WO2020050896A1 - Batterie secondaire au lithium-métal contenant une anode au lithium protégée - Google Patents

Batterie secondaire au lithium-métal contenant une anode au lithium protégée Download PDF

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Publication number
WO2020050896A1
WO2020050896A1 PCT/US2019/038455 US2019038455W WO2020050896A1 WO 2020050896 A1 WO2020050896 A1 WO 2020050896A1 US 2019038455 W US2019038455 W US 2019038455W WO 2020050896 A1 WO2020050896 A1 WO 2020050896A1
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lithium
anode
layer
electrolyte
poly
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PCT/US2019/038455
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English (en)
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Hui He
Baofei Pan
Aruna Zhamu
Bor Z. Jang
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Nanotek Instruments, Inc.
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Priority claimed from US16/123,218 external-priority patent/US20190393482A1/en
Priority claimed from US16/123,212 external-priority patent/US10777810B2/en
Application filed by Nanotek Instruments, Inc. filed Critical Nanotek Instruments, Inc.
Publication of WO2020050896A1 publication Critical patent/WO2020050896A1/fr

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    • H—ELECTRICITY
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    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/381—Alkaline or alkaline earth metals elements
    • H01M4/382—Lithium
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    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0561—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of inorganic materials only
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    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
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    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/483—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides for non-aqueous cells
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    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
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    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
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    • 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
    • H01M4/581—Chalcogenides or intercalation compounds thereof
    • H01M4/5815—Sulfides
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    • 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
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    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/60—Selection of substances as active materials, active masses, active liquids of organic compounds
    • H01M4/602—Polymers
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    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
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    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
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    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
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    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
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    • H01M2300/00—Electrolytes
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    • H01M2300/0065—Solid electrolytes
    • H01M2300/0068—Solid electrolytes inorganic
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    • H01M2300/0071—Oxides
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    • H01M2300/0065—Solid electrolytes
    • H01M2300/0082—Organic polymers
    • 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
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    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present disclosure relates to the field of rechargeable lithium metal battery having a lithium metal layer (in a form of thin lithium foil, lithium coating, or sheet of lithium particles) as an anode active material layer and a method of manufacturing same.
  • Lithium-ion and lithium (Li) metal cells are considered promising power sources for electric vehicle (EV), hybrid electric vehicle (HEV), and portable electronic devices, such as lap- top computers and mobile phones.
  • EV electric vehicle
  • HEV hybrid electric vehicle
  • Lithium metal has the highest capacity (3,861 mAh/g) compared to any other metal or metal-intercalated compound (except Li 4.4 Si) as an anode active material.
  • rechargeable Li metal batteries have a significantly higher energy density than lithium ion batteries.
  • rechargeable lithium metal batteries were produced using non-lithiated compounds having high specific capacities, such as TiS 2 , MoS 2 , MnO 2 , CoO 2 and V 2 O 5 , as the cathode active materials, which were coupled with a lithium metal anode.
  • non-lithiated compounds having high specific capacities such as TiS 2 , MoS 2 , MnO 2 , CoO 2 and V 2 O 5
  • lithium ions were dissolved from the lithium metal anode and transferred to the cathode through the electrolyte and, thus, the cathode became lithiated.
  • the lithium metal resulted in the formation of dendrites that ultimately caused unsafe conditions in the battery.
  • the production of these types of secondary batteries was stopped in the early 1990's giving ways to lithium-ion batteries.
  • Fauteux, et al. [D. Fauteux, et al.,“Secondary Electrolytic Cell and Electrolytic Process,” US Pat. No.5,434,021, July 18, 1995] applied to a metal anode a protective surface layer (e.g., a mixture of polynuclear aromatic and polyethylene oxide) that enables transfer of metal ions from the metal anode to the electrolyte and back.
  • the surface layer is also electronically conductive so that the ions will be uniformly attracted back onto the metal anode during electrodeposition (i.e. during battery recharge).
  • Alamgir, et al. [M. Alamgir, et al.“Solid polymer electrolyte batteries containing metallocenes,” U.S. Pat. No.5,536,599, July 16, 1996] used ferrocenes to prevent chemical overcharge and dendrite formation in a solid polymer electrolyte-based rechargeable battery.
  • Skotheim [T. A. Skotheim,“Stabilized Anode for Lithium-Polymer Battery,” U.S. Pat. No.5,648,187 (July 15, 1997); No.5,961,672 (Oct.5, 1999)] provided a Li metal anode that was stabilized against the dendrite formation by the use of a vacuum-evaporated thin film of a Li ion- conducting polymer interposed between the Li metal anode and the electrolyte.
  • Skotheim, et al. [T. A. Skotheim, et al.“Lithium Anodes for Electrochemical Cells,” U.S. Pat. No.6,733,924 (May 11, 2004); No.6,797,428 (Sept.28, 2004); No.6,936,381 (Aug.30, 2005); and No.
  • Li anodes such as glassy surface layers of LiI- Li 3 PO 4 -P 2 S 5
  • Protective coatings for Li anodes may be obtained from plasma assisted deposition [S. J. Visco, et al.,“Protective Coatings for Negative Electrodes,” US Pat. No.6,025,094 (Feb.15, 2000)].
  • Complex, multi-layer protective coatings were also proposed by Visco, et al. [S. J. Visco, et al.,“Protected Active Metal Electrode and Battery Cell Structures with Non-aqueous Interlayer Architecture,” US Pat. No.7,282,295 (Oct. 16, 2007); No.7,282,296 (Oct.16, 2007); and No.7,282,302 (Oct.16, 2007)].
  • solid electrolyte as the sole electrolyte in a cell or as an anode-protecting layer (interposed between the lithium film and the liquid electrolyte) does not have and cannot maintain a good contact with the lithium metal. This effectively reduces the effectiveness of the electrolyte to support dissolution of lithium ions (during battery discharge), transport lithium ions, and allowing the lithium ions to re-deposit back onto the lithium anode (during battery recharge).
  • lithium metal anode Another major issue associated with the lithium metal anode is the continuing reactions between electrolyte and lithium metal, leading to repeated formation of“dead lithium-containing species” that cannot be re-deposited back to the anode and become isolated from the anode. These reactions continue to irreversibly consume electrolyte and lithium metal, resulting in rapid capacity decay. In order to compensate for this continuing loss of lithium metal, an excessive amount of lithium metal (3-5 times higher amount than what would be required) is typically implemented at the anode when the battery is made. This adds not only costs but also a significant weight and volume to a battery, reducing the energy density of the battery cell. This important issue has been largely ignored and there has been no plausible solution to this problem in battery industry.
  • an object of the present disclosure was to provide an effective way to overcome the lithium metal dendrite and reaction problems in all types of Li metal batteries having a lithium metal anode.
  • a specific object of the present disclosure was to provide a lithium metal cell that exhibits a high specific capacity, high specific energy, high degree of safety, and a long and stable cycle life.
  • a lithium metal secondary battery comprising a cathode, an anode, and an electrolyte or separator-electrolyte assembly disposed between the cathode and the anode, wherein the anode comprises: (a) a layer of lithium or lithium alloy (in the form of a foil, coating, or multiple particles aggregated together) as an anode active material layer; (b) a first anode-protecting layer having a thickness from 1 nm to 100 mm and comprising a thin layer of a lithium ion-conducting material (having a lithium ion conductivity from 10 -8 S/cm to 5 x 10 -2 S/cm) in physical contact with and in protecting relation to the anode active material layer (e.g.
  • a second anode-protecting layer in contact with the first protecting layer, having a thickness from 1 nm to 100 ⁇ m and comprising an elastomer having a fully recoverable tensile elastic strain from 2% to 1,000%, a lithium ion conductivity from 10 -8 S/cm to 5 x 10 -2 S/cm when measured at room temperature.
  • the first anode-protecting layer partially or, preferably, completely covers the anode active material layer when the battery is made.
  • the second anode-protecting layer is disposed between the first anode-protecting layer and the electrolyte or separator-electrolyte assembly layer.
  • the foil or coating of lithium or lithium alloy may be supported by a current collector (e.g. a Cu foil, a Ni foam, a porous layer of nanofilaments, such as graphene sheets, carbon nanofibers, carbon nanotubes, etc.).
  • a porous separator may not be necessary if the electrolyte is a solid-state electrolyte.
  • the lithium battery does not contain a porous separator and the second anode-protecting layer itself acts as a separator that electronically separates the anode active material layer from the cathode.
  • the invented lithium metal secondary battery does not include a lithium-sulfur cell or lithium-selenium cell.
  • the cathode does not include sulfur, lithium polysulfide, selenium and lithium polyselenide.
  • the lithium ion-conducting material in the first anode-protecting layer comprises a lithium salt selected from lithium perchlorate (LiClO 4 ), lithium
  • LiPF 6 lithium borofluoride
  • LiAsF 6 lithium hexafluoroarsenide
  • LiCF 3 SO 3 lithium trifluoro-methanesulfonate
  • LiN(CF 3 SO 2 ) 2 lithium bis(oxalato)borate
  • LiBOB lithium oxalyldifluoroborate
  • LiNO 3 Li-fluoroalkyl-phosphate
  • LiPF 3 (CF 2 CF 3 ) 3 lithium bisperfluoro- ethylsulfonylimide (LiBETI)
  • lithium bis(trifluoromethanesulfonyl)imide lithium
  • LiTFSI lithium trifluoromethanesulfonimide
  • the lithium ion-conducting material in the first anode-protecting layer may comprise a lithium ion-conducting polymer selected from poly(ethylene oxide) (PEO), polypropylene oxide (PPO), poly(acrylonitrile) (PAN), poly(methyl methacrylate) (PMMA), poly(vinylidene fluoride) (PVDF), poly bis-methoxy ethoxyethoxide-phosphazene, polyvinyl chloride, polydimethylsiloxane, poly(vinylidene fluoride)-hexafluoropropylene (PVDF-HFP), a co- polymer thereof, a sulfonated derivative thereof, or a combination thereof.
  • a lithium ion-conducting polymer selected from poly(ethylene oxide) (PEO), polypropylene oxide (PPO), poly(acrylonitrile) (PAN), poly(methyl methacrylate) (PMMA), poly(vinylidene fluoride) (
  • the lithium ion-conducting material comprises an inorganic solid-state electrolyte material having a lithium ion conductivity greater than 10 -6 S/cm.
  • solid electrolyte materials that can be adapted as a lithium ion-conducting material in the presently invented first anode-protecting layer.
  • the solid-state electrolyte material may be selected from a ceramic electrolyte, glass-ceramic electrolyte, glass electrolyte, metal sulfide electrolyte, or a combination thereof.
  • Solid electrolytes that can be implemented in the presently invented first anode-protecting layer include the well-known NASICON-type, Granet-type, LISICON-type, Perovskite-type, sulfide-type, Li 3 N-type, Argyrodite-type, and thin-film solid state electrolytes.
  • the lithium ion-conducting material may be formed as a layer of sintered ceramic, glass, glass-ceramic, or sulfide material, etc. as would be normally used as a solid-state electrolyte in a lithium battery.
  • this material may be formed into a thin film (e.g. via sputtering or laser-assisted deposition) deposited on a primary surface of the anode active material layer or a primary surface of the second anode-protecting layer.
  • the layer preferably has a thickness from 2 nm to 2 ⁇ m, more preferably from 2 nm to 100 nm.
  • the solid- state electrolyte material used in the first anode protecting layer may comprise particles of a sintered or un-sintered solid electrolyte material that are bonded together by a resin binder to form a layer of structural integrity.
  • the resin binder is from 1% to 50% of this second anode-protecting layer layer.
  • This layer may be chemically bonded to the elastomer layer or integral with the elastomer layer.
  • this layer may be an extension of the elastomer layer, but preferably having a different composition than the rest of the elastomer layer; e.g. having a much higher concentration of solid electrolyte material particles or other additives near the skin zone of the elastomer layer than the rest of the elastomer layer.
