Preparation method of carbon-loaded metal monatomic composite material and application of carbon-loaded metal monatomic composite material in zinc-iodine battery

Abstract

The invention provides a preparation method of a carbon-loaded metal monatomic composite material. The preparation method comprises the following steps: 1) pretreating a conductive agent; 2) compounding the conductive agent with a metal salt solution; (3) doping g-C3N4; 4) heating the conductive agent to realize g-C3N4 pyrolysis; 5) soaking with dilute acid, filtering and drying; 6) performing vulcanization / halogenation / boronation to obtain a carbon-loaded metal monatomic composite material; the invention also provides an application of the carbon-loaded metal monatomic composite material in a zinc-iodine battery, a positive plate containing the carbon-loaded metal monatomic composite material, and the zinc-iodine battery containing the carbon-loaded metal monatomic composite material. Compared with the prior art, the prepared conductive agent has the advantages that the reversibility, the capacity, the dynamics and the cycle life of the battery are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the field of preparation of carbon-supported metal single-atom composites and their applications in zinc-iodine batteries, and particularly to a method for preparing carbon-supported metal single-atom composites and their applications in zinc-iodine batteries. Background Art

[0002] With the reduction of fossil fuels and the intensification of global climate problems, it is crucial to develop clean, renewable energy and efficient energy storage devices. Aqueous zinc-iodine (Zn-I2) batteries are expected to be substitutes for lithium-ion batteries in the field of stationary energy storage due to their advantages such as low cost, environmental friendliness, and relatively high theoretical capacity. However, the practical application of this battery is limited by the "shuttle effect" (ShE). Aqueous zinc-iodine batteries are low-cost, environmentally friendly, non-flammable, and easy to recycle, with a theoretical capacity of 211 mAh g -1 , a working potential of 1.38 V (vs. Zn 2+ / Zn), and a satisfactory energy density. However, the water-soluble triiodide ion (I3 - ), an intermediate product of the reversible redox reaction of I2 / I - , will migrate from the cathode to the anode during charge and discharge, resulting in irreversible loss of active substances and corrosion of the zinc anode, and thus the battery has low Coulombic efficiency, rapid capacity decay, and poor cycle stability. To solve the ShE, methods such as reformulating the electrolyte and optimizing the separator have been tried. However, many electrolyte formulations are more expensive than typical dilute aqueous electrolytes due to the use of solid / quasi-solid and concentrated electrolytes, and are not economically advantageous; although metal-organic framework or zeolite membrane separators can replace conventional separators to prevent I3 - from migrating from the cathode to the anode, they cannot prevent its dissolution from the cathode; restricting triiodide in a porous host material cannot inhibit the ShE during long-term cycling due to weak physical adsorption. In single-atom catalysts (SACs), all active metal species exist in the form of isolated single atoms, with higher atomic utilization efficiency compared to bulk metals and nanoparticle catalysts, and show strong chemical interactions and high catalytic effects in batteries. In lithium-sulfur batteries, their adsorption ability and catalytic activity have a positive effect on inhibiting polysulfide shuttling and promoting conversion kinetics. It is speculated that SACs may also have strong triiodide adsorption ability and fast conversion kinetics in zinc-iodine batteries, thereby reducing or eliminating the ShE. However, the current understanding of the interaction between SACs and iodine species is insufficient, and it is still challenging to find suitable SACs to inhibit the ShE in zinc-iodine batteries.

[0003] Therefore, it is very necessary to study other means, such as compounding a conductive agent with a metal salt solution, doping g-C3N4 in the conductive agent, etc., to improve the reversibility, capacity, kinetics, and cycle life of the battery. Summary of the Invention

[0004] The object of the present invention is to provide a method for preparing a carbon-supported metal single-atom composite material and its application in a zinc-iodine battery in view of the deficiencies of the prior art, thereby improving the reversibility, capacity, kinetics and cycle life of the battery.

[0005] To achieve the above object, the present invention adopts the following technical solutions: A method for preparing a carbon-supported metal single-atom composite material, comprising the following steps:

[0006] 1) Pretreat the conductive agent to generate active sites conducive to metal loading;

[0007] 2) Compound the conductive agent with a metal salt solution and then dry it;

[0008] 3) Dope g-C3N4 into the conductive agent;

[0009] 4) Heat the conductive agent using a tubular furnace to pyrolyze g-C3N4;

[0010] 5) Immerse the conductive agent in dilute acid, filter and dry;

[0011] 6) Use a tubular furnace to sulfide / halogenate / boronate the conductive agent to obtain a carbon-supported metal single-atom composite material.

[0012] Further, in the above technical solution, in step 1), the conductive agent is selected from at least one of Ketjenblack, SuperC, Super P, Ks-6, single-walled carbon nanotubes or multi-walled carbon nanotubes.

