WO2015086759A1 - Alkali-ion conducting composite membranes for electronic applications - Google Patents

Alkali-ion conducting composite membranes for electronic applications Download PDF

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Publication number
WO2015086759A1
WO2015086759A1 PCT/EP2014/077410 EP2014077410W WO2015086759A1 WO 2015086759 A1 WO2015086759 A1 WO 2015086759A1 EP 2014077410 W EP2014077410 W EP 2014077410W WO 2015086759 A1 WO2015086759 A1 WO 2015086759A1
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WIPO (PCT)
Prior art keywords
alkali
ion conducting
separator assembly
particles
conducting separator
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PCT/EP2014/077410
Other languages
French (fr)
Inventor
Oliver Gronwald
Johan Ter Maat
Klaus Leitner
Klaus MÜHLBACH
Werner Goedel
Lutz Reinhardt
Peggy SCHUMANN
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Basf Se
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Publication of WO2015086759A1 publication Critical patent/WO2015086759A1/en

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Classifications

    • 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
    • H01M50/431—Inorganic material
    • H01M50/434—Ceramics
    • H01M50/437—Glass
    • 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
    • H01M50/403—Manufacturing processes of separators, membranes or diaphragms
    • 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
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • 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
    • H01M50/431—Inorganic material
    • H01M50/434—Ceramics
    • 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
    • H01M50/446—Composite material consisting of a mixture of organic and inorganic materials
    • 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
    • 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

