A low-temperature-operated direct fabrication method for all-solid-state flexible micro-supercapacitors

Flexible micro-supercapacitors (MSCs) are promising candidates as miniaturized power sources and energy storage components for next generation wearable electronic devices. Herein, we report a low-temperature-operated ((similar to)80 degrees C) direct fabrication method for the realization of flexible MSCs. To demonstrate the capability of the fabrication method, a flexible MSC based on zinc oxide (ZnO) nanorod/titanium (Ti)/titanium nitride (TiN) core-shell nanostructures and metallic interdigits on a polyethylene terephthalate (PET) substrate was fabricated, with no additional transfer procedure required. The as-produced MSC exhibits increased power (432 W kg(-1)) and energy (0.24 Wh kg(-1)) densities, when compared to those of ZnO nanorod based or ZnO seed layer/Ti/TiN based devices. The capacitance retention is over 98% after 5000 cycles, showing an excellent stability. The flexibility of the MSC is tested by bending the device from 0 degrees to 180 degrees, demonstrating nearly identical electrochemical properties for all bending angles. With such a low temperature environment, the proposed fabrication strategy can be applied to other material networks to further improve the performance of MSCs. This method potentially allows for mass production due to its low fabrication complexity, paving the way for the direction fabrication of on-chip MSCs for flexible and wearable devices.