Suggested Citation:
Eze, Chika, Jingyuan Zhao, Huaqiang Liu, Yu Shi, Dukhyun Chung, Jiyun Zhao, Guanhua Chen, Abel Chuang (2025)

Coupled Electrochemical-Thermal Analysis of the Novel TESLA-Type Large Format 4680 Cylindrical Lithium-Ion Battery Under Normal and Extreme Conditions

The novel TESLA's large format (LF) 4680 tabless cylindrical lithium-ion battery (LIB) represents a significant advancement in battery technology, promising higher energy density, faster charging capabilities, and reduced costs compared to the traditional LIBs used in current electric vehicles (EVs). Despite the above advantages, the tabless 4680 cell is particularly vulnerable to thermal safety hazards due to its higher energy storage capacity and poor heat dissipation performance resulting from a reduced surface-to-volume ratio. To address this concern, we develop an unrolled 3D electrochemical (EC) model coupled with a 2D axisymmetric heat transfer (HT) model for a tabbed 21700 cylindrical LIB, and utilize this to create the corresponding Tabless designs by modifying the 21700 tabs into continuous layouts, and scaling up and down to the tabless 4680 and 18650 cells respectively, enabling a comparative analysis of the coupled EC-HT performances of the three cell types under normal and extreme conditions. At a standard ambient temperature of 25 °C, the voltage curves and total volumetric heat profiles of all three cell types align across discharge currents ranging from 0.1C to 4C rates. This alignment is attributed to the cell's tabless design, which reduces internal resistance and enhances current distribution. In contrast, their corresponding temperature profiles differ significantly, which demonstrates that although all cells generated total heats at the same volumetric rate, the 4680-cell reached highest maximum temperature (MT) and temperature differentials (TD) due to its lower heat dissipation capacity relative to the other cell types. At subzero ambient temperature (−25 °C), the voltage drops below terminal voltage at 1C-rate for 18650, 21700 and 4680 cells occur at depth of discharge (DoD) of 56 %, 58 %, and 72 %, respectively, which suggests lower capacity degradation of 4680 cells, attributed to reduced Li-ion ohmic, and concentration overpotentials. At a high discharge rate of 4C, all cells exhibit similar capacity degradation with a sharp voltage drop below the terminal voltage at the early stage of discharge process (DoD = 6.4 %). Finally, various battery thermal management systems (BTMS) designs for LF 4680 cell were explored for a discharge protocol of 4C. And we find that increasing coolant's heat transfer coefficient (HTC) only helps to reduce overheating while worsening temperature non-homogeneity. On the other hand, increasing radial thermal conductivity (k_radial) may help to lower both overheating and temperature non-homogeneity. While the optimal cooling architecture is a combined “top and bottom” cooling approach. This study provides new insights into the EC-HT performance evaluation and BTMS designs of the LF 4680 cell for current and next-generation EVs.