阅读说明：本技术 基于共价有机框架材料的氟化碳正极材料的制备方法 (Preparation method of carbon fluoride anode material based on covalent organic framework material ) 是由 候小鹏 李秀涛 曾浩 杜邵文 李娜 朱怡雯 傅小珂 于 2020-12-18 设计创作，主要内容包括：本发明提供了一种基于共价有机框架材料的氟化碳正极材料的制备方法。其以多孔材料——共价有机框架材料为原料,经过高温碳化可以获得含有杂原子的多孔碳材料,采用由氟气、氟化氢和氩气组成的混合气体作为氟化气体,在加热条件下对多孔碳材料进行氟化可获得含有杂原子的多孔氟化碳正极材料；由于多孔碳材料中含有大量的杂原子,而杂原子通过电子诱导作用可以使C-F键的生成更容易,从而可降低氟化反应温度,并且生成的C-F键多为半离子键,进而可提高氟化碳正极材料的放电电压平台；另外,本发明方法以氟气、氟化氢和氩气组成的混合气体作为氟化气体,由于氟化氢的强极化作用,也可以一定程度降低氟化反应温度。(The invention provides a preparation method of a carbon fluoride anode material based on a covalent organic framework material. The porous carbon material containing the heteroatom is obtained by taking a porous material-covalent organic framework material as a raw material and carbonizing at high temperature, and the porous carbon material containing the heteroatom is obtained by fluorinating the porous carbon material under the heating condition by taking a mixed gas consisting of fluorine gas, hydrogen fluoride and argon as a fluorinated gas; because the porous carbon material contains a large amount of heteroatoms, and the heteroatoms can enable the generation of C-F bonds to be easier through the electron induction effect, the fluorination reaction temperature can be reduced, and the generated C-F bonds are mostly semi-ionic bonds, so that the discharge voltage platform of the carbon fluoride anode material can be improved; in addition, the method of the present invention uses a mixed gas of fluorine gas, hydrogen fluoride and argon gas as the fluorine gas, and can reduce the fluorination reaction temperature to some extent due to the strong polarization effect of hydrogen fluoride.)

1. A preparation method of a carbon fluoride anode material based on a covalent organic framework material is characterized by comprising the following steps: the preparation method comprises the following steps which are carried out in sequence:

(1) carrying out high-temperature carbonization on the covalent organic framework material in a nitrogen atmosphere, and then cooling to room temperature to obtain a carbon source of a carbon fluoride precursor;

(2) and (2) placing the carbon fluoride precursor carbon source in a reaction kettle for drying, introducing a mixed gas consisting of fluorine gas, hydrogen fluoride and argon as a fluorinated gas for carrying out a fluorination reaction, and carrying out vacuum drying after the fluorination reaction is finished to obtain the carbon fluoride cathode material.

2. The method of preparing a fluorinated carbon cathode material based on a covalent organic framework material according to claim 1, characterized in that: in the step (1), the covalent organic framework material is selected from at least one of boron-oxygen hexacyclic covalent organic framework materials COF-1, COF-102, COF-103, borate covalent organic framework materials COF-5, COF-105, COF-108, triazine covalent organic framework materials CTF-1, CTF-2, imine covalent organic framework materials COF-LZU-1 and ether covalent organic framework materials COF-316, COF-318, JUC-505 and JUC-506.

3. The method of preparing a fluorinated carbon cathode material based on a covalent organic framework material according to claim 1, characterized in that: in the step (1), the temperature rise rate of the high-temperature carbonization is 1-5 ℃/min, the carbonization temperature is 500-1200 ℃, and the carbonization time is 1-6 hours.

4. The method of preparing a fluorinated carbon cathode material based on a covalent organic framework material according to claim 1, characterized in that: in the step (2), the mixed gas consists of 10-50% by volume of fluorine gas, 10-30% by volume of hydrogen fluoride and 20-80% by volume of argon gas; the fluorination reaction temperature is 100-350 ℃, and the fluorination reaction time is 2-6 hours.

Technical Field

The invention belongs to the technical field of carbon material synthesis, and particularly relates to a preparation method of a carbon fluoride anode material based on a covalent organic framework material.

