WO2000028611A1 - Materials for use in proton-conducting polymer electrolytes - Google Patents

Materials for use in proton-conducting polymer electrolytes Download PDF

Info

Publication number
WO2000028611A1
WO2000028611A1 PCT/CA1999/001022 CA9901022W WO0028611A1 WO 2000028611 A1 WO2000028611 A1 WO 2000028611A1 CA 9901022 W CA9901022 W CA 9901022W WO 0028611 A1 WO0028611 A1 WO 0028611A1
Authority
WO
WIPO (PCT)
Prior art keywords
compound
acid
polymer
organic compound
acetonitrile
Prior art date
Application number
PCT/CA1999/001022
Other languages
French (fr)
Inventor
Fernand Brochu
Michel Duval
Original Assignee
Hydro-Quebec
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hydro-Quebec filed Critical Hydro-Quebec
Publication of WO2000028611A1 publication Critical patent/WO2000028611A1/en

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
    • C07F9/00—Compounds containing elements of Groups 5 or 15 of the Periodic Table
    • C07F9/02—Phosphorus compounds
    • C07F9/06—Phosphorus compounds without P—C bonds
    • C07F9/08—Esters of oxyacids of phosphorus
    • C07F9/09—Esters of phosphoric acids
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/102—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer
    • H01M8/1023—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer having only carbon, e.g. polyarylenes, polystyrenes or polybutadiene-styrenes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/102—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer
    • H01M8/1025—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer having only carbon and oxygen, e.g. polyethers, sulfonated polyetheretherketones [S-PEEK], sulfonated polysaccharides, sulfonated celluloses or sulfonated polyesters
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/102—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer
    • H01M8/1027—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer having carbon, oxygen and other atoms, e.g. sulfonated polyethersulfones [S-PES]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/102—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer
    • H01M8/103—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer having nitrogen, e.g. sulfonated polybenzimidazoles [S-PBI], polybenzimidazoles with phosphoric acid, sulfonated polyamides [S-PA] or sulfonated polyphosphazenes [S-PPh]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/102—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer
    • H01M8/1032—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer having sulfur, e.g. sulfonated-polyethersulfones [S-PES]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/1039—Polymeric electrolyte materials halogenated, e.g. sulfonated polyvinylidene fluorides
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/1041—Polymer electrolyte composites, mixtures or blends
    • H01M8/1046—Mixtures of at least one polymer and at least one additive
    • H01M8/1048—Ion-conducting additives, e.g. ion-conducting particles, heteropolyacids, metal phosphate or polybenzimidazole with phosphoric acid
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/15—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on an electrochromic effect
    • G02F1/1514—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on an electrochromic effect characterised by the electrochromic material, e.g. by the electrodeposited material
    • G02F1/1523—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on an electrochromic effect characterised by the electrochromic material, e.g. by the electrodeposited material comprising inorganic material
    • G02F1/1525—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on an electrochromic effect characterised by the electrochromic material, e.g. by the electrodeposited material comprising inorganic material characterised by a particular ion transporting layer, e.g. electrolyte
    • 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
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Definitions

