Preparation method and application of conductive organic sulfur polymer microcage

Abstract

The present invention discloses a preparation method and application of a conductive organosulfur polymer microcage, belonging to the technical field of organic micron material synthesis. The method comprises: dispersing yeast in acetone, stirring thoroughly, centrifuging, discarding the supernatant, and drying the precipitate to obtain acetone-treated yeast; dissolving the acetone-treated yeast in water, adding sodium chloride solution and glutaraldehyde solution, and conducting a hydrothermal reaction. After the hydrothermal reaction, the product is centrifuged, filtered, and washed to obtain a hollow yeast-based microcage; and uniformly mixing the hollow yeast-based microcage with sulfur powder, and heat-treating under an inert atmosphere to obtain the conductive organosulfur polymer microcage. The preparation method of the conductive organosulfur polymer microcage provided by the present invention is simple in process, efficient in production, and environmentally friendly. The room-temperature alkali metal-sulfur battery prepared therefrom has high specific capacity, excellent rate performance, and cycle performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic micron material synthesis, and in particular relates to a preparation method and application of a conductive organic sulfur polymer micron cage. Background Art

[0002] Lithium-ion batteries are the main energy storage devices currently in widespread use. However, the intercalation oxide cathode capacity of lithium-ion batteries is usually very limited and relies on rare and expensive resources such as cobalt and nickel, leading to concerns about battery energy density and resource sustainability. Room-temperature alkali metal sulfur batteries, including lithium sulfur, sodium sulfur, and potassium sulfur batteries, are based on resource-rich sulfur cathodes. When coupled with the corresponding alkali metal anodes, they have ultra-high theoretical capacities (1675 mAh g -1 Especially for sodium-sulfur and potassium-sulfur batteries, not only are the sulfur resources of the positive electrode abundant, but the sodium and potassium resources of the negative electrode are also extremely abundant, so the advantages of cost and resource sustainability are more obvious.

[0003] Despite the advantages of high capacity and abundant resources, sulfur cathodes face numerous challenges, including poor electrochemical stability and reaction kinetics. For example, cyclic S8 has long been widely studied for use as cathodes in alkali metal-sulfur batteries, including potassium-sulfur, sodium-sulfur, and lithium-sulfur batteries. However, unfavorable factors, such as the shuttling of long-chain soluble polysulfides, low sulfur conductivity, poor reaction kinetics, and severe electrode volume deformation, have led to poor battery cycling performance and low sulfur utilization, hindering the practical application of alkali metal-sulfur batteries. Notably, the poor reaction kinetics and large volume deformation are exacerbated in sodium-sulfur and potassium-sulfur batteries due to the larger size of sodium and potassium ions. For example, in the case of potassium-sulfur battery cathodes, the reduction of K2S3 to K2S is extremely difficult, resulting in limited reversible capacity. Furthermore, due to the formation of K2S, the theoretical volume change of the sulfur electrode is as high as 296%, which is significantly more severe than the 80% value of Li2S, making it even more difficult to achieve high-capacity and stable sulfur cathodes in potassium-sulfur batteries.

[0004] Converting cyclic S8 into smaller sulfur molecules (S 2-4 ) or covalent short-chain sulfur (-S x -,x≤4) strategy has achieved many successes in accelerating the reaction kinetics of sulfur cathode and effectively improved the cycle performance of batteries. For example, Guo Yuguo's group reported that the smaller sulfur molecules (S 2-4) confined in suitable nanopores can avoid the formation of high-order polysulfide intermediates, thereby exhibiting better cycling performance than cyclic S8 cathodes (reference: Adv. Energy Mater. 2018, 8, 1800855). However, from the perspective of electrode material production, confining smaller sulfur molecules in porous materials usually requires strict control of the pore size, which makes the preparation process complex and unstable. In addition, previously reported sulfur cathodes are generally only applicable to a certain type of alkali metal-sulfur battery, such as lithium-sulfur batteries. Directly transferring high-performance sulfur cathodes in lithium-sulfur batteries to another metal-sulfur battery (such as sodium-sulfur batteries or potassium-sulfur batteries) usually fails. In particular, for potassium-sulfur systems, the cycling performance of sulfur cathodes is always poor, whether they are confined as small molecules in nanopores or covalently bonded to the main chain as short-chain sulfur. Therefore, it is very necessary to develop new sulfur cathodes that are suitable for various room-temperature alkali metal-sulfur batteries, including lithium-sulfur, sodium-sulfur and potassium-sulfur batteries, and have excellent capacity, cycling performance and rate performance. Summary of the Invention

[0005] To address the above technical issues, the present invention proposes a method for preparing conductive organosulfur polymer microcages and their application. This method is simple, efficient, low-cost, and environmentally friendly, overcoming the problems of low sulfur conductivity, severe volume expansion, shuttle effects, and slow kinetics in alkali metal-sulfur batteries. The conductive organosulfur polymer microcages prepared by this invention can be widely used in room-temperature lithium-sulfur, sodium-sulfur, and potassium-sulfur batteries.

