Metallic battery anode material, method for preparing same, and use thereof

Abstract

This invention relates to the field of metal battery technology, specifically to a metal battery anode material, its preparation method, and its application. The preparation method includes the following steps: dispersing porous carbon fibers and non-carbon fibers in a solvent to obtain a mixed dispersion; removing the solvent from the mixed dispersion; wherein the dispersion and / or sedimentation rate of the porous carbon fibers in the solvent differs from that of the non-carbon fibers; the porous carbon fibers are doped with heterogeneous elements, and the non-carbon fibers are doped with metal ions. The metal battery anode material prepared by this invention has a self-supporting three-dimensional gradient framework structure. This three-dimensional gradient framework structure can accommodate more rapid and uniform metal deposition and effectively suppress metal dendrite growth; moreover, the non-carbon fibers form a support layer, enabling the electrode to have good thermal stability, which is beneficial to improving the electrochemical performance and safety performance of the metal battery system.

Description

Technical Field

[0001] This invention relates to the field of metal battery technology, specifically to a metal battery anode material, its preparation method, and its application. Background Technology

[0002] With the continued development and utilization of traditional energy sources, problems such as resource depletion and environmental pollution are becoming increasingly serious, making clean and sustainable energy storage a focus of widespread attention. However, with the upgrading of electrical equipment, even the most widely used and relatively high-performance lithium-ion rechargeable batteries are gradually failing to meet the demands of electrical equipment for fast charging, cycle life, and energy density. Therefore, the development of next-generation high-efficiency energy storage devices is urgently needed.

[0003] Among various energy storage devices, metal batteries, by directly using metal as the negative electrode, possess high energy density and low electrode potential, thus exhibiting significant advantages. Unlike the reaction mechanism of ion batteries, the negative electrode side of a metal battery undergoes a metal deposition and stripping reaction. During charging and discharging, the battery typically operates at a constant current density, with the same current flowing through both electrodes. However, the positive electrode is usually porous with a relatively uniform electric field distribution, while the metal negative electrode is non-porous, resulting in extremely high local current density on its surface. This leads to uneven local electric field strength, causing metal dendrites to grow on the metal negative electrode. Consequently, this destabilizes the SEI film, exacerbates side reactions between the metal negative electrode and the electrolyte, and ultimately affects the safety and energy utilization efficiency of the battery system. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defect of metal dendrite growth in the metal battery anode in the prior art, thereby providing a metal battery anode material, its preparation method and application.

[0005] Therefore, the present invention provides a method for preparing a metal battery anode material, comprising the following steps:

[0006] Porous carbon fibers and non-carbon fibers are dispersed in a solvent to obtain a mixed dispersion;

[0007] Remove the solvent from the mixed dispersion;

[0008] The porous carbon fibers have different dispersion and / or sedimentation rates in the solvent compared to the non-carbon fibers in the solvent; the porous carbon fibers are doped with impurity elements, while the non-carbon fibers are doped with metal ions.

[0009] Optionally, removing the solvent from the mixed dispersion includes:

[0010] The mixed dispersion is then filtered or freeze-dried.

[0011] Optionally, the porous carbon fiber has a porosity of 1–30%, a pore size of 0.0001–100 μm, and a pore volume of 0.5–5 cm³. 3 / g, specific surface area of ​​50-4000m² 2 / g;

[0012] Optionally, the heteroelement includes at least one of oxygen, nitrogen, sulfur, chlorine, fluorine, and phosphorus.

[0013] Optionally, the weight of the impurity element accounts for 0.5% to 20% of the weight of the porous carbon fiber.

[0014] Optionally, the preparation process of the porous carbon fiber includes the following steps:

[0015] Take carbon fiber precursor and perform first electrospinning and carbonization treatment.

[0016] Optionally, the conditions for the first electrospinning include: a spinning temperature of 20–80°C, a spinning time of 1–10 h, a positive voltage of 10–20 kV, a negative voltage of -10–-2 kV, a receiving distance of 10–30 cm, and a feed speed of 0.05–0.30 mm / min.

[0017] Optionally, the carbonization process includes: carbonizing at a temperature of 400–800°C for 1–3 hours in a protective gas atmosphere;

[0018] Optionally, the carbon fiber precursor includes at least one of gelatin, lignin fiber, soybean protein, corn protein, cellulose acetate and dextran;

[0019] Optionally, before performing the first electrospinning, the process further includes adding an inorganic compound, said inorganic compound including at least one of potassium sulfide, sodium sulfide, potassium chloride, potassium nitrate, sodium fluoride, and potassium dihydrogen phosphate.