  • the present invention relates to proton conductors for use in electrochromic devices, rechargeable batteries and fuel cells. More specifically, the invention is concerned with organoacid materials, preferably organophosphoric derivatives, obtained from the reaction of a strong acid with an organic reagent.
  • Membranes made of proton-conducting polymer electrolyte are increasingly used in electrochromic devices, batteries and fuel cells.
  • the protons in such membranes are provided either by the addition of free acids such as sulphuric acid or orthophosphoric acid to a polymer, or by using polymers on which a sulphonic or phosphonic group has been grafted to the polymer backbone or side chain.
  • Perfluorosulphonic acid polymers of the Nafion ® type are good examples.
  • a well known macromolecular material is a complex of orthophosphoric acid - polyoxyethylene. The complex is conventionally prepared by dissolving both components in a compatible and inert solvent, such as acetonitrile, methanol, tetrahydrofuran, ethanol or mixtures thereof.
  • a major problem associated with the use of free acids in electrochromic devices is the chemical stability of the polymer in such a strongly acidic environment. Corrosion and polymer degradation is frequently observed. In the field of glazings for buildings and cars, a yellowing phenomenon is observed overtime, probably caused by the formation of free radicals resulting from the degradation of the polymer. This drawback could be overcome by the addition of antioxidants, but because of compatibility problems with the acidic medium and the solvents used for the preparation of the macromolecular material, few antioxidant solutions have been found.
  • US 5,507,965 describes a protonic, conductive, macromolecular material comprising a solid complex of anhydrous orthophosphoric acid and polyoxyethylene.
  • the patent proposes the use of a triphenylphosphine as an antioxidant.
  • the macromolecular material is obtained by dissolving anhydrous orthophosphoric acid in tetrahydrofuran, and adding this solution to polyoxyethylene, followed by the addition of acetonitrile to solubilize the polymer and form the complex.
  • Triphenylphosphine is added in tetrahydrofuran since it is soluble therein.
  • the resulting orthophosphoric acid - polyoxyethylene macromolecular complex is said to be useful as an electrolyte in electrochromic systems.
  • US 5,518,838 is directed to electrochemical cells such as batteries and capacitors, comprising a solid polymer electrolyte, which gives energy storage devices with very high power density.
  • the solid polymer electrolyte includes polyoxyethylene, polyvinylalcohol, polyvinyl acetate, polyacrylamide etc. combined with sulphuric acid or phosphoric acid as a polymer binder.
  • US 4,844,591 concerns an electrochromic device comprising a polyvinyl acetate - orthophosphoric acid complex or a polyoxyethylene (POE) - orthophosphoric acid complex.
  • the POE-orthophosphoric acid complex is said to be prepared under rigorous anhydrous conditions.
  • an organoacid material obtained from the reaction of a strong acid with an organic compound, for use as a proton conductor in a polymer electrolyte.
  • the organic compound replaces one or more hydrogen atoms on the acid, thus leading to an adduct that prevents the degradation of the polymer electrolyte.
  • Preferred organic compounds include acetonitrile, acrylonitrile, a low molecular weight ether, a low molecular weight alcohol, or mixtures thereof.
  • Preferred strong acids include orthophosphoric acid and sulphuric acid.
  • Polymer electrolytes comprising the novel organoacid material are also part of the present invention.
  • the present invention is directed to an organoacid material suitable for use as a proton conductor in polymer electrolytes.
  • polymer electrolytes are conventionally used in electrochromic devices, rechargeable batteries, fuel cells, etc.
  • the present organoacid material has the beneficial effect of preventing the degradation of the polymers while still providing excellent ionic conductivity, thus representing an alternative to orthophosphoric acid currently used for proton conduction in polymer electrolytes utilized in the above fields and in those requiring electrical energy production.
  • Examples are microelectronics, generators or cells such as those for pacemakers, or for energy storage purposes.
  • the present organoacid material is obtained by reacting a strong acid with an organic compound, in order to replace at least one of the hydrogen atoms of the acid with an organic substituent.
  • organic compounds include acetonitrile, acrylonitrile, C,-C 4 alcohol, low molecular weight ether and the like. Most preferred compounds are acetonitrile, diethyl ether and methanol. It has been found that tetrahydrofuran does not represent a suitable organic compound because it leads to side reactions such as colour and peroxide formation, which are likely to degrade the polymer electrolyte.
  • alcohols and ethers of higher molecular weights i.e., containing 5 or more carbon atoms, tend to form coloured phosphates, which means that the compound is less stable, and will therefore cause undesirable polymer electrolyte degradation.
  • These compounds are therefore less suitable, particularly in the field of electrochromic devices because of the change of color.
  • Example of strong acids suitable for the purposes of the present invention include orthophosphoric acid; sulphuric acid, perchloric acid and mixtures thereof.
  • the strong acid is reacted with the organic compound during one to several days under reflux, or slightly below the boiling point of the organic compound in a closed vessel.
  • This has the effect of replacing at least one hydrogen atom, or more than one is that is the case, of the acid by an organic group from the organic compound.
  • Control of the number of hydrogen atoms replaced on the acid can be controlled by taking samples periodically and analyzing them by measuring the increase in mass of the formed adduct and by conventional spectroscopic methods such as Fourier transformed infrared (FTIR) or NMR spectroscopy.
