Nickel monatomic bridged MoS2 / carbon composite material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of potassium ion batteries, and particularly relates to a nickel monatomic bridged MoS2 / carbon composite material as well as a preparation method and application thereof. The composite material has a carbon-Ni / MoS2-carbon layered structure, Ni / MoS2 nanosheets are uniformly distributed on a hollow cubic carbon shell, MoS2 and a carbon layer are bridged by nickel single atoms through O-Ni-S covalent bonds, and an atomic-scale electron transmission channel is constructed. The preparation method comprises the following three steps: firstly, preparing the hollow cubic carbon shell; secondly, growing Ni / MoS2 nanosheets on the surface in situ; and finally, realizing nickel monatomic bridging through dopamine polymerization and carbonization treatment. The composite material shows excellent rate capability and cycling stability as a potassium ion battery negative electrode material. According to the invention, high conductivity of a carbon material and interface regulation and control of nickel monatomic bridging are integrated, and multi-dimensional synergistic interaction with stable structure, continuous conductivity and reversible reaction is realized.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of potassium ion batteries, in particular to a nickel single-atom bridged MoS2 / carbon composite material and a preparation method and application thereof. BACKGROUND

[0002] Lithium ion batteries have promoted the rapid development of portable devices and electric vehicles due to their high energy density and long cycle life, greatly improving the convenience of society. However, due to the high cost and scarcity of lithium resources, lithium ion batteries face resource bottlenecks and cost pressures in large-scale application fields such as renewable energy storage. To address this issue, researchers have turned their attention to other alkali metal ion battery systems.

[0003] Potassium ion batteries have attracted widespread attention due to the abundant resources, low cost and similar chemical properties of potassium. The standard redox potential of potassium (~2.93 V vs. SHE) is close to that of lithium (~3.04 V vs. SHE), enabling potassium ion batteries to achieve a working voltage comparable to lithium ion batteries, thereby having high energy density potential. In addition, the smaller Stokes radius of potassium ions results in weaker solvation effects and lower ion transport resistance in electrolytes, thereby facilitating fast charge transfer dynamics. On the other hand, potassium metal does not alloy with aluminum current collectors, so aluminum foil can be directly used as the negative electrode current collector, thereby effectively reducing the manufacturing cost and weight of the battery.

[0004] However, the larger ionic radius of potassium ions (1.38 Å) can easily cause significant volume expansion, lattice stress accumulation and structure pulverization during charging and discharging, resulting in poor rate performance and cycle performance of the material. To alleviate these problems, transition metal sulfides (TMSs) are widely explored as negative electrode materials for potassium ion batteries. Among them, molybdenum disulfide (MoS2) is considered one of the most promising negative electrode materials for potassium ion batteries due to its layered structure, large interlayer spacing (about 0.62 nm) and abundant active sites. MoS2 can achieve a high theoretical capacity through intercalation and conversion reactions (MoS2 Mo + K2S) during potassium storage. However, pure MoS2 has poor electrical conductivity (about 10 -4 S / cm), severe volume expansion and long ion diffusion paths, resulting in slow electrochemical reaction kinetics, poor cycle and rate performance, and difficulty in meeting the needs of high-performance energy storage devices.

[0005] To improve the conductivity and structural stability of MoS2, researchers have tried various modification strategies, including carbon material composite, metal doping, heterostructure construction and phase engineering regulation, etc. Among them, carbon coating and composite can improve the overall conductive network, but the electronic coupling between the interfaces is still limited; metal ion doping (such as Co, Fe, Ni, etc.) can adjust the local electronic structure, but it is easy to cause lattice distortion and even destroy the layered structure of MoS2 due to uneven doping or aggregation; and simple physical composite or weak chemical bond interface is easy to fail under long cycle conditions, resulting in increased interface contact resistance and blocked electron / ion transmission.

[0006] Therefore, the existing modification methods generally have the following shortcomings: (1) The doped metal is unevenly distributed or aggregated in the lattice, reducing the continuity of the interface electronic coupling; (2) The metal-sulfide interface has weak binding force and lacks stable chemical anchoring, which is easy to separate during the cycle; (3) The electronic transmission channel is discontinuous, the interface charge transfer efficiency is low, and the reaction kinetics is affected; (4) There is a lack of atomic-level regulation means for interface charge distribution and chemical bond configuration, making it difficult to simultaneously consider conductivity and structural stability.

