CuO embedded β-Ni(OH)2 nanocomposite as advanced electrode materials for supercapacitors

Abstract

A new nanocomposite has been prepared embedding CuO nanoparticles as an additive into grafted β-nickel hydroxide electrode and their electrochemical performance in KOH electrolyte have been investigated. β-nickel hydroxide (β-Ni(OH)2) has been prepared by a simple precipitation method. Ni(OH)2/NiOOH, the main active materials in the pasted nickel electrode have been prepared using nickel mesh in the form of current collector. A study on the electrochemical performances of the pure β-Ni(OH)2 and CuO added β-Ni(OH)2 electrodes in 6.0 M KOH electrolyte has revealed that CuO embedded β-Ni(OH)2 displays much higher specific capacitance and better cyclability than pure β-Ni(OH)2. In fact, the addition of CuO improves the reversibility of the electrode by reducing the anodic (Epa) and cathodic (Epc) peak potential difference and also increases the separation of the oxygen evolution (EOE) and anodic (Epa) peak potential. Further, CuO nanoparticles grafted β-Ni(OH)2 electrode displays elevated proton diffusion co-efficient (D) and inferior charge transfer resistance. Specifically, CuO embedded β-Ni(OH)2 exhibits 855 F g−1 at 5 Ag-1 and good cycling stability as it maintains more than 90% of its original capacitance even after 3000 cycles. The enhancement may be attributed to the nanosize of CuO and chemical interaction between CuO and β-Ni(OH)2. These results are expected to offer new insight to future researchers who wish to work on the development of novel electrode materials for energy storage applications.