  • FTIR Fourier transformed infrared
  • NMR spectroscopy The families of polymers used for the preparation of the electrolyte membranes are those currently used with orthophosphoric acid in the preparation of electrochromic devices, proton-conducting rechargeable batteries and fuel cells.
  • polyethers include, without being limited to, polyethers, polyamides, polyacrylates, polyvinylalcohols, polyvinylacetates, polyvinylpyridines, polyacrylamide, polyimides, polybenzimidazoles, polyvinylpyrolidone, polyaromatic pyrazoles, perfluoronated sulphonic acid polymers, polyarylenesulfone, and the sulphonic acid derivatives of trifluorostyrene, styrene/ethylene butylene copolymers, fluorinated ethylene propylene polymer (FEP), polyvinylidene fluoride (PNDF), and mixtures thereof.
  • FEP fluorinated ethylene propylene polymer
  • PNDF polyvinylidene fluoride
  • orthophosphoric acid is mixed with the organic compound in a closed vessel, and heated to a few degrees below the boiling point of the organic compound.
  • the mixture can be heated under refluxing conditions at boiling point. In either process, heating is maintained for at least one, and generally, several hours or days, depending on the extent of reaction desired.
  • the solid organophosphoric adduct is isolated by evaporating any unreacted organic compound, and drying under vacuum.
  • the extent of the reaction of the organic compound with the orthophosphoric acid can be estimated 1) by looking at the increase in mass of the formed adduct and comparing with the starting amount of orthophosphoric acid; and 2) by looking at the increase in viscosity of the solution.
  • This increase in viscosity has no effect on the optical, mechanical and electrochemical properties of the electrolyte films. It may be useful for the coating process, by allowing to reduce the organic compound content of the electrolyte solution and to increase the thickness of the electrolyte films. If viscosity is too high, however, the organic compound content may have to be increased again in order to get a solution possible to handle for coating.
  • the duration of the reaction may therefore be chosen so as to optimise the coating parameters, as a function of the polymer type, coating method used and electrolyte thickness desired.
  • the thickness of the electrolyte can be from about 10 to about 300 ⁇ m.
  • the increase in mass of the adduct corresponds to the addition of one acetonitrile molecule to one hydrogen of the acid, with the elimination of one molecule of water.
  • the FTLR spectrum of the adduct shows the decrease of the P-OH groups at between 800 cm “1 and 1000 cm “1 , and the appearance of new absorption bands at 1500 cm “1 and 1700 cm “1 , corresponding to N-O or N-P chemical bonds. As the reaction is allowed to proceed further during several hours or days, no more increase in mass of the formed adduct is observed, meaning that no additional hydrogen on the acid is replaced.
  • the preferred duration of reaction is between 1 and 12 hours.
  • the viscosity is much too high after 72 hours.
  • organophosphoric materials wherein one hydrogen only has been replaced have been found preferred in terms of ionic conductivity in the electrolyte and chemical resistance of the polymer towards degradation.
  • the amount of organoacid material to be added to the polymer binder will vary depending on the end properties desired for the electrolyte. If the ratio of polymer binder to organoacid material is increased, the electrolyte films will be less electrochemically conducting, but also less amorphous, and therefore, more mechanically resistant, and vice-versa if the ratio is decreased.
  • the molar ratio of polymer to organoacid material in the electrolyte may vary from 0.2 to 10. A preferred range of from about 0.5 to about 1 has been found to provide optimal conductivity and mechanical properties.
  • fumed or pyrogenic silica products such as Aerosil ® , are added in
  • Fumed or pyrogenic silica products are generally ultrafme powders, i.e., of very low particle size, and are commonly used in the coating industry for this purpose. They have no effect on the final optical, mechanical and electrochemical properties of the electrolyte films.
  • the electrolyte film loses its mechanical properties, indicating a total degradation of the polymer into a wax-like material.
  • a film of polymer electrolyte ( ⁇ 300 ⁇ m after drying) is prepared by coating the solution of a FEP substrate in a conventional manner.
  • the electrolyte film is perfectly clear, and can be peeled off from the substrate even after weeks of storage. It retains its mechanical strength after being left for extended periods of time in ambient moist air, or
  • a length of electrolyte film is placed between plates of electrochromic glass that have been coated with thin transparent electrodes of WO 3 in a conventional manner. Electrochromic switching occurs for voltage differentials of around 2.5 V as expected.
  • Example 5 The electrolyte film prepared in previous Example 2 is placed between an anode consisting of a foil of an antimony-bismuth alloy, and a cathode consisting of a foil of nickel-molybdenum-chromium alloy, in order to obtain a rechargeable, proton- conducting, polymer electrolyte battery.
  • the open cell voltage was about 0.4V.
  • the organoacid material of the present invention provides an ionic conductivity comparable to that given by orthophosphoric acid, but has a much lower reactivity towards the polymer used in the electrolyte, thus preventing the degradation of the polymer overtime.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Manufacturing & Machinery (AREA)
  • General Chemical & Material Sciences (AREA)
  • Electrochemistry (AREA)
  • Sustainable Energy (AREA)
  • Sustainable Development (AREA)
  • Engineering & Computer Science (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Organic Chemistry (AREA)
  • Biochemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Molecular Biology (AREA)
  • General Health & Medical Sciences (AREA)
  • Composite Materials (AREA)
  • Conductive Materials (AREA)
  • Secondary Cells (AREA)
  • Primary Cells (AREA)

