Laser direct synthesis of Co/CoO modified graphene for high-performance microsupercapacitors

Graphene/CoO nanocomposites have excellent electrochemical performance and are extensively applied to microsupercapacitors (MSCs). Herein, we propose a simple and efficient method for laser direct writing on a graphene oxide/Co(CH3COO)2 precursor to process graphene/Co/CoO nanocomposite interdigital electrodes for MSCs. This work investigates the structural defects, crystal structure, sheet resistance, elemental composition, and bond characteristics of graphene/Co/CoO nanocomposites synthesized at different laser writing speeds. The specific capacitance, power density, and energy density of the prepared MSC based on PVA/H3PO4 electrolyte and graphene/Co/CoO interdigital electrodes reach 420.23 mF cm−2 (48.31 F cm−3), 1.97 mW cm−2 (226.43 mW cm−3), and 58.37 μWh cm−2 (6.71 mWh cm−3), respectively. Moreover, the Coulombic efficiency and capacitance retention rate of the prepared MSC after 10,000 cycles are 97.97% and 86.56%, respectively. The charge storage of the prepared MSC is mainly achieved through diffusion-controlled intercalation reactions. In addition, the prepared MSC shows good mechanical flexibility.