Flexible Solid-State Supercapacitor Using 2D White Graphene

Abstract

Future inventions and technologies like miniaturize electronics with various functionalities, wearable devices, and bio-implantable sensors have demand for reliable and efficient flexible energy storage devices that can stand mechanical deformation. The flexibility of energy storage devices depends upon configuration, and assembly design to integrate all components into a single flexible unit. In this work, we exhibit a flexible all solid-state supercapacitor which consists of two flexible electrodes, fabricated by modified activated carbon with 2D nanostructure of hexagonal boron nitride (h-BN) ionomers. The electrodes are separated by a nano-engineered electrolyte membrane developed in our previous work. The surface-functionalized h-BN (FhBN) ionomers and nanocomposite electrolyte membranes showed superionic conduction with through- and in-plane ion conductivity of 0.1 S.cm−1 and 0.41 S.cm−1, respectively, which are 14 and 7 times higher than the commercial Nafion ionomer and membrane. The performance of the flexible supercapacitor was validated by cyclic voltammetry, constant current charge/discharge tests, and electrochemical impedance spectroscopy (EIS). These tests are performed in symmetric assembly of supercapacitor and displayed outstanding areal-specific capacitance which was ~2 times higher than that of a supercapacitor made of commercial Nafion electrolyte. Furthermore, we observed that the FhBN-based flexible supercapacitor can conserve its capacitance during the bending test under the mechanical stress, demonstrating its outstanding mechanical flexibility while maintaining its electrochemical performance. With the exceptional mechanical and electrical robustness, the FhBN-based flexible supercapacitors promises an exciting candidate for high-performance flexible energy storage devices in wearable electronics.