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°. 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.