A phosphorus-carbon-magnesium boride composite material, an electrode active material and a phosphorus-based electrode sheet, and a preparation method and application thereof
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-15
- Publication Date
- 2026-08-11
AI Technical Summary
2019年以来，快充磷基负极实现了极快充电(XFC)的目标，10分钟充电时间即可实现大于80%的容量保持率，然而，磷基负极材料自身导电性较差，且在充放电循环过程中体积变化大，这限制了其倍率性能和循环稳定性
[0018] (1) By introducing magnesium boride into the phosphorus-carbon composite material, this invention can simultaneously achieve excellent cycle stability and excellent air stability. Boron can effectively accelerate the transport of electrons and lithium ions, greatly improving the structural stability of the composite material. Therefore, the phosphorus-carbon-magnesium boride electrode has excellent electrochemical performance, including high lithium storage capacity, long cycle stability and impressive rate performance, which is far superior to red phosphorus-carbon materials and most reported phosphorus-based anodes.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of electrode materials technology, and in particular to a phosphorus-carbon-boron magnesium composite material, an electrode active material, and a phosphorus-based electrode sheet, as well as their preparation methods and applications. Background Technology
[0002] New energy storage devices have been widely studied for their practical applications in electric vehicles, mobile communications, and portable electronic devices, and their importance is increasingly prominent. Both the scientific and industrial communities are committed to exploring and developing new battery materials with high energy density, environmental friendliness, economic efficiency, and ease of fabrication. Currently widely used graphite anode materials, although theoretically possessing a specific capacity potential of up to 372 mAh / g, often have their specific capacity limited to the range of 300 to 330 mAh / g in practical applications. Furthermore, graphite electrodes suffer significant irreversible capacity loss during the initial charge-discharge cycle and exhibit insufficient performance under high-rate discharge conditions. These technical bottlenecks severely hinder the widespread adoption and in-depth application of graphite anode materials in high-energy-density applications, particularly in the electric vehicle industry. In recent years, the exploration and development of alloy conversion anode materials with high theoretical capacity, excellent cycle stability, and good performance has been a significant research hotspot in the scientific research field.
[0003] As an emerging two-dimensional material, phosphorus has demonstrated great potential as an anode material for lithium-ion batteries due to its excellent electronic / ionic conductivity and its theoretical capacity of up to 2596 mAh / g in lithium / sodium / potassium ion batteries. The graphite-like layered structure of black phosphorus provides favorable conditions for the rapid shuttle of ions. Since 2019, fast-charging phosphorus-based anodes have achieved the goal of ultra-fast charging (XFC), achieving a capacity retention rate of over 80% in just 10 minutes of charging. However, phosphorus-based anode materials themselves have poor conductivity and large volume changes during charge-discharge cycles, which limits their rate performance and cycle stability. Summary of the Invention
[0004] To address the aforementioned technical problems, this invention provides a magnesium phosphorus-carbon-boride composite material and its preparation method, which exhibits excellent electrical conductivity.
[0005] A further technical problem to be solved by the present invention is to provide an electrode active material comprising the above-mentioned phosphorus-carbon-boride magnesium composite material and a phosphorus-based electrode sheet.
[0006] To achieve the above objectives, the present invention adopts the following technical solution:
[0007] A phosphorus-carbon-magnesium boride composite material possesses a three-dimensional continuous conductive network and a three-dimensional ion transport network. The three-dimensional continuous conductive network is constructed by carbon-boron and phosphorus-boron covalent bonds formed between magnesium boride and phosphorus or carbon. The three-dimensional ion transport network is formed by the interconnection of interlayer channels in magnesium boride with ion insertion channels in phosphorus and pores in the carbon matrix. The three-dimensional continuous conductive network enhances the conductivity of the phosphorus-carbon material and reduces interfacial resistance. The three-dimensional ion transport network, combined with the temporary adsorption of lithium ions by magnesium ions on the magnesium boride surface, lowers the lithium ion insertion energy barrier and accelerates lithium storage kinetics.
[0008] The phosphorus-carbon-magnesium boride composite material is composed of the following components by mass fraction: 40-70% phosphorus, 20-60% carbon materials, and 5-10% magnesium boride.
[0009] Wherein, the phosphorus is at least one of red phosphorus, black phosphorus or purple phosphorus; the carbon material is at least one of graphene, carbon nanotubes, soft carbon and porous carbon; the magnesium boride is a nano-sized powder with a particle size of 20~80 nm and a purity ≥99.5%.
[0010] The preparation method of the above-mentioned phosphorus-carbon-magnesium boride composite material includes the following steps: using an appropriate amount of a mixture of high-purity phosphorus powder, magnesium boride powder and carbon material as raw materials, and performing high-energy ball milling treatment to obtain the composite material.
