A Generalized Ultrasonic Inspection Method for Batteries

The generalized ultrasonic inspection method harnesses piezoelectric transducers and ultrasonic resonance spectroscopy to detect sub-500-micron defects in batteries. By analyzing the resonance behavior of high-frequency sound waves and employing novel data processing techniques, subtle structural changes in batteries can be identified. Two hardware setups were developed: one employing direct transducer contact and another utilizing ultrasonic measurements through a captured water column. Both configurations incorporate a scanning technique that captures spatial degradation data – rather than a single point measurement – enabling structural insights even in layers too thin for time-domain c-scan resolution. Processing of the data includes converting the measurements and reference time domain signals to the frequency domain, then normalizing the measurement signal in the frequency domain to determine the frequency dependent reflection coefficient. As a result, resonance behavior between the test specimen and apparatus can be isolated. This resonance-based approach is ideal for delicate materials unsuitable for high-powered laser excitation or full immersion testing, and the associated data-analysis allows the battery defects to be detected more efficiently. This NASA invention offers significant potential for highly sensitive, nondestructive enhancements of battery safety and quality control in industries such as automotive, aerospace, additive manufacturing, and composites. Ultrasonic battery inspection is an innovative nondestructive evaluation (NDE) technique that leverages high-frequency sound waves to reveal subtle battery characteristics—ranging from internal defects and quality variations to estimations of State of Health (SoH) and State of Charge (SoC). Localized disruption or change in structure of internal components, such as electrodes, are a common and known mechanism for battery degradation. Conventional testing methods often struggle to detect minute degradation or delicate flaws without resorting to destructive approaches, such as high-power lasers. For both NASA and private sector organizations, the ability to noninvasively evaluate battery failure modes is essential for advancing battery design and ensuring safe, reliable operation. In response to this challenge, innovators at NASA’s Langley Research Center have developed a generalizable NDE ultrasonic inspection method to determine structural and material properties of a battery.