Phosphorus-carbon negative electrode material and preparation method and application thereof

Abstract

The invention provides a phosphorus-carbon negative electrode material and a preparation method and application thereof, and the preparation method comprises the following steps: mixing porous carbon and an amine solution of red phosphorus for dipping to obtain mixed slurry, and carrying out solid-liquid separation to obtain filtrate and filter residues; drying the filter residue to obtain a solid; and adding the solid into the filtrate, and repeatedly carrying out mixed impregnation, solid-liquid separation and drying until the filtrate is used up to obtain the phosphorus-carbon negative electrode material. According to the preparation method, a liquid phase deposition method is adopted, the deposition amount of red phosphorus particles in the pore structure of the porous carbon matrix is increased, meanwhile, the risk of producing white phosphorus can be effectively reduced, the safety performance of the phosphorus-carbon negative electrode material is improved, and large-scale production is facilitated.

Description

Technical Field

[0001] This application relates to the field of battery materials technology, and in particular to a phosphorus-carbon anode material, its preparation method, and its application. Background Technology

[0002] Phosphorus is a special anode material. Unlike graphite and silicon anode materials commonly used in lithium-ion batteries, and hard carbon anode materials commonly used in sodium-ion batteries, phosphorus anode materials possess both lithium and sodium intercalation capabilities. Therefore, phosphorus anode materials can be used as anode materials for both lithium-ion and sodium-ion batteries. Although phosphorus anode materials have a high theoretical specific capacity, their application in the battery field is limited by their extremely poor conductivity and large volume expansion rate after lithium / sodium intercalation. Phosphorus exists in various allotropes, including red phosphorus, white phosphorus, black phosphorus, and purple phosphorus, with red phosphorus being the most stable. Currently, there are methods to improve the conductivity of phosphorus anode materials by combining red phosphorus with carbon materials, but the problem of some red phosphorus converting to white phosphorus during the composite process still exists, which not only reduces capacity but also makes it difficult to guarantee safety. Summary of the Invention

[0003] In view of this, this application provides a phosphorus-carbon anode material, its preparation method and application. The preparation method includes mixing and impregnating porous carbon with an amine solution of red phosphorus to obtain a mixed slurry, separating the solid and liquid to obtain a filtrate and a filter residue; drying the filter residue to obtain a solid; adding the solid to the filtrate, and repeating the mixing, impregnation, solid-liquid separation and drying until the filtrate is used up to obtain the phosphorus-carbon anode material.

[0004] This preparation method employs liquid-phase deposition, which increases the deposition amount of red phosphorus particles in the porous carbon matrix while effectively reducing the risk of white phosphorus formation, thus improving the safety performance of the phosphorus-carbon anode material and facilitating large-scale production. The phosphorus-carbon anode material prepared by this method exhibits good conductivity and high safety, and can effectively alleviate the volume expansion problem of the anode material during intercalation / deintercalation.

[0005] The first aspect of this application provides a method for preparing a phosphorus-carbon anode material, comprising:

[0006] Porous carbon was mixed and impregnated with an amine solution of red phosphorus to obtain a mixed slurry. Solid-liquid separation was performed to obtain filtrate and filter residue.

[0007] The filter residue is dried to obtain a solid.

[0008] The solid is added to the filtrate, and the mixing, impregnation, solid-liquid separation and drying are repeated until the filtrate is used up to obtain the phosphorus-carbon anode material.

[0009] In this embodiment of the application, the cumulative number of solid-liquid separations is less than or equal to n, where n is greater than or equal to M. RP / (M PC The smallest integer of *V*c), where M RP M represents the mass of the red phosphorus. PC M represents the mass of the porous carbon. RP and M PC The unit is g; V is the pore volume of the porous carbon, in cm³. 3 / g; c is the concentration of red phosphorus in the amine solution of the red phosphorus, in g / cm³. 3 .

[0010] In this embodiment of the application, the pore volume of the porous carbon is 0.6 cm³. 3 / g-1.5cm 3 / g; the porous carbon includes a pore structure with an average pore size of 1.2nm-10nm; the pore structure includes micropores, the volume of which accounts for 10%-90% of the total volume of the pore structure.

[0011] In this embodiment of the application, the concentration of phosphorus in the amine solution of red phosphorus is 0.01 g / mL to 10 g / mL; the mass ratio of red phosphorus to porous carbon is (0.1-1.5):1.

[0012] In this embodiment of the application, the method for preparing the amine solution of red phosphorus includes the following steps: mixing red phosphorus with an amine solvent; the mixing treatment is carried out at a temperature of 60℃-120℃ for a time of 24h-72h.

[0013] In the embodiments of this application, the amine solvent includes one or more of ethylenediamine, formamide, isopropylamine, N,N-dimethylformamide, N-methylpyrrolidone, and dimethyl sulfoxide.

[0014] In this embodiment of the application, the mixed impregnation is carried out at room temperature.

