Thin film composite electrolytes, sodium-sulfur cells including same, processes of making same, and vehicles including same
AssigneeTrans Ionics Corporation
InventorRobert C. Schucker
Life of this patent
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Abstract
Thin film composite electrolyte structures are disclosed that are preferably ionically conductive but not electronically conductive and are therefore suitable for use in electrochemical cells, such as secondary batteries based on sodium and sulfur. Vehicles including the electrochemical cells are also disclosed.
Claims34
A thin film composite electrolyte structure suitable for use in electrochemical cells, which composite electrolyte structure is comprised of a first layer comprised of a mixture of two or more chemically distinct compounds, at least one of which is ion-conductive, and ii) a second layer to which is bonded said first layer, said second layer being comprised of a refractory support structure having an effective microporosity that will allow a flow of anodic or cathodic reactants to said first layer, wherein said first layer and said second layer have a coefficient of thermal expansion within about 5 percent, or less, of each other.
A method for producing a composite thin-film electrolyte structure suitable for use in high temperature electrochemical cells, which process comprises:
- a) selecting a microporous refractory support substrate;
- b) applying to said substrate a mixture of at least two electrolyte compositions, at least one of which is conductive with respect to a predetermined ion, said mixture being formulated to have, when dried and sintered, approximately the same average coefficient of thermal expansion as the microporous substrate;
- c) drying said mixture;
- and d) sintering said mixture for an effective amount of time and at an effective temperature to produce a substantially dense composite electrolyte layer on said substrate.
An electrochemical cell comprising:
- a) an anode containing at least one anodic reactant;
- b) a cathode containing at least one cathodic reactant;
- and c) a composite ion-conductive electrolyte structure comprised of:
- i) a first layer comprised of a mixture of two or more chemically distinct compounds, at least one of which is ion-conductive;
- and ii) a second layer to which is bonded said first layer, said second layer being comprised of a refractory support structure having an effective microporosity that will allow a flow of anodic or cathodic reactants to said first layer, wherein said first layer and said second layer have a coefficient of thermal expansion within about 5%, or less, of each other.
A method of making a thin-film electrolyte structure and composition comprising an ionically conductive layer and a porous substrate, the methods comprising the steps of:
- a) depositing a composition comprising a precursor of the porous substrate via a deposition process onto an electrically conductive, oxidizable substrate material;
- b) applying, via electrophoretic deposition, a composition comprising a presursor to the ionically conductive layer to at least a portion of the composition comprising a presursor of the porous substrate, preferably without intermediate drying of the composition comprising a precursor of the porous substrate, thus forming a green structure and composition;
- and
- c) drying and sintering the green structure and composition in an atmosphere comprising oxygen to remove substantially all of the electrically conductive, oxidizable substrate material.
A method of making a thin-film electrolyte structure and composition comprising an ionically conductive layer comprising β-alumina and a substrate comprising α-alumina, the method comprising the steps of:
- a) depositing a composition comprising α-alumina via a deposition process onto an electrically conductive, oxidizable substrate material, thus forming a composition comprising α-alumina on the substrate;
- b) applying, via electrophoretic deposition, a composition comprising β″-alumina to at least a portion of the composition comprising α-alumina, preferably without intermediate drying of the composition comprising α-alumina, thus forming a green structure and composition;
- and
- c) drying and sintering the green structure and composition in an atmosphere comprising oxygen to remove substantially all of the electrically conductive, oxidizable substrate material.
A transportation vehicle comprising an electrochemical cell, the electrochemical cell connected electrically to a motor, the electrochemical cell comprising an anode material comprising liquid sodium, a cathode material comprising liquid sulfur/polysulfide mixture, and a thin-film electrolyte, the thin-film electrolyte selected from the group consisting of
- a) a structure having a first layer comprising a mixture of β″-alumina and Na3Zr2Si2PO12, and a second layer comprising graphite;
- and
- b) a structure having a layer of β″-alumina bonded to a layer of α-alumina, the layer of β″-alumina having a thickness less than 50 microns, and the layer of α-alumina having a thickness less than 100 microns.
Dependencies are inferred from the claim text.