Preparation method of cose2-decorated porous carbon cloth
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NANJING UNIV OF POSTS & TELECOMM
- Filing Date
- 2022-05-12
- Publication Date
- 2026-06-23
Smart Images
Figure CN114914416B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for preparing CoSe2-decorated porous carbon cloth, belonging to the field of materials preparation technology. Background Technology
[0002] With the rapid development of flexible and wearable devices, the demand for flexible power sources is increasing, providing power for the stable operation of flexible displays, wearable devices, and other devices under mechanical deformation. This context has, in turn, spurred research and development into flexible batteries. As an important branch of lithium batteries, lithium-sulfur (Li-S) batteries, with their ultra-high theoretical capacity (1675 mAh g⁻¹), have become increasingly popular. -1 The availability and affordability of sulfur resources have made it a key direction for the future development of lithium-ion batteries, and significant progress has been made in practical applications, gaining widespread acceptance. Applying flexible lithium-sulfur batteries to power flexible wearable devices can achieve higher energy densities, providing longer battery life for flexible devices and equipment. However, the shuttle effect of polysulfides and the formation of lithium dendrites still severely restrict the development of flexible Li-S batteries. Furthermore, flexible Li-S batteries require high performance even under bending, folding, or stretching conditions, necessitating a certain degree of flexibility in all battery components. The positive electrode, negative electrode, and separator, as key components of lithium-sulfur batteries, play a decisive role in the mechanical and electrochemical performance of flexible lithium-sulfur batteries.
[0003] To date, much research has focused on developing stable lithium anodes and high coulombic efficiency sulfur-containing cathodes, including designing artificial solid electrolyte interphase (SEI) layers, using electrolyte additives, and developing lithium substrates with high specific surface areas. On the cathode side, metal oxides, sulfides, nitrides, and carbon-based materials are used as sulfur storage carriers to reduce the "shuttle effect" of polysulfides through physical confinement and chemical adsorption. Simultaneously, designing and modifying the separator has become an effective means of suppressing polysulfide shuttle. Despite rapid research progress, even state-of-the-art technologies cannot avoid the use of excess lithium; compared to sulfur-containing cathodes, lithium metal anodes typically use 15-150 times more excess lithium. Furthermore, poor lithium dendrite growth in flexible Li-S batteries leads to poor battery performance; parasitic side reactions occur when lithium metal anodes contact soluble lithium polysulfides (LiPS), causing rapid capacity decay; and poor mechanical flexibility remains a limiting factor. The development of flexible Li-S batteries is a crucial factor. Therefore, there is an urgent need to design and match the three key components of lithium-sulfur batteries: the positive electrode, the negative electrode, and the separator. For flexible lithium-sulfur full batteries, excellent battery performance often requires comprehensive consideration of battery components such as the positive and negative electrodes. Research on designing only the positive or negative electrode often has limitations and is difficult to meet practical application requirements. At the same time, for the overall structure of flexible batteries, excellent bending resistance and high energy density are usually mutually exclusive; achieving good flexibility typically requires introducing redundancy in capacity to release stress within the battery. Therefore, a balance needs to be found between flexibility and battery capacity to design and fabricate flexible lithium-sulfur batteries that meet the requirements.
[0004] There are three main aspects to improve the performance of flexible lithium-sulfur batteries: 1) suppressing the dissolution of polysulfides (LiPS); 2) stabilizing LiPS by adjusting the solvation structure, reducing the activity of LiPS and thus weakening the corrosion of lithium metal anode; 3) optimizing SEI or strengthening bulk Li metal protection of lithium metal anode, reducing the amount of lithium metal used, and achieving a smaller N / P ratio of 16.
[0005] Numerous research findings demonstrate that designing integrated, functionalized sulfur and lithium storage carriers to limit and adsorb polysulfides, accelerate electrochemical reaction kinetics, and suppress the "shuttle effect" can, to some extent, protect the lithium anode and improve battery performance. Simultaneously, developing lithium metal anodes with high specific surface area, reducing the nucleation barrier of lithium metal on the current collector, and suppressing the formation and growth of lithium dendrites also play a crucial role in achieving lower N / P ratio full cells and improving electrode flexibility. Summary of the Invention
[0006] The technical problem to be solved by the present invention is to provide a method for preparing CoSe2-modified bifunctional porous carbon cloth and apply it to flexible lithium-sulfur full cells to achieve efficient assembly loading of sulfur active material and precise control of lithium metal content. This effectively solves the contradiction between high sulfur loading, high sulfur utilization and excessive lithium metal anode, and achieves high loading, long life, low N / P ratio and high sulfur utilization in flexible lithium-sulfur full cells.