Background

Lithium/fluorocarbon batteries have the highest theoretical energy density among the existing primary batteries, and thus have been widely used in the fields of aerospace, military industry, medical treatment, and the like. At present, carbon fluoride materials have been reported mainly as: the battery using the fluorinated graphene and the fluorinated carbon nanotube as the anode material has more researches, and the material has larger specific capacity, but has the defect of lower discharge voltage platform, thereby influencing the specific energy of the whole fluorinated carbon battery. Meanwhile, the carbon source of the carbon fluoride material is graphene and carbon nano tubes, so that the cost of raw materials is high; and the fluorination conditions are harsh (fluorination at a temperature of more than 500 ℃ in a fluorine gas atmosphere), so that the method is not favorable for industrial production.

Metal organic frame materials have been used for preparing carbon fluoride positive electrode materials (for example, patent patents: CN201910398470.0, CN201910415544.7, CN201910398454.1 and CN201910415216.7), although the performance of the carbon fluoride battery can be improved to a certain extent, the materials contain a large amount of metal elements, so that the production cost and the post-treatment cost are high, the materials are difficult to prepare carbon materials containing non-metal heteroatoms (such as boron, nitrogen and the like) in situ, and the carbon materials containing the non-metal heteroatoms have been proved to have the advantages of low fluorination temperature and good performance of the carbon fluoride battery.

Covalent organic framework materials are a class of organic porous polymers with periodicity and crystallinity. The material is connected by light elements (C, H, O, N, B and the like) through covalent bonds, has low density, high thermal stability and inherent porosity, has wide application potential in the research fields of gas adsorption, heterogeneous catalysis, energy storage and the like, and has attracted strong research interest in the scientific community. Therefore, the material is expected to become an important raw material source of the carbon fluoride material.

Disclosure of Invention

In order to solve the above problems, it is an object of the present invention to provide a method for preparing a fluorinated carbon cathode material based on a covalent organic framework material.

In order to achieve the above object, the present invention provides a method for preparing a fluorinated carbon cathode material based on a covalent organic framework material, comprising the following steps performed in sequence:

(1) carrying out high-temperature carbonization on the covalent organic framework material in a nitrogen atmosphere, and then cooling to room temperature to obtain a carbon source of a carbon fluoride precursor;

(2) and (2) placing the carbon fluoride precursor carbon source in a reaction kettle for drying, introducing a mixed gas consisting of fluorine gas, hydrogen fluoride and argon as a fluorinated gas for carrying out a fluorination reaction, and carrying out vacuum drying after the fluorination reaction is finished to obtain the carbon fluoride cathode material.

In the step (1), the covalent organic framework material is selected from at least one of boron-oxygen hexacyclic covalent organic framework materials COF-1, COF-102, COF-103, borate covalent organic framework materials COF-5, COF-105, COF-108, triazine covalent organic framework materials CTF-1, CTF-2, imine covalent organic framework materials COF-LZU-1 and ether covalent organic framework materials COF-316, COF-318, JUC-505 and JUC-506.

In the step (1), the temperature rise rate of the high-temperature carbonization is 1-5 ℃/min, the carbonization temperature is 500-1200 ℃, and the carbonization time is 1-6 hours.

In the step (2), the mixed gas consists of 10-50% by volume of fluorine gas, 10-30% by volume of hydrogen fluoride and 20-80% by volume of argon gas; the fluorination reaction temperature is 100-350 ℃, and the fluorination reaction time is 2-6 hours.

The main technical principle of the preparation method of the carbon fluoride anode material based on the covalent organic framework material provided by the invention is as follows: taking a porous material-covalent organic framework material as a raw material, carbonizing at high temperature to obtain a porous carbon material containing heteroatoms, and fluorinating the porous carbon material under a heating condition by using a mixed gas consisting of fluorine gas, hydrogen fluoride and argon as a fluorinated gas to obtain a porous carbon fluoride anode material containing heteroatoms; because the porous carbon material contains a large amount of heteroatoms, and the heteroatoms can enable the generation of C-F bonds to be easier through the electron induction effect, the fluorination reaction temperature can be reduced, and the generated C-F bonds are mostly semi-ionic bonds, so that the discharge voltage platform of the carbon fluoride anode material can be improved; in addition, the method of the present invention uses a mixed gas of fluorine gas, hydrogen fluoride and argon gas as the fluorine gas, and can reduce the fluorination reaction temperature to some extent due to the strong polarization effect of hydrogen fluoride.

