Preparation method of lithium battery negative electrode, lithium battery

Abstract

This application relates to a method for preparing a lithium battery negative electrode and a lithium battery, relating to the field of new energy. The method includes the following steps: coaxial electrospinning of a core solution and a shell solution to obtain a fiber membrane; carbonizing the fiber membrane to obtain a carbon fiber membrane; heat-treating the carbon fiber membrane in an ammonia atmosphere to obtain a current collector; preparing lithium metal on the surface of the current collector to obtain a pre-formed negative electrode; and pressing the pre-formed negative electrode to obtain a lithium battery negative electrode. The fiber membrane has a core structure and a shell structure, with the shell structure covering the core structure. The core solution is used to form the core structure, and the shell solution is used to form the shell structure. The core solution includes a carbonizable first polymer, and the shell solution includes a salt substance and a carbonizable second polymer. The metal element of the salt substance is at least one selected from chromium, nickel, cobalt, manganese, iron, copper, molybdenum, and zinc. This application readily yields a very thin lithium battery negative electrode.

Description

Technical Field

[0001] This application relates to the field of new energy, and in particular to lithium batteries. Background Technology

[0002] Traditional lithium-ion battery anode materials are graphite, but due to its low specific capacity, the energy density of lithium-ion batteries has reached a bottleneck. Lithium metal, with its high specific capacity and low electrode potential, is considered the most promising anode material for next-generation high-energy-density battery systems. However, currently available commercial lithium foils are usually very thick (the thinnest being about 50 μm), resulting in a serious oversupply of lithium. This not only means an imbalance in the capacity ratio between anode and cathode materials, but also that the utilization rate of lithium is quite low, which is a waste of lithium resources. Summary of the Invention

[0003] This application provides a method for preparing a lithium battery anode and a lithium battery, in order to solve the technical problem that the thickness of lithium metal anode materials is not thin enough.

[0004] In a first aspect, embodiments of this application provide a method for preparing a lithium battery negative electrode, the method comprising the following steps:

[0005] A fiber membrane was obtained by coaxial electrospinning using a core solution and a shell solution.

[0006] The fiber membrane is subjected to carbonization treatment to obtain a carbon fiber membrane;

[0007] The carbon fiber membrane is heat-treated in an ammonia atmosphere to obtain a current collector;

[0008] Lithium metal is prepared on the surface of the current collector to obtain a pre-fabricated negative electrode;

[0009] The pre-fabricated negative electrode is pressed to obtain the lithium battery negative electrode.

[0010] The fiber membrane has a core structure and a shell structure, the shell structure covering the core structure. The core solution is used to form the core structure during the coaxial electrospinning process, and the shell solution is used to form the shell structure during the coaxial electrospinning process. The core solution includes a carbonizable first polymer, and the shell solution includes a salt substance and a carbonizable second polymer. The metal element of the salt substance is at least one selected from chromium, nickel, cobalt, manganese, iron, copper, molybdenum, and zinc.

[0011] In some embodiments of this application, the first polymer is at least one selected from polyacrylonitrile, polyvinylpyrrolidone, polyvinylidene fluoride, polycaprolactone, polyurethane, silk fibroin, polyamide, polyvinyl alcohol, polymethyl methacrylate, and bitumen; and / or,

[0012] The solvent of the core solution is at least one selected from water, ethanol, N,N-dimethylformamide, acetone, N,N-diethylacetamide, formic acid, tetrahydrofuran, isopropanol, and hexafluoroisopropanol; and / or,

[0013] In the core solution, the mass ratio of the first polymer to the solvent of the core solution is 1:5 to 12.

[0014] In some embodiments of this application, the second polymer is at least one selected from polyacrylonitrile, polyvinylpyrrolidone, polyvinylidene fluoride, polycaprolactone, polyurethane, silk fibroin, polyamide, polyvinyl alcohol, polymethyl methacrylate, and bitumen; and / or,

[0015] The solvent for the shell solution is at least one selected from water, ethanol, N,N dimethylformamide, acetone, N,N diethylacetamide, formic acid, tetrahydrofuran, isopropanol, and hexafluoroisopropanol; and / or,

[0016] In the shell solution, the mass ratio of the second polymer to the salt is 1:0.8–1.2; and / or,

[0017] In the shell solution, the mass ratio of the second polymer to the solvent of the shell solution is 1:4 to 6.

