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
  • H01M4/64—Carriers or collectors
  • H01M4/66—Selection of materials
  • H01M4/661—Metal or alloys, e.g. alloy coatings
• • 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
  • H01M4/64—Carriers or collectors
  • H01M4/66—Selection of materials
  • H01M4/664—Ceramic materials
• • 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
  • H01M4/64—Carriers or collectors
  • H01M4/66—Selection of materials
  • H01M4/663—Selection of materials containing carbon or carbonaceous materials as conductive part, e.g. graphite, carbon fibres
• • 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

• Molten salt electrolytes are considered safer than traditional organic electrolytes, especially for automobile applications.
• corrosion of the electron collector severely affects the performance of batteries having a molten salt electrolyte, degrading cycling ability and high rate performance.
• Corrosion results from the oxidation of the molten salt electrolyte on the surface of the metal collector, typically aluminum (Al) or iron (Fe), during charge or discharge.
• Al aluminum
• Fe iron
• a battery comprises a first electrode, a second electrode, an electrolyte such as a molten salt electrolyte, and an electron collector associated with the first electrode.
• the electron collector has a surface treatment, the surface treatment reducing corrosion of the electron collector by the molten salt electrolyte.
• the surface treatment may be a protection layer, such as a protection layer comprising an oxide, a nitride, a sulfide, a phosphide, and/or a carbide.
• the protection layer can be a metal film having a substantially greater corrosion resistance than the electron collector, such as tungsten, or a surface alloy formed on the material of the electron collector, such as an aluminum alloy formed on an aluminum electron collector.
• the protection layer may include one or more materials selected from a group of materials consisting of metals, metal alloys, metal carbides, metal oxides, and metal phosphides, examples of which include tungsten, titanium carbide, tantalum carbide, aluminum oxide, titanium oxide, nickel oxide, copper phosphide, nickel phosphide, iron phosphide, and iron nitride.
• the surface treatment may also be an anodization of the electron collector, or a treatment that substantially lowers the surface potential of the electron collector.
• the electron collector is substantially aluminum metal
• the protection layer is an aluminum alloy having a lower aluminum content than the electron collector.
• the battery is a lithium-ion battery having a molten salt electrolyte; however the improved electron collectors described herein may be used in other battery technologies, for example those based on other cationic species.
• An improved battery includes an electron collector having a protection layer on the surface of the electron collector.
• the electron collector is an aluminum foil
• the protection layer comprises a material, such as an electron- conducting material, selected from the group consisting of: oxides having at least one element which belongs to group 2 to 14 in the third or subsequent period of the periodic table as a constituent element thereof; carbides having at least one element which belongs to group 2 to 14 in the third or subsequent period of the periodic table as a constituent element thereof; nitrides having at least one element which belongs to group 2 to 14 in the third or subsequent period of the periodic table as a constituent element thereof; and tungsten.
• examples include tin oxide, titanium oxide indium-tin oxide, tantalum oxide, tungsten oxide, chromium oxide, and thallium oxide.
• Protection layers may also include magnesium oxide, barium titanate, titanium oxide, zirconium oxide, aluminum oxide, and silica, which have excellent electrochemical stability.
• Other example protection layers include oxides, carbides, nitrides of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and W, and combinations of materials discussed herein (such as oxynitrides, oxycarbides, mixed metal compounds (oxides, nitrides, and carbides), and the like.
• FIG. 1 shows a structure of a battery having electron collectors, each electron collector having a protection layer.
• a protection layer comprising one or more electron conducting materials can be used in a protection layer disposed on a surface which would otherwise be in contact with a molten salt, so as to prevent or slow corrosion of the surface.
• the surface of an Al electron collector within a molten salt Li-ion battery can support a protection layer comprising one or more electron conducting materials so as to substantially prevent corrosion of the Al surface by the molten salt electrolyte.
• Improved electron conductive materials have been developed for use as protection layers. Electron conductive materials for use in protection layers used within a Li-ion battery with a molten salt electrolyte are described.
