Spore-derived porous carbon with tailored heteroatom doping for anode of sodium-ion capacitors
Sodium-ion capacitors (SICs) are attractive for low-cost and safe energy storage, but their practical development is limited by sluggish Na+ storage kinetics and structural instability of anodes. Control of both bulk structure and surface chemistry can address these limitations. We report a heteroatom-rich porous carbon (HRPC) derived from spores via hydrothermal pretreatment, low-temperature carbonization, and acid-mediated functionalization. The optimized GLSHC-HNO3 anode exhibits hierarchical porosity and multi-element co-doping, enabling rapid ion/electron transport, improved electrolyte wettability, and abundant Na+ adsorption sites. Density functional theory calculations reveal distinct contributions of different heteroatom configurations to sodium adsorption. The HRPC anode delivers an ultrahigh reversible capacity of 446.1 mAh g−1 at 50 mA g−1, retains 237.3 mAh g−1 at 2 A g−1, and shows excellent cycling stability. A full SIC with a polyaniline-derived porous carbon cathode achieves an energy density of 114.4 Wh kg−1 at 290 W kg−1, 43.1 Wh kg−1 at 1450 W kg−1, and a maximum power density of 5800 W kg−1, with 84.3% capacity retention after 5000 cycles and nearly 100% Coulombic efficiency. This work establishes a scalable, sustainable route for converting biomass into high-value carbon anodes, providing a new pathway for high-performance sodium-ion energy storage.