Low-energy consumption LiCl–LiBr–KBr–CsBr electrolyte for high-energy thermal battery application

The activation of thermal batteries requires plentiful heat to melt the ambient solid electrolyte into an ionic conductor with high ionic conductivity for large current discharge. The process necessitates massive heating powder to provide heat, severely reducing the effective specific energy of the thermal battery. To decrease energy consumption, we developed the LiCl–LiBr–KBr–CsBr molten salt with low melting point of 239 °C, fusion enthalpy at 59.08 J/g, specific heat capacity of 0.38 J/K·g and 0.88 J/K·g in the solid and liquid states, correspondingly, which takes 44% less heat to reach the operating temperature (generally 500 °C) compared to the commonly used LiF–LiCl–LiBr electrolyte. These reductions not only enable the battery to discharge across a broad temperature range, but also lessens the quantity of pyrotechnic heating pellets and enhances the thermal battery's overall specific energy and safety.