Lithium ion battery isolating membrane based on dual-drive self-assembly and preparation method thereof

Abstract

The invention discloses a lithium ion battery isolating membrane based on dual-drive self-assembly and a preparation method of the lithium ion battery isolating membrane. The isolating membrane comprises two layers of modified non-woven fabric base membranes and a reinforced coating arranged between the two layers of modified non-woven fabric base membranes, and the modified non-woven fabric basemembranes are prepared by modifying and processing polypropylene non-woven fabric. According to the invention, the polypropylene non-woven fabric is used as a raw material; firstly, methyl methacrylate is used as a monomer, and methyl methacrylate is copolymerized on the surface of acrylic acid, so that the hydrophilicity of the non-woven fabric is improved, and the moisture absorption rate and the water retention rate of the non-woven fabric are further improved; then silicon dioxide is crosslinked and fixed in the non-woven fabric through a silane coupling agent, so that a filling effect isachieved, the equivalent aperture of the non-woven fabric is reduced, and the aperture distribution of the non-woven fabric is more uniform; finally, a layer of honeycomb net structure is formed on the surface of the non-woven fabric intermediate, so that the modified non-woven fabric base membrane is obtained; and the non-woven fabric base membranes have good adsorption capacity and permeation selectivity.

Description

technical field [0001] The invention belongs to the technical field of lithium-ion batteries, and in particular relates to a lithium-ion battery separator based on dual-drive self-assembly and a preparation method thereof. Background technique [0002] Due to its environmental friendliness and high energy density, lithium-ion batteries are currently one of the most widely used secondary batteries in the market, and are also the main development direction of the secondary battery industry. Lithium-ion batteries mainly include positive electrodes, negative electrodes, separators and Electrolyte, in which the diaphragm is used to isolate the positive electrode of the battery from the negative electrode of the battery, and to ensure that the ions in the electrolyte can penetrate it. It can prevent the short circuit of the positive and negative electrodes. Its comprehensive performance directly affects the capacity, cycle performance and internal Therefore, improving the quality ...

AI Technical Summary

Problems solved by technology

[0003] In the prior art, the diaphragm is mainly made of polyolefin material or non-woven fabric material. The cost of polyolefin material is low, but when working in a high temperature environment, the volume of polyolefin tends to shrink, so that the diaphragm loses its isolation effect. A short circuit occurs due to the contact of the negative electrode, which greatly reduces the safety of the battery. At the same time, the separator made of polyolefin material has poor hydrophilicity, which affects the cycle performance of the battery, while the separator made of non-woven material has larger pores. And the distribution is uneven, which will directly affect the properties of lithium-ion batteries. In order to solve the above problems, a lithium-ion battery separator with non-woven fabric as the base material and uniform pore distribution is provided. The present invention provides the following technical solutions