Detection of Internal Defects in Lithium-Ion Batteries Using Lock-in Thermography

Thermal imaging is an established technique for studying temperature distribution with high spatial resolution; however, lock-in thermography offers the ability to identify heat transfer mechanisms and internal defects. Here, for the first time, lock-in thermography is applied to Li-ion batteries to investigate the effect of periodic electro-thermal stimulation on the amplitude and phase response of both new and aged Li-ion pouch cells. We demonstrate the effectiveness of this technique in the detection of gas pockets formed during cell aging, and propose its application in the identification of internal defects in operational systems and validation of thermal models. (C) 2015 The Electrochemical Society. All rights reserved.