CN115249797A - Arrayed molybdenum-doped cobalt diselenide composite material and preparation method and application thereof - Google Patents

Arrayed molybdenum-doped cobalt diselenide composite material and preparation method and application thereof Download PDF

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CN115249797A
CN115249797A CN202111623603.3A CN202111623603A CN115249797A CN 115249797 A CN115249797 A CN 115249797A CN 202111623603 A CN202111623603 A CN 202111623603A CN 115249797 A CN115249797 A CN 115249797A
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cobalt
molybdenum
array
mixed solution
sodium
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杨叶锋
路米雪
姚珠君
蔡晨
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Zhejiang Sci Tech University ZSTU
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Abstract

The invention discloses an arrayed molybdenum-doped cobalt diselenide composite material as well as a preparation method and application thereof, wherein the method comprises the following steps: immersing a flexible conductive substrate into a mixed solution of 2-methylimidazole and cobalt nitrate to obtain a cobalt-based metal organic framework precursor with a unique structure; after cleaning and drying, putting the mixture into a sodium molybdate solution for water bath reaction to obtain a molybdenum-cobalt double metal hydroxide array with a complete structure; and then, respectively carrying out electrodeposition coating of polypyrrole and selenylation treatment on the carbon-coated molybdenum-doped cobalt diselenide composite material to obtain the arrayed carbon-coated molybdenum-doped cobalt diselenide composite material. The molybdenum doping can improve the conductivity of the cobalt diselenide and the electrode reaction kinetics, the use of a high-molecular binder can be avoided by the arraying and carbon coating design, the electrode preparation process is simplified, and the problems of volume expansion and shrinkage of the cobalt diselenide in the sodium deintercalation process are effectively solved. When the prepared composite electrode is used as a negative electrode material of a sodium-ion battery, excellent electrochemical performance is shown.

Description

Arrayed molybdenum-doped cobalt diselenide composite material and preparation method and application thereof
Technical Field
The invention relates to the technical field of cathode materials of sodium ion batteries, in particular to an arrayed molybdenum-doped cobalt diselenide composite material and a preparation method and application thereof.
Background
In recent years, flexible electronic devices have become more and more widely used in fields such as flexible sensors, wearable devices, energy storage, implant medicine, and the like. Therefore, the development of flexible batteries as energy supply carriers is receiving increasing attention. Among them, sodium Ion Batteries (SIBs) are widely paid attention by researchers because of their abundant sodium resource reserves, lower cost and great potential as a new generation of energy storage batteries. The negative electrode material plays an important role in improving the performance of the sodium ion battery, and the transition metal selenide has high specific capacity and is widely concerned by people. But its poor conductivity and the huge volume change caused by sodium desorption during electrochemical cycling lead to its capacity decay faster under high current, limiting its large-scale application.
In order to solve the problems, researchers have conducted a great deal of research and study on metal selenide materials, and found that the storage performance of sodium ions can be improved after certain regulation and control on the components and microstructures of the materials. In the aspect of component regulation, researchers usually adopt a metal ion doping mode to improve the conductivity of the selenide, and defects introduced by doping are beneficial to the intercalation and deintercalation of sodium ions, so that the electrochemical performance of the electrode material is improved. In addition, in the aspect of microstructure design, the selenide and the carbon material are compounded to stabilize the microstructure of the metal selenide, so that the electrode material is prevented from being pulverized due to huge volume change and stress in the process of sodium intercalation and deintercalation. Meanwhile, the carbon material is used as a conductive matrix to coat the metal selenide, so that the conductivity can be improved. However, the metal selenide powder material modified by the above means still needs to be coated with slurry to form an electrode, and is not suitable for flexible electronic devices.
Disclosure of Invention
Aiming at the problems in the background art, the invention aims to provide an arrayed molybdenum-doped cobalt diselenide composite material, and a preparation method and application thereof. The invention develops the binderless arrayed molybdenum-doped cobalt diselenide composite electrode material, compared with the traditional electrode, the complex preparation steps are simplified, the impedance of the electrode is reduced, and rich electron transmission channels are provided; the metal ion doped selenide can accelerate the electron and ion diffusion dynamics of the transition metal selenide; the stable carbon buffer layer can ensure rapid electron and ion transfer and relieve volume expansion. When the above strategy is used for the negative electrode material of the sodium-ion battery, the capacity is higher and the cycle life is longer.
