Preparation method of sodium sulfide carbon limited pre-sodium coating based on single atom catalysis

Abstract

The application provides a preparation method of a sodium sulfide carbon confined pre-sodium coating based on single-atom catalysis, and belongs to the technical field of sodium battery materials. The method comprises the following steps: mixing cobalt phthalocyanine and melamine powder, and obtaining a composite powder through ultrasonic-assisted mechanical stirring and drying and grinding; blending the composite powder with sodium sulfate and polyvinylpyrrolidone in a certain proportion, and obtaining a precursor powder through stirring and drying and grinding; sintering the precursor powder in an argon atmosphere, so that sodium sulfate is converted into sodium sulfide in situ, and cobalt atoms in the cobalt phthalocyanine are dispersed in a carbon network in a single-atom state, thereby obtaining a single-atom cobalt catalysis-carbon confined sodium sulfide composite material; mixing the composite material with a conductive agent, a first binder and a first organic solvent, and preparing a slurry through stirring and defoaming stirring; coating the slurry on the surface of a positive electrode material to form a sodium supplement interface layer, and obtaining a positive electrode with a pre-sodium coating through vacuum drying. The application solves the problems of sodium loss in initial cycles of a sodium ion battery, long-term cycle performance decline and defects of traditional sodium supplement salts.

Description

Technical Field

[0001] This invention relates to the field of sodium battery materials technology, and in particular to a method for preparing a sodium sulfide carbon confined pre-sodium coating based on single-atom catalysis. Background Technology

[0002] Currently, lithium-ion batteries (LIBs) are the superior energy storage technology for portable devices and automotive applications. However, the scarcity and geographical limitations of lithium resources make it impossible to sustain and meet explosive market demand. Given the widespread availability and cost-effectiveness of sodium resources, sodium-ion battery (SIB) technology has emerged as a strong alternative to LIBs. In the initial cycling of SIBs, the negative electrode irreversibly consumes the limited sodium ions released from the positive electrode, leading to a decrease in initial coulombic efficiency (ICE) and consequently, energy density. Releasing the inherent full capacity of the positive electrode material throughout the battery system is a complex and challenging task. Especially when used in conjunction with mainstream hard carbon (HC) anodes, their relatively low ICE (70-90%) inevitably leads to the irreversible consumption of active sodium, resulting in a significant loss of overall cell capacity.

[0003] After long-term cycling, the reliable operation of sodium-ion batteries is hampered by structural degradation, impaired ion transport, and side reactions, leading to a decline in battery performance. For example, vanadium in sodium vanadium phosphate (NVP) may degrade at a rate of V0.05. 3+ dissolve V in the form of 4+ This leads to the collapse of the cathode material structure. Dissolved vanadium ions migrate to the anode surface, damaging the SEI layer and catalyzing sodium dendrite growth, resulting in cross-contamination. Furthermore, the migrating vanadium ions trigger continuous side reactions through redox shuttle effects. On the other hand, the parasitic irreversible reaction between exposed reactive Na and organic solvents, along with incomplete Na stripping, will collectively deplete the active Na in the cathode lattice. + in stock.

[0004] To address the aforementioned issues, improving sodium ion utilization and optimizing interfacial performance are crucial. Existing sodium replenishment technologies mostly employ traditional sodium salts, which suffer from drawbacks such as high decomposition potential and gas generation from side reactions, making it difficult to balance sodium replenishment efficiency with interfacial stability. Therefore, developing a pre-sodiuming technology that can efficiently compensate for sodium ions, suppress side reactions, and improve cycle performance is of great significance for promoting the practical application of sodium-ion batteries. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, the present invention aims to provide a method for preparing a sodium sulfide carbon-confined pre-sodium coating based on single-atom catalysis. This method involves converting sodium sulfate into sodium sulfide via carbothermic reduction at 800-900℃, utilizing an inert atmosphere to prevent oxidation and remove gaseous products. This confines the sodium sulfide within a three-dimensional carbon network, preventing aggregation and shortening the ion diffusion path. Simultaneously, the triple mechanism of cobalt single atoms reduces the sodium sulfide decomposition voltage and improves sodium replenishment efficiency, providing an efficient and stable solution for sodium replenishment technology in high-energy-density sodium-ion batteries. This synergistic optimization of ion transport and sodium replenishment processes significantly enhances the cycle stability, rate performance, and high-voltage tolerance of sodium-ion batteries, thereby improving their overall performance.

