Coal-based graphene/Fe2O3 nanostructures grow on nickel foams as an enhanced free standing anode for lithium ion batteries

The development of new carbon nanomaterials from coal has great application potential in enhancing the electrochemical performance of transition metal oxides to fabricate electrode materials for lithium-ion batteries (LIBs) with high specific capacity and high stability.Herein,the coal-based graphene oxide (CGO) was developed through a combined strategy of high temperature graphitization and chemical oxidation using Taixi anthracite as a carbon precursor,and then the coal-based graphene/ferric oxide (CG/Fe2O3) structures were constructed via electrochemical deposition method with nickel foam as substrate.With the composites directly served as a free-standing anode of LIBs,the high reversible capacity of 1156 mAh/g can be achieved at a high current density of 1.0 A/g,and the capacity retention is 88.9%,when the current density is increased to 5.0 A/g,the capacity can still be maintained at about 1 074 mAh/g,showing a better rate performance and cycling stability than Fe2O3.The analysis of the charge storage mechanism shows that the capacitance of the CG/Fe2O3-1 is mainly contributed by the electric double-layer capacitance generated by CG and the pseudocapacitance generated by the Fe2O3 redox reaction during the charging and discharging process.The remarkable lithium storage capacity of CG/Fe2O3 can be ascribed to the exquisite design of three-dimensional hierarchical architecture,which endows it with a highly interpenetrated porous conductive network and more stable spatial structure,provide more accessible electrode/electrolyte interfaces for effective Li+ and charge transport,accelerating the kinetics of lithiation/delithiation.Overall,the present study provides a useful insight into the development of coal-based graphene composites used as advanced electrode materials for LIBs.