  • the present invention relates to an alkali-ion conducting separator assembly comprising as a first component (A) a continuous matrix (A) of at least one polymer, and as a second component (B) particles (B) of an alkali-ion conducting material, which are embedded in the continuous matrix (A), wherein at least 50 % of the embedded particles (B) penetrate both sides of the continuous matrix (A) and are uncovered by matrix (A).
  • the present invention further relates to a process for producing such an alkali-ion conducting separator assembly and to an electrochemical cell comprising such an alkali-ion conducting separator assembly.
  • Secondary batteries, accumulators or “rechargeable batteries” are just some embodiments by which electrical energy can be stored after generation and used when required. Owing to the significantly better power density, there has in recent times been a move away from the water- based secondary batteries toward development of those batteries in which the charge transport in the electrical cell is accomplished by lithium ions. Many components are of significance, such as the electrodes and the electrolyte. However, particular attention will be paid to the separator which physically separates the anode and the cathode, thereby preventing short circuits.
  • the separator should allow lithium ions to pass.
  • a separator should have the necessary mechanical properties to effectively separate anode and cathode from each other.
  • membranes which comprise particles embedded in a continuous matrix, wherein at least 50 percent of the embedded particles at both and opposite surfaces of the membrane, are uncovered by the matrix.
  • the membranes can be used for the separation of a desired compound from a mixture comprising that desired compound.
  • US201 1027642A describes a microporous polyolefin composite film with a thermally stable porous layer at high temperature, which is used as a separator for a high-capacity/high-power lith- ium secondary battery.
  • J. Eur. Ceram. Soc. 24 (2004) 1385-1387 describes PEO-based solid polymer electrolytes comprising nanosized Zr02 particles for building rechargeable lithium metal batteries.
  • US 8,334,075 describes a composite solid electrolyte, which includes a monolithic solid electrolyte base component that is a continuous matrix of an inorganic active metal ion conductor and a filler component used to eliminate through porosity in the solid electrolyte.
  • US 8,383,268 describes a lithium ion secondary battery, which includes a positive electrode, a negative electrode and a thin film solid electrolyte including lithium ion conductive inorganic substance.
  • the thin film solid electrolyte has thickness of 20 ⁇ or below and is formed directly on an electrode material or materials for the positive electrode and/or the negative electrode.
  • separators known from the literature which comprise alkali-ion conducting materials, still have deficiencies in respect of one or more of the properties desired for such separators, for example low thickness, low weight per unit area, good mechanical stability during processing or in operation of the battery in respect of metal dendrite growth, good heat resistance, good ion conductivity and complete impermeability for organic solvents.
  • Some of the deficiencies of the known separators are ultimately responsible for a reduced life or limited performance of the electrochemical cells comprising them.
  • separators in principle have to be not only mechanically but also chemically stable toward the cathode materials, the anode materials and the electrolytes.
  • an alkali-ion conducting separator assembly comprising
  • the inventive alkali-ion conducting separator assembly comprises a continuous matrix (A) of at least one polymer, also called matrix (A) for short, and particles (B) of an alkali-ion conducting material, also called particles (B) for short, which are embedded in the continuous matrix (A), wherein at least 50 %, preferably at least 80 %, more preferably at least 90 %, in particular at least 95% of the embedded particles (B) penetrate both sides of the continuous matrix (A) and are uncovered by matrix (A).
  • the particles which penetrate both sides of the continuous matrix (A) and which are uncovered by matrix (A), expose a fraction of 10% to 40% of their total surface on each side of the continuous matrix (A), in particular these particles expose on each side of the continuous matrix (A) a similar fraction of their surface.
  • Matrix (A) together with embedded particles (B) forms a layer or membrane which is permeable for alkali-ions, in particular for lithium ions, and which is electrically insulating. While particles (B) are alkali-ion conducting the matrix (A) itself can in principle be either alkali-ion conducting or non-alkali-ion conducting, depending on the nature of the polymer or mixture of polymers form- ing matrix (A).
  • matrix (A) is a non-ion conducting matrix, in particular a non-alkali-ion conducting matrix.
  • the expression “electrically insulating” means, that the electrical conductivity of the alkali-ion conducting separator assembly is less than 10 -8 S/cm at 25 °C.
  • the alkali-ion conducting separator assembly is characterized in that the continuous matrix (A) is a non-ion conducting matrix, in particular a non-alkali-ion conducting matrix.
  • the polymer or mixture of polymers forming matrix (A) can be chosen from a wide range of polymers, for example organic polymers or inorganic polymers like polyphosphazenes or poly(organo)siloxanes, providing that the chosen polymer or mixture of polymers is insoluble or non-swellable, in particular insoluble in such solvents to which the inventive alkali-ion conduct- ing separator assembly is exposed in its designated application, in particular in electrochemical cells.
  • the polymer is insoluble in aprotic organic solvents, more preferably insoluble in ethers, carbonates, amides, sulfoxides, sulfones or mixtures thereof, in particular insoluble in ethers, carbonates or mixtures thereof.
  • the alkali-ion conducting separator assembly is characterized in that the polymer of the continuous matrix (A) is a non-swellable polymer.
  • Suitable polymers are preferably hydrophobic polymers, which are obtainable from appropriate monomers, which are in particular polymerizable by UV initiators.
  • Preferred examples of such monomers are trimethylolpropane triacrylate (Laromer ® TMPTA), trimethylolpropane trimethacry- late (TMPTMA), mixture of 7,9,9 and 7,7,9-trimethyl-4,13-dioxo-3,14-dioxa-5,12- diazahexadecan-1 ,16-diol-dimethylacrylate (Plex 6661 -0 ® , HEMATMDI), 1 ,3- butanedioldimethylacrylat (1 ,3-BDDMA), 1 ,4-butanedioldimethylacrylat (1 ,4-BDDMA), eth- yleneglycoldimethylacrylate (EGDMA), divinylbenzene or mixtures thereof.
  • Laromer ® TMPTA trimethyl
  • the polymer forming matrix (A) can be linear, branched, ladder-like or cross-linked.
  • the polymer of the continuous matrix (A) is a cross-linked polymer, in particular a cross-linked polyacrylate or polymethacrylate.
  • the alkali-ion conducting separator assembly is characterized in that the polymer of the continuous matrix (A) is a cross-linked polymer.
  • the shape of the inventive alkali-ion conducting separator assembly is preferably the shape of a sheet or flat body.
  • the expression "flat” means that the alkali-ion conducting separator assembly described, a three-dimensional body, is smaller in one of its three spatial dimensions (extents), namely the thickness, with respect to the two other dimensions, the length and width.
  • the thickness of the alkali-ion conducting separator assembly is less than the second-greatest dimension at least by a factor of 5, preferably at least by a factor of 10, more preferably at least by a factor of 20.
  • inventive alkali-ion conducting separator assembly is flat, it can not only be incorporated as flat layer between cathode and anode, but can also, as required, be rolled up, wound up or folded as desired.
  • the thickness of matrix (A) of the inventive alkali-ion conducting separator assembly can be varied in a wide range.
  • the thickness of matrix (A) depends on the average diame- ter of particles (B), since both sides of matrix (A) should be penetrated by particles (B).
  • matrix (A) has an average thickness in the range from 0.01 to 100 ⁇ , preferably in the range from 0.1 to 10 ⁇ .
  • the alkali-ion conducting separator assembly is characterized in that the continuous matrix (A) has an average thickness in the range from 0.01 to 100 ⁇ , preferably in the range from 0.1 to 10 ⁇ .
  • particles (B) of the inventive alkali-ion conducting separator assembly penetrate both sides of the continuous matrix (A) and are uncovered by matrix (A) preferably particles (B) form a monolayer in order to achieve that result.
  • the alkali-ion conducting separator assembly is characterized in that the particles (B) form a monolayer.
  • Particles (B) consist of an alkali-ion conducting material.
  • Alkali-ion conducting materials in particular lithium ion conducting materials are known to the person skilled in the art. Non limiting examples of suitable alkali-ion conducting materials are described in US 8,383,268, col. 3, line 42 to col. 4, line 60.
  • the alkali-ion conducting material is selected from the group consisting of ceramics, sintered ceramics, glass-ceramics and glasses, more preferably well- known Li ion conducting inorganic solid lithium ion conductors as described by P.
  • the alkali-ion conducting separator assembly is characterized in that the alkali-ion conducting material is selected from the group consisting of ceramics, sintered ceramics, glass-ceramics and glasses.
  • the average diameter of particles (B) can be varied in a wide range.
  • the average diameter of particles (B) is in the range from 0.1 to 10 ⁇ , more preferably in the range from 0.3 to 5 ⁇ , in particular in the range from 0.5 to 2 ⁇ .
  • the particle size distribution was determined by means of laser diffraction technology in powder form to DIN ISO 13320-1 with a Mastersizer from Malvern Instruments GmbH,dorfberg, Germany.
  • the crucial value for the mean particle size is what is called the d90 value.
  • the d90 value of the volume-weighted distribution is that particle size for which 90% of the particle vol- ume of particles are smaller than or equal to the d90 value.
  • the alkali-ion conducting separator assembly is characterized in that the average diameter of particles (B) is in the range from 0.1 to 10 ⁇ .
  • the shape of particles (B) can be freely chosen, but platelets and in particular cubes offer a better contact area for lithium ion transfer and can be arranged into a very high volume percentage of matrix (A).
  • the alkali-ion conducting separator assembly is characterized in that the shape of particles (B) is the shape of platelets or of cubes, in particular of cubes.
  • particles (B) are arranged in a monolayer it is extremely important to have a narrow particle size distribution, because particles which are significantly thinner or smaller than the average particles would not protrude on both sides of matrix (A).
  • Particles (B) of an alkali-ion conducting material can be obtained from the corresponding material in macroscopic size by grinding processes resulting in a very wide particle size distribution. In such a case
  • over/undersize particles may be removed by suitable and well-established methods like filtration, sieving and sifting.
  • the ratio of d50 to d10 and also d90 to d50 should be below 3, prefera- bly below 2.
  • the alkali-ion conducting separator assembly is characterized in that the ratio of the d50 value to the d10 value and of the d90 value to the d50 value of the particle size distribution of particles (B) is below 3, preferably below 2.
  • Particles in the shape of platelets or cubes are preferably obtained by using wet-chemical synthesis routes, which offer better control of the particle morphology than grinding methods.
  • the ratio of the average thickness of the continuous matrix (A) to the average diameter of parti- cles (B) can be varied in a wide range.
  • the ratio of the average thickness of the continuous matrix (A) to the average diameter of particles (B) is in the range from 0.1 to 10, more preferably in the range from 0.5 to 5, in particular in the range from 0.75 to 3.
  • the ratio of the average thickness of the continuous matrix (A) to the average diameter of parti- cles (B) is in the range from 0.1 to 2, more preferably in the range from 0.5 to 1 .2, in particular in the range from 0.75 to 1 .
  • the alkali-ion conducting separator assembly is characterized in that the ratio of the average thickness of the continuous matrix (A) to the average diameter of particles (B) is in the range from 0.1 to 10, preferably in the range from 0.5 to 5, in particular in the range from 0.75 to 3.
  • the alkali-ion conducting separator assembly is characterized in that the ratio of the average thickness of the continuous matrix (A) to the average diameter of particles (B) is in the range from 0.1 to 2, more preferably in the range from 0.5 to 1 .2, in particular in the range from 0.75 to 1 .
