Simultaneous Sensing of Temperature and Bi-Directional Strain in a Prismatic Li-Ion Battery

Abstract

Thermal and pressure stability of Li-ion batteries (LiB) are the most important parameters for safety. In abuse operating conditions, the rapid increase of temperature and pressure can cause the appearance of hot-spots, which may lead to an increasing degradation rate or even to the battery’s explosion and/or combustion. A sensing network of fiber Bragg gratings is attached to the surface of a prismatic LiB to monitor its temperature and bi-directional strain variations through normal charge (0.70 C) and two different discharge rates (1.32 C and 5.77 C) in the x- and y-directions. More significant variations are registered when the LiB operates in abnormal conditions. A maximum temperature variation of 27.52 ± 0.13 °C is detected by the sensors located close to the positive electrode side. Regarding strain and consequent length variations, maximum values of 593.58 ± 0.01 µε and 51.05 ± 0.05 µm are respectively obtained by the sensors placed on the y-direction. The sensing network presented can be a solution for the real-time monitoring, multipoint and in operando temperature and bi-directional strain variations in the LiBs, promoting their safety