[0006] To achieve the above objectives, the present invention provides the following technical solutions:

[0007] One of the technical solutions of the present invention:

[0008] A method for preparing a conductive organosulfur polymer microcage comprises the following steps:

[0009] The yeast is dispersed in acetone, stirred thoroughly, centrifuged, the supernatant is discarded, and the precipitate is dried to obtain acetone-treated yeast;

[0010] The acetone-treated yeast is dissolved in water, and a sodium chloride solution and a glutaraldehyde solution are added to perform a hydrothermal reaction. After the hydrothermal reaction is completed, the product is centrifuged, filtered, and washed to obtain hollow yeast-based microcages;

[0011] The hollow yeast-based microcage and sulfur powder are evenly mixed, and heat-treated under an inert atmosphere to obtain the conductive organic sulfur polymer microcage.

[0012] The present invention uses acetone to pre-wash the yeast, which can effectively destroy the cell membrane and release the substances in the cell, and then proceed to the subsequent steps; the sodium chloride solution can adjust the osmotic pressure of the yeast, which is conducive to the release of the intracellular substances. The glutaraldehyde solution plays a fixing role, and after the hydrothermal reaction, hollow yeast-based microcages are formed.

[0013] Preferably, the mass ratio of the hollow yeast-based microcage to sulfur powder is 1:(0.5-4), more preferably 1:4.

[0014] Preferably, the sulfur powder is commercial sublimed sulfur powder.

[0015] Preferably, the ratio of the yeast to acetone is 1 g:10 mL.

[0016] Preferably, the volume ratio of the sodium chloride solution to the glutaraldehyde solution is 25:1, the concentration of the sodium chloride solution is 100 mg / mL, and the concentration of the glutaraldehyde solution is 25 wt %.

[0017] Preferably, the temperature of the hydrothermal reaction is 190° C. and the time is 8 hours.

[0018] Preferably, the heat treatment temperature is 250-550° C., the heating rate is 1-20° C. / min, and the holding time is 1-10 h.

[0019] More preferably, the heat treatment temperature is 350° C., the heating rate is 5° C. / min, and the holding time is 5 h.

[0020] Preferably, the inert gas is argon, nitrogen or helium, more preferably an argon atmosphere.

[0021] The present invention obtains conductive organic sulfur polymer microcages by uniformly mixing hollow yeast-based microcages and sulfur powder and then heat-treating them at low temperature (250-550°C). The microcages are different from the common porous carbon material structure. The conductive organic sulfur polymer microcages of the present invention have open pores on the surface and cavities inside, but have high electrical conductivity, which can reach 7.4×10 -7 S cm -1 The sulfur component exists in the form of short-chain sulfur (S x ,x≤4), is covalently bonded to the polymer matrix through carbon and sulfur, resulting in abundant delocalized C=C and C=S groups, which promote charge delocalization and enhance electrical conductivity. The sulfur content in this conductive organosulfur polymer microcage can reach up to 46.3 wt%.

[0022] This invention proposes for the first time a method for obtaining conductive organosulfur polymer microcages by pyrolysis under an inert atmosphere using microbial yeast as a precursor. Given the unique hollow structure, abundant delocalized groups, and short-chain covalent sulfur, conductive organosulfur polymers not only promote electron transfer, enhance the material's conductivity, and achieve high-rate performance, but also avoid the formation of soluble polysulfides, thereby avoiding the shuttle effect and achieving high storage capacity and high electrochemical stability. The method of the present invention features a simple, gentle, and highly efficient preparation process, overcoming the problems of low sulfur cathode conductivity, severe volume deformation, the shuttle effect, and poor reaction kinetics present in room-temperature alkali metal-sulfur batteries.

