Water-based conductive adhesive for lithium battery and preparation method thereof

Abstract

The invention provides a water-based conductive adhesive for a lithium battery, and the adhesive comprises 0.01-0.8 part of single-walled carbon nanotube, 1-10 parts of multi-walled carbon nanotube and 10-50 parts of water-based adhesive, wherein the outer diameter of the single-walled carbon nanotube is 0.4-40nm, and the thickness of the tube wall of the single-walled carbon nanotube is greater than or equal to 1[mu]m; the outer diameter of the multi-walled carbon nanotube is 2-20nm, and the thickness of the tube wall of the multi-walled carbon nanotube is 500nm-10cm; and the length-diameterratio of the single-walled carbon nanotube to the multi-walled carbon nanotube is greater than or equal to 1,000nm. The water-based conductive adhesive for the lithium battery, which is prepared by adopting a simple process of one-step synthesis and one-step dispersion, has the properties of electric conduction, adhesion and dispersion, is low in dosage, and can reduce the internal resistance of the battery, improve the adhesion force of a pole piece and improve the cycle performance of the battery; in addition, the preparation cost of the water-based conductive adhesive is low, water is usedas a solvent in the whole process, and the water-based conductive adhesive conforms to the trend of environmental protection.

Description

technical field [0001] The invention relates to the technical field of lithium ion battery materials, in particular to a water-based conductive binder for lithium batteries and a preparation method thereof. Background technique [0002] At present, there are three main categories of binders widely used in lithium-ion batteries: polyvinylidene fluoride (PVDF for short), styrene-butadiene rubber (SBR for short), sodium carboxymethyl cellulose (CMC for short), Among them, PVDF is mainly used for oil-based positive electrodes of lithium-ion batteries, and N-methylpyrrolidone (NMP for short) is used as a solvent, which is not environmentally friendly and has a high cost; SBR and CMC are mainly used for water-based negative electrodes of lithium-ion batteries. , the dosage is large, and the adhesion is poor. At the same time, the battery made by using it has a great internal resistance, and there are certain problems with the dispersion performance of nanomaterials. In addition, t...

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Problems solved by technology

[0002] At present, there are three main categories of binders widely used in lithium-ion batteries: polyvinylidene fluoride (PVDF for short), styrene-butadiene rubber (SBR for short), sodium carboxymethyl cellulose (CMC for short), Among them, PVDF is mainly used for oil-based positive electrodes of lithium-ion batteries, and N-methylpyrrolidone (NMP for short) is used as a solvent, which is not environmentally friendly and has a high cost; SBR and CMC are mainly used for water-based negative electrodes of lithium-ion batteries. , the dosage is large, and the adhesion is poor. At the same time, the battery made by using it has a great internal resistance, and there are certain problems with the dispersion performance of nanomaterials. In addition, the above-mentioned binders are not conductive, and the battery production The factory needs to add additional conductive agent to the positive electrode or negative electrode electrode slurry in the process of making lithium batteries, which makes the battery manufacturing process cumbersome and easily causes the main material of the positive and negative electrodes, the conductive agent and the binder. Uneven dispersion, unable to give full play to the advantages of the conductive agent on the conductive properties of the positive or negative main material, or the adhesion of the electrode is not high enough, easy to drop powder, destroy the capacity performance of the positive or negative main material itself, and cause Poor battery cycle performance

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