Self-Supported Sisal-like CuCo₂O₄@Ni(OH)₂Core–Shell Composites Grown on Ni Foam for High-Performance All-Solid State Supercapacitors

Abstract

Construction of reasonable nanostructures for electrode materials is regarded as one critical strategy for improving capacitance and cycle life of supercapacitors (SCs). Here, self-supported, sisal-like CuCo2O4@Ni(OH)2 composites were successfully synthesized on Ni foam using a hydrothermal treatment followed by the electrochemical deposition reaction. Scanning electron microscopy characterization of the composites verified that the sisal-like CuCo2O4@Ni(OH)2 core–shell nanostructure comprising coating CuCo2O4 nanoneedles with Ni(OH)2 nanoflakes. This novel structure afforded the CuCo2O4@Ni(OH)2 composites a markedly enhanced specific capacitance of 1902 F g–1 at 2 A g–1 and an ultralong cycle life with a captaincy retention of 87.6% after 50 000 cycles at 10 A g–1. Furthermore, an asymmetric solid-state supercapacitor comprising CuCo2O4@Ni(OH)2//activated carbon was assembled and it exhibited a high energy density of 38.6 W h kg–1 at 800 W kg–1. These performances strongly suggest that the self-supported sisal-like CuCo2O4@Ni(OH)2 electrode is a very promising positive material for use in SCs.