＥＡ－Ｃｌ添加時及び非添加時におけるインピーダンスの比較を行ったところ、ＴＥＡ－Ｃｌ添加時にイオンピーダンスの減少が見られたことから、上記放電容量の向上は、正極表面に堆積するＬｉ２Ｏ２の電子伝導性がＴＥＡ－Ｃｌによって増大されるためであることが示唆される。 3. Impedance comparison As shown in FIG. 5, when TEA-Cl was added and when it was not added, impedance was compared when TEA-Cl was added and when TEA-Cl was added using Nyquist plot. The decrease in ion impedance at the time of addition indicates that the improvement in the discharge capacity is due to the fact that the electronic conductivity of Li 2 O 2 deposited on the positive electrode surface is increased by TEA-Cl.
　以上の結果は、ハロゲン化物塩を電解液に添加することによって、正極表面に堆積するリチウム酸化物の電子伝導性が向上し、それによって放電容量の向上が得られることを実証するものである。従って、本発明の電解液がリチウム－空気電池における好適な電解液として機能し得ることを実証するものである。 The above results demonstrate that the addition of a halide salt to the electrolytic solution improves the electronic conductivity of the lithium oxide deposited on the positive electrode surface, thereby improving the discharge capacity. Therefore, it is demonstrated that the electrolytic solution of the present invention can function as a suitable electrolytic solution in a lithium-air battery.
以上、本発明の具体的態様を詳細に説明したが、これらは例示に過ぎず、特許請求の範囲を限定するものではない。また、特許請求の範囲に記載の発明には、以上の例示した具体的態様を種々変更したものが含まれ得る。 Although specific embodiments of the present invention have been described in detail above, these are merely examples and do not limit the scope of the claims. In addition, the invention described in the claims may include various modifications of the specific embodiments described above.

Claims (11)

  1. 非水溶媒とハロゲン化物塩とを含むリチウム－空気電池用電解液。 An electrolyte for a lithium-air battery comprising a nonaqueous solvent and a halide salt.
  2. 前記ハロゲン化物塩が、塩化物塩である、請求項１に記載の電解液。 The electrolytic solution according to claim 1, wherein the halide salt is a chloride salt.
  3. 前記ハロゲン化物塩を構成するカチオンが、テトラ（Ｃ１～Ｃ4）アンモニウム、Ｎ－アルキルピリジニウム、及びＮ，Ｎ－ジアルキルピロリジニウムよりなる群から選択される、請求項１に記載の電解液。 The electrolytic solution according to claim 1, wherein the cation constituting the halide salt is selected from the group consisting of tetra (C 1 -C 4 ) ammonium, N-alkylpyridinium, and N, N-dialkylpyrrolidinium. .
  4. 前記ハロゲン化物塩が、塩化テトラエチルアンモニウムである、請求項１に記載の電解液。 The electrolytic solution according to claim 1, wherein the halide salt is tetraethylammonium chloride.
  5. 前記ハロゲン化物塩の濃度が、０．５～５ｍＭである、請求項１～４のいずれか１項に記載の電解液。 The electrolyte solution according to any one of claims 1 to 4, wherein a concentration of the halide salt is 0.5 to 5 mM.
  6. 前記ハロゲン化物塩の濃度が、１～３ｍＭである、請求項１～４のいずれか１項に記載の電解液。 The electrolytic solution according to any one of claims 1 to 4, wherein the concentration of the halide salt is 1 to 3 mM.
  7. 前記非水溶媒が、非プロトン性溶媒である、請求項１～６のいずれか１項に記載の電解液。 The electrolytic solution according to any one of claims 1 to 6, wherein the non-aqueous solvent is an aprotic solvent.
  8. 前記非水溶媒が、１，２－ジメトキシエタン又はテトラエチルグリコールジメチルエーテルである、請求項１～６のいずれか１項に記載の電解液。 The electrolytic solution according to any one of claims 1 to 6, wherein the non-aqueous solvent is 1,2-dimethoxyethane or tetraethyl glycol dimethyl ether.
  9. 酸素を正極活物質とする正極と、
    リチウムイオンを吸蔵及び放出可能な負極活物質を含む負極と、
    請求項１～８のいずれか１項に記載の電解液とを有するリチウム－空気電池。     A positive electrode using oxygen as a positive electrode active material;
    A negative electrode including a negative electrode active material capable of inserting and extracting lithium ions;
    A lithium-air battery comprising the electrolyte solution according to any one of claims 1 to 8.
  10. 前記正極が酸素の酸化還元触媒を含む、請求項９に記載のリチウム－空気電池。 The lithium-air battery of claim 9, wherein the positive electrode includes an oxygen redox catalyst.
  11. 前記負極活物質が、金属リチウム、リチウム合金、又はリチウム金属酸化物である、請求項９に記載のリチウム－空気電池。 The lithium-air battery according to claim 9, wherein the negative electrode active material is metallic lithium, a lithium alloy, or a lithium metal oxide.
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JPH05258782A (en) * 1992-03-13 1993-10-08 Hitachi Ltd Air cell
JPH06310182A (en) * 1993-04-27 1994-11-04 Shigeyuki Yasuda Electrochemical generating device
JP2011108388A (en) * 2009-11-13 2011-06-02 Nippon Telegr & Teleph Corp <Ntt> Lithium air battery
WO2011074325A1 (en) * 2009-12-16 2011-06-23 トヨタ自動車株式会社 Normal-temperature molten salt, electrode, cell, agent for preventing charge-up, and method for observing sample
JP2013527567A (en) * 2010-04-23 2013-06-27 リオクス パワー インコーポレイテッド Soluble oxygen evolution catalyst for rechargeable metal-air batteries

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05258782A (en) * 1992-03-13 1993-10-08 Hitachi Ltd Air cell
JPH06310182A (en) * 1993-04-27 1994-11-04 Shigeyuki Yasuda Electrochemical generating device
JP2011108388A (en) * 2009-11-13 2011-06-02 Nippon Telegr & Teleph Corp <Ntt> Lithium air battery
WO2011074325A1 (en) * 2009-12-16 2011-06-23 トヨタ自動車株式会社 Normal-temperature molten salt, electrode, cell, agent for preventing charge-up, and method for observing sample
JP2013527567A (en) * 2010-04-23 2013-06-27 リオクス パワー インコーポレイテッド Soluble oxygen evolution catalyst for rechargeable metal-air batteries

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