Ceramic diaphragm and preparation method thereof

Abstract

The present invention provides a ceramic diaphragm comprising a diaphragm substrate having a surface coated with a polymer-coated functional ceramic powder. The polymer coating the surface of the ceramic powder is polystyrene sulfonic lithium (PSSLi) and a polyethylene glycol methacrylate hydrocarbon microporous diaphragm. The diaphragm substrate is a polyolefin microporous diaphragm. The polyethylene glycol methacrylate (PEGMA) has an average molecular weight of 400 to 5000 g / mol. The method provided by the invention comprises firstly activating the ceramic powder by using a silane coupling agent; then introducing a halogen functional group to graft the ceramic powder with a halogen initiator; adding sodium benzenesulfonate monomer (SSNa) and polyethylene glycol methacrylate (PEGMA) for apolymerization reaction; then adding the mixture to a lithium ion aqueous solution for ion exchange to obtain the polymer-coated functional ceramic powder; and finally stirring the polymer-coated functional ceramic powder to form a ceramic slurry and form the polymer-coated ceramic diaphragm by coating. The method provided by the present invention greatly improves the dispersibility and the functionality of lithium ions.

Description

technical field [0001] The invention belongs to the technical field of lithium-ion batteries, and in particular relates to a ceramic separator for lithium-ion batteries and a preparation method thereof. More specifically, the invention relates to a method of grafting single-ion conductive polymers to The surface of ceramic powder, thereby improving the dispersion and functionality of ceramics. Background technique [0002] In the lithium-ion battery structure, the diaphragm is one of the key inner components. The diaphragm is located between the positive electrode and the negative electrode. , can maintain the necessary electrolyte and form a channel for ion movement. With the vigorous development of the new energy industry in recent years, higher requirements have been placed on the separator. The performance of the separator determines the interface structure and internal resistance of the battery, which directly affects the capacity, cycle and safety performance of the b...

AI Technical Summary

Problems solved by technology

The main reason is that some atoms or groups in the molecule are close to each other and the tension in the molecule caused by the steric hindrance and deviation from the normal bond angle) is relatively large, that is, the sodium benzenesulfonate derivatives all contain rigid benzene rings with high tension. When such reagents attack Al as nucleophiles 2 o 3 When the surface hydroxyl group, due to the influence of the larger steric hindrance of the benzene ring connected by the sulfonic acid group, the reaction rate of the two reactants is greatly reduced, thus reducing the Al 2 o 3 The number of reactions between hydroxyl groups and sodium sulfonate derivatives on the surface of ceramics, thereby reducing the grafting rate of ceramics

Al on ceramic surface 2 o 3 Only part of the hydroxyl groups in the ceramics are successfully grafted and covered, and most of the free hydroxyl groups fail to react with the surface active monomers to be grafted and covered. When the ceramics are dispersed, there will still be free hydroxyl groups to obtain intramolecular hydrogen bonds. resulting in a large amount of ceramic agglomeration

The result must be that the dispersion problem of ceramics has not been fundamentally solved, and due to the low grafting rate, Li can be exchanged + Also less, unable to meet functional requirements

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