Preparation method and application of a ni p3 / fe p4 heterojunction carbon composite material

Abstract

The application provides a preparation method and application of a NiP3 / FeP4 heterojunction carbon composite material, and belongs to the technical field of energy materials. The method comprises the following steps: taking nickel powder, iron powder and red phosphorus powder as raw materials, mixing the raw materials uniformly, and then adding the mixed raw materials into a ball mill tank for ball milling treatment to obtain a phosphorus-rich phase nickel phosphide / iron phosphide NiP3 / FeP4 heterojunction material; and mixing the obtained NiP3 / FeP4 heterojunction material and a carbon material uniformly, and then performing ball milling treatment again to obtain a NiP3 / FeP4 heterojunction carbon composite material. The preparation method provided by the application is prepared by a two-step ball milling method, and has the advantages of simple operation, high efficiency, suitability for industrial large-scale production and the like. The NiP3 / FeP4 heterojunction carbon composite material prepared by the method has good stability, has a high lithium / sodium storage capacity due to the phosphorus-rich phase characteristics, and has a wide application prospect in the fields of lithium / sodium ion batteries, electrocatalysis, capacitors and photoelectric information.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of energy materials, in particular to a preparation method and application of a NiP3 / FeP4 heterojunction carbon composite material. BACKGROUND

[0002] Although renewable energy (such as wind energy, solar energy and tidal energy) can alleviate environmental pollution and energy depletion to a certain extent, it is affected by natural conditions and geographical factors and has randomness and intermittency, and therefore cannot provide continuous and sufficient energy supply. Therefore, in order to realize efficient storage and utilization of renewable energy, it is urgent to develop a new energy storage and conversion device with high energy density and stable output, so as to promote efficient use of renewable energy.

[0003] Compared with secondary batteries such as lead-acid batteries, nickel-cadmium batteries and nickel-hydrogen batteries, lithium ion batteries have the advantages of high energy density, long cycle life, low self-discharge, no memory effect, environmental friendliness and the like, and play an important role in the fields of mobile phones, notebook computers and electric vehicles. At present, the commercial graphite negative electrode of lithium ion batteries has a low specific capacity (372 mAh / g), and therefore cannot meet the urgent demand of the market for lithium ion battery negative electrode materials with high energy density, high power density and long cycle life. Compared with the low capacity of graphite negative electrode materials, the transition metal phosphide negative electrode material with a high phosphorus content has a higher capacity and is a new type of energy storage and conversion material, which has great development potential in the fields of lithium ion batteries and catalysis. Therefore, at the present stage, it is of great practical significance and application prospect to develop a lithium ion battery phosphorus-based negative electrode material with high charge and discharge capacity, high cycle stability and high energy density.

[0004] As a lithium ion battery negative electrode material, the transition metal phosphide with a high phosphorus content has a high theoretical capacity, which is much higher than that of traditional graphite negative electrode materials, which means that it can store more lithium ions under the same mass, thereby significantly improving the energy density of lithium batteries and meeting the demand for high energy density energy storage. In addition, the transition metal phosphide with a high phosphorus content has a low polarization characteristic in the charge and discharge process, which can reduce the energy loss in the electrode reaction and improve the charge and discharge efficiency of the battery. At the same time, it also has a suitable voltage platform, so that the battery can maintain a relatively stable voltage output during the charge and discharge process. In addition to the above advantages, the transition metal phosphide with a high phosphorus content has a variety of lithium storage reaction mechanisms, which helps to maintain the structural stability of the material.

[0005] However, the transition metal phosphide of the phosphorus-rich phase will have a large volume expansion in the charging and discharging process, causing the electrode to be crushed and the specific capacity to rapidly decay. At the same time, due to the volume expansion, the transition metal phosphide will continuously generate a new surface in the cycle process, leading to the decomposition of the electrolyte and the formation of an unstable solid electrolyte interface (SEI). In addition, most of the transition metal phosphide belongs to a semiconductor material, and its conductivity is poor. In the charging and discharging process, the electron conduction speed is slow, especially at a large rate of charging and discharging, the ion migration kinetics is slow, resulting in poor rate performance.

