CoO nanoflowers woven by CNT network for high energy density flexible micro-supercapacitor

Miniaturized energy storage devices have attracted considerable research attention due to their promising applications such as power-on-chip units in various smart electronic devices. In this work, a printable micro-supercapacitor (MSC) device was designed and fabricated wherein a novel three dimensional (3D) nanocomposite consisting of cobalt oxide (CoO) nanoflowers woven with carbon nanotubes (CNTs) networks were used as the active material. The CoO/CNT nanocomposites were synthesized via a high-throughput hydrothermal method. High capacitance of 17.4F/cm³ and energy density of ~3.48mWh/cm³ were achieved for the CoO/CNT MSC at a current density of 0.25A/cm³. The high volumetric energy density is attributed to the widened operation voltage window ranging from 0 to 1.2V. Moreover, the printed CoO/CNT MSCs also showed remarkable cycling stability with ~85% energy density retention after 1700 cycles and high mechanical flexibility which can function well even after bending up to 180°. As a result, the printed CoO/CNT MSC is a possible contender in future energy storage devices for low-cost on-chip power applications.