[0020] Optionally, the inorganic compound has a particle size of 1 to 100 μm, and the amount of the inorganic compound added is 6 to 40% of the weight of the carbon fiber precursor.

[0021] Optionally, the non-carbon fiber has a porosity of 0.2–5%, a pore size of 5–100 μm, and a pore volume of 0.05–0.3 cm³. 3 / g, specific surface area of ​​1-50m² 2 / g;

[0022] Optionally, the metal ions account for 0.5% to 20% of the weight of the non-carbon fiber.

[0023] Optionally, the metal ions include at least one selected from lithium ions, sodium ions, potassium ions, magnesium ions, aluminum ions, zinc ions, iron ions, nickel ions, cobalt ions, and chromium ions;

[0024] The non-carbon fiber includes at least one of hydroxyapatite fiber, cellulose fiber, perovskite fiber, metal sulfide fiber, metal oxide fiber, PVDF fiber, PEO fiber, and PAN fiber.

[0025] Optionally, the process of doping the non-carbon fiber with the metal ions includes the following steps:

[0026] Take the non-carbon fiber, immerse it in a solution of metal salt for 10–20 hours, then remove and dry; or,

[0027] Take the raw material used to form the non-carbon fiber, mix it with a metal salt, and perform a second electrospinning.

[0028] Optionally, the metal salt includes at least one of the following: chloride salts, sulfide salts, sulfate salts, nitrate salts, perchlorates, hexafluorophosphates, trifluoromethanesulfonates, and tetrafluoroborates of lithium, sodium, potassium, magnesium, aluminum, zinc, iron, nickel, cobalt, and chromium.

[0029] Optionally, the concentration of the metal salt in the solution is 0.0001 g / mL to 0.1 g / mL, preferably 0.0005 g / mL to 0.05 g / mL;

[0030] Optionally, the conditions for the second electrospinning include: a spinning temperature of 20–30°C, a spinning time of 2–5 h, a positive voltage of 15–30 kV, a negative voltage of -10–-1 kV, a receiving distance of 15–30 cm, and a feed speed of 0.10–0.30 mm / min.

[0031] For example, hydroxyapatite fibers, cellulose fibers, and perovskite fibers can be doped with the metal ions by the impregnation method described above; metal sulfide fibers, metal oxide fibers, PVDF fibers, PEO fibers, and PAN fibers can be doped with the metal ions by the electrospinning method described above. The raw materials used to form non-carbon fibers can be PEO, PVDF, PAN, metal oxides, or metal sulfides.

[0032] Optionally, the dispersion of porous carbon fibers and non-carbon fibers in a solvent to obtain a mixed dispersion includes:

[0033] The porous carbon fiber and the non-carbon fiber are placed in the solvent and sonicated for 1.5 to 3 hours to obtain the mixed dispersion.

[0034] Optionally, the weight ratio of the porous carbon fiber to the non-carbon fiber is (1-10):(1-100), preferably 1:(1-50);

[0035] Optionally, the weight ratio of the porous carbon fiber to the solvent is 1:(100-10000), preferably 1:(1000-6000);

[0036] Optionally, the solvent includes at least one of ethanol, methanol, water, diethyl ether, acetone, N-methylpyrrolidone, and ethyl acetate.

[0037] The present invention also provides a metal battery anode material prepared by the preparation method described above, wherein the metal battery anode material has a three-dimensional fibrous structure, a porosity of 0.5-25%, a pore size of 0.1 nm-100 μm, and a pore volume of 0.1-3 cm³. 3 / g, specific surface area of ​​10–3000 cm² 2 / g, fiber aspect ratio is (100~10000):1.

[0038] The present invention also provides a metal battery anode, wherein the metal battery anode comprises the metal battery anode material described above.

[0039] The present invention also provides a metal battery, wherein the metal battery includes the metal battery negative electrode material or the metal battery negative electrode described above.

