Flexible micro-supercapacitors with organic gel electrolytes based on screen-printable CuO-ink

In recent years, due to the increase in the demand for miniaturized devices, there has been a massive increase in research to develop flexible, thin and scalable rechargeable energy storage micro-devices. Micro-supercapacitors (MSCs) with high charge-discharge rates and power density are excellent options for small, lightweight, easy-toincorporate, flexible energy storage devices. However, the main problem with modern MSCs is their low energy density and money-intensive, time taking, sophisticated construction methods. Screen-printing is a simple, costeffective and scalable method for fabricating MSCs. Using silver as the current collector, copper oxide as the active material, and gel electrolyte, we present a screen-printable method for constructing flexible MSCs on a PET substrate. The printed MSC was found to give 10.13 mA h cm-3 of volumetric specific capacity and energy density of 10.1 mW h cm-3 with an excellent stability of 99.5% over 3000 cycles and very small capacity degradation even with 120 degrees bending deformation, suggesting outstanding mechanical flexibility and operation stability. Additionally, by connecting numerous MSC devices in series and parallel, the output voltage and current are intelligently adjusted to meet the requirements of varied applications. This study offers an efficient and economical approach to generate MSCs characterized by a substantial energy density. This breakthrough opens avenues for incorporating these MSCs into upcoming wearable technologies.