Sodium-ion storage devices have received widespread attention because of their abundant sodium resources, low cost and high energy density, which verges on lithium-ion storage devices. Electrochemical redox reactions of metal oxides offer a new approach to construct high-capacity anodes for sodium-ion storage devices. However, the poor rate performance, low Coulombic efficiency, and undesirable cycle stability of the redox conversion anodes remain a huge challenge for the practical application of sodium ion energy storage devices due to sluggish kinetics and irreversible structural change of most conversion anodes during cycling. Herein, a nitrogen-doping graphene/Fe2O3 (N-GF-300) composite material was successfully prepared as a sodium-ion storage anode for sodium ion batteries and sodium ion supercapacitors through a water bath and an annealing process, where Fe2O3 nanoparticles with a homogenous size of about 30 nm were uniformly anchored on the graphene nanosheets. The nitrogen-doping graphene structure enhanced the connection between Fe2O3 nanoparticles with graphene nanosheets to improve electrical conductivity and buffer the volume change of the material for high capacity and stable cycle performance. The N-GF-300 anode material delivered a high reversible discharge capacity of 638 mAh g-1 at a current density of 0.1 A g-1 and retained 428.3 mAh g-1 at 0.5 A g-1 after 100 cycles, indicating a strong cyclability of the SIBs. The asymmetrical N-GF-300//graphene SIC exhibited a high energy density and power density with 58 Wh kg-1 at 1365 W kg-1 in organic solution. The experimental results from this work clearly illustrate that the nitrogen-doping graphene/Fe2O3 composite material N-GF-300 is a potential feasibility for sodium-ion storage devices, which further reveals that the nitrogen doping approach is an effective technique for modifying carbon matrix composites for high reaction kinetics during cycles in sodium-ion storage devices and even other electrochemical storage devices.
Keywords: graphene/Fe2O3 composite; high-performance anode material; nitrogen-doping modified graphene; sodium-ion storage.