A Co4S3 / Ni3S2@C-CNF catalytic material, its preparation method and application

Abstract

This invention discloses a Co4S3 / Ni3S2@C-CNF catalytic material, its preparation method, and its application. The method includes: 1. Dissolving Ni(NO3)2·6H2O, Co(NO3)2·6H2O, and urea in a mixed solution of isopropanol and deionized water, stirring until homogeneous, and then transferring the solution to a hydrothermal reactor. Maintaining the temperature at 100–120°C for 12–16 h, followed by washing and drying, yields a basic carbonate; 2. Dissolving the basic carbonate and thioacetamide in anhydrous ethanol and stirring until homogeneous, transferring the solution to a hydrothermal reactor, maintaining the temperature at 120–130°C for 6–12 h, followed by washing and drying, yields NiCo2S4; 3. Weighing hydrochloric acid... 4. Mix dopamine and NiCo2S4, add Tris solution to the mixture, stir in the dark to form NiCo2S4@PDA solution, filter to obtain NiCo2S4@PDA composite material; 5. Disperse bacterial cellulose BC and NiCo2S4@PDA composite material in deionized water and stir evenly, dry to obtain NiCo2S4@PDA / BC composite material; 6. Place NiCo2S4@PDA / BC composite material in a tube furnace and carbonize at high temperature to obtain Co4S3 / Ni3S2@C-CNF composite material, which has good adsorption effect on sulfides and improves the electrochemical performance of Li-S battery.

Description

Technical Field

[0001] This invention belongs to the field of lithium-sulfur battery technology, specifically a Co4S3 / Ni3S2@C-CNF catalytic material, its preparation method, and its application. Background Technology

[0002] Lithium-sulfur (Li-S) batteries are a new type of rechargeable battery with extremely high theoretical specific energy (2600Wh / kg). They are considered the most promising next-generation energy storage batteries. The cathode of lithium-sulfur batteries uses sulfur as the active material, and the specific capacity is as high as 1675mAh / g, which is 6 to 10 times that of the current commercial lithium-ion battery cathode materials lithium iron phosphate (170mAh / g) and lithium cobalt oxide (274mAh / g).

[0003] In addition, sulfur is one of the most abundant elements on Earth, and it is inexpensive, environmentally friendly and non-toxic. However, the commercialization of lithium-sulfur batteries is limited by problems such as the electronic insulation of sulfur and its discharge product lithium polysulfides, the shuttling of soluble polysulfides between the positive and negative electrodes, and the volume expansion of sulfur during charging and discharging. Therefore, it is necessary to continuously explore and develop new materials suitable for lithium-sulfur batteries to improve their electrochemical performance and promote their commercial application. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a Co4S3 / Ni3S2@C-CNF catalytic material, its preparation method, and its application. The prepared Co4S3 / Ni3S2@C-CNF catalytic material exhibits good adsorption effects on sulfides, thereby improving the electrochemical performance of Li-S batteries.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] A method for preparing a Co4S3 / Ni3S2@C-CNF catalytic material includes the following steps:

[0007] Step 1: First, take Ni(NO3)2·6H2O, Co(NO3)2·6H2O, urea, isopropanol and deionized water in the following proportions: (2-6g): (4-8g): (20-30g): 120mL: 24mL. Then, dissolve Ni(NO3)2·6H2O, Co(NO3)2·6H2O and urea in the mixed solution of isopropanol and deionized water, stir evenly, transfer to a hydrothermal reactor, and keep warm at 100-120℃ for 12-16h. Then wash and dry in sequence to obtain basic carbonate powder.

[0008] Step 2: First, take basic carbonate powder, thioacetamide, and anhydrous ethanol in the following proportions: (0.4-0.6g): (0.8-1.2g): (100-120mL). Then, dissolve the basic carbonate powder and thioacetamide in anhydrous ethanol, stir evenly, and transfer to a hydrothermal reactor. Keep it at 120-130℃ for 6-12 hours. Then, wash and dry the powder to obtain NiCo2S4 powder.

[0009] Step 3: First, weigh dopamine hydrochloride and NiCo2S4 powder at a mass ratio of 1:1 and mix them to obtain mixture A. Then, weigh an equal amount of Tris solution to mixture A, add mixture A to the Tris solution, stir in the dark to form NiCo2S4@PDA solution, filter, and obtain NiCo2S4@PDA composite material.

