Additive-Enhanced Local-High-Concentration Polymer Electrolyte for Anode-Free Lithium Metal Batteries

Anode-free lithium metal batteries (AFLMBs) show significant potential for next-generation energy storage systems. However, the lifespan of AFLMBs is constrained by continuous parasitic reactions between lithium and electrolytes and the generation of dead lithium. Here, we design a local-high-concentration polymer electrolyte (LHCPE), which is composed of a poly(1,3-dioxolane)/poly(vinylidene fluoride-co-hexafluoropropylene) polymer blend and LiFSI salt. The distinct anion-rich Li+ solvation structure in LHCPE induces an inorganic-rich interface, which can suppress Li dendrites. The additive of tin trifluoromethanesulfonate (Sn(OTf)2) is incorporated into LHCPE to mitigate nonuniform Li deposition through the formation of a CuSn alloy layer on the current collector. The developed electrolyte shows remarkable cycling stability of AFLMB (Cu-NCM811), maintaining 50.9% capacity after 50 cycles at a cutoff voltage of 4.5 V. This strategy is promising in the design of polymer electrolytes for anode-free batteries.