Thermodynamics and Kinetics of Ion Transport in Batteries and Microelectronics

Abstract: Energy storage and semiconductor microelectronics are two critical strategic technologies for the United States. In this talk, I will present our recent research on the thermodynamics and kinetics of ions in these technologies. Metal oxides fabricated using low-temperature processes are widely used in microelectronic devices including resistive memory, thin-film transistors, and ferroelectrics. Oxygen diffusion within these solid metal oxides plays critical roles in the functionality and reliability of such devices. In our study of tantalum oxides used in resistive memory, we show that oxygen diffusion kinetics are not governed by ideal Fickian diffusion; instead, they are governed by nonideal thermodynamic interactions including phase separation and spinodal decomposition, and can be described with a regular solution model. This phase separation not only enables information retention for over 10 years under typical computing environments but can also be used to engineer nonvolatile memory under extreme temperatures exceeding 500C.  

Next, we investigate lithium transport in battery materials by assembling individual battery particles onto microelectrode array, a platform adapted from the field of neuroscience. By measuring lithium diffusion and reaction rates in individual particles, we show that particle cracking, which was long believed to be detrimental, is essential for the fast charge and discharge of battery particles. Moreover, attempts to eliminate cracks would substantially hinder fast charge and discharge. Such studies show the importance of ion transport in current and future technologies for energy, microelectronics, and beyond.

Bio: Yiyang Li is an Assistant Professor of Materials Science and Engineering at the University of Michigan since 2020. His group studies ion transport in materials for energy storage and microelectronics. He received his PhD in materials science and engineering from Stanford University in 2016, and was a Harry Truman Postdoctoral Fellow at Sandia National Laboratories from 2017-20. Yiyang Li has received the Intel Rising Star and the DARPA Young Faculty Award.