A conversion-type nickel-copper sulfide negative electrode material and preparation, battery

Abstract

The application discloses a conversion type nickel-copper sulfide negative material and a preparation method and a battery, and belongs to the field of sodium ion batteries. The preparation method comprises the following steps: S1, preparing an electrolyte: dissolving a nickel source, a copper source, a sulfur source and ammonium chloride in a solvent, stirring and dissolving to obtain the electrolyte; S2, electrodeposition: using the electrolyte in the step S1, performing electrodeposition in a three-electrode system, and performing cleaning and drying after the electrodeposition is completed to obtain an electrodeposition product; S3, annealing treatment: annealing the electrodeposition product in the step S2 to obtain the conversion type nickel-copper sulfide negative material. The method has the advantages of simple synthesis and mild conditions, meets the requirements of green development, and is beneficial to industrial application and popularization. The prepared negative material not only has a high capacity, but also has the advantages of good kinetics and stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of sodium ion batteries, in particular, to a conversion type nickel copper sulfide negative electrode material and preparation and battery. BACKGROUND

[0002] Energy problems are the shackles that restrict the development of human civilization and society, and the development of new energy technology not only can promote the progress of technology, but also can empower the economy. Lithium ion batteries (LIBs) are widely used in our daily life as an efficient energy conversion device. However, the shortage of lithium resources has led to a surge in prices, limiting its further development in the future. Sodium ion batteries (SIBs) have similar charging and discharging mechanisms as lithium ion batteries (LIBs), and sodium resources are widely studied due to their low cost and wide distribution. In addition to cost advantages, SIBs also have unique advantages over LIBs, such as high safety, good high and low temperature performance, etc. However, the radius of sodium ions is larger than that of lithium ions, making it difficult to achieve the level of lithium ion batteries in terms of energy density and volume density, which is mainly due to the electrode material. Therefore, it is crucial to find a suitable SIBs electrode material.

[0003] Transition metal sulfides have high theoretical capacity, multiple sodium ion storage mechanisms, strong thermodynamic stability, and low price, and are considered as potential anode materials for sodium ion batteries. Metal-S bonds have lower bond energy than metal-O bonds, thereby reducing the potential barrier during sodiumization / desodiation. However, the high expansion rate of conversion type transition metal sulfides makes them prone to pulverization during charging and discharging, and in addition, the low intrinsic electrical conductivity also limits the cycle capacity and rate performance. SUMMARY

[0004] 1. Problem to be solved

[0005] In view of the high expansion rate and poor stability of the existing sodium ion battery negative electrode material, the present application provides a conversion type nickel copper sulfide negative electrode material and a preparation method thereof.

[0006] 2. Technical solution

[0007] In order to solve the above problems, the technical scheme adopted by the present application is as follows:

[0008] In a first aspect, the present application provides a preparation method of a conversion type nickel copper sulfide negative electrode material, comprising the following steps:

[0009] S1. Preparation of electrolyte: dissolve nickel source, copper source, sulfur source and ammonium chloride in a solvent, stir and dissolve to obtain an electrolyte;

[0010] S2. Electrodeposition: using the electrolyte in the step S1, electrodeposition is carried out in a three-electrode system, and after the electrodeposition is completed, cleaning and drying are carried out to obtain an electrodeposition product;

[0011] S3. Annealing treatment: the electrodeposition product in the step S2 is subjected to annealing to obtain a conversion type nickel copper sulfide negative electrode material.

[0012] The advantages of the above technical solution are: first, the high-capacity nickel sulfide is combined with the good conductivity of copper sulfide, the capacity and conductivity are considered, and the specific capacity of the battery is improved due to the synergistic effect of multiple metals; the main purpose of introducing copper element is to introduce more sodium storage sites, improve the morphology of the multi-metal sulfide, i.e. the conversion type nickel copper sulfide negative electrode material, reduce the volume expansion during the cycle process, and improve the cycle stability;

[0013] Secondly, the conversion type nickel copper sulfide negative electrode material is synthesized by the method of constant current electrodeposition, which has simple and easy-to-operate preparation process, greatly reduces the preparation cost of electrode material, and is green and environmentally friendly in the preparation process;

[0014] Finally, the conversion type nickel copper sulfide negative electrode material is obtained after annealing treatment, and is used as a negative electrode of a sodium ion battery after being made into a sheet, which enhances the structural stability of the negative electrode of the sodium ion battery during the cycle process, and shows excellent electrochemical performance.