[0006] Therefore, in order to solve the problems of poor conductivity of the transition metal phosphide and volume expansion in the charging and discharging process, it is of great practical significance to propose a preparation method of a NiP3 / FeP4 heterojunction carbon composite material. SUMMARY

[0007] In order to overcome the shortcomings of the prior art, the purpose of the present application is to provide a preparation method and application of a NiP3 / FeP4 heterojunction carbon composite material, which is prepared by a two-step ball milling method, has the advantages of simple operation, high efficiency, and suitability for industrial large-scale production, and the phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material prepared by the method has good stability. Due to its phosphorus-rich phase characteristics, it has a high lithium / sodium storage capacity, and has a wide application prospect in the fields of lithium / sodium ion batteries, electrocatalysis, capacitors, and photoelectric information.

[0008] To achieve the above purpose, the present application provides the following scheme:

[0009] A preparation method of a NiP3 / FeP4 heterojunction carbon composite material, comprising the following steps:

[0010] S1, taking nickel powder, iron powder and red phosphorus powder as raw materials, mixing uniformly and then adding into a ball milling tank for ball milling treatment to obtain a phosphorus-rich phase nickel phosphide / iron phosphide NiP3 / FeP4 heterojunction material;

[0011] S2, mixing the obtained NiP3 / FeP4 heterojunction material and carbon material uniformly, and then performing ball milling treatment again to obtain a NiP3 / FeP4 heterojunction carbon composite material.

[0012] Preferably, in S1, the mass ratio of the nickel powder, the iron powder and the red phosphorus powder is x:1-x:4-x, wherein 0

[0013] Preferably, in S1, the balls used for the ball milling treatment are one or more of zirconia balls, agate balls and stainless steel balls, the ball-to-material ratio is 50-80:1, the rotation speed during the ball milling treatment is 600-800 r / min, the ball milling time is 12-36 h, and the ball milling tank is filled with one or more protective gases such as argon and nitrogen.

[0014] Preferably, in S2, the carbon material is one or more of graphite, superconducting carbon black, carbon nanotubes, carbon fibers, and porous carbon.

[0015] Preferably, in S2, when the ball milling treatment is performed again, the balls used for ball milling are one or more of zirconia balls, agate balls, and stainless steel balls, the ball-to-material ratio is 30-60:1, the ball milling speed is 300-800 r / min, the ball milling time is 6-24 h, and the ball milling tank is filled with one or more of argon, nitrogen, and other protective gases.

[0016] The application also provides a NiP3 / FeP4 heterojunction carbon composite material prepared by the above preparation method of the NiP3 / FeP4 heterojunction carbon composite material.

[0017] The application also provides an application of the NiP3 / FeP4 heterojunction carbon composite material prepared by the above preparation method of the NiP3 / FeP4 heterojunction carbon composite material in a lithium ion battery negative electrode material.

[0018] According to the above, the application composites transition metal phosphide and high-conductivity carbon material to form a phosphorus-rich phase transition metal phosphide carbon composite material, the carbon material can improve the lithium ion and electron transmission rate, inhibit the volume change during lithium intercalation / deintercalation, and maintain the stability of the electrode structure. In addition, the heterojunction formed by different materials has a more stable structure and can better withstand the volume change and stress change during the electrochemical reaction process, thereby improving the stability and cycle life of the electrode. In addition, the heterojunction material has excellent electron transport rate and abundant active sites and shorter ion diffusion path, thereby enhancing the chemical adsorption capacity and electrochemical reaction activity of the electrode material, and synergistically improving the energy storage capacity. During the charging and discharging process, the transmission speed of ions and electrons is faster, which can realize higher charging and discharging rate and meet the demand for fast charging and discharging. Based on the above, the application prepares a phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material by a simple ball milling method and applies it to a lithium ion battery negative electrode.

[0019] In summary, the application has the following technical effects:

[0020] (1) The phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material is successfully synthesized by a simple and efficient two-step ball milling method, and has high lithium storage specific capacity, excellent electron transport rate, abundant active sites and short ion diffusion path. After being combined with the added carbon materials such as graphite, carbon nanotubes and superconducting carbon black, the volume expansion problem in the charging and discharging process can be inhibited, the stability of the electrode structure can be maintained, and the performance of the phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material in lithium / sodium ion batteries, electrocatalysis and other applications can be improved.

