There is a significant need for integrated solutions in lithium-ion batteries that provide both preventive and containment strategies for thermal runaway without compromising the battery's performance or design efficiency. The risk of thermal runaway in li-ion batteries is an inherent challenge due to their electrochemical nature.
'Polymer mini-channel cold plates', is one such cutting-edge solution researched and demonstrated by Graichen H-C et. al. (2023) to mitigate the risk of thermal runaway while maintaining the battery's thermal efficiency. These cold plates use a polymer material that is lightweight, space-efficient, and, importantly, exhibits characteristics beneficial for both heat dissipation & as a thermal barrier. The design involves indirect liquid cooling through mini-channels, allowing for effective heat removal from the battery's surface.
Thermal runaway tests were conducted using NMC pouch cells (12.5Ah), subjecting them to overcharging to find out the impact of polymer mini-channel cold plates. Here are the key takeaways:
1) Without Cold Plates: In the absence of any cooling mechanism, thermal runaway and subsequent propagation occurred swiftly within an hour of overcharging.
2) With Cold Plates: Incorporating the mini-channel cold plates significantly altered the trajectory of thermal events. Notably, in scenarios with active thermal management, the batteries avoided reaching a critical thermal runaway state within the same time frame. The system effectively delayed the onset of hazardous conditions by dissipating heat and serving as a thermal barrier.
The polymer-based mini-channel cold plates demonstrated peak performance, significantly slowing down the process chain leading to cell firing & effectively preventing propagation to adjacent cells, even when the thermal management system was intentionally malfunctioned to simulate a worst-case scenario.
The incorporation of polymer-based mini-channel cold plates into li-ion battery systems marks a significant step forward in thermal management & safety. The findings suggest that this technology can effectively delay and potentially prevent the occurrence of thermal runaway in large aspect-ratio battery cells. It offers a promising avenue for enhancing the safety of li-ion batteries without compromising their energy efficiency or design compactness.
The technology opens new pathways for safer battery designs, particularly in high-stake applications like EVs & large-scale energy storage systems. Further research can expand on the foundation laid by this study, exploring variations in polymer materials, channel geometry & integration with different cell types & formats.