Spore-derived porous carbon with tailored heteroatom doping for anode of sodium-ion capacitors

Sodium-ion capacitors (SICs) are attractive candidates for low-cost and safe energy storage, but their practical development is limited by the sluggish Na + storage kinetics and structural instability of the anodes. Control of both the bulk structure and surface chemistry can address these limitations and achieve fast and durable sodium storage. We report a heteroatom-rich porous carbon (HRPC) produced from spores by hydrothermal pretreatment, low-temperature carbonization, and acid-mediated functionalization. Control of both the pore structure and surface chemistry enables rapid ion/electron transport, improved electrolyte wettability, and abundant Na + adsorption sites. Density functional theory calculations show the distinct contributions of different heteroatom configurations to sodium adsorption, providing mechanistic insights into the improved storage behavior. The HRPC anode has an ultrahigh reversible capacity of 446.1 mAh g −1 at 50 mA g −1 , retaining 237.3 mAh g −1 at 2 A g −1 , and has an excellent cycling stability. A full SIC assembled with a polyaniline-derived porous carbon cathode has an energy density of 114.4 Wh kg −1 at 290 W kg −1 and an 84.3% capacity retention after 5000 cycles. This work establishes a scalable and sustainable route for converting biomass into high-value carbon anodes by controlling both the pore structure and surface chemistry, and providing a new way to provide high-performance sodium-ion energy storage. Download: Download high-res image (96KB) Download: Download full-size image