[0013] Further, in the above technical solution, in step 2), the metal salt is selected from any one or a combination of two of scandium chloride, titanocene dichloride, vanadium trichloride, chromium trichloride, manganese chloride, iron chloride, cobalt chloride, copper chloride, zinc acetate, yttrium acetylacetonate, zirconium chloride, niobium trichloride, ammonium molybdate, silver nitrate, cerium chloride, tungsten hexachloride, platinum acetylacetonate, aluminum trichloride, gallium nitrate, indium nitrate, tetraethyl orthosilicate, tin chloride, antimony pentachloride, potassium nitrate, sodium nitrate, ammonium nitrate, sodium sulfate, hydrazine nitrate, mercury nitrate, silver nitrate, sodium nitrate, calcium nitrate, magnesium nitrate, barium nitrate, zinc nitrate, copper nitrate, iron nitrate, ferrous nitrate, nickel nitrate, manganese nitrate, cobalt nitrate, lead nitrate, chromium nitrate, lithium nitrate, tin nitrate, molybdenum nitrate, vanadium nitrate, titanium nitrate, platinum nitrate, mercury nitrate, magnesium sulfate, ammonium sulfate, copper sulfate, calcium sulfate, potassium sulfate, barium sulfate, ferrous sulfate, ferric sulfate, potassium bisulfate, silver sulfate, lead sulfate, chromium sulfate, manganese sulfate, cobalt sulfate, nickel sulfate, potassium alum, chromium sulfate, molybdenum sulfate, vanadium sulfate, ammonium ferrous sulfate, ammonium zinc sulfate, ammonium aluminum sulfate, potassium aluminum sulfate, calcium magnesium sulfate, ammonium ferric sulfate, hydroxylamine sulfate, gold sulfate, platinum sulfate, sodium acetate, potassium acetate, calcium acetate, lead acetate, ammonium acetate, zinc acetate, copper acetate, iron acetate, ferrous acetate, manganese acetate, ammonium acetate, dodecylammonium acetate, octadecylamine acetate, ethanolamine acetate, chromium acetate, bismuth nitrate, and sodium selenite.

[0014] Further, in the above technical solution, in step 3), the feeding mass of g-C3N4 accounts for 5-99% of the total mass of the conductive agent.

[0015] Further, in the above technical solution, in step 4), under the protection of argon / nitrogen, the heating rate of the tubular furnace is controlled at 1-10 °C / min, the decomposition temperature is 600-1600 °C, and the decomposition time is 10-420 min.

[0016] Further, in the above technical solution, in step 5), the acid is selected from hydrochloric acid, sulfuric acid or nitric acid, with a concentration of 0.5-10 mol / L; the soaking time is 30-1660 min.

[0017] Further, in the above technical solution, in step 6), sulfurization is carried out using sulfur or thioacetamide, halogenation is carried out using lithium fluoride, sodium fluoride, lithium chloride, sodium chloride, lithium bromide, sodium bromide, lithium iodide or sodium iodide, and boronation is carried out using boric acid.

[0018] Further, in the above technical solution, in step 6), the specific operation is as follows: place the sulfurization reagent / halogenation reagent / boronation reagent in the upstream area of the gas flow direction in the tubular furnace, place the conductive agent in the downstream area of the gas flow direction in the tubular furnace, control the heating rate of the tubular furnace at 1-20 °C / min, the sulfurization / halogenation / boronation temperature at 200-2000 °C, and the sulfurization / halogenation / boronation time at 60-999 min.

[0019] The present invention also provides a positive electrode sheet for a zinc-iodine battery containing a carbon-supported metal single-atom composite material. The positive electrode sheet for the zinc-iodine battery includes a current collector and a positive electrode material coated on the current collector.

[0020] Further, in the above technical solution, the positive electrode material includes the carbon-supported metal single-atom composite material prepared by the foregoing method and a binder; the binder is selected from one or more of sodium carboxymethyl cellulose, polyvinylidene fluoride, and sodium polyacrylate.

[0021] The present invention also provides a zinc-iodine battery containing a carbon-supported metal single-atom composite material, including: a positive electrode sheet for a zinc-iodine battery, a battery negative electrode sheet, a separator, a housing, and an electrolyte.

[0022] Further, in the above technical solution, the positive electrode material includes the carbon-supported metal single-atom composite material prepared by the foregoing solution and a binder; the binder is selected from one or more of sodium carboxymethyl cellulose, polyvinylidene fluoride, or sodium polyacrylate.

[0023] Further, in the above technical solution, the preparation method of the zinc-iodine battery is to mix and beat the carbon-supported metal single-atom composite material obtained by the foregoing method with a binder, coat it on a current collector to prepare a positive electrode sheet, and then make a zinc-iodine battery containing the positive electrode sheet.

[0024] Advantages of the present invention:

[0025] A. Efficiently adsorb triiodide ions: SACs, due to their own structural characteristics, exhibit strong adsorption force on triiodide ions (I3 - ). For example, SACu@NKB has a strong interaction with I3 - , can adsorb a large amount of I3 - in the solution, making the solution color lighter, and it is not easily redissolved after adsorption. This characteristic effectively inhibits the migration of I3 - from the cathode to the anode in the zinc-iodine battery, that is, the "shuttle effect", avoids the loss of active substances and the corrosion of the zinc anode, and ensures the battery performance.