[0021] (2) The phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction prepared by ball milling can better withstand the volume change and stress change in the electrochemical reaction process, thereby improving the stability and cycle life of the electrode. In addition, the heterojunction has excellent electron transport rate, abundant active sites and short ion diffusion path, thereby enhancing the chemical adsorption capacity and electrochemical reaction activity of the electrode material, and synergistically improving the energy storage capacity. In the charging and discharging process, the transmission speed of ions and electrons is faster, and a higher charging and discharging rate can be achieved.

[0022] (3) In the preparation process, the conductive carbon material is introduced to construct a conductive network, thereby avoiding the co-embedding of lithium ions and solvents, forming a stable solid electrolyte interface film, thereby inhibiting the low coulomb efficiency caused by electrolyte decomposition, providing a complete and stable chemical and electrochemical reaction interface, solving the problem of poor conductivity, improving the interface charge transfer rate while inhibiting the volume change during lithium insertion / extraction, and maintaining the stability of the electrode structure.

[0023] (4) The phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material prepared by the application can be applied in the fields of lithium / sodium ion batteries, electrocatalysis, electronic information and photoelectric information. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0025] Figure 1 The scanning electron microscope image of the phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction provided for Embodiment 1 of the present application;

[0026] Figure 2X-ray diffraction pattern of the phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction provided for the embodiment 1 of the present application;

[0027] Figure 3 Scanning electron microscope image of the phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite provided for the embodiment 1 of the present application;

[0028] Figure 4 X-ray diffraction pattern of the phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite provided for the embodiment 1 of the present application;

[0029] Figure 5 Rate performance graph of the phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite provided for the embodiment 1 of the present application as a negative electrode of a lithium ion battery;

[0030] Figure 6 Cycle performance graph of the phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite provided for the embodiment 1 of the present application as a negative electrode of a lithium ion battery;

[0031] Figure 7 Scanning electron microscope image of the phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite provided for the embodiment 2 of the present application;

[0032] Figure 8 X-ray diffraction pattern of the phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite provided for the embodiment 2 of the present application;

[0033] Figure 9 X-ray diffraction pattern of the nickel phosphide (NiP2) provided for the comparative example 1 of the present application;

[0034] Figure 10 X-ray diffraction pattern of the ferrous phosphide (FeP) provided for the comparative example 2 of the present application. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present application will be apparently and completely described below with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by one of ordinary skill in the art without any creative work belong to the scope of protection of the present application.

[0036] In order to make the above objectives, characteristics and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with the drawings and specific embodiments.

[0037] The application provides a preparation method of a NiP3 / FeP4 heterojunction carbon composite material, comprising the following steps:

[0038] S1, taking nickel powder, iron powder and red phosphorus powder as raw materials, mixing uniformly, and then adding into a ball mill tank for ball milling treatment to obtain a phosphorus-rich phase nickel phosphide / iron phosphide NiP3 / FeP4 heterojunction material;

[0039] S2, uniformly mixing the obtained NiP3 / FeP4 heterojunction material and carbon material, and then performing ball milling treatment again to obtain a NiP3 / FeP4 heterojunction carbon composite material.

[0040] In S1, the mass ratio of the nickel powder, the iron powder and the red phosphorus powder is x:1-x:4-x, wherein 0

[0041] In S2, the carbon material is one or more of graphite, superconducting carbon black, carbon nanotube, carbon fiber and porous carbon. When the ball milling treatment is performed again, the balls used for ball milling are one or more of zirconia balls, agate balls and stainless steel balls, wherein the ball-to-material ratio is 30-60:1, the ball milling speed is 300-800 r / min, the ball milling time is 6-24 h, and the ball mill tank is filled with one or more protective gases of argon and nitrogen.

[0042] The preparation method provided above is further described in the specific embodiments as follows, and the instrument manufacturers used in the following examples are as follows: planetary ball mill XQM-2-DW, Changsha Tianchuang Powder Technology Co., Ltd.; constant temperature test all-in-one machine MIHW-200-160CH, Shenzhen Xinwei Electronic Co., Ltd.

