Preparation method and application of selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery diaphragm

Abstract

The application discloses a preparation method and application of a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery diaphragm. A MoO3@ZIF-8 nanotube precursor material is synthesized through a hydrothermal method, and then is subjected to annealing treatment and selenium treatment, so as to obtain a selenium and nitrogen co-doped carbon loaded molybdenum carbide modified diaphragm. The application has the advantages of mild reaction condition, simple preparation method, obvious structural advantages of the obtained product, three-dimensional network structure of nanotube which can accelerate the transmission of electrons and ions and provide a large number of catalytic sites, strong polarity which can improve the adsorption capacity of polysulfides, and the like, and the lithium-sulfur battery has high discharge specific capacity, large current rate bearing capacity and excellent cycle stability, so that the lithium-sulfur battery has a wide application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lithium-sulfur batteries, and particularly relates to a preparation method and application of a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery diaphragm. BACKGROUND

[0002] To achieve the carbon neutralization goal, electric vehicles (EVs) and large-scale energy storage systems (ESSs) have been rapidly developed. For many years, lithium-ion batteries (LIBs) have been widely used in these fields as a green power source. Lithium-sulfur (Li-S) batteries, which have a high theoretical specific capacity (1675 mAh g -1 ) and energy density (2600 Wh kg -1 ), have attracted extensive attention from researchers and are considered to be one of the most promising high-energy storage systems. The chargeability of these batteries mainly depends on the redox conversion of polysulfides (LiPSs) with long or short sulfur chains (from S8 2- to S2 2- ). One of the main problems they face in practical applications is the "shuttle effect" caused by the dissolution of polysulfides in the electrolyte. These soluble polysulfides can migrate unimpeded through the porous diaphragm to the lithium anode, resulting in active material loss and shortening of the battery cycle life. In the past few decades, many immobilization strategies have been developed to address this problem, such as composite cathodes, polysulfide adsorption, solid electrolytes, and electrolyte additives. Although these strategies prevent the escape of soluble polysulfides from the cathode to some extent, there is increasing evidence that the inhomogeneous deposition of lithium ions on the anode side can lead to dendrite growth and battery short circuits. In addition, the "dead sulfur" generated near the commercial polypropylene (PP) diaphragm during the charge and discharge cycle also causes serious problems. Therefore, some researchers propose to modify the traditional diaphragm by coating a layer of functional material on its surface. Common modification materials based on physical barriers and chemical adsorption include carbon nanotubes, graphene, nitrides, sulfides, etc., which are coated on the surface of the traditional diaphragm to prevent the escape of soluble polysulfides from the anode. However, the modification strategy is difficult to enhance the adsorption sites of the polar material and also difficult to change the slow kinetics of the polysulfide conversion process. Therefore, the development of new modified materials with excellent chemical adsorption performance and high electrolytic activity is still an important topic. SUMMARY

[0003] To solve the above problems, the purpose of the present application is to provide a preparation method and application of a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery diaphragm, which is used to develop controllable preparation technology of selenium and nitrogen co-doped molybdenum-based material electrocatalysts, to accelerate the redox reaction kinetics of sulfur and inhibit the "shuttle effect" of polysulfides.

[0004] To achieve the above object, the present application adopts the following technical solutions to achieve the above object:

[0005] A preparation method of a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery separator, comprising the following steps:

[0006] S1: Dissolve MoO3, polyvinylpyrrolidone and metal zinc salt in anhydrous methanol, and obtain a mixed solution after sufficient stirring;

[0007] S2: Dissolve 2-methylimidazole in anhydrous methanol, and obtain a clear solution after sufficient stirring;

[0008] S3: Mix and stir the mixed solution of S1 and the clear solution of S2 to obtain a precipitate, and obtain MoO3@ZIF-8 precursor material after washing and drying the precipitate;

[0009] S4: Anneal the MoO3@ZIF-8 precursor material to obtain a nitrogen-doped carbon loaded molybdenum carbide material;

[0010] S5: Mix and heat treat the nitrogen-doped carbon loaded molybdenum carbide material with selenium powder to obtain a selenium and nitrogen co-doped carbon loaded molybdenum carbide material;

[0011] S6: Mix the selenium and nitrogen co-doped carbon loaded molybdenum carbide material with a PVDF binder, then add it to an N-methylpyrrolidone solvent and stir uniformly to form a slurry, coat the slurry on the surface of a commercial polypropylene separator, and dry to obtain a modified battery separator.

