Ionogel electrolyte with dynamic metal-ligand interactions enabled self-healable supercapacitor with high energy density

Abstract

Flexible semisolid supercapacitors (FSCs) are a kind of essential energy supplies for fast-developed wearable devices. However, the widely reported FSCs use hydrogel electrolytes, dramatically limiting the improvement of the energy density and working potential. Using ionogel electrolytes can solve these problems, but tolerating destruction is still a challenge. Herein, an ionogel electrolyte with good flexibility, high mechanical strength, wide potential window, and fast self-healing feature is designed to assemble the FSCs, solving the above problems simultaneously. The metal-ligand interaction of P(VI-co-VmimBF4) with Zn2+ as the dynamic motif is introduced in the ionogel electrolyte, which not only leads to good flexibility and high mechanical strength of 0.58 MPa, but also endows the fast self-healing ability. Benefitting from the good ionic conductivity of 0.36 mS/cm and wide potential window of 3.2 V of the electrolyte, the assembled FSCs with a covalent organic framework/reduced graphene oxide electrodes achieve a high energy density of 46 Wh/kg. No capacitance deterioration appears for the assembled supercapacitor in bending, and 85% of the original capacitance can be retained for the healed device from two cut pieces. This work provides a way to design a high-performance gel electrolyte for assembling flexible and healable energy storage devices.