Binder as well as preparation method and application thereof

Abstract

The invention provides a binder as well as a preparation method and application thereof. The binder is prepared from polyvinyl alcohol and polyfunctional group sulfonic acid; the mass ratio of the polyvinyl alcohol to the polyfunctional group sulfonic acid is 20: (1-6). The preparation method comprises the following steps: (1) mixing polyfunctional group sulfonic acid with a solvent to obtain a polyfunctional group sulfonic acid solution; mixing polyvinyl alcohol with a solvent to obtain a polyvinyl alcohol solution; and (2) mixing the polyvinyl alcohol solution obtained in the step (1) with the polyfunctional group sulfonic acid solution, and carrying out a cross-linking reaction to obtain the binder. The binder provided by the invention has relatively good toughness and relatively good electrical properties, and is suitable for preparation of a silicon negative electrode lithium ion battery.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a binder and a preparation method and application thereof. Background technique [0002] Today's society requires efficient energy storage systems, and lithium-ion batteries are currently one of the most concerned energy storage devices, mainly used in electric vehicles, smartphones, and tablet computers. The performance of the electrode material is the key to determine the performance of the lithium-ion battery. Among them, the binder is used to bind the conductive agent particles and the active material, and bind them to the surface of the metal current collector. The performance of the binder is closely related to the cycle performance of the battery. relevant. If the performance of the binder is not good, it is easy to cause the electrode to pulverize during the electrochemical cycle, causing the electrode material to fall off from the surface of th...

AI Technical Summary

Problems solved by technology

However, the study found that when polyvinyl alcohol is used as the binder, its toughness is poor after the electrode is dried, and it cannot meet the volume expansion requirements of silicon particles well.

[0007] With the development of science and technology, silicon anode materials are considered to be one of the new generation of promising anode materials for lithium-ion batteries because of their high theoretical specific capacity (4200mAh / g), but there are also some problems with silicon anode materials: On the one hand, silicon will face a large volume expansion (about 300%) in the process of deintercalating lithium, which will cause the electrode material to pulverize and fall off, and lose electrical contact with the current collector, resulting in a significant increase in battery impedance and rapid capacity decay; On the one hand, due to the volume expansion, the destruction and rearrangement of the solid electrolyte interfacial film (SEI) will also occur, and a large amount of active lithium will be lost, causing the battery to fail quickly, which restricts the further development of silicon materials in the lithium-ion battery industry.

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