[0015] It should be noted that the electrodeposition product on the working electrode in the three-electrode system in step S2 can be removed for annealing treatment to obtain a conversion type nickel copper sulfide negative electrode material; or the working electrode and the electrodeposition product in step S2 can be simultaneously subjected to annealing treatment, and then the conversion type nickel copper sulfide negative electrode material is taken out.

[0016] Further, in step S2, the conditions for electrodeposition are: constant current density: 0.1-5 A·cm -2 ; electrodeposition time: 20-150 s.

[0017] The advantages of the above technical solution are: too low current density will result in a dense plated film, i.e. electrodeposition product, and too high current density will result in a too loose plated film, 0.1-5 A·cm -2 is a reasonable current density; too long electrodeposition time will result in a too thick plated film, and too short electrodeposition time will result in a too thin plated film, and 20-150 s is a reasonable electrodeposition time.

[0018] Further, in step S2, the cleaning is specifically: using deionized water for cleaning.

[0019] Further, in step S2, the conditions for drying include: drying temperature: 50-100℃; drying time: 1-5 h.

[0020] For example, a vacuum drying oven can be used for drying.

[0021] Further, in the step S2, the three-electrode system includes a working electrode, a counter electrode and a reference electrode.

[0022] The working electrode is a current collector,

[0023] The working electrode includes at least one of a copper foil, an aluminum foil, a nickel foam and a copper foam.

[0024] Further, the counter electrode includes at least one of a Pt sheet and a carbon rod.

[0025] Further, the reference electrode includes at least one of a saturated calomel electrode and a silver / silver chloride electrode.

[0026] Further, in the step S1, the preparation conditions of the electrolyte include a preparation temperature of 20-30°C. Preferably, the temperature is normal temperature of 25°C.

[0027] The advantages of the above technical solution are that the preparation method can be performed at normal temperature without the need for temperature control, and the conditions are mild and the operation is simple.

[0028] Further, in the step S1, the nickel source includes at least one of nickel chloride, nickel acetate, nickel sulfate and nickel nitrate.

[0029] Further, in the step S1, the copper source includes at least one of copper chloride, copper acetate, copper sulfate and copper nitrate.

[0030] Further, in the step S1, the sulfur source includes at least one of sodium sulfide, sodium thiosulfate, thioacetamide and thiourea.

[0031] Further, in the step S1, in the electrolyte, the concentrations of the nickel source, the copper source and the sulfur source are 0.1-0.3 mol / L, 0.01-0.2 mol / L and 0.1-0.6 mol / L, respectively.

[0032] The reason for using the above technical solution is that the nickel source, the copper source and the sulfur source are controlled within the above ranges, and the prepared hybrid nickel-copper sulfide is formed by accumulation of nanoparticles, has a loose and porous three-dimensional flower-like structure, and the particles are uniformly distributed, which is beneficial to increase the contact area of the negative electrode material with the electrolyte, provides more exposed active sites, shortens the sodium ion diffusion path, and improves the transmission efficiency of ions or electrons.

[0033] Further, in the step S1, in the electrolyte, the concentration of ammonium chloride is 0.1-0.3 mol / L.

[0034] Further, in step S1, the solvent includes at least one of deionized water, distilled water, reverse osmosis water, ultrapure water and double distilled water.

[0035] Further, in step S1, the stirring and dissolving can be performed by magnetic stirring.

[0036] Further, the step S1 is specifically as follows:

[0037] First, the ammonium chloride is added to the solvent and stirred until completely dissolved;

[0038] Then, the nickel source and the copper source are added and stirred until completely dissolved;

[0039] Then, the sulfur source is added and stirred until completely dissolved, to obtain the electrolyte.

[0040] Further, in step S3, the annealing conditions include: annealing temperature: 300-600℃; annealing time: 2-5h.

[0041] For example, the annealing process can be performed in an annealing tube furnace.

[0042] The reason for using the above technical solution is that controlling the temperature and time of annealing within the above range is beneficial to improving the electrical conductivity and thermal stability of the material.

[0043] Further, in step S3, the annealing conditions also include that the annealing is performed in an inert gas atmosphere or a vacuum condition.

[0044] The reason for using the above technical solution is that the inert gas atmosphere can protect the deposition product from oxidation or other chemical reactions during the annealing process; in addition, the vacuum environment can also avoid the reaction of the electrodeposited product with any gas molecules at high temperature.

[0045] Further, the inert gas includes at least one of nitrogen, argon and helium.

[0046] Further, the inert gas is nitrogen.

[0047] The reason for using the above technical solution is that nitrogen is the gas with the highest content in the atmosphere, so it is relatively easy to obtain, has low cost and good chemical stability.

