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Preparation method of porous Si/SiC/C material and negative electrode material

A technology of silicon powder and powder, which is applied in the field of porous Si/SiC/C material preparation, can solve the problems of complex process, difficult to guarantee the thickness and uniformity of silicon carbide layer, etc., and achieve low cost, huge environmental benefits and Economic benefits, the effect of solving the problem of garbage disposal

Active Publication Date: 2020-07-31
XIAMEN UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the introduction method of SiC layer generally needs to pre-deposit a layer of acetylene black, and then undergo high temperature reaction. Not only the process is complicated, but also the thickness and uniformity of the SiC layer are difficult to be guaranteed.

Method used

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  • Preparation method of porous Si/SiC/C material and negative electrode material
  • Preparation method of porous Si/SiC/C material and negative electrode material
  • Preparation method of porous Si/SiC/C material and negative electrode material

Examples

Experimental program
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Effect test

Embodiment 1

[0052] refer to figure 1 The process flow in prepares porous Si / SiC / C material, specifically as follows:

[0053] S1. Grinding and mixing 1g of silicon powder and 1.8g of magnesium powder, the mixture and 10ml of absolute ethanol were placed in a planetary ball mill for physical ball milling for 24 hours, and dried to obtain a silicon-magnesium alloy powder;

[0054] S2. In a nitrogen atmosphere, put the silicon-magnesium alloy powder in a crucible, place it in an atmosphere sintering furnace, raise the temperature to 550°C at a rate of 3°C / min, keep it for 5 hours, cool it with the furnace, and grind it to obtain the described Magnesium silicide powder;

[0055] S3. Put the magnesium silicide powder in a crucible, place it in an atmosphere sintering furnace, and then 2 , heat up to 650°C at a rate of 10°C / min, keep warm for 1 hour, cool in the furnace, grind, pickle with 1mol / L hydrochloric acid aqueous solution, then pickle with 1wt% hydrofluoric acid aqueous solution and ...

Embodiment 2

[0061] To prepare a lithium ion battery, the porous Si / SiC / C material prepared in Example 1 was used as an active material to make a button half battery (CR-2025). The steps include: mixing 60wt% active material, 20wt% Super P and 20wt% sodium alginate binder to form a uniform slurry; pasting the obtained slurry on a copper foil, vacuum drying in an oven at 100°C for 12h, and then Punch the copper foil into a disc. The half-cells were assembled in a glove box filled with argon, using pure lithium foil as the counter electrode, and a porous membrane (Celgard2400) as the separator.

Embodiment 3

[0063] The button half-cell (CR-2025) prepared in Example 2 was used to conduct an electrochemical test at room temperature within a voltage window of 0.01V-1.5V. see test results Figure 5 , Figure 6 .

[0064] From Figure 5 It can be seen that the first discharge specific capacity of the battery is 903mAh / g at a current density of 400mA / g. After the first 20 cycles, the specific capacity retention rate is greater than or equal to 90%; after 100 cycles, the specific capacity is 594mAh / g. g, with better cycle performance.

[0065] From Figure 6 It can be seen that the battery exhibits a relatively stable rate performance. Under the current density of 3A / g, the specific discharge capacity remained at 617mAh / g.

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Abstract

The invention relates to a preparation method of a porous Si / SiC / C material and a negative electrode material. The preparation method comprises the steps of S1 grinding and mixing waste silicon powderand magnesium powder according to a mass ratio, placing the mixture and absolute ethyl alcohol in a planetary ball mill for physical ball milling, and drying to obtain silicon-magnesium alloy powder;S2 under the protection of inert gas, carrying out heating reaction on the silicon-magnesium alloy powder, carrying out furnace cooling and grinding to acquire magnesium silicide powder; and S3 carrying out heating reaction on the magnesium silicide powder in a CO2 atmosphere, and carrying out furnace cooling, grinding and acid pickling to obtain the porous Si / SiC / C material. The porous Si / SiC / Cmaterial is used as a lithium ion battery negative electrode material. The porous structure on the SiC / C protective layer is utilized to alleviate the volume expansion effect of the internally coatedsilicon, and the SiC / C layer can coat the silicon more completely, thereby effectively enhancing the rate capability and cycle performance of the silicon-carbon negative electrode material.

Description

technical field [0001] The invention relates to the technology in the field of lithium batteries, in particular to a method for preparing a porous Si / SiC / C material and a negative electrode material. Background technique [0002] Lithium-ion battery is the main choice of power supply for portable electronic devices (such as mobile phones, digital cameras and portable notebooks), and it is also more and more widely used in electric vehicles, hybrid electric vehicles, large-scale energy storage, space technology, defense industry, etc. in a field. With the rapid rise of new energy vehicles in recent years, the energy density and power performance of the original lithium-ion batteries have been unable to meet the demand. It is important to develop new battery materials and optimize battery manufacturing technology to improve the battery life and power characteristics of lithium-ion batteries. The key to the high-level development of the electric vehicle industry. It is genera...

Claims

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Application Information

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IPC IPC(8): H01M4/36H01M4/38H01M4/587H01M10/0525
CPCH01M4/364H01M4/386H01M4/587H01M10/0525H01M2004/021H01M2004/027Y02E60/10
Inventor 姜春海周文扬邹智敏
Owner XIAMEN UNIV OF TECH
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