The Woodruff School

SUMMARY

Zoom meeting passcode: 908987 Lithium batteries and fuel cells play important roles in the emerging renewable energy landscape of the world. Practical applications of both systems face outstanding challenges, including the increasing energy density and power density of lithium batteries and the safety issue of structural components for hydrogen storage and transportation. To address these challenges, this thesis focuses on chemomechanical modeling of lithium-ion transport through complex electrode microstructures in lithium batteries and hydrogen embrittlement of metallic alloys under cyclic mechanical loads. For lithium-ion transport through complex electrode microstructures, a numerical framework is developed to construct porous electrode microstructures and evaluate their effective transport properties and geometric characteristics. Correlations between the effective transport properties and microstructure parameters offer mechanistic insights into the design of novel electrode microstructures to enable fast ion transport in lithium batteries. Furthermore, ion transport is studied in electrodes with laser patterned conical channels through a theoretical model. A quantitative relation is established between the process parameters and effective diffusivities, offering design guidance toward high-performance batteries. To enable the quantitative characterization of hydrogen-induced mechanical degradation of metallic structural components, a cyclic crystal plasticity finite element (CPFE) model is developed to simulate the mechanical behavior of austinite 316L stainless steel with the face-centered cubic crystal structure. This cyclic CPFE model is applied to predict both the crack deformation field and fatigue crack growth rate based on accumulated plastic work and can be generalized to investigate the time-dependent crack growth that is strongly influenced by the crystallographic effects of crack tip grains. Overall, this thesis advances predictive chemomechanical modeling toward the computational design of reliable structural components for renewable energy applications.

SUBJECT:	Ph.D. Dissertation Defense

BY:	Baolin Wang

TIME:	Thursday, October 20, 2022, 11:00 a.m.

PLACE:	https://gatech.zoom.us/j/96493043927, Zoom

TITLE:	Chemomechanical Modeling of Rechargeable Battery Electrodes and Hydrogen Embrittlement

COMMITTEE:	Dr. Ting Zhu, Chair (ME) Dr. Hailong Chen (ME) Dr. Matthew McDowell (ME) Dr. Shuman Xia (ME) Dr. Gleb Yushin (MSE) Dr. Jessica Zhang (ME(CMU))

SUMMARY Zoom meeting passcode: 908987 Lithium batteries and fuel cells play important roles in the emerging renewable energy landscape of the world. Practical applications of both systems face outstanding challenges, including the increasing energy density and power density of lithium batteries and the safety issue of structural components for hydrogen storage and transportation. To address these challenges, this thesis focuses on chemomechanical modeling of lithium-ion transport through complex electrode microstructures in lithium batteries and hydrogen embrittlement of metallic alloys under cyclic mechanical loads. For lithium-ion transport through complex electrode microstructures, a numerical framework is developed to construct porous electrode microstructures and evaluate their effective transport properties and geometric characteristics. Correlations between the effective transport properties and microstructure parameters offer mechanistic insights into the design of novel electrode microstructures to enable fast ion transport in lithium batteries. Furthermore, ion transport is studied in electrodes with laser patterned conical channels through a theoretical model. A quantitative relation is established between the process parameters and effective diffusivities, offering design guidance toward high-performance batteries. To enable the quantitative characterization of hydrogen-induced mechanical degradation of metallic structural components, a cyclic crystal plasticity finite element (CPFE) model is developed to simulate the mechanical behavior of austinite 316L stainless steel with the face-centered cubic crystal structure. This cyclic CPFE model is applied to predict both the crack deformation field and fatigue crack growth rate based on accumulated plastic work and can be generalized to investigate the time-dependent crack growth that is strongly influenced by the crystallographic effects of crack tip grains. Overall, this thesis advances predictive chemomechanical modeling toward the computational design of reliable structural components for renewable energy applications.