A sulfonic acid-based organic polymer, a sulfonic acid-based organic polymer / carbon nanotube composite material, and a preparation method and application thereof

Abstract

This invention belongs to the technical field of lithium-ion battery cathode materials, specifically relating to a sulfonic acid-based organic polymer, a sulfonic acid-based organic polymer / carbon nanotube composite material, its preparation method, and its application. The sulfonic acid-based organic polymer is prepared by a dehydration condensation reaction of 2,5-diaminobenzenesulfonic acid and hexaazabenzophenanthrene hexacarboxylic acid trianal. When used as a lithium-ion battery cathode material, it exhibits high specific capacity and excellent cycle stability, overcoming the solubility problem of organic cathode materials in electrolytes. When the sulfonic acid-based organic polymer is combined with carbon nanotubes and applied to lithium-ion battery cathode materials, battery performance is significantly improved, and the capacity remains stable even after long-term cycling. The synthesis methods of the sulfonic acid-based organic polymer and the sulfonic acid-based organic polymer / carbon nanotube composite material of this invention are simple, have abundant raw material sources, and good reproducibility, making them suitable for industrial production and possessing broad application prospects in the field of lithium-ion batteries.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery cathode material technology, and specifically relates to a sulfonic acid-based organic polymer, a sulfonic acid-based organic polymer / carbon nanotube composite material, its preparation method and application. Background Technology

[0002] With increasing industrial activity and rising energy consumption and demand, traditional rechargeable batteries are gradually losing their ability to meet current and future market demands. To address this challenge, developing advanced, flexible, and controllable energy technologies has become an urgent priority. Currently, lithium-ion batteries present some safety issues and environmental hazards, necessitating the consideration of alternatives. One approach to improving the efficiency of energy storage devices is to focus on the development and improvement of their components, such as electrode materials and separators. Cathode materials play a crucial role in the composition of lithium-ion batteries, not only because of their high cost but also because they significantly impact battery performance.

[0003] Traditional inorganic materials are limited in natural resources and pose a risk of heavy metal pollution, which is detrimental to future green development needs. Furthermore, when used as cathodes in lithium-ion batteries, these inorganic materials exhibit low capacity; for example, the theoretical specific capacity of LiCoO2 is only 274 mAh g⁻¹. -1 However, its actual specific capacity is only half of the theoretical capacity; for example, the theoretical capacity of LiMn2O4 is only 147 mAh g. -1 Organic materials, due to their abundant sources and relatively low environmental impact during extraction and synthesis, have gained increasing attention in the battery field in recent years for replacing currently used inorganic materials with redox-active organic materials as electrode materials for lithium-ion batteries. However, the low conductivity of most organic electrode materials and the high solubility of many small-molecule organic materials in electrolytes lead to low overall battery capacity and poor cycle stability, limiting the commercialization of organic lithium-ion batteries. However, research over the past few decades has revealed that some organic cathode materials possess strong functional design capabilities, allowing for the improvement of battery performance through the introduction of specific functional structural units. In 2014, Wang et al. reported a group of sulfonated anthraquinone compounds (AQDS) and studied the effect of the presence or absence of sulfonic acid functional groups on the electrochemical performance of cathode materials. Although this material only achieved a 130 mAh g⁻¹ at 0.2C... -1 Despite its low specific capacity, it exhibits excellent cycling stability, indicating that sulfonation modification plays a multifunctional role in solving the solubility problem of the compound and regulating the lithium storage voltage (RSCA Advances, 2014, 4(38): 19878-19882). Furthermore, combining the material with carbon nanotubes can also improve performance; for example, in 2022, Yao et al. combined COF with dual active centers... TPDA-PMDAIn-situ composite with carbon nanotubes via π-π interactions significantly enhances electronic conductivity and mass transfer kinetics through the abundant triangular micropores and hexagonal mesopores in the structure. At 5A g -1 It still maintains 80mAh g after 1800 cycles at high current density. -1 High capacity and cycling stability (Journal of the American Chemical Society, 2022, 144(51): 23534-23542).

[0004] Therefore, introducing specific functional groups and combining them with materials such as carbon nanotubes is considered an effective way to improve the performance of lithium-ion batteries. Thus, researching such materials as cathode materials for lithium-ion batteries is expected to discover organic cathode materials with high capacity and excellent cycle performance, thereby promoting the application and development of high-performance lithium batteries. Summary of the Invention

[0005] The purpose of this invention is to provide a sulfonic acid-based organic polymer, a sulfonic acid-based organic polymer / carbon nanotube composite material, and a method for preparing the same, and to apply the sulfonic acid-based organic polymer and the sulfonic acid-based organic polymer / carbon nanotube composite material to lithium-ion battery cathode materials.