  • the ratio of the total volume of the particles (B) to the total volume of the continuous matrix (A) can be varied in a wide range depending on the alkali-ion conducting properties of these two components.
  • the ratio of the total volume of the particles (B) to the total volume of the continuous matrix (A) is in the range from 95 / 5 to 20 / 80, more preferably in the range from 80 / 20 to 40 / 60.
  • the ratio of the volume fraction of the particles (B) to the volume fraction of the continuous matrix (A) is in the range from 19 to 0.25, more preferably in the range from 4 to 0.66.
  • the alkali-ion conducting separator assembly is characterized in that the ratio of the total volume of the particles (B) to the total volume of the continuous matrix (A) is in the range from 95 / 5 to 20 / 80, preferably in the range from 80 / 20 to 40 / 60.
  • the total mass of all particles (B) in the inventive alkali-ion conducting separator assembly is preferably least 20% by weight, more preferably at least 40% by weight, in particular in the range from 60% to 95% by weight based on the total weight of the alkali-ion conducting separa- tor assembly.
  • the mass fraction of all particles (B) in the inventive alkali-ion conducting separator assembly is preferably least 0.2, more preferably at least 0.4, in particular in the range from 0.60 to 0.95.
  • the sum of the total mass of matrix (A) and of the total mass of all particles (B) is preferably least 60% by weight, more preferably at least 80% by weight, in particular in the range from 90% up to 100% by weight based on the total weight of the alkali-ion conducting separator assembly.
  • the inventive alkali-ion conducting separator assembly which is an electrical insulator, shows preferably good wettability with respect to electrolytes, in particular to non-aqueous electrolytes, which are used in electrochemical cells.
  • inventive alkali-ion conducting separator assembly is preferably chemically inert against the components of the electrodes, more preferably chemically inert against anode components, in particular chemically inert against lithium in form of lithium metal or an alloy of lithium.
  • the inventive alkali-ion conducting separator assembly is impermeable to organic solvents, ensuring that only naked lithium cations can cross the separator, in particular through particles (B).
  • the alkali-ion conducting separator assembly is characterized in that the alkali-ion conducting separator assembly is impermeable to organic solvents.
  • the inventive alkali-ion conducting separator assembly is preferably produced as a freestanding separator, that is the inventive separator assembly is preferably produced independently of any electrode.
  • the free-standing separator is combined with other parts of an electrochemical cell, like anode or cathode, in a subsequent production step by the cell producer.
  • the alkali-ion conducting separator assembly is characterized in that the alkali-ion conducting separator assembly is a free-standing separator.
  • the present invention further provides a process for producing an alkali-ion conducting separa- tor assembly comprising
  • particles (B) of an alkali-ion conducting material and a liquid phase (A2) comprising at least one polymer or at least one polymerizable compound are deposited on a smooth surface of a solid or liquid phase (C).
  • the particles (B) of an alkali-ion conducting material which are deposited on a smooth surface of a solid or liquid phase (C), have been described above.
  • the particles (B) are preferably modified on their surface, in particular to adjust the hydrophilicity and hydrophobicity respectively, for example by coating the particles with a thin layer of a very hydrophobic material in order to minimize the contact of the particles with an aqueous phase (C) and to ensure a close contact to liquid phase (A2).
  • Liquid phase (A2) comprises a compound or a mixture of compounds, that can be solidified by evaporating volatile components like solvents, or by crystallization, vitrification or polymerization of an appropriate component.
  • liquid phase (A2) comprises at least one polymer or at least one polymerizable compound, which is also called monomer, preferably an organic compound, which can be polymerized in a radical polymerization, preferably using thermal initiators in particular using photoinitiators.
  • polymerizable compounds are for example acrylates or methacrylates.
  • Examples for preferred polymerizable organic compounds are trimethylolpropane triacrylate (Laromer ® TMPTA), trimethylolpropane trimethacrylate (TMPTMA), mixture of 7,9,9 and 7,7,9-trimethyl-4,13-dioxo-3,14-dioxa-5,12-diazahexadecan- 1 ,16-diol-dimethylacrylate (Plex 6661 -0 ® , HEMATMDI), 1 ,3-butanedioldimethylacrylat (1 ,3- BDDMA), 1 ,4-butanedioldimethylacrylat (1 ,4-BDDMA), ethyleneglycoldimethylacrylate (EGDMA) and divinylbenzene.
  • Laromer ® TMPTA trimethylolpropane trimethacrylate
  • TMPTMA trimethylolpropane trimethacrylate
  • EGDMA ethyleneglycoldimethylacrylate
  • Preferred solvents in liquid phase (A2) are non-polar, aprotic compounds such as toluene, which can be used in particular in combination with a liquid phase (C) comprising water or consisting of water.
  • the solid or liquid phase (C) is usually a phase that is immiscible with liquid phase (A2) and that can be easily separated from solidified phase (A2).
  • Examples of a suitable solid phase (C) are plates of salt, frozen liquid like ice, polyethylene, polypropylene or polytetrafluoroethylene or the electrode materials described in detail above.
  • Examples of a liquid phase (C) are water, ionic liquids, salt melts, aqueous salt solutions or liquid metals like mercury.
  • phase (C) neither reacts with particles (B) nor reacts with liquid phase (A2).
  • water is used as liquid phase (C) due to its non-toxic properties and high surface tension.
  • the density of liquid phase (C) can be adjusted by dis- solution of salts, such as metal halogenides to ensure that at least 50 % of the embedded particles (B) penetrate both sides of the continuous matrix (A) and are uncovered by matrix (A).
  • salts such as metal halogenides
  • ZnBr2 zinc bromide
  • the average particle size can be adjusted to the surface tension of liquid phase (C) in order to obtain the inventive alkali-ion conducting separators.
  • liquid phase (A2) is solidified by evaporating volatile components, crystallization, vitrification or polymerization in order to form matrix (A).
  • Process step (b) can be also described as hardening or curing. The person skilled in the art is aware of different systems and methodologies the convert a liquid phase under controlled conditions into a solid phase. De- pending on the physical properties of particles (B) or surface modified particles (B), in particular depending on their size in combination with their density and the hydrophilicity of their surface, the liquid phase (A2) and the solid or liquid phase (C) have to be chosen properly.
  • process step (c) the continuous matrix (A) with the embedded particles (B) is separated from the surface of phase (C).
  • process step (c) can be varied, for example the separation is simply done mechanically by taking off the inventive alkali-ion conducting separator assembly from either a solid or liquid phase (C) or after melting phase (C) or even after evaporating phase (C).
  • inventive alkali-ion conducting separator assemblies are particularly suitable as separator or as constituent of a separator in electrochemical cells, in particular in rechargeable electrochemical cells in order to separate anode from cathode in an electrochemical cell.
  • the separator assemblies can be obtained in the form of continuous belts which are processed further by the battery manufacturer, especially assembling the in- ventive separator assemblies with appropriate flat cathodes and flat anodes in order to produce electrochemical cells.
  • the term electrochemical cell or battery encompasses batteries, capacitors and accumulators (secondary batteries) of any type, in particular alkali metal cells or batteries such as lithium, lithium ion and alkaline earth metal batteries and accumulators, including in the form of high-energy or high-power systems, and also electrolyte capacitors and double-layer capacitors which are known under the names Supercaps, Goldcaps, BoostCaps or Ultracaps.
  • the present invention further provides an electrochemical cell, in particular a rechargeable electrochemical cell comprising at least one anode (a), (b) at least one cathode (b),
  • suitable cathode materials suitable anode materials, suitable electrolytes and possible arrangements
  • suitable monographs and reference works e.g. Wakihara et al. (editor): Lithium ion Batteries, 1 st edition, Wiley VCH, Weinheim, 1998; David Linden: Handbook of Batteries (McGraw-Hill Handbooks), 3 rd edition, Mcgraw-Hill Professional, New York 2008; J. O. Besenhard: Handbook of Battery Materials. Wiley-VCH, 1998.
  • Inventive cells are preferably selected from alkali metal containing cells. More preferably, in- ventive cells are selected from lithium-ion containing cells. In lithium-ion containing cells, the charge transport is effected by Li + ions.
  • the electrode where during discharging a net negative charge occurs is called the anode.
  • Anode (a) can be selected from anodes being based on various active materials.
  • Suitable active materials are metallic lithium, carbon-containing materials such as graphite, graphene, charcoal, expanded graphite, in particular graphite, furthermore lithium titanate (Li4Ti 5 0i2), anodes comprising In, Tl, Sb, Sn or Si, in particular Sn or Si, for example tin oxide (Sn02) or nanocrystalline silicon, and anodes comprising metallic lithium.
  • anode (a) is selected from graphite anodes, lithium titanate anodes, anodes comprising In, Tl, Sb, Sn or Si, and anodes comprising metallic lithium.
  • Anode (a) can further comprise a current collector.
  • Suitable current collectors are, e.g., metal wires, metal grids, metal gaze and preferably metal foils such as copper foils.
  • Anode (a) can further comprise a binder.
  • Suitable binders can be selected from organic
  • Suitable organic (co)polymers may be halogenated or halogen-free.
  • Examples are polyethylene oxide (PEO), cellulose, carboxymethyl cellulose, polyvinyl alcohol, polyethylene, polypropylene, polytetrafluoroethylene, polyacrylonitrile-methyl methacrylate, styrene- butadiene copolymers, tetrafluoroethylene-hexafluoropropylene copolymers, vinylidene fluoride- hexafluoropropylene copolymers (PVdF-HFP), vinylidene fluoride-tetrafluoroethylene copolymers, perfluoroalkyl vinyl ether copolymers, ethylene-tetrafluoroethylene copolymers, vinylidene fluoride-chlorotrifluoroethylene copolymers, ethylene-chlorofluoroethylene copolymers, eth- ylene-acrylic acid copolymers, optional
  • Suitable binders are especially polyvinyl alcohol and halogenated (co)polymers, for example polyvinyl chloride or polyvinylidene chloride, especially fluorinated (co)polymers such as polyvinyl fluoride and especially polyvinylidene fluoride and polytetrafluoroethylene.
  • the average molecular weight M w of binder may be selected within wide limits, suitable examples being 20,000 g/mol to 1 ,000,000 g/mol.
  • anode (a) can have a thickness in the range of from 15 to 200 ⁇ , preferably from 30 to 100 ⁇ , determined without the current collector.
  • Inventive cells further comprise a cathode (b).
  • Cathode (b) can contain solid, liquid or gaseous active materials, e. g., air (or oxygen). In a preferred embodiment, however, cathode (b) contains a solid active material.
  • Solid active materials for cathode (b) can be selected from phosphates with olivine structure such as lithium iron phosphates (LiFePC ) and lithium manganese phosphate (LiMnPC ) which can have a stoichiometric or non-stoichiometric composition and which can be doped or not doped.
  • phosphates with olivine structure such as lithium iron phosphates (LiFePC ) and lithium manganese phosphate (LiMnPC ) which can have a stoichiometric or non-stoichiometric composition and which can be doped or not doped.
  • active material for cathode (b) can be selected from lithium containing transition metal spinels and lithium transition metal oxides with a layered crystal structure.
  • cathode (b) contains at least one material selected from lithium containing transition metal spinels and lithium transition metal oxides with a layered crystal structure, respectively.
  • the electrochemical cell is characterized in that cathode (b) contains at least one material selected from lithium containing transition metal spinels and lithium transition metal oxides with a layered crystal structure.
  • lithium-containing metal spinels are selected from those of the general formula the variables being defined as follows: 0.9 ⁇ a ⁇ 1 .3, preferably 0.95 ⁇ a ⁇ 1 .15,
  • M 1 is selected from one or more out of Al, Mg, Ca, Na, B, Mo, W and transition metals of the first row of the transition metals in the periodic table of the elements.
  • M 1 is selected from the group consisting of Ni, Co, Cr, Zn, and Al. Even more preferably, M 1 is defined to be Ni.