[0012] Preferably, in step S1, the metal zinc salt is zinc nitrate, zinc chloride or zinc sulfate; the mass ratio of MoO3 to polyvinylpyrrolidone is 1:10-10:1; the mass ratio of MoO3 to metal zinc salt is 1:10-10:1; the mass ratio of polyvinylpyrrolidone to metal zinc salt is 1:5-5:1; the concentration of MoO3 is 0.01-0.1 mmol / mL; the concentration of polyvinylpyrrolidone is 0.0001-0.001 mmol / mL; and the concentration of metal zinc salt is 0.01-0.1 mmol / mL.

[0013] Preferably, in step S2, the concentration of 2-methylimidazole in methanol is 0.1-1 mmol / mL.

[0014] Preferably, in step S3, the volume ratio of the mixed solution of S1 to the clear solution of S2 is 2:1-1:2; the stirring time is 20-45 min; and the washing is performed by washing with water and ethanol for 3-5 times.

[0015] Preferably, in step S4, the atmosphere for annealing the MoO3@ZIF-8 precursor material is N2 or Ar / H2 mixed gas; the annealing temperature is 600-900 °C; and the annealing time is 1-3 h.

[0016] As preferred, the mass ratio of the nitrogen-doped carbon supported molybdenum carbide to selenium powder mixed in step 5 is 1:10-10:1.

[0017] As preferred, the atmosphere of the heat treatment in step S5 is N2 or Ar / H2 mixed gas, the time of the heat treatment is 1-5 h, and the temperature of the heat treatment is 300-700 °C.

[0018] As preferred, the selenium and nitrogen co-doped carbon supported molybdenum carbide material in step S6 is 15-25 mg, the PVDF binder is 2-3 mg, and the N-methyl pyrrolidone solvent is 90-110 mg, and the slurry is coated on the surface of a commercial polypropylene separator with a thickness of 10-100 μm.

[0019] As preferred, the temperature of the drying in step S6 is 40-90 °C, and the drying time is 9-18 h.

[0020] The selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator can be used to make a battery.

[0021] The selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator prepared according to the above method has a nanorod-shaped catalyst, the doping of each element is uniform, and the synergistic effect between multiple active components enables the electrocatalyst to effectively resist polysulfides and accelerate the sulfur redox reaction kinetics and inhibit the "shuttle effect" of polysulfides.

[0022] As preferred, the prepared selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator exhibits excellent performance when assembled into a lithium-sulfur battery, such as a discharge specific capacity of 1156.0 and 572.1 mAh g -1 at a rate of 0.2 C and 5 C, respectively, and a cycle capacity decay rate of only 0.055% per cycle after 700 cycles at a current rate of 1 C.

[0023] By adjusting the electronic structure of the catalyst material through various strategies, such as heteroatom doping and defect engineering, the chemical action and catalytic activity can be effectively improved. Recently, molybdenum-based materials can strongly interact with soluble polysulfides through various mechanisms due to their adjustable crystal structure, adjustable composition, and variable valence of Mo, thereby inhibiting the "shuttle effect". In addition, molybdenum-based materials also have a strong affinity for lithium, which helps to inhibit the formation of lithium dendrites on the anode and prolong the cycle life of lithium-sulfur batteries. At the same time, we selected selenium as a "composite accelerator" to improve the redox reaction kinetics of sulfur, and the doping of selenium is expected to further enhance the catalytic effect of the material on polysulfides.

