Dual‐Interphase‐Stabilizing Sulfolane‐Based Electrolytes for High‐Voltage and High‐Safety Lithium Metal Batteries

Abstract

Abstract High‐voltage Li metal battery (HV‐LMB) is one of the most promising energy storage technologies to achieve ultrahigh energy density. Nevertheless, electrolytes reported to date are difficult to simultaneously stabilize the Li metal anode and high‐voltage cathode, especially without the assistance of expensive and corrosive high‐concentration Li salts. Herein, a dual‐interphase‐stabilizing (DIS) and safe electrolyte that bypasses the high‐concentration Li salt is reported. The electrolyte consists of high‐flash‐point sulfolane as solvent, molecular‐orbital‐engineered additives that enable stable B‐F rich cathodic interphase, and unique C‐F rich organic anodic interphase. The stable cycling of both Li metal anode and 4.75 V‐LiCoO2 cathode in the DIS electrolyte (> 500 cycles) is demonstrated. HV‐LMB pouch cells of a high energy density (435 Wh kg−1) can sustainably operate for more than 100 cycles. Moreover, the low cost and high thermal stability of the DIS electrolyte offer superior cost‐effectiveness and safety for large‐scale applications of HV‐LMBs in the future.

Keywords

• high‐voltage electrolytes
• interphase
• lithium metal batteries (LMBs)
• safety
• sulfolane