[0010] Step 4: Weigh the NiCo2S4@PDA composite material and bacterial cellulose BC at a mass ratio of 50:1. Then, take deionized water at a ratio of 10mg:1mL for NiCo2S4@PDA composite material and deionized water. Disperse the bacterial cellulose BC and NiCo2S4@PDA composite material in the deionized water and stir evenly. After drying, the NiCo2S4@PDA / BC composite material is obtained.

[0011] Step 5: Place the NiCo2S4@PDA / BC composite material in a tube furnace, first heat it from room temperature to 200℃ at a heating rate of 5℃ / min, then heat it to 600-700℃ at a heating rate of 2℃ / min, hold it at that temperature for 2 hours, and then cool it to room temperature with the furnace to obtain the Co4S3 / Ni3S2@C-CNF composite material.

[0012] Furthermore, the stirring in step 1 is performed using a magnetic stirrer for 30 minutes.

[0013] Furthermore, the stirring in step 2 is performed using a magnetic stirrer for 15 minutes.

[0014] Furthermore, the washing in steps 1 and 2 involves alternating washing with deionized water and anhydrous ethanol 3 to 5 times.

[0015] Furthermore, the drying in steps 1, 2, and 4 is carried out at 60°C for 12–24 hours.

[0016] Furthermore, the stirring time in step 3 is 6 to 24 hours in the dark.

[0017] Furthermore, the stirring time in step 3 is 6 hours in the dark.

[0018] A Co4S3 / Ni3S2@C-CNF catalytic material.

[0019] Application of a Co4S3 / Ni3S2@C-CNF catalytic material in lithium-sulfur battery separators, whereby the Co4S3 / Ni3S2@C-CNF catalytic material is used as a surface modification layer for commercial lithium-sulfur battery separators.

[0020] Compared with the prior art, the present invention has the following technical effects:

[0021] This invention first prepares NiCo2S4 powder through a simple process. Tris solution, dopamine hydrochloride, and NiCo2S4 are mixed and stirred in the dark to obtain a NiCo2S4@PDA composite material. The NiCo2S4@PDA composite material is then uniformly mixed with BC to obtain a NiCo2S4@PDA / BC composite material. The NiCo2S4@PDA / BC composite material is carbonized by high-temperature sintering to generate a highly conductive Co4S3 / Ni3S2@C-CNF composite material containing bimetallic sulfides Co4S3 and Ni3S2. Because hydroxylated BC has a fine network structure, it maintains this network structure after carbonization. The strong conductivity of the hydroxylated BC network can alleviate the aggregation of Co4S3 and Ni3S2, thereby exposing more active sites, effectively mitigating the "shuttle effect," and improving the adsorption effect on polysulfides. In summary, this invention not only has a simple preparation process and a short preparation cycle, but also produces Co4S3 / Ni3S2@C-CNF with excellent adsorption effects on sulfides.

[0022] Taking advantage of the excellent adsorption effect of Co4S3 / Ni3S2@C-CNF on sulfides, it was used as a modification layer for the Li-S battery separator, resulting in a modified Li-S battery separator. The modified Li-S battery separator can improve the specific capacity and cycle stability of Li-S batteries, endowing them with excellent electrochemical performance and providing broad prospects for the commercial application of Li-S batteries.

[0023] Especially when dopamine hydrochloride, NiCo2S4 powder, and Tris solution are mixed and stirred in the dark for 6 hours, the final product Co4S3 / Ni3S2@C-CNF exhibits better adsorption performance for sulfides. Li-S batteries assembled using this modified Li-S battery separator demonstrate an initial capacity as high as 1482.9 mAh g⁻¹ at 0.1C. -1 Even under 2C conditions, the capacity still reaches 878.8mAh g. -1 It exhibits high utilization of active sulfur; on the other hand, at 0.2C, the Li-S battery still maintains a capacity of 701.4 mAh g after 200 cycles. -1 At 2C, after 500 cycles, it can maintain 564.1 mAh g. -1With a capacity of only 0.025% per cycle, it exhibits excellent cycle stability. Attached Figure Description

[0024] Figure 1 XRD pattern of Co4S3 / Ni3S2@C-CNF prepared in Example 1 of this invention;