[0023] The second technical solution of the present invention:

[0024] The present invention also provides a conductive organosulfur polymer microcage prepared according to the above preparation method. The sulfur element in the conductive organosulfur polymer microcage is covalently bonded to the carbon skeleton via CS in the form of sulfur chains. The particle size of the conductive organosulfur polymer microcage is 2 to 3 μm. Analysis by an elemental analyzer reveals that the sulfur content in the conductive organosulfur polymer microcage is 46.3 wt%.

[0025] The third technical solution of the present invention:

[0026] The present invention also provides a room temperature alkali metal sulfur battery positive electrode material, comprising a conductive agent, a binder and the conductive organic sulfur polymer microcage.

[0027] Preferably, the conductive agent includes conductive carbon black (Super P), acetylene black (Acetylene Black) or carbon nanotubes (CNT), more preferably Super P.

[0028] Preferably, the binder comprises: sodium carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR) mixed in equal mass ratio, or polyacrylic acid (PAA), or polyvinylidene fluoride (PVDF), more preferably CMC and SBR mixed in equal mass ratio.

[0029] Preferably, the mass ratio of the conductive organic sulfur polymer microcage, the conductive agent and the binder is (80-60): (3-30): (5-20), more preferably (60-80): (10-25): (8-20), such as 70:20:10, or 75:15:10.

[0030] The fourth technical solution of the present invention:

[0031] The present invention also provides the use of the conductive organic sulfur polymer microcage in preparing a positive electrode material for a room temperature alkali metal sulfur battery.

[0032] The fifth technical solution of the present invention:

[0033] The present invention also provides the use of the conductive organic sulfur polymer microcage in the preparation of potassium sulfur batteries, sodium sulfur batteries or lithium sulfur batteries.

[0034] Preferably, the potassium-sulfur battery comprises a negative electrode, an electrolyte and the room temperature alkali metal sulfur battery positive electrode material.

[0035] Preferably, the sodium-sulfur battery comprises a negative electrode, an electrolyte and the room temperature alkali metal sulfur battery positive electrode material.

[0036] Preferably, the lithium-sulfur battery comprises a negative electrode, an electrolyte and the room temperature alkali metal sulfur battery positive electrode material.

[0037] Compared with the prior art, the present invention has the following advantages and technical effects:

[0038] (1) The conductive organic sulfur polymer microcage cathode prepared by the present invention can show excellent electrochemical performance in potassium sulfur battery. -1 The first-cycle potassium storage capacity of the organosulfur polymer cathode is as high as 1206.5 mAh g at the current density. -1 ; at 1.8A·g -1 The potassium storage capacity at this current density is 371 mAh g -1 , with excellent rate performance; at 0.9A·g -1 The capacity retention rate is as high as 99% after 1100 cycles at the current density, which shows excellent cycle performance.

[0039] (2) The conductive organic sulfur polymer microcage cathode prepared by the present invention can also exhibit excellent electrochemical performance in sodium sulfur batteries. -1 The first-cycle sodium storage reversible capacity of the organosulfur polymer cathode is as high as 1348.3 mAh·g at the current density. -1 ; at 3.6A·g -1 At a current density of 1.5 GHz, the sodium storage capacity reaches 355.9 mAh g -1 , with excellent rate performance; at 0.9A·g -1 After cycling for more than 450 times at the current density, its capacity retention rate is 90%, which has excellent cycle performance.

[0040] (3) The conductive organic sulfur polymer microcage positive electrode prepared by the present invention can also show excellent electrochemical performance in lithium sulfur batteries. -1 The first cycle reversible capacity of the organosulfur polymer cathode is as high as 1153.4 mAh·g at a current density of -1 ; at 3.6A·g -1At a current density of 1.5 GHz, the lithium storage capacity reaches 447.1 mAh g -1 , with excellent rate performance; at 0.6A·g -1 The capacity retention rate was 91% after more than 350 cycles at the current density. The prepared conductive organic sulfur polymer microcage also had excellent cycle performance as the positive electrode of lithium-sulfur battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the application. The exemplary embodiments and descriptions of the application are intended to explain the application and do not constitute an undue limitation of the application. The capacity marked in the following drawings refers to the reversible specific capacity, and the efficiency marked refers to the coulombic efficiency. In the accompanying drawings:

[0042] Figure 1 This is a flow chart for preparing the conductive organosulfur polymer microcage of the present invention;

[0043] Figure 2 1 is a transmission electron micrograph of the conductive organosulfur polymer microcage prepared in Example 1;

[0044] Figure 3 Element distribution diagram of the conductive organosulfur polymer microcage prepared in Example 1;

