Microwave-assisted facile and rapid synthesis of layered metal hydroxide nanosheet arrays towards high-performance aqueous hybrid supercapacitors

Abstract Layered metal hydroxides (LMHs) have been extensively investigated due to their high surface area and excellent properties. However, rapid synthesis of LMHs, with desirable nanostructures and performance, is a challenging task. Herein, a novel microwave (MW)-assisted synthesis route is presented by employing household microwave oven to directly grow LMH nanosheet arrays (NSAs) on current collectors for binder-free electrodes in supercapacitors. Ni(OH)2 NSAs delivered a great capacitance of 2516 and 1273 F/g at 1 and 20 A/g, respectively. Furthermore, a Ni(OH)2//AC aqueous hybrid supercapacitor delivered a significantly large energy density up to 66.7 Wh/kg at 400 W/kg as well as good cycle stability of 85.2%. Moreover, the green and low-cost MW-assisted synthesis route can be adopted for other LMH NSAs, i.e., vertically aligned Cu2(OH)3NO3 NSAs. The excellent electrochemical performance of LMH NSAs can be attributed to the unique nanostructure, direct production of binder-free electrodes and highly efficient MW aqueous method. These results demonstrate the potential of MW-assisted synthesis process for facile and rapid production of LMH NSAs with a wide variety of applications.