[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0008] A method for preparing and applying CoSe2-modified bifunctional porous carbon cloth includes the following steps:
[0009] Step S1: Clean the hydrophilic carbon cloth and use a solvent method to coat the ZIF-67 dodecahedron onto the carbon cloth fiber network (CC@ZIF67).
[0010] Step S2: The CC@ZIF-67 obtained in step S1 is subjected to high-temperature annealing and carbonization under an argon-hydrogen mixed atmosphere to prepare carbonized CC@Co.
[0011] Step S3: Anneal the CC@Co carbonized in step S2 in air to obtain cobalt tetroxide coated carbon nanofibers (CC@Co3O4);
[0012] Step S4: The CC@Co3O4 obtained from the annealing in step S3 is selenized using selenium powder under an argon atmosphere to obtain CC@CoSe2.
[0013] Step S5: Using the CC@CoSe2 obtained from selenization in step S4 as a carrier material, sulfur is deposited onto the CC@CoSe2 porous network by plasma chemical vapor deposition, thereby preparing CC@CoSe2 / S composite sulfur-containing cathode material;
[0014] Step S6: Using the CC@CoSe2 obtained from selenization in step S4 as a carrier material, lithium metal is deposited onto the CC@CoSe2 porous network by electrodeposition, thereby preparing the CC@CoSe2 / Li composite lithium metal anode material;
[0015] In step S7, the CC@CoSe2 / S composite sulfur-containing cathode material and CC@CoSe2 / Li composite lithium metal anode material prepared in steps S5 and S6 are used as the cathode and anode materials of lithium-sulfur batteries, respectively, and their electrochemical performance is tested. At the same time, the cathode and anode are applied to flexible lithium-sulfur full batteries.
[0016] Furthermore, in step S1, the carbon cloth is cleaned by ultrasonication with ethanol and acetone for 30 minutes each.
[0017] Furthermore, in step S1, the ZIF67 dodecahedral carbon fiber network is coated using a solvent method. The chemical reagents used are 2 mmol cobalt nitrate (0.582 g) and 16 mmol 2-methylimidazole (1.3136 g), which are added to 40 ml of methanol solution and ultrasonically stirred until fully dissolved.
[0018] Furthermore, in step S1, the experimental method for preparing ZIF67 dodecahedral coated carbon fiber network using the solvent method is to add 16 mmol of 2-methylimidazole (1.3136 g) solution to 2 mmol of cobalt nitrate (0.582 g) solution, stir rapidly for 5 min, then place the carbon cloth in a beaker and let it stand for 8-12 h. The resulting CC@ZIF67 is then washed three times each with methanol and ethanol, and dried in an oven at 60 °C for 12 h.
[0019] Furthermore, in step S2, the CC@ZIF-67 obtained in step S1 is subjected to high-temperature annealing and carbonization under an argon-hydrogen mixed atmosphere. The annealing conditions are 700°C for 2 hours to prepare carbonized CC@Co.
[0020] Further in step S3, the CC@Co carbonized in step S2 is annealed in air at 500°C for 2-8 hours to obtain cobalt tetroxide-coated carbon nanofibers (CC@Co3O4).
[0021] Furthermore, in step S4, the CC@Co3O4 obtained by annealing in step S3 is selenized using selenium powder under an argon atmosphere. The selenization conditions are 600℃ for 4-8 hours to obtain CC@CoSe2.
[0022] Furthermore, in step S5, the CC@CoSe2 obtained from selenization in step S4 is used as a carrier material, and sulfur is deposited onto the CC@CoSe2 porous network by plasma chemical vapor deposition. The plasma is oxygen plasma, and the solid source used is sublimated sulfur.
[0023] Furthermore, in step S6, the CC@CoSe2 obtained from selenization in step S4 is used as a carrier material, and the deposition current used to deposit metallic lithium onto the CC@CoSe2 porous network by electrodeposition is 0.1-2 mA cm⁻¹. -2 ;
[0024] Furthermore, in step S7, the CC@CoSe2 obtained from selenization in step S4 is used as a carrier material, and lithium metal is deposited onto the CC@CoSe2 porous network by electrodeposition, with a deposition amount of 1-10 mAh cm⁻¹. -2 ;
[0025] Furthermore, in step S7, the CC@CoSe2 / S composite sulfur-containing cathode material and the CC@CoSe2 / Li composite lithium metal anode material from steps S5 and S6 are applied to flexible lithium-sulfur full batteries, with an electrochemical testing window of 1.7-2.8V.
[0026] Compared with the prior art, the beneficial effects of the present invention are as follows: The CC@CoSe2 / S cathode material and CC@CoSe2 / Li anode material with dual-function self-supporting porous structure prepared by the present invention integrate high conductivity, high loading capacity, excellent sulfur limiting ability and suppression of lithium dendrites. It comprehensively utilizes the functions of CC@CoSe2 material in lithium-sulfur full batteries in terms of efficient sulfur fixation and catalytic conversion, and realizes the construction of electrodes with high sulfur loading capacity, high packing density, high sulfur utilization rate and low nucleation barrier.
