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WO2001061772A1 - Extraction de plastifiants a partir de cellules electrochimiques - Google Patents

Extraction de plastifiants a partir de cellules electrochimiques Download PDF

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Publication number
WO2001061772A1
WO2001061772A1 PCT/US2001/003365 US0103365W WO0161772A1 WO 2001061772 A1 WO2001061772 A1 WO 2001061772A1 US 0103365 W US0103365 W US 0103365W WO 0161772 A1 WO0161772 A1 WO 0161772A1
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Prior art keywords
extraction solvent
plasticizer
electrochemical cell
current collector
cell precursor
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Ceased
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PCT/US2001/003365
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English (en)
Inventor
Tracy E. Kelley
Chariclea A. Scordilis-Kelley
Porter H. Mitchell
Jeremy Barker
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Valence Technology Inc
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Valence Technology Inc
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Priority to AU2001233231A priority Critical patent/AU2001233231A1/en
Publication of WO2001061772A1 publication Critical patent/WO2001061772A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0409—Methods of deposition of the material by a doctor blade method, slip-casting or roller coating
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0416—Methods of deposition of the material involving impregnation with a solution, dispersion, paste or dry powder
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/043—Processes of manufacture in general involving compressing or compaction
    • H01M4/0435—Rolling or calendering
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/443—Particulate material
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • This invention relates to fabricating electrochemical (electrolytic) cells and, more particularly, to a method for removing plasticizer from an electrochemical cell (or a precursor thereof) by extraction.
  • Non-aqueous lithium electrochemical cells typically include an anode, a separator containing a lithium electrolyte prepared from a lithium salt dissolved in one or more organic solvents and a cathode of an electrochemically active material, typically a chalcogenide of a transition metal.
  • an electrochemically active material typically a chalcogenide of a transition metal.
  • Li x C Li x C
  • a carbon anode such as coke or graphite intercalated with lithium ions to form Li x C.
  • lithium passes from the carbon through the electrolyte to the cathode where it is taken up just as in a cell with a metallic lithium anode.
  • the lithium is transferred back to the anode where it reintercalates into the carbon.
  • melting of the anode does not occur even under abuse conditions.
  • Non-aqueous lithium electrochemical cells are discussed in U.S. Patent Nos. 4,472,487, 4,668,595 and 5,028,500.
  • Electrochemical cells typically include anode and cathode current collectors.
  • a preferred material for the cathode current collector is aluminum.
  • the present invention provides an efficient method for removing plasticizers from an electrochemical cell precursor by solvent extraction whereby the aluminum cathode current collector remains essentially unaffected.
  • the invention is based in part on the recognition that the galvanic current that exists in the electrochemical cell precursor between either the carbon formulation of the grid coating of the current collector or the small potential difference between the cathode and anode of the precursor apparently increases the corrosion rate of the metal (e.g., aluminum) current collector.
  • the invention is directed to a method for removing plasticizer from an electrode/current collector assembly that comprises contacting an electrode/current collector assembly comprising (i) a current collector made from a metal that is selected from the group consisting of aluminum, copper, aluminum-copper alloys, stainless steel, and nickel, and (ii) an electrode composition comprising an electrode material, a polymer, and a plasticizer, with an alcohol extraction solvent that is selected from the group consisting of ethanol, propanol, butanol, and pentanol, and mixtures thereof.
  • the invention is directed to a method for removing plasticizer from an electrochemical cell precursor, that comprises contacting an electrochemical cell precursor comprising (i) an anode composition comprising an anodic material, a first polymer, and a first plasticizer; (ii) a cathode composition comprising a cathode active material, a second polymer, and a second plasticizer; and (iii) a separator comprising a third polymer and third plasitcizer, with an alcohol extraction solvent that is selected from the group consisting of ethanol, propanol, butanol, and pentanol, and mixtures thereof, wherein at least one of the anode composition or cathode composition is attached to a current collector.
  • the invention is directed to a method of preparing an electrochemical cell, which method includes the steps of:
  • Preferred solvents include the various isomeric forms of the alcohols including, for example, n-propanol, iso-propanol, n-butanol, sec-butanol, tert-butanol, isobutanol, n-pentanol, and iso-pentanol.
  • the extraction solvent is isopropanol and the plasticizers are dibutyl phthalate.
  • the method includes the step of applying ultrasound waves to the electrode/current collector assembly or electrochemical cell precursor to facilitate the removal of the plasticizers.
  • the polymer(s) used in this invention is selected from the group consisting of copolymers of vinylidene difluoride and hexafluoropropylene, poly vinylidene difluoride, copolymers of ethylene and acrylic acid, copolymers of ethylene and vinyl acetate, and mixtures thereof. More preferably, the polymer is a copolymer of vinylidene difluoride and hexafluoropropylene .
