Improving battery safety: reliable internal battery temperature calculation using EIS technology

To prevent thermal runaway in battery energy storage systems, accurate temperature monitoring is required. The inaccuracy with which typical surface temperature sensors portray inner battery temperatures may cause delays in detecting overheating. To overcome this, the battery's internal temperature (BIT) is determined using electrochemical impedance spectroscopy (EIS). This paper reviews four EIS-based BIT estimation techniques: phase shift (PoI), real part (RoI), imaginary part (IoI), and impedance magnitude (MoI). Based on studies with 28 batteries, it also makes recommendations for frequency settings that improve the accuracy of BIT estimates.