A high-stability MoS2 negative electrode material, its preparation method and application

Abstract

The present application discloses a high-stability MoS2 anode material, its preparation method and application, relating to the technical field of energy storage of lithium-ion batteries. The high-stability MoS2 anode material is a thermodynamically stable pure 2H phase, stacked by nano-fragments with a size of 20-150 nm, having abundant edge lithium storage sites. At the same time, some silicon atoms of the SiO2 template are incorporated and stabilize the MoS2 lattice structure during the high-temperature treatment. Thus, when this material is applied to the anode of a lithium-ion battery, it exhibits excellent specific capacity and rate performance, and significantly improves the long-term cycle stability.

Description

Technical Field

[0001] This application relates to the technical field of lithium-ion battery energy storage, and particularly relates to a high-stability MoS2 anode material, its preparation method and application. Background Art

[0002] With the popularization and use of large-scale energy storage devices and electric vehicles, the relatively low theoretical specific capacity (372 mAh / g) of traditional graphite anodes can no longer meet the requirements for high-energy lithium-ion batteries. As an intercalation-type material, in the electrochemical reaction, graphite anodes store charge by forming Li x C6 intercalation compounds through the intercalation of lithium ions into the graphite layers. Its lithium intercalation kinetics are relatively slow, which is not conducive to the fast charging application of batteries.

[0003] Molybdenum disulfide (MoS2), as a typical layered transition metal sulfide, exists in the form of molybdenite in nature and has rich reserves. The theoretical capacity of MoS2 is as high as 670 mAh / g, and it is considered to be one of the most potential anode materials for lithium-ion batteries. The MoS2 layers are connected by weak van der Waals forces, and the layer spacing is 0.62 nm, which is conducive to the rapid transport of lithium ions and has great potential in the field of fast charging of lithium-ion batteries. MoS2 stores lithium through the "intercalation-conversion" mechanism. In the first-cycle electrochemical reaction, lithium ions first insert into the MoS2 layers to form the lithium intercalation compound Li x MoS2. However, with the increase in the amount of lithium ions intercalated, the layered structure of MoS2 rearranges, easily forming large bulk-phase particles, making it unable to fully react during subsequent lithiation / delithiation processes. This irreversible structural change causes the rapid decay of the lithium storage capacity, making the material exhibit poor cycle stability and rate performance, which greatly hinders the commercialization process of MoS2.

[0004] Compared with bulk materials, the nanosizing of electrode materials can greatly shorten the diffusion paths of lithium ions and electrons, significantly improve their transport kinetics, and thus enhance the rate performance. As the particle size decreases, it also helps to release the stress generated during the lithium intercalation / deintercalation process, thereby greatly improving the cycle performance of the material. In addition, introducing heteroatoms into the MoS2 material is beneficial to adjusting its electronic structure and alleviating the structural changes during charge and discharge. For example, introducing metal atoms such as Cr, V, and Co into the MoS2 material can significantly change the electronic density of states of monolayer MoS2, improve its conductivity, and thus promote charge transfer. Introducing Si atoms into MoS2 can reduce the diffusion energy barrier of lithium ions and effectively stabilize the lattice structure of the material during the reaction, thereby improving the rate and cycle performance of the material. Summary of the Invention

[0005] To solve the above-mentioned technical problems existing in the prior art, the present application provides a high-stability MoS2 anode material, its preparation method and application, so as to overcome the technical problem that the electrochemical performance of the MoS2 anode material in the prior art rapidly decays due to poor structural stability during the lithium storage process.

[0006] To achieve the above object, the technical solution of the embodiment of the present application is as follows:

[0007] The first aspect of the present application provides a high-stability MoS2 anode material, which crystallizes into a thermodynamically stable pure 2H phase, is stacked by nano-fragments with a size of 20-150 nm, has abundant edge sites, and at the same time, a small amount of silicon atoms derived from the SiO2 template are incorporated to stabilize the MoS2 lattice structure.

[0008] The second aspect of the present application provides a preparation method of the high-stability MoS2 anode material described in the first aspect, and the preparation method includes:

[0009] Disperse a surfactant containing cetyltrimethylammonium cation CTA + and triethanolamine in water, add a tetraethyl orthosilicate / cyclohexane mixed solution, carry out a stirring reaction and a purification treatment, and collect the dendritic mesoporous SiO2 nanospheres surface-modified with CTA + ;

[0010] Disperse the dendritic mesoporous SiO2 nanospheres surface-modified with CTA + in an aqueous molybdate solution, carry out vacuum filtration and drying to obtain a mesoporous SiO2@CTA + @MoO x composite material;

[0011] Carry out a confined sulfidation reaction on the mesoporous SiO2@CTA + @MoO x composite material and thiourea in an inert gas atmosphere to obtain a mesoporous SiO2@MoS2 composite material;

[0012] Disperse the mesoporous SiO2@MoS2 composite material in an aqueous sodium hydroxide solution for etching and purification treatment, and then the high-stability MoS2 anode material can be obtained.

