Electrolyte Engineering Empowers Li||CFx Batteries to Achieve High Energy Density and Low Self‐Discharge at Harsh Conditions

Abstract Given its exceptional theoretical energy density (over 2000 Wh kg −1 ), lithium||carbon fluoride (Li||CF x ) battery has garnered global attention. N ‐methylpyrrolidone (NMP)‐based electrolyte is regarded as one promising candidate for tremendously enhancing the energy density of Li||CF x battery, provided self‐discharge challenges can be resolved. This study successfully achieves a low self‐discharge (LSD) and desirable electrochemical performance in Li||CF x batteries at high temperatures by utilizing NMP as the solvent and incorporating additional ingredients, including vinylene carbonate additive, as well as the dual‐salt systems formed by LiBF 4 with three different Li salts, namely lithium bis (oxalato)borate, lithium difluoro(oxalato)borate, and LiNO 3 . The experimental results unfold that the proposed methods not only minimize aluminum current collector corrosion, but also effectively passivate the Li metal anode. Among them, LiNO 3 exhibits the most pronounced effect that achieves an energy density of ≈2400 Wh kg −1 at a current density of 10 mA g −1 at 30 °C, nearly 0% capacity‐fade rate after 300 h of storage at 60 °C, and the capability to maintain a stable open‐circuit voltage over 4000 h. This work provides a distinctive perspective on how to realize both high energy density and LSD rates at high temperature of Li||CF x battery.