Boron doping enhancing the sodium storage capacity of lignite-based hard carbon

Due to their affordable pricing and remarkable physicochemical properties, hard C materials have garnered significant attention in the field of sodium-ion batteries (SIBs). Nevertheless, the application of hard C as SIBs anodes is difficult owing to its poor stable cycle and rate performance, low electrode potential. In this study, we have developed B-doped hierarchical porous C composites using lignite as raw material. The incorporation of B atoms into C matrix can create a substantial number of reactive sites for Na+, and increase the interlayer spacing of C matrix, hence accelerating the process of Na+ de/intercalation. Consequently, when utilized as anodes for SIBs, B-doped hierarchical porous C composites exhibit a substantial reversible capacity of 359.1 mAh g-1 after 400 cycles at 0.1 A g-1, with a capacity retention up to 98.6%. Additionally, these composites demonstrate exceptional long-term stability, maintaining a capacity of 195.9 mAh g-1 after 1000 cycles at a rate of 1.0 A g-1.