[0024] Compared with the prior art, the present application has the following beneficial effects:

[0025] The application discloses a preparation method and application of a selenium-nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery diaphragm. -1 The battery assembled by the catalyst modified diaphragm can reach a discharge specific capacity of 572.1 mAh g

[0026] The application also discloses the preparation method of the selenium-nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery diaphragm. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The X-ray diffraction pattern of the selenium-nitrogen co-doped carbon loaded molybdenum-based catalyst prepared in Example 1;

[0028] Figure 2 The scanning electron microscope (SEM) image of the selenium-nitrogen co-doped carbon loaded molybdenum-based catalyst prepared in Example 1;

[0029] Figure 3 The physical properties of the selenium-nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery diaphragm prepared in Example 1;

[0030] Figure 4 The long cycle performance of the lithium-sulfur battery assembled by the selenium-nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery diaphragm prepared in Example 1;

[0031] Figure 5 The rate performance of the lithium-sulfur battery assembled by the selenium-nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery diaphragm prepared in Example 1. DETAILED DESCRIPTION

[0032] To enable those skilled in the art to understand the features and effects of the present application, the following is a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific words used in the text are the usual meanings understood by those skilled in the art for the present application, and in case of conflict, the definition in the specification shall prevail.

[0033] Theories or mechanisms described and disclosed herein, whether correct or not, should not in any way limit the scope of the present application, i.e., the present application can be practiced without being limited by any particular theory or mechanism.

[0034] Herein, all features defined by a numerical range or a percentage range, such as numerical values, amounts, contents and concentrations, are for the sake of brevity and convenience only. Accordingly, the description of a numerical range or a percentage range should be considered to have encompassed and specifically disclosed all possible sub-ranges and individual numerical values within the range (including integers and fractions).

[0035] Herein, unless otherwise specifically noted, "comprise", "comprising", "contain", "containing", "have", "having", or the like, are all meant to encompass the "consisting of" and "consisting essentially of" concepts, e.g., "A comprises a" means "A comprises a and other", as well as "A comprises only a".

[0036] Herein, for the sake of brevity, all possible combinations of the various technical features described in the various embodiments or examples are not described. Therefore, the various technical features in the various embodiments or examples can be combined with each other as long as there is no contradiction in the combination, and all possible combinations are to be considered as falling within the scope of the present specification.

[0037] The present application is further described in detail by the following Examples. It is to be understood that the examples are only used to illustrate the present application and not intended to limit the scope of the present application. Furthermore, it is to be understood that various modifications or changes can be made by those skilled in the art upon reading the contents of the present specification, and such equivalent forms are also to be included within the scope of the appended claims.

[0038] The following examples use the apparatuses and devices that are conventional in the art. The experimental methods in the following examples, unless otherwise specified, are usually carried out under the conventional conditions, or under the conditions recommended by the manufacturers. The following examples use various raw materials, unless otherwise specified, and the conventional commercially available products are used, and the specifications are the conventional specifications in the art. In the specification of the present application and the following examples, unless otherwise specified, "%" means weight percent, "parts" means weight parts, and the ratio means weight ratio. Example

[0039] A method for preparing and using a selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator includes the following steps:

[0040] S1: 200 mg of MoO3, 1 g of polyvinylpyrrolidone (PVP), and 5 mmol of zinc nitrate hexahydrate (1487.45 mg) were mixed into 60 mL of anhydrous methanol, and a mixed solution was obtained after sufficient stirring.

[0041] S2: 40 mmol of 2-methylimidazole was dissolved in 60 mL of anhydrous methanol, and a clear solution was obtained after sufficient stirring.

[0042] S3: The mixed solution was mixed with a clear solution, and after stirring for 30 min, a precipitate was obtained, which was collected by centrifugation, washed with water and ethanol for 3 times, and vacuum dried to obtain MoO3@ZIF-8 precursor material.

[0043] S4: The MoO3@ZIF-8 was annealed at 800 °C for 2 h in an Ar / H2(10%) atmosphere to obtain a nitrogen-doped carbon-loaded molybdenum carbide material.

[0044] S5: The nitrogen-doped carbon-loaded molybdenum carbide material was heated with selenium powder (mass ratio = 10:1) at 600 °C for 4 h in an Ar / H2(10%) atmosphere to obtain a selenium and nitrogen co-doped carbon-loaded molybdenum carbide material.

[0045] S6: 20 mg of the selenium and nitrogen co-doped carbon-loaded molybdenum carbide material was mixed with 2.3 mg of PVDF binder, then added to 100 mg of N-methyl pyrrolidone (NMP) solvent and stirred uniformly to form a slurry. The slurry was coated on the surface of a commercial polypropylene (PP) separator, with a thickness of 20 μm. After drying at 60 °C for 12 h, a modified battery separator was obtained.

