Nondestructive Evaluation of LithiumIon Battery Health Using Low-Frequency Resonant Vibration

The structural integrity of lithium-ion batteries is crucial for safety and reliability, particularly in electric vehicles and energy storage systems. Electrical diagnostics alone often cannot reveal internal defects such as delamination, lithium plating, or layer separation, particularly after mechanical impacts. This study introduces a nondestructive evaluation (NDE) method based on low-frequency resonant vibration (LFRV) using a shaker and a laser Doppler vibrometer. Four groups of commercial LiFePO4 battery packs, including healthy, aged, and mechanically impacted samples at different states of charge, were tested under controlled excitation. The measured vibration spectra were used to extract features, including peak frequency, spectral centroid, and energy-related metrics. These features were reduced and visualized using principal component analysis (PCA) to identify differences between battery conditions. PCA separated damaged and healthy packs with strong clustering, demonstrating the sensitivity of the vibration-based features to internal structural changes. The proposed LFRV method, combined with statistical pattern recognition, offers a fast and noninvasive approach for assessing battery health and post-impact screening.