A method to achieve full incorporation of PMMA-based gel electrolyte in fiber-structured PVB for solid-state electrochromic device fabrication

Abstract Based on the modified PMMA-PEG polymer loading with LiClO4/PC, a flexible, transparent free-standing quasi-solid polymer electrolyte (QSPE) was prepared. The ionic conductivity of QSPE membrane was carefully studied through electrochemical impedance spectroscopy. It was found that the QSPE membrane with 30 wt% 0.1 M LiClO4/PC displays a high conductivity (5.23 × 10−6 S/cm at room temperature), good transparency (over 70% in visible ranges) and a certain of mechanical strength. Furthermore, a novel fiber-network structured membrane of polyvinyl butyral (PVB) was designed and prepared via electro-spinning, which would allow the liquid QSPE fully complex with PVB polymer structurally. A great improvement for interfacial adhesion between the gel electrolyte and electrodes was achieved, the tensile strength increased to 0.31 MPa (QSPE-PVB) from 0.05 MPa (QSPE), while remaining a good transparency. Meanwhile, the ionic conductivity of the composite electrolyte reached a level of 10−5 S/cm. Using the gel composite electrolyte (QSPE-PVB membrane), all-solid-state electrochromic device (ECD) was assembled with a configuration of PProDot-Me2/QSPE-PVB/V2O5. This novel electrolyte could guarantee that PProDot-Me2 was able to switch its color from bleached state (Tb= 71.4% at 580 nm) to colored state (Tc= 23.7% at 580 nm) within 6 s under the applied potential of ±1.5 V. The as-fabricated QSPE-PVB ECD also exhibited an impressive stability of almost no transmittance attenuation. This new all-solid ECDs offered a certain operational advantage in real-world applications.