Carbon-coated exfoliated metal sulfide composite graphite nanosheet battery negative electrode material and preparation method thereof

Abstract

The application provides a carbon-coated exfoliated metal sulfide composite graphite nanosheet battery negative material and a preparation method thereof. The method mainly uses flaky graphite and layered metal sulfide as raw materials, resin as a grinding and exfoliating medium and a catalytic carbon source, and nitrate as a catalyst. The method obtains a nanoscale layered flaky graphite with increased interlayer spacing, a metal sulfide and a resin mixture through in-situ exfoliation by a three-roll grinding machine. The mixture is cleaned by using anhydrous ethanol. The content of the resin is controlled by controlling the cleaning times. The powder mixture is obtained by ultrasonic treatment, centrifugation, mixing of the nitrate and freeze-drying. The carbon nanotube amorphous carbon-coated nanoscale metal sulfide composite graphite nanosheet is formed by heat treatment. The prepared composite layered material has the characteristics of rich multi-dimensional carbon structure coating, adjustable thickness, more uniform thickness, more active sites, defects and the like, and can meet the demand of lithium / sodium / potassium battery negative material energy storage.

Description

Technical Field

[0001] This invention relates to a carbon-coated and exfoliated metal sulfide composite graphite nanosheet battery anode material and its preparation method, belonging to the field of battery energy storage technology. Background Technology

[0002] In recent years, the demand for energy storage equipment has increased significantly due to the rise of new electronic products, the development of new energy vehicles, and the proposal of large-scale energy storage networks. Faced with this situation, there is an urgent need for high-capacity, high-stability energy storage equipment to meet market demands. Emerging sodium and potassium batteries have very high energy densities, but lack suitable anode materials with good stability and high specific capacity, while traditional anode materials are no longer applicable.

[0003] Anode materials are currently the most critical link in the battery industry. In terms of cost proportion, anode materials account for 25%-28% of the total cost of lithium-ion batteries. Compared to cathode materials, research on anode materials is still in its early stages. Anode materials are mainly divided into two categories: carbon materials and non-carbon materials. Carbon materials refer to carbon-based systems, mainly including graphite anode materials (natural graphite, artificial graphite, composite graphite, and mesophase carbon microspheres), graphene anode materials, and disordered carbon anode materials (hard carbon, soft carbon). Non-carbon materials mainly include silicon-based anode materials (silicon-oxygen anode materials, silicon-carbon anode materials, and silicon-based alloy anode materials), lithium titanate anode materials, and other non-carbon anode materials.

[0004] While carbon-based anode materials are technically mature and cost-effective, they suffer from low lithium intercalation potentials, leading to lithium deposition and safety concerns when used as lithium-ion battery anodes. They also exhibit low specific capacity in other battery types. Graphene, a novel carbon material, offers advantages such as high specific capacity and good cycle performance as a nanoscale material, but it is prone to accumulation during cycling and has a relatively low specific capacity at high current. Metal oxides and metal sulfides possess high potentials and high specific capacities, but their volume expands during ion insertion and extraction, resulting in poor battery cycle stability and voltage hysteresis.

[0005] Currently, metal sulfides have attracted considerable attention as anode materials. Metal sulfides possess abundant natural reserves, simple synthesis methods, and diverse possible compositions, valence states, crystal structures, and morphologies, resulting in excellent electrochemical performance. Metal sulfides exhibit excellent redox properties, leading to higher specific capacity than graphite anode materials. However, this excellent redox reaction also results in poor cycle stability and low rate capability when used as anode materials. To improve the stability of metal sulfides, carbon coating is currently the most commonly used modification method. Compared to metal-based coating, carbon coating is easier to implement.

[0006] Carbon coating involves introducing highly conductive carbon materials onto the surface of the anode material to construct a conductive network. This not only improves the material's electronic conductivity and specific capacity but also reduces its particle size. Carbon coating protects the active material from oxidation in air, reducing polarization and oxidation reactions during the later stages of charging. Furthermore, carbon coating increases the material's structural stability, enhances electronic conductivity, and reduces agglomeration and dispersion.

[0007] Carbon nanotubes (CNTs) have been extensively studied as novel active materials and structural additives due to their excellent mechanical, optical, and electrochemical properties. The p-electrons of carbon atoms in CNTs form extensive delocalized π bonds, resulting in significant conjugation effects and thus good electrical properties. CNTs possess excellent electrical conductivity and a large specific surface area, making them suitable for direct application in battery technology. Their unique tubular structure and intertwined network structure can accelerate ion transport rates, and CNTs themselves possess a certain electrical capacity.

[0008] Amorphous carbon, a novel carbon material developed in the early 1970s, is characterized by its impermeability, high chemical resistance, good thermal conductivity, abrasion resistance, high purity, non-contamination, and good biocompatibility. Consequently, it is increasingly used in electrochemical analysis, semiconductor industry, metallurgical industry, chemical industry, and medical research. It is an amorphous carbon composed entirely of sp2 hybridized atoms, possessing a graphite-like or fullerene-like structure. It exhibits excellent airtightness and electrical conductivity, a low coefficient of thermal expansion, hardness, ease of polishing to a mirror finish, chemical inertness, and a high hydrogen overpotential, making it suitable as a working electrode material for electrochemical and electroanalytical applications.

[0009] While carbon coating is a common method for improving battery performance, the approaches differ between amorphous carbon, carbon nanotube-coated metal sulfides, and micro / nano graphite flake composites. Common methods for coating metal sulfides involve first generating the sulfides through complex reactions, then mixing them with carbon source materials such as polymers (PVP, dopamine, sugars) and heat-treating them. However, these methods are complex, requiring the sulfide to be generated automatically, and the carbon source used for coating is subject to pH requirements. Furthermore, the coating thickness is uncontrollable when using certain carbon sources.

[0010] In view of this, it is indeed necessary to propose a carbon-coated and exfoliated metal sulfide composite graphite nanosheet battery anode material and its preparation method to solve the above problems. Summary of the Invention

[0011] The purpose of this invention is to provide a carbon-coated and exfoliated metal sulfide composite graphite nanosheet battery anode material and its preparation method, which can improve the energy storage performance of battery anode materials.

[0012] To achieve the above objectives, this invention provides a method for preparing a carbon-coated, exfoliated metal sulfide composite graphite nanosheet battery anode material, mainly comprising the following steps:

[0013] Step 1: Mix layered flake graphite and layered metal sulfide evenly, then add the mixture to the resin and stir in a water bath at 35-70℃ for 10-30 minutes to obtain mixture A;

[0014] Step 2: The mixture A obtained in Step 1 is peeled off by a three-roll differential mill. After repeated peeling, the mixture B, which is a composite of layered metal sulfide nanosheets and resin, is collected from the discharge roller.

[0015] Step 3: Add 50-200 vol% alcohol to the mixture B of graphite nanosheets and resin obtained by exfoliation of layered metal sulfide nanosheets, stir and sonicate for 10 min, put it into a centrifuge tube for centrifugation and remove impurities, repeat step 3 and continue to wash with alcohol, and finally centrifuge to obtain substance C.

[0016] Step 4: Using the impurity liquid removed by centrifugation after the last alcohol cleaning of the resin in Step 3 as a solvent, measure an amount of the impurity liquid with the same volume as substance C obtained by centrifugation, dissolve 0.1-1 wt% of nitrate raw material in it, mix it with substance C and stir for 1-10 min, then dry to remove the alcohol to form mixture D.

[0017] Step 5: Place mixture D in a freeze dryer and freeze dry it under vacuum at -50 to -30°C to obtain mixture E that maintains a sheet-like structure;

[0018] Step 6: Place the freeze-dried mixture E in a tube furnace and heat-treat it under an argon atmosphere, from room temperature at a rate of 1-5°C / min. -1 The temperature is increased to 500-900℃, held for 1-5 hours, and then allowed to cool naturally to room temperature to obtain carbon-coated and exfoliated metal sulfide composite graphite nanosheet battery anode material.

[0019] As a further improvement of the present invention, the chemical formula of the layered metal sulfide is MS2, wherein M is one of Mo, W, V or Ti.

