Black phosphorus-carbon-nitrogen composite negative electrode material and preparation method therefor

Abstract

The present invention relates to the technical field of negative electrode materials for quick charging of secondary batteries, and provides a black phosphorus-carbon-nitrogen composite negative electrode material and a preparation method therefor. The preparation method for the black phosphorus-carbon-nitrogen composite negative electrode material comprises the following steps: S1: placing black phosphorus, a carbon material, and an alkaline nitrogen-containing compound in a ball milling tank in an atmosphere of nitrogen or argon, and adding grinding balls at the same time; and S2: carrying out mixed ball milling at a rotating speed of 100-600 rpm for 1-72 h to obtain the black phosphorus-carbon-nitrogen composite negative electrode material. According to the preparation method for the black phosphorus-carbon-nitrogen composite negative electrode material provided by the present invention, the reconstruction and hybridization processes of phosphorus atoms at the edge of the activated black phosphorus can be accelerated, facilitating phosphorus-carbon-nitrogen bonding. Due to the improvement of the uniform hybridization degree of black phosphorus, the particle size of the obtained black phosphorus-carbon-nitrogen composite negative electrode material is more uniform, effectively solving the problem of non-uniform material size obtained by conventional ball milling. A fast lithium ion conductor can be formed during electrochemical reaction of nitrogen, and with a good conductive channel in the material, a quick charging process is implemented.

Description

A black phosphorus-carbon-nitrogen composite negative electrode material and preparation method thereof Technical Field

[0001] The present invention belongs to the technical field of fast-charging negative electrode materials for secondary batteries, and in particular relates to a black phosphorus-carbon-nitrogen composite negative electrode material and a preparation method thereof. Background Art

[0002] Electric vehicles and consumer electronics are now increasingly integral to our lives, creating an ever-increasing need for fast charging. As a type of secondary battery, lithium-ion batteries offer advantages such as high energy density, rapid charge and discharge capabilities, and a long service life, making them suitable for fast-charging energy storage devices.

[0003] One of the key aspects of lithium-ion secondary batteries lies in the development of fast-charging anode materials. Currently, the most researched anode materials include carbon-based, silicon-based, and lithium titanate-based. However, if we want to achieve fast charge and discharge, especially at 5 C or faster (i.e., 12 minutes at most), while also maintaining a high energy density, these three commonly used anode materials are not suitable for fast charging scenarios.

[0004] The theoretical lithium storage capacity of elemental phosphorus is 2596 mAh / g, and it is abundant in reserves and low in cost, making it a potential fast-charging negative electrode material. As a new type of elemental phosphorus layered material, black phosphorus has a high conductivity (300 S / m), Li + Black phosphorus has a low diffusion barrier (0.08 eV), making it an excellent candidate for next-generation anode materials. However, the alloying process between black phosphorus and lithium ions is complex and results in significant volume expansion (~300%). This leads to low initial Coulombic efficiency (typically below 75%, significantly lower than current commercial anode materials (>90%)), making it difficult to achieve stable fast charging.

[0005] The current common strategy to address the bottleneck of black phosphorus fast charging is to rationally combine black phosphorus with carbon materials (i.e., considering the material preparation). This process is mainly achieved through methods such as ball milling, hydrothermal methods, and evaporation-deposition methods. However, most of these steps are relatively cumbersome, making it difficult to achieve uniform hybridization of black phosphorus and large-scale preparation of composite materials, which restricts the rapid charge / discharge process of black phosphorus-based composite materials. Therefore, it is urgent to develop a method for preparing a fast, large-scale, and uniformly hybridized black phosphorus-based fast-charging anode material.

[0006] Summary of the Invention

[0007] In order to solve the problem in the prior art that the composite method of black phosphorus and carbon materials is cumbersome and difficult to achieve uniform hybridization of black phosphorus and large-scale preparation of composite materials, the present invention provides a method for preparing a black phosphorus-carbon-nitrogen composite negative electrode material.