[0045] Figure 4 This is a Raman spectrum of the conductive organosulfur polymer microcage prepared in Example 1;

[0046] Figure 5 The potassium-sulfur battery prepared in Example 5 is -1 The first cycle charge and discharge curve at the current density of ;

[0047] Figure 6 The potassium-sulfur battery prepared in Example 5 is -1 Schematic diagram of the cycling performance after 50 cycles at a current density of ;

[0048] Figure 7 The potassium-sulfur battery prepared in Example 5 is at 0.9 A·g -1 Schematic diagram of the cycling performance after 1100 cycles at a current density of ;

[0049] Figure 8 This is a rate performance diagram of the potassium-sulfur battery prepared in Example 5 under different current density conditions;

[0050] Figure 9 The sodium-sulfur battery prepared in Example 6 is -1 The first cycle charge and discharge curve at the current density of ;

[0051] Figure 10 This is a rate performance diagram of the sodium-sulfur battery prepared in Example 6 under different current density conditions;

[0052] Figure 11 The sodium-sulfur battery prepared in Example 6 is -1 Schematic diagram of the cycling performance after 120 cycles at a current density of ;

[0053] Figure 12 The sodium-sulfur battery prepared in Example 6 is -1 Schematic diagram of the cycling performance of more than 450 cycles at a current density of ;

[0054] Figure 13 The lithium-sulfur battery prepared in Example 7 is -1 The first cycle charge and discharge curve at the current density of ;

[0055] Figure 14 The lithium-sulfur battery prepared in Example 7 is -1 Schematic diagram of the cycling performance after more than 350 cycles at a current density of ;

[0056] Figure 15 This is a rate performance diagram of the lithium-sulfur battery prepared in Example 7 under different current density conditions;

[0057] Figure 16 This is a scanning electron microscope image of the amorphous carbon material prepared in Comparative Example 1, where a is 2 μm and b is 1 μm;

[0058] Figure 17 This is a Raman spectrum of the amorphous carbon material prepared in Comparative Example 1;

[0059] Figure 18 is a Raman spectrum of the conductive organosulfur polymer prepared in Comparative Example 2;

[0060] Figure 19 Schematic diagram of the preparation of conductive organosulfur polymer microcages in Example 1 and the preparation of carbon microcage / S8 composites in Comparative Example 3;

[0061] Figure 20 This is the XRD pattern of the conductive organosulfur polymer microcage prepared in Example 1;

[0062] Figure 21 The electrochemical behavior diagram of the conductive organic sulfur polymer microcage prepared in Example 1 as the positive electrode material of the lithium-sulfur battery in Example 8, where a is the electrochemical behavior of the conductive organic sulfur polymer microcage in 0.03Ag -1 The first and third charge-discharge curves under the conditions of b; b is the conductive organic sulfur polymer microcage at a scan rate of 0.1 mV s -1Cyclic voltammetry (CV) curves. DETAILED DESCRIPTION

[0063] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0064] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0065] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0066] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be illustrative only.

[0067] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0068] Unless otherwise specified, the room temperature in the present invention is 25±2°C.

[0069] Unless otherwise specified, the experimental materials, reagents, instruments, etc. used in the examples of the present invention are all commercially available; unless otherwise specified, all technical means in the examples of the present invention are conventional means well known to those skilled in the art.

[0070] The core of the present invention is to provide a method for obtaining conductive organic sulfur polymer microcages by using hollow yeast-based microspheres of a single component that are directly synthesized without any post-modification as a precursor, mixing them evenly with sulfur powder, and then pyrolyzing them in an inert atmosphere in one step.

[0071] The present application provides a method for preparing a conductive organic sulfur polymer microcage, the preparation flow chart of which is as follows: Figure 1 As shown, the specific steps include:

[0072] S01: Disperse the yeast in acetone, stir thoroughly, centrifuge and discard the supernatant, transfer the precipitate to an oven and dry it to obtain acetone pre-washed yeast;

[0073] S02: The yeast pre-washed with acetone was dissolved in water, and sodium chloride solution and glutaraldehyde solution were added. After stirring, the mixture was transferred to a reactor. The reactor was placed in an oven for hydrothermal reaction at 190°C for 8 hours. After the reaction, centrifugation, filtration and washing were repeated three times to obtain a brown solid product (hollow yeast-based microcages);

[0074] S03: Grind and mix the obtained brown solid product and commercial sublimed sulfur powder, and perform heat treatment under inert atmosphere to obtain conductive organic sulfur polymer microcages.