[0020] As a further improvement of the present invention, the layered flake graphite and the layered metal sulfide are used as raw materials, the resin is used as a grinding medium and a coated carbon raw material, and the nitrate is used as a catalyst, wherein the layered flake graphite accounts for 10-15 wt%, the layered metal sulfide accounts for 0.5-5 wt%, the resin accounts for 75-88 wt%, and the nitrate accounts for 0.1-1 wt%.

[0021] As a further improvement of the present invention, the resin is one of phenolic resin, epoxy resin or polyethylene resin, and the nitrate is at least one of nickel nitrate, ferric nitrate or cobalt nitrate.

[0022] As a further improvement of the present invention, in step 2, the number of cyclic peelings is 8-15 times, and in step 3, the alcohol cleaning is repeated 3-6 times.

[0023] As a further improvement of the present invention, the three-roll differential grinding mill includes a discharge roller N1, a center roller N2 and a feed roller N3, wherein the rotational speed ratio of the feed roller N3, the center roller N2 and the discharge roller N1 is 1:3:9, and during the cyclic peeling process, the gap between the center roller N2 and the feed roller N3 is always greater than twice the gap between the discharge roller N1 and the center roller N2.

[0024] As a further improvement of the present invention, during the first to fourth cycles of peeling, the gap between the center roller N2 and the feed roller N3, as well as the gap between the discharge roller N1 and the center roller N2, are all between 20 and 200 μm.

[0025] As a further improvement of the present invention, during the 5th to 8th cyclic peeling, the gap between the center roller N2 and the feed roller N3, as well as the gap between the discharge roller N1 and the center roller N2, are all between 5 and 20 μm.

[0026] As a further improvement of the present invention, after the 9th cyclic peeling, the gap between the center roller N2 and the feed roller N3 and the gap between the discharge roller N1 and the center roller N2 are both between 0.5-5μm.

[0027] To achieve the above objectives, the present invention provides a carbon-coated exfoliated metal sulfide composite graphite nanosheet battery anode material, which is prepared by the method described above for preparing carbon-coated exfoliated metal sulfide composite graphite nanosheet battery anode material.

[0028] The beneficial effects of this invention are: the composite layered material prepared by this invention has rich multidimensional carbon structure coating, adjustable thickness, more uniform thickness, more active sites and defects in the edge state, etc., which can meet the energy storage requirements of lithium / sodium / potassium battery anode materials. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to specific embodiments.

[0030] It should be noted that, in order to avoid obscuring the present invention with unnecessary details, other details that are not closely related to the present invention have been omitted from the structure and / or processing steps that are closely related to the present invention.

[0031] Additionally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0032] This invention discloses a carbon-coated exfoliated metal sulfide composite graphite nanosheet battery anode material, mainly using layered flake graphite and layered metal sulfides as raw materials, resin as the grinding medium and coating carbon raw material, and nitrate as a catalyst. The layered flake graphite accounts for 10-15 wt%, the layered metal sulfides for 0.5-5 wt%, the resin for 75-88 wt%, and the nitrate for 0.1-1 wt%. The preparation method of the carbon-coated exfoliated metal sulfide composite graphite nanosheet battery anode material mainly includes the following steps:

[0033] Step 1: Mix layered flake graphite and layered metal sulfide evenly, then add the mixture to the resin and stir in a water bath at 35-70℃ for 10-30 minutes to obtain mixture A;

[0034] Step 2: The mixture A obtained in Step 1 is peeled off by a three-roll differential mill. After repeated peeling, the mixture B, which is a composite of layered metal sulfide nanosheets and resin, is collected from the discharge roller.

[0035] Step 3: Add 50-200 vol% alcohol to the mixture B of graphite nanosheets and resin obtained by exfoliation of layered metal sulfide nanosheets, stir and sonicate for 10 min, put it into a centrifuge tube for centrifugation and remove impurities, repeat step 3 and continue to wash with alcohol, and finally centrifuge to obtain substance C.

[0036] Step 4: Using the impurity liquid removed by centrifugation after the last alcohol cleaning of the resin in Step 3 as a solvent, measure an amount of the impurity liquid with the same volume as substance C obtained by centrifugation, dissolve 0.1-1 wt% of nitrate raw material in it, mix it with substance C and stir for 1-10 min, then dry to remove the alcohol to form mixture D.

[0037] Step 5: Place mixture D in a freeze dryer and freeze dry it under vacuum at -50 to -30°C to obtain mixture E that maintains a sheet-like structure;

[0038] Step 6: Place the freeze-dried mixture E in a tube furnace and heat-treat it under an argon atmosphere, from room temperature at a rate of 1-5°C / min. -1 The temperature is increased to 500-900℃, held for 1-5 hours, and then allowed to cool naturally to room temperature to obtain carbon-coated and exfoliated metal sulfide composite graphite nanosheet battery anode material.

[0039] Steps 1 through 6 will be described in detail below.

[0040] In step 1, the chemical formula of the layered metal sulfide is MS2, where M is one of Mo, W, V, or Ti, and the length and width of the layered metal sulfide are 20-500 μm, and the thickness is 1-40 μm; the length and width of the layered flake graphite are 20-500 μm, and the thickness is 5-50 μm. The resin is one of phenolic resin, epoxy resin, or polyethylene resin.

[0041] In step 2, the number of cyclic peeling cycles is 8-15 times. The three-roll differential speed grinding mill includes a discharge roller N1, a center roller N2, and a feed roller N3. The speed ratio of the feed roller N3, the center roller N2, and the discharge roller N1 is 1:3:9. During the cyclic peeling process, the gap between the center roller N2 and the feed roller N3 is always greater than twice the gap between the discharge roller N1 and the center roller N2.

[0042] It should be noted that the roller gap varies with the number of peeling cycles. For example, during the first to fourth peeling cycles, the gap between the center roller N2 and the feed roller N3, as well as the gap between the discharge roller N1 and the center roller N2, are all between 20 and 200 μm. During the fifth to eighth peeling cycles, the gap between the center roller N2 and the feed roller N3, as well as the gap between the discharge roller N1 and the center roller N2, are all between 5 and 20 μm. After the ninth peeling cycle, the gap between the center roller N2 and the feed roller N3, as well as the gap between the discharge roller N1 and the center roller N2, are all between 0.5 and 5 μm.

[0043] In step 3, repeat this step to control the number of alcohol cleaning cycles to 3-6.

[0044] In step 4, the nitrate is at least one of nickel nitrate, ferric nitrate, or cobalt nitrate.

[0045] In step 6, the final carbon-coated exfoliated metal sulfide composite graphite nanosheet battery anode material includes few-layer nano-metal sulfide composite few-layer graphite nanosheets formed by exfoliating metal sulfides and flake graphite with a thickness of micrometers in resin through three-roll milling, as well as amorphous carbon coated with resin in the heat-treated part of their surface and carbon nanotubes formed by the catalytic part of the resin. After exfoliation, the interlayer spacing of the nano-metal sulfide and nano-graphite flakes increases. Among them, the few-layer nano-metal sulfide accounts for 2-20 wt% of the total mass, the few-layer graphite nanosheets account for 70-80 wt% of the total mass, the amorphous carbon accounts for 0.5-5 wt% of the total mass, and the carbon nanotubes account for 0.1-5 wt% of the total mass.

[0046] The following description, in conjunction with examples and comparative examples, provides a detailed explanation.

[0047] Example 1: The negative electrode material prepared in this example uses layered flake graphite and layered MoS2 as raw materials, phenolic resin as grinding medium and coated carbon raw material, and nickel nitrate as catalyst. The raw material components by weight percentage are: layered flake graphite 14 wt%, layered MoS2 2.8 wt%, phenolic resin 83.15 wt%, and nitrate 0.05 wt%. The layered MoS2 raw material has a length and width of 50 μm and a thickness of 15 μm; the layered flake graphite has a length and width of 150 μm and a thickness of 10 μm.

