Controlled Synthesis\nof Flower-like Hierarchical NiCo-Layered\nDouble Hydroxide Integrated with Metal–Organic Framework-Derived\nCo@C for Supercapacitors

Abstract

Layered double hydroxides (LDHs) have come to the foreground\nrecently,\nconsidering their unique layered structure and short ion channels\nwhen they act as electrode materials for supercapacitors (SCs). However,\ndue to their poor rate and cycle performance, they are not highly\nsought after in the market. Therefore, a flower-like hierarchical\nNiCo-LDH@C nanostructure with flake NiCo-LDH anchored on the carbon\nskeleton has emerged here, which is constructed by calcination and\nhydrothermal reaction and applying flake ZIF-67 as a precursor. In\nthis structure, NiCo-LDH grows outward with abundant and homogeneously\ndistributed Co nanoparticles on Co@C as nucleation sites, forming\na hierarchical structure that is combined tightly with the carbon\nskeleton. The flower-like hierarchical nanostructures formed by the\ncomposite of metal–organic frameworks (MOFs) and LDHs have\nsuccessfully enhanced the cycle and rate performance of LDH materials\non the strength of strong structural stability, large specific surface\narea, and unique cooperative effect. The NiCo-LDH@C electrode displays\nsuperb electrochemical performance, with a specific capacitance of\n2210.6 F g^–1 at 1 A g^–1 and 88.8%\ncapacitance retention at 10 A g^–1. Furthermore,\nthe asymmetric supercapacitor (ASC) constructed with NiCo-LDH@C//RGO\nreveals a remarkable energy density of 45.02 W h kg^–1 with a power density of 799.96 W kg^–1. This project\naims to propose a novel avenue to exploit NiCo-LDH electrode materials\nand provide theory and methodological guidance for deriving complex\nstructures from MOF derivatives.