  • the elastomer (sulfonated or non-sulfonated) in the second anode-protecting layer is a high-elasticity material which exhibits an elastic deformation that is at least 2% (preferably at least 5% and up to approximately 1,000%) when measured under uniaxial tension.
  • the“elastic deformation” is defined as a deformation of a material (when being mechanically stressed) that is essentially fully recoverable upon release of the load and the recovery process is essentially instantaneous (no or little time delay).
  • the elastic deformation is more preferably greater than 10%, even more preferably greater than 30%, further more preferably greater than 50%, and still more preferably greater than 100%.
  • the elastomer in the second anode-protecting layer preferably and more typically has a fully recoverable elastic tensile strain from 5% to 300% (most typically from 10% to 150%), a thickness from 10 nm to 20 ⁇ m, and an electrical conductivity of at least 10 -4 S/cm when measured at room temperature on a cast thin film 20 ⁇ m thick.
  • the elastomer in the second anode-protecting layer contains a sulfonated or non-sulfonated version of natural polyisoprene, synthetic polyisoprene, polybutadiene, chloroprene rubber, polychloroprene, butyl rubber, styrene-butadiene rubber, nitrile rubber, ethylene propylene rubber, ethylene propylene diene rubber, metallocene-based poly(ethylene- co-octene) (POE) elastomer, poly(ethylene-co-butene) (PBE) elastomer, styrene-ethylene- butadiene-styrene (SEBS) elastomer, epichlorohydrin rubber, polyacrylic rubber, silicone rubber, fluorosilicone rubber, perfluoroelastomers, polyether block amides, chlorosulfonated
  • polyethylene polyethylene, ethylene-vinyl acetate, thermoplastic elastomer, protein resilin, protein elastin, ethylene oxide-epichlorohydrin copolymer, polyurethane, urethane-urea copolymer, or a combination thereof.
  • thermoplastic elastomer polyethylene, ethylene-vinyl acetate, thermoplastic elastomer, protein resilin, protein elastin, ethylene oxide-epichlorohydrin copolymer, polyurethane, urethane-urea copolymer, or a combination thereof.
  • elastomers or rubbers when present without graphene sheets, exhibit a high elasticity (having a fully recoverable tensile strain from 2% to 1,000%). In other words, they can be stretched up to 1,000% (10 times of the original length when under tension) and, upon release of the tensile stress, they can fully recover back to the original dimension.
  • the fully recoverable tensile strains are typically reduced down to 2%-500% (more typically from 5% to 300% and most typically from 10% to 150%).
  • the elastomer if sulfonated, becomes significantly more lithium ion-conducting.
  • the lithium ion conductivity of an elastomer, sulfonated or un-sulfonated, may be further improved if some desired amount of lithium ion-conducting additive is incorporated into the elastomer matrix.
  • the first anode-protecting layer is preferably chemically bonded to the second anode- protecting layer or is integral with the second anode-protecting layer. Such an connection enables the first anode-protecting layer to move in a concerted manner with the second anode protecting layer when the elastomer deforms (being compressed or relaxed) during battery recharge or discharge.
  • the lithium foil/coating layer may decrease in thickness due to dissolution of lithium into the electrolyte to become lithium ions as the lithium battery is discharged, creating a gap between the current collector/lithium foil and the solid electrolyte layer in a conventional all-solid lithium battery. Such a gap would make the re-deposition of lithium ions back to the anode active layer impossible.
  • the instant elastomer layer is capable of expanding or shrinking congruently or conformably with the anode active material layer. The elastic stress of the elastomer layer can help to maintain a good contact between the current collector (or the lithium film itself) and the first anode-protecting layer, enabling the re-deposition of lithium ions without interruption.
  • the elastomer in the second anode-protecting layer may further contain a lithium salt selected from lithium perchlorate (LiClO 4 ), lithium hexafluorophosphate (LiPF 6 ), lithium borofluoride (LiBF 4 ), lithium hexafluoroarsenide (LiAsF 6 ), lithium trifluoro-methanesulfonate (LiCF 3 SO 3 ), bis-trifluoromethyl sulfonylimide lithium (LiN(CF 3 SO 2 ) 2 ), lithium
  • a lithium salt selected from lithium perchlorate (LiClO 4 ), lithium hexafluorophosphate (LiPF 6 ), lithium borofluoride (LiBF 4 ), lithium hexafluoroarsenide (LiAsF 6 ), lithium trifluoro-methanesulfonate (LiCF 3 SO 3 ), bis-trifluoromethyl sulfonylimide lithium
  • LiBOB bis(oxalato)borate(LiBOB), lithium oxalyldifluoroborate (LiBF 2 C 2 O 4 ), lithium nitrate (LiNO 3 ), Li-Fluoroalkyl-Phosphates (LiPF 3 (CF 2 CF 3 ) 3 ), lithium bisperfluoro-ethylsulfonylimide (LiBETI), lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium
  • LiTFSI trifluoromethanesulfonimide
  • ionic liquid-based lithium salt an ionic liquid-based lithium salt, or a combination thereof.
  • the elastomer for the second protective layer is designed or selected to have a lithium ion conductivity no less than 10 -5 S/cm, more preferably no less than 10 -4 S/cm, and most preferably no less than 10 -3 S/cm.
  • the selected elastomers when sulfonated, can exhibit a lithium ion conductivity greater than 10 -2 S/cm.
  • the elastomer is a neat elastomer containing no additive or filler dispersed therein.
  • the elastomer is an elastomer matrix composite containing from 0.1% to 40% by weight (preferably from 1% to 30% by weight) of a lithium ion-conducting additive dispersed in an elastomer matrix material.
  • the elastomer contains from 0.1% by weight to 10% by weight of a reinforcement nanofilament selected from carbon nanotube, carbon nanofiber, graphene, or a combination thereof.
  • the elastomer in the second anode-protecting layer is selected from a sulfonated or un-sulfonated version of natural polyisoprene (e.g. cis-1,4-polyisoprene natural rubber (NR) and trans-1,4-polyisoprene gutta-percha), synthetic polyisoprene (IR for isoprene rubber), polybutadiene (BR for butadiene rubber), chloroprene rubber (CR), polychloroprene (e.g.
  • natural polyisoprene e.g. cis-1,4-polyisoprene natural rubber (NR) and trans-1,4-polyisoprene gutta-percha
  • synthetic polyisoprene IR for isoprene rubber
  • polybutadiene BR for butadiene rubber
  • chloroprene rubber CR
  • polychloroprene e.g.
  • Neoprene, Baypren etc. butyl rubber (copolymer of isobutylene and isoprene, IIR), including halogenated butyl rubbers (chloro butyl rubber (CIIR) and bromo butyl rubber (BIIR), styrene-butadiene rubber (copolymer of styrene and butadiene, SBR), nitrile rubber (copolymer of butadiene and acrylonitrile, NBR), EPM (ethylene propylene rubber, a copolymer of ethylene and propylene), EPDM rubber (ethylene propylene diene rubber, a terpolymer of ethylene, propylene and a diene-component), epichlorohydrin rubber (ECO), polyacrylic rubber (ACM, ABR), silicone rubber (SI, Q, VMQ), fluorosilicone rubber (FVMQ), fluoroelastomers (FKM, and FEPM; such as Viton,
  • Hypalon and ethylene-vinyl acetate (EVA), thermoplastic elastomers (TPE), protein resilin, protein elastin, ethylene oxide-epichlorohydrin copolymer, polyurethane, urethane-urea copolymer, or a combination thereof.
  • TPE thermoplastic elastomers
  • protein resilin protein elastin
  • ethylene oxide-epichlorohydrin copolymer polyurethane
  • urethane-urea copolymer or a combination thereof.
  • the elastomer may form a mixture, blend, co- polymer, or semi-interpenetrating network (semi-IPN) with an electron-conducting polymer selected from polyaniline, polypyrrole, polythiophene, polyfuran, a bi-cyclic polymer, derivatives thereof (e.g. sulfonated versions), or a combination thereof.
  • an electron-conducting polymer selected from polyaniline, polypyrrole, polythiophene, polyfuran, a bi-cyclic polymer, derivatives thereof (e.g. sulfonated versions), or a combination thereof.
  • the elastomer in the second anode-protecting layer may form a mixture, blend, or semi-IPN with a lithium ion-conducting polymer selected from poly(ethylene oxide) (PEO), polypropylene oxide (PPO), poly(acrylonitrile) (PAN), poly(methyl methacrylate) (PMMA), poly(vinylidene fluoride) (PVDF), poly bis-methoxy ethoxyethoxide-phosphazene, polyvinyl chloride, polydimethylsiloxane, poly(vinylidene fluoride)-hexafluoropropylene (PVDF-HFP), a sulfonated derivative thereof, or a combination thereof. Sulfonation is herein found to impart improved lithium ion conductivity to a polymer.
  • a lithium ion-conducting polymer selected from poly(ethylene oxide) (PEO), polypropylene oxide (PPO), poly(acrylonitrile) (PAN),
  • the cathode active material may be selected from an inorganic material, an organic material, a polymeric material, or a combination thereof.
  • the inorganic material may be selected from a metal oxide, metal phosphate, metal silicide, metal selenide, metal sulfide, or a combination thereof.
  • the inorganic material may be selected from a lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium vanadium oxide, lithium-mixed metal oxide, lithium iron phosphate, lithium manganese phosphate, lithium vanadium phosphate, lithium mixed metal phosphate, lithium metal silicide, or a combination thereof.
  • the inorganic material is selected from a metal fluoride or metal chloride including the group consisting of CoF 3 , MnF 3 , FeF 3 , VF 3 , VOF 3 , TiF 3 , BiF 3 , NiF 2 , FeF 2 , CuF 2 , CuF, SnF 2 , AgF, CuCl 2 , FeCl 3 , MnCl 2 , and combinations thereof.
  • a metal fluoride or metal chloride including the group consisting of CoF 3 , MnF 3 , FeF 3 , VF 3 , VOF 3 , TiF 3 , BiF 3 , NiF 2 , FeF 2 , CuF 2 , CuF, SnF 2 , AgF, CuCl 2 , FeCl 3 , MnCl 2 , and combinations thereof.
  • the inorganic material is selected from a lithium transition metal silicate, denoted as Li 2 MSiO 4 or Li 2 Ma x Mb y SiO 4 , wherein M and Ma are selected from Fe, Mn, Co, Ni, V, or VO; Mb is selected from Fe, Mn, Co, Ni, V, Ti, Al, B, Sn, or Bi; and x + y £ 1.
  • the inorganic material is selected from a transition metal dichalcogenide, a transition metal trichalcogenide, or a combination thereof.
  • the inorganic material is selected from TiS 2 , TaS 2 , MoS 2 , NbSe 3 , MnO 2 , CoO 2 , an iron oxide, a vanadium oxide, or a combination thereof.
  • the cathode active material layer may contain a metal oxide containing vanadium oxide selected from the group consisting of VO 2 , Li x VO 2 , V 2 O 5 , Li x V 2 O 5 , V 3 O 8 , Li x V 3 O 8 , Li x V 3 O 7 , V 4 O 9 , Li x V 4 O 9 , V 6 O 13 , Li x V 6 O 13 , their doped versions, their derivatives, and combinations thereof, wherein 0.1 ⁇ x ⁇ 5.
  • the cathode active material layer may contain a metal oxide or metal phosphate, selected from a layered compound LiMO 2 , spinel compound LiM 2 O 4 , olivine compound LiMPO 4 , silicate compound Li 2 MSiO 4 , Tavorite compound LiMPO 4 F, borate compound LiMBO 3 , or a combination thereof, wherein M is a transition metal or a mixture of multiple transition metals.
  • a metal oxide or metal phosphate selected from a layered compound LiMO 2 , spinel compound LiM 2 O 4 , olivine compound LiMPO 4 , silicate compound Li 2 MSiO 4 , Tavorite compound LiMPO 4 F, borate compound LiMBO 3 , or a combination thereof, wherein M is a transition metal or a mixture of multiple transition metals.
