High-temperature resistant composite battery separator and preparation method thereof

Abstract

The invention discloses a high-temperature resistant composite battery separator and a preparation method thereof. The high-temperature resistant composite battery separator comprises a base film anda high-temperature resistant coating layer, wherein the high-temperature resistant coating layer is coated on at least one surface of the base film and is formed by coating inorganic particles containing nanometer cellulose as a binding agent. In the composite battery separator, the nanometer cellulose is creatively used as the binding agent to prepare the high-temperature resistant coating layer,the interface bonding force of the coating layer and the base film is improved, the stripping strength of the composite battery separator is further improved, and the problems of falling and powder dropping of the coating layer are solved very well; with the addition of the nanometer cellulose, the inorganic particles are better in dispersion effect in water; moreover, the nanometer cellulose isused as the binding agent to form the coating layer, the high-temperature resistant composite battery separator is rapid in liquid conductivity and high in liquid absorption capability, gel is easilyformed after the electrolyte is absorbed, so that the composite battery separator can be attached onto a surface of an electrode very well, and the integral performance of the lithium ion battery is improved.

Description

technical field [0001] The present application relates to the field of lithium-ion battery separators, in particular to a high-temperature-resistant composite battery separator and a preparation method thereof. Background technique [0002] Lithium-ion battery separator is a porous membrane. The main function of the lithium-ion battery separator in the lithium-ion battery is to isolate the positive and negative electrodes of the battery to prevent the internal short circuit of the battery; to provide a channel for the migration of lithium ions during charging and discharging, and to allow lithium ions to pass through. The pre-commercialized diaphragms are mainly divided into dry-process unidirectional stretched diaphragms and wet-process biaxially stretched diaphragms. See patent US5480745, JP2004323820. [0003] In order to further improve the ability of the lithium battery separator to absorb electrolyte, improve the thermal stability of the separator and the ability to ...

AI Technical Summary

Problems solved by technology

However, the bonding effect of existing adhesives is limited

Moreover, there is no stress conduction between the ceramic particles, and the mechanical strength of the diaphragm decreases; the ceramic particles are easy to fall off from the surface of the diaphragm, that is, powder, which causes the diaphragm to be broken down during the hot pressure test of the cell, and the particles mixed between the diaphragm and the pole piece Particles will cause micro-short circuit inside the separator, high probability of self-discharge, and affect battery performance

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