Composite spinning fibre lithium ion battery diaphragm and preparation method thereof

Abstract

The invention discloses a composite spinning fibre lithium ion battery diaphragm. The composite spinning fibre lithium ion battery diaphragm is prepared by the steps of: uniformly mixing and dispersing surface etched carbon nano tube dispersion liquid with 4,4'-diaminodiphenyl ether at first, after ball milling and stirring at room temperature, adding pyromellitic dianhydride, reacting with 4,4'-diaminodiphenyl ether attached on the surface of a carbon nano tube, so that the carbon nano tube is uniformly dispersed in polyamide acid solution, preparing composite spinning fibre from the mixed solution through a spinning process, and then, performing thermal imidization processing in a stepped temperature rising manner. According to the composite spinning fibre lithium ion battery diaphragm disclosed by the invention, the surface etched carbon nano tube is uniformly dispersed in a polyimide material through a ball milling-stirring process; therefore, the diaphragm material has relatively high porosity; the disadvantages that the traditional polyolefin diaphragm is low in porosity, poor in ionic conductivity and the like can be broken through; and the comprehensive performance of the lithium ion battery is improved.

Description

technical field [0001] The invention relates to the field of polyimide materials, in particular to a composite spinning fiber lithium-ion battery diaphragm and a preparation method thereof. Background technique [0002] With the development of lithium-ion batteries to power fields such as electric vehicles, aerospace, energy storage, and large-scale instruments and meters, higher requirements are put forward for the comprehensive performance of batteries. The role of the separator determines that it must be a highly insulating microporous membrane. The membrane itself is used to block the transfer of electrons between the positive and negative electrodes, and its internal pores can ensure the unimpeded flow of electrolyte ions, thereby realizing the charging and discharging process of the battery. Therefore, on the one hand, the inside of the separator should have a high porosity to ensure the passage of electrolyte ions; on the other hand, the pore size should be kept at an...

AI Technical Summary

Problems solved by technology

However, many traditional and even modified carbon nanotubes are used as a conductive network for lithium-sulfur battery cathodes, but they show a large capacity decay rate.

In the final analysis, this is because the specific surface area and pore volume of traditional carbon nanotubes are relatively low, so that many active materials, sulfur, cannot enter the pore structure and are exposed on the outer wall of carbon nanotubes, which makes these sulfur very difficult to absorb during the cycle charge and discharge process. It is easy to fall off and diffuse into the electrolyte, causing the electrode capacity to decay quickly