[0007] In summary, there is an urgent need in the art for a regulation strategy that realizes stable interface connection and charge bridging at the atomic scale, to significantly improve the interface electronic conduction efficiency, optimize the ion diffusion kinetics, and enhance the cycle stability and rate response of the electrode while maintaining the integrity of the MoS2 layered structure.

[0008] The above information disclosed in the background technology is only used to increase the understanding of the background technology of the present application, and should not be regarded as acknowledging or implying in any form that the information constitutes prior art known to those skilled in the art. SUMMARY

[0009] To solve the problems existing in the prior art, the present application provides a nickel monatomic bridged MoS2 / carbon composite material, a preparation method and application thereof.

[0010] A nickel monatomic bridged MoS2 / carbon composite material has a layered structure of carbon-Ni / MoS2-carbon, and nickel monatomic atoms are connected to MoS2 and carbon layers through O-Ni-S chemical bonds to form an atomic-level electronic transmission channel.

[0011] A preparation method of a nickel monatomic bridged MoS2 / carbon composite material includes the following steps: (1) Preparation of hollow cubic carbon shell: cubic ferric oxide templates are prepared by hydrothermal reaction using ferric chloride and sodium hydroxide as raw materials; the templates are subjected to polymerization reaction with dopamine hydrochloride in an alkaline buffer solution, and the obtained polymer is collected as a precursor after centrifugation, washing and drying; the precursor is carbonized in an inert atmosphere, and the carbonized product is obtained after removing the templates by etching with a hydrochloric acid solution and washing and drying; (2) Preparation of hollow cubic carbon shell supported Ni / MoS2 nanosheet: the hollow cubic carbon shell obtained in step (1), a nickel source, a molybdenum source, a sulfur source and glucose are dispersed in a mixed solvent of water and ethanol, and after hydrothermal reaction, centrifugation, washing and drying, the hollow cubic carbon shell supported Ni / MoS2 nanosheet is obtained; (3) Preparation of nickel single-atom bridged MoS2 / carbon composite material: the hollow cubic carbon shell supported Ni / MoS2 nanosheet obtained in step (2) is subjected to polymerization reaction with dopamine hydrochloride in an alkaline buffer solution, and after centrifugation, washing and drying, carbonization treatment is carried out in a reducing atmosphere, and finally the nickel single-atom bridged MoS2 / carbon composite material is obtained.

[0012] Preferably, the temperature of the hydrothermal reaction in step (1) is 180-220 ℃, the reaction time is 4-7 days, the polymerization reaction time is 8-24 h, and the pH of the reaction system is 7-9.

[0013] Preferably, the temperature of the carbonization treatment in step (1) is 500-700 ℃, the heating rate is 1-5 ℃ / min, and the holding time is 1-4 h; the inert atmosphere is nitrogen or argon; the concentration of the hydrochloric acid solution is 2-6 mol / L, and the etching temperature is 30-50 ℃.

[0014] Preferably, the nickel source in step (2) includes one or more of nickel chloride hexahydrate, nickel nitrate hexahydrate, nickel acetate tetrahydrate and nickel sulfate hexahydrate; the molybdenum source is one or more of sodium molybdate dihydrate or ammonium molybdate tetrahydrate; and the sulfur source is one or more of thiourea, thioacetamide or L-cysteine.

[0015] Preferably, the volume ratio of water to anhydrous ethanol in step (2) is 1:2; the mass ratio of hollow cubic carbon shell to molybdenum source is 1:5-1:10; the mass ratio of hollow cubic carbon shell to glucose is 1:10; and the molar ratio of nickel source to molybdenum source is 1:3-1:12.

[0016] Preferably, the hydrothermal reaction temperature in step (2) is 180-220 ℃, and the holding time is 8-24 h.

[0017] Preferably, in step (3), the mass ratio of the hollow cubic carbon shell-supported Ni / MoS2 nanosheets to dopamine hydrochloride is 1:1 to 4:1; the polymerization reaction time is 2 to 8 h; and the pH of the reaction system is 7 to 9.

[0018] Preferably, the carbonization temperature in step (3) is 500~700 ℃, the heating rate is 1~5 ℃ / min, and the holding time is 1~4 h; the reducing atmosphere is an argon-hydrogen mixture.

[0019] An application of a nickel single-atom-bridged MoS2 / carbon composite material, which exhibits excellent rate performance and cycle stability when used as a negative electrode material for potassium-ion batteries.

