C / mo s2-fe mo2s4-mo c composite material and application thereof in lithium-air battery

Abstract

The application discloses a C / MoS2-FeMo2S4-MoC composite material and application thereof in a lithium air battery, and a preparation method of the composite material is as follows: molybdenum salt, thiourea and glucose are dissolved in deionized water, C / MoS2 material is prepared through a hydrothermal method, then dopamine is coated on the surface of the C / MoS2 material, iron salt is adsorbed on the surface of the dopamine, and C / MoS2@Fe-PDA precursors are obtained after drying; and the C / MoS2-FeMo2S4-MoC composite material is obtained by high-temperature calcination under the protection of argon. The preparation process is simple, and the cost is low; the obtained composite material has a low overvoltage, a high discharge specific capacity and excellent cycle performance when used as a lithium air battery positive electrode catalyst, and has a good research prospect.

Description

TECHNICAL FIELD

[0001] The application relates to the field of battery material preparation, in particular to a C / MoS2-FeMo2S4-MoC composite material and a preparation method thereof and application of the composite material in a lithium-air battery. BACKGROUND

[0002] With the continuous development of electric vehicles and new energy technologies, people's demand for energy storage technologies is increasing. Lithium-air batteries are a battery technology with extremely high theoretical energy density, and the theoretical specific capacity is as high as 3828 mAh / g, which makes them show important application prospects in the fields of electric vehicles and smart grids [1] . However, lithium-air batteries are still far from commercial application, and many problems need to be solved, such as large overpotential, poor cycle stability, low cycle efficiency, etc [2] . The main reason for these problems is the slow kinetics of the oxygen reduction reaction and the oxygen evolution reaction on the positive electrode of the lithium-air battery, so designing and preparing a reasonable ORR / OER bifunctional catalyst is crucial for the development of lithium-air batteries. Transition metal sulfides are gradually valued by researchers as excellent electrocatalysts.

[0003] Molybdenum disulfide is a layered transition metal chalcogenide, which is theoretically and experimentally proved to have high activity for lithium-air batteries. The monolayer of MoS2 has a sandwich structure, with two layers of sulfur sandwiching one layer of molybdenum, and multiple layers of molybdenum disulfide are connected by van der Waals forces, which can provide abundant reaction sites for the oxidation-reduction reaction [3] . In addition, the edge Mo sites of molybdenum disulfide show stronger adsorption of O2, Li2O2 and other intermediates, resulting in high electrochemical catalytic activity for reversible Li2O2 conversion [4] . However, molybdenum disulfide is a semiconductor material with low conductivity and serious agglomeration. To solve these problems, some researchers have adopted carbon materials and molybdenum disulfide for compounding to improve the conductivity of molybdenum disulfide, and the introduction of carbon can inhibit the stacking of molybdenum disulfide nanosheets [5] . However, the simple compounding of carbon and molybdenum disulfide is not ideal for the catalytic effect of ORR / OER. Therefore, other active metal ions are needed to further improve the catalytic effect of ORR / OER. Iron is a cheap transition metal, and studies have shown that it has ideal catalytic effect on ORR / OER [6] . The carbon-based iron-molybdenum bimetallic catalyst exhibits better catalytic performance for oxygen evolution and reduction reactions.

[0004] REFERENCES

[0005] [1]Wang N, Lin H P, Fang X R, et al. Research progress of lithium-air battery cathode catalysts[J]. Battery Bimonthly, 2017, 21(04): 35-43.

[0006] [2]Guo X H, Huang S T, Zhao N, et al. Rapid development of secondary lithium-air battery and key scientific problems to be solved[J]. Journal of Inorganic Materials, 2014, 29(2): 113-123.

[0007] [3]Tang W., Chen Z., Tian B., Lee H.-W., Zhao X., Fan X. et al. In situ observation and electrochemical study of encapsulated sulfur nanoparticles by MoS2 flakes[J]. Journal of the American Chemical Society, 2017, 139(29): 10133-10141.