[0075] The hollow yeast-based microcages and commercial sublimated sulfur powder are heat-treated under inert atmosphere at a temperature of 250°C to 550°C, preferably 350°C, and a heating rate of 0.5°C / min to 20°C / min, preferably 5°C / min. The inert gas is argon, nitrogen, or helium.

[0076] The technical solution of the present invention is further illustrated by the following examples.

[0077] Example 1

[0078] This embodiment provides a method for preparing conductive organosulfur polymer microcages:

[0079] S01: Disperse 1.0 g of yeast in 10 mL of acetone, stir for 30 min, centrifuge and discard the supernatant, place the precipitate in an oven and dry at 50°C to obtain acetone-prewashed yeast;

[0080] S02: The yeast pre-washed with acetone was dissolved in 30 mL of water, 5 mL of sodium chloride solution (100 mg / mL) and 200 μL of glutaraldehyde solution (concentration of 25 wt%) were added, and the mixture was stirred and transferred to a 50 mL reactor. The reactor was placed in an oven and hydrothermally reacted at 190°C for 8 hours. After the reaction, centrifugation, filtration and washing were repeated three times to obtain hollow yeast-based microspheres;

[0081] S03: The obtained hollow yeast-based microspheres and commercial sublimed sulfur powder were evenly mixed in a mass ratio of 1:4, and heat-treated at 350°C for 5 h under an argon atmosphere at a heating rate of 5°C / min to obtain conductive organic sulfur polymer microcages.

[0082] The transmission electron microscopy image of the conductive organosulfur polymer microcage prepared in this example is shown in Figure 2 , element distribution diagram see Figure 3 , Raman spectrum is shown in Figure 4 It can be seen that the sulfur element in the conductive organic sulfur polymer microcage is covalently bonded to the carbon skeleton in the form of sulfur chains through CS. The particle size of the conductive organic sulfur polymer microcage is 2-3 μm; the S element content in the conductive organic sulfur polymer microcage is 46.3 wt%.

[0083] Example 2

[0084] This embodiment provides a method for preparing conductive organosulfur polymer microcages:

[0085] S01: Disperse 1.0 g of yeast in 10 mL of acetone, stir for 30 min, centrifuge and discard the supernatant, place the precipitate in an oven and dry at 50°C to obtain acetone-prewashed yeast;

[0086] S02: The yeast pre-washed with acetone was dissolved in 30 mL of water, 5 mL of sodium chloride solution (100 mg / mL) and 200 μL of glutaraldehyde solution (concentration of 25 wt%) were added, and the mixture was stirred and transferred to a 50 mL reactor. The reactor was placed in an oven and hydrothermally reacted at 190°C for 8 hours. After the reaction, centrifugation, filtration and washing were repeated three times to obtain hollow yeast-based microspheres;

[0087] S03: The obtained hollow yeast-based microspheres and commercial sublimed sulfur powder were evenly mixed in a mass ratio of 1:4, and heat-treated at 250°C for 10 h under a nitrogen atmosphere at a heating rate of 10°C / min to obtain conductive organic sulfur polymer microcages.

[0088] Example 3

[0089] This embodiment provides a method for preparing conductive organosulfur polymer microcages:

[0090] S01: Disperse 1.0 g of yeast in 10 mL of acetone, stir for 30 min, centrifuge and discard the supernatant, place the precipitate in an oven and dry at 50°C to obtain acetone-prewashed yeast;

[0091] S02: The yeast pre-washed with acetone was dissolved in 30 mL of water, 5 mL of sodium chloride solution (100 mg / mL) and 200 μL of glutaraldehyde solution (concentration of 25 wt%) were added, and the mixture was stirred and transferred to a 50 mL reactor. The reactor was placed in an oven and hydrothermally reacted at 190°C for 8 hours. After the reaction, centrifugation, filtration and washing were repeated three times to obtain hollow yeast-based microspheres;

[0092] S03: The obtained hollow yeast-based microspheres and commercial sublimed sulfur powder were evenly mixed in a mass ratio of 1:4, and heat-treated at 550°C for 1 h in a helium atmosphere at a heating rate of 20°C / min to obtain conductive organic sulfur polymer microcages.

[0093] Example 4

[0094] The same as Example 1, except that the hollow yeast-based microspheres and commercial sublimed sulfur powder in S03 are uniformly mixed in a mass ratio of 1:0.5.

