A negative electrode material for a lithium-ion battery, a lithium-ion battery, and a preparation method thereof

Abstract

A negative electrode material for a lithium-ion battery, a lithium-ion battery and a preparation method thereof, belonging to the technical field of secondary batteries. The negative electrode material for a lithium-ion battery comprises a MOF material obtained by reacting a zinc salt with 1H-1,2,3-triazole, and a porous carbon material doped with zinc and zinc cyanide is obtained after carbonization. The porous carbon material has good electronic conductivity, a large volume expansion tolerance, and zinc and zinc cyanide have a lithiumophilic property, which can reduce the nucleation potential of lithium metal, realize the uniform deposition and stripping of lithium ions, avoid the formation and growth of lithium dendrites, and improve the cycle performance and safety performance of the lithium-ion battery.

Description

Technical Field

[0001] This application relates to the technical field of secondary batteries, and more particularly, to a negative electrode material for a lithium-ion battery, a lithium-ion battery, and a preparation method thereof. Background Art

[0002] Secondary batteries, especially lithium-ion batteries, have the advantages of high energy density, high output voltage, no memory effect, no environmental pollution, etc. They can be used not only in portable electronic devices, but also as power sources for electric vehicles and energy storage components for devices such as solar or wind energy, and have good application prospects.

[0003] Traditional lithium-ion batteries generally use graphite as the negative electrode material, layered lithium cobaltate (LiCoO 2 ) or lithium iron phosphate (LiFePO 4 ) as the positive electrode material, and a non-aqueous lithium-ion conductive medium as the electrolyte.

[0004] Graphite materials have good layered structures and electrical conductivity, and their theoretical specific capacity is 372 mAh / g. However, existing graphite electrodes are prone to the co-insertion phenomenon of lithium ions and solvent molecules, and the growth of lithium dendrites piercing the separator, which is likely to cause battery short circuits, thus restricting the practical application of lithium-ion batteries. In addition, with the repeated insertion and extraction of lithium ions, the graphite structure continuously expands and contracts repeatedly, causing the graphite sheets to easily fall off and resulting in a rapid attenuation of the electrode material capacity. Summary of the Invention

[0005] Based on the above deficiencies, this application provides a negative electrode material for a lithium-ion battery, a lithium-ion battery, and a preparation method thereof to partially or completely improve the problem that the negative electrode material affects the performance of lithium-ion batteries in related technologies.

[0006] This application is implemented as follows:

[0007] In a first aspect, an example of this application provides a negative electrode material for a lithium-ion battery, including a porous carbon material doped with zinc and zinc cyanide.

[0008] In the above implementation process, the porous carbon material has good electronic conductivity. Using it as the negative electrode of a lithium-ion battery can increase the conductivity between the current collector and the negative electrode. And the porous carbon material has a large tolerance for the volume expansion of lithium-ion batteries, reducing the expansion probability of lithium-ion batteries and improving the long-term cycle stability and safety of the battery.

[0009] Zinc and zinc cyanide are doped in the porous carbon material. Zinc and zinc cyanide have a lithiophilic property, which can reduce the nucleation potential of lithium metal, achieve uniform deposition and stripping of lithium ions, avoid the formation and growth of lithium dendrites, and improve the cycling performance and safety performance of the lithium-ion battery. In addition, the doping of zinc and zinc cyanide in the porous material can prevent co-insertion of the solvent, further improving the Coulombic efficiency of the battery.

[0010] The negative electrode material of this lithium-ion battery can endow the lithium-ion battery with longer cycling stability and safety.

[0011] Combined with the first aspect, in the first possible implementation manner of the first aspect of this application, the porous carbon material has a hierarchical pore structure.

[0012] Combined with the first aspect, in the second possible implementation manner of the first aspect of this application, the hierarchical pore structure includes a first pore with a pore diameter of 0.5 - 50 μm and a second pore with a pore diameter of 2 - 500 nm.

[0013] In the above implementation process, the porous carbon material has a hierarchical pore structure, which includes a first pore with a pore diameter of 0.5 - 50 μm and a second pore with a pore diameter of 2 - 500 nm. It can improve the specific surface area of the porous carbon material while ensuring the structural stability of the porous carbon material and avoiding structural collapse, providing more active sites for the insertion and extraction of lithium ions, and thus improving the stability of the lithium-ion battery.

