LIMITED-CYCLE SECONDARY BATTERY USING LITHIUM ANODE

Abstract : The lithium-cupric fluoride and lithium-cobaltic fluoride electrochemical systems were investigated with eventual battery development as the goal. Specific conductivities of .0134/Omega/cm and .0068/Omega/cm were experimentally determined for solutions of sodium hexafluorophosphate in butyrolactone and propylene carbonate. Cells with reference electrodes showed lithium anode polarization of 70 mv during a 100-hr discharge at 1 ma/sq. in NaPF6-propylene carbonate and 150 mv under similar conditions with NaPF6- butyrolactone electrolyte. Approximately 90-percent utilization of lithium was achieved in these tests. Cupric fluoride cathodes were prepared from cupric fluoride-silver flake blends. Utilization of 72 percent was achieved for cupric fluoride to 1.5-v polarization, which is approximately equivalent to a 2.0-v cell endpoint. Values of 128 w-hr/lb of electrodes or 24 w-hr/lb of electrodes and electrolyte actually used were obtained during these tests. Aluminum-cased cells discharged with a profiled load rate had lower weight-to-energy figures than the previous test cells. Figures of 4 to 15 w-hr/lb of electrode and electrolyte were obtained at 1.2 to 0.6 ma/sq. in. current density to a 2.0-v endpoint.