Journal of Inorganic Materials ›› 2021, Vol. 36 ›› Issue (2): 161-167.DOI: 10.15541/jim20200376

Special Issue: 电致变色材料与器件 功能材料论文精选(2021) 电致变色专栏2021

• TOPLCAL SECTION: Electrochromic Materials and Devices (Contributing Editor: DIAO Xungang, WANG Jinmin) • Previous Articles     Next Articles

High-conductivity Hydrophobic Fumed-SiO2 Composite Gel Electrolyte for High Performance Electrochromic Devices

ZHAO Qi1(), QIAO Ke1, YAO Yongji1, CHEN Zhang1, CHEN Dongchu2(), GAO Yanfeng1()   

  1. 1. School of Materials Science and Engineering, Shanghai University, Shanghai 200444, China
    2. School of Materials Science and Energy Engineering, Foshan University, Foshan 528000, China
  • Received:2020-07-06 Revised:2020-10-29 Published:2021-02-20 Online:2020-11-05
  • Contact: GAO Yanfeng, professor. E-mail: yfgao@shu.edu.cn;
  • About author:ZHAO Qi(1995–), male, PhD candidate. E-mail: zq0911@shu.edu.cn
  • Supported by:
    Foundation item: Ministry of Science and Technology of China(2016YFB0303901-05);Innovation Program of Shanghai Municipal Education Commission(2019-01-07-00-09-E00020);Science and Technology Commission of Shanghai Municipality(18JC1412800);Cheung Kong Scholars Programme of China(T2015136)

Abstract:

Gel electrolytes are chemically stable, nonflammable and easy to encapsulate, however, their moderate ionic conductivity (10-4-10-5S?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.

Key words: gel electrolyte, electrochromic, hydrophobic, SiO2

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