Preparation method of polyimide nanometer lithium ion battery diaphragm and product thereof

Abstract

The invention discloses a preparation method of a polyimide nanometer lithium ion battery diaphragm and a product thereof. The preparation method comprises the following steps: preparing a polyamide acid solution, namely, performing condensation polymerization on 4,4'-diaminodiphenyl ether and 4,4'-oxydiphthalic anhydride in dimethylacetamide (DMAc) in a certain ratio; preparing a melt, namely, curing the obtained polymer solution at a certain temperature to obtain a condensate, and melting the condensate within the range of 20-30 DEG C below a melting point to obtain a semi-crystalline melt; preparing a diaphragm, namely, treating the obtained melt through a series of process including melt spinning, recrystallization, cold and thermal stretching and heat setting to obtain a nanometer diaphragm; carrying out diaphragm post-treatment, namely, removing a diluent and a part of remaining solvent in the diaphragm, and drying a polyamide acid diaphragm in vacuum; carrying out imidization treatment, namely, performing high-temperature imidization treatment on the prepared polyamide acid nanometer diaphragm to obtain the polyimide nanometer diaphragm. The prepared product is excellent in performance, and easy and convenient to process.

Description

technical field [0001] The invention relates to a preparation method and a product of a lithium-ion battery diaphragm. Background technique [0002] As one of the most important components of lithium-ion batteries, the diaphragm is called the "third pole" of the battery. Its main function is to isolate the direct contact between the positive and negative electrodes, prevent short circuits, and provide a channel for the reciprocating movement of lithium ions. At present, the separator widely used in lithium-ion batteries is mainly polyolefin separator, and its preparation process is divided into dry method and wet method. The biggest defect of the polyolefin separator is that it has poor contact with the organic electrolyte and is not easily wetted by the electrolyte, which seriously affects the improvement of ionic conductivity. There have been many patents describing the preparation of single-layer or double-layer polyolefin diaphragms and various modified diaphragms by dr...

AI Technical Summary

Problems solved by technology

The above formula enhances the strength of the membrane, and the separator basically meets the requirements of the lithium-ion battery for the separator, but there are the following defects: the pore size of the formed separator is not uniform, which affects its performance in the battery

However, the processing of this diaphragm is complicated and its performance is not ideal.

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