Abstract

Proton conductors for use in electrochromic devices, rechargeable batteries and fuel cells. More specifically, organophosphoric materials obtained from the reaction of orthophosphoric acid with various organic reagents, including acetonitrile, acrylonitrile, a low molecular weight ether, a low molecular weight alcohol, or mixtures thereof. The novel organophosphoric materials have the beneficial effect of preventing the degradation of the polymers while still providing excellent ionic conductivity.

Description

TITLE
Materials for use in proton-conducting polymer electrolytes
FIELD OF THE INVENTION The present invention relates to proton conductors for use in electrochromic devices, rechargeable batteries and fuel cells. More specifically, the invention is concerned with organoacid materials, preferably organophosphoric derivatives, obtained from the reaction of a strong acid with an organic reagent.
BACKGROUND OF THE INVENTION
Membranes made of proton-conducting polymer electrolyte are increasingly used in electrochromic devices, batteries and fuel cells. The protons in such membranes are provided either by the addition of free acids such as sulphuric acid or orthophosphoric acid to a polymer, or by using polymers on which a sulphonic or phosphonic group has been grafted to the polymer backbone or side chain. Perfluorosulphonic acid polymers of the Nafion® type are good examples. A well known macromolecular material is a complex of orthophosphoric acid - polyoxyethylene. The complex is conventionally prepared by dissolving both components in a compatible and inert solvent, such as acetonitrile, methanol, tetrahydrofuran, ethanol or mixtures thereof.
A major problem associated with the use of free acids in electrochromic devices is the chemical stability of the polymer in such a strongly acidic environment. Corrosion and polymer degradation is frequently observed. In the field of glazings for buildings and cars, a yellowing phenomenon is observed overtime, probably caused by the formation of free radicals resulting from the degradation of the polymer. This drawback could be overcome by the addition of antioxidants, but because of compatibility problems with the acidic medium and the solvents used for the preparation of the macromolecular material, few antioxidant solutions have been found.
Another problem associated with electrochromic devices is the presence of haze, which is equal to the diffused light proportion compared with the incident light. When exceeding 1%, the eye starts to perceive deformation of images.
US 5,507,965 describes a protonic, conductive, macromolecular material comprising a solid complex of anhydrous orthophosphoric acid and polyoxyethylene. The patent proposes the use of a triphenylphosphine as an antioxidant. The macromolecular material is obtained by dissolving anhydrous orthophosphoric acid in tetrahydrofuran, and adding this solution to polyoxyethylene, followed by the addition of acetonitrile to solubilize the polymer and form the complex. Triphenylphosphine is added in tetrahydrofuran since it is soluble therein. The resulting orthophosphoric acid - polyoxyethylene macromolecular complex is said to be useful as an electrolyte in electrochromic systems.
US 5,518,838 is directed to electrochemical cells such as batteries and capacitors, comprising a solid polymer electrolyte, which gives energy storage devices with very high power density. The solid polymer electrolyte includes polyoxyethylene, polyvinylalcohol, polyvinyl acetate, polyacrylamide etc. combined with sulphuric acid or phosphoric acid as a polymer binder.
US 4,844,591 concerns an electrochromic device comprising a polyvinyl acetate - orthophosphoric acid complex or a polyoxyethylene (POE) - orthophosphoric acid complex. The POE-orthophosphoric acid complex is said to be prepared under rigorous anhydrous conditions.
SUMMARY OF THE INVENTION In accordance with the present invention, there is now provided an organoacid material obtained from the reaction of a strong acid with an organic compound, for use as a proton conductor in a polymer electrolyte. The organic compound replaces one or more hydrogen atoms on the acid, thus leading to an adduct that prevents the degradation of the polymer electrolyte. Preferred organic compounds include acetonitrile, acrylonitrile, a low molecular weight ether, a low molecular weight alcohol, or mixtures thereof. Preferred strong acids include orthophosphoric acid and sulphuric acid. Polymer electrolytes comprising the novel organoacid material are also part of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is directed to an organoacid material suitable for use as a proton conductor in polymer electrolytes. Such polymer electrolytes are conventionally used in electrochromic devices, rechargeable batteries, fuel cells, etc. It has unexpectedly been found that the present organoacid material has the beneficial effect of preventing the degradation of the polymers while still providing excellent ionic conductivity, thus representing an alternative to orthophosphoric acid currently used for proton conduction in polymer electrolytes utilized in the above fields and in those requiring electrical energy production. Examples are microelectronics, generators or cells such as those for pacemakers, or for energy storage purposes. The present organoacid material is obtained by reacting a strong acid with an organic