Hierarchical urchin-like Co9S8@Ni(OH)2 heterostructures with superior electrochemical performance for hybrid supercapacitors

The hierarchical core-shell heterostructure is a promising electrode material for the construction of highperformance hybrid supercapacitors. Here, a novel urchin-like Co9S8@ Ni(OH) 2 core-shell heterostructure was synthesized. The Co9S8@ Ni(OH) 2 heterostructure exhibited high specific capacity of 1307 C g 1 at a current density of 1 A g 1 and good cycling stability with 98.6% retention after 5000 cycles. Moreover, the hybrid supercapacitor fabricated by using the Co9S8@ Ni(OH) 2 heterostructure as the cathode and activated carbon as the anode delivered maximum energy density of 48 W h kg 1 at 800 W kg 1 with good cycling stability of 85% after 6000 cycles. The unique hierarchical heterostructure and the synergistic effect between each component contributed to the remarkable electrochemical performance of the Co9S8@ Ni(OH) 2 heterostructure. These results will encourage researchers to construct high-performance hybrid supercapacitors by using core-shell heterostructure electrode materials.