Solid-state-grinding method to synthesize NiCoFe alloy/NiCoFe–OH nanosheets for asymmetric supercapacitor

Abstract Solid-state-grinding is a facile method to prepare electrode materials, which is more beneficial to large-scale production. Herein, 3D NiCoFe alloy framework covered with NiCoFe–OH nanosheets hybrid architecture is constructed via solid-state-grinding and subsequent glycerol solvothermal treatment. Highly conductive NiCoFe alloy core stimulates its fast and charged transport, and as a result, high-capacity NiCoFe–OH nanosheets with rich active sites could participate into rapid electrochemical phase variation with KOH electrolyte. Moreover, the abundance of existing interfaces between the NiCoFe and NiCoFe–OH structures produces more electrochemical activity and presents further improvement to the electrical conductivity, both of which greatly regulate the electrochemical performance of electrode materials. NiCoFe/NiCoFe–OH//active carbon (AC) asymmetric supercapacitor (ASC) was assembled, showing a specific capacitance of 106 F g−1 at 1 A g−1, 36% of capacitance retention at 10 A g−1 and 37.4 Wh kg−1 of energy density at 756.4 W kg−1 of power density. The most noteworthy is its excellent cycling stability, 89.3% of capacitance retention after 20,000 cycles. The simple and large-scale preparation method, high energy and power densities, and long cycling stability make NiCoFe/NiCoFe–OH//AC ASC an ideal energy storage device for driving LED bulbs and electronics, etc., as well as being able to charge/discharge repeatedly.