Preparation method of integrated electrode

Abstract

The invention relates to the technical field of battery electrodes, and discloses an integrated electrode and a preparation method thereof. The method comprises the following steps: pre-oxidizing, carbonizing and cutting a fiber precursor to obtain carbonized fiber; activating the carbonized fibers to obtain porous fibers; combining the porous cellosilk with an energy storage battery electrode active material through a vapor deposition reaction to obtain active cellosilk; and coating the active fibers with a conductive and / or ion-conductive coating material to obtain the integrated electrode. Through the synergistic effect of the porous carbon skeleton structure design, the vapor deposition active substance and the surface coating, the problem that an active material is easy to separate from a current collector in the charging and discharging process of a traditional electrode is solved, the electrode manufacturing process is simplified, and the prepared self-supporting integrated electrode has high specific capacity, excellent cycling stability and rate capability and is suitable for large-scale popularization and application. The material can be applied to energy storage equipment such as lithium ion batteries, sodium ion batteries, lithium-sulfur batteries, solid-state batteries and the like.

Description

Technical Field

[0001] The present application relates to the field of electrochemical energy storage materials, and in particular to the technology for preparing energy storage battery electrodes. Background Art

[0002] With the rapid development of science and technology, the efficient storage and utilization of energy has become increasingly important, and the development of new energy storage devices has become a major topic in today's scientific and technological fields. In modern society, lithium-ion batteries, sodium-ion batteries, lithium-sulfur batteries, and solid-state batteries have become the most widely used energy storage devices due to their high energy density and long cycle life. These batteries store and release electrical energy through the directional movement of charged particles between positive and negative electrodes.

[0003] In traditional electrode manufacturing, active materials that reversibly store charged particles are mixed with conductive agents, binders, and other agents to form a slurry, which is then coated onto a metal foil current collector. However, this manufacturing method has two significant drawbacks: First, the coated active material often undergoes volume changes during the charge and discharge process. For example, the volume of silicon anodes used in lithium-ion batteries can change by over 400% during lithium insertion and removal, causing the active material to easily separate from the current collector and degrade battery performance. Second, traditional electrode manufacturing involves multiple steps, including powder kneading, homogenization, coating, and roller pressing, placing extremely high demands on engineering control. Adjusting parameters in any particular step often requires significant manpower and resources to adjust the parameters of the entire manufacturing chain.

[0004] To overcome these shortcomings, researchers have developed a number of integrated electrode materials. These materials possess properties such as self-support and high conductivity, and can be used without coating on metal foil. For example, a patent has been filed using a hydrothermal method to deposit active materials onto carbon cloth for lithium / sodium-ion battery electrodes, demonstrating excellent electrochemical performance. Another patent uses electrospinning to prepare organically doped self-supporting porous carbon fiber membrane-based negative electrode materials by regulating porogens and dopants, achieving high capacity and high initial efficiency when applied to lithium-ion batteries.

[0005] However, existing technologies still lack a universal, integrated electrode fabrication method applicable to a wide range of energy storage battery types. In particular, existing technologies have significant shortcomings in terms of active material loading, interface structure control, and overall electrode performance optimization. Therefore, developing an integrated electrode fabrication method that can flexibly control microstructure while balancing high active material loading and structural stability is crucial for improving the performance of energy storage devices. Summary of the Invention

[0006] The purpose of this application is to provide a method for preparing an integrated electrode to solve the problems raised in the above background technology.

[0007] The present application discloses a method for preparing an integrated electrode, comprising the following steps:

[0008] S1, pre-oxidizing, carbonizing, and cutting fiber precursors to obtain carbonized fiber filaments;

[0009] S2, activating the carbonized fiber filaments to obtain porous fiber filaments;

[0010] S3, combining the porous fiber filaments with an energy storage battery electrode active material that can be combined by a vapor deposition reaction to obtain active fiber filaments;

[0011] S4, coating the active fiber filaments with a conductive and / or ion-conducting coating material to obtain an integrated electrode; wherein the integrated electrode can form a film by itself when applied to an energy storage battery.

[0012] In a preferred embodiment, it is characterized in that: in S1, the fiber precursor is selected from the following fibers: natural fibers, chemical fibers, inorganic fibers, biomass-based fibers and composite fibers; wherein the natural fibers include cellulose-based fibers such as cotton and linen, and animal fibers such as hair and silk; the chemical fibers include resin-based fibers, asphalt-based fibers, conductive polymer fibers, adhesive fibers, high-performance aramid fibers, and polyacrylonitrile-based, petroleum coke-based, asphalt-based, and phenolic resin-based fibers; the inorganic fibers include carbon-based fibers such as carbon fiber, carbon nanotube fibers, and graphene fibers; the biomass-based fibers include polylactic acid fibers, chitin fibers, and bacterial silk fibers; and the diameter of the carbonized fiber filaments (CFF) is 1-50 μm.

[0013] In S2, the BET specific surface area of ​​the porous fiber is 100-3000m 2 / g, pore volume of 0.1-2.0cm 3 / g, average pore size is 0.8-50nm;

[0014] In S3, the vapor deposition reaction temperature is 280-1100° C., and the porous fiber pores are pre-filled with reaction raw materials by an impregnation method before the vapor deposition reaction;

[0015] In S4, the reaction temperature used for the coating treatment is lower than the boiling point of the active material contained in the active fiber to avoid the loss of the active material. The specific surface area of ​​the obtained integrated electrode is 0.5-100m 2 / g.

[0016] In a preferred example, the energy storage battery electrode active material is one or more of phosphorus, sulfur, silicon, zinc, lithium, sodium, potassium, and molybdenum disulfide.

[0017] In a preferred embodiment, the conductive and / or ion-conducting coating material is one or more of carbon, conductive polymer, and solid electrolyte.

[0018] In a preferred embodiment, in S1, the pre-oxidation temperature is 170-400° C., the pre-oxidation time is 2-10 h, and the pre-oxidation is carried out in air or an oxygen-containing atmosphere, with the volume fraction of oxygen being 20%-50%.

[0019] In a preferred embodiment, in S1, the carbonization temperature is 400-1100° C., the carbonization time is 0.5-3 h, and the carbonization atmosphere is an inert atmosphere.

[0020] In a preferred embodiment, in S1, cutting is performed before pre-oxidation, before carbonization or after carbonization, and the length of the single wire after cutting is 20 μm-150 mm.

[0021] In a preferred example, in S2, the activation temperature is 850-1100°C, the activation time is 2-10h, the activation atmosphere is a mixture of activation gas and inert gas, the activation gas is one or more mixtures of carbon dioxide, water vapor, and oxygen, and the inert gas is one or more mixtures of nitrogen and argon.

[0022] In a preferred embodiment, in S2, the ratio of the activation gas to the inert gas in the activation atmosphere is 1:10 to 1:1.

[0023] In a preferred embodiment, in S2, potassium hydroxide activator is used instead of activation gas or to assist activation, and the ratio of potassium hydroxide to carbonized fiber filaments is 1:1 to 5:1.

[0024] In a preferred embodiment, in S3, the vapor deposition reaction is physical vapor deposition or chemical vapor deposition, and the reaction apparatus is a tubular furnace, a rotary furnace or a fluidized bed reactor.

[0025] In a preferred embodiment, in S3, the reaction atmosphere consists of reaction gas, auxiliary gas and inert gas, with the reaction gas accounting for 2-90% of the total volume, the auxiliary gas accounting for 0-10% of the total volume, and the inert gas accounting for 10-98% of the total volume.

[0026] In a preferred embodiment, in S3, the porous fiber filaments are surface treated by soaking or calcining before the vapor deposition reaction. When the active material is sulfur, silicon, or zinc, the porous fiber filaments are treated with ammonia at 400-500°C to generate nitrogen-containing element groups on their surface.

[0027] In a preferred example, in S4, when the coating material is carbon, one of the following methods is adopted: chemical vapor deposition coating method, the gas introduced is a mixture of carbon-containing gas and inert gas, the reaction temperature of the vapor deposition equipment is 350-1100°C, and the carbon coating amount is 1-10% of the electrode mass; or liquid phase coating method, the liquid phase coating solvent is one of water, ethanol, acetone, and toluene, and the coating agent is resin or asphalt.

[0028] In a preferred embodiment, in S4, when the coating material is a conductive polymer, a dipping method, a brushing method or an in-situ polymerization method is adopted, and the conductive polymer is one or more of polypyrrole, polyaniline and polythiophene.

[0029] In a preferred example, in S4, when the coating material is a solid electrolyte, an in-situ polymerization method, a sol-gel method or a solution coating method is adopted, and the solid electrolyte is one or more of an oxide solid electrolyte, a sulfide solid electrolyte, a halide solid electrolyte, a polymer solid electrolyte or a composite semi-solid electrolyte.

[0030] In a preferred embodiment, in S4, coating methods using different coating materials are sequentially stacked and used, and the coated materials are heated in an inert environment to carbonize the coating layer and more tightly bond with the fiber.

[0031] In a preferred example, in S4, the coated integrated electrode is post-processed by one of the following methods: mechanical compaction, isostatic compaction or hot pressing process to improve flatness, uniformity and density; or acupuncture, weaving or papermaking to obtain an electrode with a specific fiber structure.

[0032] This application provides an integrated electrode with a clear preparation process and excellent electrochemical performance, and its preparation method. Compared with the existing technology, this invention has the following significant advantages and technical effects:

[0033] The carbonized fiber skeleton obtained by pre-oxidation and high-temperature carbonization treatment has excellent conductivity, chemical stability and mechanical strength, and can provide efficient electron transmission pathways and structural support for electrodes.

[0034] A developed porous structure is constructed through activation treatment, and the BET specific surface area can reach 100-3000m 2 / g, pore volume of 0.1-2.0cm 3 / g, with an average pore size of 0.8-50nm, which provides ample space for the loading of active substances and forms an efficient ion transmission channel.

[0035] The vapor deposition method achieves the effective loading of active substances (such as phosphorus, sulfur, silicon, zinc, lithium, sodium, potassium, and molybdenum disulfide) within the carbon fiber pores. The active material loading amount can be controlled within the range of 1-95% mass increase, which not only ensures sufficient capacity but also maintains excellent mechanical strength, effectively alleviating the problem of volume change during charging and discharging.

[0036] The interface structure of the electrode is further optimized by coating with carbon, conductive polymers or solid electrolytes, which improves the electronic / ionic conductivity performance. At the same time, the active materials are protected from direct contact with the electrolyte, reducing side reactions and improving the coulombic efficiency and cycle stability of the battery.

[0037] Self-supporting integrated electrodes prepared by processes such as hot pressing, needle punching, weaving or papermaking do not require additional current collectors and binders, simplifying the battery assembly process and improving the overall energy density.

[0038] The prepared integrated electrodes exhibit excellent electrochemical energy storage performance. For example, the sulfur-based electrode achieved an initial discharge capacity of 1250 mAh / g at a 0.5C rate, and after 50 cycles, the capacity retention rate reached 82%, significantly superior to conventional coated electrodes. For example, the silicon-based electrode achieved an initial discharge capacity of 2250 mAh / g at a 0.2C rate, an initial coulombic efficiency of 93%, and a capacity retention rate of 99.3% after 100 cycles, far superior to conventional silicon-based electrodes.

[0039] The various process steps of this application work together to form a systematic preparation method, which can optimize the process parameters of each step for different types of energy storage batteries and has good universality and scalability.

