A Surrogate-Based Multi-Scale Model for Mass Transport and Electrochemical Kinetics in Lithium-Ion Battery Electrodes

Lithium-ion batteries are now used in a wide range of applications, and much knowledge has been accumulated in the relevant physical phenomena. However, the application of this knowledge in battery design still relies on an inefficient manual process, in large part due to limitations in existing computational models. To address this, a multi-scale model is developed that incorporates microscopic simulation data for effective ion diffusivity and electronic conductivity, and interfacial electrochemical kinetics, into a macroscopic homogeneous model at the cell scale. Microscopic physics-based models are applied to 3D microstructures, and automated simulations are performed for statistically significant averaging of the results. A surrogate model couples the length scales by precomputing solutions based on a design of experiments. Results for the porosity-tortuosity relationship are compared to experimental data in the literature, and global sensitivity analysis is performed to quantify the relative impact of ion concentration and electric potential distribution on the electrochemical kinetics profile. The resulting multi-scale model successfully reproduces the microscopic solution while retaining the computational efficiency of the macroscopic homogeneous model. These attributes make it a suitable candidate for implementation in an automated simulation and optimization framework that may lead to a more efficient design process for high performance batteries.