In situ and real-time monitoring of the internal temperature, pressure, and current of lithium-ion batteries for long cycle life safety using a flexible multi-parameter sensor array

Abstract

The frequent incidents of thermal runaway in lithium batteries have accelerated the development of sensing technologies to ensure service safety by monitoring specific parameters. However, current external sensors exhibit response delays and low accuracy, while internal sensors lack a multi-parameter monitoring function due to limited implantable space and low integration density. This study developed a flexible multi-parameter sensor (FMS) by integrating sensing materials, including a thermo-sensitive metal film, pressure-sensitive carbon nanofiber/polyester elastomer composite film (CNF/PBDSE), and magnetic-sensitive Fe₃O₄/polyester-based elastomer (Fe₃O₄/LSIB), on a flexible printed circuit (FPC). The FMS is implanted into a lithium battery to achieve simultaneous monitoring of internal temperature, pressure and current, with a temperature measurement range of –20–80 °C with 1.2%FS accuracy, pressure measurement range of 0–1 MPa with 4%FS accuracy and current measurement range of 0–2.5 A with 5%FS accuracy. Monitoring of internal temperature, pressure and current using FMS can effectively detect the risks of thermal runaway, swelling and short circuits in lithium batteries. Meanwhile, the FMS shows almost no influence on the cyclic performance of the battery, with the 6Ah battery exhibiting only 0.62% and 2.06% lower coulombic efficiency and capacity retention, respectively, than conventional batteries after 300 charge/discharge cycles. Thus, the FMS shows great value in lithium battery safety monitoring.