Listening to batteries helps scientists decode faint sounds

"When lithium-ion batteries degrade, they emit acoustic signals that reveal what's going wrong inside. Now, MIT researchers say they've figured out how to interpret those sounds, and the subtle creaks and pops that come before major failures, to help predict problems before things go up in smoke. Led by MIT chemical engineering and mathematics professor Martin Bazant, the team's recently published findings suggest that it doesn't take much more than listening to the groans of a Li-ion battery to determine precisely what's going on inside."

""We were able to classify [acoustic emissions] as coming from gas bubbles that are generated by side reactions, or by fractures from the expansion and contraction of the active material, and to find signatures of those signals even in noisy data," Bazant told MIT News. In order to determine which sounds indicated what type of failure, Bazant and his team attached microphones to Li-ion batteries and ran them through charge and discharge cycles while also monitoring their electrochemical states."

Lithium-ion batteries emit characteristic acoustic signals as they degrade, with different sounds corresponding to distinct failure mechanisms such as gas bubble formation or fractures from material expansion and contraction. Simultaneous recording of acoustic emissions and electrical/electrochemical measurements allows correlation of specific sound patterns with electrical states and failure conditions. Distinct acoustic signatures can appear well before thermal runaway, and signal processing can extract those signatures from noisy data. Acoustic monitoring provides a noninvasive method to classify failure types and offers potential for early warning and improved safety management of Li-ion cells.

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