Preparation method and application of NiP3 / FeP4 heterojunction carbon composite material

Abstract

The invention provides a preparation method and application of a NiP3 / FeP4 heterojunction carbon composite material, and belongs to the technical field of energy materials. Comprising the following steps: by taking nickel powder, iron powder and red phosphorus powder as raw materials, uniformly mixing 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; and uniformly mixing the obtained NiP3 / FeP4 heterojunction material with a carbon material, and then carrying out ball milling treatment again to obtain the NiP3 / FeP4 heterojunction carbon composite material. The preparation method provided by the invention adopts a two-step ball milling method for preparation, has the advantages of simplicity in operation, high efficiency, suitability for industrial large-scale production and the like, and the NiP3 / FeP4 heterojunction carbon composite material prepared by adopting the method has good stability, has higher lithium / sodium storage capacity due to the phosphorus-rich phase characteristic, and is suitable for industrial large-scale production. The method has a wide application prospect in the fields of lithium / sodium ion batteries, electro-catalysis, capacitors, photoelectric information and the like.

Description

Technical Field

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

[0002] While renewable energy sources (wind, solar, tidal, and other sources) can alleviate environmental pollution and energy depletion to a certain extent, they are subject to randomness and intermittent nature, influenced by natural conditions and geographical factors, and cannot provide a continuous and sufficient energy supply. Therefore, to achieve efficient storage and utilization of renewable energy, there is an urgent need to develop new energy storage and conversion devices with high energy density and stable output to promote the efficient use of renewable energy.

[0003] Compared to secondary batteries such as lead-acid, nickel-cadmium, and nickel-metal hydride batteries, lithium-ion batteries (LIBs) offer advantages such as high energy density, long cycle life, low self-discharge, no memory effect, and environmental friendliness. They play a vital role in applications such as mobile phones, laptops, and electric vehicles. Currently, commercially available graphite anodes for LIBs suffer from a low specific capacity (372 mAh / g), failing to meet the urgent market demand for LIB anode materials with high energy density, high power density, and long cycle life. Compared to the low capacity of graphite anode materials, phosphorus-rich transition metal phosphide anode materials offer higher capacity and represent an emerging class of energy storage and conversion materials with great potential for development in LIBs, catalysis, and other fields. Therefore, the development of phosphorus-based anode materials for LIBs with high charge / discharge capacity, high cycle stability, and high energy density is of great practical significance and promising for future applications.

[0004] As a negative electrode material for lithium-ion batteries, phosphorus-rich transition metal phosphides have a high theoretical capacity, much higher than traditional graphite negative electrode materials, which means that at the same mass, they can store more lithium ions, thereby significantly improving the energy density of lithium batteries and meeting the needs of high energy density energy storage. In addition, phosphorus-rich transition metal phosphides have low polarization characteristics during the charge and discharge process, which can reduce energy loss in the electrode reaction and improve the charge and discharge efficiency of the battery. At the same time, they also have a suitable voltage platform, which enables the battery to maintain a relatively stable voltage output during the charge and discharge process. In addition to the advantages mentioned above, phosphorus-rich transition metal phosphides have a variety of lithium storage reaction mechanisms, which helps them maintain the structural stability of the material.

[0005] However, phosphorus-rich transition metal phosphides undergo significant volume expansion during the charge and discharge process, causing electrode shattering and rapid capacity decay. Simultaneously, due to this volume expansion, transition metal phosphides continuously create new surfaces during cycling, leading to electrolyte decomposition and the formation of an unstable solid electrolyte interface (SEI). Furthermore, most transition metal phosphides are semiconductor materials with poor electrical conductivity. During charge and discharge, electron conduction is slow, especially at high rates, where ion migration kinetics are sluggish, resulting in poor rate performance.

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

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

[0008] To achieve the above object, the present invention provides the following solutions: A method for preparing a NiP3 / FeP4 heterojunction carbon composite material comprises the following steps: S1, nickel powder, iron powder and red phosphorus powder are mixed and then added into a ball mill for ball milling to obtain a phosphorus-rich nickel phosphide / iron phosphide NiP3 / FeP4 heterojunction material; S2. Evenly mix the obtained NiP3 / FeP4 heterojunction material and carbon material, and then perform ball milling again to obtain a NiP3 / FeP4 heterojunction carbon composite material.

