In-situ Lithium-ion Cell Sensing and Thermal Runaway in an Oil Immersed Setup

Exceeding the manufacturer limits of Lithium-ion cells can initiate thermal runaway which can cause explosion and fire. This paper presents an experimental study on the efficacy of a dielectric oil bath for thermal management in Lithiumion battery testing in comparison to a traditional air-controlled environment. A temperature conditioned oil bath is utilised as an isothermal test platform for submerged Lithium-ion cells that are instrumented with an array of temperature sensors and are rapidly charged and discharged with monitoring of the internal and surface temperatures. The results indicate a significant safety and performance improvement when using the oil bath; the internal temperature of the cells never exceeded the manufacturer’s maximum rated temperature, unlike in air-cooled setups. In the nail penetration test, thermal runaway in the oil bath did not result in fire or explosion, demonstrating enhanced safety compared to air environments. In addition, the external temperature of the cell in oil during the nail penetration test did not exceed the threshold for which propagation of thermal runaway could occur in adjacent cells in a battery system.