Electrolyte Strategy Enables High‐Rate Lithium Carbon Fluoride (Li/CF_x) Primary Batteries in All‐Climate Environments

Abstract

Lithium/carbon fluoride (Li/CFx) batteries have garnered significant attention due to their exceptional theoretical energy density (2180 Wh kg−1) in the battery field. However, its inadequate rate capability and limited adaptability at low‐temperature are major bottlenecks to its practical application due to the low conductivity of CFx materials and electrochemical inertness of discharge products LiF. Herein, an efficient and novel functional electrolyte formula is disclosed with tin trifluoromethanesulfonate (Sn(OTf)2) as an additive to solve these challenges. It is shown that Sn(OTf)2 possessing reasonable Lewis acidity can effectively facilitate the dissolution of LiF during the discharging process. Thereafter, the CFx electrode materials exhibit excellent rate performance with 1145 Wh kg−1 at 15 000 mA g−1 (or 15 A g−1, 30 °C) and high capacity retention of 95.8% at a low temperature of −50 °C compared with the operating temperature of 30 °C. Moreover, the Sn2+ dissolved from Sn(OTf)2 promotes the formation of Li‐Sn alloy on the lithium metal anode, effectively protecting the lithium metal anode, and Li/CFx battery can be well stored for over 1 000 h at 60 °C with negligible self‐discharge behavior. This work presents a novel electrolyte exploring strategy that can effectively guide the development of next‐generation electrolytes operating under extreme conditions.