[0009] Preferably, in S1, the molar ratio of the nickel powder, iron powder and red phosphorus powder is x:1-x:4-x, wherein 0<x<1.

[0010] Preferably, 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 milling tank is filled with one or more protective gases selected from argon and nitrogen.

[0011] Preferably, in S2, the carbon material is one or more of graphite, superconducting carbon black, carbon nanotubes, carbon fibers, and porous carbon.

[0012] 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, 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 milling tank is filled with one or more protective gases of argon and nitrogen.

[0013] The present invention also provides a NiP3 / FeP4 heterojunction carbon composite material prepared by the above-mentioned preparation method of the NiP3 / FeP4 heterojunction carbon composite material.

[0014] The present invention also provides an application of the NiP3 / FeP4 heterojunction carbon composite material prepared by the above-mentioned preparation method of the NiP3 / FeP4 heterojunction carbon composite material in lithium ion battery negative electrode materials.

[0015] Based on the above, the present invention combines transition metal phosphides with high-conductivity carbon materials to form a phosphorus-rich transition metal phosphide-carbon composite material. The carbon material can improve the lithium ion and electron transport rate, suppress volume changes during lithium insertion and extraction, and maintain the stability of the electrode structure. Furthermore, the heterojunction formed by the different materials has a more stable structure, better able to withstand volume changes and stress changes during electrochemical reactions, thereby improving the stability and cycle life of the electrode. Furthermore, the heterojunction material has excellent electron transport rate, abundant active sites, and short ion diffusion paths, thereby enhancing the chemical adsorption capacity and electrochemical reaction activity of the electrode material, synergistically improving the energy storage capacity. During the charge and discharge process, the ion and electron transport speed is faster, enabling higher charge and discharge rates, meeting the requirements of fast charge and discharge. Based on the above, the present invention prepares a phosphorus-rich nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material through a simple ball milling method and applies it to the negative electrode of lithium-ion batteries.

[0016] In summary, the present invention discloses the following technical effects: (1) The present invention successfully synthesized a phosphorus-rich nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material through a simple and efficient two-step ball milling method. The composite material has a high lithium storage capacity, excellent electron transport rate, abundant active sites, and a short ion diffusion path. When combined with carbon materials such as graphite, carbon nanotubes, and superconducting carbon black, it can suppress volume expansion during charge and discharge, maintain the stability of the electrode structure, and improve the performance of the phosphorus-rich nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material in applications such as lithium / sodium ion batteries and electrocatalysis.

[0017] (2) The phosphorus-rich nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction prepared by ball milling in the present invention can better withstand volume changes and stress changes during electrochemical reactions, thereby improving the stability and cycle life of the electrode. In addition, the heterojunction has excellent electron transport rate, abundant active sites, and a 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. During the charge and discharge process, the transmission speed of ions and electrons is faster, which can achieve a higher charge and discharge rate.

[0018] (3) The present invention introduces conductive carbon materials during the preparation process to construct a conductive network, thereby avoiding the co-embedding of lithium ions and solvents and forming a stable solid electrolyte interface film, thereby suppressing the low Coulomb efficiency caused by the decomposition of the electrolyte, providing a structurally complete and stable chemical and electrochemical reaction interface, solving the problem of poor conductivity, improving the interfacial charge transfer rate while suppressing the volume change during lithium insertion / extraction, and maintaining the stability of the electrode structure.