  • lithium containing metal spinels are selected from LiNio,5Mni, 5 04-d and LiM ⁇ C .
  • lithium transition metal oxides with a layered crystal structure are selected from compounds of general formula (II) the variable being defined as follows: 0 ⁇ t ⁇ 0.3 und
  • M 2 selected from one or more elements from Al, Mg, B, Mo, W, Na, Ca and transition metals of the first row of the transition metals in the periodic table of the elements, at least one element being manganese.
  • At least 30 mole-% of M 2 are selected from manganese, preferably at least 35 mole-%, in each time with respect to the complete amount of M 2 .
  • M 2 is selected from combinations of Ni, Co and Mn not containing significant amounts of additional elements.
  • M 2 is selected from combinations of Ni, Co and Mn containing significant amounts of at least one additional element, for example in the range of from 1 to 10 mole-% Al, Ca or Na.
  • lithium transition metal oxides with a layered crystal structure are selected from compounds of general formula Li(i + x)[NieCOfMn g M 3 h](i-x)02 (III) the variables being defined as follows: x a number in the range of from zero to 0.2, e a number in the range of from 0.2 to 0.6, f a number in the range of from 0.1 to 0.5,
  • M 3 selected from Al, Mg, V, Fe, Cr, Zn, Cu, Ti and Mo.
  • M 2 in formula (II) is selected from Nio,33Coo,33Mno,33, Nio,5Coo,2Mn 0 ,3, Nio,4Coo,3Mn 0 ,4, Ni 0 ,4Coo,2Mn 0 ,4 und Ni 0 ,45Coo,ioMn 0 ,45.
  • Cathode (b) can further comprise a current collector.
  • Suitable current collectors are, e.g., metal wires, metal grids, metal gaze and preferably metal foils such as aluminum foils.
  • Cathode (b) can further comprise a binder. Suitable binders can be selected from organic
  • Suitable organic (co)polymers may be halogenated or halogen-free.
  • the same binders used for anode (a) can also be employed for cathode (b).
  • Preferred binders are especially polyvinyl alcohol and halogenated (co)polymers, for example polyvinyl chloride or polyvinylidene chloride, especially fluorinated (co)polymers such as polyvinyl fluoride and especially polyvinylidene fluoride and polytetrafluoroethylene.
  • cathode (b) can have a thickness in the range of from 15 to 200 ⁇ , preferably from 30 to 100 ⁇ , determined without the current collector.
  • Cathode (b) can further comprise electrically conductive carbonaceous material.
  • Electrically conductive carbonaceous material can be selected, for example, from graphite, carbon black, carbon nanotubes, graphene or mixtures of at least two of the aforementioned sub- stances.
  • electrically conductive, carbonaceous material can also be referred to as carbon for short.
  • electrically conductive carbonaceous material is carbon black.
  • Carbon black may, for example, be selected from lamp black, furnace black, flame black, thermal black, acetylene black and industrial black.
  • Carbon black may comprise impurities, for example hydrocarbons, especially aromatic hydrocarbons, or oxygen-containing compounds or oxygen-containing groups, for example OH groups.
  • sulfur- or iron- containing impurities are possible in carbon black.
  • electrically conductive carbonaceous material is partially oxidized carbon black.
  • the electrochemical cell is characterized in that cathode (b) contains a material based on electrically conductive carbon.
  • Inventive electrochemical cells further comprise, as well as the inventive alkali-ion conducting separator assembly, the cathode (a) and the anode (b), at least one electrolyte composition (c) comprising
  • Possible aprotic organic solvents (c1 ) may be liquid or solid at room temperature and are pref- erably liquid at room temperature.
  • Solvents (c1 ) are preferably selected from polymers, cyclic or noncyclic ethers, cyclic or noncyclic acetals, cyclic or noncyclic organic carbonates and ionic liquids.
  • the inventive rechargeable electrochemical cell is characterized in that the aprotic organic solvent (c1 ) is selected from polymers, cyclic or noncyclic ethers, noncyclic or cyclic acetals and cyclic or noncyclic organic carbonates.
  • the aprotic organic solvent (c1 ) is selected from polymers, cyclic or noncyclic ethers, noncyclic or cyclic acetals and cyclic or noncyclic organic carbonates.
  • suitable polymers are especially polyalkylene glycols, preferably poly-Ci-C4- alkylene glycols and especially polyethylene glycols.
  • Polyethylene glycols may comprise up to 20 mol% of one or more Ci-C4-alkylene glycols in copolymerized form.
  • Polyalkylene glycols are preferably doubly methyl- or ethyl-capped polyalkylene glycols.
  • the molecular weight M w of suitable polyalkylene glycols and especially of suitable polyethylene glycols may be at least 400 g/mol.
  • the molecular weight M w of suitable polyalkylene glycols and especially of suitable polyethylene glycols may be up to 5 000 000 g/mol, preferably up to 2 000 000 g/mol.
  • noncyclic ethers are, for example, diisopropyl ether, di-n-butyl ether, 1 ,2- dimethoxyethane, 1 ,2-diethoxyethane, preference being given to 1 ,2-dimethoxyethane.
  • Suitable cyclic ethers are tetrahydrofuran and 1 ,4-dioxane.
  • suitable noncyclic acetals are, for example, dimethoxymethane, diethoxymethane, 1 ,1 -dimethoxyethane and 1 ,1 -diethoxyethane.
  • Suitable cyclic acetals are 1 ,3-dioxane and especially 1 ,3-dioxolane.
  • noncyclic organic carbonates examples include dimethyl carbonate, ethyl methyl carbonate and diethyl carbonate.
  • Suitable cyclic organic carbonates are compounds of the general formulae (X) and (XI)
  • R 1 , R 2 and R 3 may be the same or different and are each selected from hydrogen and Ci-C4-alkyl, for example methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert- butyl, where R 2 and R 3 are preferably not both tert-butyl.
  • R 1 is methyl and R 2 and R 3 are each hydrogen, or R 1 , R 2 and R 3 are each hydrogen.
  • Another preferred cyclic organic carbonate is vinylene carbonate, formula (XII).
  • alkali metal salts (c2) which are used as conductive salts, have to be soluble in the aprotic organic solvent (c1 ).
  • Preferred alkali metal salts (c2) are lithium salts or sodium salts, in particular lithium salts.
  • the inventive rechargeable electrochemical cell is characterized in that the alkali metal salt (c2) is a lithium salt or sodium salt, preferably a lithium salt.
  • Suitable alkali metal salts are especially lithium salts. Examples of suitable lithium salts are LiPF 6 , LiBF 4 , UCIO4, LiAsFe, UCF3SO3, LiC(CnF 2n+ iS02)3, lithium imides such as
  • LiN(C n F2n+iS02)2 where n is an integer in the range from 1 to 20, LiN(S02F)2, Li2SiF6, LiSbF6, LiAICU, and salts of the general formula (C n F2n+iS02)mXLi, where m is defined as follows:
  • m 3 when X is selected from carbon and silicon.
  • Preferred alkali metal salts are selected from LiC(CF 3 S0 2 ) 3 , LiN(CF 3 S0 2 ) 2 , LiPF 6 , LiBF 4 , LiCI0 4 , and particular preference is given to LiPF6 and LiN(CFsS02)2.
  • the concentration of conductive salt in electrolyte is in the range of from 0.01 M to 5 M, preferably 0.5 M to 1 .5 M.
  • Inventive electrochemical cells further comprise as separator at least one inventive alkali-ion conducting separator assembly, which has been described above, wherein the separator assembly is positioned between anode (a) and cathode (b) in the electrochemical cells.
  • separator assembly is positioned between anode (a) and cathode (b) in a way that it is like a layer to either a major part of one surface of anode (a) or cathode (b).
  • separator assembly is positioned between anode (a) and cathode (b) in a way that it is like a layer to both a major part of one surface of anode (a) and cathode (b).
  • separator assembly is positioned between anode (a) and cathode (b) in a way that it is like a layer to one surface of anode (a) or of cathode (b). In another preferred embodiment of the present invention, separator assembly is positioned between anode (a) and cathode (b) in a way that it is like a layer to one surface of both anode (a) and of cathode (b).
  • inventive alkali-ion conducting separator assemblies have overall advantageous properties. They help to secure a long duration of electrochemical cells with very low loss of capacity, good cycling stability, and a reduced tendency towards short circuits after longer operation and/or repeated cycling. They can help batteries to have a long duration with very low loss of capacity, good cycling stability, and high temperature stability.
  • inventive electrochemical cells can contain additives such as wetting agents, corrosion inhibitors, or protective agents such as agents to protect any of the electrodes or agents to protect the salt(s).
  • inventive electrochemical cells can have a disc-like shape. In another embodiment, inventive electrochemical cells can have a prismatic shape.
  • inventive electrochemical cells can include a hous- ing that can be from steel or aluminium.
  • inventive electrochemical cells are combined to stacks including electrodes that are laminated. In one embodiment of the present invention, inventive electrochemical cells are selected from pouch cells.
  • Inventive electrochemical cells have overall advantageous properties. They have a long duration with very low loss of capacity, good cycling stability, and a reduced tendency towards short circuits after longer operation and/or repeated cycling.
  • a further aspect of the present invention refers to batteries, in particular to an alkali metal ion battery, comprising at least one inventive electrochemical cell, for example two or more.
  • inventive electrochemical cells can be combined with one another in inventive alkali metal ion batteries, for example in series connection or in parallel connection. Series connection is preferred.
  • Inventive batteries have advantageous properties. They have a long duration with very low loss of capacity, good cycling stability, and high temperature stability.
  • a further aspect of the present invention is the use of inventive electrochemical cells or inventive batteries according for making or operating cars, computers, personal digital assistants, mobile telephones, watches, camcorders, digital cameras, thermometers, calculators, laptop BIOS, communication equipment or remote car locks, and stationary applications such as ener- gy storage devices for power plants.
  • a further aspect of the present invention is a method of making or operating cars, computers, personal digital assistants, mobile telephones, watches, camcorders, digital cameras, thermometers, calculators, laptop BIOS, communication equipment, remote car locks, and stationary applications such as energy storage devices for power plants by employing at least one inventive battery or at least one inventive electrochemical cell.
  • the present invention further provides a device comprising at least one inventive electrochemical cell, in particular a rechargeable electrochemical cell as described above.
  • a device comprising at least one inventive electrochemical cell, in particular a rechargeable electrochemical cell as described above.
  • inventive electrochemical cell in particular a rechargeable electrochemical cell as described above.
  • Lithium-Aluminium-Titanium-Phosphate (LATP) particles of average diameter of DV 10 0.7 ⁇ , DV 50 1 .9 ⁇ , DV 90 5.2 ⁇ (1 g) were dispersed in demineralized water (75 ml.) and stirred for i h. Subsequently, the dispersion was centrifugalized and the water was decanted. This procedure was repeated 3 times. Then the particles were dried at ambient temperature under ambient atmosphere, and pressure overnight and then at 120 °C for 5 h.
  • a glass Petri dish of 5 cm diameter and 1.5 cm height was filled to half its height with demineralized water, placed on a dark surface and illuminated with a bright white light source from the top.
  • Approximately 1 .5 g of a mixture comprising LATP particles prepared in Example I., monomer (Visiomer ® -HEMATMDI, Evonic industries), photo initiator system (Esacure ® ITX/Esacure ® A 198, Lamberti S.p.A.,) and ethyl acetate (mass ratios 1 : 0.5 : 0.02 : 100) was applied to the water surface of the half-filled Petri dish using a syringe with a stainless steel needle, the needle tip touching the water surface.
  • Preparation of the membrane was conducted similar to the way of preparation detailed in ex- ample II with the following deviations.
  • a Langmuir trough (14.9 cm x 40.3 cm, KSV 3000) was filled with demineralized water and the movable barrier was positioned at the outmost position.
  • Approximately 9 g of a mixture comprising LATP particles, monomer, photo initiator and ethyl acetate (mass ratios 1 : 0.5 : 0.02 : 100) was applied to the water surface drop by drop using a syringe with a stainless steel needle within a period of approximately one minute.
  • the movable barrier was moved inwards at a speed of 0.2 to 0.5 m min- 1 until the area between the movable and the stationary barriers was approximately 14.9 cm x 8.5 cm.
  • the endpoint of lateral compression was determined by visual inspection, using the same criteria as detailed above.

