Unveiling the Effects of the Diffusivity and Exchange Current Density on the Electrochemical Modeling of Lithium-Ion Battery

The diffusivity and exchange current density are the two main parameters that determine both ionics and electrodics in the Newman’s battery model. Nonetheless, the values of both parameters are normally selected from eminent literatures or experimental data measured under specific conditions, furthermore, and they are occasionally overfitted to coincide with real electrochemical behaviors without sufficient consideration. Herein, the diffusivities and exchange current densities of a LiNi0.4Mn0.3Co0.3O2/Li half-cell are measured and applied to the electrochemical model using four different electrochemical techniques: galvanostatic intermittent titration technique (GITT), potentiostatic intermittent titration technique (PITT), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). The model adopting the diffusivity and exchange current density measured in PITT and EIS, respectively, simulates the actual voltage and capacity profiles well with low errors without any fitting. Therefore, this case study helps us understand the effects of the essential parameters on the electrochemical behavior and the pros and cons of each measurement technique.