[0018] In some embodiments of this application, the coaxial electrospinning is performed through at least one coaxial spinneret, and the process parameters of the coaxial electrospinning, averaged across each coaxial spinneret, satisfy the following conditions:

[0019] The voltage is 12–20 kV;

[0020] The spinning solution flow rate is 0.6–1.5 mL / h;

[0021] The receiving distance is 12-20cm;

[0022] The duration is 1.8 to 2.2 hours.

[0023] In some embodiments of this application, the carbonization treatment temperature is 700–900°C; and / or,

[0024] The carbonization treatment time is 1 to 3 hours; and / or,

[0025] The carbonization process is carried out in an inert atmosphere.

[0026] In some embodiments of this application, prior to the carbonization treatment of the fiber membrane, the method further includes the following steps:

[0027] The fiber membrane is subjected to pre-oxidation treatment.

[0028] In some embodiments of this application, the temperature of the pre-oxidation treatment is 200–300°C; and / or,

[0029] The pre-oxidation treatment time is 0.5–1 hour; and / or,

[0030] The pre-oxidation treatment is carried out in an oxygen-containing atmosphere.

[0031] In some embodiments of this application, the heat treatment temperature is 400–700°C; and / or,

[0032] The heat treatment time is 1 to 3 hours.

[0033] In some embodiments of this application, the preparation of lithium metal on the surface of the current collector includes the following steps:

[0034] The current collector is immersed in molten lithium metal in an inert atmosphere.

[0035] Secondly, embodiments of this application provide a lithium battery, the lithium battery comprising a lithium battery negative electrode prepared by the method described in any embodiment of the first aspect.

[0036] The technical solutions provided in this application have the following advantages compared with the prior art:

[0037] The method for preparing a lithium battery negative electrode provided in this application involves preparing a fiber membrane with a shell structure loaded with a large number of metal ions through coaxial electrospinning. The fiber membrane is then subjected to carbonization and heat treatment in ammonia to form a current collector with a metal nitride surface. Lithium metal is then prepared on the surface of the current collector to obtain a pre-formed negative electrode. Due to the large gaps between the fibers of the current collector, the pre-formed negative electrode is highly compressible, and a very thin lithium battery negative electrode can be easily obtained through pressing. Furthermore, the current collector described in this application has a good affinity for lithium metal, which can effectively guide the orderly deposition and stripping of lithium metal during charging and discharging, suppress the growth of lithium dendrites and the volume expansion during lithium deposition and desorption, thereby effectively improving the coulombic efficiency and cycle life of the lithium metal negative electrode. Attached Figure Description

[0038] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0039] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a schematic flowchart illustrating a method for preparing a lithium battery negative electrode according to an embodiment of this application. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0042] Unless otherwise specified, the terminology used herein should be understood as having the meaning commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. In case of any conflict, this specification shall prevail.

[0043] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0044] Currently, lithium metal anode materials suffer from the technical problem of insufficient thickness.

[0045] The technical solution provided in this application is to solve the above-mentioned technical problems, and the general idea is as follows:

[0046] In a first aspect, embodiments of this application provide a method for preparing a lithium battery negative electrode, the method comprising the following steps:

[0047] S1: Coaxial electrospinning is performed using the core solution and the shell solution to obtain a fiber membrane;

[0048] S2: The fiber membrane is subjected to carbonization treatment to obtain a carbon fiber membrane;

[0049] S3: The carbon fiber membrane is heat-treated in an ammonia atmosphere to obtain a current collector;

[0050] S4: Prepare lithium metal on the surface of the current collector to obtain a pre-fabricated negative electrode;

[0051] S5: The pre-fabricated negative electrode is pressed to obtain the lithium battery negative electrode.

