Bimetallic CoGa-LDH Integrated with Co-MOFs-Derived Co@C Nanosheets on Carbon Fiber for Flexible and High-Performance Potassium-Ion Supercapacitors

Abstract

Bimetallic layered double hydroxides (LDHs) have garnered significant attention from researchers due to their distinctive layered structure and compact ion channels for supercapacitor electrodes. Herein, a flower-like hierarchical nanostructure that combines flake-like cobalt gallium layered double hydroxide (CoGa-LDH) with a cobalt-metal–organic framework (Co-MOFs) derived carbon framework (Co@C) on carbon cloth (CoGa-LDH@Co@C) is designed to enhance the properties and functional diversity. The carbon nanolayer derived from calcination of the flake-like zeolite imidazolate framework-67 (ZIF-67) contains abundant Co nanoparticles that serve as nucleation sites for subsequent CoGa-LDH growth. This entails tight integration between the cobalt nanoparticles and CoGa-LDH, resulting in a unique nanoflower-like structure. Owing to the synergistic effects of the composite materials, the durability, conductivity, and surface area of the carbon-nanostructured skeleton, the electrochemical properties of LDH materials are improved significantly. CoGa-LDH@Co@C has exceptional electrochemical characteristics, such as a specific capacitance of 1180 F g –1 at a current of 0.25 mA cm –2 as well as 81.3% capacitance retention when the current is raised to 1 mA cm –2 . The asymmetric potassium-ion supercapacitor (ASC) assembled with CoGa-LDH@Co@C as the anode and activated carbon (AC) as the cathode exhibits an energy density of 45.02 W kg –1, power density of 753.46 W kg –1, and capacity retention of 84.8% after 5,500 cycles. Density functional theory (DFT) calculations reveal a potassium ion adsorption energy of −2.415 eV and density of state (DOS) near the Fermi level. The carbon fiber and MOFs-derived Co@C with enhanced surface electron transport of CoGa-LDH nanoflakes and exceptional cyclic characteristics have large commercial potential.

Topics & Concepts