[0027] The present invention has the following significant advantages:
[0028] (1) A bifunctional CC@Co3O4 self-supporting electrode was prepared by a highly efficient and convenient solvent method and thermal annealing method. The synthesis process is simple and fast, which significantly shortens the development cycle of the electrode and reduces the preparation cost.
[0029] (2) During the several heat annealing processes of CC@ZIF67, as the annealing temperature increases, the time is extended and the annealing atmosphere changes, the product continuously self-assembles to form well-morphological porous carbon cloth supported CoSe2 nanocatalytic units. At the same time, the micromorphology and nanoscale size of the catalytic units can be controlled by changing the reaction time, temperature and atmosphere, which provides a certain reference for preparing well-morphological porous carbon cloth supported nanocatalytic units.
[0030] (3) The prepared bifunctional CC@Co3O4 self-supporting electrode material was loaded with 2 mg cm⁻¹ via plasma-enhanced chemical vapor deposition. -2 Sulfur was used as an integrated positive electrode to assemble a lithium-sulfur half-cell for testing at 0.5C (1C = 1675 mA g). -1 At a charge / discharge current of ), the initial capacity is 1076 mAh g. -1 After 80 cycles, it still maintains 885.7mAh g. -1 Specific capacity; loaded with 10mAh cm⁻¹ via electrodeposition technique. -2 Lithium metal was used as an integrated negative electrode to assemble a symmetrical cell for testing at 1 mA cm⁻¹. -2At a current density, the deposition amount was 1 mAh cm⁻¹. -2 After 500 hours of cycling, the composite anode still maintained good electrochemical stability, with low overpotentials for lithium-ion insertion and extraction. A flexible lithium-sulfur full cell was assembled using the above-loaded sulfur cathode and lithium-storage anode, and its performance was tested at 5 mg / cm². -2 Sulfur loading, 0.5 (1C = 1675 mA g) -1 At a charge / discharge current of ), the initial specific capacity can reach 848.5 mAh g. -1 After 100 stable cycles at a current density of 0.5C, the reversible discharge capacity still reaches 122.5 mAh g. -1 Flexible pouch batteries possess excellent flexibility and electrochemical performance, meeting the needs of industrial production. Attached Figure Description
[0031] Figure 1 These are scanning electron microscope (SEM) images from the present invention, wherein (a) is a microscopic morphology image of the carbon cloth after cleaning, (b) is a SEM image of the carbon cloth after ZIF67 growth, (c) is a SEM image of CC@ZIF67 after annealing at high temperature and oxidation in air, and (d) is a SEM image of CC@CoSe2.
[0032] Figure 2 The X-ray diffraction patterns of the materials in this invention are shown, where (a) is ZIF67, (b) is Co3O4, and (c) is carbon cloth (CC) and CC@CoSe2.
[0033] Figure 3 The CC@CoSe2 / S self-supporting electrode in this invention is loaded with 2 mg cm⁻¹ -2 Sulfur was used as an integrated positive electrode to assemble a lithium-sulfur half-cell for testing. The cycling performance at a charge-discharge current of 0.5C is shown in the figure.
[0034] Figure 4 In this invention, CC@CoSe2 is loaded with 10 mAh cm⁻¹ using electrodeposition technology. -2 Lithium metal was used as an integrated negative electrode to assemble a symmetrical cell for testing at 1 mA cm⁻¹. -2 At a current density, the deposition amount was 1 mAh cm⁻¹. -2 Electrochemical performance test diagram.
[0035] Figure 5 In this invention, a flexible lithium-sulfur assembly is constructed using CC@CoSe2 / S as the positive electrode and CC@CoSe2 / Li as the negative electrode. (The last sentence appears to be incomplete and possibly refers to a specific process or method.) -2 Sulfur loading, 0.1 / 0.5C (1C = 1675 mA g) -1 Charging and discharging cycle performance diagram based on current density. Detailed Implementation
[0036] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.
