CuCo₂O₄ Nanorods Coated with CuO Nanoneedles for Supercapacitor Applications

Herein, we report the chemical synthesis of a core–shell nanoarchitecture comprising CuCo2O4@CuO (CCO@CuO) on a flexible stainless steel mesh substrate (FSSM) with CuCo2O4 (core) and CuO (shell) by a simple, cost-efficient, additive-free hydrothermal deposition method, followed by successive ionic layer adsorption and reaction method for fabricating a flexible electrode for an asymmetric supercapacitor (ASC). The nanocomposite of CCO@CuO revealed a high surface area of 98.33 m2 g–1 and the electrode delivered a high specific capacitance of 713 F g–1 at a high current density of 11 mA cm–2, which was noted to be higher than those of the individual constituent CuO (436 F g–1) and CuCo2O4 (443 F g–1) metal oxide electrodes. The CCO@CuO electrode demonstrated remarkable cycling stability (∼90% capacitance retention after 5000 charge–discharge cycles at 15 mA cm–2). The ASC device CCO@CuO//rGO (reduced graphene oxide) delivered a maximum energy density of 37.43 Wh kg–1 at a power density of 250 W kg–1. The device revealed 83% capacitance retention after 4000 cycles. These results indicate that the CCO@CuO/FSSM electrode is a promising functional material for energy storage devices.