Preparation method and application of sulfur-based polymer cathode material

Abstract

The application discloses a kind of sulfur-based polymer positive electrode material preparation method and application, it is related to chemical power supply technical field.The application generates a brand-new sulfur-based polymer positive electrode material with highly cross-linked, good conductivity and rich active site network structure by the reaction of two kinds of high nitrogen content polymer and sulfur, by planetary ball mill mixing poly (1,2,4,5-tetraamino benzene) and polyacrylonitrile, and adding elemental sulfur and anhydrous ethanol for ball milling treatment, precursor is prepared after drying.Heating reaction is carried out to precursor in sealed quartz tube, then grinding is carried out, and finally annealing treatment in open quartz tube can obtain sulfur-based polymer positive electrode material.The method of the application is simple in operation, and material performance is stable.

Description

Technical Field

[0001] This invention relates to the field of chemical power source technology, specifically to a method for preparing a sulfur-based polymer cathode material and its application. Background Technology

[0002] Lithium-sulfur batteries have attracted much attention in the rechargeable battery field due to their advantages such as high theoretical capacity, abundant resources, environmental friendliness, and low cost. However, the "solid-liquid-solid" reaction process during discharge of traditional lithium-sulfur batteries results in a dual discharge plateau in voltage. Especially at the 2.4V high voltage plateau, sulfur is converted into higher-order polysulfides and migrates to the negative electrode, causing loss of active material and affecting the performance of the negative electrode.

[0003] To address these issues, researchers are exploring the use of novel materials to replace traditional cathodes, aiming to shift to a "solid-solid" reaction mechanism, eliminate the generation of soluble lithium polysulfides and the resulting shuttle effect, and achieve a single discharge platform. Since the 1980s, sulfur-containing polymers have attracted considerable attention as potential cathode active materials. Among them, organic sulfides, due to their unique cross-linked network structure and diverse functional groups, offer excellent specific capacity and energy density, and can effectively mitigate volume changes during charge and discharge, preventing lithium polysulfide shuttle.

[0004] This study developed an innovative sulfur-based polymer cathode material. This material links poly(1,2,4,5-tetraaminobenzene) to polyacrylonitrile via sulfur chains, forming a highly cross-linked network structure with good conductivity and abundant active sites. Figure 1 As shown in the figure. This structure enhances the overall conductivity and sulfur content of the material, thereby significantly improving its capacity and effectively solving the problem of low discharge specific capacity of traditional sulfur-based polymer cathode materials. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing sulfur-based polymer cathode materials and their applications, so as to solve the problems mentioned in the background art.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for preparing a sulfur-based polymer cathode material, the specific steps of which are as follows:

[0007] S1, poly(1,2,4,5-tetraaminobenzene) and polyacrylonitrile are thoroughly mixed to obtain a polymer mixture. Elemental sulfur and alcohol are added as dispersants, and the mixture is ball-milled and dried to obtain a precursor of sulfur-based polymer cathode material.

[0008] S2, the precursor obtained in S1 is placed in a sealed quartz tube and placed in a tube furnace for heating and reaction. After the reaction is completed, the intermediate product in the quartz tube is ground to ensure its uniformity.

[0009] S3. The intermediate product ground in S2 is placed in an open quartz tube and then placed in a tube furnace for annealing. After annealing, it is taken out and ground evenly to obtain sulfur-based polymer cathode material.

[0010] Furthermore, in step S1, the molecular weight of the polyacrylonitrile is 5-50W, and the ratio of poly(1,2,4,5-tetraaminobenzene) to polyacrylonitrile is 1:2 to 2:1.

[0011] The planetary ball mill rotates at 200-1000 rpm / min and the milling time is 0.5-6 hours.

[0012] The ratio of polymer mixture to elemental sulfur is 1:2 to 1:10, and the alcohol used has a purity of 99-100%.

[0013] The drying temperature is 40-100℃, and the drying time is 0.5-48 hours.

[0014] Furthermore, in step S2, the atmosphere inside the sealed quartz tube is argon or nitrogen, the heating temperature is 300-500℃, and the heating time is 2-20 hours.

[0015] Furthermore, the annealing temperature in step S3 is 100-300℃, and the annealing time is 2-60 hours.

[0016] The present invention also provides a sulfur-based polymer cathode material, prepared by the method described above.

[0017] Furthermore, it is applied in lithium metal batteries, lithium-ion batteries, sodium-ion batteries, sodium metal batteries, potassium-ion batteries, or potassium metal batteries.

[0018] The beneficial effects of this invention are as follows: Through innovative preparation technology, poly(1,2,4,5-tetraaminobenzene), polyacrylonitrile, and sulfur are fused to develop a novel sulfur-based polymer cathode material. Compared to traditional sulfur-based polymer cathode materials such as sulfurized polyacrylonitrile, sulfurized polyacrylic acid, and sulfurized polyethyleneimine, which all have a sulfur content below 50%, this invention has a sulfur content of over 60% and possesses conductivity, thereby improving the battery's energy density and charge / discharge efficiency. The preparation method provided by this solution is stable and scalable, paving the way for large-scale industrial production.

[0019] The method for preparing sulfur-based polymer cathode materials provided by this invention is simple and easy to implement, using readily available raw materials and convenient operation. By adjusting the preparation parameters, mass production of the material can be easily achieved, thereby significantly improving production efficiency. The low cost of raw materials helps battery manufacturers reduce production costs, thus enhancing the market competitiveness of their products. Attached Figure Description

[0020] Figure 1This is the chemical structure diagram of a sulfur-based polymer cathode material.

[0021] Figure 2 This is a scanning electron microscope image of a sulfur-based polymer cathode material.

