Preparation method and application of caramel-shaped carbon nanosheets containing Co / CoSe2 heterostructure supported on carbon cloth

Abstract

This invention belongs to the field of lithium metal battery technology, specifically relating to a method for preparing and applying starfruit-shaped carbon nanosheets with a Co / CoSe2 heterostructure loaded on carbon cloth. The invention first immerses carbon cloth in a mixed solution of cobalt nitrate hexahydrate and 2-methylimidazole, allowing it to stand to form a precursor. This precursor is then subjected to carbonization and selenization treatments to obtain starfruit-shaped carbon nanosheets with a Co / CoSe2 heterostructure loaded on three-dimensional carbon cloth. The Co / CoSe2 heterostructure interface and the built-in electric field it forms can induce uniform lateral deposition of metallic lithium, effectively suppressing the growth of lithium dendrites. Simultaneously, the Co nanoparticles coated with graphite carbon can catalyze the formation of carbon nanotubes with high specific surface area and good conductivity on the carbon layer surface, alleviating the volume expansion of the electrode during charge and discharge. The synergistic effect of the Co / CoSe2 heterostructure and carbon nanotubes significantly improves the cycle life and stability of lithium metal batteries.

Description

Technical Field

[0001] This invention belongs to the field of lithium metal battery technology, specifically relating to a method for preparing starfruit-shaped carbon nanosheets containing a Co / CoSe2 heterostructure loaded on carbon cloth and their application. Background Technology

[0002] Lithium metal batteries boast an ultra-high theoretical specific capacity (3860 mAh·g) -1 It has a lower electrochemical potential (-3.04 V vs. standard hydrogen electrode) and a lighter density (0.534 g·cm³). -3 Lithium metal (LiMH) is considered an ideal choice for next-generation rechargeable battery anode materials, showing great application potential in electric vehicles, aerospace, and energy storage. However, the commercialization of lithium metal batteries still faces many challenges. These challenges stem from uncontrollable dendrite growth, the generation of large amounts of "dead lithium," and significant volume expansion during battery cycling, severely impacting cycle stability and posing a significant threat to battery safety. To address these internal battery problems, researchers have creatively proposed a series of solutions, such as using solid-state electrolytes, constructing artificial solid electrolyte mesophases, and modifying liquid electrolytes. Recent research indicates that using a three-dimensional framework with lithiophilic sites modified on its surface or internally as a "host" to accommodate lithium metal can effectively alleviate the volume expansion of lithium metal during charging and discharging, and improve lithium nucleation and growth by lowering the lithium nucleation barrier, thereby inhibiting lithium dendrite formation to some extent. However, in high deposition areal capacities (>4 mAh·cm³), the development of lithium metal anodes still faces challenges. -2 When this occurs, a large amount of dead lithium is generated and accumulates on the substrate surface, blocking Li + The diffusion pathway to lithiophilic sites renders their regulatory effect on subsequent Li nucleus distribution ineffective, causing the advantage of lowering the nucleation barrier to gradually disappear during cycling. Therefore, it is urgent to explore the stability and protection strategies of lithiophilic sites in a three-dimensional framework to ensure the stability of lithium metal anodes. Summary of the Invention

[0003] To overcome the shortcomings of the prior art, this invention designs and prepares starfruit-shaped carbon nanosheets with a Co / CoSe2 heterostructure loaded on a three-dimensional carbon cloth. Through the strong adsorption of metallic lithium by the Co / CoSe2 heterostructure and the built-in electric field generated at the Co / CoSe2 heterostructure interface, lithium adsorption is accelerated. + The diffusion of lithium dendrites is prevented from forming an accumulation at the adsorption sites, thereby effectively inducing uniform lateral deposition of lithium metal to solve the problem of poor confinement of lithium dendrites by the host material in the existing technology.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] The first aspect of this invention provides a method for preparing starfruit-shaped carbon nanosheets containing a Co / CoSe2 heterostructure loaded on carbon cloth, the method comprising the following steps:

[0006] Preparation of S1 and ZIF-67@CC precursor: First, carbon cloth (CC) is soaked in cobalt nitrate hexahydrate solution, then 2-methylimidazole solution is added. After being fully dissolved, ZIF-67@CC precursor is obtained by standing at room temperature.