[0040] The technical solution of this invention has the following advantages:

[0041] 1. The method for preparing a metal battery anode material provided by this invention first disperses porous carbon fibers and non-carbon fibers with different dispersibility and / or sedimentation rates in a solvent, and then removes the solvent to obtain the metal battery anode material. Due to the different dispersibility and / or sedimentation rates of the two fibers in the solvent, the two fibers exhibit a stratification trend in the mixed dispersion, and the concentrations of the two fibers in the mixed dispersion gradually increase in opposite directions. This also results in a stratification trend in the prepared metal battery anode material. However, at the contact points, both fibers extend into each other's fiber structures, and along the direction from the porous carbon fiber layer to the non-carbon fiber layer, the content of porous carbon fibers gradually decreases, while the content of non-carbon fibers gradually increases. That is, the metal battery anode material prepared by the method of this invention has a self-supporting three-dimensional gradient framework structure. This three-dimensional gradient framework structure can accommodate more metal for rapid and uniform deposition and can effectively suppress metal dendrite growth. Moreover, the non-carbon fibers form a support layer, which enables the electrode to have good thermal stability, which is beneficial to improving the electrochemical performance and safety performance of the metal battery system.

[0042] Furthermore, in the metal battery anode material prepared above, porous carbon fibers, as conductive fibers, can provide efficient electron transport channels during metal deposition and stripping; the abundant pore structure can serve as an electrolyte buffer, promoting the diffusion of metal ions and improving ion transport capability; the doped heteroelements can provide abundant metal-affinity sites, enabling metal to be deposited quickly and uniformly on the surface of porous carbon fibers, effectively preventing metal dendrite growth caused by metal accumulation in porous carbon fibers; along the direction from the non-carbon fiber layer to the porous carbon fiber layer, the porous carbon fiber layer gradually increases, that is, the metal-affinity sites gradually increase, which can effectively induce metal ions to preferentially deposit at the bottom of the anode material (i.e., the bottom of the porous carbon fiber layer), thereby effectively inhibiting the deposition of metal ions at the top of the anode material (i.e., the top of the non-carbon fiber layer), which can further prevent metal dendrite growth;

[0043] Non-carbon fiber layers, used as a support layer covering the surface of porous carbon fiber layers, can effectively improve the mechanical and flame-retardant properties of the anode material. They can also suppress the growth of metal dendrites through physical constraints. Meanwhile, the doped metal ions can provide efficient ion transport channels during the deposition and stripping of metals.

[0044] 2. The method for preparing metal battery anode material provided by the present invention utilizes the different dispersion and / or sedimentation rates of two types of fibers in a solvent to obtain a self-supporting metal battery anode material with a three-dimensional gradient framework structure through a simple one-step filtration or freeze-drying process. This method is not only simple and efficient, safe and environmentally friendly, low in cost and reproducible, but also produces anode material with continuous layers, good connectivity and conductivity. Detailed Implementation

[0045] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0046] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0047] Example 1

[0048] Metal battery anode materials were prepared according to the following method:

[0049] (1) Preparation of porous carbon fibers:

[0050] A 15% (w / w) gelatin aqueous solution was used as the spinning solution for electrospinning. The electrospinning temperature was 65℃, the spinning time was 8h, the positive voltage was 14kV, the negative voltage was -5kV, the receiving distance was 20cm, and the feed speed was 0.2mm / min. After electrospinning, the resulting product was placed in a protective gas atmosphere and carbonized at 700℃ for 1.5h to obtain gelatin carbon fibers, which were then used as porous carbon fibers.

[0051] The porous carbon fibers prepared above are doped with oxygen and nitrogen elements, with oxygen doping amounting to 5.4% and nitrogen doping amounting to 2.4% of the weight of the porous carbon fibers. The porous carbon fibers have a porosity of 25%, a pore size of 0.005–20 μm, and a pore volume of 0.89 cm³. 3 / g, specific surface area is 1250m² 2 / g.

[0052] (2) Preparation of non-carbon fiber materials:

[0053] 1g of hydroxyapatite was placed in 100mL of ethanol solution containing 0.15g of lithium chloride, soaked for 15h, and then dried to obtain lithium-ion-doped hydroxyapatite fibers, which were used as non-carbon fibers.

[0054] The non-carbon fiber prepared above is doped with lithium ions at a doping amount of 4.2% of the non-carbon fiber weight. Its porosity is 1.1%, pore size is 5–50 μm, and pore volume is 0.08 cm³. 3 / g, specific surface area 32m² 2 / g.

[0055] (3) Preparation of negative electrode materials:

[0056] Weigh 20 mg of the porous carbon fiber and 100 mg of the non-carbon fiber (weight ratio of 1:5) and add them to a beaker containing 150 mL of ethanol solution. Then place the beaker in an ultrasonic machine and sonicate for 3 hours until the mixture is homogeneous to obtain a mixed dispersion. Set up a filtration device and use the different dispersibility of the two fibers to filter the prepared mixed dispersion into a film. After removing the film and drying it, a negative electrode material with a three-dimensional gradient framework structure is obtained.

