(1. School of Materials Science and Engineering, Southwest University of Science and Technology，Mianyang 621000，China) (2. Institute of Electronic Engineering, China Academy of Engineering Physics，Mianyang 621000，China)
Thermal batteries are often used as a one-time reserve power source for modern military weapons such as nuclear weapons, missiles and artillery. The separator material of the thermal battery is composed of molten salt electrolyte and binder. It is used to separate the cathode and anode of the battery under normal temperature storage conditions (to prevent self-discharge). Under the working condition of high temperature (350～550 ℃), activated by the heating system inside the battery, the non-conductive solid molten salt electrolyte melts, and the electrodes are connected by ion conduction. Among them, the molten salt electrolyte is in a liquid state within the operating temperature range of the thermal battery (endotherm causes melting), and the binder is always kept in a solid state to adsorb the liquid molten salt, which plays a role in inhibiting the flow of the electrolyte to ensure the normal operation of the thermal battery. For decades, related researchers have been exploring the molten salt electrolyte with low melting point and high electrical conductivity, as well as the binder with high stability and high specific surface area, to extend the life of the thermal battery and reduce the binder amount. Lessening the binder can reduce the internal resistance of the thermal battery and improve the electrical performance of the battery, thereby making the thermal battery develop to the trend of high performance and miniaturization. This article outlines the development of separator materials of thermal batteries in the past years, and introduces from three aspects of the mixed process of molten salt electrolyte, binder and separator material. Finally, according to the research progress and actual application requirements, the future of thermal battery separator materials is prospected.