[0040] In summary, this application constructs a new integrated electrode with stable structure and excellent electrochemical performance through the synergistic effect of the porous structure design of the carbon fiber skeleton, the vapor deposition loading of the active material and the surface protection coating. It effectively overcomes the defects of the traditional electrode manufacturing process such as the easy separation of the active material from the current collector and the complex engineering control, and realizes the simple preparation of high-performance energy storage battery electrodes, which is of great significance to promoting the development of high-energy density and long cycle life energy storage equipment.

[0041] The specification of this application records a large number of technical features, which are distributed in various technical solutions. If all possible combinations of technical features of this application (i.e., technical solutions) are to be listed, the specification will be too lengthy. In order to avoid this problem, the various technical features disclosed in the above-mentioned invention content of this application, the various technical features disclosed in the various embodiments and examples below, and the various technical features disclosed in the accompanying drawings can be freely combined with each other to form various new technical solutions (these technical solutions are all deemed to have been recorded in this specification), unless such a combination of technical features is technically infeasible. For example, in one example, feature A+B+C is disclosed, and in another example, feature A+B+D+E is disclosed. Features C and D are equivalent technical means that play the same role. Technically, only one of them can be used, and it is impossible to use them at the same time. Feature E can be technically combined with feature C. Then, the solution of A+B+C+D should not be considered as having been recorded because it is technically infeasible, while the solution of A+B+C+E should be considered as having been recorded. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic diagram of the overall process of the preparation method of the integrated electrode according to the present application.

[0043] Figure 2 This is a scanning electron microscope photograph of a sulfur-based integrated electrode prepared according to the method for preparing an integrated electrode of an embodiment of the present application.

[0044] Figure 3 This is an XRD test curve diagram of the composite fiber material prepared according to Example 2 of the present application.

[0045] Figure 4 This is the cycle performance data of the sulfur-based integrated electrode prepared in Example 1 after being assembled into a 2016-type button battery.

[0046] Figure 5 This is the cycle capacity-voltage curve of the silicon-based integrated electrode prepared in Example 2 after being bent 180 degrees 100 times.

[0047] Figure 6 This is the rate performance test result of the molybdenum disulfide-based integrated electrode prepared in Example 4. DETAILED DESCRIPTION

[0048] In the following description, many technical details are provided to help readers better understand this application. However, those skilled in the art will understand that even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in this application can be implemented.

[0049] Description of some concepts:

[0050] Integrated Electrode (ITE): A self-supporting electrode material that can be directly used as an electrode in energy storage batteries without the need for a binder or metal foil current collector. It has the characteristics of structural integrity and excellent electrochemical performance.

[0051] Fiber Original String (FOS): Precursor material used to prepare carbonized fiber, including polymer materials such as polyacrylonitrile-based, asphalt-based or phenolic resin-based, which can be converted into carbon fiber through pre-oxidation and carbonization.

[0052] Pre-oxidation (PO) is a heat treatment process in which fiber precursors are subjected to an oxygen-containing atmosphere to introduce oxygen-containing groups into the polymer chain, forming a heat-resistant structure in preparation for subsequent carbonization.

[0053] Carbonization (C) is the process of treating pre-oxidized fibers at high temperature in an inert atmosphere to remove non-carbon elements and form carbon fibers.

[0054] Cutting (CT) is the process of cutting fiber precursors or carbonized fibers into specific lengths, which can be performed before pre-oxidation, before carbonization, or after carbonization.

[0055] Carbonized Fiber Filament (CFF): Carbon fiber obtained after pre-oxidation and carbonization, with high strength and conductivity.

[0056] Activation (ACT) is the process of treating carbonized fiber at high temperature in the presence of an activating gas (such as CO2, water vapor, oxygen) and / or an activating agent (such as potassium hydroxide) to form microporous and mesoporous structures on the surface and inside of the fiber.

[0057] Porous Fiber Filament (PFF): Carbon fiber with high specific surface area and rich pore structure after activation treatment.

[0058] Vapor Deposition Reaction (VDR): A process in which active substances are deposited onto porous fiber filaments in a vapor environment, including physical vapor deposition (PVD) and chemical vapor deposition (CVD).

[0059] Active Material (AM): Materials that can reversibly store charge, such as phosphorus, sulfur, silicon, zinc, lithium, sodium, potassium, molybdenum disulfide, etc., are the main body of electrochemical reactions in the electrode.

[0060] Active Fiber Filament (AFF): A composite fiber material formed by combining active substances with porous fiber filaments.

[0061] Coating (COA) is the process of depositing one or more layers of conductive and / or ion-conducting materials on the surface of active fiber filaments to improve the conductivity, stability and electrochemical performance of the electrode.

[0062] Conductive polymer (CP): A polymer material with electron conductivity, such as polypyrrole, polyaniline, polythiophene, etc., which can be used as a conductive additive for electrodes.

[0063] Solid State Electrolyte (SSE): A material that can conduct ions under solid conditions, used to improve the ion conductivity of electrode materials, such as LLZTO.

[0064] BET specific surface area: The specific surface area of ​​a material measured using the Brunauer-Emmett-Teller theory, in m 2 / g, reflects the degree of development of the pore structure of the material.

[0065] Pore ​​Volume: The sum of the volumes of all pores per unit mass of material, in cm 3 / g, which is related to the adsorption and energy storage capacity of the material.

[0066] Average Pore Size: The average diameter of the pores in a material, measured in nm, which affects the transmission rate of ions and electrons in the material.

[0067] Rotary Kiln: A rotatable heat treatment device that allows the material to be fully mixed and exposed to the reaction gas through rotation, and is suitable for vapor deposition reactions.

[0068] Fluidized Bed Reactor: A reaction device that uses gas to suspend solid particles and fluidize them to improve the efficiency of gas-solid reactions.

[0069] Papermaking Method: A process in which fiber materials are suspended in a liquid and formed into a uniform film through filtration and drying. It is used to prepare fiber structure electrodes.

[0070] The following is a summary of some of the innovative features of this application:

[0071] In summary, this application, by deeply understanding the contradictory relationship between material volume change and structural stability in the field of energy storage battery electrode materials, and addressing the difficulty in controlling manufacturing parameters due to the high correlation of engineering control parameters, proposes an integrated electrode construction strategy based on the synergistic integration of a porous carbon fiber skeleton and vapor-deposited active materials. The core innovation of this strategy lies in:

[0072] First, the carbonized fiber is obtained by pre-oxidation-carbonization-cutting of the fiber precursor, and the activation temperature (600-1150℃), activation time (1-20h), activation gas and inert gas ratio (1:10 to 10:1) and other parameters are precisely controlled to make the porous fiber filaments 100-3000m thick. 2 / g specific surface area, while achieving pore size distribution control in the range of 0.8-50nm, constructing a three-dimensional porous skeleton network with electrical conductivity and ion transport capabilities at the microscopic level and self-supporting properties at the macroscopic level;

[0073] Secondly, by using a vapor deposition reaction in the temperature range of 280-1100°C rather than simple physical adsorption or wet chemical mixing, a chemical bond is formed between the active material of the energy storage battery electrode and the porous fiber filaments. Based on the synergistic effect of pre-filling by impregnation and chemical surface treatment (ammonia treatment at 400-500°C), the active material is evenly distributed and firmly fixed in the pores, which is difficult to achieve through conventional physical mixing methods. This solves the structural damage problem caused by the large expansion of the active material in traditional electrodes during charge and discharge (for example, the volume change of silicon negative electrode during lithium insertion / de-lithiation is greater than 400%).

[0074] Finally, by selecting a coating material based on the characteristics of the active material, a coating process was used to construct a conductive and / or ion-conducting coating layer (such as carbon, conductive polymer, or solid electrolyte). This not only provides dual electron / ion channels but also inhibits adverse reactions between the active material and the electrolyte at the interface scale. This multi-level, multi-scale structural design principle, combined with precise process parameter control, cleverly resolves the long-standing technical contradiction in energy storage electrode materials, which requires both high active material loading and structural stability. This allows the prepared integrated electrode to achieve electrochemical performance that is difficult to achieve with traditional coated electrodes without the need for external binders and metal current collectors. The sulfur-based electrode has a discharge capacity of 1250mAh / g and a capacity retention rate of 82% after 50 cycles. The silicon-based electrode has an initial discharge capacity of 2250mAh / g and a capacity retention rate of 99.3% after 100 cycles.

[0075] More importantly, the process system established in this application is not a "customized" solution for a specific electrode material. Instead, through systematic parameter optimization and screening, it establishes a universal methodology that can be adapted to the needs of different energy storage systems. This significantly simplifies the electrode manufacturing process while providing an engineering-feasible technical path for the development of next-generation high-energy-density, long-cycle-life energy storage devices.

[0076] Furthermore, during the implementation of this application, it was found that there is an important correlation between the microstructural parameters of the integrated electrode and the macroscopic electrochemical performance. These relationships provide guidance for process optimization: First, the porous structure characteristics directly affect the ion transport performance of the electrode. By comparing the examples, it can be seen that when the specific surface area of ​​the carbon fiber skeleton is within an appropriate range (such as 1200m in Example 1), the ion transport performance of the electrode is significantly improved. 2 / g), can provide an ideal ion transport channel; and as described in the embodiment, too low specific surface area (such as only 650m2 when activated at 800℃) 2 / g) will lead to a decrease in sulfur loading and insufficient specific capacity; an excessively high specific surface area may lead to an uneven pore structure, affecting the cycle stability. At the same time, the pore size distribution also has a significant effect on the rate performance. For example, the BET test in Example 1 shows that the narrow distribution characteristics of the integrated electrode centered at 2nm help to improve the utilization rate of sulfur, thereby improving the specific capacity and rate performance. Secondly, there is a balance between the active material loading and the overall performance of the electrode. As shown in Example 1, the optimized sulfur deposition time (5h) enables the sulfur loading to reach about 28wt%, which not only ensures sufficient specific capacity (1180mAh / g at 0.2C), but also maintains good cycle stability (85% retention after 50 cycles). However, experimental comparisons show that when the sulfur loading time is insufficient (3h), the loading amount is too low, resulting in insufficient specific capacity; if the loading time is too long (8h), it is easy to cause sulfur to agglomerate and enrich on the fiber surface, blocking the pores, resulting in sulfur falling off the fiber surface during subsequent use, and accelerating capacity decay. This phenomenon is closely related to the dispersion state of the active material in the porous structure. Third, the coating properties are crucial to the interface stability and performance of the electrode. As shown in Example 1, the thickness of the carbon coating layer obtained by controlling the acetylene deposition time (2h) is about 15nm, which is evenly coated on the fiber surface and tightly bonded to the fiber interface. Experimental comparison shows that when the carbon coating temperature is too low (400°C), the coating layer is too thin (<5nm) and the structure is not strong. Although the initial discharge capacity is high (1300mAh / g), the cycle stability is poor (the retention rate after 50 cycles is only 70%); when the temperature is too high (500°C), the coating layer is too thick (>30nm), which hinders the diffusion of lithium ions, and the loss of sulfur causes the capacity to decrease (only 850mAh / g). This phenomenon illustrates the importance of controlling the thickness of the coating layer. Finally, it can be observed from the electrochemical test results of the embodiment that the excellent comprehensive performance of the integrated electrode of the present application is derived from the synergistic effect of the multi-scale structure. The carbon fiber skeleton provides a continuous electron transport network, resulting in a low resistivity (e.g., only 1.5Ω / cm in Example 1). The uniform dispersion of the active material within the pores shortens the ion migration path, improving rate performance. The surface coating effectively suppresses side reactions and increases coulombic efficiency (e.g., 99.8% for sulfur-based electrodes). This multi-level structural design of "skeleton-active material-protective layer" effectively solves the problem of balancing capacity and cycling stability in traditional electrodes.