[0043] Example 1

[0044] The embodiment provides a preparation method of a NiP3 / FeP4 heterojunction carbon composite material, and the steps are as follows:

[0045] (1) Preparation of phosphorus-rich phase nickel phosphide / iron phosphide heterojunction material: 512.8 mg of nickel powder (99.99%), 54.2 mg of iron powder (99.99%), and 933.0 mg of red phosphorus block (99.9%) were used as raw materials. The raw materials were mixed uniformly and then placed in a 50 mL zirconium oxide jar with a ball-to-material ratio of 60:1. The zirconium oxide jar was sealed in a glove box, and after the jar was filled with protective gas, it was taken out and placed in a XQM-2-DW planetary ball mill, which was operated at a speed of 700 r / min for 24 h to obtain the phosphorus-rich phase nickel phosphide / iron phosphide heterojunction material.

[0046] The obtained phosphorus-rich phase nickel phosphide / iron phosphide heterojunction material was characterized by scanning electron microscopy, and the results are shown in FIG. 1. Figure 1

[0047] The obtained phosphorus-rich phase nickel phosphide / iron phosphide heterojunction material was characterized by X-ray diffraction pattern, and the results are shown in FIG. 2. It was found that the XRD diffraction peaks in the pattern matched NiP3 and FeP4 phases, and no other impurity peaks were shown, indicating that the phosphorus-rich phase nickel phosphide / iron phosphide heterojunction material was successfully prepared by the method, specifically a NiP3 / FeP4 heterojunction material. Figure 2

[0048] (2) Preparation of phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material: 1050 mg of phosphorus-rich phase nickel phosphide / iron phosphide heterojunction material was mixed with 450 mg of carbon nanotubes and then placed in a 50 mL zirconium oxide jar with a ball-to-material ratio of 60:1. The zirconium oxide jar was sealed in a glove box, and after the jar was filled with protective gas, it was taken out and placed in a planetary ball mill, which was operated at a speed of 700 r / min for 18 h to obtain the phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material.

[0049] The obtained phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material was characterized by scanning electron microscopy, and the results are shown in FIG. 3. Figure 3

[0050] The obtained phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material was characterized by X-ray diffraction pattern, and the results are shown in FIG. 4. It was found that the XRD diffraction peaks in the pattern matched NiP3 and FeP4 phases, and no other impurity peaks were shown, and a broad characteristic peak of carbon appeared around 20°, indicating that the phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material was successfully prepared by the method. Figure 4

[0051] Example 2

[0052] ​​​​The embodiment provides a preparation method of a NiP3 / FeP4 heterojunction carbon composite material, and steps are as follows:

[0053] (1) Preparation of phosphorus-rich phase nickel phosphide / iron phosphide heterojunction material: 479.9 mg of nickel powder (99.99%), 80.6 mg of iron powder (99.99%) and 939.5 mg of red phosphorus block (99.9%) are used as raw materials, the raw materials are uniformly mixed and then placed in a 50 mL zirconium oxide jar, and the ball-to-material ratio is 60:1. The zirconium oxide jar is sealed in a glove box, and after the jar is filled with protective gas, it is taken out and placed in a XQM-2-DW planetary ball mill at a speed of 700 r / min for 24 h to obtain the phosphorus-rich phase nickel phosphide / iron phosphide heterojunction material.

[0054] (2) Preparation of phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material: 1050 mg of the phosphorus-rich phase nickel phosphide / iron phosphide heterojunction material is mixed with 450 mg of carbon nanotubes and then placed in a 50 mL zirconium oxide jar, and the ball-to-material ratio is 50:1. The zirconium oxide jar is sealed in a glove box, and after the jar is filled with protective gas, it is taken out and placed in a planetary ball mill at a speed of 700 r / min for 18 h to obtain the phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material.

[0055] The obtained phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material is subjected to scanning electron microscope characterization, and the obtained results are shown in Figure 7 .

[0056] The obtained phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material is subjected to X-ray diffraction pattern characterization, and the obtained results are shown in Figure 8 . It is found that the XRD diffraction peaks in the spectrum match NiP3 and FeP4, and no other impurity peaks are shown, and a wide characteristic peak of carbon appears at about 20°, which indicates that the phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material is successfully prepared by the method.