[0008] [4]Sun G., Li F., Wu T., Cong L., Sun L., Yang G. et al. O2 adsorption associated with sulfur vacancies on MoS2 microspheres[J]. Inorganic chemistry, 2019, 58(3): 2169-2176.

[0009] [5]Wu J, Lu Z, Li K, et al. Hierarchical MoS2 / carbon microspheres as long-life and high-rate anodes for sodium-ion batteries[J]. Journal of Materials Chemistry A, 2018, 6(14): 5668-5677.

[0010] [6]Chen J, Huang B, Cao R, et al. Steering local electronic configuration of Fe-N-C-based coupling catalysts via ligand engineering for efficient oxygen electroreduction[J]. Advanced Functional Materials, 2023, 33(4): 2209315. SUMMARY

[0011] In view of the deficiencies of the existing lithium-air battery positive electrode catalyst materials, the purpose of the present application is to provide a C / MoS2-FeMo2S4-MoC composite material which can be prepared by a simple process and has good electrical conductivity and catalytic performance, and to apply it to lithium-air batteries to improve their performance.

[0012] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0013] The present application first discloses a preparation method of C / MoS2-FeMo2S4-MoC composite material, which is characterized by: dissolving molybdenum salt, thiourea and glucose in deionized water and mixing uniformly, preparing C / MoS2 material by hydrothermal method; then coating dopamine on the surface of C / MoS2 material and adsorbing iron salt on the surface of dopamine, drying to obtain C / MoS2@Fe-PDA material; finally, calcining C / MoS2@Fe-PDA material under inert atmosphere at high temperature to obtain C / MoS2-FeMo2S4-MoC composite material. Specifically, it includes the following steps:

[0014] Step one, dissolve molybdenum salt, thiourea and glucose in deionized water, ultrasonically mix uniformly, then transfer to the reaction kettle, react at 180-200℃ for 20-24h, filter the obtained product, dry to obtain C / MoS2 material.

[0015] Step two, dissolve the C / MoS2 material obtained in step one in Tris-Hcl buffer solution, ultrasonically mix uniformly, then add hydrochloric acid dopamine, stir for 12-24h, centrifuge and wash the obtained product.

[0016] Step three, dissolve iron salt and dicyandiamide in deionized water, then add the material obtained in step two, stir for 3-6h, dry to obtain C / MoS2@Fe-PDA material;

[0017] Step four, the C / MoS2@Fe-PDA material obtained in step three is placed in a tube furnace, and high-temperature calcination is carried out under an inert atmosphere, to obtain a C / MoS2-FeMo2S4-MoC composite material.

[0018] Further, in step one, the molybdenum salt is sodium molybdate, molybdenum chloride, molybdenum trioxide or ammonium molybdate.

[0019] Further, in step one, the use amount ratio of the molybdenum salt, thiourea, glucose and deionized water is 1.6-3.2 g: 3.75-7.5 g: 2.8-5.6 g: 18.25-37.5 mL.

[0020] Further, in step two, the use amount ratio of the C / MoS2 material, Tris-Hcl buffer solution and dopamine hydrochloride is 0.1-0.2 g: 20-40 mL: 0.02-0.04 g.

[0021] Further, in step three, the iron salt is ferric chloride, ferric nitrate, ferric sulfate, iron acetylacetone or phthalocyanine iron.

[0022] Further, in step three, the use amount ratio of the iron salt, dicyandiamide and the material obtained in step two is 0.03-0.06 g: 0.2-0.3 g: 0.1 g.

[0023] Further, in step four: the inert atmosphere is nitrogen or argon; the temperature of the high-temperature calcination is 700-900 DEG C, and the calcination time is 2-4 h.

[0024] The C / MoS2-FeMo2S4-MoC composite material prepared by the preparation method has ORR and OER dual-function catalytic activity and can be used as a metal-air battery positive electrode catalyst material.

