Carbon-based anode: Nitrogen-doped graphene (N-GN), nitrogen-doped graphene-coated Fe _x O _y (Fe _x O _y @Fe-N-GN), and nitrogen-doped graphene with hollow nano-hemispheres (Fe-N-GN) were produced as anode materials for lithium ion batteries. The Fe-N-GN obtained from acid leaching of Fe _x O _y @Fe-N-GN outperformed other samples showing the significance of simple chemical post-processes to enhance the performance of carbon-based materials.

Abstract

The development of high-performance Li-ion battery anodes is closely dependent on understanding the effect of chemical and physical properties of active materials played in the storage mechanism. In this study, mesoporous high surface area nitrogen-doped graphene (N-GN) and nitrogen-doped graphene-coated nano-spherical Fe _x O _y containing composite (Fe _x O _y @Fe-N-GN) were synthesized by a bottom-up solvothermal process using required starting materials. Acid leaching of Fe _x O _y @Fe-N-GN resulted in a highly microporous structure consisting of a hollow graphene nano-hemisphere and a large basal plane monoblock structure with 63 % N-doped graphene and 37 % graphitic N-doped graphene (Fe-N-GN). While N-GN and Fe _x O _y @Fe-N-GN exhibited 310 and 571 mAh g⁻¹ reversible capacity, respectively, after 100 cycles, Fe-N-GN showed 940 mAh g⁻¹ reversible capacity through >70 % diffusion-controlled process with beneficially lower intercalation potential below ~0.25 V and 87 % capacity retention demonstrating the impact of the chemical composition and structural properties on the capacity of carbon-based anodes.