Lithium ion battery aqueous adhesive as well as preparation method and lithium ion battery electrode piece thereof

Abstract

The invention provides a lithium ion battery aqueous adhesive as well as a preparation method and a lithium ion battery electrode piece thereof. The lithium ion battery aqueous adhesive has a structure of formula I as shown in the specification. By modifying hydroxyl in a water-soluble polymer repetitive unit group, purposes of introducing a flexible side chain polarity group with a polarity anion group and improving the polarity of a polymer and a current collector can be achieved, so that the adhesive force can be improved, in addition, the flexibility of the polymer can be improved, an electrode piece with good flexibility can be manufactured, and furthermore the electrode piece has high primary coulombic efficiency. The aqueous adhesive provided by the invention is simple in preparation method, gentle in condition, easy in raw material obtaining and applicable to popularization and application.

Description

technical field [0001] The invention belongs to the field of lithium-ion battery materials, and relates to a lithium-ion battery water-based binder, a preparation method thereof, and a lithium-ion battery pole piece. Background technique [0002] Today, lithium-ion batteries have been widely used in products such as mobile phones, computers and electric vehicles, and have great commercial value. At present, the cathode materials of commercial lithium-ion batteries are based on oxides such as LiCoO 2 , LiMn 2 o 4 and LiFePO 4 etc.; the negative electrode material is mainly graphite. Due to the low theoretical capacity of graphite (372mAh / g), it is difficult to meet the needs of the rapid development of today's electronic information and energy technologies. Therefore, high-capacity silicon-based materials (theoretical capacity 4200mAh / g) have been developed. g) It has become a major issue in the development of lithium-ion battery technology. However, because silicon-base...

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Problems solved by technology

Using PVDF as a binder, organic solvents such as nitrogen methylpyrrolidone (NMP) used to dissolve PVDF are harmful to the environment and human body, and are expensive

When SBR is used as a binder, cellulose (CMC) must be added as a thickener at the same time, but CMC is generally viscous, brittle, and poor in flexibility, and the pole piece is easy to crack when charging and discharging.

At the same time, when the SBR binder is a point-to-point bonding mechanism, when it is applied to a new type of silicon-based composite negative electrode, due to the large volume expansion of the silicon-based base during charge-discharge cycles, the point-to-point bonding is easy to lose its cohesiveness, which deteriorates the electrical performance.

PAA is used as the binder. Because the polymer has a high glass transition temperature and is relatively hard at room temperature, it is easy to cause the pole piece to be hard and brittle. Therefore, the binder is prone to cracking during the coating process. There are many stripes, edge decarburization during cutting, and powder dropping at the bending of the pole piece during the winding process. The processing performance is poor, which seriously restricts its application in batteries.

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