Phenyl organic acid compound modified graphite negative electrode material and preparation method thereof

Abstract

The invention belongs to the technical field of battery negative electrode materials, and provides a phenyl organic acid compound modified graphite negative electrode material, the negative electrodematerial comprises a phenyl organic acid compound and graphite, and the weight ratio of the phenyl organic acid compound to the graphite is 1-6: 100; according to the structural general formula of thephenyl organic acid compound, RA1 is a hydrocarbyl organic acid group containing a carbon-carbon single bond, a carbon-carbon double bond or a carbon-carbon triple bond, and the organic acid group isone or two of sulfonic acid, phosphonic acid, boric acid and carboxylic acid. The invention also provides a preparation method of the negative electrode material. According to the preparation method,the first coulombic efficiency of the graphite negative electrode is remarkably improved, the lithium consumption caused by rupture and reforming of a SEI membrane in the long-term cycle process of the battery is greatly reduced, and the long-term cycle stability and the high-temperature cycle stability of the battery are remarkably improved.

Description

technical field [0001] The invention relates to the technical field of battery negative electrode materials, in particular to a graphite negative electrode material modified with a phenyl organic acid compound and a preparation method thereof. Background technique [0002] Graphite is currently the most commonly used negative electrode material for high-performance lithium-ion batteries. It not only has the advantages of abundant raw materials, low cost, low reaction potential, and good conductivity, but also shows a small volume effect during battery charging and discharging. Graphite is used as The market for lithium-ion battery anode materials has reached hundreds of thousands of tons per year. However, graphite anode materials also have some problems and challenges in the large-scale application of electric vehicles and large-scale energy storage. One of the outstanding problems is how to ensure the solid electrolyte interface film formed on the graphite surface under th...

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Problems solved by technology

However, graphite anode materials also have some problems and challenges in the large-scale application of electric vehicles and large-scale energy storage. One of the outstanding problems is how to ensure the solid electrolyte interface film formed on the graphite surface under the condition of aqueous binder ( SEI film) has good stability and high lithium conductivity, further expands the working temperature range of graphite anodes, and meets the requirements of power vehicles and large-scale energy storage

[0003] The interface stability of graphite is the most critical and core issue restricting the performance of batteries. In order to stabilize the surface of graphite materials, people have developed many effective methods, including the coating technology of zero-strain materials, such as TiO2, Al2O3 surface coating, this non-electrochemical The active oxide coating layer has the advantages of high strength and good stability, but these inorganic oxides are brittle and cannot tolerate the volume change of graphite materials during charging and discharging, and are easy to break and fall off, so modification cannot be achieved Large-scale industrial application of graphite materials

Electrolyte additives are also an important way to improve the surface of graphite electrodes. In recent years, people have developed many film-forming additives, such as vinylene carbonate. Although electrolyte additives help to passivate the graphite surface, the residual additives in the battery will cause The continuous growth of the SEI film on the graphite surface causes an increase in internal resistance, which is detrimental to the power properties of the battery for long-term use

Previously, we developed graphite materials coated with organic small molecular salts containing unsaturated bonds, and made some progress on stabilizing graphite surfaces, but small molecular salts containing carbon-carbon double bonds (such as sodium maleate, sodium fumarate etc.) are all water-soluble organic small molecules. When using these substances to modify the graphite surface, only PVDF oily binder can be used in electrode preparation, and water-based binder cannot be used, otherwise it will dissolve and fall off

In recent years, the application of PVDF in graphite negative electrodes has been almost completely replaced by water-based binders such as CMC+SBR. From this point of view, the technology of coating modified graphite with small organic molecular salts containing carbon-carbon double bonds is difficult to popularize and apply.

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