EIS mimicking DC measurement technique: a novel path for battery aging analysis

Official URL: https://dx.doi.org/10.1002/est2.70229

Electrochemical impedance spectroscopy (EIS), an alternating current (AC) technique, is commonly employed to monitor the aging process of lithium-ion batteries (LIBs). However, its use requires sophisticated electrochemical equipment, which not only complicates battery management systems (BMS) but also raises overall costs. Moreover, analyzing EIS data often requires expert-level interpretation. In this study, we investigated the applicability of various direct current (DC) methods for tracking the total internal resistance (T-IR) during the aging process. We evaluated the accuracy of their potential use in estimating the State of Health (SoH). The performance of these DC methods was compared with classical EIS techniques to identify the most reliable conditions for accurate SoH estimation. Among the techniques explored, one method involved applying a low current to the battery and determining T-IR based on the real-time voltage response, thereby mimicking the EIS approach. This method demonstrated the highest accuracy compared to classical EIS results. Additionally, we evaluated the impact of high-DC pulses on T-IR and analyzed its variation with the state of charge (SoC), comparing these findings with EIS-derived data. Our results indicate that low-DC techniques not only provide reliable T-IR measurements but also offer a cost-effective and simpler alternative for SoH monitoring in BMS and laboratory applications. The EIS-mimicking low-DC approach, in particular, shows promise as a versatile tool for determining the T-IR of electrochemical cells under various operational scenarios.