Negative electrode material for improving rate capability, preparation method thereof, electrode and supercapacitor

Abstract

The invention discloses a negative electrode material for improving rate capability, a preparation method thereof, an electrode and a supercapacitor, and the preparation method comprises the following steps: S1, mixing polyethylene glycol, a tin-containing compound and titanium-based Mxene, adding an alkaline solution into the mixture, and uniformly stirring; s2, performing hydrothermal reaction on the uniformly stirred mixture, and drying to obtain an intermediate material; and S3, mixing the intermediate material with polyaniline, and calcining to obtain the modified negative electrode material. The physical and chemical properties of the MXene are optimized through multi-interface engineering, optimization and modification are carried out by improving the hydrophilicity and stability of the titanium-based MXene and increasing the synergistic effect between materials, and the supercapacitor with high rate performance is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of supercapacitors, and in particular to a negative electrode material with improved rate performance, a preparation method thereof, an electrode and a supercapacitor. Background Art

[0002] In today's society, the new energy industry is the preferred choice for most people and is gradually replacing the traditional energy industry. While this new energy industry primarily relies on lithium and sodium batteries, which offer excellent energy density and cycle life, they still have significant shortcomings in terms of power density.

[0003] As an emerging energy storage device, supercapacitors combine the advantages of traditional capacitors and batteries. They not only have excellent energy density and power density, but also have good performance in cycle life. However, the only drawback is that the charging and discharging capabilities of supercapacitors at high current density still have certain potential for improvement. Therefore, how to improve the rate performance of supercapacitors has become one of the research directions of many scholars. Summary of the Invention

[0004] The purpose of the present invention is to provide a negative electrode material with improved rate performance, a preparation method thereof, an electrode and a supercapacitor, and the rate performance is improved by modifying the negative electrode material.

[0005] To achieve the above object, the technical solution provided by the present invention is:

[0006] A first aspect of the present application provides a method for preparing a negative electrode material with improved rate performance, comprising the following steps:

[0007] S1: Mix polyethylene glycol, tin-containing compound and titanium-based MXene, add alkaline solution to the mixture, and stir evenly;

[0008] S2: subjecting the stirred mixture to a hydrothermal reaction and then drying to obtain an intermediate material;

[0009] S3: The intermediate material and polyaniline are mixed and calcined to obtain a modified negative electrode material.

[0010] To optimize the above technical solutions, specific measures taken also include:

[0011] In step S1, the amount of polyethylene glycol is 1-3% of the mass of the titanium-based Mxene, and the amount of tin element in the tin-containing compound is 0.6-3% of the mass of the titanium-based Mxene; in step S3, the amount of polyaniline is 2.5-4% of the mass of the titanium-based Mxene.

[0012] In step S1, the alkaline solution is a 0.5-1.5 mol / L sodium hydroxide or potassium hydroxide solution, and the mass / volume ratio of the titanium-based Mxene to the alkaline solution is 1:20-25 g / ml.

[0013] The tin-containing compound is selected from SnS2, SnCl4 or SnO2; the titanium-based Mxene is Ti3C2T x 、Ti3C2T x / N-CNT composites or Ti3C2T x / cellulose composite materials.

[0014] In step S2, the uniformly stirred mixture is subjected to a hydrothermal reaction and then dried to obtain an intermediate material. Specifically, the intermediate material is first subjected to a hydrothermal reaction and then dried, and then washed, filtered, and freeze-dried to obtain the intermediate material.

[0015] Furthermore, the conditions for the hydrothermal reaction and drying are: reacting at a temperature of 160 to 190° C. for 10 to 15 hours; the medium used for washing is water; and the conditions for freeze-drying are freezing at -45 to -35° C. for 5 to 7 hours to completely freeze, and then vacuum drying at -65 to -55° C. for 9 to 11 hours.

[0016] Furthermore, in step S3, the calcination conditions are: calcining at a temperature of 500-600° C. for 8-12 hours under nitrogen protection, wherein the heating rate is 30-50° C. / min, and the annealing rate is 20-40° C. / min.

[0017] The second aspect of the present application provides a negative electrode material with improved rate performance, which is prepared by the above method.

[0018] The third aspect of the present application provides an electrode containing the above-mentioned negative electrode material with improved rate performance.

[0019] A fourth aspect of the present application provides a supercapacitor comprising the above-mentioned electrode.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention prepares a modified MXene material by hydrothermal reaction and freeze-drying of polyethylene glycol (PEG2000), a tin-containing compound, and titanium-based MXene, and then calcining it with polyaniline at high temperature. The modified material is optimized by improving the hydrophilicity and stability of titanium-based MXene and increasing the synergistic effect between the materials, thereby improving the rate performance.