[0037] Example 1
[0038] (1) Preparation method of CoSe2 modified bifunctional porous carbon cloth
[0039] First, the hydrophilic carbon cloth was cleaned by sonicating with ethanol and acetone for 30 minutes each, and then dried in a vacuum drying oven for 12 hours. Next, 2 mmol of cobalt nitrate (0.582 g) and 16 mmol of 2-methylimidazole (1.3136 g) were added to 40 ml of methanol solution and sonicated until fully dissolved. The 16 mmol... A 2-methylimidazole (1.3136 g) solution was added to a 2 mmol cobalt nitrate (0.582 g) solution and stirred rapidly for 5 min. The carbon cloth was then placed in a beaker and allowed to stand for 8 h to obtain CC@ZIF67. The carbon cloth was washed three times each with methanol and ethanol and dried in an oven at 60 °C for 12 h. Next, the obtained CC@ZIF67 was subjected to high-temperature carbonization annealing for 2 h under an argon-hydrogen mixed atmosphere to obtain CC@Co. The CC@Co was then annealed in air at 500 °C for 2 h to obtain cobalt tetroxide-coated carbon nanofibers (CC@Co3O4). Finally, the annealed CC@Co3O4 was selenized using selenium powder at 600 °C for 6 h under an argon atmosphere to obtain CC@CoSe2.
[0040] (2) Preparation method of CC@CoSe2 / S self-supported sulfur-loaded electrode
[0041] Selenized CC@CoSe2 was used as a sulfur carrier material. Sulfur was deposited onto the CC@CoSe2 porous network via plasma-enhanced chemical vapor deposition at a temperature of 155℃ for 2 hours, with a sulfur loading of 2 mg / cm³. -2 Thus, a CC@CoSe2 / S composite sulfur-containing cathode material was prepared.
[0042] (3) Preparation method of CC@CoSe2 / Li self-supporting lithium storage electrode
[0043] Selenization-derived CC@CoSe2 was used as a carrier material to deposit metallic lithium via electrodeposition at 1 mA cm⁻¹. -2 With a current density of 10 h, the lithium metal storage density is 10 mAh cm⁻¹. -2Thus, CC@CoSe2 / Li composite lithium metal anode material was prepared.
[0044] (4) CoSe2 modified bifunctional porous carbon cloth is used as a sulfur-loaded positive electrode and lithium storage negative electrode in lithium-sulfur batteries.
[0045] The prepared CC@CoSe2 / S composite sulfur-containing cathode and CC@CoSe2 / Li composite lithium metal anode were used as the cathode and anode materials for lithium-sulfur batteries, respectively, and their related electrochemical performance was tested: CC@Co3O4 / S self-supporting electrode loaded with 2mg cm⁻¹ -2 Sulfur was used as an integrated positive electrode to assemble a lithium-sulfur half-cell, and charge-discharge tests were conducted at a current density of 0.5C. A 10mAh cm⁻¹ was loaded onto CC@CoSe₂ using electrodeposition technology. -2 Lithium metal is used as an integrated negative electrode to assemble a symmetrical cell at 1 mA cm⁻¹. -2 At a current density, the deposition amount was 1 mAh cm⁻¹. -2 Electrochemical performance testing was conducted on a flexible lithium-sulfur assembly with CC@CoSe2 / S as the positive electrode and CC@CoSe2 / Li as the negative electrode, at a concentration of 5 mg / cm³. -2 Sulfur loading, 0.1 / 0.5C (1C = 1675 mA g) -1 Charge-discharge cycle performance test based on current density.
[0046] Example 2
[0047] (1) Preparation method of CoSe2 modified bifunctional porous carbon cloth
[0048] First, the hydrophilic carbon cloth was cleaned by sonicating with ethanol and acetone for 30 minutes each, and then dried in a vacuum drying oven for 12 hours. Next, 2 mmol of cobalt nitrate (0.582 g) and 16 mmol of 2-methylimidazole (1.3136 g) were added to 80 ml of methanol solution and sonicated until fully dissolved. The 16 mmol... A 2-methylimidazole (1.3136 g) solution was added to a 2 mmol cobalt nitrate (0.582 g) solution and stirred rapidly for 60 min. The carbon cloth was then placed in a beaker and allowed to stand for 12 h to obtain CC@ZIF67. The carbon cloth was washed three times each with methanol and ethanol and then dried in an oven at 60 °C for 12 h. Next, the obtained CC@ZIF67 was subjected to high-temperature carbonization annealing for 2 h under an argon-hydrogen mixed atmosphere to obtain CC@Co. The CC@Co was then annealed in air at 500 °C for 2 h to obtain cobalt tetroxide-coated carbon nanofibers (CC@Co3O4). Finally, the annealed CC@Co3O4 was selenized using selenium powder at 600 °C for 6 h under an argon atmosphere to obtain CC@CoSe2.
[0049] (2) Preparation method of CC@CoSe2 / S self-supported sulfur-loaded electrode
[0050] Selenized CC@CoSe2 was used as a sulfur carrier material. Sulfur was deposited onto the CC@CoSe2 porous network via plasma-enhanced chemical vapor deposition at a temperature of 155℃ for 2 hours, with a sulfur loading of 2 mg / cm³. -2 Thus, a CC@CoSe2 / S composite sulfur-containing cathode material was prepared.