According to the invention, based on the strategy, MOF with a unique structure is synthesized as a template, mo ions are successfully doped by using methods such as ion exchange and the like, and then the Mo ions are subjected to carbon coating treatment and further selenization treatment, so that the arrayed molybdenum-doped cobalt diselenide composite material with excellent performance is further obtained.
A preparation method of an arrayed molybdenum-doped cobalt diselenide composite material comprises the following steps:
(1) Stirring and mixing a cobalt salt aqueous solution and a 2-methylimidazole aqueous solution to obtain a mixed solution A;
(2) Transferring the mixed solution A obtained in the step (1) to a reaction kettle, adding a flexible substrate, standing for reaction for a period of time, taking out the flexible substrate, washing and drying to obtain a precursor cobalt-based metal organic framework (Co-MOF) array;
(3) Dissolving sodium molybdate in water, adding ethanol, and mixing and stirring uniformly to obtain a mixed solution B. Immersing the precursor Co-MOF array into the solution B for water bath, and after the water bath is finished, washing and drying to obtain a double-metal hydroxide Mo-Co LDH array;
(4) Dissolving pyrrole (Py), sodium Dodecyl Benzene Sulfonate (SDBS) and sodium chloride in deionized water in sequence, and stirring and mixing to obtain a mixed solution C. Soaking the Mo-Co LDH array obtained in the step (3) in a solution C for electrodeposition coating of polypyrrole (PPy), and after deposition is finished, washing and drying the Mo-Co LDH array to obtain a Mo-Co LDH @ PPy array;
(5) Taking selenium powder and Mo-Co LDH @ PPy obtained in the step (4) to be put in a tube furnace for heat treatment under the protection of inert gas, and obtaining carbon-coated molybdenum-doped cobalt diselenide (Mo-Co Se) after natural cooling 2 @ C) array.
The following are preferred technical schemes of the invention:
in the step (1), the mixed solution A adopts the following components in proportion:
60-100mL of water;
1-3mmol of cobalt salt;
8-24mmol of 2-methylimidazole;
wherein the cobalt salt is one of cobalt nitrate, cobalt chloride and cobalt sulfate, the stirring time is 5-30 minutes, and the solution A is purple suspension.
In the step (2), the standing reaction temperature is 10-60 ℃, and the standing time is 3-5 hours.
In the step (3), the using amount of sodium molybdate is 0.1-1.0g, and the total volume of water and ethanol is 100mL, wherein the volume ratio of water to ethanol is 1:3 to 5 (preferably 1:4). The water bath temperature is 70-95 ℃ and the time is 10-20 minutes.
In the step (4), the mixed solution B adopts the following components in proportion:
Figure BDA0003439023040000031
the electrodeposition adopts cyclic voltammetry, and the parameters are as follows: the number of deposition turns is 2-6 turns, the voltage range is 0.2-0.7V, and the scanning rate is 0.1-2.0mVs -1 。
In the step (5), the calcining atmosphere of the heat treatment is nitrogen or argon, the temperature is 300-500 ℃, the heat preservation time is 1-3 hours, and the heating rate is 1-5 ℃/min.
The arrayed molybdenum-doped cobalt diselenide composite material, mo-CoSe 2 @ C content of 0.9-1.3mgcm -2 。
The arrayed molybdenum-doped cobalt diselenide composite material comprises a molybdenum-doped cobalt diselenide sheet material uniformly grown on a substrate. It is characterized in that a regular and ordered sheet structure appears before calcination, good and regular morphology is still maintained after calcination of the coated carbon, and the length of the sheet is 1-2 μm.
The molybdenum-doped cobalt diselenide composite material array is used as a sodium ion battery cathode material, the obtained arrayed molybdenum-doped cobalt diselenide composite material is cut into square pieces of 1cm by 1cm and directly used as working electrodes, sodium metal foils are used as counter electrodes and reference electrodes, a glass fiber membrane is used as a diaphragm, and an electrolyte is 1M NaClO 4 Dissolved in a mixed solvent of ethylene carbonate and dimethyl carbonate (EC/DMC volume ratio of 1:1) and 5% by weight of fluoroethylene carbonate (FEC) was added as an additive. When the battery is assembled, the negative electrode shell, the electrode material, the diaphragm, the electrolyte, the sodium metal foil, the gasket, the elastic sheet and the positive electrode shell are assembled in sequence from bottom to top, and the operation is completed in a glove box filled with argon.
