Lithium-ion (Li-ion) battery manufacturers must detect various physical flaws during production to ensure safe, reliable performance. Failure to detect even minute defects could lead to internal short circuits, overheating, fire, explosion, diminished function, costly product recalls, and serious reputation damage.
Today, the use of advanced Scanning Acoustic Microscopy (SAM) is an increasingly important technique to detect potential flaws in the manufacture of Li-ion batteries. SAM can quickly and effectively image the material forms and internal structures of up to 100% of batteries to identify areas where layers are improperly bonded or otherwise physically defective.
Early detection of flaws not only enables manufacturers to prevent defective products from entering the marketplace – reducing potential recalls, liability and reputational damage – but also facilitates design and production changes to eliminate future problems.
“Scanning Acoustic Microscopy is detecting any degradation or change in the mechanical properties of the Li-ion battery cell. For example, is it swelling or disbonding? The technology effectively monitors what the chemistry is doing to the mechanical construction of the package. This becomes critical as Li-ion battery production ramps up and there’s increasing variation in physical form factors,” says Hari Polu, President of OKOS, a Virginia-based manufacturer of Scanning Acoustic Microscopy (SAM) and industrial ultrasonic non-destructive (NDT) systems. OKOS, a wholly owned subsidiary of PVA TePla AG Germany, offers manual and automated inspection systems for batteries, flat panels, thin plates, circular discs, sputtering targets, and special alloys.
Scanning Acoustic Microscopy, acknowledged for its capability to identify defects as minuscule as 50-microns, is extensively embraced in the semiconductor industry as a metrology technology for failure analysis and reliability detection. Now the same high-speed technology is being applied to testing and failure analysis of Li-ion battery cells.
Manufacturers are increasingly integrating SAM inspection tools into their processes to catch defects at an early stage. For high volume operations, automated systems are also available that enable 100% inspection of battery cells, ensuring safety and performance.
According to Polu, effective testing for Li-ion battery flaws across the diverse form factors utilized requires both expertise in SAM technology as well as customization to the specific application. For some types of inspection, such as electric vehicle (EV) Li-ion batteries, an immersive type of SAM is proving effective. With this method, battery components are submerged in a fluid (typically water) to facilitate the transmission of ultrasonic waves during scanning.
“For thick battery packages like EV vehicles, we use relatively low-frequency, highly customized transducers to penetrate through the parts. The special transducers need to have very high surface penetration to a depth of approximately five millimeters while still maintaining resolution.,” says Polu. He notes that the utilization of special transducers and software enables efficient detection of Li-ion battery defects across a wide range of form factors.
As technology progresses, new variations and form factors of Li-ion batteries are emerging. Manufacturers across a wide range of industries that work with an expert provider of SAM, which can customize the technology to their specific application, will have an advantage in ensuring the safety, quality, and reliability of their products.
For more information, contact OKOS at [email protected] or visit www.okos.com. OKOS is a wholly owned subsidiary of PVA TePla AG, Germany.