Fully-Printed, High-Temperature Microsupercapacitor Arrays Enabled by Hexagonal Boron Nitride Ionogel Electrolytes

Abstract: Rising demand for portable electronics and sensors for the Internet of Things continues to drive innovations in the energy storage sector. In order for these devices to run remotely, they must be able to self-sufficiently store their own energy and thus require compact, integrated power sources. Microsupercapacitors are an excellent option due to their exceptionally long cycle lives and their rapid energy delivery and uptake. Additionally, their planar device architecture is easily integrated with all components of a wireless device, allowing for streamlined manufacturing directly on a single substrate. In this work, we demonstrate fully screen-printed, flexible microsupercapacitor arrays via rapid deposition of a high-temperature hexagonal boron nitride (hBN) ionogel electrolyte. The hBN ionogel can be printed onto large-area (~100 cm²) graphene-based microsupercapacitor arrays within seconds, enabling mass-manufacturing. The devices have an areal capacitance of 0.92 mF cm^-2, which rivals the best graphene-based devices to date. In addition, unlike incumbent polymer-based electrolytes, hBN ionogel electrolytes exhibit stable cycling at high temperatures up to 180°C. Elevated operating temperatures result in an increase in power density and enable self-powered, remote devices to be deployed in harsh, high-temperature environments such as underground exploration, aviation, and electric vehicles. This combination of high-performance functionality in harsh conditions and a scalable fabrication strategy significantly expands the application space for microsupercapacitors.