Chemical crosslinking regulating microstructure of lignin-derived hard carbon for high-performance sodium storage

Lignin, a biomass derived polymer, has gained considerable recognition as a highly promising precursor of hard carbon primarily due to its ample reserve, eco-friendliness, and cost-effectiveness. However, lignin-derived hard carbon via direct carbonization generally yields suboptimal performance for sodium storage due to the unsuitable microstructure. Herein, a simple phytic acid activation combined high-temperature annealing strategy is proposed to regulate the microstructure of lignin-derived hard carbon for high-performance sodium-ion batteries (SIBs) anode. Phytic acid activation not only reduces the ordering and creates abundant closed pores through improving the crosslinking degree and thermal stability of lignin but also introduces P heteroatoms to effectively expand the interlayer spacing of the derived hard carbon. High-temperature carbonization further increases the size of closed pores, leading to a more favorable sodium storage in the plateau region. Consequently, the optimal phytic acid activating lignin derived hard carbon (PLHC 1300) delivers a high capacity of 380.3 mAh g −1 with an enhanced plateau capacity ratio of near 68.1% at 30 mA g −1 , and achieves a capacity retention of near 100% after 150 cycles at 1 A g −1 . This work significant advances the application of lignin in energy storage and contributes to the progression of commercial SIBs. Graphical