Metal-loaded ultralight graphene aerogel for lithium-sulfur battery and preparation method of metal-loaded ultralight graphene aerogel

Abstract

The invention provides metal-loaded ultra-light graphene aerogel for a lithium-sulfur battery and a preparation method of the metal-loaded ultra-light graphene aerogel, and belongs to the field of new energy storage. According to the method, a liquid nitrogen rapid freezing method is adopted, and the metal-loaded ultralight graphene aerogel is obtained. The aerogel provided by the invention has the advantages of light weight, good conductivity, large specific surface area and the like, and is beneficial to adsorption of polysulfide. Meanwhile, the metal particles loaded on the surface of the aerogel can effectively inhibit the shuttle effect and improve the electrode reaction kinetics. Besides, the flexible and conductive graphene aerogel not only can bear volume expansion of sulfur in the lithiation process, but also is beneficial to electron transfer, so that the electrochemical stability of the sulfur positive electrode can be effectively improved. When the composite material is applied to a lithium-sulfur battery, a series of problems of'shuttle effect 'caused by polysulfide, poor rate capability and poor cycling stability caused by poor conductivity of short-chain polysulfide and the like of the lithium-sulfur battery are solved.

Description

Technical Field

[0001] The present invention relates to the field of new energy storage, and in particular to a metal-loaded ultralight graphene aerogel for lithium-sulfur batteries and a preparation method thereof. Background Art

[0002] With the exhaustion of fossil energy and global warming, energy issues have become increasingly prominent. Traditional fossil energy can hardly meet the development needs of today's society, and the development of new energy has become particularly important. At present, vigorously developing clean and efficient renewable energy has become one of the key points of technology research and development and key breakthroughs in the energy field. After new energy vehicles replaced previous fuel vehicles, they saved fossil energy while avoiding environmental pollution caused by carbon emissions. For new energy electric vehicles, high-performance new energy batteries are essential.

[0003] As a new type of battery, lithium-sulfur battery has the advantages of high energy density, low cost and low toxicity, and has received extensive attention from scientific researchers. However, the inherent problems of lithium-sulfur batteries have seriously hindered its commercialization process. For example, during the charge and discharge process of lithium-sulfur batteries, lithium polysulfide will dissolve in the electrolyte to cause a "shuttle effect" and poor cycle stability; at the same time, the discharge product (Li2S2 / Li2S) of lithium-sulfur batteries is insulating, which is not conducive to the high rate performance of the battery. In recent years, aerogels have been used as excellent sulfur-carrying materials due to their light weight, low density, good conductivity and large specific surface area. The aerogels after high-temperature carbonization have high conductivity, which can not only physically adsorb polysulfides, but also withstand the volume expansion of sulfur during the lithiation process, and can effectively improve the electrochemical performance of the sulfur positive electrode. However, relying on the van der Waals force physical adsorption between non-polar carbon and polar polysulfides, the effect of improving the electrochemical stability and kinetic performance of the sulfur positive electrode is limited. Based on this, the present invention proposes a method for preparing metal-loaded ultra-light graphene aerogels for lithium-sulfur batteries. Summary of the invention

[0004] The purpose of this article is to solve the problems existing in the above-mentioned prior art and to provide a metal-loaded ultra-light graphene aerogel for lithium-sulfur batteries and a preparation method thereof.

[0005] The purpose of the present invention is achieved in this way: an aerogel with a stable mechanical structure is obtained by using a liquid nitrogen rapid freezing technology. And by introducing metal ions into the aerogel, an ultra-light graphene aerogel with surface metal loading is obtained after high-temperature annealing. Since the metal nanoparticles have a high Fermi energy level, a part of the electrons easily flow from the metal particles to the carbon substrate, resulting in a rearrangement of the electron cloud structure, generating a built-in electric field at the interface between the metal particles and the carbon, further strengthening the adsorption of polysulfides and the deposition of lithium sulfide, and giving the hybrid a higher conductivity.

