Electrode structure is closely coupled with mechanical behavior, ion transport, and reaction uniformity during battery operation. In addition to conventional slurry-cast electrodes, emerging fabrication approaches provide new opportunities to study and design electrode architectures. This thesis investigates lithium-ion battery electrodes through two complementary perspectives related to the electrode structure: micro-scale mechanical characterization to elucidate degradation mechanisms and additive manufacturing of three-dimensional (3D) micro-architected electrodes to investigate structure-transport relationships. In Chapters 2 and 3, the mechanical behavior of lithium-ion battery electrodes was investigated using nanoindentation and micro-pillar compression experiments. State-of-charge-dependent mechanical properties of electroplated LiCoO2 (LCO) cathodes were quantified, revealing a decreasing tendency in elastic modulus and hardness during delithiation, which is attributed to the expansion of LCO layered structure. Fracture toughness distribution across the electrode thickness was analyzed to understand how structural heterogeneity contributes to the mechanical property landscape. In addition, we studied the deformation of lithium-based composite anodes, confirming that the Li/Na composite anode exhibits higher deformability at the electrode-electrolyte interface, which enhances interfacial contact. The interconnected pore structure and large surface-to-volume ratio of 3D architected battery electrodes render them promising for enhancing electrochemical performance via more efficient ionic transport. In Chapters 4 and 5, we develop a hydrogel infusion additive manufacturing (HIAM)-based approach to fabricate micro-architected LiFePO4 (LFP)/C composite electrodes with feature sizes down to 18 µm. The concomitant formation of carbon within the lattice enhances the mechanical strength, which preserves shape integrity of the 3D structure during cell assembly and function. We designed electrodes with different geometries, including tilted cubes, honeycombs, and triply periodic minimal surfaces (TPMS), to probe the influence of geometric factors on electrochemical performance under various charge-discharge rates. We propose an experimentally informed electrochemical model that demonstrates the roles of Li+ transport in the electrolyte and Li+ diffusion in the electrode in determining the utilization of active materials. This work introduces a versatile manufacturing platform for printing 3D battery components and provides insights into structure optimization for high-performance rechargeable batteries.
Yingjin Wang (Tue,) studied this question.