[0014] In the second aspect, an example of this application provides a preparation method for a negative electrode material of a lithium-ion battery, including:

[0015] Step 1: Dissolve zinc salt and 1H-1,2,3-triazole in a solvent and fully react to obtain a MOF material;

[0016] Step 2: Heat and activate the MOF material, and then calcine it in an inert gas atmosphere to obtain a porous carbon material doped with zinc and zinc cyanide.

[0017] In the above implementation process, a porous coordination compound with a carbon source and a metal source (metal ions) and a periodic network structure can be obtained through the reaction of zinc salt and 1H-1,2,3-triazole, so as to obtain a porous carbon material doped with zinc and zinc cyanide through a carbonization process under an inert atmosphere later. This porous carbon material has a good pore structure and conductivity. Using it as the negative electrode of a lithium-ion battery can increase the conductivity between the current collector and the negative electrode, reduce the probability of battery failure caused by the expansion of the lithium-ion battery, and improve the long-cycle stability and safety of the battery. Zinc and zinc cyanide have a lithiophilic property, which can reduce the nucleation potential of lithium metal, achieve uniform deposition and stripping of lithium ions at the porous carbon, avoid the formation and growth of lithium dendrites, and improve the cycling performance and safety performance of the lithium-ion battery.

[0018] In combination with the second aspect, in the first possible implementation manner of the second aspect of the present application, in step one, the molar ratio of 1H-1,2,3-triazole to Zn in the zinc salt is 1:(2-5). 2+ The molar ratio is 1:(2-5).

[0019] In the above implementation process, 1H-1,2,3-triazole and Zn with a molar ratio of 1:(2-5) are mixed in a solvent to form a MOF material, so as to avoid impurities formed after carbonization of the MOF material due to excessive 1H-1,2,3-triazole, or to avoid the inability to form zinc cyanide after carbonization of the MOF material due to too little 1H-1,2,3-triazole, which will reduce the beneficial effects of the obtained porous carbon material on the performance and safety of lithium-ion batteries. 2+ In the above implementation process, 1H-1,2,3-triazole and Zn with a molar ratio of 1:(2-5) are mixed in a solvent to form a MOF material, so as to avoid impurities formed after carbonization of the MOF material due to excessive 1H-1,2,3-triazole, or to avoid the inability to form zinc cyanide after carbonization of the MOF material due to too little 1H-1,2,3-triazole, which will reduce the beneficial effects of the obtained porous carbon material on the performance and safety of lithium-ion batteries.

[0020] In combination with the second aspect, in the second possible implementation manner of the second aspect of the present application, the solvent includes ethanol, water, ammonia water, and N,N-dimethylformamide;

[0021] Optionally, the volume ratio of ethanol:water:ammonia water:N,N-dimethylformamide is 10:15:4:5; the mass ratio of the zinc salt to water is 1:15.

[0022] In the above implementation process, dissolving the zinc salt and 1H-1,2,3-triazole in a solvent of ethanol, water, ammonia water, and N,N-dimethylformamide can make the zinc salt and 1H-1,2,3-triazole disperse evenly, facilitating the full reaction of the zinc salt and 1H-1,2,3-triazole to form a MOF material. And ammonia water is added to the solvent, and ammonia water can neutralize the hydrogen in 1H-1,2,3-triazole, and NH 4 + ions combine with the anions in the zinc salt to accelerate the reaction process.

[0023] Limiting the volume ratio of ethanol:water:ammonia water:N,N-dimethylformamide in the solvent to 10:15:4:5, and the mass ratio of the zinc salt to water to 1:15 can, while accelerating the reaction process, reduce the generation of side reactants and increase the beneficial effects of the porous carbon material doped with zinc and zinc cyanide on the performance and safety of lithium-ion batteries.

[0024] In combination with the second aspect, in the third possible implementation manner of the second aspect of the present application, in step two, the calcination temperature is 500-700 °C.

[0025] In combination with the second aspect, in the fourth possible implementation manner of the second aspect of the present application, the inert atmosphere is argon.

[0026] In the above implementation process, calcining the MOF material within the temperature range of 500 - 700 °C can ensure that while the MOF material is carbonized to obtain porous carbon, zinc, and zinc cyanide, it can also avoid side reactions between zinc or zinc cyanide and other chemical substances caused by incomplete carbonization at too low a temperature or excessive temperature, such as reactions with gases like nitrogen to form impurities.