[0015] In this embodiment of the application, the drying temperature is 110℃-200℃, and the drying time is 2h-6h.

[0016] In this embodiment of the application, the method for preparing the phosphorus-carbon anode material further includes the step of forming a coating layer on the surface of the phosphorus-carbon anode material; the coating layer includes a conductive polymer coating layer.

[0017] The second aspect of this application provides a phosphorus-carbon anode material prepared by the preparation method provided in the first aspect, the phosphorus-carbon anode material comprising a porous carbon matrix and red phosphorus particles loaded in the pore structure of the porous carbon matrix.

[0018] In this embodiment of the application, the mass of the red phosphorus particles in the phosphorus-carbon anode material is less than or equal to M. PC *V*ρ RP , of which M PC V represents the mass of the porous carbon, in grams; V represents the pore volume of the porous carbon matrix, in centimeters. 3 / g;ρ RP The density of red phosphorus is expressed in g / cm³. 3 .

[0019] In this embodiment of the application, the surface of the phosphorus-carbon anode material further includes a conductive polymer coating layer.

[0020] A third aspect of this application provides a negative electrode sheet, the negative electrode sheet comprising a current collector and a negative electrode active layer disposed on the surface of the current collector, the negative electrode active layer comprising a phosphorus-carbon negative electrode material prepared by the preparation method provided in the first aspect or a phosphorus-carbon negative electrode material provided in the second aspect.

[0021] A fourth aspect of this application provides a battery comprising a positive electrode, a negative electrode, a separator and an electrolyte located between the positive electrode and the negative electrode, wherein the negative electrode comprises the negative electrode provided in the third aspect.

[0022] The fifth aspect of this application provides an electrical device, which includes the battery provided in the fourth aspect. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the cross-sectional structure of a phosphorus-carbon anode material provided in an embodiment of this application;

[0024] Figure 2 This is a schematic diagram of the cross-sectional structure of a phosphorus-carbon anode material provided in another embodiment of this application.

[0025] Explanation of icon numbers

[0026] 10-Phosphorus-carbon anode material; 111-Porous carbon matrix; 112-Red phosphorus particles; 12-Conductive polymer coating layer. Detailed Implementation

[0027] The present application will be further described in detail below with reference to preferred embodiments, but the scope of protection of the present application is not limited to the following specific embodiments.

[0028] In this application, all technical terms have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the scope of protection of this application.

[0029] Phosphorus is a special anode material. Unlike graphite and silicon anode materials commonly used in lithium-ion batteries, and hard carbon anode materials commonly used in sodium-ion batteries, phosphorus anode materials possess both lithium and sodium intercalation capabilities. Therefore, phosphorus anode materials can be used as anode materials for both lithium-ion and sodium-ion batteries. Although phosphorus anode materials have a high theoretical specific capacity (2596 mAh / g), their extremely poor conductivity (10-1) makes them unsuitable for use in other batteries. -12 Phosphorus's application in the battery field is limited by factors such as its high S / cm ratio and large volume expansion rate after lithium / sodium intercalation (>300%). Phosphorus exists in various allotropes, including red phosphorus, white phosphorus, black phosphorus, and purple phosphorus, with red phosphorus being the most stable. Currently, there are methods to improve the conductivity of phosphorus anode materials by combining red phosphorus with carbon materials, but there is still a problem that some red phosphorus will be converted into white phosphorus during the composite process, which will not only reduce the capacity but also make it difficult to guarantee its safety.

[0030] To address the aforementioned issues, this application provides a phosphorus-carbon anode material, its preparation method, and its applications. This preparation method employs a multi-step liquid-phase deposition process, which increases the deposition amount of red phosphorus particles in the porous carbon matrix while effectively reducing the risk of white phosphorus formation, thus improving the safety performance of the phosphorus-carbon anode material and facilitating large-scale production. The phosphorus-carbon anode material prepared using this method exhibits good conductivity and high safety, and can effectively alleviate the volume expansion problem of the anode material during intercalation / deintercalation.

[0031] This application provides a method for preparing a phosphorus-carbon anode material, including:

[0032] Porous carbon was mixed and impregnated with an amine solution of red phosphorus to obtain a mixed slurry. Solid-liquid separation was performed to obtain filtrate and filter residue.

[0033] The filter residue is dried to obtain a solid.

[0034] The solid is added to the filtrate, and the mixing, impregnation, solid-liquid separation and drying are repeated until the filtrate is used up to obtain the phosphorus-carbon anode material.

[0035] The method for preparing phosphorus-carbon anode materials provided in this application uses a multi-step liquid phase deposition method, which enables nanoscale red phosphorus particles to grow in situ in the pore structure of porous carbon. This increases the amount of red phosphorus deposited and enhances the uniformity of red phosphorus dispersion in porous carbon. Furthermore, the liquid phase deposition method can effectively reduce the risk of white phosphorus formation, improve the safety of the preparation process, and facilitate large-scale production.