And (3) carrying out constant current charge and discharge test on the assembled sodium-ion battery after the assembled sodium-ion battery is placed for 12 hours, wherein the charge and discharge voltage is 3V-0.01V, and the specific capacity, the rate capability and the charge and discharge cycle performance of the negative electrode of the sodium-ion battery are measured in an environment of 25 +/-1 ℃.
Compared with the prior art, the invention has the following advantages:
(1) The invention develops a binder-free arrayed molybdenum-doped cobalt diselenide composite electrode material which is applied to a sodium ion battery. Compared with the traditional electrode, the method not only eliminates the problems of simplifying fussy electrode preparation steps and the like, but also reduces the impedance of the electrode, provides ordered and rich electron transmission channels, and is suitable for flexible electronic devices.
(2) The prepared arrayed molybdenum-doped cobalt diselenide composite material successfully realizes the doping introduction of Mo ions, and shows specific capacity exceeding that of a single component, namely the specific capacity of the composite electrode exceeds the theoretical specific capacity of cobalt diselenide. The Mo ion doping is beneficial to increasing the lattice size of the metal selenide, improving the conductivity and electrochemical activity of the metal selenide, and accelerating the electron and ion diffusion dynamics of the transition metal selenide, thereby obtaining the sodium storage performance exceeding that of the single-component transition metal selenide.
(3) The prepared arrayed molybdenum-doped cobalt diselenide composite material is successfully subjected to carbon coating, and the stable carbon buffer layer can ensure rapid electron and ion transfer in the charging and discharging process and relieve volume expansion and shrinkage caused by sodium deintercalation.
Drawings
Fig. 1 is an X-ray diffraction (XRD) pattern of the arrayed molybdenum-doped cobalt diselenide composite prepared in example 1;
FIGS. 2 (a), (b) are Scanning Electron Microscope (SEM) images of the precursor Co-MOF prepared in example 1 at different magnifications;
FIGS. 3 (a), (b) are SEM images of Mo-Co LDH at different magnifications prepared in example 1;
FIGS. 4 (a), (b) are SEM images of Mo-Co LDH @ PPy at different magnifications prepared in example 1;
FIGS. 5 (a), (b) are the arrayed Mo-CoSe doped with Mo-CoSe of Mo-Se prepared in example 1 under different magnifications 2 SEM image of @ C composite electrode material;
fig. 6 is a graph of the cell cycling performance of the arrayed molybdenum-doped cobalt diselenide composite electrode material prepared in example 1;
fig. 7 is a graph of cell rate performance for an arrayed molybdenum-doped cobalt diselenide composite electrode material prepared in example 1.
Detailed Description
The present invention will be further specifically described below by way of examples, but the present invention is not limited to the following examples.
Example 1
(1) Mixing 40mL of an aqueous solution containing 0.5821g of cobalt nitrate hexahydrate and 40mL of an aqueous solution containing 1.3137g of 2-methylimidazole (molar ratio 1:8) and stirring for 10 minutes to obtain a mixed solution A;
(2) Transferring the mixed solution A obtained in the step (1) to a reaction kettle, adding carbon cloth, standing for 4 hours at 25 ℃, taking out a sample, alternately washing with water and absolute ethyl alcohol for three times, and drying to obtain a precursor Co-MOF array;
(3) 0.2g of sodium molybdate dihydrate was dissolved in 20mL of water, followed by addition of 80mL of ethanol, followed by mixing and stirring for 5 minutes to obtain a mixed solution B. Then immersing the precursor Co-MOF array into the mixed solution B, carrying out water bath for 12 minutes at 85 ℃, after the water bath is finished, alternately washing the sample with water and absolute ethyl alcohol for three times, and drying to obtain a double-metal hydroxide Mo-Co LDH array;
(4) 70 mu L of pyrrole, 0.384g of Sodium Dodecyl Benzene Sulfonate (SDBS) and 0.0583g of sodium chloride are dissolved in 100mL of deionized water in sequence, and mixed and stirred for 30 minutes to obtain a mixed solution C. Soaking the Mo-Co LDH array obtained in the step (3) in a solution C for electrodeposition, wherein cyclic voltammetry is adopted, the voltage range is 0.2-0.7V, the deposition cycle number is 4 cycles, and the scanning rate is 1.0mVs -1 After the deposition is finished, alternately washing the substrate for three times by using water and absolute ethyl alcohol, and drying the substrate to obtain a Mo-Co LDH @ PPy array;
(5) Putting 3.0mg selenium powder and Mo-Co LDH @ PPy obtained in the step (4) in a tube furnace, heating to 400 ℃ at the heating rate of 2 ℃/min under the protection of nitrogen, preserving the temperature for 2 hours for selenization, and naturally cooling to obtain Mo-CoSe 2 The @ C array.
