N-Doped Biomass Carbon/Reduced Graphene Oxide as a High-Performance Anode for Sodium-Ion Batteries

Abstract

For the further development of sodium-ion batteries (SIBs), it is very important to research and develop low-cost and high-performance anode materials. Though hard carbon has high theoretical capacity for SIBs, nevertheless, in practical applications, it presents low conductivity, poor electrochemical stability, and slow kinetics. In this research, a N-doped biomass carbon/reduced graphene oxide (NC/RGO) composite is facilely constructed by pyrolyzing cellulose, chitosan, and GO. The NC/RGO shows a highly reversible sodium storage capacity of 395 mAh g–1 at 0.1 A g–1. Even at a high current density of 5 A g–1, it can retain an ultrahigh and stable capacity of 227 mAh g–1 after 5000 cycles, which exceeds that of most of the reported carbon materials. The RGO improved the conductivity of the carbon. In addition, nitrogen doping not only improved the conductivity but also increased the layer spacing, accelerated electron transfer, and promoted the insertion of sodium ions. Moreover, NC/RGO had a surface-induced capacitive process, which increased the kinetics of ion diffusion during the cyclic process thereby obtaining better electrochemical performance. These data demonstrate a novel idea to design advanced anode materials for excellent-property SIBs.