Ceramic diaphragm and preparation method thereof, and lithium ion battery

Abstract

The invention discloses a ceramic diaphragm and a preparation method thereof, and a lithium ion battery. The method comprises steps that (1) ball milling of alumina ceramics is performed to obtain alumina ceramic powder; (2), mixing binder with organic solvent and polytetraethylene-pyridine is performed to obtain glue solution; (3), mixing the said alumina ceramic powder with the glue solution isperformed to obtain slurry; and (4), the slurry is applied to at least a part of a base film, and the ceramic diaphragm is obtained after drying. The method is advantaged in that the method can prepare the ceramic diaphragm with high air permeability and good thermal stability, the ceramic diaphragm can capture Mn2+ ions, the Mn2+ ions are applied to in a lithium ion battery, deposition of dissolved manganese on a negative electrode can be effectively reduced, and thereby safety performance and cycle performance of the lithium ion battery are improved.

Description

technical field [0001] The invention belongs to the field of lithium ion batteries, and in particular relates to a ceramic diaphragm, a preparation method thereof and a lithium ion battery. Background technique [0002] Lithium-ion batteries have the characteristics of high energy density, high specific power, good cycle performance, no memory effect, and no pollution. They have good economic benefits, social benefits, and strategic significance. They have become the most eye-catching green chemical power sources. [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 microporous structures, such as single-layer or multi-layer films of polyethylene (Polyethylene, PE) and polypropylene (Polypropylene, PP). Due to the characteristics of th...

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Problems solved by technology

LiPF 6 Decomposition of LiPF occurs in the electrolyte 6 =LiF+PF 5 , in the presence of water in the electrolyte, PF 5 Further decomposition of PF will occur 5 +H 2 O=2HF+PF 3 O, HF and Lewis acid (PF) produced by the above reaction 5 、PF 3 O, etc.) can cause side reactions in lithium-ion batteries, leading to battery performance degradation, such as studies have shown in LiFePO 4 Adding 1000ppm of moisture to the graphite battery will lead to a significant decrease in the cycle life of the battery, and the life is less than 50 times. The EIS test shows that adding moisture to the battery will lead to a significant increase in the internal resistance of the battery, which shows that the extra moisture is cause LiPF in the electrolyte 6 Decomposition occurs, and the generated HF and Lewis acid will cause side reactions in the battery, so that the lithium-ion battery will form a high-impedance SEI film, which will affect the life of the lithium-ion battery

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