[0057] Example 3

[0058] The embodiment provides a preparation method of a NiP3 / FeP4 heterojunction carbon composite material, and steps are as follows:

[0059] (1) Preparation of phosphorus-rich phase nickel phosphide / iron phosphide heterojunction material: 416.0 mg of nickel powder (99.99%), 131.9 mg of iron powder (99.99%), and 952.1 mg of red phosphorus block (99.9%) were used as raw materials. The raw materials were mixed uniformly and then placed in a 50 mL zirconium oxide jar with a ball-to-material ratio of 60:1. The zirconium oxide jar was sealed in a glove box, and after the jar was filled with protective gas, it was taken out and placed in a XQM-2-DW planetary ball mill, which was operated at a speed of 700 r / min for 24 h to obtain the phosphorus-rich phase nickel phosphide / iron phosphide heterojunction material.

[0060] (2) Preparation of phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material: 1050 mg of phosphorus-rich phase nickel phosphide / iron phosphide heterojunction material was mixed with 450 mg of carbon nanotubes and then placed in a 50 mL zirconium oxide jar with a ball-to-material ratio of 40:1. The zirconium oxide jar was sealed in a glove box, and after the jar was filled with protective gas, it was taken out and placed in a planetary ball mill, which was operated at a speed of 700 r / min for 18 h to obtain the phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material.

[0061] Example 4

[0062] The present embodiment provides a method for preparing a NiP3 / FeP4 heterojunction carbon composite material, the steps of which are as follows:

[0063] (1) Preparation of phosphorus-rich phase nickel phosphide / iron phosphide heterojunction material: 265.5 mg of nickel powder (99.99%), 252.7 mg of iron powder (99.99%), and 981.8 mg of red phosphorus block (99.9%) were used as raw materials. The raw materials were mixed uniformly and then placed in a 50 mL zirconium oxide jar with a ball-to-material ratio of 60:1. The zirconium oxide jar was sealed in a glove box, and after the jar was filled with protective gas, it was taken out and placed in a XQM-2-DW planetary ball mill, which was operated at a speed of 700 r / min for 24 h to obtain the phosphorus-rich phase nickel phosphide / iron phosphide heterojunction material.

[0064] (2) Preparation of phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material: 1050 mg of phosphorus-rich phase nickel phosphide / iron phosphide heterojunction material was mixed with 450 mg of carbon nanotubes and then placed in a 50 mL zirconium oxide jar with a ball-to-material ratio of 40:1. The zirconium oxide jar was sealed in a glove box, and after the jar was filled with protective gas, it was taken out and placed in a planetary ball mill, which was operated at a speed of 700 r / min for 18 h to obtain the phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material.

[0065] Comparative Example 1

[0066] Take 580.4 mg of nickel powder (99.99%) and 919.6 mg of red phosphorus block (99.9%) as raw materials, mix them evenly, and then put them into a 50 mL zirconia jar with a ball-to-material ratio of 60:1. The zirconia jar is sealed in a glove box, filled with protective gas, taken out and put into a planetary ball mill at a speed of 700 r / min for 24 h. The obtained material is characterized by X-ray diffraction pattern, and the results are shown in FIG. 1. The XRD diffraction peaks in the pattern match NiP2, but the nickel triphosphide material (NiP3) cannot be obtained. Figure 9 As shown in FIG. 1, the XRD diffraction peaks in the pattern match NiP2, but the nickel triphosphide material (NiP3) cannot be obtained.

[0067] Comparative Example 2

[0068] Take 465.8 mg of iron powder (99.99%) and 1034.2 mg of red phosphorus block (99.9%) as raw materials, mix them evenly, and then put them into a 50 mL zirconia jar with a ball-to-material ratio of 60:1. The zirconia jar is sealed in a glove box, filled with protective gas, taken out and put into a planetary ball mill at a speed of 700 r / min for 24 h. The obtained material is characterized by X-ray diffraction pattern, and the results are shown in FIG. 2. The XRD diffraction peaks in the pattern match FeP, but the iron tetraphosphide material (FeP4) cannot be obtained. Figure 10 As shown in FIG. 2, the XRD diffraction peaks in the pattern match FeP, but the iron tetraphosphide material (FeP4) cannot be obtained.

