Suggested Citation:
Eze, Chika, Jingyuan Zhao, Dukhyun Chung, Mohammad Fakhimi Bonab, Abel Chuang, Andrew Burke, Guanhua Chen (2024)

Numerical Heat Generation Analysis of the Tabbed and Novel Tabless Designs of Cylindrical-Type Lithium-Ion Batteries

. Institute of Transportation Studies, University of California, Davis, Journal Article UCD-ITS-RP-24-12

Abstract:

The heat generation behaviours of a traditional tabbed cylindrical lithium-ion (Li-ion) battery are known to greatly affect its performance, cycle life, and safety. In this study, we explore the heat generation behaviours of the tabbed and novel tabless designs of a 21,700 cylindrical cell with graphite anode and NCA/LiNi0.8Co0.15Al0.05O2 cathode, by coupling the discreet layers of a three-dimensional (3D) disassembled electrochemical (EC) model with a two-dimensional (2D) axisymmetric heat transfer (HT) model. The respective heat generation mechanisms of each battery components of tabbed and tabless designs are first compared, and it is observed that the tabbed design generates significantly more heat than the tabless design, with the negative current collectors (NCC) in the tabbed design accounting for over 80 % of the total heats at 1C-rate. Also, the tabless design reduces the cell voltage drop due to its lower ohmic impedance and promotes a more homogenous cell temperature than the tabbed design. Next, the effects of particle size (ω) for the tabless design on the ohmic, reversible, and polarization heats of the battery’s electrodes are investigated at a high discharge rate of 10C, and the results show that polarisation heat decreases significantly in both electrodes as ω decreases. At the Negative Electrode (NE), the ohmic heating decreases initially as ω decreases because the battery is not drawing significant current. As the current drawn increases, Li-ion transport resistance also increases and at depth of discharge (DoD) = 36 %, a reverse in the trend is observed leading to an increase in Ohmic heating up to the end of life. In contrast, the ohmic heating at the Positive Electrode (PE) increases throughout the discharge process as ω decreases. For the reversible heat, the heat is negative in the NE side initially and fluctuates with ω towards the end of life (DOD = 88 %) when it changes from heat sink to heat source, whereas in the PE it remains unchanged for all ω throughout the discharge process. The resulting temperature drop is caused by the increase in the overall reversible heat sink effect in the NE side, as well as the weakened polarization heat in both electrodes. On the other hand, miniaturising the electrode thickness (η) causes a considerable decrease in ohmic heating in both electrodes resulting in larger temperature drops and elevated voltage curve. This study provides relevant insights in support of the development of battery thermal management systems (BTMS) for the tabbed and novel tabless batteries in a realistic environment.