[0077] In order to make the objectives, technical solutions and advantages of this application clearer, the implementation methods of this application will be further described in detail below with reference to the accompanying drawings.

[0078] The present application relates to a method for preparing an integrated electrode, the overall process of which is as follows: Figure 1 As shown, the method includes the following steps:

[0079] Step 100: pre-oxidize, carbonize, and cut the fiber precursor to obtain carbonized fiber filaments.

[0080] Step 200: activating the carbonized fiber filaments to obtain porous fiber filaments.

[0081] Step 300 : combining the porous fiber filaments with an energy storage battery electrode active material that can be combined by a vapor deposition reaction through a vapor deposition reaction to obtain active fiber filaments.

[0082] Step 400: coating the active fiber filaments with a conductive and / or ion-conducting coating material to obtain an integrated electrode; wherein the integrated electrode can form a film by itself when applied to an energy storage battery.

[0083] Optionally, in step 100, the fiber precursors are selected from raw materials including but not limited to natural fibers (such as cellulose-based cotton, linen, etc., animal fibers such as hair and silk, etc.), chemical fibers (such as various resin-based fibers, asphalt-based fibers, conductive polymer fibers, adhesive fibers, high-performance fibers such as aramid, especially polyacrylonitrile-based, petroleum coke-based, asphalt-based, phenolic resin-based fibers, etc.), inorganic fibers (such as carbon-based fibers such as carbon fibers, carbon nanotube fibers, graphene fibers, etc.), biomass-based fibers (such as polylactic acid fibers, chitin fibers, bacterial silk fibers, etc.), and various composite fibers. The diameter of the carbonized fiber filaments is 1-50 microns;

[0084] In step 200, the BET specific surface area of ​​the porous fiber is 100-3000m 2 / g, pore volume of 0.1-2.0cm 3 / g, average pore size is 0.8-50nm;

[0085] In step 300, the vapor deposition reaction temperature is 280-1100° C., and the porous fiber pores are pre-filled with reaction raw materials by an impregnation method before the vapor deposition reaction to promote the vapor deposition reaction;

[0086] In step 400, the reaction temperature used in the coating treatment is lower than the boiling point of the active material contained in the active fiber to avoid the loss of the active material. The specific surface area of ​​the obtained integrated electrode is 0.5-100m 2 / g.

[0087] Optionally, the energy storage battery electrode active material is one or more of phosphorus, sulfur, silicon, zinc, lithium, sodium, potassium, and molybdenum disulfide.

[0088] Optionally, the conductive and / or ion-conducting coating material is one or more of carbon, conductive polymer, and solid electrolyte.

[0089] Optionally, in step 100, the pre-oxidation temperature is 170-400° C., the pre-oxidation time is 2-10 h, and the pre-oxidation is performed in air or an oxygen-containing atmosphere with an oxygen volume fraction of 20%-50%.

[0090] Optionally, in step 100, the carbonization temperature is 400-1100° C., the carbonization time is 0.5-3 h, and the carbonization atmosphere is an inert atmosphere.

[0091] Optionally, in step 100, cutting is performed before pre-oxidation, before carbonization, or after carbonization, and the length of a single wire after cutting is 20 μm-150 mm.

[0092] Optionally, in step 200, the activation temperature is 600-1150°C, preferably 850-1100°C, the activation time is 1-20h, preferably 2-10h, and the activation atmosphere is a mixture of activation gas and inert gas, the activation gas is a mixture of one or more of carbon dioxide, water vapor, and oxygen, and the inert gas is a mixture of one or more of nitrogen and argon.

[0093] Optionally, in step 200, the ratio of the activation gas to the inert gas in the activation atmosphere is 1:10 to 10:1, preferably 1:10 to 1:1.

[0094] Optionally, in step 200, potassium hydroxide activator is used instead of activation gas or to assist activation, and the ratio of potassium hydroxide to carbonized fiber filaments is 1:5 to 10:1, preferably 1:1 to 5:1.

[0095] Optionally, in step 300, the vapor deposition reaction is physical vapor deposition or chemical vapor deposition, and the reaction apparatus is a tubular furnace, a rotary furnace or a fluidized bed reactor.

[0096] Optionally, in step 300, the reaction atmosphere consists of reaction gas, auxiliary gas and inert gas, with the reaction gas accounting for 2-90% of the total volume, the auxiliary gas accounting for 0-10% of the total volume, and the inert gas accounting for 10-98% of the total volume.

[0097] Optionally, in step 300, the porous fiber filaments are surface treated by soaking or calcining before the vapor deposition reaction. When the active substance is sulfur, silicon, or zinc, the porous fiber filaments are treated with ammonia at 400-500°C to generate nitrogen-containing element groups on their surface.

[0098] Optionally, in step 400, when the coating material is carbon, one of the following methods is adopted: chemical vapor deposition coating method, the gas introduced is a mixture of carbon-containing gas and inert gas, the reaction temperature of the vapor deposition equipment is 350-1100°C, and the carbon coating amount is 1-10% of the electrode mass; or liquid phase coating method, the liquid phase coating solvent is one of water, ethanol, acetone, and toluene, and the coating agent is resin or asphalt.

[0099] Optionally, in step 400, when the coating material is a conductive polymer, a dipping method, a brushing method or an in-situ polymerization method is adopted, and the conductive polymer is one or more of polypyrrole, polyaniline and polythiophene.

[0100] Optionally, in step 400, when the coating material is a solid electrolyte, an in-situ polymerization method, a sol-gel method or a solution coating method is adopted, and the solid electrolyte is one or more of an oxide solid electrolyte, a sulfide solid electrolyte, a halide solid electrolyte, a polymer solid electrolyte or a composite semi-solid electrolyte.

[0101] Optionally, in step 400, coating methods using different coating materials are sequentially stacked and the coated materials are heated in an inert environment to carbonize the coating layer and more tightly bond it to the fibers.

[0102] Optionally, in step 400, the coated integrated electrode is post-processed by one of the following methods: mechanical compaction, isostatic compaction or hot pressing process to improve flatness, uniformity and density; or acupuncture, weaving or papermaking to obtain an electrode with a specific fiber structure.

[0103] Specific Examples 1-4 are further described below.

[0104] In the present application, fiber precursors (FOS) can be made of a variety of fiber materials, including but not limited to: natural fibers (such as cellulose-based cotton, linen, etc., animal fibers such as hair and silk, etc.), chemical fibers (such as various resin-based fibers, asphalt-based fibers, conductive polymer fibers, viscose fibers, high-performance fibers such as aramid, especially polyacrylonitrile-based, petroleum coke-based, asphalt-based, phenolic resin-based fibers, etc.), inorganic fibers (such as carbon-based fibers, carbon nanotube fibers, graphene fibers, etc.), biomass-based fibers (such as polylactic acid fibers, chitin fibers, bacterial silk fibers, etc.) and various composite fibers.

[0105] Different fiber types may require appropriate adjustments to process parameters during the pre-oxidation and carbonization processes. Process parameters such as pre-oxidation temperature, carbonization temperature, and treatment time can be adjusted based on the fiber's chemical composition, structural characteristics, and thermal stability. For example, the pre-oxidation and carbonization temperature windows vary for different fiber types, and the gas selection during the activation process may also need to be optimized based on the specific fiber type.

[0106] The choice of different fibers will affect the mechanical properties, conductivity, and pore structure of the final integrated electrode and can be selected based on specific application requirements. The following examples primarily illustrate polyacrylonitrile-based, asphalt-based, and phenolic resin-based fibers. Those skilled in the art can adapt the methods described and the characteristics of different fibers to achieve integrated electrodes with varying performance characteristics.

[0107] Furthermore, during the implementation of this application, the physical properties and electrochemical performance of the coated integrated electrode can be further optimized through a variety of post-processing processes. These post-processing processes mainly include the following categories:

[0108] Mechanical compaction: Improves the density and strength of the electrode by applying unidirectional or multi-directional mechanical pressure. Mechanical compaction can be performed using equipment such as hydraulic presses and roller presses and is suitable for electrode materials of various shapes and sizes.

[0109] Isostatic compaction: This technique uses a fluid medium to apply uniform, omnidirectional pressure, preventing uneven material deformation that can occur under unidirectional pressure. Compared to traditional mechanical compaction, isostatic compaction achieves more uniform pressure distribution, avoiding stress concentration within the material and improving the structural stability of the electrode.

[0110] Hot Pressing: Applying pressure under heating conditions simultaneously achieves plastic deformation and structural solidification of the material. Hot press molding not only increases the density of the electrode, but also promotes internal bonding of the material, enhancing the overall strength and conductivity of the electrode.

[0111] Fiber structure processing: including needle punching, weaving, and papermaking. Needle punching uses mechanical needles to crosslink fibers, forming a three-dimensional network structure; weaving interweaves fibers in a specific pattern to create a directional structure; and papermaking uses a wet process to prepare a uniformly dispersed fiber membrane.

[0112] The choice of these post-processing processes depends on the specific application scenario and performance requirements of the electrode. For example, for electrodes requiring high energy density, mechanical compaction or isostatic compaction processes may be preferred; for electrodes requiring high flexibility, needle punching or weaving processes may be selected; and for large-area uniform thin film electrodes, papermaking may be a more appropriate choice.

[0113] In the following examples, the specific applications of hot pressing and needling are mainly demonstrated. Those skilled in the art may select other appropriate post-processing processes according to actual needs.

[0114] Example 1: Preparation of sulfur-based integrated electrodes from polyacrylonitrile-based fiber precursors

[0115] Raw Material Preparation: The polyacrylonitrile (PAN) fiber precursor used in this example was prepared using a wet spinning process and has fiber diameter, linear density, tensile strength, and elongation properties suitable for subsequent carbonization treatment. The homemade water-based polyurethane and water-based polyurethane curing agent were dissolved in water in appropriate proportions and stirred evenly. For example, a molar ratio of 1:1.1 was dissolved in 100 times the mass of water and stirred evenly to form a uniform and stable sizing agent solution. This ratio was optimized through orthogonal experiments and can give the sizing agent optimal wettability, adhesion, and film-forming properties, providing the necessary mechanical support and protection for the subsequent fiber pre-oxidation process.

[0116] Step 100: Pre-oxidation, carbonization, cutting

[0117] Weigh 1 kg of the above-mentioned PAN fiber precursor, immerse it in the prepared sizing agent, immerse it for 15 minutes, take it out, and dry it at 110±5°C for 2 hours to obtain PAN fiber with a surface evenly coated with the sizing agent.

[0118] An automatic laser cutting machine was used to cut the sizing-treated PAN fibers into equal length segments of (65 ± 1) mm. The cuts were clean, burr-free, and had consistent fiber orientation. The 65 mm cut length was chosen based on considerations of the suitability of subsequent processing equipment and the product's application requirements, falling near the midpoint of the preferred length range of 20 μm to 150 mm.

