Investigation of Li Anode/FeS₂ Cathode Electrochemical Properties for Optimizing High‐Power Thermal Batteries

Abstract Herein, the discharge properties of lithium (Li) anode with FeS₂ cathode system are investigated under different pressure loads, weight percent of Li, temperatures, and current densities to provide a fundamental understanding of the operational safety, electrochemical properties, and optimization parameters for Li anode‐based thermal batteries. The lithium anode was prepared via physically mixing Li with Fe powder. The Li−Si alloy, the most common anode for thermal batteries, was investigated simultaneously to show the clear distinction in electrochemical performance between the Li anode and Li−Si anode. For achieving high operational safety and discharge performance with Li anode, the recommended pressure load and weight percent of Li are below 6 kgf cm⁻² and 15 wt%, respectively, to prevent any leakage or short‐circuiting problems. The discharge at 500 °C and 0.2–0.4 A cm⁻² exhibits the optimal performance for the Li anode and FeS₂ cathode system. Finally, the thermal batteries with 17 cells are manufactured to confirm the aforementioned parameters at −32 and 63 °C to demonstrate that the previous results coincide with the actual battery level experiments. Due to the intertwined nature of the parameters, the optimization should always be conducted in a holistic manner to obtain high‐performance thermal batteries for future military applications.