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

[0007] A method for preparing a sodium sulfide carbon-confined pre-sodium coating based on single-atom catalysis includes the following steps:

[0008] S1. Cobalt phthalocyanine CoPC is mixed with melamine powder and a slurry is obtained by ultrasonic-assisted mechanical stirring. After drying and grinding, a composite powder containing cobalt-nitrogen precursor is obtained.

[0009] S2. The composite powder is mixed with sodium sulfate (Na2SO4) and polyvinylpyrrolidone (PVP) in a certain proportion, and after stirring, drying and grinding, a precursor powder containing sodium source and carbon precursor is obtained.

[0010] S3. The precursor powder is sintered under an argon atmosphere to convert sodium sulfate into sodium sulfide Na2S in situ through a carbothermal reduction reaction. At the same time, the cobalt atoms in cobalt phthalocyanine are dispersed in the carbon network in a single-atom state to obtain a single-atom cobalt catalytic-carbon confined sodium sulfide SA-Co / Na2S@C composite material.

[0011] S4. The single-atom cobalt-catalyzed-carbon-confined sodium sulfide SA-Co / Na2S@C composite material is mixed with a conductive agent, a first binder and a first organic solvent, and then subjected to first degassing and stirring to obtain a slurry.

[0012] S5. The slurry is coated onto the surface of the cathode material to form a sodium-supplemented interface layer, and then dried under a first vacuum to obtain a cathode with a sodium sulfide carbon confined pre-sodium coating based on single-atom catalysis.

[0013] Preferably, in S1, the mass ratio of cobalt phthalocyanine CoPC to melamine powder is 1:30, and the mixing process is carried out in ammonia water, with ultrasonic time of 4-6 hours, and the slurry is made viscous by mechanical stirring.

[0014] Preferably, in S1, the drying conditions are vacuum drying at 75-85°C for 10-12 hours to remove solvents and volatile components.

[0015] Preferably, in step S2, the mass ratio of the composite powder, sodium sulfate, and polyvinylpyrrolidone is 1:4:1, the blending process is carried out in ethanol, and the stirring temperature is 80°C.

[0016] Preferably, in S2, the drying conditions are vacuum drying at 69-70℃ for 6-8 hours, followed by ball milling at a speed of 400-600 r / min.

[0017] Preferably, in S3, the heating rate of the sintering treatment is 2-5℃ / min, the sintering temperature is 800-900℃, and the holding time is 2-3h.

[0018] Preferably, in S3, the argon flow rate is 60 mL / min, and a segmented cooling strategy is adopted after sintering: natural cooling before 500°C, and cooling to room temperature with the furnace after 500°C.

[0019] Preferably, in S4, the mass ratio of the single-atom cobalt catalytic-carbon confined sodium sulfide SA-Co / Na2S@C composite material, the conductive agent, and the first binder is 3-6:3-6:1; the first binder is one or more of polyvinylidene fluoride, polymethyl methacrylate, or polyvinylidene fluoride-hexafluoropropylene copolymer.

[0020] Preferably, in S4, the first degassing stirring speed is 400-800 r / min, and the first organic solvent is N-methyl-2-pyrrolidone.

[0021] Preferably, in S5, the thickness of the sodium-supplementing interface layer is 5-15 μm, and the first vacuum drying condition is drying at 60°C for 12 hours.

[0022] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0023] (1) In the technical solution of the present invention, Na2SO4 is converted into Na2S by carbothermal reduction reaction in a high temperature environment of 800-900℃. The inert atmosphere plays a protective role, on the one hand preventing the generated Na2S from being oxidized, and on the other hand helping to remove the gaseous products CO2 or CO produced by the reaction. The Na2S generated in situ through this process will be uniformly confined inside the three-dimensional carbon network formed by the carbonization of polyvinylpyrrolidone (PVP), which can avoid agglomeration and shorten the path required for ion diffusion.