[0057] The anode material prepared above includes a porous carbon fiber layer and a non-carbon fiber layer, which are in contact with each other. Both types of fibers extend into each other's fiber structure at the contact points. Along the direction from the porous carbon fiber layer to the non-carbon fiber layer, the content of porous carbon fiber gradually decreases, while the content of non-carbon fiber gradually increases. It is doped with lithium, oxygen, and nitrogen elements. The overall porosity of the material is 15%, the pore size is 5 nm to 50 μm, and the pore volume is 0.28 cm³. 3 / g, specific surface area is 550m² 2 / g, fiber aspect ratio range is (4000~6000):1.

[0058] (4) Performance Testing

[0059] The prepared negative electrode material was cut into 14mm diameter discs to serve as the negative electrode. A lithium metal sheet was used as the counter electrode, PP was used as the separator, and 1M LiPF6 (EC / DEC 1:1) was used as the electrolyte to assemble a half-cell. The electrolyte was then applied at 1mA / cm². 2 Lithium was deposited by constant current discharge at a current density, with a cutoff capacity set at 1 mAh / cm³. 2 The cutoff voltage was 1V, and the overpotential was measured to be 25mV. Next, a lithium deposition stripping test was performed at 1mA / cm. 2 Current density, 1mAh / cm 2 After 200 cycles at the deposition / exfoliation capacity, its coulombic efficiency was retained at 96.5%; at 1 mA / cm²... 2 Current density, 1mAh / cm 2 After cycling for 450 hours at the deposition / stripping capacity, the voltage remained stable, indicating good long-cycle performance.

[0060] The performance test results above clearly show that the anode material prepared by the above method exhibits excellent electrochemical performance when used as a lithium metal substrate.

[0061] Example 2

[0062] The metal battery anode material was prepared according to the method of Example 1, except that the porous carbon fiber in this example is lignin carbon fiber, and the non-carbon fiber is cellulose fiber. Specifically, the preparation methods of the porous carbon fiber and the non-carbon fiber in this example are as follows:

[0063] (1) Preparation of porous carbon fibers:

[0064] Using a lignin aqueous solution with a mass percentage concentration of 15% as the spinning solution, electrospinning and carbonization were carried out according to the method of step (1) in Example 1 to obtain lignin carbon fibers, which were then used as porous carbon fibers.

[0065] The porous carbon fibers prepared above are doped with oxygen at a doping amount of 7.2% of the carbon fiber weight. They have a porosity of 26%, a pore size of 0.005–25 μm, and a pore volume of 0.86 cm³. 3 / g, specific surface area is 1132m² 2 / g.

[0066] (2) Preparation of non-carbon fiber materials:

[0067] 1g of cellulose fiber was placed in 100mL of ethanol solution containing 0.15g of lithium chloride, soaked for 15h, and then dried to obtain lithium-ion-doped cellulose fiber, which was used as a non-carbon fiber.

[0068] The non-carbon fiber prepared above is doped with lithium ions, with a doping amount of 4.3% of the total non-carbon fiber content. Its porosity is 1.1%, pore size is 10–60 μm, and pore volume is 0.07 cm³. 3 / g, specific surface area is 28m² 2 / g.

[0069] The negative electrode material prepared in this embodiment is doped with lithium and oxygen. The overall porosity of the material is 14%, the pore size is 5 nm to 60 μm, and the pore volume is 0.25 cm³. 3 / g, specific surface area is 522m² 2 / g, fiber aspect ratio range is (3000~6000):1.

[0070] The performance of the negative electrode material prepared in this embodiment was tested according to the method of Example 1. The overpotential was measured to be 27mV, the coulombic efficiency after 200 cycles was 94.8%, and the voltage remained stable after 450 hours of cycling, showing good long-cycle performance.

[0071] Example 3

[0072] The metal battery anode material was prepared according to the method of Example 1, except that the porous carbon fiber in this example was soybean protein carbon fiber, and the non-carbon fiber was PAN fiber. Specifically, the preparation methods of the porous carbon fiber and the non-carbon fiber in this example are as follows:

[0073] (1) Preparation of porous carbon fibers:

[0074] Using a 15% (w / w) soybean protein aqueous solution as the spinning solution, electrospinning and carbonization were performed according to step (1) in Example 1 to obtain soybean protein carbon fibers, which were then used as porous carbon fibers.

[0075] The porous carbon fibers prepared above are doped with nitrogen at a doping level of 6.9%, with a porosity of 22%, a pore size of 0.005–30 μm, and a pore volume of 0.78 cm³. 3 / g, specific surface area is 989m² 2 / g.