[0022] The present invention optimizes the physical and chemical properties of MXene through multiple interface engineering, providing new ideas for the design of high-rate performance supercapacitor electrode materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 : Schematic diagram of the process for preparing a negative electrode material with improved rate performance according to the present invention. DETAILED DESCRIPTION

[0024] The above contents of the present invention are further described in detail below in the form of specific implementation methods, but this should not be understood as the scope of the above subject matter of the present invention being limited to the following embodiments. All technologies implemented based on the above contents of the present invention belong to the scope of the present invention.

[0025] The experimental methods used in the following examples are conventional methods unless otherwise specified, and the reagents, methods and equipment used are conventional reagents, methods and equipment in the art unless otherwise specified.

[0026] The present invention provides a method for preparing a negative electrode material with improved rate performance, comprising the following steps:

[0027] S1: Mix polyethylene glycol, tin-containing compound and titanium-based MXene, add alkaline solution to the mixture, and stir evenly;

[0028] S2: subjecting the stirred mixture to a hydrothermal reaction and then drying to obtain an intermediate material;

[0029] S3: The intermediate material and polyaniline are mixed and calcined to obtain a modified negative electrode material.

[0030] In step S1, the amount of polyethylene glycol is 1-3% of the mass of the titanium-based Mxene, and the amount of tin element in the tin-containing compound is 0.6-3% of the mass of the titanium-based Mxene; in step S3, the amount of polyaniline is 2.5-4% of the mass of the titanium-based Mxene.

[0031] In step S1, the alkaline solution is a 0.5-1.5 mol / L sodium hydroxide or potassium hydroxide solution, and the mass / volume ratio of the titanium-based Mxene to the alkaline solution is 1:20-25 g / ml.

[0032] The tin-containing compound is selected from SnS2, SnCl4 or SnO2; the titanium-based Mxene is Ti3C2T x 、Ti3C2T x / N-CNT composites or Ti3C2T x / cellulose composite materials.

[0033] Among them, the titanium-based MXene is preferably a few-layer Ti3C2T x .

[0034] In step S2, the uniformly stirred mixture is subjected to a hydrothermal reaction and then dried to obtain an intermediate material. Specifically, the intermediate material is first subjected to a hydrothermal reaction and then dried, and then washed, filtered, and freeze-dried to obtain the intermediate material.

[0035] The conditions for the hydrothermal reaction and drying are: reacting at a temperature of 160-190° C. for 10-15 hours; and the washing medium is deionized water.

[0036] The freeze-drying conditions are: freezing at -45 to -35°C for 5 to 7 hours to completely freeze, and then vacuum drying at -65 to -55°C for 9 to 11 hours.

[0037] In step S3, the calcination conditions are: calcining at a temperature of 500-600° C. for 8-12 hours under nitrogen protection, wherein the heating rate is 30-50° C. / min, and the annealing rate is 20-40° C. / min.

[0038] In this application, polyethylene glycol (PEG2000), a tin-containing compound, and titanium-based MXene are subjected to hydrothermal reaction, freeze-dried, and then calcined with polyaniline at high temperature to prepare a modified MXene material:

[0039] The present invention helps prevent the secondary stacking of titanium-based MXene by introducing a small amount of surfactant PEG2000;

[0040] When titanium-based MXene is prepared by etching the MAX phase (such as Ti3AlC2) with hydrofluoric acid (HF), -F groups will be attached to the surface of MXene as a by-product of the etching reaction. Therefore, the alkaline solution in the hydrothermal reaction of the present invention not only facilitates the dissolution of the tin-containing compound, but also replaces the -F groups on the surface of the titanium-based MXene with -OH, thereby improving the hydrophilicity of the material.

[0041] Sn in tin-containing compounds 4+ It is uniformly attached to the surface of titanium-based MXene through ion exchange and electrostatic interaction, playing a synergistic role; Sn 4+ The introduction of Sn-O-Ti can partially fill the interlayer gaps of titanium-based MXene, forming a stable Sn-O-Ti bond and inhibiting the volume expansion during the cycle. The -OH group formed on the surface of MXene after alkali treatment has negative electronegativity and reacts with Sn-O-Ti to form a stable Sn-O-Ti bond. 4+ Through the combination of ion exchange and electrostatic interaction, Sn 4+ During high-temperature calcination in N2, the nitrogen source polyaniline nitrogen doped the intermediate material, further increasing the polarity of the Ti-C bond and the stability of the modified MXene material. In addition, during high-temperature calcination, the polyaniline carbonized to form a conductive network while retaining Sn. 4+ Active site.