[0048] In a second aspect, the present application also provides a conversion type nickel-copper sulfide negative electrode material prepared by the above preparation method.

[0049] The conversion type nickel-copper sulfide negative electrode material is a three-dimensional flower-like structure formed by accumulation of nanoparticles.

[0050] Further, the conversion-type nickel-copper sulfide negative electrode material is a loose porous three-dimensional flower-like structure formed by accumulation of nanoparticles; the nanoparticles are uniformly distributed, which means that within a certain spatial range, the arrangement of the nanoparticles presents a relatively balanced and consistent state, that is, the spacing, density or number distribution of the nanoparticles have no significant local deviation or aggregation phenomenon.

[0051] Further, the particle size of the nanoparticles is 50-500 nm.

[0052] In a third aspect, the application provides a sodium ion battery comprising a negative electrode, wherein the negative electrode comprises the conversion-type nickel-copper sulfide negative electrode material prepared by the preparation method or the conversion-type nickel-copper sulfide negative electrode material.

[0053] The reason for adopting the above technical solution is that the negative electrode of the sodium ion battery comprises the conversion-type nickel-copper sulfide negative electrode material, which has higher capacity and longer service life.

[0054] 3. Beneficial effects

[0055] Compared with the prior art, the application has the following beneficial effects: the application provides a method for preparing a conversion-type nickel-copper sulfide negative electrode material by electrodeposition, and the obtained negative electrode material not only has high capacity, but also has good kinetic performance, high stability and other advantages, meeting the requirements of sodium ion battery negative electrode design.

[0056] More specifically, the application has the following beneficial effects:

[0057] (1) The preparation method of the conversion-type nickel-copper sulfide negative electrode material provided by the application uses a simple constant-current electrodeposition method to form a conversion-type nickel-copper sulfide negative electrode material on a current collector substrate, which has the advantages of simple synthesis and mild conditions, meets the requirements of green development, and is conducive to industrialization application and popularization.

[0058] (2) The conversion-type nickel-copper sulfide negative electrode material provided by the application is formed by accumulation of nanoparticles and has a loose porous three-dimensional flower-like structure, and the nanoparticles are uniformly distributed. Such a structure increases the contact area of the negative electrode material with the electrolyte, provides more exposed active sites, shortens the diffusion path of sodium ions, and improves the transmission efficiency of ions or electrons.

[0059] (3) The conversion-type nickel-copper sulfide negative electrode material provided by the application effectively slows down the serious structural damage of the electrode material caused by volume change during the sodium ion insertion / extraction process, overcomes the disadvantages of high expansion rate and easy pulverization of the conversion-type transition metal sulfide, and improves the cycle stability of the electrode material.

[0060] (4) The sodium ion battery negative electrode material of the present application shows high capacity and excellent cycle stability, is a potential application material for high-capacity long-life sodium ion batteries, and has potential large-scale market application value. BRIEF DESCRIPTION OF DRAWINGS

[0061] Figure 1 Scanning electron microscope image of the conversion type nickel copper sulfide negative electrode material prepared for Example 1 of the present application;

[0062] Figure 2 Cycle performance graph of the conversion type nickel copper sulfide negative electrode material prepared for Example 1 of the present application. DETAILED DESCRIPTION

[0063] The present disclosure can be more easily understood by reference to the following description in conjunction with the examples included herein. It should be understood that the present disclosure is not limited to the particular products, methods, conditions or parameters described and / or shown herein, all of which can vary. Further, the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting, unless otherwise specified.

[0064] It should also be understood that certain features of the present disclosure, which are, for clarity, described in the context of separate embodiments, can also be provided in combination in a single embodiment. That is, each individual embodiment can be combined with any other embodiment or embodiments unless specifically noted otherwise. Conversely, various features of the present disclosure, which are, for brevity, described in the context of a single embodiment, can also be provided separately or in any sub-combination. Finally, while the various embodiments of the present disclosure can be described in the context of a series of steps of a method or a series of structures of a composition, it is to be understood that each step or each structure can be performed or implemented independently of the other steps or structures. To the extent that they can be mutually exclusive, they are not specifically noted.

[0065] In this disclosure, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a substance" is a reference to at least one of such a substance and equivalents thereof.

