Thermal stability of ionic liquid-loaded electrospun poly(vinylidene fluoride) membranes and its influences on performance of electrochromic devices

► SCCO2-treated electrospun PVDF-HFP membranes are used as the ionic-liquid (IL) host. ► We examined the effects of thermal annealing on the IL/PVDF-HFP electrospun membrane. ► The membrane retains good transparency and high ionic conductivity after annealing. ► Electrochromic device with the annealed membrane shows no performance deterioration. ► Such electrolyte has the potential for the devices used in harsh environments.