Preparation method of lithium battery positive electrode and lithium battery

Abstract

The application relates to a preparation method of a lithium battery positive electrode and a lithium battery and relates to the new energy field.The preparation method of the lithium battery positive electrode comprises the following steps: taking a carbonizable polymer as a material, preparing a fiber film through electrostatic spinning; performing heat treatment on the fiber film to obtain a carbon fiber film; providing a nano sulfur particle suspension and a binder solution; performing suction filtration treatment on the nano sulfur particle suspension and the binder solution by taking the carbon fiber film as a filter membrane to obtain a prefabricated positive electrode; and drying the prefabricated positive electrode to obtain the lithium battery positive electrode.The application provides a large buffer space for volume changes in the mutual conversion process of sulfur and lithium sulfide, and can effectively improve the problem of low positive electrode conductivity of a lithium-sulfur system.In addition, the suction filtration treatment has the advantages of simple operation and easy control of the morphology of sulfur.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of new energy, in particular to a lithium battery. BACKGROUND

[0002] The energy density of lithium ion batteries with ternary and lithium iron phosphate as the positive electrode has reached the theoretical value, reaching the bottleneck of technology development. In order to solve the range anxiety of electric vehicles, it is urgent to develop new battery systems with high energy density. Lithium-sulfur batteries have a theoretical energy density of up to 2600 Wh / kg, several times that of ternary systems. However, the active material sulfur and the discharge end product lithium sulfide in the lithium-sulfur system have low electrical conductivity, resulting in serious battery polarization; the density of the active material sulfur is about 2.07 g / cm 3 , and the density of the discharge end product lithium sulfide is about 1.66 g / cm 3 , resulting in about 80% volume expansion during charging and discharging, which easily causes destructive effects on the positive electrode structure. The technical problems of low electrical conductivity and volume expansion of the positive electrode of the lithium-sulfur system hinder its application in lithium batteries. SUMMARY

[0003] Embodiments of the present application provide a preparation method of a lithium battery positive electrode and a lithium battery to solve the technical problems of low electrical conductivity and volume expansion of the positive electrode of the lithium-sulfur system.

[0004] In a first aspect, embodiments of the present application provide a preparation method of a lithium battery positive electrode, which comprises the following steps:

[0005] Preparation of a fiber membrane by electrospinning using a carbonizable polymer as a material;

[0006] Heat treatment of the fiber membrane to obtain a carbon fiber membrane;

[0007] Providing a nano-sulfur particle suspension and a binder solution, and performing suction filtration treatment on the nano-sulfur particle suspension and the binder solution using the carbon fiber membrane as a filter membrane to obtain a pre-prepared positive electrode;

[0008] Drying the pre-prepared positive electrode to obtain the lithium battery positive electrode.

[0009] In some embodiments of the present application, the polymer material is at least one of polyacrylonitrile, polyvinylpyrrolidone, polyvinylidene fluoride, polycaprolactone, polyurethane, silk fibroin, polyamide, polyvinyl alcohol, polymethyl methacrylate, and pitch; and / or,

[0010] The solvent of the electrospinning solution used in the electrospinning is at least one of water, ethanol, N-N dimethylformamide, acetone, N-N diethylacetamide, formic acid, tetrahydrofuran, isopropyl alcohol, and hexafluoroisopropanol; and / or,

[0011] In the electrospinning solution used for electrospinning, the mass ratio of the polymer material to the solvent in the electrospinning solution is 1:5 to 12.

[0012] In some embodiments of this application, the electrospinning is performed through at least one spinneret, and the process parameters of the electrospinning, averaged across each spinneret, satisfy the following conditions:

[0013] The voltage is 12–20 kV;

[0014] The spinning solution flow rate is 0.6–1.5 mL / h;

[0015] The receiving distance is 12-20cm.

[0016] In some embodiments of this application, the heat treatment includes a pre-oxidation treatment and a carbonization treatment performed sequentially.

[0017] In some embodiments of this application, the temperature of the pre-oxidation treatment is 200–300°C; and / or,

[0018] The pre-oxidation treatment time is 0.5–1 hour; and / or,

[0019] The pre-oxidation treatment is carried out in an oxygen-containing atmosphere; and / or,

[0020] The carbonization treatment temperature is 700–900°C; and / or,

[0021] The carbonization treatment time is 1 to 3 hours; and / or,

[0022] The carbonization process is carried out in an inert atmosphere.