[0048] The specific steps include:

[0049] Step 1: Mix layered flake graphite and layered MoS2 evenly, then add the mixture to the resin and stir in a 50°C water bath for 20 minutes to obtain mixture A;

[0050] Step 2: The mixture A obtained in Step 1 is exfoliated using a three-roll differential mill. After 15 cycles of exfoliation, a mixture B of layered MoS2 nanosheets composite graphite nanosheets and resin is collected from the discharge roller. During the first to fourth cycles of exfoliation, the gap between N3 and N2 is 50 μm, and the gap between N2 and N1 is 20 μm. During the fifth to eighth cycles of exfoliation, the gap between N3 and N2 is 10 μm, and the gap between N2 and N1 is 5 μm. During the ninth to fifteenth cycles of exfoliation, the gap between N3 and N2 is 2 μm, and the gap between N2 and N1 is 0.5 μm.

[0051] Step 3: Add 100 vol% alcohol to the mixture B of graphite nanosheets and phenolic resin obtained by exfoliation of layered MoS2 nanosheets, stir and sonicate for 10 min, put it into a centrifuge tube for centrifugation and remove impurities. Repeat this step to control the number of alcohol washing times to 4 times, and finally centrifuge to obtain substance C.

[0052] Step 4: Using the impurity liquid removed by centrifugation after washing the resin with alcohol in step 3 for the fourth time, take an equal volume of the impurity liquid as the centrifuged substance C, dissolve 0.05wt% of nitrate raw material in it, mix it with substance C and stir for 5 minutes, then dry to remove the alcohol to form mixture D.

[0053] Step 5: Place mixture D in a freeze dryer and freeze dry it under vacuum at -40°C to obtain mixture E that can maintain its sheet-like structure;

[0054] Step 6: Place the freeze-dried mixture E in a tube furnace and heat-treat it under an argon atmosphere, starting from room temperature at a rate of 3°C / min. -1 The temperature was increased to 800℃, held for 3 hours, and then allowed to cool naturally to room temperature to obtain the MoS2 composite graphite nanosheet battery anode material with amorphous carbon coating exfoliated from carbon nanotubes.

[0055] Weigh out 0.07 g of the amorphous carbon nanotube-coated MoS2 composite graphite nanosheet battery negative electrode material prepared in this embodiment, 0.015 g of acetylene black (conductive agent), and 0.015 g of PVDF (HSV900, binder). After thorough grinding, add 0.4 mL of NMP for dispersion and mixing, then uniformly coat it onto copper foil. After vacuum drying at 120 °C for 10 h, cut it into 12 mm diameter discs and assemble them in an argon-atmosphere glove box. Use a lithium metal sheet as the counter electrode, 1 M LiPF6 solution (solvent EC:DEC volume ratio 1:1) as the electrolyte, and Celegard 2400 as the separator to assemble a CR2032 type coin cell lithium battery. At 25 °C, at 100 mA g... -1 Constant current charge-discharge tests were conducted on the MoS2 composite graphite nanosheet battery anode material with amorphous carbon nanotube coating exfoliation at a current density within a voltage window of 0.01-3.0V. The initial charge / discharge specific capacities as a lithium-ion battery anode were 756 / 1068 mA hg, respectively. -1 The discharge specific capacity after 100 cycles is 690 mAh g. -1 At 25°C, in 1A g -1 A constant current charge-discharge test was conducted on the MoS2 composite graphite nanosheet battery anode material with amorphous carbon nanotube coating exfoliation at a current density with a voltage window of 0.01-3.0V. After 500 cycles, the capacity still had 554 mAh g / g. -1 1A g -1 The capacity retention rate is 98% after 500 cycles at current density.

[0056] Sodium batteries were assembled and their performance tested under the same preparation conditions and parameters. A sodium metal sheet was used as the counter electrode, a 1M NaClO4 solution (solvent EC:PC volume ratio 1:1) was used as the electrolyte, and a glass fiber Whatman GF / A membrane was used as the separator. A CR2032 type coin cell sodium battery was assembled. The performance was tested at 25°C and 100 mA g. -1 Constant current charge-discharge tests were conducted on the MoS2 composite graphite nanosheet battery anode material with amorphous carbon nanotube coating exfoliation at a current density within a voltage window of 0-3.0V. The initial charge / discharge specific capacities as a sodium-ion battery anode were 515.7 / 776 mA hg, respectively. -1 The discharge specific capacity after 100 cycles is 505 mAh g. -1 .

[0057] Potassium-ion batteries were assembled and their performance tested under the same preparation conditions and parameters. A CR2032 coin cell was assembled using a potassium metal sheet as the counter electrode, a 1M KPF6 solution (DIGLYME solvent) as the electrolyte, and a glass fiber Whatman GF / A separator. The performance was tested at 25°C and 100 mA g. -1 Constant current charge-discharge tests were conducted on the MoS2 composite graphite nanosheet battery anode material with amorphous carbon coating exfoliated from carbon nanotubes within a voltage window of 0-3.0V at a current density. The initial charge / discharge specific capacities as a potassium-ion battery anode were 350.5 / 514.8 mA hg, respectively. -1 The discharge specific capacity after 100 cycles is 330.5 mAh g. -1 .

[0058] Example 2: The negative electrode material prepared in this example uses layered flake graphite and layered MoS2 as raw materials, phenolic resin as the grinding medium and coating carbon raw material, and nickel nitrate as the catalyst. The raw material components by weight percentage are: layered flake graphite 10 wt%, layered MoS2 1.25 wt%, phenolic resin 88.73 wt%, and nitrate 0.02 wt%. The layered MoS2 raw material has a length and width of 50 μm and a thickness of 15 μm; the layered flake graphite has a length and width of 150 μm and a thickness of 10 μm.

[0059] The specific steps include:

[0060] Step 1: Mix layered flake graphite and layered MoS2 evenly, then add the mixture to the resin and stir it in a 60°C water bath for 10 minutes to obtain mixture A;

[0061] Step 2: The mixture A obtained in Step 1 is exfoliated using a three-roll differential mill. After 10 cycles of exfoliation, a mixture B of layered MoS2 nanosheets composite graphite nanosheets and resin is collected from the discharge roller. During the first to fourth cycles of exfoliation, the gap between N3 and N2 is 50 μm, and the gap between N2 and N1 is 20 μm. During the fifth to eighth cycles of exfoliation, the gap between N3 and N2 is 10 μm, and the gap between N2 and N1 is 5 μm. During the ninth to tenth cycles of exfoliation, the gap between N3 and N2 is 2 μm, and the gap between N2 and N1 is 0.5 μm.

[0062] Step 3: Add 100 vol% alcohol to the mixture B of graphite nanosheets and phenolic resin obtained by exfoliation of layered MoS2 nanosheets, stir and sonicate for 10 min, put it into a centrifuge tube for centrifugation and remove impurities. Repeat this step to control the number of alcohol washing times to 3 times, and finally centrifuge to obtain substance C.

[0063] Step 4: Using the impurity liquid removed by centrifugation after the third cleaning of the resin with alcohol in Step 3 as a solvent, measure an amount of the impurity liquid with the same volume as substance C obtained by centrifugation, dissolve 0.02wt% nitrate raw material in it, mix it with substance C and stir for 8 minutes, then dry to remove the alcohol to form mixture D.

[0064] Step 5: Place mixture D in a freeze dryer and freeze dry it under vacuum at -40°C to obtain mixture E that can maintain its sheet-like structure;

[0065] Step 6: Place the freeze-dried mixture E in a tube furnace and heat-treat it under an argon atmosphere, starting from room temperature and increasing the temperature by 5°C / min. -1 The temperature was increased to 600℃, held for 4 hours, and then allowed to cool naturally to room temperature to obtain the MoS2 composite graphite nanosheet battery anode material with amorphous carbon coating exfoliated from carbon nanotubes.

