Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/36—Selection of substances as active materials, active masses, active liquids
  • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
  • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/0021—Reactive sputtering or evaporation
  • C23C14/0036—Reactive sputtering
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
  • C23C14/08—Oxides
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
  • C23C14/34—Sputtering
  • C23C14/3407—Cathode assembly for sputtering apparatus, e.g. Target
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
  • C23C14/34—Sputtering
  • C23C14/3492—Variation of parameters during sputtering
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/04—Processes of manufacture in general
  • H01M4/0402—Methods of deposition of the material
  • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/04—Processes of manufacture in general
  • H01M4/0402—Methods of deposition of the material
  • H01M4/0421—Methods of deposition of the material involving vapour deposition
  • H01M4/0423—Physical vapour deposition
  • H01M4/0426—Sputtering
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
  • H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
  • H01M4/139—Processes of manufacture
  • H01M4/1397—Processes of manufacture of electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/36—Selection of substances as active materials, active masses, active liquids
  • H01M4/362—Composites
  • H01M4/366—Composites as layered products
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M2004/021—Physical characteristics, e.g. porosity, surface area
• • 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
• • 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
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/49002—Electrical device making
  • Y10T29/49108—Electric battery cell making
• • 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
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/49002—Electrical device making
  • Y10T29/49108—Electric battery cell making
  • Y10T29/49115—Electric battery cell making including coating or impregnating

Definitions

• the present invention relates to a power storage device and a manufacturing method thereof.
• a lithium ion battery formed using a metal oxide containing lithium, such as lithium iron phosphate has high capacitance and high safety.
• LiFeP0 4 of an olivine structure that contains a divalent iron ion (hereinafter referred to as Fe(II)) and Li 3 Fe 2 (P0 4 ) 3 of a NASICON structure that contains a trivalent iron ion (hereinafter referred to as Fe(III)).
• LiFeP0 4 of an olivine structure that contains Fe(II) is an excellent positive electrode material which has high capacitance and a high discharge potential (see Patent Document 1).
• a thin-film battery whose electrode is formed by a technique for forming a thin film has characteristics such as excellent flexibility and high durability and has attracted attention in recent years.
• lithium iron phosphate formed by a sputtering method has an amorphous structure.
• lithium iron phosphate having an amorphous structure can be changed into lithium iron phosphate having a crystalline structure, such as LiFeP0 4 having an olivine structure or Li 3 Fe 2 (P0 4 )3 having a NASICON structure.
• Lithium iron phosphate having an amorphous structure and lithium iron phosphate having a crystalline structure can be used as an active material of a positive electrode.
• Patent Document 1 Japanese Published Patent Application No. 2008-257894
• Patent Document 2 Japanese Translation of PCT International Application No. 2000-509193
• Fe(II) is readily oxidized to Fe(III) by oxygen in an atmosphere.
• a step of performing heat treatment on lithium iron phosphate having an amorphous structure which is formed by a technique for forming a thin film residual oxygen in a heat treatment atmosphere oxidizes Fe(II) and the lithium iron phosphate having an amorphous structure is changed into Li 3 Fe 2 (P0 4 ) 3 having a NASICON structure that contains Fe(III), which is problematic.
• An object of one embodiment of the present invention is to provide a power storage device with favorable battery characteristics and a manufacturing method of the power storage device.
• one embodiment of the present invention is a power storage device including at least a positive electrode and a negative electrode which is provided so as to face the positive electrode with an electrolyte provided therebetween.
• the positive electrode includes a collector and a film containing an active material which is provided over the collector.
• the film containing the active material contains Li e Fe/P g O / , satisfying relations 3.5 ⁇ h/g ⁇ 4.5, 0.6 ⁇ g/f ⁇ 1.1, and 0 ⁇ e/f ⁇ 1.3 and U a Fe b ? c O d satisfying relations 3.5 ⁇ die ⁇ 4.5, 0.6 ⁇ c/b ⁇ 1.8, and 0.7 ⁇ alb ⁇ 2.8.
• the film containing the active material contains the Li a Fe f eP c O d satisfying the relations 3.5 ⁇ die ⁇ 4.5, 0.6 ⁇ c/b ⁇ 1.8, and 0.7 ⁇ alb ⁇ 2.8 in a region which is in contact with the electrolyte.