[0052] The fiber membrane has a core structure and a shell structure, the shell structure covering the core structure. The core solution is used to form the core structure during the coaxial electrospinning process, and the shell solution is used to form the shell structure during the coaxial electrospinning process. The core solution includes a carbonizable first polymer, and the shell solution includes a salt substance and a carbonizable second polymer. The metal element of the salt substance is at least one selected from chromium, nickel, cobalt, manganese, iron, copper, molybdenum, and zinc.

[0053] As is easily understood, coaxial electrospinning is performed using a coaxial spinneret, which comprises two capillaries with different inner diameters but coaxial alignment. The basic principle of coaxial electrospinning is to inject a core solution and a shell solution into the smaller-diameter capillary and a larger-diameter capillary, respectively. These solutions converge at the end of the coaxial spinneret and solidify under the influence of an electric field to form nanofibers with core and shell structures. The shell structure encapsulates the core structure, and both the core and shell structures are formed by the core solution.

[0054] It is easy to understand that electrospun fabrics typically have large gaps between their fibers and possess a large specific surface area. The carbon fiber membrane described in this application is made by heat-treating the fiber membrane, which is an electrospun fabric. This gives the current collector the structural characteristics of an electrospun fabric as well. Because the current collector has a large specific surface area, its surface can be loaded with a large amount of lithium metal. The large gaps between the fibers of the current collector can also accommodate lithium dendrites, thus minimizing the damage to the lithium battery's function caused by lithium dendrites. Furthermore, the current collector serves as the prefabricated skeleton, and the large gaps between its fibers make the prefabricated negative electrode highly compressible, allowing for the easy acquisition of very thin lithium battery negative electrodes through pressing.

[0055] It is readily understood that the shell structure contains metal ions contained in the salt material. Heat treatment of the carbon fiber film in an ammonia atmosphere allows these metal ions to form nitrides. These metal nitrides are beneficial for inducing lithium metal nuclei and exhibit excellent affinity for lithium metal. This effectively guides the orderly deposition and stripping of lithium metal during charge and discharge processes, suppresses the growth of lithium dendrites and volume expansion during lithium deposition and desorption, thereby effectively improving the coulombic efficiency and cycle life of the lithium metal anode.

[0056] This application prepares a fiber membrane with a shell structure loaded with a large number of metal ions through coaxial electrospinning. The fiber membrane is then subjected to carbonization and heat treatment in ammonia to form a current collector with a metal nitride surface. Lithium metal is then prepared on the surface of the current collector to obtain a pre-fabricated negative electrode. Due to the large gaps between the fibers of the current collector, the pre-fabricated negative electrode is highly compressible, and a very thin lithium battery negative electrode can be easily obtained through pressing. Furthermore, the current collector described in this application has a good affinity for lithium metal, which can effectively guide the orderly deposition and stripping of lithium metal during charging and discharging, suppress the growth of lithium dendrites and the volume expansion during lithium deposition and desorption, thereby effectively improving the coulombic efficiency and cycle life of the lithium metal negative electrode.

[0057] In some embodiments of this application, the first polymer is at least one selected from polyacrylonitrile, polyvinylpyrrolidone, polyvinylidene fluoride, polycaprolactone, polyurethane, silk fibroin, polyamide, polyvinyl alcohol, polymethyl methacrylate, and bitumen; and / or,

[0058] The solvent of the core solution is at least one selected from water, ethanol, N,N-dimethylformamide, acetone, N,N-diethylacetamide, formic acid, tetrahydrofuran, isopropanol, and hexafluoroisopropanol; and / or,

[0059] In the core solution, the mass ratio of the first polymer to the solvent of the core solution is 1:5 to 12.

[0060] It is easy to understand that when the above-mentioned polymer materials are used as the first polymer, they are all suitable for electrospinning processes and are raw materials with good electrospinning effects. In addition, the above-mentioned polymers are easy to carbonize through heat treatment to form carbon fibers.

[0061] It is easy to understand that the beneficial effect of having a mass ratio of 1:5 to 12 between the first polymer and the solvent in the core solution is that it ensures that the fibers formed by coaxial electrospinning can be well shaped, while also ensuring that the first polymer can be fully dispersed in the core solution.