[0006] The present invention provides an ultralight graphene aerogel loaded with metal particles, wherein the metal-loaded ultralight graphene aerogel is a directional three-dimensional structure; the mass of the metal-loaded ultralight graphene aerogel is 0.3-0.4 g, and the density is 0.03-0.04 g / cm 3 , with a specific surface area of ​​120 to 130 m 2 / g; the metal-loaded ultralight graphene aerogel is uniformly coated with metal particles, and the particle size of the metal particles is 5.5 to 6 nm.

[0007] The present invention further provides a method for preparing metal-loaded ultralight graphene aerogel, comprising the following steps:

[0008] Step 1: After dissolving acetate, graphene oxide and chitosan in an acetic acid aqueous solution, the mixture is first quickly frozen in a liquid nitrogen environment and then freeze-dried in a vacuum;

[0009] Step 2: placing the freeze-dried sample in a tubular furnace for annealing to obtain aerogel after high-temperature carbonization; washing the aerogel in a sulfuric acid aqueous solution, and continuing to freeze-dry to obtain metal-loaded ultra-light graphene aerogel;

[0010] Furthermore, in step 1, the acetate is one or more of cobalt acetate, nickel acetate and ferric acetate; the mass ratio of the acetate, chitosan and graphene oxide is (600-700):(400-500):(10-30); the concentration of acetic acid is 80%-90%, and the volume ratio of acetic acid to deionized water is (0.7-0.9):(40-60).

[0011] Furthermore, in step 1, the freezing time in the liquid nitrogen environment is 20 to 30 minutes; the vacuum freeze drying pressure is less than 30 Pa, the temperature is -70°C to -60°C, and the time is 48 to 72 hours;

[0012] Furthermore, in step 2, the annealing temperature is 700-900°C, the time is 60-180 min, and the concentration of the sulfuric acid aqueous solution is 1-2 mol L -1 .

[0013] The present invention further provides an application of a metal-loaded ultralight graphene aerogel, wherein the metal-loaded ultralight graphene aerogel and sublimated sulfur powder are hydrothermally treated to obtain a metal particle-loaded ultralight graphene aerogel composite sulfur material; the metal particle-loaded ultralight graphene aerogel composite sulfur material is mixed with conductive carbon black and a binder to form a slurry, which is coated on an aluminum foil to obtain a metal-loaded ultralight graphene aerogel composite sulfur cathode; the metal-loaded ultralight graphene aerogel composite sulfur cathode is applied to the assembly of a lithium-sulfur battery.

[0014] Furthermore, the lithium-sulfur battery is assembled by encapsulating a metal-loaded ultralight graphene aerogel composite sulfur cathode and a metal lithium sheet anode in a battery shell, the cathode and the anode are separated by a diaphragm, and both sides of the diaphragm are filled with electrolyte.

[0015] Furthermore, the mass ratio of the metal-loaded ultralight graphene aerogel to the sublimated sulfur powder is (30-50):(50-70); the hydrothermal reaction temperature is 150-160° C., and the time is 12-24 hours.

[0016] Furthermore, the mass ratio of the metal-loaded ultralight graphene aerogel composite sulfur cathode material, conductive carbon black and binder is (60-80): (10-20): (10-20).

[0017] Furthermore, the diaphragm is a polypropylene diaphragm; the metal lithium anode is a high-purity lithium foil with a thickness of 0.1 to 0.3 mm; the electrolyte is selected from one or more mixed solutions of lithium nitrate, lithium bisimide, 1,3-dioxolane and 1,2-dimethoxyethane, with a concentration of 0.5 to 3 mol L -1 .

