A Novel Hybrid Battery Thermal Management System for Prevention of Thermal Runaway Propagation

Abstract

Lithium-ion batteries are extensively used in electric vehicles because of their high energy density and long service life. Designing a battery thermal management system (BTMS) that prevents thermal runaway propagation in the event of abusive accidents is crucial. The goal of this study is to design a novel hybrid BTMS with both active liquid cooling and passive cooling for preventing thermal runaway propagation in the battery module. A numerical model for a battery module (16 cylindrical 18650 cells) was developed in COMSOL multi-physics software to examine the thermal runaway propagation caused by a single cell. Copper foam and expanded graphite-paraffin (EG-PCM) composite material were used for passive cooling. In addition to the thermal runaway scenario, the thermal behaviors of the battery module with the hybrid BTMS were also evaluated under the 3C discharging and driving cycle circumstances. A conventional BTMS with natural air cooling is chosen as the baseline. The findings reveal that the proposed hybrid BTMS, which uses EG-PCM with a melting temperature of 52 °C and thermal diffusivity of 9.68 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /s and copper foam with a porosity of 0.7-0.9, is capable of limiting the maximum cell temperature below the thermal safety threshold (80 °C) to prevent thermal runaway propagation. Under the NEDC load cycle, the battery module can be maintained within an optimal working temperature range by passive cooling only. By applying active liquid cooling with a flow rate of 0.3 m/s for BTMS, the average temperature reduction of the battery module at a 3C discharging rate can be up to 72.5% and 52.7% compared to passive cooling with copper foam and EG-PCM, respectively. The study highlights that the combination of active liquid cooling and appropriate passive cooling is an efficient thermal management solution for Li-ion battery applications in electric vehicles, notably in the consideration of thermal safety.