[0024] (2) This invention introduces a single-atom catalyst to reduce the Na2S decomposition voltage. The introduced cobalt single-atom SA-Co, relying on the triple mechanism of atomic-level active site construction, electronic structure regulation and reaction path optimization, can significantly reduce the Na2S decomposition voltage and improve the efficiency of the sodium replenishment process, providing a solution with both high efficiency and stable performance for sodium replenishment technology of high-energy-density sodium-ion batteries. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a flowchart of a method for preparing a sodium sulfide carbon confined pre-sodium coating based on single-atom catalysis according to the present invention;

[0027] Figure 2 This is a TEM image of SA-Co / Na2S@C provided in Embodiment 1 of the present invention;

[0028] Figure 3 XRD comparison images of Embodiment 1 and Comparative Examples 1-2 provided by the present invention;

[0029] Figure 4 A comparison diagram of the charge-discharge curves of half-cells in Embodiment 1 and Comparative Examples 1-2 provided by the present invention;

[0030] Figure 5 A comparison chart of long-cycle capacity retention rates between Example 1 and Comparative Examples 1-2 provided by the present invention;

[0031] Figure 6 A comparison chart of the full-cell charge-discharge curves of Example 1 and sodium vanadium phosphate NVP provided by the present invention;

[0032] Figure 7 A comparison chart of the full-cell long-cycle capacity retention of Example 1 provided by the present invention and sodium vanadium phosphate NVP. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] like Figure 1 As shown, this invention provides a method for preparing a sodium sulfide carbon-confined pre-sodium coating based on single-atom catalysis, comprising the following steps:

[0036] S1. Cobalt phthalocyanine CoPC is mixed with melamine powder and a slurry is obtained by ultrasonic-assisted mechanical stirring. After drying and grinding, a composite powder containing cobalt-nitrogen precursor is obtained.

[0037] S2. The composite powder is mixed with sodium sulfate (Na2SO4) and polyvinylpyrrolidone (PVP) in a certain proportion, and after stirring, drying and grinding, a precursor powder containing sodium source and carbon precursor is obtained.

[0038] S3. The precursor powder is sintered under an argon atmosphere to convert sodium sulfate into sodium sulfide Na2S in situ through a carbothermal reduction reaction. At the same time, the cobalt atoms in cobalt phthalocyanine are dispersed in the carbon network in a single-atom state to obtain a single-atom cobalt catalytic-carbon confined sodium sulfide SA-Co / Na2S@C composite material.

[0039] S4. The single-atom cobalt-catalyzed-carbon-confined sodium sulfide SA-Co / Na2S@C composite material is mixed with a conductive agent, a first binder and a first organic solvent, and then subjected to first degassing and stirring to obtain a slurry.

[0040] S5. The slurry is coated onto the surface of the cathode material to form a sodium-supplemented interface layer, and then dried under a first vacuum to obtain a cathode with a sodium sulfide carbon confined pre-sodium coating based on single-atom catalysis.

[0041] In step S1, the mass ratio of cobalt phthalocyanine (CoPC) to melamine powder is 1:30, and the mixing process is carried out in ammonia water with ultrasonic treatment for 4-6 hours. The slurry is then mechanically stirred until it reaches a viscous consistency. The drying conditions are vacuum drying at 75-85°C for 10-12 hours to remove solvents and volatile components.

[0042] In step S2, the mass ratio of the composite powder, sodium sulfate, and polyvinylpyrrolidone is 1:4:1, and the blending process is carried out in ethanol at a stirring temperature of 80°C. The drying conditions are vacuum drying at 69-70°C for 6-8 hours, followed by ball milling at a speed of 400-600 r / min.

[0043] In S3, the heating rate for sintering is 2-5℃ / min, the sintering temperature is 800-900℃, and the holding time is 2-3h. The argon flow rate is 60mL / min. After sintering, a segmented cooling strategy is adopted: natural cooling before 500℃, and then furnace cooling to room temperature after 500℃.

[0044] In step S4, the mass ratio of the single-atom cobalt-catalyzed carbon-confined sodium sulfide SA-Co / Na2S@C composite material, the conductive agent, and the first binder is 3-6:3-6:1; the first binder is one or more of polyvinylidene fluoride, polymethyl methacrylate, or polyvinylidene fluoride-hexafluoropropylene copolymer. The first degassing stirring speed is 400-800 r / min, and the first organic solvent is N-methyl-2-pyrrolidone.

[0045] In S5, the thickness of the sodium-supplementing interface layer is 5-15 μm, and the first vacuum drying condition is drying at 60°C for 12 hours.

[0046] Based on the above scheme, by uniformly coating SA-Co / Na2S@C onto the surface of sodium vanadium phosphate (NVP) cathode, this coating can serve as a "sodium source reservoir." During the initial charging process, the Na2S layer decomposes in situ to release active sodium, precisely compensating for sodium loss in the cathode lattice. Simultaneously, sodium polysulfides (NaPs) generated during sodium replenishment form a dynamic protective layer on the cathode surface, suppressing vanadium dissolution at a high voltage of 4.3V. The released Na... + After migrating to the hard carbon (HC) anode, a dense SEI is induced by solvation structure reconstruction, which reduces the interfacial impedance and yields a sodium-ion battery exhibiting excellent cycle stability and rate performance.

