Comparative study of thermal stability of lithium metal anode in carbonate and ether based electrolytes

The highest specific capacity and the lowest potential make the lithium metal anode an ultimate choice of battery anode and thus becoming a hot topic in the battery research community. Extensive efforts are afforded to improve the electrochemical performances of lithium metal anode and encouraging progresses are made to achieve stable cycling of lithium metal battery. However, the safety issue such as the thermal stability of the lithium metal-based electrode against electrolytes and the practical safety performance of lithium metal batteries, which may be the biggest obstacle for practical application of lithium metal anode, is largely unknown. The present work prepares the metallic lithium deposited in carbonate- and ether-based electrolytes and then compares their thermal stability towards electrolytes. It is found that a significant amount of heat can be generated by the reactions of lithium and electrolyte. The electrolyte solvent, solid electrolyte interphase composition and structure, and lithium deposition morphology are found to impact the thermal behaviors. Based on the thermal behavior of lithium anode, possible thermal runaway reaction chains in lithium metal batteries are revealed and possible modification strategies are proposed, highlighting the important role of electrode/electrolyte interface in achieving high thermal stability of lithium metal anode.