A selenium-loaded amorphous carbon film modified carbon cloth current collector and a preparation method and application thereof

Abstract

This invention provides a carbon cloth current collector modified with a selenium-loaded amorphous carbon film, its preparation method, and its application, relating to the field of lithium metal battery technology. The preparation method involves a one-step pyrolysis process, coating a precursor solution containing aromatic cyclic selenium organic matter and phenolic resin onto carbon cloth, followed by high-temperature carbonization, forming a tightly bonded, smooth selenium-loaded amorphous carbon film on the carbon cloth surface. In this invention, the carbon cloth current collector modified with the selenium-loaded amorphous carbon film forms a high-density three-dimensional carbon framework through the carbonization of the aromatic cyclic selenium organic matter. The selenium component is stabilized by Se-C covalent bonds, and the π-π conjugation effect strengthens the interfacial bonding between the film layer and the carbon cloth. It possesses both high conductivity and lithium affinity, effectively suppressing lithium nucleation overpotential and lithium dendrite growth. Simultaneously, the three-dimensional porous structure of the carbon cloth alleviates volume expansion. When used as a negative electrode in lithium metal batteries, it effectively solves the problems of dendrite short circuits and volume expansion in lithium metal batteries, significantly improving the long-cycle stability and safety of the battery.

Description

Technical Field

[0001] This invention relates to the field of lithium metal battery technology, and in particular to a carbon cloth current collector modified with a selenium-loaded amorphous carbon film, its preparation method, and its application. Background Technology

[0002] Lithium metal batteries have an extremely high theoretical specific capacity (3860 mAh·g). -1 ) and lowest electrochemical potential (-3.04V) vs. SHE Lithium is widely recognized as the core choice for next-generation high-energy-density energy storage systems, with broad application prospects in electric vehicles, portable electronic devices, and large-scale energy storage. However, two key problems in lithium metal cycling severely restrict its commercialization: first, the disordered growth of lithium dendrites leads to the risk of internal short circuits in the battery; second, the dramatic volume expansion during lithium deposition / stripping can damage the integrity of the electrode structure, ultimately causing rapid capacity decay, electrolyte depletion, and safety hazards.

[0003] To address the aforementioned issues, constructing three-dimensional current collectors with high specific surface area and spatial buffering capacity has proven to be an effective way to induce uniform lithium deposition. Carbon cloth, due to its excellent conductivity, chemical stability, and three-dimensional porous structure, has become one of the ideal substrates for lithium metal battery current collectors. However, pure carbon cloth has insufficient lithiophilicity, a high nucleation overpotential, and weak interfacial interactions with the active material, resulting in uneven lithium deposition and limited dendrite suppression, failing to meet the requirements for long-cycle stability.

[0004] Existing technologies typically employ surface functionalization modifications of carbon cloth to improve its properties. Currently, research on surface functionalization modifications of carbon cloth mainly focuses on particle loading modification strategies, and related reports have formed a large-scale research system. Researchers introduce various functional particles, including carbon-based particles, metal / metal oxide particles, and porous material particles, into the surface of carbon cloth through methods such as physical deposition, chemical grafting, and in-situ growth, aiming to optimize the lithiophilicity and interfacial properties of carbon cloth through the physical occupancy and chemical interaction of the particles.

[0005] However, the inventors' research revealed that existing particle loading modification methods for carbon cloth still have the following technical problems: insufficient bonding force between the loaded particles and the carbon cloth; poor uniformity of the distribution of loaded particles on the carbon cloth surface, resulting in an uneven surface of the modified layer; and poor interface uniformity between the loaded particles and the carbon cloth. Specifically, after functional modification of the carbon cloth, the particles are in a dispersed loading form, resulting in poor bonding between the loaded particles and the carbon cloth matrix and easy detachment. While they can form a certain degree of physical occupancy on the carbon cloth surface, they cannot construct a smooth surface structure, leading to an uneven interface state and difficulty in forming a continuous and uniform functional modified film. These problems directly result in poor current collector interface stability and poor interface contact, thus significantly reducing the cycle stability and lifespan of the battery. Summary of the Invention

[0006] To address the technical problems existing in the prior art, this invention provides a carbon cloth current collector modified with a selenium-loaded amorphous carbon film, its preparation method, and its application. Through a simple one-step pyrolysis method, a tightly bonded and smooth selenium-loaded amorphous carbon film is formed on the carbon fiber surface of the carbon cloth, resulting in a carbon cloth current collector modified with a selenium-loaded amorphous carbon film. This effectively avoids the defects of existing particle loading modification methods for carbon cloth, and can effectively improve the interface stability and working stability of the current collector, as well as significantly improve the cycle stability and service life of lithium metal batteries, while inducing uniform lithium deposition and suppressing lithium dendrites.

