Review—Online Monitoring of Internal Temperature in Lithium-Ion Batteries

In recent years, fire and explosion accidents caused by high temperature of lithium-ion batteries have become increasingly frequent, and the safety and reliability of batteries have been of great concern. Battery temperature monitoring is an important means to prevent the occurrence of safety accidents, but at present, it mainly focuses on the external temperature and lacks the monitoring of internal temperature changes and measurement of physical parameters of the battery, which makes it difficult to effectively solve the safety problem of the battery. In this paper, starting from the thermal runaway safety problem faced by Li-ion batteries, we analyze the heat generation principle and temperature effect during battery operation, and discuss various methods of internal battery temperature monitoring, including in situ temperature measurement, multi-parameter measurement inside the battery, temperature measurement based on thin-film sensors and distributed fiber optic sensors, and impedance-based temperature estimation. Also, the advantages and disadvantages of different sensing techniques are compared, and the challenges of inserting temperature sensors into real batteries are reviewed. Finally, this paper presents directions and difficulties for future research on internal temperature monitoring of Li-ion batteries.