[0008] The preparation method of the black phosphorus-carbon-nitrogen composite negative electrode material comprises the following steps:

[0009] S1: In a nitrogen or argon atmosphere, black phosphorus, carbon material and basic nitrogen-containing compound are placed in a ball mill and grinding balls are added;

[0010] S2: performing mixing ball milling at a rotation speed of 100-600 rpm for 1-72 h to obtain the black phosphorus-carbon-nitrogen composite negative electrode material.

[0011] Furthermore, the basic nitrogen-containing compound is selected from one or more of o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 2,2'-bipyridine, 2,3'-bipyridine, 2,4'-bipyridine, 4,4'-bipyridine, 1,3,5-triazine-2,4,6-triamine, aniline, quinoline, acridine and phenanthridine.

[0012] Furthermore, the black phosphorus is selected from one or more of micron-sized black phosphorus powder, black phosphorus film, black phosphorus nanosheets and black phosphorus quantum dots.

[0013] Furthermore, the carbon material is selected from one or more of graphene, carbon nanotubes, conductive carbon black, porous carbon, amorphous carbon and graphite.

[0014] Furthermore, the mass ratio of the black phosphorus to the carbon material is 1:20-10:1, and the mass ratio of the black phosphorus to the basic nitrogen-containing compound is 1:10-100:1.

[0015] Furthermore, the ball milling is implemented by drum ball milling or planetary ball milling.

[0016] Furthermore, the ball mill and the grinding balls are made of one or more of agate, zirconium oxide, silicon carbide, stainless steel, polyurethane, and polytetrafluoroethylene.

[0017] Furthermore, the mass ratio of the black phosphorus to the grinding balls is 1:200-1:5, and the diameter of the grinding balls is 1-20 mm.

[0018] The present invention also provides a black phosphorus-carbon-nitrogen composite negative electrode material, which is obtained by the method for preparing the black phosphorus-carbon-nitrogen composite negative electrode material as described in any one of the above.

[0019] The present invention also provides a lithium battery, wherein the negative electrode of the lithium battery is the black phosphorus-carbon-nitrogen composite negative electrode material described above.

[0020] The above technical solution has the following advantages or beneficial effects:

[0021] (1) The present invention utilizes a one-step ball milling process to mix black phosphorus, carbon materials, and alkaline nitrogen-containing compounds. This differs from the traditional ball milling process of mixing black phosphorus and carbon materials. The alkaline nitrogen-containing compound can accelerate the activation of phosphorus atoms at the edge of black phosphorus, promote the reconstruction and hybridization of the edge phosphorus atoms, facilitate covalent bonding between phosphorus and carbon, and generate a large number of phosphorus-nitrogen chemical bonds on the surface of black phosphorus. Due to the improved uniform hybridization of black phosphorus, the particle size of the resulting black phosphorus-carbon-nitrogen composite negative electrode material is more uniform, making it suitable for use as a fast-charging material. This effectively solves the problem of uneven size of black phosphorus-based negative electrode materials prepared by traditional ball milling processes.

[0022] (2) The black phosphorus-carbon-nitrogen composite negative electrode material provided by the present invention contains an alkaline nitrogen-containing compound (organic nitride), which can promote the full infiltration of the black phosphorus-carbon-nitrogen composite negative electrode material with the organic electrolyte, and nitrogen can derive lithium nitrogen compounds that are fast lithium ion conductors during the electrochemical process, forming a uniform solid electrolyte interface film, which, combined with the good conductive channels inside the material, is conducive to the rapid transmission of lithium ions and electrons, thereby realizing a fast charging process.

[0023] (3) The one-step ball milling process for the black phosphorus-carbon-nitrogen composite negative electrode material provided by the present invention has the advantages of a simple preparation process and easy scalability. The phosphorus raw materials, carbon materials, and alkaline nitrogen-containing compounds used are widely available and inexpensive, significantly reducing production costs.

