We are excited to announce another significant milestone in the PHOENIX Project. A new generation of sensors and triggers for self-healing batteries has been successfully developed, with prototypes now ready for shipment to our consortium partners.

Thanks to technical advancements, the partners have developed enhanced prototypes that have been constructed and thoroughly tested for functionality. These innovative prototypes are now poised for integration into battery cells at our partner CIDETEC, ready for being validated in multilayered battery cells. 

A highlight of this development is the self-regulating thermal trigger made from materials with a positive temperature coefficient and an internal resistance of less than 10 Ohms. This thermal trigger activates the battery’s self-healing effects without causing thermal damage. 

Additionally, a mechanical trigger based on a HASEL actuator will exert increased mechanical force on braced battery cells, unlocking pressure-induced self-healing effects. 

Soft and pressure-sensitive elastomer sensors, designed with tailored sensitivity and a compact form factor, will monitor expansion and internal pressure throughout the battery’s lifecycle, providing valuable insights into the State of Health (SoH) of the cell. 

Furthermore, printed temperature sensors on flexible substrates made from optimized NTC (negative temperature coefficient) materials will track temperature changes during the battery’s lifespan, enabling precise SoH monitoring. 

For precise thermal monitoring inside Li-ion battery, a second approach was developed using distributed optical fiber sensing technique based on optical frequency-domain reflectometry. CSEM has designed and built all necessary digital electronics, algorithms and assembly methodology. The sensing system operates with a spatial resolution of a few centimeters and a measurement uncertainty of <0.1 °C at a measurement speed of 20 Hz. To validate the sensing performance, the system was used to monitor the temporal evolution of temperature in single layer pouch cells while cycling the batteries. These tests successfully demonstrated that the distributed temperature sensing system is a promising solution for monitoring the battery health.  

The ultrasonic sensors mounted on both sides of the cells will utilize time-of-flight measurements to detect cell expansion and changes in Young-modulus, allowing us to monitor the health status of the cells (SoH) in real-time. 

We have also developed thin-layered memristor gas sensors for hydrogen detection, utilizing functional metal oxide materials deposited on a flexible substrate. The developed sensors enable the detection of hydrogen from 50 ppm at RT in the air, as well as in inert gas atmospheres. Prototypes of these sensors are now ready for integration into the battery pouch cells. 

Moreover, an optimized design for a reference electrode with minimal blocking effect has been extensively evaluated on coin cell level and is now available for transfer to pouch cell applications. 

We are thrilled with the progress we are making in the PHOENIX Project. Stay tuned for more updates and exciting developments in the world of self-healing batteries!