compound, in order to replace at least one of the hydrogen atoms of the acid with an organic substituent. Examples of suitable organic compounds include acetonitrile, acrylonitrile, C,-C4 alcohol, low molecular weight ether and the like. Most preferred compounds are acetonitrile, diethyl ether and methanol. It has been found that tetrahydrofuran does not represent a suitable organic compound because it leads to side reactions such as colour and peroxide formation, which are likely to degrade the polymer electrolyte. Further, alcohols and ethers of higher molecular weights, i.e., containing 5 or more carbon atoms, tend to form coloured phosphates, which means that the compound is less stable, and will therefore cause undesirable polymer electrolyte degradation. These compounds are therefore less suitable, particularly in the field of electrochromic devices because of the change of color.
Example of strong acids suitable for the purposes of the present invention include orthophosphoric acid; sulphuric acid, perchloric acid and mixtures thereof.
Typically, the strong acid is reacted with the organic compound during one to several days under reflux, or slightly below the boiling point of the organic compound in a closed vessel. This has the effect of replacing at least one hydrogen atom, or more than one is that is the case, of the acid by an organic group from the organic compound. Control of the number of hydrogen atoms replaced on the acid can be controlled by taking samples periodically and analyzing them by measuring the increase in mass of the formed adduct and by conventional spectroscopic methods such as Fourier transformed infrared (FTIR) or NMR spectroscopy. The families of polymers used for the preparation of the electrolyte membranes are those currently used with orthophosphoric acid in the preparation of electrochromic devices, proton-conducting rechargeable batteries and fuel cells. They include, without being limited to, polyethers, polyamides, polyacrylates, polyvinylalcohols, polyvinylacetates, polyvinylpyridines, polyacrylamide, polyimides, polybenzimidazoles, polyvinylpyrolidone, polyaromatic pyrazoles, perfluoronated sulphonic acid polymers, polyarylenesulfone, and the sulphonic acid derivatives of trifluorostyrene, styrene/ethylene butylene copolymers, fluorinated ethylene propylene polymer (FEP), polyvinylidene fluoride (PNDF), and mixtures thereof.
According to a most preferred embodiment of the present invention, orthophosphoric acid is mixed with the organic compound in a closed vessel, and heated to a few degrees below the boiling point of the organic compound. Alternately, the mixture can be heated under refluxing conditions at boiling point. In either process, heating is maintained for at least one, and generally, several hours or days, depending on the extent of reaction desired. The solid organophosphoric adduct is isolated by evaporating any unreacted organic compound, and drying under vacuum. The extent of the reaction of the organic compound with the orthophosphoric acid can be estimated 1) by looking at the increase in mass of the formed adduct and comparing with the starting amount of orthophosphoric acid; and 2) by looking at the increase in viscosity of the solution. This increase in viscosity has no effect on the optical, mechanical and electrochemical properties of the electrolyte films. It may be useful for the coating process, by allowing to reduce the organic compound content of the electrolyte solution and to increase the thickness of the electrolyte films. If viscosity is too high, however, the organic compound content may have to be increased again in order to get a solution possible to handle for coating. The duration of the reaction may therefore be chosen so as to optimise the coating parameters, as a function of the polymer type, coating method used and electrolyte thickness desired. Typically, the thickness of the electrolyte can be from about 10 to about 300 μm.
As an example, when orthophosphoric acid is reacted with acetonitrile at 70°C
during 1 hour or more, the increase in mass of the adduct corresponds to the addition of one acetonitrile molecule to one hydrogen of the acid, with the elimination of one molecule of water. The FTLR spectrum of the adduct shows the decrease of the P-OH groups at between 800 cm"1 and 1000 cm"1, and the appearance of new absorption bands at 1500 cm"1 and 1700 cm"1, corresponding to N-O or N-P chemical bonds. As the reaction is allowed to proceed further during several hours or days, no more increase in mass of the formed adduct is observed, meaning that no additional hydrogen on the acid is replaced. However, a sharp increase in viscosity of the solution is observed, indicating that some type of self-polymerisation of the formed adduct is occurring. In this example, for coating purposes, the preferred duration of reaction is between 1 and 12 hours. The viscosity is much too high after 72 hours.
By using other types of organic compounds and/or higher temperatures, it is possible that other hydrogen atoms may be replaced. However, organophosphoric materials wherein one hydrogen only has been replaced have been found preferred in terms of ionic conductivity in the electrolyte and chemical resistance of the polymer towards degradation.
It should also be noted that slight coloration of the product might be observed depending on the strong acid - organic compound combination employed. For electrochromic applications, the most suitable organoacids are obviously those producing no coloration.
