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

Abstract

Lithium/carbon fluoride (Li/CF_x) 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 CF_x 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 CF_x 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/CF_x 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.