[0007] To solve the above technical problems, the technical solution adopted by the present invention is as follows: A method for preparing a carbon cloth current collector modified with a selenium-loaded amorphous carbon film includes the following steps: dissolving an aromatic ring-containing selenium organic compound and phenolic resin in acetone, stirring until homogeneous to obtain a homogeneous precursor solution; immersing the carbon cloth in the precursor solution after washing and annealing, allowing it to stand for immersion, removing it and drying it, and then heat-treating it in an inert atmosphere to obtain a carbon cloth current collector modified with a selenium-loaded amorphous carbon film. The aromatic ring-containing selenium organic compound is one of the following: methyl phenyl selenide, diphenyl selenide, or di-p-toluene selenide.

[0008] Preferably, the mass ratio of the aromatic ring-containing selenium organic compound, phenolic resin, and acetone is 0.55-0.60:1:10.

[0009] Preferably, the annealing treatment is carried out in an inert atmosphere at 300-320°C for 1-1.5 hours.

[0010] Preferably, the volume ratio of carbon cloth to precursor liquid is 1:55-75.

[0011] Preferably, the temperature for static immersion is room temperature, and the immersion time is 1-2 hours.

[0012] Preferably, the heating rate of the heat treatment is 3-5℃ / min, the heat treatment temperature is 500-540℃, and the heat treatment time is 5-7h.

[0013] A carbon cloth current collector modified with a selenium-loaded amorphous carbon film prepared by the aforementioned method includes: a carbon cloth current collector fiber matrix; The surface of the fibers in the carbon cloth current collector fiber matrix is ​​coated with an amorphous carbon layer. The amorphous carbon layer is loaded with Se nanoparticles, and the Se nanoparticles are covalently connected to the carbon atoms of the amorphous carbon layer.

[0014] Application of the aforementioned selenium-loaded amorphous carbon film-modified carbon cloth current collector in the preparation of lithium metal batteries.

[0015] A lithium metal battery, comprising: a composite lithium metal anode; The method for preparing the composite lithium metal anode is as follows: in an inert atmosphere, the aforementioned carbon cloth current collector modified with selenium-loaded amorphous carbon film is placed in an inert crucible, and then a lithium metal sheet is placed on top of the carbon cloth current collector modified with selenium-loaded amorphous carbon film. The temperature is raised to 200°C and held until the lithium metal sheet is completely melted. After cooling, the composite lithium metal anode is obtained.

[0016] Preferably, in the preparation of the composite lithium metal anode, the weight ratio of the lithium metal sheet to the carbon cloth current collector modified with selenium-loaded amorphous carbon film is controlled to be 1:1.5-1.8.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1) In the carbon cloth current collector modified with selenium-loaded amorphous carbon film prepared in this invention, the selenium-loaded amorphous carbon film has a uniform and smooth surface. This smooth structure benefits from the precise construction of Se-C covalent bonds, the structural advantages of the precursor, and the film-forming and framework support of phenolic resin. It fundamentally solves the problems of poor interface uniformity and difficulty in forming continuous and uniform functional film layers in particle loading modification: On the one hand, selenium and carbon matrix achieve atomic-level anchoring through stable Se-C covalent bonds, avoiding interfacial voids and component agglomeration caused by physical mixing. At the same time, the aromatic cyclic selenium organic precursor has a regular molecular structure, and phenolic resin has excellent leveling and film-forming properties, which can be applied to carbon... Before carbonization, a continuous and dense precursor film is formed, which effectively fills the interfacial gaps and inhibits component segregation. During high-temperature carbonization, it works with selenium organic matter to achieve uniform growth of the carbon skeleton and uniform dispersion of selenium atoms, eliminating local protrusions and defects, and forming a continuous smooth film with uniform thickness and extremely low roughness. This overcomes the defect that particles cannot physically occupy the site to build a smooth surface. On the other hand, this uniform and smooth film surface can inhibit the preferential growth of lithium dendrites at defects, induce uniform and dense deposition of lithium ions, eliminate the risk of dendrite short circuits, and at the same time, the dense selenium-loaded amorphous carbon film can act as an artificial SEI layer to buffer volume expansion. With uniform stress distribution, it significantly improves the stability of the electrode structure.

