Natural polymers as sustainable precursors for scalable production of N/SO_x doped carbon material enabling high‐performance supercapacitors

Abstract Natural polymers‐based carbon electrodes have gained significant research attention for next‐generation portable supercapacitors. Herein, present an environmentally benign and novel approach for the synthesis of N/S‐O_x carbon material derived from natural polymers on gram scale. By capitalizing the synergistic effect of sulfonated lignin and amino‐containing chitosan, this methodology produces a straightforward, low‐budget, and scalable process. The incorporation of sulfonate motifs from lignin contributes to the formation of C‐SO_x moieties and multi‐porous architecture with a high surface area. Simultaneously, amino groups in chitosan induce nitrogen doping, enhancing conductivity, and wettability. The resulting N/SO_x carbon material exhibits a micro/meso‐porous architecture, facilitating electrolyte diffusion, and demonstrating improved rate capability and pseudocapacitance via Faradaic redox reactions. The N/SO_x carbon material showcases notable capacitance (392 F g⁻¹ at 1 Ag⁻¹) as compared with the reported carbon materials form biomass and outstanding cyclic stability (94.8% retention after 5000 cycles). By optimizing various chitosan mass ratios, the most effective N/SO_x carbon material SNACM = S/N‐doped activated carbon material (SNACM‐2) was produced using a lignin: chitosan sample ratio of 1:2 for symmetric supercapacitors. Furthermore, the quasi‐solid‐state symmetric supercapacitors based on SNACM‐2 exhibit an excellent specific capacitance of 142 F g⁻¹ at 1 A g⁻¹, coupled with outstanding flexibility. The SNACM‐2 demonstrates a high‐energy density of 9.8 W h kg⁻¹ at a power density of 0.5 kW kg⁻¹. This study presents a successful strategy for transforming low‐valued, eco‐friendly natural polymers into renewable, high‐performance carbon materials for supercapacitors. image