[0026] B. Accelerate the electrochemical reaction: SACs can significantly accelerate the electrochemical reaction process of I2 / I3 - / I - . Taking SACu as an example, it promotes the reaction of reducing I2 to I - , and the relevant reaction energy barrier is low. In the cyclic voltammetry test, the cathode reduction peak current of SACu@NKB is large and the electrochemical polarization is small; the electrochemical impedance spectrum shows that its charge transfer resistance is low, and the activation energy for participating in the iodine reduction reaction is only 7.382 kJ / mol, and the reaction kinetics is fast, improving the charge and discharge efficiency of the battery.

[0027] C. Optimize the electronic structure: Different SACs metal atoms form different electronic structures with ligands, and the d-band center is crucial for catalytic performance. Theoretical calculations show that a lower d-band center is more conducive to catalytic reactions. For example, the d-band center of SACu is lower than that of SACo, resulting in a lower overpotential in the iodine reduction reaction, enabling the reaction to proceed at a lower energy and improving the overall performance of the battery.

[0028] D. Stabilize the electrode structure: From the perspective of material structure, SACs are loaded on nitrogen-doped Ketjenblack (NKB) to form a stable structure. Taking SACu@NKB as an example, monodispersed Cu single atoms are evenly distributed on the surface of NKB, with a particle size of about 0.3 nm, and Cu exists in the form of mononuclear and metal centers without Cu-Cu coordination. This stable structure helps maintain the performance stability of the battery during charge and discharge and extends the battery cycle life. Description of the Drawings

[0029] Figure 1 For the conductive agent positive zinc-iodine batteries prepared in Comparative Example 3 and Examples 1-4 at 0.2 / 0.5 / 1 / 2 / 5 / 10 / 20 / 50 Ag -1 Rate performance;

[0030] Figure 2 For the conductive agent positive zinc-iodine batteries prepared in Comparative Example 3 and Examples 1-4 at 0.1 Ag -1 Long cycle performance.

[0031] Figure 3 XRD diffraction pattern of Cu@NKB-1000. Detailed Embodiments

[0032] The technical solutions of the present invention will be further described below in combination with specific implementation examples, but the protection scope of the present invention is not limited to the following examples.

[0033] All raw materials used in the implementation examples of the present invention are commercially available.

[0034] Comparative Example 1

[0035] 1) Pretreat 1 g of Ketjenblack by soaking it in 15 mL of ethanol / 15 mL of aqueous solution for 1 h, then loading it into a Teflon-lined hydrothermal autoclave, sealing it, heating it to 340 °C and holding for 24 h. Finally, open the lid of the hydrothermal autoclave, hold at 80 °C for 12 h, and dry the solvent to generate active sites conducive to metal loading on Ketjenblack;

[0036] 2) Take 1 g of Ketjenblack obtained in step 1), compound it with 0.597 g of copper chloride and 30 mL of water, and freeze-dry at -30 °C for 72 h / vacuum-dry at 60 °C for 72 h;

[0037] 3) Immerse the conductive agent obtained in step 2) in 1 mol / L dilute hydrochloric acid for 480 min, then perform suction filtration, washing, and drying to obtain the composite material Cu@NKB.

[0038] Comparative Example 2

[0039] 1) Pretreat 1 g of Ketjenblack by immersing it in 15 mL of ethanol / 15 mL of aqueous solution for 1 h, then place it in a hydrothermal autoclave lined with Teflon, seal it, heat it to 160 °C and keep it warm for 24 h. Finally, open the lid of the hydrothermal autoclave, keep it warm at 80 °C for 12 h, and dry the solvent to generate active sites on Ketjenblack that are beneficial for metal loading.

[0040] 2) Take 1 g of Ketjenblack obtained in step 1), compound it with 0.597 g of copper chloride and 30 mL of water, and perform freeze-drying at -30 °C for 72 h / vacuum drying at 60 °C for 72 h.

[0041] 3) Dope g-C3N4 into the conductive agent obtained in step 2) so that the mass of g-C3N4 fed accounts for 45% of the total mass of the new conductive agent.

[0042] 4) Use a tube furnace to heat the conductive agent obtained in step 3) from room temperature to 1000 °C under argon protection, keep it for 1 h, and then take it out to achieve the pyrolysis of g-C3N4.

[0043] 5) Immerse the conductive agent obtained in step 2) in 1 mol / L dilute hydrochloric acid for 480 min, then perform suction filtration, washing, and drying to obtain the composite material Cu@NKB-1000.

[0044] Comparative Example 3

[0045] 1) Pretreat 1 g of Ketjenblack by immersing it in 15 mL of ethanol / 15 mL of aqueous solution for 1 h, then place it in a hydrothermal autoclave lined with Teflon, seal it, heat it to 160 °C and keep it warm for 24 h. Finally, open the lid of the hydrothermal autoclave, keep it warm at 80 °C for 12 h, and dry the solvent to generate active sites on Ketjenblack that are beneficial for metal loading.