[0062] As an example, the mass ratio of the first polymer to the solvent of the core solution can be 1:5, 1:7, 1:9, 1:10, or 1:12.

[0063] In some embodiments of this application, the second polymer is at least one selected from polyacrylonitrile, polyvinylpyrrolidone, polyvinylidene fluoride, polycaprolactone, polyurethane, silk fibroin, polyamide, polyvinyl alcohol, polymethyl methacrylate, and bitumen; and / or,

[0064] The solvent for the shell solution is at least one selected from water, ethanol, N,N dimethylformamide, acetone, N,N diethylacetamide, formic acid, tetrahydrofuran, isopropanol, and hexafluoroisopropanol; and / or,

[0065] In the shell solution, the mass ratio of the second polymer to the salt is 1:0.8–1.2; and / or,

[0066] In the shell solution, the mass ratio of the second polymer to the solvent of the shell solution is 1:4 to 6.

[0067] It is easy to understand that when the above-mentioned polymer materials are used as the second polymer, they are all suitable for electrospinning processes and are raw materials with good electrospinning effects. In addition, the above-mentioned polymers are easy to carbonize through heat treatment to form carbon fibers.

[0068] It is easy to understand that the beneficial effect of a mass ratio of the second polymer to the salt substance of 1:0.8 to 1.2 is that it allows the shell structure to contain a large number of metal ions without affecting the formation of the shell structure. Furthermore, the beneficial effect of a mass ratio of the second polymer to the solvent of the shell solution of 1:4 to 6 is that it ensures both good fiber formation by coaxial electrospinning and good dispersion of the salt substance in the shell solution.

[0069] As an example, the mass ratio of the second polymer to the salt substance can be 1:0.8, 1:0.9, 1:1, 1:1.1, or 1:1.2.

[0070] As an example, the mass ratio of the second polymer to the solvent in the shell solution can be 1:4, 1:4.5, 1:5, 1:5.5, or 1:6.

[0071] In some embodiments of this application, the coaxial electrospinning is performed through at least one coaxial spinneret, and the process parameters of the coaxial electrospinning, averaged across each coaxial spinneret, satisfy the following conditions:

[0072] The voltage is 12–20 kV;

[0073] The total infusion rate of the core solution and the shell solution is 0.6–1.5 mL / h;

[0074] The ratio of the infusion rates of the core solution and the shell solution is 1:1;

[0075] The receiving distance is 12-20cm;

[0076] The duration is 1.8 to 2.2 hours.

[0077] It is easy to understand that the beneficial effect of a voltage of 12–20 kV is that it allows the fibers produced by coaxial electrospinning to have a smaller diameter while ensuring fiber formation. The beneficial effect of a total feed rate of 0.6–1.5 mL / h for the core solution and the shell solution is to ensure the efficiency of coaxial electrospinning and fiber formation.

[0078] As is easily understood, the receiving distance is the distance from the liquid outlet end of the coaxial spinneret to the fiber receiving device. The beneficial effects of a receiving distance of 12–20 cm are: ensuring sufficient electric field strength during coaxial electrospinning; simultaneously ensuring appropriate displacement distances for the core and shell solutions to reach the fiber receiving device, thus enabling the fiber receiving device to collect fibers smoothly; and also allowing the solvent to fully evaporate during the movement of the core and shell solutions.

[0079] As an example, the voltage can be 12kV, 14kV, 16kV, 18kV, or 20kV.

[0080] As an example, the total infusion rate can be 0.6 mL / h, 0.8 mL / h, 1 mL / h, 1.3 mL / h, or 1.5 mL / h;

[0081] As an example, the receiving distance can be 12cm, 14cm, 16cm, 18cm, or 20cm.

[0082] In some embodiments of this application, the carbonization treatment temperature is 700–900°C; and / or,

[0083] The carbonization treatment time is 1 to 3 hours; and / or,

[0084] The carbonization process is carried out in an inert atmosphere.