  • the plasticizer(s) employed in this invention is selected from the group consisting of dialkyl phthalates, wherein each alkyl group independently contains 1 to about 12 carbon atoms; trisbutoxyethyl
  • the plasticizer is a dialkyl phthalate selected from the group consisting of dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate and mixtures thereof. Still more preferably, the plasticizer is dibutyl phthalate.
  • the extraction solvent employed may also include solvent(s) selected from the group consisting of alkanes and cycloalkanes having 5 to about 12 carbon atoms; aliphatic alcohols having 5 to about 12 carbon atoms; haloalkanes and haloalkenes having 1 to about 6 carbon atoms; dialkyl ethers and cycloalkyl ethers having 4 to about 12 carbon atoms; dialkyl formates, wherein each alkyl group independently contains 1 to about 6 carbon atoms; diaikyl carbonates, wherein each alkyl group independently contains 1 to about 6 carbon atoms; and mixtures thereof.
  • solvent(s) selected from the group consisting of alkanes and cycloalkanes having 5 to about 12 carbon atoms; aliphatic alcohols having 5 to about 12 carbon atoms; haloalkanes and haloalkenes having 1 to about 6 carbon atoms; dialkyl ethers and cycloalkyl ethers
  • the electrolyte solvent preferably comprises one or more organic carbonates. More preferably, the electrolyte solvent comprises a mixture of ethylene carbonate and dimethyl carbonate.
  • the salt used in this invention is preferably an alkali metal salt of an anion selected from the group consisting of I “ , Br “ , SCN “ , ClO 4 ", BF 4 “ , PF 6 “ , AsF 6 ⁇ CF 3 COO ⁇ CF 3 SO 3 -, and N(SO 2 CF 3 ) 2 -.
  • the present invention provides an improved method of extracting plasticizer from an electrochemical cell precursor whereby the structural integrity of the metal current collector(s) is not adversely affected as with some prior art techniques.
  • the extraction solvent is an aliphatic alcohol selected from the group consisting of ethanol, propanol, butanol, and pentanol and mixtures thereof.
  • Preferred solvents include the various isomeric forms of the alcohols including, for example, n-propanol, isopropanol, n-butanol, sec-butanol, tert-butanol, isobutanol, n-pentanol, and iso-pentanol.
  • the extraction solvent is isopropanol; the presence of methanol should be avoided.
  • the polymer network of these components has a stable porous structure.
  • the precursor is activated by the addition of an electrolyte solution comprising electrolyte solvents and salts. Electrochemical cells so fabricated will demonstrate superior electrochemical performance.
  • ultrasound waves are applied to facilitate the extraction process.
  • Preferred electrochemical cells comprise a cathode comprising a cathode active material and an intercalation-based carbon anode, with each electrode capable of reversibly incorporating (e.g., intercalating) an alkali metal ion, and a separator containing an electrolyte solution comprising an organic electrolyte solvent and a salt of the alkali metal.
  • Each electrode has a current collector.
  • Particularly preferred electrochemical cells and batteries use lithium and salts thereof.
  • the anode comprises an anode film that is laminated onto one or both sides of a current collector which is a thin metal foil or grid.
  • each anode film is from about 100 ⁇ m to about 250 ⁇ m in thickness, preferably about 110 ⁇ m to about 200 ⁇ m, and more preferably about 125 ⁇ m to about 175 ⁇ m.
  • the cathode preferably comprises a cathode film that is laminated onto one or both sides of the current collector which is a thin foil or grid.
  • each cathode film is from about 100 ⁇ m to about 200 ⁇ m in thickness, preferably about 130 ⁇ m to about 175 ⁇ m, and more preferably about 140 ⁇ m to about 165 ⁇ m.
  • the anode and cathode each also preferably include a current collector that comprises, for example, a screen, grid, expanded metal, woven or non-woven fabric formed from an electron conductive material such as metals or alloys.
  • the current collector has a thickness from about 25 ⁇ m to about 75 ⁇ m, preferably about 35 ⁇ m to about
  • Each current collector is also connected to a current collector tab which extends from the edge of the current collector.
  • the anode tabs are preferably welded together and connected to a copper or nickel lead.
  • the cathode tabs are similarly welded and connected to a lead. External loads can be electrically connected to the leads.
  • Current collectors and tabs are described in U.S. Patent 4,925,752, 5,011,501, and 5,326,653, which are incorporated herein.
  • ultrasound waves or “ultrasonic waves” or “ultrasonic energy” refer to sound waves having a frequency above about 20,000 hertz.
  • plasticizer refers to an organic solvent, with limited solubility of polymers, that facilitates the formation of porous polymeric structures.
  • porous structure is meant that upon extraction of the plasticizer the polymer remains as a porous mass.
  • Suitable plasticizers have high boiling points typically from about 100°C to about 350°C. A number of criteria are important in the choice of plasticizer including compatibility with the components of the electrochemical cell precursor, processability, low polymer solubility and extractability.