[0046] The modified separator was used to assemble a lithium-sulfur battery and perform electrochemical tests as follows:

[0047] (1) Sulfur powder and Super C were mixed in a mass ratio of 7:3 and ground for 30 min, then placed in an oven at 155 °C for 12 h, and after cooling, a sulfur-carbon positive electrode material was obtained.

[0048] (2) The sulfur-carbon positive electrode material, conductive carbon, and PVDF binder were mixed and ground uniformly in a mass ratio of 8:1:1, then the slurry was coated on the surface of a carbon-coated aluminum foil, and after vacuum drying at 60 °C, it was cut into a circular sheet with a diameter of 10 mm to obtain a sulfur-carbon electrode sheet.

[0049] (3) In an argon-filled glove box, a button cell was assembled with a sulfur-carbon electrode sheet as the positive electrode, a metal lithium as the negative electrode, and the selenium and nitrogen co-doped carbon-loaded molybdenum-based lithium-sulfur battery separator of the application as the separator. The electrolyte composition was: 1 mol / L of lithium bis(trifluoromethylsulfonyl)imide, 2 wt% of lithium nitrate; the solvent was a mixture of 1,3-dioxolane (DOL) and dimethyl ether of ethylene glycol (DME) in a volume ratio of 1:1.

[0050] Figure 1 The X-ray diffraction pattern of the selenium and nitrogen co-doped carbon-loaded molybdenum-based electrocatalyst prepared in Example 1 is shown. From the X-ray diffraction pattern of the product, it can be seen that the synthesized product is MoC, has high phase purity, is highly consistent with the standard card JCPDF No. 65-3558 of MoC, has a hexagonal crystal structure, and a space group of P63 / mmc, a = 3.013 Å, c = 14.640 Å.

[0051] Figure 2 SEM images of the selenium and nitrogen co-doped carbon supported molybdenum-based electrocatalyst prepared in Example 1 are shown. The SEM images show that the catalyst is in the form of nanorods with a size of about 200 nm in diameter.

[0052] Figure 3 Physical properties of the selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator prepared in Example 1 are shown. The modified separator did not fall off after being folded and restored, which indicates that the modified separator has good physical properties.

[0053] Figure 4 Long cycle performance of the lithium-sulfur battery assembled with the selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator prepared in Example 1 is shown. The lithium-sulfur battery assembled with the modified separator has a long cycle performance at 1 C, with an initial discharge specific capacity of 941.9 mAh g -1 , and still maintains 575.4 mAh g -1 after 700 cycles, with a capacity decay rate of only 0.055% per cycle.

[0054] Figure 5 Rate performance of the lithium-sulfur battery assembled with the selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator prepared in Example 1 is shown. The lithium-sulfur battery assembled with the modified separator has excellent rate performance and reversibility. The discharge specific capacities at 0.2, 0.5, 1, 2, 3, 5 C are 1156.0 mAh g -1 , 875.7 mAh g -1 , 785.9 mAh g -1 , 708.7 mAh g -1 , 640.7 mAh g -1 , 571.4 mAh g -1 , and 928.0 mAh g -1 when returning to 0.2 C, showing excellent redox reaction reversibility. Example

[0055] According to the method of Example 1, except that the metal zinc salt in step (1) is zinc chloride, and the rest is the same as Example 1, a selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator is obtained. Example

[0056] According to the method of Example 1, except that the metal zinc salt in step (1) is zinc sulfate, and the rest is the same as Example 1, a selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator is obtained. Example

[0057] A selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator was obtained according to the method of Example 1, except that the mass ratio of MoO3 to PVP in step (1) was 1:10, and the rest were the same as Example 1. Example

[0058] A selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator was obtained according to the method of Example 1, except that the mass ratio of MoO3 to PVP in step (1) was 1:1, and the rest were the same as Example 1. Example

[0059] A selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator was obtained according to the method of Example 1, except that the mass ratio of MoO3 to PVP in step (1) was 5:1, and the rest were the same as Example 1. Example

[0060] A selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator was obtained according to the method of Example 1, except that the mass ratio of MoO3 to PVP in step (1) was 10:1, and the rest were the same as Example 1. Example

[0061] A selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator was obtained according to the method of Example 1, except that the mass ratio of MoO3 to metal zinc salt in step (1) was 1:10, and the rest were the same as Example 1. Example

[0062] A selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator was obtained according to the method of Example 1, except that the mass ratio of MoO3 to metal zinc salt in step (1) was 1:5, and the rest were the same as Example 1.

