One-step microwave synthesis CoOOH/Co(OH) 2 /CNT nanocomposite as superior electrode material for supercapacitors

CoOOH/Co(OH) 2 /CNT nanocomposite was rapidly prepared through one-step microwave method and characterised by XRD, SEM and XPS. Electrochemical performance was analysed via cyclic voltammetry, chronopotentiometry, cyclic charge-discharge and electrochemical impedance in a 6 M KOH electrolyte. The optimum capacitance of CoOOH/Co(OH) 2 /CNT can achieve 768 F g −1 at 2 A g −1 and could be further increased by 144% (1104 F g −1 ) after 700 cycles. An excellent cycling stability of 77.5% capacitance retention of the highest value (111% capacitance retention of the original value) was achieved after 3000 cycles. An asymmetric supercapacitor device on the basis of the CoOOH/Co(OH) 2 /CNT//AC showed the maximum energy density of 25 Wh kg −1 at a power density of 0.42 kW kg −1 and maintained 85% of the highest specific capacitance value after 20,000 cycles, thereby indicating its immense potential in energy storage devices. Graphical abstract