Anomalous Temperature Dependence of Lithium Deposition/Stripping Process in Ether‐Based Anode‐Free Lithium Metal Batteries

The formation of lithium dendrites and dead lithium during deposition/stripping process restricts battery performance especially in wide temperature range. However, due to the lack of real-time detection methods, the intrinsic mechanism of how operational temperature affects the dynamic process on lithium metal anodes is still unclear. Here, an in situ investigation of lithium deposition and dead lithium formation during the first charge-discharge cycle in an ether-based electrolyte system is presented. Both the deposition process and stripping process are found to be temperature dependent. Below 293 K, the lithium deposition is less dense plating and the dead lithium is formed, which contributes to the capacity loss. Above 293 K, the lithium deposition becomes denser, and dead lithium formation is significantly reduced. The capacity loss is primarily driven by the formation of solid electrolyte interphase (SEI) resulting from reactions between lithium and ether-based electrolyte. Further study reveals that the ratio of lithium oligoethoxides on the SEI changes abruptly with temperature above 293 K and thus significantly alters the conductivity and reactivity of SEI, which leads to the abrupt change of the deposition/stripping process. These findings highlight the critical role of temperature in lithium deposition/stripping processes in ether-based anode-free lithium metal batteries.