[0024] (4) When the black phosphorus-carbon-nitrogen composite negative electrode material provided by the present invention is used as a fast-charging negative electrode material for lithium-ion secondary batteries, it can significantly alleviate the volume change of black phosphorus during the alloying process, achieve rapid transmission of lithium ions, and effectively inhibit the occurrence of side reactions. The initial coulombic efficiency is greater than 90% @ 0.05 A / g (existing solutions are generally less than 75%). It has excellent and stable long-cycle fast-charging chemical performance, and its rate performance is better than that of currently reported phosphorus-based negative electrode materials and common fast-charging negative electrode materials. It has good application prospects in the field of fast energy storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG1 is a flow chart of a method for preparing a black phosphorus-carbon-nitrogen composite negative electrode material provided by the present invention;

[0026] FIG2 is a scanning electron microscope image of the materials in Example 1 of the present invention and Comparative Example 1;

[0027] FIG3 is a secondary particle size distribution diagram of the materials in Example 1 of the present invention and Comparative Example 1;

[0028] FIG4 is a primary particle size distribution diagram of the materials in Example 1 of the present invention and Comparative Example 1;

[0029] FIG5 is an elemental scanning electron microscope image of the material in Example 1 of the present invention;

[0030] FIG6 is an X-ray diffraction pattern of the materials in Example 1 of the present invention and Comparative Example 1;

[0031] FIG7 is a comparison of the N 1s binding energies of the material of Example 1 of the present invention and o-phenylenediamine;

[0032] FIG8 shows the contact angles of the materials in Example 1 of the present invention and Comparative Example 1 with the organic electrolyte;

[0033] FIG9 is a comparison of the coulombic efficiencies of the materials of Example 1 of the present invention and Comparative Example 1 at 0.05 A / g;

[0034] FIG10 shows the volume expansion of the materials in Example 1 of the present invention and Comparative Example 1 after the electrochemical process;

[0035] FIG11 shows the rate test results of the materials in Example 1 of the present invention and Comparative Example 1 at a range of 0.2 to 50 A / g;

[0036] FIG12 is a comparison of the rate performance of Example 1 of the present invention and reported typical phosphorus-based negative electrode materials;

[0037] FIG13 is a comparison of the rate performance of Example 1 of the present invention and reported typical fast-charging negative electrode materials;

[0038] FIG14 is a comparison of the lithium ion diffusion coefficients of the materials in Example 1 of the present invention and Comparative Example 1;

[0039] FIG15 is a cyclic stability test result of the material of Example 1 of the present invention at 40 A / g;

[0040] FIG16 is an infrared spectrum of the material of Example 2 of the present invention;

[0041] FIG17 is a cyclic stability test result of the material of Example 3 of the present invention at 1 A / g.

[0042] DETAILED DESCRIPTION

[0043] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings, but they should not be understood as limiting the scope of implementation of the present invention.

[0044] In the present invention, unless otherwise specified, all equipment and raw materials can be purchased from the market or are commonly used in the industry. The methods in the following embodiments, unless otherwise specified, are all conventional methods in the art.

[0045] The present invention provides a black phosphorus-carbon-nitrogen composite negative electrode material, which is prepared by the following method.

[0046] As shown in FIG1 , a method for preparing a black phosphorus-carbon-nitrogen composite negative electrode material comprises the following steps:

[0047] S1: In a nitrogen or argon atmosphere, black phosphorus, carbon material and basic nitrogen-containing compound are placed in a ball mill and grinding balls are added;

[0048] S2: performing mixing ball milling at a rotation speed of 100-600 rpm for 1-72 h to obtain the black phosphorus-carbon-nitrogen composite negative electrode material.

[0049] According to the above-mentioned method for preparing the black phosphorus-carbon-nitrogen composite negative electrode material, the present invention provides Examples 1-10.