[0042] Therefore, the present application improves the rate performance by increasing the hydrophilicity and stability of titanium-based MXene and increasing the synergy between materials.

[0043] The present invention also provides a negative electrode material with improved rate performance, which is prepared by the above method.

[0044] The present invention also provides an electrode containing the above-mentioned negative electrode material with improved rate performance.

[0045] The present invention also provides a supercapacitor comprising the above-mentioned electrode.

[0046] The technical solution of the present invention is further described in detail below with reference to specific embodiments:

[0047] Example 1:

[0048] (1) Modified few-layer Ti3C2T x Material preparation

[0049] A certain amount of polyethylene glycol (PEG2000), SnS2 and few-layer Ti3C2T x Put it into a beaker, add a certain amount of NaOH solution, stir evenly, transfer it to the reactor, and use a blast drying oven to dry it at 180℃ for 12h. After washing, filtering and freeze drying, the intermediate few-layer Ti3C2T x -Sn; freeze-drying conditions are as follows: place the sample in a freeze-drying chamber at -40°C and freeze for 6 hours to completely freeze the sample; place the completely frozen sample in a drying chamber, ensure a vacuum environment, reduce the pressure to 1.33 Pa, and keep the temperature at -60°C for 10 hours. Then, the intermediate and polyaniline are mechanically mixed and placed in a magnetic boat. N2 is introduced into a tube furnace and calcined at 500°C-600°C for 10 hours to finally obtain modified few-layer Ti3C2T x Materials. Heating rate: 40℃ / min, annealing rate: 30℃ / min.

[0050] Among them, few-layer Ti3C2T x The dosage is 5g, the concentration of NaOH solution is 1mol / L, the dosage is 110mL, and the addition amount of PEG2000 is x 1.5% of SnS2 is added to the few-layer Ti3C2T x The amount of polyaniline added is 2-3% (corresponding to the amount of Sn element 1.3-2.0%), and the amount of polyaniline added is a few-layer Ti3C2T x 3-3.5%;

[0051] (2) Preparation of negative electrode slurry:

[0052] The negative electrode active material is the product obtained in step (1) modified with a few-layer Ti3C2T x The materials, PVDF (KF1100) as the binder and Super P (Tremeco, Switzerland) as the conductive agent were mixed in a ratio of 8:1:1 for active material: binder: conductive agent. After mixing evenly, the mixture was coated on carbon paper and dried in a vacuum drying oven at 60°C for 12 hours.

[0053] (3) Rate performance test:

[0054] GCD (constant current charge and discharge) test was carried out using a three-electrode test system and an electrochemical workstation. The electrolyte in the electrolytic cell was 0.1M Na2SO4 solution, the reference electrode was Ag / AgCl electrode, the counter electrode was Pt electrode, and the working electrode was a carbon sheet coated with active material. The operating voltage range was -0.8 to 0V.

[0055] Example 2:

[0056] It is basically the same as Example 1, except that the amount of SnS2 added is less than that of Ti3C2T x 0.5-1% (corresponding to the amount of Sn element 0.32-0.65%).

[0057] Example 3:

[0058] It is basically the same as Example 1, except that the amount of SnS2 added is less than that of Ti3C2T x 1 to 2% (corresponding to the amount of Sn element 0.65 to 1.30%).

[0059] Example 4:

[0060] It is basically the same as Example 1, except that the amount of SnS2 added is less than that of Ti3C2T x 3-4% (corresponding to the amount of Sn element 1.95-2.60%).

[0061] Example 5:

[0062] It is basically the same as Example 1, except that the amount of SnS2 added is less than that of Ti3C2T x 4-5% (corresponding to the amount of Sn element 2.60-3.25%).

[0063] Example 6:

[0064] The same as Example 1, except that the amount of polyaniline added is less than that of Ti3C2T x 2 to 2.5%.

[0065] Example 7:

[0066] The same as Example 1, except that the amount of polyaniline added is less than that of Ti3C2T x 2.5 to 3% of the total.

[0067] Example 8:

[0068] The same as Example 1, except that the amount of polyaniline added is less than that of Ti3C2T x 3.5 to 4% of the total.

[0069] Example 9:

[0070] The same as Example 1, except that the amount of polyaniline added is less than that of Ti3C2T x 4 to 4.5%.

[0071] Comparative Example 1:

[0072] The process is basically the same as Example 1, except that no SnS2 is introduced in step 1.

[0073] Comparative Example 2:

[0074] The process is basically the same as Example 1, except that no polyaniline is introduced in step 1.

