A preparation method and application of graphene composite nickel sulfide

Abstract

The present invention belongs to, but is not limited to, the field of energy storage materials technology and discloses a method for preparing graphene-composite nickel sulfide and its application. A nickel source, a carbon source, and a sulfur source compound are added to a certain amount of deionized water. After a period of vigorous stirring, a green, clear solution is obtained. The clear solution is frozen with liquid nitrogen and placed in a freeze dryer. After drying at a certain temperature for several hours, a precursor material is obtained. The prepared precursor material is placed in a high-temperature tube furnace and subjected to high-temperature heat treatment in an inert atmosphere to obtain the graphene-composite nickel sulfide. The nickel source and carbon source compounds are nickel citrate, and the sulfur source compound is thiourea, and the mass ratio of the two is 1:6 to 5:4. The method of the present invention has the advantages of simplicity, high efficiency, and low preparation cost. The prepared graphene-composite nickel sulfide has high electrical conductivity and excellent structural stability, and exhibits excellent electrochemical performance as a negative electrode for sodium ion batteries.

Description

Technical Field

[0001] The present invention belongs to but is not limited to the technical field of energy storage materials, and in particular relates to a preparation method of graphene composite nickel sulfide and applications thereof. Background Art

[0002] Sodium-ion batteries (SIBs) are attracting much attention as a potential alternative to lithium-ion batteries (LIBs) in large-scale energy storage systems due to their significant cost-effectiveness and the abundance of sodium resources in nature. Similar to LIBs, electrode materials are one of the key factors determining the electrochemical performance of SIBs. However, the larger ionic radius of sodium ions ( contrast Therefore, finding suitable sodium storage materials is of great significance for promoting the development of sodium-ion batteries.

[0003] Nickel sulfide, as a transition metal sulfide (TMCs) anode material based on a conversion mechanism, shows great potential as a negative electrode for SIBs. Nickel sulfide is not only abundant in the earth's crust and low in cost, but also has a high theoretical capacity (591 mAhg-1 for NiS and 446 mAhg-1 for NiS) through multi-electron conversion reactions. This value far exceeds the capacity of the current LIBs graphite anode. However, nickel sulfide also faces some challenges as a sodium storage anode material. First, its inherent low electrical conductivity limits the efficiency of electron transmission within the material, which in turn affects the electrochemical performance. Secondly, during the charge and discharge process, the nickel sulfide material will undergo a huge volume change, resulting in the instability of the electrode structure, thereby accelerating the capacity decay and affecting the rate performance. Therefore, improving the electrical conductivity of the material and optimizing the stability of the electrode structure are the key to developing high-performance nickel sulfide anodes.

[0004] Constructing carbonaceous composite nanostructures is an effective approach to improving the electrochemical performance of nickel sulfide for sodium storage. The strong rigidity of carbonaceous materials can buffer volume changes during charge and discharge, ensuring the structural stability of the electrode. Furthermore, the conductive network constructed by the carbonaceous composite facilitates rapid electron transport, increasing the material's electronic conductivity. Furthermore, nanostructuring can increase the material's specific surface area and shorten the electron / ion transmission distance, significantly enhancing the sodium storage capacity and rate capability of nickel sulfide. Currently used carbonaceous materials primarily include graphene, carbon nanotubes, and conductive polymers. Graphene is the most widely used carbon-based composite material due to its unique two-dimensional layered structure, extremely high theoretical specific surface area, high electrical conductivity, and excellent structural stability. However, graphene is currently primarily synthesized through the reduction of graphene oxide. Traditional methods for preparing graphene oxide are the Brodie, Staudenmaier, and Hummers methods, all of which rely on the reaction of graphite with large amounts of concentrated nitric acid, concentrated sulfuric acid, potassium permanganate, and other strong composite oxidants. While these methods are well-established and technologically mature, they pose drawbacks such as explosion risk, severe pollution, and long reaction times, making them difficult to scale up. Furthermore, existing graphene-nickel sulfide composites are typically achieved through physical and chemical methods, using simple mechanical and chemical bonding. Due to the weak bonding force between the two, significant improvements in the material's electrical conductivity and structural stability are difficult to achieve. Summary of the Invention

[0005] In response to the problems existing in the prior art, the present invention provides an efficient and convenient method for preparing graphene-composite nickel sulfide, and examines its electrochemical performance as the negative electrode of sodium ion batteries; the present invention significantly increases the electrical conductivity and structural stability of the nickel sulfide material by constructing a carbonaceous material composite nanostructure, thereby achieving high capacity, long cycle life and high rate of the nickel sulfide sodium storage negative electrode.

