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WO2013090249A1 - Cellules électrochimiques comprenant des polymères solubles partiellement fluorés comme additifs d'électrolyte - Google Patents

Cellules électrochimiques comprenant des polymères solubles partiellement fluorés comme additifs d'électrolyte Download PDF

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WO2013090249A1
WO2013090249A1 PCT/US2012/068923 US2012068923W WO2013090249A1 WO 2013090249 A1 WO2013090249 A1 WO 2013090249A1 US 2012068923 W US2012068923 W US 2012068923W WO 2013090249 A1 WO2013090249 A1 WO 2013090249A1
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electrochemical cell
cell according
partially fluorinated
electrolyte
fluorinated polymer
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William M. Lamanna
Ang Xiao
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3M Innovative Properties Co
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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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0568—Liquid materials characterised by the solutes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0569—Liquid materials characterised by the solvents
    • 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 disclosure relates to electrolyte additives for secondary batteries.
  • fluorinated polymers in the construction of lithium-ion electrochemical cells is well known in the art.
  • these are high molecular weight polymers comprising vinylidene fluoride (VDF) or a mixture of VDF with hexafluoropropylene (HFP) for use either as composite electrode binders or in the preparation of polymer gel electrolytes.
  • VDF vinylidene fluoride
  • HFP hexafluoropropylene
  • dissolution of the fluorinated polymers in the liquid electrolyte would be detrimental to their intended function which is the binding together of electrode particles when the fluorinated polymers are used in binders or maintaining gel cohesion and physical separation between positive and negative electrode when the fluorinated polymers are used in polymer gel electrolytes.
  • Fluoropolymers used in these applications are chosen to have a sufficiently high molecular weight and a composition that renders them essentially insoluble in the liquid electrolyte - generally a -1.0M solution of lithium salt (usually LiPF 6 ) in a mixture of cyclic and acyclic organic carbonate solvents.
  • the fluoropolymer is a major component of the electrolyte (not just a minor additive) and is designed to be swollen by, but not dissolve in, the liquid electrolyte in order to maintain the cohesive strength of the polymer and provide a robust physical barrier between cathode and anode (to prevent shorting), while providing channels for facile Li-ion transport.
  • LIBs lithium- ion batteries
  • HEV Hybrid Electric Vehicles
  • PHEV Plug- in Hybrid Electric Vehicles
  • EV Pure Electric Vehicles
  • PNGV New Generation of Vehicles
  • the most extensively used LIB electrolytes are composed of LiPF 6 dissolved in organic carbonates or esters. However, these commonly used electrolytes have limited thermal and high voltage stability. Thermal and electrochemical degradation of the electrolyte can be a primary cause of reduced Li- ion battery performance over time.
  • Electrolyte additives designed to selectively react with, bond to, or self organize at the electrode surface in a way that passivates the interface represents one of the simplest and potentially most cost effective ways of achieving this goal.
  • electrolyte solvents and additives such as ethylene carbonate (EC), vinylene carbonate (VC), fluoroethylene carbonate (FEC), and lithium bisoxalatoborate (LiBOB)
  • SEI solid-electrolyte interface
  • Lithium bis(trifluoromethanesulfonyl) imide (HQ-1 15, available from 3M, St. Paul, MN) has been used as an electrolyte additive in commercial lithium ion batteries. When used as an electrolyte additive, lithium bis(trifluoromethanesulfonyl) imide improves cycle life in
  • bis(trifluoromethanesulfonyl) imide also can reduce gassing at the negative electrode and can prevent shorting under high temperature float test conditions with single layer PE separator. Thus cell life and safety are improved using lithium bis(trifluoromethanesulfonyl) imide as additives in standard electrolyte.
  • Fluorocarbon electrolyte additive that include multifunctional anions have also been disclosed, for example, in U.S. S.N. 61/494,094 (Lamanna et al.) filed on June 7, 201 1 and entitled "Lithium-ion Electrochemical Cells That Include Fluorocarbon Electrolyte Additives".
  • electrolyte additives that: 1) are capable of improving the high temperature performance and stability (e.g. > 55°C) of lithium- ion cells, 2) can provide electrolyte stability at high voltages (e.g. > 4.2V) for increased energy density, and 3) can enable new state of the art high capacity electrode materials (both new cathodes and new anodes).
