Enhanced Electrochromic Properties of NiO_x Films Through Magnesium Doping Strategy

In order to improve the electrochromic properties of NiO_x films, Mg ions were introduced into NiO_x films using the sol-gel method and the spin-coating method. The introduction of Mg ions leads to the loose structure of the compact NiO_x film, which can provide more channels for the transport of OH^-. In addition, the introduction of Mg ions increases the oxygen vacancies and oxygen interstitial defects in the NiO_x film, which effectively increases the reactive sites and improves the charge transfer efficiency at the interface between the NiO_x film and the electrolyte. The electrochemical results further show that the film electrode (NiO_x-Mg2) has the largest charge storage capacity when the Mg doping concentration is 10%. Compared with the undoped NiO_x film, the doping of Mg improves the transmittance modulation (ΔT) performance of the NiO_x film (ΔT up to 55.8%) and shortens the response time (2.39 s/0.63 s for coloring/bleaching). In general, Mg doping is an effective method for improving the electrochromic properties of NiO_x films.