[0063] Example 10:

[0064] A selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator was obtained according to the method of Example 1, except that the mass ratio of MoO3 to metal zinc salt in step (1) was 1:1, and the rest were the same as Example 1.

[0065] Example 11:

[0066] A selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator was obtained according to the method of Example 1, except that the mass ratio of MoO3 to metal zinc salt in step (1) was 5:1, and the rest were the same as Example 1.

[0067] Example 12:

[0068] The method is the same as that in Example 1, except that the mass ratio of MoO3 to metal zinc salt in step (1) is 10:1, and the rest is the same as in Example 1, to obtain a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery separator.

[0069] Example 13:

[0070] The method is the same as that in Example 1, except that the mass ratio of PVP to metal zinc salt in step (1) is 1:5, and the rest is the same as in Example 1, to obtain a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery separator.

[0071] Example 14:

[0072] The method is the same as that in Example 1, except that the mass ratio of PVP to metal zinc salt in step (1) is 1:1, and the rest is the same as in Example 1, to obtain a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery separator.

[0073] Example 15:

[0074] The method is the same as that in Example 1, except that the mass ratio of PVP to metal zinc salt in step (1) is 5:1, and the rest is the same as in Example 1, to obtain a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery separator.

[0075] Example 16:

[0076] The method is the same as that in Example 1, except that the concentration of MoO3 in step (1) is 0.01 mmol / mL, and the rest is the same as in Example 1, to obtain a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery separator.

[0077] Example 17:

[0078] The method is the same as that in Example 1, except that the concentration of MoO3 in step (1) is 0.05 mmol / mL, and the rest is the same as in Example 1, to obtain a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery separator.

[0079] Example 18:

[0080] The method is the same as that in Example 1, except that the concentration of MoO3 in step (1) is 0.1 mmol / mL, and the rest is the same as in Example 1, to obtain a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery separator.

[0081] Example 19:

[0082] The method according to example 1, except that the concentration of PVP in step (1) is 0.0001 mmol / mL, and the rest is the same as example 1, to obtain a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery separator.

[0083] Example 20:

[0084] The method according to example 1, except that the concentration of PVP in step (1) is 0.0005 mmol / mL, and the rest is the same as example 1, to obtain a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery separator.

[0085] Example 21:

[0086] The method according to example 1, except that the concentration of PVP in step (1) is 0.001 mmol / mL, and the rest is the same as example 1, to obtain a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery separator.

[0087] Example 22:

[0088] The method according to example 1, except that the concentration of metal zinc salt in step (1) is 0.01 mmol / mL, and the rest is the same as example 1, to obtain a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery separator.

[0089] Example 23:

[0090] The method according to example 1, except that the concentration of metal zinc salt in step (1) is 0.05 mmol / mL, and the rest is the same as example 1, to obtain a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery separator.

[0091] Example 24:

[0092] The method according to example 1, except that the concentration of metal zinc salt in step (1) is 0.1 mmol / mL, and the rest is the same as example 1, to obtain a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery separator.

[0093] Example 25:

[0094] The method according to example 1, except that the concentration of 2-methylimidazole in methanol in step (2) is 0.1 mmol / mL, and the rest is the same as example 1, to obtain a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery separator.

[0095] Example 26:

[0096] The method of Example 1 was followed, except that in step (2) the concentration of 2-methylimidazole in methanol was 0.5 mmol / mL, and the rest was the same as Example 1, to obtain a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery separator.

[0097] Example 27:

[0098] The method of Example 1 was followed, except that in step (2) the concentration of 2-methylimidazole in methanol was 1 mmol / mL, and the rest was the same as Example 1, to obtain a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery separator.

