Nitrogen-doped carbon quantum dot modified lithium-sulfur battery diaphragm, preparation method thereof and lithium-sulfur battery

Abstract

The invention belongs to the technical field of lithium-sulfur batteries, and relates to a nitrogen-doped carbon quantum dot modified lithium-sulfur battery diaphragm, a preparation method thereof and a lithium-sulfur battery. The preparation method comprises the following steps: cleaning and drying the waste nylon fabric, cutting the fabric into millimeter-scale fabric fragments, soaking the fabric fragments in liquid nitrogen, adding an activating agent, and grinding and crushing the fabric fragments into mixed powder; carrying out microwave treatment on the mixed powder, and grinding to obtain dark brown powder; dissolving the dark brown powder in deionized water, taking supernate, centrifuging, filtering and dialyzing to obtain a purified nitrogen-doped carbon quantum dot solution, and freeze-drying to obtain nitrogen-doped carbon quantum dot solid powder; and dispersing conductive carbon, the nitrogen-doped carbon quantum dot solid powder and a binder into an organic solvent to obtain slurry, uniformly coating a polypropylene diaphragm with the slurry, drying, and cutting into a wafer to obtain the nitrogen-doped carbon quantum dot modified lithium-sulfur battery diaphragm. The problems of shuttle effect and low electronic conductivity of the existing lithium-sulfur battery are solved.

Description

Technical Field

[0001] This invention belongs to the field of lithium-sulfur battery technology, specifically relating to a nitrogen-doped carbon quantum dot modified lithium-sulfur battery separator and its preparation method, and a lithium-sulfur battery. Background Technology

[0002] Energy storage technology, as a key link connecting energy production and consumption, plays an important role in improving energy utilization efficiency, smoothing the output of renewable energy generation, and ensuring the stable operation of the power grid. It is also an important technological support for promoting the green transformation of the energy structure and achieving sustainable development.

[0003] Among numerous electrochemical energy storage devices, rechargeable secondary batteries have attracted widespread attention due to their flexibility and convenience. Lithium-sulfur batteries, as a novel high-energy-density electrochemical energy storage system, boast a theoretical specific capacity of sulfur as its positive electrode active material, reaching 1675 mAh / g, far exceeding that of commonly used positive electrode materials in commercially available lithium-ion batteries. Simultaneously, the theoretical energy density of the lithium-sulfur battery system can reach 2600 Wh / kg, demonstrating significant advantages. Furthermore, the abundant reserves, low cost, and environmental friendliness of sulfur resources make lithium-sulfur batteries a promising candidate for applications in fields with high energy density requirements, such as electric vehicles, large-scale energy storage, and aerospace, and they are widely considered an important development direction for next-generation high-performance energy storage technology.

[0004] Despite the aforementioned advantages, lithium-sulfur batteries still face a series of technical challenges in practical applications, severely hindering their commercialization. First, during battery operation, sulfur species at the positive electrode generate soluble lithium polysulfide intermediates during charge-discharge cycles. These substances migrate between the positive and negative electrodes in the electrolyte, a phenomenon known as the "shuttle effect," leading to the loss of active material, accelerated capacity decay, reduced cycle life, and decreased coulombic efficiency. This is one of the key issues affecting the electrochemical performance of lithium-sulfur batteries. Second, sulfur and its discharge end product, lithium sulfide, have low electronic conductivity, which restricts the kinetics of the electrode reaction and affects the battery's rate performance. Furthermore, sulfur undergoes approximately 80% volume change during the reaction, easily causing electrode structure pulverization or collapse, compromising electrode integrity, and consequently affecting the battery's cycle stability. These problems are all technical bottlenecks that urgently need to be addressed in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a nitrogen-doped carbon quantum dot modified lithium-sulfur battery separator and its preparation method, as well as a lithium-sulfur battery, which solves the problems of shuttle effect and low electronic conductivity in existing lithium-sulfur batteries.