[0036] In this application, the preparation method of the amine solution of red phosphorus includes the following steps: mixing red phosphorus with an amine solvent. In this application, the amine solvent includes, but is not limited to, one or more of ethylenediamine, formamide, isopropylamine, N,N-dimethylformamide, N-methylpyrrolidone, and dimethyl sulfoxide. In some specific embodiments, ethylenediamine is selected as the amine solvent. Compared with other solvents, ethylenediamine has a higher solubility for red phosphorus, which is more conducive to increasing the red phosphorus content in the amine solution, thereby promoting the subsequent liquid-phase deposition rate of red phosphorus in porous carbon and increasing the amount of red phosphorus deposited in each liquid-phase deposition, reducing the number of solid-liquid separation steps, and depositing as much red phosphorus as possible in the porous carbon while shortening the preparation process. Furthermore, amine solvents have high wettability to porous carbon; dissolving red phosphorus in them allows the amine solution of red phosphorus to fully fill the pore structure of the porous carbon, thereby increasing the amount of red phosphorus deposited in the porous carbon.

[0037] In this embodiment, the mixing temperature for preparing the amine solution of red phosphorus is 60℃-120℃, and the mixing time is 24h-72h. In some specific embodiments, the mixing temperature can be, for example, 60℃, 70℃, 80℃, 90℃, 100℃, 110℃, or 120℃; and the mixing time can be, for example, 24h, 28h, 32h, 36h, 40h, 44h, 48h, 52h, 56h, 60h, 64h, 68h, or 72h. Red phosphorus is insoluble or has very low solubility in most solvents. This application, by selecting amine solvents and controlling the mixing time and temperature within a suitable range, can further promote the dissolution of red phosphorus in amine solvents, thereby increasing the concentration of red phosphorus in the amine solution and facilitating subsequent liquid-phase deposition of red phosphorus.

[0038] In this application, the concentration of red phosphorus in the amine solution is 0.01 g / mL to 10 g / mL. In some specific embodiments, the concentration of phosphorus in the amine solution can be, for example, 0.01 g / mL, 0.05 g / mL, 0.1 g / mL, 0.5 g / mL, 1 g / mL, 2 g / mL, 3 g / mL, 4 g / mL, 5 g / mL, 6 g / mL, 7 g / mL, 8 g / mL, 9 g / mL, or 10 g / mL. In some embodiments of this application, the concentration of red phosphorus in the amine solution can be 5 g / mL to 10 g / mL. By selecting amine solvents as the system for dissolving red phosphorus and controlling the parameters of the amine treatment of red phosphorus within a suitable range, this application can maximize the solubility of red phosphorus in the solvent, thereby enabling subsequent liquid-phase deposition of red phosphorus in porous carbon while avoiding excessively high concentrations that would lead to too many subsequent solid-liquid separation steps and prolong the process, further reducing production costs.

[0039] In this embodiment, the pore volume V of the porous carbon is 0.6 cm³.3 / g-1.5cm 3 / g. In some specific embodiments, the pore volume V of the porous carbon can be, for example, 0.6 cm³. 3 / g, 0.7cm 3 / g, 0.8cm 3 / g, 0.9cm 3 / g, 1cm 3 / g, 1.1cm 3 / g, 1.2cm 3 / g, 1.3cm 3 / g, 1.4cm 3 / g, 1.5cm 3 / g. In this application, porous carbon is selected as the carrier for loading and containing red phosphorus particles. On the one hand, compared with other carbon materials, porous carbon has a larger porosity and can accommodate more red phosphorus particles. On the other hand, by controlling the pore volume of porous carbon within a suitable range, it is more conducive to the liquid phase deposition of red phosphorus in porous carbon, thereby increasing the amount of red phosphorus deposited in porous carbon and increasing its dispersion uniformity.

[0040] In this application, the porous carbon includes a pore structure with an average pore size of 1.2 nm to 10 nm. In some specific embodiments, the average pore size of the pore structure can be, for example, 1.2 nm, 1.5 nm, 2 nm, 2.5 nm, 3 nm, 3.5 nm, 4 nm, 4.5 nm, 5 nm, 5.5 nm, 6 nm, 6.5 nm, 7 nm, 7.5 nm, 8 nm, 8.5 nm, 9 nm, 9.5 nm, or 10 nm. In this application, the pore structure includes micropores, with the volume of the micropores accounting for 10% to 90% of the total volume of the pore structure. In some specific embodiments, the volume of the micropores accounts for 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% of the total volume of the pore structure. In some embodiments, the volume of the micropores accounts for 20% to 80% of the total volume of the pore structure. This application controls the parameters of the pore structure in porous carbon within a suitable range. This allows for sufficient space to accommodate red phosphorus particles while maximizing the surface area, ensuring adequate contact between the pore structure and the amine solution of red phosphorus, thus facilitating the liquid-phase deposition rate of the red phosphorus particles. Furthermore, controlling the size of the pores in the porous carbon within a suitable range can significantly suppress the volume expansion of the contained red phosphorus particles after lithium / sodium intercalation. In the embodiments of this application, the volume ratio of micropores in the pore structure can be characterized using a nitrogen adsorption-desorption apparatus.