[0119] The cut PAN fibers were pre-oxidized in a tubular furnace at 200°C for 4 hours at a heating rate of 2°C / min, with an air flow rate of 1.5 L / min and an O2 volume fraction of 21%. This pre-oxidation temperature and time, verified through extensive experiments, ensures sufficient intramolecular cyclization, dehydrogenation, and cross-linking of the PAN molecules while maximally maintaining fiber morphology and strength. The O2 in the air provides an ideal pre-oxidation reaction atmosphere.

[0120] The pre-oxidized PAN fibers were transferred to a carbonization furnace. The temperature was first raised to 600°C at a rate of 5°C / min under a nitrogen flow of 5 L / min, followed by carbonization at a constant temperature for 2 hours. A controlled heating rate of 5°C / min suppressed surface defects during carbonization. Maintaining the temperature for 2 hours ensured that each link within the PAN molecular chain was fully cracked and cross-linked, resulting in carbon fibers with excellent performance and uniform structure. Furthermore, nitrogen protection played a crucial role in preventing oxidation of the carbon fibers at high temperatures.

[0121] Step 200: CO2 Activation Treatment 1 kg of the carbonized PAN fiber obtained in step 100 was weighed and placed in a rotary drum activation furnace, which was sealed and evacuated to -0.1 MPa.

[0122] Under the continuous flow of 5L / min of high-purity nitrogen, the furnace temperature was raised to 900°C at a rate of 5°C / min and then stabilized for 2 hours. 900°C is within the preferred activation temperature range of 850-1100°C and represents the optimal temperature determined through extensive prior experiments, achieving a balance between activation and strength.

[0123] The flow ratio of N2 to CO2 was adjusted to 1:1 (volume ratio), maintaining a total flow rate of 5 L / min, and activation was continued for 5 hours. A 1:1 ratio of the two gases was determined to be the optimal solution after comprehensive consideration of factors such as activation efficiency and cost. While excessively high CO2 concentrations (e.g., 2:1) can increase the specific surface area, they can easily lead to overactivation, resulting in decreased fiber strength and pore structure collapse. On the other hand, excessively low CO2 concentrations (e.g., 1:2) can slow the activation process and limit the increase in specific surface area. A 1:1 gas ratio strikes a good balance between these two factors.

[0124] After activation, the CO2 introduction was stopped and the mixture was cooled to room temperature at a rate of 3°C / min under N2 protection to obtain porous carbon fibers with rich active sites and well-developed pores.

[0125] After cooling to room temperature, the porous carbon fibers were removed, surface dust was purged with nitrogen, and the activated carbon fibers were weighed. The yield from the activation process was calculated. The resulting product was black, consistent in length with the original carbon fibers, had no apparent surface defects, and exhibited a certain degree of flexibility when handled.

[0126] The product was characterized by N2 adsorption-desorption, and its BET specific surface area was measured to be (1200±50)m 2 / g, pore volume (0.7±0.05)cm 3 / g, with an average pore diameter of (1.8±0.05) nm. A comprehensive analysis of parameters such as specific surface area, pore volume, and pore diameter reveals that this porous carbon fiber exhibits high porosity, large specific surface area, and a concentrated pore size distribution, providing an ideal porous substrate for sulfur loading. These structural parameters are all within the optimal ranges defined in the claims.

[0127] Step 300: H2S vapor deposition introduces sulfur

[0128] 500 g of the porous carbon fiber prepared in step 200 was weighed, placed in a quartz tube vapor deposition furnace (inner diameter 50 mm), and evenly spread using a quartz boat.

[0129] Under the protection of 2L / min high-purity N2, the temperature was raised to 400°C at a rate of 5°C / min, and then maintained at this temperature while introducing 0.1L / min of NH3 gas. NH3 pretreatment significantly increased the nitrogen content on the fiber surface. XPS characterization confirmed the introduction of nitrogen-containing functional groups such as pyridine and pyrrole. TG testing confirmed the successful loading of sulfur onto the carbon fibers, with a loading capacity of approximately 28wt%.

[0130] Adjust the N2 flow rate to 2L / min, then introduce 1L / min H2S (purity 99.99%), raise the temperature to 700℃, and continue the vapor deposition reaction for 5h.

[0131] The volume ratio is 1:2, the H2S partial pressure is about 0.33atm, and the reaction temperature and time are optimized through thermodynamic calculations and kinetic experiments, which can inhibit the aggregation and growth of elemental sulfur while the reaction is fully carried out.

[0132] After the reaction is completed, H2S is turned off and the mixture is naturally cooled to room temperature under the protection of N2 to obtain gray-yellow sulfur / carbon composite fibers with a smooth surface and no obvious sulfur frost.

[0133] The product was taken out and weighed, and the sulfur loading was approximately (28±3) wt%.

[0134] Comparing the samples before and after vapor deposition, the specific surface area increased from 1200m 2 / g dropped to (260±20)m 2 / g, and the pore volume decreased from 0.7 cm3 / g to (0.09±0.02) cm3 / g, indicating that sulfur has been efficiently filled into the pores of carbon fibers, achieving a nano-confinement effect, which indicates excellent electrochemical performance.

[0135] Step 400: Carbon cladding & molding

[0136] Weigh 400g of the sulfur / carbon composite fiber synthesized in step 300 and place it back into the tubular vapor deposition furnace. The temperature was initially raised to 420°C under 3L / min N2. This temperature, optimized through preliminary thermal analysis and mechanical property testing, was not only below the boiling point of elemental sulfur (444.6°C), preventing sulfur evaporation, but also below the temperature of the carbon-sulfur reaction (>1100°C), preventing performance degradation.

[0137] After the temperature stabilizes, switch the gas source and introduce 1L / min acetylene (carbon-containing gas) and 2L / min N2 (carrier gas). Maintain the temperature at normal pressure for 2 hours to allow the acetylene to decompose and deposit on the surface of the composite fiber to form a dense carbon coating.

[0138] After vapor deposition, the acetylene feed was discontinued and the electrode was cooled to room temperature at a rate of 2°C / min under a nitrogen atmosphere. The material was then unloaded to yield a black fiber product with no apparent agglomeration. Weight calculations revealed that the carbon coating accounted for (6±1)% of the total electrode mass, consistent with the theoretical design value.

[0139] The fiber product was placed in a stainless steel mold using an automated hot press and maintained at 170°C and 20 MPa for 10 minutes. This resulted in a 100±5 μm thick, integrated sulfur / carbon / carbon electrode with neat edges, a smooth surface, and bendable, self-supporting properties. The 170°C hot-pressing temperature, well below the boiling point of elemental sulfur, maximized the retention of active material. The 20 MPa pressure, optimized through systematic testing, ensured electrode density without excessive deformation.

[0140] Product characterization and performance evaluation

[0141] The prepared electrodes were characterized by SEM. Figure 2 It can be seen that the fibers are uniform in size and interconnected in a network, with a diameter of about 10 μm and a length of >500 μm. There is no obvious agglomeration of sulfur particles on the fiber surface.

[0142] BET test shows that the specific surface area of ​​the integrated electrode is (2.5±0.3)m 2 / g, which is consistent with the process design and far below 100m 2 The upper limit requirement of 100 / g helps to suppress side reactions such as electrolyte decomposition. The pore size distribution curve shows a narrow distribution characteristic centered at 2nm, which helps to improve sulfur utilization.

[0143] The electrode can be bent 180° without cracks, indicating that the integrated structure gives the electrode excellent mechanical properties, laying the foundation for the application of flexible devices.

[0144] The prepared integrated electrode was used as the positive electrode and the metal lithium sheet as the negative electrode to assemble a 2016-type button battery. During the first discharge at a 0.2C rate, the electrode specific capacity reached 1250mAh / g, the coulombic efficiency was 89%, and the capacity retention rate was greater than 82% after 50 cycles.

[0145] Figure 4 Shown is the cycle performance data of the sulfur-based integrated electrode prepared in Example 1 after being assembled into a 2016-type button battery. As can be seen from the figure, the battery shows good cycle stability during 50 cycles, the initial charge and discharge specific capacity is high, and the capacity retention rate after 50 cycles is greater than 82%. In the figure, the black squares represent the charging process, the red dots represent the discharge process, the vertical axis is the specific capacity (mAh / g), and the horizontal axis is the number of cycles. These data demonstrate that the prepared integrated electrode has excellent electrochemical properties and cycle stability, which is significantly better than the reference sulfur / carbon electrode under the same conditions (first discharge 1050mAh / g, 50 cycle retention rate <70%). The specific capacity at 0.5C and 1C rates reaches 980mAh / g and 860mAh / g, respectively, showing excellent rate performance.

[0146] The prepared integrated electrode was used as the negative electrode, the NCM811 electrode sheet as the positive electrode, and PEO-LiTFSI (EO:Li = 9:1) as the solid electrolyte to form a monolithic soft-pack battery. Constant current charge and discharge tests were conducted at 65°C. The specific capacity reached 1030 mAh / g, and the initial coulombic efficiency reached 81%.

[0147] The resulting integrated electrode served as the positive electrode, and a flexible lithium metal foil supported on copper foil served as the negative electrode. A flexible liquid soft-pack battery was assembled and subjected to bending constant-current charge-discharge tests. Before bending, the specific capacity reached 1125 mAh / g, and after 100 180-degree bends, the capacity retention rate exceeded 95%.

[0148] A multi-channel battery testing system was used to evaluate the consistency of 20 batteries prepared in the same batch. The dispersion of initial specific capacity, coulombic efficiency, and energy efficiency was controlled within ±1%, indicating the controllability and repeatability of the preparation process of this embodiment.

[0149] Design and discussion of comparative examples

[0150] Taking activation temperature as an example, the effect of activation temperature on the pore structure parameters and electrochemical performance of the electrode was investigated. The results showed that when activated at 800℃, the fiber specific surface area was only 650m 2 / g, the sulfur loading is reduced to 20wt%, the first discharge capacity at 0.5C is 820mAh / g; when activated at 1050℃, the specific surface area increases to 2300m 2 / g, but the pore structure is uneven and the pore wall collapses severely, resulting in increased structural damage and accelerated capacity decay during cycling. A comparison of the two shows that 900℃ is the optimal temperature point for balancing porosity and pore structure stability.

[0151] The effects of optimized sulfur deposition time (3, 5, and 8 hours) on electrode performance were investigated. Results showed that 3 hours resulted in low sulfur loading (<20%) and insufficient specific capacity, while 8 hours was associated with increased sulfur aggregation, pore blockage, and accelerated capacity decay. 5 hours was found to be the optimal balance between sulfur loading and dispersion, consistent with cycling performance results.

[0152] Using characterization methods such as thermogravimetry-differential scanning calorimetry (TG-DSC), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and Raman spectroscopy, we systematically analyzed the composition, structure, morphology, and interface changes of the samples before and after each key step, verified the necessity of process parameter optimization, and elucidated the synergistic enhancement mechanism of multi-level porous structure construction and gradient functionalization: ① The high specific surface area and abundant mesopores can effectively buffer the volume expansion of sulfur and inhibit the shuttling of polysulfides; ② The surface nitrogen-containing groups can not only chemically adsorb active sulfur species, but also promote the rapid deintercalation of Li+, thereby improving the reaction kinetics; ③ The outer carbon coating can physically block the dissolution of sulfur while ensuring the efficient transmission of electrons and ions.

