Design, synthesis and characterization of polysiloxane and polyetherdiamine based comb-shaped hybrid solid polymer electrolytes for applications in electrochemical devices

In this study, polysiloxane and polyetherdiamine based comb-shaped solid polymer electrolytes (SPEs) are developed by hydrosilylation and sol-gel reactions of polymethylhydrosiloxane, allyltriethoxysilane, bis(2-aminopropyl) polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol and (3-glycidoxypropyl)trimethoxysilane followed by LiClO₄ doping. The absence of residual Si‒H functionality in FTIR and ²⁹Si CPMAS NMR spectra confirms the completion of hydrosilylation reaction. The formation of comb-shaped SPEs with silicate backbones is confirmed by ¹³C and ²⁹Si solid-state NMR spectroscopy. The maximum ionic conductivity value of 5.8 × 10⁻⁴ S cm⁻¹ is obtained for the SPE with [O]/[Li] ratio of 16 at 80 °C with electrochemical stability window reaching up to 4.8 V. The fabricated electrochromic device with the hybrid SPE of [O]/[Li] = 16 demonstrates good electrochromic contrast and optical density change values of 49.3% and 0.39, respectively, at wavelength of 550 nm. The results show that the present comb-shaped SPEs have potential to be used in various electrochemical devices.