[0047] The following specific implementation methods will further verify the above content so that those skilled in the art can better understand and implement the present invention. However, the embodiments given are not intended to limit the present invention.

[0048] Example 1

[0049] In this embodiment, the preparation of the single-atom cobalt-catalyzed carbon-confined sodium sulfide SA-Co / Na2S@C composite material includes the following steps:

[0050] Step 1: Dissolve 0.2g of CoPc in 25wt% ammonia water and mix it with 6g of melamine powder. Stir the mixture with ultrasonic assistance until a uniformly dispersed slurry system is formed. Then, place the mixed slurry in a vacuum drying oven and heat-treat it at 70℃ for 12h to completely remove the solvent and volatile components. Finally, grind the dried product to obtain the composite powder.

[0051] Step 2: Mix 2g of Na2SO4, 500mg of PVP and 500mg of composite powder, dissolve in anhydrous ethanol, and magnetically stir at 80℃ and 300-500rpm until the solvent is completely evaporated; then place in a vacuum drying oven at 60℃ for 8h to obtain primary powder; then ball mill using a planetary ball mill (zirconia grinding balls, ball-to-material ratio 20:1, speed 400rpm) for 2h to obtain precursor powder with uniform particle size.

[0052] Step 3: The obtained precursor powder was placed in a tube furnace and a high-purity argon atmosphere with a flow rate of 60 ml / min was introduced. The temperature was increased to 800℃ at 5℃ / min and held at the temperature for 2 hours for carbothermic reduction reaction. Then, a segmented cooling strategy was adopted: natural cooling before 500℃, and furnace cooling to room temperature after 500℃. Finally, a single-atom cobalt-catalyzed carbon-confined sodium sulfide SA-Co / Na2S@C composite material with a three-dimensional porous carbon network confined structure was obtained.

[0053] The SA-Co / Na2S@C composite material prepared in Example 1 was used as a sodium supplement material in a sodium-ion battery for electrochemical performance testing. The procedure was as follows: SA-Co / Na2S@C material, polyvinylidene fluoride binder, and SuperP conductive agent in a mass ratio of 8:1:1 were weighed and sequentially added to N-methyl-2-pyrrolidone (NMP) to obtain a black slurry with a solid content of 40%. The black slurry was then coated onto aluminum foil and vacuum dried at 60°C for 12 hours. The solid content on the dried aluminum foil was 3.5 mg / cm³. -2 The dried coated aluminum foil was stamped into 12mm round discs as the positive electrode, sodium sheet as the negative electrode, Whatman GF / A as the separator between the positive and negative electrodes, and NP-035 as the electrolyte. The CR2016 button cell was assembled and its electrochemical performance was tested.

[0054] The material in this embodiment was characterized by transmission electron microscopy (TEM), and the results are as follows: Figure 2 As shown, the Na2S generated in situ in Example 1 is uniformly confined within the three-dimensional carbon network formed by the carbonization of polyvinylpyrrolidone (PVP), preventing aggregation, shortening the ion diffusion path, and promoting the release of more active Na during charging and discharging. + Used to supplement sodium.

[0055] Comparative Example 1

[0056] In this comparative example, the preparation of the single-atom cobalt / sodium sulfide@carbon composite material includes the following steps:

[0057] Step 1: Mix 2g of Na2SO4, 500mg of PVP, 200mg of Co(NO3)2 and 500mg of Ketjen Black (KB), dissolve in anhydrous ethanol, and magnetically stir at 80℃ and 300-500rpm until the solvent is completely evaporated; then place in a vacuum drying oven at 60℃ for 8h to obtain primary powder; then ball mill using a planetary ball mill (zirconia grinding balls, ball-to-material ratio 20:1, speed 400rpm) for 2h to obtain precursor powder with uniform particle size.

[0058] Step 2: Place the obtained precursor powder in a tube furnace, introduce a high-purity argon atmosphere with a flow rate of 60 ml / min, raise the temperature to 800℃ at 5℃ / min and hold it at the temperature for 2 hours for carbothermic reduction reaction, and then use a segmented cooling strategy: natural cooling before 500℃, and furnace cooling to room temperature after 500℃, finally obtaining a single-atom cobalt / sodium sulfide@carbon (NP-Co / Na2S@C) composite material with a three-dimensional porous carbon network confined structure.

