Experimental Assessment of the Lumped Lithium Ion Battery Model at Different Operating Conditions

Abstract

This study investigates the electrical and thermal characteristics of a cylindrical lithium-ion cell with an axisymmetric two-dimensional lumped model. The cell is completely discharged at 0.5, 1 and 1.5 C rates under 0, 20 and 50 °C operating temperatures. Both the open circuit voltage values and the average specific heat value of the cell are measured and used as an input to the model. The model uses the variable internal resistance approach to evaluate the voltage variation of the cell that is obtained from experimental data. A cylindrical lithium-ion cell has a spiral construction that involves multiple layers. However, these layers are assumed as a uniform material in the lumped model. The lumped model in COMSOL Multiphysics couples the heat transfer and lumped battery interfaces so it allows predicting the surface temperature of the cell during discharging processes. The experimental results point out that the operating temperature inversely affects the internal resistance and the heat generation within the cell during a discharging process. Furthermore, it is found that the capacity of the cell significantly decreases at low operating temperatures. Finally, the predicted temperature profile follows the same trend with the experimental data and is consistent at each operating condition.

Additional information

Notes on contributors

Tanılay Özdemir

Tanılay Özdemir is a PhD student and a research assistant at the Mechanical Engineering Department of Hacettepe University, Ankara, Turkey. He received his BSc degree in Mechanical Engineering from Yıldız Technical University in 2012, and MSc degree from the Institute of Energy, Istanbul Technical University in 2015. His doctoral research is focused on the thermal behavior of the lithium ion batteries under normal and abuse operating conditions.

Ali Amini

Ali Amini received his BSc and MSc degrees in Mechanical Engineering Faculty from Tabriz University and Sahand Technical University, respectively. He has gained his PhD in Mechanical Engineering from Ataturk University. His main academic fields are internal combustion engines, computational fluid dynamics analysis, energy efficiency, modeling of dynamic systems, electric and hybrid vehicles, drying systems and Li-ion batteries. He is working as a design specialist and consultant for R&D companies in Ankara.

Özgür Ekici

Özgür Ekici received his BSc and MSc degrees from the Department of Mechanical Engineering, METU, Ankara, and PhD degree from the University of Texas at Austin in 2007. Following one year of postdoctoral position at the same university, he worked in industry as a design specialist. Since 2011, he has been associated with the Hacettepe University as a faculty member in the Department of Mechanical Engineering. His research area includes thermal-fluid systems, numerical modeling and computational fluid dynamics applications.

Murat Köksal

Murat Koksal studied Mechanical Engineering at the Middle East Technical University receiving BS and MS degrees and then completed his PhD at Dalhousie University in 2001. He has been with Hacettepe University since 2006. His research interests lie in the fields of multiphase flows and novel energy conversion systems.