Decomposition Study of Degradation Reasons for LiCoO2-Based 14500 Lithium-Ion Batteries Using a Nondestructive Method

Detailed information about the components of degradation is quite beneficial for the prognostics and health management study of lithium-ion batteries. This paper reports a nondestructive method for the decomposition study of the reasons of degradation for LiCoO₂ batteries. The values of parameters of the multiphysics model are obtained in a four-pattern aging test and, then, the components of the capacity fade, overpotential rise, and heat behavior are quantitatively calculated by using the identified parameters and model simulation. The capacity fade is divided into three components due to the changes of parameter, the volume fraction of active material (ε_s), and stoichiometric numbers (x₀ and x_end) during aging process. The overpotential rising is divided into three components according to the reaction overpotential and the terminal voltage equations in the multiphysics model. In addition, the heat generation is divided into three components and the heat exchange is divided into two components based on the thermal part of the multiphysics model. All the decomposition results are graphically shown, and the ratios of the degradation components are presented in tables. The proposed method is expected to extend the applications of the multiphysics model and bring a new idea to the primary diagnosis of lithium-ion battery.