Abstract

The present invention relates to an alkali-ion conducting separator assembly comprising as a first component (A) a continuous matrix (A) of at least one polymer, and as a second component (B) particles (B) of an alkali-ion conducting material, which are embedded in the continuous matrix (A), wherein at least 50 % of the embedded particles (B) penetrate both sides of the continuous matrix (A) and are uncovered by matrix (A). The present invention further relates to a process for producing such an alkali-ion conducting separator assembly and to an electrochemical cell comprising such an alkali-ion conducting separator assembly.

Description

Alkali-ion conducting composite membranes for electronic applications
Description The present invention relates to an alkali-ion conducting separator assembly comprising as a first component (A) a continuous matrix (A) of at least one polymer, and as a second component (B) particles (B) of an alkali-ion conducting material, which are embedded in the continuous matrix (A), wherein at least 50 % of the embedded particles (B) penetrate both sides of the continuous matrix (A) and are uncovered by matrix (A).
The present invention further relates to a process for producing such an alkali-ion conducting separator assembly and to an electrochemical cell comprising such an alkali-ion conducting separator assembly. Secondary batteries, accumulators or "rechargeable batteries" are just some embodiments by which electrical energy can be stored after generation and used when required. Owing to the significantly better power density, there has in recent times been a move away from the water- based secondary batteries toward development of those batteries in which the charge transport in the electrical cell is accomplished by lithium ions. Many components are of significance, such as the electrodes and the electrolyte. However, particular attention will be paid to the separator which physically separates the anode and the cathode, thereby preventing short circuits.
On one hand, the separator should allow lithium ions to pass. On the other hand, a separator should have the necessary mechanical properties to effectively separate anode and cathode from each other.
DE102007049203A1 and J. Am. Chem. Soc, 2013, 135 (1 1 ), pp 4380^1388 describe membranes, which comprise particles embedded in a continuous matrix, wherein at least 50 percent of the embedded particles at both and opposite surfaces of the membrane, are uncovered by the matrix. The membranes can be used for the separation of a desired compound from a mixture comprising that desired compound.
US201 1027642A describes a microporous polyolefin composite film with a thermally stable porous layer at high temperature, which is used as a separator for a high-capacity/high-power lith- ium secondary battery.
J. Eur. Ceram. Soc. 24 (2004) 1385-1387 describes PEO-based solid polymer electrolytes comprising nanosized Zr02 particles for building rechargeable lithium metal batteries. US 8,334,075 describes a composite solid electrolyte, which includes a monolithic solid electrolyte base component that is a continuous matrix of an inorganic active metal ion conductor and a filler component used to eliminate through porosity in the solid electrolyte. US 8,383,268 describes a lithium ion secondary battery, which includes a positive electrode, a negative electrode and a thin film solid electrolyte including lithium ion conductive inorganic substance. The thin film solid electrolyte has thickness of 20 μηη or below and is formed directly on an electrode material or materials for the positive electrode and/or the negative electrode.
The separators known from the literature, which comprise alkali-ion conducting materials, still have deficiencies in respect of one or more of the properties desired for such separators, for example low thickness, low weight per unit area, good mechanical stability during processing or in operation of the battery in respect of metal dendrite growth, good heat resistance, good ion conductivity and complete impermeability for organic solvents. Some of the deficiencies of the known separators are ultimately responsible for a reduced life or limited performance of the electrochemical cells comprising them. Furthermore, separators in principle have to be not only mechanically but also chemically stable toward the cathode materials, the anode materials and the electrolytes.
It was therefore an object of the invention to provide an inexpensive separator for a long-lived electrochemical cell, which has advantages in respect of one or more properties of a known separator, in particular a separator which displays sufficient ion conductivity, low thickness, high thermal stability and good mechanical properties, for example sufficient flexibility and sufficient stability with respect to growing metal dendrites.
This object is achieved by an alkali-ion conducting separator assembly comprising
(A) a continuous matrix (A) of at least one polymer, and
(B) particles (B) of an alkali-ion conducting material, which are embedded in the continuous matrix (A), wherein at least 50 % of the embedded particles (B) penetrate both sides of the continuous ma- trix (A) and are uncovered by matrix (A).
The inventive alkali-ion conducting separator assembly comprises a continuous matrix (A) of at least one polymer, also called matrix (A) for short, and particles (B) of an alkali-ion conducting material, also called particles (B) for short, which are embedded in the continuous matrix (A), wherein at least 50 %, preferably at least 80 %, more preferably at least 90 %, in particular at least 95% of the embedded particles (B) penetrate both sides of the continuous matrix (A) and are uncovered by matrix (A).
Preferably the particles, which penetrate both sides of the continuous matrix (A) and which are uncovered by matrix (A), expose a fraction of 10% to 40% of their total surface on each side of the continuous matrix (A), in particular these particles expose on each side of the continuous matrix (A) a similar fraction of their surface. Matrix (A) together with embedded particles (B) forms a layer or membrane which is permeable for alkali-ions, in particular for lithium ions, and which is electrically insulating. While particles (B) are alkali-ion conducting the matrix (A) itself can in principle be either alkali-ion conducting or non-alkali-ion conducting, depending on the nature of the polymer or mixture of polymers form- ing matrix (A). Preferably matrix (A) is a non-ion conducting matrix, in particular a non-alkali-ion conducting matrix.
In the context of the present invention the expression "electrically insulating" means, that the electrical conductivity of the alkali-ion conducting separator assembly is less than 10-8 S/cm at 25 °C.
In one embodiment of the present invention the alkali-ion conducting separator assembly is characterized in that the continuous matrix (A) is a non-ion conducting matrix, in particular a non-alkali-ion conducting matrix.
The polymer or mixture of polymers forming matrix (A) can be chosen from a wide range of polymers, for example organic polymers or inorganic polymers like polyphosphazenes or poly(organo)siloxanes, providing that the chosen polymer or mixture of polymers is insoluble or non-swellable, in particular insoluble in such solvents to which the inventive alkali-ion conduct- ing separator assembly is exposed in its designated application, in particular in electrochemical cells. Preferably the polymer is insoluble in aprotic organic solvents, more preferably insoluble in ethers, carbonates, amides, sulfoxides, sulfones or mixtures thereof, in particular insoluble in ethers, carbonates or mixtures thereof. In one embodiment of the present invention the alkali-ion conducting separator assembly is characterized in that the polymer of the continuous matrix (A) is a non-swellable polymer.
Suitable polymers are preferably hydrophobic polymers, which are obtainable from appropriate monomers, which are in particular polymerizable by UV initiators. Preferred examples of such monomers are trimethylolpropane triacrylate (Laromer®TMPTA), trimethylolpropane trimethacry- late (TMPTMA), mixture of 7,9,9 and 7,7,9-trimethyl-4,13-dioxo-3,14-dioxa-5,12- diazahexadecan-1 ,16-diol-dimethylacrylate (Plex 6661 -0®, HEMATMDI), 1 ,3- butanedioldimethylacrylat (1 ,3-BDDMA), 1 ,4-butanedioldimethylacrylat (1 ,4-BDDMA), eth- yleneglycoldimethylacrylate (EGDMA), divinylbenzene or mixtures thereof.
In principle the polymer forming matrix (A) can be linear, branched, ladder-like or cross-linked. Preferably the polymer of the continuous matrix (A) is a cross-linked polymer, in particular a cross-linked polyacrylate or polymethacrylate. In one embodiment of the present invention the alkali-ion conducting separator assembly is characterized in that the polymer of the continuous matrix (A) is a cross-linked polymer. The shape of the inventive alkali-ion conducting separator assembly is preferably the shape of a sheet or flat body. In the context of the present invention, the expression "flat" means that the alkali-ion conducting separator assembly described, a three-dimensional body, is smaller in one of its three spatial dimensions (extents), namely the thickness, with respect to the two other dimensions, the length and width. Typically, the thickness of the alkali-ion conducting separator assembly is less than the second-greatest dimension at least by a factor of 5, preferably at least by a factor of 10, more preferably at least by a factor of 20.
Since the inventive alkali-ion conducting separator assembly is flat, it can not only be incorporated as flat layer between cathode and anode, but can also, as required, be rolled up, wound up or folded as desired.
The thickness of matrix (A) of the inventive alkali-ion conducting separator assembly can be varied in a wide range. In particular the thickness of matrix (A) depends on the average diame- ter of particles (B), since both sides of matrix (A) should be penetrated by particles (B). Preferably matrix (A) has an average thickness in the range from 0.01 to 100 μηη, preferably in the range from 0.1 to 10 μηη.
In one embodiment of the present invention the alkali-ion conducting separator assembly is characterized in that the continuous matrix (A) has an average thickness in the range from 0.01 to 100 μηη, preferably in the range from 0.1 to 10 μηη.
Since at least 50 % of particles (B) of the inventive alkali-ion conducting separator assembly penetrate both sides of the continuous matrix (A) and are uncovered by matrix (A) preferably particles (B) form a monolayer in order to achieve that result.
In one embodiment of the present invention the alkali-ion conducting separator assembly is characterized in that the particles (B) form a monolayer. Particles (B) consist of an alkali-ion conducting material. Alkali-ion conducting materials, in particular lithium ion conducting materials are known to the person skilled in the art. Non limiting examples of suitable alkali-ion conducting materials are described in US 8,383,268, col. 3, line 42 to col. 4, line 60. Preferably the alkali-ion conducting material is selected from the group consisting of ceramics, sintered ceramics, glass-ceramics and glasses, more preferably well- known Li ion conducting inorganic solid lithium ion conductors as described by P. Knauth in Solid State Ionics 180 (2009) 91 1 -916 or by A. Hayashi and M. Tatsumisago in Electronic Materials Letters 8 (2012) 199-207. In particular, ceramic materials with the perovskite, Nasicon, Thio- Lisicon or garnet crystal structure offer good conductivities, but also inorganic sulfide glasses in powder form are good candidates.
In one embodiment of the present invention the alkali-ion conducting separator assembly is characterized in that the alkali-ion conducting material is selected from the group consisting of ceramics, sintered ceramics, glass-ceramics and glasses. The average diameter of particles (B) can be varied in a wide range. Preferably the average diameter of particles (B) is in the range from 0.1 to 10 μηη, more preferably in the range from 0.3 to 5 μηη, in particular in the range from 0.5 to 2 μηη.
The particle size distribution was determined by means of laser diffraction technology in powder form to DIN ISO 13320-1 with a Mastersizer from Malvern Instruments GmbH, Herrenberg, Germany. The crucial value for the mean particle size is what is called the d90 value. The d90 value of the volume-weighted distribution is that particle size for which 90% of the particle vol- ume of particles are smaller than or equal to the d90 value.
In one embodiment of the present invention the alkali-ion conducting separator assembly is characterized in that the average diameter of particles (B) is in the range from 0.1 to 10 μηη. In principle the shape of particles (B) can be freely chosen, but platelets and in particular cubes offer a better contact area for lithium ion transfer and can be arranged into a very high volume percentage of matrix (A).
In one embodiment of the present invention the alkali-ion conducting separator assembly is characterized in that the shape of particles (B) is the shape of platelets or of cubes, in particular of cubes.
Especially if particles (B) are arranged in a monolayer it is extremely important to have a narrow particle size distribution, because particles which are significantly thinner or smaller than the average particles would not protrude on both sides of matrix (A). Particles (B) of an alkali-ion conducting material can be obtained from the corresponding material in macroscopic size by grinding processes resulting in a very wide particle size distribution. In such a case
over/undersize particles may be removed by suitable and well-established methods like filtration, sieving and sifting. The ratio of d50 to d10 and also d90 to d50 should be below 3, prefera- bly below 2.
In one embodiment of the present invention the alkali-ion conducting separator assembly is characterized in that the ratio of the d50 value to the d10 value and of the d90 value to the d50 value of the particle size distribution of particles (B) is below 3, preferably below 2.
Particles in the shape of platelets or cubes are preferably obtained by using wet-chemical synthesis routes, which offer better control of the particle morphology than grinding methods.
The ratio of the average thickness of the continuous matrix (A) to the average diameter of parti- cles (B) can be varied in a wide range. Preferably the ratio of the average thickness of the continuous matrix (A) to the average diameter of particles (B) is in the range from 0.1 to 10, more preferably in the range from 0.5 to 5, in particular in the range from 0.75 to 3. More preferably the ratio of the average thickness of the continuous matrix (A) to the average diameter of parti- cles (B) is in the range from 0.1 to 2, more preferably in the range from 0.5 to 1 .2, in particular in the range from 0.75 to 1 .
In one embodiment of the present invention the alkali-ion conducting separator assembly is characterized in that the ratio of the average thickness of the continuous matrix (A) to the average diameter of particles (B) is in the range from 0.1 to 10, preferably in the range from 0.5 to 5, in particular in the range from 0.75 to 3.
In another embodiment of the present invention the alkali-ion conducting separator assembly is characterized in that the ratio of the average thickness of the continuous matrix (A) to the average diameter of particles (B) is in the range from 0.1 to 2, more preferably in the range from 0.5 to 1 .2, in particular in the range from 0.75 to 1 .
The ratio of the total volume of the particles (B) to the total volume of the continuous matrix (A) can be varied in a wide range depending on the alkali-ion conducting properties of these two components. Preferably the ratio of the total volume of the particles (B) to the total volume of the continuous matrix (A) is in the range from 95 / 5 to 20 / 80, more preferably in the range from 80 / 20 to 40 / 60. This means in other words that preferably the ratio of the volume fraction of the particles (B) to the volume fraction of the continuous matrix (A) is in the range from 19 to 0.25, more preferably in the range from 4 to 0.66.
