One-step microwave-controlled synthesis of CoV2O6•2H2O nanosheet for super long cycle-life battery-type supercapacitor

•The CoV2O6•2H2O nanosheet offered superior durability with 96.4% retention at the current density of 5 A g−1 during 80,000 cycles.•The CoV2O6•2H2O uniform nanosheet piled up in an orderly manner and displayed stable structure.•The CoV2O6•2H2O nanosheet was controlled synthesis at a 90 s heating time via one-step microwave irradiation. The CoV2O6•2H2O nanosheet was controlled synthesis at 800 W microwave power and a 90 s heating time via one-step microwave irradiation. The XRD, XPS, SEM as well as EDS were used to ascertain the crystal structure and chemical constituents of CoV2O6•2H2O nanosheet. Impressively, the CoV2O6•2H2O uniform nanosheet piled up in an orderly manner and displayed stable structure. The material offered superior durability with 96.4% retention at 5 A g−1 during 80,000 circles and had the specific capacity of 177.5 C g−1 (355 F g−1) at 1 A g−1. Meanwhile, the asymmetric supercapacitor was formed from CoV2O6•2H2O as anode as well as activated carbon used cathode, providing excellent cyclic stability (maintaining 78.6% of the highest capacity over 35,000 cycles) and an energy density of 19.0 W h kg−1 with a power density of 400 W kg−1. [Display omitted]