Fig. 1 is an XRD spectrum of the arrayed molybdenum-doped cobalt diselenide composite material prepared in this example 1. As can be seen from fig. 1, the molybdenum-doped cobalt diselenide composite material prepared in this example 1 shows characteristic peaks of cobalt diselenide of a macaroni structure (JCPDS No. 53-0449) and cobalt diselenide of a pyrite structure (JCPDS No. 09-0234). FIGS. 2 (a), (b) are SEM images of the precursor Co-MOF prepared in example 1 at different magnifications, the precursor Co-MOF array having smooth surface and sheet length of 1-2 μm. FIGS. 3 (a), (b) are SEM images of Mo-Co LDH at different magnifications prepared in example 1, with rougher surface. FIGS. 4 (a), (b) are SEM images of Mo-Co LDH @ PPy at different magnifications prepared in example 1, with the platelets significantly thickened and the structure not collapsed, remaining intact. FIGS. 5 (a), (b) are arrayed Mo-CoSe prepared in example 1 at different magnifications 2 SEM image of @ C composite material, with complete sheet-like array structure, and sheet-like size of 1-2 μm.
Example 2
(1) Mixing 40mL of an aqueous solution containing 1.1246g of cobalt sulfate hexahydrate and 40mL of an aqueous solution containing 1.3137g of 2-methylimidazole (molar ratio 1:4) and stirring for 10 minutes to obtain a mixed solution A;
(2) Transferring the mixed solution A obtained in the step (1) to a reaction kettle, adding carbon cloth, standing for 4 hours at 25 ℃, taking out a sample, alternately washing with water and absolute ethyl alcohol for three times, and drying to obtain a precursor Co-MOF array;
(3) 0.2g of sodium molybdate dihydrate was dissolved in 20mL of water, followed by addition of 80mL of ethanol, followed by mixing and stirring for 5 minutes to obtain a mixed solution B. Then immersing the precursor Co-MOF array into the mixed solution B, carrying out water bath for 12 minutes at 85 ℃, after the water bath is finished, alternately washing the sample with water and absolute ethyl alcohol for three times, and drying to obtain a double-metal hydroxide Mo-Co LDH array;
(4) 70 mu L of pyrrole, 0.384g of Sodium Dodecyl Benzene Sulfonate (SDBS) and 0.0583g of sodium chloride are dissolved in 100mL of deionized water in sequence, and mixed and stirred for 30 minutes to obtain a mixed solution C. Soaking the Mo-Co LDH array obtained in the step (3) in a solution C for electrodeposition, wherein cyclic voltammetry is adopted, the voltage range is 0.2-0.7V, the deposition turns are 4 turns, and the scanning rate is 1.0mVs -1 After the deposition is finished, alternately washing the substrate for three times by using water and absolute ethyl alcohol, and drying the substrate to obtain a Mo-Co LDH @ PPy array;
(5) Taking 3.0mg selenium powder and Mo-Co LDH @ PPy in the step (4) in a tube furnace, heating to 400 ℃ at the heating rate of 2 ℃/min under the protection of nitrogen, preserving heat for 2 hours for selenization treatment, and naturally cooling to obtain Mo-CoSe 2 The @ C array.
