Rational Design of Sulfur-Doped Carbon with Expanded Inter-layer Spacing toward Anode Material of Sodium-Ion Batteries

For renewable energy storage, it is critical to develop effective carbon-based anode materials for sodium-ion storage, and heteroatom doping is a viable method for fine-tuning the electrochemical performance of carbon materials. Heteroatom-doped carbon materials, especially sulfur-doped carbon (CS) materials, have been the favored anode material to provide enhanced specific capacity for sodium-ion batteries. This report provides a method for the successful preparation of CSs from thiophene as a single-source precursor accompanied by annealing at a high temperature. The existence of sulfur provides expanded interlayers of carbon, and via changing the pyrolysis temperature (1000–1200 °C), the sulfur content is varied. Under a current density of 25 mA g–1, the produced electrode material acts as an anode and exhibits a specific capacity of almost 243 mA h g–1. The fabricated electrode also exhibits outstanding cyclic stability, sustaining 77% at 100 mA g–1 current over 500 cycles. The synergistic effect of sulfur and expanded interlayers of carbon brought on by the doping of sulfur atoms can be the reason for the optimized carbon's improved performance.