[0041] In this application, the particle size D50 of the porous carbon is within the conventional particle size range of porous carbon materials in the field, and is not particularly limited, but can be selected according to actual application requirements. In some embodiments, the particle size D50 of the porous carbon can be 4μm-15μm. In some specific embodiments, the particle size D50 of the porous carbon can be, for example, 4μm, 5μm, 6μm, 6.5μm, 7μm, 7.5μm, 8μm, 8.5μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, or 15μm. In this application, the particle size D50 refers to the particle size corresponding to a particle size distribution percentage of 50%. In this application, the particle size testing method can adopt GB / T 41949-2022 "Technical Requirements for Laser Particle Size Analyzers", and the testing instrument is a Malvern laser particle size analyzer.

[0042] In this embodiment, the mass ratio of red phosphorus to porous carbon is (0.1-1.5):1. In some specific embodiments, the mass ratio of red phosphorus to porous carbon can be, for example, 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.80:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, or 1.5:1. By controlling the mass ratio of red phosphorus to porous carbon within the above range, this application can maximize the deposition of red phosphorus in the porous carbon without wasting red phosphorus, thereby further increasing the capacity of the phosphorus-carbon anode material.

[0043] In this embodiment, the cumulative number of solid-liquid separations is less than or equal to n, where n is greater than or equal to M. RP / (M PC The smallest integer of *V*c), where M RP M represents the mass of the red phosphorus. PC M represents the mass of the porous carbon. RP and M PC The unit is g; V is the pore volume of the porous carbon, in cm³. 3 / g; c is the concentration of red phosphorus in the amine solution of the red phosphorus, in g / cm³. 3 Because the red phosphorus content in the amine solution is low, only the red phosphorus in the surrounding liquid at the contact point with the porous carbon's pore structure will deposit into the porous carbon's pore structure. A single liquid-phase immersion deposition process is insufficient to ensure complete liquid-phase deposition of all the red phosphorus in the solution. Therefore, this application employs stepwise liquid-phase deposition, where each liquid-phase immersion fully fills the porous carbon's pore structure with the amine solution; that is, the volume of the amine solution filling the porous carbon's pore structure is approximately M. PC *V, meaning the amount of red phosphorus deposited in one solid-liquid separation is approximately M. PC*V*c. After each liquid-phase deposition, the solid is mixed with the remaining phosphoric acid liquid for the next liquid-phase deposition until the filtrate is used up. This ensures that all the red phosphorus in the amine solution is deposited in the porous carbon, resulting in a theoretical cumulative number of solid-liquid separations of approximately M times. RP / (M PC The number of solid-liquid separations in this application is less than or equal to n, as n is the smallest integer of *V*c. However, due to material loss during the actual preparation process, the actual cumulative number of solid-liquid separations in this application is less than or equal to n. Compared to the traditional vapor deposition method, the liquid phase deposition method used in this application is safer and effectively avoids the problem of white phosphorus formation during red phosphorus deposition, thus further improving the safety of the preparation and making it more conducive to large-scale production. By further controlling the number of solid-liquid separations, this application can ensure sufficient deposition of red phosphorus, thereby increasing the deposition density and utilization rate of red phosphorus, and further improving the capacity and production cost of the phosphorus-carbon anode material. In this application, solid-liquid separation can be performed using conventional methods such as vacuum filtration.

[0044] In this application, the conditions for mixed impregnation are not particularly limited; it is sufficient to ensure that the porous carbon and the amine solution of red phosphorus are fully impregnated. In some specific embodiments, the mixed impregnation is carried out at room temperature.

[0045] In this embodiment, the purpose of drying is to evaporate the amine solvent in the porous structure of the porous carbon, thereby allowing the red phosphorus in the amine solution to precipitate in situ within the porous carbon structure, forming nanoscale red phosphorus particles housed within the porous carbon structure. Therefore, this application does not impose any particular limitation on the drying conditions, as long as the objective is achieved. Optionally, the drying temperature is 110℃-200℃, and the drying time is 2h-6h. In some specific embodiments, the drying temperature can be, for example, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, 190℃, or 200℃; and the drying time can be, for example, 2h, 3h, 4h, 5h, or 6h. Optionally, drying can be carried out under vacuum conditions. This application uses these conditions for drying, which allows the drying process to be performed more efficiently.

[0046] In some embodiments of this application, the method for preparing the phosphorus-carbon anode material further includes the step of forming a coating layer on the surface of the phosphorus-carbon anode material. The coating layer may be, for example, a conductive polymer coating layer. By coating the phosphorus-carbon anode material with a conductive polymer, the insufficient conductivity of red phosphorus deposited in porous carbon can be further compensated, thereby further improving the conductivity of the phosphorus-carbon anode material.