[0013] Preferably in combination with the second aspect, the surfactant containing CTA + is one or more of cetyltrimethylammonium bromide and cetyltrimethylammonium chloride;

[0014] And / or, the addition amount of the surfactant containing CTA + is 4-6 g;

[0015] And / or, the addition amount of the triethanolamine is 0.5 to 1.0 mL, and the concentration is 0.35 g / mL.

[0016] Combined with the second aspect, preferably, the addition amount of the tetraethyl orthosilicate is 3 to 5 mL;

[0017] And / or, the addition amount of the cyclohexane is 15 to 25 mL;

[0018] And / or, the stirring reaction time is 12 to 20 h.

[0019] Combined with the second aspect, preferably, the collection of the surface-modified CTA + of the dendritic mesoporous SiO2 nanospheres includes: using absolute ethanol to perform three centrifugal separations on the intermediate product to retain the CTA on the surface of the mesoporous SiO2 pores + .

[0020] Combined with the second aspect, preferably, the molybdate is one or more of ammonium molybdate and sodium molybdate;

[0021] And / or, the concentration of the molybdate aqueous solution is 1.0 mol / L;

[0022] And / or, the mass ratio of the mesoporous SiO2 nanospheres to the molybdate is 1:8 to 25.

[0023] Combined with the second aspect, preferably, the mass ratio of the mesoporous SiO2@CTA + @MoO x composite material to the thiourea is 1:1 to 3;

[0024] And / or, the sulfidation reaction temperature is 500 to 800 °C, the heating rate is 5 to 10 °C / min, and the sulfidation time is 2 to 5 h.

[0025] And / or, the inert gas is one or more of nitrogen and argon, and the flow rate of the introduced gas is 20 to 60 mL / min.

[0026] Combined with the second aspect, preferably, the concentration of the sodium hydroxide aqueous solution is 2 to 4 mol / L, and the reaction time is 5 to 8 h.

[0027] The third aspect of the present application provides a high-stability MoS2 anode material described in the first aspect or a high-stability MoS2 anode material prepared by any method described in the second aspect for use in a lithium-ion battery.

[0028] Compared with the prior art, the advantages or beneficial effects of the embodiments of the present application at least include:

[0029] The high-stability MoS2 anode material provided by the embodiments of the present application, on the one hand, is stacked by numerous nanosheets with sizes of 20-150 nm, which can form abundant edge sites. These edge sites can be used for lithium storage, so that it can exhibit extremely high specific capacity and rate performance; on the other hand, some silicon atoms of the SiO2 template migrate, incorporate into and stabilize the MoS2 lattice structure, significantly improving the problem that the current MoS2 anode material has poor structural stability during charge and discharge, resulting in rapid attenuation of its electrochemical performance.

[0030] The SiO2 template used in the preparation method of the embodiments of the present application is a nanosphere with dendritic mesopores, the sizes of its particles and mesopores can be adjusted, and its surface is uniformly modified with CTA + . Based on the + electrostatic interaction and coordination interaction between CTA x and molybdate anions, with the assistance of vacuum filtration, the MoO + precursor is confined and loaded on the mesoporous surface of SiO2, and then high-temperature sulfidation is carried out and the SiO2 template is etched away to obtain high-stability 2H-phase MoS2. Due to the confinement effect of the mesoporous SiO2 template and the guiding effect of CTA BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is the X-ray diffraction pattern of the high-stability MoS2 anode materials 1-3 prepared in Examples 1-3;

[0032] Figure 2 is the X-ray diffraction pattern of the MoS2 anode material prepared in Comparative Example 1;

[0033] Figure 3 is the scanning electron microscope image of the high-stability MoS2 anode material 2 prepared in Example 2;

[0034] Figure 4 is the transmission electron microscope image of the high-stability MoS2 anode material 2 prepared in Example 2;

[0035] Figure 5 is the scanning electron microscope image of the anode material without etching the SiO2 hard template in Example 2;

