An approximate solution for electrolyte concentration distribution in physics-based lithium-ion cell models

An approximate solution for the electrolyte concentration distribution is obtained for improving the computational efficiency of the physics-based lithium-ion cell models. The approximate solution is derived from the analysis of the essential physical processes, using a parabolic profile approximation which assumes that the electrolyte concentration profile in the porous electrode is a parabolic polynomial in x at any time. By comparing the electrolyte concentration distributions and its overpotential profiles from this solution with those from the numerical finite difference solution, it is validated that the solution from this study is better than most existed ones in light of real-time computations and controls in EV, HEV and so forth. Moreover, the approximate solution can be applied to any type of charge-discharge operating scenarios with no loss of accuracy. Particularly, this solution provides a simpler mathematical expression with fewer terms and higher computational efficiency.