Re-synthesis of nano-structured LiFePO4/graphene composite derived from spent lithium-ion battery for booming electric vehicle application

Currently extensive attentions on application of LiFePO4 batteries in electric vehicles are attracted to the researchers. Owing to the high cost of raw materials and burdensome preparation process, the re-synthesis of LiFePO4 from spent batteries becomes an economical and convenient way. Herein, a novel closed-loop regeneration process simultaneously from spent LiFePO4 cathode and graphite anode is proposed. Spent LiFePO4 cathode material is first successfully regenerated through Li+ compensation and structure reshaping via hydrothermal method, and then graphene oxide is recovered from spent graphite anode via Hummers method. The as-regenerated LiFePO4/reduced graphene oxide composites present spherical morphology, smaller and more uniform particles. The composite mode of LiFePO4 and graphene includes LiFePO4 distributing in the interlayer structure of graphene and the graphene evenly covering on the surface of the particles. The regenerated LiFePO4/reduced graphene oxide batteries exhibit reversible capacities of 162.6 mAhg(-1) and high columbic efficiency, stable cycle performances at 0.2 and 1C and excellent rate capacity. Through comparison, the regenerated LiFePO4/reduced graphene oxide composites from hydrothermal process shows better prosperities than those of regenerated LiFePO4 from solid phase roasting method whatever electrochemical properties or economical efficiency in the booming electric vehicles and hybrid electric vehicles industrialization.