EP0346397A1 - Couche active chargee d'hydrogel dans des electrodes de diffusion de gaz supportant la pression - Google Patents

Couche active chargee d'hydrogel dans des electrodes de diffusion de gaz supportant la pression

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Publication number
EP0346397A1
EP0346397A1 EP88903502A EP88903502A EP0346397A1 EP 0346397 A1 EP0346397 A1 EP 0346397A1 EP 88903502 A EP88903502 A EP 88903502A EP 88903502 A EP88903502 A EP 88903502A EP 0346397 A1 EP0346397 A1 EP 0346397A1
Authority
EP
European Patent Office
Prior art keywords
gas
electrode
cell
electrolyte
precursor polymer
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP88903502A
Other languages
German (de)
English (en)
Inventor
Arnold Z. Gordon
Ernest B. Yeager
Donald S. Tryk
M. Sohrab Hossain
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
CBS Corp
Original Assignee
Gould Inc
Westinghouse Electric Corp
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 Gould Inc, Westinghouse Electric Corp filed Critical Gould Inc
Publication of EP0346397A1 publication Critical patent/EP0346397A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M12/00—Hybrid cells; Manufacture thereof
    • H01M12/04—Hybrid cells; Manufacture thereof composed of a half-cell of the fuel-cell type and of a half-cell of the primary-cell type
    • H01M12/06—Hybrid cells; Manufacture thereof composed of a half-cell of the fuel-cell type and of a half-cell of the primary-cell type with one metallic and one gaseous electrode
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/90—Selection of catalytic material
    • H01M4/9008—Organic or organo-metallic compounds
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/96—Carbon-based electrodes

