Engineering 101

Freezing Lithium-Ion Car Batteries Makes Them Safe to Transport

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One of the reasons it took so long to develop workable lithium-ion batteries for cars was the inherent instability of lithium, especially during charging. Metallic lithium plating that can occur during extreme temperature fluctuations means that damaged and defective lithium ion car batteries are hard to transport. Legislation dictates they have to be placed within an explosion proof box which costs thousands of pounds to be transported.

This makes transporting damaged and defective car batteries an expensive process. However researchers from Warwick Manufacturing Group (WMG) at the University of Warwick, in collaboration with Jaguar Land Rover engineers, have been able to freeze batteries with liquid nitrogen.

An explosion proof box to transport a typical Tesla-sized battery costs €10,000 and a further €10,000 for the UN accreditation. The ability to transport them in plastic containers which cost a couple of hundred pounds has been made more accessible thanks to researchers from WMG at the University of Warwick.

The researchers highlighted that cryogenic freezing does not reduce lithium ion battery’s energy capacity or affect cycle or service life, and could be transported in a safer way.

As the sales of electric vehicles increases, there is more concern for the transportation of damaged and defective lithium ion battery packs. Explosion boxes are used to contain the battery in case it goes into thermal runway, an overheating condition which can lead to violent explosions and toxic gases being released. However being able to cryogenically flash freeze the batteries completely removes the risk of an explosion, and could therefore mean they can be transported safely in a plastic box.

Researchers who were part of the ELEVATE project funded by ESPRC, Catapult and supported by Jaguar Land Rover tested the batteries’ activity before they froze cells with liquid nitrogen and after. They also drove nails through the frozen cell to test their safety of them, and managed to show that their performance was not affected after freezing.

When being transported batteries will have to be kept in a lorry at -35°, however the amount of packaging is significantly less than explosion proof boxes, making the process more sustainable.

“Transporting damaged and defective batteries is an expensive and unsustainable process, however being able to freeze them with liquid nitrogen could save thousands of pounds and help electric vehicle manufacturers be more sustainable,” said Dr. Thomas Grandjean from WMG, at the University of Warwick. “We tested the batteries in the most extreme abuse conditions, such as driving nails through the cells and inducing external short circuits, proving that the freezing process is effective and safe.”

Source: University of Warwick

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