CN110867572A

CN110867572A - Preparation method of double-layer carbon-coated silicon composite material

Info

Publication number: CN110867572A
Application number: CN201911161853.2A
Authority: CN
Inventors: 解勤兴; 李铱蔓; 赵晋辉
Original assignee: Tianjin Polytechnic University
Current assignee: Tianjin Polytechnic University
Priority date: 2019-11-25
Filing date: 2019-11-25
Publication date: 2020-03-06

Abstract

The invention discloses a preparation method of a double-layer carbon-coated silicon composite material, which comprises the following specific steps: dispersing 5-50 parts by mass of micro-nano silicon powder into a proper amount of solvent, sequentially adding 50-200 parts by mass of inorganic salt and 5-50 parts by mass of organic ligand, and uniformly stirring and mixing. And ball-milling the obtained mixture for 0.2-5 hours in an inert atmosphere. And washing, filtering and drying the obtained material, then uniformly mixing the material and the organic polymer in a solvent according to the mass ratio of 1/0.2-5, removing the solvent, heating to 400-700 ℃ at the speed of 2-5 ℃ per minute in an inert atmosphere, preserving the heat for 1-3 hours, cooling to room temperature, and purifying to obtain the secondary carbon-coated silicon composite material. The silicon composite material prepared by the method can be used as a negative electrode material of a lithium ion battery and a lithium sulfur battery.

Description

Preparation method of double-layer carbon-coated silicon composite material

Technical Field

The invention relates to the technical field of inorganic nonmetallic materials, in particular to a preparation method of a silicon-carbon composite negative electrode material for energy storage of a lithium battery.

Background

In recent years, low energy density and low safety lithium ion batteries using graphite as a negative electrode are being phased out due to the increasing wide demand for clean energy. The development of new energy automobiles needs novel lithium ion batteries with high energy density, high power density and high safety to meet the requirement of long endurance. Silicon as a lithium ion battery negative electrode material has a theoretical capacity as high as 4200mAh/g, so that the silicon has attracted much attention in the research and development aspects of long-endurance power batteries. However, the volume expansion effect of the silicon negative electrode in the charging and discharging process is huge (up to 300%), and the silicon negative electrode continuously shrinks and expands to generate large internal stress in the material, so that the pulverization and the falling are caused to inactivate, and the conductivity and the cycling stability of the electrode are reduced. At present, the cycling stability of the silicon cathode is improved by adopting a method of compounding nano porous silicon and a Carbon material (Carbon, 2016, 98: 582-.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention adopts the following technical scheme to prepare the double-layer carbon-coated micro-nano silicon composite material.

The technical scheme adopted by the invention is as follows: dispersing 5-50 parts by mass of micro-nano silicon powder into a proper amount of solvent, sequentially adding 50-200 parts by mass of inorganic salt and 5-50 parts by mass of organic ligand, and uniformly stirring and mixing. And ball-milling the obtained mixture for 0.2-5 hours in an inert atmosphere. And washing, filtering and drying the obtained material, then uniformly mixing the material and the organic polymer in a solvent according to the mass ratio of 1/0.2-5, removing the solvent, heating to 400-700 ℃ at the speed of 2-5 ℃ per minute in an inert atmosphere, preserving the heat for 1-3 hours, cooling to room temperature, and purifying to obtain the secondary carbon-coated silicon composite material.

The solvent used in the above steps is one or more of water, tetrahydrofuran, carbon disulfide, dimethylformamide, alcohols, esters, ethers and ketones.

The inorganic salt used in the steps is one or more of transition metal chloride, sulfate, nitrate and acetate.

The organic ligand used in the above step has one or more of nitrogen-containing and oxygen-containing functional groups.

The organic polymer used in the above steps is one or more of polyolefin, polyacrylonitrile, polysaccharide, asphalt, polymethyl methacrylate, polyvinyl alcohol, cellulose and polyethylene glycol.

Drawings

FIG. 1 is a scanning electron micrograph of the product of example 1.

FIG. 2 is a scanning electron micrograph of the product of example 2.

FIG. 3 is a scanning electron micrograph of the product of example 3.

FIG. 4 is a graph of the charge and discharge cycle performance of the product of example 2.

FIG. 5 is a graph of the charge and discharge cycle performance of the product of example 3.

