Development of Dual Temperature Sensing Approach for In-situ Temperature Monitoring of a Lithium-ion Battery

Battery temperature is one of the primary indicators for monitoring battery operation and safety, which has a significant impact on battery performance. Currently, the battery internal temperature monitoring is mainly divided into two situations: normal operation and thermal runaway. The former requires sensors to have relatively high accuracy, while the latter requires sensors to have sufficiently wide temperature measurement range. However, high-accuracy sensors are often accompanied by a narrow temperature measurement range, while sensors with a wide temperature measurement range have relatively low accuracy. This results in the inability of current cell instrumentations to accommodate temperature monitoring across multiple battery states. Our study proposes a novel dual-sensor temperature measurement system that integrates a T-type thermocouple and a K-type thermocouple inside the same commercial cylindrical cell for simultaneous accurate and wide-range temperature sensing, to meet the temperature measurement requirements of different battery applications and scenarios. We found that instrumentation did not adversely affect battery performance. We also compared and quantified the temperature monitoring capabilities of T -type thermocouples and K-type thermocouples in the range of 15–60 °C. The radial temperature gradient collected by the T -type thermocouple was 3.78 °C, which was 0.79 °C higher than that of the K-type thermocouple at the end of 1.4C discharge. The linear relationship between the radial temperature gradient and the discharge rate and ambient temperature obtained from T-type thermocouple has a larger slope than that from K-type thermocouple. During thermal runaway testing, K-type thermocouple could well capture the internal peak temperature without being damaged.