Hard carbon negative electrode slurry and preparation method thereof

Abstract

The invention relates to negative electrode slurry, in particular to hard carbon negative electrode slurry and a preparation method thereof. The raw material of the hard carbon negative electrode slurry comprises 90-97 wt% of a hard carbon material; the raw materials further comprise a composite dispersing agent; the mass ratio of the hard carbon material to the composite dispersant is (90-97): (0.5-2); the composite dispersing agent is selected from two or three of sodium polyepoxysuccinate, sodium carboxymethyl cellulose and polyvinylpyrrolidone. The solid content of the hard carbon negative electrode slurry ranges from 40% to 55.6%, and the slurry has low fineness, good sieving performance and good stability. The hard carbon negative electrode slurry has the advantages of small use amount of the dispersing agent, high solid content, low viscosity, good stability, no coating scratch and the like.

Description

technical field [0001] The present invention relates to a negative electrode slurry, in particular to a hard carbon negative electrode slurry and a preparation method thereof. Background technique [0002] In the 21st century, lithium batteries are used in mobile phones, computers, wearable devices, electric vehicles, two-wheeled bicycles, power tools, street lights and many other fields. With the increasing use of lithium batteries, the consumption of lithium resources shows that the amount of use is larger and the consumption rate is faster, and the increase in lithium production cannot meet the increase in consumption. This is because: first, lithium The resources are limited, mainly in the state of spodumene ore and salt lake lithium. Second, lithium cannot be extracted from salt lake lithium in winter, resulting in a surge in the price of lithium metal and compounds. [0003] In contrast, sodium has a wide range of sources and abundant reserves. The reserves of sodium ...

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Problems solved by technology

[0004] Sodium is the second lightest alkali metal and has similar chemical properties to lithium, but the sodium ion radius is 0.102nm, which is 34.2% larger than the lithium ion radius of 0.076nm, which makes sodium ions not suitable for the traditional small interlayer spacing. Energy storage is carried out in graphite anode materials, and hard carbon materials are considered to be ideal anode materials for sodium-ion batteries in the future due to their larger layer spacing than graphite

[0005] However, hard carbon materials have the following disadvantages: First, hard carbon materials are usually made of phenolic, furfural, pitch and other resins as raw materials, and are obtained by thermal decomposition at about 1000-1500 °C. Dispersion is difficult; second, the particle size of hard carbon materials is too small, which further leads to poor dispersion ability in the slurry; third, hard carbon materials have poor electrical conductivity, and a large amount of conductive agent should be added when using them

For the above three points, when the hard carbon material is used as a negative electrode, in the preparation process of the slurry, it is necessary to increase the stirring intensity and dispersion intensity to avoid the above shortcomings; however, after increasing the stirring intensity and dispersion intensity, it can be used as a dispersion, Thickening and anti-sedimentation CMC molecular chains are easily broken, resulting in hard carbon negative electrode slurry settling and unable to be coated

Although it is also possible to prevent the slurry from settling by increasing the addition ratio of CMC, it reduces the energy density and cycle life of the corresponding sodium-ion battery.

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