Ni-Co Double Hydroxides Electrode Materials for Supercapacitor

Abstract

Ni-Co hydroxides with different Ni:Co ratio were synthesized using 2-electrode electrodeposition method. The effects of Ni:Co with different ratio on the hydroxides’ structural and optical properties were investigated using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) method and scanning electron microscopy (SEM). The shifting, changing in shapes and intensity of the corresponding Ni(OH)2 and Co(OH)2 characteristic bands in Ni-Co hydroxides FTIR spectra confirmed that the Ni-Co hydroxides were successfully deposited onto the substrate’s surface. SEM micrographs of Ni-Co hydroxides also showed that all corresponding particles were uniformly distributed and meet the ratio of Ni:Co accordingly. Moreover, XRD patterns confirmed the amorphous nature of nano-sized Ni-Co hydroxides as they were thinly coated. The effects of cobalt on the physical and electrochemical properties of Ni(OH)2 were also investigated. SEM images of Ni-Co hydroxides portrayed that cobalt creates flower-like pores on Ni(OH)2 surface where such pores are important for facile ions diffusion for better electrochemical performance. The Ni-Co hydroxides’ electrochemical properties were also characterized by means of cyclic voltammetry and electrochemical impedance spectroscopy. It was further confirmed in the cyclic voltammetric and impedance spectroscopic studies that Ni:Co=1:3 ratio has the best electrochemical performance.