[0011] The ball-to-material ratio in the high-energy ball milling process is 40-100:1, the rotation speed is 300-500 r / min, and the milling time is 12-48 h.
[0012] The ball tank and ball used in the high-energy ball milling process are made of at least one of zirconium oxide, agate, and stainless steel, and the ball tank is filled with an inert reactive gas.
[0013] The mass ratio of phosphorus powder, carbon material and magnesium boride powder is (40~70):(20~60):(5~10).
[0014] An electrode active material comprising the above-mentioned magnesium phosphorus-carbon-boride composite material, a conductive agent, and a binder, wherein the mass ratio of the magnesium phosphorus-carbon-boride composite material, the conductive agent, and the binder is (7~9):(0.5~2):(0.5~1).
[0015] A phosphorus-based electrode sheet includes a current collector and an electrode active material coated on the surface of the current collector, wherein the electrode active material is the aforementioned electrode active material.
[0016] The aforementioned phosphorus-based electrode sheets are used as negative electrode sheets in solid-state batteries, lithium-ion batteries, or lithium-ion capacitors.
[0017] The beneficial effects of this invention are as follows:
[0018] (1) By introducing magnesium boride into the phosphorus-carbon composite material, this invention can simultaneously achieve excellent cycle stability and excellent air stability. Boron can effectively accelerate the transport of electrons and lithium ions, greatly improving the structural stability of the composite material. Therefore, the phosphorus-carbon-magnesium boride electrode has excellent electrochemical performance, including high lithium storage capacity, long cycle stability and impressive rate performance, which is far superior to red phosphorus-carbon materials and most reported phosphorus-based anodes.
[0019] (2) The electron-deficient boron sites in magnesium boride of the present invention have a strong ability to attract lone pairs of electrons from phosphorus, which greatly improves the air stability of the phosphorus-magnesium boride-graphene composite material.
[0020] (3) The preparation process of the phosphorus-carbon-boride magnesium composite material of the present invention is simple, with excellent electrochemical performance and good air stability, providing a new idea for the design of phosphorus-based lithium-ion battery anode materials. Attached Figure Description
[0021] Figure 1 The XRD patterns are of the black phosphorus crystals used in Examples 1 to 4.
[0022] Figure 2 The XRD patterns of the black phosphorus-graphene-magnesium boride composite material and the phosphorus-carbon material prepared in Example 1 and Comparative Example 1 are shown.
[0023] Figure 3 The cycle performance diagrams of the composite materials prepared in Example 1 and Comparative Example 1 when used as negative electrodes of lithium-ion batteries are shown.
[0024] Figure 4 The rate performance diagrams are for the composite materials prepared in Example 1 and Comparative Example 1 when used as negative electrodes of lithium-ion batteries.
[0025] Figure 5 The cycling performance diagrams of the black phosphorus-carbon nanotube-magnesium boride and black phosphorus-carbon nanotube composite materials prepared in Example 2 and Comparative Example 2 when used as negative electrodes of lithium-ion batteries are shown.
[0026] Figure 6 The cycling performance diagrams of the black phosphorus-soft carbon-magnesium boride and black phosphorus-soft carbon composite materials prepared in Example 3 and Comparative Example 3 when used as negative electrodes of lithium-ion batteries are shown.
[0027] Figure 7 The graph shows the cycle performance of the black phosphorus-porous carbon-magnesium boride and black phosphorus-porous carbon composite materials prepared in Example 4 and Comparative Example 4 when used as negative electrodes of lithium-ion batteries. Detailed Implementation
[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.
[0029] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; the reagents and materials described are commercially available unless otherwise specified.
[0030] To improve the conductivity and lithium storage kinetics of phosphorus-carbon composite materials and achieve high-capacity, long-cycle, and high-rate lithium-ion battery anode applications, we prepared phosphorus-carbon composite materials using different conductive carbonaceous materials, including graphene, carbon nanotubes, soft carbon, and porous carbon, via high-energy mechanical ball milling. The formation of PC or POC bonds at the composite interface maintains good electrical contact between the carbon matrix and phosphorus, accommodates volume changes, and inhibits the dissolution of LixPs. Therefore, higher rate performance and cycle stability can be obtained.