[0020] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention employs a three-dimensional layered confinement structure of “inner hollow cubic carbon shell - middle MoS2 nanosheets - outer carbon layer”, which uniformly fixes MoS2 nanosheets between the inner hollow cubic carbon shell and the outer carbon layer to form a continuous conductive network. This structure provides a buffer space for the volume expansion of MoS2 during charging and discharging, effectively suppressing particle pulverization and electrode peeling, and enhancing the structural integrity of the electrode material. At the same time, the bidirectional electron transport pathway of the carbon layer significantly improves the overall conductivity, thereby improving the cycle life and rate response performance. (2) By regulating the formation of stable O-Ni-S covalent bridge bonds between nickel atoms and the MoS2-carbon interface, an atomic-level electronic channel was established. Nickel atoms act as an interfacial electronic bridge and charge regulation center, effectively reducing interfacial resistance, enhancing interfacial electronic coupling strength, establishing an efficient charge transport channel, and promoting the development of MoS2-carbon interfacial electron transport. The reversible reaction of Mo / K2S and the bridging mechanism transform the traditional physical contact into a strong chemical bond greatly suppress the detachment of MoS2 from the carbon substrate during cycling, overcome the drawbacks of metal agglomeration or interface desorption in traditional doping systems, and fundamentally improve the reaction kinetics. (3) This invention integrates the high conductivity of carbon materials with the interface regulation of nickel single-atom bridging, achieving multi-dimensional synergistic effects of structural stability, continuous conductivity, and reversible reaction, thereby effectively enhancing the electrochemical performance of potassium-ion battery anodes and solving the long-standing problem in the field of potassium-ion battery anode materials where "stability" and "kinetics" are difficult to achieve simultaneously. This invention provides a new structural design idea for constructing high-performance potassium-ion battery anode materials and can be extended to the preparation of other composite materials and various energy storage systems. Attached Figure Description

[0021] In order to more clearly illustrate the technical solutions of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. Obviously, the following described is only one embodiment of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the premise that there is no conflict between them.

[0022] Figure 1 The scanning electron microscope images of the NC@Ni / MoS2@NC composite material prepared in Example 1, wherein the scale of A is 500 nm, the scale of B is 200 nm, and the scale of C is 50 nm.

[0023] Figure 2 The X-ray diffraction patterns of the NC@Ni / MoS2@NC composite material prepared in Example 1 and the NC@MoS2@NC composite material prepared in Comparative Example 1.

[0024] Figure 3 The rate performance graphs of the NC@Ni / MoS2@NC composite material prepared in Example 1, the NC@MoS2@NC composite material prepared in Comparative Example 1 and the Ni / MoS2@NC composite material prepared in Comparative Example 2 as negative electrode materials.

[0025] Figure 4 The short cycle performance graphs of the NC@Ni / MoS2@NC composite material prepared in Example 1, the NC@MoS2@NC composite material prepared in Comparative Example 1 and the Ni / MoS2@NC composite material prepared in Comparative Example 2 as negative electrode materials.

[0026] Figure 5 The long cycle performance graph of the NC@Ni / MoS2@NC composite material prepared in Example 1 as a negative electrode material.

[0027] Figure 6 The long cycle performance graphs of the NC@MoS2@NC composite material prepared in Comparative Example 1 and the Ni / MoS2@NC composite material prepared in Comparative Example 2 as negative electrode materials. DETAILED DESCRIPTION

[0028] The present application provides a nickel single-atom bridged MoS2 / carbon composite material, a preparation method and an application thereof. In order to facilitate those skilled in the art to understand the present application, the specific embodiments of the present application will be described below with reference to the drawings. The technical features involved in each embodiment of the present application described below can be combined with each other as long as there is no conflict between them. The raw materials used in the embodiments are conventional raw materials and can be obtained commercially unless otherwise specified. The methods used in the embodiments are conventional methods and are prior art unless otherwise specified.