[0099] Example 28:

[0100] The method of Example 1 was followed, except that in step (3) the volume ratio of the S1 mixed solution to the S2 clear solution was 2:1, and the rest was the same as Example 1, to obtain a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery separator.

[0101] Example 29:

[0102] The method of Example 1 was followed, except that in step (3) the volume ratio of the S1 mixed solution to the S2 clear solution was 1:2, and the rest was the same as Example 1, to obtain a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery separator.

[0103] Example 30:

[0104] The method of Example 1 was followed, except that in step (4) the annealing atmosphere for the MoO3@ZIF-8 precursor material was N2, and the rest was the same as Example 1, to obtain a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery separator.

[0105] Example 31:

[0106] The method of Example 1 was followed, except that in step (4) the annealing atmosphere for the MoO3@ZIF-8 precursor material was Ar / H2(5%), and the rest was the same as Example 1, to obtain a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery separator.

[0107] Example 32:

[0108] The method of Example 1 was followed, except that in step (4) the annealing time for the MoO3@ZIF-8 precursor material was 1 h, and the rest was the same as Example 1, to obtain a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery separator.

[0109] Example 33:

[0110] According to the method of Example 1, except that the annealing treatment time of the MoO3@ZIF-8 precursor material in step (4) is 3 h, and the others are the same as Example 1, a selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator is obtained.

[0111] Example 34:

[0112] According to the method of Example 1, except that the annealing treatment time of the MoO3@ZIF-8 precursor material in step (4) is 4 h, and the others are the same as Example 1, a selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator is obtained.

[0113] Example 35:

[0114] According to the method of Example 1, except that the annealing treatment time of the MoO3@ZIF-8 precursor material in step (4) is 5 h, and the others are the same as Example 1, a selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator is obtained.

[0115] Example 36:

[0116] According to the method of Example 1, except that the annealing treatment temperature of the MoO3@ZIF-8 precursor material in step (4) is 600 °C, and the others are the same as Example 1, a selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator is obtained.

[0117] Example 37:

[0118] According to the method of Example 1, except that the annealing treatment temperature of the MoO3@ZIF-8 precursor material in step (4) is 700 °C, and the others are the same as Example 1, a selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator is obtained.

[0119] Example 38:

[0120] According to the method of Example 1, except that the annealing treatment temperature of the MoO3@ZIF-8 precursor material in step (4) is 900 °C, and the others are the same as Example 1, a selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator is obtained.

[0121] Example 39:

[0122] According to the method of Example 1, except that the mixing of the nitrogen-doped carbon supported molybdenum carbide and selenium powder in step (5) is 1:10 in mass ratio, and the others are the same as Example 1, a selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator is obtained.

[0123] Example 40:

[0124] According to the method of Example 1, except that in step (5), the nitrogen-doped carbon loaded molybdenum carbide is mixed with selenium powder, the mass ratio is 1:5, and the rest is the same as Example 1, a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery separator is obtained.

[0125] Example 41:

[0126] According to the method of Example 1, except that in step (5), the nitrogen-doped carbon loaded molybdenum carbide is mixed with selenium powder, the mass ratio is 1:1, and the rest is the same as Example 1, a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery separator is obtained.

[0127] Example 42:

[0128] According to the method of Example 1, except that in step (5), the nitrogen-doped carbon loaded molybdenum carbide is mixed with selenium powder, the mass ratio is 5:1, and the rest is the same as Example 1, a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery separator is obtained.

[0129] Example 43:

[0130] According to the method of Example 1, except that in step (5), the nitrogen-doped carbon loaded molybdenum carbide is mixed with selenium powder, the atmosphere is N2, and the rest is the same as Example 1, a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery separator is obtained.

[0131] Example 44:

[0132] According to the method of Example 1, except that in step (5), the nitrogen-doped carbon loaded molybdenum carbide is mixed with selenium powder, the atmosphere is Ar / H2(5%), and the rest is the same as Example 1, a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery separator is obtained.

[0133] Example 45:

[0134] According to the method of Example 1, except that in step (5), the nitrogen-doped carbon loaded molybdenum carbide is mixed with selenium powder, the heat treatment time is 1 h, and the rest is the same as Example 1, a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery separator is obtained.

