Wide‐Temperature, High‐Voltage, Flame‐Retardant Electrolyte for 4.8 V Li||NCM94 Batteries

Abstract All‐climate lithium metal batteries attract great interest, but their poor safety and cycling performance hinder their applications, especially with high cut‐off voltage nickel‐rich layered oxide cathode. Herein, we develop a high‐voltage, wide‐temperature, and flame‐retardant electrolyte for Li|| LiNi 0.94 Co 0.05 Mn 0.01 O 2 (NCM94) batteries with excellent cycling performance through constructing highly Li + ‐conductive, lithophilic gradient cathode electrolyte interphase (CEI). Such CEI exhibits a gradual decrease in C─F and a gradient increase in LiF and LiB x O y from the outside to the inside, which effectively inhibits structural degradation of the NCM94 cathode. With an excellent CEI, Li|| NCM94 batteries show outstanding cycling stability and wide temperature applicability (−40∼60 °C). The battery could exhibit a capacity retention of 87% after 200 cycles at 4.8 V, and deliver 112% (or 56%) of their room‐temperature capacity at 60 °C and −40 °C, respectively. Furthermore, as‐constructed 7.6 Ah pouch cell could run 145 cycles with an energy density of 541 Wh kg −1 . This work provides the guidance on designing electrode–electrolyte interfaces for wide‐temperature, high‐voltage lithium metal batteries.