[0031] Simultaneously, magnesium boride (MgB2) was added during preparation. Magnesium boride consists of alternating layers of Mg and B atoms, with the B and Mg layers forming a honeycomb-like stack. It possesses a band structure similar to graphite, with a deep π band, a two-dimensional covalent band with in-plane O bonds, and a three-dimensional metallic conductive band with interlayer bonds, making it a highly attractive material in the field of superconductivity. Magnesium boride exhibits high lithium storage specific capacity, forming a high-capacity lithium-ion battery anode material. It also possesses good thermal stability and conductivity, thereby improving the electrochemical kinetics performance of the anode, reducing electrode polarization, increasing the rate capacity of the lithium battery, and flattening the anode potential. Boron-doped carbon materials prepared by a simple ball milling method can significantly enhance the chemical affinity between carbon and phosphorus. By introducing boron doping into the carbon material to form electronic defect sites, stable PC bonds are maintained, and the transfer of lone pair electrons to the carbon material significantly improves the air stability of phosphorus.
[0032] Example 1
[0033] Under an argon atmosphere, black phosphorus crystal powder (BP), magnesium boride, and graphene were placed in a ball mill jar, and grinding balls were added simultaneously. The mass ratio of BP, magnesium boride, and graphene was 6:0.5:3.5. The ball milling was performed using a planetary ball mill. Both the ball mill jar and the grinding balls were made of stainless steel, with diameters of 5 mm and 10 mm, and the mass ratio of the mixed powder to the grinding balls was 1:100. The mixture was ball-milled at 500 rpm for 24 hours to obtain the phosphorus-carbon-magnesium boride composite anode material, named black phosphorus-graphene-magnesium boride.
[0034] A phosphorus-carbon-boride magnesium composite material, conductive carbon black, and PVDF binder were mixed with an organic solvent (NMP) in a mass ratio of 7:2:1. The resulting electrode slurry (solid content 20%) was coated onto the surface of a current collector with a thickness of 10 μm and then dried in a vacuum oven at 100 °C for 8 hours at a vacuum degree <1 Pa to obtain a phosphorus-based electrode sheet. The areal loading of the electrode active material was 1 mg·cm³. -2 .
[0035] Example 2
[0036] Under an argon atmosphere, black phosphorus crystal powder, magnesium boride, and carbon nanotubes were placed in a ball mill jar, and grinding balls were added simultaneously. The mass ratio of phosphorus powder, magnesium boride, and carbon nanotubes was 6:0.5:3.5. The ball milling was performed using a planetary ball mill. Both the ball mill jar and the grinding balls were made of stainless steel, with diameters of 5 mm and 10 mm, and the mass ratio of the mixed powder to the grinding balls was 1:100. The mixture was ball-milled at 500 rpm for 24 hours to obtain the phosphorus-carbon-magnesium boride composite anode material.
[0037] A phosphorus-carbon-boride magnesium composite material, conductive carbon black, and PVDF binder were mixed with an organic solvent (NMP) in a mass ratio of 7:2:1. The resulting electrode slurry (solid content 20%) was coated onto the surface of a current collector with a thickness of 10 μm and then dried in a vacuum oven at 100 °C for 8 hours at a vacuum degree <1 Pa to obtain a phosphorus-based electrode sheet. The areal loading of the electrode active material was 1 mg·cm³. -2 .
[0038] Example 3
[0039] Under an argon atmosphere, black phosphorus crystal powder, magnesium boride, and soft carbon were placed in a ball mill jar, and grinding balls were added simultaneously. The mass ratio of phosphorus powder, magnesium boride, and soft carbon was 6:0.5:3.5. The ball milling was performed using a planetary ball mill. Both the ball mill jar and the grinding balls were made of stainless steel, and the diameters of the grinding balls were 5 mm and 10 mm, respectively. The mass ratio of the mixed powder to the grinding balls was 1:100. The mixture was ball-milled at 500 rpm for 24 hours to obtain the phosphorus-carbon-magnesium boride composite anode material.
[0040] A phosphorus-carbon-boride magnesium composite material, conductive carbon black, and PVDF binder were mixed with an organic solvent (NMP) in a mass ratio of 7:2:1. The resulting electrode slurry (solid content 20%) was coated onto the surface of a current collector with a thickness of 10 μm and then dried in a vacuum oven at 100 °C for 8 hours at a vacuum degree <1 Pa to obtain a phosphorus-based electrode sheet. The areal loading of the electrode active material was 1 mg·cm³. -2 .
[0041] Example 4
[0042] Under an argon atmosphere, black phosphorus crystal powder, magnesium boride, and porous carbon were placed in a ball mill jar, and grinding balls were added simultaneously. The mass ratio of phosphorus powder, magnesium boride, and porous carbon was 6:0.5:3.5. The ball milling was performed using a planetary ball mill. Both the ball mill jar and the grinding balls were made of stainless steel, with diameters of 5 mm and 10 mm, and the mass ratio of the mixed powder to the grinding balls was 1:100. The mixture was ball-milled at 500 rpm for 24 hours to obtain the phosphorus-carbon-magnesium boride composite anode material.
