Multiscale modeling of lithium ion batteries: thermal aspects

Abstract

SummaryThe thermal behavior of lithium ion batteries has a huge impact on their lifetime and the initiation of degradation processes. The development of hot spots or large local overpotentials leading, e.g., to lithium metal deposition depends on material properties as well as on the nano- und microstructure of the electrodes. In recent years a theoretical structure emerges, which opens the possibility to establish a systematic modeling strategy from atomistic to continuum scale to capture and couple the relevant phenomena on each scale. We outline the building blocks for such a systematic approach and discuss in detail a rigorous approach for the continuum scale based on rational thermodynamics and homogenization theories. Our focus is on the development of a systematic thermodynamically consistent theory for thermal phenomena in batteries at the microstructure scale and at the cell scale. We discuss the importance of carefully defining the continuum fields for being able to compare seemingly different phenomenological theories and for obtaining rules to determine unknown parameters of the theory by experiments or lower-scale theories. The resulting continuum models for the microscopic and the cell scale are numerically solved in full 3D resolution. The complex very localized distributions of heat sources in a microstructure of a battery and the problems of mapping these localized sources on an averaged porous electrode model are discussed by comparing the detailed 3D microstructure-resolved simulations of the heat distribution with the result of the upscaled porous electrode model. It is shown, that not all heat sources that exist on the microstructure scale are represented in the averaged theory due to subtle cancellation effects of interface and bulk heat sources. Nevertheless, we find that in special cases the averaged thermal behavior can be captured very well by porous electrode theory.

Quantifying Inhomogeneity of Lithium Ion Battery Electrodes and Its Influence on Electrochemical Performance

“…the potential between the current collectors) is the sum of the SOC-dependent open circuit potential of graphite OCP graphite , the resistance overpotential in the electrolyte θ E , the activation overpotential η act and the contact resistance overpotential of the current collectors R CC : 30,45 θ tot = OC P Graphite + θ E + η act + R CC While the OVP Graphite is the same for all electrodes, the resistance overpotential of the electrolyte θ E and the activation overpotential η act modeled by the Butler-Volmer equation, depend on the lithium concentration in the electrolyte, which is influenced by the microstructure of the electrodes.…”

Derivation of a local volume-averaged model and a stable numerical algorithm for multi-dimensional simulations of conversion batteries

“…We implement the governing equations (see Section S1 of the Supplementary Information) in our in-house tool BEST, Battery and Electrochemistry Simulation Tool [38, 39,40]. BEST uses a finite volume scheme for spatial discretization and an implicit Euler method for time integration [41].…”

A Review of Model-Based Design Tools for Metal-Air Batteries

“…In this case, a coupled expression for diffusion-migration flux can be derived from non-equilibrium thermodynamics [134,152,153]. For strongly acidic or alkaline electrolytes, the concentrations of H + or OH -are usually so high that concentration gradients do not affect the thermodynamic stability of the solutes.…”