2D nanochannels boosting ionic conductivity of zinc-ion “water-in-salt” electrolyte for wearable micro-supercapacitor

Abstract

Energy storage units on a microscale are critical for the miniaturization of portable and highly integrated electronic devices. Rechargeable micro-supercapacitors with high power density and long cycle life are promising candidates for this purpose. In this study, a wearable nanoconfined “water-in-salt” electrolyte-based micro-supercapacitor (NWMS) is designed by confining ZnCl2-based “water-in-salt” into the nanoslits of graphene oxide membrane, which provides a wide electrochemical stability window, high ionic conductivity, and high safety. The NWMS possesses a high reversible capacitance of 75 mF/cm2, superior cycling stability with 100% capacitance retention and 97% coulombic efficiency within 10,000 cycles. Moreover, the NWMS can be easily scaled up by connecting multiple devices in parallel or series, and it is capable of powering microelectronic devices such as a timer, LED lights, and a game console. This high-performance NWMS holds great promise as an energy storage unit for next-generation wearable electronics.