  • Preferred plasticizers are selected from the group consisting of dialkyl phthalates, wherein each alkyl group independently contains 1 to about 12 carbon atoms; trisbutoxyethyl phosphate; propylene carbonate; ethylene carbonate; and mixtures thereof.
  • Particularly preferred plasticizers include, by way of example, dialkyl phthalates selected from the group consisting of dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate and mixtures thereof.
  • Other preferred plasticizers include, for example, acetates, glymes and low molecular weight polymers.
  • the weight ratio of plasticizer to polymer is from about 1 to about 50, more preferably about 10 to about 30, and most preferably about 20 to about 25.
  • extraction solvent refers a low boiling organic solvent in which the plasticizer is soluble or miscible and the polymer is essentially insoluble (i.e., a non-solvent for the polymer).
  • Extraction solvents used in the present invention include the alcohols described above. Other extraction solvents can also be included and these have boiling points of less than about 150°C, more preferably less than 100°C, and still more preferably less than 75 °C. Additionally, the extraction solvent preferably has a low viscosity, preferably less than about 2.0 cp at 25 °C, more preferably less than about 1.0 cp at 25 °C. Preferred solvents also have low toxicity and a low fire hazard risk.
  • the other extraction solvents are selected from the group consisting of alkanes and cycloalkanes having 5 to about 12 carbon atoms; aliphatic alcohols having 5 to about 12 carbon atoms; haloalkanes and haloalkenes having 1 to about 6 carbon atoms; dialkyl ethers and cycloalkyl ethers having 4 to about 12 carbon atoms; dialkyl formates, wherein each alkyl group independently contains 1 to about 6 carbon atoms; dialkyl carbonates, wherein each alkyl group independently contains 1 to about 6 carbon atoms; and mixtures thereof.
  • extraction solvents include diethyl ether, petroleum ether, propanes, butanes, pentanes, hexanes, cyclohexane, dichloromethane, trichloroethylene, fluorotrichloromethane, chlorotrifluoromethane, carbon tetrafluoride, dichlorofluromethane, chlorodifluoromethane, trifluoromethane, 1,2-dichlorotetrafluoroethane, hexafluoroethane, trichloroethane, and the like, and mixtures thereof.
  • electrochemical cell precursor or “electrolytic cell precursor” refers to the structure of the electrochemical cell prior to the addition of the electrolyte solution.
  • the prec ⁇ rsor typically comprises (each in precursor form) an anode, a cathode, and separator that typically comprises a polymeric matrix.
  • the anode and/or cathode may each include a current collector.
  • activation refers to the placement of an inorganic salt and electrolyte solvent into an electrochemical cell precursor. After activation, the electrochemical cell is charged by an external energy source prior to use.
  • electrochemical cell or “electrolytic cell” refers to a composite structure containing an anode, a cathode, and an ion-conducting electrolyte interposed therebetween.
  • battery refers to two or more electrochemical cells electrically interconnected in an appropriate series/parallel arrangement to provide the required operating voltage and current levels.
  • salt refers to any salt, for example, an morgamc salt, which is suitable for use in a non-aqueous electrolyte.
  • suitable inorganic ion salts are alkali metal salts of less mobile anions of weak bases having a large anionic radius. Examples of such anions are I ' , Br, SCN ' , C V, BF 4 ⁇ PF 6 ⁇ AsF 6 " , CF 3 COO ⁇ CF 3 SO 3 ⁇ N(SO 2 CF 3 ) 2 " , and the like.
  • suitable inorganic ion salts include LiClO 4 , LiSCN, LiBF 4 , LiAsF 6 , LiCF 3 SO 3 , LiPF 6 , (CF 3 SO 2 ) 2 NLi, (CF 3 SO 2 ) 3 CLi, NaSCN, and the like.
  • the inorganic ion salt preferably contains at least one cation selected from the group consisting of Li, Na, Cs, Rb, Ag, Cu, Mg and K.
  • the electrolyte typically comprises from about 5 to about 25 weight percent of the inorganic ion salt based on the total weight of the electrolyte; preferably, from about 10 to 20 weight percent; and even more preferably from about 10 to about 15 weight percent.
  • the percentage of salt depends on the type of salt and electrolytic solvent employed.
  • compatible electrolyte solvent or “electrolytic solvent,” or in the context of components of the non-aqueous electrolyte, just “solvent,” is a low molecular weight organic solvent added to the electrolyte and/or the cathode composition, which may also serve the purpose of solvating the inorganic ion salt.
  • the solvent is any compatible, relatively non-volatile, aprotic, relatively polar, solvent.
  • these materials have boiling points greater than about 85 °C to simplify manufacture and increase the shelf life of the electrolyte/battery.
  • Typical examples of solvent are mixtures of such materials as dimethyl carbonate, diethyl carbonate, propylene carbonate, ethylene carbonate, methyl ethyl carbonate, gamma- butyrolactone, triglyme, tetraglyme, dimethylsulfoxide, dioxolane, sulfolane, and the like.