[0027] Setting the inert atmosphere to argon, compared with inert gases such as nitrogen, argon has better chemical stability and can reduce the probability of impurity formation during the carbonization process.

[0028] In a third aspect, the implementation of the present application provides a lithium-ion battery, including:

[0029] A negative electrode made of the lithium-ion battery negative electrode material provided by the first aspect or the second aspect;

[0030] A current collector sheet, with the negative electrode disposed on one surface of the current collector sheet.

[0031] In the above implementation process, the negative electrode made of the lithium-ion battery negative electrode material provided by the first aspect or the second aspect is disposed on one surface of the current collector sheet. The porous carbon material has good electronic conductivity, enabling good conductivity between the current collector and the negative electrode and improving the charge and discharge performance of the lithium-ion battery. Moreover, the porous carbon material has a large tolerance for the volume expansion of the lithium-ion battery, reducing the probability of battery expansion and endowing the lithium-ion battery with good long-cycle stability and safety. The porous material doped with zinc and zinc cyanide, due to the lithium-philic characteristics of zinc and zinc cyanide, can reduce the nucleation potential of lithium metal, achieve uniform deposition and stripping of lithium ions, avoid the formation and growth of lithium dendrites, and improve the cycle performance and safety performance of the lithium-ion battery. The porous carbon material doped with zinc and zinc cyanide can also prevent the co-insertion of solvents and lithium ions, making the lithium-ion battery have a high Coulomb efficiency.

[0032] In a fourth aspect, the implementation of the present application provides a preparation method of a lithium-ion battery, including:

[0033] Mixing the lithium-ion battery negative electrode material obtained by the preparation method of the lithium-ion battery negative electrode material provided by the first aspect or the second aspect and a binder in water to obtain a first mixture;

[0034] Optionally, the weight ratio of the lithium-ion battery negative electrode material to the binder is 8:1;

[0035] Coating the first mixture on one surface of the current collector sheet and drying it under vacuum.

[0036] In the above implementation process, the porous carbon material doped with zinc and zinc cyanide provided by the first aspect or the second aspect is mixed with a binder in water to form a coating solution in which the porous carbon material and the binder are uniformly mixed, so as to coat and form a firm and uniformly distributed negative electrode material on the surface of the current collector sheet. Using water as a solvent during the dissolution process can avoid the use of organic solvents such as PVDF, which conforms to the concept of green new energy development, and at the same time reduces the harm and pollution of organic substances. Description of the Drawings

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for description in the embodiments or the prior art.

[0038] Figure 1 Flow chart for the preparation of the lithium-ion battery electrode sheet of the present application;

[0039] Figure 2 XRD diffraction pattern of the negative electrode material of the lithium-ion battery obtained in Example 1;

[0040] Figure 3 SEM image of the negative electrode material of the lithium-ion battery obtained in Example 1;

[0041] Figure 4 Pore size distribution diagram of the negative electrode material of the lithium-ion battery obtained in Example 1;

[0042] Figure 5 Coulombic efficiency vs. cycle number graph of the lithium-ion battery provided in Example 4. Detailed Embodiments

[0043] The following will describe the implementation solutions of the present application in detail in conjunction with the embodiments. However, those skilled in the art will understand that the following embodiments are only used to illustrate the present application and should not be construed as limiting the scope of the present application. For those not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. Those reagents or instruments not specified by the manufacturer can be obtained as conventional products through commercial purchase.

[0044] The following specifically describes the negative electrode material, lithium-ion battery and preparation method provided by the examples of the present application:

[0045] Lithium-ion batteries have the advantages of high energy density, high output voltage, no memory effect, no environmental pollution, etc., and have good application prospects. Traditional lithium-ion batteries generally use graphite as the negative electrode material and layered lithium cobaltate (LiCoO 2 ) or lithium iron phosphate (LiFePO 4) is used as the positive electrode material, and a non-aqueous lithium-ion conductive medium is used as the electrolyte. During charging, lithium ions are removed from the positive electrode and embedded in the negative electrode. During discharging, lithium ions escape from the negative electrode and are embedded in the positive electrode, thus forming a round-trip process of insertion and extraction between the electrode materials.