[0047] In this application, the method of coating the surface of the phosphorus-carbon anode material with a conductive polymer coating layer is not limited. In some specific embodiments, the conductive polymer coating layer may be grown in situ on the surface of the phosphorus-carbon anode material.

[0048] In some embodiments of this application, the conductive polymer coating layer can be obtained by in-situ polymerization on the surface of the phosphorus-carbon anode material, for example, by adding a conductive polymer monomer and an initiator. In some embodiments, the conductive polymer monomer includes one or more of pyrrole, aniline, sodium benzenesulfonate, 3,4-ethylenedioxythiophene, acrylic acid, and acrylonitrile. In some specific embodiments, the conductive polymer monomer may be, for example, acrylonitrile. By selecting suitable conductive polymer monomers and initiators for in-situ coating on the surface of the phosphorus-carbon anode material, this application can further improve the conductivity of the phosphorus-carbon anode material. In some embodiments of this application, the initiator includes one or more of ferric chloride, sodium persulfate, potassium persulfate, and ammonium persulfate. In the embodiments of this application, the amount of initiator added is 0.1%-5% of the content of the conductive polymer monomer. In some specific embodiments, the amount of initiator added can be, for example, 0.1%, 0.2%, 0.3%, 0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5% of the content of the conductive polymer monomer. This application can further promote the polymerization of the conductive polymer monomer by selecting a suitable initiator and controlling its addition amount within an appropriate range, thereby further improving the quality of the obtained conductive polymer coating layer.

[0049] In other embodiments of this application, the conductive polymer coating layer can be formed by cyclizing a chain-like conductive polymer onto the surface of the phosphorus-carbon anode material using a cyclization heat treatment. In some specific embodiments of this application, the chain-like conductive polymer includes one or more of polyacrylonitrile, polyamic acid, and polyacrylic acid. In these embodiments, the cyclization heat treatment temperature is 110℃-200℃, and the cyclization heat treatment time is 4h-12h. In some specific embodiments, the cyclization heat treatment temperature can be, for example, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, 190℃, or 200℃, and the cyclization heat treatment time can be, for example, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, or 12h. By selecting a suitable chain-like conductive polymer for cyclization coating on the surface of the phosphorus-carbon anode material, this application can further improve the conductivity of the phosphorus-carbon anode material.

[0050] The method for preparing phosphorus-carbon anode materials provided in this application uses a multi-step liquid phase deposition method, which enables nanoscale red phosphorus particles to grow in situ in the pore structure of porous carbon. This increases the amount of red phosphorus deposited and enhances the uniformity of red phosphorus dispersion in porous carbon. Furthermore, the liquid phase deposition method can effectively reduce the risk of white phosphorus formation, improve the safety of the preparation process, and facilitate large-scale production.

[0051] This application also provides a phosphorus-carbon anode material 10 prepared by the preparation method described above, and a schematic diagram of the cross-sectional structure of the phosphorus-carbon anode material 10 is shown below. Figure 1 As shown, the phosphorus-carbon anode material 10 includes a porous carbon matrix 111 and red phosphorus particles 112 supported in the porous structure of the porous carbon matrix 111. The phosphorus-carbon anode material 10 provided in this application selects a porous carbon matrix 111 with a porous structure as the matrix for supporting the red phosphorus particles 112. On the one hand, the porous carbon matrix 111 has good conductivity, which can provide a good electronic pathway for the phosphorus-carbon anode material 10, compensating for the lack of conductivity of red phosphorus; on the other hand, the porous structure of the porous carbon matrix provides sufficient space for the red phosphorus particles 112, and the porous structure of the porous carbon can also limit the volume expansion of the red phosphorus particles 112 during the lithium / sodium intercalation process to a certain extent, thereby improving the electrochemical performance of the phosphorus-carbon anode material.

[0052] In this embodiment, the particle size D50 of the red phosphorus particles 112 is 1 nm-10 nm. In some specific embodiments, the particle size D50 of the red phosphorus particles 112 can be, for example, 1 nm, 1.5 nm, 2 nm, 2.5 nm, 3 nm, 3.5 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, or 10 nm. This application uses a liquid phase deposition method to grow nanoscale red phosphorus particles in situ in a porous carbon matrix. Compared with conventional red phosphorus particles, the size of the red phosphorus particles is reduced, allowing them to be housed in the pore structure of porous carbon. This enables the nanoscale red phosphorus particles to be combined with porous carbon to obtain the phosphorus-carbon anode material 10.

