The realization of high-performance micro-supercapacitors remains a significant challenge, despite the growing demand for miniaturized energy storage devices in applications ranging from wearable electronic gadgets to wireless sensor networks and the Internet of Things. While micro-supercapacitors offer rapid charge and discharge capabilities with a quasi-unlimited lifetime, their energy storage capacity has been a limiting factor. In the 3D-CAP project, we introduce a paradigm shift in micro-supercapacitor design, aiming to enhance energy storage capacities.
As a significant achievement, the project successfully developed micro-supercapacitor electrodes using hydrous ruthenium dioxide (RuO2), a pseudocapacitive material known for its high capacitance. A thin film of ruthenium oxide was conformally deposited onto a high-surface-area 3D current collector, prepared using an innovative dynamic template constructed with hydrogen bubbles. The structural features of these 3D architectures were precisely tailored through advanced processing methodologies, employing deposition methods such as Atomic Layer Deposition (ALD) or electrodeposition for the ruthenium oxide. The electrodes were combined with a groundbreaking solid electrolyte (protic ionogel) capable of operating over an extended cell voltage. Notably, prototypes demonstrate a huge electrode areal capacitance of 24 F/cm2, showcasing a significant leap in performance.