Use of acoustic emission for Lithium-ion battery to identify defects, overcharging, and swelling

In the past two decades, the use of lithium-ion batteries has considerably increased in different sectors ranging from small electronic gadgets to large transport vehicles. In addition, battery reuse has also gained attraction in many areas, most notably the energy and automobile industries. Despite the presence of multiple safety barriers found in modern batteries, battery related accident reports are overrepresented, and therefore safety remains a huge concern. To address the concern related to battery safety and based on knowledge gap in literature, this study investigates the use of acoustic emissions (AE) to identify battery defects and detect precursors of battery fire such as overcharging and swelling. Testing was performed in two phases. In the first testing phase, lithium-ion cells in good, swollen, and exposed to salt water was tested to identify battery defects. An active AE sensing system, with an ultrasound sensor, was used to excite the lithium-ion cell and trigger elastic waves. In the second testing phase, a passive AE sensing system was used to detect overcharging and swelling. From the recorded AE signal in both experimental phases, condition indicators were calculated to identify battery defects and to detect onset of overcharging and swelling. The root mean square feature calculated from the AE signal showed good repeatability in identifying the battery health condition, onset of overcharging, and swelling. This study lays a strong basis for the battery industry to use AE as an additional safety barrier to assess battery health condition and to detect overcharging.