[0066] Weigh out 0.07 g of the amorphous carbon nanotube-coated MoS2 composite graphite nanosheet battery anode material prepared in this embodiment, 0.015 g of acetylene black (conductive agent), and 0.015 g of PVDF (HSV900, binder). After thorough grinding, add 0.4 mL of NMP for dispersion and mixing, then uniformly coat it onto copper foil. After vacuum drying at 120 °C for 10 h, cut it into 12 mm diameter discs and assemble them in an argon-atmosphere glove box. Use a lithium metal sheet as the counter electrode, 1 M LiPF6 solution (solvent EC:DEC volume ratio 1:1) as the electrolyte, and Celegard 2400 as the separator to assemble a CR2032 type coin cell lithium battery. At 25 °C, at 100 mA g... -1Constant current charge-discharge tests were conducted on the MoS2 composite graphite nanosheet battery anode material with amorphous carbon nanotube coating exfoliation at a current density within a voltage window of 0.01-3.0V. The initial charge / discharge specific capacities as a lithium-ion battery anode were 662 / 929 mA hg, respectively. -1 The discharge specific capacity after 100 cycles is 617 mAh g. -1 At 25°C, in 1A g -1 A constant current charge-discharge test was conducted on the MoS2 composite graphite nanosheet battery anode material with amorphous carbon nanotube coating exfoliation at a current density with a voltage window of 0.01-3.0V. After 500 cycles, the capacity still had 502 mAh g / g. -1 1A g -1 The capacity retention rate is 96% after 500 cycles at current density.

[0067] Example 3: The negative electrode material prepared in this example uses layered flake graphite and layered WS2 as raw materials, phenolic resin as grinding medium and coated carbon raw material, and nickel nitrate as catalyst. The raw material components by weight percentage are: layered flake graphite 12wt%, layered WS2 1.9wt%, phenolic resin 86.0wt%, and nitrate 0.1wt%. The layered WS2 raw material has a length and width of 40μm and a thickness of 10μm. The layered flake graphite has a length and width of 150μm and a thickness of 10μm.

[0068] The specific steps include:

[0069] Step 1: Mix layered flake graphite and layered WS2 evenly, then add the mixture to the resin and mix it in a 45°C water bath for 15 minutes by stirring to obtain mixture A;

[0070] Step 2: The mixture A obtained in Step 1 is exfoliated using a three-roll differential mill. After 12 cycles of exfoliation, a mixture B of layered WS2 nanosheets composite graphite nanosheets and resin is collected from the discharge roller. During the first to fourth cycles of exfoliation, the gap between N3 and N2 is 50 μm, and the gap between N2 and N1 is 20 μm. During the fifth to eighth cycles of exfoliation, the gap between N3 and N2 is 10 μm, and the gap between N2 and N1 is 5 μm. During the ninth to twelfth cycles of exfoliation, the gap between N3 and N2 is 2 μm, and the gap between N2 and N1 is 0.5 μm.

[0071] Step 3: Add 100 vol% alcohol to the mixture B of graphite nanosheets and phenolic resin obtained by exfoliation of layered WS2 nanosheets, stir and sonicate for 10 min, put it into a centrifuge tube for centrifugation and remove impurities. Repeat this step to control the number of alcohol washing times to 3 times, and finally centrifuge to obtain substance C.

[0072] Step 4: Using the impurity liquid removed by centrifugation after the third cleaning of the resin with alcohol in Step 3 as a solvent, measure an amount of the impurity liquid with the same volume as substance C obtained by centrifugation, dissolve 0.1 wt% of nitrate raw material in it, mix it with substance C and stir for 5 minutes, then dry to remove the alcohol to form mixture D.

[0073] Step 5: Place mixture D in a freeze dryer and freeze dry it under vacuum at -40°C to obtain mixture E that can maintain its sheet-like structure;

[0074] Step 6: Place the freeze-dried mixture E in a tube furnace and heat-treat it under an argon atmosphere, from room temperature at a rate of 2°C / min. -1 The temperature was increased to 700℃, held for 4 hours, and then allowed to cool naturally to room temperature to obtain the WS2 composite graphite nanosheet battery anode material with amorphous carbon coating exfoliated from carbon nanotubes.

[0075] Weigh out 0.07g of the carbon nanotube-coated amorphous carbon-coated WS2 composite graphite nanosheet battery anode material prepared in this embodiment, 0.015g of acetylene black (conductive agent), and 0.015g of PVDF (HSV900, binder). After thorough grinding, add 0.4mL of NMP for dispersion and mixing, then uniformly coat it onto copper foil. After vacuum drying at 120℃ for 10h, cut it into 12mm diameter discs and assemble them in an argon-atmospheric glove box. Use a lithium metal sheet as the counter electrode, 1M LiPF6 solution (solvent EC:DEC volume ratio 1:1) as the electrolyte, and Celegard 2400 as the separator to assemble a CR2032 type coin cell lithium battery. At 25℃, at 100mA g -1 Constant current charge-discharge tests were conducted on the WS2 composite graphite nanosheet battery anode material with amorphous carbon nanotube coating exfoliation at a current density within a voltage window of 0.01-3.0V. The initial charge / discharge specific capacities as a lithium-ion battery anode were 458 / 633 mA hg, respectively. -1 The discharge specific capacity after 100 cycles is 396 mAh g. -1 At 25°C, in 1Ag -1 A constant current charge-discharge test was conducted on the WS2 composite graphite nanosheet battery anode material with amorphous carbon nanotube coating exfoliation at a current density with a voltage window of 0.01-3.0V. After 500 cycles, the capacity still had 364 mAh g / g. -1 1A g -1 The capacity retention rate is 95% after 500 cycles at current density.

[0076] Example 4: The negative electrode material prepared in this example uses layered flake graphite and layered VS2 as raw materials, phenolic resin as grinding medium and coated carbon raw material, and nickel nitrate as catalyst. The raw material components by weight percentage are: layered flake graphite 15 wt%, layered VS2 3.0 wt%, phenolic resin 81.8 wt%, and nitrate 0.2 wt%. The layered VS2 raw material has a length and width of 50 μm and a thickness of 15 μm. The layered flake graphite has a length and width of 150 μm and a thickness of 10 μm.

[0077] The specific steps include:

[0078] Step 1: Mix layered flake graphite and layered VS2 evenly, then add the mixture to the resin and stir it in a 55°C water bath for 10 minutes to obtain mixture A;

[0079] Step 2: The mixture A obtained in Step 1 is exfoliated using a three-roll differential mill. After 11 cycles of exfoliation, a mixture B of layered VS2 nanosheet composite graphite nanosheets and resin is collected from the discharge roller. During the first to fourth cycles of exfoliation, the gap between N3 and N2 is 50 μm, and the gap between N2 and N1 is 20 μm. During the fifth to eighth cycles of exfoliation, the gap between N3 and N2 is 10 μm, and the gap between N2 and N1 is 5 μm. During the ninth to eleventh cycles of exfoliation, the gap between N3 and N2 is 2 μm, and the gap between N2 and N1 is 0.5 μm.

[0080] Step 3: Add 100 vol% alcohol to the mixture B of graphite nanosheets and phenolic resin obtained by exfoliation of layered VS2 nanosheets, stir and sonicate for 10 min, put it into a centrifuge tube for centrifugation and remove impurities. Repeat this step to control the number of alcohol washing times to 4 times, and finally centrifuge to obtain substance C.

[0081] Step 4: Using the impurity liquid removed by centrifugation after washing the resin with alcohol in step 3 for the fourth time, take an amount of impurity liquid with the same volume as substance C obtained by centrifugation, dissolve 0.2wt% nitrate raw material in it, mix it with substance C and stir for 5 minutes, then dry to remove the alcohol to form mixture D.

[0082] Step 5: Place mixture D in a freeze dryer and freeze dry it under vacuum at -40°C to obtain mixture E that can maintain its sheet-like structure;

[0083] Step 6: Place the freeze-dried mixture E in a tube furnace and heat-treat it under an argon atmosphere, starting from room temperature at a rate of 3°C / min. -1The temperature was increased to 800℃, held for 3 hours, and then allowed to cool naturally to room temperature to obtain the VS2 composite graphite nanosheet battery anode material with amorphous carbon coating exfoliated from carbon nanotubes.