[0050] Example 1

[0051] S1: Under an argon atmosphere, micron-sized black phosphorus powder, conductive carbon black, and o-phenylenediamine are placed in a ball mill, and grinding balls are added. The mass ratio of micron-sized black phosphorus powder to conductive carbon black is 7:3, and the mass ratio of micron-sized black phosphorus powder to o-phenylenediamine is 35:1. The ball milling is implemented by planetary ball milling. The ball mill and grinding balls are both made of agate. The diameters of the grinding balls are 3 mm and 10 mm, and the mass ratio of micron-sized black phosphorus powder to grinding balls is 1:120.

[0052] S2: The mixed material was ball-milled at 400 rpm for 6 h to obtain the black phosphorus-carbon-nitrogen composite negative electrode material A.

[0053] Comparative Example 1

[0054] This comparative example is basically the same as Example 1, except that o-phenylenediamine is not added. The obtained material is counted as comparative sample 1.

[0055] The products of Example 1 and Comparative Example 1 were characterized and tested as follows:

[0056] 1. Structural Characterization: Scanning electron microscopy results are shown in Figure 2. As shown in Figure 2, the agglomerated particle size (secondary particle size) of the black phosphorus-carbon-nitrogen composite negative electrode material A prepared in Example 1 is relatively uniform, around 2 μm, while the secondary particle sizes of the particles of comparative sample 1 vary greatly.

[0057] 2. Particle size distribution was measured by laser diffraction (reference standard GB / T 19077-2016; secondary particle size). The results are shown in Figure 3. The peak secondary particle size of black phosphorus-carbon-nitrogen composite anode material A in Example 1 was 2.5 μm, while the peak secondary particle sizes of comparative sample 1 were 2.9 μm and 13.2 μm, respectively. This preliminarily indicates that the basic nitrogen-containing compound o-phenylenediamine improves the uniform hybridization of black phosphorus, resulting in a more uniform particle size of the resulting black phosphorus-carbon-nitrogen composite anode material A.

[0058] 3. Structural Characterization and Statistics: The particle size at the nanoscale (i.e., primary particle size) in the scanning electron microscope image was statistically analyzed. The results are shown in FIG4 . The primary particle size of the black phosphorus-carbon-nitrogen composite negative electrode material A in Example 1 is 209±29 nm, and the primary particle size of the comparative sample 1 is 283±209 nm, further confirming that o-phenylenediamine can improve the uniformity of the particles.

[0059] 5. Example 1 The elemental surface scan picture of the scanning electron microscope image of the black phosphorus-carbon-nitrogen composite negative electrode material A is shown in FIG5 . It can be seen that the elements carbon and nitrogen are evenly distributed on the phosphorus element.

[0060] 6. X-ray diffraction results are shown in FIG6 . The black phosphorus-carbon-nitrogen composite negative electrode material A of Example 1 has lower crystallinity and tends to be amorphous, indicating that nitrogen promotes phosphorus hybridization and amorphous particles can achieve a rapid alloying process with lithium ions.

[0061] 7. The X-ray photoelectron spectroscopy (XPS) spectrum analysis results are shown in FIG7 . Compared with o-phenylenediamine, the N 1s peak of the black phosphorus-carbon-nitrogen composite negative electrode material A of Example 1 shifts from approximately 402 eV to approximately 400 eV, indicating the formation of a phosphorus-nitrogen bond.

[0062] 8. The contact angles of the organic electrolyte (1 M LiPF6, 1:1 EC:DEC vol:vol, 5% FEC, 1% VC) on the black phosphorus-carbon-nitrogen composite negative electrode material A of Example 1 and the comparative sample 1 are shown in FIG8 . The contact angle on the black phosphorus-carbon-nitrogen composite negative electrode material A of Example 1 is 27 o The contact angle on the comparative sample 1 is 46 o The contact angle on the black phosphorus-carbon-nitrogen composite negative electrode material A in Example 1 is much smaller than the contact angle on the comparative sample 1. Therefore, the alkaline nitrogen-containing compound o-phenylenediamine accelerates the wetting process between the material and the organic electrolyte.