[0025] Figure 2 SEM image of NiCo2S4@PDA / BC prepared in Example 1 of this invention;

[0026] Figure 3 SEM image of Co4S3 / Ni3S2@C-CNF prepared in Example 1 of this invention;

[0027] Figure 4 Comparison of rate performance of Li-S batteries assembled with separators modified with different materials;

[0028] Figure 5 Comparison of cycling performance of Li-S batteries assembled with separators modified with different materials at 0.2C current density;

[0029] Figure 6 Comparison of cycling performance of Li-S batteries assembled with separators modified with different materials at 2C current density. Detailed Implementation

[0030] The specific content of the present invention will be further explained in detail below with reference to the embodiments.

[0031] Example 1

[0032] Step 1: Dissolve 4g Ni(NO3)2·6H2O, 6g Co(NO3)2·6H2O and 25g urea in a mixed solution of 120mL isopropanol and 24mL deionized water. Stir with a magnetic stirrer for 30min, then transfer to a hydrothermal reactor and keep warm at 120℃ for 15h. Wash three times with anhydrous ethanol and deionized water, and finally dry at 60℃ for 12h to obtain basic carbonate powder.

[0033] Step 2: Dissolve 0.4g of basic carbonate powder and 0.8g of thioacetamide in 120mL of anhydrous ethanol. Stir with a magnetic stirrer for 15min, then transfer to a hydrothermal reactor and keep warm at 120℃ for 6h. Then wash with anhydrous ethanol and deionized water three times alternately, and dry at 60℃ for 12h to obtain NiCo2S4 powder.

[0034] Step 3: First, weigh dopamine hydrochloride and NiCo2S4 powder at a mass ratio of 1:1 and mix them to obtain mixture A. Then, weigh an equal amount of Tris solution to mixture A, add mixture A to the Tris solution, stir for 6 hours in the dark to form NiCo2S4@PDA solution, filter, and obtain NiCo2S4@PDA composite material.

[0035] Step 4: Take 40 mg of bacterial cellulose BC and 2000 mg of NiCo2S4@PDA composite material and disperse them in 200 mL of deionized water and stir evenly. Dry at 60 °C for 12 h to remove excess water and obtain NiCo2S4@PDA / BC composite material.

[0036] Step 5: Place the NiCo2S4@PDA / BC composite material in a tube furnace, first heat it from room temperature to 200℃ at a heating rate of 5℃ / min, then heat it to 600℃ at a heating rate of 2℃ / min, hold it at that temperature for 2 hours, and then cool it to room temperature with the furnace to obtain the Co4S3 / Ni3S2@C-CNF composite material.

[0037] from Figure 1 It can be seen that after high-temperature heat treatment, NiCo2S4 in the NiCo2S4@PDA / BC composite material generates bimetallic sulfides Co4S3 and Ni3S2, which can provide more active sites when used as a membrane modification material, thereby alleviating the "shuttle effect" of soluble polysulfides at the positive and negative electrodes.

[0038] from Figure 2 It can be seen that the particle size of NiCo2S4 in NiCo2S4@PDA / BC is 2μm, and the bacterial cellulose BC connects the NiCo2S4 particles, which can effectively prevent NiCo2S4 from agglomerating, thereby exposing more active sites.

[0039] from Figure 3 It can be seen that after the bacterial cellulose BC in NiCo2S4@PDA / BC is carbonized at high temperature, carbon nanofibers are generated, which makes the resulting Co4S3 / Ni3S2@C-CNF have higher conductivity.

[0040] Co4S3 / Ni3S2@C-CNF, acetylene black, and PVDF were mixed and ground at a mass ratio of 8:1:1, and then NMP was added to prepare a uniform slurry. This slurry was then uniformly coated onto the surface of a commercial lithium-sulfur battery separator polypropylene membrane. After drying, a Co4S3 / Ni3S2@C-CNF modified separator was obtained. For comparison, using the same method, Co8NiS8 / Ni3S2-CNF, Co4S3 / Ni3S2@C, and NiCo2S4, prepared in the prior art, were each prepared into slurries and coated onto the surface of a commercial lithium-sulfur battery separator polypropylene membrane, respectively, to obtain Co8NiS8 / Ni3S2-CNF modified separator, Co4S3 / Ni3S2@C modified separator, and NiCo2S4 modified separator, respectively. Li-S batteries were assembled using these four modified separators, and various performance tests were conducted. The test results are as follows:

[0041] from Figure 4 It can be seen that when the Co4S3 / Ni3S2@C6-CNF prepared in Example 1 is used as a modification layer for the Li-S battery separator, the initial capacity of the Li-S battery reaches 1482.9 mAh g at 0.1C. -1 Even at 2C, its capacity still reaches 878.8mAh g. -1 All of these values ​​are higher than the capacities of Li-S batteries assembled with Co8NiS8 / Ni3S2-CNF modified separators, Co4S3 / Ni3S2@C modified separators, and NiCo2S4 modified separators. This shows that the Co4S3 / Ni3S2@C6-CNF restriction prepared in Example 1 improves the utilization rate of active sulfur in Li-S batteries.

[0042] from Figure 5 It can be seen that when Co4S3 / Ni3S2@C-CNF is used as the separator modification layer for Li-S batteries, the capacity of the Li-S battery can reach 701.4 mAh g after 200 cycles at a current density of 0.2C. -1 The capacity is significantly higher than that of lithium-sulfur batteries using Co8NiS8 / Ni3S2-CNF, Co4S3 / Ni3S2@C, and NiCo2S4 as battery separator modification layers.

[0043] from Figure 6 It can be seen that the Li-S battery using the Co4S3 / Ni3S2@C-CNF modified separator can maintain a current density of 564.1 mAh g⁻¹ after 500 cycles at 2C. -1 The specific capacity is high, with an average capacity loss of only 0.025% per cycle, exhibiting excellent cycle stability, which is significantly higher than the specific capacity of Li-S batteries using Co8NiS8 / Ni3S2-CNF modified separators under the same conditions.

[0044] Example 2

[0045] Step 1: Dissolve 2g Ni(NO3)2·6H2O, 4g Co(NO3)2·6H2O and 20g urea in a mixed solution of 120mL isopropanol and 24mL deionized water. Stir with a magnetic stirrer for 30min, then transfer to a hydrothermal reactor and keep warm at 100℃ for 12h. Wash with anhydrous ethanol and deionized water four times, and finally dry at 60℃ for 14h to obtain basic carbonate powder.

[0046] Step 2: Take 0.44g of basic carbonate powder and 0.9g of thioacetamide and dissolve them in 100mL of anhydrous ethanol. Stir with a magnetic stirrer for 15min, then transfer to a hydrothermal reactor and keep warm at 125℃ for 8h. Then wash with anhydrous ethanol and deionized water alternately 4 times and dry at 60℃ for 14h to obtain NiCo2S4 powder.

[0047] Step 3: First, weigh dopamine hydrochloride and NiCo2S4 powder at a mass ratio of 1:1 and mix them to obtain mixture A. Then, weigh an equal amount of Tris solution to mixture A, add mixture A to the Tris solution, stir in the dark for 14 hours to form NiCo2S4@PDA solution, filter, and obtain NiCo2S4@PDA composite material.

[0048] Step 4: Take 20 mg of bacterial cellulose BC and 1000 mg of NiCo2S4@PDA composite material and disperse them in 100 mL of deionized water and stir evenly. Dry at 60 °C for 14 h to remove excess water and obtain NiCo2S4@PDA / BC composite material.

[0049] Step 5: Place the NiCo2S4@PDA / BC composite material in a tube furnace, first heat it from room temperature to 200℃ at a heating rate of 5℃ / min, then heat it to 680℃ at a heating rate of 2℃ / min, hold it at that temperature for 2 hours, and then cool it to room temperature with the furnace to obtain the Co4S3 / Ni3S2@C-CNF composite material.

[0050] Example 3

[0051] Step 1: Dissolve 3g Ni(NO3)2·6H2O, 5g Co(NO3)2·6H2O and 24g urea in a mixed solution of 120mL isopropanol and 24mL deionized water. Stir with a magnetic stirrer for 30min, then transfer to a hydrothermal reactor and keep warm at 110℃ for 13h. Wash with anhydrous ethanol and deionized water five times, and finally dry at 60℃ for 16h to obtain basic carbonate powder.

