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Title: Method of preparing electrodes with porous current collector structures and solid reactants for secondary electrochemical cells
Claims: The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: 1. A method of preparing an electrode for use in a high-temperature, secondary, electrochemical cell comprising distributing solid, particulate, electrode, reactant material over an upper surface of an electrically conductive, porous substrate; vibrating said substrate to impregnate said reactant material into a portion of the void volume of said porous substrate; and filling substantially all of the remaining void volume of said substrate with molten electolytic salt. 2. The method of claim 1 wherein said reactant particles are uniformly distributed in a measured amount over a major surface of said substrate and vibrated for a sufficient period to impregnate substantially all particles of reactant uniformly with respect to said major surface of said substrate. 3. The electrochemical cell of claim 1 wherein said electrode is a positive electrode of said secondary electrochemical cell and said reactant material impregnated into said porous substrate comprises a metal sulfide in sufficient volume to occupy between one-fourth and one-half the void volume of said substrate. 4. The method of claim 1 wherein said electrode is a negative electrode of said secondary electrochemical cell and said reactant material impregnated into said porous substrate is a metallic alloy of an alkali metal in sufficient volume to occupy between one-half and three-fourths the void volume of said substrate. 5. The method of claim 1 wherein said substrate is vibrated at a frequency of about 100 to 150 cycles per second and an amplitude of about 0.02 to 0.1 cm for about 30 to 120 seconds. 6. The method of claim 1 wherein said substrate is of 90 to 99 percent porosity prior to said vibrating step and is filled with said particulate reactant material to obtain a porosity of about 20 to 70 percent prior to filling with said electrolytic salt. 7. An electrode prepared by the method of claim 1. 8. In a secondary, high-temperature, electrochemical cell including an alkali metal alloy reactant in the negative electrode, a metal sulfide reactant in the positive electrode, and a molten electrolyte containing ions of said alkali metal, the improvement wherein at least one of said electrodes comprises an integral, porous substrate of electrically conductive material impregnable by said molten electrolyte and having solid particles of reactant distributed throughout the void volume of said substrate. 9. The electrochemical cell of claim 8 wherein said electrode substrate is of a foamed electrically conductive material selected from the group of foamed materials consisting of vitreous carbon foam, graphite foam, iron foam, nickel foam, molybdenum foam, niobium foam and chromium foam. 10. The electrochemical cell of claim 8 wherein said electrode substrate is of flat shape with two major opposing surfaces defining a thickness therebetween, said solid particles of reactant being uniformly distributed in respect to said major surfaces into said substrate. 11. The electrochemical cell of claim 8 wherein said electrode substrate being of flat configuration with opposing major surfaces defining a thickness therebetween, said substrate having a central volume portion circumscribed by marginal volume portions extending through the thickness of said substrate between said major surfaces, said central volume portion being of greater porosity and lesser structural strength than said marginal volume portion and said central portion containing most of said solid particles of reactant contained within said substrate. 12. The electrochemical cell of claim 8 wherein said solid particles of reactant having a melting point in excess of the melting point of said molten electrolyte. 13. The electrochemical cell of claim 8 wherein said porous substrate having interconnected pores of about 100 to 300 microns pore size and a porosity of about 90 to 99 percent excluding said electrolyte and reactant, and said reactant being in the form of solid particles of about 100 to 300 microns size. 14. The electrochemical cell of claim 8 wherein said electrode is a positive electrode and said reactant material is a metal sulfide having a melting point between 500 and 1800.degree.C., and said electrolyte within said cell having a melting point below 500.degree.C. 15. The electrochemical cell of claim 8 wherein said electrode is a negative electrode and said particles of reactant materials are selected from the group of alkali metal alloys consisting of lithium-aluminum, lithium-silicon-aluminum and lithium-silicon having melting temperatures above 500.degree.C., and said electrolyte within said cell having a melting point below 500.degree.C. 16. The electrochemical cell of claim 8 wherein said electrode is a centrally disposed electrode between two electrodes of opposite polarity with major surfaces of said centrally disposed electrode facing major surfaces of said electrodes of opposite polarity, said centrally disposed electrode comprising two porous substrates disposed parallel along inwardly facing, major surfaces and having layers of electronically insulative material over and in contact with said inwardly facing, major surfaces to bias the electrode reaction from the inwardly facing towards the outwardly facing, major surfaces of said centrally disposed electrode. Other info: Inventors: Gay, Eddie C. (Park Forest, IL, US) Martino, Fredric J. (Riverdale, IL, US) Application Number: 565021 Filing Date: 1975-04-03 Publication_date: 1976-01-20 Assignee: The United States of America as represented by the United States Energy (Washington, DC) Primary Class(es): 429/103 429/199, 429/221, 429/223, 429/231.5, 429/231.95 Other Classes: US Patent Ref:
Other Refs: Primary Examiner: Skapars, Anthony Assistant Examiner: Attorney: Carlson; Dean E., Churm; Arthur A., Glenn; Hugh W. |
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