Hierarchical porous honeycomb microsphere composites assembled from in-situ grown carbon nanosheets of MoS2 nanocrystals and their preparation and application

Abstract

The present invention discloses a hierarchical porous honeycomb microsphere composite material suitable for preparing a negative electrode of a lithium-ion battery, assembled with in-situ grown carbon nanosheets of MoS2 nanocrystals, and its preparation method and application. The mass percentage of MoS2 in the material is 30%-60%, and the MoS2 nanocrystals are embedded in the carbon nanosheets. 2-7 carbon nanosheets are stacked and entangled to form a hollow sphere unit with a diameter of 100-500nm and a spherical hollow hole. Multiple hollow sphere units are densely assembled into a large microsphere, forming a honeycomb sphere structure with a diameter of 2-6μm. The preparation method comprises: adjusting the pH of a suspension of monodisperse polystyrene spheres with a diameter of 100-300nm to 1-3, adding dopamine hydrochloride and mixing, and then adding sodium molybdate. After fully stirring the reaction, the solid is washed and dried, calcined at 400-500℃ in an argon atmosphere, and vapor-phase vulcanized to obtain a hierarchical porous honeycomb microsphere composite material assembled with in-situ grown carbon nanosheets of MoS2 nanocrystals.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion batteries, and in particular to a hierarchical porous honeycomb microsphere composite material assembled by in-situ grown carbon nanosheets of molybdenum disulfide (MoS2) nanocrystals, and a preparation method and application thereof. Background Art

[0002] Over the past few decades, lithium-ion batteries (LIBs) have become the main energy storage system in the field of electric vehicles and portable devices due to their high energy density, low cost, and environmental protection. Electrode materials are the key factors affecting the performance of lithium-ion batteries, especially the negative electrode materials. Due to low theoretical capacity and safety issues, commercial negative electrode graphite can no longer continue to promote the development of high-performance LIBs. Therefore, people are working hard to develop potential alternative materials for LIBs negative electrodes. Among them, MoS2 has a theoretical capacity of up to 670mAh·g -1 However, MoS2 has poor conductivity, is prone to agglomeration, and experiences large volume changes during the lithiation / delithiation process. These issues lead to low specific capacity, unsatisfactory rate performance, and rapid capacity decay. This has severely hampered the application of MoS2.

[0003] To improve the performance of MoS2 lithium-ion batteries, people have conducted various explorations. The invention patent with authorization publication number CN109904408B discloses a composite material of MoS2 nanosheets embedded in a carbon substrate. The invention patent application with application number CN202010887227.8 discloses a lithium-ion battery negative electrode material of nitrogen-doped porous carbon-coated MoS2. The invention patent with authorization publication number CN107681142B discloses a MoS2-coated carbon nanofiber used as a negative electrode material for lithium-ion batteries. For most MoS2-based composite materials, a carbon matrix is usually synthesized first, and then MoS2 is grown on the surface of the carbon matrix through various methods. This reduces the bonding strength between MoS2 and the matrix. Due to the lack of external protection, MoS2 on the outside of the carbon matrix easily falls off during the charge and discharge process. For MoS2, growing on the inner surface of hollow carbon spheres, carbon tubes, and honeycomb carbon spheres is a better strategy. However, it is difficult to grow MoS2 uniformly and firmly on the inner surface of the synthesized carbon matrix through later synthesis methods.

[0004] Shuang Li et al. developed a mesoporous carbon sphere containing highly dispersed molybdenum carbide / molybdenum nitride derived from a metal organic precursor (Adv.Funct.Mater.2019,29,1807419). Its purpose is not for energy storage, but as an electrocatalyst for hydrogen evolution reaction, which makes it possible to use the product normally even if the molybdenum content is very low. The document uses SiO2 nanospheres with a diameter of 20nm as a pore-forming template. Finally, the SiO2 nanospheres need to be etched away with alkali, and the alkali etching will dissolve the molybdenum oxide at the same time. Relatively speaking, the solubility of molybdenum carbide will be slightly lower, so the document needs to be heat treated above 750°C to form molybdenum carbide instead of leaving molybdenum in the form of molybdenum oxide. Despite this, the molybdenum content in the final product of the document is still difficult to exceed 3wt%, which makes the material unusable in the field of energy storage. Summary of the Invention

[0005] In response to the above-mentioned technical problems and the shortcomings in the field, the present invention provides a hierarchical porous honeycomb microsphere composite material assembled by in-situ grown carbon nanosheets of MoS2 nanocrystals (also referred to as MoS2@honeycomb carbon microspheres in the present invention), which has the characteristics of high molybdenum content retention rate, unique structure, excellent performance, simple synthesis process and good energy storage performance.