  • the inorganic material is selected from: (a) bismuth selenide or bismuth telluride, (b) transition metal dichalcogenide or trichalcogenide, (c) sulfide, selenide, or telluride of niobium, zirconium, molybdenum, hafnium, tantalum, tungsten, titanium, cobalt, manganese, iron, nickel, or a transition metal; (d) boron nitride, or (e) a combination thereof.
  • the cathode active material layer may contain an organic material or polymeric material selected from poly(anthraquinonyl sulfide) (PAQS), a lithium oxocarbon, 3,4,9,10- perylenetetracarboxylic dianhydride (PTCDA), poly(anthraquinonyl sulfide), pyrene-4,5,9,10- tetraone (PYT), polymer-bound PYT, quino(triazene), redox-active organic material, tetracyanoquinodimethane (TCNQ), tetracyanoethylene (TCNE), 2,3,6,7,10,11- hexamethoxytriphenylene (HMTP), poly(5-amino-1,4-dyhydroxy anthraquinone) (PADAQ), phosphazene disulfide polymer ([(NPS 2 ) 3 ]n), lithiated 1,4,5,8–naphthalenetetra
  • the thioether polymer is selected from poly[methanetetryl-tetra(thiomethylene)] (PMTTM), poly(2,4-dithiopentanylene) (PDTP), a polymer containing poly(ethene-1,1,2,2- tetrathiol) (PETT) as a main-chain thioether polymers, a side-chain thioether polymer having a main-chain consisting of conjugating aromatic moieties, and having a thioether side chain as a pendant, poly(2-phenyl-1,3-dithiolane) (PPDT), poly(1,4-di(1,3-dithiolan-2-yl)benzene) (PDDTB), poly(tetrahydrobenzodithiophene) (PTHBDT), poly[1,2,4,5- tetrakis(propylthio)benzene] (PTKPTB, or poly[3,4(ethylenedithio)thiophene] (
  • the cathode active material layer contains an organic material selected from a phthalocyanine compound, such as copper phthalocyanine, zinc phthalocyanine, tin phthalocyanine, iron phthalocyanine, lead phthalocyanine, nickel phthalocyanine, vanadyl phthalocyanine, fluorochromium phthalocyanine, magnesium phthalocyanine, manganous phthalocyanine, dilithium phthalocyanine, aluminum phthalocyanine chloride, cadmium phthalocyanine, chlorogallium phthalocyanine, cobalt phthalocyanine, silver phthalocyanine, a metal-free phthalocyanine, a chemical derivative thereof, or a combination thereof.
  • a phthalocyanine compound such as copper phthalocyanine, zinc phthalocyanine, tin phthalocyanine, iron phthalocyanine, lead phthalocyanine, nickel phthalocyanine, vanadyl phthalocyanine, fluorochrom
  • the cathode active material is preferably in a form of nanoparticle (spherical, ellipsoidal, and irregular shape), nanowire, nanofiber, nanotube, nanosheet, nanobelt, nanoribbon, nanodisc, nanoplatelet, or nanohorn having a thickness or diameter less than 100 nm. These shapes can be collectively referred to as“particles” unless otherwise specified or unless a specific type among the above species is desired. Further preferably, the cathode active material has a dimension less than 50 nm, even more preferably less than 20 nm, and most preferably less than 10 nm.
  • one particle or a cluster of particles may be coated with or embraced by a layer of carbon disposed between the particle(s) and/or a sulfonated elastomer composite layer (an encapsulating shell).
  • the cathode layer may further contain a graphite, graphene, or carbon material mixed with the cathode active material particles.
  • the carbon or graphite material is selected from polymeric carbon, amorphous carbon, chemical vapor deposition carbon, coal tar pitch, petroleum pitch, mesophase pitch, carbon black, coke, acetylene black, activated carbon, fine expanded graphite particle with a dimension smaller than 100 nm, artificial graphite particle, natural graphite particle, or a combination thereof.
  • Graphene may be selected from pristine graphene, graphene oxide, reduced graphene oxide, graphene fluoride, hydrogenated graphene, nitrogenated graphene, functionalized graphene, etc.
  • the cathode active material particles may be coated with or embraced by a conductive protective coating, selected from a carbon material, graphene, electronically conductive polymer, conductive metal oxide, or conductive metal coating.
  • the present disclosure also provides a lithium metal-air battery comprising an air cathode, an anode comprising the first anode-protecting layer (i.e. comprising a lithium ion- conducting material) and the second anode-protecting layer (e.g. an elastomer or elastomer matrix composite) as defined above, and electrolyte, or electrolyte combined with a separator, disposed between the anode and the air cathode.
  • oxygen from the open air or from an oxygen supplier external to the battery
  • the air cathode needs an inert material to support the lithium oxide material formed at the cathode.
  • an integrated structure of conductive nanofilaments can be used as an air cathode intended for supporting the discharge product (e.g., lithium oxide).
  • a further embodiment of the present disclosure is a lithium metal-air battery, wherein the air cathode comprises an integrated structure of electrically conductive nanometer- scaled filaments that are interconnected to form a porous network of electron-conducting paths comprising interconnected pores, wherein the filaments have a transverse dimension less than 500 nm (preferably less than 100 nm).
  • These nanofilaments can be selected from carbon nanotubes (CNTs), carbon nanofibers (CNFs), graphene sheets, carbon fibers, graphite fibers, etc.
  • the disclosure also provides a method of manufacturing a lithium battery, the method comprising: (a) providing a cathode active material layer and an optional cathode current collector to support the cathode active material layer; (b) providing an anode active material layer (e.g.
  • a lithium metal or lithium alloy foil or coating containing a lithium metal or lithium alloy foil or coating
  • an optional anode current collector to support the lithium metal or lithium alloy foil or coating
  • the disclosure also provides a method of improving the cycle-life of a lithium metal secondary battery (not including a lithium-sulfur battery or lithium-selenium battery).
  • the method comprises implementing two anode-protecting layers between an anode active material layer and an electrolyte or a porous separator/electrolyte assembly.
  • the first anode-protecting layer has a thickness from 1 nm to 100 mm (preferably from 2 nm to 100 nm) and comprises a thin layer of a lithium ion-conducting material having a lithium ion conductivity from 10 -8 S/cm to 5 x 10 -2 S/cm and being in physical contact with the anode active material layer.
  • the second anode-protecting layer comprises an elastomer having a recoverable tensile elastic strain from 2% to 1,000% (preferably from 5% to 300%), a lithium ion conductivity no less than 10 -8 S/cm (preferably > 10 -5 S/cm) at room temperature, and a thickness from 1 nm to 100 ⁇ m (preferably from 10 nm to 10 mm).
  • This second anode-protecting layer is disposed between the first anode-protecting layer (covering the lithium metal or lithium alloy foil or coating) and the porous separator (or electrolyte).
  • the elastomer in the second layer contains a material selected from a sulfonated or non-sulfonated version of natural polyisoprene, synthetic polyisoprene, polybutadiene, chloroprene rubber, polychloroprene, butyl rubber, styrene-butadiene rubber, nitrile rubber, ethylene propylene rubber, ethylene propylene diene rubber, metallocene-based poly(ethylene-co-octene) elastomer, poly(ethylene-co-butene) elastomer, styrene-ethylene- butadiene-styrene elastomer, epichlorohydrin rubber, polyacrylic rubber, silicone rubber, fluorosilicone rubber, perfluoroelastomers, polyether block amides, chlorosulfonated polyethylene, ethylene-vinyl acetate, thermoplastic elastomer, protein resilin,
  • the step of implementing a first anode-protecting layer may be conducted by spraying a slurry of a lithium ion-conducting material (e.g. an inorganic solid electrolyte material along with an optional binder resin, or a polymer electrolyte material) dispersed in a liquid (e.g. an organic solvent) onto a primary surface of the anode active material layer, followed by liquid removal.
  • a lithium ion-conducting material e.g. an inorganic solid electrolyte material along with an optional binder resin, or a polymer electrolyte material
  • a liquid e.g. an organic solvent
  • anode active material layer e.g. a Li foil
  • the step of implementing a second anode-protecting layer may be conducted by depositing a layer of an elastomer onto one primary surface of the first protective layer that in turn covers the anode active material layer.
  • This step comprises optionally compressing the protected anode to improve the contact between the anode-protecting layers and the anode active material layer, followed by combining the protected anode, the separator/electrolyte, and the cathode together to form the lithium metal secondary battery.
  • a good contact between the anode active material layer and the anode-protecting layer is essential to reducing internal resistance.
  • the step of implementing the anode-protecting layers is conducted by (i) preparing a lithium ion-conducting material-protected anode active material layer; (ii) depositing a layer of an elastomer onto one primary surface of the separator to form a coated separator; and (iii) combining the ion-conducting material (first protecting layer)- protected active anode layer, the coated separator, a cathode, and the electrolyte together to form the lithium metal secondary battery.
  • a compressive stress may be advantageously applied (e.g. via press-rolling) to improve the contact between the anode-protecting layers and the anode active material layer to be protected.
  • the step of implementing anode-protecting layers is conducted by forming a first protecting layer and a second protecting layer of elastomer, followed by laminating the anode active material layer, the first protecting layer, the second protecting layer of elastomer, the optional separator layer, the cathode layer, along with the electrolyte to form the lithium metal secondary battery, wherein an optional (but desirable) compressive stress is applied to improve the contact between the anode-protecting layers and the anode active material layer during or after this laminating step.
  • the elastomer layer has a lithium-ion conductivity from 10 -5 S/cm to 5 x 10 -2 S/cm.
  • the elastomer has a recoverable tensile strain from 10% to 300% (more preferably > 30%, and further more preferably > 50%).
  • the procedure of providing an elastomer contains providing a mixture/blend/composite of an elastomer (sulfonated or un-sulfonated) with an electronically conductive polymer (e.g. polyaniline, polypyrrole, polythiophene, polyfuran, a bi-cyclic polymer, a sulfonated derivative thereof, or a combination thereof), a lithium-ion conducting material, a reinforcement material (e.g. carbon nanotube, carbon nanofiber, and/or graphene), or a combination thereof.
  • an electronically conductive polymer e.g. polyaniline, polypyrrole, polythiophene, polyfuran, a bi-cyclic polymer, a sulfonated derivative thereof, or a combination thereof
  • a lithium-ion conducting material e.g. carbon nanotube, carbon nanofiber, and/or graphene
  • the elastomer contains a lithium ion-conducting material dispersed therein and selected from lithium perchlorate (LiClO 4 ), lithium hexafluorophosphate (LiPF 6 ), lithium borofluoride (LiBF 4 ), lithium hexafluoroarsenide (LiAsF 6 ), lithium trifluoro- methanesulfonate (LiCF 3 SO 3 ), bis-trifluoromethyl sulfonylimide lithium (LiN(CF 3 SO 2 ) 2 ), lithium bis(oxalato)borate (LiBOB), lithium oxalyldifluoroborate (LiBF 2 C 2 O 4 ), lithium nitrate (LiNO 3 ), Li-fluoroalkyl-phosphate (LiPF 3 (CF 2 CF 3 ) 3 ), lithium bisperfluoro-ethylsulfonylimide (LiBETI), lithium bis(LiCl
  • the two anode-protecting layers implemented between the anode active layer and the separator (or the electrolyte) is mainly for the purpose of reducing or eliminating the lithium metal dendrite by providing a more stable Li metal-electrolyte interface that is more conducive to uniform deposition of Li metal during battery charges.
  • These anode-protecting layers also act to block the penetration of any dendrite, if initiated, from reaching the separator or cathode.
  • the second anode-protecting layer being highly elastic, also can shrink or expand conformably, responsive to the thickness increase or decrease of the anode active material layer. Other advantages will become more transparent later.