• protection layers can reduce or eliminate decomposition of the surface on which they are disposed, for example, the surface of an electron collector.
• the electron conductive materials may have properties including: high electron conductivity, non-reactivity with molten salts, particulate form (such as nanoparticles, having an average diameter in the range 0.5 nm — 1 micron), and high density.
• An electrically conductive material typically may have an electrical conductivity of at least lxlO -2 S/cm, more preferably at least lxlO 3 S/cm, in the ordinary state of use and operating temperature of the battery. Protection layers are described which can reduce or eliminate the problem of corrosion of the electron collector by molten salt electrolytes within a lithium ion battery.
• Electron collectors may include aluminum, iron, other metal, or other electrically conducting material.
• Approaches include physical coating of the electron collector by electron conducting materials, chemical coating (for example, decreasing the Al surface potential by oxidation additives), and/or providing promoted Al with an Al-alloy thin film.
• Novel methods and materials are described for providing a protection layer on a component surface, (such as an electrode collector, negative electrode, positive electrode, other electrical component, or housing component) in contact with a molten salt electrolyte, so as to slow or prevent corrosion of the component surface.
• Figure 1 shows a Li-ion battery structure, showing electron collectors 10 and 22, negative electrode layer (anode layer) 12, electrolyte at 14 and 18, separator 16, and positive electrode 20.
• the positive electrode includes a cathode electroactive material, electron conductive material, and binder material
• the negative electrode includes anode electroactive material, electron conductive material, and binder material.
• the electron collectors are each covered by a protection layer, shown at 24 and 26. If the electrolyte is a molten salt electrolyte, and the electron collectors each comprise an aluminum foil (often the case in a conventional Li-ion battery), the electrolyte decomposes on the aluminum foil. In certain examples described herein, the provision of a protection layer to an electrolyte is a molten salt electrolyte, and the electron collectors each comprise an aluminum foil (often the case in a conventional Li-ion battery), the electrolyte decomposes on the aluminum foil. In certain examples described herein, the provision of a protection layer to an
• Al electron collector in a molten salt Li-ion battery is described.
• the provision of a protection layer on the surface of the Al electron collector can substantially prevent corrosion of the Al electron collector by a molten salt electrolyte, and can improve cyclability of a molten salt Li-ion battery.
• the invention is not limited to the provision of protection layers to Al electron collectors. Electron collectors formed from other materials can be provided with a protection layer according to the present invention. Protection layers, of the same or different composition, can also be applied to the negative electrode and/or positive electrode, or to other battery component surfaces which would otherwise be in contact with a molten salt.
• Electron collectors may comprise aluminum, iron, another metal, or other electrically conducting materials.
• Approaches to protection layer formation include physical coating of the electron collector by electron conducting materials, chemical coating (for example, decreasing the Al surface potential using oxidation additives), and/or providing promoted Al with an Al-alloy thin film.
• a protection layer is provided to the electron collector, for example, by a physical coating method. The protection layer transmits electrons to or from the electron collector.
• the protection layer may include an electrically conductive polymer.
• Electron collectors may be coated with one or more protection layers.
• Example protection layers comprise tungsten (W), platinum (Pt), titanium carbide (TiC), tantalum carbide (TaC), tungsten carbide (WC), titanium oxide (for example, Ti 4 O 7 ), copper phosphide (Cu 2 P 3 ), nickel phosphide (Ni 2 P 3 ), iron phosphide (FeP), and the like.
• W tungsten
• platinum platinum
• TiC titanium carbide
• TaC tantalum carbide
• WC tungsten carbide
• titanium oxide for example, Ti 4 O 7
• copper phosphide Cu 2 P 3
• Ni 2 P 3 nickel phosphide
• FeP iron phosphide
• the chemical formulas given are exemplary.
• titanium oxide also includes TiO 2 , and non-stoichiometric compounds of titanium and oxygen, and likewise with other compounds mentioned.
