Li–Ga Alloy-Contained Hybrid Solid Electrolyte Interphase Induced by In Situ Polymerization for High-Performance Lithium Metal Batteries

Construction of quasi-solid-state lithium metal batteries (LMBs) by in situ polymerization is considered a key strategy for the next generation of energy storage systems with high specific energy and safety. Poly(1,3-dioxolane) (PDOL)-based electrolytes have attracted wide attention among researchers, benefiting from the low cost and high ionic conductivity. However, interfacial deterioration and uncontrollable growth of lithium dendrites easily appeared in LMBs due to the high reactivity of lithium metal, resulting in the failure of LMBs. In this work, a strategy is developed of using Ga(OTF)₃ as the initiator to obtain a PDOL-based gel electrolyte (GaPD). In addition, a hybrid stable solid electrolyte interphase (SEI) of lithium fluoride/Li₂O/Li-Ga alloys is observed on the surface of lithium metal. Combined with density functional theory calculations, the hybrid SEI shows high affinity toward Li⁺, indicating that a uniform deposition of Li⁺ could be achieved. Therefore, the Li/GaPD/Li cell operates stably for 1600 h at room temperature. In addition, the LiFePO₄/GaPD/Li cell retains a capacity retention rate of 90.2% over 200 cycles at 1 C. This work provides a reference for the practical application of in situ polymerization technology in high-performance and safe LMBs.