[0007] Preparation of S2 and Co@CNT@CC: The ZIF-67@CC precursor of S1 was placed in an inert atmosphere, and after adding a catalyst, it was calcined to obtain starfruit-shaped nanosheets Co@CNT@CC with Co nanoparticles loaded for in-situ catalytic growth of carbon nanotubes.

[0008] Preparation of S3, Co / CoSe2@CNT@CC:

[0009] Selenium powder was added to the Co@CNT@CC material of S2 at a mass ratio of 1:7-9 to Co@CNT@CC. After calcination under an inert atmosphere, starfruit-shaped carbon nanosheets Co / CoSe2@CNT@CC with a Co / CoSe2 heterostructure were obtained and loaded on a three-dimensional carbon cloth.

[0010] This invention first immerses carbon cloth in a mixed solution of cobalt nitrate hexahydrate and 2-methylimidazole. After standing, a ZIF-67@CC precursor is obtained. The precursor is then subjected to carbonization and selenization treatments to prepare starfruit-shaped carbon nanosheets (Co / CoSe2@CNT@CC) with a Co / CoSe2 heterostructure loaded on three-dimensional carbon cloth. The preparation method of this invention is simple, convenient, clean, and pollution-free. It has low equipment requirements, requires a low reaction temperature, and is moderately costly, making it suitable for large-scale production. The unique feature of this invention is that the Co / CoSe2 heterostructure formed after selenization has a strong adsorption effect on metallic lithium, and the built-in electric field can regulate the rapid transport of ions and electrons, inducing uniform lateral deposition of metallic lithium, thereby effectively inhibiting the growth of lithium dendrites. Simultaneously, the graphite carbon-coated Co nanoparticles can catalyze the formation of carbon nanotubes with high specific surface area and good conductivity on the carbon layer surface. These carbon nanotubes can accelerate the deposition of lithium... + The carbon nanotubes facilitate the transport of lithium metal and store large quantities of lithium metal, thus mitigating the volume expansion of the electrodes during charging and discharging. Therefore, the synergistic effect of the Co / CoSe2 heterostructure and carbon nanotubes significantly improves the cycle life and stability of lithium metal batteries.

[0011] Preferably, in S1, the concentration of the cobalt nitrate hexahydrate solution is 0.720-0.730 g / 50 mL, and the concentration of the 2-methylimidazole solution is 1.630-1.642 g / 50 mL.

[0012] Preferably, in S1, the room temperature standing time is 20-30 hours.

[0013] Preferably, in S2, the catalyst is melamine, and the mass ratio of the catalyst to the ZIF-67@CC precursor is 1:1.

[0014] Preferably, in S2, the calcination process is at 4-6°C / min. -1 The heating rate is increased to 700-900℃ and held for 1-3 hours. The calcination temperature in S2 affects the formation of carbon nanotubes. ZIF-67 is heat-treated at 700-900℃ in a nitrogen atmosphere. During the carbonization process, the Co nanoparticles coated with graphite carbon catalyze the formation of carbon nanotubes with high specific surface area and good conductivity on the carbon layer surface. These carbon nanotubes can accelerate the formation of Li. + It can transmit and store large amounts of metallic lithium, thereby alleviating the volume expansion of the electrode during charging and discharging.

[0015] Preferably, in S2, the calcination process is at 4-6°C / min. -1 The temperature is increased to 550-600℃ for selenization reaction for 1-3 hours. The Co / CoSe2 heterostructure formed after selenization has a strong adsorption effect on metallic lithium, and the built-in electric field can regulate the rapid transport of ions and electrons, induce uniform lateral deposition of metallic lithium, and effectively inhibit the growth of lithium dendrites.

