High-specific capacity thermal battery cathode Fe and Ni doped CoS2 by enhanced thermal stability and conductivity

Abstract

CoS2 can meet the strict requirements of high probability output capacity and high energy output capacity of thermal batteries in modern weaponry thanks to its advantages of low resistivity and high thermal decomposition temperature combined with a full Li+ conductive electrolyte. Nevertheless, CoS2 has the limitations of a low voltage platform and theorical capacity. In this case, Fe and Ni are doped into the CoS2 lattice through low-temperature solid-phase sintering to synthesize Fe0.1Co0.8Ni0.1S2 with a single-phase structure. Fe0.1Co0.8Ni0.1S2 generated by the solid phase method has higher thermal stability, which can reduce the high temperature thermal shock at the immediate start of the thermal battery and assure the safety of the thermal battery in operation. Meanwhile, the mass loss of Fe0.1Co0.8Ni0.1S2 at 615 °C is only 5 %, allowing it to discharge at the maximum effective mass at the normal operating temperature(∼500 °C). Because of the synergistic action of Fe2+, Ni2+, and Co2+ in the discharge process, the discharge voltage of CoS2 increases significantly, giving CoS2 higher specific energy. The simultaneous boost in specific energy and specific capacity indicates that doping has been highly successful in modifying CoS2, making CoS2 more appropriate for the use of high current and long-life thermal cell systems.