Process for manufacture of positive electrode for lithium/metal sulfide secondary cell
AssigneeGreat Lakes Carbon Corporation
InventorsLouis A. Joo', Frederick C. Miller
Life of this patent
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Abstract
An electrode for a high temperature secondary electrical storage cell including an alkali metal negative electrode, a molten salt electrolyte, and a transition metal sulfide as the positive electrode, formed by mechanically loading a precut form or graphite felt or foam with FeS.sub.x powder, coating or impregnating the precut form with a high carbon yield resin, curing the resin at an intermediate temperature, and carbonizing the resin at a temperature below 1000.degree. C.
Claims5
In a positive electrode for a high-temperature secondary electrochemical cell which uses a positive electrode, a lithium or lithium alloy negative electrode, a molten salt electrolyte containing lithium ions, and a porous separator, and wherein the active material of said positive electrode is a metal sulfide or a metal oxide or mixture thereof 100% of which passes through a 100 mesh per inch screen, and being selected from the group consisting of the sulfides and oxides of iron, copper, cobalt, and nickel deposited within a preformed solid continuous carbonaceous matrix selected from the group consisting of:
- graphite felts;
- carbon fiber felts;
- and carbonaceous foams with a void volume of from 50 to 95%, the improvement wherein said active material is bonded in place in said preformed matrix by the carbonized residue of a high carbon yield resin.
A positive electrode structure for a high-temperature secondary electrochemical cell utilizing a lithium or lithium alloy negative electrode, and a porous separator, said positive electrode comprising a preshaped graphite fiber felt form of approximately 90% void volume, with fibers of 8-10 micron diameter, and a surface area of approximately 20 sg.m./g., said form being mechanically loaded to approximately 30% by volume with cathodically active material selected from the group consisting of the sulfides and oxides of iron, copper, cobalt, and nickel, and mixtures thereof, with a particle size such that 100% of said active material passes through a 100 mesh per inch screen, the improvement comprising said active material being held in place by the carbonized residue of a high carbon yield resin selected from the group consisting of the solutions in water or organic solvents of phenol-formaldehyde condensation products and furan type resins, said form being impregnated with said resin solution under alternating cycles of vacuum and pressure, said form then being heated to cross-link said resin at approximately 150.degree. C. for about 8 hours, then heated slowly to carbonize the resin, reaching the carbonizing temperature of approximately 950.degree. C. over a period of three to six days, the resulting structure of said positive electrode having from 20-77% void volume, approximately 30% by volume said active material within a range of 15 to 50%, approximately 10% by volume graphite fiber, and from 5-15% by volume of the carbonized residue of said high carbon yield resin bonding said active material in place.
Dependencies are inferred from the claim text.