• An improved electron collector may comprise aluminum, or other metal susceptible to corrosion by a molten salt electrolyte, and a protection layer on the surface of the aluminum (or other electron collector material) acting to reduce corrosion of the electron collector.
• an improved battery includes a molten salt electrolyte, electrodes (positive electrode and negative electrode), and electron collectors, which have a surface treatment which reduces corrosion of the electron collector by the molten salt electrolyte.
• the surface treatment to the electron collector may include chemical and/or physical deposition processes, chemical bath, anodization technique, or other process or combination of processes.
• Electron collectors can include aluminum, copper, iron, steel (such as stainless steel), nickel, zinc, conducting polymers, metalized polymers (such as metalized Mylar), and the like.
• a protection layer may include a polymer, such as a polyalklyene oxide (such as polyethylene oxide), conducting polymer (such as (such as polyethylene oxide), conducting polymer (such as a polypyrrole, polyaniline, polythiophene, polyvinylidene fluoride, derivatives thereof, or other electrically conducting polymer), polycarbonate, PVDF, polymer complex, and the like.
• a polymer such as a polyalklyene oxide (such as polyethylene oxide), conducting polymer (such as (such as polyethylene oxide), conducting polymer (such as a polypyrrole, polyaniline, polythiophene, polyvinylidene fluoride, derivatives thereof, or other electrically conducting polymer), polycarbonate, PVDF, polymer complex, and the like.
• a protection layer applied to an electron collector may a material such as a metal or metal alloy, boride, carbide, nitride, oxide, fluoride, other halide, silicide, phosphide, sulfide (or other chalcogenide).
• a metal or metal alloy such as a metal or metal alloy, boride, carbide, nitride, oxide, fluoride, other halide, silicide, phosphide, sulfide (or other chalcogenide).
• metal compounds including transition metal compounds
• metal borides such as: metal borides, metal carbides, metal nitrides, metal oxides, metal fluorides (and other metal halides), metal suicides, metal phosphides, and metal chalcogenides.
• Compounds may be mixed metal compounds, for example including two or more metal species.
• Protection layers may also comprise an oxynitride, oxycarbide, or other compound including one or more atom from the group C, N, O, Si, P, and S. Protection layers may comprise a layer of solid electrolyte, glassy material, crystalline material, amorphous material, elastomer, sol-gel, and the like.
• a protection layer may include a polymer, such as a polyalklyene oxide (such as polyethylene oxide), conducting polymer (such as a polypyrrole), polycarbonate, PVDF, polymer complex (e.g. with a lithium compound), and the like. Certain compounds may fall into one or more categories discussed herein. Iron-based protection layers can provide corrosion resistance to molten salts containing alkali oxides.
• the protection layer can also comprise a nickel-containing alloy, such as described in U.S. Pat. No. 6,224,824 to Zhang.
• An iron (or iron-containing) electron collector can be nitrided to reduce corrosion by the electrolyte, so that the protection layer includes iron nitride.
• An electron collector, such as an iron electron collector can be surface treated using an oxidizing bath to reduce surface corrosion, for example using an oxidizing bath such as described in U.S. Patent 4,448,611 to Grellet et al. Protection layers may comprise copper, silver, or copper-silver alloys, for example as described in U.S. Pat. No.
• U.S. Pat. No. 5,591,544 to Fauteux et al. describes methods of reducing the interfacial impedance of an aluminum electron collector, including coating with a primer material. Such materials may be used in place of, or in addition to, other techniques to reduce electron collector corrosion.
• the electron collector may be coated with a metal film, for example an electroplated metal film, for example using the electroplating techniques described in U.S. Pat. No. 5,518,839 to Olsen.
• Nickel plated, or other metal or alloy plated electron collectors may be used in a Li-ion battery having a molten salt electrolyte.
• one or more oxidation additives are disposed on the surface of the electron collector, decreasing the surface potential of the electron collector, and reducing its corrosion by the molten salt electrolyte.
• an aluminum electron collector an Al 2 O 3 or NiO thin film could reduce the Al oxidation potential.
• the electron collector can be coated with a thin alloy film, the alloy being resistant to corrosion by the electrolyte.
