Preparation method of high-safety lithium ion battery diaphragm

Abstract

The invention discloses a preparation method of a high-safety lithium ion battery diaphragm, wherein the preparation method comprises the steps of hollow rubber microsphere surface treatment, substrate coating, tensile hole forming treatment, extraction treatment and the like, a diaphragm substrate is coated with hollow rubber microspheres by assisting of paraffin, an ion pathway is formed by tensile pore forming treatment, and finally an organic solvent which can dissolve paraffin is used for extracting and removing the paraffin. When the temperature of the interior of a lithium ion battery abnormally rises because of fault, the hollow rubber microspheres are expanded, an original gap in the diaphragm is filled, and migration of ions in the electrolyte solution at two sides of the diaphragm is prevented, so that the temperature of the interior of the lithium ion battery drops, and the safety of the lithium ion battery is ensured; after the temperature drops, the hollow rubber microspheres are shrunk and are restored to the original state; and the lithium ion battery diaphragm has relatively high thermal stability and mechanical strength, even the temperature of the interior of thelithium ion battery is too high, a heat shrinkage phenomenon cannot happen, and contact of positive and negative electrodes is prevented.

Description

technical field [0001] The invention relates to the technical field of lithium-ion battery diaphragm manufacturing, in particular to a preparation method of a high-safety lithium-ion battery diaphragm. Background technique [0002] In recent years, the rapid development of portable electronic products, electric vehicles, energy storage power stations and other fields has put forward higher requirements for energy storage technology. Lithium-ion batteries are the first choice in these fields due to their high energy density, and their energy density is getting higher. As the energy density of lithium-ion batteries is getting higher and higher, the safety problems it faces are becoming more and more severe, which has severely limited the terminal use of high-energy-density lithium-ion batteries. The safety problem of lithium-ion batteries is mainly due to the thermal runaway of batteries. Due to the abnormal heat generation reaction inside the battery, the internal temperatu...

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Problems solved by technology

For example, Chinese Patent Publication No. CN104269509A, the patent publication date is January 7, 2015, discloses a ceramic coating diaphragm for lithium batteries and a preparation method thereof, which includes a ceramic coating and a substrate diaphragm, and the ceramic coating is composed of a water-based ceramic coating The coating slurry is evenly coated on the surface of the substrate diaphragm, and the ceramic coating slurry includes 10-30wt% of alumina, 0.5-3wt% of adhesive, 0.2-1.0wt% of additives and 0.01-0.1wt% % additives, alumina is a nano-alumina powder with a particle size ratio D1 / D2 of 0.10 to 0.20; the ceramic coating diaphragm of the technical solution of the present invention has improved thermal safety and strong wettability to the electrolyte, and is applied in Lithium batteries can improve the cycle life of the battery; however, the ceramic-coated diaphragm can only improve the thermal stability and strength of the diaphragm, and cannot block the side reactions of heat generation, so the improvement effect is limited. Currently, it can only solve the problem that the energy density does not exceed 200Wh. / kg battery safety issues, not widely available

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