[0006] A hierarchical porous honeycomb microsphere composite material composed of in-situ grown MoS2 nanocrystals and assembled carbon nanosheets suitable for preparing lithium-ion battery negative electrodes. The MoS2 nanocrystals are embedded in the carbon nanosheets, and 2-7 carbon nanosheets are stacked and entangled to form a hollow sphere unit with a diameter of 100-500nm and spherical hollow pores. Multiple hollow sphere units are densely assembled into a large microsphere, forming a honeycomb sphere structure with a diameter of 2-6μm.

[0007] In the hierarchical porous honeycomb microsphere composite material assembled by in-situ growth of MoS2 nanocrystals and carbon nanosheets, the mass percentage of MoS2 is 30%-60%.

[0008] In one embodiment, the thickness of the carbon nanosheets is 5-50 nm, and the carbon therein is an amorphous structure.

[0009] In one embodiment, the MoS2 nanocrystals are in 2H phase and have a size of 5-50 nm.

[0010] The present invention also provides a method for preparing the hierarchical porous honeycomb microsphere composite material assembled by in-situ growth of MoS2 nanocrystals and carbon nanosheets, comprising the steps of:

[0011] (1) providing a suspension of monodisperse polystyrene (PS) spheres with a diameter of 100-300 nm;

[0012] (2) Adjusting the pH of the monodisperse polystyrene sphere suspension to 1-3, adding dopamine hydrochloride and mixing, and then adding sodium molybdate, stirring the reaction thoroughly, washing, and drying the solid, calcining it at 400-500° C. in an argon atmosphere to obtain molybdenum oxide @ honeycomb carbon microspheres, and vapor-phase vulcanizing it to obtain the hierarchical porous honeycomb microsphere composite material assembled by in-situ growth of MoS2 nanocrystals and carbon nanosheets.

[0013] In the preparation method of the present invention, it is first necessary to control the diameter of the polystyrene balls in the monodisperse polystyrene ball suspension to be between 100 and 300 nm (the specific synthesis method can be a microemulsion polymerization method, etc.). Polystyrene balls with diameters that are too small or too large cannot produce the MoS2@honeycomb carbon microspheres with the specific structure and morphology of the present invention. Secondly, the polymerization reaction of dopamine hydrochloride and sodium molybdate is used to generate Mo-PDA organic / inorganic hybrid nanosheets to wrap the PS balls, and further assemble them into larger composite balls. Then, they are calcined at 400-500°C to first form molybdenum oxide@honeycomb carbon microspheres (the overall structure remains independent after the PS balls are removed and will not collapse), and then vapor-phase vulcanization is performed to obtain MoS2@honeycomb carbon microspheres with target morphology and structural characteristics. If the calcination temperature is too low or too high, it is difficult to form molybdenum oxide. For example, if the temperature is too high, molybdenum carbide is easily formed, and molybdenum carbide cannot be vapor-phase vulcanized to form MoS2, and the target product cannot be obtained. The preparation method of the present invention has almost no molybdenum loss, high molybdenum atom utilization rate, and can improve the specific capacity and cycle performance of MoS2.

[0014] In one embodiment, in step (2), the specific operation of the vapor phase sulfurization includes: placing molybdenum oxide@honeycomb carbon microspheres and sulfur powder in a tube furnace, and then heating them at 400-600° C. under the protection of flowing argon.

[0015] The present invention also provides the use of the hierarchical porous honeycomb microsphere composite material assembled by in-situ growth of MoS2 nanocrystals and carbon nanosheets in the preparation of lithium ion battery negative electrodes.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1) Using PS spheres of a specific size as pore-forming agents and calcining them at a specific temperature, the PS spheres are removed to create pores while completely preserving the Mo within the composite, preventing its loss and preserving it as molybdenum oxide. This provides the material basis for obtaining a high MoS2 content in the final composite. This method is simple, efficient, environmentally friendly, and low-cost.

[0018] 2) PS spheres are polymer spheres that are selective for adsorption materials. Furthermore, the large PS spheres used are more difficult to adsorb than smaller spheres. The successful use of PS spheres of a specific diameter as pore-forming agents for Mo-PDA is innovative.

