Hierarchical Porous and Sandwich-like Sulfur-Doped Carbon Nanosheets as High-Performance Anodes for Sodium-Ion Batteries

The development of high-performance carbon-based anodes for Na-ion batteries is highly desired but still remains challenging because of carbon materials with a low reversible capacity and poor cyclic performance. Herein, novel S-doped carbon nanosheets (SCNs) were prepared by a hydrothermal self-assembly process in the presence of graphene oxide (GO) as the matrix, starch as the carbon source, and dibenzyl disulfide as the sulfur source. The obtained SCNs with hierarchical pores and a sandwich-like structure were utilized as anode materials for Na-ion batteries, exhibiting a high reversible discharging capacity of 207.3 mAh g–1 after 100 cycles at 50 mA g–1. When the current density is up to 1 A g–1, a reversible discharge capacity of 118.8 mAh g–1 can also be acquired. Moreover, the prominent long-term cycling stability of more than 500 cycles can be obtained at 200 mA g–1. The outstanding electrochemical property (high reversible capacity, high rate performance, and long-term cycling stability) of the SCN electrode may be due to the synergistic effect of S doping, hierarchical pores, and the sandwich-like structure. Furthermore, electrochemical kinetic analysis also confirmed that the sodium storage mechanism of the SCN electrode reinforced pseudocapacitive-control behavior. The present study not only shows a high-performance anode material for Na-ion batteries but also provides a new method to prepare S-doped carbon materials for various applications.