Example 3
(1) Mixing and stirring 40mL of an aqueous solution containing 0.2379g of cobalt chloride hexahydrate and 40mL of an aqueous solution containing 1.3137g of 2-methylimidazole (molar ratio 1;
(2) Transferring the mixed solution A obtained in the step (1) to a reaction kettle, adding carbon cloth, standing at 25 ℃ for 4 hours, taking out a sample, alternately washing with water and absolute ethyl alcohol for three times, and drying to obtain a precursor Co-MOF array;
(3) 0.2g of sodium molybdate dihydrate was dissolved in 20mL of water, followed by addition of 80mL of ethanol, followed by mixing and stirring for 5 minutes to obtain a mixed solution B. Then immersing the precursor Co-MOF array into the mixed solution B, carrying out water bath for 12 minutes at 85 ℃, after the water bath is finished, alternately washing the sample with water and absolute ethyl alcohol for three times, and drying to obtain a double-metal hydroxide Mo-Co LDH array;
(4) 70 mu L of pyrrole, 0.384g of Sodium Dodecyl Benzene Sulfonate (SDBS) and 0.0583g of sodium chloride are dissolved in 100mL of deionized water in sequence, and mixed and stirred for 30 minutes to obtain a mixed solution C. Soaking the Mo-Co LDH array obtained in the step (3) in a solution C for electrodeposition, wherein cyclic voltammetry is adopted, the voltage range is 0.2-0.7V, the deposition cycle number is 4 cycles, and the scanning rate is 1.0mVs -1 After the deposition is finished, alternately washing the substrate for three times by using water and absolute ethyl alcohol, and drying the substrate to obtain a Mo-Co LDH @ PPy array;
(5) Putting 3.0mg selenium powder and Mo-Co LDH @ PPy obtained in the step (4) in a tube furnace, heating to 400 ℃ at the heating rate of 2 ℃/min under the protection of nitrogen, preserving the temperature for 2 hours for selenization, and naturally cooling to obtain Mo-CoSe 2 The @ C array.
Example 4
(1) Mixing and stirring 40mL of an aqueous solution containing 0.5821g of cobalt nitrate hexahydrate and 40mL of an aqueous solution containing 1.3137g of 2-methylimidazole for 10 minutes to obtain a mixed solution A;
(2) Transferring the mixed solution A obtained in the step (1) to a reaction kettle, adding carbon cloth, standing for 4 hours at 25 ℃, taking out a sample, alternately washing with water and absolute ethyl alcohol for three times, and drying to obtain a precursor Co-MOF array;
(3) 0.2g of sodium molybdate dihydrate was dissolved in 20mL of water, followed by addition of 80mL of ethanol, followed by mixing and stirring for 5 minutes to obtain a mixed solution B. Then immersing the precursor Co-MOF array into the mixed solution B, carrying out water bath for 12 minutes at 70 ℃, after the water bath is finished, alternately washing the sample with water and absolute ethyl alcohol for three times, and drying to obtain a double-metal hydroxide Mo-Co LDH array;
(4) 100 mu L of pyrrole, 0.384g of Sodium Dodecyl Benzene Sulfonate (SDBS) and 0.0583g of sodium chloride are dissolved in 100mL of deionized water in sequence, and mixed and stirred for 30 minutes to obtain a mixed solution C. Soaking the Mo-Co LDH array obtained in the step (3) in a solution C for electrodeposition, and adopting cyclic voltammetry and a voltage range0.2-0.7V, 4 deposition turns, and a scan rate of 1.0mVs -1 After the deposition is finished, alternately washing the substrate for three times by using water and absolute ethyl alcohol, and drying the substrate to obtain a Mo-Co LDH @ PPy array;
(5) Putting 3.0mg selenium powder and Mo-Co LDH @ PPy obtained in the step (4) in a tube furnace, heating to 300 ℃ at a heating rate of 2 ℃/min under the protection of nitrogen, preserving heat for 2 hours for selenization, and naturally cooling to obtain Mo-CoSe 2 An array of @ C.