[0006] The present invention is achieved by a method for preparing graphene-composite nickel sulfide, comprising the following steps:

[0007] (1) Preparing a precursor: Add a nickel source, a carbon source, and a sulfur source compound to a certain amount of deionized water. After a period of vigorous stirring, a green clear solution is obtained. The clear solution is frozen with liquid nitrogen and placed in a freeze dryer. After drying at a certain temperature for several hours, a precursor material is obtained.

[0008] (2) Preparing graphene-composite nickel sulfide: placing the precursor material prepared in step (1) in a high-temperature tube furnace, and performing high-temperature heat treatment in an inert atmosphere to obtain graphene-composite nickel sulfide;

[0009] In the step (1), the nickel source and carbon source compound is nickel citrate, and the sulfur source compound is thiourea, and the mass ratio of the two added is 1:6 to 5:4.

[0010] Furthermore, in the step (1), the amount of deionized water added is 50 to 200 ml.

[0011] Furthermore, in the step (1), the stirring time is 0.5 to 12 hours.

[0012] Furthermore, in the step (1), the freeze-drying temperature is -30 to -60°C.

[0013] Furthermore, in the step (1), the freeze-drying time is 12 to 72 hours.

[0014] Furthermore, in step (2), the heating rate of the high-temperature heat treatment process is 2 to 5°C / min.

[0015] Furthermore, in the step (2), the holding temperature of the high-temperature heat treatment process is in the range of 400 to 1000° C., and the holding time is in the range of 1 to 10 hours.

[0016] Furthermore, in step (2), the inert atmosphere is one or both of argon and nitrogen.

[0017] The object of the present invention is to provide a graphene composite nickel sulfide prepared by the preparation method of the graphene composite nickel sulfide.

[0018] Another object of the present invention is to provide a sodium ion battery comprising: a negative electrode, a positive electrode, a separator between the positive and negative electrodes, and an electrolyte, wherein the negative electrode is prepared from the above-mentioned graphene composite nickel sulfide.

[0019] In combination with the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solutions to be protected by the present invention are as follows:

[0020] First, the present invention uses nickel citrate and thiourea as raw materials, and synthesizes a graphene-uniform composite nickel sulfide material in situ through a solution reaction and high-temperature calcination method;

[0021] The method of the present invention synthesizes graphene material in situ during the preparation of nickel sulfide, and simultaneously achieves the composite of nickel sulfide and graphene. Compared with other preparation technologies, this method does not require the cumbersome graphene preparation process, and the in-situ synthesis of graphene and nickel sulfide is achieved during the synthesis process of nickel sulfide and graphene. It has the advantages of simplicity, high efficiency and low preparation cost.

[0022] The graphene-composite nickel sulfide prepared by the present invention has high electrical conductivity and excellent structural stability, and exhibits excellent electrochemical performance as a sodium storage negative electrode.

[0023] Second, the main parameters of the present invention:

[0024] 1. Nickel source, carbon source and sulfur source compounds:

[0025] Nickel and carbon source: nickel citrate

[0026] Sulfur source: thiourea

[0027] Mass ratio: 1:6~5:4

[0028] 2. Deionized water:

[0029] Addition amount: 50~200ml

[0030] 3. Mixing time:

[0031] 0.5 to 12 hours

[0032] 4. Freeze drying:

[0033] Temperature: -30~-60℃

[0034] Time: 12 to 72 hours

[0035] 5. High temperature heat treatment:

[0036] Heating rate: 2~5℃ / min

[0037] Insulation temperature: 400~1000℃

[0038] Keep warm time: 1 to 10 hours

[0039] Inert atmosphere: argon or nitrogen

[0040] Technical problems solved by existing technologies:

[0041] 1. Complex preparation process and high cost issues:

[0042] Traditional methods for preparing graphene-composite nickel sulfide often involve multi-step reactions, resulting in complex processes and high costs. The present invention uses a one-step method to prepare the precursor material and perform high-temperature heat treatment, simplifying the preparation process and reducing production costs.

[0043] 2. Material structure and performance instability issues:

[0044] In existing technologies, composite materials often suffer from unstable structures and properties, which affects their effectiveness in practical applications. This invention ensures the structural stability and excellent performance of the graphene-nickel sulfide composite material by precisely controlling the stirring time, freeze-drying temperature and duration, and high-temperature heat treatment conditions.

[0045] 3. Environmental and safety issues:

[0046] Some chemical reagents used in traditional preparation methods are potentially harmful to the environment and operators. The present invention uses safe and non-toxic nickel citrate and thiourea as precursor materials, which improves the environmental friendliness and safety of the preparation process.

