Upcycling Spent LiFePO ₄ Toward Pseudo‐Solid‐Solution LiFePO ₄ @Li ₃ V ₂ (PO ₄ ) ₃ With Great High‐Voltage Stability and Rate Properties

ABSTRACT For highly effective recycling of spent LiFePO 4 (LFP), direct regeneration has been regarded as a next‐generation strategy due to low energy consumption and a short process. Considering S‐LFP derived from industry 10 years ago, simply recovering physical‐chemical properties hardly meets the demand of up‐to‐date high rate and voltage. Upcycling spent LFP is urgent for effective regeneration. Combining the advantages of a homogenization manner, spent LFP is successfully regenerated for LFP@LVP composites. Benefitting from the same monoclinic system of Li 3 V 2 (PO 4 ) 3 (LVP) and intermediate Li 3 Fe 2 (PO 4 ) 3 , the uniform distribution of both phases is noted at nano‐size, deemed as pseudo‐solid‐solution, along with the lowering diffusion energy barrier 0.23 eV, leading to the obvious improvements of Li + /e − conductivity and the establishments of rapid shuttling paths. Supported by the high‐voltage stability of LVP, it served as charge‐supplying compensation at excessive charge state. The detailed kinetic analysis revealed their enhancements of the internal ion‐diffusion coefficient. The as‐regeneration sample displays a capacity of 150 mAh g −1 at 1.0 C at high‐voltage. Even at 20.0 C after 2000 cycles, its capacity has remained about 90 mAh g −1 . Thus, the work is anticipated to offer the upcycling strategies of spent LFP, whilst illustrating their formation mechanism of isomorphisms.