Green Synergy Conversion of Waste Graphite in Spent Lithium‐Ion Batteries to GO and High‐Performance EG Anode Material

The increasing demand for graphite and the higher lithium content than environment abundance make the recycling of anode in spent lithium-ion batteries (LIBs) also become an inevitable trend. This work proposes a simple pathway to convert the retired graphite to high-performance expanded graphite (EG) under mild conditions. After the oxidation and intercalation by FeCl₃ for the retired graphite, H₂O₂ molecules are more likely to penetrate into the extended layers. And the gas phase diffusion caused by the produced O₂ from the redox reaction between FeCl₃ and H₂O₂ further promotes lattice expansion of interlayers (0.535 nm), which is beneficial to the stripping of graphene oxide (GO) with fewer layers. The EG exhibits excellent electrochemical performances in both LIBs and sodium-ion batteries (SIBs). It delivers 331.5 mAh g^-1 at 3C (1C = 372 mA g^-1) in LIBs, while it achieves 176.8 mAh g^-1 at 3C (1C = 120 mA g^-1) in SIBs. Then the capacity retains 753.6 (LIBs) and 201.6 (SIBs) mAh g^-1 after a long-term cycling of 500 times at 1C, respectively. The full cells with the EG electrodes after prelithium/presodiation also show excellent cycle stability. Thus, this work offers another referable strategy for the recycling of waste graphite in spent LIBs.