[0016] Preferably, the carbon cloth is cleaned before use: first, it is washed with dilute hydrochloric acid and acetone in sequence, and then washed repeatedly with ethanol and water alternately.

[0017] More preferably, the concentration of the dilute hydrochloric acid is 2-5%, the cleaning time is 15-30 min, the cleaning time of the acetone is 5-10 min, and the number of times the ethanol and deionized water are alternately cleaned is 1-3 times.

[0018] Preferably, the inert atmosphere described in S2 and S3 includes a nitrogen atmosphere and an argon atmosphere.

[0019] The second aspect of the present invention provides starfruit-shaped carbon nanosheets containing a Co / CoSe2 heterostructure loaded on carbon cloth, prepared by the preparation method described in the first aspect.

[0020] The starfruit-shaped carbon nanosheets with a Co / CoSe2 heterostructure loaded on three-dimensional carbon cloth prepared by the method of the present invention can exhibit good affinity for lithium metal when used as host materials for lithium metal anodes. Furthermore, the transport of Li ions and electrons can be effectively regulated by the built-in electric field of the heterostructure interface, thereby improving the deposition behavior of lithium metal and enabling it to maintain good cycling stability under practical conditions.

[0021] The third aspect of the present invention provides the application of the starfruit-shaped carbon nanosheets containing a Co / CoSe2 heterostructure loaded on carbon cloth as described in the second aspect in the preparation of lithium metal batteries, wherein the starfruit-shaped carbon nanosheets containing a Co / CoSe2 heterostructure loaded on carbon cloth serve as the negative electrode host material or negative electrode material of lithium metal batteries.

[0022] The starfruit-shaped carbon nanosheets with a Co / CoSe2 heterostructure prepared by the method of this invention exhibit excellent lithium-affinity properties. When used as a host material in the anode of lithium metal batteries, they effectively suppress the formation of lithium dendrites, resulting in batteries with high coulombic efficiency, ultra-long cycle life, and stability. Importantly, the assembled Li||LiFePO4 battery demonstrates a long-term cycle durability exceeding 350 cycles at 1C.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] This invention discloses a method for preparing starfruit-shaped carbon nanosheets containing a Co / CoSe2 heterostructure loaded on carbon cloth. First, carbon cloth is immersed in a mixed solution of cobalt nitrate hexahydrate and 2-methylimidazole. After standing, a ZIF-67@CC precursor is obtained. Then, the precursor is subjected to carbonization and selenization treatments to prepare starfruit-shaped carbon nanosheets (Co / CoSe2@CNT@CC) loaded on three-dimensional carbon cloth containing a Co / CoSe2 heterostructure. Specifically, this invention has the following advantages:

[0025] (1) The method of the present invention is simple and easy to implement, requires a low temperature, is convenient for post-processing, does not require high equipment, has a moderate cost, and is suitable for large-scale production.

[0026] (2) The Co / CoSe2 heterostructure formed after selenization has a strong adsorption effect on lithium metal, and the built-in electric field formed can regulate the rapid transport of ions and electrons, induce uniform lateral deposition of lithium metal, and thus effectively inhibit the growth of lithium dendrites.

[0027] (3) During the carbonization process, after ZIF-67 is heat-treated at 750℃ in an Ar atmosphere, the graphite carbon-coated Co nanoparticles can catalyze the formation of carbon nanotubes with high specific surface area and good conductivity on the carbon layer surface. These carbon nanotubes can accelerate the formation of Li + It can transmit and store large amounts of metallic lithium, thereby alleviating the volume expansion of the electrode during charging and discharging.

[0028] (4) The starfruit-shaped carbon nanosheets containing Co / CoSe2 heterostructures synthesized by the method of the present invention and loaded on three-dimensional carbon cloth have excellent wettability with metallic lithium, and molten metallic lithium can quickly undergo an alloy reaction with the Co / CoSe2@CNT@CC electrode, thereby obtaining a uniform composite lithium metal anode (Li@Co / CoSe2@CNT@CC) with high efficiency and low cost.