Compared with the prior art, the preparation method of the carbon fluoride anode material based on the covalent organic framework material has the following effects: (1) the raw material is of a porous structure, does not contain metal elements, is rich in non-metal heteroatoms, can effectively reduce the fluorination reaction temperature, and improves the discharge voltage and specific capacity of the carbon fluoride anode material; (2) the invention adopts the mixed gas composed of fluorine gas, hydrogen fluoride and argon gas as the fluorinated gas, which can further improve the efficiency of the fluorination reaction and reduce the temperature of the fluorination reaction; (3) the carbon fluoride anode material prepared by the invention has rich inner holes, high specific surface area and good battery performance, can be applied to the fields of lithium ion batteries and the like, and has good application prospect.

Drawings

FIG. 1 is a schematic representation of the molecular structure of a representative covalent organic framework material.

Detailed Description

The present invention is further described in the following description of the specific embodiments, which is not intended to limit the invention, but various modifications and improvements can be made by those skilled in the art according to the basic idea of the invention, within the scope of the invention, as long as they do not depart from the basic idea of the invention.

Example 1

The preparation method of the carbon fluoride cathode material based on the covalent organic framework material provided by the embodiment comprises the following steps which are sequentially carried out:

(1) carrying out high-temperature carbonization on 1.0g of boron-oxygen hexacyclic covalent organic framework material COF-1 in a nitrogen atmosphere at the temperature rise speed of 5 ℃/min, the carbonization temperature of 800 ℃ for 4 hours, and then cooling to room temperature to obtain a carbon fluoride precursor carbon source;

(2) and (2) placing the carbon fluoride precursor carbon source in a reaction kettle, drying at the temperature of 150 ℃, introducing a mixed gas consisting of 35 volume percent of fluorine gas, 15 volume percent of hydrogen fluoride and 50 volume percent of argon as a fluorinated gas, heating to 250 ℃, carrying out fluorination reaction for 4 hours, continuing introducing argon after the fluorination reaction is finished to remove the unreacted fluorinated gas, and then carrying out vacuum drying to obtain the carbon fluoride cathode material.

FIG. 1 is a schematic representation of the molecular structure of a representative covalent organic framework material. This example provides a fluorocarbon positive electrode material having a specific surface area of 861m as measured by the BET method²(ii)/g; the fluorine-carbon ratio of the carbon fluoride anode material is 0.82 measured by an element analysis method; according to the test of an electrochemical test method, the discharge median voltage of the carbon fluoride anode material is 3.08V under the condition of 0.05C multiplying power, and the discharge specific capacity is 861 mAh/g.

Example 2

The preparation method of the carbon fluoride cathode material based on the covalent organic framework material provided by the embodiment comprises the following steps which are sequentially carried out:

(1) and (2) carrying out high-temperature carbonization on 1.0g of borate covalent organic framework material COF-5 in a nitrogen atmosphere at the temperature rise speed of 5 ℃/min, the carbonization temperature of 900 ℃ for 4 hours, and then cooling to room temperature to obtain the carbon fluoride precursor carbon source.

(2) And (2) placing the carbon fluoride precursor carbon source in a reaction kettle, drying at the temperature of 150 ℃, introducing a mixed gas consisting of 45 volume percent of fluorine gas, 15 volume percent of hydrogen fluoride and 40 volume percent of argon as a fluorinated gas, heating to 200 ℃, carrying out fluorination reaction for 4 hours, after the fluorination reaction is finished, continuously introducing argon to remove the unreacted fluorinated gas, and then carrying out vacuum drying to obtain the carbon fluoride cathode material.

This example provides a fluorocarbon positive electrode material having a specific surface area of 903m as measured by the BET method²(ii)/g; the fluorine-carbon ratio of the carbon fluoride anode material is 0.89 measured by an element analysis method; according to the electrochemical test method, the discharge median voltage of the carbon fluoride anode material is 3.21V under the condition of 0.05C multiplying power, and the discharge specific capacity is 877 mAh/g.

