Hierarchical Assembly of Nanoparticles Onto Electrochemical Electrodes

Electrochemical electrodes depend on the fast transport of ions to and from their surface to interact with the active materials. A hierarchical pore size distribution on the electrode is known to improve the performance of high-rate applications such as supercapacitors, but work to date has relied on polydisperse nanoparticle building blocks that are mixed with additives such as polymeric binders and carbon black. The polydisperse nanoparticles result in uncontrolled pore structure, and the additives complicate the ionic transport and reactive interface. This project aims to solve these challenges by creating a hierarchically structured porous electrode from monodisperse nanoparticles deposited onto a substrate without the use of additives. In this work, monodisperse copper sulfide nanoparticles were assembled onto a metal substrate through electrophoretic deposition (EPD). A setup for the EPD electrodes was designed and optimized, and the ideal type of nanoparticle, type of ligand, method of ligand attachment, and solution concentration for EPD were determined. The Keyence VK-X260 Laser-Scanning Profilometer was used to measure the film thickness and uniformity. Using this data, the average film density and porosity was calculated for each sample. Preliminary results have shown that porosity can be controlled, that film uniformity decreases at high voltages, and that there exists a crossover in film thickness between applied voltages of 400 V and 650 V.