[0019] 3) Due to the use of PS balls of specific sizes, the growth pattern of Mo-PDA nanosheets is changed, and the Mo-PDA nanosheets are changed from conventional planar growth to growth wrapped around PS balls. 2-7 layers of Mo-PDA nanosheets are stacked and grown wrapped around PS balls. Due to the bending of the sheets, the stacking is not dense, there are abundant pores between the nanosheets, and there are also pores between the wrapped balls. This makes the honeycomb balls after calcination and gas phase sulfurization have micropores and mesopores. Combined with the macropores left after the removal of the PS balls, a hierarchical porous structure with a large pore span, covering micropores, mesopores and macropores is formed. This hierarchical porous structure plays an important role in facilitating the penetration of the electrolyte, improving the contact between the active material and the electrolyte, and buffering the volume change of MoS2. It is one of the important reasons for the high specific capacity and excellent cycle performance of the composite material.

[0020] 4) In the Mo-PDA organic / inorganic hybrid microspheres embedded with PS balls, molybdate ions and polydopamine are combined together, so that the Mo element obtains a highly uniform dispersion effect at the atomic level in the composite material, resulting in the calcined product MoO x Nanocrystals are also highly uniformly dispersed and embedded in carbon nanosheets. MoO x The in-situ conversion to MoS2 occurs because, due to the constraints of the surrounding carbon matrix, MoS2 cannot grow and remains nanocrystalline and highly dispersed, which makes the synthesized MoS2 highly electrochemically active. The MoS2 nanocrystals are tightly bound to the surrounding carbon matrix, which improves the electrical conductivity and structural stability of MoS2. Due to the constraints of the surrounding carbon matrix, the (002) crystal plane of MoS2 cannot fully grow, and MoS2 can only grow and transform in the direction allowed by the environment, thus forming a few-layer MoS2. For MoS2 with fewer layers, the internal atoms are more easily exposed, which has a significant improvement in the physical and chemical properties of MoS2. The combined synergistic effect of these factors significantly improves the specific capacity and cycle performance of MoS2. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a scanning electron microscope (SEM) photograph of the Mo-PDA organic / inorganic hybrid microspheres embedded with PS spheres prepared in Example 1;

[0022] Figure 2 Transmission electron microscopy (TEM) images of Mo-PDA organic / inorganic hybrid microspheres embedded with PS spheres prepared in Example 1;

[0023] Figure 3 MoO prepared in Example 1 x @SEM photos of honeycomb carbon microspheres;

[0024] Figure 4 MoO prepared in Example 1 x@TEM photo of honeycomb carbon microspheres;

[0025] Figure 5 This is the SEM photo of MoS2@ honeycomb carbon microspheres prepared in Example 1;

[0026] Figure 6 TEM image of MoS2@ honeycomb carbon microspheres prepared in Example 1;

[0027] Figure 7 This is a high-resolution transmission electron microscopy (HRTEM) image of MoS2@ honeycomb carbon microspheres prepared in Example 1;

[0028] Figure 8 The X-ray diffraction (XRD) pattern of MoS2@ honeycomb carbon microspheres prepared in Example 1;

[0029] Figure 9 This is the thermogravimetric curve of MoS2@ honeycomb carbon microspheres prepared in Example 1 under air;

[0030] Figure 10 This is the nitrogen adsorption and desorption isotherm of MoS2@ honeycomb carbon microspheres prepared in Example 1;

[0031] Figure 11 This is the TEM photo of the comparative material MoS2@carbon microspheres prepared in Example 1.

[0032] Figure 12 MoS2@ honeycomb carbon microspheres and MoS2@ carbon microspheres prepared in Example 1 were heated to 0.1A·g -1 The cycle performance diagram below. DETAILED DESCRIPTION

[0033] The present invention will be further described below in conjunction with the accompanying drawings and specific examples. It should be understood that these examples are intended to illustrate the present invention and are not intended to limit the scope of the invention. The operating methods in the following examples where no specific conditions are specified are generally performed under conventional conditions or as recommended by the manufacturer.

