We have known for a while that lithium-ion batteries produce sounds, although we can’t detect these with our human ears. However, scientists have been able to listen to what they describe as ‘bubbly noises’, using specialist equipment. Massachusetts Institute of Technology (MIT) engineers have found a way of hearing bubbles in batteries, that tell us more about what is happening inside.
What Do Bubbles in Batteries Tell Us?
Faint bubbly sounds in batteries are normal signs they are charging, discharging, and yes degrading too. However, until now, scientists have been unable to relate these warnings to more serious states in lithium-ion batteries.
These out of normal conditions could be warnings they are about to lose power, fail completely, or even catch fire. It goes almost without saying that we need to close this knowledge gap, in the interests of lithium-ion battery safety.
The MIT engineers’ new technique for hearing bubbles in batteries does just that, even when the sounds include irrelevant data. This could become the basis for user-friendly information in future:
- Imagine if future batteries incorporated simple, passive monitoring systems.
- And these systems alerted electric vehicle drivers and battery storage operators to imminent failure.
How MIT Engineers Heard Bubbles Clearly
The team managed to decode the acoustic emissions through careful scientific work. They discovered how to classify the sounds as coming from gas bubbles, generated by side reactions, or from fractures caused by expansion and contraction of active material.
These states are two primary mechanisms for lithium-ion battery degradation, leading to failure. Here’s a quick summary of how MIT engineers achieved their breakthrough:
- They compared the the results of electrochemical battery tests to the sounds they heard inside.
- Then they dismantled the batteries, and looked for signs of fracturing under an electron microscope.
These comparisons confirmed that MIT had indeed found a way to interpret warning signs of gas emissions. These emissions can be the first stages of thermal runaway leading to fires. “It’s like seeing the first tiny bubbles in a pot of heated water, long before it boils”, they compared thoughtfully.
More Information
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