[0018] The beneficial effect is that a graphene aerogel with a layered structure is obtained by rapid freezing with liquid nitrogen and vacuum freeze drying, and the aerogel obtained by this method can achieve a stable multilayer structure and uniform metal loading. The present invention provides a metal-loaded ultra-light graphene aerogel for lithium-sulfur batteries. The aerogel has the advantages of light weight, good conductivity and large specific surface area, and sulfur and polysulfide can be embedded in the aerogel sheet structure, which is beneficial to the physical adsorption of polysulfide. At the same time, the catalytic conversion effect of metal particles loaded on the surface of the aerogel is utilized to suppress the "shuttle effect" to the maximum extent, and the electrode reaction kinetics of the lithium-sulfur battery is improved. In addition, the flexible and conductive graphene aerogel can not only withstand the volume expansion of sulfur during the lithiation process, but also facilitate the transfer of electrons, and can effectively improve the electrochemical stability of the sulfur positive electrode. It can be seen that the application of the metal-loaded ultra-light graphene aerogel provided by the present invention to lithium-sulfur batteries can solve a series of problems faced by lithium-sulfur batteries in the past, such as the "shuttle effect" caused by polysulfides, the poor rate performance caused by the poor conductivity of short-chain polysulfides, and the poor cycle stability.

[0019] The present invention adopts liquid nitrogen rapid freezing technology to prepare a metal-loaded ultra-light graphene aerogel for lithium-sulfur batteries. The lithium-sulfur battery with the aerogel as the host still maintains 495.8 mAh g after 300 cycles at 1.0C rate. -1 The aerogel also has good rate performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a photo of the precursor of the metal cobalt-loaded ultralight graphene aerogel according to Example 1 of the present invention;

[0021] Figure 2 This is a scanning electron microscope photograph of the metal cobalt-loaded ultralight graphene aerogel after annealing in Example 1 of the present invention;

[0022] Figure 3 This is a transmission electron microscope photograph of the metal cobalt-loaded ultralight graphene aerogel before acid washing in Comparative Example 1 of the present invention;

[0023] Figure 4 This is a transmission electron microscope photograph of the metal cobalt-loaded ultralight graphene aerogel after acid washing in Example 1 of the present invention;

[0024] Figure 5 This is a calculation table of the mass and density of the metal cobalt-loaded ultralight graphene aerogel before and after high-temperature carbonization in Example 1 of the present invention;

[0025] Figure 6 This is a specific surface area diagram of the metal cobalt-loaded ultralight graphene aerogel provided in Example 1 of the present invention after high-temperature carbonization and acid washing;

[0026] Figure 7 It is a rate performance diagram of a lithium-sulfur battery assembled by combining the metal cobalt-loaded ultralight graphene aerogel and sulfur before and after acid washing provided in Example 1 of the present invention and Comparative Example 1;

[0027] Figure 8 It is a cycle performance diagram of a lithium-sulfur battery assembled by combining metal-loaded ultralight graphene aerogel with sulfur before and after acid washing provided in Example 1 of the present invention and Comparative Example 1 at a current of 1.0C. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0029] The present invention provides a metal-loaded ultralight graphene aerogel for lithium-sulfur batteries and a preparation method thereof. The overall concept of this embodiment is to prepare an ultralight graphene aerogel loaded with metal particles, which has the advantages of light weight, good conductivity and large specific surface area. The high conductivity can overcome the insulation of short-chain polysulfides, and the large specific surface area can accommodate more sulfur and improve the capacity of the battery. At the same time, the metal particles loaded on the surface of the aerogel can promote the catalytic conversion of polysulfides, effectively inhibit the "shuttle effect", and improve the electrode reaction kinetics.

[0030] The technical scheme claimed in the present invention is further described below by some examples and accompanying drawings. However, the examples are used to explain the embodiments of the present invention and do not exceed the scope of the subject matter of the present invention, and the protection scope of the present invention is not limited by the examples. Unless otherwise specified, the materials and reagents used in the present invention can be obtained from commercial products in the field.

[0031] The invention discloses a lithium-sulfur battery. The lithium-sulfur battery comprises an aerogel composite sulfur cathode and a metal lithium sheet anode encapsulated in a battery shell, the cathode and the anode are separated by a diaphragm, and both sides of the diaphragm are filled with electrolyte; the aerogel is a metal-loaded ultra-light graphene aerogel, and the aerogel composite sulfur cathode is a sulfur cathode that is coated on an aluminum foil in a certain proportion after the aerogel is carbonized at high temperature and pickled with a sulfuric acid solution and then hydrothermally treated with sulfur, conductive carbon, and a binder.