[0095] Example 5

[0096] This embodiment provides a process for preparing a positive electrode sheet for a potassium-sulfur battery and a method for assembling a battery:

[0097] S01: The conductive organic sulfur polymer microcage in Example 1 was used as the positive electrode material, and was evenly mixed with a conductive agent Super P and a binder in a mass ratio of 70:20:10. A mixture of CMC and SBR in a mass ratio of 1:1 was used as the binder. Deionized water was added in an amount of 150 μL deionized water / 100 mg active material (i.e., conductive organic sulfur polymer microcage, the same below). The mixture was stirred by mechanical stirring to form a uniform slurry. The slurry was coated on aluminum foil and dried under vacuum for 6 hours to obtain a positive electrode sheet.

[0098] S02: Cut the dried positive electrode sheet into a circular electrode sheet with a diameter of 10 mm;

[0099] S03: The obtained circular electrode sheet is used as the positive electrode of the potassium-sulfur battery, the glass fiber membrane is used as the battery separator, 2.5M KFSI TEP is used as the electrolyte, and it is assembled with metallic potassium into a button battery. The specification of the button battery is CR2032.

[0100] Battery performance test:

[0101] The potassium-sulfur battery prepared in this embodiment was subjected to a constant current charge and discharge test using a battery charge and discharge tester. The test voltage range was 0.5 to 3 V, and the test environment temperature was 25° C. Figure 5 The potassium-sulfur battery of this embodiment is 0.03A·g -1 The first cycle charge and discharge curve at a current density of 1000 nm is shown in Figure 2. The reversible capacity of the first cycle is as high as 1206.5 mAh g -1 , which has a high reversible specific capacity. Figure 6 The potassium-sulfur battery in this embodiment is at 0.15A·g -1 Schematic diagram of the cycling performance after 50 cycles under current density conditions. Figure 7 The potassium-sulfur battery of this embodiment is 0.9A·g -1Schematic diagram of the cycling performance after 1100 cycles at the same current density, with a capacity retention rate of 99%. Figure 8 The rate performance diagram of the potassium-sulfur battery of this embodiment under different current density conditions is shown in FIG. -1 At a current density of 1.5 GHz, the specific capacity reaches 371 mAh g -1 It can be seen that the conductive organic sulfur polymer microcage prepared by the present invention has excellent rate performance as the positive electrode of potassium-sulfur battery.

[0102] Example 6

[0103] This embodiment provides a preparation process for a sodium-sulfur battery positive electrode sheet and a battery assembly method:

[0104] S01: The conductive organosulfur polymer microcages prepared in Example 1 were used as the positive electrode material and mixed with a conductive agent, Super P, and a binder in a mass ratio of 70:20:10. A mixture of CMC and SBR in a mass ratio of 1:1 was used as the binder. Deionized water was added at a rate of 150 μL per 100 mg of active material. The mixture was mechanically stirred to form a uniform slurry, which was then coated on aluminum foil and dried under vacuum for 6 hours to obtain a positive electrode sheet.

[0105] S02: Cut the dried positive electrode sheet into a circular electrode sheet with a diameter of 10 mm;

[0106] S03: The obtained circular electrode sheet is used as the positive electrode of the sodium-sulfur battery, the glass fiber membrane is used as the battery separator, 1M NaPF6 EC PC is used as the electrolyte, and it is assembled with metallic sodium into a button battery. The specification of the button battery is CR2032.

[0107] Battery Test:

[0108] The sodium-sulfur battery prepared in this embodiment was subjected to a constant current charge and discharge test using a battery charge and discharge tester. The test voltage range was 0.5 to 2.8 V, and the test environment temperature was 25° C. Figure 9 The sodium-sulfur battery of this embodiment is 0.03A·g -1 The first cycle charge and discharge curve at a current density of 100 nm is shown in Figure 2. The reversible sodium storage capacity of the first cycle is as high as 1348.3 mAh g -1 , which has a high reversible specific capacity. Figure 10 The rate performance diagram of the sodium-sulfur battery of this embodiment under different current density conditions is shown in FIG. -1 At a current density of 1.5 GHz, the specific capacity reaches 355.9 mAh g -1 , which has excellent rate performance. Figure 11 The sodium-sulfur battery in this embodiment is tested at a rate of 0.06A·g -1Schematic diagram of the cycling performance after 120 cycles under current density conditions. Figure 12 The sodium-sulfur battery of this embodiment is 0.9A·g -1 Schematic diagram of the cycling performance after more than 450 cycles at the same current density, with a capacity retention rate of 90%. This shows that the conductive organic sulfur polymer microcage prepared by the present invention also has excellent cycling stability as the positive electrode of sodium-sulfur batteries.