• an aluminum electron collector can be coated with an aluminum alloy.
• the aluminum alloy may be an alloy between aluminum and one or more transition metals.
• lithium ion transmitting materials such as lithium phosphorus oxynitride, which can be used as protection layers for electrodes, and which may also be used in embodiments of the present invention.
• Lithium ion transmitting materials used for electrode protection layers may also be used as protection layers for electron collectors.
• protection layers may comprise a lithium compound (such as a lithium salt), lithium alloy (such as LiAl alloys),), lithium oxide, hydroxide, or other lithium compound.
• Protection layers may include a compound which forms intercalation compounds with lithium ions (such as titanium disulfide), or other sulfide.
• an oxide coating can be formed on the surface of the electron collector by forming a halide coating one the electron collector, with the oxide coating being formed subsequently, for example by exposing to a combination of heat and oxygen, other chemical treatment, and/or exposure of the halide layer to the molten salt electrolyte in the battery.
• Halide layers can, for example, be formed using a process adapted from that described in U.S. Pat. No. 3,639,100 to Rick.
• a protection layer of titanium dioxide can be formed on an electron collector by a process including the formation of a titanium halide layer on the electron collector, followed by heating in air. Protection layers comprise mixtures, such as composites, of a first conducting material and a second material.
• the first conducting material may be a metal, conducting polymer, or other conducting material.
• the second material may be an oxide (such as a metal oxide), carbide, sulfide, nitride, or other material. Composites of two or more materials such as described herein may be used as protective layers.
• the protection layer can comprise a material that is non- reactive (e.g. non-catalytic) with respect to the molten salt electrolyte.
• the protection layer can include inorganic electronic conductive materials (such as metals, metal oxides, metal carbides, and the like), organic electron conductive materials such as a conducting polymer, or a combination of organic and inorganic materials (such as inorganic particles mixed with an organic polymer), or ormosil.
• the protection layer can comprise both organic and inorganic constituents.
• the protection layer can include a mixture of inorganic particles (such as TiC, TaC, or W particles) and an electron conducting polymer.
• the protection layer can include a metal (such as a transition metal), metal alloy, metal oxide, metal carbide, metal nitride, metal oxide, metal oxynitride, metal oxycarbide, or metal phosphide. Examples include W, Pt, TiC, TaC, WC, or Ti 4 O 7 .
• the protection layer can include an oxide, other oxygen-containing compound
• a phosphate or sulfate such as a phosphate or sulfate
• a carbide such as a phosphide, a nitride, an oxynitride, a sulfide, a compound including a metal and one or more other elements (such as elements selected from a group consisting of S, N, O, C, and P), a halide, conducting glass, silicon compound, semiconductor, conducting plastic, ceramic, alloy, or other conducting (including semiconducting) material.
• the protection layer can be a material, such as an electron-conducting material, for example a material selected from the group consisting of: oxides having at least one element which belongs to group 2 to 14 in the third or subsequent period of the periodic table as a constituent element thereof; carbides having at least one element which belongs to group 2 to 14 in the third or subsequent period of the periodic table as a constituent element thereof; nitrides having at least one element which belongs to group 2 to 14 in the third or subsequent period of the periodic table as a constituent element thereof; and tungsten.
• oxides having at least one element which belongs to group 2 to 14 in the third or subsequent period of the periodic table as a constituent element thereof
• carbides having at least one element which belongs to group 2 to 14 in the third or subsequent period of the periodic table as a constituent element thereof
• nitrides having at least one element which belongs to group 2 to 14 in the third or subsequent period of the periodic table as a constituent element thereof
• tungsten tungsten
• Examples include SnO 2 , T O , In 2 O 3 /SnO 2 (ITO), Ta 2 O 5 , WO 2 , W ⁇ 8 O 49 , CrO 2 and Tl 2 O 3 , in which the oxidation number of the metal in the oxide is relatively high, and hence the resistance to oxidation is good.
