Production method for diaphragm used for lithium ion battery

Abstract

The invention discloses a production method for a diaphragm used for a lithium ion battery, which comprises the following steps: preparing high melting point plastic particles blended with a nano material; extruding and stretching the obtained high melting point plastic particles blended with the nano material; and thermoforming; wherein the nano material is one of nanosilicon dioxide, nano-barium sulfate and nano calcium carbonate, and the high melting point plastic particles are one of PEEK, PEI or PPS plastic particles. The thickness of the produce diaphragm can reach 1 micrometer, the porosity can reach 80%; the inorganic nano particles are non-conducting material, and can not be melted under the temperature of diaphragm melting, anode cathode contact of the battery can be effectively obstructed, and the generation of internal short circuit of the battery can be prevented. The production method for the diaphragm used for the lithium ion battery can reduce the cost of the lithium ion battery and increase the service life of the lithium ion battery.

Description

[Technical field] [0001] The invention relates to a lithium ion battery separator, in particular to a production method of a lithium ion battery separator. [Background technique] [0002] Lithium-ion battery separator is one of the key materials of lithium-ion battery and plays a crucial role in the performance of the battery. Thin lithium-ion battery separators are beneficial to improve the safety performance of lithium-ion batteries because they require a small amount of organic electrolyte. It also improves the safety of lithium ions; the separator containing inorganic insulating fillers can effectively prevent the contact between the positive and negative electrodes of the lithium ion battery after the separator melts and cause short circuit, which is very important for the safety of lithium ion batteries. [0003] Chinese invention patent application CN200610025144.8 discloses a microporous membrane that works at a higher temperature, using polyethersulfone resin as ra...

AI Technical Summary

Problems solved by technology

[0003] Chinese invention patent application CN200610025144.8 discloses a microporous membrane that works at a higher temperature. Polyethersulfone resin is used as a raw material. Since polyethersulfone cannot resist the corrosion of small molecule organic esters and hydrogen fluoride, it cannot be used as a lithium membrane. Separators for ion batteries

[0004] Chinese invention patent application CN201110048688.7 discloses a method of coating an insulating layer on the diaphragm to achieve the isolation of the positive and negative electrodes of the lithium-ion battery after the diaphragm is melted to ensure safety. The technology provided by this invention is very cumbersome, and the coating needs to be used Large amount of organic solvents, high production costs, and the quality of the final product cannot be guaranteed

[0005] Chinese invention patent application CN200810241632.1 provides a polyimide diaphragm. In order to improve the safety of the diaphragm, this patent uses the technology of coating the surface of the diaphragm with insulating material. This technology has poor operability and high cost

[0006] At present, the thickness of lithium-ion battery separators of polyethylene or polypropylene is more than 16 microns, and it is difficult to achieve less than 10 microns. The porosity of polyethylene or polypropylene lithium-ion battery separators can generally only reach about 50%; polyethylene lithium The closed cell temperature of the ion battery separator is the melting point of polyethylene, about 130°C, and the closed cell temperature of the polypropylene lithium ion battery separator is about 150°C