Example 5
(1) Mixing and stirring 40mL of an aqueous solution containing 0.5821g of cobalt nitrate hexahydrate and 40mL of an aqueous solution containing 1.3137g of 2-methylimidazole for 10 minutes to obtain a mixed solution A;
(2) Transferring the mixed solution A obtained in the step (1) to a reaction kettle, adding carbon cloth, standing for 4 hours at 25 ℃, taking out a sample, alternately washing with water and absolute ethyl alcohol for three times, and drying to obtain a precursor Co-MOF array;
(3) 0.2g of sodium molybdate dihydrate was dissolved in 20mL of water, followed by addition of 80mL of ethanol, and the mixture was stirred for 5 minutes to obtain a mixed solution B. Then immersing the precursor Co-MOF array into the mixed solution B, carrying out water bath for 12 minutes at 95 ℃, alternately washing the sample with water and absolute ethyl alcohol for three times after the water bath is finished, and drying to obtain a double-metal hydroxide Mo-Co LDH array;
(4) Dissolving 40 mu L of pyrrole, 0.384g of Sodium Dodecyl Benzene Sulfonate (SDBS) and 0.0583g of sodium chloride in 100mL of deionized water, and mixing and stirring for 30 minutes to obtain a mixed solution C. Soaking the Mo-Co LDH array obtained in the step (3) in a solution C for electrodeposition, wherein cyclic voltammetry is adopted, the voltage range is 0.2-0.7V, the deposition cycle number is 4 cycles, and the scanning rate is 1.0mVs -1 After the deposition is finished, alternately washing the substrate for three times by using water and absolute ethyl alcohol, and drying the substrate to obtain a Mo-Co LDH @ PPy array;
(5) Taking 3.0mg selenium powder and Mo-Co LDH @ PPy obtained in the step (4) into a tube furnace, heating to 500 ℃ at the heating rate of 2 ℃/min under the protection of nitrogen, preserving the temperature for 2 hours for selenization, and naturally cooling to obtain Mo-CoSe 2 The @ C array.
Example 6
(1) Mixing and stirring 40mL of an aqueous solution containing 0.5821g of cobalt nitrate hexahydrate and 40mL of an aqueous solution containing 1.3137g of 2-methylimidazole for 10 minutes to obtain a mixed solution A;
(2) Transferring the mixed solution A obtained in the step (1) to a reaction kettle, adding carbon cloth, standing at 25 ℃ for 4 hours, taking out a sample, alternately washing with water and absolute ethyl alcohol for three times, and drying to obtain a precursor Co-MOF array;
(3) 0.2g of sodium molybdate dihydrate was dissolved in 20mL of water, followed by addition of 80mL of ethanol, followed by mixing and stirring for 5 minutes to obtain a mixed solution B. Then immersing the precursor Co-MOF array into the mixed solution B, carrying out water bath for 12 minutes at 85 ℃, after the water bath is finished, alternately washing the sample with water and absolute ethyl alcohol for three times, and drying to obtain a double-metal hydroxide Mo-Co LDH array;
(4) Dissolving 40 mu L of pyrrole, 0.384g of sodium dodecyl benzene sulfonate SDBS and 0.0583g of sodium chloride in 100mL of deionized water in sequence, and mixing and stirring for 30 minutes to obtain a mixed solution C. Soaking the Mo-CoLDH array obtained in the step (3) in a solution C for electrodeposition, wherein cyclic voltammetry is adopted, the voltage range is 0.2-0.7V, the deposition turns are 2 turns, and the scanning rate is 0.5mVs -1 After the deposition is finished, alternately washing the substrate for three times by using water and absolute ethyl alcohol, and drying the substrate to obtain a Mo-CoLDH @ PPy array;
(5) Putting 3.0mg selenium powder and Mo-CoLDH @ PPy obtained in the step (4) in a tube furnace, heating to 400 ℃ at the heating rate of 2 ℃/min under the protection of nitrogen, preserving the temperature for 2 hours for selenization, and naturally cooling to obtain Mo-CoSe 2 The @ C array.