[0047] 4.Improvement of electrochemical performance of materials:

[0048] Existing graphene-composite nickel sulfide materials have limitations in their electrochemical performance. This invention significantly improves the material's conductivity and electrochemical stability by optimizing its preparation parameters, such as the temperature and duration of high-temperature heat treatment, enabling it to excel in battery energy storage applications.

[0049] Significant technological advancements achieved:

[0050] 1. Process simplification and cost reduction:

[0051] By preparing the precursor material in a one-step method and performing heat treatment under an inert atmosphere in a high-temperature tube furnace, the present invention simplifies the traditional complex preparation process, significantly reduces production costs, and improves the feasibility of industrial production.

[0052] 2. High stability and excellent performance:

[0053] Precise control of preparation parameters ensures the structural stability of graphene-composite nickel sulfide materials, improves the performance stability and durability of the materials in electrochemical applications, and broadens their application areas.

[0054] 3. Environmental friendliness and operational safety:

[0055] The selection of safe and non-toxic compounds such as nickel citrate and thiourea as precursor materials improves the environmental friendliness of the preparation process, reduces health hazards to operators, and complies with the principles of green chemistry.

[0056] 4. Significant improvement in electrochemical performance:

[0057] By optimizing high-temperature heat treatment conditions, the conductivity and electrochemical properties of the material were significantly improved, greatly increasing its application potential in sodium-ion battery energy storage devices and promoting the development of the energy materials field.

[0058] In summary, the present invention not only solves the problems of complex process, high cost, environmental safety and material performance stability in the existing technology by optimizing preparation parameters and selecting environmentally friendly and safe precursor materials, but also significantly improves the electrochemical properties of graphene composite nickel sulfide materials, providing a solid technical foundation for its application in energy storage and conversion equipment, and demonstrating significant technological progress and application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 This is a flow chart of a method for preparing graphene-composite nickel sulfide provided by an embodiment of the present invention;

[0060] Figure 2 The X-ray diffraction pattern (XRD) of the graphene composite nickel sulfide material obtained in Example 1 of the present invention;

[0061] Figure 3 This is a transmission electron microscopy (TEM) image of the graphene-composite nickel sulfide material obtained in Example 1 of the present invention;

[0062] Figure 4 The graphene composite nickel sulfide material obtained in Example 1 of the present invention is subjected to 200 mAg -1 Cycling performance diagram at current density of ;

[0063] Figure 5 is the X-ray diffraction pattern (XRD) of the graphene composite nickel sulfide material obtained in Example 2 of the present invention;

[0064] Figure 6 This is a transmission electron microscopy (TEM) image of the graphene-composite nickel sulfide material obtained in Example 2 of the present invention;

[0065] Figure 7 The graphene composite nickel sulfide material obtained in Example 2 of the present invention is subjected to 200 mAg -1 Cycling performance diagram at current density of ;

[0066] Figure 8 This is the X-ray diffraction pattern (XRD) of the graphene composite nickel sulfide material obtained in Example 3 of the present invention;

[0067] Figure 9 This is a transmission electron microscopy (TEM) image of the graphene-composite nickel sulfide material obtained in Example 3 of the present invention;

[0068] Figure 10 The graphene composite nickel sulfide material obtained in Example 3 of the present invention is subjected to 200 mAg -1 Cycling performance diagram at current density of . DETAILED DESCRIPTION

[0069] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0070] The following are two examples of the preparation method of the graphene-composite nickel sulfide:

[0071] Application Example 1:

[0072] 1. Preparation of precursor:

[0073] Nickel source, carbon source compound: nickel citrate, 10g

[0074] Sulfur source compound: thiourea, 24g (mass ratio is 1:2.4, within the range of 1:6 to 5:4)

[0075] Deionized water: 100ml (within the range of 50-200ml)

[0076] Stirring time: 6h (within the range of 0.5 to 12h)

[0077] Freeze drying temperature: -45°C (within the range of -30 to -60°C)

[0078] Freeze drying time: 48h (within the range of 12 to 72h)

[0079] 2. Preparation of graphene composite nickel sulfide:

[0080] High temperature heat treatment heating rate: 3℃ / min (within the range of 2~5℃ / min)

[0081] High temperature heat treatment holding temperature: 600℃ (within the range of 400~1000℃)

[0082] High temperature heat treatment holding time: 5h (within the range of 1 to 10h)

[0083] Inert atmosphere: Argon

[0084] Application Example 2:

