Lithium ion battery composite binder and preparation method and application thereof

Abstract

The invention discloses a lithium ion battery composite binder and a preparation method and application thereof, and belongs to the technical field of lithium ion battery materials. Comprising a binder component A and a binder component B. The binder component A is prepared by performing cross-linking reaction on sodium alginate (SA), polyvinyl alcohol (PVA) and polyacrylic acid (PAA) and then compounding with a carbon nanotube aqueous dispersion liquid; the binder B component is PVA (polyvinyl alcohol) modified rubber emulsion; the mass ratio of the binder component A to the binder component B is (2-10): 1. The binder component A has a large number of ester groups and hydroxyl groups, so that the surface acting force of the binder and silicon particles can be enhanced, and the binding power is improved; the composite binder disclosed by the invention has relatively good binding performance, the binding force between an active material in an electrode and a current collector can be improved, the binding force of a pole piece can reach 0.45-0.57 N / 25mm, and the swelling rate is 11.9-13.4%.

Description

technical field [0001] The invention relates to the technical field of lithium-ion battery materials, and more specifically, to a lithium-ion battery composite binder and its preparation method and application. Background technique [0002] With the further expansion of the application field of lithium-ion batteries, there are higher requirements for the charge-discharge performance of lithium-ion batteries in low-temperature environments. It is hoped that they can be used in northern cold regions. At -20 ° C or even lower temperatures, lithium-ion batteries Ion batteries can work normally; but the low-temperature performance of lithium-ion batteries is poor. The charging temperature of traditional lithium-ion batteries is from 0°C to +45°C, and the discharge temperature is from -20°C to +60°C, below -20°C It cannot be discharged normally in a low temperature environment, and cannot be charged in a low temperature environment below 0°C. Therefore, it has become a market dem...

AI Technical Summary

Problems solved by technology

The polymer whose binder is an insulator will seriously affect the low-temperature performance of the lithium-ion battery due to the decrease in the molecular segment movement ability of the polymer in a low-temperature environment.

[0004] Sodium carboxymethyl cellulose and styrene-butadiene latex are commonly used as binders for negative electrodes of traditional lithium-ion batteries. These two substances have stable chemical properties and electrochemical properties, but in the silicon negative electrode material system, the inhibitory effect on the expansion of silicon particles Weak, leading to SEI film damage, pulverization, and significant increase in impedance, especially in low temperature environments, resulting in loss of lithium, resulting in lithium precipitation, reducing the service life of lithium batteries

And this type of binder polymer has a poor affinity with the electrolyte, resulting in the inability of the electrolyte to penetrate into the active material particles of the electrode, thereby increasing the interface resistance of the electrode and the internal resistance of the battery, which seriously affects the battery life. Low temperature performance

[0005] Therefore, it is of great significance to develop a binder to solve the problem of poor low-temperature performance of lithium-ion batteries in the prior art

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