[0006] This invention is achieved through the following technical solution: This invention discloses a method for preparing a nitrogen-doped carbon quantum dot modified lithium-sulfur battery separator, comprising the following steps: Step 1: After cleaning and drying the waste nylon fabric, cut it into millimeter-sized fabric fragments. After soaking the fabric fragments in liquid nitrogen, add the activator ZnCl2 and grind them into a uniform mixed powder. Step 2: After microwave treatment of the mixed powder, a solid product is obtained. After grinding, a dark brown powder is obtained. Step 3: Dissolve the dark brown powder in deionized water, take the supernatant, centrifuge, filter, and dialyze to obtain a purified nitrogen-doped carbon quantum dot solution, freeze-dry to obtain nitrogen-doped carbon quantum dot solid powder; Step 4: Disperse conductive carbon, nitrogen-doped carbon quantum dot solid powder and binder into an organic solvent, stir to obtain a slurry, coat the slurry evenly on a polypropylene separator, dry and cut into round pieces to obtain a nitrogen-doped carbon quantum dot modified lithium-sulfur battery separator.

[0007] Furthermore, in step one, a ball mill is used for grinding, with the ball mill speed being 300-600 rpm, and the grinding is carried out intermittently and repeatedly.

[0008] Furthermore, in step two, the microwave reaction power is 500-600W, and the processing time is 8-10 minutes.

[0009] Furthermore, in step three, dialysis is performed using a 300Da dialysis bag for 24-48 hours.

[0010] Furthermore, in step four, the conductive carbon material is selected from carbon nanotubes.

[0011] Furthermore, in step four, the organic solvent is selected from N... Methylpyrrolidone. Furthermore, in step four, the adhesive is polyvinylidene fluoride.

[0012] Furthermore, in step four, the mass ratio of conductive carbon, nitrogen-doped carbon quantum dot solid powder and PVDF is 6-8:1-3:1.

[0013] The present invention also discloses a nitrogen-doped carbon quantum dot modified lithium-sulfur battery separator obtained by the above preparation method.

[0014] The present invention also discloses a lithium-sulfur battery comprising a positive electrode, a negative electrode, an electrolyte, and the nitrogen-doped carbon quantum dot modified lithium-sulfur battery separator, wherein the nitrogen-doped carbon quantum dot modified lithium-sulfur battery separator is disposed between the positive electrode and the negative electrode.

[0015] Compared with the prior art, the present invention has the following beneficial technical effects: This invention provides a method for preparing nitrogen-doped carbon quantum dot-modified lithium-sulfur battery separators. Waste nylon fabric is selected as the raw material for preparing nitrogen-doped carbon quantum dots, whose main component, polyamide, itself contains a large number of carbon and nitrogen atoms, making it an ideal carbon and nitrogen source. This avoids the use of chemical reagents, conforms to the principles of green chemistry, and provides a novel high-value conversion pathway for textile waste. The synthesis method employs a microwave-assisted method, which has high energy utilization efficiency and a fast reaction rate.

[0016] ZnCl2, specially introduced as an activator, plays the following role in the microwave reaction: Catalytic degradation: Promotes the breaking of amide bonds in polyamide macromolecules, accelerating their conversion into carbon quantum dots; Pore ​​formation and carbon expansion: Zn 2+ The template effect can create more defects and pores in the carbon core, increase the specific surface area, and provide more luminescent sites; Surface modification: After the reaction, Zn may remain on the surface of carbon dots in the form of oxides or combine with them, which helps to improve the fluorescence quantum yield.

[0017] This invention also discloses a nitrogen-doped carbon quantum dot-modified lithium-sulfur battery separator. By modifying a commercially available lithium-sulfur battery polypropylene separator with nitrogen-doped carbon quantum dots, a flexible coating is created on the positive electrode side of the separator. Because nitrogen-doped carbon quantum dots are rich in oxygen, their nitrogen-containing functional groups can form chemical bonds with polysulfides in the electrolyte, thus anchoring sulfur species to the positive electrode and significantly suppressing the shuttle effect. Furthermore, nitrogen-doped carbon quantum dots can effectively catalyze the conversion reaction of sulfur species, improving the charge / discharge capacity and active sulfur utilization rate of the lithium-sulfur battery. Nitrogen-doped carbon quantum dots also exhibit good electronic and ionic conductivity, enhancing the transport of electrons and lithium ions in the lithium-sulfur battery system.

