Universal route to fabricate facile and flexible micro-supercapacitors with gold-coated silver electrodes

Currently, microsupercapacitors (MSCs) are considered as a promising strategy to solve the energy problems of micro-scale devices. Due to complex fabrication processes and high costs, innovative techniques need to be developed to micro-fabricate and integrate MSCs on chips. In this paper, for the first time, a facile, cost-effective and universal route to fabricate flexible Ag@Au MSCs was proposed. This technique combines a surface ion-exchange (SMIE) process with immersion plating. The commercially-available polyimide film was first treated with SMIE, followed by immersion plating. Via this method, the pristine polyimide is finally turned into gold coated silver electrodes. The whole fabrication is cleanroom-free and environmentally friendly. With this novel patterning and slicing method, a new route for simple and scalable fabrication of MSCs may fulfill a wide variety of applications. As demonstrations, two types of MSCs have also been fabricated. Coated with MWNTs, MSCs were examined in an electrolyte. For sandwiched MSCs, high cycling properties enable MSCs to work at a scan rate up to 10 V s^-1. The maximum phase angle is above -75°. For planar MSCs, the scan rate is easily over 100 V s^-1. The mechanical flexible testing indicated that the SMIE Ag@Au electrodes are sufficiently robust.