[0153] Summary This example uses polyacrylonitrile-based carbon fibers as the skeleton, and through systematic optimization of key reaction conditions and structural parameters such as CO2 activation, NH3 surface modification, H2S sulfurization, and acetylene cracking carbon coating, successfully constructed a sulfur / carbon / carbon integrated electrode with a multi-level porous structure and a chemical and physical gradient synergistically regulated interface. The electrode has the advantages of high sulfur loading (28%), high specific capacity (1250mAh / g@0.2C), high rate performance (860mAh / g@1C), and long cycle life (82% retention rate after 50 cycles). These results demonstrate the advanced nature of the process route of this application and provide new ideas for the practical application of high-performance lithium-sulfur batteries. Subsequent research can focus on clarifying the evolution of electrode / electrolyte interface components, quantifying kinetic mechanisms, and examining the introduction of more functionalized coatings (such as phosphating, doping, etc.) to further explore the potential of electrode materials.

[0154] Example 2: Preparation of silicon-based integrated electrodes from polyacrylonitrile-based fiber precursors

[0155] Raw material preparation

[0156] The polyacrylonitrile (PAN) fiber precursor used in this example was produced using a wet spinning process and possesses fiber diameter, linear density, tensile strength, and elongation characteristics suitable for subsequent carbonization. A water-based polyurethane and a water-based polyurethane curing agent were dissolved in water in an appropriate ratio and stirred evenly. For example, a molar ratio of 1:1 was dissolved in 100 times the mass of water. The mixture was stirred thoroughly to form a uniform, transparent sizing solution. The viscosity was controlled between 300 and 500 mPa·s to ensure wettability of the PAN fibers and sufficient sizing solution adhesion.

[0157] Step 100: Pre-oxidation, carbonization and cutting

[0158] 1 kg of PAN fiber precursor was immersed in the prepared sizing solution, immersed at 80°C for 2 hours, taken out, and placed in a 110°C oven to dry for 4 hours to obtain PAN fiber with a surface evenly coated with the sizing agent.

[0159] The sizing-treated PAN fibers are cut into equal lengths of (110 ± 5) mm using an automatic cross-cutting machine, with smooth cuts. A length of approximately 110 mm helps ensure uniformity and batch stability during the subsequent carbonization process.

[0160] The cut PAN fibers were placed in a tubular furnace and heated in air at a rate of 2°C / min to 200°C, then at a rate of 1°C / min to 280°C, where they were held for 3 hours to complete the pre-oxidation process. This two-stage heating process facilitates the slow crosslinking of PAN macromolecules in the initial stage and the full cyclization and dehydrogenation in the later stages.

[0161] The brown-black PAN fibers obtained by pre-oxidation were first heated to 600°C at a rate of 5°C / min under a nitrogen gas flow and held for 2 hours to achieve carbonization. The temperature was then further raised to 1000°C and held for 1 hour to further improve the degree of carbonization and carbon yield. This two-stage carbonization process produces carbon fibers with a more ordered structure while maintaining the mechanical properties of the fibers.

[0162] Step 200: CO2 activation treatment

[0163] Weigh 500 g of the carbon fiber prepared in step 100, place it in a rotary drum activation furnace, evacuate it, introduce 5 L / min of high-purity N2, raise the temperature to 900°C at a rate of 5°C / min, and keep the temperature constant for 1 hour.

[0164] The CO2 and N2 flow ratio was adjusted to 1:2, the total flow rate was maintained constant at 5 L / min, and activation was continued for 8 hours. Compared with Example 1, a longer activation time is beneficial for obtaining a higher specific surface area, providing more sites for subsequent silicon loading.

[0165] After activation, the CO2 valve was closed and the mixture was naturally cooled to room temperature under the protection of N2 to obtain black porous carbon fiber, which had obvious flexibility and elasticity when held.

[0166] The porous carbon fibers are cut to a certain length to maintain their fiber structure and self-supporting properties, then mixed evenly for later use. Maintaining the appropriate fiber length facilitates the formation of a network structure and improves the efficiency of subsequent activation treatments.

[0167] A small amount of the above fiber sample was taken for N2 isothermal adsorption and desorption characterization, and the BET specific surface area reached (1500±80)m 2 / g, with a total pore volume of (0.6±0.1) cm3 / g and an average pore diameter of 1.8nm. The pore size distribution is dominated by micropores (accounting for approximately 86%). The high specific surface area and rich multi-level pore structure are important prerequisites for achieving high silicon loading and rapid ion transport.

[0168] Step 300: SiH4 vapor deposition introduces silicon

[0169] 300 g of the porous carbon fiber prepared in step 200 was placed in a tubular vapor deposition furnace and evacuated to below 0.1 Pa.

[0170] Under the protection of 500 sccm of high-purity argon (Ar), the temperature was raised to 430°C at a rate of 10°C / min. After the temperature was maintained constant, 200 sccm of silane (SiH4) was introduced for chemical vapor deposition. At high temperatures, SiH4 diffuses and deposits on the inner walls of the carbon fiber channels, achieving uniform loading.

[0171] The SiH4 to Ar flow ratio was maintained at 1:4, with a total flow rate of 600 sccm, and the reaction was carried out for 10 hours. Compared with the H2S sulfidation in Example 1, the SiH4 cracking process requires more stringent control of temperature and flow rate, ensuring that the reaction proceeds completely while preventing excessive growth of silicon particles.

[0172] After the deposition is completed, the SiH4 is first turned off and the mixture is cooled naturally for 1 hour under Ar flow. Then, the mixture is vacuumed and cooled to room temperature to obtain a gray-brown silicon / carbon composite fiber. The carbon content measured by the carbon-sulfur analyzer is (55±3) wt%, based on which the silicon loading is calculated to be (45±3) wt%. The XRD test results are as follows: Figure 3 As shown, the product has an amorphous structure.

[0173] Step 400: C2H2 chemical vapor deposition carbon coating and composite coating

[0174] 200g of the silicon-deposited composite fiber was placed in a tube furnace, heated to 520°C under 500sccm Ar, and then introduced with 200sccm of acetylene (C2H2) for chemical vapor deposition of carbon coating. Using C2H2 as the carbon source allows for uniform deposition at lower temperatures, resulting in an amorphous coating.

[0175] Maintaining an Ar / C₂H₂ flow ratio of 5:2 and a total flow rate of 700 sccm for 5 hours, the composite fiber surface was coated with an amorphous carbon layer that seamlessly connected to the internal silicon particles and carbon skeleton, forming a "core-shell-skeleton" multi-level structure.

[0176] Prepare the composite coating solution: dissolve 0.4 g of single-walled carbon nanotubes (diameter <8 nm, aspect ratio >1000), 0.6 g of reduced graphene oxide (average size 200 nm, number of layers <5), 2 g of acetylene black, and 4 g of sodium carboxymethyl cellulose in 96 g of deionized water, and ultrasonically disperse for 2 h to obtain a uniform slurry.

[0177] The prepared fibers were immersed in a coating solution and stirred for 12 hours to fully wet the fibers, followed by vacuum drying at 100 degrees Celsius. The composite coating helps strengthen the conductive network, improving the fixation and conductivity of the silicon particles.

[0178] Forming and electrochemical performance testing

[0179] An appropriate amount of composite silicon / carbon fiber was placed in a Φ12 mm stainless steel mold and maintained at 120°C and 25 MPa for 10 min to obtain a disc electrode with a surface density of 1.5 mg / cm 2 , electrode thickness (65±4)μm.

[0180] A 2016-type button cell was assembled using a metallic lithium sheet as the counter electrode, Celgard 2325 as the separator, and 1M LiPF6 EC / DEC (1:1 v / v) as the electrolyte.

[0181] The battery's initial coulombic efficiency reached 93%, with initial discharge / charge specific capacities of (2420±10) mAh / g and (2250±10) mAh / g (based on the composite electrode mass), significantly higher than that of a graphite anode. After 100 cycles, the capacity retention rate was 99.3%, and the cyclic coulombic efficiency was >99.9%.

[0182] The prepared integrated electrode was used as the negative electrode, the lithium cobalt oxide electrode sheet as the positive electrode, and PEO-LiTFSI (EO:Li=9:1) as the solid electrolyte to form a monolithic soft-pack battery. Constant current charge and discharge tests were conducted at 65°C. The specific capacity reached 1950 mAh / g, and the initial coulombic efficiency reached 87%.

[0183] The resulting integrated electrode served as the positive electrode, and a flexible lithium metal foil supported on copper foil served as the negative electrode. A flexible liquid-filled soft-pack battery was assembled and subjected to constant-current charge-discharge testing during flexure. Before flexing, the specific capacity reached 2010 mAh / g, and after 100 180-degree bends, the capacity retention rate exceeded 93%.

[0184] Figure 5 Shown is the cycle capacity-voltage curve of the silicon-based integrated electrode prepared in Example 2 after being bent 180 degrees 100 times. As can be seen from the figure, even after repeated bending, the electrode still maintains good electrochemical properties, indicating that the integrated electrode has excellent mechanical flexibility and structural stability. In the figure, the horizontal axis represents capacity (Ah), the vertical axis represents voltage (V), and the curve shows the voltage change during the charge and discharge process. These results prove that the prepared silicon-based integrated electrode not only has a high specific capacity, but also has good flexibility, and is suitable for the field of flexible energy storage devices.

[0185] In summary, the silicon / carbon / carbon composite fiber electrode prepared in this embodiment has the following characteristics: (1) With a silicon loading of up to 45%, the lithium storage capacity is more than three times that of graphite; (2) The multi-level porous carbon fiber skeleton can buffer the volume expansion of silicon and maintain the stability of the electrode structure; (3) In-situ carbon coating and composite coating jointly improve the conductivity of silicon particles and inhibit side reactions at the solid-liquid interface; (4) The unique integrated structure gives the electrode excellent flexibility and mechanical strength. This electrode is expected to be used in high-energy-density, long-life, fast-charging lithium-ion batteries, especially flexible energy storage devices. The next step can focus on optimizing the silicon / carbon interface, improving the first efficiency and compaction density, etc., to further explore the application potential of electrode materials.

[0186] Example 3: Preparation of zinc-based integrated electrodes from asphalt-based fiber precursors

[0187] Raw material preparation

[0188] This embodiment uses high softening point asphalt-based fibers (abbreviated as HP fibers) produced by the Shanxi Coal Chemistry Research Institute of the Chinese Academy of Sciences, which have fiber diameter, carbon content, ash content, and length characteristics suitable for carbonization treatment. Waterborne polyurethane and cross-linked polyurethane are dissolved in deionized water in appropriate proportions and stirred evenly. For example, they are dissolved in 100 times the mass of deionized water at a molar ratio of 0.8:1 and stirred for 2 hours to prepare an impregnation solution. The HP fibers are immersed in the impregnation solution, ultrasonically treated at 40°C for 2 hours, and then taken out and dried for use. The total solid content of polyurethane in the sizing solution is about 10wt%, which is beneficial to improving the antioxidant properties of carbon fibers.

[0189] Step 100: Pre-oxidation and carbonization

[0190] 500g of sized HP fibers were placed in a roller kiln and pre-oxidized for 2 hours at 180°C with an air flow rate of 10 L / min. Compared to PAN-based fibers, HP fibers have a higher softening temperature, and the pre-oxidation starting temperature can be as low as 180°C, which helps maintain fiber morphology.

