Decoupling parameter estimation strategy based electrochemical-thermal coupled modeling method for large format lithium-ion batteries with internal temperature experimental validation

Abstract

Accurate battery model generally plays a significant role in the optimal design and management of lithium-ion batteries (LIBs). However, performing fast and accurate parameter estimation of a commercial LIB is still a challenging task, especially for the electrochemical reaction and transport mechanism based model. In this study, a pseudo two-dimensional electrochemical model and a three-dimensional thermal model are coupled to describe the electrical and thermal dynamics of a commercial LIB, and a variable solid state diffusion concept is adopted in electrochemical model for enhancing the model prediction ability. To improve the parameter estimation efficiency and accuracy, a novel decoupling estimation strategy of electrochemical and thermal related parameters is proposed. In addition, a surrogate model based optimization approach is introduced to handle the high computational parameter estimation procedure. To effectively validate the proposed modeling strategy, twenty-five thermocouples were embedded into a commercial large format prismatic LIB during manufacturing for characterizing the non-uniform internal temperature distribution. Both fitting and prediction results of terminal voltage and temperature distribution indicate that the proposed model is capable of capturing the electrical and thermal dynamic characteristics of large format prismatic LIB under different discharge rates and ambient temperatures. It is thus illustrated that the proposed modeling strategy could provide a potential promising solution framework for constructing an accurate model of commercial batteries and is greatly helpful for performing further battery design and management.