Honeycomb-like MgCo2O4@ZnCo layered double hydroxide as novel electrode material for high-performance all-solid-state supercapacitors

Abstract

MgCo2O4 (MC) is a ternary transition metal oxide that has attracted much attention owing to its superb electrochemical properties. Whereas, the sole MC electrode material is difficult to achieve its theoretical specific capacitance (Cs) in practical applications owing to its simple structure, low specific surface area and poor cycle stability. In this study, the assembled MC@ZnCo-LDH on nickel foam (NF) with honeycomb-like microstructure materials by a simple hydrothermal method, calcination treatments and electrodeposition methods. At a current density of 1 A g−1, the Cs of the as-prepared MC@ZnCo-LDH/NF electrode material can reach 2353.8F/g, which is higher than that of MC/NF or ZnCo-LDH/NF related electrode materials. Moreover, an asymmetric supercapacitor (ASC) is successfully assembled with MC@ZnCo-LDH/NF as positive electrode and active carbon (AC) as negative electrode. The MC@ZnCo-LDH/NF//AC device exhibits a relatively high energy density of 61.64 Wh kg−1 at a power density of 750 W kg−1 and it can still maintain 88.9 % of the original specific capacitance after 10,000 cycles. A heart-like LED indicator can be lit by three all-solid asymmetric supercapacitors connected in series for 12.5 mins. The design of honeycomb-like MC@ZnCo-LDH materials may open up a methodology for next-generation high-performance supercapacitors.