  • a sequestering agent such as a crown ether, is added in the electrolyte.
  • the electrolytic solvent preferably comprises a mixture of ethylene carbonate and dimethyl carbonate.
  • the electrolytic solvent preferably comprises a mixture of propylene carbonate and triglyme.
  • organic carbonate refers to hydrocarbyl carbonate compounds of no more than about 12 carbon atoms and which do not contain any hydroxyl groups.
  • the organic carbonate is an aliphatic carbonate and more preferably a cyclic aliphatic carbonate.
  • Suitable cyclic aliphatic carbonates for use in this invention include l,3-dioxolan-2-one (ethylene carbonate); 4-methyl-l,3-dioxolan-2-one (propylene carbonate); 4,5-dimethyl-l,3-dioxolan-2-one; 4- ethyl-1 ,3-dioxolan-2-one; 4,4-dimethyl-l ,3-dioxolan-2-one; 4-methyl-5- ethyl- l,3-dioxolan-2-one; 4,5-diethyl-l,3-dioxolan-2-one; 4,4-diethyl-l,3- dioxolan-2-one; l,3-dioxan-2-one; 4,4-dimethyl-l, 3-dioxan-2-one; 5,5-di- methyl-1 ,3-dioxan-2-one; 5-methyl-l ,3-
  • cyclic aliphatic carbonates are commercially available such as propylene carbonate and ethylene carbonate.
  • the cyclic aliphatic carbonates can be readily prepared by well known reactions. For example, reaction of phosgene with a suitable alkane- ⁇ , ⁇ -diol (dihydroxy alkanes having hydroxyl substituents on adjacent carbon atoms) or an alkane-c , ⁇ -diol (dihydroxy alkanes having hydroxyl substituents on carbon atoms in a 1,3 relationship) yields an a cyclic aliphatic carbonate for use within the scope of this invention. See, for instance, U.S. Patent No. 4,115,206, which is incorporated herein by reference in its entirety.
  • the cyclic aliphatic carbonates useful for this invention may be prepared by transesterification of a suitable alkane- ⁇ , ⁇ -diol or an alkane- ⁇ , ⁇ -diol with, e.g., diethyl carbonate under transesterification conditions. See, for instance, U.S. Patent Nos. 4,384,115 and 4,423,205 which are incorporated herein by reference in their entirety. Additional suitable cyclic aliphatic carbonates are disclosed in U.S. Patent No. 4,747,850 which is also incorporated herein by reference in its entirety.
  • the anode typically comprises a compatible anodic material which is any material which functions as an anode in an electrolytic cell.
  • Such compatible anodic materials include, by way of example, lithium, lithium alloys, such as alloys of lithium with aluminum, mercury, manganese, iron, zinc, intercalation based anodes such as those employing carbon, tungsten oxides, and the like.
  • Preferred anodes include lithium intercalation anodes employing carbon materials such as graphite, cokes, mesocarbons, disordered carbon, hard carbon and the like.
  • the anode may also include an electron conducting material such as carbon black.
  • Such carbon intercalation based anodes typically include a polymeric binder and extractable plasticizer suitable for forming a bound porous composite having a molecular weight of from about 1,000 to 5,000,000.
  • Preferred polymeric binders include, but are not limited to, copolymers of vinylidene difluoride and hexafluoropropylene, polyvinylidene difluoride, copolymers of ethylene and acrylic acid, copolymers of ethylene and vinyl acetate, and mixtures thereof.
  • suitable polymeric binders include EPDM (ethylene propylene diamine termonomer) and the like.
  • Especially preferred polymers are copolymers of vinylidenedifluoride and hexafluoropropylene.
  • the polymer or copolymer employed has a high average molecular weight.
  • the average molecular weight is between 50,000 to 750,000, more preferably 50,000 to 200,000, and most preferably 50,000 to 120,000.
  • polymer or copolymer has a narrow molecular weight have range.
  • Polyvinylidene difluoride (PVDF) and hexafluoropropylene (HFP) copolymers are common binder materials, and are the binder materials which are generally useful in the subject invention.
  • the copolymer generally comprises about 75 to 92% (by weight) of the PVDF, and about 8 to 25 % HFP.
  • the copolymer comprises about 85 to 90% of the PVDF, and about 10 to 15% HFP.
  • One especially preferred, commercially available copolymer material is KYNAR. Flex 2801 (Elf Atochem North America, Philadelphia, PA), which provides an 88:12 ratio of PVDF:HFP.
  • Inorganic filler adjuncts, such as fumed alumina or fumed silica, are added as desired to provide structural stability to the binder and provide a film having desirable qualities.
  • the cathode typically comprises a compatible cathodic material (i.e., insertion compounds) which is any material which functions as a positive pole in an electrolytic cell.
  • a compatible cathodic material i.e., insertion compounds
  • Such compatible cathodic materials include, by way of example, transition metal oxides, sulfides, and selenides, including lithiated compounds thereof.