[0046] Graphite materials have a good layered structure and electrical conductivity, and their theoretical specific capacity is 372 mAh / g. However, the inventors found that although graphite materials have a relatively high theoretical specific capacity, graphite electrodes are prone to the co-insertion phenomenon of lithium ions and solvent molecules, and uneven carbon deposition is likely to lead to the growth of lithium dendrites piercing the separator, easily causing battery short circuits and consuming the electrodes, thus restricting the practical application of lithium-ion batteries. In addition, with the repeated insertion and extraction of lithium ions, the graphite structure continuously expands and contracts repeatedly, making the graphite sheets prone to shedding and resulting in a rapid attenuation of the electrode material capacity.

[0047] Based on this, the inventors provided a negative electrode material for lithium-ion batteries, providing a porous carbon material doped with zinc and zinc cyanide. Since the porous carbon material has good electronic conductivity, a large tolerance for the volume expansion of lithium-ion batteries, and zinc and zinc cyanide have a lithium-philic property, they can reduce the nucleation potential of lithium metal, achieve uniform deposition and stripping of lithium ions, and avoid the formation and growth of lithium dendrites, so as to improve the cycle performance and safety performance of lithium-ion batteries.

[0048] The following combines Figure 1 to further describe in detail the preparation method of the negative electrode material for lithium-ion batteries of this application.

[0049] S1. Dissolve a zinc salt and 1H-1,2,3-triazole in a solvent and react fully to obtain a MOF material.

[0050] Through the full reaction of the zinc salt and 1H-1,2,3-triazole, a porous coordination compound with a carbon source and a metal source (metal ions) and a periodic network structure can be obtained.

[0051] This application does not limit the specific type of zinc source. Relevant personnel can make corresponding selections according to needs on the premise of ensuring that Zn 2+ can react fully with 1H-1,2,3-triazole to form a MOF material.

[0052] In a possible implementation manner, the zinc salt is selected as ZnF 2 , ZnCl 2 , ZnBr 2 , ZnI 2 , Zn(NO 3 ) 2 , Zn(NO 3 ) 2 ·6H 2 O and Zn(OAc)2 · 6H 2 One or more of O. Exemplarily, ZnCl 2 is mixed with 1H-1,2,3-triazole in a solvent.

[0053] This application does not limit the addition ratio of zinc salt and 1H-1,2,3-triazole, and relevant personnel can make corresponding selections according to needs.

[0054] In a possible implementation, the molar ratio of 1H-1,2,3-triazole to Zn in the zinc salt 2+ is 1:(2 - 5).

[0055] Mix 1H-1,2,3-triazole with Zn in a molar ratio of 1:(2 - 5) 2+ in a solvent to form a MOF material, so as to avoid excessive 1H-1,2,3-triazole leading to impurities formed after carbonization of the MOF material, or to avoid too little 1H-1,2,3-triazole resulting in the inability to form zinc cyanide after carbonization of the MOF material, which will reduce the beneficial effects of the obtained porous carbon material on the performance and safety of lithium-ion batteries.

[0056] Exemplarily, the molar ratio of 1H-1,2,3-triazole to Zn in the zinc salt 2+ includes but is not limited to one of 1:2, 1:2.5, 1:3, 1:4, and 1:5 or the range between any two of them.

[0057] This application does not limit the specific type of solvent. Relevant personnel can make corresponding selections according to needs on the premise that the zinc salt and 1H-1,2,3-triazole can be uniformly dispersed to react to obtain a MOF material.

[0058] In a possible implementation, the solvent includes ethanol, water, ammonia water, and N,N-dimethylformamide.

[0059] Dissolving the zinc salt and 1H-1,2,3-triazole in a solvent of ethanol, water, ammonia water, and N,N-dimethylformamide can make the zinc salt and 1H-1,2,3-triazole disperse evenly, facilitating the full reaction of the zinc salt and 1H-1,2,3-triazole to form a MOF material. And ammonia water is added to the solvent, and ammonia water can neutralize H in 1H-1,2,3-triazole, and NH 4 + ions combine with the anions in the zinc salt to accelerate the reaction process.

[0060] This application does not limit the addition ratio of ethanol, water, ammonia water, and N,N-dimethylformamide in the solvent. In a possible implementation, the volume ratio of ethanol:water:ammonia water:N,N-dimethylformamide is 10:15:4:5, and the mass ratio of the zinc salt to water is 1:15.

[0061] Adding zinc salts in a suitable proportion to the solvent can accelerate the reaction process while ensuring uniform dispersion, reduce the generation of side reactants, and enhance the beneficial effects of zinc and zinc cyanide-doped porous carbon materials on the performance and safety of lithium-ion batteries.

