Drexel Researchers Develop Ultrasound Technique to Diagnose Battery Failures Before They Happen

Spotting Bad Batteries Before They Malfunction
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A recent increase in battery-related fires has highlighted the difficulty in identifying defects that can lead to catastrophic failures, which are often not visible to the naked eye. To address this issue, researchers from Drexel University have developed a standardized testing process aimed at providing manufacturers with deeper insights into the internal mechanics of batteries.

In a paper published in the journal Electrochimica Acta, the research team introduced methods that utilize ultrasound technology to monitor both the electrochemical and mechanical functions of batteries. This approach allows for the immediate detection of any damage or flaws that could result in overheating or even trigger a phenomenon known as “thermal runaway.”

“Although lithium-ion batteries have been studied for nearly fifty years and have been commercially available for over thirty years, we have only recently developed tools capable of providing high-resolution internal views,” stated Wes Chang, PhD, assistant professor and primary investigator at the Battery Dynamics Lab in Drexel’s College of Engineering. “Ultrasound has only been adapted for battery diagnostics in the last decade, drawing techniques from fields like geophysics and biomedical sciences. There is a significant need to educate battery engineers on how this technology works and its advantages.”

The team’s recent efforts aim to achieve this by showcasing a cost-effective, accessible benchtop ultrasonic tool designed for easy implementation by battery engineers, particularly those in the automotive sector focused on electric vehicle production.

According to a report from Consumer Affairs, individuals use three to four battery-powered devices daily—ranging from laptops and smartphones to electric bikes and scooters—and this number has doubled over the past five years. The rapid demand for batteries has created a market that prioritizes speed and cost, raising concerns about allowing low-quality cells to enter circulation.

“While most lithium-ion batteries today are safe and perform well, defects are inevitable when thousands of cells are utilized in electric vehicles and millions of these vehicles are produced annually,” Chang noted.

Current safety and quality control measures for manufactured batteries heavily rely on visual inspections and performance tests of selected battery cells post-production. X-ray imaging may also be used to create high-resolution images of a battery’s internal structure, but this method is both slow and costly. Although manufacturers must adhere to these inspection protocols, the sheer volume of battery production means that even minor design or manufacturing flaws can lead to significant batches of defective batteries reaching the market.

In contrast, the method proposed by the Drexel team employs acoustic imaging—ultrasound—which is both faster and less expensive than X-ray techniques while providing complementary insights into the mechanical properties of batteries. The researchers utilized scanning acoustic microscopy technology to transmit low-energy sound waves through commercial pouch cell batteries. The speed at which these waves travel changes as they move through different battery materials, enabling researchers to obtain a quick, comprehensive view of the chemical modifications occurring within the battery during use.

“By analyzing how the sound waves change when they interact with the sample, we can infer numerous structural and mechanical characteristics,” the report states. This process aids in identifying structural defects that could lead to electrical shorts, material deficiencies that might impair performance, and signs indicating potential future problems.

One material that the scanning method excels at detecting is gas, which is crucial because gas presence within a battery signifies dry areas that could result in cell failure during operation. The ultrasound technique’s sensitivity not only allows for the detection of manufacturing defects but also helps assess how new battery chemistries might fail in research and development settings.

As part of their research, Chang’s team collaborated with SES AI, a startup specializing in lithium metal batteries. Implementing the testing platform at SES AI’s research and development facility provided engineers with immediate access to data during the design and testing phases, facilitating quicker adjustments and corrections.

In addition to detailing their ultrasound testing process, the team created open-source software to operate the instrument and swiftly analyze the data generated. “By lowering the barrier to entry, we hope that ultrasonic testing can become a standard practice in battery research and development,” Chang remarked. “Battery scientists are focused on developing better batteries rather than new tools. We provide an easy-to-use interface with regular software updates, adding to the array of tools available for measuring and diagnosing next-generation battery performance.”

The research team intends to enhance the technology further, aiming to facilitate scans of battery electrodes and cells while producing more detailed three-dimensional images, moving beyond the current limitations of two-dimensional scans for more effective defect detection. This research was supported by a grant from SES AI.

Sam Amsterdam, PhD, a postdoctoral researcher at Drexel University, conducted the studies and authored the manuscript.

Read the full paper here: [Electrochimica Acta](https://www.sciencedirect.com/science/article/pii/S0013468625003755)