[0018] 2) The aromatic ring selenium organic precursor and phenolic resin composite system selected in this invention have three core advantages, specifically solving the technical bottlenecks of insufficient binding force of particle loading modification, loose interfacial bonding and easy detachment, uneven surface and poor interfacial uniformity: ① The highly conjugated regular structure of the aromatic ring and the cross-linking film-forming characteristics of the phenolic resin work synergistically to form a high-density and high-stability three-dimensional carbon skeleton after carbonization, which greatly improves the carbon yield and provides a structural basis for the uniform dispersion of selenium atoms, avoiding film surface defects caused by uneven growth of carbon matrix and improving the problem of poor interfacial uniformity; ② The Se-C bond cleavage in the precursor is controllable and can be precisely formed. Stable covalent bonds are formed, which anchor selenium atoms uniformly in the carbon skeleton. The continuous carbon matrix formed by phenolic resin further constrains the distribution of selenium components, which not only avoids the surface protrusion caused by selenium agglomeration, loss and local enrichment, but also inhibits the dissolution of polyselenoides and improves cycle stability; ③ Aromatic rings form a strong π-π conjugation effect with the carbon fiber surface. After the phenolic resin is cured, it forms a strong chemical bond and interface wetting with the carbon fiber, which makes the selenium-loaded amorphous carbon film and carbon cloth substrate have a much stronger interface adhesion than traditional physical bonding. This solves the problem of poor bonding between particles and the matrix and easy detachment and cracking during cycling, and continuously maintains the smoothness of the film surface and the integrity of the electrode structure.

[0019] 3) In the carbon cloth current collector modified with selenium-loaded amorphous carbon film of the present invention, the three-dimensional porous structure of the carbon cloth and the modification with selenium-loaded amorphous carbon film form a synergistic effect, and the uniform and smooth characteristics of the film further amplify this synergistic advantage: the three-dimensional porous structure of the carbon cloth not only provides sufficient lithium deposition space and alleviates the pressure of volume expansion, but also expands the electrode / electrolyte contact area and improves ion transport efficiency; the lithiophilic modification of the selenium-loaded amorphous carbon film (derived from the lithiophilic properties and uniform distribution of Se element) further reduces the lithium nucleation energy barrier, and combined with the high conductivity of the carbon cloth itself, effectively reduces the charge transfer resistance of the current collector; while the uniform and smooth surface of the film makes lithium ion deposition more uniform, avoiding uneven volume expansion caused by excessive local deposition, combined with the mechanical flexibility and chemical stability of the carbon cloth, and the strong adhesion of the selenium-loaded amorphous carbon film, the modified carbon cloth current collector still maintains structural integrity after long cycle, without fiber breakage or film peeling, significantly improving the long cycle reliability of the battery - at a 1.0C rate, the capacity retention rate can reach more than 85% after 500 cycles.

[0020] 4) The method for preparing the carbon cloth current collector modified with selenium-loaded amorphous carbon film of the present invention adopts a one-step heating method to complete the preparation of selenium-loaded amorphous carbon film and carbon cloth modification, without the need for complex pretreatment, multi-step loading or post-treatment processes: This process simultaneously achieves precursor carbonization, Se-C covalent bond formation and uniform film deposition through a single high-temperature process, avoiding problems such as uneven film thickness and surface defects caused by multi-step processes, and further ensuring the uniform and smooth characteristics of the composite film; Compared with the traditional multi-step preparation method, this process has simple equipment requirements, streamlined operation process, and significantly reduced unit cost in large-scale production, and has good prospects for industrial application. Attached Figure Description

[0021] Figure 1 The image shows a SEM image of the carbon cloth current collector modified with a selenium-loaded amorphous carbon film prepared in Example 1.

[0022] Figure 2 Mapping diagram of the carbon cloth current collector modified with selenium-loaded amorphous carbon film prepared in Example 1.

[0023] Figure 3 The energy spectrum of the carbon cloth current collector modified with selenium-loaded amorphous carbon film prepared in Example 1 is shown.

