Simplified Electrochemical and Thermal Model of LiFePO₄-Graphite Li-Ion Batteries for Fast Charge Applications

Abstract

International audienceDerived from the Pseudo Two-Dimensional mathematical structure, a simplified electrochemical and thermal model of LiFePO4-graphite based Li-ion batteries is developed in this paper. Embedding the porous electrode theory, this model integrates the main design parameters of Li-ion systems and its partial differential equations mathematical structure makes it a promising candidate for battery management system (BMS) applications and comprehensive aging investigations. Based on a modified Single-Particle approach, the model is used to simulate and discuss capacity restitution in galvanostatic charges and discharges at various rates and temperatures. Constant high-rate solicitations similar to fast charge of plug-in electric vehicles or electric vehicles, are experimentally tested and simulated with the present model. Also, thermal issues occurring during these specific operating conditions are quantitatively pointed out. The concept of current-dependent spherical particle radius is used to obtain good agreement with experimental data related to galvanostatic charges and discharges. The capabilities and limits of this preliminary modeling work are discussed in detail and ways to extend the potentialities of this approach to BMS applications are proposed

Current-induced transition from particle-by-particle to concurrent intercalation in phase-separating battery electrodes

“…We obtain good fits, with an of 0.2 and a of 0.6 A m -2 , yielding an average exchange current density of ~ 0.3 A m -2 . The exchange current density is higher than most reported values in literature; however, past work did not consider the active particle fraction and likely overestimated the active reaction area [20][21][22][23] . The fittings may also be affected by departures from Butler-Volmer kinetics at high rates that that lead to curved Tafel plots and small effective values of 27 .…”

“…Dreyer et al proposed that the thermodynamic origin of this behaviour arises from the non-monotonic chemical potential of Li as a function of the particle's composition 17 . On the other hand, a concurrent intercalation pathway, whereby most particles intercalate at once, has also been observed in LFP 18,19 .Despite its crucial importance, the active population has been largely neglected in models describing electrode cycling [20][21][22][23] . Differing approximations in the active population may have contributed to the vast range of experimentally-measured specific exchange current densities, which range from 10 -6 A m -2 to 10 -1 A m -2 in LFP [20][21][22][23] .…”

“…Despite its crucial importance, the active population has been largely neglected in models describing electrode cycling [20][21][22][23] . Differing approximations in the active population may have contributed to the vast range of experimentally-measured specific exchange current densities, which range from 10 -6 A m -2 to 10 -1 A m -2 in LFP [20][21][22][23] .…”

“…Differing approximations in the active population may have contributed to the vast range of experimentally-measured specific exchange current densities, which range from 10 -6 A m -2 to 10 -1 A m -2 in LFP [20][21][22][23] . The active population has sometimes been considered in terms of an electrode-level lithiation front from the separator to the current collector 24 .…”

Multiphysics based thermal modeling of a pouch lithium-ion battery cell for the development of pack level thermal management system

“…It leads to higher temperature rise inside the battery pack. These phenomena are well known from the tests and empirical field data that the reliability and lifetime performance of battery packs are mainly temperature related [1,2]. Moreover, the current trend is now towards the use of the increasingly high performance, and high power batteries inside the pack with dense packaging.…”