[0076] (2) Preparation of non-carbon fiber materials:

[0077] A PAN solution with a mass percentage concentration of 10% was prepared using DMF as a solvent. Simultaneously, lithium chloride with a mass of 2% of PAN was added to prepare a spinning solution. Electrospinning was then performed to obtain lithium-ion-doped PAN fibers, which were used as non-carbon fibers. The electrospinning temperature was 25℃, the spinning time was 5h, the positive voltage was 15kV, the negative voltage was -8kV, the receiving distance was 25cm, and the feed speed was 0.20mm / min.

[0078] The non-carbon fiber prepared above is doped with lithium ions at a doping level of 3.8%, has a porosity of 0.9%, a pore size of 5–60 μm, and a pore volume of 0.07 cm³. 3 / g, specific surface area is 26m² 2 / g.

[0079] The negative electrode material prepared in this embodiment is doped with lithium and oxygen. The overall porosity of the material is 13%, the pore size is 5 nm to 60 μm, and the pore volume is 0.24 cm³. 3 / g, specific surface area is 488m² 2 / g, fiber aspect ratio range (2000~5000):1.

[0080] The performance of the negative electrode material prepared in this embodiment was tested according to the method of Example 1. The overpotential was measured to be 29mV, the coulombic efficiency after 200 cycles was 94.5%, and the voltage remained stable after 450 hours of cycling, showing good long-cycle performance.

[0081] Example 4

[0082] The metal battery anode material was prepared according to the method of Example 1. The difference is that in this example, 0.6g of potassium sulfide was added to the gelatin aqueous solution when preparing porous carbon fibers to regulate the pore structure of the obtained carbon fibers and to achieve the incorporation of sulfur.

[0083] The porous carbon fibers prepared above are doped with oxygen, nitrogen, and sulfur. The oxygen doping amount is 4.8% of the weight of the porous carbon fibers, the nitrogen doping amount is 2.1% of the weight of the porous carbon fibers, and the sulfur doping amount is 1.9% of the weight of the porous carbon fibers. The porosity of this porous carbon fiber is 29%, the pore size is 0.005-20 μm, and the pore volume is 1.08 cm³. 3 / g, specific surface area is 1780m² 2 / g.

[0084] The negative electrode material prepared in this embodiment is doped with lithium, oxygen, nitrogen, and sulfur. The overall porosity of the material is 23%, the pore size ranges from 0.2 nm to 50 μm, and the pore volume is 2.0 cm³. 3 / g, specific surface area is 2001m² 2 / g, fiber aspect ratio range (800~5000):1.

[0085] The performance of the negative electrode material prepared in this embodiment was tested according to the method of Example 1. The overpotential was measured to be 18mV, the coulombic efficiency after 200 cycles was 99.2%, and the voltage remained stable after 500 hours of cycling, showing good long-cycle performance.

[0086] Example 5

[0087] The metal battery anode material was prepared according to the method of Example 1. The difference is that in this example, the weight ratio of porous carbon fiber to non-carbon fiber in the preparation of the anode material is 1:20. That is, in step (3), the amount of porous carbon fiber weighed is 20mg and the amount of non-carbon fiber weighed is 400mg.

[0088] The negative electrode material prepared in this embodiment is doped with lithium, oxygen, and nitrogen. The overall porosity of the material is 7%, the pore size ranges from 8 to 60 nm, and the pore volume is 0.26 cm³. 3 / g, specific surface area is 232m² 2 / g, fiber aspect ratio range is (4000~7000):1.

[0089] The performance of the negative electrode material prepared in this embodiment was tested according to the method of Example 1. The overpotential was measured to be 31mV, the coulombic efficiency after 200 cycles was 93.5%, and the voltage remained stable after 450 hours of cycling, showing good long-cycle performance.

[0090] Example 6

[0091] The metal battery anode material was prepared according to the method of Example 1, except that the amount of lithium chloride used in the preparation of non-carbon fiber in this example was 0.75g.

[0092] The non-carbon fiber prepared above is doped with lithium ions at a doping amount of 7.2% of the non-carbon fiber weight. Its porosity is 1.9%, pore size is 5–60 μm, and pore volume is 0.11 cm³. 3 / g, specific surface area 50m² 2 / g.

[0093] The negative electrode material prepared in this embodiment is doped with lithium, oxygen, and nitrogen. The overall porosity of the material is 17%, the pore size ranges from 8 nm to 65 μm, and the pore volume is 0.30 cm³. 3 / g, specific surface area 560m² 2 / g, fiber aspect ratio range (500~4000):1.

