A comprehensive analysis and experimental investigation for the thermal management of cell-to-pack battery system

Driving range has become one of the primary issues restricting the electric vehicle development, which requires more battery energy to be filled in the pack volume. However, it is challenging to continuously to enhance the specific energy of battery. Compact pack structure can further enhance the specific energy of the pack, such as the cell-to-pack (CTP) design. Compared with the traditional design structure, the CTP battery system omitted the small module components, which directly increased the volume energy density by 15%-20%, making an essential breakthrough in pack specific energy. The thermal performance of the CTP battery pack gradually emerged in applications. Thermal performance analysis for the CTP battery system has become a critical factor restricting the large-scale application. This paper carries out the primary work is for the digital twin modeling of the CTP battery system. An accurate thermal model of cells and the battery pack with a liquid plate structure is established based on measuring the heating characteristics and thermo-physical parameters. After calibration, the thermal model can not only predict the temperature response of CTP system under fast charging and cooling conditions, but also further guide the development of other battery systems. The calculation error of the CTP thermal model is controlled within ± 15% under various operations compared with the experimental results. The proposed thermal model synchronizes with the battery pack test, significantly enhances the efficiency of battery system design, providing guidance for the thermal characteristics analysis, design, and optimization of CTP pack thermal management systems.