◆Impact on security
A thicker diaphragm can better ensure the isolation of the positive and negative electrodes inside the lithium-ion battery when it is impacted by foreign objects, so a thicker diaphragm also means better safety.
Since lithium-ion batteries increase in temperature during continuous use, separators typically have the added function of providing a thermal shutdown. When the internal resistance of lithium-ion battery packs increases by three orders of magnitude, the thermal shutdown function of the separator will come into use.
◆Influence on internal resistance
The air permeability of the separator is proportional to the internal resistance of the lithium ion battery with which it is assembled, that is, the higher the air permeability of the separator, the greater the internal resistance of the lithium ion battery.
Whether the separator can be completely wetted by the electrolyte used in the lithium-ion battery also affects the internal resistance of the battery. The wettability of the electrolyte is related to the separator material itself and its internal microstructure.