[0046] 2) Take 1 g of Ketjenblack obtained in step 1), compound it with 0.597 g of copper chloride and 30 mL of water, and perform freeze-drying at -30 °C for 72 h / vacuum drying at 60 °C for 72 h.

[0047] 3) Dope g-C3N4 into the conductive agent obtained in step 2) with a mass ratio of copper chloride to g-C3N4 of 1 / 3.

[0048] 4) Under argon protection, control the heating rate of the tubular furnace in step 3) to be 1 °C / min, the decomposition temperature to be 1000 °C, and the decomposition time to be 240 min to achieve the pyrolysis of g-C3N4;

[0049] 5) Immerse the conductive agent obtained in step 2) in 1 mol / L dilute hydrochloric acid for 480 min, and then perform suction filtration, washing, and drying;

[0050] 6) Under argon protection, place the conductive agent obtained in 5) in the downstream area of the gas flow direction in a tubular furnace, and place sulfur in the upstream area of the gas flow direction. Heat it to 350 °C at a rate of 5 °C / min and hold for 320 min for sulfidation to obtain the carbon-supported single-atom metal composite Cu@NKB-1000.

[0051] Example 1

[0052] 1) Pretreat 1 g of Ketjenblack by soaking it in 15 mL of ethanol / 15 mL of aqueous solution for 1 h, then load it into a hydrothermal autoclave lined with Teflon, seal it, heat it to 160 °C and hold for 24 h. Finally, open the lid of the hydrothermal autoclave, hold it at 80 °C for 12 h, and dry the solvent to generate active sites on Ketjenblack that are beneficial for metal loading;

[0053] 2) Take 1 g of Ketjenblack obtained in step 1), compound it with 0.597 g of indium nitrate and 30 mL of water, and freeze-dry it at -30 °C for 72 h / vacuum-dry it at 60 °C for 72 h;

[0054] 3) Dope g-C3N4 into the conductive agent obtained in step 2) so that the feeding mass of g-C3N4 accounts for 45% of the total mass of the new conductive agent;

[0055] 4) Under argon protection, use a tubular furnace to control the heating rate of the tubular furnace in step 3) to be 1 °C / min, the decomposition temperature to be 900 °C, and the decomposition time to be 240 min to achieve the pyrolysis of g-C3N4;

[0056] 5) Immerse the conductive agent obtained in step 2) in 10 mL / L dilute hydrochloric acid for 480 min, and then perform suction filtration, washing, and drying;

[0057] 6) Under argon protection, place the conductive agent obtained in 5) in the downstream area of the gas flow direction in a tubular furnace, and place sulfur in the upstream area of the gas flow direction. Heat it to 350 °C at a rate of 5 °C / min and hold for 320 min for sulfidation to obtain the carbon-supported single-atom metal composite In@NKB-900.

[0058] Example 2

[0059] 1) Pretreat 1 g of Super C by soaking it in 15 mL of ethanol / 15 mL of aqueous solution for 1 h, then loading it into a hydrothermal autoclave with a Teflon liner, sealing it, heating it to 160 °C and holding for 24 h. Finally, open the lid of the hydrothermal autoclave, hold at 80 °C for 12 h, and dry the solvent to generate active sites on Super P that are favorable for metal loading;

[0060] 2) Take 1 g of the Super C obtained in step 1), compound it with 0.597 g of copper chloride and 30 mL of water, and freeze-dry at -30 °C for 72 h / dry in vacuum at 60 °C for 72 h;

[0061] 3) Dope g-C3N4 into the Super C obtained in step 2) such that the mass of the g-C3N4 feed accounts for 45% of the total mass of the conductive agent;

[0062] 4) Under argon protection, use a tube furnace to control the heating rate of the tube furnace in step 3) to 1 °C / min, the decomposition temperature to 950 °C, and the decomposition time to 240 min to achieve the pyrolysis of g-C3N4;

[0063] 5) Soak the conductive agent obtained in step 2) with 1 mol / L dilute sulfuric acid for 480 min, and perform suction filtration, washing, and drying;

[0064] 6) Under argon protection, use a tube furnace to place the conductive agent obtained in 5) in the downstream area of the gas flow direction, and place sulfur in the upstream area of the gas flow direction. Heat it to 350 °C at a rate of 5 °C / min and hold for 320 min for sulfidation to obtain the carbon-supported metal single-atom composite material Cu@NSC-950.