  • FIG.1 Schematic of a prior art lithium metal battery cell, containing an anode layer (a thin Li foil or Li coating deposited on a surface of a current collector, Cu foil), a porous separator, and a cathode active material layer, which is composed of particles of a cathode active material, a conductive additive (not shown) and a resin binder (not shown).
  • anode layer a thin Li foil or Li coating deposited on a surface of a current collector, Cu foil
  • a porous separator a porous separator
  • a cathode active material layer which is composed of particles of a cathode active material, a conductive additive (not shown) and a resin binder (not shown).
  • a cathode current collector supporting the cathode active layer is also shown.
  • FIG.2 Schematic of a presently invented lithium metal battery cell containing an anode layer (a thin Li foil or Li coating deposited on a surface of a current collector, Cu foil), a lithium ion-conducting material-based 1 st anode-protecting layer, an elastomer-based 2 nd anode- protecting layer, an electrolyte (not shown) or porous separator/electrolyte layer, and a cathode active material layer, which is composed of particles of a cathode active material, a conductive additive (not shown) and a resin binder (not shown).
  • An optional cathode current collector supporting the cathode active layer is also shown.
  • FIG.3 The specific lithium storage specific capacity curves of three lithium cells each having a cathode containing graphene-wrapped V 2 O 5 particles: the first cell having a Garnet-type electrolyte species Li 7-x La 3 Zr 2-x Ta x O 12 –based first anode-protecting layer and a sulfonated elastomer-based 2 nd anode-protecting layer; the second cell having a sulfonated elastomer-based anode-protecting layer only, and the third cell having the species Li 7-x La 3 Zr 2-x Ta x O 12 -based anode-protecting layer only.
  • FIG.4 The specific capacity values of three lithium-LiCoO 2 cells (initially the cell being lithium- free) featuring (1) only a sulfonated PB elastomer-based protecting layer at the anode; (2) only a PEO/LiBH 4 composite-based protection layer at the anode; and (3) double protection layers for the anode containing a PEO/LiBH 4 composite-based 1 st anode- protecting layer and a sulfonated PB-based 2 nd anode-protecting layer, respectively.
  • FIG.5 the discharge capacity curves of four coin cells having the same cathode active material (FeF 3 ), but the 1 st cell having both a PPO/sulfated-ZrO 2 -based 1 st anode-protecting layer and a sulfonated elastomer-based 2 nd anode-protecting layer, the 2 nd cell having an elastomer-based protecting layer only, the 3 rd cell having an ion-conducting
  • FIG.6 Specific capacities of two lithium-FePc (organic) cells, each having Li foil as an anode active material and FePc/RGO mixture particles as the cathode active material (one cell containing double layer-protected anode and the other no anode protection layer).
  • This disclosure is directed at a lithium metal secondary battery, which is preferably based on an organic electrolyte, a polymer gel electrolyte, an ionic liquid electrolyte, a quasi-solid electrolyte, or a solid-state electrolyte.
  • the shape of a lithium metal secondary battery can be cylindrical, square, button-like, etc.
  • the present disclosure is not limited to any battery shape or configuration or any type of electrolyte.
  • the invented lithium secondary battery does not include a lithium-sulfur cell or lithium-selenium cell.
  • the disclosure provides a lithium metal secondary battery, comprising a cathode, an anode, and electrolyte or separator-electrolyte assembly (porous separator and liquid electrolyte, gel electrolyte, quasi-solid electrolyte, etc.) disposed between the cathode and the anode.
  • electrolyte or separator-electrolyte assembly porous separator and liquid electrolyte, gel electrolyte, quasi-solid electrolyte, etc.
  • the anode comprises: (a) a layer of lithium or lithium alloy (in the form of a foil, coating, or multiple particles aggregated together) as an anode active material layer; (b) a first anode-protecting layer having a thickness from 1 nm to 100 mm and comprising a thin layer of a lithium ion-conducting material (having a lithium ion conductivity from 10 -8 S/cm to 5 x 10 -2 S/cm) in physical contact with and in protecting relation to the anode active material layer (e.g. covering the anode active material); and (c) a second anode-protecting layer, in contact with the first protecting layer (e.g.
  • the first anode-protecting layer having a thickness from 1 nm to 100 ⁇ m and comprising an elastomer having a fully recoverable tensile elastic strain from 2% to 1,000%, a lithium ion conductivity from 10 -8 S/cm to 5 x 10 -2 S/cm when measured at room temperature.
  • the foil or coating of lithium or lithium alloy, as the anode active material layer or electrode may be supported by a current collector (e.g. a Cu foil, a Ni foam, a porous layer of nanofilaments, such as membrane, paper, foam, or fabric of graphene sheets, carbon nanofibers, carbon nanotubes, etc. forming a 3D interconnected network of electron-conducting pathways).
  • a current collector e.g. a Cu foil, a Ni foam, a porous layer of nanofilaments, such as membrane, paper, foam, or fabric of graphene sheets, carbon nanofibers, carbon nanotubes, etc. forming a 3D interconnected network of electron-conducting pathways.
  • the first anode-protecting layer partially or, preferably, completely covers the anode active material layer when the battery is made.
  • the lithium ion-conducting material in the first anode-protecting layer comprises a lithium salt selected from lithium perchlorate (LiClO 4 ), lithium
  • LiPF 6 lithium borofluoride
  • LiAsF 6 lithium hexafluoroarsenide
  • LiCF 3 SO 3 lithium trifluoro-methanesulfonate
  • LiN(CF 3 SO 2 ) 2 lithium bis(oxalato)borate
  • LiBOB lithium oxalyldifluoroborate
  • LiNO 3 Li-fluoroalkyl-phosphate
  • LiPF 3 (CF 2 CF 3 ) 3 lithium bisperfluoro- ethylsulfonylimide (LiBETI)
  • lithium bis(trifluoromethanesulfonyl)imide lithium
  • LiTFSI lithium trifluoromethanesulfonimide
  • the lithium ion-conducting material in the first anode-protecting layer may comprise a lithium ion-conducting polymer selected from poly(ethylene oxide) (PEO), polypropylene oxide (PPO), poly(acrylonitrile) (PAN), poly(methyl methacrylate) (PMMA), poly(vinylidene fluoride) (PVDF), poly bis-methoxy ethoxyethoxide-phosphazene, polyvinyl chloride,
  • a lithium ion-conducting polymer selected from poly(ethylene oxide) (PEO), polypropylene oxide (PPO), poly(acrylonitrile) (PAN), poly(methyl methacrylate) (PMMA), poly(vinylidene fluoride) (PVDF), poly bis-methoxy ethoxyethoxide-phosphazene, polyvinyl chloride,
  • PVDF-HFP poly(vinylidene fluoride)-hexafluoropropylene
  • the lithium ion-conducting material comprises an inorganic solid-state electrolyte material having a lithium ion conductivity greater than 10 -6 S/cm.
  • solid electrolyte materials that can be adapted as a lithium ion-conducting material in the presently invented first anode-protecting layer.
  • the solid-state electrolyte material may be selected from a ceramic electrolyte, glass-ceramic electrolyte, glass electrolyte, metal sulfide electrolyte, or a combination thereof.
  • Solid electrolytes that can be implemented in the presently invented first anode-protecting layer include the well-known NASICON-type, Granet-type, LISICON-type, Perovskite-type, sulfide-type, and thin-film solid state electrolytes.
  • the lithium ion-conducting inorganic materials for use in the first anode-protecting layer may be selected from commonly used solid electrolytes, such as, Li 3 N, lithium-phosphorous- oxynitride (LiPON), Li 2 S-based glass, NaSICON-type oxides, Li 0.05-3x La 0.5+x TiO 3 , Li 7 La 3 Zr 2 O 12 , their mixtures with a polymer electrolyte. These materials have demonstrated fairly good Li-ion conductivity.
  • Lithium ion conducting sulfide glasses such as Li 2 S-GeS 2 , Li 2 S-P 2 S 5 , Li 2 S-B 2 S 3 , and Li 2 S-SiS 2 systems can exhibit lithium ion conductivities higher than 10 -4 S/cm at room temperature.
  • lithium thio-silicate Li 2 S-SiS 2 glasses show not only higher conductivity, but also higher glass transition temperatures and easy preparation without vacuum sealing.
  • Li 2 S-SiS 2 glasses are composited with small amounts of ortho-oxosalts, such as Li 3 PO 4 , Li 4 SiO 4 and Li 4 GeO 4 , significantly higher conductivities over 10 -3 S/cm at room temperature and a wide electrochemical window could be obtained. Furthermore, the addition of a small amount of those ortho-oxosalts to the Li 2 S-SiS 2 sulfide system could also improve the glass stability against crystallization. Both high conductivity and high thermal stability of the Li 2 S-SiS 2 -based oxy-sulfide glasses are desirable features for use in the first anode-protecting layer.
  • ortho-oxosalts such as Li 3 PO 4 , Li 4 SiO 4 and Li 4 GeO 4
  • Thio-LiSICON-based electrolytes have high conductivity and low activation energy at room-temperature.
  • glass ceramics with thio-LiSICON structures could exhibit even higher conductivity (3.2 ⁇ 10 -3 S/cm for 70Li 2 S-30P 2 S 5 ), about an order of magnitude higher conductivity at room temperature than their amorphous counterparts.
  • Elemental substitution may be used to increase lithium ion conductivity of solid electrolyte crystals.
  • the conductivity of Li 3 PS 4 crystal could be significantly increased by incorporating phosphorus and germanium into Li 3 PS 4 crystals and the resulting Li 3.25 P 0.75 Ge 0.25 S 4 crystals can exhibit a high conductivity higher than 2.2 ⁇ 10 -3 S/cm at room temperature.
  • Li 10 GeP 2 S 12 with a three-dimensional framework structure could exhibit an extremely high lithium ionic conductivity of 1.2 x 10 -2 S/cm at room temperature.
  • lithium ion-conducting material is the so-called sodium super ionic conductors, such as (NASICON)-type lithium ion conductors, due to their high conductivity ( ⁇ 7 ⁇ 10 -4 S/cm) at room temperature and their stability in both atmosphere and water.
  • NASICON sodium super ionic conductors
  • the substitution of Ti 4+ by smaller sized Al 3+ cation could reduce the unit-cell dimension of NASICON framework, significantly increasing Li + conductivity.
  • the Li 1+x Al x Ti 2-x (PO 4 ) 3 materials with a high conductivity up to 1.3 ⁇ 10 -3 S/cm are commercially available.
  • the Perovskite structure such as Li 0.05-3x La 0.5+x TiO 3 (LLTO) could show a bulk conductivity as high as 1 ⁇ 10 -3 S/cm.
  • Garnet-like structural compounds such as Li 5 La 3 Ta 2 O 12 (LLTa) and Li 7 La 3 Zr 2 O 12 (LLZ), are relatively stable against Li metal.
  • LLTa Li 5 La 3 Ta 2 O 12
  • LLZ Li 7 La 3 Zr 2 O 12
  • their bulk Li- ion conductivity is as high as 5 ⁇ 10 -4 S/cm at room temperature.
  • the lithium ion-conducting material may be formed as a layer of sintered ceramic, glass, glass-ceramic, or sulfide material, etc. as would be normally used as a solid-state electrolyte in a lithium battery.
  • this material may be formed into a thin film (e.g. via sputtering or laser-assisted deposition) deposited on a primary surface of the anode active material layer or a primary surface of the second anode-protecting layer.
  • the layer preferably has a thickness from 2 nm to 2 ⁇ m, more preferably from 2 nm to 100 nm.
  • the solid- state electrolyte material used in the first anode protecting layer may comprise particles of a sintered or un-sintered solid electrolyte material that are bonded together by a resin binder to form a layer of structural integrity.
  • the resin binder is from 1% to 50% of this second anode-protecting layer.
  • This layer may be chemically bonded to the elastomer layer or integral with the elastomer layer.
