Stabilization of Lithium Metal Interfaces by Constructing Composite Artificial Solid Electrolyte Interface with Mesoporous TiO₂ and Perfluoropolymers

Abstract The next generation of high‐energy‐density storage devices is expected to be rechargeable lithium metal batteries. However, unstable metal‐electrolyte interfaces, dendrite growth, and volume expansion will compromise lithium metal batteries (LMB) safety and life. A simple drop‐casting method is used to create a double‐layer functional interface composed of inorganic mesoporous TiO₂ and F‐rich organics PFDMA. For high‐quality lithium deposition, TiO₂ can provide uniform mechanical pressure, abundant mesoporous channels, and increased ionic conductivity, while PFDMA provides enough F to form LiF in the first cycle and improves Li‐electrolyte compatibility. Experiments and simulations are combined to investigate the optimized mechanism of the LiF‐rich solid electrolyte interface (SEI). The high binding energy of organic matter and Li demonstrates that Li⁺ preferentially binds with the F atom in organic matter. As a result, the tightly bound double‐layer structure can inhibit lithium dendrite growth and slow electrolyte decomposition. Consequently, the symmetric Li||Li cell has a high stability performance of over 800 h. The assembled LiFePO₄||Li cell can sustain 300 cycles at a 1 C rate and has a reversible capacity of 136.7 mAh g⁻¹.