Battery Dynamics Exploration: Insights and Implications of Relaxation Time in Electrochemical Impedance Spectroscopy

Understanding Li-ion batteries' dynamic and complex electrochemical behavior presents significant challenges in battery diagnostics and prognostics. To deal with these challenges, researchers rely on electrochemical impedance spectroscopy (EIS), which offers valuable insights into the electrochemical phenomena within the battery. This paper investigates the significance of resting or relaxation time in obtaining stable and reproducible EIS measurements. This paper identifies the impact of battery rest time by analyzing the voltage and temperature behavior for different impulse discharge rates at various battery states of charge (SOC) levels. In addition, the influence of test current level and battery rest time on EIS measurements is studied. Adequate rest time enables the battery to reach a stable equilibrium, minimizing transient effects and ensuring reproducibility. At the same time, optimal current amplitude selection enhances the signal-to-noise ratio and facilitates accurate impedance spectrum interpretation, minimizing the influence on the battery state. The findings of our study improve the accuracy and reliability of battery diagnostics and contribute to the understanding of battery system dynamics.