[0032] The present invention further discloses a method for preparing a lithium-sulfur battery, comprising the following steps:

[0033] Step 1: Dissolve acetate, graphene oxide, and chitosan in acetic acid solution, stir evenly, and then freeze rapidly in liquid nitrogen environment, freeze-dry in a vacuum dryer, and anneal the sample in a tube furnace to obtain metal-loaded ultralight graphene aerogel. Wash most of the metal clusters from the obtained aerogel in a sulfuric acid aqueous solution, filter until neutral, and then freeze-dry;

[0034] In step 1, the mass ratio of acetate, chitosan and graphene oxide is (600-700): (400-500): (10-30); the concentration of acetic acid is 80%-90%, and the volume ratio of acetic acid to deionized water is (0.7-0.9): (40-60); the freezing time in the liquid nitrogen environment is 20-30 min; the vacuum freeze drying pressure is less than 30 Pa, the temperature is -70°C to -60°C, and the time is 48-72 h; the annealing temperature is 700-900°C, and the time is 60-180 min; the concentration of the sulfuric acid aqueous solution is 1-2 mol L -1 .

[0035] Step 2: Grind the obtained sample and sublimated sulfur in a mortar, transfer the obtained powder to an autoclave, and perform a hydrothermal reaction. Obtain a metal-loaded ultralight graphene aerogel composite sulfur cathode material; the mass ratio of the sample to the sublimated sulfur is (30-50): (50-70); the hydrothermal temperature is 150-160°C.

[0036] Step 3: Mix the metal-loaded ultralight graphene aerogel composite sulfur cathode material obtained in step 1, conductive carbon black and a binder to form a slurry, and coat the slurry on an aluminum foil to obtain a metal-loaded ultralight graphene aerogel composite sulfur cathode;

[0037] In step three, the mass ratio of the metal-loaded ultralight graphene aerogel composite sulfur cathode material, conductive carbon black and binder is (60-80): (10-20): (10-20).

[0038] Step 4: Assemble the metal-loaded ultra-light graphene aerogel composite sulfur cathode, separator, metal lithium sheet anode and electrolyte obtained in step 2 into a button battery, which is a lithium-sulfur battery with metal-loaded ultra-light graphene aerogel modified positive electrode material;

[0039] In step 4, the diaphragm is a polypropylene diaphragm; the metal lithium anode in step 3 is a high-purity lithium foil with a thickness of 0.1 to 0.3 mm; the electrolyte in step 3 is selected from one or more mixed aqueous solutions of lithium nitrate, lithium bisimide, 1,3-dioxolane and 1,2-dimethoxyethane, with a concentration of 0.5 to 3 mol L -1 .

[0040] Example 1

[0041] 1. Preparation of metal-loaded ultra-light graphene aerogel:

[0042] (1) 622.5 mg acetate ((CH3COO)2Co), 480 mg chitosan ((C6H 11 NO4)n) and 20 mg of graphene oxide (rGO) and 80 μL of acetic acid were dissolved in 50 mL of deionized water (DI) to obtain a uniform solution; the resulting solution was then quickly frozen in a liquid nitrogen environment for 0.3 h, and freeze-dried in a freeze dryer at a pressure of less than 30 Pa and a temperature of -70°C for 48 h to obtain a purple aerogel.

[0043] (2) The obtained aerogel was placed in a tubular furnace and heated at 5 °C min under N2 atmosphere. -1 The temperature was raised to 800 °C at a heating rate and maintained for 2 h. The high-temperature carbonized aerogel was acid-washed in 100 mL of 1 M sulfuric acid solution for 24 h.

[0044] (3) The obtained aerogel and sublimated sulfur were ground in a mortar at a mass ratio of 4:6, and the obtained powder was transferred to an autoclave and hydroheated at 155°C for 15 h under an argon atmosphere to obtain a metal-loaded ultra-light graphene aerogel composite sulfur positive electrode material.

