Flexible Magnetoelectric Device Based on VB2/PVDF/Metglass for Real-Time Monitoring of External Short Circuits in Lithium-Ion Batteries

Lithium-ion batteries are susceptible to external short-circuit (ESC) faults during charging and discharging, which induce a sudden current surge and a consequent drastic change in the surrounding magnetic field, posing a serious threat to battery safety. In this study, a VB2/PVDF-TrFE/Metglass magnetoelectric device was developed for real-time monitoring of ESC faults. By optimizing the VB2 doping ratio, the composite film with 7 wt% VB2 exhibited the highest β-phase content (Fβ = 88.03%) and optimal piezoelectric performance. After integration with Metglass, the device demonstrated stable magnetoelectric response within 0–12 kHz, with optimal performance at 11 kHz. It responds to ESC events with high sensitivity and accuracy, delivering stable signals upon each trigger and release without omission, with response times of 0.64 ms and 0.52 ms. The device is self-powered and flexible, enabling magnetic-field-to-voltage conversion without an external power supply. These results indicate its promising potential for early warning and online monitoring of external short-circuit faults in batteries.