A green strategy towards fabricating FePO4-graphene oxide for high-performance cathode of lithium/sodium-ion batteries recovered from spent batteries

•The FePO4-GO is initially regenerated from spent LiFePO4 through advanced oxidation.•The cycling performance of FePO4-GO is enhanced by coating with graphene oxide.•The FePO4-GO exhibits enhanced performance for both LIBs and SIBs. Owing to the growing concern about the resource shortage and environmental pollution caused by the vast usage of lithium-ion batteries, the recycle of spent lithium-ion power batteries in electric vehicles becomes urgent. Herein, we report a one-pot method to recover FePO4 from spent LiFePO4 cathode powder through advanced oxidation, which is further successfully used as cathode materials of lithium/sodium-ion batteries (LIBs/SIBs) for the first time. With this facile method, the electrochemical performance can be further improved by simply optimizing FePO4 with graphene oxide coating. The optimized FePO4-graphene oxide (FePO4-GO) exhibits enhanced electrochemical performances of 145 mAh g−1 at 0.5 C for LIBs and 75 mAh g−1 at 0.1 C for SIBs, as well as high capacity retention (144 mAh g−1 at 1 C after 300 cycles for LIBs; 61 mAh g−1 at 1 C after 300 cycles for SIBs). We expect that our current work will provide a facile and green strategy to recover LiFePO4 material from spent batteries.