Seawater submersion for cylindrical lithium-ion batteries thermal runaway prevention

Abstract

Lithium-ion batteries (LIBs) are currently used in various electric vehicles, including electric boats. To assess the risk of fire due to thermal runaway of the LIB during the operation of ferries, seawater can be used as a cooling fluid for the LIB to prevent thermal runaway as it is abundant. However, the seawater could corrode the electrodes of the battery, which would lead to toxic wastewater. Prevention of thermal runaway of lithium-ion batteries by submersion in seawater needs to be investigated to clarify the corrosion that could lead to toxic wastewater. In this study, fully charged, pristine 18650 NMC Li-ion cells were submerged in synthetic seawater (SSW) to investigate the corrosion effect compared to deionized (DI) water. The results showed that SSW induced rapid voltage discharge, leading to corrosion on the electrodes and toxic effluents, while DI water maintained the stability of the cells and did not cause any corrosion effect. In addition, the prevention of thermal runaway was investigated by exposing fully charged LIB to extreme overheating conditions. The liquid submersion system was activated by rapid voltage drop monitoring to evaluate its effectiveness in preventing thermal runaway (TR). The investigation of TR prevention by SSW submersion showed that the TR process can be effectively prevented. In addition, no corrosion effect was observed during submersion in SSW as the battery voltage was not applied. This study shows that seawater can be used to prevent TR in LIB and does not cause environmental problems comparable to water.