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

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. Thermal battery: The application of lithium metal embedded in Fe powder matrix as the high power thermal battery anode for military application is investigated in this work along with several optimization parameters that must be considered in order to manufacture safe, reliable thermal battery – Li loading, pressure, current density, and temperature. The detailed electrochemical experiments including EIS and actual battery‐level discharge were studied to discover the underlying mechanism for such high performance.