[0029] (5) Using the starfruit-shaped carbon nanosheets containing Co / CoSe2 heterostructures and synthesized by the method of the present invention as the negative electrode skeleton material of lithium metal battery, the nucleation barrier of lithium metal can be reduced by alloying with lithium ions, thereby reducing deposition resistance and promoting uniform deposition of lithium metal.

[0030] (6) The starfruit-shaped carbon nanosheets with Co / CoSe2 heterostructures loaded on three-dimensional carbon cloth synthesized by the method of the present invention have the advantages of high coulombic efficiency and good cycle stability. Attached Figure Description

[0031] Figure 1 Scanning electron microscope images and elemental distribution maps of Co / CoSe2@CNT@CC;

[0032] Figure 2 High-resolution transmission electron microscopy (TEM) image and selected area electron diffraction (SED) pattern of Co / CoSe2@CNT@CC;

[0033] Figure 3 X-ray diffraction patterns of Co / CoSe2@CNT@CC, Co@CNT@CC, and CoSe2@CNT@CC;

[0034] Figure 4 Three types of starfruit-shaped carbon nanosheets with Co, CoSe2, and Co / CoSe2 heterostructures loaded on three-dimensional carbon cloth were tested at 0.5 mA·cm⁻¹. -2 The current density and 0.5 mAh·cm -2 Lithium deposition / stripping coulombic efficiency at area capacity;

[0035] Figure 5 Three types of starfruit-shaped carbon nanosheets with Co, CoSe2, and Co / CoSe2 heterostructures loaded on three-dimensional carbon cloth were tested at 1 mA·cm⁻¹. -2 Current density and 1 mAh·cm -2 The long-cycle performance of symmetrical cells with a certain area capacity;

[0036] Figure 6 The adsorption diagram of Co / CoSe2@CNT@CC for molten lithium at 300℃ (0-10s represents the time for adsorption of molten lithium);

[0037] Figure 7 The graph shows the cycling performance of three types of starfruit-shaped carbon nanosheets with Co, CoSe2 and Co / CoSe2 heterostructures loaded on three-dimensional carbon cloth as anode materials for lithium metal batteries at 1C rate. Detailed Implementation

[0038] The specific embodiments of the present invention will be further described below. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0039] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and the experimental materials used in the following embodiments are all available through conventional commercial channels.

[0040] Example 1: A method for preparing starfruit-shaped nanosheets (Co@CNT@CC) with Co nanoparticles supporting in-situ catalytic growth of carbon nanotubes.

[0041] (1) Cleaning carbon cloth: First, soak the carbon cloth (CC) in dilute hydrochloric acid with a concentration of 4% and clean it for 15 minutes under ultrasonic conditions of 600w. Then, use acetone for ultrasonic washing for 5 minutes. Finally, use anhydrous ethanol and deionized water to clean it 5 times alternately.

[0042] (2) Preparation of ZIF-67@CC precursor: 0.724 g of cobalt nitrate hexahydrate was dissolved in 50 mL of deionized water to form solution A. Then, the washed wet CC (with an area of ​​4 × 5 cm²) was added. 2 The sample was completely immersed in solution A. Then, 1.640 g of 2-methylimidazole was dissolved in 50 mL of deionized water to form solution B. Solution B was then quickly poured into solution A, and the mixture was stirred (500 rpm for 5 min) until fully dissolved. The solution was then left to stand at room temperature for 24 h. The resulting composite material was then washed three times with deionized water and anhydrous ethanol, and then dried overnight in an oven (60 °C for 12 h) to obtain the ZIF-67@CC precursor.

