Lithium Battery Separator Coating - Small & Strong
Coating Modification The functional coating is adhered to the surface of the separator by an adhesive to improve its thermal stability.
For the thermal stability test of boehmite coated on polyethylene film, when the temperature is heated to 170 degrees, the diaphragm has undergone obvious deformation, and the coating film has almost no shrinkage. The coating process can improve the low melting point and poor safety of the diaphragm. shortcomings.
The edge coating of the pole piece is of great significance to the safety and yield of the battery. Materials such as boehmite can also be used to coat the pole pieces of lithium battery cells to improve the safety performance and yield of lithium batteries.
The pole piece coating can be applied to the positive and negative electrodes of the battery, respectively:
1) Coating of the edge of the positive pole piece: Since the positive pole piece is generally smaller than the negative pole piece, the edge of the wide side of the pole piece is prone to burrs during cutting. Once the diaphragm is pierced and the negative pole is touched, the battery will be short-circuited.
The surface of boehmite is smooth, after coating, it can fill the edge of the positive electrode, making the cut surface smooth and burr-free.
2) Coating the edge of the negative pole piece: The surface of the negative electrode is rough, and after coating the ultra-small particle size boehmite, the negative electrode pore formation becomes uniform, which can improve the wettability of the electrolyte and make the lithium ion more smooth during the charging and discharging process.
Among the coating materials, the inorganic coating with boehmite and alumina as the main coating materials is more mature than the organic coating and organic-inorganic hybrid coating technology represented by PVDF and aramid. Better tensile strength and thermal shrinkage.
Boehmite has absolute advantages over alumina in performance indicators. As a ceramic coating material, alumina can significantly improve the comprehensive properties of polyolefin separators.
However, alumina has problems such as high hardness, high cost, and serious wear on equipment, which affects its application as a ceramic coating material in battery separators to a certain extent.
As a new ceramic coating material, boehmite has the characteristics of low hardness, low cost, and less water-soluble sodium ions, which can make up for the shortcomings of alumina as a coating material for polyolefin separators.
