It has electronic insulation to ensure the mechanical separation of the positive and negative electrodes.
It has a certain pore size and porosity to ensure low resistance and high ion conductivity, and has good permeability to lithium ions;
It is resistant to electrolyte corrosion, and has sufficient chemical and electrochemical stability, because the solvent of the electrolyte is an organic compound with strong polarity.

Good electrolyte wettability, strong liquid absorption and moisturizing ability;
High mechanical stability, including puncture strength, tensile strength, etc. , But the thickness is as small as possible;
Good spatial stability and smoothness;
Good thermal stability and automatic shutdown protection performance;
The heat shrinkage rate is very small, otherwise it will cause a short circuit and cause the battery to thermally run out of control. In addition, composite membranes are often used in power batteries, which require higher separators.