[0018] The nitrogen-doped carbon quantum dot-modified separator of this invention effectively suppresses the "shuttle effect," the biggest challenge in lithium-sulfur batteries, thereby improving the utilization rate of sulfur, the active material, and catalyzing the conversion reaction of sulfur species. The introduction of nitrogen-doped carbon quantum dots also effectively alleviates the problem of poor conductivity of sulfur and its discharge products, significantly improving the charge and discharge capacity of lithium-sulfur batteries. Attached Figure Description

[0019] Figure 1 The first charge-discharge curve of the lithium-sulfur battery using the nitrogen-doped carbon quantum dot modified separator prepared in Example 1 at a rate of 0.2C is shown. Figure 2 The cycling capacity of a lithium-sulfur battery using a nitrogen-doped carbon quantum dot-modified separator prepared in Example 1 at a rate of 0.2C is shown. Figure 3The first charge-discharge curve of the lithium-sulfur battery using the nitrogen-doped carbon quantum dot modified separator prepared in Example 2 at a rate of 0.2C is shown. Figure 4 The cycling capacity of a lithium-sulfur battery using the nitrogen-doped carbon quantum dot-modified separator prepared in Example 2 at a rate of 0.2C is shown. Figure 5 The first charge-discharge curve of the lithium-sulfur battery using the nitrogen-doped carbon quantum dot modified separator prepared in Example 3 at a rate of 0.2C. Figure 6 The cycling capacity of a lithium-sulfur battery using the nitrogen-doped carbon quantum dot-modified separator prepared in Example 3 at a rate of 0.2C is shown. Figure 7 The graph shows the cycle capacity of lithium-sulfur batteries using nitrogen-doped carbon quantum dot modified separators prepared in Examples 1, 2 and 3 at different rates. Figure 8 The first charge-discharge curves of lithium-sulfur batteries with nitrogen-doped carbon quantum dot modified separators and unmodified polypropylene separators prepared using the optimal scheme (Example 2) are shown at a rate of 0.2C. Figure 9 The cycling capacity diagrams at 0.2C are shown for lithium-sulfur batteries with nitrogen-doped carbon quantum dot modified separators and unmodified polypropylene separators prepared using the optimal scheme (Example 2), respectively. Figure 10 The graphs show the cycle capacity of lithium-sulfur batteries at different rates for nitrogen-doped carbon quantum dot modified separators and unmodified polypropylene separators prepared using the optimal scheme (Example 2), respectively. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the present invention clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention; that is, the described embodiments are only a part of the embodiments of the present invention, and not all of them.

[0021] The detailed description of the embodiments of the present invention provided in the following figures is not intended to limit the scope of the claimed invention, but merely to illustrate one selected embodiment of the invention. All other embodiments obtained by those skilled in the art based on the figures and embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0022] This invention discloses a method for preparing a nitrogen-doped carbon quantum dot modified lithium-sulfur battery separator, comprising the following steps: Step 1: After cleaning and drying the waste nylon fabric, cut it into millimeter-sized fragments. After soaking the fabric fragments in liquid nitrogen, add the activator ZnCl2 and grind them into a uniform and fine mixed powder using a ball mill. Step 2: The mixed powder is placed in a microwave reactor for microwave treatment to obtain a solid product, which is then ground to obtain a dark brown powder. Step 3: Dissolve the dark brown powder in deionized water and take the supernatant. After centrifugation, filtration and dialysis, a purified nitrogen-doped carbon quantum dot solution is obtained. Freeze-dry to obtain a brownish-yellow nitrogen-doped carbon quantum dot solid powder. Step 4: Disperse conductive carbon, nitrogen-doped carbon quantum dot solid powder and binder into an organic solvent, stir until a slurry of suitable viscosity is formed, then uniformly coat it onto a polypropylene separator, dry it and cut it into round pieces to obtain a nitrogen-doped carbon quantum dot modified lithium-sulfur battery separator.