[0023] In some embodiments of this application, the mass ratio of the solvent to the nano-sulfur particles in the nano-sulfur particle suspension is 1:1.5 to 4; and / or,

[0024] The solvent for the nano-sulfur particle suspension includes at least one of N-methylpyrrolidone and N,N-dimethylformamide.

[0025] In some embodiments of this application, the nano-sulfur particle suspension further includes a conductive agent and a surfactant.

[0026] In some embodiments of this application, the conductive agent is at least one of acetylene black and conductive carbon black; and / or,

[0027] In the nano-sulfur particle suspension, the mass ratio of the conductive agent to the nano-sulfur particles is 1:9 to 50; and / or, the surfactant is at least one of hexadecyltrimethylammonium bromide, polyvinylpyrrolidone, and Triton.

[0028] In some embodiments of this application, the adhesive is at least one selected from polyvinylpyrrolidone, polyvinylidene fluoride, polytetrafluoroethylene, polyacrylic acid, styrene-butadiene rubber, and carboxymethyl cellulose; and / or,

[0029] The solvent of the adhesive solution is at least one of N-methylpyrrolidone and N,N-dimethylformamide; and / or,

[0030] The adhesive solution contains an adhesive with a mass fraction of 0.5% to 1%.

[0031] Secondly, embodiments of this application provide a lithium battery, the lithium battery comprising a lithium battery positive electrode prepared by the method described in any embodiment of the first aspect.

[0032] The technical solutions provided in this application have the following advantages compared with the prior art:

[0033] The method for preparing a lithium battery cathode provided in this application involves heat-treating an electrospun fabric to create a carbon fiber membrane with the structural characteristics of an electrospun fabric. Then, using this carbon fiber membrane as a carrier, nano-sulfur particles are loaded through a filtration process, causing the nano-sulfur particles to deposit in the gaps between the carbon fibers of the carbon fiber membrane during filtration. The abundant gaps between the carbon fibers, along with the good flexibility of the carbon fibers themselves, provide a large buffer space for the volume changes during the interconversion of sulfur and lithium sulfide. The large specific surface area of ​​the carbon fiber membrane provides abundant contact sites for sulfur or lithium sulfide, effectively improving the low conductivity of the cathode in the lithium-sulfur system. Furthermore, the filtration process has the advantages of simple operation and easy control of the sulfur morphology. Attached Figure Description

[0034] 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.

[0035] 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.

[0036] Figure 1 This is a schematic flowchart illustrating a method for preparing a lithium battery cathode according to an embodiment of this application. Detailed Implementation

[0037] 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.

[0038] 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.

[0039] 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.

[0040] Existing lithium-sulfur cathode systems suffer from technical problems such as low conductivity and volume expansion.

[0041] The technical solution provided in this application is to solve the above-mentioned technical problems, and the general idea is as follows:

[0042] In a first aspect, embodiments of this application provide a method for preparing a lithium battery positive electrode, the method comprising the following steps:

[0043] S1: Fiber membranes are prepared by electrospinning using carbonizable polymers as materials;

[0044] S2: The fiber membrane is heat-treated to obtain a carbon fiber membrane;

[0045] S3: Provide a suspension of nano-sulfur particles and a binder solution, and use the carbon fiber membrane as a filter membrane to perform vacuum filtration on the suspension of nano-sulfur particles and the binder solution to obtain a pre-fabricated positive electrode;

[0046] S4: Dry the pre-made positive electrode to obtain the lithium battery positive electrode.

[0047] It is easy to understand that in electrospun fabrics, there are usually large gaps between fibers, and the electrospun fabric itself has a large specific surface area. The carbon fiber membrane described in this application is made by heat treatment of the fiber membrane, and the fiber membrane is an electrospun fabric, which gives the carbon fiber membrane the structural characteristics of an electrospun fabric.

[0048] This application employs a filtration process to deposit nano-sulfur particles into the gaps between the carbon fibers of the carbon fiber membrane. During the charging and discharging of the lithium battery cathode, a reaction involving the interconversion of sulfur and lithium sulfide also occurs simultaneously on the surface of the carbon fibers. The abundant gaps between the carbon fibers, along with the good flexibility of the carbon fibers themselves, provide a large buffer space for the volume changes during the interconversion of sulfur and lithium sulfide. The large specific surface area of ​​the carbon fiber membrane provides abundant contact sites for sulfur or lithium sulfide, effectively improving the low conductivity of the cathode in lithium-sulfur systems.

