UCLA

Electrodeposition of Zn and ZnO have attracted attention from both academia and industry because of their broad applications in energy storage and optoelectronic devices. The goal of this dissertation work is to develop fundamental understanding of the growth kinetics of Zn and ZnO during electrodeposition.

In situ characterization techniques are employed for the investigation of Zn and ZnO electrodeposition kinetics. First, Zn dendrite formation and oscillatory growth were analyzed using in situ optical microscopy. Second, the morphological evolutions of Zn and ZnO during electrodeposition were studied with in situ atomic force microscopy. Finally, the phases involved in and the mechanism underlying the ZnO electrodeposition were revealed by in situ wide-angle X-ray scattering and in situ electrochemical quartz crystal microbalance measurements.

In this dissertation, I investigated the morphological evolution of Zn dendrites during electrodeposition and developed fundamental insights to the growth behavior, which then set the foundation for the study of Zn growth kinetics under oscillatory conditions. A growth model for spontaneous oscillatory Zn dendrite growth was suggested based on the considerations of growth dynamics and structural characteristics. The understanding of Zn growth kinetics was then achieved by direct monitoring the nucleation and growth on both poly- and single-crystalline substrates. In addition, a pH-dependent morphological evolution was observed during Zn growth, triggering the studies of ZnO electrodeposition, whereby ZnO formation was demonstrated to be an electrochemical induced chemical precipitation process. In situ observations of ZnO nucleation and growth allowed me to understand the electrochemical reaction pathways leading to the formation of ZnO during electrodeposition.