[0085] It is easy to understand that the beneficial effect of the carbonization treatment temperature of 700-900℃ is to save energy as much as possible while ensuring the carbonization effect.

[0086] It is easy to understand that the beneficial effect of the carbonization process being 1 to 3 hours is to save energy as much as possible while ensuring the carbonization effect.

[0087] As an example, the carbonization temperature can be 700°C, 750°C, 800°C, 850°C, or 900°C.

[0088] As an example, the carbonization treatment time can be 1h, 1.5h, 2h, 2.5h, or 3h.

[0089] In some embodiments of this application, prior to the carbonization treatment of the fiber membrane, the method further includes the following steps:

[0090] S20: The fiber membrane is pre-oxidized.

[0091] It is easy to understand that pre-oxidizing the fiber membrane can introduce oxygen-containing groups into the fiber membrane, so that sufficient oxygen atoms can participate in the subsequent carbonization process, thereby making the carbonization process more complete and thorough.

[0092] In some embodiments of this application, the temperature of the pre-oxidation treatment is 200–300°C; and / or,

[0093] The pre-oxidation treatment time is 0.5–1 hour; and / or,

[0094] The pre-oxidation treatment is carried out in an oxygen-containing atmosphere.

[0095] It is easy to understand that the beneficial effect of the pre-oxidation treatment temperature of 200-300°C is that it can effectively introduce oxygen-containing groups into the fiber membrane without destroying the structure of the fibers in the fiber membrane.

[0096] It is easy to understand that the beneficial effect of the pre-oxidation treatment time of 0.5 to 1 hour is that it can effectively introduce oxygen-containing groups into the fiber membrane without destroying the structure of the fibers in the fiber membrane.

[0097] In some embodiments of this application, the heat treatment temperature is 400–700°C; and / or,

[0098] The heat treatment time is 1 to 3 hours.

[0099] It is easy to understand that the beneficial effect of the heat treatment temperature of 400-700℃ is that it can both maximize the reaction between metal ions and ammonia gas and save energy as much as possible.

[0100] It is easy to understand that the beneficial effect of the heat treatment time of 1 to 3 hours is that it allows the reaction between metal ions and ammonia to proceed as fully as possible while saving energy as much as possible.

[0101] As an example, the temperature of the heat treatment can be 400℃, 500℃, 600℃, or 700℃.

[0102] As an example, the heat treatment time can be 1h, 1.5h, 2h, 2.5h, or 3h.

[0103] In some embodiments of this application, the preparation of lithium metal on the surface of the current collector includes the following steps:

[0104] S41: Immerse the current collector in molten lithium metal in an inert atmosphere.

[0105] It is easy to understand that the beneficial effect of preparing lithium metal on the surface of the current collector by immersing molten lithium metal is that the molten lithium metal can penetrate into the surface layer of the fibers of the current collector, thereby bonding more firmly with the current collector. Moreover, the temperature and inert atmosphere conditions required for immersing molten lithium metal are easy to provide, and the equipment requirements are not high.

[0106] Secondly, embodiments of this application provide a lithium battery, the lithium battery comprising a lithium battery negative electrode prepared by the method described in any embodiment of the first aspect.

[0107] The lithium battery is based on the lithium battery negative electrode described in any embodiment of the first aspect. The specific implementation of the lithium battery can be referred to the above embodiments and common knowledge in the art. Since the lithium battery adopts some or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be described in detail here.

[0108] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to industry standards. If there is no corresponding industry standard, then common international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0109] Example 1

[0110] This embodiment provides a method for preparing a lithium battery negative electrode, the method comprising the following steps:

[0111] A fiber membrane was obtained by coaxial electrospinning using a core solution and a shell solution.

[0112] The fiber membrane is subjected to pre-oxidation and carbonization treatments in sequence to obtain a carbon fiber membrane;

[0113] The carbon fiber membrane is heat-treated in an ammonia atmosphere to obtain a current collector;

[0114] In a nitrogen atmosphere, the current collector is immersed in molten lithium metal for 5 minutes to prepare lithium metal on the surface of the current collector, thereby obtaining a pre-fabricated negative electrode;

[0115] The pre-fabricated negative electrode is pressed to obtain the lithium battery negative electrode.

