Investigation on heat generation in fast charging of lithium-ion batteries: Effect of charging rate and battery component thickness

Abstract

Understanding heat generation mechanisms during fast charging is essential for designing and optimizing lithium-ion batteries. In this study, we have formulated a three-dimensional electrochemical-thermal coupling model for pouch lithium-ion batteries. The model is validated by the experimental results based on the distribution of temperature, current, and voltage. We investigate the effects of charging rate, active material coating thickness, and current collector thickness (each at three levels) on heat generation and temperature distribution. The electrodes account for most of the total heat generation (87.5% with a 2.5C charging rate), and the percentage decreases as the charging rate increases. The heat generated at the negative electrode is slightly higher than that at the positive electrode. Reversible heat is the main heat source at a low charging rate, and it decreases as the charging rate rises. The effects of battery component thicknesses on thermal behaviors under fast charging are significant. The overall battery temperature increases by 11.5 K as the positive electrode thickness increases from 40 to 70 µm due to the rise in ohmic resistance and polarization resistance within the electrode. The increased ohmic resistance in the separator and the current collector raises the temperature. Reducing the thickness of the current collector by 33% resulted in a doubling of heat generation from the current collectors. Yet, it had minimal impact on the overall temperature of the battery.

Keywords:

• Charging rates
• current collector thickness
• electrochemical-thermal coupling model
• heat generation
• lithium-ion batteries

Disclosure statement

No potential conflict of interest was reported by the author(s).