Multilayered core-shell NiCo-layered double hydroxide@NiCo2O4 composite electrode for high-performance supercapacitor

The present work reports the fabrication of multilayered hierarchical core-shell NiCo-layered double hydroxide@NiCo2O4 thin film on stainless steel mesh substrate (NC-LDH@NCO/SSM) as an electrode by a successive two-step hydrothermal method for supercapacitor application. The NC-LDH@NCO/SSM electrode with urchin-like NiCo2O4 (NCO) nanowires as a core backbone and NiCo-LDH (NC-LDH) nanosheets as a shell structure exhibit a specific surface area of 110.90 m2 g-1 which is more than NCO (77.66 m2 g-1) and NC-LDH (34.93 m2 g-1). The NC-LDH@NCO/SSM composite electrode delivered an enhanced specific capacitance of 2222.27 F g-1 at a current density of 10 mA cm-2, and it demonstrated a specific capacitance retention of 94% after 2500 cycles at a higher current density of 50 mA cm-2. Further, the asymmetric device was assembled using NC-LDH@NCO/SSM (positive electrode), activated carbon (AC/SSM) (negative electrode), and PVA/KOH gel electrolyte. The device exhibited an energy density of 47.5 Wh kg-1 at a power density of 1094 W kg-1 with 97.6% capacitance retention even after 3500 cycles at a current density of 30 mA cm-2. These findings signify the potential of NC-LDH@NCO/SSM core-shell structured electrodes in energy storage systems and are expected to pave the way for further development in the field.