  • the new partially fluorinated additives are low molecular weight, soluble fluoropolymers containing at least one monomer selected from tetrafluoroethylene (TFE), vinylidene fluoride (VDF) and hexafluoropropylene (HFP).
  • TFE tetrafluoroethylene
  • VDF vinylidene fluoride
  • HFP hexafluoropropylene
  • the provided partially fluormated polymer additives are soluble in common lithium-ion battery electrolyte formulations and are capable of enhancing lithium- ion cell performance (cycle life, calendar life, impedance) at elevated temperatures or high voltage.
  • an electrochemical cell in one aspect, includes a positive electrode that includes at least one electrochemically active material, a negative electrode; and a charge-carrying liquid electrolyte, wherein the charge-carrying liquid electrolyte includes at least one organic solvent, an electrolyte salt, and at least one partially fluorinated polymer additive that is soluble in the liquid electrolyte.
  • the electrochemically active material can be a lithium transition metal oxide and can include cobalt, manganese, or nickel.
  • the at least one organic solvent can include ethylene carbonate, dimethyl carbonate, or methyl ethyl carbonate.
  • the at least one partially fluorinated polymer additive can be the product of polymerization of a monomer mixture that includes tetrafluoroethylene, vinylidene fluoride, or hexafluoropropylene.
  • a method of stabilizing an electrochemical cell includes providing an electrochemical cell having a positive electrode that includes at least one
  • the charge-carrying liquid electrolyte includes at least one organic solvent, and an electrolyte salt; and dissolving a partially fluorinated polymer additive in the charge-carrying liquid electrolyte.
  • active or “electrochemically active” refers to a material that can undergo lithiation and delithiation by reaction with lithium;
  • inactive or “electrochemical inactive” refers to a material that does not react with lithium and does not undergo lithiation and delithiation;
  • lithium mixed metal oxide refers to a lithium metal oxide composition that includes one or more transition metals in the form of an oxide
  • loading refers to the amount (in weight) of partially fluorinated polymer additive that is placed in the electrolyte whether it is soluble or not;
  • negative electrode refers to an electrode (often called an anode) where electrochemical oxidation and delithiation occurs during a discharging process
  • positive electrode refers to an electrode (often called a cathode) where electrochemical reduction and lithiation occurs during a discharging process
  • soluble or “solubility” refers to the amount of partially fluorinated polymer additive that can dissolve in the liquid electrolyte at room temperature— if the "solubility" of the additive is greater than 1 weight percent in the liquid electrolyte, the additive is considered “soluble”.
  • the solubility of the partially fluorinated polymer additive is greater than 5 weight percent in the liquid electrolyte.
  • the provided partially fluorinated polymer additives are soluble in common lithium-ion battery electrolyte formulations and are capable of enhancing lithium- ion cell performance (cycle life, calendar life, impedance) at elevated temperatures (e.g., > 55°C) or high voltage (e.g., > 4.2 V vs. Li/Li + ). They are low molecular weight and are soluble (at 1 weight percent or greater, typically 5 weight percent or greater) in liquid electrolytes.
  • Fig. 1 is the 19 F NMR spectrum of the supernatant solution obtained by combining 1.0M LiPF 6 in ethylene carbonate (EC): ethyl methyl carbonate (EMC) (3:7 by weight) electrolyte with 2 wt% of LFC- 1 from Preparatory Example 1 at room temperature.
  • EC ethylene carbonate
  • EMC ethyl methyl carbonate
  • Fig. 2 is a schematic diagram showing how voltage drop, percent reversible, irreversible, and total capacity loss is calculated from high temperature thermal storage data in full cells.
  • Electrochemical cells typically, lithium-ion electrochemical cells, are provided that include a positive electrode that includes at least one electrochemically active material.
  • electrochemically active materials include, for example, LiFeP0 4 , LiMnP0 4 , LiMn 2 0 4 , L1C0PO 4 , and L1C0O 2 ; lithium transition metal oxides as disclosed in U. S. Pat. Nos. 5,858,324; 5,900,385; 6,143,268 (all to Dahn et al.); and 6,680, 145 (Obrovac et al.); U. S. Pat. Nos. 6,964,828 and 7,078, 128 (Lu et al.); U. S. Pat. Appl. Publ.
