Advantages Of Boehmite Used In Lithium-Ion Battery Separator Coating

Commonly used coating materials include inorganic (represented by alumina and boehmite) and organic (represented by PVDF and aramid).

Boehmite has good safety and economy and can replace alumina in some markets.

Boehmite + magnetic material has a low water absorption rate, which can effectively ensure the safety of the diaphragm. The specific gravity of boehmite is low, and the dosage can be reduced by 25% under the same coating area; the hardness is low, the service life of the coating roller is prolonged by 3-4 times, and the overall economy is better. Boehmite currently accounts for 40-50% of inorganic materials and will reach 70% in 2025.

ZC-TECH independently developed a series of boehmite products according to the actual needs of the market. The product has a flake or block structure, high purity, narrow particle size distribution, good dispersion, and good batch stability, and can be widely used in many fields such as new energy battery diaphragm coating, lithium-ion battery pole piece coating, copper clad laminate, polishing abrasive, and so on.

Product advantages: mainstream products have reached a high particle size distribution, purity, and magnetic foreign body control. The company can produce 0.3-0.5um boehmite products: the smaller the particle size, the more complex the production.

Boehmite has high purity and high heat-resistant temperature. It is a new type of inorganic lithium battery coating material.

Boehmite is also called boehmite and boehmite, and its chemical formula is γ-AlOOH, which belongs to the orthorhombic crystal system of a close-packed cubic structure. It is divided into natural and artificial. Natural boehmite exists in bauxite and can be calcined to prepare alumina powder; synthetic boehmite has the characteristics of high purity and high heat resistance.

From the product aspect: the current inorganic coating has good flatness, air permeability, stretchability, and puncture strength; the organic layer is light and thin, which can better comply with the trend of increasing battery energy density, and due to the adhesion of PVDF, it can improve The hardness of the battery core reduces deformation.

(1) From the perspective of areal density range: boehmite (±2)<PVDF(±3), indicating that its flatness is better, the areal density is more uniform, and the consistency is good;

(2) From the perspective of gas permeability: 7 and 9μm base films, although the thickness of the boehmite coating is 3μm and the thickness of the PVDF layer is only 2μm, the gas permeability of boehmite is still better than that of PVDF, indicating that the unit gas The shorter the time to pass the diaphragm, the lower the internal resistance, which is conducive to the passage of lithium ions and ensures the rate of lithium-ion batteries.

(3) From the point of view of tensile strength and puncture strength: Because the thickness of boehmite and PVDF coatings are different, they cannot be directly compared. Choose the same base film and coating thickness for comparison. The tensile strength and puncture strength of boehmite film are better than the mixed coating film, indicating that PVDF drags the composite coating film. It can be seen that the ceramic diaphragm has better tensile strength and puncture resistance than PVDF.

In addition to boehmite used for diaphragm coating, the pole piece coating market is also gradually emerging. Coated in the lithium battery pole piece, it can prevent the burrs generated during the slitting process of the positive electrode material from piercing the diaphragm, improve the safety performance of the lithium battery, improve the battery production process, and increase the energy density. However, because the edge technology of the positive electrode material is some Customers, including CATL and BYD, are still conducting verification tests on newly developed processes. The particle size of the pole piece coating material is larger than the particle size of the boehmite used for the diaphragm coating.