Li-Ion Battery Mesoscale Homogenization for Full-Cell Simulation
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Solution Overview
Problem
Current electrochemical models for Li-ion batteries struggle to accurately capture performance and aging drivers due to limitations in continuum modeling, which assumes uniform material properties, and microstructure modeling, which is impractical for full cell simulations.
Innovation Solution
A method is developed to upscale battery microstructure characterization from the micrometer scale to a coarse resolution electrochemical simulation, maintaining fine resolution heterogeneity effects on performance, aging, and degradation within a workable model size. This involves creating a coarsened heterogeneous porosity model and calculating porosity-dependent constitutive relationships to simulate full Li-ion battery cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If microstructure modeling is used to capture real microstructure behavior, then accuracy of microstructure behavior is improved, but model size becomes intractable for full cell simulation
Solution Approach 1:
The battery cell is divided into representative volume elements (RVEs) that capture microstructure heterogeneity at a reduced scale. Each RVE contains simplified geometric representations of particles, pores, and other microstructural features, allowing local heterogeneity to be modeled without requiring full-cell microstructure resolution.
Solution Approach 2:
Homogenization techniques serve as an intermediary between microstructure modeling and continuum modeling. Effective properties are calculated from RVE simulations and then used in continuum-scale models, bridging the gap between microstructural accuracy and full-cell scalability.
2Productivity
If continuum modeling is used to simulate full cell battery, then ability to simulate full cell is improved, but accuracy of microstructure behavior deteriorates due to homogenized material properties
Solution Approach 1:
The model assigns different levels of detail to different spatial locations. RVEs with explicit microstructure are placed at critical locations where heterogeneity effects are most important, while other regions use homogenized continuum properties. This allows full-cell simulation capability while maintaining microstructural accuracy where needed.
Solution Approach 2:
The modeling approach creates a composite model structure that combines discrete RVE elements with continuous matrix material. This composite modeling framework allows the system to exhibit both microstructural heterogeneity effects and continuum-scale behavior, achieving accuracy and scalability simultaneously.
Data Source
AI summary
A microstructure is upscaled to generate a coarsened heterogeneous spatial distribution of porosity and a set of porosity dependent constitutive relationships. A three dimensional (3D) microstructure model, bulk material properties, and/or porosity is received for anode, cathode, and separator battery components. A coarsened porosity model with emergent properties is calculated from the battery component microstructures as a function of the porosity. Bruggeman coefficients for each battery component sub region are calculated from the effective ionic conductivity, electric and thermal conductivity, and ionic diffusivity. A heterogeneous mesoscale 3D battery model is created by combining the anode, cathode, and separator materials into a single cell structure and separately partitioning each into coarse voxels to create a 3D model of porosity.