A facile method to prepare Fe3O4@CTP QDs composite as advanced anode material for lithium ion batteries

Graphene quantum dots (GQDs) hybrid compositions have aroused wide attention with regard to their application in energy storage; however, complex procedures for their separation, purification and functionalization hinder their practical application. The present study put forward a facile and environmentally friendly coprecipitation approach to prepare Fe3O4@CTP QDs composites using coal tar pitch (CTP) as "natural GQDs" for the first time. When used as anode in lithium ion batteries (LIBs), the Fe3O4@CTP QDs-2 composite demonstrates high reversible capacity of 810 mAh g−1 over 200 cycles at the current density of 100 mA g−1. Moreover, at a high current density of 2000 mA g−1, the reversible capacity reaches 547 mAh g−1, which is 6 times that of pure Fe3O4 (91 mAh g−1). The marked ameliorated electrochemical performance is attributed to the fact that the successful coupling between Fe3O4 and CTP QDs can not only improves the overall conductivity but also effectively help preserving the structural integrity during cycling. This facile method does not require any cost precursor, harsh reagents, and complicated synthesis processes and can be developed into an eco-friendly way to large-scale production of CTP QDs hybrid materials for applications in energy storage.