[0053] In this embodiment of the application, the mass of the red phosphorus particles 112 in the phosphorus-carbon anode material 10 is less than or equal to M. PC *V*ρ RP , of which M PC V represents the mass of the porous carbon, in grams; V represents the pore volume of the porous carbon matrix, in centimeters. 3 / g;ρ RP The density of red phosphorus is expressed in g / cm³. 3 In this application, the density of red phosphorus is data that can be obtained from relevant literature, specifically 2.34 g / cm³. 3 The volume of the porous carbon matrix 111 in the phosphorus-carbon anode material 10 is M. PC*V, Since the red phosphorus particles 112 in this application are housed within the porous structure of the porous carbon matrix 111, the maximum mass of the red phosphorus particles 112 in the phosphorus-carbon anode material 10 in this application is less than or equal to M. PC *V*ρ RP .

[0054] In some embodiments of this application, the cross-sectional structure diagram of the phosphorus-carbon anode material 10 is shown below. Figure 2 As shown, the surface of the phosphorus-carbon anode material 10 also includes a conductive polymer coating layer 12. In this application, the conductive polymer coating layer 12 can further improve the conductivity of the phosphorus-carbon anode material 10, while making the porous carbon matrix 111 and the red phosphorus particles 112 more tightly bonded.

[0055] This application also provides a negative electrode sheet, which includes a current collector and a negative electrode active layer disposed on the surface of the current collector. The negative electrode active layer includes a phosphorus-carbon negative electrode material prepared by the preparation method described above or the phosphorus-carbon negative electrode material described above. In embodiments of this application, the current collector includes, but is not limited to, at least one of copper, aluminum, nickel, and stainless steel. In some specific embodiments of this application, the current collector may be copper foil.

[0056] In some embodiments of this application, the negative electrode active layer further includes a conductive agent, which can increase the conductivity of the negative electrode active layer and improve the electronic conductivity. Specifically, the conductive agent includes, but is not limited to, at least one of graphite, carbon black, acetylene black, and graphene. In some embodiments of this application, the negative electrode active layer also includes a binder, which can improve the bonding ability of the components in the negative electrode active layer and improve the bonding ability between the negative electrode active layer and the current collector. Specifically, the binder includes, but is not limited to, one or more of polyvinylidene fluoride, polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, polystyrene, polybutadiene, acrylic resin, epoxy resin, polyethylene oxide, sodium carboxymethyl cellulose, and styrene-butadiene latex.

[0057] This application also provides a battery, including a positive electrode, a negative electrode, a separator and an electrolyte located between the positive and negative electrode, wherein the negative electrode includes the negative electrode provided above. In embodiments of this application, the battery can be a lithium-ion battery or a sodium-ion battery. The negative electrode provided in this application, made from phosphorus-carbon negative electrode material, can be applied to both lithium-ion and sodium-ion battery systems, and has a wide range of applications. In some embodiments, the battery can be a lithium-ion battery, and the positive electrode includes a positive electrode active material, such as at least one selected from lithium iron phosphate, lithium manganese iron phosphate, lithium cobalt oxide, lithium manganese oxide, nickel-cobalt-manganese, and nickel-cobalt-aluminum materials. In some embodiments, the battery can be a sodium-ion battery, and the positive electrode includes a positive electrode active material, such as at least one selected from transition metal oxides, polyanionic compounds, Prussian blue compounds, and organic compounds.

[0058] In this embodiment, the separator is a commonly used separator material in the battery industry. Specifically, the separator can be, for example, a woven membrane, non-woven fabric, microporous membrane, composite membrane, rolled membrane, or separator paper. In this embodiment, the electrolyte is a commonly used electrolyte in the battery industry, wherein at least a portion of the positive electrode and at least a portion of the negative electrode are immersed in the electrolyte.

[0059] This application also provides an electrical device, which includes the battery provided in any of the above embodiments. The electrical device in this application can refer to a vehicle, electronic device, energy storage system, etc.

[0060] The present application will be further described below with reference to several embodiments:

[0061] Example 1

[0062] (1) Add 10g of red phosphorus to 100mL of ethylenediamine, heat to 100℃ and stir for 30h to obtain an amine solution of red phosphorus. The concentration of red phosphorus in the amine solution of red phosphorus is 0.1g / mL.

[0063] (2) 10g of material with a pore volume of 0.9cm 3 / g, porous carbon with a particle size D50 of 6μm is mixed with the above-mentioned red phosphorus amine solution at a red phosphorus to porous carbon mass ratio of 1:1 at room temperature and stirred for 30min to obtain a mixed slurry. The mixed slurry is subjected to a first solid-liquid separation to obtain filtrate A1 and filter residue B1. Filter residue B1 is dried under vacuum at 200℃ for 4h to obtain a solid. The solid is added to the filtrate and subjected to a second solid-liquid separation to obtain filtrate A2 and filter residue B2. The above process is repeated until the 10th solid-liquid separation is completed and the filtrate is used up to obtain filter residue B10. After vacuum drying at 200℃ for 4h, the phosphorus-carbon anode material is obtained.

