Determination of Internal Temperature Differences for Various Cylindrical Lithium-Ion Batteries Using a Pulse Resistance Approach

Abstract

The temperature of lithium-ion batteries is crucial in terms of performance, aging, and safety. The internal temperature, which is complicated to measure with conventional temperature sensors, plays an important role here. For this reason, numerous methods exist in the literature for determining the internal cell temperature without sensors, which are usually based on electrochemical impedance spectroscopy. This study presents a method in the time domain, based on the pulse resistance, for determining the internal cell temperature by examining the temperature behavior for the cylindrical formats 18650, 21700, and 26650 in isothermal and transient temperature states for different states of charge (SOCs). A previously validated component-resolved 2D thermal model was used to analyze the location of the calculated temperature TR within the cell, which is still an unsolved question for pulse resistance-based temperature determination. The model comparison shows that TR is close to the average jelly roll temperature. The differences between surface temperature and TR depend on the SOC and cell format and range from 2.14K to 2.70K (18650), 3.07K to 3.85K (21700), and 4.74K to 5.45K (26650). The difference decreases for each cell format with increasing SOC and is linear dependent on the cell diameter.