A kind of lithium battery negative electrode binder and its preparation method and application

Abstract

The invention provides a lithium battery negative electrode binder and its preparation method and application. The lithium battery negative electrode binder is calculated in parts by mass, and the preparation raw materials include the following components: 40.0-55.0 parts of polyacrylonitrile compounds, 5.0-20.0 parts of butadiene compounds and 5.0-20.0 parts of styrene compounds; the polyacrylonitrile compounds are polyacrylonitrile and / or polyacrylonitrile derivatives, and the butadiene compounds is butadiene and / or butadiene derivatives, and the styrene compound is styrene and / or styrene derivatives. The preparation method of the binder includes an ultrasonic polymerization step and a homogeneous mixing step, and is easy to operate without adding initiator and plasticizer. The negative electrode sheet prepared by using the binder has the advantages of small impedance and not easy to break during processing, which further improves the safety performance of the lithium battery.

Description

technical field [0001] The invention belongs to the technical field of lithium battery processing, and in particular relates to a lithium battery negative electrode binder and a preparation method and application thereof. Background technique [0002] In recent years, with the vigorous development of the drone market, high-rate polymer lithium batteries have gradually become known to people. When the lithium battery is discharged at a high rate, due to the sharp rise in the surface temperature of the battery, an undercut will generally appear in the initial stage of the discharge curve. In order to solve this problem, the high-rate polymer lithium battery needs to reduce the impedance of the positive and negative plates as much as possible. The conductivity of the electrolyte can be increased under the condition of constant viscosity, and the porosity of the separator can also be appropriately increased to make the lithium battery discharge. Polarization in the process is m...

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Problems solved by technology

[0003] At present, the method to reduce the impedance of the negative electrode sheet is mainly to increase the content of the negative electrode conductive agent, but this method will lead to a corresponding decrease in the content of the negative electrode active material, thereby reducing the capacity of the battery

Under the premise of not reducing the battery capacity, the impedance of the negative electrode sheet prepared by using different negative electrode binders is quite different. For example, the impedance of the negative electrode sheet prepared by using polyacrylonitrile emulsion as the binder is small, but the disadvantage is: the negative electrode sheet is coated It is easy to crack in the cloth process, brittle in the rolling and bending process, and easy to drop powder in the electrode sheet cutting process; the negative electrode sheet prepared with styrene-butadiene rubber as the binder has a large impedance, but it has the property of coating without cracking , the pole piece is soft and so on

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