Preparation method of adhesive for improving cycling stability of silicon electrode of lithium battery

Abstract

The invention discloses a preparation method of an adhesive for improving cycling stability of a silicon electrode of a lithium battery, which comprises the following steps that acrylic acid, deionized water, graphene coated cobalt molybdate reticulate nanosheets, carboxymethyl cellulose and a photoinitiator are uniformly mixed and then are directly ultraviolet light cross-linked through an in-situ polymerization method, so that the adhesive containing a polyacrylic acid grafted carboxymethyl cellulose copolymer is obtained. According to the preparation method disclosed by the invention, the graphene coated cobalt molybdate reticulate nanosheets are added into the adhesive, and the network structure of the material is utilized, so that the nano silicon particles can be effectively prevented from moving in the circulation process, the electrode structure is kept stable, and the cycling stability of the electrode is facilitated.

Description

technical field [0001] The invention relates to the field of lithium batteries, in particular to a lithium battery binder, in particular to a preparation method of a binder for improving the cycle stability of a silicon electrode of a lithium battery. Background technique [0002] Lithium-ion batteries are currently one of the most extensively researched and in-depth energy storage devices. Because of their advantages such as high capacity density, high cycle life, environmental protection, wide operating temperature range and high safety performance, they are widely used in smartphones, Tablet PCs, electric vehicles and other fields. The mechanical properties of the binder are closely related to the cycle life of the battery. If the mechanical properties are not good, it is easy to cause the electrode sheet to pulverize during the electrochemical cycle, causing the electrode material to fall off the surface of the current collector and lose the electrochemical energy storag...

AI Technical Summary

Problems solved by technology

The general problem of the current polyvinylidene fluoride lithium battery binder products on the market is that the molecular weight distribution is wide. Judging from the viscosity of PVDF solution with the same percentage content, the narrow molecular weight distribution has a relatively high viscosity, that is to say Has relatively high adhesive properties

In addition, polyvinylidene fluoride is a semi-crystalline polymer, the crystallinity is generally about 40%, and the crystallization temperature is around 140°C. Regarding the crystallinity of PVDF, on the one hand, the higher the crystallinity, the more difficult it is for ions to migrate. It is easy to lead to an increase in the internal resistance of the battery. On the other hand, the higher the crystallinity of polyvinylidene fluoride, the more difficult it is for ions to migrate in the pole piece, resulting in an increase in the internal resistance of the battery. At the same time, the higher the crystallinity, the internal stress of the electrode makes the electrode active. The substance is partially or completely peeled off from the current collector, causing the capacity to deteriorate. Therefore, the appropriate crystallinity has a certain impact on the performance of the battery