NiAl layered double hydroxides with enhanced interlayer spacing via ion-exchange as ultra-high performance supercapacitors electrode materials

Supercapacitors play a significant role in energy storage systems, and much efforts have been devoted to the development of electrode materials with excellent electrochemical properties. Here, a flower-like spherical NiAl layered double hydroxide with chloride ions as interlayer anions (NiAl-Cl LDH) is successfully prepared via a two-step method, which exhibits a prominent specific capacity of 2512 F/g (379.7 mAh/g) at a current density of 1 A/g is much higher than that of the precursor. NiAl-Cl LDH presents widen interlayer spacing that can promote transport kinetics of OH- ion and electrons between the brucite-like layers and improve the utilization of active materials, resulting in superior rate capability (the specific capacitance at 20 A/g is 77.5% of that at 1A/g). Meanwhile, the interspace between the interlaced hierarchical structure is beneficial to buffer the volume change, ensuring the structural stability of NiAl-Cl LDH during the redox reaction. Furthermore, the assembled NiAl-Cl LDH//AC asymmetric supercapacitor exhibits a high energy density of 53.9 Wh/kg corresponding to a power density of 1540 W/kg, and remains 94.1% of initial specific capacitance after 1000 cycles examinations.

Automated summary

A flower-like spherical NiAl-Cl LDH with widened interlayer spacing is successfully prepared. It exhibits excellent electrochemical and rate performance, with the widened interlayer spacing promoting the utilization of active materials and ensuring structural stability. The assembled asymmetric supercapacitor demonstrates high energy density and long cycle life.