[0045] 2. Preparation of metal-loaded ultra-light graphene aerogel composite sulfur cathode:

[0046] The metal-loaded ultralight graphene aerogel composite sulfur cathode material, conductive carbon black and binder were uniformly mixed in a mass ratio of 70:20:10 to prepare a slurry; then, the obtained slurry was coated on an aluminum foil, and the coating amount of the slurry was 2.0 mg cm based on the area of ​​the substrate. -2Finally, the electrode coated with the mixed slurry was dried in a vacuum oven for 12 h to obtain a metal-loaded ultra-light graphene aerogel composite sulfur cathode.

[0047] 3. Assembling a lithium-sulfur battery with metal-loaded ultra-light graphene aerogel composite sulfur cathode material:

[0048] (1) Place the negative electrode shell flat on the panel with the opening facing upward;

[0049] (2) placing a spring sheet and a current collector on the negative electrode shell in sequence;

[0050] (3) Placing a lithium metal sheet on a current collector;

[0051] (4) placing the diaphragm on the metal lithium sheet;

[0052] (5) adding 3-5 drops of electrolyte on the diaphragm to wet the diaphragm;

[0053] (6) placing the prepared metal-loaded ultralight graphene aerogel composite sulfur electrode downward at the center of the diaphragm;

[0054] (7) covering the positive electrode shell to obtain a preliminary lithium-sulfur battery with a metal-loaded ultra-light graphene aerogel composite sulfur positive electrode;

[0055] (8) Pressing the preliminary battery obtained in step (7) at a pressure of 50 MPa to obtain a lithium-sulfur battery device with a metal-loaded ultra-light graphene aerogel composite sulfur positive electrode.

[0056] Comparative Example 1

[0057] 1. Preparation of un-acid-washed metal-loaded ultralight graphene aerogel:

[0058] (1) 622.5 mg acetate ((CH3COO)2Co), 480 mg chitosan ((C6H 11 NO4)n) and 20 mg of graphene oxide (rGO) and 80 μL of acetic acid were dissolved in 50 mL of deionized water (DI) to obtain a uniform solution; the resulting solution was then quickly frozen in a liquid nitrogen environment for 0.3 h, and freeze-dried in a freeze dryer at a pressure of less than 30 Pa and a temperature of -70°C for 48 h to obtain a purple aerogel.

[0059] (2) The obtained aerogel was placed in a tubular furnace and heated at 5 °C min under N2 atmosphere. -1 The temperature was raised to 800 °C at a heating rate and maintained for 2 h.

[0060] (3) The obtained aerogel and sublimated sulfur were ground in a mortar at a mass ratio of 4:6, and the obtained powder was transferred to an autoclave and hydroheated at 155°C for 15 h under an argon atmosphere to obtain an unacid-washed metal-loaded ultralight graphene aerogel composite sulfur positive electrode material.

[0061] 2. Preparation of un-acid-washed metal-loaded ultra-light graphene aerogel composite sulfur cathode:

[0062] The un-acid-washed metal-loaded ultralight graphene aerogel composite sulfur cathode material, conductive carbon black and binder were uniformly mixed in a mass ratio of 70:20:10 to prepare a slurry; then, the obtained slurry was coated on an aluminum foil, and the coating amount of the slurry was 2.0 mg cm based on the area of ​​the substrate. -2 Finally, the electrode coated with the mixed slurry was dried in a vacuum oven for 12 h to obtain an un-acid-washed metal-loaded ultralight graphene aerogel composite sulfur cathode.

[0063] 3. Assembling un-acid-washed metal-loaded ultra-light graphene aerogel composite sulfur cathode material lithium-sulfur battery:

[0064] (1) Place the negative electrode shell flat on the panel with the opening facing upward;

[0065] (2) placing a spring sheet and a current collector on the negative electrode shell in sequence;

[0066] (3) Placing a lithium metal sheet on a current collector;

[0067] (4) placing the diaphragm on the metal lithium sheet;

[0068] (5) adding 3-5 drops of electrolyte on the diaphragm to wet the diaphragm;

[0069] (6) placing the prepared un-acid-washed metal-loaded ultralight graphene aerogel composite sulfur electrode downward at the center of the diaphragm;

[0070] (7) covering the positive electrode shell to obtain a lithium-sulfur battery with an initial metal-loaded ultra-light graphene aerogel composite sulfur positive electrode that has not been acid-washed;

[0071] (8) Pressing the preliminary battery obtained in step (7) at a pressure of 50 MPa to obtain a lithium-sulfur battery device with an un-acid-washed metal-loaded ultra-light graphene aerogel composite sulfur positive electrode.