[0043] (3) Preparation of Co@CNT@CC: The ZIF-67@CC precursor obtained in step (2) was placed under a nitrogen atmosphere and melamine catalyst was added. The mass ratio of melamine to ZIF-67@CC precursor was 1:1. Then, the mixture was heated at 5℃·min. -1 The temperature was increased to 800℃ and held for 2 hours to obtain starfruit-shaped nanosheets with Co nanoparticles supporting in-situ growth of carbon nanotubes, denoted as Co@CNT@CC.

[0044] Example 2: A method for preparing starfruit-shaped carbon nanosheets (CoSe2@CNT@CC) with a Co / CoSe2 heterostructure loaded on three-dimensional carbon cloth.

[0045] Steps (1)-(3) are the same as in Example 1, and also include a selenization step after carbonization. Specifically:

[0046] (4) Selenization of Co@CNT@CC: Selenium powder was added to the Co@CNT@CC material obtained in step (3) at a mass ratio of 1:1, and the mixture was heated at 5°C·min under a nitrogen atmosphere. -1 The temperature was increased to 600℃ and held for 2 hours to obtain CoSe2@CNT@CC. Example 3: A method for preparing starfruit-shaped carbon nanosheets (Co / CoSe2@CNT@CC) with a Co / CoSe2 heterostructure supported on three-dimensional carbon cloth.

[0047] Steps (1)-(3) are the same as in Example 1. The selenization in step (4) is basically the same as in Example 2. The difference is that the mass ratio of selenium powder to Co@CNT@CC material is 1:8, and Co / CoSe2@CNT@CC is obtained by calcination.

[0048] Morphological characterization of Co / CoSe2@CNT@CC was performed. Figure 1 Scanning electron microscopy (SEM) images and elemental distribution maps show that Co / CoSe2@CNT@CC exhibits a starfruit-like carbon nanosheet morphology. The elemental distribution map results show that it contains C, N, Co, and Se elements, which are uniformly distributed in the starfruit-like carbon nanosheets of the selenized Co / CoSe2 heterostructure.

[0049] Figure 2 High-resolution transmission electron microscopy (TEM) images and selected area electron diffraction (SED) patterns of Co / CoSe2@CNT@CC were obtained. The lattice spacing of 0.204 nm corresponds to the (111) plane of Co, and 0.26 nm corresponds to the (210) plane of CoSe2. This indicates that a Co / CoSe2 heterojunction was successfully established at the interface.

[0050] Figure 3 The X-ray diffraction patterns of Co / CoSe2@CNT@CC, Co@CNT@CC, and CoSe2@CNT@CC are shown. It can be seen that the diffraction peaks of the Co / CoSe2 heterostructure match well with the standard peaks of Co and CoSe2, indicating that the heterostructure was successfully constructed and has high purity.

[0051] Experimental Example: Preparation and Performance Testing of Lithium Metal Anode Materials

[0052] Starfruit-shaped carbon nanosheets containing Co nanoparticles, CoSe2 heterostructures, or Co / CoSe2 heterostructures loaded on three-dimensional carbon cloth in Example 1 or 2 were cut into 12 mm electrode sheets and dried in a vacuum oven at 60 °C for 12 h to obtain lithium metal anode materials, which were labeled as Co@CNT@CC, CoSe2@CNT@CC, and Co / CoSe2@CNT@CC, respectively, and were used as lithium metal battery anode materials for electrochemical performance testing.

[0053] In half-cells, Co@CNT@CC, CoSe2@CNT@CC, and Co / CoSe2@CNT@CC electrodes are used directly as self-supporting electrodes; in full-cells, Co@CNT@CC, CoSe2@CNT@CC, and Co / CoSe2@CNT@CC electrodes are used with lithium metal as composite anodes, where Co@CNT@CC, CoSe2@CNT@CC, and Co / CoSe2@CNT@CC electrodes are the host materials for the lithium metal battery anode.