[0109] Example 7

[0110] This embodiment provides a process for preparing a positive electrode sheet for a lithium-sulfur battery and a method for assembling a battery:

[0111] S01: The conductive organosulfur polymer microcages prepared in Example 1 were used as the positive electrode material and mixed with a conductive agent, Super P, and a binder in a mass ratio of 70:20:10. A mixture of CMC and SBR in a mass ratio of 1:1 was used as the binder. Deionized water was added at a rate of 150 μL per 100 mg of active material. The mixture was mechanically stirred to form a uniform slurry, which was then coated on aluminum foil and dried under vacuum for 6 hours to obtain a positive electrode sheet.

[0112] S02: Cut the dried positive electrode sheet into a circular electrode sheet with a diameter of 10 mm;

[0113] S03: The obtained circular electrode sheet is used as the positive electrode of the lithium-sulfur battery, the glass fiber membrane is used as the battery separator, 5M LiFSI EC EMC is used as the electrolyte, and it is assembled with metallic lithium into a button battery. The specification of the button battery is CR2032.

[0114] Battery Test:

[0115] The lithium-sulfur battery prepared in this embodiment was subjected to a constant current charge and discharge test using a battery charge and discharge tester. The test voltage range was 1-3 V, and the test environment temperature was 25° C. Figure 13 The lithium-sulfur battery of this embodiment is 0.03A·g -1 The first cycle charge and discharge curve at a current density of 100 nm is shown in Figure 2. The reversible capacity of lithium storage in the first cycle is as high as 1153.4 mAh g -1 , which has a high reversible specific capacity. Figure 14 The lithium-sulfur battery of this embodiment is 0.6A·g -1 Schematic diagram of the cycling performance after more than 350 cycles at the same current density, with a capacity retention rate of 91%. Figure 15 The rate performance diagram of the lithium-sulfur battery of this embodiment under different current density conditions is shown in FIG. -1 At a current density of 1.5 GHz, the specific capacity reaches 447.1 mAh g -1; It can be seen that the conductive organic sulfur polymer microcage prepared by the present invention also has excellent rate performance as the positive electrode of lithium-sulfur battery.

[0116] Example 8

[0117] The same as Example 7, except that the electrolyte in this example is 1M LiTFSIDOL DME (volume ratio 1:1) electrolyte, which contains 2 wt% LiNO3 as an electrolyte additive.

[0118] Comparative Example 1

[0119] S01: Disperse 1.0 g of yeast in 10 mL of acetone, stir for 30 min, centrifuge and discard the supernatant, place the precipitate in an oven and dry at 50°C to obtain acetone-prewashed yeast;

[0120] S02: The yeast pre-washed with acetone was dissolved in 30 mL of water, 5 mL of sodium chloride solution (100 mg / mL) and 200 μL of glutaraldehyde solution (concentration of 25 wt%) were added, and the mixture was stirred and transferred to a 50 mL reactor. The reactor was placed in an oven and hydrothermally reacted at 190°C for 8 hours. After the reaction, centrifugation, filtration and washing were repeated three times to obtain hollow yeast-based microspheres;

[0121] S03: The obtained hollow yeast-based microspheres were heat-treated at 350° C. for 5 h under an argon atmosphere at a heating rate of 5° C. / min to obtain an amorphous carbon microcage material.

[0122] The scanning electron microscope image of the amorphous carbon material prepared in this comparative example is shown in FIG. Figure 16 , Raman spectrum is shown in Figure 17 The Raman spectrum shows a D peak induced by defects and a G peak induced by graphite corresponding to the amorphous carbon material, and no peaks corresponding to CS, SS, C=S and S=S appear. The particle size of the amorphous carbon material is 2 to 3 μm. Since no sulfur powder is added during the heat treatment in this comparative example, an amorphous carbon material is obtained.

[0123] Comparative Example 2

[0124] Same as Example 1, except that the heat treatment temperature in S03 is 800°C.

[0125] The Raman spectrum of this comparative example is shown in Figure 18 From the obvious D peak and G peak, it can be seen that the conductive organic sulfur polymer is carbonized due to the high heat treatment temperature of this comparative example.