[0019] (4) The phosphorus-rich nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material prepared by the present invention can be used in the fields of lithium / sodium ion batteries, electrocatalysis, electronic information and optoelectronic information. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 A scanning electron microscope image of a phosphorus-rich nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction provided in Example 1 of the present invention; Figure 2 The X-ray diffraction pattern of the phosphorus-rich nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction provided in Example 1 of the present invention; Figure 3 A scanning electron microscope image of the phosphorus-rich nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material provided in Example 1 of the present invention; Figure 4 The X-ray diffraction pattern of the phosphorus-rich nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material provided in Example 1 of the present invention; Figure 5A rate capability graph of a phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material provided for the embodiment 1 of the present application as a negative electrode of a lithium ion battery; Figure 6 A cycle performance graph of a phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material provided for the embodiment 1 of the present application as a negative electrode of a lithium ion battery; Figure 7 A scanning electron microscope graph of a phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material provided for the embodiment 2 of the present application; Figure 8 An X-ray diffraction pattern of a phosphorus-rich phase nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material provided for the embodiment 2 of the present application; Figure 9 An X-ray diffraction pattern of nickel phosphide (NiP2) provided for the comparative example 1 of the present application; Figure 10 An X-ray diffraction pattern of ferrous phosphide (FeP) provided for the comparative example 2 of the present application. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be apparently and completely described below with reference to 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 a person of ordinary skill in the art without any creative work fall within the protection scope of the present application.

[0023] In order to make the above objectives, characteristics and advantages of the present application more apparent, comprehensible and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0024] The present application provides a preparation method of a NiP3 / FeP4 heterojunction carbon composite material, comprising 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 pot for ball milling treatment to obtain a phosphorus-rich phase nickel phosphide / iron phosphide NiP3 / FeP4 heterojunction material; 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.

[0025] In S1, the molar ratio of the nickel powder, iron powder, and red phosphorus powder is x:1-x:4-x, where 0<x<1. The balls used in the ball milling process are one or more of zirconia balls, agate balls, and stainless steel balls, with a ball-to-material ratio of 50-80:1. The ball milling process is performed at a rotation speed of 600-800 rpm for a ball milling time of 12-36 hours. The ball milling tank is filled with one or more protective gases selected from argon and nitrogen.

[0026] In S2, the carbon material is one or more of graphite, superconducting carbon black, carbon nanotubes, carbon fibers, and porous carbon. When ball milling 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 to 60:1, the ball milling speed is 300 to 800 rpm, the ball milling time is 6 to 24 hours, and the ball milling tank is filled with one or more protective gases selected from argon and nitrogen.

[0027] The preparation method provided above is further described below with specific implementation methods. The manufacturers of the instruments used in the following examples are as follows: planetary ball mill XQM-2-DW, Changsha Tianchuang Powder Technology Co., Ltd.; constant temperature testing all-in-one machine MIHW-200-160CH, Shenzhen Xinwell Electronics Co., Ltd.

[0028] Example 1 This embodiment provides a method for preparing a NiP3 / FeP4 heterojunction carbon composite material, the steps of which are as follows: (1) Preparation of phosphorus-rich nickel phosphide / iron phosphide heterojunction material: 512.8 mg nickel powder (99.99%), 54.2 mg iron powder (99.99%), and 933.0 mg red phosphorus block (99.9%) were used as raw materials. The raw materials were mixed evenly and 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 filled with protective gas. After that, it was taken out and placed in an XQM-2-DW planetary ball mill at 700 r / min for 24 h to obtain a phosphorus-rich nickel phosphide / iron phosphide heterojunction material.

[0029] The obtained phosphorus-rich nickel phosphide / iron phosphide heterojunction material was characterized by scanning electron microscopy, and the results were as follows: Figure 1 shown.

[0030] The obtained phosphorus-rich nickel phosphide / iron phosphide heterojunction material was characterized by X-ray diffraction patterns, and the results were as follows: Figure 2 As shown, it was found that the XRD diffraction peaks in the spectrum all matched those of NiP3 and FeP4, and no other impurity peaks were shown, indicating that the method successfully prepared phosphorus-rich nickel phosphide / iron phosphide heterojunction materials, specifically NiP3 / FeP4 heterojunction materials.

[0031] (2) Preparation of phosphorus-rich nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material: 1050 mg of phosphorus-rich nickel phosphide / iron phosphide heterojunction material was mixed with 450 mg of carbon nanotubes and 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 filled with protective gas. The jar was then taken out and placed in a planetary ball mill and ball milled at 700 r / min for 18 h to obtain a phosphorus-rich nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material.

