NiTi layered double hydroxide thin films for advanced pseudocapacitor electrodes

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.