[0054] 1. Characterization of Cyclic Performance

[0055] (1) Assembly of half-cells: Co@CNT@CC or CoSe2@CNT@CC or Co / CoSe2@CNT@CC electrodes with a diameter of 12 mm and lithium metal sheets were assembled into Li|Co@CNT@CC, Li|CoSe2@CNT@CC and Li|Co / CoSe2@CNT@CC half-cells respectively in a glove box filled with nitrogen and with water and oxygen content below 0.01 ppm. The electrolyte system was selected as a 1,3-dioxolane (DOL) / ethylene glycol dimethyl ether (DME) solution containing 2 wt% lithium nitrate (LiNO3) and 1 mol / L lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) (v / v = 1:1). The separator was a commercially available polypropylene porous membrane.

[0056] (2) Electrochemical Testing: Coulombic efficiency (CE) is the ratio of lithium stripping capacity to lithium deposition capacity in a single battery cycle, and is another key indicator for evaluating electrode reversibility and host material performance. The Li||Co / CoSe2@CNT@CC, Li|CoSe2@CNT@CC, and Li|Co / CoSe2@CNT@CC half-cells were first tested at 0.05 mA·cm⁻¹. -2 Cycled 5 times at a current between 0.01 and 3V, then at 5mA·cm -2 Repeated deposition / exfoliation at current density of 5 mAh·cm -2 Lithium metal, with a coulombic efficiency as shown Figure 4As shown in the figure, the Co / CoSe2@CNT@CC electrode still exhibits stable CE after 500 cycles, with an average CE as high as 98.7%. This indicates that using a starfruit-shaped carbon nanosheet array containing a Co / CoSe2 heterostructure supported on a three-dimensional carbon cloth as a lithium storage material, the strong adsorption of metallic lithium by the Co / CoSe2 heterostructure can alleviate the volume expansion of lithium metal to a certain extent, forming a stable SEI layer. Furthermore, the built-in electric field generated at the Co / CoSe2 heterostructure interface can accelerate the lithium absorption capacity. + The diffusion of lithium metal is prevented from accumulating at adsorption sites, thereby effectively inducing uniform lateral deposition of lithium metal.

[0057] 2. Characterization of long-cycle performance

[0058] (1) Assembly of symmetrical cells: First, electrodeposition was performed on Li|Co@CNT@CC, Li|CoSe2@CNT@CC and Li|Co / CoSe2@CNT@CC half-cells, with a discharge current density of 0.5 mA·cm. -2 Pre-deposition 10mAh·cm -2 The half-cell was then disassembled in a glove box, and the composite lithium metal anodes Li@Co@CNT@CC, Li@CoSe2@CNT@CC, and Li@Co / CoSe2@CNT@CC were removed. The surface residual electrolyte was cleaned with excess DME. Two composite electrodes, Li@Co / CoSe2@CNT@CC, containing the same lithium metal capacity, were then assembled into symmetrical cells: Li@Co@CNT@CC|Li@Co@CNT@CC, Li@CoSe2@CNT@CC|Li@CoSe2@CNT@CC, and Li@Co / CoSe2@CNT@CC|Li@Co / CoSe2@CNT@CC. The electrolyte system was a 1,3-dioxolane (DOL) / ethylene glycol dimethyl ether (DME) solution containing 2 wt% lithium nitrate (LiNO3) and 1 mol / L lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) (v / v = 1:1). A commercially available polypropylene porous membrane was used as the separator.

[0059] (2) Electrochemical tests: Symmetric cells of Li@Co@CNT@CC|Li@Co@CNT@CC, Li@CoSe2@CNT@CC|Li@CoSe2@CNT@CC, and Li@Co / CoSe2@CNT@CC|Li@Co / CoSe2@CNT@CC were tested at 1 mA·cm⁻¹. -2 Repeated deposition / exfoliation at current density of 1 mAh·cm -2 Lithium metal, its cycle performance is as follows Figure 5As shown in the figure, the Li@Co / CoSe2@CNT@CC|Li@Co / CoSe2@CNT@CC symmetric cell exhibits a stable cycling curve within 1800 h.

