Highly Sensitive, Thin, and Conformal MoS2 Thermistors for In Situ Thermal Characterization of Lithium-Ion Batteries

Lithium-ion batteries (LIBs) experience continuous temperature changes during operation and can overheat due to overcharging and short circuits, leading to severe safety hazards, such as thermal runaway. As temperature during the operation is a direct indicator of the safety status of LIBs, developing a high performance thermistor that is capable of sensitively monitoring the temperature changes of LIBs in real time is crucial. In this study, we developed, fabricated, and evaluated a highly sensitive, thin, and flexible temperature sensor composed of 2D MoS₂ as a thermosensitive material. The sensor can be conformally integrated onto the surface of LIBs without interfering with the assembly of other components. The MoS₂ thermistor exhibits a high temperature coefficient of resistance (TCR) of −1.94%/°C (corresponding thermal sensitivity is 200 mV/°C) with a high linearity (R² of 0.98) in the 20–60°C temperature range. This sensitivity is three to four orders of magnitude higher than that of thermocouples (usually tens of μV/°C) that are conventionally used for the temperature monitoring of LIBs. Moreover, the MoS₂ thermistor exhibits an insignificant response to bending, with resistance changes of less than 0.3% under a bending angle of 40°, which the sensor could experience owing to LIB swelling during operation. The spatial temperature changes of LIBs during their charge-discharge cycles can also be monitored accurately in real time by integrating multiple MoS₂ thermistors. Our thermistor provides sensitivity, stability, simplicity, and portability, which are critical for the continuous thermal characterization of LIBs and the reduction of the risk of thermal runaway.