Thermal-activated interphase enables high-temperature stable lithium metal batteries

High-temperature operation exacerbates interfacial instability in high-energy-density lithium metal batteries (LMBs). However, conventional electrolytes fail to form robust interphases under thermal stress. Here, we propose a temperature-activated electrolyte for high-temperature LMBs to address instability at the electrode-electrolyte interphases. The electrolyte modulates its solvation structure at elevated temperatures via a temperature-activated, competitive coordination mechanism between the solvent and anions, leading to the formation of a stable first solvation shell. The temperature-activated solvation transition reduces excessive anion aggregation at high temperatures. It enables the formation of a stable, LiF-rich solid electrolyte interphase (SEI) on the anode while simultaneously constructing a protective cathode layer that mitigates surface degradation. Consequently, Li||LiFePO₄ (Li||LFP) cells with this electrolyte demonstrate a high-capacity retention of 70.33% after 500 cycles at 100 °C and 82.15% after 200 cycles at 150 °C. Moreover, the Li||LFP pouch cell (capacity: 500 mA h) based on the electrolyte retain 89.91% of its initial capacity over 40 cycles at 100 °C. Our work presents a novel electrolyte design framework for high-temperature reliable LMBs.