South China University of Technology researchers have proposed a sustainable strategy to synthesize a series of FePO4 wrapped by reduced graphene oxides (FePO4@rGx (x = 0.05, 0.10 and 0.15) composites directly from waste LiFePO₄ batteries.
This strategy not only provides closed-loop recycling of both cathode (LiFePO₄) and anode (graphite) materials, but also enhances performance via in situ rG wrapping.
The series of FePO4@rGx were prepared by hydrothermal treatment of FePO4 in the presence of graphene oxides (GO) with different mass concentration (x = 0.05, 0.10 and 0.15 for GO/(FePO4 + GO)). FePO4 and GO were obtained from the oxidation of wLFP by Na2S2O8 and the Hummer's treatment of wG, respectively.
Benefiting from the rational level of rG with the improved electronic/ionic conductivity and accommodation of the volume change of the electrode during the cycles, the FePO4@rG0.10 can deliver a high initial reversible specific capacity of 166.8 mAh g−1 at 0.1C, excellent rate capability (e.g., 128.3 and 112.6 mAh g−1 at 5 and 10C, respectively) and maintains relatively long-term cycling stability over 500 cycles (e.g., 144.5 mAh g−1 after 500 cycles at 1C), which are much more superior than those of FePO4.
The synthesis of FePO4 and GO originate from electrodes of a used LiFePO4 battery and the use of FePO4@rG0.10 as cathode materials for LIBs displays impressive lithium storage properties.
