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 .