Separators for Lithium-ion Batteries

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. 

The through-pore size of the separator is a key parameter for ensuring optimal battery performance. The pores must be small enough to prevent dendrites from forming across the separator and causing a short circuit but large enough to facilitate ion flow between the cathode and anode. Additionally, larger pores or pin holes must be screened for and prevented because they may lead to short circuits. 

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.