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7756684 
Journal Article 
High-conductivity Hydrophobic Fumed-SiO2 Composite Gel Electrolyte for High Performance Electrochromic Devices 
Zhao Qi; Qiao Ke; Yao Yongji; Chen Zhang; Chen Dongchu; Gao Yanfeng 
2021 
1 
Wuji Cailiao Xuebao
ISSN: 1000-324X 
Science Press 
36 
2 
161-+ 
English 
WOS:000613271900006 
Gel electrolytes are chemically stable, nonflammable and easy to encapsulate, however, their moderate ionic conductivity (10-4-10-5 S·cm-1) hinders their further development for the usage in electrochromic devices (ECDs). Here, we developed a highly conductive hydrophobic SiO2/PMMA/PC/LiClO4 gel polymer electrolyte (H-SiO2 GPE). Electrochemical behaviors of ECDs were characterized by electrochemical impedance spectroscope (EIS), cyclic voltammetry (CV) and chronoamperometry (CA). Systematic analyses show that the ionic conductivity of the H-SiO2 GPE can reach 5.14 mS∙cm-1 (at 25 ℃) by introducing only 0.5wt% hydrophobic fumed SiO2. This increase is due to the good compatibility and hydrophobic-hydrophobic attractions between SiO2 additive and organic electrolyte, which promotes the dissociation of lithium perchlorate. Additionally, the viscosity as a function of shear rate for GPE with various fumed silica contents shows the behavior of shear thinning, which indicates the formation of a three-dimensional network structure. This structure provides ion transport channels, leading to a clearly improved switching speed for ECDs assembled with hydrophobic SiO2 GPEs (tbleaching=4 vs 8 s and tcoloring=14 vs 16 s). Similarly, the investigation of hydrophobic fumed SiO2 in liquid electrolyte is demonstrated that the ionic conductivity of LiClO4/PC liquid electrolyte without and with hydrophobic fumed SiO2 increases from 6.94 to 7.58 mS∙cm-1, respectively. Therefore, hydrophobic fumed SiO2 as a filler has a positive effect on electrolytes, and the proposal of the H-SiO2 GPE provides a new idea for offsetting the trade-off between a high ionic conductivity and easy leakage when applied in ECDs. © 2021, Science Press. All right reserved. 
gel electrolyte; electrochromic; hydrophobic; SiO2