[0060] 3. Molten lithium adsorption test:

[0061] First, the prepared Co / CoSe2@CNT@CC composite material was cut into electrode sheets with a diameter of 12 mm using a punching machine. Then, molten lithium adsorption tests were conducted in a glove box filled with nitrogen, with water and oxygen contents both below 0.01 ppm. The lithium sheet was placed in a stainless steel crucible and heated to 300°C on a hot plate. The Co / CoSe2@CNT@CC composite material was then placed on top of the molten lithium; the molten lithium was instantly adsorbed onto the electrode sheet, forming a composite lithium electrode. After cooling to room temperature, the Li@Co / CoSe2@CNT@CC composite electrode was obtained. Figure 6 The above results indicate that Co / CoSe2@CNT@CC exhibits good lithiophilicity, thereby improving the wettability of the substrate to lithium.

[0062] 3. Characterization of full-cell cycle performance

[0063] (1) Assembly of the full cell: First, electrodeposition was performed on the Li|Co@CNT@CC, Li|CoSe2@CNT@CC and Li|Co / CoSe2@CNT@CC half cells, with a discharge current of 0.5 mA·cm. -2 Pre-deposition 10mAh·cm -2 The lithium metal was then removed; the half-cell was then disassembled in a glove box, and the composite lithium metal anodes Li@Co@CNT@CC, Li@CoSe2@CNT@CC, and Li@Co / CoSe2@CNT@CC were removed. The surface residual electrolyte was then cleaned with excess DME; the active material loading was then increased to approximately 11 mg cm⁻¹. -2 Lithium iron phosphate (LFP) cathodes and composite lithium metal anodes were assembled in a glove box to form Li@Co@CNT@CC||LFP, Li@CoSe2@CNT@CC||LFP, and Li@Co / CoSe2@CNT@CC||LFP full cells, respectively. The electrolyte system used contained 1 mol·L⁻¹ -1 A lithium hexafluorophosphate (LiPF6) solution in ethylene carbonate (EC) / diethyl carbonate (DEC) (v / v = 1:1) was used with a polypropylene porous membrane as the membrane material.

[0064] (2) Electrochemical testing: Li@Co@CNT@CC||LFP, Li@CoSe2@CNT@CC||LFP, and Li@Co / CoSe2@CNT@CC||LFP full cells were charged and discharged at 1C rate between 2.4 and 4V. Their cycle performance is as follows: Figure 7 As shown in the figure, the Li@Co / CoSe2@CNT@CC||LFP full cell exhibits good cycling performance at 1C, with an initial discharge specific capacity of 155 mAh·g. -1 It maintains a high discharge specific capacity of 138 mAh·g after 350 stable cycles. -1 The capacity retention rate is as high as 89%; this indicates that the starfruit-shaped carbon nanosheets with Co / CoSe2 heterostructure loaded on the three-dimensional carbon cloth have a strong adsorption effect on metallic lithium through the Co / CoSe2 heterostructure, and the built-in electric field generated by the Co / CoSe2 heterostructure interface can accelerate the adsorption of lithium. + The diffusion of the Li@Co / CoSe2@CNT@CC||LFP full cells prevents them from accumulating at adsorption sites, thus enabling them to exhibit excellent electrochemical performance.

[0065] In summary, this invention first immerses carbon cloth in a mixed solution of cobalt nitrate hexahydrate and 2-methylimidazole, and after standing, obtains the ZIF-67@CC precursor. Then, the precursor undergoes carbonization and selenization treatments to prepare starfruit-shaped carbon nanosheets (Co / CoSe2@CNT@CC) loaded on three-dimensional carbon cloth and containing a Co / CoSe2 heterostructure. This invention utilizes the strong adsorption of metallic lithium by the Co / CoSe2 heterostructure and the built-in electric field generated at the Co / CoSe2 heterostructure interface to accelerate the adsorption of Li... + The diffusion of lithium dendrites is prevented from forming an accumulation at the adsorption sites, thereby effectively inducing uniform lateral deposition of lithium metal and solving the problem of poor confinement of lithium dendrites by the host material in the existing technology.

