(Invited) In Situ Measurement of Temperature Distributions in Lithium-Ion Cells Under Extreme Conditions for Failure Analysis

Abstract

Lithium-ion (Li-ion) batteries are susceptible to failures, even thermal runaway, when operating under extreme conditions that exceed safety limits, such as overcharge, overheating and short circuit. Temperature plays an important role in such failures due to its interaction with electrochemical reactions and heat generation (1). With very low thermal conductivity of battery materials (2, 3) and typically non-uniform heat generation under such extreme conditions, the local temperatures inside Li-ion cells can be very different from surface temperature. In situ measurement of temperature distributions in Li-ion cells can be therefore very useful for safety and failure analysis. Various efforts have been reported in measuring Li-ion cells internal temperatures with insightful findings obtained, typically using embedded thermocouples (4-18), RTD (19, 20) or fiber optic sensors (21-23), or via electrochemical impedance (24-27). But most of these studies only address normal operating conditions. In the few studies that address extreme conditions, only one internal temperature sensor was embedded (4, 10, 18), providing very limited information. In this research temperature distributions in Li-ion cells under extreme conditions are measured for detailed failure analysis. The progress will be reported in the presentation.