[0063] The present invention also provides a lithium battery, wherein the negative electrode of the lithium battery is obtained by the preparation method of the black phosphorus-carbon-nitrogen composite negative electrode material.

[0064] Furthermore, lithium batteries include lithium full cells and lithium half cells.

[0065] The present invention assembled lithium-ion half-cells using the methods described in the reference literature (DOI: 10.1016 / j.jpowsour.2022.231025) using the materials prepared in Example 1 and Comparative Example 1. The coulombic efficiency, rate performance, lithium-ion diffusion coefficient, and cycling stability of the corresponding lithium-ion half-cells were tested. The charge / discharge voltage range was 0.01-2.5 V. The coulombic efficiency, rate performance, and cycling stability tests were conducted in a constant current charge / discharge mode with a 5-minute dwell time. The lithium-ion diffusion coefficient test was conducted at a pulse current density of 0.05 A / g for 30 minutes, with a 60-minute dwell time between each pulse.

[0066] 1. Coulombic efficiency results are shown in Figure 9. Comparing the coulombic efficiencies, the black phosphorus-carbon-nitrogen composite anode material A of Example 1 achieved an initial coulombic efficiency of 90.8% at 0.05 A / g, while the initial coulombic efficiency of Comparative Sample 1 was 73.4% at 0.05 A / g. Initial coulombic efficiencies of known phosphorus-based anode materials in the prior art are typically less than 75%. Under the same test conditions, the initial coulombic efficiency of the black phosphorus-carbon-nitrogen composite anode material A of Example 1 was significantly greater than that of Comparative Sample 1 and the initial coulombic efficiencies of previously reported phosphorus-based anode materials, and the coulombic efficiency rapidly rose to 99.5% or above.

[0067] 2. Volume Expansion After the Electrochemical Process As shown in Figure 10, the batteries of Example 1 black phosphorus-carbon-nitrogen composite negative electrode material A and Comparative Sample 1 were disassembled before and after 200 cycles at 0.5 A / g, and corresponding scanning electron microscope images were taken. It can be seen that the thickness of the materials on the current collector was similar before cycling, with Example 1 black phosphorus-carbon-nitrogen composite negative electrode material A being approximately 9.9 μm and Comparative Sample 1 being approximately 9.4 μm. After electrochemical cycling, significant thickness changes occurred, with Example 1 black phosphorus-carbon-nitrogen composite negative electrode material A expanding to approximately 13.4 μm and Comparative Sample 1 expanding significantly to approximately 17.1 μm. Therefore, the volume expansion rate of Example 1 black phosphorus-carbon-nitrogen composite negative electrode material A after the electrochemical process was 35%, far less than the corresponding expansion rate of Comparative Sample 1 (82%), significantly mitigating the volume change of black phosphorus during the alloying process.

[0068] 3. Rate performance evaluation results are shown in Figures 11-13. In Figure 11, the black phosphorus-carbon-nitrogen composite anode material A from Example 1 achieves charge and discharge within the range of 0.2-50 A / g. Even at 50 A / g, the specific capacity remains >300 mAh / g, and the charge and discharge process is completed within 30 s. This demonstrates that the excellent electrochemical performance of the black phosphorus-carbon-nitrogen composite anode material A from Example 1 stems from the synergistic effect between black phosphorus, carbon, and nitrogen, which accelerates the rate of lithium ion insertion and extraction from black phosphorus and the rapid transport of electrons within the material, while also suppressing the volume expansion of the black phosphorus during alloying. Figure 12 includes the rate performance of phosphorus-based negative electrode materials in the prior art, and Figure 13 includes the rate performance of commonly used negative electrode materials in the prior art. Compared with phosphorus-based negative electrode materials and commonly used negative electrode materials, the black phosphorus-carbon-nitrogen composite negative electrode material A in Example 1 has better rate performance, which once again confirms the feasibility of the application of the technical solution of the present invention in fast-charging lithium-ion secondary batteries.