[0052] Step 2: Take 0.48g of basic carbonate powder and 1.0g of thioacetamide and dissolve them in 110mL of anhydrous ethanol. Stir with a magnetic stirrer for 15min, then transfer to a hydrothermal reactor and keep warm at 130℃ for 10h. Then wash with anhydrous ethanol and deionized water alternately 5 times and dry at 60℃ for 16h to obtain NiCo2S4 powder.

[0053] Step 3: First, weigh dopamine hydrochloride and NiCo2S4 powder at a mass ratio of 1:1 and mix them to obtain mixture A. Then, weigh an equal amount of Tris solution to mixture A, add mixture A to the Tris solution, stir in the dark for 16 hours to form NiCo2S4@PDA solution, filter, and obtain NiCo2S4@PDA composite material.

[0054] Step 4: Take 10 mg of bacterial cellulose BC and 500 mg of NiCo2S4@PDA composite material and disperse them in 50 mL of deionized water and stir evenly. Dry at 60 °C for 16 h to remove excess water and obtain NiCo2S4@PDA / BC composite material.

[0055] Step 5: Place the NiCo2S4@PDA / BC composite material in a tube furnace, first heat it from room temperature to 200℃ at a heating rate of 5℃ / min, then heat it to 700℃ at a heating rate of 2℃ / min, hold it at that temperature for 2 hours, and then cool it to room temperature with the furnace to obtain the Co4S3 / Ni3S2@C-CNF composite material.

[0056] Example 4

[0057] Step 1: Dissolve 4g Ni(NO3)2·6H2O, 5g Co(NO3)2·6H2O and 26g urea in a mixed solution of 120mL isopropanol and 24mL deionized water. Stir with a magnetic stirrer for 30min, then transfer to a hydrothermal reactor and keep warm at 120℃ for 14h. Wash three times with anhydrous ethanol and deionized water, and finally dry at 60℃ for 18h to obtain basic carbonate powder.

[0058] Step 2: Take 0.5g of basic carbonate powder and 1.1g of thioacetamide and dissolve them in 120mL of anhydrous ethanol. Stir with a magnetic stirrer for 15min, then transfer to a hydrothermal reactor and keep warm at 120℃ for 12h. Then wash with anhydrous ethanol and deionized water three times alternately, and dry at 60℃ for 18h to obtain NiCo2S4 powder.

[0059] Step 3: First, weigh dopamine hydrochloride and NiCo2S4 powder at a mass ratio of 1:1 and mix them to obtain mixture A. Then, weigh an equal amount of Tris solution to mixture A, add mixture A to the Tris solution, stir in the dark for 18 hours to form NiCo2S4@PDA solution, filter, and obtain NiCo2S4@PDA composite material.

[0060] Step 4: Take 60 mg of bacterial cellulose BC and 3000 mg of NiCo2S4@PDA composite material and disperse them in 300 mL of deionized water and stir evenly. Dry at 60 °C for 18 h to remove excess water and obtain NiCo2S4@PDA / BC composite material.

[0061] Step 5: Place the NiCo2S4@PDA / BC composite material in a tube furnace, first heat it from room temperature to 200℃ at a heating rate of 5℃ / min, then heat it to 620℃ at a heating rate of 2℃ / min, hold it at that temperature for 2 hours, and then cool it to room temperature with the furnace to obtain the Co4S3 / Ni3S2@C-CNF composite material.

[0062] Example 5

[0063] Step 1: Take 5g Ni(NO3)2·6H2O, 7g Co(NO3)2·6H2O and 28g urea respectively and dissolve them in a mixed solution of 120mL isopropanol and 24mL deionized water. Stir with a magnetic stirrer for 30min, then transfer to a hydrothermal reactor and keep warm at 115℃ for 16h. Then wash with anhydrous ethanol and deionized water four times, and finally dry at 60℃ for 20h to obtain basic carbonate powder.

[0064] Step 2: Take 0.56g of basic carbonate powder and 1.2g of thioacetamide and dissolve them in 110mL of anhydrous ethanol. Stir with a magnetic stirrer for 15min, then transfer to a hydrothermal reactor and keep warm at 120℃ for 7h. Then wash with anhydrous ethanol and deionized water alternately 4 times and dry at 60℃ for 20h to obtain NiCo2S4 powder.