[0051] (3) Preparation method of CC@CoSe2 / Li self-supporting lithium storage electrode
[0052] Selenization-derived CC@CoSe2 was used as a carrier material to deposit metallic lithium via electrodeposition at 1 mA cm⁻¹. -2 With a current density of 10 h, the lithium metal storage density is 10 mAh cm⁻¹. -2 Thus, CC@CoSe2 / Li composite lithium metal anode material was prepared.
[0053] (4) CoSe2 modified bifunctional porous carbon cloth is used as a sulfur-loaded positive electrode and lithium storage negative electrode in lithium-sulfur batteries.
[0054] The prepared CC@CoSe2 / S composite sulfur-containing cathode and CC@CoSe2 / Li composite lithium metal anode were used as the cathode and anode materials for lithium-sulfur batteries, respectively, and their related electrochemical performance was tested: CC@Co3O4 / S self-supporting electrode loaded with 2mg cm⁻¹ -2 Sulfur was used as an integrated positive electrode to assemble a lithium-sulfur half-cell, and charge-discharge tests were conducted at a current density of 0.5C. A 10mAh cm⁻¹ was loaded onto CC@CoSe₂ using electrodeposition technology. -2 Lithium metal is used as an integrated negative electrode to assemble a symmetrical cell at 1 mA cm⁻¹. -2 At a current density, the deposition amount was 1 mAh cm⁻¹. -2 Electrochemical performance testing was conducted on a flexible lithium-sulfur assembly with CC@CoSe2 / S as the positive electrode and CC@CoSe2 / Li as the negative electrode, at a concentration of 5 mg / cm³. -2 Sulfur loading, 0.1 / 0.5C (1C = 1675 mA g) -1 Charge-discharge cycle performance test based on current density.
[0055] Example 3
[0056] (1) Preparation method of CoSe2 modified bifunctional porous carbon cloth
[0057] First, the hydrophilic carbon cloth was cleaned by sonicating with ethanol and acetone for 30 minutes each, and then dried in a vacuum drying oven for 12 hours. Next, 2 mmol of cobalt nitrate (0.582 g) and 16 mmol of 2-methylimidazole (1.3136 g) were added to 80 ml of methanol solution and sonicated until fully dissolved. The 16 mmol... A 2-methylimidazole (1.3136 g) solution was added to a 2 mmol cobalt nitrate (0.582 g) solution and stirred rapidly for 60 min. The carbon cloth was then placed in a beaker and allowed to stand for 12 h to obtain CC@ZIF67. The carbon cloth was washed three times each with methanol and ethanol and then dried in an oven at 60 °C for 12 h. Next, the obtained CC@ZIF67 was subjected to high-temperature carbonization annealing for 4 h under an argon-hydrogen mixed atmosphere to obtain CC@Co. The CC@Co was then annealed in air at 400 °C for 2 h to obtain cobalt tetroxide-coated carbon nanofibers (CC@Co3O4). Finally, the annealed CC@Co3O4 was selenized using selenium powder at 500 °C for 4 h under an argon atmosphere to obtain CC@CoSe2.
[0058] (2) Preparation method of CC@CoSe2 / S self-supported sulfur-loaded electrode
[0059] Selenized CC@CoSe2 was used as a sulfur carrier material. Sulfur was deposited onto the CC@CoSe2 porous network via plasma-enhanced chemical vapor deposition at a temperature of 155℃ for 2 hours, with a sulfur loading of 2 mg / cm³. -2 Thus, a CC@CoSe2 / S composite sulfur-containing cathode material was prepared.
[0060] (3) Preparation method of CC@CoSe2 / Li self-supporting lithium storage electrode
[0061] Selenization-derived CC@CoSe2 was used as a carrier material to deposit metallic lithium via electrodeposition at 1 mA cm⁻¹. -2 With a current density of 10 h, the lithium metal storage density is 10 mAh cm⁻¹. -2 Thus, CC@CoSe2 / Li composite lithium metal anode material was prepared.
[0062] (4) CoSe2 modified bifunctional porous carbon cloth is used as a sulfur-loaded positive electrode and lithium storage negative electrode in lithium-sulfur batteries.
[0063] The prepared CC@CoSe2 / S composite sulfur-containing cathode and CC@CoSe2 / Li composite lithium metal anode were used as the cathode and anode materials for lithium-sulfur batteries, respectively, and their related electrochemical performance was tested: CC@Co3O4 / S self-supporting electrode loaded with 2mg cm⁻¹ -2Sulfur was used as an integrated positive electrode to assemble a lithium-sulfur half-cell, and charge-discharge tests were conducted at a current density of 0.5C. A 10mAh cm⁻¹ was loaded onto CC@CoSe₂ using electrodeposition technology. -2 Lithium metal is used as an integrated negative electrode to assemble a symmetrical cell at 1 mA cm⁻¹. -2 At a current density, the deposition amount was 1 mAh cm⁻¹. -2 Electrochemical performance testing was conducted on a flexible lithium-sulfur assembly with CC@CoSe2 / S as the positive electrode and CC@CoSe2 / Li as the negative electrode, at a concentration of 5 mg / cm³. -2 Sulfur loading, 0.1 / 0.5C (1C = 1675 mA g) -1 Charge-discharge cycle performance test based on current density.
