Micropore-dominant S, P co-doped carbon derived from biomass waste with rearranged pore structure for enhanced cycling stability supercapacitors

The practical application of carbon and its analogues has been impeded by their high cost and the complexity of preparation methods, thereby driving significant interest in identifying cost-effective alternatives for future energy storage applications. Biomass-derived carbon has emerged as promising substitutes for graphene in energy storage devices. However, enhancing their specific surface area and electrochemical performance remains a considerable challenge. We developed a novel approach by utilizing thiourea and sodium hypophosphite as activators and co-dopants to synthesize sulfur and phosphorus co-doped porous carbon derived from biomass waste. This strategy effectively facilitated pore structure rearrangement and introduced a synergistic combination of non-metallic dopants, significantly improving the electrochemical performance for supercapacitors by adjusting the ratio of co-dopants. The resulting sample exhibited a hierarchical porous structure with superior specific surface area (2691.85 m 2  g −1 ) and abundant micropores, endowing a high capacitance (323.5 F g −1 at 1 A g −1 ) and a superb cycling stability (100.37 % after 10,000 cycles). Furthermore, the assembled button-type supercapacitors yielded a remarkable energy density of 31.8 Wh kg −1 coupled with outstanding cyclic stability, retaining approximately 92.17 % after 25,000 cycles. These promising results exemplified a sustainable and cost-effective approach to design electrode materials for high-performance supercapacitors with extended cycle life.