[0065] Example 3

[0066] 1) Pretreat 1 g of Super P by soaking it in 15 mL of ethanol / 15 mL of aqueous solution for 1 h, then loading it into a hydrothermal autoclave with a Teflon liner, sealing it, heating it to 160 °C and holding for 24 h. Finally, open the lid of the hydrothermal autoclave, hold at 80 °C for 12 h, and dry the solvent to generate active sites on Super P that are favorable for metal loading;

[0067] 2) Take 1 g of the Super P obtained in step 1), compound it with 0.597 g of copper chloride and 30 mL of water, and freeze-dry at -30 °C for 72 h / dry in vacuum at 60 °C for 72 h;

[0068] 3) Dope g-C3N4 into the conductive agent obtained in step 2) such that the mass of the g-C3N4 feed accounts for 45% of the total mass of the new conductive agent;

[0069] 4) Under argon protection, use a tube furnace to control the heating rate of the tube furnace in step 3) to 1 °C / min, the decomposition temperature to 700 °C, and the decomposition time to 240 min to achieve the pyrolysis of g-C3N4;

[0070] 5) Immerse the conductive agent obtained in step 2) in 1 mol / L dilute hydrochloric acid for 480 min, and then perform suction filtration, washing, and drying;

[0071] 6) Under argon protection, use a tube furnace to place the conductive agent obtained in 5) in the downstream area of the gas flow direction, and place sulfur in the upstream area of the gas flow direction. Heat it to 350 °C at a rate of 5 °C / min and hold for 320 min for sulfidation to obtain the carbon-supported metal single-atom composite material Cu@NSP-700.

[0072] Example 4

[0073] 1) Pretreat 1 g of Ketjenblack. Immerse Ketjenblack in 15 mL of ethanol / 15 mL of aqueous solution for 1 h, then seal the above materials in a hydrothermal autoclave with a Teflon liner, heat to 160 °C and hold for 24 h. Finally, open the lid of the hydrothermal autoclave, hold at 80 °C for 12 h, and dry the solvent to generate active sites on Ketjenblack that are beneficial for metal loading;

[0074] 2) Take 1 g of Ketjenblack obtained in step 1), compound it with 0.55 g of copper chloride and 30 mL of water, and freeze-dry at -30 °C for 72 h / vacuum-dry at 60 °C for 72 h;

[0075] 3) Dope g-C3N4 into the conductive agent obtained in step 2) so that the feeding mass of g-C3N4 accounts for 45% of the total mass of the new conductive agent;

[0076] 4) Under argon protection, use a tube furnace to control the heating rate of the tube furnace in step 3) to 1 °C / min, the decomposition temperature to 800 °C, and the decomposition time to 240 min to achieve the pyrolysis of g-C3N4;

[0077] 5) Immerse the conductive agent obtained in step 2) in 1 mol / L dilute hydrochloric acid for 480 min, and then perform suction filtration, washing, and drying;

[0078] 6) Under argon protection, use a tube furnace to place the conductive agent obtained in 5) in the downstream area of the gas flow direction, and place sulfur in the upstream area of the gas flow direction. Heat it to 350 °C at a rate of 5 °C / min and hold for 320 min for sulfidation to obtain the carbon-supported metal single-atom composite material Cu@NKB-950.

[0079] Example 5

[0080] 1) Pretreat 1 g of Ketjenblack by soaking it in 15 mL of ethanol / 15 mL of aqueous solution for 1 h, then sealing it in a hydrothermal autoclave with a Teflon liner, heating it to 160 °C and holding for 24 h. Finally, open the lid of the hydrothermal autoclave, hold at 80 °C for 12 h, and dry the solvent to generate active sites on Ketjenblack that are favorable for metal loading;

[0081] 2) Take 1 g of Ketjenblack obtained in step 1), compound it with 0.44 g of indium nitrate and 30 mL of water, and freeze-dry at -30 °C for 72 h / dry in vacuum at 60 °C for 72 h;

[0082] 3) Dope g-C3N4 into the conductive agent obtained in step 2) such that the mass of the g-C3N4 feed accounts for 45% of the total mass of the new conductive agent;

[0083] 4) Under argon protection, use a tube furnace to control the heating rate of the tube furnace in step 3) to 1 °C / min, the decomposition temperature to 750 °C, and the decomposition time to 240 min to achieve the pyrolysis of g-C3N4;

[0084] 5) Soak the conductive agent obtained in step 2) with 1 mol / L dilute hydrochloric acid for 480 min, and then perform suction filtration, washing, and drying;

[0085] 6) Under argon protection, use a tube furnace to place the conductive agent obtained in 5) in the downstream area of the gas flow direction, place sulfur in the upstream area of the gas flow direction, heat it to 350 °C at a rate of 5 °C / min and hold for 320 min for sulfidation to obtain the carbon-supported metal single-atom composite material In@NKB-800.