Example 7
(1) Mixing and stirring 40mL of an aqueous solution containing 0.5821g of cobalt nitrate hexahydrate and 40mL of an aqueous solution containing 1.3137g of 2-methylimidazole for 10 minutes to obtain a mixed solution A;
(2) Transferring the mixed solution A obtained in the step (1) to a reaction kettle, adding carbon cloth, standing for 4 hours at 25 ℃, taking out a sample, alternately washing with water and absolute ethyl alcohol for three times, and drying to obtain a precursor Co-MOF array;
(3) 0.2g of sodium molybdate dihydrate was dissolved in 20mL of water, followed by addition of 80mL of ethanol, followed by mixing and stirring for 5 minutes to obtain a mixed solution B. Then immersing the precursor Co-MOF array into the mixed solution B, carrying out water bath for 12 minutes at 85 ℃, after the water bath is finished, alternately washing the sample with water and absolute ethyl alcohol for three times, and drying to obtain a double-metal hydroxide Mo-Co LDH array;
(4) 100 mu L of pyrrole, 0.384g of Sodium Dodecyl Benzene Sulfonate (SDBS) and 0.0583g of sodium chloride are dissolved in 100mL of deionized water in sequence, and mixed and stirred for 30 minutes to obtain a mixed solution C. Soaking the Mo-Co LDH array obtained in the step (3) in a solution C for electrodeposition, wherein cyclic voltammetry is adopted, the voltage range is 0.2-0.7V, the deposition cycle number is 6 cycles, and the scanning rate is 2.0mVs -1 After the deposition is finished, alternately washing the substrate for three times by using water and absolute ethyl alcohol, and drying the substrate to obtain a Mo-Co LDH @ PPy array;
(5) Putting 3.0mg selenium powder and Mo-Co LDH @ PPy obtained in the step (4) in a tube furnace, heating to 400 ℃ at the heating rate of 2 ℃/min under the protection of nitrogen, preserving the temperature for 2 hours for selenization, and naturally cooling to obtain Mo-CoSe 2 The @ C array.
The molybdenum-doped cobalt diselenide composite material obtained in the step (5) in the embodiment is used as a sodium ion battery cathode material, the obtained arrayed molybdenum-doped cobalt diselenide composite material is cut into square pieces of 1cm by 1cm and directly used as working electrodes, sodium metal foils are used as counter electrodes and reference electrodes, meanwhile, a glass fiber membrane is used as a diaphragm, and an electrolyte is 1M NaClO 4 Dissolved in a mixed solvent of ethylene carbonate and dimethyl carbonate (EC/DMC volume ratio of 1:1), and 5% by weight of fluoroethylene carbonate (FEC) was added as an additive. When the battery is assembled, the negative electrode shell, the electrode material, the diaphragm, the electrolyte, the sodium foil, the gasket, the elastic sheet and the positive electrode shell are assembled in sequence from bottom to top, and the operation is completed in a glove box filled with argon.
And (3) carrying out constant current charge and discharge test on the assembled sodium-ion battery after the assembled sodium-ion battery is placed for 12 hours, wherein the charge and discharge voltage is 3V-0.01V, and the specific capacity, the rate capability and the charge and discharge cycle performance of the negative electrode of the sodium-ion battery are measured in an environment of 25 +/-1 ℃.
With the change of selenization temperature and the number of electrodeposition cycles, the sodium ion battery shows different electrochemical performances, and the maximum discharge capacities at different current densities after the Mo-doped cobalt diselenide composite array materials in examples 1 to 7 are assembled into the sodium ion battery as sodium ion electrode materials are shown in table 1:
TABLE 1
Figure BDA0003439023040000101
As can be seen from the table, the water bath temperature, the selenization temperature of the heat treatment, and the carbon coating process all have an influence on the performance of the Mo-doped cobalt diselenide composite material. When the water bath temperature and the selenization temperature are reduced (examples 1 and 4), the material performance is reduced, which shows that the exchange rate of Mo ions is reduced at a lower water bath temperature, so that the exchange amount of the Mo ions is insufficient; meanwhile, the diffusion is insufficient at a lower temperature, and the crystallinity of the composite material is lower, so that the rate capability is reduced; however, too high selenization temperature (examples 1 and 5) can make the material sheet become thin and brittle, which leads to severe pulverization of the electrode material during the circulation process and reduces the overall performance of the electrode. Then, when the influence of the carbon coating thickness on the battery was investigated, it was found that a moderate carbon coating (examples 1, 6, and 7) had an important influence on the improvement of the performance. Because the carbon coating is too thin, the effect of relieving volume expansion of the material in the circulation process is insufficient; the carbon coating layer is too thick, which will hinder the migration of sodium ions and reduce the rate capability.
