A high-energy aqueous on-chip lithium-ion capacitor based on interdigital 3D carbon microelectrode arrays

There is a growing interest in the development of high energy on-chip capacitive energy storage units for application in microelectronic devices. Lithium-ion capacitor (LIC) typically comprising battery-type and capacitor-type electrodes offer the opportunity for an improved energy density in capacitive energy storage. In this work, an aqueous on-chip LIC was fabricated using carbon microelectromechanical systems (C-MEMS) technique. Oxygen plasma-treated 3D carbon microelectrode arrays served as the capacitor-type electrode in the LIC, while LiFePO4 integrated on the 3D carbon microelectrode arrays was used as the battery-type cathode. Electrochemical performance evaluation shows that the aqueous on-chip LIC can deliver an areal density up to ~5.03 μWh cm−2, which is ~5 times higher than the oxygen plasma-treated symmetric carbon microelectrode-based electrochemical capacitor.