[0024] Figure 4 SEM image of the selenium-loaded carbon cloth current collector prepared for Comparative Example 1. Figure 5 SEM image of the selenium-loaded carbon cloth current collector prepared for Comparative Example 2. Figure 6 SEM image of the selenium-loaded carbon cloth current collector prepared for Comparative Example 3.

[0025] Figure 7The graph shows a comparison of the cycle performance of symmetric batteries made from the materials prepared in Example 1 and Comparative Example 1.

[0026] Figure 8 The graph shows a comparison of the cycle performance of lithium metal batteries made from the materials prepared in Example 1 and Comparative Example 1. Detailed Implementation

[0027] To provide a clearer understanding of the technical features, objectives, and effects of this invention, specific embodiments are now described. It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0028] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. As used herein, "first," "second," etc., are used to distinguish similar objects and are not used to describe a particular order or sequence. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0029] In a first aspect, embodiments of the present invention provide a method for preparing a carbon cloth current collector modified with a selenium-loaded amorphous carbon film, comprising the following steps: dissolving a selenium organic compound containing an aromatic ring and a phenolic resin in acetone, stirring until homogeneous to obtain a homogeneous precursor solution; immersing the carbon cloth in the precursor solution after washing and annealing, allowing it to stand for immersion, removing it and drying it, and then performing heat treatment in an inert atmosphere to obtain a carbon cloth current collector modified with a selenium-loaded amorphous carbon film.

[0030] Preferably, in the preparation of the carbon cloth current collector modified with selenium-loaded amorphous carbon film, the selenium organic compound containing an aromatic ring is one of the following: methyl phenyl selenide, diphenyl selenide, or di-p-toluene selenide.

[0031] Preferably, in the preparation of the carbon cloth current collector modified with selenium-loaded amorphous carbon film, the phenolic resin is a linear phenolic resin with a number-average molecular weight of 500-800.

[0032] Preferably, in the preparation of the carbon cloth current collector modified with selenium-loaded amorphous carbon film, the mass ratio of the aromatic ring-containing selenium organic compound, phenolic resin, and acetone is 0.55-0.60:1:10.

[0033] Preferably, in the preparation of the carbon cloth current collector modified with selenium-loaded amorphous carbon film, the volume ratio of carbon cloth to precursor liquid is 1:55-75.

[0034] Preferably, in the preparation of the carbon cloth current collector modified with selenium-loaded amorphous carbon film, the temperature for static impregnation is room temperature, and the static impregnation time is 1-2 hours.

[0035] Preferably, in the preparation of the carbon cloth current collector modified with selenium-loaded amorphous carbon film, the drying temperature after static impregnation is 80-85℃, and the drying time is 6-8h.

[0036] Preferably, in the preparation of the carbon cloth current collector modified with selenium-loaded amorphous carbon film, the heating rate of the heat treatment is 3-5℃ / min, the heat treatment temperature is 500-540℃, and the heat treatment time is 5-7h.

[0037] Preferably, in the preparation of the carbon cloth current collector modified with selenium-loaded amorphous carbon film, the annealing treatment is carried out in an inert atmosphere at 300-320°C for 1-1.5 hours.

[0038] Secondly, embodiments of the present invention also provide a carbon cloth current collector modified with a selenium-loaded amorphous carbon film prepared by the aforementioned method, comprising: a carbon cloth current collector fiber matrix; The surface of the fibers in the carbon cloth current collector fiber matrix is ​​coated with an amorphous carbon layer. The amorphous carbon layer is loaded with Se nanoparticles, and the Se nanoparticles are covalently connected to the carbon atoms of the amorphous carbon layer.

[0039] Thirdly, embodiments of the present invention also provide the application of the carbon cloth current collector modified with the selenium-loaded amorphous carbon film in the preparation of lithium metal batteries.

[0040] Fourthly, embodiments of the present invention also provide a lithium metal battery, comprising: a composite lithium metal anode; The method for preparing the composite lithium metal anode is as follows: in an inert atmosphere, the carbon cloth current collector modified with the aforementioned selenium-loaded amorphous carbon film is placed in an inert crucible, and then a lithium metal sheet is placed on top of the carbon cloth current collector modified with the selenium-loaded amorphous carbon film. The temperature is raised to 200°C and held until the lithium metal sheet is completely melted. After cooling, the composite lithium metal anode is obtained.

