Contactless sensor for real-time monitoring of lithium battery external short circuit based on magnetoelectric elastomer composites

The frequent accident due to external short circuit of lithium-ion batteries in electric vehicles have prompted people to develop sensing technology to achieve early warning. However, the limited space and high temperature in highly integrated lithium-ion battery packs present significant challenges for current sensors to achieve external short circuit monitoring with high structural flexibility and heat resistance. In this study, a piezoelectric elastomer is designed and blended with magnetostrictive ferric tetroxide to prepare the LMPE/Fe3O4 magnetoelectric current sensor (LMPE/Fe3O4 MCS). The amorphous structure and low modulus of the piezoelectric elastomer enable the LMPE/Fe3O4 MCS to exhibit large deformability over 50 % elongation, and the non-ferroelectric LMPE and ferric tetroxide with high Curie temperature offer the LMPE/Fe3O4 MCS with high heat resistance over 150 °C. Meanwhile, the excellent interfacial interaction between the piezoelectric elastomer and the ferric tetroxide eliminates stress transfer loss between the interface, presenting outstanding magnetoelectric response and excellent linearity (>0.99) with current sensitivity of 5.975 mV A−1. The LMPE/Fe3O4 MCS can achieve real-time monitoring and early warning for external vibration and short circuit during the charging and discharging process of lithium batteries, which shows promising solutions for the safety improvement of electric vehicles.