An all-climate CFx/Li battery with mechanism-guided electrolyte

Abstract

High-energy-density CFx/Li batteries have attracted wide applications, but encountered poor environmental adaptability at high/low temperatures. Guided with unique electrolyte-involved reaction mechanism, propylene carbonate (PC)/methyl butyrate (MB) co-solvent formulation was optimized to tune the desolvation barrier and stability for wide temperature operation. Weak affinity of Li+-MB and unique solvation structure of electrolyte, which facilitated easy desolvation at both high rate and low temperature, were uncovered with theoretical calculations and spectra characterizations. Desolvation process from intermediate and percolation-type reaction were clearly revealed with in-situ FT-IR and ex-situ TEM. The synergistic effect of handy desolvation with fast kinetics at the interface enabled excellent rate performance (1C, 834 mAh g−1) at +25°C and high capacity (240 mAh g−1) at low temperature of -70°C. Simultaneously, the stability of electrolyte assisted to realize high-temperature tolerance up to +95°C. The mechanism-guided electrolyte design offers deep understanding and novel strategy to improve CFx/Li batteries for wide temperature applications.