There are two main methods to make lithium-ion battery separators: the dry process and the wet process.

Starting with the dry method, there are two techniques. One is the single-stretch, and the other is the double-stretch. The double-stretch technique was developed by the Chinese Academy of Sciences’ Institute of Chemistry. However, it’s not widely used now because it didn’t meet the performance standards people wanted. The equipment for the dry process is pretty reliable, and the whole thing is pretty straightforward. One big advantage is that the dry method doesn’t have much heat shrinkage, so it’s safer. Plus, it’s cheaper. This makes it great for making separators for storage batteries, consumer batteries, and iron phosphate lithium power batteries.

On the other hand, the wet method costs more than the dry one. But it has its perks. The separators made with the wet process have uniform and well-aired holes. They can also be thinner and lighter. Many think that “wet-base + coated layer” separators are best for high-energy-density power batteries. Right now, the wet method is leading the way. More separators are made using the wet process than the dry one, and it’s the go-to choice in the market.