Thermoplastic-based composite embedding printed strain gauges for real time monitoring of battery casing deformations

Abstract The main critical indicators that ensure nominal batteries performances are energy storage density, charging capability and lifetime. These performances depend on the thermal conditions of use, the thermal history and the potential mechanical damages to the battery system. Over-heating of Li-Ion Batteries (LIBs) due to over-voltage or over-current during use or charging may induce irreversible battery degradation, and even battery integrity. The primary function of the battery casing is to protect the battery cells against potential ground impacts. Besides, being generally located underbody, recurrent stone impacts and/or shocks can affect the battery casing mechanical integrity. It is therefore essential to monitor the integrity of the casing with dedicated sensors placed in critical areas, in order to optimize the lifetime of the battery-casing system. From an eco-circularity perspective, recording the deformations of composite-based casings can be highly valuable when considering their potential reuse. The ambition of this study is then to provide a lightweight battery casing with an integrated stress management to maximize the battery performance, safety, lifetime and reusability. In this context, printed strain gauges were designed and integrated into thermoplastic composite-based samples. Electrical measurements of the strain gauges signal variations were achieved using an experimental set-up that controlled the strain applied at different locations of the instrumented composite. Finite element-based mechanical simulations were also conducted to validate the magnitude of the deformations expected to be recorded by the printed gauges and to assess the potential of this instrumented casing for damage detection in LIBs.