  • Representative materials include cobalt oxides, manganese oxides, molybdenum oxides, vanadium oxides, sulfides of titanium, molybdenum and niobium, the various chromium oxides, copper oxides, lithiated cobalt oxides, e.g., LiCoO 2 and LiCoVO 4 , lithiated manganese oxides, e.g., LiMn 2 O 4 , lithiated nickel oxides, e.g., LiNiO 2 and LiNiVO 4> and mixtures thereof.
  • Cathode-active material blends of Li x Mn 2 O 4 (spinel) is described in U.S. Patent 5,429,890 which is incorporated herein.
  • the blends can include Li x Mn 2 O 4 (spinel) and at least one lithiated metal oxide selected from
  • Blends can also include Li y - ⁇ -MnO 2 (0 ⁇ y ⁇ 1) which has a hollandite-type structure and is described in U.S. Patent 5,561,007 which is incorporated herein by reference.
  • the compatible cathodic material is mixed with an electroconductive material including, by way of example, graphite, powdered carbon, powdered nickel, metal particles, conductive polymers (i.e., characterized by a conjugated network of double bonds like polypyrrole and poly acetylene), and the like, and a polymeric binder to form under pressure a positive cathodic plate.
  • an electroconductive material including, by way of example, graphite, powdered carbon, powdered nickel, metal particles, conductive polymers (i.e., characterized by a conjugated network of double bonds like polypyrrole and poly acetylene), and the like
  • a polymeric binder for the cathode can be the same as those used in the anode.
  • the term "separator” refers to the ionic medium between the anode and cathode.
  • the electrolyte/separator is typically a solid electrolyte, or separator and liquid electrolyte.
  • Solid electrolytes typically comprise polymeric matrices which contain an ionic conductive medium.
  • Liquid electrolytes typically comprise a solvent and an alkali metal salt which form an ionically conducting liquid. In this latter case, the separation between the anode and cathode is maintained, for example, by a relatively inert layer of material.
  • a separator membrane may be a commercially available separator made of glass fiber, porous polypropylene or porous polyethylene. Such separators include Type A/E glass fiber filter (Gelman Sciences, Ann Arbor, MI), and Celgard (Hoechst-Celanese Corp., NY, NY).
  • Preferred polymeric (or electrolyte membranes) are produced using a casting process in which a carrier liquid is removed to form a flexible sheet.
  • An alternate preferred method produces polymeric electrolyte membranes by extrusion processes.
  • Suitable polymeric electrolyte membranes provide a porous structure, permeated with a plasticizer, upon casting or curing.
  • Suitable solid polymeric matrices include solid matrices formed from organic polymers, inorganic polymers or a mixture of organic polymers with inorganic non-polymeric materials.
  • the solid polymeric matrix is an organic matrix derived from a solid matrix forming monomer and from partial polymers of a solid matrix forming monomer. See, for example, U.S. Patents 5,501,921, 5,498,491, 5,491,039, 5,489,491, 5,482,795, 5,463,179, 5,419,984, 5,393,621, 5,358,620, 5,262,253, 5,346,787, 5,340,669, 5,300,375, 5,294,501, 5,262,253, and 4,908,283, which are incorporated herein.
  • Inorganic monomers are disclosed in U.S. Patents 4,247,499, 4,388,385, 4,414,607, 4,394,280, 4,432,891, 4,539,276, and 4,557,985, which are incorporated herein.
  • the solid matrix forming monomer or partial polymer can be cured or further cured prior to or after addition of the salt, solvent and, optionally, a viscosifier.
  • a composition comprising requisite amounts of the monomer or partial polymer, salt, organic carbonate solvent and viscosifier can be applied to a substrate and then cured.
  • monomer or partial polymer can be first cured and then dissolved in a suitable volatile solvent. Requisite amounts of the salt, organic carbonate solvent and viscosifier can then be added. The mixture is then placed on a substrate and removal of the volatile solvent would result in the formation of a solid electrolyte. In either case, the resulting solid electrolyte would be a homogeneous, single phase product which is maintained upon curing, and does not readily separate upon cooling to temperatures below room temperature.
  • the solid polymeric matrix can be formed by a casting process which does not require the use of monomers or prepolymers, that is, no curing is required.
  • a preferred method employs a copolymer of polyvinylidene difluoride and hexafluoropropylene dissolved in acetone or other suitable solvent.
  • the solvent is evaporated to form the solid polymeric matrix.
  • the solution may be casted directly onto a current collector.
  • the solution is casted onto a substrate, such as a carrier web, and after the solvent (e.g., acetone) is removed, an electrode film is formed thereon.
  • the solid polymeric matrix further comprises a silanized fumed SiO 2 .
  • the SiO 2 is a filler which impart toughness and strength to the polymeric matrix. In addition, it is believed that the SiO 2 assists the activation process by creating physico-chemical conditions such that the electrolyte solution quickly and completely fills the pores created in the polymeric matrix by the extraction of the plasticizer.
