基于高电导率的疏水气相SiO_(2)复合凝胶电解质的高性能电致变色器件

High-conductivity Hydrophobic Fumed-SiO_(2) Composite Gel Electrolyte for High Performance Electrochromic Devices

凝胶电解质具有化学稳定、难燃和易于封装等特点,其低离子电导率(10^(–4)~10^(–5) S·cm^(-1))阻碍了电致变色器件(ECDs)凝胶电解质的进一步发展。本研究制备了一种高电导率的疏水SiO_(2)/PMMA/PC/LiClO_(4)凝胶聚合物电解质(H-SiO2 GPEs),并用电化学阻抗谱(EIS)、循环伏安法(CV)和计时电流法(CA)分析了ECDs的电化学行为。实验结果表明,仅引入0.5wt%的疏水性气相SiO_(2),即可使H-SiO_(2) GPEs的离子电导率达到5.14 mS·cm^(–1)(25℃时)。离子电导率的增加归因于SiO_(2)添加物和有机电解质之间良好的相容性和疏水–疏水吸引力促进了高氯酸锂的离解。同时,不同气相二氧化硅含量的GPEs的粘度与剪切速率的关系表现出剪切稀化行为,这表明研究体系形成了三维网状结构。该结构为离子提供了传输通道,进而提高了基于H-SiO_(2) GPEs电致变色器件的响应速度(tbleaching=4 vs 8 s和tcoloring=14 vs 16 s)。同样,通过探究添加疏水性气相SiO_(2)对液态电解液的影响表明:复合疏水性气相SiO2使得LiClO_(4)/PC液态电解液的离子电导率由原来的6.94 mS·cm^(-1)增大到7.58 mS·cm^(-1)。疏水性气相SiO_(2)作为填料对电解质的离子电导率具有一定的积极作用,H-SiO_(2) GPEs的研究为解决ECDs高离子电导率和易泄漏之间的矛盾提供了新思路。

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 SiO_(2)/PMMA/PC/LiClO_(4) gel polymer electrolyte(H-SiO_(2) 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-SiO_(2) 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 SiO_(2) 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 SiO_(2) in liquid electrolyte is demonstrated that the ionic conductivity of LiClO_(4)/PC liquid electrolyte without and with hydrophobic fumed SiO_(2) increases from 6.94 to 7.58 mS·cm^(-1),respectively.Therefore,hydrophobic fumed SiO_(2) as a filler has a positive effect on electrolytes,and the proposal of the H-SiO_(2) GPE provides a new idea for offsetting the trade-off between a high ionic conductivity and easy leakage when applied in ECDs.