Hydrocarbon-Derived Prenetworked Carbon Nano-Onions for Wearable and Flexible Printed Microsupercapacitors

Carbon nanomaterials have emerged as a promising solution for printed electronics, especially in microsupercapacitor (MSC) applications. This study examines the significance and compatibility of a newly developed industrial carbon nanomaterial derived from hydrocarbon streams via a scalable, catalyst-free process in a proprietary reactor. The carbon nanomaterials exhibit a unique morphology, characterized by nanoscale building blocks forming microscale networks, enhancing printed flexible electronics' efficiency. Here, we utilize carbon nano-onions (CNOs) as an electrode material for MSCs. In addition to CNOs' unique networked structure, high electrical conductivity, and large surface area make CNOs ideal for next-generation printed MSCs. The printed MSCs operate efficiently without metal current collectors, indicating that the printed electrodes with hydrocarbon-derived CNOs have sufficient conductivity comparable to that of metal-based current collectors. The printed MSCs demonstrated an excellent specific capacitance of 3.2 mF/cm2, outperforming many graphene-based MSCs. Additionally, these MSCs exhibited outstanding cycling stability, retaining 97% of their capacity after 10,000 galvanostatic charge-discharge cycles, and superior capacitance retention of 91% at a bending angle of 180 degrees. These results indicate that the networked structure of CNOs maintains capacitance at various bending angles, confirming their high compatibility with flexible printed electronics. The integration of hydrocarbon-derived CNOs into printed electronics not only facilitates the development of lightweight, flexible, and cost-effective devices but also opens the door to innovative printed electronic applications.