[0025] Compared with the prior art, the beneficial effects of the present application are reflected in:

[0026] 1. The C / MoS2-FeMo2S4-MoC provided by the present application is prepared by coating dopamine adsorbed with an iron salt on the surface of C / MoS2, and then high-temperature calcination and compounding. At high temperature, a part of MoS2 is iron sulfide, and a bimetallic sulfide FeMo2S4 is formed. In addition, dopamine is carbonized at high temperature and reacts with a part of molybdenum to generate MoC. The composite material has a large specific surface area, provides more catalytically active sites, and therefore has excellent catalytic performance when used as a lithium-air battery positive electrode catalyst.

[0027] 2. In the C / MoS2-FeMo2S4-MoC composite material of the present application, the MoS2 interlayer is filled with porous carbon, which inhibits the stacking of MoS2, and in addition, the porous wrinkled FeMo2S4 semi-encapsulates the C / MoS2, which not only inhibits the volume expansion of MoS2, but also further increases the specific surface area of the composite material.

[0028] 3. The C / MoS2-FeMo2S4-MoC composite material of the present application has good oxygen reduction (ORR) and oxygen evolution (OER) electrocatalytic activity in alkaline electrolyte, has potential application value in the field of energy conversion and storage, and can be used for preparing metal-air batteries with high energy density and good stability.

[0029] 4. The composite material provided by the present application is applied to lithium-air batteries, and results show that, under high-purity oxygen conditions, deep battery performance tests (2.0-4.5V) are carried out, the first discharge specific capacity is 19200mAh / g, and the battery can be stably operated for 202 cycles at a current density of 500mA / g, and the overvoltage is maintained at about 1.08V, and the performance is excellent.

[0030] 5. The preparation process of the present application is simple and low in cost. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 XRD pattern of the sample obtained in Example 1.

[0032] Figure 2 Raman pattern of the sample obtained in Example 1.

[0033] Figure 3 SEM pattern of the sample obtained in Example 1.

[0034] Figure 4 XPS pattern of the sample obtained in Example 1.

[0035] Figure 5 First charge-discharge performance diagram of the lithium-air battery assembled by the sample obtained in Example 1.

[0036] Figure 6 Cycle performance diagram of the lithium-air battery assembled by the sample obtained in Example 1.

[0037] Figure 7 Overpotential diagram of the lithium-air battery assembled by the sample obtained in Example 1.

[0038] Figure 8 ORR performance test diagram of the samples obtained in Examples 1-5, a-e represent the samples obtained in Examples 1-5 in turn. DETAILED DESCRIPTION

[0039] The following will be described in detail the embodiments of the present application, the embodiments are implemented on the premise of the technical solutions of the present application, and detailed implementation manners and specific operation processes are given, but the protection scope of the present application is not limited to the following embodiments.

[0040] Embodiment 1

[0041] The C / MoS2-FeMo2S4-MoC composite material is prepared according to the following steps:

[0042] Step one, 1.6076g of ammonium molybdate tetrahydrate, 3.75g of thiourea and 2.813g of glucose are dissolved in 37.5mL of deionized water, and then transferred into a reaction kettle after ultrasonic mixing, and reacted at 180℃ for 24h. The obtained product is extracted by suction filtration and dried to obtain a C / MoS2 material.

[0043] Step two, 0.1g of the C / MoS2 material obtained in step one is dissolved in 20mL of Tris-Hcl buffer solution with pH=8.5, and then 0.02g of dopamine hydrochloride is added after ultrasonic mixing, and stirred for 14h. The obtained product is centrifuged and washed.

[0044] Step three, 0.03g of iron chloride hexahydrate and 0.25g of dicyandiamide are dissolved in 10mL of deionized water, and then 0.1g of the material obtained in step two is added, stirred for 4h, and dried to obtain a C / MoS2@Fe-PDA material as a precursor.