• the negative electrode may contain a material which does not include lithium.
• lithium iron phosphate containing Fe(II) is formed on a surface which is in contact with the collector and lithium iron phosphate containing Fe(III) is formed on a surface which is in contact with the electrolyte.
• a typical example of lithium iron phosphate containing Fe(II) is LiFeP0 4 .
• a typical example of lithium iron phosphate containing Fe(III) is Li 3 Fe 2 (P0 4 ) 3 .
• Each of the lithium iron phosphate containing Fe(II) and the lithium iron phosphate containing Fe(IIl) may have an amorphous structure.
• the lithium iron phosphate containing Fe(II) may be LiFeP0 4 having an olivine structure.
• the lithium iron phosphate containing Fe(III) has a crystalline structure
• the lithium iron phosphate containing Fe(III) may be Li 3 Fe 2 (P0 4 ) 3 having a NASICON structure.
• the active material of the positive electrode which has the above structure may be formed to have a stacked-layer structure including two or more layers.
• the positive electrode has a stacked-layer structure including the collector, a film containing an active material (A) formed over the collector, and a film containing an active material (B) formed over the film containing the active material (A).
• the active material (A) contains lithium iron phosphate containing Fe(II) and the active material (B) is lithium iron phosphate containing (III).
• the film containing the active material (B) is positioned on a surface which is in contact with the electrolyte.
• the film containing the active material (B) is positioned between the film containing the active material (A) and the electrolyte.
• the active material (A) contains at least lithium iron phosphate containing Fe(II).
• the active material (A) may contain lithium iron phosphate containing Fe(ll) and lithium iron phosphate containing Fe(III).
• the lithium iron phosphate containing Fe(II) which is contained in the active material (A) is the Li e Fe/P g O / , satisfying the relations 3.5 ⁇ h/g ⁇ 4.5, 0.6 ⁇ g/f ⁇ 1.1, and 0 ⁇ e/f ⁇ 1.3.
• the lithium iron phosphate containing Fe(III) which is the active material (B) is the Li a Fe ⁇ P c C satisfying the relations 3.5 ⁇ die ⁇ 4.5, 0.6 ⁇ c/b ⁇ 1.8, and 0.7 ⁇ alb ⁇ 2.8.
• each of the film containing the active material (A) and the film containing the active material (B) may have an amorphous structure.
• the active material (A) when the active material (A) has a crystalline structure, the active material (A) may be LiFeP0 4 having an olivine structure. Further, when the active material (B) has a crystalline structure, the active material (B) may be Li 3 Fe 2 (P0 4 ) 3 having a NASICON structure.
• One embodiment of the present invention is a method for manufacturing a power storage device including a positive electrode and a negative electrode which is provided so as to face the positive electrode with an electrolyte provided therebetween.
• the positive electrode is formed by forming a film containing an active material (A) over a collector and then forming a film containing an active material (B) over the film containing the active material (A).
• the active material (A) contains lithium iron phosphate containing Fe(II) and the active material (B) is lithium iron phosphate containing Fe(III).
• One embodiment of the present invention is a method for manufacturing a power storage device which includes a positive electrode and a negative electrode which is provided so as to face the positive electrode with an electrolyte provided therebetween.
• the positive electrode is formed by a method including the following steps: a step of forming a film containing an active material (A) over a collector by a sputtering method; and a step of forming a film containing an active material (B) over the film containing the active material (A) by a sputtering method.
• the two stacked films are formed with the use of the same target.
• the active material (A) contains lithium iron phosphate containing Fe(II) and the active material (B) is lithium iron phosphate containing Fe(III).
• the target used in the sputtering method is a material which contains, as a main component, lithium iron phosphate containing Fe(II).
• Oxygen partial pressure in a deposition atmosphere at the time of formation of the film containing the active material (A) by a sputtering method is greater than or equal to 0 % and less than or equal to 0.01 %; oxygen partial pressure in a deposition atmosphere at the time of formation of the film containing the active material (B) is 0.1 % or more, preferably 1 % or more.
• FIG. 1 is a cross-sectional view illustrating a mode of a structure of a power storage device
• FIGS. 2A to 2C are cross-sectional views illustrating a mode of a structure of a power storage device.
• FIG. 1 illustrates an example of a structure of a positive electrode used in a power storage device.
