Polyanion-induced single zinc-ion gel polymer electrolytes for wide-temperature and interfacial stable zinc-ion hybrid capacitors

Flexible power supplies are urgently needed due to the rapid development of flexible wearable technology. Zinc-ion hybrid capacitors (ZIHCs), which combine the advantages of zinc-ion batteries with high energy density and supercapacitors with high power density, are new and extremely promising future energy storage devices. However, issues such as electrodes dissolution and corrosion, as well as performance degradation of electrolyte in a wide temperature range, can affect the application of ZIHCs. The creation of electrolytes with high adhesion, thermal stability and anti-freeze characteristics can be effective in achieving this objective. Herein, the sulfonic acid groups on 2-acrylamido-2-methylpropanesulfonic acid (AMPS) are utilized as the active sites to design polyanion-induced single zinc-ion gel polymer electrolytes (GPEs). The resulting GPEs of P(AM-AMPS-Zn)/Gelatin (PMPG) display excellent interfacial adhesion and high mechanical strength. Meanwhile, ion migration channels are provided by the ZnCl2-filled PMPG to lessen adverse reactions and extend lifespan. With the combined advantages of PMPG GPE, the assembled ZIHC can provide a high energy density of 140 Wh kg−1 at a high power density of 800 W kg−1 and an excellent cycling durability with the capacity retention of 93.1% and 84.2% at -20 and 60 °C, respectively. More encouragingly, after 5000 charge and discharge cycles of the assembled flexible ZIHC, the electrodes show excellent compatibility with the GPE, suggesting excellent interface stability. Accordingly, this strategy provides new guidance and insights for exploring GPEs that assist ZIHCs in achieving wide temperature resistance and stable interface.