Investigation of the P2D and of the modified single-particle models for predicting the nonlinear behavior of Li-ion batteries

Abstract

Lithium-ion battery technology has become one of the most practical rechargeable energy storage solutions. Online robust and precise numerical prediction of Li-ion batteries' macroscopic state (e.g., voltage by capacity) and microscopic state (e.g. electrolyte and solid concentration) is vital for improving their performance. It has been shown by Valøen and Reimer that the electrolyte properties such as the diffusivity, the conductivity, and the thermodynamic factor are concentration-dependent. Yet, most simplified models of Li-ion batteries consider constant electrolyte properties. The present work addresses this shortcoming by investigating the effect of electrolyte properties concentration on the macroscopic and microscopic battery states. The comparison between the pseudo-two-dimension (P2D) model with constant and dependent electrolyte properties reveals significant differences in battery outputs, especially at higher C-rates. A nonlinear modified single-particle model is proposed as a simplified electrochemical-based model (SEBM) in order to capture the nonlinearity caused by the concentration-dependent electrolyte parameters. As a result, the simplified model can mimic the full order P2D with a significantly lower computation time.