• a positive electrode 101 includes a collector 103, a film 105 containing an active material (A) which is formed over the collector 103, and a film 107 containing an active material (B) which is formed over the film 105 containing the active material (A).
• the active material (A) at least lithium iron phosphate containing Fe(II) is used.
• the active material (B) is lithium iron phosphate containing Fe(III). Note that another structure is acceptable as long as the active material (A) contains at least lithium iron phosphate containing Fe(II).
• the active material (A) may contain lithium iron phosphate containing Fe(II) and lithium iron phosphate containing Fe(III). In this embodiment, a case where lithium iron phosphate containing Fe(II) is used as the active material (A) is described.
• the lithium iron phosphate (Li e Fe/PgO 3 ⁇ 4 ) containing Fe(II) which is contained in the active material (A) satisfies the relations 3.5 ⁇ h/g ⁇ 4.5, 0.6 ⁇ glf ⁇ 1.1, and 0 ⁇ elf ⁇ 1.3.
• the lithium iron phosphate (Li a FetP c Or f ) containing Fe(III) which is the active material (B) satisfies the relations 3.5 ⁇ die ⁇ 4.5, 0.6 ⁇ elb ⁇ 1.8, and 0.7 ⁇ alb ⁇ 2.8.
• LiFeP0 4 having an amorphous structure may be employed.
• the LiFeP0 4 having a crystalline structure is employed, the LiFeP0 4 has an olivine structure.
• Li 3 Fe 2 (P0 4 ) 3 having an amorphous structure may be employed.
• the Li 3 Fe 2 (P0 4 ) 3 has a NASICON structure.
• Each of the film 105 containing the active material (A) and the film 107 containing the active material (B) can be a thin film of the active material, a film in which particles of the active material are dispersed, or an aggregate of particles of the active material.
• the thickness of the film 105 containing the active material (A) is preferably greater than or equal to 50 nm and less than or equal to 30 ⁇ . Further, the thickness of the film 107 containing the active material (B) is preferably greater than or equal to 5 nm and less than or equal to 1 ⁇ . When the thickness of the film 107 containing the active material (B) is half or less the thickness of the film 105 containing the active material (A), a reduction of discharge capacitance can be prevented.
• the diameter of the particle is preferably greater than or equal to 5 nm and less than or equal to 200 nm.
• the film 105 containing the active material (A) and the film 107 containing the active material (B) are formed by a sputtering method.
• a rare gas such as helium, neon, argon, xenon, or krypton
• a target which contains, as a main component, lithium iron phosphate containing Fe(II) is sputtered, so that the film 105 containing the active material (A) is formed over the collector 103.
• oxygen partial pressure in a treatment chamber is greater than or equal to 0 % and less than or equal to 0.01 , whereby lithium iron phosphate containing Fe(II) can be formed as the film 105 containing the active material (A).
• oxygen partial pressure in the treatment chamber is 0.1 % or more, preferably 1 % or more, whereby lithium iron phosphate containing Fe(III) can be formed as the film 107 containing the active material (B).
• the film 105 containing the active material (A) and the film 107 containing the active material (B) can be sequentially formed in one chamber, which contributes to simplification of the process. Further, when the films are sequentially formed in one chamber, contamination of an interface can be prevented and the film containing the active material can have favorable electrical characteristics. In addition, when the film 107 containing the active material (B) which is stable against oxidation and is not easily oxidized is formed on a surface of the positive electrode, natural oxidation of the lithium iron phosphate containing Fe(II) in the air atmosphere can be suppressed.
• a material which contains lithium iron phosphate containing Fe(II) is used as a target.
• the film 105 containing the active material (A) and the film 107 containing the active material (B) may be subjected to heat treatment so as to have crystalline structures.
• the lithium iron phosphate containing Fe(III) which is stable against oxidation and is not easily oxidized is formed on a surface of the lithium iron phosphate containing Fe(II) which is an active material of the positive electrode, whereby surface oxidation due to residual oxygen in a heat treatment atmosphere can be prevented and a stable film can be obtained.
• a material of the collector 103 although not particularly limited, a material with high conductivity, such as aluminum or titanium, can be used.
• FIGS. 2A to 2C illustrate an example of a structure of a power storage device.
