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Simple preparation method of graphite and/or silicon negative electrode material with surface coated with carbon

A silicon negative electrode, carbon coating technology, applied in battery electrodes, structural parts, electrical components, etc., can solve the problems of high production cost, cumbersome process, high operation cost, and achieve simple coating method, uniform coating layer, and easy operation. low cost effect

Inactive Publication Date: 2015-04-22
SHANDONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

This method is difficult to ensure the integrity and uniformity of the coating, and the resulting coated modified graphite and silicon have poor performance
However, the solvent method generally uses a large amount of organic solvents, causing great environmental pollution and high production costs.
In the patent CN103072974 A, phenolic resin is used to coat and carbonize graphite in situ, and a layer of uniform amorphous carbon is coated on the graphite surface, but this method is cumbersome and expensive to operate, and is not suitable for industrial production

Method used

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  • Simple preparation method of graphite and/or silicon negative electrode material with surface coated with carbon
  • Simple preparation method of graphite and/or silicon negative electrode material with surface coated with carbon
  • Simple preparation method of graphite and/or silicon negative electrode material with surface coated with carbon

Examples

Experimental program
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Effect test

Embodiment 1

[0021] First, in a 500ml beaker, dissolve 0.03g of dopamine hydrochloride in 450ml of water, then add 1g of tris / tris hydrochloride Tris mixture (solution pH is 7), stir for 5min, Add 3 g of graphite after dissolution. Then put the beaker into a constant temperature water bath, set the reaction temperature at 1°C, stir mechanically for 24 hours, and rotate at a speed of 80r / min. After the reaction time has elapsed, filter, wash with deionized water three times, and then dry overnight in an oven at 50°C to obtain polydopamine-coated spherical graphite. Afterwards, under the protection of nitrogen atmosphere, it was carbonized in a tube furnace at 200° C. for 2 hours to obtain modified spherical graphite uniformly coated with an amorphous carbon layer. Therefore, the carbon coating thickness of graphite coated graphite using dopamine as a carbon precursor can reach 20-30nm, see figure 1 . It can be seen from the figure that the coating is very uniform.

Embodiment 2

[0023] First, in a 500ml beaker, dissolve 50g of dopamine hydrochloride in 450ml of water, then add 20g of Tris (the pH of the solution is 15), stir for 5min, and add 10g of silicon after dissolving. Then put the beaker into a constant temperature water bath, set the reaction temperature to 100°C, stir mechanically for 0.5h, and rotate at a speed of 80r / min. After the reaction time has elapsed, filter, wash with deionized water three times, and then dry overnight in an oven at 70°C to obtain polydopamine-coated spherical graphite. Afterwards, under the protection of argon atmosphere, it was carbonized in a tube furnace at 1500° C. for 2 hours to obtain a modified spherical graphite uniformly coated with an amorphous carbon layer. Therefore, the carbon coating layer thickness of silicon coated with dopamine as carbon precursor can reach 10-20nm, see figure 2 . The graphite, as a lithium battery anode material, has an efficiency as high as 95% in the first week, and a capacit...

Embodiment 3

[0025] First, in a 500ml beaker, dissolve 20g of dopamine hydrochloride in 400ml of water, then add 1.35g of Tris (the pH of the solution is 8.5), stir for 5min, and add 1g of graphite after dissolving. Then put the beaker into a constant temperature water bath, set the reaction temperature to 50°C, stir mechanically for 48 hours, and rotate at a speed of 80r / min. After the reaction time has elapsed, filter, wash with deionized water three times, and then dry overnight in an oven at 50°C to obtain polydopamine-coated spherical graphite. Afterwards, under the protection of nitrogen atmosphere, it was carbonized in a tube furnace at 1000° C. for 4 hours to obtain a modified spherical graphite uniformly coated with an amorphous carbon layer. According to the comparison of the SEM pictures before and after spherical graphite coating, the graphite surface is obviously covered by the coating layer. For details, see image 3 and Figure 4 .

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Abstract

The invention relates to a simple preparation method of a graphite and / or silicon negative electrode material with the surface coated with carbon. The method comprises the steps that dopamine hydrochloride, water and alkaline matter are used for preparing a dopamine buffer solution, natural spherical graphite and / or silicon and the dopamine buffer solution are mixed, stirred for 0.1-96 hours at the temperature ranging from 10 DEG C to 100 DEG C, filtered and dried to obtain graphite and / or silicon coated with a dopamine precursor, the graphite and / or the silicon coated with the dopamine precursor is carbonized for 0.1-96 hours at the temperature ranging from 200 DEG C to 3500 DEG C under the protection of inert gases, and finally modified graphite and / or modified silicon evenly coated with amorphous carbon is obtained. The coating method is easy, convenient and low in operating cost and has great industrial prospect. Compared with an existing coating method, the method has the advantages that a coating layer is uniform, and the coating rate is high; moreover, the thickness of the coating layer can be accurately controlled by adjusting the concentration of the dopamine solution and the stirring time so that the optimum thickness of the graphite coated with the amorphous carbon can be obtained after optimization.

Description

technical field [0001] The invention belongs to the field of lithium ion batteries, and mainly relates to the coating modification of spherical graphite, which is a cathode material of lithium ion batteries. Background technique [0002] With the increasingly serious energy crisis and environmental pollution, the development and utilization of clean energy, such as solar energy and wind energy, has received more and more attention from various countries. As an emerging electrical energy storage device, lithium-ion batteries have the advantages of high energy density, stable discharge voltage, small self-discharge, no memory effect, environmental friendliness, and long cycle life. Naturally, they will be used as the main energy conversion and storage devices in the future. In addition, lithium-ion batteries are also one of the ideal choices for electric vehicles. Graphite and silicon are the main anode materials for lithium-ion batteries. Due to their stable cycle performanc...

Claims

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Application Information

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IPC IPC(8): H01M4/36H01M4/38H01M4/587H01M4/62
CPCH01M4/36H01M4/38H01M4/587H01M4/625Y02E60/10
Inventor 冯金奎张震
Owner SHANDONG UNIV
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