[0086] Example 6

[0087] 1) Pretreat 1 g of Ketjenblack by soaking it in 15 mL of ethanol / 15 mL of aqueous solution for 1 h, then sealing it in a hydrothermal autoclave with a Teflon liner, heating it to 160 °C and holding for 24 h. Finally, open the lid of the hydrothermal autoclave, hold at 80 °C for 12 h, and dry the solvent to generate active sites on Ketjenblack that are favorable for metal loading;

[0088] 2) Take 1 g of Ketjenblack obtained in step 1), compound it with 0.206 g of cobalt chloride and 30 mL of water, and freeze-dry at -30 °C for 72 h / dry in vacuum at 60 °C for 72 h;

[0089] 3) Dope g-C3N4 into the conductive agent obtained in step 2) such that the mass of the g-C3N4 feed accounts for 45% of the total mass of the new conductive agent;

[0090] 4) Under argon protection, use a tube furnace to control the heating rate of the tube furnace in step 3) to be 1 °C / min, the decomposition temperature to be 750 °C, and the decomposition time to be 240 min to achieve the pyrolysis of g-C3N4;

[0091] 5) Immerse the conductive agent obtained in step 2) in 1 mol / L dilute hydrochloric acid for 480 min, and then perform suction filtration, washing, and drying;

[0092] 6) Under argon protection, use a tube furnace to place the conductive agent obtained in 5) in the downstream area of the gas flow direction, and place sulfur in the upstream area of the gas flow direction. Heat it to 350 °C at a rate of 5 °C / min and hold for 320 min for sulfidation to obtain the carbon-supported single-atom metal composite Co@NKB-750.

[0093] Example 7

[0094] 1) Pretreat 1 g of Ketjenblack, soak Ketjenblack in 15 mL of ethanol / 15 mL of aqueous solution for 1 h, then load it into a hydrothermal autoclave lined with Teflon and seal it. Heat it to 160 °C and hold for 24 h. Finally, open the lid of the hydrothermal autoclave, hold at 80 °C for 12 h, and dry the solvent to make Ketjenblack generate active sites conducive to metal loading;

[0095] 2) Take 1 g of Ketjenblack obtained in step 1), compound it with 0.228 g of anhydrous zinc acetate and 30 mL of water, and freeze-dry at -30 °C for 72 h / vacuum-dry at 60 °C for 72 h;

[0096] 3) Dope g-C3N4 into the conductive agent obtained in step 2) so that the feeding mass of g-C3N4 accounts for 45% of the total mass of the new conductive agent;

[0097] 4) Under argon protection, use a tube furnace to control the heating rate of the tube furnace in step 3) to be 1 °C / min, the decomposition temperature to be 750 °C, and the decomposition time to be 240 min to achieve the pyrolysis of g-C3N4;

[0098] 5) Immerse the conductive agent obtained in step 2) in 1 mol / L dilute hydrochloric acid for 480 min, and then perform suction filtration, washing, and drying;

[0099] 6) Under argon protection, use a tube furnace to place the conductive agent obtained in 5) in the downstream area of the gas flow direction, and place sulfur in the upstream area of the gas flow direction. Heat it to 350 °C at a rate of 5 °C / min and hold for 320 min for sulfidation to obtain the carbon-supported single-atom metal composite Zn@NKB-750.

[0100] Example 8

[0101] 1) Pretreat 1 g of Ketjenblack by soaking it in 15 mL of ethanol / 15 mL of aqueous solution for 1 h. Then, seal the above materials in a Teflon-lined hydrothermal autoclave, heat it to 160 °C and keep it warm for 24 h. Finally, open the lid of the hydrothermal autoclave, keep it warm at 80 °C for 12 h, and dry the solvent to generate active sites on Ketjenblack that are beneficial for metal loading;

[0102] 2) Take 1 g of Ketjenblack obtained in step 1), compound it with 0.466 g of aluminum trichloride and 30 mL of water, and freeze-dry it at -30 °C for 72 h / vacuum-dry it at 60 °C for 72 h;

[0103] 3) Dope g-C3N4 into the conductive agent obtained in step 2) so that the mass of the g-C3N4 feed accounts for 45% of the total mass of the new conductive agent;

[0104] 4) Under argon protection, use a tube furnace to control the heating rate of the tube furnace in step 3) to be 1 °C / min, the decomposition temperature to be 750 °C, and the decomposition time to be 240 min to achieve the pyrolysis of g-C3N4;

[0105] 5) Soak the conductive agent obtained in step 2) with 1 mol / L dilute hydrochloric acid for 480 min, and perform suction filtration, washing, and drying;

[0106] 6) Under argon protection, use a tube furnace to place the conductive agent obtained in 5) in the downstream area of the gas flow direction, and place sulfur in the upstream area of the gas flow direction. Heat it to 350 °C at a rate of 5 °C / min and keep it warm for 320 min for sulfidation to obtain the carbon-supported metal single-atom composite material Al@NKB-750.

