ELECTROCHEMICAL-BEHAVIOR OF NICKEL PHOSPHOTRISULFIDE IN A LITHIUM BATTERY CONTAINING A MOLTEN THIOCYANATE ELECTROLYTE

A study has been made on the electrochemical interaction between nicke l phosphotrisulfide and lithium in a liquid composed of a eutectic mix ture of lithium and potassium thiocyanates at 200-degrees-C. Nickel ph osphotrisulfide is electroreduced in several stages at potentials of 2 .7-1.8 V approximately to Li/Ni = 7.5, after which the products cataly ze the decomposition of the electrolyte. The electrode can work revers ibly with charging-discharging cycles in the range 0 less-than-or-equa l-to Li/Ni less-than-or-equal-to 3, which greatly exceeds the existenc e region for the interstitial phase LixNiPS3 (0 less-than-or-equal-to x less-than-or-equal-to 1.5).