[0069] 4. The lithium ion diffusion coefficient was tested using a constant current intermittent titration technique (reference DOI: 10.1039 / D0NR07386E). As shown in Figure 14, the black phosphorus-carbon-nitrogen composite negative electrode material A of Example 1 has a better lithium ion diffusion coefficient than that of the comparative sample 1 during the charge and discharge process. This indicates that the black phosphorus-carbon-nitrogen composite negative electrode material A of Example 1 derives a lithium nitrogen compound that is a fast lithium ion conductor during the electrochemical process, thereby increasing the rate of lithium ion insertion / extraction of the material.

[0070] 5. Cycling stability was measured. The results, shown in Figure 15, indicate that the black phosphorus-carbon-nitrogen composite negative electrode material A from Example 1 can achieve stable long-term cycling at 40 A / g (each charge or discharge process takes approximately 30 seconds), with a specific capacity of 330 mAh / g after 2000 cycles. Therefore, the lithium battery provided by the present invention completes a rapid charge / discharge cycle within 1 minute.

[0071] Example 2

[0072] S1: Under an argon atmosphere, black phosphorus nanosheets, graphene, and 4,4'-bipyridine were placed in a ball mill, and grinding balls were added. The mass ratio of black phosphorus nanosheets to graphene was 8:2, and the mass ratio of black phosphorus nanosheets to 4,4'-bipyridine was 10:1. The ball milling was implemented by planetary ball milling. The ball mill and grinding balls were both made of zirconia. The diameter of the grinding balls was 5 mm, and the mass ratio of black phosphorus nanosheets to grinding balls was 1:40.

[0073] S2: The mixed material was ball-milled at 300 rpm for 12 h to obtain the black phosphorus-carbon-nitrogen composite negative electrode material B.

[0074] The present invention measured the infrared spectrum of the black phosphorus-carbon-nitrogen composite negative electrode material B in Example 2 (Figure 16), and it can be found that the material has an infrared spectrum at 785 cm -1 The characteristic infrared absorption peak of phosphorus-nitrogen bond appeared nearby, indicating that a chemical bond was formed between black phosphorus and 4,4'-bipyridine during the ball milling process.

[0075] Example 3

[0076] S1: Under a nitrogen atmosphere, black phosphorus film, carbon nanotubes, and 1,3,5-triazine-2,4,6-triamine were placed in a ball mill, and grinding balls were added. The mass ratio of black phosphorus film to carbon nanotubes was 9:1, and the mass ratio of black phosphorus film to 1,3,5-triazine-2,4,6-triamine was 5:1. The ball milling was carried out by drum milling. The ball mill and grinding balls were both made of polyurethane. The diameter of the grinding balls was 20 mm, and the mass ratio of black phosphorus film to grinding balls was 1:20.

[0077] S2: The mixed material was ball-milled at 200 rpm for 72 h to obtain the black phosphorus-carbon-nitrogen composite negative electrode material C.

[0078] The present invention assembled a lithium-ion half-cell using the method described in the reference document (DOI: 10.1016 / j.jpowsour.2022.231025) for the materials prepared in Example 3, and then tested the cycling stability at 1 A / g ( FIG17 ). It was found that the specific capacity of the black phosphorus-carbon-nitrogen composite negative electrode material C in Example 3 after 60 cycles at 1 A / g was as high as 1330 mAh / g, indicating that the technical solution of the present invention has good application prospects in the field of fast charging energy storage.

[0079] Example 4

[0080] S1: Under a nitrogen atmosphere, black phosphorus nanosheets, porous carbon, and m-phenylenediamine were placed in a ball mill, and grinding balls were added at the same time. The mass ratio of black phosphorus nanosheets to porous carbon was 1:20, and the mass ratio of black phosphorus nanosheets to m-phenylenediamine was 100:1. The ball milling was implemented by planetary ball milling. The ball mill and grinding balls were both made of silicon carbide. The diameter of the grinding balls was 10 mm, and the mass ratio of black phosphorus nanosheets to grinding balls was 1:200.