[0032] The obtained phosphorus-rich nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material was characterized by scanning electron microscopy, and the results were as follows: Figure 3 shown.

[0033] The obtained phosphorus-rich nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material was characterized by X-ray diffraction patterns, and the results were as follows: Figure 4 As shown, it was found that the XRD diffraction peaks in the spectrum all matched those of NiP3 and FeP4, and no other impurity peaks were shown. A broad characteristic peak of carbon appeared at around 20°, indicating that this method successfully prepared phosphorus-rich nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite materials.

[0034] Example 2 This embodiment provides a method for preparing a NiP3 / FeP4 heterojunction carbon composite material, the steps of which are as follows: (1) Preparation of phosphorus-rich nickel phosphide / iron phosphide heterojunction material: 479.9 mg nickel powder (99.99%), 80.6 mg iron powder (99.99%), and 939.5 mg red phosphorus block (99.9%) were used as raw materials. The raw materials were mixed evenly and 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 filled with protective gas. After that, it was taken out and placed in an XQM-2-DW planetary ball mill at 700 r / min for 24 h to obtain a phosphorus-rich nickel phosphide / iron phosphide heterojunction material.

[0035] (2) Preparation of phosphorus-rich nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material: 1050 mg of phosphorus-rich nickel phosphide / iron phosphide heterojunction material was mixed with 450 mg of carbon nanotubes and placed in a 50 mL zirconia jar with a ball-to-material ratio of 50:1. The zirconia jar was sealed in a glove box and filled with protective gas. The jar was then taken out and placed in a planetary ball mill and ball milled at 700 r / min for 18 h to obtain a phosphorus-rich nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material.

[0036] The obtained phosphorus-rich nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material was characterized by scanning electron microscopy, and the results were as follows: Figure 7 shown.

[0037] The obtained phosphorus-rich nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material was characterized by X-ray diffraction patterns, and the results were as follows: Figure 8 As shown, it was found that the XRD diffraction peaks in the spectrum all matched those of NiP3 and FeP4, and no other impurity peaks were shown. A broad characteristic peak of carbon appeared at around 20°, indicating that this method successfully prepared phosphorus-rich nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite materials.

[0038] Example 3 This embodiment provides a method for preparing a NiP3 / FeP4 heterojunction carbon composite material, the steps of which are as follows: (1) Preparation of phosphorus-rich nickel phosphide / iron phosphide heterojunction material: 416.0 mg nickel powder (99.99%), 131.9 mg iron powder (99.99%), and 952.1 mg red phosphorus block (99.9%) were used as raw materials. The raw materials were mixed evenly and 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 filled with protective gas. After that, it was taken out and placed in an XQM-2-DW planetary ball mill at 700 r / min for 24 h to obtain a phosphorus-rich nickel phosphide / iron phosphide heterojunction material.

[0039] (2) Preparation of phosphorus-rich nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material: 1050 mg of phosphorus-rich nickel phosphide / iron phosphide heterojunction material was mixed with 450 mg of carbon nanotubes and placed in a 50 mL zirconia can with a ball-to-material ratio of 40:1. The zirconia can was sealed in a glove box and filled with protective gas. The can was then taken out and placed in a planetary ball mill and ball milled at 700 r / min for 18 h to obtain a phosphorus-rich nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material.

[0040] Example 4 This embodiment provides a method for preparing a NiP3 / FeP4 heterojunction carbon composite material, the steps of which are as follows: (1) Preparation of phosphorus-rich nickel phosphide / iron phosphide heterojunction material: 265.5 mg nickel powder (99.99%), 252.7 mg iron powder (99.99%), and 981.8 mg red phosphorus block (99.9%) were used as raw materials. The raw materials were mixed evenly and 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 filled with protective gas. After that, it was taken out and placed in an XQM-2-DW planetary ball mill at 700 r / min for 24 h to obtain a phosphorus-rich nickel phosphide / iron phosphide heterojunction material.