Definitions

  • This invention relates generally to gas diffusion electrodes and, more particularly, this invention relates to gas diffusion electrodes adapted for use in electrochemical cells utilizing an aqueous alkaline electrolyte and consuming or generating a gas via the electrochemical process occurring within the gas diffusion electrode.
  • gas diffusion electrodes have also been used in the electrolysis, either oxidation or reduction, of gaseous reactants. It is also possible to generate gases in such electrodes.
  • gas diffusion electrodes take the form of solid porous (gas and liquid permeable) bodies formed at least in part of an electronically conductive, electrochemically active material, and may include a catalyst. Such electrodes generally define an electrolyte contacting surface and a gas contacting surface. Electrochemical oxidation and reduction occur at the points in the electrode where the gas to be oxidized or reduced contacts both the electrode and the active material of the electrode. In the case of gas generation, electrolyte contacts the active material and gas is generated at this interface.
  • Electrochemical cells utilizing such electrodes generally comprise the gas diffusion electrode, a spaced counter electrode, a liquid electrolyte (which is generally aqueous) which contacts both the counter electrode and the gas diffusion electrode, and a gas which contacts the gas diffusion electrode either (1) for reduction or oxidation of the gas or (2) produced via electrolytic generation. Circuit connections are disposed between the counter and gas diffusion electrodes. Additionally, the counter electrode may also be a gas diffusion electrode. A well known example of such a design is the H 2 / ⁇ 2 fuel cell. Electrochemical batteries r for example, the metal air type, commonly utilize either an aqueous alkaline or neutral (e.g., saline) electrolyte, while fuel cells may commonly utilize either acidic electrolytes or alkaline electrolytes. Other types of electrolytes are also use, depending upon the specific gas which is consumed or generated.
  • electrochemical batteries of an oxygen-containing gas ' such as air which is reduced at the gas diffusion electrode.
  • an oxygen-containing gas ' such as air which is reduced at the gas diffusion electrode.
  • hydrogen gas is oxidized in some fuel cells.
  • the present invention is generally applicable to all such types of gas diffusion electrodes and cells.
  • the electronically conductive material in a gas diffusion electrode typically may be carbon. Additionally, a wide variety of catalyst such as platinum or transition metal organometallic catalysts (such as porphyrins) are available.
  • liquid electrolyte and the gaseous electrode reactant be flowed through the body of the cell over the electrode surfaces.
  • Flowing electrolyte and/or flowed gaseous reactant are of course accompanied by a pressure drop across the cell, especially on the electrode side. This can be lead to excess pressures either on the gas-side or the electrode-side of the electrode.
  • One example of such a situation would be one in which the performance is increased by pressurizing the gaseous reactant.
  • One means of accomplishing this is to utilize a relatively high gas pressure or flow rate.
  • typical air cathodes exhibit a gas blow-through pressure of less than about 0.25 psi. If the differential pressures exceeds the blow-through pressure, pumping of gas into the liquid electrolyte may result.
  • typical blow-through pressures range from 0-1 psi, and are determined primarily by interfacial tension and pore size distribution
  • liquid electrolyte pressure is higher than the gas pressure and the differential pressure exceeds the liquid bleed-through pressure
  • liquid may be pumped into the gas side of the cell, which may result in liquid in the gas manifold with consequent pumping problems and a decrease in cell performance and useful cell life due to flooding of the active layer of the electrode.
  • gas-generating cells it is customary for the gas to be generated on the front face (electrolyte- side) of the electrode. The gas is thus generated as bubbles in the electrolyte, which can lead to removal of electrolyte from the cell and increased oh ic losses.
  • Generation of gas in a gas diffusion electrode is more desirable because the gas can exit the cell directly through the back of the electrode. Operation in this mode would require a certain amount of pressure tolerance. Even higher pressure tolerance would be required if the gas is generated in a pressurized state.
  • an ionomeric, ionically conductive, substantially gas impermeable material is disposed within the pore volume of a porous gas diffusion electrode adapted for use in a gas generating or consuming electrochemical cell utilizing a liquid electrolyte.
  • the material comprises •a hydrophilic ionic polymer form by by coprecipitation Of at least two precursor polymers.
  • the invention also comprehends an electrochemical cell comprising the gas diffusion electrode spaced from a counter electrode and in contact with a liquid electrolyte.
  • a gas to be oxidized, reduced or generated is in contact with the gas side of the electrode, and circuit connections are disposed between the counter and gas diffusion electrodes.
  • the electrode and cell of the invention are capable of operating at very high gas v. electrolyte differential pressures at high current densities without significant voltage loss.
  • Fig 1. is a transverse sectional view of one embodiment of an electrochemical cell in which the invention may be utilized;
  • Fig. 2 is a schematic sectional view of a typical gas diffusion electrode with which the invention may be utilized;
  • Fig. 3 is a sectional view of an electrode holder useful in testing gas diffusion electrodes
  • Fig. 4 is a schematic exploded perspective view of an electrode assembly adapted for use with the electrode holder of Fiq. 3;
  • Fig. 5 is a schematic transverse sectional view of an electrode as use in Figs. 3 and 4;
  • Fig» 6 is a series of polarization curves exhibited by an electrode made according to the invention.