[0036] Figure 6 is the elemental surface distribution result map of the high-stability MoS2 anode material prepared in Example 2;

[0037] Figure 7The first, second, third, and fifth cycle galvanostatic charge-discharge performance curves of the highly stable MoS2 anode materials 1-3 prepared in Examples 1-3;

[0038] Figure 8 The rate performance diagrams of the highly stable MoS2 anode materials 1-3 prepared in Examples 1-3;

[0039] Figure 9 The cycle performance diagram of the highly stable MoS2 anode material 1 prepared in Example 1 at a current density of 0.1 A / g;

[0040] Figure 10 The cycle performance diagram of the highly stable MoS2 anode material 1 prepared in Example 1 at a current density of 1.0 A / g;

[0041] Figure 11 The cycle performance diagram of the MoS2 anode material prepared in Comparative Example 1 at a current density of 1.0 A / g. Detailed implementation manners

[0042] In order to make the objectives, technical solutions, and advantages of this application clearer, the following will further describe this application in detail in conjunction with the accompanying drawings. The described embodiments should not be regarded as limitations of this application. All other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of this application.

[0043] In the following description, reference is made to "some embodiments", which describe a subset of all possible embodiments. However, it can be understood that "some embodiments" can be the same subset or different subsets of all possible embodiments, and can be combined with each other without conflict. Unless otherwise defined, all technical and scientific terms used in the embodiments of this application have the same meaning as commonly understood by those skilled in the technical field to which the embodiments of this application belong. The terms used in the embodiments of this application are only for the purpose of describing the embodiments of this application and are not intended to limit this application.

[0044] In the following description of this embodiment, the terms "include", "comprise", "have", and "contain" are all open-ended terms, that is, they are intended to include but not limited to.

[0045] It should be noted that all raw materials / reagents in the embodiments of this application can be purchased on the market or prepared by conventional methods well-known to those skilled in the art; the term " / or" in the embodiments of this application is only used to describe the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B means three situations of A existing alone, B existing alone, and A and B existing simultaneously. Among them, A and B can be singular or plural, and the character " / " generally represents an "or" relationship between the front and back associated objects.

[0046] In the following description of this embodiment, the term "at least one" means one or more, and "a plurality" means two or more. "At least one of the following" or its similar expressions refer to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can both represent: a, b, c, a - b (i.e., a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively.

[0047] Those skilled in the art should understand that in the following description of the embodiments of this application, the sequence numbers do not imply the order of execution, and some or all steps can be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of this application.

[0048] The terms used in the embodiments of this application are only for the purpose of describing specific embodiments, and are not intended to limit this application. The singular forms "a" and "the" used in the embodiments of this application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0049] Those skilled in the art should understand that the numerical ranges in the embodiments of this application should be understood as specifically disclosing each intermediate value between the upper and lower limits of the range. Each intermediate value between any stated value and the intermediate values within the stated range, as well as each smaller range between any other stated value or the intermediate values within the stated range, is also included in this application. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0050] Unless otherwise specified, the technical / scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which this application pertains. Although this application only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the embodiments or test examples of this application. All documents mentioned in this specification are generally incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this application shall prevail.

[0051] It should be noted that all raw materials and / or reagents in the embodiments of this application are purchased on the market or prepared according to the conventional methods well-known to those skilled in the art.

[0052] In a first aspect, an embodiment of the present application provides a highly stable MoS2 negative electrode material, which crystallizes into a thermodynamically stable pure 2H phase and is stacked by nano-fragments with a size of 20-150 nm. It has abundant edge sites, and at the same time, a small amount of silicon atoms derived from the SiO2 template are incorporated to stabilize the MoS2 lattice structure.

[0053] The highly stable MoS2 negative electrode material provided by the embodiment of the present application, on the one hand, is stacked by numerous nano-fragments with a size of 20-150 nm, which can form abundant edge sites. These edge sites can be used for lithium storage, so that it can exhibit extremely high specific capacity and rate performance; on the other hand, some silicon atoms of the SiO2 template migrate, incorporate into and stabilize the MoS2 lattice structure, significantly improving the problem that the current MoS2 negative electrode material has poor structural stability during charge and discharge, resulting in rapid decay of its electrochemical performance.