[0085] 1. Preparation of precursor:

[0086] Nickel source, carbon source compound: nickel citrate, 20g

[0087] Sulfur source compound: thiourea, 16g (mass ratio is 5:4, within the range of 1:6 to 5:4)

[0088] Deionized water: 200ml (within the range of 50-200ml)

[0089] Stirring time: 12h (within the range of 0.5 to 12h)

[0090] Freeze drying temperature: -60℃ (within the range of -30~-60℃)

[0091] Freeze drying time: 72h (within the range of 12 to 72h)

[0092] 2. Preparation of graphene composite nickel sulfide:

[0093] High temperature heat treatment heating rate: 5℃ / min (within the range of 2~5℃ / min)

[0094] High temperature heat treatment holding temperature: 1000℃ (within the range of 400~1000℃)

[0095] High temperature heat treatment holding time: 10h (within the range of 1 to 10h)

[0096] Inert atmosphere: nitrogen

[0097] In these two examples, all parameters are within the ranges specified in the claims, demonstrating how to specifically apply the method for preparing graphene-composite nickel sulfide.

[0098] like Figure 1 As shown, a method for preparing graphene-composite nickel sulfide provided by an embodiment of the present invention comprises the following steps:

[0099] (1) Preparing a precursor: Add a nickel source, a carbon source, and a sulfur source compound to a certain amount of deionized water. After a period of vigorous stirring, a green clear solution is obtained. The clear solution is frozen with liquid nitrogen and placed in a freeze dryer. After drying at a certain temperature for several hours, a precursor material is obtained.

[0100] (2) Preparing graphene-composite nickel sulfide: placing the precursor material prepared in step (1) in a high-temperature tube furnace, and performing high-temperature heat treatment in an inert atmosphere to obtain graphene-composite nickel sulfide;

[0101] In the step (1), the nickel source and carbon source compound is nickel citrate, and the sulfur source compound is thiourea, and the mass ratio of the two added is 1:6 to 5:4.

[0102] Example 1

[0103] This embodiment includes the following steps:

[0104] (1) Nickel citrate and thiourea were added to 50 ml of deionized water in a mass ratio of 1:3, and stirred vigorously for 2 h to obtain a green clear solution. The solution was frozen in a liquid nitrogen environment and placed in a freeze dryer and dried at -60 °C for 12 h to obtain a precursor material.

[0105] (2) The obtained precursor material is subjected to high-temperature heat treatment. The specific heating program is: heating at a rate of 5°C / min and keeping at 600°C for 2h. The entire high-temperature heat treatment process is carried out in an argon atmosphere to obtain the target product.

[0106] Figure 2 The X-ray diffraction pattern (XRD) of the graphene composite nickel sulfide material obtained in Example 1 of the present invention is as follows: Figure 2 It can be seen that the X-ray diffraction peak of the graphene composite nickel sulfide obtained in Example 1 is similar to that of NiS 1.03 (JCPDS 02-1273) standard card, proving that the synthesized nickel sulfide is NiS 1.03 .

[0107] Figure 3 Transmission electron microscopy (TEM) of the graphene composite nickel sulfide material obtained in Example 1 of the present invention, Figure 3 It can be seen that in Example 1 of the present invention, the nickel sulfide obtained is nanoparticles of 50-100 nm and is evenly coated in the flaky graphene.

[0108] Figure 4 The graphene composite nickel sulfide material obtained in Example 1 of the present invention is subjected to 200 mAg -1 Cycling performance diagram under current density, Figure 4 The material showed a capacity of 638.6 mAhg -1 The first-week capacity and coulombic efficiency of the first week are 77.9%, and the sodium storage capacity after 300 cycles is 348.1 mAh g -1 , the capacity retention rate is 54.5%.

[0109] Example 2

[0110] This embodiment includes the following steps:

[0111] (1) Nickel citrate and thiourea were added to 80 ml of deionized water in a mass ratio of 2:3, and stirred vigorously for 2 h to obtain a green clear solution. The solution was frozen in a liquid nitrogen environment and placed in a freeze dryer and dried at -60 °C for 24 h to obtain a precursor material.

[0112] (2) The obtained precursor material is subjected to high-temperature heat treatment. The specific heating program is: heating at a rate of 8°C / min and keeping at 600°C for 2h. The entire high-temperature heat treatment process is carried out in an argon atmosphere to obtain the target product.