[0064] Example 4
[0065] (1) Preparation method of CoSe2 modified bifunctional porous carbon cloth
[0066] First, the hydrophilic carbon cloth was cleaned by sonicating with ethanol and acetone for 30 minutes each, and then dried in a vacuum drying oven for 12 hours. Next, 2 mmol of cobalt nitrate (0.582 g) and 16 mmol of 2-methylimidazole (1.3136 g) were added to 40 ml of methanol solution and sonicated until fully dissolved. The 16 mmol... A 2-methylimidazole (1.3136 g) solution was added to a 2 mmol cobalt nitrate (0.582 g) solution and stirred rapidly for 5 min. The carbon cloth was then placed in a beaker and allowed to stand for 8 h to obtain CC@ZIF67. The carbon cloth was washed three times each with methanol and ethanol and dried in an oven at 60 °C for 12 h. Next, the obtained CC@ZIF67 was subjected to high-temperature carbonization annealing for 2 h under an argon-hydrogen mixed atmosphere to obtain CC@Co. The CC@Co was then annealed in air at 500 °C for 2 h to obtain cobalt tetroxide-coated carbon nanofibers (CC@Co3O4). Finally, the annealed CC@Co3O4 was selenized using selenium powder at 600 °C for 6 h under an argon atmosphere to obtain CC@CoSe2.
[0067] (2) Preparation method of CC@CoSe2 / S self-supported sulfur-loaded electrode
[0068] Selenized CC@CoSe2 was used as a sulfur carrier material. Sulfur was deposited onto the CC@CoSe2 porous network via plasma-enhanced chemical vapor deposition at a temperature of 200℃ for 4 hours, with a sulfur loading of 8 mg / cm³. -2 Thus, a CC@CoSe2 / S composite sulfur-containing cathode material was prepared.
[0069] (3) Preparation method of CC@CoSe2 / Li self-supporting lithium storage electrode
[0070] Selenization-derived CC@CoSe2 was used as a carrier material to deposit metallic lithium via electrodeposition at 1 mA cm⁻¹. -2 At a current density of 5 h, the lithium metal storage density was 5 mAh cm⁻¹. -2 Thus, CC@CoSe2 / Li composite lithium metal anode material was prepared.
[0071] (4) CoSe2 modified bifunctional porous carbon cloth is used as a sulfur-loaded positive electrode and lithium storage negative electrode in lithium-sulfur batteries.
[0072] The prepared CC@CoSe2 / S composite sulfur-containing cathode and CC@CoSe2 / Li composite lithium metal anode were used as the cathode and anode materials for lithium-sulfur batteries, respectively, and their related electrochemical performance was tested: CC@Co3O4 / S self-supporting electrode loaded with 2mg cm⁻¹ -2 Sulfur was used as an integrated positive electrode to assemble a lithium-sulfur half-cell, and charge-discharge tests were conducted at a current density of 0.5C. A 5mAh cm⁻¹ was loaded onto CC@CoSe₂ using electrodeposition technology. -2 Lithium metal is used as an integrated negative electrode to assemble a symmetrical cell at 1 mA cm⁻¹. -2 At a current density, the deposition amount was 1 mAh cm⁻¹. -2 Electrochemical performance testing; flexible lithium-sulfur assembly with CC@CoSe2 / S as the positive electrode and CC@CoSe2 / Li as the negative electrode was tested at 8 mg / cm³. -2 Sulfur loading, 0.1 / 0.5C (1C = 1675 mA g) -1 Charge-discharge cycle performance test based on current density.
[0073] Relevant characterizations of the embodiments:
[0074] Figure 1 The images shown are scanning electron microscope (SEM) images. (a) is a microscopic image of the carbon cloth after cleaning; (b) is a SEM image of the carbon cloth after ZIF67 growth; (c) is a SEM image of CC@ZIF67 after high-temperature annealing and oxidation in air; and (d) is a SEM image of CC@CoSe2. Analysis of the SEM images shows that ZIF67 is uniformly grown within the carbon cloth fiber network. Furthermore, the carbon cloth fibers exhibit numerous porous structures on their surface after carbonization and oxidation, and the selenized CoSe2 maintains a good microscopic morphology at the nanoscale.