In one embodiment of the present invention the alkali-ion conducting separator assembly is characterized in that the ratio of the total volume of the particles (B) to the total volume of the continuous matrix (A) is in the range from 95 / 5 to 20 / 80, preferably in the range from 80 / 20 to 40 / 60.
The total mass of all particles (B) in the inventive alkali-ion conducting separator assembly is preferably least 20% by weight, more preferably at least 40% by weight, in particular in the range from 60% to 95% by weight based on the total weight of the alkali-ion conducting separa- tor assembly. This means in other words that the mass fraction of all particles (B) in the inventive alkali-ion conducting separator assembly is preferably least 0.2, more preferably at least 0.4, in particular in the range from 0.60 to 0.95.
The sum of the total mass of matrix (A) and of the total mass of all particles (B) is preferably least 60% by weight, more preferably at least 80% by weight, in particular in the range from 90% up to 100% by weight based on the total weight of the alkali-ion conducting separator assembly. This means in other words that the sum of the mass fraction of matrix (A) and of the mass fraction of all particles (B) is preferably least 0.60, more preferably at least 0.80, in particular in the range from 0.90 up to 1 .
The inventive alkali-ion conducting separator assembly, which is an electrical insulator, shows preferably good wettability with respect to electrolytes, in particular to non-aqueous electrolytes, which are used in electrochemical cells. In addition the inventive alkali-ion conducting separator assembly is preferably chemically inert against the components of the electrodes, more preferably chemically inert against anode components, in particular chemically inert against lithium in form of lithium metal or an alloy of lithium. Particularly preferred the inventive alkali-ion conducting separator assembly is impermeable to organic solvents, ensuring that only naked lithium cations can cross the separator, in particular through particles (B).
In one embodiment of the present invention the alkali-ion conducting separator assembly is characterized in that the alkali-ion conducting separator assembly is impermeable to organic solvents.
The inventive alkali-ion conducting separator assembly is preferably produced as a freestanding separator, that is the inventive separator assembly is preferably produced independently of any electrode. The free-standing separator is combined with other parts of an electrochemical cell, like anode or cathode, in a subsequent production step by the cell producer.
In one embodiment of the present invention the alkali-ion conducting separator assembly is characterized in that the alkali-ion conducting separator assembly is a free-standing separator.
The present invention further provides a process for producing an alkali-ion conducting separa- tor assembly comprising
(A) a continuous matrix (A) of at least one polymer, and
(B) particles (B) of an alkali-ion conducting material, which are embedded in the continuous matrix (A), wherein at least 50 % of the embedded particles (B) penetrate both sides of the continuous matrix (A) and are uncovered by matrix (A), comprising the process steps of (a) depositing particles (B) of an alkali-ion conducting material and a liquid phase (A2) comprising at least one polymer or at least one polymerizable compound on a smooth surface of a solid or liquid phase (C),
(b) solidifying liquid phase (A2) by evaporating volatile components, crystallization, vitrifica- tion or polymerization, and
(c) separating the continuous matrix (A) with the embedded particles (B) from the surface of phase (C). The description and preferred embodiments of the alkali-ion conducting separator assembly and its components, in particular the description of the continuous matrix (A) as a first component and of the particles (B) as a second component, in the process of the invention correspond to the above description of these components for the alkali-ion conducting separator assembly of the invention.
Different embodiments of the inventive process comprising process steps a), b) and c) are pre- sented in figures 1 to 4 of DE102007049203A1 and in J. Am. Chem. Soc, 2013, 135 (1 1 ), pp 4380^1388.
In process step (a) particles (B) of an alkali-ion conducting material and a liquid phase (A2) comprising at least one polymer or at least one polymerizable compound are deposited on a smooth surface of a solid or liquid phase (C).
The particles (B) of an alkali-ion conducting material, which are deposited on a smooth surface of a solid or liquid phase (C), have been described above. Depending on the nature of phase (C) and depending on the nature of liquid phase (A2) the particles (B) are preferably modified on their surface, in particular to adjust the hydrophilicity and hydrophobicity respectively, for example by coating the particles with a thin layer of a very hydrophobic material in order to minimize the contact of the particles with an aqueous phase (C) and to ensure a close contact to liquid phase (A2). Preferably Lisicon-type Lii.3Alo.3Tii.7(P04)3 (LATP) is used as alkali-ion conducting material due to its non-sensitivity to ambient conditions (humidity, carbon dioxide). Pref- erably the surface of the alkali-ion conducting material is modified to increase its hydrophobicity. Surface modification is preferably carried out by treatment with silanes such as 1 H, 1 H, 2H, 2H- perflurooctyltriethoxysilane (PFOTES), but also halogenated silanes or phosphonic acids can be used for surface modification. Liquid phase (A2) comprises a compound or a mixture of compounds, that can be solidified by evaporating volatile components like solvents, or by crystallization, vitrification or polymerization of an appropriate component. Preferably liquid phase (A2) comprises at least one polymer or at least one polymerizable compound, which is also called monomer, preferably an organic compound, which can be polymerized in a radical polymerization, preferably using thermal initiators in particular using photoinitiators. Particularly preferred suitable polymerizable compounds are for example acrylates or methacrylates. Examples for preferred polymerizable organic compounds are trimethylolpropane triacrylate (Laromer®TMPTA), trimethylolpropane trimethacrylate (TMPTMA), mixture of 7,9,9 and 7,7,9-trimethyl-4,13-dioxo-3,14-dioxa-5,12-diazahexadecan- 1 ,16-diol-dimethylacrylate (Plex 6661 -0®, HEMATMDI), 1 ,3-butanedioldimethylacrylat (1 ,3- BDDMA), 1 ,4-butanedioldimethylacrylat (1 ,4-BDDMA), ethyleneglycoldimethylacrylate (EGDMA) and divinylbenzene. Preferred solvents in liquid phase (A2) are non-polar, aprotic compounds such as toluene, which can be used in particular in combination with a liquid phase (C) comprising water or consisting of water. The solid or liquid phase (C) is usually a phase that is immiscible with liquid phase (A2) and that can be easily separated from solidified phase (A2). Examples of a suitable solid phase (C) are plates of salt, frozen liquid like ice, polyethylene, polypropylene or polytetrafluoroethylene or the electrode materials described in detail above. Examples of a liquid phase (C) are water, ionic liquids, salt melts, aqueous salt solutions or liquid metals like mercury. Preferably phase (C) neither reacts with particles (B) nor reacts with liquid phase (A2). Preferably water is used as liquid phase (C) due to its non-toxic properties and high surface tension. Depending on the density of the alkali-ion conducting material, the density of liquid phase (C) can be adjusted by dis- solution of salts, such as metal halogenides to ensure that at least 50 % of the embedded particles (B) penetrate both sides of the continuous matrix (A) and are uncovered by matrix (A). In one embodiment zinc bromide (ZnBr2) is added to water in order to increase density of liquid phase (C). As alternative, the average particle size can be adjusted to the surface tension of liquid phase (C) in order to obtain the inventive alkali-ion conducting separators.
In process step (b) liquid phase (A2) is solidified by evaporating volatile components, crystallization, vitrification or polymerization in order to form matrix (A). Process step (b) can be also described as hardening or curing. The person skilled in the art is aware of different systems and methodologies the convert a liquid phase under controlled conditions into a solid phase. De- pending on the physical properties of particles (B) or surface modified particles (B), in particular depending on their size in combination with their density and the hydrophilicity of their surface, the liquid phase (A2) and the solid or liquid phase (C) have to be chosen properly.
In process step (c) the continuous matrix (A) with the embedded particles (B) is separated from the surface of phase (C). Depending on the physical nature of phase (C) process step (c) can be varied, for example the separation is simply done mechanically by taking off the inventive alkali-ion conducting separator assembly from either a solid or liquid phase (C) or after melting phase (C) or even after evaporating phase (C). The inventive alkali-ion conducting separator assemblies are particularly suitable as separator or as constituent of a separator in electrochemical cells, in particular in rechargeable electrochemical cells in order to separate anode from cathode in an electrochemical cell. By the above-described process the separator assemblies can be obtained in the form of continuous belts which are processed further by the battery manufacturer, especially assembling the in- ventive separator assemblies with appropriate flat cathodes and flat anodes in order to produce electrochemical cells.
For the purposes of the present invention, the term electrochemical cell or battery encompasses batteries, capacitors and accumulators (secondary batteries) of any type, in particular alkali metal cells or batteries such as lithium, lithium ion and alkaline earth metal batteries and accumulators, including in the form of high-energy or high-power systems, and also electrolyte capacitors and double-layer capacitors which are known under the names Supercaps, Goldcaps, BoostCaps or Ultracaps. The present invention further provides an electrochemical cell, in particular a rechargeable electrochemical cell comprising at least one anode (a), (b) at least one cathode (b),
(c) at least one electrolyte composition (c) comprising at least one aprotic organic solvent (c1 ), and
(c2) at least one alkali metal salt (c2), and (d) at least one alkali-ion conducting separator assembly as described above.
As regards suitable cathode materials, suitable anode materials, suitable electrolytes and possible arrangements, reference is made to the relevant prior art, e.g. appropriate monographs and reference works: e.g. Wakihara et al. (editor): Lithium ion Batteries, 1 st edition, Wiley VCH, Weinheim, 1998; David Linden: Handbook of Batteries (McGraw-Hill Handbooks), 3rd edition, Mcgraw-Hill Professional, New York 2008; J. O. Besenhard: Handbook of Battery Materials. Wiley-VCH, 1998.
Inventive cells are preferably selected from alkali metal containing cells. More preferably, in- ventive cells are selected from lithium-ion containing cells. In lithium-ion containing cells, the charge transport is effected by Li+ ions.
In the context with the present invention, the electrode where during discharging a net negative charge occurs is called the anode.
Anode (a) can be selected from anodes being based on various active materials. Suitable active materials are metallic lithium, carbon-containing materials such as graphite, graphene, charcoal, expanded graphite, in particular graphite, furthermore lithium titanate (Li4Ti50i2), anodes comprising In, Tl, Sb, Sn or Si, in particular Sn or Si, for example tin oxide (Sn02) or nanocrystalline silicon, and anodes comprising metallic lithium.
In one embodiment of the present invention the electrochemical cell is characterized in that anode (a) is selected from graphite anodes, lithium titanate anodes, anodes comprising In, Tl, Sb, Sn or Si, and anodes comprising metallic lithium.
Anode (a) can further comprise a current collector. Suitable current collectors are, e.g., metal wires, metal grids, metal gaze and preferably metal foils such as copper foils.
Anode (a) can further comprise a binder. Suitable binders can be selected from organic
(co)polymers. Suitable organic (co)polymers may be halogenated or halogen-free. Examples are polyethylene oxide (PEO), cellulose, carboxymethyl cellulose, polyvinyl alcohol, polyethylene, polypropylene, polytetrafluoroethylene, polyacrylonitrile-methyl methacrylate, styrene- butadiene copolymers, tetrafluoroethylene-hexafluoropropylene copolymers, vinylidene fluoride- hexafluoropropylene copolymers (PVdF-HFP), vinylidene fluoride-tetrafluoroethylene copolymers, perfluoroalkyl vinyl ether copolymers, ethylene-tetrafluoroethylene copolymers, vinylidene fluoride-chlorotrifluoroethylene copolymers, ethylene-chlorofluoroethylene copolymers, eth- ylene-acrylic acid copolymers, optionally at least partially neutralized with alkali metal salt or ammonia, ethylene-methacrylic acid copolymers, optionally at least partially neutralized with alkali metal salt or ammonia, ethylene-(meth)acrylic ester copolymers, polysulfones, polyimides and polyisobutene.
Suitable binders are especially polyvinyl alcohol and halogenated (co)polymers, for example polyvinyl chloride or polyvinylidene chloride, especially fluorinated (co)polymers such as polyvinyl fluoride and especially polyvinylidene fluoride and polytetrafluoroethylene.
The average molecular weight Mw of binder may be selected within wide limits, suitable examples being 20,000 g/mol to 1 ,000,000 g/mol.
In one embodiment of the present invention, anode (a) can have a thickness in the range of from 15 to 200 μηη, preferably from 30 to 100 μηη, determined without the current collector.
Inventive cells further comprise a cathode (b). Cathode (b) can contain solid, liquid or gaseous active materials, e. g., air (or oxygen). In a preferred embodiment, however, cathode (b) contains a solid active material.
Solid active materials for cathode (b) can be selected from phosphates with olivine structure such as lithium iron phosphates (LiFePC ) and lithium manganese phosphate (LiMnPC ) which can have a stoichiometric or non-stoichiometric composition and which can be doped or not doped.
In one embodiment of the present invention, active material for cathode (b) can be selected from lithium containing transition metal spinels and lithium transition metal oxides with a layered crystal structure. In such cases, cathode (b) contains at least one material selected from lithium containing transition metal spinels and lithium transition metal oxides with a layered crystal structure, respectively.
In one embodiment of the present invention the electrochemical cell is characterized in that cathode (b) contains at least one material selected from lithium containing transition metal spinels and lithium transition metal oxides with a layered crystal structure.
In one embodiment of the present invention, lithium-containing metal spinels are selected from those of the general formula
Figure imgf000012_0001
the variables being defined as follows: 0.9 < a < 1 .3, preferably 0.95 < a < 1 .15,
0 < b < 0.6, for example 0.0 or 0.5, wherein, if M1 = Ni, 0.4 < b < 0.55,
-0.1 < d < 0.4, preferably 0 < d < 0.1 , M1 is selected from one or more out of Al, Mg, Ca, Na, B, Mo, W and transition metals of the first row of the transition metals in the periodic table of the elements. In a preferred embodiment, M1 is selected from the group consisting of Ni, Co, Cr, Zn, and Al. Even more preferably, M1 is defined to be Ni. In one embodiment of the present invention, lithium containing metal spinels are selected from LiNio,5Mni,504-d and LiM^C .
