2023-11-04 21:10:00
How likely is it that an electric vehicle battery will ignite and explode on its own? According to some analyses, gasoline vehicles are almost 30 times more likely to catch fire than electric vehicles. Recent incidents of electric vehicles catching fire while parked have, however, raised questions among many consumers and researchers. How can these rare events occur?
Thermal leak: a well-known phenomenon
Researchers have long known that high electrical currents can cause “thermal leak» – a chain reaction that can cause a battery to overheat, catch fire and explode. However, in the absence of a reliable method for measuring currents inside a battery at rest, it has not been clear why some batteries enter thermal leakage, even when an electric vehicle is parked.
“We are the first to capture real-time 3D images that measure state of charge changes at the particle level inside a lithium-ion battery after it has been charged.” – said Nitash Balsara, Principal Investigator, Materials Sciences Division.
New imaging technique reveals local currents
Using an imaging technique called “ x-ray operando microtomography », scientists from the Lawrence Berkeley National Laboratory (Berkeley Lab) and UC Berkeley showed that the presence of large local currents inside batteries at rest after rapid charging could be one of the causes of thermal leakage.
“What’s exciting about this work is that Nitash Balsara’s group doesn’t just look at images – They use the images to determine how batteries work and change in time-dependent ways. This study is the culmination of many years of work,” added co-author Dilworth Y. Parkinson, scientist and deputy for photon science operations at Advanced Light Source (ALS) du Berkeley Lab.
3D microtomography experiments conducted at the Advanced Light Source allowed researchers to identify particles that generated current densities reaching 25 milliamps per square centimeter inside a battery at rest after rapid charging. For comparison, the current density needed to charge the test battery in 10 minutes was 18 milliamps per square centimeter. (Credit: Nitash Balsara and Alec S. Ho/Berkeley Lab)
Synthetic
This study provides surprising clues about rare incidents of thermal leakage inside a lithium-ion battery at rest. Researchers found that local currents inside a battery at rest after rapid charging were surprisingly large.
These findings could help develop improved safety protocols for electric vehicle batteries. However, much work remains to be done before this approach can be used for this purpose.
Main lessons
Key lessonsDetailsFire risk of electric vehiclesGasoline vehicles are nearly 30 times more likely to catch fire than electric vehicles.Thermal leakHigh electrical currents can lead to “thermal leakage” – a chain reaction that can cause a battery to overheat , catch fire and explode.Imaging techniqueAn imaging technique called “X-ray operando microtomography” has been used to measure the currents inside a battery at rest.Local currentsThe presence of large local currents at the Interior of batteries at rest after rapid charging could be one of the causes of thermal leakage. Implications These results could help develop improved safety protocols for electric vehicle batteries.
For a better understanding
1. What is “thermal leakage” in an electric vehicle battery?
The “thermal leakis a chain reaction that can cause a battery to overheat, catch fire and explode. It can be caused by high electrical currents.
2. Why do some electric vehicles catch fire while parked?
Large local currents inside the batteries at rest after rapid charging could be one of the causes of the thermal leak.
The researchers used an imaging technique called x-ray operando microtomography » to measure the currents inside a battery at rest.
4. What is “X-ray operando microtomography”?
It is an imaging technique that captures real-time 3D images and measures changes in state of charge at the particle level inside a lithium-ion battery after it has been charged. .
5. What are the implications of this discovery?
These findings could help develop improved safety protocols for electric vehicle batteries. However, much work remains to be done before this approach can be used for this purpose.
The information in this article comes from a study by scientists at Lawrence Berkeley National Laboratory (Berkeley Lab) and UC Berkeley, published in the journal ACS Nano.
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