Composite nanofiber lithium battery diaphragm and making method thereof

Abstract

The invention relates to a composite nanofiber lithium battery diaphragm and a making method thereof. The composite nanofiber lithium battery diaphragm is obtained by compounding at least one layer of an aramid 1313 nanofiber film containing nanoparticles with at least one layer of a low-melting-point polymer nanofiber film containing nanoparticles, and nanofibers in the fiber films containing nanoparticles are mutually interlaced and are bonded and connected with each other at interlaced points. The aperture range and the pore closing temperature of the surface layer of the fibers in the composite nanofiber lithium battery diaphragm are 100-400nm and 130-170DEG C respectively, the fiber film does not shrink after the pore closure, the heat shrinkage is less than 2% after the fiber film is heated at 250DEG C for 1h, and the tensile strength is 100-1000MPa, so the composite nanofiber lithium battery diaphragm has the characteristics of heat closing effect, good heat dimension stability and high strength. The making method has the advantages of simple process and low cost, and the obtained composite nanofiber lithium battery diaphragm has a wide application prospect in energy storage fields of supercapacitors, sodium ion batteries and the like.

Description

Technical field [0001] The invention relates to a diaphragm material used for energy storage devices such as lithium ion secondary batteries and a preparation method thereof, in particular to a high-performance composite nanofiber lithium battery diaphragm and a preparation method thereof, and belongs to the technical field of lithium battery diaphragm manufacturing. Background technique [0002] Lithium-ion batteries have been widely used in electrical equipment such as mobile communications, notebook computers, small cameras, etc. because of their high energy density, long cycle life, fast charge and discharge, no pollution and no memory effect. It also shows good application prospects and potential economic benefits in the fields of electric vehicles, aerospace, energy storage, and military. As the core and key component of the battery, the diaphragm is mainly used to separate the positive and negative electrodes of the battery to prevent the two poles from contacting and shor...

AI Technical Summary

Problems solved by technology

Due to its good chemical stability, polyvinylidene fluoride is widely used as a diaphragm material, which has attracted widespread attention of researchers, such as (CN200910077740.4), (CN201110003226.3), (CN201110003213.6), but due to the The high crystallinity results in low ionic conductivity and low heat resistance, which poses a safety hazard during use

In order to improve the heat resistance of the separator, researchers mainly adopt the following two methods: one is to improve the heat resistance of the nanofiber separator by in-situ generation of sol-gel or adding nanoparticles or coating a solution containing nanoparticles, Such as CN200810244343.7, CN201110434221.6, Research on Advanced Lithium-ion Battery Diaphragm Materials Based on Electrospinning Fibers (Ph. CN201210280002.1, the preparation process of these methods is complicated, and generally requires coating process, hot-pressing treatment or extraction and other processes. At the same time, when the diaphragm is closed, the volume shrinks and the membrane area shrinks, so that the diaphragm loses the partition function between the positive and negative electrodes. Cause unsafe hidden danger; The 2nd, use the polymer solution of high heat resistance to carry out electrospinning, as CN201210425855.X, CN201010166400.1 and CN201210169182.6, the fiber membrane function of this method preparation is single, can not satisfy simultaneously The excellent thermal dimensional stability and good self-closing performance that the diaphragm material should have will cause potential hazards such as combustion and explosion of the battery.

Chinese patent CN200910011641.6 discloses an electrospinning preparation method of a high-performance polyarylether resin lithium battery diaphragm. The diaphragm prepared by this method has both thermal dimensional stability and self-closing function, but its strength is poor (Influence of Collecting on Fiber Orientation, Morphology and Tensile Properties of Electrospun PPESK Fabrics (3.677MPa)), which cannot meet the actual production needs of lithium batteries, and because the two fibers are entangled together during the spinning process, there is a serious occurrence when the diaphragm is closed. Potential hazards of volume shrinkage

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