Ni Oxyhydroxide Thin Films Prepared by Reactive Sputtering Using O_2 + H_2O Mixed Gas

摘要

In this study, we have examined the preparation of thin films of Ni oxyhydroxide, which are used for batteries, supercapacitors, and electrochromic devices, by reactive sputtering. Transmittance and resistivity were found to decrease with the incorporation of H_2O into the sputtering gas. This indicates that the valence state of Ni atoms in the film changes from Ni~(2+) to Ni~(3+). Peaks due to Ni-OH and hydrogen bonded OH were observed by Fourier transform IR (FTIR) spectroscopy of the films sputtered in O_2 + H_2O mixed gas. From the obtained results, it is confirmed that Ni oxyhydroxide films are formed by reactive sputtering in O_2 + H_2O mixed gas. An electrochromic coloration efficiency of 29cm~2/C was obtained in 1 M KOH aqueous electrolyte solution for the Ni oxyhydroxide films.