[0094] The performance of the negative electrode material prepared in this embodiment was tested according to the method of Example 1. The overpotential was measured to be 30mV, the coulombic efficiency after 200 cycles was 94.2%, and the voltage remained stable after 450 hours of cycling, showing good long-cycle performance.

[0095] Example 7

[0096] Metal battery anode materials were prepared according to the method of Example 1, except that in this example, an equal amount of zinc nitrate was used to replace lithium chloride in the preparation of non-carbon fiber. The non-carbon fiber prepared above was doped with zinc ions at a doping level of 8.7%, with a porosity of 2%, a pore size of 8–65 μm, and a pore volume of 0.1 cm³. 3 / g, specific surface area is 45m² 2 / g.

[0097] The negative electrode material prepared in this embodiment is doped with zinc, oxygen, and nitrogen. The overall porosity of the material is 18%, the pore size ranges from 5 nm to 65 μm, and the pore volume is 0.42 cm³. 3 / g, specific surface area is 677m² 2 / g, fiber aspect ratio range is (3000~6000):1.

[0098] The negative electrode material prepared in this embodiment was cut into circular pieces with a diameter of 14 mm to serve as the negative electrode. A zinc metal sheet was used as the counter electrode, glass fiber was used as the separator, and a 2 mol / L ZnSO4 solution was used as the electrolyte to assemble a half-cell. At 1 mA / cm², 2 Zinc is deposited by constant current discharge at a current density, with a cutoff capacity set at 1 mAh / cm³. 2 The cutoff voltage was 0.5V, and the overpotential was measured to be 25mV. Next, a zinc deposition stripping test was performed, which showed a value of 1mA / cm. 2 1mAh / cm 2 Under certain conditions, the coulombic efficiency remained at 97.8% after 200 cycles, demonstrating excellent performance; at a current of 1 mA / cm², the efficiency was maintained at 97.8%. 2 The deposition / stripping capacity is 1 mAh / cm³. 2 Under certain conditions, the voltage remains stable after 400 hours of cycling, demonstrating good long-cycle performance.

[0099] Example 8

[0100] Metal battery anode materials were prepared according to the method of Example 1, except that in this example, an equal amount of sodium sulfide was used to replace lithium chloride in the preparation of non-carbon fiber. The non-carbon fiber prepared above was doped with sodium ions at a doping amount of 4.2%, with a porosity of 0.8%, a pore size of 15–60 μm, and a pore volume of 0.06 cm³. 3 / g, specific surface area 18m²2 / g.

[0101] The negative electrode material prepared in this embodiment is doped with sodium, oxygen, and nitrogen. The overall porosity of the material is 12%, the pore size ranges from 5 nm to 60 μm, and the pore volume is 0.39 cm³. 3 / g, specific surface area is 401m² 2 / g, fiber aspect ratio range is (3000~5000):1.

[0102] The negative electrode material prepared in this embodiment was cut into circular pieces with a diameter of 14 mm to serve as the negative electrode. A sodium metal sheet was used as the counter electrode, glass fiber as the separator, and NaPF6 (100% diglyme) as the electrolyte to assemble a half-cell. The electrolyte was then applied at 0.5 mA / cm². 2 Sodium was deposited by constant current discharge at a specific current density, with a cutoff capacity set at 0.5 mAh / cm³. 2 With a cutoff voltage of 0.5V, its overpotential was measured to be 23mV; subsequently, a sodium deposition stripping test was performed, which showed a value of 0.5mA / cm. 2 0.5mAh / cm 2 Under certain conditions, the coulombic efficiency remained at 96.9% after 200 cycles, demonstrating excellent performance; at a current of 0.5 mA / cm², the efficiency was maintained at 96.9%. 2 The deposition / stripping capacity is 0.5 mAh / cm³. 2 Under certain conditions, the voltage remains stable after 300 hours of cycling, demonstrating good long-cycle performance.

[0103] Example 9

[0104] The metal battery anode material was prepared according to the method of Example 1. The difference is that in this example, an equal amount of water was used to replace the ethanol solution as a solvent when preparing the anode material, so as to improve the dispersion of the two fibers in the mixed dispersion.

[0105] The negative electrode material prepared in this embodiment is doped with lithium, oxygen, and nitrogen. The overall porosity of the material is 15%, the pore size ranges from 5 nm to 50 μm, and the pore volume is 0.27 cm³. 3 / g, specific surface area is 445m² 2 / g, fiber aspect ratio range is (4000~6000):1.

