Energy Storage Science and Technology ›› 2023, Vol. 12 ›› Issue (8): 2615-2625.doi: 10.19799/j.cnki.2095-4239.2023.0082

• Energy Storage Test: Methods and Evaluation • Previous Articles     Next Articles

Heat generation analysis for lithium-ion battery components using electrochemical and thermal coupled model

Jiaxing YANG(), Hengyun ZHANG(), Yidong XU   

  1. School of Mechanical & Automotive Engineering, Shanghai University of Engineering Science, Shanghai 201620, China
  • Received:2023-02-20 Revised:2023-03-14 Online:2023-08-05 Published:2023-08-23
  • Contact: Hengyun ZHANG E-mail:yoogating@163.com;zhanghengyun@sues.edu.cn

Abstract:

Understanding the thermal aspects of the battery electrochemical process is essential for managing the heat generated in lithium-ion batteries. Herein, an electrochemical-thermal coupled model was developed for an NMC lithium-ion battery. Experimental tests were conducted to validate the accuracy of the model in predicting voltage and temperature variations at different discharge rates and temperatures. Simulation studies were then conducted to estimate battery performance at different temperatures. At normal temperatures, regardless of the discharge rate, the NE heat generation was always smaller than the PE heat generation. While the NE polarization heat was higher than the PE polarization heat, the reversible heat absorption of NE was larger than that of PE. Consequently, the NE heat generation remained lower than that of PE. As the discharge rate increased, the proportion of PE heat generation decreased, whereas the proportion of NE heat generation increased first and then decreased. Simultaneously, the proportion of collector heat generation continued to rise. However, the heat generation characteristics differed when the battery discharge was discharged at subzero temperature compared to the normal temperature case. Firstly, subzero temperatures considerably increased the proportion of NE generation at low discharge rates. The reversible heat from NE became the primary contributor to the total reversible heat. Conversely, at high discharge rates, the NE heat generation rate decreased, while the PE heat generation rate exhibited the opposite trend. Secondly, the discharge time at subzero temperatures showed different trends with increasing discharge rates. At high discharge rates, the voltage rapidly decreased, leading to incomplete discharge and a phenomenon known as voltage rebound. At low discharge rates of 0.5—1 C discharge operation, the basic discharge process was completed, but the voltage rebound still occurred. The subzero temperature restricted the timely diffusion of lithium ions from the NE particles, leading to increased resistance and a rapid voltage drop. Meanwhile, a large amount of heat generation contributed to the temperature rise in the battery. Therefore, the battery exhibited the ability to rebound and maintain a continuous discharge at low rates.

Key words: lithium-ion battery, electrochemical-thermal coupled model, heat generation, subzero temperature characteristics, voltage rebound

CLC Number: