How are lithium battery separators made?

Separators for the lithium battery market are usually manufactured via a “wet” or “dry” process. In the “dry” process, polypropylene (PP) or polyethylene (PE) is extruded into a thin sheet and subjected to rapid drawdown.

Why do lithium battery separators break?

The principal reason is that, after shutting down, the internal temperature of the battery is often high enough to cause residual stress and reduced mechanical properties leading to shrinkage, tearing, or pinhole formation. Separators for the lithium battery market are usually manufactured via a “wet” or “dry” process.

What is a dry process separator?

It prevents contact between the electrodes which would cause a short, while allowing lithium ions to pass between the electrodes. Dry-process separator uses polypropylene (PP) as the main component and is manufactured with a solvent-free process.

Should you use a dry separator in your blade battery?

Although in the beginning wet separators was more common in LFP, the demand for more affordable cells has become the key factor that driving manufacturers to opt for dry separators. BYD is one of the biggest and well-known manufacturers that began to use dry separators since 2016 and now they are using dry separators in their blade battery.

How do lithium battery separator rolls work?

After delivery to the lithium battery manufacturer, separator rolls are loaded onto an un-winding station along with individual rolls of cathode and anode. Two separator rolls are required so that the separator is interspersed between the anode and cathode while all 4 layers are wound around a pin to form a “jellyroll”.

Do LFP batteries need a wet or dry separator?

As for LFP batteries, both wet and dry separators are used by cell manufacturers. Although in the beginning wet separators was more common in LFP, the demand for more affordable cells has become the key factor that driving manufacturers to opt for dry separators.