In one embodiment of the present invention, lithium transition metal oxides with a layered crystal structure are selected from compounds of general formula (II)
Figure imgf000013_0001
the variable being defined as follows: 0 < t≤0.3 und
M2 selected from one or more elements from Al, Mg, B, Mo, W, Na, Ca and transition metals of the first row of the transition metals in the periodic table of the elements, at least one element being manganese.
In one embodiment of the present invention, at least 30 mole-% of M2 are selected from manganese, preferably at least 35 mole-%, in each time with respect to the complete amount of M2.
In one embodiment of the present invention M2 is selected from combinations of Ni, Co and Mn not containing significant amounts of additional elements.
In a different embodiment of the present invention M2 is selected from combinations of Ni, Co and Mn containing significant amounts of at least one additional element, for example in the range of from 1 to 10 mole-% Al, Ca or Na.
In a particular embodiment of the present invention, lithium transition metal oxides with a layered crystal structure are selected from compounds of general formula Li(i+x)[NieCOfMngM3h](i-x)02 (III) the variables being defined as follows: x a number in the range of from zero to 0.2, e a number in the range of from 0.2 to 0.6, f a number in the range of from 0.1 to 0.5,
9 a number in the range of from 0.2 to 0.6, h a number in the range of from zero to 0.1 , and: e + f + g + h = 1 ,
M3 selected from Al, Mg, V, Fe, Cr, Zn, Cu, Ti and Mo.
In one embodiment of the present invention, M2 in formula (II) is selected from Nio,33Coo,33Mno,33, Nio,5Coo,2Mn0,3, Nio,4Coo,3Mn0,4, Ni0,4Coo,2Mn0,4 und Ni0,45Coo,ioMn0,45.
Cathode (b) can further comprise a current collector. Suitable current collectors are, e.g., metal wires, metal grids, metal gaze and preferably metal foils such as aluminum foils. Cathode (b) can further comprise a binder. Suitable binders can be selected from organic
(co)polymers. Suitable organic (co)polymers may be halogenated or halogen-free. In general, the same binders used for anode (a) can also be employed for cathode (b).
Preferred binders are especially polyvinyl alcohol and halogenated (co)polymers, for example polyvinyl chloride or polyvinylidene chloride, especially fluorinated (co)polymers such as polyvinyl fluoride and especially polyvinylidene fluoride and polytetrafluoroethylene.
In one embodiment of the present invention, cathode (b) can have a thickness in the range of from 15 to 200 μηη, preferably from 30 to 100 μηη, determined without the current collector.
Cathode (b) can further comprise electrically conductive carbonaceous material.
Electrically conductive carbonaceous material can be selected, for example, from graphite, carbon black, carbon nanotubes, graphene or mixtures of at least two of the aforementioned sub- stances. In the context of the present invention, electrically conductive, carbonaceous material can also be referred to as carbon for short. In one embodiment of the present invention, electrically conductive carbonaceous material is carbon black. Carbon black may, for example, be selected from lamp black, furnace black, flame black, thermal black, acetylene black and industrial black. Carbon black may comprise impurities, for example hydrocarbons, especially aromatic hydrocarbons, or oxygen-containing compounds or oxygen-containing groups, for example OH groups. In addition, sulfur- or iron- containing impurities are possible in carbon black.
In one variant, electrically conductive carbonaceous material is partially oxidized carbon black. In one embodiment of the present invention the electrochemical cell is characterized in that cathode (b) contains a material based on electrically conductive carbon.
Inventive electrochemical cells further comprise, as well as the inventive alkali-ion conducting separator assembly, the cathode (a) and the anode (b), at least one electrolyte composition (c) comprising
(c1 ) at least one aprotic organic solvent (c1 ), and
(c2) at least one alkali metal salt (c2).
Possible aprotic organic solvents (c1 ) may be liquid or solid at room temperature and are pref- erably liquid at room temperature. Solvents (c1 ) are preferably selected from polymers, cyclic or noncyclic ethers, cyclic or noncyclic acetals, cyclic or noncyclic organic carbonates and ionic liquids.
In one embodiment of the present invention the inventive rechargeable electrochemical cell is characterized in that the aprotic organic solvent (c1 ) is selected from polymers, cyclic or noncyclic ethers, noncyclic or cyclic acetals and cyclic or noncyclic organic carbonates.
Examples of suitable polymers are especially polyalkylene glycols, preferably poly-Ci-C4- alkylene glycols and especially polyethylene glycols. Polyethylene glycols may comprise up to 20 mol% of one or more Ci-C4-alkylene glycols in copolymerized form. Polyalkylene glycols are preferably doubly methyl- or ethyl-capped polyalkylene glycols.
The molecular weight Mw of suitable polyalkylene glycols and especially of suitable polyethylene glycols may be at least 400 g/mol.
The molecular weight Mw of suitable polyalkylene glycols and especially of suitable polyethylene glycols may be up to 5 000 000 g/mol, preferably up to 2 000 000 g/mol.
Examples of suitable noncyclic ethers are, for example, diisopropyl ether, di-n-butyl ether, 1 ,2- dimethoxyethane, 1 ,2-diethoxyethane, preference being given to 1 ,2-dimethoxyethane.
Examples of suitable cyclic ethers are tetrahydrofuran and 1 ,4-dioxane. Examples of suitable noncyclic acetals are, for example, dimethoxymethane, diethoxymethane, 1 ,1 -dimethoxyethane and 1 ,1 -diethoxyethane.
Examples of suitable cyclic acetals are 1 ,3-dioxane and especially 1 ,3-dioxolane.
Examples of suitable noncyclic organic carbonates are dimethyl carbonate, ethyl methyl carbonate and diethyl carbonate.
Examples of suitable cyclic organic carbonates are compounds of the general formulae (X) and (XI)
Figure imgf000016_0001
in which R1, R2 and R3 may be the same or different and are each selected from hydrogen and Ci-C4-alkyl, for example methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert- butyl, where R2 and R3 are preferably not both tert-butyl.
In particularly preferred embodiments, R1 is methyl and R2 and R3 are each hydrogen, or R1, R2 and R3 are each hydrogen. Another preferred cyclic organic carbonate is vinylene carbonate, formula (XII).
O
X
0 ° (XII)
Preference is given to using the solvent(s) in what is called the anhydrous state, i.e. with a water content in the range from 1 ppm to 0.1 % by weight, determinable, for example, by Karl Fischer titration.
Possible alkali metal salts (c2), which are used as conductive salts, have to be soluble in the aprotic organic solvent (c1 ). Preferred alkali metal salts (c2) are lithium salts or sodium salts, in particular lithium salts. In one embodiment of the present invention the inventive rechargeable electrochemical cell is characterized in that the alkali metal salt (c2) is a lithium salt or sodium salt, preferably a lithium salt. Suitable alkali metal salts are especially lithium salts. Examples of suitable lithium salts are LiPF6, LiBF4, UCIO4, LiAsFe, UCF3SO3, LiC(CnF2n+iS02)3, lithium imides such as
LiN(CnF2n+iS02)2, where n is an integer in the range from 1 to 20, LiN(S02F)2, Li2SiF6, LiSbF6, LiAICU, and salts of the general formula (CnF2n+iS02)mXLi, where m is defined as follows:
m = 1 when X is selected from oxygen and sulfur,
m = 2 when X is selected from nitrogen and phosphorus, and
m = 3 when X is selected from carbon and silicon.
Preferred alkali metal salts are selected from LiC(CF3S02)3, LiN(CF3S02)2, LiPF6, LiBF4, LiCI04, and particular preference is given to LiPF6 and LiN(CFsS02)2.
In one embodiment of the present invention, the concentration of conductive salt in electrolyte is in the range of from 0.01 M to 5 M, preferably 0.5 M to 1 .5 M.
Inventive electrochemical cells further comprise as separator at least one inventive alkali-ion conducting separator assembly, which has been described above, wherein the separator assembly is positioned between anode (a) and cathode (b) in the electrochemical cells.
In one embodiment of the present invention, separator assembly is positioned between anode (a) and cathode (b) in a way that it is like a layer to either a major part of one surface of anode (a) or cathode (b).
In one embodiment of the present invention, separator assembly is positioned between anode (a) and cathode (b) in a way that it is like a layer to both a major part of one surface of anode (a) and cathode (b).
In a preferred embodiment of the present invention, separator assembly is positioned between anode (a) and cathode (b) in a way that it is like a layer to one surface of anode (a) or of cathode (b). In another preferred embodiment of the present invention, separator assembly is positioned between anode (a) and cathode (b) in a way that it is like a layer to one surface of both anode (a) and of cathode (b).
Inventive alkali-ion conducting separator assemblies have overall advantageous properties. They help to secure a long duration of electrochemical cells with very low loss of capacity, good cycling stability, and a reduced tendency towards short circuits after longer operation and/or repeated cycling. They can help batteries to have a long duration with very low loss of capacity, good cycling stability, and high temperature stability. In one embodiment of the present invention, inventive electrochemical cells can contain additives such as wetting agents, corrosion inhibitors, or protective agents such as agents to protect any of the electrodes or agents to protect the salt(s).
In one embodiment of the present invention, inventive electrochemical cells can have a disc-like shape. In another embodiment, inventive electrochemical cells can have a prismatic shape.
In one embodiment of the present invention, inventive electrochemical cells can include a hous- ing that can be from steel or aluminium.
In one embodiment of the present invention, inventive electrochemical cells are combined to stacks including electrodes that are laminated. In one embodiment of the present invention, inventive electrochemical cells are selected from pouch cells.
Inventive electrochemical cells have overall advantageous properties. They have a long duration with very low loss of capacity, good cycling stability, and a reduced tendency towards short circuits after longer operation and/or repeated cycling.
A further aspect of the present invention refers to batteries, in particular to an alkali metal ion battery, comprising at least one inventive electrochemical cell, for example two or more. Inventive electrochemical cells can be combined with one another in inventive alkali metal ion batteries, for example in series connection or in parallel connection. Series connection is preferred.
Inventive batteries have advantageous properties. They have a long duration with very low loss of capacity, good cycling stability, and high temperature stability.
A further aspect of the present invention is the use of inventive electrochemical cells or inventive batteries according for making or operating cars, computers, personal digital assistants, mobile telephones, watches, camcorders, digital cameras, thermometers, calculators, laptop BIOS, communication equipment or remote car locks, and stationary applications such as ener- gy storage devices for power plants. A further aspect of the present invention is a method of making or operating cars, computers, personal digital assistants, mobile telephones, watches, camcorders, digital cameras, thermometers, calculators, laptop BIOS, communication equipment, remote car locks, and stationary applications such as energy storage devices for power plants by employing at least one inventive battery or at least one inventive electrochemical cell.
The present invention further provides a device comprising at least one inventive electrochemical cell, in particular a rechargeable electrochemical cell as described above. The invention is illustrated by the examples which follow but do not restrict the invention.
Figures in percent are each based on % by weight, unless explicitly stated otherwise.
I. Preparation of hydrophobized Particles
Lithium-Aluminium-Titanium-Phosphate (LATP) particles of average diameter of DV 10 0.7 μηη, DV 50 1 .9 μηη, DV 90 5.2 μηη (1 g) were dispersed in demineralized water (75 ml.) and stirred for i h. Subsequently, the dispersion was centrifugalized and the water was decanted. This procedure was repeated 3 times. Then the particles were dried at ambient temperature under ambient atmosphere, and pressure overnight and then at 120 °C for 5 h. They were added to a solution of 1 H,1 H,2H,2H-perfluorooctyltriethoxysilane (PFOTES) (0.27 g) in toluene (43.5 g) and stirred for 48 h. Subsequently, the particles were recovered by centrifugation and decanting the supernatant, washed with toluene, acetone and ethanol (each time followed by centrifugation and decanting the supernatant). Afterwards they were dried at ambient temperature under ambient atmosphere, and pressure at 130 °C for 5 h.
II. Preparation of composite membranes by float-casting without lateral compression on a Petri dish
A glass Petri dish of 5 cm diameter and 1.5 cm height was filled to half its height with demineralized water, placed on a dark surface and illuminated with a bright white light source from the top. Approximately 1 .5 g of a mixture comprising LATP particles prepared in Example I., monomer (Visiomer®-HEMATMDI, Evonic industries), photo initiator system (Esacure® ITX/Esacure® A 198, Lamberti S.p.A.,) and ethyl acetate (mass ratios = 1 : 0.5 : 0.02 : 100) was applied to the water surface of the half-filled Petri dish using a syringe with a stainless steel needle, the needle tip touching the water surface. The exact amount to be spread was determined by visual inspec- tion: Spreading initially gives rise to translucent patches on the water surface that differ in reflectivity from the original water surface and are visible if inspected at a shallow angle. Towards the end of the spreading these patches merge into a continuous layer. If the amount of solution applied exceeds the desired amount, white opaque schlieren appear on the water surface. If even more solution is applied, one observes in addition white opaque patches on the water sur- face. After spreading, the layer was exposed to air for 1 h (to evaporate the volatile compounds). Subsequently an arc discharge lamp with a primary emission wavelength at 395 nm (PC-2000/38003 of Dymax corp) was mounted 10 cm above the petri dish. The lamp was operated for 30 min, illuminating the layer with an intensity of 50 mW/cm2. This illumination gave rise to a solidification of the layer. Subsequently the layer was lifted off the water surface using ei- ther continuous silicon or metal substrates, filter paper or metal grids. III. Preparation of composite membranes by float-casting with lateral compression on a Langmuir trough
Preparation of the membrane was conducted similar to the way of preparation detailed in ex- ample II with the following deviations. A Langmuir trough (14.9 cm x 40.3 cm, KSV 3000) was filled with demineralized water and the movable barrier was positioned at the outmost position. Approximately 9 g of a mixture comprising LATP particles, monomer, photo initiator and ethyl acetate (mass ratios = 1 : 0.5 : 0.02 : 100) was applied to the water surface drop by drop using a syringe with a stainless steel needle within a period of approximately one minute. Immediately after application of this mixture the movable barrier was moved inwards at a speed of 0.2 to 0.5 m min-1 until the area between the movable and the stationary barriers was approximately 14.9 cm x 8.5 cm. The endpoint of lateral compression was determined by visual inspection, using the same criteria as detailed above.
Illumination and transfer was conducted as detailed above.