[0075] Figure 2The X-ray diffraction patterns of the materials are shown. (a) represents ZIF67, (b) represents Co3O4, and (c) represents carbon cloth (CC) and CC@CoSe2. Analysis of the XRD lattice diffraction patterns reveals that the coated ZIF67 exhibits excellent crystallinity, with the standard characteristic peaks of the composite ZIF67. Furthermore, after oxidation in air, the ZIF67 nanostructure transforms into Co3O4 crystals, which are then completely converted to CoSe2 after high-temperature selenization. Comparison with the characteristic peaks of the carbon cloth clearly shows the diffraction peaks of CC@CoSe2 coated on the carbon cloth, demonstrating the successful preparation of CoSe2-modified bifunctional porous carbon cloth.
[0076] Figure 3 2 mg cm⁻¹ was loaded onto the CC@Co₃O₄ / S self-supporting electrode. -2 Using sulfur as an integrated cathode, lithium-sulfur half-cells were assembled and tested. The cycle performance diagram at a charge-discharge current of 0.5C demonstrates that CC@Co3O4, as a sulfur-loaded cathode, has excellent effects on the adsorption and catalysis of polysulfides.
[0077] Figure 4 10 mAh cm⁻¹ was loaded onto CC@CoSe₂ using electrodeposition technology. -2 Lithium metal was used as an integrated negative electrode to assemble a symmetrical cell for testing at 1 mA cm⁻¹. -2 At a current density, the deposition amount was 1 mAh cm⁻¹. -2 The electrochemical performance test results show that the CC@CoSe2 / Li composite anode can effectively suppress the growth of lithium dendrites, reduce the nucleation barrier of Li metal, and help extend the service life of the lithium metal anode.
[0078] Figure 5 A flexible lithium-sulfur full cell assembled with CC@CoSe2 / S as the positive electrode and CC@CoSe2 / Li as the negative electrode, at 5 mg cm⁻¹ -2 Sulfur loading, 0.1 / 0.5C (1C = 1675 mA g) -1 The charge-discharge cycle performance diagram based on current density demonstrates that the prepared CC@CoSe2 bifunctional electrode material can effectively improve the lifespan of flexible lithium-sulfur batteries while exhibiting excellent electrochemical performance.
[0079] The preparation and electrochemical performance of CC@CoSe2 / S∥Li half-cells were tested:
[0080] The prepared CC@CoSe2 / S and commercial lithium foil were used as the positive and negative electrodes of a lithium-sulfur battery, respectively. 1 mol / L lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and 1 wt% LiNO3 were dissolved in a 1:1 volume ratio of 1,3-dioxolane DOL + ethylene glycol dimethyl ether (DME) as the electrolyte. The lithium-sulfur battery was tested at 2.0 mg / cm³. -2 Charge-discharge cycle tests were conducted under sulfur loading. The TiN nanowire film nitrided at 900℃ showed good performance at 0.5C (1C = 1675 mA g). -1 At a charge / discharge current of 0.5C (1C = 1675mA g), -1 At a charge / discharge current of ), the initial capacity is 1076 mAh g. -1 After 80 cycles, it still maintains 885.7 mAh g. -1 It has a high specific capacity and excellent charge / discharge performance.
[0081] The fabrication and electrochemical performance of CC@CoSe2 / Li∥CC@CoSe2 / Li symmetric cells were tested.
[0082] The two prepared chips had a loading capacity of 10 mAh cm⁻¹ -2 A lithium-ion CC@CoSe2 / Li composite anode was used as the positive and negative electrodes of a coin cell, respectively. 1 mol / L lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and 1 wt% LiNO3 were dissolved in a 1:1 volume ratio of 1,3-dioxolane DOL + ethylene glycol dimethyl ether (DME) as the electrolyte. At 1 mA cm⁻¹ -2 At a current density, the deposition amount was 1 mAh cm⁻¹. -2 After 500 hours of cycling, the composite anode still maintains good electrochemical stability, with low overpotentials for lithium ion insertion and extraction.
[0083] The preparation and electrochemical performance of a flexible lithium-sulfur full cell (CC@CoSe2 / S∥CC@CoSe2 / Li) were tested.
[0084] CC@CoSe2 / S and CC@CoSe2 / Li were used as the positive and negative electrodes of a lithium-sulfur battery, respectively. 1 mol / L lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and 1 wt% LiNO3 were dissolved in a 1:1 volume ratio of 1,3-dioxolane DOL + ethylene glycol dimethyl ether (DME) as the electrolyte. The CC@CoSe2 / S∥CC@CoSe2 / Li lithium-sulfur full cell was tested at 5.0 mg / cm³. -2 Charge-discharge cycle tests were conducted under sulfur load. At 0.1 (1C = 1675 mA g) -1 At a charge / discharge current of ), the initial specific capacity can reach 848.5 mAh g. -1After 100 stable cycles at a current density of 0.5C, the reversible discharge capacity still reaches 122.5 mAh g. -1 Flexible pouch batteries possess excellent flexibility and electrochemical performance, meeting the needs of industrial production.