[0084] Weigh out 0.07g of the carbon nanotube-coated amorphous carbon-exfoliated VS2 composite graphite nanosheet battery anode material prepared in this embodiment, 0.015g of acetylene black (conductive agent), and 0.015g of PVDF (HSV900, binder). After thorough grinding, add 0.4mL of NMP for dispersion and mixing, then uniformly coat it onto copper foil. After vacuum drying at 120℃ for 10h, cut it into 12mm diameter discs and assemble them in an argon-atmospheric glove box. Use a lithium metal sheet as the counter electrode, 1M LiPF6 solution (solvent EC:DEC volume ratio 1:1) as the electrolyte, and Celegard 2400 as the separator to assemble a CR2032 type coin cell lithium battery. Test at 25℃ at 100mAg... -1 Constant current charge-discharge tests were conducted on the VS2 composite graphite nanosheet battery anode material with amorphous carbon nanotube coating exfoliation at a current density within a voltage window of 0.01-3.0V. The initial charge / discharge specific capacities as a lithium-ion battery anode were 467 / 689 mA hg, respectively. -1 The discharge specific capacity after 100 cycles is 416 mAh g. -1 At 25°C, in 1A g -1 A constant current charge-discharge test was conducted on the VS2 composite graphite nanosheet battery anode material with amorphous carbon nanotube coating exfoliation at a current density with a voltage window of 0.01-3.0V. After 500 cycles, the capacity still had 372 mAh g / g. -1 1A g -1 The capacity retention rate is 96% after 500 cycles at current density.

[0085] Comparative Example 1 differs from Example 1 in that it does not involve the use of a three-roll mill for peeling, phenolic resin, or nickel nitrate. As a result, there is no carbon nanotube or amorphous carbon coating. Instead, it directly utilizes two-dimensional layered MoS2 raw material with a thickness of micrometers and flake graphite raw material in a mass ratio of 2.8% to 14%.

[0086] Weigh out 0.07g of two-dimensional layered MoS2 (50μm x 15μm) and flake graphite (150μm x 10μm), 0.015g of acetylene black (conductive agent), and 0.015g of PVDF (HSV900, binder). After thorough grinding, add 0.4mL of NMP for dispersion and mixing. Then, uniformly coat the mixture onto copper foil. After vacuum drying at 120℃ for 10h, cut into 12mm diameter discs. Assemble in an argon-atmosphere glove box, using a lithium metal sheet as the counter electrode, 1M LiPF6 solution (solvent EC:DEC volume ratio 1:1) as the electrolyte, and Celegard 2400 as the separator to assemble a CR2032 type coin cell lithium battery. Test at 25℃ and 100mA g. -1 Constant current charge-discharge tests were conducted on micron-sized two-dimensional layered MoS2 raw materials and flake graphite raw material composites under a current density with a voltage window of 0.01-3.0V. The initial charge / discharge specific capacities as lithium-ion battery anodes were 421 / 597 mA hg, respectively. -1 The discharge specific capacity after 100 cycles is 369 mAh g. -1 At 25°C, in 1A g -1 A constant current charge-discharge test was conducted on a micron-sized two-dimensional layered MoS2 material and flake graphite material composite material at a current density with a voltage window of 0.01-3.0V. After 500 cycles, the capacity still had 334 mAh g. -1 1A g -1 The capacity retention rate after 500 cycles at current density is 78%.

[0087] Comparative Example 2 differs from Example 1 in that it does not use a three-roll mill for peeling, but includes phenolic resin and no nickel nitrate. After heat treatment, it exhibits amorphous carbon coating but lacks carbon nanotubes, thus forming amorphous carbon-coated micron-sized flake graphite and micron-sized two-dimensional layered MoS2 raw materials. The specific preparation steps are as follows:

[0088] The negative electrode material prepared in this comparative example uses layered flake graphite and layered MoS2 as raw materials, and phenolic resin as the carbon coating material. The raw material composition by weight percentage is: layered flake graphite 14 wt%, layered MoS2 2.8 wt%, and phenolic resin 83.2 wt%. The layered MoS2 raw material has a length and width of 50 μm and a thickness of 15 μm. The layered flake graphite has a length and width of 150 μm and a thickness of 10 μm.

[0089] The specific steps include:

[0090] Step 1: Mix layered flake graphite and layered MoS2 evenly, then add the mixture to the resin and stir in a 50°C water bath for 20 minutes to obtain mixture A;

[0091] Step 2: Add 100 vol% alcohol to mixture A, stir and sonicate for 10 min, then centrifuge in a centrifuge tube to remove impurities. Repeat this step to wash with alcohol 4 times, and finally centrifuge to obtain substance B.

[0092] Step 3: Place mixture B in a freeze dryer and freeze dry it under vacuum at -40°C to obtain mixture C that can maintain its sheet-like structure;

[0093] Step 4: Place the freeze-dried mixture C in a tube furnace and heat-treat it under an argon atmosphere, from room temperature at a rate of 3°C / min. -1 The temperature was raised to 800℃, held for 3 hours, and then allowed to cool naturally to room temperature, thus obtaining the amorphous carbon-coated micron-scale flake graphite and micron-scale two-dimensional layered MoS2 raw material battery anode material described in this comparative example.

[0094] Weigh out 0.07 g of amorphous carbon-coated micron-sized flake graphite and micron-sized two-dimensional layered MoS2 raw material anode material prepared in this comparative example, 0.015 g of acetylene black (conductive agent), and 0.015 g of PVDF (HSV900, binder). After thorough grinding, add 0.4 mL of NMP for dispersion and mixing, then uniformly coat it onto copper foil. After vacuum drying at 120 °C for 10 h, cut it into 12 mm diameter discs and assemble them in an argon-atmospheric glove box. Use lithium metal sheet as the counter electrode, 1 M LiPF6 solution (solvent EC:DEC volume ratio 1:1) as the electrolyte, and Celegard 2400 as the separator to assemble a CR2032 type coin cell lithium battery. At 25 °C, at 100 mA g -1 The voltage window at the current density was 0.01-3.0V. Constant current charge-discharge tests were conducted on the amorphous carbon-coated micron-sized flake graphite and micron-sized two-dimensional layered MoS2 raw material battery anode materials prepared in the comparative example. The initial charge / discharge specific capacities as lithium-ion battery anodes were 486 / 675 mAh g, respectively. -1 The discharge specific capacity after 100 cycles is 424 mAh g. -1 At 25°C, in 1A g -1 Constant current charge-discharge tests were conducted on amorphous carbon-coated micron-sized flake graphite and micron-sized two-dimensional layered MoS2 raw material battery anode materials with a voltage window of 0.01-3.0V at a current density. After 500 cycles, the capacity still had 375mAh g / g. -1 1A g-1 The capacity retention rate after 500 cycles at current density is 88%.

[0095] Comparative Example 3 differs from Example 1 in that it involves a three-roll mill for peeling, but ultimately all phenolic resin is washed away, and there is no nickel nitrate. Heat treatment is unnecessary, and therefore carbon nanotubes and amorphous carbon coating are absent. Only nanoscale graphite flakes and nanoscale two-dimensional layered MoS2 are formed. The specific preparation steps are as follows:

[0096] The negative electrode material prepared in this comparative example uses layered flake graphite and layered MoS2 as raw materials, and phenolic resin as the grinding medium. The raw material components by weight percentage are: layered flake graphite 14 wt%, layered MoS2 2.8 wt%, and phenolic resin 83.2 wt%. The layered MoS2 raw material has a length and width of 50 μm and a thickness of 15 μm. The layered flake graphite has a length and width of 150 μm and a thickness of 10 μm.

[0097] The specific steps include:

[0098] Step 1: Mix layered flake graphite and layered MoS2 evenly, then add the mixture to the resin and stir in a 50°C water bath for 20 minutes to obtain mixture A;

[0099] Step 2: The mixture A obtained in Step 1 is exfoliated using a three-roll differential mill. After 15 cycles of exfoliation, a mixture B of layered MoS2 nanosheets composite graphite nanosheets and resin is collected from the discharge roller. During the first to fourth cycles of exfoliation, the gap between N3 and N2 is 50 μm, and the gap between N2 and N1 is 20 μm. During the fifth to eighth cycles of exfoliation, the gap between N3 and N2 is 10 μm, and the gap between N2 and N1 is 5 μm. During the ninth to fifteenth cycles of exfoliation, the gap between N3 and N2 is 2 μm, and the gap between N2 and N1 is 0.5 μm.

