Spectral Characterstics of Active Wide-Band Acoustic Emission Signals for Lithium-Ion Battery Monitoring

The performance and safety of lithium-ion batteries (LIBs) critically depend on dynamic structural and interfacial changes within constituent materials (electrodes, electrolyte, separator) during electrochemical cycling. Understanding the evolution of microstructures and interfaces - particularly as functions of State of Charge (SOC) and State of Health (SOH) is essential for advancing Battery Management Systems (BMS). This study introduces a novel non-destructive method for inspecting LIB material properties using active acoustic interrogation and spectral analysis. The approach transmits swept-frequency acoustic waves into both parametrically designed 3D-printed samples (with controlled microstructural variations) and operational pouch-cell LIBs, analyzing the resulting acoustic emissions. Extracted spectral features reveal distinct correlations with specific material conditions in both sample types and pouch cells. These findings establish a frequency-domain framework for precise battery diagnostics, enabling potential visualization of dynamic material-property evolution throughout charge-discharge cycles.