Ultrahigh Conductive and Stretchable Eutectogel Electrolyte for High-Voltage Flexible Antifreeze Quasi-solid-state Zinc-Ion Hybrid Supercapacitor

Abstract

The aqueous zinc-ion hybrid supercapacitor (ZHSC) is a prospective energy storage device for next-generation wearable electronics due to its high safety, low cost, and high energy density. However, the preparation of gel electrolytes reported in the literature is complex and time-consuming, which limits their application in practice. Herein, we developed a robust and stretchable eutectogel electrolyte through a one-step gelation process in situ without introducing additional initiators and cross-linkers. The eutectogel electrolyte consists of ternary deep eutectic solvent (DES) based on Zn(ClO4)2, AM(acrylamide), and H2O, among which ClO4– triggers the free-radical polymerization of AM monomer and Zn2+ cross-links the polymer chains. The prepared Zn-PAM-1 gel exhibits a high ionic conductivity of 51.7 mS cm–1. Due to the inhibition of the free water activity in DES, the voltage window of the constructed flexible ZHSC was extended to 0–2.2 V. Moreover, the ZHSC in situ formed manifests a maximum energy density of 117.5 W h kg–1 at a power density of 833.8 W kg–1 and shows admirable cycling stability, retaining 87.6% of its capacitance after 4000 cycles. In addition, the supercapacitor possesses remarkable temperature stability within a range of −20 to 70 °C. Furthermore, the assembled flexible device illustrates favorable bendability from 0° to 180° without scarifying capacitance, displaying great promise as flexible wearable electronic devices. In summary, such a feasible approach provides further insight into the exploration of innovative eutectogel electrolyte systems for assembling quasi-solid-state pliable high energy storing devices.