Cu-Doped Layered Double Hydroxide Constructs the Performance-Enhanced Supercapacitor Via Band Gap Reduction and Defect Triggering

Abstract

Layered double hydroxides (LDHs) are regarded as the excellent electrode materials for supercapacitors because of their high theoretical capacitance and abundance. However, the poor conductivity and limited reaction kinetics of LDHs restrict their practical application severely. Herein, Cu is chosen from groups VIII/IB/IIB as dopants for Co-based LDH (CuCo-LDH). The designed metal-organic framework-derived hierarchical CuCo-LDH hollow nanoarrays integrated on nickel foam are fabricated via a facile in situ hydrolysis method. Consequently, the introduction of copper significantly enhances the local electron density of cobalt-based hydroxide, which enhances electronic conductivity and facilitates the charge transfer. Copper doping induces lattice defects, providing more active sites to improve the charge storage capacity. As a result, our CuCo-LDH electrode delivers a package-enhanced pseudocapacitive performance. The as-fabricated asymmetric supercapacitor CuCo-LDH//AC provides a relatively high energy density of 22 W h kg-1 and a remarkable cycling stability (91.3% after 10,000 cycles) towards practical applications of supercapacitors.