Electron Acceptor-Driven Solid Electrolyte Interphases with Elevated LiF Content for 4.7 V Lithium Metal Batteries

High-voltage lithium (Li) metal batteries (LMBs) face substantial challenges, including Li dendrite growth and instability in high-voltage cathodes such as LiNi_0.8Mn_0.1Co_0.1O₂ (NCM811), which impede their practical applications and long-term stability. To address these challenges, tris(pentafluorophenyl)borane additive as an electron acceptor is introduced into an ethyl methyl carbonate/fluoroethylene carbonate-based electrolyte. This approach effectively engineers robust dual interfaces on the Li metal anode and the NCM811 cathode, thereby mitigating dendritic growth of Li and enhancing the stability of the cathode. This additive-driven strategy enables LMBs to operate at ultra-high voltages up to 4.7 V. Consequently, Li||Cu cells achieve a coulombic efficiency of 98.96%, and Li||Li symmetric cells extend their cycle life to an impressive 4000 h. Li||NCM811 full cells maintain a high capacity retention of 87.8% after 100 cycles at 4.7 V. Additionally, Li||LNMO full cells exhibit exceptional rate capability, delivering 132.2 mAh g^-1 at 10 C and retaining 95.0% capacity after 250 cycles at 1 C and 5 V. As a result, NCM811||graphite pouch cells maintain a 93.4% capacity retention after 1100 cycles at 1 C. These findings underscore the efficacy of additive engineering in addressing Li dendrite formation and instability of cathode under high voltage, thereby paving the road for durable, high-performance LMBs.