[0006] This invention provides a sulfonic acid-based organic polymer with the following structural formula:

[0007]

[0008] Furthermore, the sulfonic acid-based organic polymer (PSHT-polymer) is generated by reacting 2,5-diaminobenzenesulfonic acid and hexaazabenzophenanthrene hexacarboxylic acid trihydric acid, and the synthesis reaction equation is as follows:

[0009]

[0010] The specific steps are as follows:

[0011] 2,5-Diaminobenzenesulfonic acid, hexaazabenzenephenanthrene hexacarboxylic acid trihydride, and organic solvent are added to a thick-walled reaction flask. After being fully dissolved and dispersed, a dehydration condensation reaction is carried out by a solvothermal method. After the reaction is completed and cooled to room temperature, the mixture is filtered or centrifuged, washed 2-3 times with deionized water, and dried under vacuum to obtain the product, which is the sulfonic acid-based organic polymer.

[0012] Furthermore, the molar ratio of 2,5-diaminobenzenesulfonic acid and hexaazabenzophenanthrene hexacarboxylic acid trihydric acid is 1.5:1-1.6:1.

[0013] Furthermore, the organic solvent is N,N-dimethylformamide or 1-methyl-2-pyrrolidone.

[0014] Furthermore, the concentration of the 2,5-diaminobenzenesulfonic acid in the organic solvent is 50-75 mmol / L.

[0015] Furthermore, the dehydration condensation reaction is carried out at a temperature of 120-165℃ for 2-5 days.

[0016] The present invention also provides a sulfonic acid-based organic polymer / carbon nanotube composite material, which is formed by in-situ composite of the above-mentioned sulfonic acid-based organic polymer and carbon nanotube, wherein the mass ratio of sulfonic acid-based organic polymer to carbon nanotube is 1:1-3:1.

[0017] Furthermore, the preparation method of the sulfonic acid-based organic polymer / carbon nanotube composite material includes the following steps: after uniformly mixing organic solvent, hexaazabenzanphenanthrene hexacarboxylic acid trihydric acid, carbon nanotubes and 2,5-diaminobenzenesulfonic acid, a dehydration condensation reaction is carried out by solvothermal method. After the reaction is completed and cooled to room temperature, the mixture is filtered or centrifuged, washed and dried to obtain the sulfonic acid-based organic polymer / carbon nanotube composite material.

[0018] Furthermore, the molar ratio of 2,5-diaminobenzenesulfonic acid and hexaazabenzophenanthrene hexacarboxylic acid trihydric acid is 1.5:1-1.6:1;

[0019] The concentration of the 2,5-diaminobenzenesulfonic acid in the organic solvent is 50-75 mmol / L;

[0020] The organic solvent is N,N-dimethylformamide or 1-methyl-2-pyrrolidone.

[0021] This invention also provides the application of the above-mentioned sulfonic acid-based organic polymers and sulfonic acid-based organic polymer / carbon nanotube composite materials in lithium-ion battery cathode materials, the specific steps of which are as follows:

[0022] An electrode sheet made of sulfonic acid-based organic polymer or sulfonic acid-based organic polymer / carbon nanotube composite material was used as the positive electrode, lithium foil as the negative electrode, and porous polypropylene as the separator. 1.0 mol L -1 LiTFSI and 1 wt% LiNO3 were dissolved in DME (dimethoxyethane) and DOL (1,3-dioxolane) in a volume ratio of 1:1 as electrolytes and assembled into coin cells;

[0023] The electrode sheet, made from sulfonic acid organic polymer or sulfonic acid organic polymer / carbon nanotube composite material, is prepared by mixing and grinding sulfonic acid organic polymer or sulfonic acid organic polymer / carbon nanotube composite material, battery conductive agent, and binder in a mass ratio of 30:60:10-60:30:10, adding an appropriate amount of dispersant (such as 1-methyl-2-pyrrolidone), grinding again, and then uniformly coating it onto the current collector aluminum sheet and vacuum drying to form the electrode sheet.