[0135] Example 46:

[0136] According to the method of Example 1, except that in step (5), the nitrogen-doped carbon loaded molybdenum carbide is mixed with selenium powder, the heat treatment time is 2 h, and the rest is the same as Example 1, a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery separator is obtained.

[0137] Example 47:

[0138] According to the method of Example 1, except that in step (5) the nitrogen-doped carbon supported molybdenum carbide was mixed with selenium powder, the heat treatment time was 3 h, and the rest were the same as Example 1, a selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator was obtained.

[0139] Example 48:

[0140] According to the method of Example 1, except that in step (5) the nitrogen-doped carbon supported molybdenum carbide was mixed with selenium powder, the heat treatment time was 5 h, and the rest were the same as Example 1, a selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator was obtained.

[0141] Example 49:

[0142] According to the method of Example 1, except that in step (5) the nitrogen-doped carbon supported molybdenum carbide was mixed with selenium powder, the heat treatment temperature was 300 °C, and the rest were the same as Example 1, a selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator was obtained.

[0143] Example 50:

[0144] According to the method of Example 1, except that in step (5) the nitrogen-doped carbon supported molybdenum carbide was mixed with selenium powder, the heat treatment temperature was 400 °C, and the rest were the same as Example 1, a selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator was obtained.

[0145] Example 51:

[0146] According to the method of Example 1, except that in step (5) the nitrogen-doped carbon supported molybdenum carbide was mixed with selenium powder, the heat treatment temperature was 500 °C, and the rest were the same as Example 1, a selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator was obtained.

[0147] Example 52:

[0148] According to the method of Example 1, except that in step (5) the nitrogen-doped carbon supported molybdenum carbide was mixed with selenium powder, the heat treatment temperature was 700 °C, and the rest were the same as Example 1, a selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator was obtained.

[0149] Example 53:

[0150] According to the method of Example 1, except that in step (6) 15 mg of selenium and nitrogen co-doped carbon supported molybdenum carbide material was mixed with 2 mg of PVDF binder and then added to 90 mg of N-methyl pyrrolidone (NMP) solvent to form a slurry, and the rest were the same as Example 1, a selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator was obtained.

[0151] Example 54:

[0152] The method of Example 1 was followed, except that in step (6), 25 mg of selenium and nitrogen co-doped carbon supported molybdenum carbide material was mixed with 3 mg of PVDF binder and then added to 110 mg of N-methyl pyrrolidone (NMP) solvent to form a slurry, and the rest was the same as Example 1, to obtain a selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator.

[0153] Example 55:

[0154] The method of Example 1 was followed, except that in step (6), 18 mg of selenium and nitrogen co-doped carbon supported molybdenum carbide material was mixed with 2.7 mg of PVDF binder and then added to 100 mg of N-methyl pyrrolidone (NMP) solvent to form a slurry, and the rest was the same as Example 1, to obtain a selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator.

[0155] Example 56:

[0156] The method of Example 1 was followed, except that in step (6), the slurry was coated on the surface of the PP separator, with a thickness of 10 μm, and the rest was the same as Example 1, to obtain a selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator.

[0157] Example 57:

[0158] The method of Example 1 was followed, except that in step (6), the slurry was coated on the surface of the PP separator, with a thickness of 50 μm, and the rest was the same as Example 1, to obtain a selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator.

[0159] Example 58:

[0160] The method of Example 1 was followed, except that in step (6), the slurry was coated on the surface of the PP separator, with a thickness of 100 μm, and the rest was the same as Example 1, to obtain a selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator.

[0161] Example 59:

[0162] The method of Example 1 was followed, except that in step (6), the modified separator was dried at a temperature of 40 °C, and the rest was the same as Example 1, to obtain a selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator.

[0163] Example 60:

[0164] According to the method of Example 1, except that the modified separator in step (6) is dried at a temperature of 50 °C, and the rest are the same as Example 1, a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery separator is obtained.

[0165] Example 61:

[0166] According to the method of Example 1, except that the modified separator in step (6) is dried at a temperature of 70 °C, and the rest are the same as Example 1, a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery separator is obtained.