[0075] Comparative Example 3:

[0076] The process is basically the same as Example 1, except that PEG2000 is not introduced in step 1.

[0077] Comparative Example 4:

[0078] It is basically the same as Example 1, except that: the traditional few-layer Ti3C2T x material as negative electrode material.

[0079] The test evaluation results of each embodiment and comparative example are as follows (the above embodiments and comparative examples are tested multiple times according to the conditions described, and the data in Table 1 are the average values of multiple tests for each example):

[0080] Table 1 Test results of Examples and Comparative Examples

[0081]

[0082]

[0083] Comparing Examples 1 to 5, it can be seen that the amount of SnS2 added will affect the performance of the modified MXene material. When the amount of SnS2 added increases, the capacitance first increases and then decreases. 4+Excessive aggregation between MXene layers or on the surface may block the original nanoscale pore channels, resulting in obstruction of the electrolyte ion diffusion path and reducing the charge and discharge rate and capacitance retention rate.

[0084] Comparing Examples 1 and 6 to 9, it can be seen that, similarly, when the amount of polyaniline added is within a certain range, it can have a significant beneficial effect on the performance of the MXene material; excessive polyaniline may cover the MXene surface, hindering the exposure of the active sites of the MXene, resulting in a decrease in specific capacitance.

[0085] Comparing Example 1 with Comparative Examples 1 to 3, it can be seen that when no SnS2, polyaniline or PEG2000 is introduced, the synergistic effect cannot be achieved, which is different from the conventional few-layer Ti3C2T x The test results of the materials as negative electrode materials are almost equivalent.

[0086] The above description is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Any simple modification, equivalent replacement and improvement made by any technician familiar with the profession to the above embodiment without departing from the scope of the technical solution of the present invention and based on the technical essence of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing a negative electrode material with improved rate performance, characterized in that: The following steps are involved: S1: Mix polyethylene glycol, tin-containing compound and titanium-based MXene, add alkaline solution to the mixture, and stir evenly; S2: subjecting the uniformly stirred mixture to a hydrothermal reaction and then drying to obtain an intermediate material; S3: The intermediate material and polyaniline are mixed and calcined to obtain a modified negative electrode material.

2. The method for preparing a negative electrode material with improved rate performance according to claim 1, wherein: In step S1, the amount of polyethylene glycol is 1-3% of the mass of the titanium-based Mxene, and the amount of tin element in the tin-containing compound is 0.6-3% of the mass of the titanium-based Mxene; in step S3, the amount of polyaniline is 2.5-4% of the mass of the titanium-based Mxene.

3. The method for preparing a negative electrode material with improved rate performance according to claim 1, wherein: In step S1, the alkaline solution is a 0.5-1.5 mol / L sodium hydroxide or potassium hydroxide solution, and the mass / volume ratio of the titanium-based Mxene to the alkaline solution is 1:20-25 g / ml.

4. The method for preparing a negative electrode material with improved rate performance according to claim 1, wherein: The tin-containing compound is selected from SnS2, SnCl4 or SnO2; the titanium-based Mxene is Ti3C2T x 、Ti3C2T x / N-CNT composites or Ti3C2T x / cellulose composite materials.

5. The method for preparing a negative electrode material with improved rate performance according to claim 1, wherein: In step S2, the uniformly stirred mixture is subjected to a hydrothermal reaction and then dried to obtain an intermediate material. Specifically, the intermediate material is first subjected to a hydrothermal reaction and then dried, and then washed, filtered, and freeze-dried to obtain the intermediate material.

6. The method for preparing a negative electrode material with improved rate performance according to claim 5, characterized in that: The conditions for the hydrothermal reaction and drying are: reacting at a temperature of 160 to 190° C. for 10 to 15 hours; the medium used for washing is water; and the conditions for the freeze-drying are freezing at -45 to -35° C. for 5 to 7 hours to completely freeze, and then vacuum drying at -65 to -55° C. for 9 to 11 hours.

7. The method for preparing a negative electrode material with improved rate performance according to claim 1, wherein: In step S3, the calcination conditions are: calcination at a temperature of 500-600° C. for 8-12 hours under nitrogen protection, wherein the heating rate is 30-50° C. / min, and the annealing rate is 20-40° C. / min.

8. A negative electrode material with improved rate performance, characterized in that: A negative electrode material with improved rate performance prepared by the method according to any one of claims 1 to 7.

9. An electrode, characterized in that: A negative electrode material with improved rate performance according to claim 8.

10. A supercapacitor, characterized in that: Containing the electrode according to claim 9.

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