Influence of Aging on the Failing Behavior of Automotive Lithium-Ion Batteries

Lithium-ion batteries (LIBs) are a dominant state-of-the-art energy storage system and have importance in the automotive sector. Still, LIBs suffer from aging effects and serious hazards from failing batteries are possible. These failures can lead to exothermic chemical reactions inside the cell, ending up in thermal runaway (TR). TR has caused most electric vehicle (EV) fires. Since statistically most accidents with EVs happen after about one year of vehicle usage, in particular, the failing behavior of aged cells needs to be investigated. Little information is available in open literature about the influence of aging paths on the failing behavior and especially on the degassing behavior of large automotive LIBs. Therefore, this study investigates the influence of three different aging paths (cyclic at -10 degrees C and at 45 degrees C and calendric at 60 degrees C) on the thermal behavior, the vent gas emission, and the vent gas composition. The results show a clear effect of aging on the failing behavior. The aged cells showed a less violent failing reaction, reduced maximal temperatures, lower amount of produced gas, significantly lower amount of CO in the vent gas, and lower mass loss than fresh cells in the same overtemperature experiments. The results are valuable for the scientific and industrial community dealing with LIBs.

Automated summary

The study investigates the influence of three different aging paths on the thermal behavior, vent gas emissions, and vent gas composition of lithium-ion batteries. The results show that aging has a clear effect on failing behavior, with aged cells exhibiting less violent reactions, reduced temperatures, and lower gas production compared to fresh cells. This information is valuable for the scientific and industrial community working with lithium-ion batteries.