[0167] Example 62:

[0168] According to the method of Example 1, except that the modified separator in step (6) is dried at a temperature of 80 °C, and the rest are the same as Example 1, a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery separator is obtained.

[0169] Example 63:

[0170] According to the method of Example 1, except that the modified separator in step (6) is dried at a temperature of 90 °C, and the rest are the same as Example 1, a selenium and nitrogen co-doped carbon loaded molybdenum-based lithium-sulfur battery separator is obtained.

[0171] The above content only illustrates the technical idea of the present application, and cannot limit the protection scope of the present application. Any modification made according to the technical idea of the present application on the basis of the technical solution falls within the protection scope of the claims of the present application.

Claims

1. A method for preparing a selenium and nitrogen co-doped carbon supported molybdenum-based lithium-sulfur battery separator, characterized in that, Comprise the following steps: S1: MoO3, polyvinylpyrrolidone and metal zinc salt are dissolved in anhydrous methanol, and a mixed solution is obtained after sufficient stirring; S2: 2-methylimidazole is dissolved in anhydrous methanol, and a clear solution is obtained after sufficient stirring; S3: The S1 mixed solution and the S2 clear solution are mixed and stirred to obtain a precipitate, and the precipitate is washed and dried to obtain a MoO3@ZIF-8 precursor material; S4: The MoO3@ZIF-8 precursor material is annealed to obtain a nitrogen-doped carbon-loaded molybdenum carbide material; S5: The nitrogen-doped carbon-loaded molybdenum carbide material is mixed with selenium powder and heat treated to obtain a selenium and nitrogen co-doped carbon-loaded molybdenum carbide material; S6: The selenium and nitrogen co-doped carbon-loaded molybdenum carbide material is mixed with a PVDF binder, then added to an N-methylpyrrolidone solvent and stirred uniformly to form a slurry, and the slurry is coated on the surface of a commercial polypropylene separator, and dried to obtain a modified battery separator; In step S1, the metal zinc salt is zinc nitrate, zinc chloride or zinc sulfate; the mass ratio of MoO3 to polyvinylpyrrolidone is 1:10 to 10:1; the mass ratio of MoO3 to metal zinc salt is 1:10 to 10:1; the mass ratio of polyvinylpyrrolidone to metal zinc salt is 1:5 to 5:1; the concentration of MoO3 is 0.01 to 0.1 mmol / mL; the concentration of polyvinylpyrrolidone is 0.0001 to 0.001 mmol / mL; the concentration of metal zinc salt is 0.01 to 0.1 mmol / mL; In step S2, the concentration of 2-methylimidazole in methanol is 0.1 to 1 mmol / mL; In step S3, the volume ratio of the S1 mixed solution to the S2 clear solution is 2:1 to 1:2; the stirring time is 20 to 45 min, and the washing is 3 to 5 times with water and ethanol; In step S4, the annealing atmosphere of the MoO3@ZIF-8 precursor material is N2 or Ar / H2 mixed gas, the annealing temperature is 600 to 900 °C, and the annealing time is 1 to 3 h.

2. The method of claim 1, wherein, In step 5, the mass ratio of the nitrogen-doped carbon-loaded molybdenum carbide to selenium powder is 1:10 to 10:

1.

3. The method of claim 1, wherein, In step S5, the heat treatment atmosphere is N2 or Ar / H2 mixed gas, the heat treatment time is 1 to 5 h, and the heat treatment temperature is 300 to 700 °C.

4. The method of claim 1, wherein, In step S6, the selenium and nitrogen co-doped carbon-loaded molybdenum carbide material is 15 to 25 mg, the PVDF binder is 2 to 3 mg, and the N-methylpyrrolidone solvent is 90 to 110 mg. The slurry is coated on the surface of a commercial polypropylene separator, and the thickness is 10 to 100 μm.

5. The method of claim 1, wherein, In step S6, the drying temperature is 40 to 90 °C, and the drying time is 9 to 18 h.

6. The use of the Se and N co-doped carbon supported Mo-based lithium-sulfur battery separator prepared according to any one of claims 1-5, characterized in that, The selenium and nitrogen co-doped carbon-loaded molybdenum-based lithium-sulfur battery separator can be used to make a battery.

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