[0029] Example 1 A preparation method of a nickel single-atom bridged MoS2 / carbon composite material, the specific steps are as follows: (1) Under strong magnetic stirring, 18 mL (6.0 mol / L) of sodium hydroxide solution was slowly added to 20 mL (2.0 mol / L) of ferric chloride solution, and the mixed solution was transferred to a 100 mL high-pressure reactor, and reacted at 100°C for 7 days. After centrifugation, washing and drying, a cubic ferric oxide template was obtained. Then, 400 mg of ferric oxide particles were dispersed in a 10 mmol / L tris (hydroxymethyl) aminomethane buffer solution (400 mL), stirred for 30 min, and then 200 mg of dopamine hydrochloride was added and dissolved. The pH value of the solution was adjusted to about 8.5 by 2 mol / L HCl solution, and continuously stirred for 12 h under this condition. After the reaction was completed, the product was collected by centrifugation and dried, and then carbonized under an argon atmosphere (heating rate 2 ℃ / min, 550 ℃ for 3 h). Then, the carbonized product was etched in a 45 ℃ hydrochloric acid solution (4 mol / L) for 72 h to remove the template, and after drying, a hollow cubic carbon shell material (denoted as NC) was obtained; (2) Hollow cubic carbon shell (10 mg), nickel acetate tetrahydrate (0.05 mmol), sodium molybdate dihydrate (0.3 mmol), L-cysteine (210 mg) and glucose (100 mg) were dispersed in a mixture of 10 mL water and 20 mL anhydrous ethanol. Then, the mixed solution was transferred to a 50 mL high-pressure reactor and kept at 200°C for 12 h. After centrifugation and drying, a hollow cubic carbon shell supported Ni / MoS2 nanosheet (denoted as Ni / MoS2@NC) was obtained, wherein the glucose not only serves as a dispersant to control the uniform growth of MoS2 on the hollow carbon shell, but also as a reducing agent to facilitate the incorporation of Ni single atoms; (3) Ni / MoS2@NC (50 mg) and dopamine hydrochloride (25 mg) were dispersed in a tris (hydroxymethyl) aminomethane buffer solution (100 mL, 10 mmol / L), and continuously stirred for 5 h. The product was collected by centrifugation and dried. Then, carbonization treatment was carried out under an argon-hydrogen mixed gas atmosphere (heating rate 2 ℃ / min, 500 ℃ for 2 h), and a nickel single-atom bridged MoS2 / carbon composite material (denoted as NC@Ni / MoS2@NC) was obtained.

[0030] Example 2 A preparation method of a nickel single-atom bridged MoS2 / carbon composite material, the specific steps are as follows: The difference between Example 2 and Example 1 is that the amount of nickel acetate tetrahydrate is changed to 0.025 mmol, and other parameters remain unchanged.

[0031] Example 3 A preparation method of a nickel single-atom bridged MoS2 / carbon composite material, the specific steps are as follows: Example 3 is different from example 1 in that the amount of nickel acetate tetrahydrate is changed to 0.1 mmol, and other parameters remain unchanged.

[0032] Example 4 A preparation method of a nickel single-atom bridged MoS2 / carbon composite material, the specific steps are as follows: Example 4 is different from example 1 in that L-cysteine is changed to thiourea, and other parameters remain unchanged.

[0033] Comparative example 1 A preparation method of a MoS2 / carbon composite material, the specific steps are as follows: Comparative example 1 is different from example 1 in that no nickel acetate tetrahydrate is added, and other parameters remain unchanged (NC@MoS2@NC).

[0034] Comparative example 2 A preparation method of a hollow cubic carbon shell supported Ni / MoS2 composite material, the specific steps are as follows: Comparative example 2 is different from example 1 in that step (3) in example 1 is not implemented, and other parameters remain unchanged.

[0035] Material characterization and electrochemical performance test The present application successfully prepared a nickel single-atom bridged MoS2 / carbon composite material with a layered hollow structure, which was confirmed to have significant advantages in microstructure design and electrochemical performance through physical characterization and electrochemical performance test, and was particularly suitable for high-performance potassium ion battery negative materials. The following describes the NC@Ni / MoS2@NC composite material prepared in example 1 as a representative, and compares it with the comparative example.

[0036] As shown in Figure 1 A and B, the NC@Ni / MoS2@NC composite material prepared in example 1 of the present application has a cubic morphology, with an average size of 400±50 nm, and the Ni / MoS2 nanosheet is uniformly distributed on the surface of the hollow cubic carbon shell, showing a highly uniform morphology, as shown in Figure 1 C, the double-dashed line is the inner carbon layer with a certain thickness, and the outer dashed line is the outer carbon layer. This structure shows that the prepared NC@Ni / MoS2@NC composite material has good hierarchical distribution and spatial confinement characteristics, which provides favorable conditions for electron transmission and structural stability.

[0037] Figure 2X-ray diffraction patterns of the composite of NC@Ni / MoS2@NC prepared in Example 1 and NC@MoS2@NC prepared in Comparative Example 1. It can be seen that the diffraction peaks at 32.6° and 58.3° correspond to the (100) and (110) crystal planes of 2H-MoS2 (standard card JCPDS No. 37-1492), respectively. Compared with NC@MoS2@NC, the (002) crystal plane diffraction peak of NC@Ni / MoS2@NC is obviously shifted from 9.7° to 9.2°, and a new peak of (004) crystal plane appears at 17.5°, indicating that the introduction of nickel monatomic atoms causes the expansion of the MoS2 interlayer spacing, and at the same time forms a composite structure of carbon layer and MoS2 layer alternately stacked.

