Electrochemical cell with high discharge/charge rate capability
AssigneeThe United States of America as represented by the United States Department of Energy
InventorLaszlo Redey
Life of this patent
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Abstract
A fully charged positive electrode composition for an electrochemical cell includes FeS.sub.2 and NiS.sub.2 in about equal molar amounts along with about 2-20 mole percent of the reaction product Li.sub.2 S. Through selection of appropriate electrolyte compositions, high power output or low operating temperatures can be obtained. The cell includes a substantially constant electrode impedance through most of its charge and discharge range. Exceptionally high discharge rates and overcharge protection are obtainable through use of the inventive electrode composition.
Claims15
A fully charged electrode reactant mixture for use in a positive electrode in an electrochemical cell to impart overcharge protection, said reactant mixture comprises the combination of FeS.sub.2, NiS.sub.2, and Li.sub.2 S, wherein Li.sub.2 S is in sufficient amount to be present in solid form in all states of charge and discharge, and wherein FeS.sub.2 and NiS.sub.2 are present in molar ratio of about 3;1 to 1;3.
An electrochemical cell capable of exhibiting overcharge protection including a negative electrode with lithium or lithium alloy as reactant, an electrolyte including a lithium halide and a positive electrode, the positive electrode includes a reactant mixture of iron in elemental or sulfide form, and nickel in elemental or sulfide form, wherein the iron and nickel are present in an Fe:Ni ratio of about 3:1to 1:3 and wherein lithium sulfide is present in the cell in excess of the amount required to form FeS.sub.2 and NiS.sub.2 with all iron and nickel in the positive electrode reactant mixture.
A fully charged positive electrode composition for imparting overcharge protection to a secondary electrochemical cell comprising Li.sub.2 S, FeS.sub.2 and NiS.sub.2, wherein the FeS.sub.2 and NiS.sub.2 are present in a molar ratio to each other of about 1:3 to 3:1 and wherein the Li.sub.2 S is present at about 2 to 20 mole percent of the FeS.sub.2, and Li.sub.2 S reactant mixture and wherein the compostion further includes an electrolyte of alkali metal halides.
Dependencies are inferred from the claim text.