[0066] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A method for preparing starfruit-shaped carbon nanosheets containing a Co / CoSe2 heterostructure loaded on carbon cloth, characterized in that, The following steps are involved: Preparation of S1 and ZIF-67@CC precursor: First, carbon cloth (CC) is soaked in cobalt nitrate hexahydrate solution, then 2-methylimidazole solution is added. After being fully dissolved, ZIF-67@CC precursor is obtained by standing at room temperature. Preparation of S2 and Co@CNT@CC: The ZIF-67@CC precursor of S1 was placed in an inert atmosphere, and after adding a catalyst, it was calcined to obtain starfruit-shaped nanosheets Co@CNT@CC with Co nanoparticles supporting in-situ growth of carbon nanotubes; the catalyst was melamine, and the mass ratio of the catalyst to the ZIF-67@CC precursor was 1:

1. Preparation of S3, Co / CoSe2@CNT@CC: Selenium powder was added to the Co@CNT@CC material of S2 at a mass ratio of 1:7-9 to Co@CNT@CC. After calcination under an inert atmosphere, starfruit-shaped carbon nanosheets Co / CoSe2@CNT@CC with a Co / CoSe2 heterostructure were obtained and loaded on a three-dimensional carbon cloth.

2. The method for preparing starfruit-shaped carbon nanosheets containing a Co / CoSe2 heterostructure loaded on carbon cloth according to claim 1, characterized in that, In S1, the concentration of the cobalt nitrate hexahydrate solution is 0.720-0.730 g / 50 mL, and the concentration of the 2-methylimidazole solution is 1.630-1.642 g / 50 mL.

3. The method for preparing starfruit-shaped carbon nanosheets containing a Co / CoSe2 heterostructure loaded on carbon cloth according to claim 1, characterized in that, In S1, the room temperature standing time is 20-30 hours.

4. The method for preparing starfruit-shaped carbon nanosheets containing a Co / CoSe2 heterostructure loaded on carbon cloth according to claim 1, characterized in that, In S2, the calcination process is at 4-6℃·min. -1 The temperature is increased to 700-900℃ and held for 1-3 hours.

5. The method for preparing starfruit-shaped carbon nanosheets containing a Co / CoSe2 heterostructure loaded on carbon cloth according to claim 1, characterized in that, In S2, the calcination process is at 4-6℃·min. -1 The heating rate is increased to 550-600℃ for selenization reaction for 1-3 hours.

6. The method for preparing starfruit-shaped carbon nanosheets containing a Co / CoSe2 heterostructure loaded on carbon cloth according to claim 1, characterized in that, The carbon cloth is cleaned before use: first, it is washed with dilute hydrochloric acid and acetone in sequence, and then it is washed repeatedly with ethanol and water alternately.

7. The method for preparing starfruit-shaped carbon nanosheets containing a Co / CoSe2 heterostructure loaded on carbon cloth according to claim 6, characterized in that, The concentration of the dilute hydrochloric acid is 2-5%, the cleaning time is 15-30 minutes, the cleaning time of the acetone is 5-10 minutes, and the number of times the ethanol and deionized water are used for alternating cleaning is 1-3 times.

8. Starfruit-shaped carbon nanosheets with a Co / CoSe2 heterostructure loaded on carbon cloth, prepared by the preparation method according to any one of claims 1-7.

9. The application of the starfruit-shaped carbon nanosheets containing a Co / CoSe2 heterostructure loaded on carbon cloth as described in claim 8 in the preparation of lithium metal batteries, characterized in that, The starfruit-shaped carbon nanosheets containing a Co / CoSe2 heterostructure loaded on carbon cloth serve as the negative electrode host material or negative electrode material for lithium metal batteries.

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