A robust ultrasonic characterization methodology for lithium-ion batteries on frequency-domain damping analysis

Recently, non-invasive ultrasonic-based detection has emerged as a powerful tool to estimate the state-of-charge (SOC) and state-of-health (SOH) of lithium-ion batteries with a promising accuracy and efficiency. However, the currently available non-invasive methodology is highly sensitive to experimental setups and conditions, leading to unpredictable and unstable results. To this end, from a more fundamental stress wave propagation perspective, we discover that the quantified change of ultrasonic damping can be an intrinsic physical quantity to correlate with the state-of-charge (SOC) of batteries. We employ time-harmonic waves with different frequencies to obtain the steady-state dynamic response of lithium-ion batteries at various SOCs and a quasi-periodic energy gap can be observed. A mesoscale physics-based model of lithium-ion batteries is established to explain the observed energy gap carrying the multiple reflections of ultrasonic waves within the multi-layered structure of the cell. Finally, the change of ultrasonic damping with SOC is quantified for fast and accurate SOC prediction based on the frequency-domain damping analysis. Results underpin a robust and accurate frequency-domain ultrasonic characterization methodology for batteries and highlight the promise of the fundamental understanding of wave propagation for advanced characterization of batteries.

Automated summary

Recently, non-invasive ultrasonic-based detection has been proven to be an accurate and efficient tool for estimating the state-of-charge (SOC) and state-of-health (SOH) of lithium-ion batteries. However, the current non-invasive methods are highly sensitive to experimental setups and conditions, resulting in unpredictable and unstable results. A new approach using quantified change of ultrasonic damping has been discovered to correlate with the SOC of batteries, providing a more fundamental understanding of wave propagation.