EIS-Based Technique for SOH Estimation of Lithium-Ion Batteries

This paper explores the application of Electrochemical Impedance Spectroscopy (EIS) for assessing the State of Health (SOH) of lithium-ion batteries (LIBs), with Coulomb Counting used as a reference for validation. EIS offers a non-destructive method to evaluate impedance and provides insights into parameters like charge transfer resistance (Rct), which correlates with SOH. Experimental results reveal a clear link between Rct and SOH, with fractional-order models (FOM) enhancing accuracy in capturing real-world battery complexities. Tests on five LIB cells demonstrated a strong correlation between EIS-based SOH estimations and reference values from Coulomb Counting, with minor deviations attributed to measurement errors and battery degradation. This study underscores the reliability of EIS for battery diagnostics and its potential for energy storage applications.