Mathematical modelling is widely used to provide insights into lithium-ion battery operation, mainly by using Doyle-Fuller-Newman (DFN) porous electrode theory. A key aspect of thermo-electrochemical models is the description of electrolyte transport phenomena and their implications on thermal effects, which are the subject of this study. We show that the so-called generalized Poisson-Nernst-Planck approach (here re-named generalized Nernst-Planck, gNP) for electrolyte transport is equivalent to DFN concentrated solution theory only if the electrolyte thermodynamic factor obeys a specific gNP expression as a function of three electrolyte parameters. However, such an expression does not capture accurately the experimental dependence of the thermodynamic factor for concentrations lower than 0.5 mol l−1 or higher than 1.5 mol l−1 in a common LiPF6-based electrolyte, causing discrepancies between model predictions. The deviation between simulation results of the DFN and gNP models is negligible at low C-rates and ambient temperature. However, as the operative conditions get more challenging as for C-rate > 1 and/or extreme temperatures, detectable deviations are shown in terms of predicted voltage, maximum temperature, and accessible/ restored capacity. Furthermore, the electrolyte transport models predict different onsets of lithium plating upon charge, showing moderate deviations in the estimated penetration depth of plating.

Comparison of Electrolyte Transport Modelling in Lithium-ion Batteries: Concentrated Solution Theory Vs Generalized Nernst-Planck Model

Marco Lagnoni
Primo
Investigation
;
Cristiano Nicolella
Secondo
Investigation
;
Antonio Bertei
Ultimo
Investigation
2022-01-01

Abstract

Mathematical modelling is widely used to provide insights into lithium-ion battery operation, mainly by using Doyle-Fuller-Newman (DFN) porous electrode theory. A key aspect of thermo-electrochemical models is the description of electrolyte transport phenomena and their implications on thermal effects, which are the subject of this study. We show that the so-called generalized Poisson-Nernst-Planck approach (here re-named generalized Nernst-Planck, gNP) for electrolyte transport is equivalent to DFN concentrated solution theory only if the electrolyte thermodynamic factor obeys a specific gNP expression as a function of three electrolyte parameters. However, such an expression does not capture accurately the experimental dependence of the thermodynamic factor for concentrations lower than 0.5 mol l−1 or higher than 1.5 mol l−1 in a common LiPF6-based electrolyte, causing discrepancies between model predictions. The deviation between simulation results of the DFN and gNP models is negligible at low C-rates and ambient temperature. However, as the operative conditions get more challenging as for C-rate > 1 and/or extreme temperatures, detectable deviations are shown in terms of predicted voltage, maximum temperature, and accessible/ restored capacity. Furthermore, the electrolyte transport models predict different onsets of lithium plating upon charge, showing moderate deviations in the estimated penetration depth of plating.
2022
Lagnoni, Marco; Nicolella, Cristiano; Bertei, Antonio
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11568/1142054
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