An Inverse Method for Estimating the Electrochemical Parameters of Lithium-Ion Batteries

Abstract

This paper is the second part of a two part study on parameter estimation of Li-ion batteries. The methodology was developed in Part I. In Part II, the methodology is tested for LiCoO 2 , LiMn 2 O 4 and LiFePO 4 positive electrode materials. An inverse method combined to a simplified version of the Pseudo-two-Dimensional (P2D) model is used to identify the solid diffusion coefficients (D s,n and D s,p ), the intercalation/deintercalation reaction-rate constants (K n and K p ), the initial SOC (SOC n,0 and SOC p,0 ), and the electroactive surface areas (S n and S p ) of Li-ion batteries. Experimental cell potentials for both low and high discharge rates provide the reference data for minimizing the objective function in the best time interval. For all cases simulated, the numerical predictions show excellent agreement with the experimental data. Lithium-ion (Li-ion) batteries are increasingly employed for energy storage. Their working voltage and energy density are higher than those of similar energy storage technologies. Their service life is longer. They exhibit high energy-to-weight ratios and low selfdischarge. As a result, they have become the preferred energy storage devices in the electronics and the automotive industries.Mathematical modeling of Li-ion batteries is an essential engineering tool for their design and operation. Two different approaches are usually adopted to predict their behavior. These approaches may be divided, broadly speaking, into empirical models and electrochemical models.Empirical models are the simplest mathematical models. They are relatively easy to implement and they provide fast responses. This is why they are mostly suited for control systems used in the high tech industry and in the automotive industry. The scope of applications of empirical models is however narrow. Empirical models ignore the physical phenomena that take place in the cell. Consequently, they cannot predict the life and the capacity fading of the battery. Furthermore, they are only valid for the battery for which they have been developed. [1][2][3] Electrochemical models provide, on the other hand, reliable responses of the battery under a wide range of operating conditions and for different applications. They account for the chemical/ electrochemical kinetics and the transport phenomena. Electrochemical models are unequivocally superior to empirical models. But they are also more complex and require longer computation times.Among the electrochemical models, the Pseudo-two-Dimensional (P2D) model stands out. The P2D model rests on the porous electrode theory, the concentrated solution theory and the use of appropriate kinetics equations.4-6 A simplified and computationally efficient version of the P2D model is the Single Particle Model (SPM). In the SPM, it is assumed that the current distribution along the thickness of the porous electrode remains uniform and that the electrolyte properties are constant. 5,7Both empirical and electrochemical models need to be calibrated in order to simulate faithfully the ...

A modeling framework to assess specific energy, costs and environmental impacts of Li-ion and Na-ion batteries

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Thermal uncertainty analysis of a single particle model for a Lithium-Ion cell

“…Likewise, there are inverse analysis electrochemical systems defined by Li-ion batteries, see [23][24][25].…”

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