Electro-Chemo-Mechanical Modeling for Battery Intercalation Materials
Repeated phase transformations in materials are often accompanied by degradation in functional properties. In intercalation battery materials, repeated charge/discharge cycling can lead to structural damage, fatigue, and voltage hysteresis, ultimately limiting electrode performance and lifetime. However, the fundamental origins of these phenomena remain poorly understood. My research seeks to uncover the interplay between atomic-scale crystallographic changes and continuum-scale microstructural evolution that governs the behavior of phase-transforming intercalation materials used in rechargeable battery electrodes.
To address this, I develop continuum models that provide quantitative insight into how crystallographic microstructures nucleate, evolve, and interact with electrochemical processes during phase transformation. In particular, I present a continuum framework for symmetry-breaking phase transformations in intercalation compounds based on Ericksen's multiwell energy formulation. Applied to LiMn2O4, a representative intercalation compound, the model predicts the nucleation and growth of crystallographic microstructures with twin-boundary orientations and volume fractions that closely agree with experimental observations.
My chemo-mechanically coupled model not only reproduces geometrically realistic microstructures through energy minimization, but also reveals the subtle coupling between twinned domains and electro-chemo-mechanical behavior. A key finding is that intercalation compounds satisfying specific crystallographic compatibility conditions, such as λ2=1 or |det U − 1|=0, exhibit lower elastic energy barriers, require smaller driving forces for phase transformation, and display narrower voltage hysteresis loops. In addition, I show that twinned domains can serve as fast diffusion pathways for lithium transport.
These findings establish quantitative design principles for intercalation battery materials, emphasizing the tailoring of lattice deformation and crystallographic compatibility, rather than simply suppressing phase transformation, to reduce energy barriers, mitigate structural degradation, and improve the electrochemical performance and durability of rechargeable battery electrodes.