Example 3

The preparation method of the carbon fluoride cathode material based on the covalent organic framework material provided by the embodiment comprises the following steps which are sequentially carried out:

(1) 1.0g of triazine covalent organic framework material CTF-1 is carbonized at high temperature in nitrogen atmosphere, the heating rate is 5 ℃/min, the carbonization temperature is 1000 ℃, the carbonization time is 3 hours, and then the carbon fluoride precursor carbon source is obtained after cooling to room temperature.

(2) And (2) placing the carbon fluoride precursor carbon source in a reaction kettle, drying at the temperature of 150 ℃, introducing a mixed gas consisting of 45 volume percent of fluorine gas, 15 volume percent of hydrogen fluoride and 40 volume percent of argon as a fluorinated gas, heating to 200 ℃, carrying out fluorination reaction for 4 hours, after the fluorination reaction is finished, continuously introducing argon to remove the unreacted fluorinated gas, and then carrying out vacuum drying to obtain the carbon fluoride cathode material.

The specific surface area of the carbon fluoride anode material provided by the embodiment is 767m measured by a BET method²(ii)/g; the fluorine-carbon ratio of the carbon fluoride anode material is 0.93 measured by an element analysis method; the electrochemical test method proves that the discharge median voltage of the carbon fluoride anode material is 3.01V under the condition of 0.05C multiplying power, and the discharge specific capacity is 907 mAh/g.

Example 4

The preparation method of the carbon fluoride cathode material based on the covalent organic framework material provided by the embodiment comprises the following steps which are sequentially carried out:

(1) 1.0g of imine covalent organic framework material COF-LZU-1 is carbonized at high temperature in nitrogen atmosphere, the heating rate is 5 ℃/min, the carbonization temperature is 900 ℃, the carbonization time is 4 hours, and then the carbon fluoride precursor carbon source is obtained after cooling to room temperature.

(2) And (2) placing the carbon fluoride precursor carbon source in a reaction kettle, drying at the temperature of 150 ℃, introducing a mixed gas consisting of 45 volume percent of fluorine gas, 15 volume percent of hydrogen fluoride and 40 volume percent of argon as a fluorinated gas, heating to 220 ℃, carrying out fluorination reaction for 4 hours, after the fluorination reaction is finished, continuously introducing argon to remove the unreacted fluorinated gas, and then carrying out vacuum drying to obtain the carbon fluoride cathode material.

This example provides a fluorocarbon positive electrode material having a specific surface area of 873m as measured by the BET method²(ii)/g; the fluorine-carbon ratio of the carbon fluoride anode material is 0.90 measured by an element analysis method; the electrochemical test method proves that the discharge median voltage of the carbon fluoride anode material is 3.16V under the condition of 0.05C multiplying power, and the discharge specific capacity is 893 mAh/g.

Example 5

The preparation method of the carbon fluoride cathode material based on the covalent organic framework material provided by the embodiment comprises the following steps which are sequentially carried out:

(1) and (2) carbonizing 1.0g of ether covalent organic framework material COF-316 at high temperature in a nitrogen atmosphere at the temperature rising speed of 5 ℃/min, the carbonization temperature of 700 ℃ for 4 hours, and then cooling to room temperature to obtain the carbon fluoride precursor carbon source.

(2) And (2) placing the carbon fluoride precursor carbon source in a reaction kettle, drying at the temperature of 150 ℃, introducing a mixed gas consisting of 40 volume percent of fluorine gas, 15 volume percent of hydrogen fluoride and 45 volume percent of argon as a fluorinated gas, heating to 190 ℃, carrying out fluorination reaction for 6 hours, continuing introducing argon after the fluorination reaction is finished to remove the unreacted fluorinated gas, and then carrying out vacuum drying to obtain the carbon fluoride cathode material.

This example provides a fluorocarbon positive electrode material having a specific surface area of 886m as measured by the BET method²(ii)/g; the fluorine-carbon ratio of the carbon fluoride anode material is 0.93 measured by an element analysis method; warp beamAccording to the measurement of an electrochemical test method, the discharge median voltage of the carbon fluoride anode material is 3.12V under the condition of 0.05C multiplying power, and the discharge specific capacity is 889 mAh/g.

The specific surface area of the coating film was 886m by the BET method²And the fluorine-carbon ratio is 0.93 measured by an element analysis method, the discharge median voltage is 3.12V under the condition of 0.05C multiplying power measured by an electrochemical test method, and the discharge specific capacity is 889 mAh/g.