• Examples also include MgO, BaTiO 3 , TiO 2 , ZrO 2 , Al 2 O 3 , and SiO 2 , which have excellent electrochemical stability.
• the protection layer can be non- electrically conducting in bulk, if when used as a thin film, does not increase the cell impedance beyond an acceptable value.
• the protection layer can include an alloy, such as a transition metal alloy, an aluminum alloy (which ( may be an alloy including aluminum and one or more transition metals), or other alloy, or intermetallic compound. The alloy can be more resistant to corrosion by the electrolyte than the underlying surface.
• an aluminum electron collector can be coated with an aluminum alloy.
• the aluminum alloy may be an alloy between aornum and one or more transition metals.
• a protection layer can include a non-metal oxide, or other non-metal compound.
• the protection layer thickness can be monolayer, sub-nanoscale, nanoscale (0.5 nm- 1 micron), or microscale (1 micron- 1 mm).
• An electron conducting material can be in the form of a film, or particulates deposited on the surface of the electron collector.
• the protection layer may comprise granules, spheres, rods, flakes, or other particle forms.
• An electron conducting material, if particulate may have a distribution of sizes, or may be substantially monodisperse.
• Electron conducting particles may also be provided with a coating to prevent or reduce decomposition problems.
• a particulate protection layer, or other protection layer can further include binding or filling agents, for example to increase mechanical strength and/or to reduce voids.
• Non-conducting or conducting particle cores can be coated with a conducting coating of a second conducting material to provide an improved electron conducting material.
• the thickness of a thin film on a particle can be substantially less than an effective dimension (e.g. diameter) of the particle.
• the film thickness can be selected to as to allow substantial electron transmission through the coating.
• a carbon film or carbon particles can be additionally coated with a thin oxide, nitride, carbide, or tungsten film.
• carbon coated with a metal oxide, metal nitride, metal carbide, or tungsten or other transition metal, such as platinum, can be used as a protection layer.
• a thin metal oxide film such as TiO 2 can be used as a protection layer.
• a protection layer can also be formed by treatment of a component surface.
• an aluminum surface of an electron collector can be treated so as to induce formation of a protection layer on an aluminum substrate.
• surface reactions between aluminum and a reagent, or surface alloying so as to form protective aluminum alloy coatings can be used.
• One or more oxidation additives can be disposed on the surface of the electron collector, decreasing the surface potential of the electron collector, and reducing its corrosion by the molten salt electrolyte.
• an Al 2 O 3 or NiO thin film could reduce the Al oxidation potential.
• Protection layers can function through a surface potential reduction, by prevention of contact between the molten salt and the surface, by another mechanism, or by any combination of mechanisms.
• a protection layer applied to an electron collector may include a lithium compound (such as a lithium salt), lithium alloy (such as LiAI alloys), oxide (for example, a metal oxide such as a transition metal oxide, lithium oxide, or mixed oxide), hydroxide, other transition metal compound (such as a transition metal chalcogenide), a compound which forms intercalation compounds with lithium ions (such as titanium disulfide), other sulfide, a layer of solid electrolyte, glassy material, crystalline material, amorphous material, elastomer, sol-gel, and the like.
• a lithium compound such as a lithium salt
• lithium alloy such as LiAI alloys
• oxide for example, a metal oxide such as a transition metal oxide, lithium oxide, or mixed oxide
• hydroxide such as a transition metal compound (such as a transition metal chalcogenide)
• a compound which forms intercalation compounds with lithium ions such as titanium disulfide
• other sulfide such as titanium disulfide
• a protection layer may include a polymer, such as a polyalklyene oxide (such as polyethylene oxide), conducting polymer (such as a polypyrrole), polycarbonate, PVDF, polymer complex (e.g. with a lithium compound), and the like. Certain compounds may fall into one or more of the above categories. Improved protection layers described herein may be applied to surfaces of one or more components, such as the negative electrode, positive electrode, electrode collector, or other component of a molten salt type batteiy. Improved protection layers described herein may also contain other materials, such as conventional binding agents, as are well known in the battery art. Electron conducting materials disclosed herein may also be used with in conjunction with other electrolytes (i.e.