[0059] Comparative Example 2

[0060] In this comparative example, the preparation of the single-atom cobalt / sodium sulfide@carbon composite material includes the following steps:

[0061] Step 1: Mix 2g of Na2SO4, 500mg of PVP, 200mg of Co(NO3)2 and 500mg of Ketjen Black (KB), dissolve in anhydrous ethanol, and magnetically stir at 80℃ and 300-500rpm until the solvent is completely evaporated; then place in a vacuum drying oven at 60℃ for 8h to obtain primary powder; then ball mill using a planetary ball mill (zirconia grinding balls, ball-to-material ratio 20:1, speed 400rpm) for 2h to obtain precursor powder with uniform particle size.

[0062] Step 2: Place the obtained precursor powder in a tube furnace, introduce a high-purity argon atmosphere with a flow rate of 60 ml / min, raise the temperature to 800℃ at 5℃ / min and hold it at the temperature for 2 hours for carbothermic reduction reaction, and then use a segmented cooling strategy: natural cooling before 500℃, and furnace cooling to room temperature after 500℃, finally obtaining a single-atom cobalt / sodium sulfide@carbon (Na2S@C) composite material with a three-dimensional porous carbon network confined structure.

[0063] The SA-Co / Na2S@C prepared in Example 1, the NP-Co / Na2S@C prepared in Comparative Example 1, and the Na2S@C prepared in Comparative Example 2 were characterized by X-ray diffraction (XRD), and the results are as follows. Figure 3As shown, it can be found that no characteristic peaks of the (002) and (102) crystal planes of metallic cobalt were detected in the spectrum of SA-Co / Na2S@C. Referring to Co JCPDS No. 89-4308 and Na2S JCPDS No. 23-0441, it is confirmed that cobalt is dispersed in the three-dimensional carbon network in a single-atom state and does not form metallic cobalt or nanoparticles.

[0064] Furthermore, the electrochemical performance of SA-Co / Na2S@C prepared in Example 1, NP-Co / Na2S@C prepared in Comparative Example 1, and Na2S@C prepared in Comparative Example 2 were tested, and the first cycle (0.1C) charge-discharge curves were obtained. The results are as follows: Figure 4 As shown, the SA-Co / Na2S@C battery prepared in Example 1 has a first-cycle (0.1C) charge specific capacity of up to 486.71 mAh g. -1 It has an excellent sodium supplementation effect; Figure 5 This is a comparison of the charge-discharge performance of a sodium-ion full cell assembled with a hard carbon (HC) anode and an NVP cathode modified with SA-Co / Na2S@C (i.e., p-NVP) in Example 1 of this invention at 0.5C, showing the NVP as a coating material and NVP as a hard carbon full cell. Figure 5 As can be seen, the first-week coulombic efficiency of the NVP||HC system is 56.37%, while that of the p-NVP||HC system is improved to 82.70%, and the first-week discharge specific capacity of the p-NVP||HC system reaches 26.68 mAh g. -1 This demonstrates that SA-Co / Na2S@C modification can effectively improve the coulombic efficiency and discharge capacity of sodium-ion full cells in the first week, verifying its positive role in improving the electrochemical performance of sodium-ion full cells in the first week. Figure 6 A comparison chart of the cycle curves of p-NVP-10 and NVP, from... Figure 6 As can be seen, after 300 cycles, the specific capacity retention of the p-NVP-10 system reached 87.85%, while that of the NVP system was 77.31%. This demonstrates that the p-NVP-10 system modified with SA-Co / Na2S@C exhibits superior cycle stability, verifying that this modification strategy can effectively improve the cycle stability of sodium-ion full batteries through the synergistic effect of dynamic sodium replenishment and interfacial catalysis, providing strong support for optimizing battery electrochemical performance and service life.

[0065] Reference Figure 7Analysis of p-NVP and NVP in Example 1 using intermittent titration with constant current (GITT) revealed that the sodium ion diffusion rate of p-NVP was higher than that of NVP during both charging and discharging processes. This indicates that sodium polysulfides (NaPs) generated from the decomposition of SA-Co / Na2S@C form a dynamic protective layer on the positive electrode surface, enabling p-NVP to exhibit faster sodium ion diffusion kinetics.

