In situ silica-bridged nanophase hybrid ionogel polymer electrolytes for high-energy flexible supercapacitors

초록

Supercapacitors are promising high-power energy storage devices, but are often limited by low energy density and mechanical instability. Here, we present an epoxy-silica hybrid ionogel polymer electrolyte (HIGPE) synthesized via an in situ sol-gel reaction combined with thermal polymerization. Two epoxy monomers, one rigid and one flexible, were combined with silica precursors and subjected to in situ sol-gel processing to generate nanophase-separated domains. The subsequent thermal curing in an ionic liquid medium produced a free-standing HIGPE featuring chemically bonded SiO2 nanoparticles, which uniformly disperse and modulate polymerization-induced phase separation (PIPS), yielding a finely structured nanoscale network. At room temperature, HIGPE exhibits an ionic conductivity of 1.5 x 10-3 S/cm and a mechanical modulus of 0.9 MPa. When assembled into symmetric activated carbon supercapacitors, HIGPE enables a specific capacitance of 145 F/g at 0.2 A/g, which is 2.5 times higher than that of SiO2-free IGPE, and achieves an energy density of 45 Wh/kg. Moreover, capacity retention remains above 80% after 5000 cycles, and bending tests confirm excellent flexibility with negligible performance loss. These results demonstrate that controlling PIPS through in situ nanoparticle incorporation produces a mechanically robust, high-conductivity electrolyte, addressing key shortcomings of conventional supercapacitors and paving the way for next-generation flexible energy storage.Graphical abstractA new hybrid epoxy-silica ionogel polymer electrolyte (HIGPE) was developed to address the challenges of low energy density and mechanical instability in supercapacitors. Created through an in situ sol-gel process followed by thermal polymerization, HIGPE features silica particles that form a nanoscale network. This structure not only enhances ionic conductivity but also maintains mechanical flexibility. HIGPE-based supercapacitors show great promise for advancing energy storage technology.

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