[0034] The preparation method of MoS2@honeycomb carbon microsphere composite material comprises the following steps:

[0035] (1) 140 ml of deionized water was added to a 500 ml three-necked round-bottom flask and placed in an oil bath at 60°C. 98 μl of oleic acid was then added. The solution was deoxygenated under a nitrogen atmosphere for 30 minutes, and then 0.1-7 ml of styrene was added. The mixed solution was stirred for 1 hour and then further heated to 70°C. Subsequently, 5 ml of an aqueous solution containing 80 mg of K2S2O8 was added to the mixed solution under stirring. The polymerization reaction was continued with stirring for 6 hours under a nitrogen atmosphere. Then, the solution temperature was raised to 80°C for 60 minutes to obtain a monodisperse polystyrene (PS) sphere suspension.

[0036] (2) Take 20 ml of the monodisperse PS sphere suspension prepared in step (1), dilute it with 10 ml of deionized water, and then add 0.1 mol L -1 The pH value of the solution was adjusted to about 2 by adding HCl solution. 0.1 g of dopamine hydrochloride (DA) was dissolved in 10 ml of deionized water and then dropped into the PS ball suspension. After 10 minutes, 0.253 g of Na2MoO4 2H2O was dissolved in 10 ml of deionized water and dropped into the DA-PS ball suspension. After continuous stirring for 40 minutes, the obtained precursor product was washed 3 times with water and ethanol, collected by centrifugation, dried at 80 ° C, and finally calcined at 400-500 ° C in an argon atmosphere for 10 hours with a heating rate of 5 ° C min -1 , and MoO x @Honeycomb carbon microspheres.

[0037] (3) Take the MoO prepared in step (2) x @0.05g of honeycomb carbon microspheres and 0.5g of sulfur powder were placed at both ends of the porcelain boat, placed in a tube furnace, and then heated at 5℃min under the protection of flowing argon. -1 The mixture was heated to 400-600°C at a heating rate of 100°C and kept at that temperature for 12 hours. The mixture was cooled to room temperature to obtain a MoS2@honeycomb carbon microsphere composite material.

[0038] Example 1

[0039] (1) 140 ml of deionized water was added to a 500 ml three-necked round-bottom flask and placed in an oil bath at 60°C. 98 μl of oleic acid was then added. The solution was deoxygenated under a nitrogen atmosphere for 30 minutes, and then 3.48 ml of styrene was added. The mixed solution was stirred for 1 hour and then further heated to 70°C. Subsequently, 5 ml of an aqueous solution containing 80 mg of K2S2O8 was added to the mixed solution under stirring. The polymerization reaction was continued with stirring for 6 hours under a nitrogen atmosphere. Then, the solution temperature was raised to 80°C for 60 minutes to obtain a monodisperse polystyrene (PS) sphere suspension.

[0040] (2) Take 20 ml of the monodisperse PS sphere suspension prepared in step (1), dilute it with 10 ml of deionized water, and then add 0.1 mol L -1 The pH value of the solution was adjusted to about 2 with HCl solution. 0.1 g of dopamine hydrochloride (DA) was dissolved in 10 ml of deionized water and then dropped into the PS ball suspension. After 10 minutes, 0.253 g of Na2MoO4 2H2O was dissolved in 10 ml of deionized water and dropped into the DA-PS ball suspension. After continuous stirring for 40 minutes, the obtained precursor product was washed 3 times with water and ethanol, collected by centrifugation, dried at 80 ° C, and finally calcined at 450 ° C for 10 hours in an argon atmosphere with a heating rate of 5 ° C min -1, and MoO x @Honeycomb carbon microspheres.

[0041] (3) Take the MoO prepared in step (2) x @0.05g of honeycomb carbon microspheres and 0.5g of sulfur powder were placed at both ends of the porcelain boat, placed in a tube furnace, and then heated at 5℃min under the protection of flowing argon. -1 The mixture was heated to 500°C at a heating rate of 1000 ℃ and kept at this temperature for 12 hours. The mixture was cooled to room temperature to obtain a MoS2@honeycomb carbon microsphere composite material.

[0042] The control material MoS2@carbon microspheres were synthesized using the above method without adding PS balls.

