A solid-state polymer electrolyte membrane is formed by blending poly(vinylidene fluoride-co-hexafluoropropylene) with the synthesized copolymer of poly(methyl methacrylate-co-1-vinyl-3-butyl-imidazolium bis(trifluoromethanesulfonyl)imide, in which lithium bis(trifluoromethane)sulfonimide molecules are applied as the source of lithium ions. The accordingly formed membrane that contains 14 wt.% of P(MMA-co-VBIm-TFSI), 56 wt.% of PVDF-HFP, and 30 wt.% of LiTFSI manifests the best electrochemical properties, achieving an ionic conductivity of 1.11 × 10⁻⁴ S·cm⁻¹ at 30 °C and 4.26 × 10⁻⁴ S·cm⁻¹ at 80 °C, a Li-ion transference number of 0.36, and a wide electrochemical stability window of 4.7 V (vs. Li/Li⁺). The thus-assembled all-solid-state lithium-ion battery of LiFePO₄/SPE/Li delivers a discharge specific capacity of 148 mAh·g⁻¹ in the initial charge–discharge cycle at 0.1 C under 60 °C. The capacity retention of the cell is 95.2% after 50 cycles at 0.1 C and the Coulombic efficiency remains close to 100% during the cycling process.

Improving the electrocatalytic performance of oxygen evolution reaction (OER) is essential for oxygen-involved electrochemical devices, including water splitting and rechargeable metal–air batteries. In this work, we report that the OER performance of commercial catalysts of IrO₂, Co₃O₄, and Pt-C can be improved by replacing the traditional Nafion^® ionomer with newly synthesized copolymers consisting of protonated imidazolium moieties such as ion conductors and binders in electrodes. Specifically, such an improvement in OER performance for all the tested catalysts is more significant in basic and neutral environments than that under acidic conditions. We anticipate that the results will provide new ideas for the conceptual design of electrodes for oxygen-involved electrochemical devices.