[0191] The pre-oxidized brown HP fibers were placed in a tubular carbonization furnace. The temperature was first raised to 450°C in a nitrogen atmosphere at a rate of 3°C / min and held for 1 hour to remove impurities. The temperature was then raised to 1100°C at a rate of 5°C / min and held for 2 hours to achieve high-temperature carbonization. High-temperature carbonization of HP fibers yields carbon fibers with a higher degree of graphitization and improved electrical conductivity.

[0192] After carbonization, the carbon fibers were cooled to room temperature in a furnace under nitrogen protection, yielding black HP-based carbon fibers. X-ray diffraction (XRD) analysis revealed an interlayer spacing (d002) of 0.338 nm, close to the theoretical value for graphite (0.335 nm), indicating a highly ordered carbon microcrystal structure. Raman spectroscopy revealed an IG / ID ratio of 1.2, further confirming the graphitization of the carbon fibers.

[0193] Step 200: Short-cut activation

[0194] HP-based carbon fibers are cut into short strands of about 5 mm and then shredded with a rotating blade to an average length of less than 100 μm to obtain carbon fibers. Shorter fibers are conducive to the uniformity of the subsequent activation reaction.

[0195] 300g of carbon fiber was placed in a fluidized bed reactor. After evacuation, 4L / min of high-purity nitrogen was introduced, and the temperature was raised to 1000°C at a rate of 10°C / min. The higher activation temperature significantly increases the specific surface area and introduces more micropores, providing more sites for the loading of metallic Zn.

[0196] Activation was performed for 8 hours by introducing 3 L / min of CO2 and 2 L / min of water vapor, respectively, maintaining a total gas flow rate of 5 L / min. HP carbon fibers are highly graphitized, requiring longer activation times to achieve a well-developed porous structure. The synergistic activation effect of CO2 and water vapor can enhance reaction efficiency and improve pore connectivity.

[0197] The activated gas was turned off and cooled to room temperature under N2 protection to obtain black porous HP carbon fiber with a bulk density of 0.15g / cm3. The BET specific surface area of ​​the carbon fiber was 2200m 2 / g, a total pore volume of 1.8cm3 / g, pore diameters between 0.8-4nm, and a micropore volume fraction of approximately 60%. This multi-level pore structure, with micropores as the main component and mesopores as the auxiliary component, is very conducive to metal loading.

[0198] Step 300: Zinc powder reduction load

[0199] 100g of the porous HP carbon fiber prepared in step 200 was thoroughly mixed with 100g of zinc powder (200 mesh, 99.99% purity), placed in a rotary kiln reactor, and heated to 920°C at a rate of 5°C / min under an Ar atmosphere. At this high temperature, the zinc powder melted and penetrated into the carbon pores due to capillary forces.

[0200] During the reaction at 920°C for one hour, Zn vapor continuously diffused into the carbon fibers, condensed, and deposited on the pore walls. Compared to the activation process, the mechanical stirring effect of the rotary kiln enhanced gas-solid mass transfer and improved the uniformity of Zn loading.

[0201] Maintaining a rotational speed of 10 r / min, the fiber was slowly cooled to 500°C at a rate of 1°C / min, then naturally cooled to room temperature and passed through a 100-mesh sieve to obtain a gray-black Zn / C composite fiber. The slow cooling process can induce the deposited Zn to fully crystallize, resulting in Zn particles of more uniform size.

[0202] Accurately weighed, the Zn loading was 58wt%, close to the stoichiometric ratio. Scanning electron microscopy revealed numerous Zn nanoparticles embedded within the carbon fiber pores, with particle sizes ranging from 50 to 100nm. High-resolution transmission electron microscopy combined with energy-dispersive spectroscopy confirmed a clear interface between the Zn particles and the carbon substrate, with uniform distribution and no apparent agglomeration. This is attributed to the confinement of Zn within the pores during the high-temperature reduction process.

[0203] Nitrogen adsorption and desorption tests showed that the specific surface area of ​​Zn / C composite fiber was 380 m 2 / g, total pore volume 0.4cm3 / g, and average pore diameter 3.2nm. Compared with activated carbon fibers, the significant reduction in specific surface area and pore volume further confirms the pore filling effect of Zn.

[0204] Step 400: Polypyrrole coating

[0205] Prepare the polymerization solution: dissolve 1.0 g of pyrrole monomer, 1.0 g of sodium dodecylbenzenesulfonate (SDBS), and 0.5 g of iron (III) p-toluenesulfonate (Fe-pTS) in 100 mL of deionized water, ultrasonically disperse for 30 min, and cool to below 5°C in an ice-water bath.

[0206] 50 g of the Zn / C composite fiber prepared in step 300 was added to the polymerization solution and magnetically stirred for 30 minutes to fully disperse the fiber.

[0207] 9 mL of 30% H₂O₂ was slowly added dropwise to adjust the pH to 2.0. The reaction system gradually changed from black to dark green and continued to react for 24 hours. Pyrrole oxidatively polymerized under the catalysis of Fe-pTS and in situ coated the surface of the Zn / C composite fiber. SDBS served as a dispersant and doping agent during the polymerization process, improving the conductivity of polypyrrole (PPy).

[0208] The black fibers, namely PPy-coated Zn / C composite fibers, were obtained by filtration, washing and drying. Thermogravimetric analysis estimated that the PPy coating content was approximately 5 wt%.

[0209] XPS analysis revealed a 4.2% nitrogen content on the composite fiber surface, primarily in the form of -NH-, confirming successful PPy coating. High-magnification electron microscopy revealed a 20nm-thick PPy film covering the fiber surface, exhibiting a typical core-shell structure. The PPy coating not only enhances the conductivity of the composite fiber but also effectively prevents Zn dissolution, improving the cycling stability of the electrode.

[0210] Forming and electrochemical testing

[0211] The PPy-coated Zn / C composite fiber was hot-pressed at 110°C and 25 MPa for 10 min to obtain a 12 mm Φ, 0.4 mm thick disc electrode with an area density of 3.2 mg / cm2 One-step molding can maximize the maintenance of the fiber interconnected structure and avoid the introduction of binders.

[0212] A button cell was assembled using a metal zinc sheet as the counter electrode, glass fiber as the separator, and a 3M Zn(TFSI)2 aqueous solution as the electrolyte.

[0213] 0.2C charge-discharge tests showed that the electrode achieved a first-cycle Coulombic efficiency of 92%, with an initial discharge / charge specific capacity of 805 / 742 mAh / g, respectively. After 50 cycles, the capacity retention reached 89%, with an average Coulombic efficiency of 99.7%. The PPy coating effectively inhibited Zn dissolution and dendrite growth, significantly improving the battery's cycle life.

[0214] At a high rate of 3C, the composite electrode still has a discharge capacity of 412 mAh / g, nearly twice that of a pure Zn electrode (220 mAh / g), demonstrating excellent rate performance. This is due to the efficient electron / ion transport channels constructed by the carbon fiber skeleton.

[0215] Immersion experiments confirmed that the morphology and size of the hot-pressed electrode did not change by more than 5% after being immersed in the electrolyte for one month, indicating that it has excellent structural stability, which is crucial for aqueous rechargeable batteries.

[0216] In this example, HP pitch-based carbon fibers were combined with Zn powder by high-temperature reduction to prepare a Zn / C composite electrode with high loading (58%) and high specific capacity (>800mAh / g). The in-situ coating of PPy not only improved the conductivity of the electrode but also inhibited the dissolution of Zn, significantly improving the cycling performance (89% after 50 cycles) and rate performance (412mAh / g at 3C) of the electrode. Subsequent research can further optimize the pyrrole polymerization process to improve the uniformity of the coating layer; or introduce other conductive polymers such as PANI and PEDOT to construct a multi-component composite coating to further improve the overall performance of the Zn electrode and accelerate its application in flexible energy storage and other fields.

[0217] Example 4: Preparation of MoS2-based Integrated Electrode from Phenolic Resin-based Fiber Protofilaments

[0218] Raw material preparation

[0219] This example uses phenolic resin-based carbon fibers (PF carbon fibers for short), which have fiber diameter, density, tensile strength, tensile modulus, and carbon content characteristics suitable for the process requirements of the present invention. The PF carbon fibers are continuously wound onto a square paper frame, with approximately 100 fibers per layer, stacked in 10 layers, and vacuum-dried at 60°C for 4 hours. Compared to polyacrylonitrile-based and asphalt-based carbon fibers, PF carbon fibers have superior mechanical properties and high-temperature resistance, but the cost of mass production is higher.

[0220] Step 100: Pre-oxidation and carbonization

[0221] The paper frame wrapped with PF fibers was placed in a heat treatment furnace and pre-oxidized for 2 hours at 180°C with an air flow rate of 1 L / min. Because PF resin already has a cross-linked structure, lowering the pre-oxidation temperature appropriately can reduce fiber surface defects.

[0222] After cooling to room temperature in the furnace, carefully remove the paper holder and lay the pre-oxidized brown PF fibers flat on a graphite boat. Place the fibers in a tubular carbonization furnace. First, heat the mixture to 700°C under an Ar atmosphere at a rate of 2°C / min, hold for 2 hours, then increase the temperature to 1000°C at a rate of 5°C / min and hold for 1 hour. This segmented carbonization facilitates the complete removal of heteroatoms within the PF macromolecular chain and the evolution of the carbon structure. Cool the furnace to room temperature to obtain black PF carbon fibers.

[0223] Step 200: Short-cut activation

[0224] A precision cutting machine is used to cut the PF carbon fiber into short shreds of about 10 mm, maintaining the self-supporting properties and network structure of the fiber.

[0225] Appropriately treated PF carbon fiber chopped strands were loaded into a quartz tube and placed in a tubular activation furnace. The temperature was raised to 1000°C at 5°C / min under 1 L / min of high-purity Ar. A mixture of 3 L / min of CO2 and 2 L / min of water vapor was introduced, and the temperature was raised to 1100°C for 6 hours. At this elevated temperature, CO2 reacts with carbon to form CO, which in situ reduces the surface oxygen groups generated during the activation process, contributing to a high specific surface area.

[0226] After cooling to room temperature and purging with N₂, a black porous PF carbon fiber network was obtained. N₂ adsorption analysis revealed a high specific surface area and a rich pore structure, with a significantly higher mesopore volume fraction than in Examples 1 and 2. This is attributed to the increased mesopore volume generated by water vapor activation. The developed multi-level pores facilitate rapid ion transport while maintaining the fiber's self-supporting properties.

[0227] Step 300 Load

[0228] Prepare ammonium molybdate solution: Dissolve 9.6 g of ammonium molybdate in 100 mL of deionized water. Heat to 80°C with magnetic stirring to clarify. After cooling, add 100 g of the porous PF carbon fiber prepared in step 200. Ultrasonic dispersion is performed for 3 hours. Vacuum dry at 60°C for 12 hours. During the drying process, (NH4)6Mo7O24 solidifies within the carbon pores, acting as a Mo precursor.

[0229] The fibers were placed in a quartz tube furnace. After evacuation, 1 L / min of high-purity Ar was introduced, and the temperature was raised to 800°C at 10°C / min. The protective gas was then switched to 1 L / min of 10% H2S / Ar, maintained at 1 L / min of Ar, and the temperature was raised to 850°C for 2 hours. The (NH4)6Mo7O24 in the nanopores underwent multi-step decomposition, reduction, and sulfidation to form molybdenum disulfide.