[0126] Comparative Example 3

[0127] The same as Comparative Example 1, except that the amorphous carbon microcage material and sulfur powder obtained in Comparative Example 1 were mixed according to a weight ratio of 53.7:46.3, then placed in a glass tube, evacuated and sealed, and then heated at 155°C for 12 hours to finally obtain a carbon microcage / S8 composite material.

[0128] The schematic diagrams of Example 1 for preparing conductive organic sulfur polymer microcages and Comparative Example 3 for preparing carbon microcage / S8 composites are shown in Figure 19 It can be seen that the present invention (left side) uses a chemical bonding method to form a conductive organic sulfur polymer microcage, short chain sulfur (-S 1-4 -) will bond to the formed polymer, which is different from the right side, which is to physically confine or load the S8 molecules to finally form a carbon microcage / S8 complex.

[0129] The XRD pattern of the conductive organic sulfur polymer microcage prepared in Example 1 is shown in Figure 20 It can be seen that the conductive organic sulfur polymer microcage prepared in the present invention has no diffraction peak signal of S8, while the carbon microcage / S8 composite in Comparative Example 3 has a strong diffraction peak.

[0130] The electrochemical behavior of the conductive organic sulfur polymer microcage prepared in Example 1 as a lithium sulfur battery in Example 8 is shown in FIG. Figure 21 , where (a) is a conductive organic sulfur polymer microcage at 0.03Ag -1 The first and third charge-discharge curves under the conditions of (a) the first and third charge-discharge curves under the conditions of (b) the first and third charge-discharge curves under the conditions of (c) the first and third charge-discharge curves under the conditions of (d) the first and third charge-discharge curves under the conditions of (e) the first and third charge-discharge curves under the conditions of (f ... -1 Cyclic voltammetry (CV) curves under the conditions of 100 nm. It is well known that long-chain sulfur (Sx, x>4) or cyclic S8 positive electrodes will show a voltage platform above 2.3 V during the discharge process of lithium batteries (reference: Matter 2023, 6(2), 316 and Angew. Chem. Int. Ed. 2019, 58(52), 18746), indicating that the solid-liquid reaction leads to the formation of long-chain polysulfides (Li2S x , x>4). For the conductive organosulfur polymer microcages, no high-voltage (>2.2V) plateau was observed during discharge, nor was there a corresponding reduction peak in the CV curve. Instead, only low-voltage (<2.1V) capacity and reaction peaks associated with the formation of short-chain polysulfides (Li2Sx, x≤4) were present, indicating that the sulfur species bound in the conductive organosulfur polymer microcages are short-chain sulfur (Sx, x≤4).

[0131] The above are merely preferred embodiments of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A method for preparing a conductive organosulfur polymer microcage, characterized in that: The following steps are involved: The yeast is dispersed in acetone, stirred thoroughly, centrifuged, the supernatant is discarded, and the precipitate is dried to obtain acetone-treated yeast; The acetone-treated yeast is dissolved in water, and a sodium chloride solution and a glutaraldehyde solution are added to perform a hydrothermal reaction. After the hydrothermal reaction is completed, the product is centrifuged, filtered, and washed to obtain hollow yeast-based microcages; The hollow yeast-based microcage and sulfur powder are uniformly mixed, and heat-treated under an inert atmosphere to obtain the conductive organic sulfur polymer microcage; The temperature of the hydrothermal reaction is 190°C and the time is 8 hours; The heat treatment temperature is 250-550°C, the heating rate is 1-20°C / min, and the holding time is 1-10h; The mass ratio of the hollow yeast-based micron cage to sulfur powder is 1: (0.5-4).

2. The method for preparing the conductive organosulfur polymer microcage according to claim 1, characterized in that: The usage ratio of the yeast and acetone is 1 g:10 mL.

3. The method for preparing the conductive organosulfur polymer microcage according to claim 1, characterized in that: The volume ratio of the sodium chloride solution to the glutaraldehyde solution is 25:

1.

4. A conductive organosulfur polymer microcage, characterized in that: The method according to any one of claims 1 to 3 is prepared.

5. A room temperature alkali metal sulfur battery cathode material, characterized in that: The method comprises a conductive agent, a binder and the conductive organic sulfur polymer microcage according to claim 4.

6. Use of the conductive organic sulfur polymer microcage according to claim 4 in preparing a positive electrode material for room temperature alkali metal sulfur batteries.

7. Use of the conductive organosulfur polymer microcage according to claim 4 in the preparation of potassium-sulfur batteries, sodium-sulfur batteries or lithium-sulfur batteries.

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