Rationally designed CuCoO@Ni(OH) with 3D hierarchical core-shell structure for flexible energy storage.

Composite electrodes that possess both rational structures and appropriate integration are needed to deliver high electrochemical performance in energy storage devices. In this paper, a flexible and binder-free electrode material based on a heterogeneous core-shell structure of CuCoO@Ni(OH) nanosheets grown on carbon cloth was fabricated by a simple method. The unique three-dimensional hierarchical structure gives the electrode a large specific surface area, which enables rapid response and increases of specific capacitance. The CuCoO@Ni(OH)/carbon fiber cloth (CFC) composite electrode exhibited a specific capacitance of 2160 F g at 1 A g and a good rate capability energy of 82.7% at 20 A g. A flexible all-solid-state asymmetric supercapacitor (FAASC) was assembled with the CuCoO@Ni(OH)/CFC electrode as the positive electrode, and activated carbon (AC)/CFC as the negative electrode. This device showed both a high energy density and power density (58.9 W h kg at a power density of 400 W kg), and good long-term cycling stability. Furthermore, the assembled CuCoO@Ni(OH)/CFC//AC/CFC devices were capable of driving a blue light-emitting diode after a short charge. The remarkable performance of this CuCoO@Ni(OH)/CFC electrode indicates that this heterogeneous structure has great potential for applications in flexible high-performance energy storage devices.