Solid polymer electrolytes (SPEs) are regarded as promising candidates for developing high energy-density Li metal batteries because of their flexible processability and low cost. However, the application of SPEs is still inherently impeded by the mediocre ionic conductivity and unstable Li/electrolyte interface. In this work, the silver fluoride (AgF) additive is introduced to optimize the ionic conductivity of PEO and induce the formation of stable solid electrolyte interphase (SEI) layer between Li metal and SPEs interface, thereby inhibiting the growth of lithium dendrites. AgF can be complex with anions to promote the dissociation of Li