With respect to the determination of the preferred molecular weight for the polymer material, anyone of ordinary skill in the art is well aware that higher molecular weight polymers are generally more structurally sound, while lower molecular weight polymers are less rigid, thus more flexible. Typically, a molecular weight varying from 100000 to 5 000 000 is preferred. Higher molecular weight polymers have the advantage of containing less hydroxyl groups, which cause degradation of the polymer.
Further, the amount of organoacid material to be added to the polymer binder will vary depending on the end properties desired for the electrolyte. If the ratio of polymer binder to organoacid material is increased, the electrolyte films will be less electrochemically conducting, but also less amorphous, and therefore, more mechanically resistant, and vice-versa if the ratio is decreased.
The molar ratio of polymer to organoacid material in the electrolyte may vary from 0.2 to 10. A preferred range of from about 0.5 to about 1 has been found to provide optimal conductivity and mechanical properties.
Typically, fumed or pyrogenic silica products such as Aerosil®, are added in
the electrolyte solutions to get dried electrolyte films more uniform, with less internal mechanical tensions and thus easier to manipulate. Fumed or pyrogenic silica products are generally ultrafme powders, i.e., of very low particle size, and are commonly used in the coating industry for this purpose. They have no effect on the final optical, mechanical and electrochemical properties of the electrolyte films.
The following examples are provided to illustrate the present invention, and shall not be construed as limiting its scope.
Example 1
50 g of anhydrous orthophosphoric acid and 5 g of Aerosil® are placed in 170 mL of stabilized tetrahydrofuran at room temperature, until the acid is dissolved. Subsequently, 170 mL of acetonitrile and 48 g of polyoxyethylene of molecular weight 900 000 are added in medium. This solution is coated on a substrate of FEP film (~ 100 μm) using a doctor blade, in order to prepare a film of polymer electrolyte (~ 300 μm after drying). The polymer electrolyte film is hazy. After a few hours of storage, the film adheres strongly to the FEP film, and cannot be peeled off, indicating a partial degradation of the polymer into lower molecular weight compounds. After being left in
ambient moist air, or after being treated one day at 90°C under nitrogen for complete
drying, the electrolyte film loses its mechanical properties, indicating a total degradation of the polymer into a wax-like material.
Example 2
50 g of anhydrous orthophosphoric acid and 120 mL of acetonitrile are heated
in a closed bottle for 24 hours at 70°C. The remaining unreacted acetonitrile is
evaporated and the organophosphoric adduct dried under a vacuum. 32 g of the dried adduct is placed in 35 mL of tetrahydrofuran, then 29 g of POE and 3 g of Aerosil® are added. A film of polymer electrolyte (~ 300 μm after drying) is prepared by coating the solution of a FEP substrate in a conventional manner. The electrolyte film is perfectly clear, and can be peeled off from the substrate even after weeks of storage. It retains its mechanical strength after being left for extended periods of time in ambient moist air, or
after being treated one day at 90°C under nitrogen, indicating that no significant polymer
degradation has occurred.
Example 3
50 g of anhydrous orthophosphoric acid and 120 mL of stabilized
tetrahydrofuran are heated at 70°C for 24 hours in a closed bottle. The solution darkens
rapidly. The electrolyte films prepared as in Example 2 develop a dark yellow colour and lose rapidly their mechanical strength.
Example 4
The electrolyte film prepared in previous Example 2 is characterized for
electrochromic applications. Its ionic conductivity is 10 s Ω"1 cm"1, the percentage of light
transmission (TL%) is 80%, and the percentage of haze is 0. Such results are excellent for this particular application for the product.
A length of electrolyte film is placed between plates of electrochromic glass that have been coated with thin transparent electrodes of WO3 in a conventional manner. Electrochromic switching occurs for voltage differentials of around 2.5 V as expected.
After 48 hours of aging at 100°C, the percentage of haze is still very low.
Example 5 The electrolyte film prepared in previous Example 2 is placed between an anode consisting of a foil of an antimony-bismuth alloy, and a cathode consisting of a foil of nickel-molybdenum-chromium alloy, in order to obtain a rechargeable, proton- conducting, polymer electrolyte battery. The open cell voltage was about 0.4V.
As seen in the above examples, the organoacid material of the present invention provides an ionic conductivity comparable to that given by orthophosphoric acid, but has a much lower reactivity towards the polymer used in the electrolyte, thus preventing the degradation of the polymer overtime.
While the invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modifications and this application is intended to cover any variations, uses or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains, and as may be applied to the essential features hereinbefore set forth, and as follows in the scope of the appended claims.

