The effect of CuCl 2 nanoparticles on the electrical properties of NiO/MnO 2 -based solid-state electrochemical capacitors

Abstract Electrochemical capacitor with a solid electrolyte composed of Polyvinyl alcohol (PVA) with different concentrations of Copper Chloride (CuCl2) salt, p-type Nickel Oxide (NiO), and n-type Manganese Oxide (MnO2) electrodes prepared as staked thin films deposited on an ITO glass, synthesized by electrodeposition and spin coating techniques. A variety of techniques have been used to characterize the obtained films. The structural properties and surface morphology studied through X-ray diffraction and scanning electron microscopy show a high degree of crystallinity within the electrolyte. FTIR spectra analysis confirms the complex formation of CuCl2-doped PVA. Electrochemical Impendence Spectroscopy (EIS) shows that the addition of CuCl2 enhances the specific capacitance of the electrochemical capacitor with high retention and stability during the repeated process of charge and discharge. Meanwhile, Hall effect measurements and EIS reveal a reverse effect after adding 10, 15, and 20 wt.% CuCl2 to the PVA. Results indicate that the electrolytes possess higher concentrations, higher charge carrier densities, and higher mobility, but lower specific capacitances. The highest specific capacitance obtained is 1.220 F.g-1 for the sample of 10 wt.% CuCl2 with 87.8% capacity retention after performing 350 cycles of charge and discharge. The GCD curves reveal a presence of internal resistance and a combination of capacitor and battery-like behavior.