[0043] Figure 1 and Figure 2 These are the SEM and TEM photos of Mo-PDA organic / inorganic hybrid microspheres embedded with PS balls. It can be seen that the PS balls are about 200 nm in diameter and are evenly embedded on the surface and inside of the microspheres. Figure 3 It's MoO x @SEM image of honeycomb carbon microspheres. After the PS spheres were removed, uniform, interconnected macropores remained on the microsphere surface. The densely distributed pores formed a honeycomb structure. Figure 4 This TEM image reveals the dense three-dimensional distribution of macropores within the microspheres. The walls of the honeycomb macropores are not dense, but rather formed by several layers of nanosheets stacked on top of each other, twisting and turning, with abundant pores between the nanosheets. The nanosheets are approximately 11 nm thick, while the honeycomb pore walls are approximately 50 nm thick. Figure 5 This is the SEM photo of MoS2@honeycomb carbon microspheres. The honeycomb microsphere structure remains intact after vapor phase vulcanization. Figure 6 This is its TEM photo, from which it can be seen that the walls of the honeycomb macropores have become smoother and more continuous. Figure 7 This is a high-resolution TEM image of MoS2@honeycomb carbon microspheres. Clear crystal grains are visible in the MoS2, indicating good crystallinity. The MoS2 nanocrystals are approximately 10-20 nm in size and are surrounded by amorphous carbon. Figure 8 The XRD patterns of MoS2@honeycomb carbon microspheres show that the diffraction peaks at 32.6°, 39.5°, and 58.3° coincide with the (100), (103), and (110) planes of the 2H phase of MoS2 (JCPDS No. 37-1429). There is no characteristic diffraction peak corresponding to the (002) crystal plane of MoS2. This is because the formation of MoS2 is restricted by the carbon nanosheet matrix. Molybdenum disulfide crystals can only grow in other favorable directions. The absence of the (002) diffraction peak indicates that the number of MoS2 layers is relatively small, indicating that it is a few-layer MoS2. Figure 9 This is the thermogravimetric result of MoS2@honeycomb carbon microspheres in air. The mass content of MoS2 can be calculated to be 43.26wt%. Figure 10The results of nitrogen adsorption and desorption isothermal experiments show a type IV isotherm with an H3 hysteresis loop, indicating that the composite material is rich in mesopores. In addition, in the extremely low range of relative pressure of 0-0.02, the isotherm exhibits a long tail phenomenon. This indicates the presence of micropores in the composite material. Combined with the 200nm macropores left after the PS balls are removed, the composite material contains micropores, mesopores and macropores, forming a hierarchical porous honeycomb structure. The specific surface area is 150.8m 2 g -1 . Figure 11 This is a TEM image of the control material, MoS2@carbon microspheres. The microspheres lack a hierarchical porous honeycomb structure. The nanosheets grow in a planar pattern, overlapping tightly with no bends or holes. This comparison demonstrates that the specially sized PS spheres of our invention indeed alter the growth pattern of the nanosheets.

[0044] The MoS2@ honeycomb carbon microsphere composite material of the present invention is used to make a lithium-ion battery negative electrode: the MoS2@ honeycomb carbon microsphere composite material, acetylene black conductive agent, and PVDF binder are weighed in a mass ratio of 70:15:15. The PVDF is dissolved in an appropriate amount of N-methylpyrrolidone and stirred until completely dissolved. The evenly ground active material and acetylene black are then added to the solution, and stirring is continued to ensure that the slurry is evenly mixed. The slurry is then evenly coated on a circular copper foil (diameter 12 mm), dried in a vacuum oven at 100°C, and finally flattened on a tablet press at a pressure of 10 MPa to produce an electrode sheet.

[0045] In a glove box filled with high-purity argon, the prepared electrode sheet, lithium sheet, and separator were assembled into a CR2025 button-type lithium-ion battery. The electrolyte was an EC / DMC solution containing 1 mol / L LiPF6. The charge-discharge and cycling performance of the lithium-ion battery was tested using a Xinwei battery testing system.

[0046] Figure 12 MoS2@ honeycomb carbon microspheres prepared in Example 1 were heated to 0.1A g -1 The cycling performance of MoS2@honeycomb carbon microspheres shows a slow decrease in discharge capacity. The average discharge capacity after 120 cycles reaches 1334 mAh g -1 The discharge capacity at the 120th cycle was 1199 mAh g -1 Except for the first 7 cycles, the Coulombic efficiency (CE) was higher than 99%, indicating that the MoS2@honeycomb carbon microspheres have excellent electrochemical reversibility. Figure 12 The cycling performance of MoS2@carbon microspheres is also provided. The discharge capacity of MoS2@carbon microspheres is 443-313 mAh g -1 The average discharge capacity of 120 cycles is only 369 mAh g -1It can be found that the average discharge capacity of MoS2@honeycomb carbon microspheres is 3.6 times that of MoS2@carbon microspheres. The huge difference clearly reveals that the hierarchical porous honeycomb microsphere structure plays a very important role in the specific capacity and cycling stability of MoS2.

