Fluorine- and Nitrogen-Donating Gel Polymer Electrolytes Enabling LiF- and Li3N-Enriched SEI for Stabilizing Lithium Metal Anodes

Lithium metal has attracted extensive attention as a promising anode material for high-performance lithium batteries. However, an unstable and fragile solid electrolyte interphase (SEI) could be formed by the side reactions between Li metal and liquid electrolytes and induce the formation of dendritic growth. Here, we propose a facile strategy to fabricate fluorine- and nitrogen-donating gel polymer electrolytes (FN-GPEs) via the polymerization of hexafluorobutyl methacrylate (HFBMA) and triazole-based methacrylate (TBMA). A uniform porous structure is formed through the regulation of the ratio of HFBMA and TBMA in the polymer matrix, which is beneficial for absorbing the liquid electrolyte and enhancing the ionic conductivity. More significantly, the FN-GPEs containing abundant fluorinated and nitrided chains could form a stable SEI in situ with the components of LiF and Li3N. This facile strategy can achieve the complementary advantages of LiF- and Li3N-based SEI protective layers and significantly enhance the interfacial stability. Consequently, the FN-GPEs exhibit high porosity, high ionic conductivity, enhanced Li-ion transference number, and a wide electrochemical window, which endow the Li/Li symmetrical cells with excellent cyclic stability, and the LiFePO4/Li batteries show good long-term cycling stability. This work provides a new avenue to construct a stable SEI in situ on Li metal via molecular design to achieve high-performance LMBs.