Claims

HAT IS CLAIMED IS:
1. An organoacid compound for use as a proton conductor in a polymer electrolyte, wherein the organoacid compound comprises a strong acid derivative comprising at least one hydrogen atom replaced with an organic group, to prevent the degradation of the polymer electrolyte.
2. An organoacid according to claim 1 wherein the acid comprises orthophosphoric acid; sulphuric acid; perchloric acid, and mixtures thereof.
3. A compound according to claim 1 wherein the organic compound comprises acetonitrile, acrylonitrile, a low molecular weight ether, a low molecular weight alcohol, and mixtures thereof.
4. A compound according to claim 2 wherein the organic compound is acetonitrile.
5. A polymer electrolyte comprising a compound according to claim 1 in admixture with a at least one polymer comprising a polyether; a polyamide; a polyacrylate; a polyvinylalcohol; a polyvinylacetate; a polyvinylpyridine; a polyacrylamide; a polyimide; a polybenzimidazole; a polyvinylpyrolidone; a polyaromatic pyrazole; a perfluoronated sulphonic acid polymer; a polyarylenesulfone; a sulphonic acid derivatives of trifluorostyrene, styrene/ethylene/butylene copolymers, fluorinated ethylene propylene polymer, or polyvinylidene fluoride.
6. A polymer electrolyte according to claim 5 wherein the organic compound is acetonitrile.
7. An electrolyte according to claim 5 wherein the molar ratio of polymer to organoacid compound is from substantially 0.2 to substantially 10.
8. An electrochromic device comprising a compound according to claim 1 as the proton conductor.
9. An electrochemical cell comprising a compound according to claim 1 as the proton conductor.
10. A cell according to claim 9 wherein the cell is a rechargeable battery.
11. An organophosphoric compound for use as a proton conductor in a polymer electrolyte, wherein the organophosphoric compound comprises an orthophosphoric acid derivative comprising at least one of the 3 hydrogen atoms of the acid replaced with an organic group, to prevent the degradation of the polymer electrolyte.
12. A compound according to claim 11 wherein the organic compound comprises acetonitrile, acrylonitrile, a low molecular weight ether, a low molecular weight alcohol, and mixtures thereof.
13. A compound according to claim 12 wherein the organic compound is acetonitrile.
14. A polymer electrolyte comprising a compound according to claim 11 in admixture with a at least one polymer comprising a polyether; a polyamide; a polyacrylate; a polyvinylalcohol; a polyvinylacetate; a polyvinylpyridine; a polyacrylamide; a polyimide; a polybenzimidazole; a polyvinylpyrolidone; a
polyaromatic pyrazole; a perfluoronated sulphonic acid polymer; a polyarylenesulfone; a
sulphonic acid derivatives of trifluorostyrene, styrene/ethylene/butylene copolymers,
fluorinated ethylene propylene polymer, or polyvinylidene fluoride.
15. A polymer electrolyte according to claim 14 wherein the organic
compound is acetonitrile.
16. An electrochromic device comprising a compound according to claim 11 as the proton conductor.
17. An electrochemical cell comprising a compound according to claim 11 as
the proton conductor.
18. A cell according to claim 17 wherein the cell is a rechargeable battery.
19. A process for producing an organophosphoric compound according to
claim 1 , which comprises mixing a strong acid with an organic compound and heating the
resulting mixture to a temperature below the boiling point of the organic compound or alternately under reflux, for a period of time sufficient to cause at least one hydrogen of
the acid acid to be replaced by the organic compound; and subsequently evaporating any
remaining organic compound to collect the organoacid compound.
20. A process according to claim 19 wherein the acid is orthophosphoric acid and the organic compound is acetonitrile.
PCT/CA1999/001022 1998-11-05 1999-11-02 Materials for use in proton-conducting polymer electrolytes WO2000028611A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US18613898A 1998-11-05 1998-11-05
US09/186,138 1998-11-05

Publications (1)

Publication Number Publication Date
WO2000028611A1 true WO2000028611A1 (en) 2000-05-18

Family

ID=22683801

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CA1999/001022 WO2000028611A1 (en) 1998-11-05 1999-11-02 Materials for use in proton-conducting polymer electrolytes

Country Status (1)

Country Link
WO (1) WO2000028611A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003090304A1 (en) * 2002-04-16 2003-10-30 Gas Technology Institute Composite polymer electrolyte membrane for polymer electrolyte membrane fuel cells
RU2488866C2 (en) * 2012-03-11 2013-07-27 Зао "Нтк" Method for preparation of jellous polymer electrolyte for light modulators with film electrochromic layers

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4795536A (en) * 1985-07-10 1989-01-03 Allied-Signal Inc. Hydrogen separation and electricity generation using novel three-component membrane
US4844591A (en) * 1986-07-04 1989-07-04 Saint-Gobain Vitrage Variable transmission glazings and method of making same
JPH0377859A (en) * 1989-08-21 1991-04-03 Nissei Kagaku Kogyo Kk Production of 2-acylamido-2-methylpropanesulfonic acid
RU1828862C (en) * 1991-03-19 1993-07-23 Волгоградский Политехнический Институт Process for preparing phosphoric acid cyanoalkyl esters
EP0704922A1 (en) * 1994-03-19 1996-04-03 Hitachi Maxell Ltd. Organic-electrolyte secondary battery
US5723645A (en) * 1996-09-05 1998-03-03 Pacific Corporation Method for preparing 3-aminopropane phosphoric acid

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4795536A (en) * 1985-07-10 1989-01-03 Allied-Signal Inc. Hydrogen separation and electricity generation using novel three-component membrane
US4844591A (en) * 1986-07-04 1989-07-04 Saint-Gobain Vitrage Variable transmission glazings and method of making same
JPH0377859A (en) * 1989-08-21 1991-04-03 Nissei Kagaku Kogyo Kk Production of 2-acylamido-2-methylpropanesulfonic acid
RU1828862C (en) * 1991-03-19 1993-07-23 Волгоградский Политехнический Институт Process for preparing phosphoric acid cyanoalkyl esters
EP0704922A1 (en) * 1994-03-19 1996-04-03 Hitachi Maxell Ltd. Organic-electrolyte secondary battery
US5723645A (en) * 1996-09-05 1998-03-03 Pacific Corporation Method for preparing 3-aminopropane phosphoric acid

