​Thermal runaway in batteries is a major safety issue, especially for on-board aircraft batteries, where early detection is crucial. In research for the EU OASIS project (Grant Agreement No. 814581), CEA-Liten, plastics and composites R&D center IPC, and Thales joined forces to develop a new battery cell packaging that is lightweight, robust enough to withstand extreme thermal and mechanical stress, and equipped with sensors capable of detecting a battery malfunction.

The novel system features two kinds of sensors developed at CEA-Liten. The first, specially designed temperature sensors, are in contact with the cells and integrated into a new composite packaging developed by IPC to replace the conventional, much heavier metal system. The second, original flexible piezoelectric sensors made of polymers deposited in very thin layers using low-cost screen printing processes, are flexible enough to be integrated inside the battery core. Used in acoustic mode, the sensors can detect changes inside the material indicative of malfunctions that can lead to thermal runaway. 

The new functionalized packaging was tested, and it successfully detected these early warning signs of thermal runaway, making batteries safer. The tests also confirmed that total battery weight can be reduced by about 15% with the system. Finally, the successful integration of flexible sensors inside a composite material by CEA-Liten and IPC will undoubtedly create new opportunities for these kinds of materials—currently used mainly in aeronautics and automotive applications—in health and medical diagnostics.