[0106] The performance of the negative electrode material prepared in this embodiment was tested according to the method of Example 1. The overpotential was measured to be 28mV, and the coulombic efficiency after 200 cycles was 95.4%, which is excellent. The voltage can still remain stable after 400 hours of cycling, showing good long-cycle performance.

[0107] Example 10

[0108] Metal battery anode materials were prepared according to the method of Example 1. The difference is that in this example, the filtration film formation process was replaced with a freeze-drying process when preparing the anode material. The freeze-drying process was carried out for 36 hours to obtain an anode material with a three-dimensional gradient framework structure.

[0109] The negative electrode material prepared in this embodiment is doped with lithium, oxygen, and nitrogen. The overall porosity of the material is 18%, the pore size ranges from 5 nm to 100 μm, and the pore volume is 0.51 cm³. 3 / g, specific surface area is 812m² 2 / g, fiber aspect ratio range is (3000~6000):1.

[0110] The negative electrode material prepared in this embodiment was tested according to the method of Example 1. The overpotential was measured to be 23mV, and the coulombic efficiency after 200 cycles was 98.7%, which is excellent. The voltage can still remain stable after 450 hours of cycling, showing good long-cycle performance.

[0111] Comparative Example 1

[0112] In this comparative example, the porous carbon fiber prepared in step (1) of Example 1 was used directly to prepare the negative electrode material. Specifically, 120 mg of the above porous carbon fiber was weighed and added to a beaker containing 150 mL of ethanol solution. The beaker was then placed in an ultrasonic machine and ultrasonicated for 3 hours until it was mixed evenly to obtain a mixed dispersion. A filtration device was set up, and the mixed dispersion prepared above was filtered into a film by utilizing the different dispersibility of the two fibers. After being removed and dried, the negative electrode material was obtained.

[0113] The performance of the negative electrode material prepared in this comparative example was tested according to the method of Example 1. The overpotential was measured to be 35mV, the coulombic efficiency retention rate after 200 cycles was 41%, and the voltage exceeded the range after 150 hours of cycling, so the test was stopped.

[0114] Comparative Example 2

[0115] In this comparative example, the non-carbon fiber obtained in step (2) of Example 1 was used directly to prepare the negative electrode material. Specifically, 120 mg of the above non-carbon fiber was weighed and added to a beaker containing 150 mL of ethanol solution. Then, it was placed in an ultrasonic machine and ultrasonicated for 3 hours until it was mixed evenly to obtain a mixed dispersion. A vacuum filtration device was set up, and the mixed dispersion prepared above was filtered into a film by utilizing the different dispersibility of the two fibers. After being removed and dried, the negative electrode material was obtained.

[0116] The performance of the negative electrode material prepared in this comparative example was tested according to the method of Example 1. The overpotential was measured to be 48mV. The battery was damaged after 20 cycles, and the voltage exceeded the range after 30 hours of cycling, so the test was stopped.

[0117] Comparative Example 3

[0118] The negative electrode material was prepared according to the following method:

[0119] (1) Using the porous carbon fiber prepared in step (1) of Example 1 as raw material, a porous carbon fiber membrane with a thickness of 40 μm was pressed.

[0120] (2) Using the non-carbon fiber prepared in step (2) of Example 1 as raw material, press a non-carbon fiber film with a thickness of 40 μm;

[0121] (3) The above porous carbon fiber membrane and non-carbon fiber membrane are stacked and pressed to obtain the negative electrode material.

[0122] The performance of the negative electrode material prepared in this comparative example was tested according to the method of Example 1. The overpotential was measured to be 38mV, the coulombic efficiency retention rate after 200 cycles was 23.4%, and the voltage exceeded the range after 450 hours of cycling, so the test was stopped.

[0123] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a metal battery anode material, characterized in that, Includes the following steps: Porous carbon fibers and non-carbon fibers are dispersed in a solvent to obtain a mixed dispersion; Remove the solvent from the mixed dispersion; The porous carbon fibers have different dispersibility and / or sedimentation rate in the solvent compared to the non-carbon fibers in the solvent; the porous carbon fibers are doped with impurity elements, while the non-carbon fibers are doped with metal ions. The hetero-elements include at least one of oxygen, nitrogen, sulfur, chlorine, fluorine, and phosphorus. The metal ions include at least one of lithium ions, sodium ions, potassium ions, magnesium ions, aluminum ions, zinc ions, iron ions, nickel ions, cobalt ions, and chromium ions.

