Abstract:

A two-dimensional simulation model was established based on a pseudo-two-dimensional (P2D) theory to explore the inconsistency performances of large-format lithium-ion power batteries. The potential distribution and boundary conditions in the current collector region was introduced in the model to analyze electrical performance such as the rate capacity, the capacity utilization rate, the resistance, and the local lithium plating to model electrodes with the length from 10 cm to 150 cm. The results show that the voltage loss of the positive current collector reaches 0.1 V at 3 C rate for a 100-cm electrode, the charging capacity utilization rate drops to 82.2 %, and the normalized polarization internal resistance of a 100-cm battery is nearly twice as big as that of a 10-cm battery; For the 100-cm battery, local lithium plating occurs at 85 s during the charging process due to non-uniform current density; and the temperatures at the two tab-area are 8.6 K higher than that at other area due to high current density. Therefore, the optimizations of battery structural design and the thermal management system are urgently required for large format lithium-ion batteries.

Key words: large-format lithium-ion power batteries, inconsistency performances in battery, capacity utilization rate, current density, local lithium plating