  • electrochemically active materials that are useful in positive electrodes for the provided electrochemical cells can include, for example, LiNio.5Mn1.5O4 and L1VPO 4 F.
  • the lithium mixed metal oxide compositions can adopt an 03 or -NaFe0 2 -type layered structure that can be desirable for efficient lithiation and delithiation. These materials are well known in the art and are disclosed, for example, in U. S. Pat. Nos.
  • the provided cathode compositions can include transition metals selected from manganese (Mn), nickel (Ni), and cobalt (Co).
  • Mn manganese
  • Ni nickel
  • Co cobalt
  • the amount of Mn can range from 0 to about 50 mole percent (mol%), from 0 to about 40 mol%, or from greater than zero to about 10 mol% based upon the total mass of the cathode composition, excluding lithium and oxygen.
  • the amount of Ni can range from 0 to about 50 mol%, from 0 to about 40 mol%, or from 0 to about 10 mol% based upon the total mass of the cathode composition, excluding lithium and oxygen.
  • the amount of Co can range from greater than about 10 mol% to about 95 mol%, from greater than about 15 mol% to about 70 mol%, or even from greater than about 20 mol% to about 50 mol% of the composition excluding lithium and oxygen.
  • the lithium metal oxide can include additional metals.
  • the lithium mixed metal oxide can include one or more additional metals as dopants.
  • Exemplary metals include Al, Mg, Zr, Fe, Cu, Zn, V, or Ti.
  • the lithium mixed metal oxides can be aluminum-doped lithium transition metal oxides as disclosed, for example, in U. S. Pat. No. 7,709,149 (Paulsen et al.) or lithium transition metal oxides with a gradient of metal compositions as disclosed, for example, in U. S. Pat. No. 7,695,649 (Paulsen et al.)
  • Other mixed metal oxide disclosures include U. S. Pat. Nos. 7,648,693; 7,939,049; and 7,939,203 (all Paulsen et al.)
  • Lithium transition metal oxides can be in the form of particles having a single phase having an 03 ( -NaFe0 2 ) crystal structure.
  • the particles may have a maximum average dimension that is no greater than 60 micrometers, no greater than 40 micrometers, or no greater than 20 micrometers.
  • the powders may for example have a maximum average particle diameter that is submicron, at least 1 micrometer, at least 2 micrometers, at least 5 micrometers, or at least 10 micrometers.
  • suitable powders often have a maximum average dimension of 1 to 60 micrometers, 10 to 60 micrometers, 20 to 60 micrometers, 40 to 60 micrometers, 1 to 40 micrometers, 2 to 40 micrometers, 10 to 40 micrometers, 5 to 20 micrometers, or 10 to 20 micrometers.
  • the powdered materials may contain optional matrix formers within powder particles. Each phase originally present in the particle (i.e., before a first lithiation) may be in contact with the other phases in the particle.
  • the average diameter of particles of the mixed metal oxide materials can be from about 2 ⁇ to about 25 ⁇ . In other embodiments, the average particle size can be less than about 1000 nm, less than about 500 nm, less than about 250 nm, less than about 100 nm, or less than about 50 nm.
  • the cathode compositions may be synthesized by jet milling or by combining precursors of the metal elements (e.g., hydroxides, nitrates, and the like), followed by heating to generate the cathode composition. Heating is preferably conducted in air at temperatures of at least about 600°C, more preferably at least 800°C. In general, higher temperatures are preferred because they lead to materials with increased crystallinity. The ability to conduct the heating process in air is desirable because it obviates the need and associated expense of maintaining an inert atmosphere. Accordingly, the particular metal elements are selected such that they exhibit appropriate oxidation states in air at the desired synthesis temperature. Conversely, the synthesis temperature may be adjusted so that a particular metal element exists in a desired oxidation state in air at that temperature.
  • precursors of the metal elements e.g., hydroxides, nitrates, and the like
  • the provided lithium-ion electrochemical cells include a negative electrode capable of intercalating lithium or alloying with lithium.
  • the lithium metal oxide positive electrodes described above can be combined with an anode and an electrolyte to form a lithium-ion electrochemical cell or a battery pack from two or more electrochemical cells.
  • suitable anodes can be made from compositions that include lithium, carbonaceous materials, silicon alloy compositions, tin alloy compositions and lithium alloy compositions.
