Low-swelling composite current collector and preparation method thereof

Abstract

The invention relates to a low-swelling composite current collector and a preparation method thereof, the low-swelling composite current collector comprises a thin film substrate layer, and two surfaces of the thin film substrate layer, which are arranged back to back, are respectively provided with a cross-linking layer and a metal layer in sequence; the cross-linking layer is formed by cross-linking a surface cross-linking agent coated on the thin film substrate layer and the thin film substrate layer through a chemical bond effect. The cross-linking layer and the metal layer are sequentially arranged on the two opposite surfaces of the film substrate layer, so that more chemical bonds are formed on the surfaces of the film substrate layer, the binding force of the metal layer and the film substrate layer can be improved, the solubility of the film substrate layer in an electrolyte of a battery is relatively low, and the service life of the battery is prolonged. According to the present invention, the swelling phenomenon of the film substrate layer is reduced, such that the chemical bond between the metal layer and the film substrate layer cannot be damaged so as to improve the peeling force between the metal layer and the film substrate layer, such that the metal layer and the film substrate layer do not easily shed so as to ensure the electrical property and the safety of the battery and the internal resistance stability of the battery.

Description

technical field [0001] The invention relates to the technical field of secondary batteries, in particular to a low-swelling composite current collector and a preparation method thereof. Background technique [0002] The current composite current collectors are mainly copper current collectors and aluminum current collectors, wherein copper current collectors or aluminum current collectors are composed of two parts, including a film substrate layer disposed in the middle and a film substrate layer disposed opposite to each other. metal layers on both surfaces. The thickness of the metal layer is generally required to be about 1 μm, and the method of preparing the composite current collector is completed by the evaporation process. However, since most of the film substrate layers are made of polymer materials such as polyethylene terephthalate (PET), These polymer materials contain a large number of ester groups. After the electrolyte in the battery is in contact with the po...

AI Technical Summary

Problems solved by technology

After the electrolyte in the battery is in contact with the polymer material, the ester group in the polymer material and the ester group in the electrolyte meet and dissolve together, resulting in the thin film substrate layer prone to appear during the long-term use of the battery. The swelling phenomenon destroys the chemical bond between the metal layer and the film substrate layer, which leads to the continuous deterioration of the peeling force between the metal layer of the composite current collector and the film substrate layer, and the metal layer and the film substrate layer are prone to fall off Phenomenon, which in turn affects the positive and negative interfaces inside the battery, resulting in poor electrical performance of the battery, and also affects the safety of the battery

After the polymer material dissolves and enters the electrolyte, it will also increase the viscosity of the electrolyte, which will increase the resistance to ion transmission and lead to an increase in the internal resistance of the battery in the later stage.

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