Solvation and interface engineering for stable operation of lithium metal batteries under harsh conditions

Abstract

Stable operation of lithium (Li) metal batteries (LMBs) under harsh conditions (e.g., at high rates, at extreme temperatures, and with water-containing electrolytes) has been suffering from the sluggish charge transfer kinetics at electrode-electrolyte interfaces, and limited thermodynamic stability in general carbonate electrolytes. Herein, lithium nitrate (LiNO₃) and N,N’-dimethylpropyleneure (DMPU) are incorporated into a commercial carbonate electrolyte to address these challenges, it significantly changed the electrolyte solvation chemistry to enhance the electrolyte's moisture tolerance and thermal stability, and lead to nitrided interfaces (including inorganic and organic nitrides) that boost interfacial kinetics and stability. Consequently, the excellent electrochemical performance is achieved with Li||Li symmetric cells, Li||Cu half cells, and Li||LiFePO₄ full cells, under harsh conditons. The Li||LiFePO₄ full cell shows a capacity retention of ∼86.0 % after 8100 cycles at 30C, and they could even cycle stably at temperatures as high as 60 °C and as low as −15 °C; besides, even if using the electrolyte containing 2 % water, the full cell delivers a capacity retention of ∼95.3 % after 5000 cycles at 10C. This work elucidates the correlations between electrolyte solvation chemistry, electrode interface composition, and battery performance, paving a way for realising stable LMBs under harsh conditions.