Nanorod-based smart windows with solid-gel electrolyte: An integrated electrochromic and pseudocapacitive technology for energy-saving and conversion

We fabricated two emerging nanorod-based smart windows with WO₃ and NiO nanorods grown on the ITO/glass and ITO/muscovite mica (MM) substrates, respectively. The WO₃/ITO/glass and WO₃/ITO/MM substrates are excellent working electrodes, while the NiO/ITO/glass and NiO/ITO/MM substrates are exceptional counter electrodes. The nanorod-based WO₃/Li⁺_(s)/NiO@glass smart window consists of a WO₃/ITO/glass working electrode, a NiO/ITO/glass counter electrode, and a solid-gel LiClO₄ electrolyte (labeled as Li⁺_(s)), respectively. The other nanorod-based WO₃/Li⁺_(s)/NiO@MM is comprised of a WO₃/ITO/MM working electrode, a NiO/ITO/MM counter electrode, and a solid-gel LiClO₄ electrolyte, respectively. Both the nanorod-based WO₃/Li⁺_(s)/NiO@glass and WO₃/Li⁺_(s)/NiO@MM smart windows have brilliant dual-band (red and near-infrared lights) electrochromic behaviors, such as large transmittance differences (ΔT), fast response times (bleaching time, t_b, and coloration time, t_c) at red (680 nm) and near infrared (1000 nm) lights and great electrochromic retention (4,000 cycles), and outstanding pseudocapacitive performances like good specific capacitances of ~18.4 F/g and ~7.6 F/g, intensive power densities of ~1779 W/kg and ~2100 W/kg with corresponding energy densities of ~5.4 Wh/kg and ~2.2 Wh/kg, enormous pseudocapacitive retention (10,000 cycles), and so on. Therefore, the brilliant dual-band electrochromic behaviors and outstanding pseudocapacitive performances make the nanorod-based WO₃/Li⁺_(s)/NiO@glass and WO₃/Li⁺_(s)/NiO@MM smart windows tremendous for use in multifunctional energy-saving-conversion devices.