[0066] Generally, use of the term“about” indicates an approximation that can vary depending on the desired properties to be achieved by the disclosed subject matter and will be construed based on functionality in a context-dependent manner. Thus, one of ordinary skill in the art would be able to determine, on a case-by-case basis, what is an acceptable degree of deviation. In some instances, the number of significant digits used in expressing a particular value can be indicative of the degree to which the value is meant to be precise. In other instances, a range of values can be presented, and the degree of deviation within the range can be determined based on the gradual transition of values within the range. Further, all ranges disclosed in the present disclosure are inclusive of the endpoints and combinable, and the disclosure of a range includes each possible combination of the values within the range.

[0067] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the application belongs; the meaning and scope of the terms used herein should be clear, however, and no special definition is intended unless otherwise defined herein. The terminology used in the description herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0068] The following examples were carried out under ordinary conditions or under conditions recommended by the manufacturer unless otherwise specified. The reagents or instruments used were all commercially available unless otherwise specified.

[0069] The application will be further described with reference to the following examples. It will be appreciated that these examples are intended to be illustrative only and are not intended to limit the scope of the application. Unless otherwise indicated, the reagents, methods and apparatuses used in the examples are conventional in the art. The essential features of the application can be appreciated from the examples described below, which are a part of the application, but not all of the application. Therefore, they do not limit the application in any way, and any non-essential improvements and adjustments made by those skilled in the art based on the content of the application are within the scope of the application.

[0070] The application will be further described with reference to the following examples. It will be appreciated that these examples are intended to be illustrative only and are not intended to limit the scope of the application. Unless otherwise indicated, the reagents, methods and apparatuses used in the examples are conventional in the art. The essential features of the application can be appreciated from the examples described below, which are a part of the application, but not all of the application. Therefore, they do not limit the application in any way, and any non-essential improvements and adjustments made by those skilled in the art based on the content of the application are within the scope of the application.

[0071] Example 1

[0072] The present embodiment provides a preparation method of a conversion type nickel copper sulfide negative electrode material, specifically comprising the following steps:

[0073] (1) Dissolve 0.025 mol of NH4Cl in 100 mL of deionized water, and magnetically stir until completely dissolved.

[0074] (2) Add 0.02 mol of NiCl2 and 0.005 mol of CuCl2 to the solution obtained in step (1), and stir until completely dissolved to obtain a light green solution.

[0075] (3) Add 0.02 mol of thiourea to the solution obtained in step (2) and stir until completely dissolved to obtain the electrolyte for deposition.

[0076] In this embodiment, steps (1)-(3) are carried out at room temperature, and the stirring speed is 600 rpm / min.

[0077] (4) In a three-electrode system, a copper foil is used as the working electrode, a Pt sheet is used as the counter electrode, and an Ag / AgCl electrode is used as the reference electrode. The deposition is carried out at a constant current density of 1.5 A·cm -2 for 50 s. After the deposition is completed, the product is carefully rinsed with deionized water and dried in a vacuum drying oven at a temperature of 60°C for 4 h.

[0078] (5) The product is annealed at 500°C for 3 h in a tube furnace under the protection of an inert gas (nitrogen) atmosphere to obtain the conversion-type nickel-copper sulfide negative electrode material.

[0079] (6) The nickel-copper sulfide negative electrode material is scraped off from the current collector, and the nickel-copper sulfide negative electrode material powder, Super P (TIMCAL SUPER P LI), and PVDF (Arkema HSV-900) are thoroughly ground in a mortar at a mass ratio of 8:1:1 to prepare a slurry using NMP, which is coated on a copper foil (thickness of 8 μm) at a loading of 6 mg / cm 2 .

[0080] (7) The commercial sodium sheet (Jiaxing Changgao New Material Technology Co., Ltd. 15.6 x 0.4 mm) is used as the counter electrode, the glass fiber (GF / D) is used as the separator, and the electrolyte is 1M NaPF6 dissolved in a solvent of EC:DMC = 1:1 (volume ratio) to test the electrochemical performance of the material.

[0081] Figure 1 The scanning electron microscope image of the conversion-type nickel-copper sulfide negative electrode material synthesized in this embodiment is shown in FIG. 2. The conversion-type nickel-copper sulfide has a distinct morphological feature, which is a loose and porous three-dimensional flower-like structure formed by uniformly distributed nanoparticles with a particle diameter of about 50-500 nm.

[0082] Figure 2 The rate performance graph of the conversion-type nickel-copper sulfide negative electrode material synthesized in this embodiment is shown in FIG. 3. The discharge specific capacity is 415.53 mAh / g at a current density of 0.1 A / g, and the discharge specific capacity is 353.2 mAh / g at a current density of 5 A / g.

