Constructed multifunctional CuOx core and electrodeposited nickel‑cobalt sulfide for high areal energy-power density supercapacitor

Abstract

Construction of heterostructure is regarded as an effective strategy for enhancing the electrochemical performance of electrode materials for supercapacitor. Moreover, the relatively poor conductivity and commonly structural design severely decrease the electron transfer ability and surface utilization of nickel cobalt sulfides during charge-discharge process. In this work, three unique core structures of Cu, CuO, and CuOx (Cu-Cu2O-CuO) were successfully constructed on copper foam via an in-situ redox strategy. Among them, the CuOx cores exhibit higher capacity and lower voltage drop because of the high conductivity of Cu, the generation of built-in electric field between Cu2O and CuO, as well as rich active areas. Three-dimensional interconnected NiCoS nanosheets grown on the surface of CuOx cores with high areal-loading and robust interfacial adhesion. Benefited from the unique structural advantages and synergistic effect of multi-metallic active centers, the CuOx/NiCoS composite exhibits high specific capacitance of 3305 mF cm−2 at 5 mA cm−2, outstanding rate capability of 68.3% when the current density increases to 60 mA cm−2, and long-term lifespan. Notably, the assembled CuOx/NiCoS//PAC asymmetric supercapacitor delivers a high areal energy density and power density (263.3 μWh cm−2 at 2.4 mW cm−2), which can drive some small electronic devices. This study offers a novel pathway for further design of a core-shell structured electrode materials with an enhanced capacity and rate capability for advanced energy storage devices.