[0045] Step four, the C / MoS2@Fe-PDA material obtained in step three is placed in a tube furnace and calcined at 800℃ for 2h under an argon atmosphere to obtain a C / MoS2-FeMo2S4-MoC-1 composite material.

[0046] Embodiment 2

[0047] The composite material is prepared according to the same method as in Embodiment 1, and the only difference is that the dosage of iron chloride hexahydrate in step three is changed to 0.04g, and the obtained product is named as C / MoS2-FeMo2S4-MoC-2.

[0048] Embodiment 3

[0049] The composite material is prepared according to the same method as in Embodiment 1, and the only difference is that the dosage of iron chloride hexahydrate in step three is changed to 0.05g, and the obtained product is named as C / MoS2-FeMo2S4-MoC-3.

[0050] Embodiment 4

[0051] This example was prepared in the same way as example 1, except that the amount of ferric chloride hexahydrate in step three was changed to 0.06 g. The product was named C / MoS2-FeMo2S4-MoC-4.

[0052] Example 5

[0053] This example was prepared in the same way as example 1, except that steps two and three were not performed, and the C / MoS2 material prepared in step one was calcined at 800 °C for 2 h under argon atmosphere.

[0054] Figure 1 The XRD pattern of the sample obtained in example 1 is shown in Figure 1. The peaks at 13.3°, 33.5° and 58.5° are characteristic diffraction peaks of MoS2(PDF # 37-1492), corresponding to (002), (100) and (110) crystal planes. The diffraction peaks at 14.9°, 17.16°, 34.6°, 42.3°, 43.4°, 44.4° are characteristic diffraction peaks of FeMo2S4(PDF # 71-0379). The diffraction peaks at 31.8°, 35.8°, 48.7°, 64.2° are characteristic diffraction peaks of MoC(PDF # 65-6664). This proves that MoS2, FeMo2S4 and MoC are successfully composited.

[0055] Figure 2 The Raman spectrum of the sample obtained in example 1 is shown in Figure 2. The D peak and G peak of the graphitic carbon material appear at 1350 and 1580 cm -1 respectively. The E -1 and A 1 characteristic peaks of MoS2appear at ~ 400 cm 2g 1g

[0056] Figure 3 The SEM image of the sample obtained in example 1 is shown in Figure 3. It can be seen that FeMo2S4is coated on the surface of the C / MoS2microspheres, and MoC particles are distributed on the surface.

[0057] Figure 4 The X-ray photoelectron spectroscopy (XPS) spectrum of the sample obtained in example 1 is shown in Figure 4. It can be seen that the obtained material successfully composites MoS2, FeMo2S4 and MoC.

[0058] ​The sample obtained in Example 1 was used as a positive electrode catalyst material for a lithium-air battery, and lithium pieces were assembled into a button lithium-air battery in the following manner: a slurry containing 60% KB, 30% catalyst material, and 10% PVDF was added to a carbon paper current collector. Then, the slurry was dried in a vacuum drying box at 60°C for 12 h. The net mass of the dried catalyst on the carbon paper was about 0.3-0.5 mg. Lithium foil was used as an anode, a glass fiber separator was laid flat, 110 μL of 1 M LiTFSI / TEGDME electrolyte was added dropwise, the carbon paper with the catalyst was added, and a foam nickel was used as a filler to cover the cathode instrument. The battery assembly was completed in an argon-filled glove box.

[0059] Figure 5 The first charge-discharge performance graph of the lithium-air battery assembled for the sample obtained in Example 1 shows that the specific capacity of the first discharge reached 19200 mAh g -1 at a constant current discharge density of 100 mA g -1 .

[0060] Figure 6 The cycle performance graph of the lithium-air battery assembled for the sample obtained in Example 1 shows that the capacity decayed after 202 cycles at a constant current discharge density of 500 mA g -1 , indicating good cycle stability.