[0064] Example 2;

[0065] Steps (1) and (2) are the same as in Example 1, with the obtained phosphorus-carbon anode material used as the precursor for the anode material;

[0066] (3) Take 0.2g of polyacrylonitrile and add it to 20mL of N-methylpyrrolidone solvent. Heat to 80℃ and stir for 30min at a speed of 400r / min to obtain a polyacrylonitrile solution with a mass concentration of 0.01g / mL.

[0067] (4) Take the negative electrode material precursor and mix it with the polyacrylonitrile solution obtained in step (3). After stirring evenly at room temperature, transfer it to a kneading pot and knead it for 4 hours at 200°C under nitrogen protection to obtain the phosphorus carbon negative electrode material.

[0068] Example 3

[0069] The difference from Example 2 is that in step (1), the mass of red phosphorus is 5g; and in step (2), the cumulative number of solid-liquid separations is 5.

[0070] Example 4

[0071] The difference from Example 2 is that in step (1), the concentration of red phosphorus in the amine solution of red phosphorus is 1 g / mL; and in step (2), the cumulative number of solid-liquid separations is 2.

[0072] Example 5

[0073] The difference from Example 2 is that in step (2), the pore volume of the porous carbon is 0.5 cm³. 3 / g; the cumulative number of solid-liquid separations was 3.

[0074] Example 6

[0075] The difference from Example 2 is that step (3) is: take 0.2g of 3,4-ethylenedioxythiophene and add it to 40mL of ethanol solvent, heat to 80℃ and stir for 30min at a speed of 400r / min to obtain a polymer monomer solution;

[0076] Step (4) is as follows: Take the negative electrode material precursor and mix it with the polymer monomer solution obtained in step (3), add 0.002g of FeCl3 as an initiator, stir evenly under room temperature conditions, transfer it to a kneading pot, and knead it for 10h under room temperature and nitrogen protection conditions to obtain phosphorus carbon negative electrode material.

[0077] Comparative Example 1

[0078] The difference from Example 2 is that in step (2), only one solid-liquid separation is performed, and the obtained filter residue B1 is dried under vacuum at 200°C for 4 hours to obtain phosphorus-carbon material.

[0079] Comparative Example 2

[0080] (1) Mix 10g of red phosphorus and 10g of porous carbon in a mass ratio of 1:1 to obtain a solid mixture. Place the solid mixture in a vacuum rotary furnace. First, purge the air in the tube with nitrogen gas at a flow rate of 1mL / min. After 1 hour of purging, close the gas valves on both sides and evacuate to a vacuum of 10Pa. Raise the temperature to 450℃ at a heating rate of 5℃ / min and hold for 6 hours. Then, lower the temperature to 260℃ at a cooling rate of 1℃ / min and hold for 12 hours. After the holding period, allow the material to cool naturally. Then, open the furnace door to take a sample to obtain the phosphorus-carbon material.

[0081] (2) Take 0.2g of polyacrylonitrile and add it to 20mL of N-methylpyrrolidone solvent. Heat to 80℃ and stir for 30min at a speed of 400r / min to obtain a polyacrylonitrile solution with a mass concentration of 0.01g / mL.

[0082] (3) Take the above phosphorus carbon anode precursor and polyacrylonitrile solution and mix them. After stirring evenly at room temperature, transfer them to a kneading pot and knead them at 200°C under nitrogen protection for 4 hours to obtain polyacrylonitrile-coated phosphorus carbon anode material.

[0083] Electrochemical performance testing:

[0084] A mixed negative electrode slurry was formed in water at a ratio of 1:1:8 using carboxymethyl cellulose (CMC) binder, styrene-butadiene rubber (SBR) (mass ratio 1:1), conductive agent Super P, and phosphorus-carbon negative electrode materials prepared in the examples and comparative examples. This slurry was then uniformly coated onto copper foil to obtain a negative electrode sheet with a thickness of approximately 100 μm. The coated negative electrode sheet was cut and vacuum dried at 60 °C for 12 h. Using metallic sodium as the counter electrode and a 1.0 mol / L LiPF6 ethyl carbonate / dimethyl carbonate solution as the electrolyte, a button cell was assembled in an argon atmosphere. After aging for 6 h, electrochemical tests were performed on a Blue Electric CT3002A charge-discharge testing system at room temperature. The battery was first allowed to stand for 10 min, then discharged at a constant current of 0.05 C to 5 mV, then allowed to stand for another 10 min, and then charged at a constant current of 0.1 C to 2 V. The cycle time was 2 weeks. The measured battery capacity, initial battery efficiency, and cycle number are shown in Table 1.

[0085] Resistivity test:

[0086] Weigh 3g ± 0.01g of the phosphorus-carbon anode material prepared in the examples and comparative examples as samples. Pour the samples into a mold and place them on the test platform. First, test within the range of 4.9MPa-5.1MPa. If the pressure value is too high or too low, make a fine adjustment according to the "+-" direction on the pressure regulating valve. Then increase the pressure to 30MPa. The resistivity of the phosphorus-carbon anode material is shown in Table 1.

