Hollow CoS 2 anchored on hierarchically porous carbon derived from Pien Tze Huang for high-performance supercapacitors.

The development of electrode materials with a high specific capacitance, power density, and long-term stability is essential and remains a challenge for developing supercapacitors. Cobalt sulfides (CoS 2 ) are considered one of the most promising and widely studied electrode materials for supercapacitors. Herein, CoS 2 and hierarchical porous carbon derived from Pien Tze Huang waste are assembled into a cobalt sulfide/carbon (CoS 2 /PZH) matrix composite using a one-step hydrothermal method to resolve the challenges of supercapacitors. The resulting CoS 2 /PZH composite material exhibits a hierarchical porous structure with hollow CoS 2 embedded in a PZH framework. The uniform dispersion of the hierarchical porous structure CoS 2 /PZH is achieved due to the PZH framework, while the uniform decoration of the porous PZH with the hollow CoS 2 prevents the PZH from stacking easily. Moreover, the excellent synergistic effect of the hierarchical porous and hollow structure of CoS 2 /PZH can shorten the electron/ion diffusion channels, expose additional active sites, and provide stable structures for subsequent reactions. As a result, the CoS 2 /PZH composite material displays a high initial specific capacity of 447.5 F g -1 at 0.5 A g -1 , a high energy density of 22.38 W h kg -1 , and long-term cycling stability (a retention rate of 92.3% over 10 000 cycles at 5 A g -1 ).