[0100] Step 3: Add 100 vol% alcohol to the mixture B of graphite nanosheets and phenolic resin obtained by exfoliation of layered MoS2 nanosheets, stir and sonicate for 10 min, put it into a centrifuge tube for centrifugation and remove impurities. Repeat this step to control the number of alcohol washing times to 15 times, and finally centrifuge to obtain substance C.

[0101] Step 4: Place mixture C in a freeze dryer and freeze dry it under vacuum at -40°C to obtain mixture D that can maintain its sheet-like structure;

[0102] Step 5: Place the freeze-dried mixture D in a tube furnace and heat-treat it under an argon atmosphere, starting from room temperature at a rate of 3°C / min. -1The temperature was increased to 800℃, held for 3 hours, and then allowed to cool naturally to room temperature to obtain the exfoliated MoS2 composite graphite nanosheet battery anode material described in this comparative example.

[0103] Weigh out 0.07 g of the MoS2 composite graphite nanosheet battery anode material, 0.015 g of acetylene black (conductive agent), and 0.015 g of PVDF (HSV900, binder) prepared in this comparative example. After thorough grinding, add 0.4 mL of NMP for dispersion and mixing, then uniformly coat it onto copper foil. After vacuum drying at 120 °C for 10 h, cut it into 12 mm diameter discs and assemble them in an argon-atmospheric glove box. Use lithium metal sheet as the counter electrode, 1 M LiPF6 solution (solvent EC:DEC volume ratio 1:1) as the electrolyte, and Celegard 2400 as the separator to assemble a CR2032 type coin cell lithium battery. At 25 °C, at 100 mA g... -1 Constant current charge-discharge tests were conducted on the exfoliated MoS2 composite graphite nanosheet battery anode material within a voltage window of 0.01-3.0V at a current density. The initial charge / discharge specific capacities as lithium-ion battery anodes were 558 / 763 mA hg, respectively. -1 The discharge specific capacity after 100 cycles is 506 mAh g. -1 At 25°C, in 1A g -1 A constant current charge-discharge test was conducted on the exfoliated MoS2 composite nanographite sheet battery anode material with a voltage window of 0.01-3.0 V at a current density. After 500 cycles, the capacity still had 430 mAh g / g. -1 1A g -1 The capacity retention rate is 92% after 500 cycles at current density.

[0104] Comparative Example 4 differs from Example 1 in that it does not involve three-roll mill peeling, uses phenolic resin and nickel nitrate, and requires heat treatment. Therefore, it contains carbon nanotubes and amorphous carbon coating, resulting only in carbon nanotube-amorphous carbon-coated micron-sized flake graphite and micron-sized two-dimensional layered MoS2 raw materials. The specific preparation steps are as follows:

[0105] The negative electrode material prepared in this comparative example uses layered flake graphite and layered MoS2 as raw materials, and phenolic resin as the grinding medium. The raw material components by weight percentage are: layered flake graphite 14 wt%, layered MoS2 2.8 wt%, phenolic resin 83.15 wt%, and nitrate 0.05 wt%. The layered MoS2 raw material has a length and width of 50 μm and a thickness of 15 μm. The layered flake graphite has a length and width of 150 μm and a thickness of 10 μm.

[0106] The specific steps include:

[0107] Step 1: Mix layered flake graphite and layered MoS2 evenly, then add the mixture to the resin and stir in a 50°C water bath for 20 minutes to obtain mixture A;

[0108] Step 2: Add 100 vol% alcohol to mixture A, stir and sonicate for 10 min, then centrifuge in a centrifuge tube to remove impurities. Repeat this step to wash with alcohol 4 times, and finally centrifuge to obtain substance B.

[0109] Step 3: Using the impurity liquid removed by centrifugation after washing the resin with alcohol in Step 2 for the fourth time, take an amount of impurity liquid with the same volume as substance B obtained by centrifugation, dissolve 0.05wt% nitrate raw material in it, mix it with substance B and stir for 5 minutes, then dry to remove the alcohol to form mixture C.

[0110] Step 4: Place mixture C in a freeze dryer and freeze dry it under vacuum at -40°C to obtain mixture D that can maintain its sheet-like structure;

[0111] Step 5: Place the freeze-dried mixture D in a tube furnace and heat-treat it under an argon atmosphere, starting from room temperature at a rate of 3°C / min. -1 The temperature was raised to 800℃, held for 3 hours, and then allowed to cool naturally to room temperature, thus obtaining the carbon nanotube amorphous carbon-coated micron-scale flake graphite and micron-scale two-dimensional layered MoS2 raw material battery anode material described in this comparative example.

[0112] Weigh out 0.07 g of the carbon nanotube amorphous carbon-coated micron-sized flake graphite and micron-sized two-dimensional layered MoS2 raw material anode material prepared in this comparative example, 0.015 g of acetylene black (conductive agent), and 0.015 g of PVDF (HSV900, binder). After thorough grinding, add 0.4 mL of NMP for dispersion and mixing, then uniformly coat it onto copper foil. After vacuum drying at 120 °C for 10 h, cut it into 12 mm diameter discs and assemble them in an argon-atmosphere glove box. Use a lithium metal sheet as the counter electrode, 1 M LiPF6 solution (solvent EC:DEC volume ratio 1:1) as the electrolyte, and Celegard 2400 as the separator to assemble a CR2032 type coin cell lithium battery. Test at 25 °C at 100 mA g. -1 The voltage window at the current density was 0.01-3.0V. Constant current charge-discharge tests were conducted on the carbon nanotube-coated micron-sized flake graphite and micron-sized two-dimensional layered MoS2 raw material battery anode materials prepared in this comparative example. The initial charge / discharge specific capacities as lithium-ion battery anodes were 526 / 735 mA hg, respectively. -1The discharge specific capacity after 100 cycles is 468 mAh g. -1 At 25°C, in 1A g -1 The voltage window at the current density is 0.01-3.0V. Constant current charge-discharge tests were conducted on the carbon nanotube-coated micron-sized flake graphite and micron-sized two-dimensional layered MoS2 raw material battery anode materials prepared in this comparative example. After 500 cycles, the capacity still had 402 mAh g⁻¹. -1 1Ag -1 The capacity retention rate is 94% after 500 cycles at current density.

[0113] Comparative Example 5 differs from Example 1 in that the drying method used is oven drying instead of freeze drying. The oven drying method produces layered flake graphite nanosheets and layered MoS2 nanosheets formed by the exfoliation of amorphous carbon coatings from carbon nanotubes. The specific preparation steps are as follows:

[0114] The negative electrode material prepared in this comparative example uses layered flake graphite and layered MoS2 as raw materials, phenolic resin as the grinding medium and coating carbon raw material, and nickel nitrate as the catalyst. The raw material components by weight percentage are: layered flake graphite 14 wt%, layered MoS2 2.8 wt%, phenolic resin 83.15 wt%, and nitrate 0.05 wt%. The layered MoS2 raw material has a length and width of 50 μm and a thickness of 15 μm. The layered flake graphite has a length and width of 150 μm and a thickness of 10 μm.

[0115] The specific steps include:

[0116] Step 1: Mix layered flake graphite and layered MoS2 evenly, then add the mixture to the resin and stir in a 50°C water bath for 20 minutes to obtain mixture A;

[0117] Step 2: The mixture A obtained in Step 1 is exfoliated using a three-roll differential mill. After 15 cycles of exfoliation, a mixture B of layered MoS2 nanosheets composite graphite nanosheets and resin is collected from the discharge roller. During the first to fourth cycles of exfoliation, the gap between N3 and N2 is 50 μm, and the gap between N2 and N1 is 20 μm. During the fifth to eighth cycles of exfoliation, the gap between N3 and N2 is 10 μm, and the gap between N2 and N1 is 5 μm. During the ninth to fifteenth cycles of exfoliation, the gap between N3 and N2 is 2 μm, and the gap between N2 and N1 is 0.5 μm.

[0118] Step 3: Add 100 vol% alcohol to the mixture B of graphite nanosheets and phenolic resin obtained by exfoliation of layered MoS2 nanosheets, stir and sonicate for 10 min, put it into a centrifuge tube for centrifugation and remove impurities. Repeat this step to control the number of alcohol washing times to 4 times, and finally centrifuge to obtain substance C.