[0023] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0024] Example 1 This invention discloses a method for preparing a nitrogen-doped carbon quantum dot modified lithium-sulfur battery separator, comprising the following steps: Step 1: After washing and drying 0.75 g of waste nylon fabric, cut it into shreds of 1-2 mm. 2 The fabric fragments were obtained by immersing the fabric fragments in liquid nitrogen for 30 minutes to fully freeze and embrittle them. Then, 50 mg of activator ZnCl2 was added to form a mixture. The mixture was placed in a ball mill and intermittently ground at 500 rpm for 3 minutes, repeated 5 times, for a total of 15 minutes to form a uniform and fine mixed powder. Step 2: Place the mixed powder in a ceramic boat and put it into a microwave reactor. React at 550W for 8 minutes to obtain a dark brown powder. Step 3: After thoroughly grinding the obtained dark brown powder, dissolve it in deionized water and take the supernatant. Centrifuge to remove large particle impurities, then filter through a 0.22 μm filter membrane, and then dialyze with a dialysis bag (molecular weight cutoff 300 Da) for 24 hours to obtain a purified nitrogen-doped carbon quantum dot solution. Freeze at -40℃ for 12 hours and vacuum dry for 24 hours. After grinding, obtain a brownish-yellow nitrogen-doped carbon quantum dot solid powder. Step 4: Disperse carbon nanotubes (CNTs), nitrogen-doped carbon quantum dot solid powder and polyvinylidene fluoride (PVDF) into N-methylpyrrolidone, stir until a slurry of suitable viscosity is formed, then coat it evenly onto a polypropylene diaphragm, dry it and cut it into round pieces for later use. The mass ratio of CNT, nitrogen-doped carbon quantum dot solid powder, and PVDF is 8:1:1.

[0025] A positive electrode slurry was coated onto carbon paper to serve as the oxygen electrode, and a lithium metal sheet was used as the counter electrode. The nitrogen-doped carbon quantum dot-modified lithium-sulfur battery separator prepared in Example 1 was used as the separator, and a 1 mol / L LiTFSI solution containing 100 mmol / L LiI (triethylene glycol dimethyl ether TEGDME as the organic solvent) was used as the organic electrolyte. The lithium-sulfur battery was assembled in a glove box under high-purity argon protection. The electrical performance of the lithium-sulfur battery prepared in Example 1 and the unmodified lithium-sulfur battery were tested, and the results were as follows: Figure 1 The first charge-discharge curve shown and as follows Figure 2 The diagram shows the cyclic capacity.

[0026] like Figure 1 As shown, in Example 1, the lithium-sulfur battery has a first-cycle discharge capacity of 1237 mAh / g at a 0.2C rate.

[0027] like Figure 2 As shown, in Example 1, the lithium-sulfur battery had a discharge capacity of 1068 mAh / g after 50 cycles at a 0.2C rate, with a capacity retention rate of 86.3%.

[0028] Example 2 This invention discloses a method for preparing a nitrogen-doped carbon quantum dot modified lithium-sulfur battery separator, comprising the following steps: Step 1: After washing and drying 0.75 g of waste nylon fabric, cut it into shreds of 1-2 mm. 2 The fabric fragments were obtained by immersing the fabric fragments in liquid nitrogen for 30 minutes to fully freeze and embrittle them. Then, 50 mg of activator ZnCl2 was added to form a mixture. Step 2: Place the mixture from Step 1 into a ball mill and grind it at 300 rpm for 3 minutes in an intermittent cycle, repeating the cycle 5 times, for a total of 15 minutes to form a uniform and fine mixed powder. Step 3: Place the mixed powder in a ceramic boat and put it into a microwave reactor. React at 600W for 8 minutes to obtain a dark brown powder. Step 3: After thoroughly grinding the obtained dark brown powder, dissolve it in deionized water and take the supernatant. Centrifuge to remove large particle impurities, then filter through a 0.22 μm filter membrane, and then dialyze with a dialysis bag (molecular weight cutoff 300 Da) for 48 hours to obtain a purified nitrogen-doped carbon quantum dot solution. After freezing at -40℃ for 12 hours, vacuum dry for 24 hours, and grind to obtain a brownish-yellow nitrogen-doped carbon quantum dot solid powder. Step 4: Disperse carbon nanotubes (CNTs), nitrogen-doped carbon quantum dot solid powder and polyvinylidene fluoride (PVDF) into N-methylpyrrolidone, stir until a slurry of suitable viscosity is formed, then coat it evenly onto a polypropylene diaphragm, dry it and cut it into round pieces for later use. The mass ratio of CNT, nitrogen-doped carbon quantum dot solid powder and PVDF is 7:2:1.

