Tailoring the Electrode‐Electrolyte Interface for Reliable Operation of All‐Climate 4.8 V Li||NCM811 Batteries

Abstract Combining high‐voltage nickel‐rich cathodes with lithium metal anodes is among the most promising approaches for achieving high‐energy‐density lithium batteries. However, most current electrolytes fail to simultaneously satisfy the compatibility requirements for the lithium metal anode and the tolerance for the ultra‐high voltage NCM811 cathode. Here, we have designed an ultra‐oxidation‐resistant electrolyte by meticulously adjusting the composition of fluorinated carbonates. Our study reveals that a solid‐electrolyte interphase (SEI) rich in LiF and Li 2 O is constructed on the lithium anode through the synergistic decomposition of the fluorinated solvents and PF 6 − anion, facilitating smooth lithium metal deposition. The superior oxidation resistance of our electrolyte enables the Li||NCM811 cell to deliver a capacity retention of 80 % after 300 cycles at an ultrahigh cut–off voltage of 4.8 V. Additionally, a pioneering 4.8 V‐class lithium metal pouch cell with an energy density of 462.2 Wh kg −1 stably cycles for 110 cycles under harsh conditions of high cathode loading (30 mg cm −2 ), low N/P ratio (1.18), and lean electrolytes (2.3 g Ah −1 ).