• the power storage device includes the positive electrode 101 and a negative electrode 203 provided so as to face the positive electrode 101 with an electrolyte 201 provided therebetween.
• a separator 205 is provided between the positive electrode 101 and the negative electrode 203.
• the electrolyte 201 has a function of transporting lithium ions.
• a material of the electrolyte 201 can be liquid or solid.
• the electrolyte When the electrolyte is liquid, the electrolyte includes a solvent and a solute
• the solute (salt) can contain one or more kinds of light metal salt (e.g., lithium salt).
• the solute (salt) can be LiPF 6 , LiBF 4 , Li(CF 3 S0 2 ) 2 N (LiTFSA), or the like.
• Li 3 P0 4 When the electrolyte is solid, for example, Li 3 P0 4 ; (x, y, and z are positive real numbers) which is formed by mixing Li 3 P0 4 with nitrogen; Li 2 S-SiS 2 ; Li 2 S-P 2 S 5 ; Li 2 S-B?S 3 ; or the like can be used. Alternatively, any of these salts which are doped with Lil can be used.
• the separator 205 prevents contact between the positive electrode 101 and the negative electrode 203 and has a function of allowing transport of lithium ions.
• a material of the separator 205 include paper, nonwoven fabric, a glass fiber, a polymeric material such as a nylon (a polyamide), vinylon (a poly(vinyl alcohol)-based fiber), a polyolefin such as polypropylene, a polyester, an acrylic resin, or a polyurethane, and the like. Note that a material which does not dissolve in the electrolyte should be selected. Note that when a solid electrolyte is employed as the electrolyte 201, the separator 205 can be omitted.
• the negative electrode 203 includes a collector 209 and a film 207 containing an active material.
• a material with high conductivity such as platinum, aluminum, copper, or titanium
• a material of an active material contained in the film 207 although not particularly limited, a carbon material (e.g., graphite), silicon, or the like can be used.
• the film 207 containing the active material, which is included in the negative electrode is formed using graphite.
• the positive electrode 101 includes the following components which are illustrated in FIG. 1: the film 105 containing the active material (A) which is formed over the collector 103; and the film 107 containing the active material (B) which is formed over the film 105 containing the active material (A). [0048]
• a power source 211 is connected between the positive electrode 101 and the negative electrode 203 as illustrated in FIG. 2B, whereby charging can be performed.
• a lithium ion in the film 105 containing the active material (A), which is included in the positive electrode 101 is extracted from the film 105, and an electron 215 is generated.
• the lithium ion 213 is transported to the negative electrode 203 through the electrolyte 201.
• the electron 215 moves to the negative electrode 203 through the power source 211.
• the lithium ion 213 receives the electron 215 in the negative electrode 203 and is inserted into the negative electrode 203 as lithium.
• a load 217 is connected between the positive electrode 101 and the negative electrode 203 as illustrated in FIG. 2C, whereby discharging can be performed.
• the lithium inserted into the negative electrode 203 through the charging is ionized, the lithium ion 213 is extracted from the negative electrode 203, and the electron 215 is generated.
• the lithium ion 213 is transported to the positive electrode 101 through the electrolyte 201.
• the electron 215 moves to the positive electrode 101 through the load 217.
• the lithium ion 213 is transported through the layer 107 containing the active material (B) and trapped in the film 105 containing the active material (A).
• Fe(III) formed in charging undergoes reduction by receiving the electron 215, resulting in Fe(II).
• the film 107 containing the active material (B) is formed over the film 105 containing the active material (A).
• the active material (A) contains lithium iron phosphate containing Fe(II) and the active material (B) is lithium iron phosphate containing Fe(III) which is stable against oxidation; thus, an electrode with stable characteristics can be formed and the battery characteristics of the power storage device are improved.

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• 2011
  • 2011-02-18 WO PCT/JP2011/054210 patent/WO2011118328A1/en not_active Ceased
  • 2011-02-18 CN CN201180016317.9A patent/CN102823036B/zh not_active Expired - Fee Related
  • 2011-03-16 US US13/049,407 patent/US8841027B2/en active Active
  • 2011-03-22 JP JP2011062194A patent/JP5785407B2/ja not_active Expired - Fee Related
  • 2011-03-23 TW TW100109871A patent/TWI470863B/zh not_active IP Right Cessation

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