HARD CARBON/NiCo2O4 COMPOSITE AS AN ANODE MATERIAL FOR SODIUM-ION BATTERIES

This study focuses on the synthesis and electrochemical/structural characterization of hard carbon (HC) derived from resorcinol-formaldehyde (RF) resin, as well as HC/NiCo2O4 composite materials, as anode materials for sodium-ion batteries (SIBs). The HC/NiCo2O4 composite material exhibited a relatively uniform structural morphology, in which NiCo2O4 nanoparticles with sizes of 50–200 nm are distributed over the surface of the hard carbon. Electrochemical tests showed that the composite delivered a specific capacity of about 360 mAh g-1 at 50 mA g-1, maintained a capacity retention of 81% after 35 charge–discharge cycles at various current densities and 37% after 100 continuous cycles at a current density of 100 mA g-1, better than the pristine RF resin-derived HC. This improvement is attributed to the synergistic effect between the Na⁺ adsorption/intercalation mechanism of hard carbon and the Faradaic conversion reaction of NiCo2O4. These results suggest that the NiCo2O4/C heterostructure is a promising anode material for sodium-ion batteries.