[0107] Example 9

[0108] 1) Pretreat 1 g of Ketjenblack by soaking it in 15 mL of ethanol / 15 mL of aqueous solution for 1 h. Then, seal it in a Teflon-lined hydrothermal autoclave, heat it to 160 °C and keep it warm for 24 h. Finally, open the lid of the hydrothermal autoclave, keep it warm at 80 °C for 12 h, and dry the solvent to generate active sites on Ketjenblack that are beneficial for metal loading;

[0109] 2) Compound 1 g of Ketjenblack obtained in step 1) with 0.800 g of stannous dichloride and 30 mL of water, and freeze-dry it at -30 °C for 72 h / vacuum-dry it at 60 °C for 72 h;

[0110]

[0111] ​4) Under argon protection, use a tube furnace to control the heating rate of the tube furnace in step 3) to be 1 °C / min, the decomposition temperature to be 750 °C, and the decomposition time to be 240 min to achieve the pyrolysis of g-C3N4;

[0112] 5) Immerse the conductive agent obtained in step 2) in 1 mol / L dilute hydrochloric acid for 480 min, and then perform suction filtration, washing, and drying;

[0113] 6) Under argon protection, use a tube furnace to place the conductive agent obtained in 5) in the downstream area of the gas flow direction, and place sulfur in the upstream area of the gas flow direction. Heat it to 350 °C at a rate of 5 °C / min and hold for 320 min for sulfidation to obtain the carbon-supported metal single-atom composite material Sn@NKB-750.

[0114] Example 10

[0115] 1) Pretreat 1 g of Ketjenblack. Immerse Ketjenblack in 15 mL of ethanol / 15 mL of aqueous solution for 1 h, then load it into a hydrothermal autoclave lined with Teflon and seal it. Heat it to 160 °C and hold for 24 h. Finally, open the lid of the hydrothermal autoclave, hold it at 80 °C for 12 h, and dry the solvent to generate active sites beneficial for metal loading on Ketjenblack;

[0116] 2) Take 1 g of Ketjenblack obtained in step 1), compound it with 0.195 g of ferric chloride and 30 mL of water, and freeze-dry it at -30 °C for 72 h / vacuum-dry it at 60 °C for 72 h;

[0117] 3) Dope g-C3N4 into the conductive agent obtained in step 2) so that the feeding mass of g-C3N4 accounts for 45% of the total mass of the new conductive agent;

[0118] 4) Under argon protection, use a tube furnace to control the heating rate of the tube furnace in step 3) to be 1 °C / min, the decomposition temperature to be 800 °C, and the decomposition time to be 240 min to achieve the pyrolysis of g-C3N4;

[0119] 5) Immerse the conductive agent obtained in step 2) in 1 mol / L dilute hydrochloric acid for 480 min, and then perform suction filtration, washing, and drying;

[0120] 6) Under argon protection, use a tube furnace to place the conductive agent obtained in 5) in the downstream area of the gas flow direction, and place sulfur in the upstream area of the gas flow direction. Heat it to 350 °C at a rate of 5 °C / min and hold for 320 min for sulfidation to obtain the carbon-supported metal single-atom composite material FE@NKB-800.

[0121] Example 11

[0122] The carbon-supported single-atom metal composite materials obtained in Comparative Example 3 and Examples 1-3 were mixed and slurried with 5% PVDF by mass in a mass ratio of 9:1, coated on a current collector to prepare a positive electrode sheet, and then a button cell containing the positive electrode sheet was fabricated.

[0123] As can be seen from the drawings, under the conditions of Comparative Example 3 and Examples 2 and 3: at 0.2 A g -1 condition, the capacitance of Cu@NKB-1000 is 156 mAh g -1 , the capacitance of Cu@NSC-800 is 142 mAh g -1 , the capacitance of Cu@NSP-800 is 134.5 mAh g -1 , it can be seen that Cu@NKB-800 has the best rate performance.

[0124] From the data, it can be seen that for SACu@NKB, it has a strong interaction with I3 - , can adsorb a large amount of I3 in the solution - , making the solution color lighter, and it is not easy to redissolve after adsorption. This property effectively inhibits the migration of I3 in the zinc-iodine battery - from the cathode to the anode, that is, the "shuttle effect", avoiding the loss of active substances and the corrosion of the zinc anode, and ensuring the battery performance.

[0125] Under the conditions of Comparative Example 3 and Example 1 in the drawings: at 0.2 A g -1 condition, the capacitance of Cu@NKB-950 is 156 mAh g-1, and the capacitance of Cu@NKB-1000 is 149 mAh g -1 , it can be seen that Cu@NKB-950 has the best rate performance ( Figure 1 ): at 0.1 A g -1 condition, the capacitance of Cu@NKB-950 is 222 mAh g -1 , and the capacitance of Cu@NKB-1000 is 210 mAh g -1 , it can be seen that Cu@NKB-950 has better long-cycle performance ( Figure 2 ).

[0126] In the present invention, g-C3N4 is pyrolyzed at 950 °C in an argon atmosphere, so that g-C3N4 fully reacts with single-atom metals at this temperature to generate the target product. If the temperature is too low, the reaction is difficult to proceed, and if it is too high, the product may decompose or other side reactions may occur.

Claims

1. A method for preparing a carbon-supported metal single-atom composite material, characterized in that, It includes the following steps: 1) Pretreat the conductive agent to generate active sites conducive to metal loading; 2) Compound the conductive agent with a metal salt solution and then dry it; 3) Dope g-C3N4 into the conductive agent; 4) Heat the conductive agent in a tube furnace to pyrolyze g-C3N4; 5) Immerse the conductive agent in dilute acid, filter and dry it; 6) Use a tube furnace to sulfidize / halogenate / borylate the conductive agent to obtain a carbon-supported single-atom metal composite material.