  • viscosifier refers to a suitable viscosifier for solid electrolytes.
  • Viscosifiers include conventional viscosifiers such as those known to one of ordinary skill in the art.
  • Suitable viscosifiers include film forming agents well known in the art which include, by way of example, polyethylene oxide, polypropylene oxide, copolymers thereof, and the like, having a number average molecular weight of at least about 100,000, polyvinylpyrrolidone, carboxymethylcellulose, and the like.
  • the viscosifier is employed in an amount of about 1 to about 10 weight percent and more preferably at about 2.5 weight percent based on the total weight of the electrolyte composition.
  • the electrolyte composition typically comprises from about 5 to about 25 weight percent of the inorganic ion salt based on the total weight of the electrolyte; preferably, from about 10 to 20 weight percent; and even more preferably from about 10 to about 15 weight percent.
  • the percentage of salt depends on the type of salt and electrolytic solvent employed.
  • the electrolyte composition typically comprises from 0 to about 80 weight percent electrolyte solvent (e.g., organic carbonate/giyme mixture) based on the total weight of the electrolyte; preferably from about 60 to about 80 weight percent; and even more preferably about 70 weight percent.
  • the electrolyte composition typically comprises from about 5 to about 30 weight percent of the solid polymeric matrix based on the total weight of the electrolyte; preferably from about 15 to about 25 weight percent.
  • the electrolyte composition further comprises a small amount of a film forming agent.
  • Suitable film forming agents are well known in the art and include, by way of example, polyethylene oxide, polypropylene oxide, copolymers thereof, and the like, having a numbered average molecular weight of at least about 100,000.
  • the film forming agent is employed in an amount of about 1 to about 10 weight percent and more preferably at about 2.5 weight percent based on the total weight of the electrolyte composition.
  • Electrochemical cells are known in the art. See, for example, U.S. Patents 5,300,373, 5,316,556, 5,346,385, 5,262,253, 4,472,487,
  • the extraction method of the present invention is conducted by first placing an electrochemical cell precursor comprising (i) an anode composition comprising an anodic material, a first polymer, and a first plasticizer; (ii) a cathode composition comprising a cathode active material, a second polymer, and a second plasticizer; and (iii) a separator comprising a third polymer and a third plasticizer, in a vessel.
  • the precursor includes current collector(s) for the anode and/or cathode.
  • An extraction solvent e.g. isopropanol
  • the extraction solvent is removed after a sufficient time to permit the plasticizers to be removed. Thereafter, the precursor is removed from the extraction solvent.
  • the extraction process can be repeated with fresh extraction solvent until the desired level of plasticizer is removed.
  • ultrasound waves are applied to the electrochemical cell precursor and the extraction solvent in the vessel so that the first, second and/or third plasticizer in the electrochemical cell precursor is solubilized into the extraction solvent.
  • the extraction solvent containing the plasticizer is then removed from contact with the electrochemical cell precursor.
  • the extraction process can be performed using either batch processes or continuous extraction methods.
  • the extraction solvent flows or is circulated through the extraction vessel so that extraction solvent containing extracted plasticizer is continually removed from the extraction vessel while pure or fresh extraction solvent is added.
  • the extraction solvent is vigorously mixed during the extraction process either by mechanical means, such as stirring, or by bubbling air or nitrogen through the extraction vessel.
  • the ultrasound waves employed have a frequency ranging from about 30 kHz to about 45 kHz. More preferably, the ultrasound waves have a frequency ranging from about 38 kHz to about 42 kHz.
  • a sweeping frequency i.e. a frequency continuously increasing and decreasing from about 30 kHz to about 45 kHz, preferably from 38 kHz to about 42 kHz, is employed to eliminate standing waves.
  • Any art-recognized apparatus or vessel may be used to conduct the ultrasound extraction process.
  • a preferred apparatus for conducting the extraction is a Bransonic Ultrasonic Cleaner (Model 5210-MTH), available from VWR Scientific Products.
  • One of the benefits of employing ultrasound waves is that the time required to complete extraction is significantly reduced without adversely affecting the electrochemical performance of electrode cells made.
  • the extraction process is preferably carried out at a temperature ranging from ambient to the boiling point of the extraction solvent.
  • the extraction is carried out at a temperature of from about 0° to about 50 °C, still more preferably, from about 20 °C to. about 30°C.
  • the extraction is carried out at a temperature near but less than the boiling point of the extraction solvent, preferably less than about 10 °C below the boiling point of the extraction solvent.
  • the ultrasonic extraction process of this invention extracts at least a portion of the plasticizer from the electrochemical ceil precursor.
  • at least 50% of the total amount of plasticizer in the electrochemical cell precursor is extracted by the ultrasonic extraction process. More preferably, at least 75% and still more preferably at least 90% of the plasticizer is removed by the extraction process. Removal of at least 95% of the plasticizer is especially preferred.