  • this layer may be an extension of the elastomer layer, but preferably having a different composition than the rest of the elastomer layer; e.g. having a much higher concentration of solid electrolyte material particles or other additives near the skin zone of the elastomer layer than the rest of the elastomer layer.
  • the second anode-protecting layer i.e. the elastomer layer
  • the second anode-protecting layer has a lithium ion conductivity no less than 10 -6 S/cm (typically and desirably from 10 -5 S/cm to 5 x10 -2 S/cm, measured at room temperature), and a thickness from 10 nm to 20 ⁇ m.
  • These conditions are more amenable to allowing lithium ions to migrate in and out of the elastomer layer without much resistance.
  • the elastomer contains a sulfonated or non-sulfonated version of an elastomer selected from natural polyisoprene, synthetic polyisoprene, polybutadiene, chloroprene rubber, polychloroprene, butyl rubber, styrene-butadiene rubber, nitrile rubber, ethylene propylene rubber, ethylene propylene diene rubber, metallocene-based poly(ethylene-co-octene) (POE) elastomer, poly(ethylene-co-butene) (PBE) elastomer, styrene-ethylene-butadiene-styrene (SEBS) elastomer, epichlorohydrin rubber, polyacrylic rubber, silicone rubber, fluorosilicone rubber, perfluoroelastomers, polyether block amides, chlorosulfonated polyethylene, ethylene- vinyl acetate, thermoplastic elasto
  • the second anode-protecting layer (the elastomer layer) is different in composition than the electrolyte per se used in the lithium battery and maintains as a discrete layer (not to be dissolved in the electrolyte) that is disposed between the protected anode active material layer (e.g. Li foil protected by the first protecting layer) and the electrolyte (or electrolyte-separator layer).
  • the second anode-protecting layer may contain a liquid electrolyte that permeates or impregnates into the sulfonated or non-sulfonated elastomer.
  • the two anode-protecting layers provide several unexpected benefits: (a) the formation of dendrite has been essentially eliminated; (b) uniform deposition of lithium back to the anode side is readily achieved; (c) the layers ensure smooth and uninterrupted transport of lithium ions from/to the lithium foil/coating and through the interface between the lithium foil/coating and the protective layer with minimal interfacial resistance; (d) significant reduction in the amount of dead lithium particles near the Li foil; and (e) cycle stability can be significantly improved and cycle life increased.
  • the anode active material (lithium) is deposited in a thin film form or a thin foil form directly onto an anode current collector (e.g. a Cu foil).
  • the battery is a lithium metal battery, lithium sulfur battery, lithium-air battery, lithium-selenium battery, etc. As previously discussed in the Background section, these lithium secondary batteries have the dendrite-induced internal shorting and“dead lithium” issues at the anode.
  • one embodiment of the present disclosure is a lithium metal battery cell containing an anode layer (a thin Li foil or Li coating deposited on a surface of a current collector, such as a layer of graphene foam or a sheet of Cu foil), two anode-protecting layers, a porous separator, and a cathode active material layer, which is composed of particles of a cathode active material, a conductive additive (not shown) and a resin binder (not shown).
  • a cathode current collector e.g.
  • Al foil) supporting the cathode active layer is also shown in FIG.2.
  • the lithium metal or alloy in the anode may be in a form of particles (e.g. surface- protected or surface-stabilized particles of Li or Li alloy).
  • the elastomer in the second anode-protecting layer exhibits an elastic deformation of at least 2% when measured under uniaxial tension.
  • the“elastic deformation” is defined as a deformation of a material (when being mechanically stressed) that is essentially fully recoverable upon release of the load and the recovery is essentially instantaneous.
  • the elastic deformation is preferably greater than 5%, more preferably greater than 10%, further more preferably greater than 30%, and still more preferably greater than 100% but less than 500%.
  • FIG.2 shows a lithium coating pre-existing at the anode when the lithium battery is made, this is but one of several embodiments of the instant disclosure.
  • An alternative embodiment is a lithium battery that does not contain a lithium foil or lithium coating at the anode (only an anode current collector, such as a Cu foil or a
  • the needed lithium to be bounced back and forth between the anode and the cathode is initially stored in the cathode active material (e.g. lithium vanadium oxide Li x V 2 O 5 , instead of vanadium oxide, V 2 O 5 ; or lithium transition metal oxide or phosphate, instead of, say, MoS 2 ).
  • the cathode active material e.g. lithium vanadium oxide Li x V 2 O 5 , instead of vanadium oxide, V 2 O 5 ; or lithium transition metal oxide or phosphate, instead of, say, MoS 2 .
  • Such an alternative battery configuration avoids the need to have a layer of lithium foil or coating being present during battery fabrication.
  • Bare lithium metal is highly sensitive to air moisture and oxygen and, thus, is more challenging to handle in a real battery manufacturing environment.
  • This strategy of pre-storing lithium in the lithiated (lithium- containing) cathode active materials makes all the materials safe to handle in a real manufacturing environment.
  • Cathode active materials such as Li x V 2 O 5 and Li 2 S x , are typically less air-sensitive.
  • the presently invented lithium secondary batteries can contain a wide variety of cathode active materials.
  • the cathode active material layer may contain a cathode active material selected from an inorganic material, an organic material, a polymeric material, or a combination thereof.
  • the inorganic material may be selected from a metal oxide, metal phosphate, metal silicide, metal selenide, transition metal sulfide, or a combination thereof.
  • the inorganic cathode active material may be selected from a lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium vanadium oxide, lithium-mixed metal oxide, lithium iron phosphate, lithium manganese phosphate, lithium vanadium phosphate, lithium mixed metal phosphate, lithium metal silicide, or a combination thereof.
  • the inorganic material as a cathode active material for the lithium battery is selected from a metal fluoride or metal chloride including the group consisting of CoF 3 , MnF 3 , FeF 3 , VF 3 , VOF 3 , TiF 3 , BiF 3 , NiF 2 , FeF 2 , CuF 2 , CuF, SnF 2 , AgF, CuCl 2 , FeCl 3 , MnCl 2 , and combinations thereof.
  • the inorganic material is selected from a lithium transition metal silicate, denoted as Li 2 MSiO 4 or
  • Li 2 Ma x Mb y SiO 4 wherein M and Ma are selected from Fe, Mn, Co, Ni, V, or VO; Mb is selected from Fe, Mn, Co, Ni, V, Ti, Al, B, Sn, or Bi; and x + y £ 1.
  • the inorganic material as a cathode active material is selected from a transition metal dichalcogenide, a transition metal trichalcogenide, or a combination thereof.
  • the inorganic material is selected from TiS 2 , TaS 2 , MoS 2 , NbSe 3 , MnO 2 , CoO 2 , an iron oxide, a vanadium oxide, or a combination thereof.
  • the cathode active material layer may contain a metal oxide containing vanadium oxide selected from the group consisting of VO 2 , Li x VO 2 , V 2 O 5 , Li x V 2 O 5 , V 3 O 8 , Li x V 3 O 8 , Li x V 3 O 7 , V 4 O 9 , Li x V 4 O 9 , V 6 O 13 , Li x V 6 O 13 , their doped versions, their derivatives, and combinations thereof, wherein 0.1 ⁇ x ⁇ 5.
  • the cathode active material layer may contain a metal oxide or metal phosphate, selected from a layered compound LiMO 2 , spinel compound LiM 2 O 4 , olivine compound LiMPO 4 , silicate compound Li 2 MSiO 4 , tavorite compound LiMPO 4 F, borate compound LiMBO 3 , or a combination thereof, wherein M is a transition metal or a mixture of multiple transition metals.
  • a metal oxide or metal phosphate selected from a layered compound LiMO 2 , spinel compound LiM 2 O 4 , olivine compound LiMPO 4 , silicate compound Li 2 MSiO 4 , tavorite compound LiMPO 4 F, borate compound LiMBO 3 , or a combination thereof, wherein M is a transition metal or a mixture of multiple transition metals.
  • the inorganic material is selected from: (a) bismuth selenide or bismuth telluride, (b) transition metal dichalcogenide or trichalcogenide, (c) sulfide, selenide, or telluride of niobium, zirconium, molybdenum, hafnium, tantalum, tungsten, titanium, cobalt, manganese, iron, nickel, or a transition metal; (d) boron nitride, or (e) a combination thereof.
  • the cathode active material layer may contain an organic material or polymeric material selected from poly(anthraquinonyl sulfide) (PAQS), a lithium oxocarbon, 3,4,9,10- perylenetetracarboxylic dianhydride (PTCDA), poly(anthraquinonyl sulfide), pyrene-4,5,9,10- tetraone (PYT), polymer-bound PYT, quino(triazene), redox-active organic material, tetracyanoquinodimethane (TCNQ), tetracyanoethylene (TCNE), 2,3,6,7,10,11- hexamethoxytriphenylene (HMTP), poly(5-amino-1,4-dyhydroxy anthraquinone) (PADAQ), phosphazene disulfide polymer ([(NPS 2 ) 3 ]n), lithiated 1,4,5,8–naphthalenetetra
  • the thioether polymer is selected from poly[methanetetryl-tetra(thiomethylene)] (PMTTM), poly(2,4-dithiopentanylene) (PDTP), a polymer containing poly(ethene-1,1,2,2- tetrathiol) (PETT) as a main-chain thioether polymers, a side-chain thioether polymer having a main-chain consisting of conjugating aromatic moieties, and having a thioether side chain as a pendant, poly(2-phenyl-1,3-dithiolane) (PPDT), poly(1,4-di(1,3-dithiolan-2-yl)benzene) (PDDTB), poly(tetrahydrobenzodithiophene) (PTHBDT), poly[1,2,4,5- tetrakis(propylthio)benzene] (PTKPTB, or poly[3,4(ethylenedithio)thiophene] (
  • the cathode active material layer contains an organic material selected from a phthalocyanine compound, such as copper phthalocyanine, zinc phthalocyanine, tin phthalocyanine, iron phthalocyanine, lead phthalocyanine, nickel phthalocyanine, vanadyl phthalocyanine, fluorochromium phthalocyanine, magnesium phthalocyanine, manganous phthalocyanine, dilithium phthalocyanine, aluminum phthalocyanine chloride, cadmium phthalocyanine, chlorogallium phthalocyanine, cobalt phthalocyanine, silver phthalocyanine, a metal-free phthalocyanine, a chemical derivative thereof, or a combination thereof.
  • a phthalocyanine compound such as copper phthalocyanine, zinc phthalocyanine, tin phthalocyanine, iron phthalocyanine, lead phthalocyanine, nickel phthalocyanine, vanadyl phthalocyanine, fluorochrom
  • the elastomer has a lithium ion conductivity no less than 10 -5 S/cm, more preferably no less than 10 -4 S/cm, further preferably no less than 10 -3 S/cm, and most preferably no less than 10 -2 S/cm.
  • the elastomer comprises from 0.1% to 50% (preferably 1% to 35%) by weight of a lithium ion-conducting additive dispersed in an elastomer matrix material.
  • the elastomer must have a high elasticity (elastic deformation strain value > 2%).
  • An elastic deformation is a deformation that is fully recoverable and the recovery process is essentially instantaneous (no significant time delay).
  • the elastomer composite can exhibit an elastic deformation from 2% up to 1,000% (10 times of its original length), more typically from 5% to 500%, and further more typically from 10% to 300%, and most typically and desirably from 30% to 300%. It may be noted that although a metal typically has a high ductility (i.e. can be extended to a large extent without breakage), the majority of the
  • deformation is plastic deformation (non-recoverable) and only a small amount of elastic deformation (typically ⁇ 1% and more typically ⁇ 0.2%).
  • an elastomer is originally in a monomer or oligomer states that can be cured to form a cross-linked polymer that is highly elastic. Prior to curing, these polymers or oligomers are soluble in an organic solvent to form a polymer solution. An ion-conducting or electron- conducting additive may be added to this solution to form a suspension. This solution or suspension can then be formed into a thin layer of polymer precursor on a surface of the first anode-protecting layer. The polymer precursor (monomer or oligomer and initiator) is then polymerized and cured to form a lightly cross-linked polymer. Alternatively, this thin layer of polymer may be tentatively deposited on a solid substrate (e.g.