  • Fig. 7 is a polarization curve exhibited by another embodiment of an electrode made according to the invention.
  • Fig. 1 illustrates a typical embodiment of an electrochemical battery utilizing a gas diffusion electrode.
  • This particular cell is an aqueous alkaline lithium-air cell.
  • the present invention is not limited to use in electrochemical batteries, not to cells in which gas is consumed. Rather, the invention finds wide applicability in cells in which gas is either consumed or produced, via either consumed or produced, via either reduction or oxidation, in which any of various electrolytes are used, etc.
  • the cell of Fig. 1 is described in detail in U.S. Patent No. 4,528,249 (July 9, 1985) the disclosure of which is incorporated by reference.
  • an electrochemical cell in Fig. 1, includes an anode 11, a gas consuming cathode 12, and a metal screen 13 interposed between the anode 11 and cathode 12 within an outer housing 14.
  • the screen 13 is in electrical contact with the cathode 12, and is in mechanical (but not electrical) contact with the anode 11.
  • the anode 11 comprises a lithium anode, which may comprose elemental lithium metal or lithium alloyed with alloying material such as small amounts of aluminum.
  • the screen 13 is not in electrical contact with the anode 11, due to the presence of an insulating, porous lithium hydroxide (LiOH) film which is formed on the anode surface by contact thereof with humid air, and is well known in the art. It is to be noted, however, that this particular feature is peculiar to the aqueous lithium-air cell. In other types of metal-air batteries and fuel cells, either an electrically insulating porous separator layer or a simple electrolyte gap would be used. It should also be noted that the screen 13 is necessary to help restrain the gas diffusion electrode 12 against the gas pressure.
  • LiOH lithium hydroxide
  • the cathode 12 is in this case an air cathode through which atmospheric air flows. Those skilled in the art, however, will recognize that such a cathode may operate with any oxygen-containing gas.
  • One surface 15 of the cathode 12 is exposed to ambient atmosphere (or a source of another oxygen- containing gas) in a chamber 16 of the housing 14, and the opposite surface 17 of the cathode 12 is contacted by the liquid electrolyte 18 which is flowed through a second chamber 19 in the housing 14 as by a suitable pump 20.
  • the electrode is provided from a reservoir 21 for suitable delivery when needed.
  • the anode 11 and cathode 12 each terminate in a respective terminal 26 or 28, and are connected to a load 30 through suitable circuit connections 32.
  • the cathode 12 comprises a structure formed of a suitable porous hydrophobic material, such as polytetrafluoroethylene (PTFE), mixed with carbon black, both pure and catalyst-containing.
  • PTFE polytetrafluoroethylene
  • a preferred form of the cathode 12 is described below in connection with Fig. 2.
  • the screen 13 illustratively may comprise a woven metal wire screen formed of suitable non-corroding metal, which in the case of alkaline electrolyte may be nickel or silver plated nickel. If desired, the screen 13 may serve as a current collector if connected to the teminal 28.
  • liquid electrolyte in this case an aqueous alkaline electrolyte such as aqueous lithium hydroxide, is flowed through the chamber 19 by means of the pump 20. As such, there is a pressure drop across the chamber 19 in the direction of flow.
  • Fig. 1 is intented to be exemplary only, as the invention is applicable to any of a variety of types of gas diffusion electrodes and electrochemical cells.
  • Fig. 2 is a schematic depiction of the structure of a preferred embodiment of the cathode 12. As shown in Fig. 2, the electrode 12 is formed essentially of a two or three component laminate defining the gas contacting surface 15 and the opposed electrolyte contacting surface 17.
  • An electronically conductive porous gas carrier layer 40 defines the gas contacting surface 15 and typically is a mixture of a hydrophobic material such as porous PTFE (e.g. Teflon brand PTFE) with a carbon black such as Shawinigan black (Cheveron Chemical Co..
  • a so-called “active layer” 42 comprises a layer 44 which comprises a mixture of carbon black, or catalyst supported on carbon black and PTFE.
  • An optional layer 46 of catalyst is disposed on the layer 44 at an interface 50.
  • layers 44 and 45 appear to be discrete layers, but in practice may define a single layer or two layers, since the catlayst is generally adsorbed onto the surface of the material of layer 44. In some cases, the material of the three layers 40, 44 and 46 may be intermixed in a single layer.
  • the entire structure of the electrode 12 of Fig. 2 is porous, generally exhibiting a porosity of 30- 60%.
  • a typical catalyst forming the layer 44 is heat-treated cobalt tetramethoxyphenyl porphyrin (CoTMPP) on a carbon black such as Vulcan XC-72 (Cabot Corp., Billerica, MA).
  • the heat treatment is typically done at 400-1000°C in inert gas.
  • the structure of CoTMPP is shown below:
  • This material is a currently preferred catalytic material.
  • Other catalysts include platinum, Mn0 2 and transition metal macrocycles other than CoTMPP.
  • the function of the layer 40 is to allow ready transmission of gas to the active layer 44. Its hydrophobicity also acts to repel liquid electrolyte which exists in the active layer 44 in order to avoid leakage of the liquid electrolyte into the gas side of the cell. It also provides electronic conductivity. The requisite consumption or generation of gas takes place in the active layer 44 where gas and liquid meet in the presence of the active material and optional catalyst, as is we°ll known in the art.
  • Fig. 3 illustrates an electrode holder useful in measuring characteristics of gas consuming or generating electrodes.
  • the electrode nolder generally designated 60, comprises a solid body 62 of a nonconductive material defining a gas inlet passage 64 communicating with a cell gas chamber 55 which in turn communicates with a gas outlet passage 68.