  • the extraction solvent used in the methods of this invention can be recovered and recycled by, for example, conventional distillation techniques, such as flash distillation. Similarly, the plasticizer can be recovered and reused after removal of the extraction solvent.
  • Anode Composition A polymer mixture comprising a copolymer of vinylidenedifluoride (VDF) and hexafluoropropylene (HFP) was prepared by mixing 6.8 grams of the copolymer in 20 grams of acetone.
  • the copolymer (average molecular weight 125,000) was Kynar Flex 2801TM from Elf Atochem North America, in Philadelphia, Pennsylvania. The mixture was stirred for about 24 hours in a milling jar available from VWR Scientific, in San Francisco, California, model H-04172-00.
  • the copolymer functions as a binder for the carbon in the anode.
  • a graphite mixture was prepared separately by first adding 23.4 grams of graphite into 0.9 grams of carbon black into a solution containing 60 grams acetone, 10.5 grams dibutyl phthalate, and 0.5 grams of a surfactant.
  • a preferred graphite is available under the designation BG35 graphite from Superior Graphite Co., Chicago, Illinois.
  • a preferred carbon black is available under the designation Super PTM from M.M.M. Carbon, Willebroek, Belgium.
  • the graphite mixture was then vigorously mixed in a high shear mixer until a substantially homogeneous blend was formed.
  • a suitable mixer is available from Ross, Model ME100DLX, Hauppauge, New York, operating at its highest setting (about 10,000 RPM) for 30 minutes.
  • An anode slurry was then prepared by mixing the polymer mixture and the graphite mixture together under low shear conditions to form an anode slurry wherein the components are well mixed. A portion of the acetone was allowed to evaporate from the slurry and it was then laminated onto each side of a current collector.
  • the anode current collector employed was a sheet of expanded copper metal that is about 50 ⁇ m thick. It is available under the designation 2Cu5-125 (flatten) from Delker, in Branford, Connecticut. Anode films formed when the remaining portion of the acetone evaporated.
  • a polymer mixture comprising a copolymer of vinylidenedifluoride (VDF) and hexafluoropropylene (HFP) was prepared by mixing 4.4 grams of the copolymer in 15 ml of acetone.
  • the copolymer was Kynar Flex 2801TM. The mixture was stirred for about 24 hours in a milling jar.
  • a cathode mixture was prepared separately by mixing 28.9 grams of LiMn 2 O 4 , 2.4 grams of carbon black (Super PTM) into a solution containing 60 grams acetone and 8.7 grams dibutyl phthalate. The mixture was then vigorously mixed in the a high shear mixer until a substantially homogeneous blend was formed.
  • the amount of cathode-active material LiMn 2 O 4 employed can be varied to provide different cathode to anode mass ratios.
  • a cathode slurry was prepared by mixing the polymer mixture and the cathode mixture together under low shear conditions to form the cathode slurry wherein the components are well mixed. A portion of the acetone was allowed to evaporate from the slurry and it was then laminated onto each side of a cathode current collector.
  • the cathode current collector employed was a sheet of expanded aluminum that is about 50 ⁇ m thick. The aluminum grid is available under the designation 2AL5-077 from Delker, in Branford, Connecticut. Cathode films formed when the remaining portion of the acetone evaporated.
  • each film can be prepared by first casting a slurry onto a substrate or carrier web and allowing the solvent to evaporate thus leaving the film. Thereafter, the films can be laminated onto each side of the current collector.
  • a polymeric matrix was formed by casting a polymeric slurry comprising acetone, dibutyl phthalate, silanized fumed SiO 2 , and the VDF/HFP copolymer on a suitable substrate or carrier web and allowing the acetone to evaporate. No curing by radiation is required.
  • the SiO 2 is a filler which imparts toughness and strength to the film.
  • the SiO 2 assists the activation process by creating physico- chemical conditions such that the electrolyte solution quickly and completely fills the pores created by the extraction of the dibutyl phthalate.
  • the polymeric slurry is mixed under low shear conditions as not to degrade the copolymer.
  • Electrochemical cell precursors were generally prepared employing the components set forth in Example 1-3. Each precursor comprised a "bicell" structure that has a cathode disposed between two anodes.
  • the cathode includes an aluminum current collector grid with cathode material laminated on both sides of the grid; similarly the anode includes a copper current collector grid with anode material laminated on both sides.
  • a polymeric layer is disposed between each of the two anode/cathode interfaces.
  • the bicell was cut into individual laminate structures or "coupons" which were subject to solvent extraction to remove the plasticizer, i.e., dibutyl phthalate.
  • the plasticizers in the coupons were extracted with an extraction solvent that contained methanol and varying amounts of water.
  • the coupons were submerged in the extraction solvent within an enclosed vessel for 2 hours; thereafter, the amount of hydrogen in the air vessel was measured. Table 1 sets forth the results.