• non-molten salt electrolytes or in other systems, as appropriate.
• materials that are non-reactive materials to a molten salt can be coated on an electron collector, e.g. an Al electron collector, providing improved performance, for example compared with an Al-Rexam sheet coated with carbon. Protection layers can be applied to both the electron collector and the positive electrode. Two or more of the herein-described materials or methods may be combined so as to enhance corrosion resistance of the electron collector.
• the protection layer may form as a result of a surface treatment of the electron collector.
• the surface treatment may be: a physical or chemical deposition process; chemical bath treatment; acid treatment; galvanic plating (electroplating); deposition of metal using an organic carrier (such as a polymer or complex) followed by elimination of the organic component by heat, solvent, or other means; or other process or combination of processes.
• the protection layer may comprise an oxide of a different metal than found in the electron collector, for example an aluminum electron collector may have a titanium dioxide protection layer. A metal film can be deposited, then oxidized.
• the electron collector may be pre-treated before formation of the protection layer, for example by deposition of a monolayer (for example, a metal monolayer) or other thin film to enhance adhesion of the protection layer.
• the protection layer can form as a reaction between the electron collector and an electrolyte, or between the electron collector and a suitable additive within the electrolyte.
• the protection layer can be deposited on an electron collector using chemical or physical deposition methods, such as evaporation, sublimation, physical vapor deposition, chemical vapor deposition, plasma treatment, sputtering, thermal treatment, photochemical treatment, silane treatment, anodization, and the like.
• the protection layer can also be an electrically conducting polymer, such as polyaniline, polypyrrole, polythiophene, polyvinylidene fluoride, derivatives thereof, or other electrically conducting polymer.
• the protection layer can be formed by any thin film coating or deposition process, alloy formation process, or other process.
• the protection layer may be used with, or formed by interaction with, an appropriate molten salt electrolyte, or other battery components.
• Protection layers can be formed by adding a small quantity of aqueous or organic material to the molten salt electrolyte, and may be formed by a reaction of a component of the molten salt electrolyte with the electron collector, or may be formed by a treatment of a electron collector such as evaporative deposition of a component that reacts with the material of the electron collector to form a protective film.
• an electrode in contact with or otherwise proximate to the electron collector may comprise a component that interacts with the electron collector so as to form the protection layer on the electron collector.
• the protection layer may be formed by a reaction between a material within the molten salt electrolyte and the electron collector, on an initial charge or discharge of the cell.
• the protection layer can be in the form of a sheet, or deposited as particles, such as a nanoparticle film.
• the protection layer can be laid down as a slurry, including inorganic components and organic components (such as solvents). Solvents can be driven off thermally after protection layer formation.
• a molten salt electrolyte is an electrolyte comprising one or more salts, that is molten (or liquid) at the operating temperatures of the device using the electrolyte.
• a molten salt electrolyte can also be described as a molten, non-aqueous electrolyte, as an aqueous solvent is not required.
• Molten salt electrolytes which may be used in embodiments of the invention are described in U.S. Pat. Nos.
• the molten salt electrolyte in the invention may include an onium, such as an ammonium, a phosphomum, an oxonium, a sulfonium, an amidinium, an imidazolium, a pyrazolium, and a low basicity anion, such as PF 6 “ , BF 4 “ , CF 3 SO 3 “ , (CF 3 SO 2 )N “ , (FSO 2 ) 2 N “ .
• an onium such as an ammonium, a phosphomum, an oxonium, a sulfonium, an amidinium, an imidazolium, a pyrazolium, and a low basicity anion, such as PF 6 “ , BF 4 " , CF 3 SO 3 “ , (CF 3 SO 2 )N “ , (FSO 2 ) 2 N “ .
