Composite diaphragm, preparation method thereof and lithium ion battery

Abstract

The invention provides a composite diaphragm, a preparation method thereof and a lithium ion battery. The composite diaphragm comprises a solid electrolyte layer, a base membrane and a polymer microsphere layer which are stacked, the solid electrolyte layer comprises an inorganic filler and a polymer; the polymer comprises any one or a combination of at least two of PVDF (Polyvinylidene Fluoride), PVDF-HFP (Polyvinyl Fluoride-Hexafluoropropylene) or PVC (Polyvinyl Chloride); the polymer microsphere layer comprises polyethylene microspheres. By compounding the two functional material coatings, the thermal hole closing temperature of the composite diaphragm is reduced, meanwhile, the thermal diaphragm breaking temperature is increased, and the safety performance of the lithium ion battery is improved on the premise that the good electrochemical performance of the composite diaphragm is guaranteed.

Description

technical field

[0001] The invention belongs to the technical field of manufacturing lithium ion batteries, and relates to a composite diaphragm, in particular to a composite diaphragm, a preparation method thereof and a lithium ion battery. Background technique

[0002] Lithium-ion batteries are composed of positive electrode materials, negative electrode materials, separators, electrolytes, and battery casings. In the lithium-ion battery structure, the diaphragm is one of the key inner components. The performance of the diaphragm determines the interface structure and internal resistance of the battery, and directly affects the capacity, cycle performance and safety performance of the battery. A separator with excellent performance plays an important role in improving the overall performance of the battery.

[0003] As lithium-ion batteries are used more and more widely, their safety performance and environmental protection requirements are also increasing. At present, t...

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