N, P Co-doped lignin/petroleum coke-derived carbon nanofibers as advanced anode for high-performance sodium-ion storage

Sodium-ion batteries (SIBs) represent promising alternatives to lithium-ion batteries for grid-scale energy storage owing to abundant sodium reserves. Nevertheless, the large ionic radius of Na + results in sluggish ion diffusion and poor sodium compatibility with graphite, which hinders the development of high-performance SIB anode materials. In this work, N, P co-doped soft-hard carbon nanofiber (PLCFP) are fabricated through electrospinning and subsequent pyrolysis. After systematic carbonization temperature optimization, PLCFP-700 treated at 700 °C delivers a reversible capacity of 339.5 mAh g −1 after 100 cycles at 25 mA g −1 and 224.3 mAh g −1 over 1000 cycles at 500 mA g −1 with outstanding cycling durability. The enhanced electrochemical performance originates from multiple synergistic advantages. N/P co-doping introduces structural defects and widens carbon interlayer spacing to 0.387 nm to facilitate Na + adsorption and intercalation. The one-dimensional nanofiber network accelerates electron transfer and shortens sodium ion diffusion paths. Additionally, the hybrid soft-hard carbon structure suppresses excessive graphitization of petroleum coke and optimizes carbon microcrystalline textures. This study offers a resource-efficient strategy to realize high-value utilization of petroleum coke industrial byproducts and lignin biomass waste, and provides a novel structural design concept for carbon-based anodes in high-performance SIBs.