[0087] Table 1

[0088]

[0089] As can be seen from the data in Table 1, the phosphorus-carbon anode material obtained in Example 1 through multi-step liquid-phase impregnation has a higher red phosphorus deposition amount, providing a higher anode capacity for the electrochemical process. In Example 2, by coating the phosphorus-carbon anode material with a conductive coating layer, both its initial efficiency and cycle performance are improved. Furthermore, after coating with a conductive polymer, its powder resistivity is significantly reduced, and its conductivity is significantly improved. The phosphorus-carbon anode materials prepared by Comparative Example 1 (which underwent only one impregnation) and Comparative Example 2 (which used vapor phase deposition) have significantly less red phosphorus deposition amount compared to the phosphorus-carbon anode material in Example 2, resulting in a significant decrease in capacity, and a reduction in both initial efficiency and cycle performance.

[0090] The preferred embodiments have been described in detail above, but the present invention is not limited to the specific implementation methods described above. Those skilled in the art can make various specific modifications under the guidance of this application without departing from the scope of protection of this application, and these modifications all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a phosphorus-carbon anode material, characterized in that, include: Porous carbon was mixed and impregnated with an amine solution of red phosphorus to obtain a mixed slurry. Solid-liquid separation was performed to obtain filtrate and filter residue. The filter residue is dried to obtain a solid. The solid is added to the filtrate, and the mixing, impregnation, solid-liquid separation and drying are repeated until the filtrate is used up to obtain the phosphorus-carbon anode material.

2. The method for preparing the phosphorus-carbon anode material as described in claim 1, characterized in that, The cumulative number of solid-liquid separations is less than or equal to n, where n is greater than or equal to M. RP / (M PC The smallest integer of *V*c), where M RP M represents the mass of the red phosphorus. PC M represents the mass of the porous carbon. RP and M PC The unit is g; V is the pore volume of the porous carbon, in cm³. 3 / g; c is the concentration of red phosphorus in the amine solution of the red phosphorus, in g / cm³. 3 .

3. The method for preparing the phosphorus-carbon anode material as described in claim 2, characterized in that, The porous carbon has a pore volume of 0.6 cm³. 3 / g-1.5cm 3 / g; the porous carbon includes a pore structure with an average pore size of 1.2nm-10nm; the pore structure includes micropores, the volume of which accounts for 10%-90% of the total volume of the pore structure.

4. The method for preparing the phosphorus-carbon anode material as described in claim 2, characterized in that, In the amine solution of red phosphorus, the concentration of red phosphorus is 0.01 g / mL to 10 g / mL; the mass ratio of red phosphorus to porous carbon is (0.1-1.5):

1.

5. The method for preparing the phosphorus-carbon anode material as described in claim 4, characterized in that, The preparation method of the red phosphorus amine solution includes the following steps: mixing red phosphorus with an amine solvent; the mixing temperature is 60℃-120℃ and the time is 24h-72h; the amine solvent includes one or more of ethylenediamine, formamide, isopropylamine, N,N-dimethylformamide, N-methylpyrrolidone and dimethyl sulfoxide.

6. The method for preparing the phosphorus-carbon anode material according to any one of claims 1-5, characterized in that, It also includes the step of forming a coating layer on the surface of the phosphorus-carbon anode material; the coating layer includes a conductive polymer coating layer.

7. A phosphorus-carbon anode material prepared by the preparation method according to any one of claims 1-6, characterized in that, The phosphorus-carbon anode material includes a porous carbon matrix and red phosphorus particles loaded in the pore structure of the porous carbon matrix.

8. The phosphorus-carbon anode material as described in claim 7, characterized in that, The mass of the red phosphorus particles in the phosphorus-carbon anode material is less than or equal to M. PC *V*ρ RP , of which M PC V represents the mass of the porous carbon, in grams; V represents the pore volume of the porous carbon matrix, in centimeters. 3 / g;ρ RP The density of red phosphorus is expressed in g / cm³. 3 .

9. The phosphorus-carbon anode material as described in claim 7 or 8, characterized in that, The surface of the phosphorus-carbon anode material also includes a conductive polymer coating layer.

10. A negative electrode sheet, characterized in that, The negative electrode sheet includes a current collector and a negative electrode active layer disposed on the surface of the current collector, wherein the negative electrode active layer includes a phosphorus-carbon negative electrode material prepared by the preparation method according to any one of claims 1-6 or a phosphorus-carbon negative electrode material according to any one of claims 7-9.

11. A battery, characterized in that, The battery includes a positive electrode, a negative electrode, a separator and an electrolyte located between the positive electrode and the negative electrode, wherein the negative electrode includes the negative electrode as described in claim 10.

12. An electrical appliance, characterized in that, The electrical device includes the battery as described in claim 11.

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