[0029] A positive electrode slurry was coated onto carbon paper to serve as the oxygen electrode, and a lithium metal sheet was used as the counter electrode. The nitrogen-doped carbon quantum dot-modified lithium-sulfur battery separator prepared in Example 1 was used as the separator, and a 1 mol / L LiTFSI solution containing 100 mmol / L LiI (triethylene glycol dimethyl ether TEGDME as the organic solvent) was used as the organic electrolyte. The lithium-sulfur battery was assembled in a glove box under high-purity argon protection. The electrical performance of the lithium-sulfur battery prepared in Example 1 and the unmodified lithium-sulfur battery were tested, and the results were as follows: Figure 3 The first charge-discharge curve shown and as follows Figure 4 The diagram shows the cyclic capacity.

[0030] like Figure 3 As shown, in Example 2, the lithium-sulfur battery has a first-cycle discharge capacity of 1276 mAh / g at a 0.2C rate.

[0031] like Figure 4 As shown, in Example 2, the lithium-sulfur battery had a discharge capacity of 1180 mAh / g after 50 cycles at a 0.2C rate, with a capacity retention rate of 92.4%.

[0032] Example 3 This invention discloses a method for preparing a nitrogen-doped carbon quantum dot modified lithium-sulfur battery separator, comprising the following steps: Step 1: After washing and drying 0.75 g of waste nylon fabric, cut it into shreds of 1-2 mm. 2 The fabric fragments were obtained by immersing the fabric fragments in liquid nitrogen for 30 minutes to fully freeze and embrittle them. Then, 50 mg of activator ZnCl2 was added to form a mixture. Step 2: Place the mixture from Step 1 into a ball mill and grind it at 600 rpm for 3 minutes in an intermittent cycle, repeating the cycle 5 times, for a total of 15 minutes to form a uniform and fine mixed powder. Step 3: Place the mixed powder in a ceramic boat and put it into a microwave reactor. React at 500W for 10 minutes to obtain a dark brown powder. Step 3: After thoroughly grinding the obtained dark brown powder, dissolve it in deionized water and take the supernatant. Centrifuge to remove large particle impurities, then filter through a 0.22 μm filter membrane, and then dialyze with a dialysis bag (molecular weight cutoff 300 Da) for 48 hours to obtain a purified nitrogen-doped carbon quantum dot solution. After freezing at -40℃ for 12 hours, vacuum dry for 36 hours, and grind to obtain a brownish-yellow nitrogen-doped carbon quantum dot solid powder. Step 4: Disperse carbon nanotubes (CNTs), nitrogen-doped carbon quantum dot solid powder and polyvinylidene fluoride (PVDF) into N-methylpyrrolidone, stir until a slurry of suitable viscosity is formed, then coat it evenly onto a polypropylene diaphragm, dry it and cut it into round pieces for later use. The mass ratio of CNT, nitrogen-doped carbon quantum dot solid powder, and PVDF is 6:3:1.

[0033] A positive electrode slurry was coated onto carbon paper to serve as the oxygen electrode, and a lithium metal sheet was used as the counter electrode. The nitrogen-doped carbon quantum dot-modified lithium-sulfur battery separator prepared in Example 1 was used as the separator, and a 1 mol / L LiTFSI solution containing 100 mmol / L LiI (triethylene glycol dimethyl ether TEGDME as the organic solvent) was used as the organic electrolyte. The lithium-sulfur battery was assembled in a glove box under high-purity argon protection. The electrical performance of the lithium-sulfur battery prepared in Example 1 and the unmodified lithium-sulfur battery were tested, and the results were as follows: Figure 5 The first charge-discharge curve shown and as follows Figure 6 The diagram shows the cyclic capacity.

[0034] like Figure 5 As shown, in Example 3, the lithium-sulfur battery has a first-cycle discharge capacity of 1224 mAh / g at a 0.2C rate.

[0035] like Figure 6 As shown, in Example 3, the lithium-sulfur battery had a discharge capacity of 1070 mAh / g after 50 cycles at a 0.2C rate, with a capacity retention rate of 87.4%.

