Highly atom-economical and environmentally friendly synthesis of LiMn0.8Fe0.2PO4/rGO/C cathode material for lithium-ion batteries

Due to its flexible two-dimensional layered structure and good hydrophilicity, graphene oxide (GO) is widely used to prepare composite electrode materials for lithium-ion batteries by co-precipitation in aqueous solutions. However, the purification process of GO prepared by the Hummers method is cumbersome and consumes a large amount of water. It also produces wastewater containing heavy metal manganese ions. What's more, both GO and manganese compounds are used during the synthesis of LiMn0.8Fe0.2PO4/reduced graphene oxide/carbon (LiMn0.8Fe0.2PO4/rGO/C) composite. In view of the issues above, a highly atom-economical route based on Hummers method is proposed in this paper to synthesize LiMn0.8Fe0.2PO4/rGO/C. The GO solution obtained by Hummers method is directly used as a substrate solution to prepare (Mn0.8Fe0.2)3(PO4)2·xH2O/GO precipitate, which is then used as a precursor to prepare LiMn0.8Fe0.2PO4/rGO/C by high temperature solid phase sintering. The obtained particles are evenly distributed and wrapped by a graphene-based three-dimensional conductive network. The synthesized composite exhibits good rate performance and cycling stability. In a word, this research develops a new route with high atomic economy and environmental friendliness for the large-scale production of LiMnxFe1-xPO4/rGO/C composites.