  • a typical material of construction for the body 62 is 3M's Kel-F brand chloro fluorocarbon polymer.
  • An annular electrode seat 70 is definded in the body 62 in order to position an electrode assembly (not shown in Fig. 3) which includes a gas diffusion electrode, generally designated 72, adjacent the cell chamber 66.
  • a conductive (e.g. platinum) wire 74 contact the seat 70 and extends therefrom through the outlet passage 68.
  • a threaded plug 76 of the same material as the body 62 retains an electrode assembly 80 (shown in Fig. 4) in place in the body 62.
  • Fig. 4 illlustrates the electrode assembly, generally designated 80, which includes the gas diffusion electrode 72 of Fig. 3.
  • the electrode 72 is shown in schematic form in Fig. 4 and formed as a cylindrical disk defining gas and electrolyte contacting surfaces 82 and 84 respectively. These surfaces are analogous to surface 15 and 17 of Fig. 1.
  • An annular conductive metal (e.g. platinum) ring 86 is disposed on the gas surface , 82 between the gas surface 82 and an annular rubber gasket 88.
  • a similar rubber gasket 90 is disposed on the electrolyte side of the electrode 72 between the electrolyte contacting surface 84 and an annular ring 92 of the same material as the body 62.
  • the ring 86 When the assembly 80 is in place in the seat 70 of the electrode holder 60, the ring 86 is in electrical contact with the wire 74 and acts as a current collector.
  • the electrode 72 as shown in Figs. 3 and 4 is schematic and these figures do not illustrate certain components such as the hydrophobic backing layer and associated screens.
  • Fig. 5 illustrates an exploded sectional schematic view of a typical embodiment of the diffusion electrode 72.
  • a silver plated nickel screen 100 is adjacent to and in contact with an electronically conductive hydrophobic backing layer 102, typically of Teflon brand PTFE plus carbon black, which defines the surface 82.
  • An active layer 104 which may include a catalyst on carbon black, is adjacent to the layer 102 and defines the surface 84.
  • a steel reinforcement screen 108 is adjacent the active layer 104. When constructed, the screen 100 is not a physical or electrical contact with the ring 186 and this merely acts as a physical restraint.
  • the gas inlet passage 64 and gas outlet passage 68 are connected with gas flow regulating means (not shown) which regulate the flow of gas through the passages 64 and 68 and the cell chamber 66, and thus the gas pressure in the chamber 66 .
  • the screens 100 and 108 may be embedded in the layer 102, and that the layers 102 and 104 may form a single homogenous layer if desired.
  • the electrode holder body 62 is positioned in a test cell such that the electrode holder body 62 is positioned in a test cell such that the electrode surface 894 is exposed to a flowing or non- flowing (e.g. stirred) electrolyte,.
  • a flowing or non- flowing (e.g. stirred) electrolyte e.g. The remainder of the cell and associated temperature control means, etc. are omitted for clarity.
  • the steel screen 108 acts as a reinforcement to prevent physical rupture of the electrode 72.
  • Flow-through of gas from the cell chamber 66 through the electrode 72 into the electrolyte side of the cell is prevented by a hydrophilic hydrogel polymer dispersed through at least a portion of the body of the electrode 72.
  • the hydrogel is an ionomeric polymer which is substantially impermeable to the gross passage of gas and which is ionically conductive. It conducts hydroxide (OH ⁇ ) as well as water. It is also possible for bulk electrolyte to slowly diffuse through the hydrogel.
  • the electrode 72 may be effectively wetted through the hydrogel, while the electrode 72 is virtually impermeable to gas flow by virtue of the presence of the hydrogel in the pore volume of the electrode.
  • the hydrogel-forming coprecipitation reaction takes place between at least two precursor polymers which can react together to coprecipitate to form a hydrophilic hydrogel which is insoluble or substantially insoluble in the electrolyte.
  • each precursor polymer is individually soluble in the electrolyte as this facilitates removal of any excess reactant present in the hydrogel.
  • At least one of the precursor polymers is an ionic polymer.
  • the electrolyte is an alkaline electrolyte
  • a cationic polymer e.g. containing ammonium or pyridinium groups, either pendent or part of the polymer claim
  • an anionic or no-ionic polar polymer In alkaline media, it is preferred that the ratio of the number of equivalents of the cationic to the anionic polymer be greater than 1. In acidic media, this ratio is typically reversed.
  • reaction product may be referred to an an "ion pair bonded polymer".
  • the method of formation of the hydrogel layer is very simple, as is known in the art, and may conveniently be carried out by mixing of solutions of the polymers.
  • the solvent is one in which the hydrogel is insoluble.
  • the ratios of the number of equivalent of the respective precursor polymers will generally be greater than one-, and typically in the range of 3-100:1, depending on the type of electrolyte to be used.
  • the ratio of the number of equivalent of the cationic polymer applied as compared to the weight of applied anionic polymer will generally be greater than one and may range as high as 100:1 or more. This is conveniently carried out by varing the concentrations of the polymers in their respective solutions, with use of approximately equal volumes of polymer solutions.
  • Any solvent which does not damage the electrode structures and in which the polymers are soluble may be used, including aqueous solvent, alcohols, ethers or other organic solvents. It is preferred, however, to use at least one and preferably both of the precursor polymers in low polarity organic solution whereby premature swelling of the polymers is avoided or minimized.
  • coprecipitated hydrogel be swellable upon contact with electroylyte as this enhances the gas impermeability characteristics of the layer.
  • the currently preferred cationic polymer is poly (diallyl dimethyl ammonium chloride), abbreviated pDMDAAC.