[0036] like Figure 7 As shown, by comparing the cycle capacity of lithium-sulfur batteries in Examples 1-3 at different rates, it can be seen that the discharge capacity of Example 2 at each rate is higher than that of Examples 1 and 3.

[0037] like Figure 8 As shown in Example 2, the lithium-sulfur battery with N-CQDs-modified separator has a first-cycle discharge capacity of 1276 mAh / g, which is much higher than the 802 mAh / g of the lithium-sulfur battery with unmodified polypropylene separator.

[0038] like Figure 9 As shown in Example 2, the lithium-sulfur battery using an N-CQDs-modified separator had a discharge capacity of 1180 mAh / g after 50 cycles, with a capacity retention rate of 92.4%. In contrast, the lithium-sulfur battery using an unmodified polypropylene separator had a discharge capacity of 391 mAh / g after 50 cycles, with a capacity retention rate of only 48.7%.

[0039] like Figure 10As shown in Example 2, the lithium-sulfur battery using N-CQDs-modified separator has a discharge capacity at all rates that is much higher than that of the lithium-sulfur battery using unmodified polypropylene separator.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for preparing a nitrogen-doped carbon quantum dot modified lithium-sulfur battery separator, characterized in that, Includes the following steps: Step 1: After cleaning and drying the waste nylon fabric, cut it into millimeter-sized fabric fragments. After soaking the fabric fragments in liquid nitrogen, add the activator ZnCl2 and grind them into a uniform mixed powder. Step 2: After microwave treatment of the mixed powder, a solid product is obtained. After grinding, a dark brown powder is obtained. Step 3: Dissolve the dark brown powder in deionized water, take the supernatant, centrifuge, filter, and dialyze to obtain a purified nitrogen-doped carbon quantum dot solution, freeze-dry to obtain nitrogen-doped carbon quantum dot solid powder; Step 4: Disperse conductive carbon, nitrogen-doped carbon quantum dot solid powder and binder into an organic solvent, stir to obtain a slurry, coat the slurry evenly on a polypropylene separator, dry and cut into round pieces to obtain a nitrogen-doped carbon quantum dot modified lithium-sulfur battery separator.

2. The method for preparing a nitrogen-doped carbon quantum dot modified lithium-sulfur battery separator according to claim 1, characterized in that, In step one, a ball mill is used for grinding. The ball mill rotates at 300-600 rpm and is used for intermittent cyclic grinding, which is repeated multiple times.

3. The method for preparing a nitrogen-doped carbon quantum dot modified lithium-sulfur battery separator according to claim 1, characterized in that, In step two, the microwave reaction power is 500-600W, and the processing time is 8-10 minutes.

4. The method for preparing a nitrogen-doped carbon quantum dot modified lithium-sulfur battery separator according to claim 1, characterized in that, In step three, use a 300Da dialysis bag for dialysis for 24-48 hours.

5. The method for preparing a nitrogen-doped carbon quantum dot modified lithium-sulfur battery separator according to claim 1, characterized in that, In step four, the conductive carbon material is selected from carbon nanotubes.

6. The method for preparing a nitrogen-doped carbon quantum dot modified lithium-sulfur battery separator according to claim 1, characterized in that, In step four, the organic solvent is selected from N... Methylpyrrolidone.

7. The method for preparing a nitrogen-doped carbon quantum dot modified lithium-sulfur battery separator according to claim 1, characterized in that, In step four, the adhesive is polyvinylidene fluoride.

8. The method for preparing a nitrogen-doped carbon quantum dot modified lithium-sulfur battery separator according to claim 1, characterized in that, In step four, the mass ratio of conductive carbon, nitrogen-doped carbon quantum dot solid powder and PVDF is 6-8:1-3:

1.

9. A nitrogen-doped carbon quantum dot modified lithium-sulfur battery separator obtained by the preparation method according to any one of claims 1-8.

10. A lithium-sulfur battery, characterized in that, The battery comprises a positive electrode, a negative electrode, an electrolyte, and a nitrogen-doped carbon quantum dot modified lithium-sulfur battery separator as described in claim 9, wherein the nitrogen-doped carbon quantum dot modified lithium-sulfur battery separator is disposed between the positive electrode and the negative electrode.

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