Mn3O4/Co(OH)2 cactus-type nanoarrays for high-energy-density asymmetric supercapacitors

A novel Mn3O4/Co(OH)2 cactus-type nanoarrays were directly grown on nickel foam, by a simple two-step process, using an electrodeposition and a hydrothermal process. Mn3O4 particles were used as a backbone anchoring Co(OH)2 to form a cactus-type nanoarray structure. Owing to the synergistic effect of Mn3O4 nanosheet arrays and Co(OH)2, the as-obtained Mn3O4/Co(OH)2 electrode displays an excellent specific capacitance of 1792.9 F g−1 at a current density of 1 A g−1. Furthermore, the assembled Mn3O4/Co(OH)2//reduced graphene oxide asymmetric supercapacitor delivers a high energy density of 53.4 Wh kg−1 at a power density of 800.0 W kg−1, as well as outstanding cycling performance (82.5% retention after 2000 cycles at 10 A g−1). These excellent properties make Mn3O4/Co(OH)2 a favorable candidate for high-performance supercapacitors.