  • bicells were immersed in 15 ml of methanol (with 250 ppm H 2 O) for two hours and the amount of hydrogen gas was measured.
  • the copper anode current collectors were either uncoated or coated with one of two types of adhesives: (1) the "PC” coating which is a mixture of polymer and graphite or (2) the "CA” which is a polymeric material that is cured.
  • the aluminum cathode current collector was coated with PC or CA.
  • the bicell coupons were subject to extraction to remove the plasticizer prior to being immersed in the methanol.
  • bicells were immersed in 15 ml of isopropyl alcohol (with 850 ppm H 2 O) for two hours and the amount of hydrogen gas was measured.
  • the current collectors were either uncoated or coated as described above.
  • the bicell coupons were subject to extraction to remove the plasticizer prior to being immersed in the alcohol.

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Abstract

L'invention concerne un procédé relatif à l'extraction de plastifiants du type phtalate de dibutyle à partir d'un ensemble électrode/collecteur de courant ou de l'anode, de la cathode et du séparateur qui constituent un précurseur de cellule électrochimique. Le procédé consiste à utiliser un solvant d'extraction renfermant un alcool aliphatique qui peut être de l'éthanol, du butanol, du pentanol et du propanol, y compris des combinaisons de ces substances. De préférence, le solvant d'extraction considéré est de l'isopropanol. On peut également utiliser des ondes ultrasonores pour réduire de manière appréciable le temps d'extraction.
PCT/US2001/003365 2000-02-17 2001-02-01 Extraction de plastifiants a partir de cellules electrochimiques Ceased WO2001061772A1 (fr)

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US09/505,503 2000-02-17

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010011496A1 (fr) * 2008-07-21 2010-01-28 Battelle Memorial Institute Procédés et compositions pour préparer des électrodes poreuses
WO2017152089A1 (fr) * 2016-03-03 2017-09-08 Apple Inc. Liants pour stratification humide et sèche de cellules de batterie
US9786887B2 (en) 2016-03-03 2017-10-10 Apple Inc. Binders for wet and dry lamination of battery cells
US11289769B2 (en) 2016-03-03 2022-03-29 Apple Inc. Binders for wet and dry lamination of battery cells
CN117096550A (zh) * 2023-10-19 2023-11-21 珙县华洁危险废物治理有限责任公司成都分公司 一种湿法锂电池隔膜中含油废膜的滴液回收方法

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US5540741A (en) * 1993-03-05 1996-07-30 Bell Communications Research, Inc. Lithium secondary battery extraction method
US5738691A (en) * 1997-04-28 1998-04-14 Valence Technology, Inc. Ultrasonic extraction of plasticizer from electrochemical cells
US5772702A (en) * 1996-04-10 1998-06-30 Valence Technology, Inc. Method of preparing electrochemical cells
WO1999045604A1 (fr) * 1998-03-04 1999-09-10 Valence Technology, Inc. Procedes d'obtention d'elements electrochimiques a l'aide de techniques d'extraction de solvants

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5540741A (en) * 1993-03-05 1996-07-30 Bell Communications Research, Inc. Lithium secondary battery extraction method
US5772702A (en) * 1996-04-10 1998-06-30 Valence Technology, Inc. Method of preparing electrochemical cells
US5738691A (en) * 1997-04-28 1998-04-14 Valence Technology, Inc. Ultrasonic extraction of plasticizer from electrochemical cells
WO1999045604A1 (fr) * 1998-03-04 1999-09-10 Valence Technology, Inc. Procedes d'obtention d'elements electrochimiques a l'aide de techniques d'extraction de solvants

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010011496A1 (fr) * 2008-07-21 2010-01-28 Battelle Memorial Institute Procédés et compositions pour préparer des électrodes poreuses
US8202569B2 (en) 2008-07-21 2012-06-19 Battelle Memorial Institute Process of making porous electrodes
WO2017152089A1 (fr) * 2016-03-03 2017-09-08 Apple Inc. Liants pour stratification humide et sèche de cellules de batterie
US9786887B2 (en) 2016-03-03 2017-10-10 Apple Inc. Binders for wet and dry lamination of battery cells
US10074838B2 (en) 2016-03-03 2018-09-11 Apple Inc. Binders for wet and dry lamination of battery cells
US10665840B2 (en) 2016-03-03 2020-05-26 Apple Inc. Binders for wet and dry lamination of battery cells
US11289769B2 (en) 2016-03-03 2022-03-29 Apple Inc. Binders for wet and dry lamination of battery cells
CN117096550A (zh) * 2023-10-19 2023-11-21 珙县华洁危险废物治理有限责任公司成都分公司 一种湿法锂电池隔膜中含油废膜的滴液回收方法
CN117096550B (zh) * 2023-10-19 2024-01-26 珙县华洁危险废物治理有限责任公司成都分公司 一种湿法锂电池隔膜中含油废膜的滴液回收方法

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