[0054] In a second aspect, an embodiment of the present application provides a preparation method of the highly stable MoS2 negative electrode material described in the first aspect. The preparation method includes:

[0055] Disperse a surfactant containing cetyltrimethylammonium cation CTA + and triethanolamine in water, add a tetraethyl orthosilicate / cyclohexane mixed solution, carry out a stirring reaction and purification treatment, and collect dendritic mesoporous SiO2 nanospheres surface-modified with CTA + ;

[0056] Disperse the dendritic mesoporous SiO2 nanospheres surface-modified with CTA + in an aqueous molybdate solution, carry out vacuum filtration and drying to obtain a mesoporous SiO2@CTA + @MoO x composite material;

[0057] Carry out a confined sulfidation reaction on the mesoporous SiO2@CTA + @MoO x composite material and thiourea in an inert gas atmosphere to obtain a mesoporous SiO2@MoS2 composite material;

[0058] Disperse the mesoporous SiO2@MoS2 composite material in an aqueous sodium hydroxide solution for etching and purification treatment, and then the highly stable MoS2 negative electrode material is obtained.

[0059] The SiO2 template used in the embodiment of the present application is a nanosphere with dendritic mesopores. The sizes of the particles and mesopores can be adjusted, and its surface is uniformly modified with CTA + . Based on CTA +The electrostatic interaction and coordination interaction between the molybdate anions, assisted by vacuum filtration, confine and load MoO on the mesoporous surface of SiO2. x Precursor, and then high-temperature vulcanization is carried out to etch away the SiO2 template to obtain highly stable 2H-phase MoS2. Due to the confinement effect of the mesoporous SiO2 template and the + directing effect of CTA, the MoS2 material is "divided" into numerous nanosheets with sizes of 20 - 150 nm, forming abundant edge sites for lithium storage. During the high-temperature vulcanization process, some silicon atoms of the SiO2 template migrate, incorporate into and stabilize the MoS2 lattice structure. Therefore, when the obtained MoS2 material is used as the anode of a lithium-ion battery, it exhibits extremely high specific capacity and rate performance, significantly improving the problem that the current MoS2 anode material has poor structural stability during charge and discharge, resulting in rapid decay of its electrochemical performance.

[0060] In specific embodiments, the surfactant containing quaternary ammonium cations in the embodiments of the present application is preferably one of cetyltrimethylammonium bromide and cetyltrimethylammonium chloride.

[0061] On the one hand, these quaternary ammonium cation surfactants act as soft template agents during the synthesis of SiO2, thus forming uniform dendritic mesoporous channels in the SiO2 nanospheres. On the other hand, these quaternary ammonium cation surfactants bind to the pore surface of the mesoporous SiO2 template and can produce electrostatic interaction and coordination interaction with molybdate anions. With the assistance of vacuum filtration, it is beneficial to confine and load the MoO x precursor on the mesoporous surface of SiO2.

[0062] In specific embodiments, the addition amount of the surfactant containing quaternary ammonium cations in the embodiments of the present application is preferably 4 - 6 g.

[0063] It should be noted that these quaternary ammonium cation surfactants act as soft template agents in the SiO2 synthesis reaction, and their addition amount directly affects the mesoporous structure of SiO2, while the mesoporous structure of SiO2 directly affects the loading state of the MoO x precursor on the pore surface. In order to enable the final MoS2 material to be effectively "divided" into numerous nanosheets by the mesoporous SiO2 to form abundant edge sites available for lithium storage, the mesoporous structure of SiO2 needs to be controlled within a suitable range.

[0064] Among them, when the addition amount of SiO2 is too small, the formed mesoporous channels will be relatively sparse and shallow, and the amount of MoO x precursor that can be loaded is too small; when the addition amount of SiO2 is too large, the mesoporous structure of SiO2 will be too dense and deep, which is not conducive to the MoO x precursor entering the pores.

[0065] In specific embodiments, the addition amount of triethanolamine in the embodiments of the present application is preferably 0.5 - 1.0 mL, and the concentration is preferably 0.35 g / mL.

[0066] It should be noted that triethanolamine in the embodiments of the present application acts as a catalyst in the SiO2 synthesis reaction, and can regulate the hydrolysis of tetraethyl orthosilicate and the nucleation rate of nanoparticles, thereby regulating the particle size and uniformity of SiO2. Therefore, the addition amount of triethanolamine is jointly determined by the solution volume and concentration.

[0067] Among them, when the addition amount of triethanolamine is too small, the reaction rate is too slow, and the particle size of the generated SiO2 is too small; when the addition amount of triethanolamine is too large, it is not conducive to regulating the reaction rate, resulting in the rapid growth of SiO2 nanoparticles, and finally the particle size is too large and the uniformity is poor.