[0049] This application's method of loading nano-sulfur particles onto the carbon fiber membrane via filtration has several advantages. First, the filtration process is very simple to operate; second, compared to electrodeposition and hot-melt casting, filtration allows for the control of sulfur morphology into nano-sulfur particles by using a nano-sulfur particle suspension as the raw material.

[0050] This application involves heat-treating electrospun fabric to create a carbon fiber membrane with the structural characteristics of electrospun fabric. The carbon fiber membrane is then used as a carrier to load nano-sulfur particles through vacuum filtration, causing the nano-sulfur particles to deposit in the gaps between the carbon fibers of the membrane during the filtration process. The abundant gaps between the carbon fibers, along with the good flexibility of the carbon fibers themselves, provide a large buffer space for the volume changes during the interconversion of sulfur and lithium sulfide. The large specific surface area of ​​the carbon fiber membrane provides abundant contact sites for sulfur or lithium sulfide, effectively improving the low cathode conductivity problem of the lithium-sulfur system. Furthermore, vacuum filtration offers advantages such as simple operation and easy control of sulfur morphology.

[0051] In some embodiments of this application, the polymeric material is at least one selected from polyacrylonitrile, polyvinylpyrrolidone, polyvinylidene fluoride, polycaprolactone, polyurethane, silk fibroin, polyamide, polyvinyl alcohol, polymethyl methacrylate, and bitumen; and / or,

[0052] The solvent in the electrospinning solution used for electrospinning is at least one selected from water, ethanol, N,N-dimethylformamide, acetone, N,N-diethylacetamide, formic acid, tetrahydrofuran, isopropanol, and hexafluoroisopropanol; and / or,

[0053] In the electrospinning solution used for electrospinning, the mass ratio of the polymer material to the solvent in the electrospinning solution is 1:5 to 12.

[0054] It is easy to understand that the above-mentioned polymer materials 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.

[0055] The beneficial effect of having a mass ratio of 1:5 to 12 between the polymer material and the solvent in the electrospinning solution is that it ensures that the fibers formed by electrospinning can be well shaped, while also ensuring that the polymer material can be fully dispersed in the electrospinning solution.

[0056] As an example, the mass ratio of the polymer material to the solvent in the electrospinning solution can be 1:5, 1:7, 1:9, 1:10, or 1:12.

[0057] In some embodiments of this application, the electrospinning is performed through at least one spinneret, and the process parameters of the electrospinning, averaged across each spinneret, satisfy the following conditions:

[0058] The voltage is 12–20 kV;

[0059] The spinning solution flow rate is 0.6–1.5 mL / h;

[0060] The receiving distance is 12-20cm.

[0061] It's easy to understand that the beneficial effect of a voltage of 12–20 kV is that it results in fibers with a smaller diameter produced by electrospinning, while ensuring fiber formation. The beneficial effect of a spinning solution flow rate of 0.6–1.5 mL / h is to ensure the efficiency of electrospinning and fiber formation.

[0062] As is easily understood, the receiving distance is the distance from the outlet end of the electrospinning solution at the spinneret to the fiber receiving device. A receiving distance of 12–20 cm has the following advantages: it ensures sufficient electric field strength during electrospinning; it also ensures a suitable displacement distance for the electrospinning solution to reach the fiber receiving device, allowing the fiber receiving device to collect fibers smoothly, and it also allows the solvent to fully evaporate during the movement of the electrospinning solution.

[0063] As an example, the voltage can be 12kV, 14kV, 16kV, 18kV, or 20kV.

[0064] As an example, the spinning solution flow rate can be 0.6 mL / h, 0.8 mL / h, 1 mL / h, 1.3 mL / h, or 1.5 mL / h;

[0065] As an example, the receiving distance can be 12cm, 14cm, 16cm, 18cm, or 20cm.

[0066] In some embodiments of this application, the heat treatment includes a pre-oxidation treatment and a carbonization treatment performed sequentially.

[0067] It is easy to understand that the purpose of the pre-oxidation treatment is to 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.

[0068] In some embodiments of this application, the temperature of the pre-oxidation treatment is 200–300°C; and / or,

[0069] The pre-oxidation treatment time is 0.5–1 hour; and / or,

[0070] The pre-oxidation treatment is carried out in an oxygen-containing atmosphere; and / or,

[0071] The carbonization treatment temperature is 700–900°C; and / or,

[0072] The carbonization treatment time is 1 to 3 hours; and / or,

[0073] The carbonization process is carried out in an inert atmosphere.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] As an example, the temperature of the pre-oxidation treatment is 200°C, 220°C, 240°C, 260°C, 280°C, or 300°C.

