Novel artificial hybrid LiF/h-BN protective layer constructed on solid polymer electrolyte for highly durable Li metal batteries

Herein, we propose a new strategy for designing and developing a novel architecture of protective hybrid interfacial layers based on a combination of LiF and h-BN as an artificial hybrid SEI for high performance solid polymer electrolyte (SPE)-based LMBs by employing a facile CF₄-plasma surface modification treatment, thus enabling the direct formation of a stable Li⁺ fluorinated artificial layer on the surface of h-BN additive-contained SPE. The Li||LiNi_0.8Co_0.15Al_0.05O₂ cell assembled with surface-modified SPE with artificial hybrid SEI (AH@SPE) exhibits highly stable performance with a specific capacity retention of 98.5 % and an average coulombic efficiency (CE) of 99 % after 200 cycles at 0.2C, along with a capacity retention rate of 90.2 % over 900 cycles with superior CE of 98 %, even at a high C-rate of 1C. The Li symmetric cell assembled with the AH@SPE exhibits excellent Li plating/stripping cycling performance with a stable voltage polarization of ∼35 mV over 1000 h at a current density of 0.1 mA cm⁻². These results indicate that the artificial hybrid SEI with synergistic benefits could enable effective stabilization of the solid-solid interface and facilitate reversible planar Li deposition by suppressing Li parasitic reactions and Li dendrite growth.