Mixed paint for composite membrane of lithium ion battery, composite membrane and preparation method thereof, and lithium ion battery

Abstract

The invention relates to mixed paint for a composite membrane of a lithium ion battery, and also relates to the composite membrane using the mixed paint and a preparation method thereof, and the lithium ion battery, and belongs to the technical field of the lithium ion batteries. The mixed paint for the composite membrane of the lithium ion battery is prepared from the following components in parts by weight: 45 to 63 parts of organic macromolecule microspheres, 35 to 53 parts of inorganic ceramic particles and 2 to 10 parts of an additive, wherein a melting point temperature or a softening point temperature of the organic macromolecule microspheres is lower than a hot smelting temperature of a base membrane used for the membrane of the lithium ion battery. According to the composite membrane of the lithium ion battery, which utilizes the mixed paint, a micro-pore blocking effect of the organic macromolecule microspheres is more sufficient, a lithium ion transmission channel is completely cut off and the safety of the lithium ion battery is greatly improved.

Description

technical field [0001] The invention relates to a mixed coating for a lithium-ion battery composite diaphragm, and also relates to a composite diaphragm using the mixed coating, a preparation method thereof and a lithium-ion battery, belonging to the technical field of lithium-ion batteries. Background technique [0002] Lithium-ion batteries have been widely used in many fields including portable electronic products because of their advantages such as high energy ratio, no memory effect, and long life. However, under various complex application conditions, lithium-ion batteries have Potential hazard of explosion and fire. With the development of the electric vehicle industry, the defects in the safety performance of lithium-ion batteries have become more obvious, which seriously restricts the application of lithium-ion batteries in power batteries and other fields. [0003] Judging from current research reports, factors such as overcharging, internal and external short cir...

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Problems solved by technology

[0006] However, in the actual production and application process, it is found that there are still some problems in the composite diaphragm made by the above method.

This kind of composite diaphragm adopts the method of coating the organic polymer microsphere layer and the inorganic ceramic layer on both sides of the polyolefin microporous membrane respectively. The organic polymer microsphere and the inorganic ceramic particles are separated. When the battery temperature rises, The organic polymer microsphere layer melts and enters the pores of the microporous membrane. At this time, the temperature inside the battery is still at a relatively high temperature, which is generally higher than the melting temperature of the organic polymer microspheres, causing the organic polymer microspheres to be in a state of melting. An unstable state, unable to be fixed in the pores of the microporous membrane, the blockage of the polyolefin micropores is not sufficient, and the lithium ion transfer channel is not completely cut off

[0007] In addition, it was found in the actual production process that when the above-mentioned composite diaphragm needs to be coated with different coatings on both sides of the polyolefin microporous membrane, it is necessary to replace the equipment after coating one material, and then carry out another coating. In the process of changing equipment, it is easy to cause structural changes in the coating materials that have been coated, which will reduce the quality of the final composite diaphragm.

And, this way process is complicated, has increased equipment and production cost

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