[0024] Compared with the prior art, the features of this invention are:

[0025] The sulfonic acid-based organic polymer of this invention has a simple, easy-to-operate, low-cost, and readily available raw material synthesis method with good reproducibility and excellent performance. When used as a cathode material for lithium-ion batteries, it exhibits high specific capacity and excellent cycle stability. The sulfonic acid-based organic polymer has a specific capacity of 0.05 Ag. -1 It has 156.2mAh g -1 The initial discharge specific capacity, and at 0.1A g -1 After 1000 cycles, it still retains 83.3mAh g. -1 The capacity retention rate reached 71.3%, demonstrating excellent cycle stability.

[0026] This invention obtains a sulfonic acid-based organic polymer / carbon nanotube composite material by compositing a sulfonic acid-based organic polymer with carbon nanotubes. The performance of the sulfonic acid-based organic polymer is significantly improved, especially at 0.05 Ag. -1 Below, the capacity is increased to 216.3mAh g. -1 Even at high currents (2Ag) -1 Under these conditions, the capacity increased by nearly 20 mAh g compared to sulfonic acid-based organic polymers. -1 Furthermore, the capacity remains stable even after long-term cycling. The sulfonic acid-based organic polymer / carbon nanotube composite material of this invention not only overcomes the dissolution problem of organic cathode materials in electrolytes, but also improves conductivity and enhances material performance through compositing with carbon nanotubes, while also exhibiting high stability. As a novel lithium-ion battery cathode material, this sulfonic acid-based organic polymer / carbon nanotube composite material possesses high discharge specific capacity, long-term cycle stability, and good rate performance, showing broad application prospects in the field of lithium-ion battery electrode materials. Attached image description:

[0027] Figure 1 Here is a structural diagram of the PSHT polymer material;

[0028] Figure 2 The NMR H-spectrum of the PSHT-polymer material;

[0029] Figure 3 The NMR C-spectrum of the PSHT-polymer material;

[0030] Figure 4 The infrared spectrum of the PSHT-polymer material is shown below.

[0031] Figure 5 The image shows the Raman spectrum of the PSHT-polymer material.

[0032] Figure 6Thermogravimetric curve of PSHT-polymer material;

[0033] Figure 7 The graph shows the nitrogen adsorption-desorption and pore size distribution of the PSHT-polymer material.

[0034] Figure 8 Cyclic voltammetry of PSHT-polymer coin cells at different scan rates;

[0035] Figure 9 The rate performance diagram of PSHT-polymer coin cells is shown.

[0036] Figure 10 The charge-discharge curves of PSHT-polymer coin cells at different current densities are shown.

[0037] Figure 11 For PSHT-polymer coin cells, in 0.1Ag -1 Cyclic stability plot at current density;

[0038] Figure 12 The AC impedance diagram for a PSHT-polymer coin cell is shown.

[0039] Figure 13 The infrared spectrum of the material PSHT-polymer / carbon nanotubes;

[0040] Figure 14 Thermogravimetric curve of PSHT-polymer / carbon nanotube material;

[0041] Figure 15 The nitrogen adsorption-desorption and pore size distribution curves of the PSHT-polymer / carbon nanotube material are shown.

[0042] Figure 16 The 0.1 mV s of the PSHT-polymer / carbon nanotube coin cell is shown. -1 Cyclic voltammogram at scan rate;

[0043] Figure 17 The rate performance of the PSHT-polymer / carbon nanotube coin cell is shown in the figure.

[0044] Figure 18 The charge-discharge curves of the PSHT-polymer / carbon nanotube material at different current densities are shown.

[0045] Figure 19 For PSHT-polymer / carbon nanotube coin cells, in 0.1A g -1 Cyclic stability plot at current density. Detailed Implementation

[0046] The present invention will be further described below through specific embodiments.

[0047] Example 1

[0048] 30 mL of N,N-dimethylformamide (DMF) was added to a 48 mL thick-walled reaction flask, along with 2,5-diaminobenzenesulfonic acid (2.25 mmol, 0.423 g) and hexaazabenzophenanthrene hexacarboxylic acid trihydric acid (purchased from Maclean, 1.5 mmol, 0.6663 g). After thorough dissolution and dispersion, the thick-walled reaction flask was subjected to vacuum treatment and kept at 125 °C for 4 days. After the reaction was completed, the mixture was washed three times with deionized water, and the solid was collected by filtration or centrifugation. The solid was then dried under vacuum at 100 °C for 12 h to obtain the sulfonic acid-based organic polymer material, i.e., PSHT-polymer, with a yield of 71%.