[0061] Figure 7 The overvoltage graph of the lithium-air battery assembled for the sample obtained in Example 1 shows that the overvoltage was about 1.08 V at a constant current discharge density of 100 mA g -1 .

[0062] Figure 8 The ORR performance test graph of the materials prepared in Examples 1-5 shows that the sample obtained in Example 1 reached the highest half-wave potential and the highest limiting current density during testing, and had the best catalytic effect.

[0063] The above only describes preferred embodiments of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a C / MoS2-FeMo2S4-MoC composite material, characterized in that: The molybdenum salt, thiourea and glucose are dissolved in deionized water and uniformly mixed, and a C / MoS2 material is prepared by a hydrothermal method; then dopamine is coated on the surface of the C / MoS2 material, and an iron salt is adsorbed on the surface of the dopamine, and the C / MoS2@Fe-PDA material is dried to obtain; finally, the C / MoS2@Fe-PDA material is calcined at high temperature in an inert atmosphere to obtain the C / MoS2-FeMo2S4-MoC composite material; the specific steps include the following: Step one, the molybdenum salt, thiourea and glucose are dissolved in deionized water, ultrasonically mixed and uniformly mixed, and then transferred to a reaction kettle, reacted at 180-200°C for 20-24h, and the obtained product is filtered and dried to obtain a C / MoS2 material; Step two, the C / MoS2 material obtained in step one is dissolved in a Tris-Hcl buffer solution, ultrasonically mixed and uniformly mixed, and then hydrochloric acid dopamine is added, stirred for 12-24h, and the obtained product is centrifuged and washed; Step three, the iron salt and dicyandiamide are dissolved in deionized water, and then the material obtained in step two is added, stirred for 3-6h, and dried to obtain a C / MoS2@Fe-PDA material; Step four, the C / MoS2@Fe-PDA material obtained in step three is placed in a tube furnace and calcined at high temperature in an inert atmosphere to obtain a C / MoS2-FeMo2S4-MoC composite material.

2. The method for preparing the C / MoS2-FeMo2S4-MoC composite material according to claim 1, characterized in that: The molybdenum salt is sodium molybdate, molybdenum chloride, molybdenum trioxide or ammonium molybdate.

3. The method for preparing the C / MoS2-FeMo2S4-MoC composite material according to claim 1, characterized in that: In step one, the amount ratio of the molybdenum salt, thiourea, glucose and deionized water is 1.6-3.2g:3.75-7.5g:2.8-5.6g:18.75-37.5mL.

4. The method for preparing the C / MoS2-FeMo2S4-MoC composite material according to claim 1, characterized in that: In step two, the amount ratio of the C / MoS2 material, Tris-Hcl buffer solution and hydrochloric acid dopamine is 0.1-0.2g:20-40mL:0.02-0.04g.

5. The method for preparing the C / MoS2-FeMo2S4-MoC composite material according to claim 1, characterized in that: In step three, the iron salt is ferric chloride, ferric nitrate, ferric sulfate, iron acetylacetate or phthalocyanine iron.

6. The method for preparing the C / MoS2-FeMo2S4-MoC composite material according to claim 1, characterized in that: In step three, the amount ratio of the iron salt, dicyandiamide and the material obtained in step two is 0.03-0.06g:0.2-0.3g:0.1g.

7. The method for preparing the C / MoS2-FeMo2S4-MoC composite material according to claim 1, characterized in that: In step four, the inert atmosphere is nitrogen or argon.

8. The method for preparing the C / MoS2-FeMo2S4-MoC composite material according to claim 1, characterized in that: In step four, the temperature of the high-temperature calcination is 700-900°C, and the calcination time is 2-4h.

9. A C / MoS2-FeMo2S4-MoC composite material prepared by the preparation method of any one of claims 1-8.

10. The application of the C / MoS2-FeMo2S4-MoC composite material of claim 9 in a lithium-air battery.

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