Nitrogen/sulfur dual-doped sponge-like porous carbon materials derived from pomelo peel synthesized at comparatively low temperatures for superior-performance supercapacitors

Pomelo peel is a popular biomass material that is eco-friendly and widely distributed worldwide. However, a large amount of pomelo peel is directly discarded instead of being utilized. This study synthesizes nitrogen/sulfur dual-doped porous carbon materials using pomelo peel and ammonium persulfate, followed by potassium hydroxide (KOH) activation at 600°C, which is lower than most average activation temperature. The as-obtained products are electrode materials applied in supercapacitors. Results indicate that the as-prepared nitrogen/sulfur dual-doped porous carbon material (NSC-600) has high nitrogen (5.89%) and sulfur (0.46%) contents, and a large surface area (1193m2g−1). As the current density is 0.5 A g−1, the specific capacitance of the NSC-600 material up to 310Fg−1. After 10,000cycles, the capacity retention is approximately 98.8% at a current density of 2 A g−1 in 6M KOH, which indicates outstanding cycling performance. Moreover, the assembled symmetric electrochemical capacitor exhibits a high energy density of 21.4Whkg−1 at a power density of 259.9Wkg−1. Therefore, the nitrogen/sulfur dual-doped porous carbon materials synthesized at comparatively low temperatures exhibit promising applications in superior-performance supercapacitors.