[0072] Test Case

[0073] The morphology of the above metal-loaded ultralight graphene aerogels was characterized, and the electrochemical performance of the lithium-sulfur battery with metal-loaded ultralight graphene aerogel composite sulfur positive electrode was tested. The results are shown in the attached Figure 1-8 shown.

[0074] Attached Figure 1This is a real photo of the metal-loaded ultralight graphene aerogel precursor obtained according to the technical solution of Example 1 of the present application. It shows that the metal-loaded ultralight graphene aerogel precursor obtained according to the technical solution of the embodiment of the present application has a very light mass and can be placed stably on top of fragile grass leaves.

[0075] Attached Figure 2 This is a scanning electron microscope photo of the metal-loaded ultralight graphene aerogel obtained according to the technical solution of Example 1 of the present application. It shows that the metal-loaded ultralight graphene aerogel obtained according to the technical solution of the embodiment of the present application exhibits a large number of layered structures, which provides favorable conditions for the loading of sulfur and also reflects the large specific surface area of ​​the host material.

[0076] Attached Figure 3 The transmission electron microscope photo of the un-acid-washed metal cobalt-loaded ultralight graphene aerogel obtained by the technical solution of comparative example 1 of the present application shows that there are still a large number of cobalt particles on the surface of the un-acid-washed aerogel, and a large number of cobalt particles reduce the utilization rate of cobalt atoms and reduce the reaction kinetics.

[0077] Attached Figure 4 This is a transmission electron microscope photo of the metal cobalt-loaded ultralight graphene aerogel obtained by the technical solution of Example 1 of the present application. It shows that after acid washing, a large number of cobalt particles on the surface of the aerogel are washed away, further improving the atomic utilization rate of cobalt.

[0078] Attached Figure 5 This is a comparison table of the mass and density of the metal-loaded ultralight graphene aerogel obtained by the technical solution of Example 1 of this application before and after high-temperature carbonization. It shows that the mass of the carbonized aerogel is 0.091g and the density is 0.04g cm -3 , demonstrating the successful preparation of ultralight graphene aerogel.

[0079] Attached Figure 6 The specific surface area of ​​the metal-loaded ultralight graphene aerogel obtained by the technical solution of Example 1 of the present application is shown in the figure. The sample after acid washing has a specific surface area of ​​121.7 m 2 g -1 large specific surface area and rich microporous structure.

[0080] Attached Figure 7 The figure is a rate cycling performance diagram of a lithium-sulfur battery with a metal-loaded ultralight graphene aerogel composite sulfur positive electrode obtained by the technical solutions of Example 1 and Comparative Example 1 of the present application. The device maintains excellent rate performance during the cycle process. The sample without acid washing has a rate performance of 519.2 mAh g at a current of 2.0 C. -1 The reversible specific capacity of the sample after acid washing is still 527 mAh g at a current of 2.0C. -1 reversible specific capacity.

[0081] Attached Figure 8 The cycle performance diagram of the lithium-sulfur battery with metal-loaded ultra-light graphene aerogel composite sulfur positive electrode obtained by the technical solutions of Example 1 and Comparative Example 1 of the present application, the current is 1.0C. The reversible specific capacity of the battery assembled from the sample without acid washing in Comparative Example 1 after 300 cycles is 345 mAh g -1 The reversible specific capacity of the battery device assembled from the acid-washed sample in Example 1 after 300 cycles is 498.5 mAh g -1 It shows that the lithium-sulfur battery with metal-loaded ultra-light graphene aerogel composite sulfur positive electrode obtained by the technical solution of the embodiment of the present application has good cycle stability.