[0041] Preferably, in the preparation of the composite lithium metal anode, the weight ratio of the lithium metal sheet to the carbon cloth current collector modified with selenium-loaded amorphous carbon film is controlled to be 1:1.5-1.8.

[0042] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described below in conjunction with some specific embodiments.

[0043] The carbon cloth used in subsequent embodiments and comparative examples is of the WOS1009 grade and has a thickness of 0.33 mm. In the specific preparation process, the carbon cloth is cut into circular pieces with a diameter of 13 mm, and the volume of a single circular piece is 4.38 × 10⁻⁶ mm. -8 m 3 .

[0044] Example 1 This embodiment provides a method for preparing a carbon cloth current collector modified with a selenium-loaded amorphous carbon film, the specific steps of which are as follows: 1) Accurately weigh 2.00g of methyl phenyl selenide and 3.50g of linear phenolic resin (number average molecular weight range 500-800), add them to a beaker containing 35.00g of acetone, and mix until the solute is completely dissolved to obtain the precursor solution.

[0045] 2) The carbon cloth was washed in a mixed solution of acetone, anhydrous ethanol, and deionized water (volume ratio = 1:1:1), annealed at 300℃ for 1 h, then immersed in a precursor solution, allowed to stand at room temperature for 1 h, and then removed and vacuum dried at 80℃ for 6 h to obtain carbon cloth coated with the precursor. The carbon cloth coated with the precursor was then placed in an argon atmosphere and heated to 500℃ at a rate of 5℃ / min, and held at that temperature for 7 h to obtain a carbon cloth current collector modified with a selenium-loaded amorphous carbon film.

[0046] This embodiment also provides a carbon cloth current collector modified with a selenium-loaded amorphous carbon film prepared using the aforementioned method. For example... Figure 1 As shown, the carbon fiber surface inside the carbon cloth current collector modified with selenium-loaded amorphous carbon film in Example 1 is smooth; simultaneously, the surface of the carbon fiber inside the current collector is smooth. Figure 2 The mapping diagram shows the presence of C and Se elements and the uniform distribution of Se elements; Figure 3 The energy spectrum also proved the presence of C and Se elements.

[0047] Example 2 This embodiment provides a method for preparing a carbon cloth current collector modified with a selenium-loaded amorphous carbon film, the specific steps of which are as follows: 1) Accurately weigh 2.2g of diphenylselenoether and 4.00g of linear phenolic resin (number average molecular weight range 500-800), add them to a beaker containing 40.00g of acetone, and mix until the solute is completely dissolved to obtain the precursor solution.

[0048] 2) The carbon cloth was washed in a mixed solution of acetone, anhydrous ethanol, and deionized water (volume ratio = 1:1:1), annealed at 300℃ for 1 h, then immersed in a precursor solution, allowed to stand at room temperature for 1 h, and then removed and vacuum dried at 80℃ for 6 h to obtain carbon cloth coated with the precursor. Then, the carbon cloth coated with the precursor was placed in an argon atmosphere and heated to 540℃ at a rate of 4℃ / min, and held at that temperature for 5 h to obtain a carbon cloth current collector modified with a selenium-loaded amorphous carbon film.

[0049] This embodiment also provides a carbon cloth current collector modified with a selenium-loaded amorphous carbon film prepared by the aforementioned method.

[0050] Example 3 This embodiment provides a method for preparing a carbon cloth current collector modified with a selenium-loaded amorphous carbon film, the specific steps of which are as follows: 1) Accurately weigh 2.70g of di-p-toluene selenide and 4.50g of linear phenolic resin (number average molecular weight range 500-800), add them to a beaker containing 45.00g of acetone, and mix until the solute is completely dissolved to obtain the precursor solution.

[0051] 2) The carbon cloth was washed in a mixed solution of acetone, anhydrous ethanol, and deionized water (volume ratio = 1:1:1), annealed at 300℃ for 1 h, then immersed in a precursor solution, allowed to stand at room temperature for 1 h, and then removed and vacuum dried at 80℃ for 6 h to obtain carbon cloth coated with the precursor. The carbon cloth coated with the precursor was then placed in an argon atmosphere and heated to 520℃ at a rate of 3℃ / min, and held at that temperature for 6 h to obtain a carbon cloth current collector modified with a selenium-loaded amorphous carbon film.