[0038] The NC@Ni / MoS2@NC obtained in Example 1, the NC@MoS2@NC obtained in Comparative Example 1 and the Ni / MoS2@NC obtained in Comparative Example 2 were respectively used as negative electrode materials for potassium ion half-batteries, and the electrochemical performance thereof was tested, with the specific steps as follows: The NC@Ni / MoS2@NC obtained in Example 1, the NC@MoS2@NC obtained in Comparative Example 1 and the Ni / MoS2@NC obtained in Comparative Example 2 were respectively used as active materials, and the active materials, conductive carbon black and carboxymethyl cellulose were mixed with deionized water / anhydrous ethanol (volume ratio 3:1) in a mass ratio of 8:1:1, and then grinded uniformly. The obtained slurry was uniformly coated on a copper foil, and dried in a vacuum oven at 70°C to obtain an active material electrode. With the active material electrode as the negative electrode, metallic potassium as the counter electrode, glass fiber as the separator, and 1.5 mol / L potassium bisfluorosulfonylimide (KFSI) dissolved in ethylene carbonate and diethyl carbonate (volume ratio 1:1) as the electrolyte, all the test electrodes were assembled into CR2032 type coin cells in an argon-filled glove box.

[0039] As Figure 3The rate performance of the NC@Ni / MoS2@NC prepared in Example 1 of the present application, the NC@MoS2@NC prepared in Comparative Example 1 and the Ni / MoS2@NC prepared in Comparative Example 2 as the negative electrode material was compared. At a current density of 0.1, 0.2, 0.5, 1, 2, 5 and 10 A / g, the NC@Ni / MoS2@NC electrode maintained a reversible capacity of 457, 424, 401, 369, 333, 288 and 255 mAh / g, respectively. When the current density returned to 0.1 A / g, the capacity could still rise to 430 mAh / g, showing excellent rate recovery performance. In contrast, the NC@MoS2@NC without the introduction of nickel monatomic and the Ni / MoS2@NC lacking the outer carbon coating both showed obvious capacity decay, indicating that the interface bridging of the nickel monatomic and the double carbon layer confinement structure played a significant role in enhancing the electrochemical reaction kinetics.

[0040] As shown in Figure 4 , the short-term cycle stability of the NC@Ni / MoS2@NC prepared in Example 1 of the present application, the NC@MoS2@NC prepared in Comparative Example 1 and the Ni / MoS2@NC prepared in Comparative Example 2 as the negative electrode material at 0.1 A / g was compared. The NC@Ni / MoS2@NC still maintained a high reversible capacity of 427 mAh / g after 100 cycles, while the capacity of the comparative sample decayed obviously. This shows that the bridging effect of the nickel monatomic and the stability of the double carbon layer confinement structure are indispensable for achieving high performance, and the two produce a synergistic enhancement effect.

[0041] Figure 5 Further shows the long-term cycle performance of the NC@Ni / MoS2@NC composite material prepared in Example 1 of the present application as the negative electrode material at 1 A / g, after 1200 cycles, the reversible capacity can reach 244 mAh / g, Figure 6 shows the long-term cycle performance of the NC@MoS2@NC prepared in Comparative Example 1 and the Ni / MoS2@NC prepared in Comparative Example 2 as the negative electrode material at 1 A / g, after 500 cycles, the specific capacity of both decayed to 100 mAh / g. The NC@Ni / MoS2@NC is obviously superior to the NC@MoS2@NC and the Ni / MoS2@NC, indicating that the nickel monatomic bridging structure effectively improves the cycle stability of MoS2. Combined with Figure 3 , Figure 4 , it can be seen that the nickel monatomic bridging structure plays a key role in improving the electron transmission rate, stabilizing the interface combination and promoting the MoS2 reversibility of the Mo / K2S conversion reaction.

[0042] In summary, the structural characterization and electrochemical test results jointly verify the synergistic enhancement effect of the nickel single-atom bridging and the layered limited structure in the nickel single-atom bridging MoS2 / carbon composite material designed in the application. The nickel atom forms a stable O-N-S bond bridge between the carbon and MoS2 interface, which not only improves the electronic coupling efficiency and interface stability, but also improves the reaction kinetics of potassium ion intercalation and deintercalation, so that the specific capacity, rate performance and cycle life of the material are significantly improved compared with the unmodified MoS2 / carbon composite material.

