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3C electronic products; Electric cars, electric motorcycles, electric tools; Large lithium-ion power battery; Large energy storage equipment

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Definition and function

Definition: Lithium battery separator is a polymer film with a microporous structure. It is one of the key inner components of lithium batteries and is usually placed between the positive and negative electrodes.

Function: It mainly isolates the positive and negative electrodes and prevents internal short circuits in the battery. At the same time, it can also allow lithium ions to pass between the positive and negative electrodes to form ion conduction channels to ensure the smooth charging and discharging process of the battery.

Performance requirements

Mechanical properties: It needs to have high tensile strength and puncture strength to ensure that it is not damaged during battery assembly and use, and to prevent direct contact between the positive and negative electrodes and cause short circuits.

Aperture and porosity: Appropriate pore size and porosity are crucial. The pore size should be small enough to prevent electrons from passing through and prevent short circuits; but it should be large enough to allow lithium ions to pass quickly to ensure the charging and discharging performance of the battery. The general porosity is around 40%-60%.

Chemical stability: In the electrolyte environment of the battery, the separator must have good chemical stability and not react chemically with the electrolyte and the positive and negative electrode materials to ensure the performance and life of the battery.

Thermal stability: Heat is generated during the battery charging and discharging process. The diaphragm needs to maintain stable performance in a wide temperature range, have a high melting point and thermal stability, and prevent shrinkage and melting at high temperatures, which may cause safety problems in the battery.

Main types

Polyolefin diaphragms: including polyethylene (PE) diaphragms and polypropylene (PP) diaphragms. PE diaphragms have good flexibility and low resistance, while PP diaphragms have higher melting points and better thermal stability. Multi-layer composite structures are often used, such as PP/PE/PP three-layer composite diaphragms, which combine the advantages of both and are widely used in various types of lithium-ion batteries.

Ceramic coated diaphragms: On the basis of polyolefin diaphragms, a layer of ceramic materials such as alumina (Al₂O₃), titanium dioxide (TiO₂), etc. is coated. The thermal stability and puncture resistance of the diaphragm are improved, which can effectively prevent thermal runaway of the battery at high temperatures, and is suitable for power batteries and other fields with high safety requirements.

Aramid diaphragms: Aramid fibers are used as the main raw material, with high strength, high heat resistance and good chemical stability. It can maintain stable performance under harsh conditions such as high temperature and high voltage, and has unique advantages in some high-end battery applications.

Composite polymer diaphragm: Compound different polymer materials, or compound with other functional materials to combine the performance advantages of multiple materials. For example, compounding polymers with nanomaterials can improve the ion conductivity and mechanical properties of the diaphragm, which is one of the hot research and development directions.

Application field

Consumer electronics field: widely used in lithium batteries of various consumer electronic products such as smart phones, tablets, laptops, digital cameras, etc., to provide stable power support for these devices and ensure their normal operation.

Power battery field: It is a key component of power battery systems such as electric vehicles, electric motorcycles, and electric bicycles. With the rapid development of the new energy vehicle industry, the performance and quality requirements of lithium battery diaphragms are constantly improving, which has promoted the continuous advancement of diaphragm technology.

Energy storage field: Lithium battery diaphragms also play an important role in energy storage systems of renewable energy such as solar energy and wind energy. It is used to store excess electrical energy, achieve stable supply and effective utilization of energy, and improve the utilization efficiency and stability of renewable energy.