[0052] This embodiment also provides a carbon cloth current collector modified with a selenium-loaded amorphous carbon film prepared by the aforementioned method.

[0053] Comparative Example 1 This comparative example uses the technical solution of Example 1, except that the selenium organic compound containing an aromatic ring is replaced with sodium selenide. The specific steps are as follows: 1) Accurately weigh 1.46g sodium selenide and 3.50g linear phenolic resin (number average molecular weight range 500-800), add them to a beaker containing 35.00g acetone, and mix until the solutes are completely dissolved to obtain the precursor solution.

[0054] 2) The carbon cloth was washed in a mixed solution of acetone, anhydrous ethanol, and deionized water (volume ratio = 1:1:1), annealed at 300℃ for 1 hour, then immersed in a precursor solution, allowed to stand at room temperature for 1 hour, and then removed and vacuum dried at 80℃ for 6 hours to obtain the carbon cloth coated with the precursor. The carbon cloth coated with the precursor was then placed in an argon atmosphere and heated to 500℃ at a rate of 5℃ / min, and held at that temperature for 7 hours to obtain a selenium-loaded carbon cloth current collector.

[0055] Depend on Figure 4 As can be seen, the carbon fiber surface inside the selenium-loaded carbon cloth current collector prepared in Comparative Example 1 has obvious particulate matter, and no smooth film is formed.

[0056] Comparative Example 2 This comparative example uses the technical solution of Example 1, except that the linear phenolic resin is replaced with glucose. The specific steps are as follows: 1) Accurately weigh 2.00g of methylphenyl selenide and 3.50g of glucose, add them to a beaker containing 35.00g of acetone, and mix until the solutes are completely dissolved to obtain the precursor solution.

[0057] 2) The carbon cloth was washed in a mixed solution of acetone, anhydrous ethanol, and deionized water (volume ratio = 1:1:1), annealed at 300℃ for 1 hour, then immersed in a precursor solution, allowed to stand at room temperature for 1 hour, and then removed and vacuum dried at 80℃ for 6 hours to obtain the carbon cloth coated with the precursor. The carbon cloth coated with the precursor was then placed in an argon atmosphere and heated to 500℃ at a rate of 5℃ / min, and held at that temperature for 7 hours to obtain a selenium-loaded carbon cloth current collector.

[0058] Depend on Figure 5 As can be seen, the surface of the carbon fibers inside the selenium-loaded carbon cloth current collector prepared in Comparative Example 2 has a large number of irregular particles.

[0059] Comparative Example 3 This comparative example uses the technical solution of Example 1, the difference being that the heat treatment temperature is increased to 600℃. The specific steps are as follows: 1) Accurately weigh 2.00g of methyl phenyl selenide and 3.50g of linear phenolic resin (number average molecular weight range 500-800), add them to a beaker containing 35.00g of acetone, and mix until the solute is completely dissolved to obtain the precursor solution.

[0060] 2) The carbon cloth was washed in a mixed solution of acetone, anhydrous ethanol, and deionized water (volume ratio = 1:1:1), annealed at 300℃ for 1 h, then immersed in a precursor solution, allowed to stand at room temperature for 1 h, and then removed and vacuum dried at 80℃ for 6 h to obtain carbon cloth coated with the precursor. The carbon cloth coated with the precursor was then placed in an argon atmosphere and heated to 600℃ at a rate of 5℃ / min, and held at that temperature for 7 h to obtain a carbon cloth current collector modified with a selenium-loaded amorphous carbon film.

[0061] Depend on Figure 6 As can be seen, the carbon fiber surface film inside the carbon cloth current collector modified with selenium-loaded amorphous carbon film prepared in Comparative Example 3 is broken to varying degrees. Analysis shows that this is mainly due to the excessively high heat treatment temperature.

[0062] Application Example 1 In an argon-atmosphere glove box, the carbon cloth current collectors modified with selenium-loaded amorphous carbon films of Examples 1-3 were placed in inert crucibles, and lithium metal sheets were added on top of them. The temperature was increased to 200°C by programmed heating (5°C / min) to completely melt the lithium sheets. The temperature was held for 30 minutes to allow the molten lithium to fully wet the porous structure of each selenium-loaded carbon cloth current collector and form a stable bond with the carbon cloth. After natural cooling to room temperature, a composite lithium metal anode modified with selenium-loaded amorphous carbon film with both high conductivity and lithium storage capacity was obtained.

