PET heavy-ion microporous composite membrane for lithium battery and preparation method thereof

Abstract

The invention discloses a PET heavy-ion microporous composite membrane for a lithium battery and a preparation method thereof. The PET heavy-ion microporous composite membrane comprises a microporous PET film with first micro-holes and a multi-micropore material layer with second micropores. The multi-micropore material layer is obtained by curing molding of macromolecule resin and inorganic oxide particles. The preparation method comprises the steps that the macromolecule resin, the inorganic oxide particles and a solvent are mixed to form a colloid material, a PET film base material is coated with the colloid material and cured and molded to form a semifinished product, and irradiation of the semifinished product and an alkaline solution etching reaction are performed to obtain a finished product. The multi-micropore material layer is not etched during micropore PET film forming etching and has the micropore structure where lithium ions can freely migrated, the defect that micropores in a traditional micropore PET film are likely to be superposed is overcome, the purpose of resisting lithium dendrites punctures and pole piece particle puncture is achieved, the whole membrane electrolyte wettability is improved, the pore diameter design range of straight micropores of the micropore PET film is larger, and the production efficiency is high.

Description

technical field [0001] The invention relates to lithium battery diaphragms, in particular to a PET heavy ion microporous composite diaphragm for lithium batteries and a preparation method thereof. Background technique [0002] The patent literature with the Chinese patent application number 201110071317.0 discloses a microporous PET film and its production method. The production method of the PET heavy ion microporous lithium battery diaphragm uses the PET film as the base material, and irradiates the PET film with high-energy heavy particles. According to the irradiation, the irradiated PET film is immersed in a container containing an acid solution or an alkali solution for etching reaction to obtain the final product microporous PET film. However, the microporous PET film prepared by this technical solution has the following defects: (1) the microporous PET film will have a certain probability of having 2 or more microporous heavy holes, and the appearance of heavy holes ...

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Problems solved by technology

However, the microporous PET film prepared by this technical solution has the following defects: (1) the microporous PET film will have a certain probability of having 2 or more microporous heavy holes, and the appearance of heavy holes will lead to a multiple of the aperture. Enlarging, reducing the puncture performance and insulation performance of the diaphragm; (2) The electrolyte wettability of the microporous PET film is not good; (3) The pore size of the microporous PET film needs to be controlled below 2 microns, which requires high pore density to reduce (4) the micropores of the microporous PET film are microporous, and there is a risk of lithium dendrites piercing from the positive electrode to the negative electrode; (5) the single-layer microporous membrane of the microporous PET film, because the pore size is microporous , the ion exchange path is the shortest, and the reaction is faster, but the surface of the positive and negative electrodes is composed of nanometer to micron powder particles, such as the separator is very thin and has straight holes, and the particles of these positive and negative materials are easy to contact in the channels. micro short circuit

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