[0069] In addition, the following application examples are provided to further illustrate the present application, in which the application examples use the phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material prepared in Example 1 for testing, and the steps are as follows:

[0070] According to the mass ratio of 7:1:2, the prepared phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material, superconducting carbon black and 10% by mass of polyvinylidene fluoride N - methylpyrrolidone solution are mixed, and then mixed evenly in a debubbling machine to obtain an electrode slurry with certain viscosity. The mixed and evenly-mixed electrode slurry is coated on a copper foil, and then the copper foil is dried in a vacuum oven at 80 ℃ for 12 h to obtain an electrode sheet, and then a slicing machine is used to punch the large electrode sheet into a circular electrode sheet with a diameter of 12 mm. In an argon-filled glove box, a CR2032 button cell shell is used to assemble a battery, and the obtained circular electrode sheet, Celgard2500 separator and metal lithium sheet are sequentially placed in the battery shell, and a 1 mol / L lithium hexafluorophosphate ethylene carbonate (EC) and diethyl carbonate (DEC) solution is injected into the battery shell, wherein the volume ratio of EC to DEC is 1:1, and the additives are 5% fluoroethylene carbonate (FEC) and 1% vinylene carbonate (VC). The assembled battery is tightly sealed in a sealing machine, and the assembled battery is left to stand for more than 15 h.

[0071] The electrochemical lithium storage performance of the obtained phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material was tested by using a constant temperature test integrated machine with model MIHW-200-160CH, and the results obtained are shown in Figure 5 As can be seen from the results, it can be found that the phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material has a stable battery charging specific capacity of 1087.71 mAh / g, 968.91 mAh / g, 870.54 mAh / g, 804.96 mAh / g, 742.77 mAh / g, 671.58 mAh / g, and 554.23 mAh / g at current densities of 0.1, 0.2, 0.5, 1, 2, 4, and 8 A / g, respectively, and when the current density is restored from 8 A / g to 0.1 A / g, the charging specific capacity is restored to 895.04 mAh / g. In addition, from Figure 6 As can be seen from the results, it can be found that the phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material has a very good cycle stability, and the reversible specific capacity is 801.3 mAh / g after 395 cycles at a current density of 0.2 A / g, and the capacity retention rate is as high as 85.9%.

[0072] The above-mentioned excellent rate performance and cycle stability are due to the stable structure of the phosphorus-rich phase nickel phosphide / iron phosphide heterojunction, which can better withstand the volume change and stress change during the electrochemical reaction process, thereby improving the stability and cycle life of the electrode. In addition, the phosphorus-rich phase nickel phosphide / iron phosphide heterojunction has excellent electron transport rate and abundant active sites and short ion diffusion path, thereby enhancing the chemical adsorption capacity and electrochemical reaction activity of the electrode material, and synergistically improving the energy storage capacity. In the charging and discharging process, the transmission speed of ions and electrons is faster, which can realize higher charging and discharging rate and meet the demand of fast charging and discharging. The carbon material can improve the lithium ion and electron transport rate, inhibit the volume change during lithium intercalation / deintercalation, and maintain the stability of the electrode structure.

[0073] Comparative Example 3

[0074] 1037.5 mg of tin powder (99.99%), 54.2 mg of iron powder (99.99%), and 933.0 mg of red phosphorus block (99.9%) were used as raw materials, wherein the tin powder replaced the nickel powder in Example 1, and the remaining raw material dosage remained consistent with Example 1. After being uniformly mixed, they were placed in a 50 mL zirconia jar with a ball-to-material ratio of 60:1. The zirconia jar was sealed in a glove box, and after the jar was filled with protective gas, it was taken out and placed in a planetary ball mill with model XQM-2-DW, and ball-milled at a speed of 700 r / min for 24 h to obtain a tin-iron phosphide heterostructure material.

[0075] Take 1050 mg of the tin iron phosphide heterostructure material described above and mix with 450 mg of carbon nanotubes, then put them into a 50 mL zirconia jar, with a ball-to-material ratio of 60:1. Seal the zirconia jar in a glove box, fill the jar with protective gas, then take it out and put it into a planetary ball mill at a speed of 700 r / min for 18 h to obtain a tin iron phosphide carbon composite material.

