A preparation method of para-aramid nanofiber composite lithium-ion battery separator

Abstract

The invention relates to a method for preparing a para-aramid nanofiber composite lithium-ion battery diaphragm, and belongs to the technical field of polymer materials. First prepare the para-aramid polymerization slurry, and use the coating method to coat the para-aramid polymerization slurry on the surface of the base film, and carry out the coating film in a coagulation bath composed of N-methyl-2-pyrrolidone and water. solidification to obtain a para-aramid nanofiber composite lithium-ion battery diaphragm; the para-aramid nanofiber composite lithium-ion battery diaphragm is washed and dried to obtain a para-aramid nanofiber composite lithium-ion battery diaphragm. Compared with the prior art, the method saves solvent and energy, reduces energy consumption and avoids adverse effects of impurities on battery performance. Moreover, the preparation process is simple, and at the same time, the high temperature resistance performance of the diaphragm is improved. The prepared diaphragm has good ion conductivity, and can obtain better performance when used as a lithium ion battery diaphragm.

Description

technical field [0001] The invention relates to a method for preparing a para-aramid nanofiber composite lithium-ion battery diaphragm, and belongs to the technical field of polymer materials. Background technique [0002] In recent years, the lithium-ion battery industry has developed rapidly. As a mature and common form of energy in mobile devices, compared with other types of batteries, it has the characteristics of high energy density, high working voltage, no memory effect and long cycle life. A lithium-ion battery generally includes a positive electrode, a negative electrode, a separator, and an electrolyte. The separator serves to make the positive and negative electrodes in a state of electronic insulation but conduction of lithium ions. With the rise of electric vehicles, the emergence of high-power power batteries poses a huge challenge to the safety of lithium-ion batteries. At present, the common lithium-ion battery separator is made of polyolefin, usually a sa...

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Problems solved by technology

However, this method has the following problems: PPTA fibers or resins are difficult to dissolve, and the adhesion to the polyolefin separator is poor, and additional binders need to be added

On the one hand, there are other impurities in the composite membrane, and on the other hand, the porosity is reduced, both of which will cause a decline in battery performance.

The 2nd, in the Japanese patent that the patent No. is unexamined 2010-254731, proposed the technology that the polymerization solution of p-aramid fibers is coated as a slurry, but still there are following three problems in its technical scheme: (1 ) A large amount of solubilizing salt (the solubilizing salt is more than 6% of the solvent quality) has been added in the aramid polymer solution, which causes the surface energy of the coating slurry to increase, and it is difficult to spread evenly on the surface of the base film with low surface energy. As a result, the uniformity and bonding fastness of the prepared composite diaphragm are not good; (2) In order to dissolve a large amount of solubilizing salt, the solvent needs to be heated to 100°C to dissolve the solubilizing salt and then cooled to 20°C for polymerization, resulting in The energy consumption increases and the operation process is cumbersome; (3) The solidification and precipitation process of this technical solution is completed in pure water, and the rapid desolventization process makes the aramid fiber coating dense and cannot form a through-hole structure, resulting in a decrease in the lithium ion passing efficiency, and the battery poor performance

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