Detailed Description

Example 1:

3.74 g of micro-nano silicon powder is dispersed into a proper amount of distilled water, 100 g of aluminum nitrate nonahydrate and 8 g of 1, 3, 5-trimesic acid are sequentially added, stirred and mixed uniformly. The resulting mixture was ball milled for 1 hour under an inert atmosphere. And washing, filtering and drying the obtained material, heating to 700 ℃ at a speed of 5 ℃ per minute in an inert atmosphere, and preserving heat for 1 hour. Cooling to room temperature, and purifying to obtain the primary carbon-coated silicon composite material, wherein the morphology of the product is shown in figure 1.

Example 2:

3.74 g of micro-nano silicon powder is dispersed into a proper amount of distilled water, 100 g of aluminum nitrate nonahydrate and 8 g of 1, 3, 5-trimesic acid are sequentially added, stirred and mixed uniformly. The resulting mixture was ball milled for 4 hours under an inert atmosphere. And washing, filtering and drying the obtained material, heating to 700 ℃ at a speed of 5 ℃ per minute in an inert atmosphere, and preserving heat for 1 hour. Cooling to room temperature, and purifying to obtain the primary carbon-coated silicon composite material, wherein the morphology of the product is shown in figure 2.

Example 3:

3.74 g of micro-nano silicon powder is dispersed into a proper amount of distilled water, 100 g of aluminum nitrate nonahydrate and 8 g of 1, 3, 5-trimesic acid are sequentially added, stirred and mixed uniformly. The resulting mixture was ball milled for 4 hours under an inert atmosphere. Washing, filtering and drying the obtained material, then uniformly mixing the material and polyethylene glycol powder in water according to the mass ratio of 1/5, heating to 700 ℃ at the speed of 5 ℃ per minute in an inert atmosphere after drying, preserving heat for 1 hour, cooling to room temperature, and purifying to obtain the secondary carbon-coated silicon composite material, wherein the morphology of the product is shown in figure 3.

Example 4: electrochemical performance testing of materials

Electrochemical testing of materials at room temperature using button cell systemThe electrolyte is 1.0M LiPF₆EC + DMC (1: 1 by volume with 5.0% FEC). A blue CT2001A type battery test system is adopted to carry out charge and discharge tests, and the voltage range is 0.005-3V. The results are shown in FIGS. 4 and 5.

Claims

1. A preparation method of a double-layer carbon-coated silicon composite material comprises the following specific steps: dispersing 5-50 parts by mass of micro-nano silicon powder into a proper amount of solvent, sequentially adding 50-200 parts by mass of inorganic salt and 5-50 parts by mass of organic ligand, and uniformly stirring and mixing. And ball-milling the obtained mixture for 0.2-5 hours in an inert atmosphere. And washing, filtering and drying the obtained material, then uniformly mixing the material and the organic polymer in a solvent according to the mass ratio of 1/0.2-5, removing the solvent, heating to 400-700 ℃ at the speed of 2-5 ℃ per minute in an inert atmosphere, preserving the heat for 1-3 hours, cooling to room temperature, and purifying to obtain the secondary carbon-coated silicon composite material.

2. The method according to claim 1, wherein the solvent is one or more of water, tetrahydrofuran, carbon disulfide, dimethylformamide, alcohols, esters, ethers, and ketones.

3. The method according to claim 1, wherein the inorganic salt is one or more of transition metal chloride, sulfate, nitrate and acetate.

4. The method of claim 1, wherein the organic ligand comprises one or more of nitrogen-containing and oxygen-containing functional groups.

5. The method for preparing the double-layer carbon-coated silicon composite material according to claim 1, wherein the organic polymer is one or more of polyolefin, polyacrylonitrile, polysaccharide, asphalt, polymethyl methacrylate, polyvinyl alcohol, cellulose and polyethylene glycol.

6. A two-layer carbon-coated silicon composite material prepared by the method of any one of claims 1 to 5.

7. A double-layer carbon-coated silicon composite material having a double-layer carbon structure around silicon particles: a metal organic framework derived porous carbon core and an organic polymer derived carbon shell.

8. The double-layer carbon-coated silicon composite material of claims 6 and 7 can be used as a lithium ion battery negative electrode material.

9. The double-layer carbon-coated silicon composite material of claims 6 and 7 can be used as a negative electrode material of a lithium-sulfur battery.