  • the currently preferred anionic polymer is poly (styrene sulfonic acid), abbreviated PSSA. Both materials are available for Polysciences of Warrington, Pennsylvania.
  • pDMDAAC is available as a 15 wt. percent solids solution in water
  • PSSA is available in a molecular weight of 70,000 in a 30 wt. percent solids solution in water.
  • the equivalent weights for pDMDAAC and PSSA, respectively, are 161 and 185.
  • each of these polymers is independently soluble in the electrolyte and would promptly wash out of the electrode body once placed in use.
  • the combination of the two polymers with opposite charges on the molecular strands thereof results in a coprecipitated, insoluble hydrophilic gel. This gel retains substantially all of the advantageous qualities of the original components, yet is insoluble in the electrolyte and should not wash out of the electrode. After exposure to water, such a hydrogel may contain up to 99.5 wt. percent (or more) water.
  • the first precursor polymer is a cationic polymer and the second precursor polymer is an anionic polymer which is perfluorinated.
  • Reaction of the cationic polymer with the perfluorinate polymer results in a partially fluorinated hydrogel.
  • This hydrogel is expected to have the particular advantages of high oxygen solubility and low rates of chemical decomposition.
  • fluorinated components especially perfluorinated materials
  • the relatively high solubility of oxygen in fluorocarbon materials is advantageous.
  • the use of fluorinated species in gas diffusion electrodes provides twofold advantages.
  • the high oxygen solubility results in improved electrode (e.g. cathode) voltages, while enhanced chemical stability results in the delay of failure of the device due to chemical attack of the fluroinated species.
  • the hydrogel is preferably preformed prior to incorporation into the electrode. Incorporation into the electrode may readily be carried out by simple mixing with the material of the active layer prior to forming the active material into the electrode.
  • a hydrogel-containing active layer is formed and subsequently joined to a hydrophobic layer in order that the hydrophobic layer be free of the hydrophilic gel, so that the function of the hydrophobic layer is not compromised.
  • CoTMPP Cobalt tetramethoxyphenyl porphyrin
  • CoTMPP in acetone for at least 24 hours.
  • the amount of the adsorbed macrocycle was calculated spectrophotometrically be determining its loss from the filtered solution.
  • the solid catlayst/carbon was air- dried and then heat-treated to 450°C in a horizontal tube furnace under continuous flow of purified argon.
  • Porous gas-fed electrodes were fabricated as follows: dilute (-2 mg/mL) Teflon T30 B aqueous suspension (DuPont) was slowly added to an aqueous suspension of the catalyst/carbon while the latter was ultraso ⁇ ically agitated. The mixed suspension was then filtered with a l ⁇ m pore size polycarbonate filter membrane. A polymeric hydrogel material was mixed with the supsension and then worked with spatula. The paste was shaped into a 1.75 cm diameter disk in a stainless steel die using hand pressure.
  • This disk was then applied to another disk, -0.5 mm thick, of Teflon-carbon black hydrophobic porous sheet material (E ⁇ tech Systems Corp., Fairport Harbor, OH) which contained a silver- plated Ni mesh.
  • Teflon-carbon black hydrophobic porous sheet material E ⁇ tech Systems Corp., Fairport Harbor, OH
  • This dual layer disk was pressed at 380 kg/cm ⁇ at room temperature and then air dried.
  • the gas-fed electrode was place in Teflon-Kel- F electrode holder as shown in Fig. 3.
  • the gas (O2 or air) pressure was applied to the back-side (hydrophobic layer) of the electrode and was monitored at the outlet.
  • a needle valve at the outlets was used to regulate the gas pressure.
  • the O2 reduction measurements for the gas-fed electrodes were done galvanostatically in a concentrated alkaline electrolyte (0.5 M LiOH in 2:1 v/v/ 50% NaOH and 45% KOH) at 80°C with a research potentiostat (Stonehard Associates, Model BC1200). This potentiostat is equipped with positive feedback IR drop compensation and correction circuits.
  • the IR drop correction adjustment is made while monitoring the potential on an oscilloscope, with the current repetitively interrupted for 0.1 us every 1.1 s. This procedure corrects for any IR drop that is external to the electrode itself.
  • Nickel foil was used as the counter electrode and Hg/HgO, OH ⁇ reference electrode was used. The polarization curves were recorded under steady-state conditions.
  • An air cathode was prepared as generally described above with a hydrogel formed by reaction of pDMDAAC and PSSA, both in methanol solution, with a 10:1 pDMDAAC:PSSA weigth ratio (11.5:1 equivalent ratio).
  • the cathode was tested for oxygen reduction with both air and oxygen at a gas/electrolyte differential pressure of 1 psi (5.9 kPa) at 100°C. Results are shown in Fig. 6. When operating with oxygen, measurements were taken both with increasing (Run 1) and decreasing (Run 2) current densities.
  • the relatively high potential exhibited with both air and oxygen and the low slope of both curves are excellent.
  • the potential at 100 mA/cm 2 was —60 V vs. Hg/HgO, OH-. This is -10 V more positive than that obtained for an electrode prepared without hydrogel.
  • an air cathode which could withstand an overpressure of at least 70 kPa (10.1 psi) without blow-through and which had relatively low polarization was prepared.
  • an ion-pair copolymer of pDMDAAC, containing quaternary amines, and Nafion brand fluorocarbon polymer, containing sulfonic acid groups was used as an ingredient of the- active layer. This copolymer readily swells with H 2 0 and forms a hydrogel. When used as a component of the active layer it fills the volume normally occupied by the liquid electrolyte. While the electrode in Fig.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Engineering & Computer Science (AREA)
  • General Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Inert Electrodes (AREA)

