The separator in a lithium-ion battery is a thin porous membrane that plays a key role in battery function by preventing a short circuit between the anode and cathode while at the same time allowing ion flow between them. Separators need to be mechanically robust, stable under active battery conditions, and inert to other cell materials – but still be porous enough to enable ion transport.
Another key parameter for separators is their mechanical strength and structural properties. Specifically, measuring how much pre-tension of the separator is required is key to avoiding rupture or tearing during assembly as well as sagging after assembly.