[0043] A phosphorus-carbon-boride magnesium composite material, conductive carbon black, and PVDF binder were mixed with an organic solvent (NMP) in a mass ratio of 7:2:1. The resulting electrode slurry (solid content 20%) was coated onto the surface of a current collector with a thickness of 10 μm and then dried in a vacuum oven at 100 °C for 8 hours at a vacuum degree <1 Pa to obtain a phosphorus-based electrode sheet. The areal loading of the electrode active material was 1 mg·cm³. -2 .
[0044] Comparative Example 1
[0045] The difference between this comparative example and Example 1 is that magnesium boride powder is not added, and the mass ratio of phosphorus powder to graphene is 6:4, which is named black phosphorus-graphene.
[0046] Comparative Example 2
[0047] The difference between this comparative example and Example 2 is that magnesium boride powder is not added, and the mass ratio of phosphorus powder to carbon nanotubes is 6:4.
[0048] Comparative Example 3
[0049] The difference between this comparative example and Example 3 is that magnesium boride powder is not added, and the mass ratio of phosphorus powder to soft carbon is 6:4.
[0050] Comparative Example 4
[0051] The difference between this comparative example and Example 4 is that magnesium boride powder is not added, and the mass ratio of phosphorus powder to porous carbon is 6:4.
[0052] Structural characterization and performance testing
[0053] The black phosphorus used in Examples 1 to 4 was characterized by XRD. Figure 1It can be seen that its characteristic diffraction peaks correspond to the (020), (040), and (060) crystal planes of black phosphorus, which are highly consistent with the standard spectrum and have no impurity peaks. This not only verifies the correctness of the phase but also indicates that the sample has high purity. All characteristic peaks come from the (0k0) crystal plane family, reflecting that the sample has obvious preferred orientation and embodies the layered structure characteristics of black phosphorus. At the same time, the sharp peaks and flat baselines indicate that the sample has high crystallinity, large grain size, and few internal defects, and the overall sample exhibits the typical XRD characteristics of high-quality black phosphorus.
[0054] Figure 2 The XRD comparison images of the composite materials of Example 1 and Comparative Example 1 show that black phosphorus-graphene-magnesium boride (Example 1) and black phosphorus-graphene (Comparative Example 1) both exhibit a broad diffuse scattering background and no obvious sharp characteristic diffraction peaks, indicating that both samples are amorphous or low-crystallinity structures. The signal intensity of the black phosphorus-graphene-magnesium boride sample is generally higher than that of black phosphorus-graphene, reflecting that the introduction of MgB2 may have improved the electron density or scattering ability of the sample. The similar slow decreasing trend of both indicates that neither composite system has formed highly crystalline black phosphorus or other crystalline phases, and both exhibit typical XRD characteristics of amorphous composite materials.
[0055] The electrochemical performance of the electrode sheets prepared for the corresponding use cases and comparative application examples was tested sequentially:
[0056] Using the electrode sheets prepared in the application examples and comparative application examples as negative electrodes, lithium metal sheets as counter and reference electrodes, polypropylene microporous membranes (Celgard 2400) as separators, and 1.0 mol / L LiPF6 solution (a mixture of ethylene carbonate EC, dimethyl carbonate DMC, and diethyl carbonate DEC in a volume ratio of 2:2:1, with 10% fluoroethylene carbonate FEC additive added) as the electrolyte, CR2025 coin cells were assembled in a glove box. Specifically, the electrode sheets, separator, and lithium metal sheets were stacked sequentially into a layered structure, then placed in a battery case, and the electrolyte was added to assemble the CR2025 coin cell. The assembled CR2025 coin cells were then transferred to a Xinwei charge-discharge tester for constant current charge-discharge cycle testing at a current density of 0.5 A·g. -1 The cutoff voltage was set to 0.01~3.0V. Simultaneously, the sweep rate for the cyclic voltammetry test was set to 0.2mV·s. -1 The voltage range is 0.01~3.0V.
[0057] Figure 3 The graph shows the cycle performance of the composite materials prepared in Example 1 and Comparative Example 1 when used as negative electrodes in lithium-ion batteries. Figure 3 It can be seen that the black phosphorus-graphene-magnesium boride sample in Example 1 has a concentration of 1 A·g -1 After 500 cycles, it maintains 1232 mAh g.-1 The high specific capacity. In stark contrast, the black phosphorus-graphene sample in Comparative Example 1 only had a capacity of 892 mA hg after 500 cycles. -1 Reversible capacity.