  • Exemplary carbonaceous materials can include synthetic graphites such as mesocarbon microbeads (MCMB) (available from Osaka Gas Co., Japan), SLP30 (available from TimCal Ltd., Bodio Switzerland), natural graphites and hard carbons.
  • Useful anode materials can also include alloy powders or thin films.
  • Such alloys may include electrochemically active components such as silicon, tin, aluminum, gallium, indium, lead, bismuth, and zinc and may also comprise electrochemically inactive components such as iron, cobalt, transition metal silicides and transition metal aluminides.
  • Useful alloy anode compositions can include alloys of tin or silicon such as Sn-Co-C alloys, and Si 7 oFeioTi 10 Cio where Mm is a Mischmetal (an alloy of rare earth elements).
  • Metal alloy compositions used to make anodes can have a nanocrystalline or amorphous microstructure. Such alloys can be made, for example, by sputtering, ball milling, rapid quenching, or other means.
  • Useful anode materials also include metal oxides such as Li 4 Ti 5 0i 2 , W0 2 , and tin oxides.
  • Other useful anode materials include tin-based amorphous anode materials such as those disclosed in U. S. Pat. No. 7,771,876 (Mizutani et al.).
  • Exemplary silicon alloys that can be used to make suitable anodes include compositions that comprise from about 65 to about 85 mol% Si, from about 5 to about 12 mol% Fe, from about 5 to about 12 mol% Ti, and from about 5 to about 12 mol% C. Additional examples of useful silicon alloys include compositions that include silicon, copper, and silver or silver alloy such as those discussed in U. S. Pat. Appl. Publ. No. 2006/0046144 (Obrovac et al.); multiphase, silicon- containing electrodes such as those discussed in U. S. Pat. No.
  • amorphous alloys having high silicon content such as those discussed in U. S. Pat. No. 7,732,095 (Christensen et al.); and other powdered materials used for negative electrodes such as those discussed in U. S. Pat. Appl. Publ. No. 2007/0269718 (Krause et al.) and U. S. Pat. No. 7,771,861 (Krause et al.).
  • Anodes can also be made from lithium alloy compositions such as those of the type described in U. S. Pat. Nos. 6,203,944 and 6,436,578 (both to Turner et al.) and in U. S. Pat. No. 6,255,017 (Turner).
  • the provided electrochemical cells include a charge-carrying liquid electrolyte that includes at least one organic solvent, an electrolyte salt, and at least one partially fluorinated polymer additive that is soluble in the liquid electrolyte.
  • a charge-carrying liquid electrolyte that includes at least one organic solvent, an electrolyte salt, and at least one partially fluorinated polymer additive that is soluble in the liquid electrolyte.
  • electrolytes can contain one or more lithium salts and a charge-carrying medium in the form of a liquid or gel.
  • Exemplary lithium salts are stable in the electrochemical window and temperature range (e.g. from about -30°C to about 70°C) within which the cell electrodes can operate, are soluble in the chosen charge-carrying media, and perform well in the chosen lithium-ion cell.
  • Exemplary lithium salts include LiPF 6 , LiBF 4 , L1CIO 4 , lithium bis(oxalato)borate, LiN(CF 3 S0 2 ) 2 , LiN(C 2 F 5 S0 2 ) 2 , LiAsF 6 , LiC(CF 3 S0 2 ) 3 , and combinations thereof.
  • Exemplary liquid electrolytes include at least one organic solvent such as, for example, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl-methyl carbonate, butylene carbonate, vinylene carbonate, fluoroethylene carbonate, fluoropropylene carbonate, ⁇ -butyrolactone, methyl difluoroacetate, ethyl difluoroacetate, dimethoxyethane, diglyme (bis(2-methoxyethyl) ether), tetrahydrofuran, dioxolane, combinations thereof and other media that will be familiar to those skilled in the art.
  • Exemplary electrolyte gels include those described in U.S. Pat. Nos. 6,387,570 (Nakamura et al.) and 6,780,544 (Noh).
  • the electrolyte can include other additives that will be familiar to those skilled in the art.
  • other additives such as redox chemical shuttles
  • Redox chemical shuttles can also be added to the electrolyte of the provided lithium-ion electrochemical cells.