[0076] The battery assembly and performance test are carried out according to the same application method as in Example 1, and the results obtained are as follows: the tin iron phosphide carbon composite material has a first reversible specific capacity of 685.3 mAh / g at a current density of 0.1 A / g, and a specific capacity of only 210.7 mAh / g at a high rate of 8 A / g; after 100 cycles at a current density of 0.2 A / g, the reversible specific capacity decreases to 298.5 mAh / g, with a capacity retention rate of only 43.5%, and the volume expansion rate during charging and discharging exceeds 350%.

[0077] Compared with Example 1, the specific capacity of Example 1 is 1087.71 mAh / g at 0.1 A / g, 554.23 mAh / g at 8 A / g, and the capacity retention rate after 395 cycles is 85.9%; in Comparative Example 3, only the tin powder is replaced with nickel powder, and the lithium storage capacity, high-rate performance and cycle stability are all significantly reduced, which shows that the metal nickel and tin are not conventional replaceable elements in the phosphorus-rich phase heterojunction carbon composite material, and there is an essential difference between the two: nickel can form a stable NiP3 / FeP4 phosphorus-rich phase heterojunction with iron and phosphorus, which cooperates with carbon material to effectively inhibit volume expansion and improve electron / ion transmission efficiency; after replacing with tin, similar phosphorus-rich phase structure cannot be formed, resulting in a significant decline in performance.

[0078] Therefore, the preparation method and application of the above-mentioned NiP3 / FeP4 heterojunction carbon composite material are prepared by a two-step ball milling method, which has the advantages of simple operation, high efficiency, and suitability for industrial large-scale production. The phosphorus-rich phase nickel phosphide / iron phosphide heterojunction carbon composite material prepared by the method has good stability, and due to its phosphorus-rich phase characteristics, it has a high lithium / sodium storage capacity, and has a wide application prospect in the fields of lithium / sodium ion batteries, electrocatalysis, capacitors and photoelectric information.

[0079] The embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other.

[0080] The principles and implementation modes of the present application are described by using specific examples in this paper, and the above examples are only used to help understand the method and core idea of the present application; at the same time, for those skilled in the art, according to the idea of the present application, the specific implementation mode and application range will be changed. In summary, the content of the specification should not be understood as a limitation of the present application.

Claims

1. A method for preparing a NiP3 / FeP4 heterojunction carbon composite material, characterized in that, The method comprises the following steps: S1, taking nickel powder, iron powder and red phosphorus powder as raw materials, mixing uniformly, and then adding into a ball mill tank for ball milling treatment to obtain a phosphorus-rich phase nickel phosphide / iron phosphide NiP3 / FeP4 heterojunction material; S2, mixing the obtained NiP3 / FeP4 heterojunction material and carbon material uniformly, and then performing ball milling treatment again to obtain a NiP3 / FeP4 heterojunction carbon composite material.

2. The preparation method of the NiP3 / FeP4 heterojunction carbon composite material according to claim 1, characterized in that, In S1, the balls used for the ball milling treatment are one or more of zirconia balls, agate balls and stainless steel balls, wherein the ball-to-material ratio is 50-80:1, the rotation speed during the ball milling treatment is 600-800 r / min, the ball milling time is 12-36 h, and the ball mill tank is filled with one or more protective gases selected from argon and nitrogen.

3. The preparation method of the NiP3 / FeP4 heterojunction carbon composite material according to claim 1, characterized in that, In S2, the carbon material is one or more of graphite, superconducting carbon black, carbon nanotubes, carbon fibers and porous carbon.

4. The preparation method of the NiP3 / FeP4 heterojunction carbon composite material according to claim 1, characterized in that, In S2, when the ball milling treatment is performed again, the balls used for the ball milling are one or more of zirconia balls, agate balls and stainless steel balls, wherein the ball-to-material ratio is 30-60:1, the ball milling rotation speed is 300-800 r / min, the ball milling time is 6-24 h, and the ball mill tank is filled with one or more protective gases selected from argon and nitrogen.

5. A NiP3 / FeP4 heterojunction carbon composite material prepared by the preparation method of the NiP3 / FeP4 heterojunction carbon composite material according to any one of claims 1-4.

6. Application of a NiP3 / FeP4 heterojunction carbon composite material prepared by the preparation method of the NiP3 / FeP4 heterojunction carbon composite material according to any one of claims 1-4 to a lithium ion battery negative electrode material.

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