  • polymer layer formation can be accomplished by using one of several procedures well-known in the art; e.g. spraying, spray-painting, printing, coating, extrusion-based film-forming, casting, etc.
  • the disclosure also provides a method of manufacturing a lithium battery, the method comprising: (a) providing a cathode active material layer and an optional cathode current collector to support the cathode active material layer; (b) providing an anode active material layer (e.g.
  • a lithium metal or lithium alloy foil or coating containing a lithium metal or lithium alloy foil or coating
  • an optional anode current collector to support the lithium metal or lithium alloy foil or coating
  • the disclosure also provides a method of improving the cycle-life of a lithium metal secondary battery (not including a lithium-sulfur battery or lithium-selenium battery).
  • the method comprises implementing two anode-protecting layers between an anode active material layer and an electrolyte or a porous separator/electrolyte combination.
  • the first anode-protecting layer has a thickness from 1 nm to 100 mm (preferably from 2 nm to 100 nm) and comprises a thin layer of a lithium ion-conducting material having a lithium ion conductivity from 10 -8 S/cm to 5 x 10 -2 S/cm and being in physical contact with the anode active material layer.
  • the second anode-protecting layer comprises an elastomer having a recoverable tensile elastic strain from 2% to 1,000% (preferably from 5% to 300%), a lithium ion conductivity no less than 10 -8 S/cm at room temperature, and a thickness from 1 nm to 100 ⁇ m (preferably from 10 nm to 10 mm).
  • the presently invented lithium secondary battery comprises at least the following layers: an optional anode current collector (e.g. a Cu foil or a graphene foam), an anode active material layer (e.g. a discrete lithium foil, a lithium coating layer, or a layer of lithium particles) supported by the anode current collector (if present), a first anode-protecting layer (e.g.
  • a layer of polymer or inorganic lithium ion-conductor substantially fully covering the anode active material layer and in good contact thereto
  • a second anode-protecting layer substantially fully covering the first anode-protecting layer
  • an electrolyte/separator assembly electrolyte alone or in combination with a layer of porous separator or membrane
  • a cathode active material layer e.g. Al foil, graphene paper sheet, etc.
  • an optional cathode current collector e.g. Al foil, graphene paper sheet, etc.
  • the porous membrane or separator is optional.
  • the step of implementing a first anode-protecting layer may be conducted by spraying a slurry of a conductive material (e.g. particles of an inorganic solid electrolyte and an optional binder resin) dispersed in a liquid (e.g. an organic solvent) onto a primary surface of the anode active material layer, followed by liquid removal.
  • a conductive material e.g. particles of an inorganic solid electrolyte and an optional binder resin
  • a liquid e.g. an organic solvent
  • a free- standing layer of such a lithium ion-conductive material first, which is then laid over a primary surface of the anode active material layer (e.g. a Li foil).
  • the step of implementing a second anode-protecting layer may be conducted by depositing a layer of an elastomer onto one primary surface of the first protective layer that in turn covers the anode active material layer.
  • This step includes optionally compressing the protected anode to improve the contact between the anode-protecting layers and the anode active material layer, followed by combining the protected anode, the separator/electrolyte, and the cathode together to form the lithium metal secondary battery.
  • a good contact between the anode active material layer and the anode-protecting layer is essential to reducing internal resistance.
  • the step of implementing the anode-protecting layers is conducted by (i) preparing a lithium ion-conductive material-protected anode active material layer; (ii) depositing a layer of an elastomer onto one primary surface of a separator to form a coated separator; and (iii) combining the ion-conducting material (first protecting layer)- protected active anode layer, the coated separator, a cathode, and the electrolyte together to form the lithium metal secondary battery.
  • a compressive stress may be advantageously applied (e.g. via press-rolling) to improve the contact between the anode-protecting layer and the anode active material layer to be protected.
  • the step of implementing anode-protecting layers is conducted by forming a first protecting layer of ion-conducting material and a second protecting layer of elastomer, followed by laminating the anode active material layer, the first protecting layer, the second protecting layer of elastomer, the separator layer, the cathode layer, along with the electrolyte to form the lithium metal secondary battery, wherein an optional (but desirable) compressive stress is applied to improve the contact between the anode-protecting layers and the anode active material layer during or after this laminating step.
  • Sulfonation of an elastomer or rubber may be accomplished by exposing the elastomer/rubber to a sulfonation agent in a solution state or melt state, in a batch manner or in a continuous process.
  • the sulfonating agent may be selected from sulfuric acid, sulfonic acid, sulfur trioxide, chlorosulfonic acid, a bisulfate, a sulfate (e.g. zinc sulfate, acetyl sulfate, etc.), a mixture thereof, or a mixture thereof with another chemical species (e.g. acetic anhydride, thiolacetic acid, or other types of acids, etc.).
  • metal sulfates that may be used as a sulfonating agent; e.g. those sulfates containing Mg, Ca, Co, Li, Ba, Na, Pb, Ni, Fe, Mn, K, Hg, Cr, and other transition metals, etc.
  • a triblock copolymer poly(styrene-isobutylene-styrene) or SIBS
  • sulfonated may be performed in solution with acetyl sulfate as the sulfonating agent.
  • acetic anhydride reacts with sulfuric acid to form acetyl sulfate (a sulfonating agent) and acetic acid (a by- product).
  • SIBS is then mixed with the mixture of acetyl sulfate and acetic acid.
  • Such a sulfonation reaction produces sulfonic acid substituted to the para-position of the aromatic ring in the styrene block of the polymer.
  • Elastomers having an aromatic ring may be sulfonated in a similar manner.
  • a sulfonated elastomer also may be synthesized by copolymerization of a low level of functionalized (i.e. sulfonated) monomer with an unsaturated monomer (e.g. olefinic monomer, isoprene monomer or oligomer, butadiene monomer or oligomer, etc.).
  • a low level of functionalized (i.e. sulfonated) monomer with an unsaturated monomer (e.g. olefinic monomer, isoprene monomer or oligomer, butadiene monomer or oligomer, etc.).
  • the elastomeric material may be selected from natural polyisoprene (e.g. cis-1,4-polyisoprene natural rubber (NR) and trans-1,4-polyisoprene gutta-percha), synthetic polyisoprene (IR for isoprene rubber), polybutadiene (BR for butadiene rubber), chloroprene rubber (CR), polychloroprene (e.g.
  • natural polyisoprene e.g. cis-1,4-polyisoprene natural rubber (NR) and trans-1,4-polyisoprene gutta-percha
  • synthetic polyisoprene IR for isoprene rubber
  • BR polybutadiene
  • CR chloroprene rubber
  • polychloroprene e.g.
  • Neoprene, Baypren etc. butyl rubber (copolymer of isobutylene and isoprene, IIR), including halogenated butyl rubbers (chloro butyl rubber (CIIR) and bromo butyl rubber (BIIR), styrene-butadiene rubber (copolymer of styrene and butadiene, SBR), nitrile rubber (copolymer of butadiene and acrylonitrile, NBR), EPM (ethylene propylene rubber, a copolymer of ethylene and propylene), EPDM rubber (ethylene propylene diene rubber, a terpolymer of ethylene, propylene and a diene-component), epichlorohydrin rubber (ECO), polyacrylic rubber (ACM, ABR), silicone rubber (SI, Q, VMQ), fluorosilicone rubber (FVMQ), fluoroelastomers (FKM, and FEPM; such as Viton,
  • Hypalon and ethylene-vinyl acetate (EVA), thermoplastic elastomers (TPE), protein resilin, protein elastin, ethylene oxide-epichlorohydrin copolymer, polyurethane, urethane-urea copolymer, and combinations thereof.
  • TPE thermoplastic elastomers
  • protein resilin protein resilin
  • protein elastin ethylene oxide-epichlorohydrin copolymer
  • polyurethane urethane-urea copolymer
  • the elastomer in the second anode-protecting layer can be mixed with a lithium ion-conducting additive, which contains a lithium salt selected from lithium perchlorate (LiClO 4 ), lithium hexafluorophosphate (LiPF 6 ), lithium borofluoride (LiBF 4 ), lithium hexafluoroarsenide (LiAsF 6 ), lithium trifluoro-methanesulfonate (LiCF 3 SO 3 ), bis-trifluoromethyl sulfonylimide lithium (LiN(CF 3 SO 2 ) 2 ), lithium bis(oxalato)borate (LiBOB), lithium
  • a lithium salt selected from lithium perchlorate (LiClO 4 ), lithium hexafluorophosphate (LiPF 6 ), lithium borofluoride (LiBF 4 ), lithium hexafluoroarsenide (LiAsF 6 ), lithium trifluoro-me
  • LiBF 2 C 2 O 4 lithium nitrate
  • LiPF 3 (CF 2 CF 3 ) 3
  • LiBETI lithium bisperfluoro-ethylsulfonylimide
  • LiTFSI trifluoromethanesulfonimide
  • ionic liquid-based lithium salt an ionic liquid-based lithium salt, or a combination thereof.
  • the elastomer in the second anode-protecting layer may form a mixture, blend, or interpenetrating network with an electron-conducting polymer selected from polyaniline, polypyrrole, polythiophene, polyfuran, a bi-cyclic polymer, derivatives thereof (e.g. sulfonated versions), or a combination thereof.
  • the elastomer may form a mixture, co-polymer, or semi-interpenetrating network with a lithium ion-conducting polymer selected from poly(ethylene oxide) (PEO), polypropylene oxide (PPO), poly(acrylonitrile) (PAN), poly(methyl methacrylate) (PMMA), poly(vinylidene fluoride) (PVDF), poly bis-methoxy ethoxyethoxide-phosphazene, polyvinyl chloride, polydimethylsiloxane, poly(vinylidene fluoride)-hexafluoropropylene (PVDF-HFP), a derivative thereof (e.g. sulfonated versions), or a combination thereof.
  • a lithium ion-conducting polymer selected from poly(ethylene oxide) (PEO), polypropylene oxide (PPO), poly(acrylonitrile) (PAN), poly(methyl methacrylate) (PMMA), poly(vinylidene flu
  • the electrolyte for a lithium secondary cell may be an organic electrolyte, ionic liquid electrolyte, gel polymer electrolyte, solid-state electrolyte (e.g. polymer solid electrolyte or inorganic solid electrolyte), quasi-solid electrolyte or a combination thereof.
  • the electrolyte typically contains an alkali metal salt (lithium salt, sodium salt, and/or potassium salt) dissolved in a solvent.
  • the solvent may be selected from 1,3-dioxolane (DOL), 1,2-dimethoxyethane (DME), tetraethylene glycol dimethylether (TEGDME), poly(ethylene glycol) dimethyl ether
  • PEGDME diethylene glycol dibutyl ether
  • DEGDBE 2-ethoxyethyl ether
  • EEE 2-ethoxyethyl ether
  • sulfone sulfolane
  • ethylene carbonate EC
  • DMC dimethyl carbonate
  • MEC methylethyl carbonate
  • DEC diethyl carbonate
  • ethyl propionate methyl propionate
  • PC propylene carbonate
  • g-BL gamma-butyrolactone
  • AN acetonitrile
  • EA propyl formate
  • MF methyl formate
  • MA fluoroethylene carbonate
  • FEC vinylene carbonate
  • AEC allyl ethyl carbonate
  • hydrofluoroether a room temperature ionic liquid solvent, or a combination thereof.