[0116] The fiber membrane has a core structure and a shell structure, the shell structure covering the core structure. The core solution is used to form the core structure during the coaxial electrospinning process, and the shell solution is used to form the shell structure during the coaxial electrospinning process. The core solution includes a carbonizable first polymer, and the shell solution includes a salt substance and a carbonizable second polymer. The metal element of the salt substance is at least one selected from chromium, nickel, cobalt, manganese, iron, copper, molybdenum, and zinc.

[0117] In some embodiments of this application, the first polymer is polyacrylonitrile, the solvent of the core solution is tetrahydrofuran, and the mass ratio of the first polymer to the solvent of the core solution is 1:5.

[0118] In some embodiments of this application, the second polymer is polyacrylonitrile, the solvent of the shell solution is tetrahydrofuran, the mass ratio of the second polymer to the salt substance in the shell solution is 1:0.8, and the mass ratio of the second polymer to the solvent of the shell solution in the shell solution is 1:4.

[0119] In some embodiments of this application, the carbonization treatment is carried out at a temperature of 700°C for 3 hours, and the carbonization treatment is performed in a nitrogen atmosphere.

[0120] In some embodiments of this application, the temperature of the pre-oxidation treatment is 200°C, the time of the pre-oxidation treatment is 1 hour, and the pre-oxidation treatment is carried out in air.

[0121] In some embodiments of this application, the heat treatment temperature is 400°C and the heat treatment time is 3 hours.

[0122] In some embodiments of this application, the coaxial electrospinning is performed using a single coaxial spinneret, and the process parameters of the coaxial electrospinning satisfy the following conditions:

[0123] The voltage is 12kV;

[0124] The spinning solution flow rate is 0.6 mL / h;

[0125] The receiving distance is 12cm;

[0126] The duration of the coaxial electrospinning is 2 hours.

[0127] In this embodiment, the negative electrode of the lithium battery is in the form of a foil, and the thickness of the negative electrode of the lithium battery is 10 μm.

[0128] Example 2

[0129] This embodiment provides a method for preparing a lithium battery negative electrode, the method comprising the following steps:

[0130] A fiber membrane was obtained by coaxial electrospinning using a core solution and a shell solution.

[0131] The fiber membrane is subjected to pre-oxidation and carbonization treatments in sequence to obtain a carbon fiber membrane;

[0132] The carbon fiber membrane is heat-treated in an ammonia atmosphere to obtain a current collector;

[0133] In a nitrogen atmosphere, the current collector is immersed in molten lithium metal for 5 minutes to prepare lithium metal on the surface of the current collector, thereby obtaining a pre-fabricated negative electrode;

[0134] The pre-fabricated negative electrode is subjected to roll forming to obtain the lithium battery negative electrode.

[0135] The fiber membrane has a core structure and a shell structure, the shell structure covering the core structure. The core solution is used to form the core structure during the coaxial electrospinning process, and the shell solution is used to form the shell structure during the coaxial electrospinning process. The core solution includes a carbonizable first polymer, and the shell solution includes a salt substance and a carbonizable second polymer. The metal element of the salt substance is at least one selected from chromium, nickel, cobalt, manganese, iron, copper, molybdenum, and zinc.

[0136] In some embodiments of this application, the first polymer is polyvinylpyrrolidone, the solvent of the core solution is acetone, and the mass ratio of the first polymer to the solvent of the core solution is 1:12.

[0137] In some embodiments of this application, the second polymer is polyurethane, the solvent of the shell solution is N,N-diethylacetamide, the mass ratio of the second polymer to the salt substance in the shell solution is 1:1.2, and the mass ratio of the second polymer to the solvent of the shell solution in the shell solution is 1:6.

[0138] In some embodiments of this application, the carbonization treatment is carried out at a temperature of 900°C for 1 hour, and the carbonization treatment is performed in a nitrogen atmosphere.

