Achieving solid-like liquid antimony sulfide cathodes for high performance thermal batteries

Advanced thermal batteries require new cathode materials with high thermal stability, high capacity, high voltage, and high-rate performance. Although antimony sulfide (Sb 2 S 3 ) has a high theoretical capacity, its low melting point characteristic hinders the application in thermal batteries. Here, we demonstrate that modifying with a small amount of graphite can effectively immobilize liquid Sb 2 S 3 to form a pellet electrode, which allows us to use cathodes made of this liquid active material just like traditional solid-state electrodes. The formation of such a solid-like liquid cathode can be attributed to graphite's affinity for Sb 2 S 3 while repelling the molten electrolyte. The electrochemical testing in LiCl-KCl eutectic at 560 °C and 600 °C indicates that, the performance of the graphite modified Sb 2 S 3 (gra@Sb 2 S 3 ) of optimized proportions far surpasses that of traditional FeS 2 , both in terms of discharge capacity and thermal stability. This study provides a strategy for developing new kind of liquid cathode materials for high-performance thermal batteries.