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
CHEMICAL ABSTRACTS, vol. 123, no. 23, 4 December 1995, Columbus, Ohio, US; abstract no. 314167, NO, BORIS I. ET AL: "Preparation of cyanoalkyl phosphate esters" XP002130604 *
J ET AL: "A H2O2 fuel cell using acid doped polybenzimidazole as polymer electrolyte", ELECTROCHIMICA ACTA,GB,ELSEVIER SCIENCE PUBLISHERS, BARKING, vol. 41, no. 2, 1 February 1996 (1996-02-01), pages 193 - 197, XP004019572, ISSN: 0013-4686 *
PATENT ABSTRACTS OF JAPAN vol. 015, no. 248 (C - 0843) 25 June 1991 (1991-06-25) *
ZVI RAPPOPORT: "The chemistry of the cyano group", 1970, INTERSCIENCE PUBLISHERS, LONDON-NEW-YORK-SYDNEY-TORONTO, XP002130716 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003090304A1 (en) * 2002-04-16 2003-10-30 Gas Technology Institute Composite polymer electrolyte membrane for polymer electrolyte membrane fuel cells
US6893763B2 (en) 2002-04-16 2005-05-17 Gas Technology Institute Composite polymer electrolyte membrane for polymer electrolyte membrane fuel cells
RU2488866C2 (en) * 2012-03-11 2013-07-27 Зао "Нтк" Method for preparation of jellous polymer electrolyte for light modulators with film electrochromic layers

Similar Documents

Publication Publication Date Title
Bannister et al. Ionic conductivities for poly (ethylene oxide) complexes with lithium salts of monobasic and dibasic acids and blends of poly (ethylene oxide) with lithium salts of anionic polymers
US5679482A (en) Fuel cell incorporating novel ion-conducting membrane
US5961672A (en) Stabilized anode for lithium-polymer batteries
US6214251B1 (en) Polymer electrolyte composition
EP1085590A1 (en) Composite polymer membrane, method for producing the same and solid polymer electrolyte membrane
EP1085051A1 (en) Sulfonic acid group-containing polyvinyl alcohol, solid polymer electrolyte, composite polymer membrane, method for producing the same and electrode
US11970590B2 (en) Polyphenylenes, methods, and uses thereof
US6878475B2 (en) Membrane for fuel cell, and fuel cell incorporating that membrane
KR101807693B1 (en) Gel polymer electrolyte and Lithium battery comprising gel polymer electrolyte and method for preparing gel polymer electrolyte
US20070231654A1 (en) Process of producing sulfonic group-containing substituted polyacetylene membrane, membrane obtained thereby and application thereof
JP3384173B2 (en) Polymer solid electrolyte
Grewal et al. Solvated Ionic‐Liquid Incorporated Soft Flexible Cross‐Linked Network Polymer Electrolytes for Safer Lithium Ion Secondary Batteries
WO2000028611A1 (en) Materials for use in proton-conducting polymer electrolytes
CN116613362A (en) Composite amphoteric ion exchange membrane for vanadium battery and preparation method thereof
CN113571768B (en) Modified aluminum-based polymer and preparation method thereof, high-pressure-resistant solid polymer electrolyte membrane and preparation method thereof, and lithium metal secondary battery
US20060260935A1 (en) Aqueous ionomeric gels and products and methods related thereto
CA2703710C (en) Ionically conductive polymer for use in electrochemical devices
CN113136047A (en) Lithiated perfluorinated polymers with mixed long and short side chains
KR100612897B1 (en) Proton conductive electrolyte, preparing method thereof, and fuel cell using the same
US20040062972A1 (en) Proton conductor, single-ion conductor, and processes for producing these
CN115498254B (en) Semi-interpenetrating network polymer electrolyte and preparation method and application thereof
RU2814465C1 (en) Polymer gel electrolyte for lithium-ion batteries
CN118263509A (en) High-concentration salt-coated polymer solid electrolyte, preparation method thereof and sodium battery containing high-concentration salt-coated polymer solid electrolyte
CN117543161A (en) High-flame-retardance diaphragm for lithium ion battery and preparation method of high-flame-retardance diaphragm
CN117525569A (en) Modified solid electrolyte, composite solid electrolyte film, solid battery and preparation method of solid battery

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): CA JP

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE

121 Ep: the epo has been informed by wipo that ep was designated in this application
DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
122 Ep: pct application non-entry in european phase