[0049] PSHT polymer was used as the active material for the positive electrode, mixed with acetylene black (Ningbo Weike Battery Co., Ltd.) and PVDF binder in a certain ratio. The ratio of PSHT polymer:acetylene black:PVDF binder was 30%:60%:10% (mass ratio). After mixing and grinding for 2 hours, an appropriate amount of 1-methyl-2-pyrrolidone (NMP) was added and grinding was repeated for 0.5 hours. The mixture was then uniformly coated onto a 1×1 cm aluminum foil sheet and vacuum dried overnight at 80°C to form an electrode sheet. This electrode sheet was used as the positive electrode, a lithium sheet as the negative electrode, and porous polypropylene (PP, Hangzhou Chuangwei Rubber & Plastics Technology Co., Ltd., hereinafter the same) as the separator. 1.0 mol L -1 LiTFSI and 1 wt% LiNO3 were dissolved in DME (dimethoxyethane) and DOL (1,3-dioxolane) in a volume ratio of 1:1 as electrolytes, assembled into coin cells, and their electrochemical performance was investigated. Figure 8 Cyclic voltammetry of a coin cell at different scan rates; Figure 9 This is a rate performance diagram for button cells. Figure 10 The graphs show the charge-discharge curves of a coin cell at different current densities, starting at 0.05 Ag. -1 The capacity can reach 140.8mAh g. -1 , in 2Ag -1 The capacity is still 56.1mAh g. -1 ; Figure 11 The circuit stability graph for the coin cell shows a capacity retention of 71.3%.

[0050] Example 2

[0051] 30 mL of N,N-dimethylformamide (DMF) was added to a 48 mL thick-walled reaction flask, along with 2,5-diaminobenzenesulfonic acid (2.25 mmol, 0.423 g), hexaazabenzphenanthrene hexacarboxylic acid trihydric acid (purchased from Maclean, 1.5 mmol, 0.6663 g), and carbon nanotubes (0.31 g). After thorough mixing and dispersion, the thick-walled reaction flask was subjected to vacuum treatment and kept at 125 °C for 4 days. After the reaction was completed, the mixture was washed three times with deionized water, and the solid was collected by filtration or centrifugation. The solid was then dried under vacuum at 100 °C for 12 h to obtain the sulfonic acid-based organic polymer / carbon nanotube material, i.e., PSHT-polymer / carbon nanotube, with a sulfonic acid-based organic polymer:carbon nanotube ratio of 2:1 (mass ratio) and a yield of 75%.

[0052] The method of assembling a coin cell using PSHT-polymer / carbon nanotubes as the active material for the positive electrode is the same as in Example 1, except that PSHT-polymer is replaced with PSHT-polymer / carbon nanotubes. The electrode preparation and battery preparation methods are exactly the same as in Example 1, and their electrochemical performance is examined.

[0053] Figure 16 The 0.1 mV s of the PSHT-polymer / carbon nanotube coin cell is shown. -1 Cyclic voltammogram at scan rate; Figure 17 The graph shows the rate performance of the PSHT-polymer / carbon nanotube coin cell at 0.05 Ag. -1 The capacity can reach 216.3mAh g. -1 In 2A g -1 The capacity is still 74.4mAh g. -1 When the current density returns to 0.05 and 0.1 A g -1 The hourly capacity recovered to 198.6 and 176.1 mAh g, respectively. -1 , Figure 18 The charge-discharge curves of the PSHT-polymer / carbon nanotube material at different current densities are shown. Figure 19 For PSHT-polymer / carbon nanotube coin cells, at 0.05 A g -1 Cyclic stability at current density: after 240 cycles, the capacity retention is nearly 99.9%.

[0054] Example 3

[0055] The experimental method was the same as in Example 1, except that the reaction conditions of holding at 125°C for 4 days were changed to holding at 140°C for 3 days, and the PSHT-polymer material was obtained with a yield of 70%.

[0056] Example 4

[0057] The experimental method was the same as in Example 2, except that the reaction conditions of holding at 125°C for 4 days were changed to holding at 140°C for 3 days, and the PSHT-polymer / carbon nanotube material was obtained with a yield of 74%.

[0058] Example 5

[0059] The experimental method was the same as in Example 2, except that the reaction conditions of sulfonic acid organic polymer: carbon nanotube = 2:1 (mass ratio) were changed to sulfonic acid organic polymer: carbon nanotube = 1:1 (mass ratio), thus obtaining the material PSHT-polymer / carbon nanotube with a yield of 73%.

