Construction of NiCo₂S₄@NiMoO₄ Core‐Shell Nanosheet Arrays with Superior Electrochemical Performance for Asymmetric Supercapacitors

Abstract

Abstract In this work, we develop hierarchical NiCo 2 S 4 @NiMoO 4 nanosheet arrays directly anchored on nickel foam by a hydrothermal method. The self‐supported core‐shell architecture take advantage of high electroactive surface area, rapid channels for ion diffusion and electron transport, and the synergistic contributions from both the NiCo 2 S 4 core and NiMoO 4 shell. Remarkably, the NiCo 2 S 4 @NiMoO 4 electrode showed high specific capacitance of 1487.6 F g −1 at a current density of 1 A g −1 and superior cycling stability (89.7 % capacitance retention after 8000 charge‐discharge cycles). An asymmetric supercapacitor (ASC) with an optimized cell voltage of 1.6 V was assembled by using activated carbon (AC) as the negative electrode and NiCo 2 S 4 @NiMoO 4 electrode as the positive electrode, achieving an extraordinary energy density of 53.2 Wh kg −1 at a power density of 560 W kg −1 , and remained 34.8 Wh kg −1 at a maximum power density of 11.2 kW kg −1 . The outstanding electrochemical behavior indicate that the NiCo 2 S 4 @NiMoO 4 nanosheet arrays hold great promise for high‐performance energy storage devices.