Lithium battery positive pole with high capacity and high security and preparation method thereof

Abstract

The invention provides a lithium battery positive pole with high capacity and high security and a preparation method thereof. the lithium battery positive pole is prepared from, by weight, 98 parts of positive active material, 0.5-1 part of conductive agent, 0.02-0.05 part of lithium carbonate, 0.8-1.5 parts of adhesion agent and 50 parts of solvent, wherein the adhesion agent comprises, by weight, 5-8 parts of polyvinylidene fluoride, 3-5 parts of glycerol ester of rosin, 2-3 parts of epoxy resin and 0.3-0.6 part of carboxymethyl cellulose sodium. According to the preparation method, PVDF composite lycerol ester of rosin, carboxymethyl cellulose sodium and epoxy resin are used as the adhesion agent to solve the existing problems that when PVDF is used alone as the adhesion agent, crystalline melting temperature is high, charging load and discharging load are high, the adhesive layer of the electrode is easy to peel partly or completely from a current collector, the load characteristic becomes bad, thus capacity deterioration is resulted in. The lithium battery positive pole prepared from the formula has the advantages of high capacity and high security, and the service life of the batter is greatly prolonged.

Description

technical field [0001] The invention belongs to the field of lithium ion batteries, and in particular relates to a high-capacity and high-safety lithium battery positive electrode and a preparation method thereof. Background technique [0002] Polyvinylidene fluoride is often used as a binder in the positive electrode of lithium batteries, but polyvinylidene fluoride is a crystalline polymer with a crystallinity of about 50% and a crystallization melting temperature around 140°C. Therefore, at the normal operating temperature of the battery, When PVDF is used alone as a binder, its crystallinity makes it difficult for molecules in the electrolyte to circulate, and the charge and discharge load increases; when the drying speed during battery preparation is not suitable, the shrinkage of PVDF and the shrinkage of the collector The difference is relatively large, and the coating film containing the active material will be detached from the current collector; even if there is no...

AI Technical Summary

Problems solved by technology

[0002] Polyvinylidene fluoride is often used as a binder in the positive electrode of lithium batteries, but polyvinylidene fluoride is a crystalline polymer with a crystallinity of about 50% and a crystallization melting temperature around 140°C. Therefore, at the normal operating temperature of the battery, When PVDF is used alone as a binder, its crystallinity makes it difficult for molecules in the electrolyte to circulate, and the charge and discharge load increases; when the drying speed during battery preparation is not suitable, the shrinkage of PVDF and the shrinkage of the collector The difference is relatively large, and the coating film containing the active material will be detached from the current collector; even if there is no problem after coating and drying, as time goes by, the internal stress of the electrode will cause the electrode binder to be damaged during use. The layer is partially or completely peeled off from the current collector, and the load characteristics deteriorate, causing capacity degradation

At the same time, the price of polyvinylidene fluoride is relatively high, and using it as a positive electrode binder will lead to high production costs of lithium batteries