[0082] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An ultralight graphene aerogel loaded with metal particles, characterized in that: The metal-loaded ultralight graphene aerogel is a directional three-dimensional structure; the mass of the metal-loaded ultralight graphene aerogel is 0.3-0.4 g, and the density is 0.03-0.04 g / cm 3 , with a specific surface area of ​​120 to 130 m 2 / g; the metal-loaded ultralight graphene aerogel is uniformly coated with metal particles, and the particle size of the metal particles is 5.5 to 6 nm.

2. A method for preparing metal-loaded ultralight graphene aerogel according to claim 1, characterized in that: The following steps are involved: Step 1: After dissolving acetate, graphene oxide and chitosan in an acetic acid aqueous solution, the mixture is first quickly frozen in a liquid nitrogen environment and then freeze-dried in a vacuum; Step 2: annealing the freeze-dried sample in a tubular furnace to obtain high-temperature carbonized graphene aerogel; washing the graphene aerogel in a sulfuric acid aqueous solution, and continuing to freeze-dry to obtain metal-loaded ultralight graphene aerogel.

3. The method for preparing metal-loaded ultralight graphene aerogel according to claim 2, characterized in that: In step 1, the acetate is one or more of cobalt acetate, nickel acetate and ferric acetate; the mass ratio of the acetate, chitosan and graphene oxide is (600-700):(400-500):(10-30); the concentration of acetic acid is 80%-90%, and the volume ratio of acetic acid to deionized water is (0.7-0.9):(40-60).

4. The method for preparing metal-loaded ultralight graphene aerogel according to claim 2, characterized in that: In step 1, the freezing time in the liquid nitrogen environment is 20 to 30 minutes; the vacuum freeze drying pressure is less than 30 Pa, the temperature is -70°C to -60°C, and the time is 48 to 72 hours.

5. The method for preparing metal-loaded ultralight graphene aerogel according to claim 2, characterized in that: In step 2, the annealing temperature is 700-900°C, the time is 60-180 min; the concentration of the sulfuric acid aqueous solution is 1-2 mol L -1 .

6. An application of the metal-loaded ultralight graphene aerogel as claimed in claim 1, characterized in that: The metal-loaded ultralight graphene aerogel and sublimated sulfur powder are hydrothermally treated to obtain a metal-loaded ultralight graphene aerogel composite sulfur material; the metal-loaded ultralight graphene aerogel composite sulfur material is mixed with conductive carbon black and a binder to form a slurry, which is then coated on an aluminum foil to obtain a metal-loaded ultralight graphene aerogel composite sulfur cathode; the metal-loaded ultralight graphene aerogel composite sulfur cathode is used in the assembly of a lithium-sulfur battery.

7. The use of the metal-loaded ultralight graphene aerogel according to claim 6, characterized in that: The lithium-sulfur battery is assembled by encapsulating a metal-loaded ultralight graphene aerogel composite sulfur cathode and a metal lithium sheet anode in a battery shell, the cathode and the anode are separated by a diaphragm, and both sides of the diaphragm are filled with electrolyte.

8. The use of the metal-supported ultralight graphene aerogel according to claim 6, characterized in that: The mass ratio of the metal-loaded ultralight graphene aerogel to the sublimated sulfur powder is (30-50):(50-70); the hydrothermal reaction temperature is 150-160° C., and the reaction time is 12-24 hours.

9. The use of the metal-supported ultralight graphene aerogel according to claim 6, characterized in that: The mass ratio of the metal-loaded ultralight graphene aerogel composite sulfur cathode material, conductive carbon black and binder is (60-80): (10-20): (10-20).

10. The use of the metal-supported ultralight graphene aerogel according to claim 7, characterized in that: The diaphragm is a polypropylene diaphragm; the electrolyte is selected from one or more mixed solutions of lithium nitrate, lithium bisimide, 1,3-dioxolane and 1,2-dimethoxyethane, with a concentration of 0.5 to 3 mol L -1 .

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