NiTi layered double hydroxide thin films for advanced pseudocapacitor electrodes

Abstract

The performance of pseudocapacitors usually depends largely on careful manipulation of nano-architectures and suitable composition of the active materials. Herein, NiTi layered double hydroxide (LDH) thin films with uniform density were synthesized by a process including two hydrothermal treatment steps and the composition of the hexagonal NiTi-LDH nanosheets was tunable in a relatively wide range. The obtained NiTi-LDH films on nickel foam show a high areal capacitance of 10.37 F cm⁻² at 5 mA cm⁻², and good cycling stability (86% of its initial value was preserved after 1000 charge–discharge cycles), much better than β-Ni(OH)₂ and basic nickel hydroxides carbonate {Ni₂(OH)₂CO₃·4H₂O} films. It is indicated that NH₃·H₂O in the reaction solution played some important roles including enlarging the particle size, focusing the size distribution, and regulating the stacking modes of NiTi-LDH on nickel foam. This work demonstrated the importance of homogeneous dispersion of Ti atoms in layered nanostructures used in supercapacitors.