Effect of electronic structure modulation and layer spacing change of NiAl layered double hydroxide nanoflowers caused by cobalt doping on supercapacitor performance

Layered double hydroxides (LDHs) with high theoretical capacity have broad prospectsin energy storage applications. However, their slow charge transfer kinetics and easy agglomerate hinder their applications in high-performance supercapacitors. Herein, Co2+-doped nickel aluminum layered double hydroxides (NiAl-LDH-Co2+-x, x = 0, 0.3, 0.6, 0.9, 1.2, 1.5) have been designed and prepared by a convenient hydrothermal process. The multicomponent layer structure formed by cobalt doping facilitates sufficient penetration of the electrolyte and accelerates the charge transfer kinetics. Furthermore, the more open layer spacing and electronic interactions induced by Co2+ doping are conducive to accelerating ion de-intercalation, thereby further improving the kinetic behavior of charge storage. Benefiting from the unique microstructure and Co2+ doping effect, the prepared NiAl-LDH-Co2+-0.9 provides a superior specific capacity of 985 C g-1 at 1 A g-1. In addition, the assembled hybrid supercapacitor with the NiAl-LDH-Co2+-0.9 as the positive electrode provides a remarkable energy density of 22.51 Wh kg-1 at a power density of 800 W kg-1 and exhibits an excellent cycle life with 80 % capacity retention after 20,000 cycles. This study demonstrates the great potential of efficient microstructure design and doping strategy in enhancing the charge storage of electrode materials.