Template-mediated strategy to regulate hierarchically nitrogen-sulfur co-doped porous carbon as superior anode material for lithium capacity

Considering its rapid lithiation/delithiation process and robust capacitive energy storage,hierarchical porous carbon is regarded as a promising candidate for lithium-ion batteries(LIBs).However,it remains a great challenge to construct a porous structure and prevent structure stacking for carbon-based materials.Herein,a templatemediated approach is developed to synthesize hierarchical nitrogen-sulfur co-doped porous carbon(NSPC)using low-cost asphalt precursors.The strategy for synthesis uses g-C_(3)N_(4) and NaHCO_(3) as gaseous templates and NaCl as a solid template,which causes the formation of hierarchical porous carbon with a high specific surface area.The resultant porous structure and nitrogen-doping process can prevent the aggregation of nanosheets,maintain the structural stability upon cycling,and achieve rate-capable lithium storage.Serving as a LIBs anode,reversible specific capacities of the NSPC24 electrode reach 788 and 280 mAh·g^(-1) at 0.1 and 1 A·g^(-1),respectively.Furthermore,its specific capacity remains at 830 mAh·g^(-1) after 115 cycles at 0.1 A·g^(-1).Even after 500 cycles,high specific capacities of 727 mAh·g^(-1) at 0.5 A·g^(-1) and 624 mAh·g^(-1) at 1 A·g^(-1) are achieved,demonstrating excellent cycling performance.The gas-solid bifunctional template-mediated approach can guide the design of porous materials very well,meanwhile realizing the high value-added utilization of asphalt.