Dual-base activation of Ipomoea Aquatica Stalk Biomass Carbon@NiS composites for high-performance supercapacitors

Against the background of energy crisis and increasing environmental pollution, the development of efficient and reliable electrode materials for high-performance supercapacitors has become particularly urgent. In this work, naturally layered Ipomoea aquatica stalks (IA) were used as a carbon source and co-activated with NaOH/KOH to achieve self-templated conversion of biomass, producing biomass-derived carbon (BIC) with vertical “spine-like” channels. Subsequently, by precisely controlling the deposition amount and morphology of flower-like NiS nanocrystals on the BIC surface through the in situ hydrothermal method, a BIC@NiS composite material with a multi-level pore structure, close interface bonding, and optimized hydrophilicity was successfully constructed. BIC@NiS-1 as an electrode material exhibited excellent specific capacitance (1157.8 F/g at 1 A/g) and retained 94.32 % of the capacitance after 10,000 cycles at 10 A/g current density. The assembled BIC@NiS-1//BIC asymmetric supercapacitor achieved a high energy density of 85.12 Wh/kg and a cycling stability of 73.88 % (10,000 cycles) within a voltage window of 1.8 V. This study offers a promising approach for the high-value utilization of biomass waste and lays a solid foundation for the development of supercapacitor electrode materials with both high energy density and excellent stability.