Flame-retardant porous polymer film and preparation method thereof

Abstract

The invention provides a preparation method for a flame-retardant porous polymer film. The method comprises the following steps of: a, dissolving the polymer with an organic solvent and adding a pore-forming agent into the dissolved polymer to obtain emulsion; b, coating the emulsion on a matrix and carrying out drying or extraction treatment on the matrix to obtain a porous polymer-based film; and c, plating an aluminum hydroxide film on the surface of the porous polymer-based film and heating the obtained product to decompose the aluminum hydroxide on the surface of the matrix into aluminum oxide to obtain the flame-retardant porous polymer film. The invention also provides the flame-retardant porous polymer film prepared by the method and a battery containing the same. The flame-retardant porous polymer film prepared by the method of the invention has uniformly dispersed aluminum oxide, so that the obtained flame-retardant porous polymer film has uniform flame retardance and the use safety of the battery is improved.

Description

technical field [0001] The invention relates to the flame retardant field, in particular to a flame retardant porous polymer film and a preparation method thereof. Background technique [0002] When the positive and negative electrodes of the lithium-ion battery are short-circuited, it is easy to cause internal combustion of the battery, which will affect the safety of the entire electrical equipment. In order to solve this problem, a flame retardant layer is usually added between the positive and negative electrodes of the battery. At the same time, in order not to affect the migration of lithium ions between the positive and negative electrodes in the battery, the flame retardant layer used must have a porous structure. Coating a porous polymer film with flame-retardant properties on the surface of the positive electrode, negative electrode or diaphragm of the battery can avoid the internal combustion phenomenon caused by the short circuit of the battery and improve the sa...

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Problems solved by technology

The above method can prepare a porous polymer membrane with uniform membrane pores and strong liquid absorption capacity, but the strength and flame retardancy of the membrane are insufficient.

In order to improve the strength and flame retardancy of the film, the existing preparation method of the flame retardant porous film is to add Al to the polymer solution containing the pore forming agent. 2 o 3 Powder is used as a reinforcing agent, the solution is stirred into a suspension and then coated to form a film, but the disadvantage of using the above method is that Al 2 o 3 Powders are prone to agglomeration in solution, therefore, Al 2 o 3 It is difficult for the powder to disperse uniformly in the solution system, so that the Al 2 o 3 The distribution in the film is not uniform, thus, on the one hand, the Al 2 o 3 The large particles after agglomeration will block the membrane pores and affect the normal operation of the battery. On the other hand, there is no Al around some membrane pores. 2 o 3 distribution, resulting in poor local flame retardancy of the film, which poses a safety hazard to the battery during use

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