Flexible Integrated Sensor Array with Long Cyclic Life and High Measuring Accuracy for Real-Time Monitoring of Internal Temperature and Pressure of Lithium Battery

The safety incidents caused by the thermal runaway of lithium-ion batteries (LIBs) have motivated people to develop sensing technologies to monitor the temperature and pressure for safety warnings. However, current external sensors face challenges such as low accuracy and high latency. Internal sensors are limited by device size, which usually allows for monitoring only a parameter and significantly impacts the capacity and cycle characteristics of LIBs. The present work designs an implantable integrated sensor (TPS) capable of real-time monitoring of the temperature and pressure inside the 6Ah LIB. The TPS is composed of a PT1000 temperature-sensitive alloy and a polydimethylsiloxane/ carbon nanotubes piezoresistive composite. The TPS offers a temperature measurement range of −50–80 °C with an accuracy of 0.30 °C; and a pressure measurement range of 0–2 MPa with an accuracy of 0.11 MPa, and shows significant accuracy when compared with external sensors. Furthermore, the TPS has a rather low impact on the battery capacity with a retention rate of 92.80% after 300 cycles, which is only 0.75% lower than normal batteries, and a maximum Coulombic efficiency difference of 0.04%. The proposed TPS holds promise for monitoring the temperature and pressure of LIBs and promotes its safe utilization.