[0085] It should be noted that the above embodiments are illustrative of the present invention and not restrictive of the present invention, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims.
Claims
1. A method for preparing CoSe2-modified bifunctional porous carbon cloth, characterized in that: The specific steps include the following: Step S1: The hydrophilic carbon cloth is cleaned, and ZIF-67 dodecahedrons are coated onto the carbon cloth fiber network using a solvent method to obtain ZIF-67 coated carbon cloth fibers, namely CC@ZIF67. Step S2: The CC@ZIF-67 obtained in step S1 is subjected to high-temperature annealing and carbonization under an argon-hydrogen mixed atmosphere. The annealing conditions are 700℃ for 2 hours to prepare the carbonized CC@Co. Step S3: Anneal the CC@Co carbonized in step S2 in air at 500°C for 2-8 hours to obtain cobalt tetroxide-coated carbon nanofibers CC@Co3O4. Step S4: The CC@Co3O4 obtained by annealing in step S3 is selenized with selenium powder under an argon atmosphere. The selenization conditions are 600℃ for 4-8 hours to obtain CC@CoSe2. Step S5: Using the CC@CoSe2 obtained from selenization in step S4 as a carrier material, sulfur is deposited onto the CC@CoSe2 porous network by plasma chemical vapor deposition, thereby preparing CC@CoSe2 / S composite sulfur-containing cathode material; Step S6: Using the CC@CoSe2 obtained from selenization in step S4 as a carrier material, lithium metal is deposited onto the CC@CoSe2 porous network by electrodeposition, thereby preparing the CC@CoSe2 / Li composite lithium metal anode material; In step S7, the CC@CoSe2 / S composite sulfur-containing cathode material and CC@CoSe2 / Li composite lithium metal anode material from steps S5 and S6 are used as the cathode and anode materials of lithium-sulfur batteries, respectively, and their electrochemical performance is tested. At the same time, the cathode and anode are applied to flexible lithium-sulfur full batteries.
2. The method for preparing CoSe2-modified bifunctional porous carbon cloth according to claim 1, characterized in that: In step S1, the carbon cloth is cleaned by ultrasonication for 30 minutes each using ethanol and acetone. ZIF67 dodecahedral carbon fiber network was coated using a solvent method. The chemical reagents used were 2 mmol cobalt nitrate (0.582 g) and 16 mmol 2-methylimidazole (1.3136 g), which were added to 40 ml of methanol solution and dissolved by ultrasonic stirring.
3. The method for preparing CoSe2-modified bifunctional porous carbon cloth according to claim 2, characterized in that: In step S1, the experimental method for preparing the ZIF67 dodecahedral-coated carbon fiber network using the solvent method is as follows: 16 mmol of 2-methylimidazole solution and 2 mmol of cobalt nitrate solution are added to methanol to prepare a solution with a concentration of 0.05 mol / L. -1 and 0.4 mol L -1 The solution was stirred rapidly for 5 minutes, then the carbon cloth was placed in a beaker and allowed to stand for 8-12 hours. The resulting CC@ZIF67 was then washed three times each with methanol and ethanol and dried in an oven at 60°C for 12 hours.
4. The method for preparing CoSe2-modified bifunctional porous carbon cloth according to claim 1, characterized in that: In step S5, the CC@CoSe2 obtained from selenization in step S4 is used as a carrier material, and sulfur is deposited onto the CC@CoSe2 porous network by plasma chemical vapor deposition. The plasma is oxygen plasma, and the solid source used is sublimated sulfur.
5. The method for preparing CoSe2-modified bifunctional porous carbon cloth according to claim 1, characterized in that: In step S6, the CC@CoSe2 obtained from selenization in step S4 is used as a carrier material, and lithium metal is deposited onto the CC@CoSe2 porous network by electrodeposition using a deposition current of 0.1-2 mA cm⁻¹. -2 .
6. The method for preparing CoSe2-modified bifunctional porous carbon cloth according to claim 1, characterized in that: In step S7, the CC@CoSe2 obtained from selenization in step S4 is used as a carrier material, and lithium metal is deposited onto the CC@CoSe2 porous network by electrodeposition, with a deposition amount of 1-10 mAh cm⁻¹. -2 .
7. The method for preparing CoSe2-modified bifunctional porous carbon cloth according to claim 1, characterized in that: In step S7, the CC@CoSe2 / S composite sulfur-containing cathode material and the CC@CoSe2 / Li composite lithium metal anode material from steps S5 and S6 are applied to flexible lithium-sulfur full batteries, with an electrochemical testing window of 1.7-2.8V.