The overall increasing application of lithium-ion batteries, driven by the field of electric vehicles and stationary storage systems forcing a permanently increase of energy and power density. Hence, new cell chemistries with thermally sensitive materials are developed by battery industry to meet the customers’ requirements in driving range. Therefore, thermal safety aspects on lithium-ion batteries are becoming increasingly more important.
A single cell failure may cause different exothermic chemical reactions leading to an uncontrolled release of heat that can trigger subsequent reactions causing a thermal runaway (TR). Combined with a fast heat transfer to neighbouring cells, the uncontrolled heat release can cause thermal propagation (TP) and may lead to a critical situation with multiple TR events in the battery system. In order to mitigate the safety risks related to TR and TP, system manufacturers have to implement hardware safety measures to guarantee a safe operation of lithium-ion batteries and cope with national and global safety requirements. Due to different concepts in cell chemistry and various properties in battery module and systems design on the market, safety concepts are getting complex.
In this work, we focus on customization and commercialization of our novel barrier materials for preventing TP. Due to our expertise in developing TP – barriers over the past few years, we are able to adapt our material to the respective application. Firstly, a couple of parameters characterizing the barrier such as thermal properties, endothermic properties, compressibility, stiffness and long-term stability are in focus. In the next step, characterization methods used for identifying the parameters of a TP simulation model are described. Furthermore, the process of optimizing barrier properties based on the results of characterization and simulation is illustrated.
In order to indicate the way to commercialization, a concept for building up a pilot production line capable of producing TP barriers with customized properties is presented. For validation, thermal propagation testing and long-term cycle tests show the functionality of the barriers according to the applicable requirements. Finally, there are some insights to the actual production research and our planned way to an economical production for supplying manufactures on the market all over the world.