[0043] It can be understood that the above-mentioned embodiments of the application do not constitute a limitation on the protection scope of the application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the application shall be included in the protection scope of the claims of the application.

Claims

1. A nickel-single-atom-bridged MoS2 / carbon composite material, characterized in that: The nickel single-atom-bridged MoS2 / carbon composite material has a layered structure of carbon-Ni / MoS2-carbon, and the nickel single atoms connect MoS2 and the carbon layer through O-Ni-S chemical bonds to form an atomic-level electron transport channel.

2. A method for preparing the nickel single-atom bridged MoS2 / carbon composite material as described in claim 1, characterized in that, Includes the following steps: (1) Preparation of hollow cubic carbon shell: Cubic ferric oxide template was prepared by hydrothermal reaction using ferric chloride and sodium hydroxide as raw materials; The template is polymerized with dopamine hydrochloride in an alkaline buffer solution. The polymer obtained after centrifugation, washing and drying is used as a precursor. The precursor is carbonized in an inert atmosphere. The carbonized product is etched with hydrochloric acid solution to remove the template. After washing and drying, a hollow cubic carbon shell is obtained. (2) Preparation of Ni / MoS2 nanosheets supported by hollow cubic carbon shell: The hollow cubic carbon shell, nickel source, molybdenum source, sulfur source and glucose obtained in step (1) are dispersed in a mixed solvent of water and ethanol. After hydrothermal reaction, the nanosheets are centrifuged, washed and dried to obtain Ni / MoS2 nanosheets supported by hollow cubic carbon shell. (3) Preparation of nickel single-atom bridged MoS2 / carbon composite material: The hollow cubic carbon shell supported Ni / MoS2 nanosheets obtained in step (2) are polymerized with dopamine hydrochloride in an alkaline buffer solution. After centrifugation, washing and drying, carbonization is carried out in a reducing atmosphere to finally obtain the nickel single-atom bridged MoS2 / carbon composite material.

3. The preparation method according to claim 2, characterized in that: The hydrothermal reaction in step (1) is carried out at a temperature of 180~220 ℃, for a reaction time of 4~7 days, for a polymerization reaction time of 8~24 h, and for a reaction system pH of 7~9.

4. The preparation method according to claim 2, characterized in that: The carbonization treatment in step (1) is carried out at a temperature of 500~700 ℃, a heating rate of 1~5 ℃ / min, and a holding time of 1~4 h; the inert atmosphere is nitrogen or argon; the concentration of the hydrochloric acid solution is 2~6 mol / L, and the etching temperature is 30~50 ℃.

5. The preparation method according to claim 2, characterized in that: The nickel source in step (2) is one or more of nickel chloride hexahydrate, nickel nitrate hexahydrate, nickel acetate tetrahydrate, and nickel sulfate hexahydrate; the molybdenum source is one or more of sodium molybdate dihydrate or ammonium molybdate tetrahydrate; and the sulfur source is one or more of thiourea, thioacetamide, or L-cysteine.

6. The preparation method according to claim 2, characterized in that: In step (2), the volume ratio of water to ethanol is 1:2; the mass ratio of hollow cubic carbon shell to molybdenum source is 1:5 to 1:10; the mass ratio of hollow cubic carbon shell to glucose is 1:10; and the molar ratio of nickel source to molybdenum source is 1:3 to 1:

12.

7. The preparation method according to claim 2, characterized in that: The temperature of the hydrothermal reaction in step (2) is 180~220 ℃, and the holding time is 8~24 h.

8. The preparation method according to claim 2, characterized in that: In step (3), the mass ratio of the hollow cubic carbon shell-supported Ni / MoS2 nanosheets to dopamine hydrochloride is 1:1 to 4:1; the polymerization reaction time is 2 to 8 h; and the pH of the reaction system is 7 to 9.

9. The preparation method according to claim 2, characterized in that: The carbonization process in step (3) is carried out at a temperature of 500-700 °C, a heating rate of 1-5 °C / min, and a holding time of 1-4 h; the reducing atmosphere is an argon-hydrogen mixture.

10. The application of the nickel single-atom bridged MoS2 / carbon composite material as described in claim 1, characterized in that: The nickel single-atom-bridged MoS2 / carbon composite material is used as a negative electrode material in potassium-ion batteries or other alkali metal-ion batteries.

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