[0081] S2: The mixed material was ball-milled at 600 rpm for 6 h to obtain the black phosphorus-carbon-nitrogen composite negative electrode material D.

[0082] Example 5

[0083] S1: Under a nitrogen atmosphere, black phosphorus quantum dots / black phosphorus film, graphite, and aniline are placed in a ball mill, and grinding balls are added. The mass ratio of black phosphorus quantum dots to black phosphorus film is 1:5, the mass ratio of black phosphorus to graphite is 10:1, and the mass ratio of black phosphorus to aniline is 1:10. The ball milling is implemented by planetary ball milling. The ball mill is made of polytetrafluoroethylene, the grinding balls are made of stainless steel, the diameter of the grinding balls is 1 mm, and the mass ratio of black phosphorus to grinding balls is 1:150.

[0084] S2: The mixed material was ball-milled at a rotation speed of 100 rpm for 48 h to obtain the black phosphorus-carbon-nitrogen composite negative electrode material E.

[0085] Example 6

[0086] S1: Under a nitrogen atmosphere, black phosphorus nanosheets, graphite, and p-phenylenediamine / quinoline are placed in a ball mill, and grinding balls are added. The mass ratio of black phosphorus nanosheets to graphite is 6:4, the mass ratio of black phosphorus nanosheets to p-phenylenediamine / quinoline is 80:1, and the mass ratio of p-phenylenediamine to quinoline is 1:1. The ball milling is implemented by planetary ball milling. The ball mill and grinding balls are both made of agate. The diameter of the grinding balls is 15 mm, and the mass ratio of black phosphorus nanosheets to grinding balls is 1:20.

[0087] S2: The mixed material was ball-milled at a rotation speed of 300 rpm for 40 h to obtain the black phosphorus-carbon-nitrogen composite negative electrode material F.

[0088] Example 7

[0089] S1: Under a nitrogen atmosphere, black phosphorus nanosheets, carbon nanotubes, and 2,4'-bipyridine were placed in a ball mill, and grinding balls were added. The mass ratio of black phosphorus nanosheets to carbon nanotubes was 2:1, and the mass ratio of black phosphorus nanosheets to 2,4'-bipyridine was 40:1. The ball milling was carried out by planetary ball milling. The ball mill and grinding balls were both made of zirconia. The diameter of the grinding balls was 6 mm, and the mass ratio of black phosphorus nanosheets to grinding balls was 1:40.

[0090] S2: The mixed material was ball-milled at 600 rpm for 3 h to obtain the black phosphorus-carbon-nitrogen composite negative electrode material G.

[0091] Example 8

[0092] S1: Under a nitrogen atmosphere, black phosphorus nanosheets, graphene, and acridine / phenanthridine are placed in a ball mill, and grinding balls are added at the same time. The mass ratio of black phosphorus nanosheets to graphene is 1:5, the mass ratio of black phosphorus nanosheets to acridine / phenanthridine is 1:5, and the mass ratio of acridine to phenanthridine is 1:10. The ball milling is implemented by planetary ball milling. The ball mill and grinding balls are both made of polytetrafluoroethylene. The diameter of the grinding balls is 10 mm, and the mass ratio of black phosphorus nanosheets to grinding balls is 1:100.

[0093] S2: The mixed material was ball-milled at a rotation speed of 500 rpm for 24 h to obtain the black phosphorus-carbon-nitrogen composite negative electrode material H.

[0094] Example 9

[0095] S1: Under a nitrogen atmosphere, black phosphorus film, conductive carbon black and 2,3'-bipyridine are placed in a ball mill, and grinding balls are added at the same time. The mass ratio of black phosphorus film to conductive carbon black is 1:10, and the mass ratio of black phosphorus film to 2,3'-bipyridine is 1:1. The ball milling is implemented by drum ball milling. The ball mill is made of polyurethane, and the grinding balls are made of zirconia. The diameter of the grinding balls is 12 mm, and the mass ratio of black phosphorus film to grinding balls is 1:10.