[0041] (2) Preparation of phosphorus-rich nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composites: 1200 mg of phosphorus-rich nickel phosphide / iron phosphide heterojunction material was mixed with 300 mg of carbon nanotubes and 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 filled with protective gas. The jar was then taken out and placed in a planetary ball mill and ball milled at 700 r / min for 18 h to obtain a phosphorus-rich nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material.

[0042] Comparative Example 1 580.4 mg of nickel powder (99.99%) and 919.6 mg of red phosphorus (99.9%) were mixed and placed in a 50 mL zirconia jar with a ball-to-batch ratio of 60:1. The zirconia jar was sealed in a glove box, filled with protective gas, and then removed and milled in a planetary ball mill at 700 rpm for 24 hours. The resulting material was characterized by X-ray diffraction patterns, as shown in the following table. Figure 9 As shown, the XRD diffraction peaks in the spectrum match those of NiP2, but nickel triphosphide material (NiP3) cannot be obtained.

[0043] Comparative Example 2 465.8 mg of iron powder (99.99%) and 1034.2 mg of red phosphorus (99.9%) were mixed and 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, filled with protective gas, and then removed and milled in a planetary ball mill at 700 rpm for 24 hours. The resulting material was characterized by X-ray diffraction patterns, as shown below. Figure 10 As shown, the XRD diffraction peaks in the spectrum match those of FeP, but iron tetraphosphide material (FeP4) cannot be obtained.

[0044] In addition, an application example is provided below to illustrate the present invention in detail. In this application example, the phosphorus-rich nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material prepared in Example 1 is used for testing. The steps are as follows: The prepared phosphorus-rich nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material, superconducting carbon black and polyvinylidene fluoride with a mass fraction of 10% were weighed according to a mass ratio of 7:1:2. N -methylpyrrolidone solution and mixed thoroughly in a degassing machine to obtain a viscous electrode slurry. The mixed electrode slurry was coated onto copper foil, which was then dried in a vacuum oven at 80°C for 12 hours to obtain electrode sheets. The large electrode sheets were then punched into circular pieces with a diameter of 12 mm using a slicer. Batteries were assembled in a CR2032 coin cell case in an argon-filled glove box. The circular electrode sheets, Celgard 2500 separator, and lithium metal sheet were placed into the case in that order. A 1 mol / L lithium hexafluorophosphate solution in ethylene carbonate (EC) and diethyl carbonate (DEC) was then injected, with a volume ratio of 1:1 for EC and DEC. Additives included 5% fluoroethylene carbonate (FEC) and 1% vinylene carbonate (VC). The assembled battery was sealed tightly in a sealing machine and allowed to rest for at least 15 hours.

[0045] The electrochemical lithium storage performance of the obtained phosphorus-rich nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material was tested using a constant temperature test all-in-one machine model MIHW-200-160CH. The results are as follows: Figure 5 As shown in the figure, it can be found that the battery charge capacity of the phosphorus-rich nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material is stable at current densities of 0.1, 0.2, 0.5, 1, 2, 4 and 8 A / g at 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, respectively. When the current density is restored from 8 A / g to 0.1 A / g, its charge capacity is restored to 895.04 mAh / g. In addition, from Figure 6 It can be seen that the phosphorus-rich nickel phosphide / iron phosphide (NiP3 / FeP4) heterojunction carbon composite material has good cycle stability. After 395 cycles at a current density of 0.2 A / g, the reversible specific capacity is 801.3 mAh / g and the capacity retention rate is as high as 85.9%.

[0046] The excellent rate performance and cycle stability provided above are due to the stable structure of the phosphorus-rich nickel phosphide / iron phosphide heterojunction, which can better withstand volume changes and stress changes during the electrochemical reaction, thereby improving the stability and cycle life of the electrode. In addition, the phosphorus-rich nickel phosphide / iron phosphide heterojunction has an excellent electron transport rate, abundant active sites and a 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 charge and discharge process, the transmission speed of ions and electrons is faster, and a higher charge and discharge rate can be achieved to meet the needs of fast charge and discharge. Carbon materials can increase the lithium ion and electron transmission rate, inhibit volume changes during lithium insertion / extraction, and maintain the stability of the electrode structure.

