A kind of composite ceramic diaphragm for lithium ion battery and preparation method thereof

Abstract

The invention discloses a composite ceramic separator for lithium ion batteries and a preparation method thereof, including a ceramic coating modification method and a ceramic lithium battery separator. The ceramic protective layer is mainly a mixture composed of ceramics graft-modified by anionic surfactants containing sodium sulfonate or sodium carboxylate groups, and a binder. Grafting is completed under the action of a coupling agent and using the "grafting on" method. The grafting rate of ceramics is relatively high. The modified ceramic separator introduces high-temperature-resistant high-specific surface area nanoceramics onto the surface of the conventional PP separator. The earth improves the insulation and electrolyte wettability of the separator, especially at high temperatures of 130°C, 150°C and 180°C, showing excellent high-temperature thermal stability. The lithium battery composite separator avoids the heat shrinkage of conventional separators, thereby avoiding thermal runaway inside the battery caused by heat shrinkage, thereby improving the safety and reliability of lithium-ion batteries.

Description

technical field [0001] The invention belongs to the technical field of lithium-ion batteries, and in particular relates to a composite ceramic separator for lithium-ion batteries and a preparation method thereof. More specifically, the invention relates to the inclusion of anionic surfactants and the modification and coating of ceramics by grafting, thereby A method to improve the dispersion and adhesion of ceramics. Background technique [0002] Lithium-ion batteries have been widely used as power sources for various mobile devices since their commercialization due to their high energy density, high operating voltage, no memory effect, and long cycle life. And it is very likely to become the most important power supply system in the field of energy storage and electric vehicles. However, with the large-scale application of lithium-ion batteries, battery safety issues have become increasingly prominent. [0003] One of the key factors affecting the safety of lithium-ion pow...

AI Technical Summary

Problems solved by technology

It mainly refers to the steric hindrance caused by some atoms or groups in the molecule being close to each other and the intramolecular tension caused by the deviation from the normal bond angle), that is, the sodium benzenesulfonate derivatives all contain rigid benzene rings with high tension. , when such reagent acts as a nucleophile to attack Al 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 some 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 intramolecular hydrogen bonds of the free hydroxyl groups. resulting in a large amount of ceramic agglomeration

The result must be that the problem of difficult dispersion of ceramics has not been solved fundamentally. On the other hand, due to the low grafting rate, the degree of improvement of the hydrophilic and lipophilic properties of the hydroxyl groups on the ceramic surface is not obvious.

In the later stage of bonding with polyolefin base film, problems such as poor adhesion and easy peeling off of the ceramic coating will occur

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