Lithium Anode Cells Operating at Room Temperature in Inorganic Electrolytic Solutions

Lithium anode electrochemical cells have been operated at room temperature using electrolytic solutions of lithium salts in inorganic solvents such as phosphorus oxychloride, thionyl chloride, and sulfuryl chloride. Lithium metal can be electrodeposited from these solutions accompanied, in the case of chlorine‐containing electrolytes, by the simultaneous electrogeneration of chlorine at the positive electrode. The resulting lithium/chlorine electrochemical cells have open‐circuit potentials of 4.0–4.3V, depending on the presence of excess Lewis acid in the electrolyte. The solvents are compatible with both lithium metal and with strong oxidants including chlorine (Cl2), cupric fluoride , polycarbon monofluoride , and tungsten trioxide which can be used as cathode materials. The solvents themselves, while difficult to oxidize, can be electrochemically reduced at various catalytic surfaces (such as carbon black and metals) and act as cathode depolarizers. This catalytic solvent reduction process leads to cells with exceptionally stable voltages and energy densities in excess of 500 W‐hr/kg.