Upcycling Spent Poly(ethylene oxide) Electrolytes into High-Value-Added Lithium Fluoride Nanowhiskers

All-solid-state batteries (ASSBs) represent a transformative advancement in energy storage, distinguished by their superior safety and energy density. However, the sustainable development of ASSBs depends critically on the effective recycling of solid electrolytes and electrode materials from spent batteries, which poses significant challenges. Here, we present a facile and high-value-added carbothermal strategy for recycling spent poly(ethylene oxide) (PEO)-based electrolytes. This approach enables the direct synthesis of one-dimensional lithium fluoride nanowhiskers (1D-LiF) by utilizing the spent PEO-based electrolytes and the surface dead Li components. Through systematic investigation, we identify two mechanisms for the growth of 1D-LiF nanowhiskers and demonstrate the high value of these 1D LiF nanowhiskers in developing advanced composite electrolytes. This simple and efficient upcycling strategy serves as a valuable reference for the recycling of other solid-state electrolytes and supports the sustainable development of ASSBs. The metal-catalysis-free synthesis of LiF nanowhiskers also provides an instructive method for the rational synthesis of 1D metal halide nanomaterials.