[0060] Example 6

[0061] The experimental method was the same as in Example 2, except that the reaction conditions of sulfonic acid organic polymer: carbon nanotube = 2:1 (mass ratio) were changed to sulfonic acid organic polymer: carbon nanotube = 3:2 (mass ratio), thus obtaining the material PSHT-polymer / carbon nanotube with a yield of 74%.

[0062] Example 7

[0063] The experimental method was the same as in Example 1, except that the reaction conditions were changed from adding 30 mL of N,N-dimethylformamide (DMF) to adding 30 mL of 1-methyl-2-pyrrolidone (NMP), thus obtaining the PSHT-polymer material with a yield of 69%.

[0064] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. The application of a sulfonic acid-based organic polymer in lithium-ion battery cathode materials, characterized in that, The specific steps are as follows: using an electrode sheet prepared from a sulfonic acid-based organic polymer as the positive electrode, lithium foil as the negative electrode, porous polypropylene as the separator, and LiTFSI and LiNO3 dissolved in dimethoxyethane and 1,3-dioxolane as the electrolyte, assembling a coin cell; the structural formula of the sulfonic acid-based organic polymer is as follows:

2. The application of the sulfonic acid-based organic polymer as described in claim 1 in lithium-ion battery cathode materials, characterized in that, The process includes the following steps: After uniformly mixing organic solvent, hexaazabenzophenanthrene hexacarboxylic acid trihydric acid and 2,5-diaminobenzenesulfonic acid, a dehydration condensation reaction is carried out by solvothermal method. After the reaction is completed and cooled to room temperature, the mixture is filtered or centrifuged, washed and dried to obtain sulfonic acid-based organic polymer material.

3. The application of the sulfonic acid-based organic polymer as described in claim 2 in lithium-ion battery cathode materials, characterized in that, The molar ratio of 2,5-diaminobenzenesulfonic acid and hexaazabenzophenanthrene hexacarboxylic acid trihydric acid is 1.5:1-1.6:1; The concentration of the 2,5-diaminobenzenesulfonic acid in the organic solvent is 50-75 mmol / L; The organic solvent is N,N-dimethylformamide or 1-methyl-2-pyrrolidone.

4. The application of the sulfonic acid-based organic polymer as described in claim 2 in lithium-ion battery cathode materials, characterized in that, The dehydration condensation reaction is carried out at a temperature of 120-165℃ for 2-5 days.

5. The application of a sulfonic acid-based organic polymer / carbon nanotube composite material in lithium-ion battery cathode materials, characterized in that, The specific steps are as follows: an electrode sheet made of sulfonic acid organic polymer / carbon nanotube composite material is used as the positive electrode, lithium foil is used as the negative electrode, porous polypropylene is used as the separator, and LiTFSI and LiNO3 are dissolved in dimethoxyethane and 1,3-dioxolane as the electrolyte to assemble a coin cell. The sulfonic acid-based organic polymer / carbon nanotube composite material is formed by in-situ composite of the sulfonic acid-based organic polymer and carbon nanotubes as described in claim 1, wherein the mass ratio of the sulfonic acid-based organic polymer to the carbon nanotubes is 1:1-3:

1.

6. The application of the sulfonic acid-based organic polymer / carbon nanotube composite material as described in claim 5 in the cathode material of lithium-ion batteries, characterized in that, The process includes the following steps: After uniformly mixing organic solvent, hexaazabenzphenanthrene hexacarboxylic acid trihydric acid, carbon nanotubes and 2,5-diaminobenzenesulfonic acid, a dehydration condensation reaction is carried out by solvothermal method. After the reaction is completed and cooled to room temperature, the mixture is filtered or centrifuged, washed and dried to obtain a sulfonic acid-based organic polymer / carbon nanotube composite material.

7. The application of the sulfonic acid-based organic polymer / carbon nanotube composite material as described in claim 6 in the cathode material of lithium-ion batteries, characterized in that, The molar ratio of 2,5-diaminobenzenesulfonic acid and hexaazabenzophenanthrene hexacarboxylic acid trihydric acid is 1.5:1-1.6:1; The concentration of the 2,5-diaminobenzenesulfonic acid in the organic solvent is 50-75 mmol / L; The organic solvent is N,N-dimethylformamide or 1-methyl-2-pyrrolidone.

8. The application of the sulfonic acid-based organic polymer / carbon nanotube composite material as described in claim 6 in the cathode material of lithium-ion batteries, characterized in that, The dehydration condensation reaction is carried out at a temperature of 120-165℃ for 2-5 days.

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