Armor‐like Inorganic‐rich Cathode Electrolyte Interphase Enabled by the Pentafluorophenylboronic Acid Additive for High‐voltage Li||NCM622 Batteries

Abstract Lithium metal batteries (LMBs) comprising Li metal anode and high‐voltage nickel‐rich cathode could potentially realize high capacity and power density. However, suitable electrolytes to tolerate the oxidation on the cathode at high cut‐off voltage are urgently needed. Herein, we present an armor‐like inorganic‐rich cathode electrolyte interphase (CEI) strategy for exploring oxidation‐resistant electrolytes for sustaining 4.8 V Li||LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622) batteries with pentafluorophenylboronic acid (PFPBA) as the additive. In such CEI, the armored lithium borate surrounded by CEI up‐layer represses the dissolution of inner CEI moieties and also improves the Li + conductivity of CEI while abundant LiF is distributed over whole CEI to enhance the mechanical stability and Li + conductivity compared with polymer moieties. With such robust Li + conductive CEI, the Li||NCM622 battery delivered excellent stability at 4.6 V cut‐off voltage with 91.2 % capacity retention after 400 cycles. The excellent cycling performance was also obtained even at 4.8 V cut‐off voltage.