Ag nanoparticles-decorated CoAl-layered double hydroxide flower-like hollow microspheres for enhanced energy storage performance

Abstract

Layered double hydroxides (LDHs) have been considered as one class of promising active electrode materials for supercapacitors due to their tunable composition and chemical versatility. Nonetheless, the poor electrical conductivity hinders their further practical applications in supercapacitors. Herein, CoAl LDH flower-like hollow microspheres are decorated with Ag nanoparticles by a facile one-step solvothermal reaction, followed by chemical bath deposition reaction. Experimental results and theoretical calculations indicate that decorating Ag nanoparticles onto CoAl LDH not only reduces the energy band gap and enhances their electrical conductivity, but also promotes fast diffusion kinetics of electrolyte ions and electrochemical reaction activity. Consequently, the prepared Ag/CoAl LDH electrode demonstrates improved specific capacities of 1214 (825) C g−1 at 3 (30) A g−1 and 91% capacity retention over 10,000 cycles at 10 A g−1 compared to the pristine CoAl LDH electrode. Moreover, using Ag/CoAl LDH and N-doped carbon nanotubes as the positive and negative electrodes, respectively, the assembled hybrid capacitor device delivers an energy density of 61.2 Wh kg−1 at a power density of 800 W kg−1. This work may showcase a great promise of engineering conductive nanoparticles-decorated LDHs-based active materials towards high-performance supercapacitors.