[0079] As an example, the pre-oxidation treatment time is 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, or 0.1h.

[0080] As an example, the oxygen-containing atmosphere can be air.

[0081] As an example, the carbonization temperature can be 700°C, 750°C, 800°C, 850°C, or 900°C.

[0082] As an example, the carbonization treatment time can be 1h, 1.5h, 2h, 2.5h, or 3h.

[0083] As an example, the inert atmosphere can be argon or nitrogen.

[0084] In some embodiments of this application, the mass ratio of the solvent to the nano-sulfur particles in the nano-sulfur particle suspension is 1:1.5 to 4; and / or,

[0085] The solvent for the nano-sulfur particle suspension includes at least one of N-methylpyrrolidone and N,N-dimethylformamide.

[0086] It is easy to understand that the beneficial effect of having a solvent-to-nanosulfur particle mass ratio of 1:1.5 to 4 in the nano-sulfur particle suspension is that the nano-sulfur particles can be fully dispersed in the nano-sulfur particle suspension, while ensuring a high concentration of nano-sulfur particles, so that the nano-sulfur particles can be rapidly deposited onto the carbon fiber membrane during the filtration process.

[0087] As an example, the mass ratio of the solvent to the nano-sulfur particles in the nano-sulfur particle suspension can be 1:1.5, 1:2, 1:2.5, 1:3, or 1:4.

[0088] In some embodiments of this application, the nano-sulfur particle suspension further includes a conductive agent and a surfactant.

[0089] In some embodiments of this application, the conductive agent is at least one of acetylene black and conductive carbon black; and / or,

[0090] In the nano-sulfur particle suspension, the mass ratio of the conductive agent to the nano-sulfur particles is 1:9 to 50; and / or, the surfactant is at least one of hexadecyltrimethylammonium bromide, polyvinylpyrrolidone, and Triton.

[0091] It is easy to understand that the beneficial effect of the mass ratio of the conductive agent to the nano-sulfur particles being 1:9 to 50 is that it can both maximize the conductivity of the nano-sulfur particles and ensure that the amount of nano-sulfur particles as active positive electrode materials is sufficient.

[0092] As an example, the mass ratio of the conductive agent to the nano-sulfur particles can be 1:9, 1:20, 1:30, 1:40, or 1:50.

[0093] In some embodiments of this application, the adhesive is at least one selected from polyvinylpyrrolidone, polyvinylidene fluoride, polytetrafluoroethylene, polyacrylic acid, styrene-butadiene rubber, and carboxymethyl cellulose; and / or,

[0094] The solvent of the adhesive solution is at least one of N-methylpyrrolidone and N,N-dimethylformamide; and / or,

[0095] The adhesive solution contains an adhesive with a mass fraction of 0.5% to 1%.

[0096] As an example, the mass fraction of the adhesive can be 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, or 1%.

[0097] Secondly, embodiments of this application provide a lithium battery, the lithium battery comprising a lithium battery positive electrode prepared by the method described in any embodiment of the first aspect.

[0098] The lithium battery is based on the lithium battery positive 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 about by the technical solutions of the above embodiments, which will not be repeated here.

[0099] The present application is further illustrated below with specific examples. 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, unless specific conditions are specified, are generally determined according to industry standards. If no corresponding industry standard exists, then generally accepted international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0100] Example 1

[0101] This application provides a method for preparing a lithium battery positive electrode, which includes the following steps:

[0102] Sa: Fiber membranes are prepared by electrospinning using carbonizable polymers as materials;

[0103] Sb: The fiber membrane is pre-oxidized and carbonized to obtain a carbon fiber membrane;

[0104] Sc: Provide a suspension of nano-sulfur particles and a binder solution. Using the carbon fiber membrane as a filter membrane, the suspension of nano-sulfur particles is dropped onto the carbon fiber membrane for filtration. Then, the binder solution is dropped onto the carbon fiber membrane for filtration to obtain a pre-fabricated positive electrode.

[0105] Sd: Dry the pre-made positive electrode to obtain the lithium battery positive electrode.

[0106] Wherein, the polymer material is polyvinyl alcohol, the solvent of the electrospinning solution used for electrospinning is water, and the mass ratio of the polymer material to the solvent of the electrospinning solution used for electrospinning is 1:9.

