Modulating thiophene-sulfur content in needle coke-based anode for enhancing the Li/Na-ion storage performance

Carbonaceous materials utilized in lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) are gradually showing an irreplaceable role in numerous energy storage devices due to their excellent electrochemical properties. Nevertheless, the inferior fast charging performance derived from sluggish Li/Na-ion reaction kinetics greatly limits their further development. Herein, a thiophene-sulfur doped needle coke-based porous carbon (SNPC) owning splendid fast-charging performance in both LIBs and SIBs has been prepared by an easily scaled-up ball milling and carbonization strategy. Attributed to high thiophene-sulfur doping content, extended carbon interlayer spacing as well as abundant porous structures, the optimized SNPC sample (SNPC31) exhibits enhanced Li/Na-ion reaction kinetics, thereby improving the fast-charging performance at high current densities. When used in SIBs, SNPC31 anode delivers large specific capacities of 552.8 and 213.4mAh g⁻¹ at 0.05 and 10 A g⁻¹, showing an excellent high-rate performance. Moreover, it retains 84.5 % capacity retention rate for 1000 cycles at 1 A g⁻¹. When employed in LIBs, the SNPC31 anode exhibits considerable reversible capacities of 945.8 and 127.8mAh g⁻¹ at 0.05 and 10 A g⁻¹, also delivering an outstanding high-rate performance. In addition, the anode delivers 91.2 % capacity retention rate for 600 cycles, showing splendid cycle stability. Moreover, various theoretical calculation models including the adsorption energy, diffusion energy as well as the density of states between Li/Na-ion and S-doped carbon material have been rationally fabricated and revealed the enhanced reaction kinetics mechanism. Furthermore, a surface-active site adsorption $-$$-$ inner surface adsorption $-$$-$ interlayer model was proposed for Na ion storage in S-doped hard carbon materials. This study provides new insights into the thiophene-sulfur effect of carbon material for developing excellent fast-charging performance in LIBs and SIBs.