[0047] The cycling performance of MoS2@honeycomb carbon microsphere composite material is better than that of a nitrogen-doped porous carbon-supported MoS2 nanoflower reported in the invention patent publication number CN112919446A at a current density of 0.1A g -1 The discharge capacity after 100 cycles is about 1014 mAh g -1 , which is superior to the MoS2 / TiO2 / graphene composite material reported in the invention patent with publication number CN112750992A at a current density of 0.1A g -1 The discharge capacity after 100 cycles is about 767 mAh g -1 .

[0048] Example 2

[0049] (1) 140 ml of deionized water was added to a 500 ml three-necked round-bottom flask and placed in an oil bath at 60°C. 98 μl of oleic acid was then added. The solution was deoxygenated under a nitrogen atmosphere for 30 minutes, and then 5.0 ml of styrene was added. The mixed solution was stirred for 1 hour and then further heated to 70°C. Subsequently, 5 ml of an aqueous solution containing 80 mg of K2S2O8 was added to the mixed solution under stirring. The polymerization reaction was continued with stirring for 6 hours under a nitrogen atmosphere. Then, the solution temperature was raised to 80°C for 60 minutes to obtain a monodisperse polystyrene (PS) sphere suspension.

[0050] The subsequent steps are the same as those in Example 1.

[0051] The structure of the product MoS2@honeycomb carbon microsphere composite material is similar to that of Example 1, the main difference being that the diameter of the honeycomb macropores is increased to about 270 nm.

[0052] Example 3

[0053] (1) 140 ml of deionized water was added to a 500 ml three-necked round-bottom flask and placed in an oil bath at 60°C. 98 μl of oleic acid was then added. The solution was deoxygenated under a nitrogen atmosphere for 30 minutes, and then 2.0 ml of styrene was added. The mixed solution was stirred for 1 hour and then further heated to 70°C. Subsequently, 5 ml of an aqueous solution containing 80 mg of K2S2O8 was added to the mixed solution under stirring. The polymerization reaction was continued with stirring for 6 hours under a nitrogen atmosphere. Then, the solution temperature was raised to 80°C for 60 minutes to obtain a monodisperse polystyrene (PS) sphere suspension.

[0054] The subsequent process is the same as that in Example 1.

[0055] The structure of the product MoS2@honeycomb carbon microsphere composite material is similar to that of Example 1, the main difference being that the diameter of the honeycomb macropores is reduced to about 110 nm.

[0056] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A method for preparing a hierarchical porous honeycomb microsphere composite material assembled by in-situ growth of MoS2 nanocrystals and carbon nanosheets suitable for preparing a negative electrode of a lithium ion battery, characterized in that: The hierarchical porous honeycomb microsphere composite material is assembled by in-situ growth of MoS2 nanocrystals and carbon nanosheets, wherein MoS2 nanocrystals are embedded in the carbon nanosheets, 2-7 carbon nanosheets are stacked and entangled to form a hollow sphere unit with a diameter of 100-500 nm and spherical hollow pores, and multiple hollow sphere units are densely assembled into a large microsphere, forming a honeycomb sphere structure with a diameter of 2-6 μm; In the hierarchical porous honeycomb microsphere composite material assembled by in-situ growth of MoS2 nanocrystals and carbon nanosheets, the mass percentage of MoS2 is 30%-60%; The preparation method comprises the steps of: (1) Providing a suspension of monodisperse polystyrene spheres with a diameter of 100-300 nm; (2) adjusting the pH of the monodisperse polystyrene sphere suspension to 1-3, adding dopamine hydrochloride and mixing, and then adding sodium molybdate, stirring the reaction thoroughly, washing and drying the solid, and calcining it at 400-500°C in an argon atmosphere to obtain molybdenum oxide @ honeycomb carbon microspheres, and vapor-phase sulfurization to obtain the MoS2 nanocrystal in situ grown carbon nanosheets assembled hierarchical porous honeycomb microsphere composite material; The specific operation of the gas phase vulcanization includes: placing molybdenum oxide@honeycomb carbon microspheres and sulfur powder in a tube furnace, and then heating them at 400-600° C. under the protection of flowing argon gas.

2. The preparation method according to claim 1, characterized in that The thickness of the carbon nanosheet is 5-50 nm, and the carbon therein is an amorphous structure.

3. The preparation method according to claim 1, characterized in that The MoS2 nanocrystals are in 2H phase and have a size of 5-50 nm.

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