[0063] The weight ratio of the added lithium metal sheet to the carbon cloth current collector modified with selenium-loaded amorphous carbon film is controlled to be 1:1.7.

[0064] To facilitate subsequent performance testing, the selenium-loaded carbon cloth current collectors prepared in Comparative Examples 1-3 were used to fabricate composite lithium metal anodes using the same method described above. Then, lithium metal batteries were assembled using the composite lithium metal anodes from Examples 1-3 and Comparative Examples 1-3, respectively, according to the following method: In an argon-atmosphere glove box (water and oxygen content both <0.1ppm), NCM811 was used as the positive electrode active material and mixed with conductive carbon black and polyvinylidene fluoride (PVDF) at a mass ratio of 8:1:1. N-methylpyrrolidone (NMP) was added to prepare a uniform slurry, which was then coated onto an aluminum foil current collector. After vacuum drying at 80℃ for 12h, the slurry was cut into positive electrode sheets with a diameter of 12mm. Using the positive electrode sheet, the composite lithium metal negative electrodes prepared in the aforementioned embodiments and comparative examples, and with Celgard 2400 as the separator (19 mm in diameter) and LiPF6 / ethylene carbonate EC-dimethyl carbonate DMC (volume ratio 1:1) at a concentration of 1 mol / L as the electrolyte, the CR2032 coin cell was assembled layer by layer in the following order: negative electrode shell → spring sheet → gasket → negative electrode → electrolyte (100 μL added to each electrode) → separator → electrolyte → positive electrode → positive electrode shell. Finally, the assembly of the lithium metal battery was completed by pressing and sealing it with a battery sealing machine.

[0065] The performance of the lithium metal batteries corresponding to Examples 1-3 and Comparative Examples 1-3 was tested, with the test current density controlled at 1C and the voltage range at 2.8-4.3V. The specific test results are shown in the table below:

[0066] The superior performance of Examples 1-3 is a concentrated manifestation of the multi-dimensional technical advantages of this invention. Its core logic lies in the synergistic empowerment of each innovative link: the key lies in the selection of aromatic ring selenium organic compounds as precursors, which form a high-density three-dimensional carbon framework after high-temperature carbonization. This structure not only provides a stable supporting matrix for the selenium active components, effectively buffering the volume expansion during lithium deposition / stripping, but also precisely constructs stable Se-C covalent bonds through the controllable cleavage of Se-C chemical bonds in the precursor. This not only avoids the agglomeration and loss of elemental selenium, but also inhibits the dissolution of polyselenides in the electrolyte, laying the foundation for stable performance. At the same time, the aromatic ring structure of the precursor and the conjugated aromatic rings on the carbon cloth surface form a strong π-π conjugation effect, which significantly improves the interfacial bonding force between the selenium-loaded amorphous carbon film and the carbon cloth substrate compared with traditional physical bonding. Combined with the compact structure and uniform smooth surface of the composite film itself, it significantly reduces the lithium nucleation overpotential (<50mV) and accelerates ion transport efficiency. On the other hand, it eliminates surface defects from the root and completely inhibits the preferential growth of lithium dendrites. Furthermore, the three-dimensional porous structure of the carbon cloth and the selenium-loaded amorphous carbon film form a synergistic effect: the carbon cloth provides ample space for lithium deposition, the lithium-affinity modification of the composite film further optimizes the deposition environment, and the process stability brought by the one-step heating method (simultaneously achieving carbonization, bonding and film deposition, ensuring film uniformity) ultimately contributes to the ultra-high performance of the battery - after 1300h long cycle, the overpotential is only maintained at 42-48mV, and the capacity retention rate is still over 85% after 500 cycles at 1.0C rate. The performance shortcomings of the comparative example, in turn, confirm the necessity of the core technology of this invention: Comparative Example 1 replaced the aromatic ring selenium-containing organic compound with sodium selenide, completely losing the advantages of the high-density carbon skeleton and controllable Se-C covalent bonds brought by the aromatic ring. This resulted in easy aggregation and loss of the selenium component, and weak adhesion between the film layer and the substrate. Ultimately, after 1200 hours of cycling, the overpotential rose to 81 mV, and the capacity retention rate after 500 cycles was only 56.6%. The above performance differences are... Figure 7 Symmetrical battery performance curves and Figure 8 The full-cell performance curves clearly demonstrate this. As shown in the figures, compared to Example 1, Comparative Example 1 exhibits a more pronounced capacity decay and a continuously increasing overpotential during cycling. In contrast, Example 1 effectively suppresses overpotential growth and slows down capacity decay during cycling. Comparative Example 2 uses glucose instead of phenolic resin precursors. The carbon skeleton formed after glucose carbonization lacks density, failing to stably support the selenium component. Furthermore, it lacks the π-π conjugation effect brought by the aromatic ring structure, resulting in easy film detachment and poor structural stability. The first-cycle discharge specific capacity is only 155 mAh / g, and the capacity retention rate after 500 cycles is as low as 47.9%. Comparative Example 3 increases the heating temperature to 600℃, disrupting the controllable cracking process of the Se-C bond. This leads to unstable bonding between selenium and the carbon matrix, and damage to the carbon skeleton structure, ultimately resulting in a capacity retention rate of only 68.3% after 500 cycles.