[0047] Comparative Example 3 1037.5 mg of tin powder (99.99%), 54.2 mg of iron powder (99.99%), and 933.0 mg of red phosphorus (99.9%) were used as raw materials. The tin powder replaced the nickel powder in Example 1, and the remaining raw materials were used in the same amounts as in Example 1. After mixing thoroughly, the mixture was placed in a 50 mL zirconia canister with a ball-to-material ratio of 60:1. The zirconia canister was sealed in a glove box and filled with protective gas. The canister was then removed and milled in an XQM-2-DW planetary ball mill at 700 rpm for 24 hours to obtain a tin-iron phosphide heterostructure material.

[0048] 1050 mg of the tin-iron-phosphide heterostructure material was mixed with 450 mg of carbon nanotubes and placed in a 50 mL zirconia jar at a ball-to-material ratio of 60:1. The zirconia jar was sealed in a glove box and filled with protective gas. The jar was then removed and milled in a planetary ball mill at 700 rpm for 18 hours to obtain a tin-iron-phosphide-carbon composite material.

[0049] The battery was assembled and performance tested according to the same application method as in Example 1, and the results were as follows: the tin-iron-phosphide-carbon composite material had an initial 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 dropped to 298.5 mAh / g, the capacity retention rate was only 43.5%, and the volume expansion rate exceeded 350% during charge and discharge.

[0050] Compared with Example 1, Example 1 has a specific capacity of 1087.71 mAh / g at 0.1 A / g and 554.23 mAh / g at 8 A / g, and a capacity retention rate of 85.9% after 395 cycles; Comparative Example 3 only replaces nickel powder with tin powder, and its lithium storage specific capacity, high-rate performance and cycle stability are significantly reduced, which shows that metallic nickel and tin are not conventional replaceable elements in phosphorus-rich heterojunction carbon composite materials, and there is an essential difference between the two: nickel can form a stable NiP3 / FeP4 phosphorus-rich heterojunction with iron and phosphorus, and cooperate with carbon materials to effectively inhibit volume expansion and improve electron / ion transmission efficiency; while tin cannot form a similar phosphorus-rich phase structure after replacement, resulting in a significant degradation of performance.

[0051] Therefore, the above-mentioned preparation method and application of a NiP3 / FeP4 heterojunction carbon composite material is adopted, which is prepared by a two-step ball milling method, and has the advantages of simple operation, high efficiency, and suitability for industrial large-scale production. The phosphorus-rich nickel phosphide / iron phosphide heterojunction carbon composite material prepared by this method has good stability. Due to its phosphorus-rich phase characteristics, it has a higher lithium / sodium storage capacity, and has broad application prospects in lithium / sodium ion batteries, electrocatalysis, capacitors, optoelectronic information and other fields.

[0052] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0053] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A method for preparing a NiP3 / FeP4 heterojunction carbon composite material, characterized in that: The following steps are involved: S1, nickel powder, iron powder and red phosphorus powder are mixed and then added into a ball mill for ball milling to obtain a phosphorus-rich nickel phosphide / iron phosphide NiP3 / FeP4 heterojunction material; S2. Evenly mix the obtained NiP3 / FeP4 heterojunction material and carbon material, and then perform ball milling again to obtain a NiP3 / FeP4 heterojunction carbon composite material.

2. The method for preparing a NiP3 / FeP4 heterojunction carbon composite material according to claim 1, characterized in that: In S1, the molar ratio of the nickel powder, iron powder and red phosphorus powder is x:1-x:4-x, wherein 0<x<1.

3. The method for preparing a 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 milling tank is filled with one or more protective gases of argon and nitrogen.

4. The method for preparing a 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.

5. The method for preparing a 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 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 milling tank is filled with one or more protective gases of argon and nitrogen.

6. A NiP3 / FeP4 heterojunction carbon composite material prepared according to the method for preparing a NiP3 / FeP4 heterojunction carbon composite material according to any one of claims 1 to 5.

7. Use of the NiP3 / FeP4 heterojunction carbon composite material prepared according to the method for preparing the NiP3 / FeP4 heterojunction carbon composite material according to any one of claims 1 to 5 in a negative electrode material for a lithium ion battery.

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