[0139] In some embodiments of this application, the pre-oxidation treatment is performed at a temperature of 300°C for 0.5 hours in air.

[0140] In some embodiments of this application, the heat treatment temperature is 700°C and the heat treatment time is 1 hour.

[0141] In some embodiments of this application, the coaxial electrospinning is performed using a single coaxial spinneret, and the process parameters of the coaxial electrospinning satisfy the following conditions:

[0142] The voltage is 20kV;

[0143] The spinning solution flow rate is 1.5 mL / h;

[0144] The receiving distance is 20cm;

[0145] The duration of the coaxial electrospinning is 2 hours.

[0146] In this embodiment, the negative electrode of the lithium battery is in the form of a foil, and the thickness of the negative electrode of the lithium battery is 30μm.

[0147] Example 3

[0148] This embodiment provides a method for preparing a lithium battery negative electrode, the method comprising the following steps:

[0149] A fiber membrane was obtained by coaxial electrospinning using a core solution and a shell solution.

[0150] The fiber membrane is subjected to pre-oxidation and carbonization treatments in sequence to obtain a carbon fiber membrane;

[0151] The carbon fiber membrane is heat-treated in an ammonia atmosphere to obtain a current collector;

[0152] In a nitrogen atmosphere, the current collector is immersed in molten lithium metal for 5 minutes to prepare lithium metal on the surface of the current collector, thereby obtaining a pre-fabricated negative electrode;

[0153] The pre-fabricated negative electrode is pressed to obtain the lithium battery negative electrode.

[0154] The fiber membrane has a core structure and a shell structure, the shell structure covering the core structure. The core solution is used to form the core structure during the coaxial electrospinning process, and the shell solution is used to form the shell structure during the coaxial electrospinning process. The core solution includes a carbonizable first polymer, and the shell solution includes a salt substance and a carbonizable second polymer. The metal element of the salt substance is at least one selected from chromium, nickel, cobalt, manganese, iron, copper, molybdenum, and zinc.

[0155] In some embodiments of this application, the first polymer is polyamide, the solvent of the core solution is N,N-dimethylformamide, and the mass ratio of the first polymer to the solvent of the core solution is 1:7.

[0156] In some embodiments of this application, the second polymer is polyvinyl alcohol, the solvent of the shell solution is water, the mass ratio of the second polymer to the salt substance in the shell solution is 1:1, and the mass ratio of the second polymer to the solvent of the shell solution in the shell solution is 1:5.

[0157] In some embodiments of this application, the carbonization treatment is carried out at a temperature of 800°C for 2 hours, and the carbonization treatment is performed in a nitrogen atmosphere.

[0158] In some embodiments of this application, the pre-oxidation treatment is performed at a temperature of 240°C for 0.8 hours in air.

[0159] In some embodiments of this application, the heat treatment temperature is 500°C and the heat treatment time is 1.5 hours.

[0160] In some embodiments of this application, the coaxial electrospinning is performed using a single coaxial spinneret, and the process parameters of the coaxial electrospinning satisfy the following conditions:

[0161] The voltage is 18kV;

[0162] The spinning solution flow rate is 1 mL / h;

[0163] The receiving distance is 17cm;

[0164] The duration of the coaxial electrospinning is 2 hours.

[0165] In this embodiment, the lithium battery negative electrode is in the form of a foil, and the thickness of the lithium battery negative electrode is 20μm.

[0166] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0167] In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. Furthermore, in the description of this application, the terms "comprising," "including," etc., mean "including but not limited to." Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone. For relationships involving three or more related objects described using "and / or", it indicates that any one of the three related objects can exist alone, or at least two of them can exist simultaneously. For example, for A, and / or B, and / or C, it can mean that any one of A, B, and C exists alone, or any two of them exist simultaneously, or all three of them exist simultaneously. In this document, "at least one" means one or more, and "more than one" means two or more. "At least one", "at least one of the following", or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple. The "parts representation" involved in this application, such as parts by weight or parts by mass, indicates the proportional relationship between the components. In the proportional relationships involved in this application, the parameters that need to be described by proportion should be understood as the first term of the proportion in the order of description, and the proportion figures should be understood as the second term of the proportion. For example, if the mass ratio of substance A, substance B and substance C is 1:2:3, then substance A, substance B and substance C should correspond one-to-one with the proportion figures in the proportion in the order of description, that is, the mass of substance A: the mass of substance B: the mass of substance C = 1:2:3.