[0230] The fiber was cooled to room temperature, purged with Ar, and passed through a 100-mesh sieve to obtain a black MoS2 / C composite fiber. Thermogravimetric analysis showed that the residual MoO3 content after calcination at 1000°C in air was 49 wt%, based on which the MoS2 loading was estimated to be 58 wt%.

[0231] The XRD pattern showed no obvious peaks characteristic of MoS2, indicating that the MoS2 was amorphous or had a low level of crystallinity. The Raman spectrum showed weak E2g and A1g vibration peaks at 379 cm⁻¹ and 405 cm⁻¹, respectively. The frequency difference between the two peaks was approximately 26 cm⁻¹, confirming the successful loading of 2H-phase MoS2.

[0232] A large number of MoS2 crystals smaller than 2 nm were observed under high-resolution transmission electron microscopy, indicating that MoS2 was embedded in the pores without forming large-sized crystals. The specific surface area of ​​MoS2 / C composite fibers is 96 m 2 / g, which is much lower than that of activated carbon fiber, indicating the filling effect of molybdenum disulfide on the pores.

[0233] Step 400 Composite coating

[0234] Prepare the LLZTO coating solution: Add 10g of LLZTO powder, 0.4g of acetylene black, and 0.6g of sodium carboxymethyl cellulose to 90g of anhydrous ethanol and stir magnetically for 6 hours until uniformly dispersed. LLZTO acts as a solid electrolyte, acetylene black improves conductivity, and sodium carboxymethyl cellulose acts as a binder.

[0235] 50 g of the Mo / C composite fiber prepared in step 300 was added to the LLZTO coating solution, ultrasonically dispersed for 2 h, filtered, and vacuum dried at 80° C. for 10 h. After drying, the LLZTO content in the fiber was approximately 10 wt%.

[0236] The fibers were formed into 50 mm Φ and 300 μm thick electrode felt discs using a vacuum papermaking machine. The discs were then dried at 120°C for 2 hours to remove any residual solvent. This papermaking method produces a uniform, porous electrode structure, which facilitates electrolyte infiltration.

[0237] The electrode felt was hot pressed at 160°C and 10 MPa for 10 min to obtain a dense MoS2 / C / LLZTO composite electrode with a thickness of about 190 μm and an area density of 2.1 mg / cm 2Hot pressing densification can improve the surface density and conductivity of the electrode, but the temperature should not be too high to avoid oxidation or denaturation of the material.

[0238] Electrochemical performance test

[0239] The prepared composite electrode was used as the positive electrode, the metal lithium sheet was used as the negative electrode, 1M LiPF6 EC / DEC electrolyte, and Celgard2400 separator were assembled into a 2025 type button battery.

[0240] During the first charge and discharge cycle at a 0.1C rate, the electrode achieved a high specific capacity of 890 mAh / g and a Coulombic efficiency of 82%. After 50 cycles, the capacity remained at 756 mAh / g, with a capacity retention rate of 85%, significantly superior to the uncoated MoS2 / C electrode (574 mAh / g, 64%). The LLZTO solid electrolyte layer effectively isolates MoS2 from direct contact with the liquid electrolyte, suppressing the shuttle effect and volume expansion.

[0241] Figure 6 Shown are the rate performance test results of the molybdenum disulfide-based integrated electrode prepared in Example 4. As can be seen from the figure, the charge and discharge performance changes of the electrode at different rates. Specifically, at different rates such as 0.1C, 0.2C, 0.5C, 1C and 2C, the electrode specific capacity is 762, 652, 566, and 480mAh / g, respectively, which are more than 2-3 times that of pure molybdenum disulfide electrodes. These data show that the prepared molybdenum disulfide-based integrated electrode has excellent rate performance and can maintain a high specific capacity even at high rates. This excellent electrochemical performance is mainly due to the synergistic effect of the carbon fiber skeleton and the LLTO solid electrolyte coating, which together provide an efficient channel for lithium ion transport.

[0242] The Li+ diffusion coefficient of the MoS2 / C / LLZTO electrode measured by the constant current intermittent titration technique (GITT) is as high as 2.1×10-10cm 2 / s, which is nearly one order of magnitude higher than that of pure MoS2 electrode, indicating that the composite electrode has better kinetic properties.

[0243] The prepared electrodes were used to assemble soft-pack lithium-ion batteries. After 200 cycles at a 0.5C rate, the capacity retention rate was 81%, much higher than that of the uncoated electrode (56%). This is due to the effective protection of the LLZTO solid electrolyte layer on the electrode material.

[0244] In summary, this embodiment uses high-strength PF carbon fiber as the skeleton, introduces molybdenum disulfide through high-temperature vulcanization, and coats the surface with LLZTO solid electrolyte to construct a "core-shell-skeleton" multi-level structure composite electrode. The prepared electrode has the characteristics of high specific capacity (890mAh / g), excellent rate performance (2C 480mAh / g) and long cycle life (81% after 200 times). The LLZTO solid electrolyte not only significantly improves the interface stability and Li+ migration kinetics, but also gives the electrode a certain flexibility, showing good application prospects in the field of flexible energy storage. Future research can focus on optimizing the pore structure, developing new solid electrolyte coatings (such as sulfides, polymers, etc.), and in-depth understanding of the solid-solid interface evolution mechanism to further improve the comprehensive performance of the electrode. At the same time, it is also necessary to explore more economical, environmentally friendly, and scalable preparation processes to accelerate its industrialization process.

[0245] To further illustrate the technical solution of this application, several specific examples are listed below. It should be noted that these examples are optimizations and improvements based on the above-mentioned implementation methods. Their purpose is to highlight the unique advantages of this application in terms of raw material selection, process parameter control, product performance, etc. through more experimental data and comparative analysis. At the same time, these examples also demonstrate the universality and scalability of the method of this application. That is, by adaptively adjusting key steps, a variety of integrated electrodes can be prepared to meet different application requirements. The preparation process and performance characterization results of these examples will be described in detail below so that those skilled in the art can implement this application accordingly.

[0246] Example 5: Simplified process of sulfur-based integrated electrode

[0247] Dissolve waterborne polyurethane and waterborne polyurethane curing agent in 100 times the mass of water at a molar ratio of 1:1.1 and stir evenly to form a uniform sizing solution. Soak 1 kg of polyacrylonitrile fiber precursor in the sizing agent, dry it at 110°C, and laser-cut it into fibers with an average length of 65 mm. Then, pre-oxidize it at 200°C for 4 hours. Then, introduce nitrogen into the reactor at a rate of 5 L / min. After the air in the reactor is exhausted, heat it to 600°C and carbonize it for 2 hours to obtain carbonized fiber filaments.

[0248] 1 kg of the obtained carbonized fiber was placed in an activation furnace, heated to 900°C under the protection of nitrogen at 5 L / min, and then activated by CO2 at a rate of 5 L / min for 5 h. After cooling, porous fiber was obtained.

[0249] 500 g of the obtained porous fiber filaments were placed in a tubular furnace, heated to 400°C under the protection of 2 L / min nitrogen and introduced 0.1 L / min ammonia for reaction for 1 hour, then heated to 700°C, and introduced H2S gas at a rate of 1 L / min for 5 hours to obtain sulfur-containing active fiber filaments; the introduction of H2S gas was stopped and the nitrogen flow rate was changed to 3 L / min, the temperature was raised to 980°C, and then CH4 gas was introduced at a rate of 1 L / min for 2 hours. After cooling, the fiber was hot pressed at 170°C and 20 MPa pressure to obtain a sulfur-based integrated electrode.

[0250] Example 6: Silicon-based integrated electrode with simplified process

[0251] Dissolve waterborne polyurethane and waterborne polyurethane curing agent in 100 times the mass of water at a molar ratio of 1:1.1 and stir evenly to form a uniform sizing solution. Soak 1 kg of polyacrylonitrile fiber precursor in the sizing agent, dry it at 110°C, and laser-cut it into fibers with an average length of 110 mm. Then, pre-oxidize it at 200°C for 4 hours. Then, introduce nitrogen into the reactor at a rate of 5 L / min. After the air in the reactor is exhausted, heat it to 600°C and carbonize it for 2 hours to obtain carbonized fiber filaments.

[0252] 1 kg of the obtained carbonized fiber was placed in an activation furnace, heated to 900°C under the protection of nitrogen at 5 L / min, and then activated by CO2 at a rate of 5 L / min for 5 h. After cooling, porous fiber was obtained.

[0253] 500g of the obtained porous fiber was placed in a tube furnace and heated to 430°C under the protection of 2L / min nitrogen. SiH4 gas was introduced at a rate of 1L / min for 10 hours to obtain silicon-containing active fiber. The introduction of SiH4 gas was stopped and the nitrogen flow rate was changed to 3L / min. The temperature was raised to 520°C, and then C2H2 gas was introduced at a rate of 1L / min for 10 hours. After cooling, the fiber was immersed in a composite coating agent and filtered out (the weight ratio of the composite coating agent components is: 0.4% single-walled carbon nanotubes, 0.6% few-layer graphene, 2% acetylene black, 4% sodium carboxymethyl cellulose, 3% sodium polyacrylate, and 90% water). The silicon-based integrated electrode was obtained by hot pressing at 120°C and 20MPa pressure.

[0254] Example 7: Simplified process zinc-based integrated electrode

[0255] Dissolve waterborne polyurethane and waterborne polyurethane curing agent in 100 times the mass of water at a molar ratio of 0.8:1 and stir evenly to form a uniform sizing agent solution. Soak 1 kg of asphalt-based fiber precursor in the sizing agent and then dry it at 110°C. Laser cut it into fibers with an average length of 10 mm, and then pre-oxidize it at 200°C for 4 hours. After that, introduce nitrogen into the reactor at a rate of 5 L / min. After the air in the reactor is exhausted, heat it to 600°C and carbonize it for 2 hours. After cooling, use a rotary knife to cut and a jet mill to crush the fibers into carbonized fiber short filaments less than 100 μm in length.

[0256] 1 kg of the obtained carbonized fiber filaments were placed in an activation furnace and heated to 1000°C under the protection of nitrogen at 5 L / min. Then, CO2 and water vapor were introduced at the speeds of 3 L / min and 2 L / min respectively for activation for 5 h. After cooling, porous fiber filaments were obtained.

[0257] 500 g of the obtained porous fiber and 500 g of high-purity zinc powder were placed in a rotary furnace at a speed of 15 Hz. The temperature was raised to 920°C and maintained for 1 h under the protection of nitrogen at a flow rate of 1 L / min. The temperature was then lowered to room temperature at a rate of 2°C / min to obtain zinc-containing active fiber.

[0258] Pyrrole monomer was dissolved in an ethanol-water solution (volume ratio of 1:1) to obtain 1 L of a 1 wt% pyrrole solution. The resulting zinc-containing active fiber was immersed in the pyrrole solution, and the solution temperature was controlled at 0°C. 50 mL of a 1 mol / L aqueous ammonium persulfate solution was slowly added dropwise and stirred for 24 hours. The polypyrrole-coated zinc-containing active fiber was filtered out and washed with ethanol. The solution was then hot-pressed at 90°C and 20 MPa to obtain a zinc-based integrated electrode.