[0068] In specific embodiments, the addition amount of tetraethyl orthosilicate in the embodiments of the present application is preferably 3 - 5 mL.

[0069] Among them, tetraethyl orthosilicate is hydrolyzed to obtain the target product SiO2. When the addition amount of tetraethyl orthosilicate is too small, the amount of generated SiO2 is too small and the particle size is too small; when the addition amount of tetraethyl orthosilicate is too large, the amount of generated SiO2 is too large and the particle size is too large, and at the same time, it also has a greater impact on the pore structure.

[0070] It should be noted that the particle size and mesoporous structure of SiO2 in the embodiments of the present application also need to be controlled within a suitable range to facilitate the subsequent loading of the MoO x precursor. The embodiments of the present application do not specifically limit the particle size and mesoporous structure of SiO2.

[0071] In specific embodiments, the addition amount of cyclohexane in the embodiments of the present application is preferably 15 - 25 mL.

[0072] Among them, cyclohexane is used as the solvent of tetraethyl orthosilicate. When the addition amount of cyclohexane is too high, the concentration of tetraethyl orthosilicate is too low; when the addition amount of cyclohexane is too low, the concentration of tetraethyl orthosilicate is too high. The concentration of tetraethyl orthosilicate directly affects the particle size and mesoporous structure of the target SiO2.

[0073] In specific embodiments, the molybdate in the embodiments of the present application is preferably one of ammonium molybdate and sodium molybdate.

[0074] In specific embodiments, the concentration of the molybdate aqueous solution in the embodiments of the present application is preferably 1.0 mol / L.

[0075] Among them, when the concentration of the molybdate aqueous solution is too small, the molybdate anions and CTA on the surface of the mesoporous SiO2 pore channels +The combination rate is too slow; when the concentration of the molybdate aqueous solution is too high, the combination rate of the two is too fast, and MoO x Nucleates rapidly in the mesoporous channels, is prone to stacking, and numerous nano-fragments with rich edges cannot be formed.

[0076] In a specific embodiment, the mass ratio of the mesoporous SiO2 nanospheres and molybdate in the embodiments of the present application is preferably 1:8 to 25.

[0077] Among them, when the mass ratio of the mesoporous SiO2 nanospheres and molybdate is greater than 1:8, the loading amount of the corresponding MoO x in the mesoporous SiO2 channels is too small; when the mass ratio of the mesoporous SiO2 nanospheres and molybdate is less than 1:25, MoO x will undergo severe stacking in the mesoporous SiO2 channels in the mesoporous channels, and numerous nano-fragments with rich edges cannot be formed.

[0078] In a specific embodiment, the mass ratio of the mesoporous SiO2@CTA + @MoO x composite material and thiourea is preferably 1:1 to 3.

[0079] It should be noted that thiourea in the embodiments of the present application is used as a sulfur source to perform confined sulfidation on the MoO x precursor.

[0080] Among them, when the mass ratio of the mesoporous SiO2@CTA + @MoO x composite material and thiourea is greater than 1:1, the amount of the sulfur source is too small to completely convert MoO x into MoS2; when the mass ratio of the mesoporous SiO2@CTA + @MoO x composite material and thiourea is less than 1:3, the amount of the sulfur source is too large, and carbon components will be deposited on the surface of MoS2 and sulfur vacancies will be formed, affecting the electrochemical performance of MoS2.

[0081] In a specific embodiment, the temperature of the confined sulfidation reaction in the embodiments of the present application is preferably 500 to 800 °C, the heating rate is preferably 5 to 10 °C / min, and the sulfidation time is preferably 2 to 5 h.

[0082] It should be noted that the high-temperature reaction process of the mesoporous SiO2@CTA + @MoO x composite material and thiourea is as follows: thiourea decomposes at high temperature to generate H2S, and H2S reacts with MoO x to generate MoS2. Among them, when the sulfidation reaction temperature is less than 500 °C, MoO xThe sulfidation reaction is insufficient or even does not occur, and pure-phase MoS2 cannot be obtained; when the sulfidation reaction temperature is higher than 800 °C, the atomic migration rate is too fast, sulfur vacancies are easily formed in MoS2, and at the same time, the incorporation amount of Si atoms increases significantly, resulting in obvious increase in stress in the material.

[0083] In a specific embodiment, the inert gas in the embodiment of the present application is preferably one of nitrogen and argon; the flow rate of the introduced gas is preferably 20-60 mL / min.

[0084] In a specific embodiment, the concentration of the sodium hydroxide aqueous solution in the embodiment of the present application is preferably 2-4 mol / L, and the reaction time is preferably 5-8 h.

