Phase change material properties identification for the design of efficient thermal management system for cylindrical Lithium-ion battery module

Performance and life of Lithium-ion battery packs in EVs and energy storage applications are limited by the thermal profile of cells during its life. Passive cooling technique based on Phase Change Material (PCM) is employed for mitigating thermal issues associated with Lithium-ion cells. The challenge with PCM materials is the trade-off between its latent heat of fusion, thermal conductivity and specific heat. Detailed CFD analysis is carried out to study the impact of PCM thermal properties on battery pack thermal profile and provide guidelines for PCM properties selection and usage of existing PCM materials. Impact of critical PCM properties such as latent heat (100-250 kJkg-- 1 ), thermal conductivity (0.2-23 Wm-- 1 K- 1 ), melting temperature and thickness of PCM material on thermal performance of a battery module during rapid discharge rate of 25 A (3.2C) is investigated. Battery module maximum temperature (Tmax) max ) reaches 54 degrees C and temperature difference (Delta T) Delta T) to 5.5 degrees C while operating at 35 degrees C with 124 kJkg-- 1 and 0.2 Wm-- 1K- K- 1 . It is found that, PCM with higher latent heat (>= 175 kJkg-1),- 1 ), thermal conductivity (>= 3 Wm-- 1 K- 1 ), PCM thickness (>= 3 mm) and appropriate phase change temperature (41- 44 degrees C) exhibit improved heat dissipation for high discharge rates by effectively reducing the T max to 44.4 degrees C and Delta T to 2.4 degrees C (25 A and 35 degrees C ambient). Further, ways to mitigate low latent heat capacity and thermal conductivity of PCM through increasing PCM material usage (i.e. inter cell distance) is emphasized. Results of the present study can be considered as a design tool for PCM development engineers which could be cost effective both in-terms of development time and effort.