[0066] Therefore, the above-mentioned method for preparing sodium sulfide carbon-confined pre-sodium coating based on single-atom catalysis involves converting sodium sulfate into sodium sulfide through carbothermic reduction at 800-900℃, using an inert atmosphere to prevent oxidation and remove gaseous products, thus confining the sodium sulfide within a three-dimensional carbon network to prevent aggregation and shorten the ion diffusion path. Simultaneously, the triple mechanism of cobalt single atoms is utilized to reduce the sodium sulfide decomposition voltage and improve sodium replenishment efficiency, providing an efficient and stable solution for sodium replenishment technology in high-energy-density sodium-ion batteries. This synergistic optimization of ion transport and sodium replenishment processes significantly enhances the cycle stability, rate performance, and high-voltage tolerance of sodium-ion batteries, thereby improving their overall performance.

[0067] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0068] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for preparing a sodium sulfide carbon-confined pre-sodium coating based on single-atom catalysis, characterized in that, Includes the following steps: S1. Cobalt phthalocyanine CoPC is mixed with melamine powder and a slurry is obtained by ultrasonic-assisted mechanical stirring. After drying and grinding, a composite powder containing cobalt-nitrogen precursor is obtained. In S1, the mass ratio of cobalt phthalocyanine CoPC to melamine powder is 1:30, and the mixing process is carried out in ammonia water, with ultrasonic time of 4-6 hours, and the slurry is made viscous by mechanical stirring. S2. The composite powder is mixed with sodium sulfate (Na2SO4) and polyvinylpyrrolidone (PVP) in a certain proportion, and after stirring, drying and grinding, a precursor powder containing sodium source and carbon precursor is obtained. In S2, the mass ratio of the composite powder, sodium sulfate, and polyvinylpyrrolidone is 1:4:1, and the blending process is carried out in ethanol at a stirring temperature of 80°C. S3. The precursor powder is sintered under an argon atmosphere to convert sodium sulfate into sodium sulfide Na2S in situ through a carbothermal reduction reaction. At the same time, the cobalt atoms in cobalt phthalocyanine are dispersed in the carbon network in a single-atom state to obtain a single-atom cobalt catalytic-carbon confined sodium sulfide SA-Co / Na2S@C composite material. In S3, the heating rate of the sintering treatment is 2-5℃ / min, the sintering temperature is 800-900℃, and the holding time is 2-3h; S4. The single-atom cobalt-catalyzed-carbon-confined sodium sulfide SA-Co / Na2S@C composite material is mixed with a conductive agent, a first binder and a first organic solvent, and then subjected to first degassing and stirring to obtain a slurry. In S4, the mass ratio of the single-atom cobalt catalytic-carbon confined sodium sulfide SA-Co / Na2S@C composite material, the conductive agent, and the first binder is 3-6:3-6:1; the first binder is one or more of polyvinylidene fluoride, polymethyl methacrylate, or polyvinylidene fluoride-hexafluoropropylene copolymer. S5. The slurry is coated onto the surface of the cathode material to form a sodium-supplemented interface layer, and then dried under a first vacuum to obtain a cathode with a sodium sulfide carbon confined pre-sodium coating based on single-atom catalysis.

2. The method for preparing a sodium sulfide carbon-confined pre-sodium coating based on single-atom catalysis according to claim 1, characterized in that, In S1, the drying conditions are vacuum drying at 75-85°C for 10-12 hours to remove solvents and volatile components.

3. The method for preparing a sodium sulfide carbon-confined pre-sodium coating based on single-atom catalysis according to claim 1, characterized in that, In S2, the drying conditions are vacuum drying at 69-70℃ for 6-8 hours, followed by ball milling at a speed of 400-600 r / min.

4. The method for preparing a sodium sulfide carbon-confined pre-sodium coating based on single-atom catalysis according to claim 1, characterized in that, In S3, the argon flow rate is 60 mL / min. After sintering, a segmented cooling strategy is adopted: natural cooling before 500℃, and cooling to room temperature with the furnace after 500℃.

5. The method for preparing a sodium sulfide carbon-confined pre-sodium coating based on single-atom catalysis according to claim 1, characterized in that, In S4, the first degassing stirring speed is 400-800 r / min, and the first organic solvent is N-methyl-2-pyrrolidone.

6. The method for preparing a sodium sulfide carbon-confined pre-sodium coating based on single-atom catalysis according to claim 1, characterized in that, In S5, the thickness of the sodium-supplementing interface layer is 5-15 μm, and the first vacuum drying condition is drying at 60°C for 12 hours.

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