[0107] The pre-oxidation treatment is carried out at a temperature of 250°C for 0.8 hours in air. The carbonization treatment is carried out at a temperature of 800°C for 2 hours in nitrogen.

[0108] In the nano-sulfur particle suspension, the mass ratio of the solvent to the nano-sulfur particles is 1:1.5, and the solvent of the nano-sulfur particle suspension is N-methylpyrrolidone.

[0109] The nano-sulfur particle suspension also includes a conductive agent and a surfactant. The conductive agent is acetylene black. In the nano-sulfur particle suspension, the mass ratio of the conductive agent to the nano-sulfur particles is 1:9. The surfactant is hexadecyltrimethylammonium bromide.

[0110] The adhesive is polyvinylidene fluoride, the solvent of the adhesive solution is N-methylpyrrolidone, and the mass fraction of the adhesive in the adhesive solution is 0.5%.

[0111] The electrospinning is performed using a single spinneret, and the process parameters for the electrospinning meet the following conditions:

[0112] The voltage is 12kV;

[0113] The spinning solution flow rate is 0.6 mL / h;

[0114] The receiving distance is 12cm.

[0115] Example 2

[0116] This application provides a method for preparing a lithium battery positive electrode, which includes the following steps:

[0117] Sa: Fiber membranes are prepared by electrospinning using carbonizable polymers as materials;

[0118] Sb: The fiber membrane is pre-oxidized and carbonized to obtain a carbon fiber membrane;

[0119] Sc: Provide a suspension of nano-sulfur particles and a binder solution. Using the carbon fiber membrane as a filter membrane, the suspension of nano-sulfur particles is dropped onto the carbon fiber membrane for filtration. Then, the binder solution is dropped onto the carbon fiber membrane for filtration to obtain a pre-fabricated positive electrode.

[0120] Sd: Dry the pre-made positive electrode to obtain the lithium battery positive electrode.

[0121] Wherein, the polymer material is polyacrylonitrile, the solvent of the electrospinning solution used for electrospinning is N,N-dimethylformamide, and the mass ratio of the polymer material to the solvent of the electrospinning solution used for electrospinning is 1:5.

[0122] The pre-oxidation treatment is carried out at a temperature of 200°C for 1 hour in air. The carbonization treatment is carried out at a temperature of 700°C for 3 hours in nitrogen.

[0123] In the nano-sulfur particle suspension, the mass ratio of the solvent to the nano-sulfur particles is 1:4, and the solvent of the nano-sulfur particle suspension is N,N-dimethylformamide.

[0124] The nano-sulfur particle suspension also includes a conductive agent and a surfactant. The conductive agent is conductive carbon black. In the nano-sulfur particle suspension, the mass ratio of the conductive agent to the nano-sulfur particles is 1:50. The surfactant is polyvinylpyrrolidone.

[0125] The adhesive is polyvinylidene fluoride, the solvent of the adhesive solution is N-methylpyrrolidone, and the mass fraction of the adhesive in the adhesive solution is 1%.

[0126] The electrospinning is performed using a single spinneret, and the process parameters for the electrospinning meet the following conditions:

[0127] The voltage is 20kV;

[0128] The spinning solution flow rate is 1.5 mL / h;

[0129] The receiving distance is 20cm.

[0130] Example 3

[0131] This application provides a method for preparing a lithium battery positive electrode, which includes the following steps:

[0132] Sa: Fiber membranes are prepared by electrospinning using carbonizable polymers as materials;

[0133] Sb: The fiber membrane is pre-oxidized and carbonized to obtain a carbon fiber membrane;

[0134] Sc: Provide a suspension of nano-sulfur particles and a binder solution. Using the carbon fiber membrane as a filter membrane, the suspension of nano-sulfur particles is dropped onto the carbon fiber membrane for filtration. Then, the binder solution is dropped onto the carbon fiber membrane for filtration to obtain a pre-fabricated positive electrode.

[0135] Sd: Dry the pre-made positive electrode to obtain the lithium battery positive electrode.

[0136] Wherein, the polymer material is polyurethane, the solvent of the electrospinning solution used for electrospinning is acetone, and the mass ratio of the polymer material to the solvent of the electrospinning solution used for electrospinning is 1:7.

[0137] The pre-oxidation treatment is carried out at a temperature of 300°C for 0.5 hours in air. The carbonization treatment is carried out at a temperature of 900°C for 1 hour in nitrogen.