[0119] Step 4: Using the impurity liquid removed by centrifugation after washing the resin with alcohol in step 3 for the fourth time, take an equal volume of the impurity liquid as the centrifuged substance C, dissolve 0.05wt% of nitrate raw material in it, mix it with substance C and stir for 5 minutes, then dry to remove the alcohol to form mixture D.

[0120] Step 5: Place the mixture D obtained after washing with alcohol in an oven and dry it at 50°C to obtain substance E.

[0121] Step 6: Place the dried mixture E in a tube furnace and heat treat it under an argon atmosphere, starting from room temperature at a rate of 3°C / min. -1 The temperature was increased to 800℃, held for 3 hours, and then allowed to cool naturally to room temperature to obtain the MoS2 composite graphite nanosheet battery anode material with amorphous carbon coating exfoliated from carbon nanotubes as described in this comparative example.

[0122] Weigh out 0.07 g of the amorphous carbon nanotube-coated MoS2 composite graphite nanosheet battery negative electrode material prepared in this comparative example, 0.015 g of acetylene black (conductive agent), and 0.015 g of PVDF (HSV900, binder). After thorough grinding, add 0.4 mL of NMP for dispersion and mixing, then uniformly coat it onto copper foil. After vacuum drying at 120 °C for 10 h, cut it into 12 mm diameter discs and assemble them in an argon-atmosphere glove box. Use lithium metal sheet as the counter electrode, 1 M LiPF6 solution (solvent EC:DEC volume ratio 1:1) as the electrolyte, and Celegard 2400 as the separator to assemble a CR2032 type coin cell lithium battery. At 25 °C, at 100 mA g... -1 A constant current charge-discharge test was conducted on the MoS2 composite graphite nanosheet battery anode material prepared in this comparative example, with a voltage window of 0.01-3.0V and a carbon nanotube amorphous carbon coating exfoliation. The initial charge / discharge specific capacities as lithium-ion battery anodes were 646 / 892 mA hg, respectively. -1 The discharge specific capacity after 100 cycles is 539 mAh g. -1 At 25°C, in 1A g -1The voltage window for the MoS2 composite graphite nanosheet battery anode material prepared in this comparative example, with amorphous carbon nanotube coating exfoliated, was subjected to constant current charge-discharge testing within the current density range of 0.01-3.0V. After 500 cycles, the capacity still retained 466 mAh g⁻¹. -1 1A g -1 The capacity retention rate is 93% after 500 cycles at current density.

[0123] Comparative Example 6 differs from Example 1 in the number of times the phenolic resin is washed. Example 1 involved four washes, while Comparative Example 6 involved two washes. This difference in washes results in varying carbon coating thickness during subsequent heat treatment. The specific preparation steps are as follows:

[0124] The negative electrode material prepared in this embodiment uses layered flake graphite and layered MoS2 as raw materials, phenolic resin as grinding medium and coating carbon raw material, and nickel nitrate as catalyst. The raw material composition by weight percentage is: layered flake graphite 14 wt%, layered MoS2 2.8 wt%, phenolic resin 83.15 wt%, and nitrate 0.05 wt%. The layered MoS2 raw material has a length and width of 50 μm and a thickness of 15 μm. The layered flake graphite has a length and width of 150 μm and a thickness of 10 μm.

[0125] The specific steps include:

[0126] Step 1: Mix layered flake graphite and layered MoS2 evenly, then add the mixture to the resin and stir in a 50°C water bath for 20 minutes to obtain mixture A;

[0127] Step 2: The mixture A obtained in Step 1 is exfoliated using a three-roll differential mill. After 15 cycles of exfoliation, a mixture B of layered MoS2 nanosheets composite graphite nanosheets and resin is collected from the discharge roller. During the first to fourth cycles of exfoliation, the gap between N3 and N2 is 50 μm, and the gap between N2 and N1 is 20 μm. During the fifth to eighth cycles of exfoliation, the gap between N3 and N2 is 10 μm, and the gap between N2 and N1 is 5 μm. During the ninth to fifteenth cycles of exfoliation, the gap between N3 and N2 is 2 μm, and the gap between N2 and N1 is 0.5 μm.

[0128] Step 3: Add 100 vol% alcohol to the mixture B of graphite nanosheets and phenolic resin obtained by exfoliation of layered MoS2 nanosheets, stir and sonicate for 10 min, put it into a centrifuge tube for centrifugation and remove impurities. Repeat this step to control the number of alcohol washing times to 2, and finally centrifuge to obtain substance C.

[0129] Step 4: Using the impurity liquid removed by centrifugation after the second alcohol washing of the resin in Step 3 as a solvent, measure an amount of the impurity liquid with the same volume as substance C obtained by centrifugation, dissolve 0.05wt% nitrate raw material in it, mix it with substance C and stir for 5 minutes, then dry to remove the alcohol to form mixture D.

[0130] Step 5: Place mixture D in a freeze dryer and freeze dry it under vacuum at -40°C to obtain mixture E that can maintain its sheet-like structure;

[0131] Step 6: Place the freeze-dried mixture E in a tube furnace and heat-treat it under an argon atmosphere, starting from room temperature at a rate of 3°C / min. -1 The temperature was increased to 800℃, held for 3 hours, and then allowed to cool naturally to room temperature to obtain the MoS2 composite graphite nanosheet battery anode material with amorphous carbon coating exfoliated from carbon nanotubes.

[0132] Weigh out 0.07 g of the amorphous carbon nanotube-coated MoS2 composite graphite nanosheet battery negative electrode material prepared in this comparative example, 0.015 g of acetylene black (conductive agent), and 0.015 g of PVDF (HSV900, binder). After thorough grinding, add 0.4 mL of NMP for dispersion and mixing, then uniformly coat it onto copper foil. After vacuum drying at 120 °C for 10 h, cut it into 12 mm diameter discs and assemble them in an argon-atmosphere glove box. Use lithium metal sheet as the counter electrode, 1 M LiPF6 solution (solvent EC:DEC volume ratio 1:1) as the electrolyte, and Celegard 2400 as the separator to assemble a CR2032 type coin cell lithium battery. At 25 °C, at 100 mA g... -1 A constant current charge-discharge test was conducted on the MoS2 composite graphite nanosheet battery anode material prepared in this comparative example, with a voltage window of 0.01-3.0V and a carbon nanotube amorphous carbon coating exfoliation. The initial charge / discharge specific capacities as lithium-ion battery anodes were 656 / 922 mA hg, respectively. -1 The discharge specific capacity after 100 cycles is 558 mAh g. -1 At 25°C, in 1A g -1 The voltage window for the MoS2 composite graphite nanosheet battery anode material prepared in this comparative example, with amorphous carbon nanotube coating exfoliated, was subjected to constant current charge-discharge testing within the current density range of 0.01-3.0V. After 500 cycles, the capacity still retained 481 mAh g⁻¹. -1 1A g -1 The capacity retention rate is 95% after 500 cycles at current density.

[0133] Table 1 below shows a performance comparison between the examples and the comparative examples.

[0134] Table 1 Performance comparison between the examples and comparative examples

[0135]

[0136]

[0137] In summary, this invention employs a three-roll mill grinding and exfoliation technique. This technique utilizes the shear force generated by the differential speed of the three rollers, the interaction between the high-viscosity resin and the surface of the phosphorus flake graphite / layered metal sulfide to overcome interlayer van der Waals forces. This allows for the exfoliation of micron-thick layered materials to prepare a large number of nanoscale flakes. These metal sulfide composite graphite nanosheets have thicknesses ranging from single-layer to several-layer, and even dozens of layers. This method ensures that the metal sulfide and graphite are uniformly dispersed in situ within the resin, resulting in better dispersion than traditional external methods.

[0138] This invention uses nitrate as a catalyst, which is dissolved in ethanol to prepare a nitrate ethanol solution. The nitrate ethanol solution is easy to mix evenly with the resin. During the subsequent heat treatment at 500-900℃, it easily catalyzes the formation of carbon nanotubes in the resin. This method has better dispersibility than adding carbon nanotubes and saves costs.