[0062] Alternatively, in a possible implementation, the solvent includes any one or more of ethanol, water, and N, N-dimethylformamide. For example, the solvent includes ethanol and water, or the solvent includes ethanol and N, N-dimethylformamide.

[0063] This application does not limit the specific reaction conditions of zinc salts and 1H-1,2,3-triazole. In a possible implementation, to accelerate the reaction rate and promote the full reaction of reactants, the mixed solution of zinc salts and 1H-1,2,3-triazole in the solvent can be placed at room temperature and allowed to stand, and then centrifugally stirred at a speed of 8000 rpm for 5-10 minutes to obtain a centrifuged precipitate. Alternatively, the mixed solution can be allowed to stand at room temperature for more than 20 hours, and the reaction solution can be filtered to obtain a precipitate.

[0064] In a possible implementation, the precipitate obtained after the standing reaction can be washed to remove impurities such as the solvent attached to the reactants. Ethanol can be used as the cleaning agent for washing the precipitate.

[0065] S2. Heat and activate the MOF material, and then calcine it in an inert gas atmosphere to obtain a porous carbon material doped with zinc and zinc cyanide.

[0066] Heating and activating the MOF material obtained in S1 can remove volatile solvents or impurities to a certain extent, obtain a dry MOF material, and enhance the activity of the MOF material. Then, carbonization is carried out to obtain a high-performance anode material for lithium-ion batteries with zinc and zinc cyanide deposited on the porous carbon material.

[0067] This application does not limit the specific conditions for heat activation. In a possible implementation, the solid precipitate (MOF material) obtained in S1 is placed in a drying oven for drying. To avoid side reactions during the drying process, drying can be carried out in a vacuum drying oven. The drying temperature should not be too high, and it can be dried at 80°C for 6-15 hours. Alternatively, drying can be directly carried out in a tube furnace so that carbonization treatment can be further carried out using the tube furnace after drying is completed.

[0068] This application does not limit the specific calcination conditions. Relevant personnel can make corresponding adjustments on the premise of ensuring that the MOF material can be carbonized to obtain a porous carbon material doped with zinc and zinc cyanide.

[0069] In a possible implementation, the MOF material obtained in S1 can be placed in the furnace tube of a tube furnace, and then the tube furnace is sealed. The tube furnace is purged to ensure that the atmosphere condition in the tube furnace is an inert gas. Then, the MOF material in the furnace tube is heated to the carbonization temperature at a certain heating rate for carbonization.

[0070] In a possible implementation, the MOF material is heated to 500 - 700 °C at a heating rate of 5 - 10 °C / min and held for 1 - 3 h.

[0071] Exemplarily, the calcination temperature includes but is not limited to one of 500 °C, 600 °C, 650 °C, and 700 °C or the range between any two of them.

[0072] This application does not limit the specific type of the inert atmosphere during the carbonization process. In a possible implementation, the inert atmosphere includes but is not limited to one or more of helium, neon, argon, krypton, xenon, and radon. Preferably, the MOF material is carbonized and calcined under an argon atmosphere.

[0073] An example of this application provides a lithium-ion battery, including a current collector sheet and a negative electrode provided on one surface of the current collector sheet. Among them, the negative electrode is made of a lithium-ion battery negative electrode material of porous carbon material doped with zinc and zinc cyanide.

[0074] This application does not limit the specific material of the current collector sheet. In a possible implementation, the current collector sheet can be selected from metal conductor materials such as copper, aluminum, nickel, and stainless steel, or semiconductor materials such as carbon, as well as composite materials. Exemplarily, a negative electrode can be provided on one surface of a copper current collector sheet.

[0075] This application does not limit the type of the lithium-ion battery. In a possible implementation, the lithium-ion battery further includes a positive current collector, a positive electrode, and a solid / liquid electrolyte. The type of the positive current collector can be the same as the above-mentioned current collector sheet. The positive electrode can be selected from lithium nickelate, lithium cobaltate, lithium titanate, or lithium iron phosphate, etc.

[0076] The following continues to combine Figure 1 to further describe in detail the preparation method of the lithium-ion battery provided in this example.

[0077] S3. The lithium-ion battery negative electrode material and the binder are mixed in water to obtain a first mixture.

[0078] The lithium-ion battery negative electrode material and the binder are mixed in water to facilitate uniformly coating the lithium battery negative electrode material on the current collector sheet and forming a stable negative electrode on the current collector sheet. And conductive carbon black is not used, thereby reducing the production cost of the lithium-ion battery and saving resources, providing a good prospect for the industrialization of the lithium-ion battery.