  • Redox chemical shuttles can impart overcharge protection to rechargeable lithium-ion electrochemical cells. Redox chemical shuttles have been disclosed, for example, in U. S. Pat. Nos. 7, 585,590 (Wang et al.) and in U. S. Pat. Nos.
  • Partially fluorinated polymer additives are provided that are soluble in common lithium ion battery electrolyte formulations and are capable of enhancing lithium ion cell performance (cycle life, calendar life, impedance) at elevated temperatures or high voltage.
  • the partially fluorinated polymer additives are the product of polymerization of a monomer mixture that includes at least one monomer selected from tetrafluoroethylene (TFE), vinylidene fluoride (VDF), and hexafluoropropylene (HFP).
  • TFE tetrafluoroethylene
  • VDF vinylidene fluoride
  • HFP hexafluoropropylene
  • the partially fluorinated polymer additives are the reaction product of vinylidene fluoride and hexafluoropropylene.
  • the solubility of the partially fluorinated polymer additives in the base electrolyte formulation is greater than 1.0% by weight, greater than 5.0% by weight, or even greater than 10% by weight at room temperature.
  • a typical loading of the partially fluorinated polymer additive in the base electrolyte formulation is less than 5.0% by weight, less than 3.0% by weight, or even less than 1.0% by weight.
  • Partially fluorinated polymer additive loadings in the base electrolyte formulation of at least 0.2 weight percent or from about 0.2 weight percent to about 2.0 weight percent are typical, with loadings of from about 0.5 weight percent to about 1.5 weight percent being most typical.
  • the partially fluorinated polymer additive typically has a molecular weight (Mn) ⁇ 50,000 atomic mass units (amu), ⁇ 20,000 amu, or even ⁇ 10,000 amu.
  • Partially fluorinated polymer additives have the same structure as their fully hydrogenated analogs with 10 percent to 90 percent of the hydrogen atoms of their fully hydrogenated analog replaced by fluorine substituents.
  • the partially fluorinated polymer additives have at least 60% of the hydrogen atoms of their fully hydrogenated analogs replaced by fluorine substituents.
  • the provided partially fluorinated polymer additives can be made using firee- radical polymerization of ethylenically unsaturated monomers in the presence of chain-transfer agents as disclosed, for example, in U. S. Pat. No. 5,208,305 (Grootaert).
  • LFC-1 is a copolymer of VDF and HFP with a molecular weight of -10,000 amu.
  • the provided electrochemical cells can contain additives such as will be familiar to those skilled in the art.
  • the electrode composition can include an electrically conductive diluent to facilitate electron transfer between the composite electrode particles and from the composite to a current collector.
  • Electrically conductive diluents can include, but are not limited to, carbon black, metal, metal nitrides, metal carbides, metal silicides, and metal borides.
  • Representative electrically conductive carbon diluents include carbon blacks such as SUPER P and SUPER S (both from MMM Carbon, Belgium), SHAWANIGAN BLACK (Chevron Chemical Co., Houston, TX), acetylene black, furnace black, lamp black, graphite, carbon fibers and combinations thereof.
  • the electrode composition can include an adhesion promoter that promotes adhesion of the composition and/or electrically conductive diluent to the binder.
  • the combination of an adhesion promoter and binder can help the electrode composition better accommodate volume changes that can occur in the composition during repeated lithiation/delithiation cycles.
  • the binders themselves can offer sufficiently good adhesion to metals and alloys so that addition of an adhesion promoter may not be needed.
  • an adhesion promoter can be made a part of the binder itself (e.g., in the form of an added functional group), can be a coating on the composite particles, can be added to the electrically conductive diluent, or can be a combination of such measures.
  • adhesion promoters include silanes, titanates, and phosphonates as described in U. S. Pat. No. 7,341,804 (Christensen).
  • a method of stabilizing an electrochemical cell includes providing an electrochemically active positive electrode, a negative electrode, and a charge-carrying electrolyte that includes at least one organic solvent and an electrolyte salt. The method further includes dissolving at least 0.2 weight percent of a partially fluorinated polymer additive in the charge- carrying liquid electrolyte.
  • the disclosed cells may be used in a variety of devices, including portable computers, tablet displays, personal digital assistants, mobile telephones, motorized devices (e.g, personal or household appliances and vehicles), instruments, illumination devices (e.g., flashlights) and heating devices.
