Interrogating the Thermo‐Electrochemical Instability and Safety in Lithium Metal Electrodes with Liquid Electrolytes

Lithium metal anodes (LMAs), with their high specific capacity and low electrochemical potential, are considered the ultimate choice for next‐generation batteries. Significant efforts have been made to enhance the performance of LMAs, yielding encouraging progress toward improving the stability of lithium metal batteries (LMBs). However, the interplay between electrochemical performance and thermal safety remains a critical challenge, particularly in systems utilizing liquid electrolytes. This study presents a comprehensive investigation into the thermal stability of LMBs by evaluating the impact of different liquid electrolytes on electrochemical response, solid electrolyte interphase (SEI) formation, and thermal runaway characteristics. Through a combination of electrochemical experiments, accelerating rate calorimetry, and physics‐based modeling, it delineates how electrolyte decomposition pathways and SEI chemistry play a pivotal role in the thermo‐electrochemical stability of LMBs. The findings highlight a fundamental trade‐off between electrochemical performance and safety, emphasizing the need for tailored electrolyte formulations to mitigate decomposition pathways leading to thermal instability. By establishing a mechanistic correlation between electrolyte composition, SEI evolution, and thermal stability, this study provides a framework for designing safer, high‐performance LMBs.