Lithium-ion battery diaphragm, preparation method of lithium-ion battery diaphragm, as well as lithium-ion battery comprising diaphragm

Abstract

A separator for a lithium-ion battery includes a substrate, a coating, and a middle layer formed between the substrate and the coating. The middle layer includes a part of the substrate and a part of the coating. The substrate contains a base polymer, a first polymer, and a first inorganic material. The coating contains a second polymer and a second inorganic material. The first polymer and the second polymer independently contain an acid radical in a side chain thereof. The first inorganic material is reactive with the first polymer via a first neutralization reaction, and the second inorganic material is reactive with the second polymer via a second neutralization reaction. A method for preparing a separator for a lithium-ion battery and a lithium-ion battery are also provided.

Description

technical field [0001] The invention belongs to the field of lithium ion batteries, and in particular relates to a lithium ion battery diaphragm, a preparation method thereof and a lithium ion battery containing the diaphragm. Background technique [0002] The separator of lithium-ion secondary batteries is usually a thin porous insulating material, which has high ion permeability, good mechanical strength, and long-term stability to various chemicals and chemical solvents. Therefore, the non-conductivity of the separator is used to separate the positive and negative electrodes of the battery to prevent the two electrodes from contacting and short circuit; at the same time, relying on the microporous structure of the separator itself, lithium ions can easily pass through and maintain good ionic conductivity between the positive and negative electrodes. . When an abnormally large current is generated inside the battery due to a short circuit or wrong connection externally, w...

AI Technical Summary

Problems solved by technology

[0005] The coating prepared by the above method has poor adhesion to the sheet-shaped flexible substrate, and the ceramic layer and the substrate are bonded only by the binder in the ceramic layer, and the bonding strength is weak. Processing the diaphragm, winding electrode group and During the charging and discharging process of the battery, the coating particles are more likely to fall off, thereby reducing the high temperature resistance of the battery separator produced according to the above method, and the shedding ceramic particles will also cause uneven performance of the separator and affect the consistency of battery performance; It will also increase the migration resistance of lithium ions in the electrolyte, which is not conducive to fast charging and fast discharging; it may also migrate to the surface of the positive and negative electrodes, affecting the insertion and extraction of lithium ions; it may even cause pinholes in the diaphragm, causing a short circuit between the positive and negative electrodes of the battery, etc. , which seriously affects the performance of the battery and affects its practical application