Design Analysis of 3D Lithium-ion Batteries with Computational Modeling

Abstract

This dissertation reports on the investigation of micrometer-scale three-dimensional (3D) batteries on the transport, kinetic, and deposition mechanisms in Lithium-ion battery (LIB) cells using physics-based computational models. Conventional LIBs use planar electrodes composed of a randomly distributed solid particle network infused with liquid electrolyte. A planar electrode imposes a trade-off between energy density and power density in LIB cells, where a higher cell capacity requires more active materials in the electrodes, which inevitably increases the electrode thickness and introduces high transport impedances. 3D electrodes address this limitation by redistributing the solid electrode particles into non-planar configurations, providing additional transport and kinetic benefits and effectively loosening the trade-off. Although various 3D LIBs have been modeled and fabricated over the last two decades, the relative performance advantages across different 3D electrode architectures and material systems remain unclear. This dissertation systematically analyzes these architectures, proposing frameworks to design, compare, and evaluate 3D LIB configurations for optimal energy and power density. The focus is on two categories of 3D LIBs: (1) the Interdigitated Electrodes (IDEs), which feature intertwined cathode and anode geometries that shorten the transport distance between the electrodes, and (2) the Structured Electrodes (SEs), which have macro-porosity integrated across the electrode thickness, acting as low tortuosity ionic transport pathways. Physics-based 3D volume-average electrochemical models were generated in VIBE-AMPERES, a battery modeling software developed by Oak Ridge National Laboratory, to assess the impact of 3D electrode architectures and materials on the charge and discharge performance of both single-layer and multi-layer battery cells. Material systems studied include Li4Ti5O12 (LTO) anode paired with LiFePO4 (LPF) cathode, graphite anode with LiNi0.5Mn0.3Co0.2O2 (NMC-532) cathode, and graphite anode with LiNi0.6Mn0.2Co0.2O2 (NMC-622) cathode. Additionally, this dissertation presents a lithium plating model developed through the 3D volume-average method, which is employed to explore how SEs influence the onset and location of lithium plating in graphite|NMC-532 cells. By investigating how controlled electrode heterogeneity affects transport and kinetic processes through 3D physics-based, continuum-scale computational models, this work reveals critical insights into cell-level performance metrics such as charge and discharge capacity, energy density, power density, and lithium plating. The overarching objective is to advance 3D electrode design strategies by deepening the fundamental understanding of these mechanisms through analytical studies.