[0022] Figure 3 This is an electrochemical cycle diagram of a sulfur-based polymer cathode material. Detailed Implementation

[0023] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described in order to avoid obscuring the invention. Example

[0024] 8g of poly(1,2,4,5-tetraaminobenzene) and 2g of polyacrylonitrile with a molecular weight of 15W were mixed in a planetary ball mill at 500 rpm for 30 minutes to form a homogeneous polymer mixture. Then, 50g of elemental sulfur and 50ml of anhydrous ethanol were added as a dispersant, and the mixture was ball-milled for another 2 hours. The mixture was then dried at 60℃ for 12 hours to obtain the precursor. The precursor was placed in a sealed quartz tube filled with argon gas and placed in a tube furnace. It was heated at 400℃ for 8 hours, then removed and ground until homogeneous. The ground intermediate was placed in an open quartz tube and placed in a tube furnace for annealing at 200℃ for 10 hours. It was then removed and ground until homogeneous, finally yielding a sulfur-based polymer cathode material with a sulfur content of 62%. The microstructure is as follows: Figure 2 As shown. Subsequently, the aforementioned sulfur-based polymer cathode material and lithium metal were assembled into a coin cell to examine its performance, as shown. Figure 3 The battery has a reversible discharge specific capacity of 1580mAh / g during charge-discharge cycles, and a discharge specific capacity of 1356mAh / g after 250 cycles, with a capacity retention rate of 85.82% and a coulombic efficiency of 100%. Example

[0025] 2g of poly(1,2,4,5-tetraaminobenzene) and 8g of polyacrylonitrile with a molecular weight of 50W were mixed in a planetary ball mill at 800 rpm for 45 minutes. Then, 50g of elemental sulfur and 50ml of precipitate were added, and the mixture was ball-milled for another 4 hours. The mixture was then dried at 40°C for 24 hours to obtain a precursor. The precursor was placed in a sealed quartz tube filled with nitrogen and heated in a tube furnace at 350°C for 12 hours, then removed and ground. The ground product was placed in an open quartz tube and annealed again in a tube furnace at 150°C for 40 hours to finally obtain a sulfur-based polymer cathode material with a sulfur content of 65%. The sulfur-based polymer cathode material and lithium metal were then assembled into coin cells to investigate performance. During charge-discharge cycling, the reversible discharge specific capacity was 1500 mAh / g, and after 250 cycles, the discharge specific capacity was 1321 mAh / g, with a capacity retention of 88% and a coulombic efficiency of 100%. Example

[0026] 5g of poly(1,2,4,5-tetraaminobenzene) and 5g of polyacrylonitrile with a molecular weight of 20W were mixed in a planetary ball mill at 200 rpm / min for 1 hour. Then, 100g of elemental sulfur and 150ml of anhydrous ethanol were added, and the mixture was ball-milled for 30 minutes. Afterward, the mixture was dried at 80℃ for half an hour to obtain the precursor. The precursor was placed in a sealed quartz tube under argon atmosphere and heated at 350℃ for 2 hours in a tube furnace, then removed and ground. The ground product was placed in an open quartz tube and annealed again at 300℃ for 2 hours to finally obtain a sulfur-based polymer cathode material with a sulfur content of 70%. The sulfur-based polymer cathode material and lithium metal were then assembled into coin cells to investigate performance. During charge-discharge cycling, the reversible discharge specific capacity was 1530 mAh / g, and after 250 cycles, the discharge specific capacity was 1341 mAh / g, with a capacity retention of 87.6% and a coulombic efficiency of 100%.

[0027] As described above, although the invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the invention itself. Various changes in form and detail may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A method for preparing a sulfur-based polymer cathode material, characterized in that, The specific steps are as follows: S1, poly(1,2,4,5-tetraaminobenzene) and polyacrylonitrile are thoroughly mixed to obtain a polymer mixture. Elemental sulfur and alcohol are added as dispersants, and the mixture is ball-milled and dried to obtain a precursor of sulfur-based polymer cathode material. S2, the precursor obtained in S1 is placed in a sealed quartz tube and placed in a tube furnace for heating and reaction. After the reaction is completed, the intermediate product in the quartz tube is ground to ensure its uniformity. S3. The intermediate product ground in S2 is placed in an open quartz tube and then placed in a tube furnace for annealing. After annealing, the product is taken out and ground evenly to obtain sulfur-based polymer cathode material.

2. The method for preparing the sulfur-based polymer cathode material according to claim 1, characterized in that, The molecular weight of the polyacrylonitrile in step S1 is 5-50W, and the ratio of poly(1,2,4,5-tetraaminobenzene) to polyacrylonitrile is 1:2 to 2:

1. Using a planetary ball mill, the rotation speed of the planetary ball mill is 200-1000 rpm / min, and the milling time is 0.5-6 hours; The ratio of polymer mixture to elemental sulfur is 1:2 to 1:10, and the alcohol used has a purity of 99-100%. The drying temperature is 40-100℃, and the drying time is 0.5-48 hours.

3. The method for preparing the sulfur-based polymer cathode material according to claim 1, characterized in that, In step S2, the atmosphere inside the sealed quartz tube is argon or nitrogen, the heating temperature is 300-500℃, and the heating time is 2-20 hours.

4. The method for preparing the sulfur-based polymer cathode material according to claim 1, characterized in that, The annealing temperature in step S3 is 100-300℃, and the annealing time is 2-60 hours.

5. A sulfur-based polymer cathode material, characterized in that, Prepared using the method described in any one of claims 1 to 4.

6. The sulfur-based polymer cathode material according to claim 5, characterized in that, It is used in lithium metal batteries, lithium-ion batteries, sodium-ion batteries, sodium metal batteries, potassium-ion batteries, or potassium metal batteries.

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