One-step synthesis of porous nickel-aluminum layered double hydroxide with oxygen defects for high-performance supercapacitor electrode

Layered double hydroxide (LDH) has been regarded as one of ideal electrode for supercapacitors due to layered structure, multiple redox active centers, and synergistic effects between metal ions. However, low capacitance and poor cycling stability greatly limit their large-scale application. Herein, nickel-aluminum layered double hydroxide (NiAl-LDH) onto nickel foam has been prepared by a simple one-step hydrothermal method, with the charge storage capability controlled by using different reactant concentration. It is found that the reactant concentration can regulate the morphology, crystallinity and loading density of NiAl-LDH. The optimized NiAl-LDH (Ni1Al1-LDH) shows a porous nanosheet structure with oxygen defects, which tightly covers on the nickel foam to facilitate ion and electron transfers, improving the redox activity of Ni ions and thus energy storage. As a supercapacitor electrode, the Ni1Al1-LDH achieves a specific capacitance of 1958.1 F/g at a current density of 1 A/g. The capacitance retention rate can reach as high as 108.7% up to 1000 cycles of continuous charge and discharge at a scan rate of 100 mV/s.