Construction of hierarchical porous carbon/NiCo2S4 composites by a microwave heating and hydrothermal process for supercapacitors

Carbon-based nanocomposites, characterized by distinctive structural properties, significantly enhance the kinetics of electron and ion transfer for energy storage, thereby achieving remarkable capacitive performance. In this work, Zanthoxylum bungeanum branches derived porous carbon (PC) was fabricated by an effective microwave heating approach. The resulting PC shows a highly developed porous structure and exhibits excellent capacitive behavior, attaining a capacitance of 557.1 F g −1 (at 0.5 A g −1 ). Furthermore, porous carbon@NiCo 2 S 4 (PC@NCS) composites were prepared through a two-step hydrothermal coating approach, in which the NiCo 2 S 4 with an urchin-like morphology was uniformly anchored onto the carbon matrix. This configuration effectively integrates the good conductivity of carbonaceous materials and the high capacity of NiCo 2 S 4 , demonstrating superior specific capacitance of 1176.7 F g −1 (at 0.5 A g −1 ) compared with that of a pure PC. An asymmetric supercapacitor device was assembled utilizing PC and PC@NCS as positive and negative electrodes via a facile screen-printing method. The device achieves a remarkable energy density of 17.58 Wh kg −1 at a power density of 750 W kg −1 and maintains exceptional cycling performance (86.22 % capacitance retention after 100 bending/recovery cycles). Additionally, series-connected flexible supercapacitors were capable of powering small electronic devices after a short charging time, such as LED bulbs and mini fan. These findings demonstrated this study paves a novel way for developing outstanding performance of biomass-based supercapacitors.