  • the disclosed cells may have particular utility in low-cost mass market electrical and electronic devices such as flashlights, radios, CD players and the like,
  • LFC- 1 partially fluorinated polymer additive was prepared by copolymerization of vinylidene fluoride and hexafluoropropylene according to the procedure disclosed in
  • Example 1 of U. S. Pat. No. 5,208,305 (Grootaert).
  • the resulting latex was purified by extraction into methyl ethyl ketone, evaporation to dryness at elevated temperature, reextraction of the resulting gum into dimethyl carbonate, filtration by suction to remove insoluble impurities, and then final evaporation to dryness under vacuum at 25-100°C.
  • the polymer had a number average molecular weight, M n , of approximately 10,000 amu as determined by standard gel phase chromatography (GPC) techniques. According to NMR analysis ( l H and 19 F) the polymer had a vinylidene fluoride:hexafluoropolypropylene ratio of 3.38: 1 and contained 2.5 wt% dimethyl carbonate solvent.
  • FIG. 1 is the 19 F NMR spectrum of the electrolyte solution.
  • the doublet at -73.8 ppm results from the resonance of LiPF 6 .
  • the peaks between -76.2 and -76.6 ppm are attributed to fluorine atom A in CF3 side group in HFP of LFC-1.
  • the calculated concentration of LFC- 1 in solution was 1.78 wt%, confirming that all the additive charged to the electrolyte dissolved (within error limits) and the solubility of LFC-1 in our standard electrolyte formulation is ample for use as an electrolyte additive.
  • LiNio. 4 Mno. 4 Coo.2O2 positive electrode active material, available from 3M, St. Paul, MN
  • Super P carbon conductive agent available from Timcal Graphite and Carbon, Bodio, Switzerland
  • polyvinylidene fluoride binder KYNAR RX PVDF available from Arkema Inc., King of Prussia, PA
  • NMP l-methyl-2- pyrrolidinone
  • a positive electrode cathode
  • the resulting cathodes were then calendered to 2.91 g/cm 3 (30% porosity) before use.
  • 92% by weight of MAGE graphite (negative electrode active material available from Hitachi) and 8 % by weight of PAA-Li binder (prepared from PAA (Polyacrylic acid available from Sigma-Aldrich) by neutralization with LiOH in water) were mixed in water as a solvent.
  • the resulting mixture was applied to a copper foil and dried to generate a negative electrode.
  • the anodes were calendared to 1.61 g/cm 3 (25% porosity) before cell assembly.
  • a non-aqueous solvent mixture comprising ethylene carbonate (EC):ethyl methyl carbonate (EMC) (both available from Novolyte) having a ratio of 3:7 by volume was prepared.
  • Lithium salt, LiPF 6 available from Novolyte
  • LiPF 6 available from Novolyte
  • Various amounts of additives were added to the l .OM electrolyte solution, as indicated in the Examples below. All electrolytes were prepared in an Ar purged glove box with water content less than 5 ppm. The above formulated electrolytes were filtered just prior to injection into the lithium ion cells.
  • Coin cells were fabricated with the resulting cathodes and anodes in 2325-size (23 mm diameter and 2.5 mm thickness) stainless steel coin-cell hardware in a dry room. Two layers of CELGARD #2335 (available from Celgard, Charlotte, NC) were used as a separator. 100 ⁇ electrolyte prepared as described above was injected into the coin cells manually. Finally the cells were sealed by crimping. Coin Cell Cycling.
  • Coin cells were prepared with cathodes and anodes as described above.
  • the additives shown in Table 1 were added to the formulated electrolyte stock solution containing l .OM LiPF 6 , described above. Table 1
  • Table 2 includes the discharge capacity and capacity retention at 200 th cycle of coin cells held at room temperature.
  • the cells with added VC (Comparative Example 2) when cycled at room temperature show obvious capacity fade after 200 cycles.
  • the control and 2% LFC-1 cells (Comparative Example 1 and Example 1) deliver similar eye lability and 1% LFC-1 cells (Example 2) show the best performance without significant capacity loss after 200 cycles.
  • Table 2 also indicates the voltage hysteresis of coin cells held at room temperature. The voltage hysteresis measures the total polarization and impedance of coin cells which can be calculated by Eq. 2.