• the molten salt electrolyte in the invention may also include Y + N " (-SO 2 Rf 2 )(-XRf 3 ), where Y 4 is a cation selected from the group consisting of an imidazolium ion, an ammonium ion, a sulfonium ion, a pyridinium, a(n) (iso)thiazolyl ion, and a(n) (iso) oxazolium ion, which may be optionally substituted with C MO alkyl or Ci-io alkyl having ether linkage, provided that said cation has at least one substituent of -CTbRf 1 or-OCHaRf 1 (where Rf is C M0 polyfluoroalkyl); Rf 2 and Rf 3 are independently C MO perfluorophenyl or may together from C O perfluoroalkylene; and X is -SO 2 - or -CO-.
• the molten salt electrolyte may also include a lithium salt, such as one or more of the following: LiPF 6 , LiAsFe, LiSbF 6 , LiBF 4 , LiClO 4 , LiCF 3 SO 3 , Li(CF 3 SO 2 ) 2 N, Li(C 2 F 5 SO 2 ) 2 N, LiC 4 F 9 SO 3 , Li(CF 3 SO 2 ) 3 C, LiBPh 4 , LiBOB, and Li(CF 3 SO 2 )(CF 3 CO)N.
• a lithium salt such as one or more of the following: LiPF 6 , LiAsFe, LiSbF 6 , LiBF 4 , LiClO 4 , LiCF 3 SO 3 , Li(CF 3 SO 2 ) 2 N, Li(C 2 F 5 SO 2 ) 2 N, LiC 4 F 9 SO 3 , Li(CF 3 SO 2 ) 3 C, LiBPh 4 , LiBOB, and Li(CF 3 SO 2 )(CF 3 CO)N
• the protection layer can form as a reaction between the negative electroactive material and the electrolyte, or between the negative electroactive material and a suitable additive within the electrolyte.
• the protection layer can be deposited on the negative electrode using chemical or physical deposition methods, such as evaporation, sublimation, physical vapor deposition, chemical vapor deposition, plasma treatment, sputtering, thermal treatment, photochemical treatment, silane treatment, sol-gel process, anodization, and the like.
• the protection layer can be formed by any thin film coating or deposition process, alloy formation process, or other process.
• the protection layer may be used with, or formed by interaction with, an appropriate molten salt electrolyte, or other battery components.
• the protection layer may be formed by depositing polymerizable materials on the surface of the negative electrode, and polymerizing in situ to form the protection layer.
• polymerization includes copolymerization processes.
• a solid polymer electrolyte layer may be formed by depositing precursor molecules, followed by polymerization, for example using UN.
• the precursor molecules may be organic (such as a polymerizable organic molecule) or inorganic (such as a silane derivative).
• the protection layer formation may take place at low temperatures (such as liquid nitrogen temperatures) or under an oxygen free atmosphere so as to inhibit reactions of the negative electroactive material during formation of the protection layer.
• Protection layers can be formed by adding a small quantity of aqueous or organic material to the molten salt electrolyte, or may be formed by a reaction of a component of the molten salt electrolyte with the lithium electrode, or may be formed by a treatment of a Li metal electrode such as evaporative deposition of a component that reacts with Li to form a protective film. Protection layers can also (or alternatively) be formed on a positive electrode, for example using a composition or formation process as described herein. The protection layer may be formed by a reaction between a material within the molten salt electrolyte and the electron collector, on an initial charge or discharge of the cell. Hence, in examples of the present invention, an electron collector can be protected against reaction with the electrolyte using a protection layer.
• the protection layer can be in the form of a uniform thin film, or deposited as particles, such as a nanoparticle film.
• the positive electrode of a battery can be formed from any suitable material.
• a positive electrode for a lithium-ion battery may comprise lithium cobalt oxide (Li x CoO 2 ), lithium manganese oxide (Li x Mn 2 O 4 ), lithium nickel oxide (Li x NiO 2 ), other lithium transition metal oxides, lithium metal phosphates, fluorinated lithium metal phosphates, and other lithium metal chalcogenides, where the metal can be a transition metal.
• the lithium content of the positive electrode or of the negative electrode can vary substantially with battery charge state.
• the positive electrode may further include an electron-conducting material and a binder.
