Hierarchical nanoflake-assembled flower-like NiCo double hydroxide@NiC₂O₄ microspheres for high-performance supercapacitor

Assembly of NiCo double hydroxide@NiC2O4 porous microspheres on Ni foam was fabricated by the direct anodisation of nickel foam (NF) and the subsequent electrodeposition of NiCo double hydroxide (NiCo-DH). The obtained Ni foam-supported NiCo-DH@NiC2O4 (NiCo-DH@NiC2O4/NF) was used as the binder-free electrode for electrochemical capacitor (EC). The combination of NiC2O4 and NiCo-DH increases the amount of active sites for redox reactions while the hierarchical porous morphology significantly enhances the diffusion of electrolyte. With Ni foam as 3D conductive substrate and current collector, the electronic conductivity of the electrode material was significantly improved and the diffusion of the electrolyte on the electrode surface was effectively enhanced. NiCo-DH@NiC2O4/NF demonstrates a high areal capacity, a good cycling stability and a good rate capability . In addition, a hybrid supercapacitor (HSC) assembled with NiCo-DH@NiC2O4/NF as the positive electrode and activated carbon (AC) as the negative electrode exhibited good performance with high energy density and power density.