2. The preparation method according to claim 1, characterized in that, The removal of the solvent from the mixed dispersion includes: The mixed dispersion is then filtered or freeze-dried.

3. The preparation method according to claim 1, characterized in that, The porous carbon fiber has a porosity of 1-30%, a pore size of 0.0001-100 μm, and a pore volume of 0.5-5 cm³. 3 / g, specific surface area of ​​50-4000m² 2 / g; The weight of the impurity element accounts for 0.5 to 20% of the weight of the porous carbon fiber.

4. The preparation method according to claim 3, characterized in that, The preparation process of the porous carbon fiber includes the following steps: Take carbon fiber precursor and perform first electrospinning and carbonization treatment. The conditions for the first electrospinning include: a spinning temperature of 20–80°C, a spinning time of 1–10 h, a positive voltage of 10–20 kV, a negative voltage of -10–-2 kV, a receiving distance of 10–30 cm, and a feed speed of 0.05–0.30 mm / min. The carbonization process includes: carbonizing at a temperature of 400–800°C for 1–3 hours in a protective gas atmosphere; The carbon fiber precursor includes at least one of gelatin, lignin fiber, soybean protein, corn protein, cellulose acetate, and dextran; Prior to the first electrospinning, the process further includes adding an inorganic compound, which includes at least one of potassium sulfide, sodium sulfide, potassium chloride, potassium nitrate, sodium fluoride, and potassium dihydrogen phosphate.

5. The preparation method according to claim 1, characterized in that, The non-carbon fiber has a porosity of 0.2–5%, a pore size of 5–100 μm, and a pore volume of 0.05–0.3 cm³. 3 / g, specific surface area of ​​1-50m² 2 / g; The metal ions account for 0.5% to 20% of the weight of the non-carbon fiber. The non-carbon fiber includes at least one of hydroxyapatite fiber, cellulose fiber, perovskite fiber, metal sulfide fiber, metal oxide fiber, PVDF fiber, PEO fiber, and PAN fiber.

6. The preparation method according to claim 5, characterized in that, The process of doping the non-carbon fiber with the metal ions includes the following steps: Take the non-carbon fiber, immerse it in a solution of metal salt for 10–20 hours, then remove and dry; or, Take the raw material used to form the non-carbon fiber, mix it with a metal salt, and perform a second electrospinning. The metal salt includes at least one of the following: chloride salts, sulfide salts, sulfate salts, nitrate salts, perchlorates, hexafluorophosphates, trifluoromethanesulfonates, and tetrafluoroborates of lithium, sodium, potassium, magnesium, aluminum, zinc, iron, nickel, cobalt, and chromium. The concentration of the metal salt in the solution is 0.0001 g / mL to 0.1 g / mL; The conditions for the second electrospinning include: a spinning temperature of 20–30°C, a spinning time of 2–5 h, a positive voltage of 15–30 kV, a negative voltage of -10–-1 kV, a receiving distance of 15–30 cm, and a feed speed of 0.10–0.30 mm / min.

7. The preparation method according to claim 6, characterized in that, The concentration of the metal salt in the solution is 0.0005 g / mL to 0.05 g / mL.

8. The preparation method according to claim 1, characterized in that, The process of dispersing porous carbon fibers and non-carbon fibers in a solvent to obtain a mixed dispersion includes: The porous carbon fiber and the non-carbon fiber are placed in the solvent and sonicated for 1.5 to 3 hours to obtain the mixed dispersion. The weight ratio of the porous carbon fiber to the non-carbon fiber is (1-10):(1-100). The solvent includes at least one of ethanol, methanol, water, diethyl ether, acetone, N-methylpyrrolidone, and ethyl acetate.

9. The preparation method according to claim 8, characterized in that, The weight ratio of the porous carbon fiber to the non-carbon fiber is 1:(1-50).

10. A metal battery anode material prepared by the preparation method according to any one of claims 1 to 9, wherein the metal battery anode material has a three-dimensional fibrous structure, a porosity of 0.5 to 25%, a pore size of 0.1 nm to 100 μm, and a pore volume of 0.1 to 3 cm³. 3 / g, specific surface area of ​​10–3000 cm² 2 / g, fiber aspect ratio is (100~10000):

1.

11. A metal battery negative electrode, characterized in that, The metal battery anode comprises the metal battery anode material as described in claim 10.

12. A metal battery, characterized in that, The metal battery includes the metal battery negative electrode material of claim 10 or the metal battery negative electrode of claim 11.