Natural polymers as sustainable precursors for scalable production of N/SOx 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-Ox 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-SOx 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/SOx carbon material exhibits a micro/meso-porous architecture, facilitating electrolyte diffusion, and demonstrating improved rate capability and pseudocapacitance via Faradaic redox reactions. The N/SOx 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/SOx 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. (Figure presented.).