Ph.D. Thesis Proposal
Jaechan Pyo
(Faculty advisor: Professor Claudio Di Leo)
"Continuum Multiphysics Modeling of Deformation, Damage, and Microstructural Evolution in Energy Storage Materials"
Tuesday, September 22
12:00 - 2:00 p.m.
Weber 200
Abstract:
The growing demand for energy storage spans a broad range of applications with fundamentally different
performance requirements. In transportation, the continued electrification of vehicles motivates battery
technologies with high specific energy density, including all-solid-state batteries employing high-capacity
electrode materials such as silicon. In stationary applications, increasing energy demand and the need for
efficient storage and utilization of thermal energy motivate technologies such as thermochemical energy stor-
age, where salt-hydrate materials offer high volumetric energy density and long-duration storage with way
economical cost compared with Li-ion batteries. Despite their distinct energy-storage mechanisms, these
material systems share an important mechanics challenge. Many materials capable of storing large amounts
of energy undergo substantial changes in chemical composition during operation, which are accompanied by
correspondingly large deformations. The resulting stresses, damage, and evolution of the internal microstruc-
ture can alter transport pathways and ultimately limit the cycling stability and realizable energy-storage
performance of the material.
Large deformations in energy-storage materials give rise to coupled physical phenomena that influence
both mechanical integrity and transport behavior. In electrochemical batteries, for example, heterogeneous
lithiation can produce non-uniform strain and stress fields, which in turn affect electrochemical reaction
and transport through changes in local chemical potential and ion-transport pathways. In thermochemi-
cal energy storage, hydration and dehydration involve coupled heat and mass transport through a porous
microstructure whose evolving porosity and interparticle contact determine the effective thermal conductiv-
ity of the material. These examples demonstrate that the macroscopic performance of high-energy-density
storage materials cannot be understood solely from their intrinsic material properties. Instead, predictive
continuum models must account for the evolution of internal microstructure, stress, and damage and their
coupling with chemical and thermal transport.
In this proposal, two different energy-storage material systems are investigated, namely amorphous silicon
(a-Si) anodes for all-solid-state batteries (ASSBs) and SrBr2 hydrates for thermochemical energy storage.
A key unresolved challenge in these materials is predicting the evolution of microstructure during elec-
trochemical and thermochemical cycling. To address this challenge, the present frameworks will be extended
to incorporate evolving mechanical and thermo-chemical contact between particles, allowing new contacts
to form and transport pathways to develop as the material undergoes large reaction-induced deformation.
The resulting framework will therefore permit initially discrete particles to merge into connected material
domains, while subsequent separation and fracture are captured through phase-field damage. In this manner,
the evolving microstructure, including the formation and loss of contacts, changes in transport pathways,
and development of damage, can be predicted directly during cycling. The framework will then be used to
investigate how microstructural design parameters, including particle morphology and composition, binders,
and prescribed defects, may be used to control stress redistribution and damage evolution. Together, these
developments will provide a predictive approach for designing evolving microstructures that maintain me-
chanical integrity and transport performance in high-energy-density storage materials.
Committee:
Dr. Claudio Di Leo (advisor), School of Aerospace Engineering
Dr. Christos E. Athanasiou, School of Aerospace Engineering
Dr. Kennedy J. Graeme , School of Aerospace Engineering
Dr. Matthew T. McDowell, School of Materials Science and Engineering
Dr. Akanksha Krishnakumar Menon, School of Mechanical Engineering