Zwitter-ion-hydrogel electrolytes with anti-freezing properties for aqueous zinc-ion batteries
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초록
내용
We prepared P(AM-co-VIPS)-VSN composite hydrogel polymer electrolytes containing dual ion salts of ZnSO4 and LiCl, where VIPS is 3-(1-vinyl-3-imidazolio)propanesulfonate) as polymerizable zwitter-ionic monomers, and VSN is vinyl silica nanoparticles as crosslinkers. Their ionic conductivities and mechanical properties were investigated as a function of VIPS contents using various experimental methods, such as EIS, DSC, and DMA. Increasing the VIPS content reduces the crystallinity and melting point at the same time, presumably due to intermolecular interactions between the zwitterion and water. The anti-freezing property is also explored by measuring ionic conductivities as a function of temperature. As a result, as the zwitter-ion content increases, the lowering of the melting point, results in stable ionic conductivity without rapid change in a wide temperature range, and the observed ionic conductivities also show the VTF temperature dependence. This probably indicates a coupling of counterion transport with the amorphous polymer chain motions.