[0138] In the nano-sulfur particle suspension, the mass ratio of the solvent to the nano-sulfur particles is 1:2, and the solvent of the nano-sulfur particle suspension is N,N-dimethylformamide.

[0139] The nano-sulfur particle suspension also includes a conductive agent and a surfactant. The conductive agent is acetylene black. In the nano-sulfur particle suspension, the mass ratio of the conductive agent to the nano-sulfur particles is 1:20. The surfactant is Triton.

[0140] The adhesive is carboxymethyl cellulose, the solvent of the adhesive solution is N,N-dimethylformamide, and the mass fraction of the adhesive in the adhesive solution is 0.8%.

[0141] The electrospinning is performed using a single spinneret, and the process parameters for the electrospinning meet the following conditions:

[0142] The voltage is 15kV;

[0143] The spinning solution flow rate is 0.9 mL / h;

[0144] The receiving distance is 15cm.

[0145] 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.

[0146] 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.

[0147] 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 positive electrode, characterized in that, The method for preparing the lithium battery cathode includes the following steps: Fiber membranes are prepared by electrospinning using carbonizable polymers as materials. The fiber membrane is heat-treated to obtain a carbon fiber membrane; A suspension of nano-sulfur particles and a binder solution are provided. Using the carbon fiber membrane as a filter membrane, the suspension of nano-sulfur particles is dropped onto the carbon fiber membrane for filtration, so that the nano-sulfur particles are deposited in the gaps between the carbon fibers of the carbon fiber membrane during the filtration process. Then, the binder solution is dropped onto the carbon fiber membrane for filtration to obtain a pre-fabricated positive electrode. The pre-made positive electrode is dried to obtain the lithium battery positive electrode; In the nano-sulfur particle suspension, the mass ratio of the solvent to the nano-sulfur particles is 1:1.5~4.

2. The method for preparing the lithium battery positive electrode according to claim 1, characterized in that, The polymer material is at least one of the following: polyacrylonitrile, polyvinylpyrrolidone, polyvinylidene fluoride, polycaprolactone, polyurethane, silk fibroin, polyamide, polyvinyl alcohol, polymethyl methacrylate, and asphalt; and / or, The solvent in the electrospinning solution used for electrospinning 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 electrospinning solution used for electrospinning, the mass ratio of the polymer material to the solvent in the electrospinning solution is 1:5~12.

3. The method for preparing the lithium battery positive electrode according to claim 1, characterized in that, The electrospinning is performed through at least one spinneret, and the process parameters for 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.

4. The method for preparing the positive electrode of a lithium battery according to claim 1, characterized in that, The heat treatment includes a pre-oxidation treatment and a carbonization treatment performed sequentially.

5. The method for preparing the lithium battery positive electrode according to claim 4, characterized in that, The pre-oxidation treatment temperature is 200~300℃; and / or, The pre-oxidation treatment time is 0.5–1 hour; and / or, The pre-oxidation treatment is carried out in an oxygen-containing atmosphere; and / or, The carbonization treatment temperature is 700~900℃; and / or, The carbonization treatment time is 1 to 3 hours; and / or, The carbonization process is carried out in an inert atmosphere.

6. The method for preparing a lithium battery cathode according to claim 1, characterized in that, The solvent for the nano-sulfur particle suspension includes at least one of N-methylpyrrolidone and N,N-dimethylformamide.

7. The method for preparing a lithium battery positive electrode according to claim 1, characterized in that, The nano-sulfur particle suspension also includes a conductive agent and a surfactant.

8. The method for preparing a lithium battery positive electrode according to claim 7, characterized in that, The conductive agent is at least one of acetylene black and conductive carbon black; and / or... In the nano-sulfur particle suspension, the mass ratio of the conductive agent to the nano-sulfur particles is 1:9~50; and / or, The surfactant is at least one of cetyltrimethylammonium bromide, polyvinylpyrrolidone, and triton.

9. The method for preparing a lithium battery positive electrode according to claim 1, characterized in that, The adhesive is at least one selected from polyvinylpyrrolidone, polyvinylidene fluoride, polytetrafluoroethylene, polyacrylic acid, styrene-butadiene rubber, and carboxymethyl cellulose; and / or, The solvent of the adhesive solution is at least one of N-methylpyrrolidone and N,N-dimethylformamide; and / or, The adhesive solution contains an adhesive with a mass fraction of 0.5% to 1%.

10. A lithium battery, characterized in that, The lithium battery includes a lithium battery cathode prepared by the method described in any one of claims 1 to 9.

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