[0113] Figure 5 The X-ray diffraction pattern (XRD) of the graphene composite nickel sulfide material synthesized in Example 2 of the present invention is as follows: Figure 5 It can be seen that the X-ray diffraction peak of the graphene composite nickel sulfide obtained in Example 2 is similar to that of NiS1.03 (JCPDS 02-1273) standard card, proving that the synthesized nickel sulfide is NiS 1.03 .

[0114] Figure 6 This is a transmission electron microscopy (TEM) image of the graphene composite nickel sulfide material obtained in Example 2 of the present invention. Figure 6 It can be seen that in Example 2 of the present invention, the nickel sulfide obtained is nanoparticles of 100-120 nm and is evenly coated in the flaky graphene.

[0115] Figure 7 The graphene composite nickel sulfide material obtained in Example 2 of the present invention is subjected to 200 mAg -1 Cycling performance diagram under current density, Figure 7 The material showed a capacity of 259 mAhg -1 The first-week capacity and coulombic efficiency of the first week are 71.2%, and the sodium storage capacity after 300 cycles is 231.1 mAh g -1 , the capacity retention rate is 89.2%.

[0116] Example 3

[0117] This embodiment includes the following steps:

[0118] (1) Nickel citrate and thiourea were added to 100 ml of deionized water in a mass ratio of 1:1, and stirred vigorously for 4 h to obtain a green clear solution. The solution was frozen in a liquid nitrogen environment and placed in a freeze dryer and dried at -60 °C for 48 h to obtain a precursor material.

[0119] (2) The obtained precursor material is subjected to high-temperature heat treatment. The specific heating program is: heating at a rate of 5°C / min and keeping at 600°C for 2h. The entire high-temperature heat treatment process is carried out in an argon atmosphere to obtain the target product.

[0120] Figure 8 The X-ray diffraction pattern (XRD) of the graphene composite nickel sulfide material synthesized in Example 3 of the present invention is as follows: Figure 8 It can be seen that the X-ray diffraction peak of the graphene composite nickel sulfide obtained in Example 3 is similar to that of NiS 1.03 (JCPDS 02-1273) standard card, proving that the synthesized nickel sulfide is NiS 1.03 .

[0121] Figure 9 This is a transmission electron microscopy (TEM) image of the graphene composite nickel sulfide material obtained in Example 3 of the present invention. Figure 9 It can be seen that in Example 3 of the present invention, the nickel sulfide obtained is nanoparticles of 20-50 nm and is evenly coated in the flaky graphene.

[0122] Figure 10 The graphene composite nickel sulfide material obtained in Example 3 of the present invention is subjected to 200 mAg -1 Cycling performance diagram under current density, Figure 10 The material showed a 361.5 mAhg -1 The first-week capacity and coulombic efficiency of the first week are 76.9%, and there is no attenuation after 300 cycles. The sodium storage capacity is 386.3 mAh g -1 .

[0123] The above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with this technical field within the technical scope disclosed by the present invention and within the spirit and principles of the present invention should be covered by the scope of protection of the present invention.

Claims

1. A method for preparing graphene composite nickel sulfide, characterized in that: The following steps are involved: (1) Preparing a precursor: Add a nickel source, a carbon source, and a sulfur source compound to a certain amount of deionized water. After a period of vigorous stirring, a green clear solution is obtained. The clear solution is frozen with liquid nitrogen and placed in a freeze dryer. After drying at a certain temperature for several hours, a precursor material is obtained. (2) Preparing graphene-composite nickel sulfide: placing the precursor material prepared in step (1) in a high-temperature tube furnace, and performing high-temperature heat treatment in an inert atmosphere to obtain graphene-composite nickel sulfide; In the step (1), the nickel source and carbon source compound are nickel citrate, and the sulfur source compound is thiourea, and the mass ratio of the two is 1:6 to 5:4; In the step (2), the heating rate of the high temperature heat treatment process is 2-5°C / min; In the step (2), the holding temperature of the high-temperature heat treatment process is in the range of 400 to 1000° C. and the holding time is in the range of 1 to 10 hours; In the step (2), the inert atmosphere is one or both of argon and nitrogen.

2. The method for preparing graphene-composite nickel sulfide according to claim 1, wherein In the step (1), the amount of deionized water added is 50 to 200 ml.

3. The method for preparing graphene composite nickel sulfide according to claim 1, wherein In the step (1), the stirring time is 0.5 to 12 hours.

4. The method for preparing graphene-composite nickel sulfide according to claim 1, wherein In the step (1), the freeze-drying temperature is -30 to -60°C.

5. The method for preparing graphene-composite nickel sulfide according to claim 1, wherein In the step (1), the freeze-drying time is 12 to 72 hours.

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