Reviewed by Frances BriggsJun 26 2025
Researchers from Drexel University have created a standard testing procedure to provide manufacturers with a better understanding of the internal workings of batteries.
Image Credit: Kinek00/Shutterstock.com
Published in Electrochimica Acta, the study aims to prevent the hazardous errors that can lead to batteries overheating and catching fire.
A recent spike in battery-related fires has highlighted the difficulty of spotting flaws in their production. Rarely visible to the naked eye, these flaws can lead to serious battery malfunctions.
The research team has examined ultrasonography as a potential technique to track a battery's mechanical and electrochemical processes, making it easier to detect early signs of damage or failure, such as the onset of thermal runaway.
While lithium-ion batteries have been studied for nearly half a century and commercialized for over 30 years, we have only recently developed tools that can see inside with high resolution. In particular, ultrasound has been adapted from other fields, such as geophysics and biomedical sciences, for battery diagnostics only in the past decade.
Because it is such a new technique in the battery and electric vehicle industries, there is a need to teach battery engineers how it works and why it is useful.
Wes Chang, PhD, Assistant Professor, Project Supervisor and Primary Investigator, Battery Dynamics Lab, College of Engineering, Drexel University
The team has showcased an inexpensive, easily accessible benchtop ultrasonic tool that it believes battery engineers could easily use to assess battery performance. This could even be used by electric vehicle manufacturers.
According to a Consumer Affairs report, people use three to four battery-operated electronic devices every day, a number that has doubled in the past five years. These devices range from laptops and tablets to power tools and electric vehicles.
With consumers using more battery-powered devices than ever before, the pressure to produce batteries quickly and inexpensively has increased. However, Assistant Professor Wes Chang warns that this could lead to the proliferation of low-quality cells in the market.
While the vast majority of lithium-ion batteries today are high performing and safe, defects are bound to exist when thousands of cells are used within electric vehicles and there are millions of electric vehicles being produced every year.
Wes Chang, PhD, Assistant Professor, Project Supervisor and Primary Investigator, Battery Dynamics Lab, College of Engineering, Drexel University
As part of current safety and quality control protocols in battery manufacturing, individual battery cells undergo visual inspection and performance testing after they are removed from the assembly line. X-rays can also be used to obtain high-resolution interior images of batteries, although this process is costly and time-consuming.
Although manufacturers must adhere to these testing and inspection procedures, given the volume of batteries used, even a minor manufacturing or design error could result in many faulty batteries reaching the market.
The team used ultrasound and acoustic imaging to analyze batteries, which is quicker and less costly than X-rays, and can offer additional details regarding the battery's mechanical characteristics. Using scanning acoustic microscopy, low-energy sound waves are passed through a commercial pouch cell battery.
As the waves travel through the different materials inside a battery, their speed changes without affecting its internal operations or performance. This enables researchers to quickly and thoroughly examine the chemical changes that occur in battery materials while they are being used.
By observing how the sound waves change after interacting with a sample, the researchers could deduce the battery's structural and mechanical properties. This method can observe material deficiencies or imbalances, structural flaws, and damage caused in production.
The ultrasound is particularly good at identifying gas, which is significant because gas inside a battery is a sign of dry spots that could cause the cell to fail while it is being used. Its sensitivity also makes it helpful in assessing how new battery chemistries fail in R&D labs as well as for identifying manufacturing flaws.
In collaboration with lithium metal battery maker SES AI, the team implemented their ultrasound system at SES’s R&D facility. This allowed engineers to access real-time data during design and testing, speeding up adjustments and troubleshooting.
In addition to their ultrasound testing tool, the team created open-source software to operate the device and generate a quick analysis of the data obtained.
We hope that by lowering the barrier to entry, ultrasonic testing can become a routine part of battery research and development. Battery scientists want to build better batteries, not develop new tools. We provide a user interface that is easy-to-use with regular software updates. This adds to the existing collection of tools that battery scientists have on hand for measuring and diagnosing next-generation battery performance.
Wes Chang, PhD, Assistant Professor, Project Supervisor and Primary Investigator, Battery Dynamics Lab, College of Engineering, Drexel University
To better identify flaws in battery manufacturing, the team intends to keep improving the technology to scan battery electrodes and cells more readily. They also hope to generate more detailed three-dimensional images, as opposed to the current scans, which are restricted to two dimensions.
Journal Reference
Amsterdam, S., et al. (2025). Design of a low-cost ultrasonic testing instrument for battery metrology. Electrochimica Acta. doi.org/10.1016/j.electacta.2025.146012.