2. The preparation method of the carbon-supported metal single-atom composite material according to claim 1, wherein: In step 1), the conductive agent is selected from at least one of Ketjenblack, Super C, Super P, Ks-6, single-walled carbon nanotubes or multi-walled carbon nanotubes.

3. The preparation method of the carbon-supported metal single-atom composite material according to claim 1, wherein: In step 2), the metal salt is selected from any one or a combination of two of scandium chloride, titanocene dichloride, vanadium trichloride, chromium trichloride, manganese chloride, iron chloride, cobalt chloride, copper chloride, zinc acetate, yttrium acetylacetonate, zirconium chloride, niobium trichloride, ammonium molybdate, silver nitrate, cerium chloride, tungsten hexachloride, platinum acetylacetonate, aluminum trichloride, gallium nitrate, indium nitrate, tetraethyl orthosilicate, tin chloride, antimony pentachloride, potassium nitrate, sodium nitrate, ammonium nitrate, sodium sulfate, hydrazine nitrate, mercury nitrate, silver nitrate, sodium nitrate, calcium nitrate, magnesium nitrate, barium nitrate, zinc nitrate, copper nitrate, iron nitrate, ferrous nitrate, nickel nitrate, manganese nitrate, cobalt nitrate, lead nitrate, chromium nitrate, lithium nitrate, tin nitrate, molybdenum nitrate, vanadium nitrate, titanium nitrate, platinum nitrate, mercury nitrate, magnesium sulfate, ammonium sulfate, copper sulfate, calcium sulfate, potassium sulfate, barium sulfate, ferrous sulfate, ferric sulfate, potassium bisulfate, silver sulfate, lead sulfate, chromium sulfate, manganese sulfate, cobalt sulfate, nickel sulfate, potassium alum, chromium sulfate, molybdenum sulfate, vanadium sulfate, ammonium ferrous sulfate, ammonium zinc sulfate, ammonium aluminum sulfate, potassium aluminum sulfate, calcium magnesium sulfate, ammonium ferric sulfate, sulfamic acid, gold sulfate, platinum sulfate, sodium acetate, potassium acetate, calcium acetate, lead acetate, ammonium acetate, zinc acetate, copper acetate, iron acetate, ferrous acetate, manganese acetate, ammonium dodecyl acetate, octadecylamine acetate, ethanolamine acetate, chromium acetate, bismuth nitrate and sodium selenite.

4. The preparation method of the carbon-supported metal single-atom composite material according to claim 1, wherein: In step 3), the feeding mass of g-C3N4 accounts for 5-99% of the total mass of the conductive agent.

5. The preparation method of the carbon-supported metal single-atom composite material according to claim 1, wherein: In step 4), under the protection of argon / nitrogen, control the heating rate of the tube furnace to be 1-10 °C / min, the pyrolysis temperature to be 300-1600 °C, and the pyrolysis time to be 10-420 min.

6. The preparation method of the carbon-supported metal single-atom composite material according to claim 1, characterized in that: In step 5), the acid is selected from hydrochloric acid, sulfuric acid or nitric acid, with a concentration of 0.5-10 mol / L; the soaking time is 30-1660 min.

7. The preparation method of the carbon-supported single-atom metal composite material according to claim 1, characterized in that: In step 6), sulfur is used for sulfidation, or thioacetamide; lithium fluoride, sodium fluoride, lithium chloride, sodium chloride, lithium bromide, sodium bromide, lithium iodide or sodium iodide is used for halogenation; boric acid is used for borylation; the operation is to place the sulfidation reagent / halogenation reagent / borylation reagent in the upstream area of the gas flow direction in the tube furnace, and place the conductive agent in the downstream area of the gas flow direction in the tube furnace, control the heating rate of the tube furnace to be 1-20 °C / min, the sulfidation / halogenation / borylation temperature to be 200-1500 °C, and the sulfidation / halogenation / borylation time to be 60-999 min.

8. The positive electrode sheet of a zinc-iodine battery with a carbon-supported metal single-atom composite material, characterized in that: The positive electrode sheet of the zinc-iodine battery comprises a current collector and a positive electrode material coated on the current collector, and the positive electrode material comprises a carbon-supported metal single-atom composite material prepared by any method of claims 1-7 and a binder.

9. The positive electrode sheet of the zinc-iodine battery according to claim 8, characterized in that: The binder is selected from one or more of sodium carboxymethyl cellulose, polyvinylidene fluoride, and sodium polyacrylate.

10. A zinc-iodine battery with a carbon-supported metal single-atom composite material, characterized in that, Comprising: A positive electrode sheet of a zinc-iodine battery, a battery negative electrode sheet, a separator, a housing, and an electrolyte; the positive electrode material comprises a carbon-supported metal single-atom composite material prepared by any method of claims 1-7 and a binder; the binder is selected from one or more of sodium carboxymethyl cellulose, polyvinylidene fluoride, or sodium polyacrylate.

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