[0058] Figure 4 The graph shows the rate performance of the composite materials prepared in Example 1 and Comparative Example 1 when used as negative electrodes in lithium-ion batteries. Figure 4 It can be seen that the sample of Example 1 showed better performance at current densities of 0.1, 0.2, 0.5, 1.0, 2.0, and 5.0 A·g. -1 The stable capacities at different times were 1707, 1580, 1465, 1389, 1296 and 1019 mA hg, respectively. -1 When the current density gradually decreases to 0.1 A·g -1 At that time, the capacity was almost completely recovered, due to the higher electronic conductivity and faster ion diffusion of boron doping. However, the capacity of the samples prepared in Comparative Example 1 was significantly lower than that of the samples in Example 1.
[0059] Figures 5 to 7 Samples from Example 2 and Comparative Example 2, Example 3 and Comparative Example 3, and Example 4 and Comparative Example 4 were tested at 1 A·g. -1 The following is a comparison chart of cycles. From Figures 5 to 7 It can be seen that the cycling performance of the samples with added magnesium boride is significantly higher than that of the samples without added magnesium boride. This indicates that introducing magnesium boride into the phosphorus-carbon composite material can simultaneously achieve excellent cycling stability and excellent air stability. Boron can effectively accelerate the transport of electrons and lithium ions, greatly improving the structural stability of the composite material.
[0060] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
[0061] The parts of this invention not described in detail are well-known in the art. The above embodiments are provided merely for the purpose of describing the invention and are not intended to limit its scope. The scope of the invention is defined by the appended claims. All equivalent substitutions and modifications made without departing from the spirit and principles of the invention should be covered within its scope.
Claims
1. A phosphorus-carbon-magnesium boride composite material, characterized by, The phosphorus-carbon-boride magnesium composite material contains a three-dimensional continuous conductive network and a three-dimensional ion transport network. The three-dimensional continuous conductive network is constructed by carbon-boron and phosphorus-boron covalent bonds formed between magnesium boride and phosphorus or carbon. The three-dimensional ion transport network is formed by the interlayer channels of magnesium boride, the ion insertion channels of phosphorus, and the pores of the carbon matrix.
2. The phosphorus-carbon-magnesium boride composite material according to claim 1, characterized in that, The phosphorus-carbon-magnesium boride composite material is composed of the following components by mass fraction: phosphorus 40-70%, carbon material 20-60%, and magnesium boride 5-10%.
3. The phosphorus-carbon-magnesium boride composite material according to claim 2, characterized in that, The phosphorus is at least one of red phosphorus, black phosphorus, or purple phosphorus; the carbon material is at least one of graphene, carbon nanotubes, soft carbon, and porous carbon; the magnesium boride is a nanoscale powder with a particle size of 20-80 nm.
4. The method for preparing the magnesium phosphorus-carbon-boride composite material according to any one of claims 1 to 3, characterized in that, The process includes the following steps: using a mixture of appropriate amounts of high-purity phosphorus powder, magnesium boride powder, and carbon materials as raw materials, and subjecting it to high-energy ball milling.
5. The method for preparing phosphorus-carbon-magnesium boride composite material according to claim 4, characterized in that, The ball-to-material ratio for the high-energy ball milling process is 40-100:1, the rotation speed is 300-500 r / min, and the milling time is 12-48 h.
6. The method of claim 4, wherein the phosphorus-carbon-magnesium boride composite is prepared by the steps of: preparing a mixture of a magnesium compound, a boron compound, and a phosphorus compound; and heating the mixture at a temperature of 300 to 1,000°C in a non-oxidizing atmosphere. The ball tank and balls used in the high-energy ball milling process are made of at least one of zirconium oxide, agate, and stainless steel, and the ball tank is filled with inert reactive gas.
7. The method for preparing the magnesium phosphorus-carbon-boride composite material according to claim 4, characterized in that, The mass ratio of phosphorus powder, carbon material and magnesium boride powder is (40~70):(20~60):(5~10).
8. An electrode active material, characterized by, The electrode active material includes the magnesium phosphorus-carbon-boride composite material, conductive agent and binder as described in any one of claims 1 to 3, wherein the mass ratio of the magnesium phosphorus-carbon-boride composite material, conductive agent and binder is (7~9):(0.5~2):(0.5~1).
9. A phosphorus-based electrode sheet, characterized by, It includes a current collector and an electrode active material coated on the surface of the current collector, wherein the electrode active material is the electrode active material according to claim 8.
10. The application of the phosphorus-based electrode sheet according to claim 9 as a negative electrode sheet in solid-state batteries, lithium-ion batteries, or lithium-ion capacitors.