[0079] In addition, using water as a solvent conforms to the concept of green new energy development and reduces the harm and pollution of organic substances in the production process of lithium-ion batteries.

[0080] The present application does not limit the specific selection of the binder. In a possible implementation, the binder can be sodium polyacrylate.

[0081] The present application does not limit the content ratio of the anode material of the lithium-ion battery to the binder. In a possible implementation, sodium polyacrylate with a weight ratio of 1:8 to the anode material of the lithium-ion battery is mixed in water.

[0082] The present application does not limit the water content. Relevant personnel make corresponding selections under the condition of facilitating the coating of the coating liquid and the dispersion of the anode material of the lithium-ion battery and the binder.

[0083] S4. Coating the first mixture on one surface of the current collector sheet and drying it under vacuum.

[0084] After coating the first mixture on one surface of the current collector sheet, it is dried under vacuum so that the anode material is uniformly attached to the surface of the current collector sheet, obtaining an electrode sheet.

[0085] The present application does not limit how to coat the first mixture on one surface of the current collector sheet. In a possible implementation, the coating methods can include rotary spraying, gravure coating, dip coating, etc.

[0086] In a possible implementation, a commercial coater is used to coat the first mixture on a copper current collector sheet with a coating blade having a thickness of 1000 μm, vacuum-drying it at a temperature of 80°C for 12 h, rolling and slicing it to obtain an electrode sheet.

[0087] The following further describes in detail the anode material of the lithium-ion battery and the lithium-ion battery of the present application in conjunction with embodiments.

[0088] Example 1

[0089] Example 1 of the present application provides an anode material for a lithium-ion battery, which is obtained by the following preparation method:

[0090] (1) Mix ethanol, water, ammonia water, and N,N-dimethylformamide according to a volume ratio of 10:15:4:5 and stir evenly.

[0091] (2) Add ZnCl 2 to the mixed solution obtained in step (1), stir and mix to obtain a second mixed solution. The mass ratio of ZnCl 2 to the water in step (1) is 1:15.

[0092] (3) Add 1H-1,2,3-triazole dropwise to the mixed solution obtained in step (2), and stir to mix. Among them, the molar ratio of 1H-1,2,3-triazole to Zn in ZnCl added in step (2) is 1:2. 2 Zn in 2+ has a molar ratio of 1:2.

[0093] (4) Place the mixed solution obtained in step (3) at room temperature and stir for 20 h. Then centrifuge at a speed of 8000 rpm for 5 min to obtain a precipitate. Wash the precipitate with ethanol to obtain the MOF material.

[0094] (5) Place the MOF material obtained in step (4) in an oven and dry it at 80 °C for 10 h. Then place the dried and activated MOF material in the furnace tube of a tubular furnace, adjust the atmosphere in the furnace tube to argon, heat it at a heating rate of 5 °C / min to 500 °C, hold for 3 h, and cool naturally.

[0095] Figure 2 is the XRD diffraction pattern of the anode material for the lithium-ion battery obtained in Example 1. Figure 3 is the SEM image of the anode material for the lithium-ion battery obtained in Example 1. Figure 4 is the pore size distribution diagram. It can be seen from Figure 2 that the anode material for the lithium-ion battery provided in this example contains zinc and zinc cyanide. It can be seen from Figure 3 that the anode material for the lithium-ion battery provided in Example 1 of this application has a hierarchical pore structure, including a first pore with a pore size of 0.5 - 50 μm and a second pore with a pore size of 2 - 500 nm (the first pore and the second pore do not refer to the number of pores, but to the pore size types of the pores). It can be seen from Figure 4 that in the porous carbon material, the second pores (2 - 500 nm) are dominant.

[0096] Example 2

[0097] The anode material for the lithium-ion battery provided in Example 2 of this application is different from that in Example 1 in that in step (3), the molar ratio of 1H-1,2,3-triazole to Zn in ZnCl added in step (2) is 1:5. 2 Zn in 2+ has a molar ratio of 1:5.

[0098] Example 3

[0099] The anode material for the lithium-ion battery provided in Example 3 of this application is different from that in Example 2 in that in step (5), heat it at a heating rate of 5 °C / min to 700 °C, hold for 3 h, and cool naturally.

