High-performance nickel-based flexible supercapacitors via in-situ electrodeposition and cyclic voltammetry oxidation on carbon cloth

To tackle the rigidity and safety issues of traditional batteries in flexible wearables, this study proposes an innovative approach. It combines electrodeposition and cyclic voltammetry (CVP) oxidation to deposit nickel on carbon cloth, followed by in-situ oxidation, creating a composite electrode (OCCEN). By optimizing electrodeposition (2V, 20 min) and CVP parameters (−1.6 V–1.6 V, 1.0 mol/L KOH, 50 cycles), a porous nickel oxide layer forms on the carbon cloth. This electrode shows a high area-specific capacitance of 1736.2 mF/cm 2 at 1 mA/cm 2 . When assembled into a supercapacitor, it has excellent rate performance, retaining 71 % of capacitance at 15 mA/cm 2 , outperforming typical carbon cloth-based and most flexible electrodes. Material characterization reveals that CVP oxidation turns the surface nickel layer into porous active NiO, significantly boosting pseudocapacitance. The process also maintains carbon cloth flexibility and solves the poor interfacial adhesion problem in traditional methods, showing great mechanical stability (98.46 % mass retention after high-power ultrasonication). As a result, the assembled flexible supercapacitor operates stably under bending, retaining nearly 100 % capacitance even at 180°. This study offers a scalable, cost-effective preparation strategy for efficient flexible energy storage devices.