Meaning
Non-destructive imaging technique utilizes high-frequency sound waves to visualize the internal microstructural features and defect distributions of solid-state materials. Ultrasonic acoustic microscopy detects internal delamination, voids and micro-cracks within solid-state electrolyte layers and electrode-electrolyte boundaries. This imaging method provides high-resolution cross-sectional and planar views of the internal structure without damaging the sample.
This non-destructive approach is particularly valuable for monitoring the evolution of internal defects during in-situ cycling of the cell under load.
Imaging Mechanism
Acoustic waves propagate through the sample and reflect at boundaries where there is a change in acoustic impedance. Air gaps or delaminated regions produce very high reflection coefficients, appearing as high-contrast zones in the resulting acoustic image. This high sensitivity allows the detection of sub-micron separations.
Quality Inspection
Battery manufacturers utilize this technology to inspect solid-state pouch cells after the hot-pressing stage of assembly. Identifying internal voids before cycling prevents the electrochemical testing of defective cells. This screening increases the efficiency of the research and development pipeline.
Sourcing Decision
Procurement of acoustic microscopy equipment depends on the required spatial resolution and the penetration depth of the transducer. High-frequency transducers offer excellent surface resolution but limited penetration into dense electrode materials. Selecting the correct transducer is essential for accurate defect characterization.