Abstract

Electrodes (12) de diffusion de gaz et cellules électrochimiques (10) générant ou consommant du gaz et utilisant lesdites électrodes. L'électrode (12) se compose d'un corps poreux électroniquement conducteur et électrochimiquement actif définissant des surfaces (15, 17) de contact respectives de gaz et d'électrolyte avec un matériau sensiblement imperméable au gaz remplissant au moins une partie du volume des pores dudit corps de sorte à empêcher le passage du gaz par cette partie. Le matériau se compose d'un hydrogel hydrophile insoluble dans l'électrolyte, conducteur ioniquement ionomère, formé par la coprécipitation entre au moins deux polymères précurseurs.
EP88903502A 1987-03-02 1988-03-02 Couche active chargee d'hydrogel dans des electrodes de diffusion de gaz supportant la pression Withdrawn EP0346397A1 (fr)

Applications Claiming Priority (2)

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US2074987A 1987-03-02 1987-03-02
US20749 1987-03-02

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EP0346397A1 true EP0346397A1 (fr) 1989-12-20

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Families Citing this family (2)

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Publication number Priority date Publication date Assignee Title
US4877694A (en) * 1987-05-18 1989-10-31 Eltech Systems Corporation Gas diffusion electrode
WO2023013248A1 (fr) * 2021-08-02 2023-02-09 シャープ株式会社 Batterie

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Publication number Priority date Publication date Assignee Title
US3124520A (en) * 1959-09-28 1964-03-10 Electrode
US3284238A (en) * 1960-08-26 1966-11-08 American Cyanamid Co Novel gel compositions and methods for preparation thereof
JPS526374A (en) * 1975-07-07 1977-01-18 Tokuyama Soda Co Ltd Anode structure for electrolysis
US4615954A (en) * 1984-09-27 1986-10-07 Eltech Systems Corporation Fast response, high rate, gas diffusion electrode and method of making same
US4614575A (en) * 1984-11-19 1986-09-30 Prototech Company Polymeric hydrogel-containing gas diffusion electrodes and methods of using the same in electrochemical systems

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* Cited by examiner, † Cited by third party
Title
See references of WO8806645A1 *

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