  • the electrolytic salts to be incorporated into a non-aqueous electrolyte may be selected from a lithium salt such as lithium perchlorate (LiClO 4 ), lithium hexafluorophosphate (LiPF 6 ), lithium borofluoride (LiBF 4 ), lithium hexafluoroarsenide (LiAsF 6 ), lithium trifluoro- methanesulfonate (LiCF 3 SO 3 ), bis-trifluoromethyl sulfonylimide lithium [LiN(CF 3 SO 2 ) 2 ], lithium bis(oxalato)borate (LiBOB), lithium oxalyldifluoroborate (LiBF 2 C 2 O 4 ), lithium nitrate (LiNO 3 ), Li-fluoroalkyl-phosphates (LiPF3(CF 2 CF 3 ) 3 ), lithium bisperfluoroethylsulfonylimide (LiBETI), an
  • LiPF 6 , LiBF 4 and LiN(CF 3 SO 2 ) 2 are preferred for Li-S cells, NaPF 6 and LiBF 4 for Na-S cells, and KBF 4 for K-S cells.
  • the content of aforementioned electrolytic salts in the non-aqueous solvent is preferably 0.5 to 3.0 M (mol/L) at the cathode side and 3.0 to > 10 M at the anode side.
  • the ionic liquid is composed of ions only.
  • Ionic liquids are low melting temperature salts that are in a molten or liquid state when above a desired temperature. For instance, a salt is considered as an ionic liquid if its melting point is below 100°C. If the melting temperature is equal to or lower than room temperature (25oC), the salt is referred to as a room temperature ionic liquid (RTIL).
  • RTIL room temperature ionic liquid
  • the IL salts are characterized by weak interactions, due to the combination of a large cation and a charge-delocalized anion. This results in a low tendency to crystallize due to flexibility (anion) and asymmetry (cation).
  • a typical and well-known ionic liquid is formed by the combination of a 1-ethyl-3- methylimidazolium (EMI) cation and an N,N-bis(trifluoromethane)sulfonamide (TFSI) anion.
  • EMI 1-ethyl-3- methylimidazolium
  • TFSI N,N-bis(trifluoromethane)sulfonamide
  • Ionic liquids are basically composed of organic ions that come in an essentially unlimited number of structural variations owing to the preparation ease of a large variety of their components.
  • various kinds of salts can be used to design the ionic liquid that has the desired properties for a given application. These include, among others, imidazolium, pyrrolidinium and quaternary ammonium salts as cations and bis(trifluoromethanesulfonyl) imide, bis(fluorosulfonyl)imide, and hexafluorophosphate as anions.
  • ionic liquids come in different classes that basically include aprotic, protic and zwitterionic types, each one suitable for a specific application.
  • RTILs room temperature ionic liquids
  • RTILs include, but not limited to, tetraalkylammonium, di-, tri-, and tetra-alkylimidazolium, alkylpyridinium, dialkyl- pyrrolidinium, dialkylpiperidinium, tetraalkylphosphonium, and trialkylsulfonium.
  • RTILs include, but not limited to, BF 4 -, B(CN) 4 -, CH 3 BF 3 -, CH2CHBF 3 -, CF 3 BF 3 -, C 2 F 5 BF 3 -, n-C 3 F 7 BF 3 -, n-C 4 F 9 BF 3 -, PF 6 -, CF 3 CO 2 -, CF 3 SO 3 -, N(SO 2 CF 3 ) 2 -, N(COCF 3 )(SO 2 CF 3 )-, N(SO 2 F) 2 -, N(CN) 2 -, C(CN) 3 -, SCN-, SeCN-, CuCl 2 -, AlCl 4 -, F(HF) 2.3 -, etc.
  • RTILs can possess archetypical properties such as high intrinsic ionic conductivity, high thermal stability, low volatility, low (practically zero) vapor pressure, non-flammability, the ability to remain liquid at a wide range of temperatures above and below room temperature, high polarity, high viscosity, and wide electrochemical windows. These properties, except for the high viscosity, are desirable attributes when it comes to using an RTIL as an electrolyte ingredient (a salt and/or a solvent) in a lithium metal cell.
  • EXAMPLE 1 Ion-conducting polyethylene oxide (PEO) and polypropylene oxide (PPO) polymers containing nanoparticles of ZrO 2 , SiO 2 , or Al 2 O 3 as a first anode-protecting layer Sulfated zirconia was prepared by treating commercial ZrO 2 powders (Aldrich nanopowders, 20–30 nm) with a concentrated (NH 4 ) 2 SO 4 solution. As a first step, the procedure included drying the commercial ZrO 2 powders at 240°C for 24 h in a vacuum oven. Then, the powders were added to an aqueous solution of (NH 4 ) 2 SO 4 and stirred vigorously.
  • PEO polyethylene oxide
  • PPO polypropylene oxide
  • the mixture was subsequently filtered and the collected wet powders dried in a vacuum oven.
  • the dried powders were thermally treated according to the following scheme: (i) heating up to 350°C at 1°C/min; (ii) resting at 350°C for 2 h; (iii) heating up to 550°C at 1°C/min; and (iv) resting at 550°C for 2 h.
  • Particles of SiO 2 and Al 2 O 3 were similarly treated.
  • Sulfated-ZrO 2 , SiO 2 , and Al 2 O 3 , respectively, along with 1-10% by wt. of LiBF 4 were mixed with PEO and PPO using a melt-mixing procedure to obtain polymer composite layers for use as the first anode-protecting layer.
  • EXAMPLE 2 A layer of lithium ion-conducting polymer as a first anode-protecting layer
  • Poly [(oxyethylene) 9 methacrylate]-g-poly(dimethyl siloxane) (POEM-g-PDMS) (70:30) was synthesized by free radical methods.
  • EXAMPLE 3 LiBH 4 as a lithium ion-conducting material for use in a first anode-protecting layer
  • LiBH 4 (Aldrich, >90% purity) and KI (Aldrich, >99.998% purity) were mixed in a mortar at a given molar ratio and pelletized under 1 t/cm 2 .
  • the obtained pellet was sealed in a silica glass tube and sintered under vacuum conditions.
  • Samples with a high LiBH 4 content were sintered at 180°C, while LiBH 4 poor samples were sintered at approximately 250°C. After sintering the samples for 1 h, they were ground and then re-pelletized for the subsequent 8 h of sintering.
  • the LiBH 4 powder was added into a PEO polymer matrix to make a layer of PEO/ LiBH 4 composite-based anode-protecting layer.
  • EXAMPLE 4 Evaporation-induced self-assembly preparation of NASICON-type nanosized solid electrolyte Li 1.4 Al 0.4 Ti 1.6 (PO 4 ) 3 (LATP) as an ion conductor
  • Ethanol soluble LiNO 3 •H 2 O, AlCl 3 , TiCl 4 , and H 3 PO 4 were used as starting materials. The materials were accurately weighed according to the stoichiometric ratio as in
  • Li 1.4 Al 0.4 Ti 1.6 (PO 4 ) 3 Li 1.4 Al 0.4 Ti 1.6 (PO 4 ) 3 .
  • TiCl 4 and AlCl 3 were first dissolved in EtOH and magnetically stirred for 30 min. Then, LiNO 3 •H 2 O and H 3 PO 4 were added to the solution under vigorous stirring for another 2 h.
  • the homogenous sol solution was poured into open Petri dishes and heated at various temperatures (35, 50, and 75°C) in air, allowing the solvent to evaporate until viscous sol-gel was formed.
  • the sol-gel was further aged at 100°C for 6 h to become the dry LATP precursor. Such dried gel was subsequently pyrolyzed in air at 300°C for 3 h, followed by annealing at 800°C for 2 h to obtain LATP powder.
  • EXAMPLE 4 Preparation of Garnet-type Li 7-x La 3 Zr 2-x Ta x O 12 (LLZT) as an ion conductor in a first anode-protecting layer
  • LLZT with a Ta content (x) of 0.45 was synthesized using a conventional solid-state reaction process.
  • Stoichiometric amounts of LiOH-H 2 O (99% with 10% excess was added to account for the evaporation of lithium at high temperatures), La(OH) 3 (99.99%), ZrO 2 (98%) and Ta 2 O 5 (99.9%), which were then ground and mixed by planetary ball-milling with zirconia balls and ethanol for 3 h in a zirconia pot, and then calcined at 900oC for 6 h in air using a tungsten carbide crucible.
  • the calcined powders were ground again by planetary ball-milling for 1 h, and then pressed into pellets at 300 MPa by cold isostatic pressing. Finally, the pellets were sintered at 1150oC for 15 h in air.
  • Precursor material Li 0.5 La 0.5 TiO 3
  • Reagents of Li 2 CO 3 (Alfa 99.9% in purity), La 2 O 3 (Alfa 99.9% purity, heated overnight at 1000°C in air atmosphere) and TiO 2 (Sigma Aldrich 99.9% purity) were mixed in a molar ratio of 1.1:1:2. Considering the potential loss of Li during the evaporation, 10 % excess was used to obtain the desired composition. The mixture was annealed at 1073oK for 6 hours and subsequently at 1473o K for 12 hours in air atmosphere with several intermittent grindings until single phase Li 0.5 La 0.5 TiO 3 was obtained.
  • Polycrystalline oxynitride powder samples were prepared by thermal ammonolysis of synthesized precursor Li 0.5 La 0.5 TiO 3 with flowing ammonia (500 ml/min) for 1, 5 and 10 hours at 1223oK. In addition to the conventional solid-state reaction technique, polycrystalline oxynitride powder samples were also obtained by thermal ammonolysis of oxide precursor.
  • EXAMPLE 6 Sulfonation of triblock copolymer poly(styrene-isobutylene-styrene) or SIBS Both non-sulfonated and sulfonated elastomers are used to build the second anode- protecting layer in the present disclosure.
  • the sulfonated versions typically provide a much higher lithium ion conductivity and, hence, enable higher-rate capability or higher power density.
  • the elastomer matrix can contain a lithium ion-conducting additive, an electron-conducting additive, and/or a lithium metal-stabilizing additive.
  • the S-SIBS samples were dissolved in a mixed solvent of toluene/hexanol (85/15, w/w) with concentrations ranging from 0.5 to 2.5% (w/v). Desired amounts of graphene sheets and a lithium metal-stabilizing additives (e.g. LiNO 3 and lithium trifluoromethanesulfonimide), if not added at an earlier stage, were then added into the solution to form slurry samples.
  • the slurry samples were slot-die coated on a PET plastic substrate to form layers of sulfonated elastomer composite.
  • the lithium metal-stabilizing additives were found to impart stability to lithium metal-electrolyte interfaces.
  • the resulting slurry was spray-dried to obtain sulfonated polybutadiene (PB-SA) composite layers.
  • PB-SA sulfonated polybutadiene
  • SBS Sulfonated styrene-butadiene-styrene triblock copolymer
  • SBS concentration 11 g/100 mL
  • the molar ratio of H 2 O 2 /HCOOH was 1.
  • the product (ESBS) was precipitated and washed several times with ethanol, followed by drying in a vacuum dryer at 60oC.
  • ESBS was first dissolved in toluene to form a solution with a concentration of 10 g/100 mL, into which was added 5 wt.% TEAB/ESBS as a phase transfer catalyst and 5 wt.% DMA/ESBS as a ring-opening catalyst.
  • TEAB tetraethyl ammonium bromide
  • DMA N,N-dimethyl aniline.
  • reaction was terminated by adding a small amount of acetone solution containing antioxidant.
  • the mixture was washed with distilled water and then precipitated by ethanol while being cast into thin films, followed by drying in a vacuum dryer at 50oC.
  • electron-conducting additive e.g. graphene sheets or CNTs
  • lithium ion-conducting additive e.g. Li 2 CO 3 and NaBF 4
  • may be added during various stages of the aforementioned procedure e.g. right from the beginning, or prior to the ring opening reaction.
  • the reaction is autocatalytic and strongly exothermic!
  • the conductive reinforcement material was added before or after this reaction.
  • the resulting slurry was stirred for 1 h, and then most of the solvent was distilled off in vacuum at 35°C.
  • the slurry containing the sulfonated elastomer, along with desired additives, was added with acetonitrile, cast into films, washed with fresh acetonitrile, and dried in vacuum at 35°C to obtain layers of sulfonated elastomers.
