Synthesis of porous carbon materials with mesoporous channels from Sargassum as electrode materials for supercapacitors

Abstract

Using Sargassum as the precursor, a facile strategy was developed to synthesize three-dimensional porous carbons with mesoporous channels as high-performance electrode materials for supercapacitors employing aqueous ammonia pretreatment and KOH activation. Part of lignin was removed by the pretreatment of aqueous ammonia, which led to the swelling of biomass structure and the formation of unique mesoporous channels during the activation process. After being pretreated by 10 wt% aqueous ammonia, the specific surface area of the as-synthesized SAC-N 10 reached as high as 3251.42 m 2 g −1 with many mesoporous channels. Based on the unique structure, SAC-N 10 exhibited excellent electrochemical performance with a high capacitance of 336 F g −1 at 1 A g −1 and a good rate capacity of 82% retention at 10 A g −1 in a two-electrode system using 6 M KOH as the electrolyte. After being tested for 10,000 cycles at a current density of 5 A g −1 , SAC-N 10 retained 85.0% of the initial specific capacitance. The SAC-N 10 also showed a high energy density of 44.42 W h kg −1 and a power density of 2441.25 W kg −1 at a current density of 1 A g −1 in the voltage range of 0–1 V. • Porous carbons with mesoporous channels were synthesized from sargassum. • Aqueous ammonia pretreatment led to the formation of unique mesoporous channels. • A large surface area of 3251.42 m 2 g −1 with many mesoporous channels was achieved. • The carbon-based electrode exhibited a high capacitance of 336 F g −1 at 1 A g −1 .