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

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 Li₂O is constructed on the lithium anode through the synergistic decomposition of the fluorinated solvents and PF₆ ^- 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).