New PVDF-Based Separator for Consumer Electronic Battery

Li-ion batteries are used in most of our portable electronics by virtue of their high energy and power density. The consumer electronics market is rapidly expanding the range of applications into unconventional fields as flexible and wearable, conformable and curved devices, which require advanced lithium ion battery technologies capable of being accommodated into different shapes without constraining their form factor. Therefore the battery core has to keep its physical integrity to be capable to deliver its best performances, whatever its position.

And the battery components must be redesigned to be able to be deformed for a better integration in electronic devices. In particular the standard porous polyolefin separator does not fully match these requirements and there is always the risk that mechanical distortion can cause the leakage of liquid electrolytes.

Consequently Solvay is developing a new polymeric separator, based on thin and dense PVDF film obtained by extrusion process. The advantages of high chemical and electrochemical stability of PVDF associated with its good mechanical integrity and excellent affinity with liquid electrolyte have been coupled with the presence of a plasticizer which guarantees sufficient ionic conductivity for use in consumer electronics. 

Thus in collaboration with CEA-Liten, new PVDF polymers have been studied for a better affinity with the plasticizer in order to optimize mechanical properties, ionic conductivity and performances in lithium-ion battery. Furthermore in addition to excellent flexibility, the separator shows excellent colamination properties with the electrodes, good adhesion and low interface issues.

The first tests in conformable small pouch batteries show the possibility to integrate this new separator in flexible and curved batteries.