  • the cells with added VC when cycled at room temperature show highest voltage hysteresis at the 200 th cycle.
  • control and 2% LFC-1 cells deliver similar polarization and 1% LFC-1 cells (Example 2) show the best performance without significant impedance rise after 200 cycles.
  • LiNio. 4 Mno. 4 Coo.2O2 cathodes and MAGE graphite anodes, as described above.
  • a non-aqueous solvent mixture comprising EC:EMC having a ratio of 3:7 by volume was prepared.
  • the lithium salt, LiPF 6 was dissolved in above solvent mixture to prepare a 1.0 M electrolyte solution.
  • the additives shown in Table 3 were added to the 1.0 M LiPF 6 electrolyte stock solution described above.
  • Coin cell test conditions (voltage limits, temperature and rate) were chosen to stress cells and cause significant capacity fade in control cells over the course of 200 cycles to allow differentiation of performance with and without additives.
  • Additive testing was conducted at 60°C using the same testing protocol as described above for Examples 1-2. For any given cell, formation and cycling were conducted at the same temperature.
  • Table 4 also shows the voltage hysteresis of coin cells held at high temperature.
  • the voltage hysteresis measures the total polarization and impedance of coin cells which can be calculated by Eq. 2.
  • the cells with added LFC-1 (Example 3) when cycled at high temperature show lowest voltage hysteresis at 200 th cycles. Additionally 2% VC and 2% LFC-1 cells
  • Example 4 deliver less impedance rise than VC alone cells (Comparative Example 4) after 200 cycles. Comparative Examples 5 and Examples 5.
  • Coin cells were prepared with LiNio. 4 Mno. 4 Coo.2O2, cathodes and MAGE graphite anodes, as described above.
  • the additives shown in Table 5 were added to the formulated electrolyte stock solution containing 1.0M LiPF 6 , described above.

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Abstract

L'invention concerne des cellules électrochimiques comprenant une électrode positive qui contient au moins un matériau actif électrochimiquement, une électrode négative et un électrolyte liquide transporteur de charges. L'électrolyte comprend au moins un solvant organique, un sel d'électrolyte et au moins un additif polymère partiellement fluoré qui est soluble à hauteur d'au moins 1 pourcent en poids dans l'électrolyte liquide. L'additif polymère partiellement fluoré est le produit de la polymérisation d'un mélange de monomères contenant du tétrafluoroéthylène, du fluorure de vinylidène ou de l'hexafluoropropylène.
PCT/US2012/068923 2011-12-14 2012-12-11 Cellules électrochimiques comprenant des polymères solubles partiellement fluorés comme additifs d'électrolyte Ceased WO2013090249A1 (fr)

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CN104282944A (zh) * 2014-10-30 2015-01-14 上海动力储能电池系统工程技术有限公司 一种锂离子电池高电压电解液及其用途
US20180166700A1 (en) * 2014-06-17 2018-06-14 Medtronic, Inc. Semi-solid electrolytes for batteries
WO2019036246A1 (fr) * 2017-08-17 2019-02-21 Medtronic, Inc. Électrolytes de solution polymère
CN120319887A (zh) * 2025-04-17 2025-07-15 江苏全锂智能科技有限公司 一种高导电率锂离子电池电解液及其制备方法

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KR20040000129A (ko) * 2002-06-24 2004-01-03 삼성에스디아이 주식회사 리튬 이온 전지용 전해질 및 이를 포함하는 리튬 이온 전지
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US20180166700A1 (en) * 2014-06-17 2018-06-14 Medtronic, Inc. Semi-solid electrolytes for batteries
US10727499B2 (en) * 2014-06-17 2020-07-28 Medtronic, Inc. Semi-solid electrolytes for batteries
CN104282944A (zh) * 2014-10-30 2015-01-14 上海动力储能电池系统工程技术有限公司 一种锂离子电池高电压电解液及其用途
WO2019036246A1 (fr) * 2017-08-17 2019-02-21 Medtronic, Inc. Électrolytes de solution polymère
CN111033826A (zh) * 2017-08-17 2020-04-17 美敦力公司 聚合物溶液电解质
CN120319887A (zh) * 2025-04-17 2025-07-15 江苏全锂智能科技有限公司 一种高导电率锂离子电池电解液及其制备方法

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