[0083] Example 2

[0084] This embodiment provides a preparation method of a conversion-type nickel-copper sulfide negative electrode material, which is basically the same as that of Example 1, except that:

[0085] In step (2), the amount of CuCl2 added was 0.002 mol.

[0086] The negative electrode material of this example had a discharge specific capacity of 388.64 mAh / g at a current density of 0.1 A / g.

[0087] Example 3

[0088] This example provides a preparation method of a conversion-type nickel copper sulfide negative electrode material, which is basically the same as that of Example 1, except that:

[0089] In step (2), the amount of CuCl2 added was 0.01 mol.

[0090] The negative electrode material of this example had a discharge specific capacity of 390.66 mAh / g at a current density of 0.1 A / g.

[0091] Example 4

[0092] This example provides a preparation method of a conversion-type nickel copper sulfide negative electrode material, which is basically the same as that of Example 1, except that:

[0093] In step (2), the amount of CuCl2 added was 0.015 mol.

[0094] The negative electrode material of this example had a discharge specific capacity of 368.53 mAh / g at a current density of 0.1 A / g.

[0095] Comparative Example 1

[0096] This comparative example provides a preparation method of a conversion-type nickel copper sulfide negative electrode material, which is basically the same as that of Example 1, except that:

[0097] In step (2), no CuCl2 was added, and only 0.02 mol of NiCl2 was added.

[0098] The negative electrode material of this comparative example had a discharge specific capacity of 303.99 mAh / g at a current density of 0.1 A / g.

[0099] Since no copper element was added in this comparative example, there were fewer exposed sodium storage sites, the ion diffusion distance was longer, and the sodiumization / desodiumization potential barrier of the single metal sulfide was higher, so the capacity was lower.

[0100] Comparative Example 2

[0101] This comparative example provides a preparation method of a conversion-type nickel copper sulfide negative electrode material, which is basically the same as that of Example 1, except that:

[0102] In step (2), no NiCl2 was added, and only 0.005 mol of CuCl2 was added.

[0103] The negative electrode material of the present comparative example has a discharge specific capacity of 118.92 mAh / g at a current density of 0.1 A / g.

[0104] The capacity of the present comparative example is relatively low due to the relatively low intrinsic sodium storage capacity of the negative electrode material because of the absence of nickel element.

Claims

1. A method for producing a transformed nickel copper sulfide negative material, characterized by, The method comprises the following steps: S1. Preparing an electrolyte: dissolving a nickel source, a copper source, a sulfur source and ammonium chloride in a solvent, stirring and dissolving to obtain an electrolyte; in the electrolyte, the concentrations of the nickel source, the copper source and the sulfur source are 0.1-0.3 mol / L, 0.01-0.2 mol / L and 0.1-0.6 mol / L respectively; the nickel source is nickel chloride; the copper source is copper chloride; and the sulfur source is thiourea; S2. Electrodeposition: using the electrolyte in step S1, electrodeposition is carried out in a three-electrode system, and after the electrodeposition is completed, cleaning and drying are carried out to obtain an electrodeposition product; the conditions of the electrodeposition are: constant current density: 0.1-5 A·cm -2 ; electrodeposition time: 20-150 s; S3. Annealing treatment: the electrodeposition product in step S2 is subjected to annealing to obtain a transformed nickel-copper sulfide negative electrode material; The conversion-type nickel-copper sulfide negative electrode material is a three-dimensional flower-like structure formed by accumulation of nanoparticles.

2. The method according to claim 1, characterized in that: In step S2, the three-electrode system comprises a working electrode, a counter electrode and a reference electrode; The working electrode is a current collector; The working electrode comprises at least one of a copper foil, an aluminum foil, a nickel foam and a copper foam; The counter electrode comprises at least one of a Pt sheet and a carbon rod; The reference electrode comprises at least one of a saturated calomel electrode and a silver / silver chloride electrode.

3. The method according to claim 2, characterized in that: In step S3, the annealing conditions comprise: The annealing temperature is 300-600 ℃; The annealing time is 2-5 h.

4. The method according to claim 3, characterized in that: In step S3, the annealing conditions further comprise that the annealing is performed under an inert gas atmosphere or in a vacuum.

5. A transformed nickel copper sulfide anode material, characterized by: The conversion-type nickel-copper sulfide negative electrode material is prepared by the method according to any one of claims 1-4.

6. The conversion-type nickel copper sulfide negative material according to claim 5, characterized in that: The particle size of the nanoparticles is 50-500 nm.

7. A sodium ion battery comprising a negative electrode, characterized in that the negative electrode comprises the conversion-type nickel-copper sulfide negative electrode material according to any one of claims 5-6.

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