[0259] Example 8: Simplified process of molybdenum disulfide-based integrated electrode

[0260] 1 kg of phenolic resin fiber precursor was laser cut into fibers with an average length of 65 mm and then pre-oxidized at 180°C for 2 hours. Nitrogen was then introduced into the reactor at a rate of 5 L / min. After the air in the reactor was exhausted, the temperature was raised to 700°C and carbonized for 2 hours. After cooling, the fibers were cut with a rotary knife and pulverized with an airflow mill to form carbonized fiber filaments less than 100 μm in length.

[0261] 1 kg of the obtained carbonized fiber filaments were placed in an activation furnace and heated to 1000°C under the protection of nitrogen at 5 L / min. Then, CO2 and water vapor were introduced at the speeds of 3 L / min and 2 L / min respectively for activation for 5 h. After cooling, porous fiber filaments were obtained.

[0262] 500 g of the obtained porous fiber staples and 200 g of ammonium molybdate were placed together in 10 L of water, stirred for 24 hours, filtered and dried to obtain porous fiber staples adsorbed with ammonium molybdate. 500 g of the porous fiber staples adsorbed with ammonium molybdate were placed in a rotary kiln at a speed of 15 Hz, heated to 800°C under a nitrogen atmosphere at a rate of 1 L / min, and H2S gas was introduced at a rate of 1 L / min for 2 hours. After cooling, active fiber staples containing molybdenum disulfide were obtained.

[0263] 10g of LLZTO solid electrolyte was mixed evenly with 90g of a composite coating agent (the weight ratio of the composite coating agent components was: 0.4% single-walled carbon nanotubes, 0.6% few-layer graphene, 2% acetylene black, 4% sodium carboxymethyl cellulose, 3% sodium polyacrylate, and 90% water). Molybdenum disulfide-containing active fiber short filaments were made into a 200μm thick fiber membrane using a papermaking method. 100g of the above fiber membrane was immersed in the LLZTO-containing composite coating agent and then removed and hot-pressed at 110°C and 20MPa to obtain a molybdenum disulfide-based integrated electrode.

[0264] The above embodiments have the following technical effects:

[0265] The above embodiment provides an integrated electrode with a clear preparation process and excellent electrochemical performance and its preparation method. Compared with the existing technology, this invention has the following significant advantages and technical effects:

[0266] The carbonized fiber skeleton obtained by pre-oxidation and high-temperature carbonization treatment has excellent conductivity, chemical stability and mechanical strength, and can provide efficient electron transmission pathways and structural support for electrodes.

[0267] A developed porous structure is constructed through activation treatment, and the BET specific surface area can reach 100-3000m 2 / g, pore volume of 0.1-2.0cm 3 / g, with an average pore size of 0.8-50nm, which provides ample space for the loading of active substances and forms an efficient ion transmission channel.

[0268] The vapor deposition method achieves the effective loading of active substances (such as phosphorus, sulfur, silicon, zinc, lithium, sodium, potassium, and molybdenum disulfide) within the carbon fiber pores. The active material loading amount can be controlled within the range of 1-95% mass increase, which not only ensures sufficient capacity but also maintains excellent mechanical strength, effectively alleviating the problem of volume change during charging and discharging.

[0269] The interface structure of the electrode is further optimized by coating with carbon, conductive polymers or solid electrolytes, which improves the electronic / ionic conductivity performance. At the same time, the active materials are protected from direct contact with the electrolyte, reducing side reactions and improving the coulombic efficiency and cycle stability of the battery.

[0270] Self-supporting integrated electrodes prepared by processes such as hot pressing, needle punching, weaving or papermaking do not require additional current collectors and binders, simplifying the battery assembly process and improving the overall energy density.

[0271] The prepared integrated electrodes exhibit excellent electrochemical energy storage performance. For example, the sulfur-based electrode achieved an initial discharge capacity of 1250 mAh / g at a 0.5C rate, and after 50 cycles, the capacity retention rate reached 82%, significantly superior to conventional coated electrodes. For example, the silicon-based electrode achieved an initial discharge capacity of 2250 mAh / g at a 0.2C rate, an initial coulombic efficiency of 93%, and a capacity retention rate of 99.3% after 100 cycles, far superior to conventional silicon-based electrodes.

[0272] The process steps of the above embodiments cooperate with each other to form a systematic preparation method, which can optimize the process parameters of each step for different types of energy storage batteries and has good universality and scalability.

[0273] In summary, the above embodiments construct a new integrated electrode with stable structure and excellent electrochemical performance through the synergistic effect of the porous structure design of the carbon fiber skeleton, the vapor deposition loading of the active material and the surface protection coating. It effectively overcomes the defects of the traditional electrode manufacturing process such as the easy separation of the active material from the current collector and the complex engineering control, and realizes the simple preparation of high-performance energy storage battery electrodes, which is of great significance to promoting the development of high-energy density and long cycle life energy storage equipment.

[0274] Figure 2 The following scanning electron microscope image shows the sulfur-based integrated electrode prepared in Example 1. The following key features can be observed from the image:

[0275] The electrode as a whole presents a fibrous network structure, which is a carbonized fiber skeleton formed by pre-oxidation, carbonization and activation of polyacrylonitrile precursor.

[0276] The fiber diameter is in the range of 10-20 microns, which corresponds to the mentioned carbon fiber filament sizes (1-50 microns, preferably 5-30 microns).

[0277] The fibers are interwoven to form a three-dimensional network, which provides good mechanical support performance, and is the structural basis for realizing self-supporting integrated electrodes.

[0278] The overall structure is tight and well-connected, a result of the hot pressing process, which improves the flatness, uniformity and density of the electrodes.

[0279] This microstructure demonstrates the technical effect of the method of this application - through multi-step processing, the effective combination of sulfur active substances and carbon fiber skeleton is achieved, forming a self-supporting integrated electrode without the need for a binder. This structure is conducive to overcoming the performance degradation problem of traditional sulfur electrodes caused by volume changes during charging and discharging.

[0280] It should be noted that in the application documents of this application, relational terms such as first and second are merely used to distinguish one entity or operation from another, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprise," "include," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article, or device. Without further restriction, an element defined by the phrase "comprising a" does not exclude the presence of other identical elements in the process, method, article, or device comprising the element. In the application documents of this application, if it is mentioned that an action is performed according to a certain element, it means that the action is performed at least according to that element, including two situations: performing the action only according to that element, and performing the action according to that element and other elements. Expressions such as "multiple," "multiple," and "multiple" include "two," "twice," "two kinds," and "more than two," "more than two times," and "more than two kinds."

[0281] All documents mentioned in this application are considered to be included in their entirety in the disclosure of this application so that they can be used as a basis for modification when necessary. In addition, it should be understood that after reading the above disclosure of this application, those skilled in the art may make various changes or modifications to this application, and these equivalent forms also fall within the scope of protection claimed in this application.

Claims

1. A method for preparing an integrated electrode, characterized in that: The following steps are involved: S1, pre-oxidizing, carbonizing, and cutting fiber precursors to obtain carbonized fiber filaments; S2, activating the carbonized fiber filaments to obtain porous fiber filaments; S3, combining the porous fiber filaments with an energy storage battery electrode active material that can be combined by a vapor deposition reaction to obtain active fiber filaments; S4, coating the active fiber filaments with a conductive and / or ion-conducting coating material to obtain an integrated electrode; wherein the integrated electrode can form a film by itself when applied to an energy storage battery.

2. The method for preparing an integrated electrode according to claim 1, wherein: In S1, the fiber precursor is selected from the following fibers: natural fibers, chemical fibers, inorganic fibers, biomass-based fibers, and composite fibers; wherein the natural fibers include cellulose-based fibers such as cotton and linen, and animal fibers such as hair and silk; the chemical fibers include resin-based fibers, asphalt-based fibers, conductive polymer fibers, adhesive fibers, high-performance aramid fibers, and polyacrylonitrile-based, petroleum coke-based, asphalt-based, and phenolic resin-based fibers; the inorganic fibers include carbon-based fibers such as carbon fiber, carbon nanotube fibers, and graphene fibers; the biomass-based fibers include polylactic acid fibers, chitin fibers, and bacterial silk fibers; and the diameter of the carbonized fiber filaments (CFF) is 1-50 μm. In S2, the BET specific surface area of ​​the porous fiber is 100-3000m 2 / g, pore volume of 0.1-2.0cm 3 / g, average pore size is 0.8-50nm; In S3, the vapor deposition reaction temperature is 280-1100° C., and the porous fiber pores are pre-filled with reaction raw materials by an impregnation method before the vapor deposition reaction; In S4, the reaction temperature used for the coating treatment is lower than the boiling point of the active material contained in the active fiber to avoid the loss of the active material. The specific surface area of ​​the obtained integrated electrode is 0.5-100m 2 / g.

3. The method for preparing an integrated electrode according to claim 1, wherein: The energy storage battery electrode active material is one or more of phosphorus, sulfur, silicon, zinc, lithium, sodium, potassium, and molybdenum disulfide.

4. The method for preparing an integrated electrode according to claim 1, wherein: The conductive and / or ion-conducting coating material is one or more of carbon, conductive polymer, and solid electrolyte.

5. The method for preparing an integrated electrode according to claim 1, wherein: In S2: The activation temperature is 850-1100°C, the activation time is 2-10h, the activation atmosphere is a mixture of activation gas and inert gas, the activation gas is one or a mixture of carbon dioxide, water vapor, and oxygen, and the inert gas is one or a mixture of nitrogen and argon; or, Potassium hydroxide activator is used instead of activation gas or to assist activation, and the ratio of potassium hydroxide to carbonized fiber filament is 1:1 to 5:

1.

6. The method for preparing an integrated electrode according to claim 1, wherein: In S3, the vapor deposition reaction is physical vapor deposition or chemical vapor deposition, and the reaction apparatus is a tubular furnace, a rotary furnace or a fluidized bed reactor.

7. The method for preparing an integrated electrode according to claim 1, wherein: In said S3, the reaction atmosphere is composed of reaction gas, auxiliary gas and inert gas, wherein the reaction gas accounts for 2-90% of the total volume, the auxiliary gas accounts for 0-10% of the total volume, and the inert gas accounts for 10-98% of the total volume.

8. The method for preparing an integrated electrode according to claim 4, wherein: In S4, when the coating material is carbon, one of the following methods is adopted: chemical vapor deposition coating method, the gas introduced is a mixture of carbon-containing gas and inert gas, the reaction temperature of the vapor deposition equipment is 350-1100°C, and the carbon coating amount is 1-10% of the electrode mass; or liquid phase coating method, the liquid phase coating solvent is one of water, ethanol, acetone, and toluene, and the coating agent is phenolic resin or asphalt.

9. The method for preparing an integrated electrode according to claim 4, wherein: In S4, when the coating material is a solid electrolyte, an in-situ polymerization method, a sol-gel method or a solution coating method is adopted, and the solid electrolyte is one or more of an oxide solid electrolyte, a sulfide solid electrolyte, a halide solid electrolyte, a polymer solid electrolyte or a composite semi-solid electrolyte.

10. The method for preparing an integrated electrode according to claim 1, wherein: In S4, the coated integrated electrode is post-processed by one of the following methods: mechanical compaction, isostatic compaction or hot pressing process to improve flatness, uniformity and density; or needle punching, weaving or papermaking to obtain an electrode with a specific fiber structure.

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