[0168] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing a lithium battery negative electrode, characterized in that, The method includes the following steps A fiber membrane was obtained by coaxial electrospinning using a core solution and a shell solution. The fiber membrane is pre-oxidized. The fiber membrane is subjected to carbonization treatment to obtain a carbon fiber membrane; The carbon fiber membrane is heat-treated in an ammonia atmosphere to obtain a current collector with metal nitrides on its surface; In an inert atmosphere, the current collector is immersed in molten lithium metal to prepare lithium metal on the surface of the current collector, thereby obtaining a pre-fabricated negative electrode; The pre-fabricated negative electrode is pressed to obtain the lithium battery negative electrode. The fiber membrane has a core structure and a shell structure, the shell structure covering the core structure, the core solution being used to form the core structure during the coaxial electrospinning process, and the shell solution being used to form the shell structure during the coaxial electrospinning process. The core solution includes a carbonizable first polymer, and the shell solution includes a salt substance and a carbonizable second polymer. The metal element of the salt substance is at least one selected from chromium, nickel, cobalt, manganese, iron, copper, molybdenum, and zinc. The heat treatment temperature is 400~700℃, and the heat treatment time is 1~3h.

2. The method for preparing a lithium battery negative electrode according to claim 1, characterized in that, The first polymer is at least one of polyacrylonitrile, polyvinylpyrrolidone, polyvinylidene fluoride, polycaprolactone, polyurethane, silk fibroin, polyamide, polyvinyl alcohol, polymethyl methacrylate, and asphalt; and / or, The solvent of the core solution is at least one selected from water, ethanol, N,N-dimethylformamide, acetone, N,N-diethylacetamide, formic acid, tetrahydrofuran, isopropanol, and hexafluoroisopropanol; and / or, In the core solution, the mass ratio of the first polymer to the solvent of the core solution is 1:5~12.

3. The method for preparing a lithium battery negative electrode according to claim 1, characterized in that, The second polymer is at least one of polyacrylonitrile, polyvinylpyrrolidone, polyvinylidene fluoride, polycaprolactone, polyurethane, silk fibroin, polyamide, polyvinyl alcohol, polymethyl methacrylate, and asphalt; and / or, The solvent for the shell solution is at least one selected from water, ethanol, N,N dimethylformamide, acetone, N,N diethylacetamide, formic acid, tetrahydrofuran, isopropanol, and hexafluoroisopropanol; and / or, In the shell solution, the mass ratio of the second polymer to the salt is 1:0.8~1.2; and / or, In the shell solution, the mass ratio of the second polymer to the solvent of the shell solution is 1:4~6.

4. The method for preparing a lithium battery negative electrode according to claim 1, characterized in that, The coaxial electrospinning is performed through at least one coaxial spinneret. The process parameters for the coaxial electrospinning, averaged across each spinneret, satisfy the following conditions: The voltage is 12~20kV; The spinning solution flow rate is 0.6~1.5 mL / h; The receiving distance is 12~20cm; The duration is 1.8~2.2 hours.

5. The method for preparing a lithium battery negative electrode according to claim 1, characterized in that, The carbonization treatment temperature is 700~900℃; and / or, The carbonization treatment time is 1-3 hours; and / or, The carbonization process is carried out in an inert atmosphere.

6. The method for preparing a lithium battery negative electrode according to claim 1, characterized in that, The pre-oxidation treatment temperature is 200~300℃; and / or, The pre-oxidation treatment time is 0.5~1h; and / or, The pre-oxidation treatment is carried out in an oxygen-containing atmosphere.

7. A lithium battery, characterized in that, The lithium battery includes a lithium battery negative electrode prepared by the method according to any one of claims 1 to 6.

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