Engineering Li + Solvation and Anion Microenvironment via Dipole Modulation for Interface‐Stable High‐Voltage Lithium Metal Batteries

ABSTRACT Carbonate electrolytes underpin the success of current Li‐ion batteries but still remain challenging for high‐voltage Li||NCM811 batteries. Specifically, the carbonate electrolytes fail to stabilize the electrode/electrolyte interface and support high‐power output of Li||NCM811 batteries. Herein, we report an additive, methyl 2,2‐difluoro‐2(fluorosulfonyl)acetate (MDFA), to form weakly solvating electrolytes and weaken EC–PF 6 − interaction via dipole modulation, promoting stable CEI/SEI to restrain the interface degeneration of the NCM811 cathode and Li anode. MDFA also facilitates rich inorganic F‐ and S‐ species in CEI/SEI and boosts charge transfer at cathode/anode interfaces. Finally, this MDFA‐engineered electrolyte enables the Li||NCM811 (4.5 V) battery to achieve a capacity retention of 93% after 250 cycles, and a marked high‐rate performance even at an extreme rate of 20 C with a high capacity of 125 mAh g −1 after 100 cycles. This work provides a novel insight into overcoming interfacial challenges in carbonate‐based high specific power Li||NCM811 batteries.