[0096] S2: The mixed material was ball-milled at 200 rpm for 60 h to obtain the black phosphorus-carbon-nitrogen composite negative electrode material I.

[0097] Example 10

[0098] S1: Under a nitrogen atmosphere, micron-sized black phosphorus powder, porous carbon, and 2,2'-bipyridine are placed in a ball mill, and grinding balls are added. The mass ratio of micron-sized black phosphorus powder to porous carbon is 2:1, and the mass ratio of micron-sized black phosphorus powder to 2,2'-bipyridine is 20:1. The ball milling is implemented by planetary ball milling. The ball mill and grinding balls are both made of stainless steel. The diameter of the grinding balls is 2 mm, and the mass ratio of micron-sized black phosphorus powder to grinding balls is 1:150.

[0099] S2: The mixed material was ball-milled at a rotation speed of 100 rpm for 36 h to obtain the black phosphorus-carbon-nitrogen composite negative electrode material J.

[0100] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a black phosphorus-carbon-nitrogen composite negative electrode material, characterized in that: The following steps are involved: S1: In a nitrogen or argon atmosphere, black phosphorus, carbon material and basic nitrogen-containing compound are placed in a ball mill, and grinding balls are added; S2: performing mixed ball milling at a rotation speed of 100-600 rpm for 1-72 h to obtain the black phosphorus-carbon-nitrogen composite negative electrode material.

2. The method for preparing the black phosphorus-carbon-nitrogen composite negative electrode material according to claim 1, characterized in that: The basic nitrogen-containing compound is selected from one or more of o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 2,2'-bipyridine, 2,3'-bipyridine, 2,4'-bipyridine, 4,4'-bipyridine, 1,3,5-triazine-2,4,6-triamine, aniline, quinoline, acridine and phenanthridine.

3. The method for preparing the black phosphorus-carbon-nitrogen composite negative electrode material according to claim 1, characterized in that: The black phosphorus is selected from one or more of micron-sized black phosphorus powder, black phosphorus film, black phosphorus nanosheets and black phosphorus quantum dots.

4. The method for preparing the black phosphorus-carbon-nitrogen composite negative electrode material according to claim 1, characterized in that: The carbon material is selected from one or more of graphene, carbon nanotubes, conductive carbon black, porous carbon, amorphous carbon and graphite.

5. The method for preparing the black phosphorus-carbon-nitrogen composite negative electrode material according to claim 1, characterized in that: The mass ratio of the black phosphorus to the carbon material is 1:20-10:1, and the mass ratio of the black phosphorus to the basic nitrogen-containing compound is 1:10-100:

1.

6. The method for preparing the black phosphorus-carbon-nitrogen composite negative electrode material according to claim 1, characterized in that: Ball milling can be achieved by drum ball milling or planetary ball milling.

7. The method for preparing the black phosphorus-carbon-nitrogen composite negative electrode material according to claim 6, characterized in that: The ball mill and the grinding balls are made of one or more of agate, zirconium oxide, silicon carbide, stainless steel, polyurethane, and polytetrafluoroethylene.

8. The method for preparing the black phosphorus-carbon-nitrogen composite negative electrode material according to claim 7, characterized in that: The mass ratio of the black phosphorus to the grinding balls is 1:200-1:5, and the diameter of the grinding balls is 1-20 mm.

9. A black phosphorus-carbon-nitrogen composite negative electrode material, characterized in that: The method is obtained by the preparation method of the black phosphorus-carbon-nitrogen composite negative electrode material as described in any one of claims 1 to 8.

10. A lithium battery, characterized in that: The negative electrode of the lithium battery is the black phosphorus-carbon-nitrogen composite negative electrode material according to claim 9.

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