Improvement in electrochromic stability of electrodeposited nickel hydroxide thin film

The electrochromic nickel hydroxide thin film was anodically deposited from an aqueous solution. The effect of solution temperature, postheat-treatment temperature, and addition of cadmium on the electrochromic behavior (color/bleach durability cycle, response time, and coloration efficiency of the nickel hydroxide films in NaOH) were investigated. A significant increase in the color/bleach durability cycle from 500 (for the as-deposited film) to more than 5000 cycles (for the heat-treated film) was observed. The addition of cadmium increased the utilization of the active materials. It was found that the coloration efficiency was 40 cm(2)/C and coloration and bleaching response time were 20 to 30 s and 8 to 10 s, respectively. The change in the electrochromic properties with heat-treatment temperature is discussed based on the physical and electrochemical analysis.