[0139] Two-dimensional layered metal sulfides, especially MoS2, possess a unique layered structure. The gaps between atomic layers allow for the intercalation of foreign reactants, resulting in a theoretically large capacity as a lithium-ion battery anode. However, due to the multi-layered stacked structure of layered metal sulfides, lithium-ion intercalation can cause changes in volume or structure. In contrast, carbon-based anode materials possess inherent elasticity, are excellent conductors of lithium ions and electrons, have a certain lithium intercalation capacity, exhibit small volume effects during lithium intercalation / deintercalation, and demonstrate excellent cycle stability. Therefore, the purpose of this invention is to use a three-roll milling technique to exfoliate a two-dimensional layered metal sulfide and flake graphite composite anode material from resin. The carbon content of the exfoliated layered metal sulfide composite graphite nanosheet anode material is controllable. Furthermore, the innovative addition of Ni / Co / Fe nitrates allows the resin to undergo heat treatment at a specific temperature, generating one-dimensional carbon nanotubes that intersect between the two-dimensional layers of micro- and nano-graphite flakes, forming a favorable three-dimensional structure. This significantly improves the initial charge-discharge specific capacity of the amorphous carbon / carbon nanotube / layered metal sulfide composite graphite nanosheet anode material, and also greatly improves cycle performance and rate performance, enhancing battery stability and meeting the demand in battery materials and other fields for metal sulfide anode materials with controllable carbon content. This composite anode material combines the high capacity of sulfides, especially MoS2, with the excellent structural stability of multidimensional carbon materials, resulting in an ideal anode composite material for ion batteries.

[0140] Carbon nanotubes possess excellent electrical conductivity and a large specific surface area, making them directly applicable to ion (Li+, Na+, K+) batteries. Their unique tubular structure and intertwined network structure can accelerate the transport rate of ions (Li+, Na+, K+), and carbon nanotubes themselves have a certain conductivity. The interlaced nanostructure provides shorter and faster transport channels for electrons and ions.

[0141] In this technical solution, transition metal Ni / Co / Fe nitrates decompose and are reduced during the heat treatment process, forming a large number of metal particles <100nm. Using an ethanol solution of transition metal nitrates instead of nano-sized metal particles avoids the agglomeration of metals directly, resulting in excellent dispersion and significantly improving the catalytic efficiency. Furthermore, an ethanol solution of transition metal nitrates is used as the catalyst, rather than an aqueous solution, because aqueous solutions are immiscible with epoxy or phenolic resins and cannot disperse them well.

[0142] The present invention yields a metal sulfide composite graphite nanosheet battery anode material with amorphous carbon nanotube coating and exfoliation. This material comprises few-layer nano-metal sulfide composite graphite nanosheets formed by exfoliating micron-thick metal sulfides and flake graphite in resin through three-roll milling. After exfoliation, the interlayer spacing of these nanosheets increases, allowing for more intercalation of external reactants and improving their capacity as a battery anode. The amorphous carbon coating and carbon nanotube intercalation reduce the polarization and impedance of the metal sulfide composite micro / nano-graphite sheet material during charge and discharge. Furthermore, the co-coating modification with amorphous carbon and carbon nanotubes exhibits superior performance compared to individual coating methods. The coating and intercalation of amorphous carbon and carbon nanotubes on and between the metal sulfide composite graphite nanosheets form a three-dimensional network structure that facilitates ion transport. Furthermore, the amorphous carbon and carbon nanotubes act as a "protective barrier," inhibiting side reactions of the electrolyte on the metal sulfides and improving the electrochemical performance of the metal sulfides. The composite of graphite nanosheets and layered metal sulfides can improve the electrochemical performance and structural stability of graphite anode materials.

[0143] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a metal sulfide composite graphite nanosheet battery anode material with carbon nanotube amorphous carbon coating and exfoliation, characterized in that, The main steps include: Step 1: Mix layered flake graphite and layered metal sulfide evenly, then add the mixture to the resin and stir in a water bath at 35-70℃ for 10-30 minutes to obtain mixture A; Step 2: The mixture A obtained in Step 1 is peeled off by a three-roll differential mill. After peeling off 8-15 times, the mixture B, which is a composite of layered metal sulfide nanosheets and resin, is collected from the discharge roller. Step 3: Add 50-200 vol% alcohol to the mixture B of graphite nanosheets and resin obtained by exfoliation of layered metal sulfide nanosheets, stir and sonicate for 10 min, put it into a centrifuge tube for centrifugation and remove impurities, repeat step 3 and continue to wash with alcohol 3-6 times, and finally centrifuge to obtain substance C. Step 4: Using the impurity liquid removed after the final alcohol washing of the resin in Step 3 by centrifugation as a solvent, measure an amount of the impurity liquid equal in volume to the centrifuged substance C, dissolve 0.1-1 wt% of nitrate raw material in it, then mix and stir with substance C for 1-10 minutes, and then dry to remove the alcohol to form mixture D; the layered flake graphite and the layered metal sulfide are the raw materials, the resin is the grinding medium and the coated carbon raw material, and the nitrate is the catalyst, wherein the layered flake graphite accounts for 10-15 wt%, the layered metal sulfide accounts for 0.5-5 wt%, the resin accounts for 75-88 wt%, and the nitrate accounts for 0.1-1 wt%; the resin is one of phenolic resin, epoxy resin, or polyethylene resin, and the nitrate is at least one of nickel nitrate, ferric nitrate, or cobalt nitrate; Step 5: Place mixture D in a freeze dryer and freeze dry it under vacuum at -50 to -30°C to obtain mixture E that maintains a sheet-like structure; Step 6: Place the freeze-dried mixture E in a tube furnace and heat-treat it under an argon atmosphere, from room temperature at a rate of 1-5°C / min. -1 The heating rate is increased to 500-900℃, held for 1-5 hours, and then allowed to cool naturally to room temperature to obtain a metal sulfide composite graphite nanosheet battery anode material with carbon nanotubes amorphous carbon coating and exfoliation.

2. The method for preparing the metal sulfide composite graphite nanosheet battery anode material with amorphous carbon coating exfoliated from carbon nanotubes according to claim 1, characterized in that: The chemical formula of the layered metal sulfide is MS2, where M is one of Mo, W, V or Ti.

3. The method for preparing the metal sulfide composite graphite nanosheet battery anode material with amorphous carbon coating exfoliated from carbon nanotubes according to claim 1, characterized in that: The three-roll differential grinding mill includes a discharge roller N1, a center roller N2, and a feed roller N3. The rotational speed ratio of the feed roller N3, the center roller N2, and the discharge roller N1 is 1:3:

9. During the cyclic peeling process, the gap between the center roller N2 and the feed roller N3 is always greater than twice the gap between the discharge roller N1 and the center roller N2.

4. The method for preparing the metal sulfide composite graphite nanosheet battery anode material with amorphous carbon coating exfoliated from carbon nanotubes according to claim 3, characterized in that: During the first to fourth cycles of peeling, the gap between the center roller N2 and the feed roller N3, as well as the gap between the discharge roller N1 and the center roller N2, are all between 20 and 200 μm.

5. The method for preparing the metal sulfide composite graphite nanosheet battery anode material with amorphous carbon coating exfoliated from carbon nanotubes according to claim 3, characterized in that: During the 5th to 8th cyclic peeling, the gap between the center roller N2 and the feed roller N3, as well as the gap between the discharge roller N1 and the center roller N2, are all between 5 and 20 μm.

6. The method for preparing the metal sulfide composite graphite nanosheet battery anode material with amorphous carbon coating exfoliated from carbon nanotubes according to claim 3, characterized in that: After the 9th cyclic peeling, the gap between the center roller N2 and the feed roller N3, as well as the gap between the discharge roller N1 and the center roller N2, are all between 0.5 and 5 μm.

7. A metal sulfide composite graphite nanosheet battery anode material with carbon nanotube amorphous carbon coating and exfoliation, characterized in that: It is prepared using the method for preparing metal sulfide composite graphite nanosheet battery anode material with carbon nanotube amorphous carbon coating and exfoliation as described in any one of claims 1-6.

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