Chia-Yun Chou: First Principles-based Atomistic Modeling

Chia-Yun Chou began her doctoral education in the Materials Science & Engineering Program in the Fall semester of 2009. She works in Dr. Hwang’s group working on first principles-based atomistic modeling.

Chia-Yun’s project focuses on computational design of electrode materials for lithium (Li) ion batteries (LIBs). More specifically, she is interested in understanding the lithiation behavior of silicon (Si) based materials, which have recently emerged as a promising candidate for LIB anode because they are abundant and exhibit a much higher Li-storage capacity than the conventional graphite anode. However, several technical hurdles are still waiting to be solved before Si-based anodes can be put to practical use. One of the most critical concerns is its large structural and volumetric changes upon Li insertion and extraction, causing pulverization, loss of electrical contact, and consequently early capacity fading. Considerable efforts have been made to overcome these drawbacks with some success, but most of the remaining challenges cannot be solved easily without a clear understanding of the underlying physics. Chia-Yun’s atomistic modeling focuses on investigating the reaction mechanism, structural evolution and lithiation energetics of Si. Based on the fundamental findings, she is trying to improve the electrochemical performance via chemical and structural modifications. High-throughput materials design will enable thorough and systematic analyses to take advantages of the synergistic effects of controlled oxidation, metal and/or carbonaceous material alloying and nano-architecturing. Chia-Yun’s goal is to develop new fundamental understanding and impetus for the rational design of new and existing Si-based anodes to achieve high energy density, excellent cycling stability and fast charging rate.

Investigating the lithiation behavior of Si-based anode materials based on density functional theory (DFT) calculations with particular attention to the effects of alloying and interfaces/surfaces

Calculated formation energies (Ef) and voltage-composition (V-x) curve for lithiated LixSi-Gr (0 ≤ x ≤ 4.33) in comparison to that of pure Si. While the presence of graphene has a negligible impact on Li incorporation in the Si matrix as the voltage profile is dominated Si lithiation, the facile Li diffusion along the Si/Gr interface could contribute towards high performance anode with fast charge/discharge rate.