Claims

Claims
1 . An alkali-ion conducting separator assembly comprising (A) a continuous matrix (A) of at least one polymer, and
(B) particles (B) of an alkali-ion conducting material, which are embedded in the continuous matrix (A), wherein at least 50 % of the embedded particles (B) penetrate both sides of the continuous matrix (A) and are uncovered by matrix (A).
2. The alkali-ion conducting separator assembly according to claim 1 , wherein the continuous matrix (A) is a non-ion conducting matrix.
3. The alkali-ion conducting separator assembly according to claim 1 or 2, wherein the polymer of the continuous matrix (A) is a cross-linked polymer.
4. The alkali-ion conducting separator assembly according to any of claims 1 to 3, wherein the continuous matrix (A) has an average thickness in the range from 0.01 to 100 μηη.
5. The alkali-ion conducting separator assembly according to any of claims 1 to 4, wherein the particles (B) form a monolayer.
6. The alkali-ion conducting separator assembly according to any of claims 1 to 5, wherein the alkali-ion conducting material is selected from the group consisting of ceramics, sintered ceramics, glass-ceramics and glasses.
7. The alkali-ion conducting separator assembly according to any of claims 1 to 6, wherein the average diameter of particles (B) is in the range from 0.1 to 10 μηη.
8. The alkali-ion conducting separator assembly according to any of claims 1 to 7, wherein the ratio of the average thickness of the continuous matrix (A) to the average diameter of particles (B) is in the range from 0.1 to 10.
9. The alkali-ion conducting separator assembly according to any of claims 1 to 8, wherein the ratio of the total volume of the particles (B) to the total volume of the continuous matrix (A) is in the range from 95 / 5 to 20 / 80.
10. The alkali-ion conducting separator assembly according to any of claims 1 to 9, wherein the alkali-ion conducting separator assembly is impermeable to organic solvents.
1 1 . A process for producing an alkali-ion conducting separator assembly according to any of claims 1 to 10, comprising the process steps of
(a) depositing particles (B) of an alkali-ion conducting material and a liquid phase (A2) comprising at least one polymer or at least one polymerizable compound on a smooth surface of a solid or liquid phase (C),
(b) solidifying liquid phase (A2) by evaporating volatile components, crystallization, vitrification or polymerization, and
(c) separating the continuous matrix (A) with the embedded particles (B) from the surface of phase (C).
12. An electrochemical cell comprising
(a) at least one anode (a),
(b) at least one cathode (b), (c) at least one electrolyte composition (c) comprising
(c1 ) at least one aprotic organic solvent (c1 ), and (c2) at least one alkali metal salt (c2), and
(d) at least one alkali-ion conducting separator assembly according to any of claims 1 to 10.
13. Alkali metal ion battery comprising at least one electrochemical cell according to claim 12.
14. A device comprising at least one electrochemical cell according to claim 12.
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20180040904A1 (en) * 2016-08-02 2018-02-08 Samsung Electronics Co., Ltd. Composite membrane, method of preparing the composite membrane, and lithium air battery including the composite membrane
WO2018054709A1 (en) 2016-09-20 2018-03-29 Basf Se Solid lithium electrolytes and process of production
EP3422459A1 (en) 2017-06-26 2019-01-02 Basf Se Rechargeable electrochemical cells protected against thermal runaway

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004036669A2 (en) * 2002-10-15 2004-04-29 Polyplus Battery Company Ionically conductive composites for protection of active metal anodes
JP2007018861A (en) * 2005-07-07 2007-01-25 Nissan Motor Co Ltd Separator for battery and battery using this
DE102007049203A1 (en) * 2007-10-08 2009-04-09 Werner A. Goedel Membrane, useful e.g. to separate oxygen and nitrogen, and separate or enrich carbon dioxide, comprises particles embedded in a continuous matrix
US20090136830A1 (en) * 2007-11-27 2009-05-28 John Howard Gordon Substantially Solid, Flexible Electrolyte For Alkili-Metal-Ion Batteries
WO2014035753A1 (en) * 2012-08-29 2014-03-06 Corning Incorporated Ion-conducting composite electrolyte

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004036669A2 (en) * 2002-10-15 2004-04-29 Polyplus Battery Company Ionically conductive composites for protection of active metal anodes
JP2007018861A (en) * 2005-07-07 2007-01-25 Nissan Motor Co Ltd Separator for battery and battery using this
DE102007049203A1 (en) * 2007-10-08 2009-04-09 Werner A. Goedel Membrane, useful e.g. to separate oxygen and nitrogen, and separate or enrich carbon dioxide, comprises particles embedded in a continuous matrix
US20090136830A1 (en) * 2007-11-27 2009-05-28 John Howard Gordon Substantially Solid, Flexible Electrolyte For Alkili-Metal-Ion Batteries
WO2014035753A1 (en) * 2012-08-29 2014-03-06 Corning Incorporated Ion-conducting composite electrolyte

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
CHUNSHENG WANG ET AL: "Solvent-Free Composite PEO-Ceramic Fiber/Mat Electrolytes for Lithium Secondary Cells", JOURNAL OF THE ELECTROCHEMICAL SOCIETY, vol. 152, no. 1, 1 January 2005 (2005-01-01), pages A205 - A209, XP055170713, ISSN: 0013-4651, DOI: 10.1149/1.1828952 *

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US20180040904A1 (en) * 2016-08-02 2018-02-08 Samsung Electronics Co., Ltd. Composite membrane, method of preparing the composite membrane, and lithium air battery including the composite membrane
US10727502B2 (en) * 2016-08-02 2020-07-28 Samsung Electronics Co., Ltd. Composite membrane including ion-conductive polymer layer and gas blocking inorganic particles, method of preparing the same, and lithium air battery including the same
US11600828B2 (en) 2016-08-02 2023-03-07 Samsung Electronics Co., Ltd. Composite membrane including ion-conductive polymer layer and gas blocking inorganic particles, method of preparing the composite membrane, and lithium air battery including the composite membrane
WO2018054709A1 (en) 2016-09-20 2018-03-29 Basf Se Solid lithium electrolytes and process of production
EP3422459A1 (en) 2017-06-26 2019-01-02 Basf Se Rechargeable electrochemical cells protected against thermal runaway

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