Polymer-modified ceramic-coated composite separator and application thereof

Abstract

The invention discloses a polymer-modified ceramic-coated composite separator and an application thereof. The polymer-modified ceramic-coated composite separator comprises an organic separator base material, a ceramic layer and polymers, wherein the ceramic layer coats the surface of the separator base material and is 0.1-20 microns in thickness; the polymers grow in situ on the surfaces of the separator base material and the ceramic layer and inside the separator base material and the ceramic layer; the polymers are polymethyl methacrylate, polyvinylidene fluoride-perfluoropropylene, polyacrylonitrile, polyimide, polyether amide, or polyethylene oxide and the like ; the particle size of inorganic powder in the ceramic layer is 5nm to 10 microns; and the molecular weight of the material of the organic separator base material is 1,000-100,000,000. According to the polymer-modified ceramic-coated composite separator disclosed by the invention, due to the presence of the polymers, and the potential safety hazards caused by dusting and liquid leakage of the ceramic layer can be effectively reduced; the physical property and the electrochemical properties of the separator are effectively improved; meanwhile, due to the presence of the polymers, the interface stability between a separator electrolyte and an electrode can also be improved; and generation of lithium dendrites can be effectively suppressed by improvement of the interface stability. Therefore, improvement of the capacity retention ability of a battery is facilitated.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a polymer-modified ceramic composite diaphragm and an application thereof. Background technique [0002] As a chemical power system with high energy density, high output voltage, no memory effect, excellent cycle performance, and environmental friendliness, lithium-ion battery has good economic benefits, social benefits and strategic significance, and has been widely used in mobile communications, Digital products and other fields, and it is very likely to become the most important power supply system in the field of energy storage and electric vehicles. [0003] In lithium-ion batteries, the separator mainly plays the role of preventing positive and negative electrodes from contacting and allowing ion conduction, and is an important part of the battery. At present, commercial lithium-ion batteries mainly use polyolefin diaphragm materials with micropor...

AI Technical Summary

Problems solved by technology

However, due to the large specific surface energy of ceramic powder, it is easy to agglomerate, and its surface is generally hydrophilic, while the polyolefin film is a hydrophobic material. Therefore, from most research reports, the uniformity of ceramic powder coating Poor, there is obvious "powder falling" phenomenon, which will greatly affect the performance of ceramic separators in lithium-ion batteries

In addition, although the powder coating of the ceramic diaphragm can improve the affinity with the electrolyte, due to the poor wetting ability of the diaphragm substrate itself and the electrolyte, the existing ceramic diaphragm still has a certain risk of leakage.

Images