Li–Ga Alloy-Contained\nHybrid Solid Electrolyte\nInterphase Induced by In Situ Polymerization for High-Performance\nLithium Metal Batteries

Construction of quasi-solid-state lithium metal batteries\n(LMBs)\nby in situ polymerization is considered a key strategy for the next\ngeneration of energy storage systems with high specific energy and\nsafety. Poly(1,3-dioxolane) (PDOL)-based electrolytes have attracted\nwide attention among researchers, benefiting from the low cost and\nhigh ionic conductivity. However, interfacial deterioration and uncontrollable\ngrowth of lithium dendrites easily appeared in LMBs due to the high\nreactivity of lithium metal, resulting in the failure of LMBs. In\nthis work, a strategy is developed of using Ga(OTF)<sub>3</sub> as\nthe initiator to obtain a PDOL-based gel electrolyte (GaPD). In addition,\na hybrid stable solid electrolyte interphase (SEI) of lithium fluoride/Li<sub>2</sub>O/Li–Ga alloys is observed on the surface of lithium\nmetal. Combined with density functional theory calculations, the hybrid\nSEI shows high affinity toward Li<sup>+</sup>, indicating that a uniform\ndeposition of Li<sup>+</sup> could be achieved. Therefore, the Li/GaPD/Li\ncell operates stably for 1600 h at room temperature. In addition,\nthe LiFePO<sub>4</sub>/GaPD/Li cell retains a capacity retention rate\nof 90.2% over 200 cycles at 1 C. This work provides a reference for\nthe practical application of in situ polymerization technology in\nhigh-performance and safe LMBs.