[0065] Step 3: First, weigh dopamine hydrochloride and NiCo2S4 powder at a mass ratio of 1:1 and mix them to obtain mixture A. Then, weigh an equal amount of Tris solution to mixture A, add mixture A to the Tris solution, stir in the dark for 18 hours to form NiCo2S4@PDA solution, filter, and obtain NiCo2S4@PDA composite material.

[0066] Step 4: Take 30 mg of bacterial cellulose BC and 1500 mg of NiCo2S4@PDA composite material and disperse them in 150 mL of deionized water and stir evenly. Dry at 60 °C for 20 h to remove excess water and obtain NiCo2S4@PDA / BC composite material.

[0067] Step 5: Place the NiCo2S4@PDA / BC composite material in a tube furnace, first heat it from room temperature to 200℃ at a heating rate of 5℃ / min, then heat it to 640℃ at a heating rate of 2℃ / min, hold it at that temperature for 2 hours, and then cool it to room temperature with the furnace to obtain the Co4S3 / Ni3S2@C-CNF composite material.

[0068] Example 6

[0069] Step 1: Dissolve 6g Ni(NO3)2·6H2O, 8g Co(NO3)2·6H2O and 30g urea in a mixed solution of 120mL isopropanol and 24mL deionized water. Stir with a magnetic stirrer for 30min, then transfer to a hydrothermal reactor and keep warm at 105℃ for 15h. Wash with anhydrous ethanol and deionized water five times, and finally dry at 60℃ for 24h to obtain basic carbonate powder.

[0070] Step 2: Dissolve 0.6g of basic carbonate powder and 0.48g of thioacetamide in 100mL of anhydrous ethanol. Stir with a magnetic stirrer for 15min, then transfer to a hydrothermal reactor and keep warm at 130℃ for 9h. Then wash with anhydrous ethanol and deionized water alternately 5 times, and dry at 60℃ for 24h to obtain NiCo2S4 powder.

[0071] Step 3: First, weigh dopamine hydrochloride and NiCo2S4 powder at a mass ratio of 1:1 and mix them to obtain mixture A. Then, weigh an equal amount of Tris solution to mixture A, add mixture A to the Tris solution, stir in the dark for 24 hours to form NiCo2S4@PDA solution, filter, and obtain NiCo2S4@PDA composite material.

[0072] Step 4: Take 50 mg of bacterial cellulose BC and 2500 mg of NiCo2S4@PDA composite material and disperse them in 250 mL of deionized water and stir evenly. Dry at 60 °C for 24 h to remove excess water and obtain NiCo2S4@PDA / BC composite material.

[0073] Step 5: Place the NiCo2S4@PDA / BC composite material in a tube furnace, first heat it from room temperature to 200℃ at a heating rate of 5℃ / min, then heat it to 660℃ at a heating rate of 2℃ / min, hold it at that temperature for 2 hours, and then cool it to room temperature with the furnace to obtain the Co4S3 / Ni3S2@C-CNF composite material.

[0074] Example 7

[0075] Step 1: Dissolve 5.6g Ni(NO3)2·6H2O, 7.4g Co(NO3)2·6H2O and 22g urea in a mixed solution of 120mL isopropanol and 24mL deionized water. Stir with a magnetic stirrer for 30min, then transfer to a hydrothermal reactor and keep warm at 100℃ for 16h. Wash three times with anhydrous ethanol and deionized water, and finally dry at 60℃ for 22h to obtain basic carbonate powder.

[0076] Step 2: Take 0.52g of basic carbonate powder and 1.2g of thioacetamide and dissolve them in 100mL of anhydrous ethanol. Stir with a magnetic stirrer for 15min, then transfer to a hydrothermal reactor and keep warm at 125℃ for 11h. Then wash with anhydrous ethanol and deionized water three times alternately, and dry at 60℃ for 22h to obtain NiCo2S4 powder.

[0077] Step 3: First, weigh dopamine hydrochloride and NiCo2S4 powder at a mass ratio of 1:1 and mix them to obtain mixture A. Then, weigh an equal amount of Tris solution to mixture A, add mixture A to the Tris solution, stir in the dark for 12 hours to form NiCo2S4@PDA solution, filter, and obtain NiCo2S4@PDA composite material.

[0078] Step 4: Take 40 mg of bacterial cellulose BC and 2000 mg of NiCo2S4@PDA composite material and disperse them in 200 mL of deionized water and stir evenly. Dry at 60 °C for 22 h to remove excess water and obtain NiCo2S4@PDA / BC composite material.

