Electrolytes
Thermally activated batteries lithium/iron disulfide

The electrolytes used in thermal batteries are molten salts, which are solid at room temperature and therefore electrically insulating. This means they can be permanently stored (for up to 20 years) on the equipment to be supplied with electrical energy, without any loss of performance due to self-discharge. The choice of electrolyte is mainly dictated by its specific properties, which must best serve the desired application (e.g. high ionic conductivity for pulse applications).