Enhanced lithium battery diaphragm and manufacturing method thereof

Abstract

The invention relates to an enhanced lithium battery diaphragm and a manufacturing method thereof. The temperature difference between the closed cell temperature and the film breaking temperature is 15-25 DEG C, and the small cutting degradation percentage caused by edge collapse is less than 0.3%.The heat shrinkage rate is less than 1.5% in MD direction and less than 1% in TD direction. The raw material of the enhanced lithium battery diaphragm is a blend, and the raw material weight parts of the blend include 70-85 parts of high molecular weight polyethylene, 15-30 parts of high molecular weight polypropylene, 0.01-5 parts of ethylene-propylene copolymer and 0.01-0.3 part of antioxidant. The blend diaphragm has simple preparation process and can be produced without modifying the originalproduction equipment and can be widely applied to the field of lithium battery diaphragm manufacturing.

Description

technical field [0001] The invention relates to the technical field of diaphragm production, in particular to a reinforced lithium battery diaphragm and a manufacturing method thereof. Background technique [0002] In lithium-ion batteries, the separator is a very important part and one of the four key materials in the battery. The lithium battery separator plays the role of separating the positive and negative electrodes to prevent short circuit, and also provides a path for the conductive ions in the electrolyte. The separator The performance of the separator determines the capacity, cycle performance, safety performance and other characteristics of the battery. Therefore, the performance of the separator has an important impact on the overall performance of the battery. [0003] The current development trend of lithium batteries is higher energy density. Therefore, only a thinner separator can provide more space for the electrode material, thereby improving the energy den...

AI Technical Summary

Problems solved by technology

[0004] In order to improve the safety of the lithium-ion battery separator, the most common method is to apply ceramic slurry coating to the polymer separator or to prepare a multi-layer separator by co-extrusion technology. The coating process is coated on the surface of the basic separator. Ceramic particles may also fall off during battery use, causing local thermal shrinkage of the separator and affecting the overall performance

The second method is to use multi-layer co-extrusion technology, which requires special equipment for production. The multi-layer co-extrusion process is complicated, and the performance of the diaphragm is not easy to control.

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