[0100] Example 4

[0101] Example 4 of this application provides a lithium-ion battery (half-cell structure), which is obtained by the following method:

[0102] a Mix sodium polyacrylate and the lithium-ion battery anode material obtained in Example 1 in water at a mass ratio of 1:8 to prepare a coating solution.

[0103] b Use a coater to coat the coating solution obtained in step a on a copper current collector sheet, dry it in a vacuum environment at a temperature of 80 °C for 12 h, and then prepare an electrode sheet with a diameter of 12 mm.

[0104] c Inside the glove box (O 2 <0.01 ppm, H 2 O <0.01 ppm), assemble the electrode sheet provided in step b and a lithium metal sheet with a diameter of 12 mm (half-cell structure) to obtain a lithium-ion battery.

[0105] Experimental Example 1

[0106] Perform a cyclic performance test on the lithium-ion battery provided in Example 4 under the conditions of a voltage range of -0.01 to 1 V and a current density of 1 mA cm -2 The test results are as Figure 5 shown.

[0107] From Figure 5 It can be seen that the Coulomb efficiency of the lithium-ion battery provided in Example 4 is greater than 99% after 450 cycles, which is better than the cyclic performance of the porous carbon anode material in the prior art (in the lithium-ion battery constructed with the porous carbon anode material obtained by carbonizing the Zn-MOF material in the prior art, the Coulomb efficiency after 100 stable cycles is lower than 90%). And compared with the anode made of the existing graphite material, the anode of the existing graphite material can only stably cycle about 80 times (see the technical document "Single-Atom Reversible Lithiophilic Sites toward StableLithium Anodes", AdvancedEnergy Materials, 2022: 2103368), which is lower than the number of stable cycles of the anode prepared from the porous carbon material doped with zinc and zinc cyanide provided in Example 4.

[0108] The above are only the preferred embodiments of this application and are not used to limit this application. For those skilled in the art, this application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this application shall be included in the protection scope of this application.

Claims

1. A preparation method of a negative electrode material for a lithium-ion battery, characterized in that, comprising: Step 1: Dissolve a zinc salt and 1H-1,2,3-triazole in a solvent and fully react to obtain a MOF material; the molar ratio of the 1H-1,2,3-triazole to Zn in the zinc salt is 1:(2-5); the solvent includes ethanol, water, ammonia water, and N,N-dimethylformamide; 2+ ​ Step 2: Heat and activate the MOF material, and then calcine it in an inert gas atmosphere to obtain a porous carbon material doped with zinc and zinc cyanide; the temperature of the calcination is 500-700 °C.

2. The preparation method of the negative electrode material for a lithium-ion battery according to claim 1, characterized in that, the volume ratio of the ethanol: the water: the ammonia water: the N, N-dimethylformamide is 10:15:4:5; the mass ratio of the zinc salt and the water is 1:

15.

3. The preparation method of the negative electrode material for a lithium-ion battery according to claim 1, characterized in that, the inert atmosphere is argon.

4. A negative electrode material for a lithium-ion battery, characterized in that, it is prepared by the preparation method according to any one of claims 1 to 3; the negative electrode material for a lithium-ion battery comprises a porous carbon material, and the porous carbon material is doped with zinc and zinc cyanide.

5. The negative electrode material for a lithium-ion battery according to claim 4, characterized in that, the porous carbon material has a hierarchical pore structure.

6. The negative electrode material for a lithium-ion battery according to claim 5, characterized in that, the hierarchical pore structure comprises a first pore with a pore diameter of 0.5-50 μm and a second pore with a pore diameter of 2-500 nm.

7. A lithium-ion battery, characterized in that, comprising: a negative electrode, which is made of the negative electrode material for a lithium-ion battery obtained by the preparation method of the negative electrode material for a lithium-ion battery provided in any one of claims 1 to 3; a current collector sheet, and the negative electrode is disposed on one surface of the current collector sheet.

8. A preparation method of a lithium-ion battery, characterized in that, comprising: Mix the negative electrode material for a lithium-ion battery obtained by the preparation method of the negative electrode material for a lithium-ion battery provided in any one of claims 1 to 3 and a binder in water to obtain a first mixture; Coat the first mixture on one surface of the current collector sheet and vacuum dry it.

9. The preparation method of the lithium-ion battery according to claim 8, characterized in that, the weight ratio of the negative electrode material for a lithium-ion battery and the binder is 8:1.

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