• An electrode may further include non-electroactive materials such as an electron-conducting material.
• a non- electroactive material does not substantially interact with the electrolyte under normal operating conditions.
• the electron-conducting material may comprise a carbon-containing material, such as graphite.
• Other example electron-conductive materials include polyaniline or other conducting polymer, carbon fibers, carbon black (such as acetylene black, or Ketjen black), and non-electroactive metals (in, for example, a lithium-ion battery) such as cobalt, copper, nickel, other metal, or metal compound.
• the electron conducting material may be in the form of particles (as used here, the term includes granules, flakes, powders and the like), fibers, a mesh, sheet, or other two or three- dimensional framework.
• An electrode may further include a binder, such as a polyethylene.
• the binder may be a fluoropolymer such as polytetrafluoroethylene.
• the binder may comprise one or more inert materials, for the purpose of improving the mechanical properties of the electrode, facilitating electrode manufacture or processing, or other purpose.
• Example binder materials include fluoropolymers (such as polytetrafluoroethylenes, polyvinylidene difluoride (PVdF), and the like), polyolefins and derivatives thereof, polyethylene oxide, acrylic polymers (including polymethacrylates), synthetic rubber, and the like.
• the electrode may further comprise regions of electrolyte, and/or an ion conductive protection layer to separate the negative electrode from the electrolyte, or other component or components. Electrodes may further comprise other non- electrically conducting, non-electroactive materials such as inert oxides, polymers, and the like.
• An example battery includes a positive electrode, a negative electrode, an electrolyte, the electrolyte including a lithium salt, and first and second current collectors, associated with the negative electrode and positive electrode respectively.
• Examples of the present invention also molten salt electrolyte batteries, and also include other non-aqueous electrolyte secondary (rechargeable) batteries).
• An example battery may further include electrical leads and appropriate packaging, for example a sealed container providing electrical contacts in electrical communication with the first and second current collectors. Batteries may further include one or more separators, located between the negative electrode and positive electrode with the purpose of preventing direct contact between the negative electrode and the positive electrode. The separator is optional, and a solid electrolyte may provide a similar function.
• a separator may be a porous material, including a material such as a polymer (such as polyethylene or polypropylene), sol-gel material, ormosil, glass, ceramic, glass-ceramic, or other material, and may be in the form of a porous sheet, mesh, fibrous mat (cloth), or other form.
• a separator may be attached to a surface of one or both electrodes.
• Electron collectors can include aluminum, copper, iron, steel (such as stainless steel), nickel, zinc, electron-conducting polymers, metalized polymers (such as metalized Mylar), and the like.
• the electron collector may take any physical form, such as a sheet (planar or curved), rod, mesh, porous, granular, two or three-dimensional lattice, or any other form.
• Example 1 A laminate cell was constructed with the materials listed below: Cathode Cathode active material: LiCoO 2 Electron conductive material: acetylene black Binder: PVdF Current collector: Coated Aluminum foil Coating paste: Disperse acetylene black and PVdF in NMP Anode Anode active material: L ⁇ TisO ⁇ Electron conductive material: acetylene black Binder: PVdF Current collector: Aluminum foil Electrolyte Solvent: EMI-FSI Lithium salt: Li-TFSI (1.0M) Separator: PP porous film Cycle test condition After conditioning, 1C cc-cc charge-discharge for 100 cycles Example 2 Apply WC powder instead of acetylene black for coating cathode current collector. Other conditions are the same as Ex.l. Reference 1 Use aluminum foil as cathode current collector. Other conditions are the same as Ex.l. Reference 2 Use nickel foil as cathode current collector. Other conditions are the same as

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• 2005
  • 2005-03-15 US US11/080,722 patent/US7521153B2/en not_active Expired - Lifetime
  • 2005-03-16 WO PCT/US2005/008769 patent/WO2005089383A2/en not_active Ceased
  • 2005-03-16 JP JP2007504069A patent/JP5259179B2/ja not_active Expired - Fee Related

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