| dc.description.abstract | This thesis investigates the effect of different sputter deposition parameters on the diameter, morphology, and distribution of nickel nanoparticles, and the consequently synthesized interconnected cross-linked carbon nanotubes (iCL-CNTs) for high energy density supercapacitors. Ni is a metal catalyst with excellent properties for CNT synthesis, which is sputter-deposited on a microstructured Al foil substrate (featuring large surface area) acting as electrode with CNTs grown on it for supercapacitor application. Since the morphology of Ni nanoparticles has a strong influence on the diameter of the resulting carbon nanotubes, therefore an approach is devised to study this effect and present optimized deposition parameters and conditions for Ni. The supercapacitors suffer from the problem of low energy density, and the thesis presents an approach to improve it.
Ni thin films of 10, 100 and 250 nm are sputter-deposited on a microstructured Al foil at applied powers of 25, 100, and 400 W (corresponding sputtering rates: 0.14, 0.77, and 3.2 Å/s) to study the influence of these parameters on the CNT growth. The CNTs were grown using an optimized gas ratio and then their mass loading was calculated. Ni nanoparticles of ~7.76 nm were characterized and CNTs measuring between 30 and 160 nm were grown. The effect of the applied power on the penetration depth of Ni into the microstructured Al substrate was also studied, and higher powers (sputtering rates) and thicker films were found to provide a larger Ni concentration or penetration depth.
At the same time, faster sputtering rates and thicker Ni films were found to increase the Ni nanoparticle/cluster size. The coalescence property of nanoparticles and its relationship with heating were studied. CNT mass loading of ~23.7 mg/cm2 was achieved which can then be extrapolated to comment on improvement in the energy density of a supercapacitor. | |