[0079] Step 5: Place the NiCo2S4@PDA / BC composite material in a tube furnace, first heat it from room temperature to 200℃ at a heating rate of 5℃ / min, then heat it to 650℃ at a heating rate of 2℃ / min, hold it at that temperature for 2 hours, and then cool it to room temperature with the furnace to obtain the Co4S3 / Ni3S2@C-CNF composite material.

Claims

1. A method for preparing a Co4S3 / Ni3S2@C-CNF catalytic material, characterized in that, Includes the following steps: Step 1: First, take Ni(NO3)2·6H2O, Co(NO3)2·6H2O, urea, isopropanol and deionized water in the following proportions: (2-6g): (4-8g): (20-30g): 120mL: 24mL. Then, dissolve Ni(NO3)2·6H2O, Co(NO3)2·6H2O and urea in the mixed solution of isopropanol and deionized water, stir evenly, transfer to a hydrothermal reactor, and keep warm at 100-120℃ for 12-16h. Then wash and dry in sequence to obtain basic carbonate powder. Step 2: First, take basic carbonate powder, thioacetamide, and anhydrous ethanol in the following proportions: (0.4-0.6g): (0.8-1.2g): (100-120mL). Then, dissolve the basic carbonate powder and thioacetamide in anhydrous ethanol, stir evenly, and transfer to a hydrothermal reactor. Keep it at 120-130℃ for 6-12 hours. Then, wash and dry the powder to obtain NiCo2S4 powder. Step 3: First, weigh dopamine hydrochloride and NiCo2S4 powder at a mass ratio of 1:1 and mix them to obtain mixture A. Then, weigh an equal amount of Tris solution to mixture A and add it to mixture A. Stir in the dark to form NiCo2S4@PDA solution. Filter the solution to obtain NiCo2S4@PDA composite material. Step 4: Weigh the NiCo2S4@PDA composite material and bacterial cellulose BC at a mass ratio of 50:

1. Then, take deionized water at a ratio of 10mg:1mL for NiCo2S4@PDA composite material and deionized water. Disperse the bacterial cellulose BC and NiCo2S4@PDA composite material in the deionized water and stir evenly. After drying, the NiCo2S4@PDA / BC composite material is obtained. Step 5: Place the NiCo2S4@PDA / BC composite material in a tube furnace, first heat it from room temperature to 200℃ at a heating rate of 5℃ / min, then heat it to 600-700℃ at a heating rate of 2℃ / min, hold it at that temperature for 2 hours, and then cool it to room temperature with the furnace to obtain the Co4S3 / Ni3S2@C-CNF composite material.

2. The preparation method of the Co4S3 / Ni3S2@C-CNF catalytic material according to claim 1, characterized in that, The stirring in step 1 is performed by stirring with a magnetic stirrer for 30 minutes.

3. The preparation method of the Co4S3 / Ni3S2@C-CNF catalytic material according to claim 1, characterized in that, The stirring in step 2 is performed by stirring with a magnetic stirrer for 15 minutes.

4. The preparation method of the Co4S3 / Ni3S2@C-CNF catalytic material according to claim 1, characterized in that, Both steps 1 and 2 involve washing with deionized water and anhydrous ethanol alternately 3 to 5 times.

5. The preparation method of the Co4S3 / Ni3S2@C-CNF catalytic material according to claim 1, characterized in that, The drying in steps 1, 2 and 4 is carried out at 60°C for 12 to 24 hours.

6. The preparation method of the Co4S3 / Ni3S2@C-CNF catalytic material according to claim 1, characterized in that, The stirring time in step 3 is 6 to 24 hours in the dark.

7. The preparation method of the Co4S3 / Ni3S2@C-CNF catalytic material according to claim 6, characterized in that, The stirring time in step 3 is 6 hours in the dark.

8. A Co4S3 / Ni3S2@C-CNF catalytic material prepared by the method according to any one of claims 1 to 7.

9. The application of the Co4S3 / Ni3S2@C-CNF catalytic material according to claim 8 in lithium-sulfur battery separators, characterized in that, Co4S3 / Ni3S2@C-CNF catalyst material as a surface modification layer for commercial lithium-sulfur battery separators.

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