A Quasi‐Solid Electrolytes Based on Crystalline Phase Modulation of PVDF‐HFP for High‐Performance Electrochromic Devices
Fan Lan, Run Li, Yaqi Zhang, Yilin Ding, Xueke Wu, Yunrui Li, Yanlong Zhao, Zhehao Ma, Aike Xi, Siming Zhao, Ya Huang, Jiaqi Xu, Zhuojing Zhao, Chunya Wang, Chunming Xu, Rufan Zhang
Abstract
Abstract A rational design of ion‐conducting layers is crucial to the performance of all‐solid‐state electrochromic devices (ECDs). However, the ECDs based on solid‐state electrolytes remain a significant challenge because of the slow ion diffusion. Herein, a quasi‐solid‐state electrolyte based on high‐polarity nanofiber membranes is prepared by electrospinning, in which ionic liquid (ILs) is combined with a poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) matrix. The obtained PVDF‐HFP/ILs gel polymer electrolytes (GPEs) showed an extremely high visible‐range transmittance (over 95%), a high ionic conductivity (5.67 mS cm −1 at 25 °C), a wide electrochemical window (4.40 V), making it an outstanding candidate to be used in ECDs as an ion‐conducting layer. The ECDs based on Prussian blue (PB) and tungsten oxide (WO 3 ) electrodes achieved a reversible color transition from transparent to dark blue, exhibiting an excellent transmittance modulation (ΔT = 90.74%), a good coloration efficiency (CE = 184.16 cm 2 C −1 ), and a good cycling stability (retained 90.78% after 1500 cycles). Additionally, the ECDs also exhibited a steady energy‐storage behavior between −20 and 50 °C and a slow self‐discharge rate, offering a viable approach to achieving high‐performance ECDs.