  • elastomers e.g. polyisoprene, EPDM, EPR, polyurethane, etc.
  • All the rubbers or elastomers can be directly immersed in a solution of sulfuric acid, a mixture of sulfuric acid and acetyl sulfate, or other sulfonating agent discussed above to produce sulfonated elastomers/rubbers.
  • desired additives may be added at various stages of the procedure.
  • EXAMPLE 10 Lithium battery containing a sulfonated elastomer composite-protected lithium anode and a cathode containing V 2 O 5 particles
  • Cathode active material layers were prepared from V 2 O 5 particles and graphene- embraced V 2 O 5 particles, respectively.
  • the V 2 O 5 particles were commercially available.
  • V 2 O 5 particles were prepared in-house.
  • vanadium pentoxide gels were obtained by mixing V 2 O 5 in a LiCl aqueous solution.
  • the Li + -exchanged gels obtained by interaction with LiCl solution was mixed with a GO suspension and then placed in a Teflon-lined stainless steel 35 ml autoclave, sealed, and heated up to 180°C for 12 h.
  • the green solids were collected, thoroughly washed, ultrasonicated for 2 minutes, and dried at 70°C for 12 h followed by mixing with another 0.1% GO in water, ultrasonicating to break down nanobelt sizes, and then spray-drying at 200°C to obtain graphene-embraced V 2 O 5 composite particulates. Selected amounts of V 2 O 5 particles and graphene-embraced V 2 O 5 particles, respectively, were then each made into a cathode layer following a well-known slurry coating process.
  • the sulfonated elastomer films for use as the second anode-protecting layer were SIBS as prepared in Example 6.
  • Several tensile testing specimens were cut from the film and tested with a universal testing machine. The results indicate that this series of sulfonated elastomer films have an elastic deformation from approximately 150% to 465%.
  • the addition of up to 30% by weight of a conductive reinforcement material (CNTs, graphene, CNFs, etc.) and/or an inorganic additive typically reduces this elasticity down to a reversible tensile strain from 6% to 110%.
  • the working electrodes were prepared by mixing 88% of graphene-embraced V 2 O 5 particles, 5.0 wt. % CNTs, and 7.0 wt. %
  • PVDF polyvinylidene fluoride
  • NMP N-methyl-2-pyrrolidinoe
  • Electrochemical measurements were carried out using CR2032 (3V) coin-type cells with lithium metal as the counter electrode (actually an anode of a Li-transition metal oxide cell), Celgard 2400 membrane as separator, and 1 M LiPF 6 electrolyte solution dissolved in a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) (EC-DEC, 1:1 v/v).
  • the cell assembly was performed in an argon-filled glove-box.
  • the CV measurements were carried out using a CH- 6 electrochemical workstation at a scanning rate of 1 mV/s.
  • the electrochemical performance of the cell featuring sulfonated elastomer composite binder and that containing PVDF binder were evaluated by galvanostatic charge/discharge cycling at a current density of 50 mA/g using an Arbin Electrochemical Testing Station.
  • first cell having a Garnet-type Li 7-x La 3 Zr 2-x Ta x O 12 –based first anode-protecting layer and a sulfonated elastomer-based 2 nd anode-protecting layer; the second cell having a sulfonated elastomer-based anode-protecting layer only, and the third cell having a Li 7-x La 3 Zr 2-x Ta x O 12 -based anode- protecting layer only.
  • the presently invented approach of double protection layers provides the battery cell with the most stable and highest specific capacity for a large number of cycles.
  • the sulfonated elastomer-based protective layer appears to be capable of reversibly deforming to a great extent without breakage when the lithium foil decreases in thickness during battery discharge.
  • the two protective layers also prevent the continued reaction between liquid electrolyte and lithium metal at the anode, reducing the problem of continuing loss in lithium and electrolyte.
  • EXAMPLE 11 Sulfonated elastomer implemented in the anode of a lithium-LiCoO 2 cell (initially the cell anode has an ultra-thin lithium layer, ⁇ 1 ⁇ m thick)
  • the sulfonated elastomer as a lithium-protecting layer was based on the sulfonated polybutadiene (PB) prepared according to a procedure used in Example 7. Tensile testing was also conducted on the sulfonated elastomer films (without the conductive reinforcement material). This series of sulfonated elastomers can be elastically stretched up to approximately 135% (having some lithium salt or conductive reinforcement material dispersed therein) or up to 770% (with no additive).
  • FIG.4 shows that the cell having a PEO/LiBH 4 composite-based 1 st anode-protecting layer (prepared in Example 3) and a sulfonated PB-based 2 nd anode-protecting layer offers the most stable cycling behavior.
  • the sulfonated elastomer also acts to isolate the electrolyte from the lithium coating yet still allowing for easy diffusion of lithium ions.
  • EXAMPLE 12 Li metal cells containing transition metal fluoride nanoparticle-based cathode and a sulfonated elastomer-based anode-protecting layer
  • This sulfonated elastomer layer was based on sulfonated styrene-butadiene-styrene triblock copolymer (SBS). Tensile testing was conducted on some cut pieces of these layers.
  • This series of cross-linked polymers can be elastically stretched up to approximately 820% (without any additive). The addition of additives results in an elasticity of approximately 5% (e.g. with 20% carbon black) to 160% (e.g. with 5% graphene sheets, as a conductive additive).
  • FIG.5 Shown in FIG.5 are the discharge capacity curves of four coin cells having the same cathode active material (FeF 3 ), but the 1 st cell having both a PPO/sulfated-ZrO 2 -based 1 st anode- protecting layer and a sulfonated elastomer-based 2 nd anode-protecting layer, the 2 nd cell having an elastomer-based protecting layer only, the 3 rd cell having a PPO/sulfated-ZrO 2 -based anode- protecting layer only, and the 4 th cell having no protective layer.
  • the double layer protection strategy provides the best protection against capacity decay of a lithium metal battery.
  • the elastomer layer appears to be capable of reversibly deforming without breakage when the anode layer expands and shrinks during charge and discharge.
  • the elastomer layer and the lithium ion-conducting PPO/sulfated-ZrO 2 -based layer also prevent continued reaction between the liquid electrolyte and the lithium metal. No dendrite-like features were found with the anode being protected by a sulfonated elastomer composite. This was confirmed by using SEM to examine the surfaces of the electrodes recovered from the battery cells after some numbers of charge-discharge cycles.
  • EXAMPLE 13 Li-organic cell containing a naphthalocyanine/reduced graphene oxide (FePc/RGO) particulate cathode and a protected Li foil anode
  • FePc/graphene sheets Particles of combined FePc/graphene sheets were obtained by ball-milling a mixture of FePc and RGO in a milling chamber for 30 minutes.
  • the resulting FePc/RGO mixture particles were potato-like in shape.
  • Two lithium cells were prepared, each containing a Li foil anode, a porous separator, and a cathode layer of FePc/RGO particles; one cell containing two anode- protecting layers and the other no protecting layer.
  • FIG.6 The cycling behaviors of these 2 lithium cells are shown in FIG.6, which indicates that the lithium-organic cell having a sulfonated elastomer-based 2 nd protection layer and a 1 st protecting layer containing a lithium ion-conducting polymer prepared in Example 2 exhibits a significantly more stable cycling response.
  • These protective layers reduce or eliminate the undesirable reactions between the lithium metal and the electrolyte, yet the elastomer layer itself remains in ionic contact with the protected lithium metal and is permeable to lithium ions. This approach has significantly increased the cycle life of all lithium-organic batteries.
  • EXAMPLE 14 Effect of lithium ion-conducting additive in a sulfonated elastomer composite
  • a wide variety of lithium ion-conducting additives were added to several different polymer matrix materials to prepare anode protection layers.
  • the lithium ion conductivity vales of a group of sulfonated elastomer matrix composite materials are summarized in Table 1 below.
  • these composite materials are suitable anode-protecting layer materials provided that their lithium ion conductivity at room temperature is no less than 10 -6 S/cm. With these materials, lithium ions appear to be capable of readily diffusing through the protective layer having a thickness no greater than 1 ⁇ m.
  • a lithium ion conductivity at room temperature of these sulfonated elastomer composites no less than 10 -4 S/cm would be required.
  • Table 1 Lithium ion conductivity of various sulfonated elastomer composite compositions as a lithium metal-protecting layer.
  • cycle life of a battery In lithium-ion battery industry, it is a common practice to define the cycle life of a battery as the number of charge-discharge cycles that the battery suffers a 20% decay in capacity based on the initial capacity measured after the required electrochemical formation. Summarized in Table 2 below are the cycle life data of a broad array of batteries featuring an anode with or without an anode-protecting polymer layer. Table 2: Cycle life data of various lithium secondary (rechargeable) batteries.
  • the two anode protecting layers are surprisingly effective in alleviating the problems of lithium metal dendrite formation and lithium metal-electrolyte reactions that otherwise lead to rapid capacity decay and potentially internal shorting and explosion of the lithium secondary batteries.
  • the elastomer layer is capable of expanding or shrinking congruently or conformably with the anode active material layer. This capability helps to maintain a good contact between the current collector (or the lithium film itself) and the protective layer(s), enabling uniform re-deposition of lithium ions without interruption.
  • the anode-protecting layers appear to be capable of performing at least the following three functions:
  • the elastomer layer helps to maintain a good contact between a Li metal layer (e.g. lithium metal foil, as the anode active material, protected by a layer of graphene paper) and an electrolyte phase (e.g. an electrolyte/separator assembly or an electrolyte phase) when the Li metal layer decreases in thickness (e.g. due to dissolution of Li in the electrolyte when the battery is discharged) or increases in thickness (e.g. due to re-deposition of lithium metal back to the Cu foil or the lithium metal layer when the battery is recharged).
  • the elastomer can expand and shrink responsive to the shrinkage and expansion of the anode active material layer. Such a conformal or congruent expansion/shrinkage of the elastomer layer helps to eliminate the potential gap between the anode active material layer and the electrolyte, thereby maintaining the lithium ion migration paths required of an operational Li metal battery.
  • the 1 st anode-protecting layer (covering the lithium metal), having a lithium ion-conducting material serving essentially as an artificial solid-electrolyte interface (SEI) layer, helps to maintain the interfacial stability and reduce or eliminate continued breakage and reformation of the SEI layer (which otherwise would continue to consume lithium ions and the electrolyte).
  • SEI solid-electrolyte interface

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Abstract

L'invention concerne une batterie secondaire au lithium, comprenant une cathode, une anode et un séparateur ou électrolyte poreux. L'anode comprend : (a) une couche active d'anode contenant une couche de lithium ou d'alliage de lithium, sous la forme d'une feuille, d'un revêtement ou de multiples particules agrégées ensemble, en tant que matériau actif d'anode ; (b) une première couche de protection d'anode ayant une épaisseur allant de 1 nm à 100 µm (de préférence < 1 µm et plus préférablement < 100 nm) et comprenant un matériau conducteur d'ions de lithium ayant une conductivité des ions de lithium allant de 10-8 S/cm à 5 x 10-2 S/cm ; et (c) une deuxième couche de protection d'anode ayant une épaisseur allant de 1 nm à 100 µm et comprenant un élastomère ayant une déformation élastique de traction complètement récupérable allant de 2 % à 1 000 % et une conductivité d'ions de lithium allant de 10-8 S/cm à 5 x 10-2 S/cm. La présente invention concerne également un procédé d'amélioration de la stabilité et du cycle de vie de l'anode d'une batterie secondaire au lithium-métal.
PCT/US2019/038455 2018-09-06 2019-06-21 Batterie secondaire au lithium-métal contenant une anode au lithium protégée WO2020050896A1 (fr)

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CN113437257A (zh) * 2021-06-26 2021-09-24 宁德时代新能源科技股份有限公司 锂金属负极极片、电化学装置及电子设备
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