Fig. 6 is a graph of the cycling performance of the sodium ion battery of example 1. As can be seen from the figure, the current density of the sodium-ion battery is 0.5A g -1 The electrochemical performance is excellent, and 672.5mAh g is still kept after 200 cycles of cycle -1 The capacity of (c). FIG. 7 is a multiplying power diagram of a sodium ion battery at 0.2A g -1 、0.5A g -1 、1A g -1 、2A g -1 、5A g -1 And return 0.2A g -1 The capacity of the current density is 1203.8mAh g -1 、754.1mAh g -1 、522.5mAh g -1 、398.4mAh g -1 、313.9mAh g -1 、1109.1mAh g -1 And excellent rate performance is shown.

Claims (10)

1. A preparation method of an arrayed molybdenum-doped cobalt diselenide composite material is characterized by comprising the following steps:
(1) Stirring and mixing a cobalt salt aqueous solution and a 2-methylimidazole aqueous solution to obtain a mixed solution A;
(2) Transferring the mixed solution A obtained in the step (1) to a reactor, adding a flexible substrate, standing for reaction, taking out the flexible substrate, washing and drying to obtain a precursor Co-MOF array;
(3) Dissolving sodium molybdate in water, adding ethanol, mixing and stirring uniformly to obtain a mixed solution B, immersing a precursor Co-MOF array into the mixed solution B for water bath, and washing and drying after the water bath is finished to obtain a double-metal hydroxide Mo-Co LDH array;
(4) Dissolving pyrrole, sodium dodecyl benzene sulfonate and sodium chloride in deionized water in sequence, stirring and mixing to obtain a mixed solution C, soaking the Mo-Co LDH array obtained in the step (3) in the mixed solution C for electrodeposition coating of polypyrrole, and washing and drying the Mo-Co LDH array after deposition to obtain a Mo-Co LDH @ PPy array;
(5) And (4) putting selenium powder and the Mo-Co LDH @ PPy array obtained in the step (4) into a tube furnace, carrying out heat treatment under protective gas, and cooling to obtain the arrayed molybdenum doped cobalt diselenide composite material.
2. The preparation method according to claim 1, wherein in the step (1), the mixed solution A comprises the following components in proportion:
60-100mL of water;
1-3mmol of cobalt salt;
8-24mmol of 2-methylimidazole.
3. The method according to claim 1, wherein in step (1), the cobalt salt is one of cobalt nitrate, cobalt chloride and cobalt sulfate.
4. The production method according to claim 1, wherein in the step (2), the temperature of the standing reaction is 10 to 60 ℃ and the time of the standing reaction is 3 to 5 hours.
5. The method according to claim 1, wherein in the step (3), the ratio of the water to the ethanol to the sodium molybdate is 100mL:0.1-1.0g, wherein the volume ratio of water to ethanol in water and ethanol is 1:3 to 5.
6. The method according to claim 1, wherein in the step (3), the temperature of the water bath is 70 to 95 ℃ for 10 to 20 minutes.
7. The preparation method according to claim 1, wherein in the step (4), the mixed solution C comprises the following components in proportion:
Figure FDA0003439023030000021
8. the method according to claim 1, wherein in the step (5), the protective gas is nitrogen or argon, the heat treatment temperature is 300 to 500 ℃, and the heat treatment holding time is 1 to 3 hours.
9. The arrayed molybdenum-doped cobalt diselenide composite material prepared by the preparation method according to any one of claims 1 to 8, which is characterized by having a sheet-like structure.
10. The use of the arrayed molybdenum-doped cobalt diselenide composite material of claim 9 as a sodium ion battery negative electrode material.
CN202111623603.3A 2021-12-28 2021-12-28 Arrayed molybdenum-doped cobalt diselenide composite material and preparation method and application thereof Pending CN115249797A (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115787300A (en) * 2022-12-01 2023-03-14 陕西科技大学 Preparation method of hierarchical-structure polypyrrole/NiCoAl-LDH/cotton fiber flexible electrode material

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