The main function of lithium battery separator film is to prevent direct physical contact between positive and negative electrodes, avoiding the risk of short - circuit caused by lithium dendrite puncture. In addition, it possesses selfclosing properties at high temperatures, providing a layer of safety for the battery. The microporous structure of the diaphragm allows the electrolyte to pass through smoothly, thus ensuring the proper functioning of the battery. Polymer lithium-ion batteries often use a solid or colloidal electrolyte. 

The liquid electrolyte, due to its meltable nature, can play the dual role of the liquid lithium-ion battery electrolyte and the diaphragm at the same time, which makes it different from the traditional structure of the liquid lithium battery.

The core role of the diaphragm is to separate the positive and negative electrodes of the battery, preventing short circuits caused by contact. At the same time, it also allows the electrolyte ions to pass through smoothly. Since the diaphragm material itself does not conduct electricity, its physicochemical properties have a significant impact on the overall performance of the battery. Different types of batteries often use adapted lithium battery tandem diaphragms.

In the field of power lithium batteries, double-layer PP diaphragm materials are mainly manufactured by Chinese companies and widely used in the domestic market. This is mainly due to the current limitations of Chinese companies in double-layer composite membrane technology, while the global automotive power lithium batteries generally use three-layer PPPP structure. Although in recent years there are other materials such as BoudunF and Kuribayash have been used in lithium battery diaphragm research, such as polyvinylidene fluoride PVDF as the body polymer preparation of lithium battery diaphragm, as well as cellulose composite film as a diaphragm material, but polyethylene is still the dominant material in the commercial lithium battery diaphragm.

The important role of the lithium battery separator film  in the battery is crucial in that it prevents the direct passage of electrons and ensures that electrons can only flow through the external circuitry that generates the current. At the same time, it allows lithium ions to travel through the diaphragm, effectively avoiding direct contact between the positive and negative electrodes. Once contact occurs between the positive and negative electrodes, it will result in a short circuit, which could lead to serious consequences such as a battery explosion or fire.

In the manufacturing process, the interpenetrating microporous membrane material is prepared by a wet production process by eluting residual solvents with volatile substances. This process is not only suitable for themanufacture of interpenetrating microporous membrane materials, but also can give lithium battery diaphragm excellent longitudinal and transverse strength. Currently, the wet production process is mainly used to optimize the physical properties of single layer lithium battery separators. The coating of the diaphragm is designed to increase the resistance in case of short-circuit, reduce the short circuit current and prevent localized thermal balance failure. 

The diaphragm plays a role in separating the positive and negative materials in the battery, ensuring that the positive and negative materials are discharged through it in an orderly manner. At present, the diaphragm material is mostly a combination of imported and domestic materials, although the technology is not yet fully mature, but as a polymer material, its scientific and technological content should not be ignored.

In short, Lithium Battery Separator Film is a key component of battery safety, performance and stability. Its main materials include porous polymer films such as polyethylene and polypropylene, which have strict requirements for safety, air permeability, porosity and thickness. Inside the lithium battery, the diaphragm ensures the orderly flow of charged ions between the positive and negative electrodes.