[0067] Unless otherwise stated, all percentages used in this invention are mass percentages.

[0068] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a carbon cloth current collector modified with a selenium-loaded amorphous carbon film, characterized in that, Includes the following steps: Selenium organic compounds containing aromatic rings and phenolic resins are dissolved in acetone and stirred evenly to obtain a homogeneous precursor solution. After washing and annealing, carbon cloth is immersed in the precursor solution, left to stand for immersion, then removed and dried. Finally, it is heat-treated in an inert atmosphere to obtain a carbon cloth current collector modified with a selenium-loaded amorphous carbon film. The aromatic ring-containing selenium organic compound is one of the following: methyl phenyl selenide, diphenyl selenide, or di-p-toluene selenide.

2. The method for preparing the carbon cloth current collector modified with selenium-loaded amorphous carbon film according to claim 1, characterized in that, The mass ratio of the aromatic ring-containing selenium organic compound, phenolic resin, and acetone is 0.55-0.60:1:

10.

3. The method for preparing the carbon cloth current collector modified with selenium-loaded amorphous carbon film according to claim 1, characterized in that, Annealing is performed in an inert atmosphere at 300-320℃ for 1-1.5 hours.

4. The method for preparing the carbon cloth current collector modified with selenium-loaded amorphous carbon film according to claim 1, characterized in that, The volume ratio of carbon cloth to precursor liquid is 1:55-75.

5. The method for preparing the carbon cloth current collector modified with selenium-loaded amorphous carbon film according to claim 1, characterized in that, The temperature for static immersion is room temperature, and the immersion time is 1-2 hours.

6. The method for preparing the carbon cloth current collector modified with selenium-loaded amorphous carbon film according to claim 1, characterized in that, The heating rate for heat treatment is 3-5℃ / min, the temperature for heat treatment is 500-540℃, and the time for heat treatment is 5-7h.

7. A carbon cloth current collector modified with a selenium-loaded amorphous carbon film, prepared by the method according to any one of claims 1-6, characterized in that, Includes: carbon fiber current collector matrix; The surface of the fibers in the carbon cloth current collector fiber matrix is ​​coated with an amorphous carbon layer. The amorphous carbon layer is loaded with Se nanoparticles, and the Se nanoparticles are covalently connected to the carbon atoms of the amorphous carbon layer.

8. The application of a carbon cloth current collector modified with a selenium-loaded amorphous carbon film as described in claim 7 in the preparation of lithium metal batteries.

9. A lithium metal battery, characterized in that, Includes: composite lithium metal anode; The method for preparing the composite lithium metal anode is as follows: in an inert atmosphere, the carbon cloth current collector modified with selenium-loaded amorphous carbon film as described in claim 7 is placed in an inert crucible, and then a lithium metal sheet is placed on top of the carbon cloth current collector modified with selenium-loaded amorphous carbon film. The temperature is raised to 200°C and held until the lithium metal sheet is completely melted. After cooling, the composite lithium metal anode is obtained.

10. The lithium metal battery according to claim 9, characterized in that, In the preparation of the composite lithium metal anode, the weight ratio of the lithium metal sheet to the carbon cloth current collector modified with selenium-loaded amorphous carbon film is controlled to be 1:1.5-1.8.

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