SUMMARY

Lithium batteries and fuel cells play important roles in the emerging renewable energy landscape of the world. However, practical applications of both systems face outstanding challenges, including fast degradation of lithium batteries and safety issues of structural components for hydrogen storage and transportation. To address these challenges, predictive chemomechanical modeling is critically needed. This thesis is focused on the chemomechanical modeling of lithium-ion transport through complex electrode microstructures in lithium batteries and hydrogen embrittlement of metallic alloys under cyclic mechanical loads. For the lithium battery study, we will develop a synthetic microstructure model of battery electrode. Novel computational methods will be used to compute the porosity-tortuosity relations of solid electrolytes that will be further compared with experimental measurements. Our model will offer mechanistic insights into the design of novel electrode microstructures to enable fast ion transport in lithium batteries. For the hydrogen embrittlement study, we will develop a mechanistically based crystal plasticity model for studying hydrogen-induced fatigue crack growth in stainless steel. The crystal plasticity model will be implemented by writing user material subroutines in the finite element simulation software ABAQUS. We will predict fatigue crack growth rates in stainless steel and compare the predictions with experimental measurements. The chemomechanical modeling framework developed can be generalized to enable the mechanistically based predictions of hydrogen embrittlement in a wide range of engineering alloys in the future. Overall, this thesis research will advance predictive chemomechanical modeling for enabling the computational design of important components for high-performance rechargeable battery and fuel cell systems.