[0085] It should be noted that the function of the sodium hydroxide aqueous solution in the embodiment of the present application is to etch and remove silicon dioxide in the SiO2@MoS2 composite material to obtain a high-stability MoS2 negative electrode material.

[0086] Among them, when the concentration of the sodium hydroxide aqueous solution is too small, the reaction is insufficient, and SiO2 will remain in the material; when the concentration of the sodium hydroxide aqueous solution is too high, sodium hydroxide directly reacts with molybdenum disulfide to generate sodium molybdate impurities.

[0087] In a third aspect, the embodiment of the present application provides a high-stability MoS2 negative electrode material described in the first aspect or a high-stability MoS2 negative electrode material prepared by any method described in the second aspect is applied to a lithium-ion battery.

[0088] The technical method of the present application will be further elaborated below in conjunction with specific embodiments.

[0089] Example 1

[0090] This Example 1 provides a preparation method for a high-stability MoS2 negative electrode material 1 and a lithium-ion battery 1, and the specific steps are as follows:

[0091] (1) Preparation of the high-stability MoS2 negative electrode material 1:

[0092] 6 g of cetyltrimethylammonium bromide (CTAB) and 0.75 mL of triethanolamine (TEA) aqueous solution are mixed in 60 mL of deionized water. The mixed solution is heated to 60 °C, stirred for 0.5 h, then tetraethyl orthosilicate (TEOS) / cyclohexane solution is added and stirred for another 12 h. Ethanol is added for centrifugal separation, and dendritic mesoporous SiO2 nanospheres are obtained after drying.

[0093] The 0.3 g of dendritic mesoporous SiO2 nanospheres obtained above and 21 mL of an aqueous solution of ammonium molybdate tetrahydrate with a concentration of 1.0 mol / L were ultrasonically dispersed uniformly. The uniformly dispersed mixed solution was poured into a Buchner funnel, and after vacuum filtration, the obtained product was placed in an oven for drying to obtain mesoporous SiO2@CTA + @MoO x composite material;

[0094] The 0.5 g of mesoporous SiO2@CTA + @MoO x composite material and 1.0 g of thiourea were respectively placed in two adjacent corundum boats. The corundum boats were respectively placed in the downstream and upstream of the gas flow in a tube furnace. After continuously introducing an inert gas, the tube furnace was heated to 700 °C, and after reacting for 2 h, it was cooled to room temperature to obtain a mesoporous SiO2@MoS2 nanocomposite material;

[0095] The obtained mesoporous SiO2@MoS2 nanocomposite material was placed in a sodium hydroxide solution with a concentration of 3 mol / L and stirred for 6 h. After centrifugation and drying, a high-stability MoS2 negative electrode material 1 was obtained.

[0096] (2) Preparation of lithium-ion battery 1:

[0097] The high-stability MoS2 negative electrode material 1 obtained in Example 1 above, polyvinylidene fluoride (PVDF), and conductive carbon black (Super P) were thoroughly ground according to a mass ratio of 7:2:1. After adding N-methylpyrrolidone (NMP) and continuing to grind and mix evenly, a black paste-like slurry was obtained. The black slurry was uniformly coated on a copper foil, and after drying, it was cut into an electrode sheet with a diameter of 10 mm as the negative electrode of the lithium-ion battery. A lithium sheet was used as the counter electrode, a polypropylene (PP) film was used as the separator, and a mixed solution with 1 M lithium hexafluorophosphate (LiPF6) as the solute and a volume ratio of 1:1:1 of dimethyl carbonate (DMC):ethylene carbonate (EC):ethyl methyl carbonate (EMC) as the solvent was used as the electrolyte. A CR2032 type button battery was assembled in a glove box, and its electrochemical performance was tested after standing for 8 h.

[0098] Example 2

[0099] This Example 2 provides a preparation method of a high-stability MoS2 negative electrode material 2, and the specific steps are as follows:

[0100] (1) Preparation of high-stability MoS2 negative electrode material 2:

[0101] Mix 6 g of CTAB and 0.75 mL of aqueous TEA solution in 60 mL of deionized water. Heat the mixed solution to 60 °C, stir for 0.5 h, then add tetraethyl orthosilicate (TEOS) / cyclohexane solution and continue stirring for 12 h. Add absolute ethanol and perform centrifugal separation. After drying, dendritic mesoporous SiO2 nanospheres are obtained;

[0102] Ultrasonically disperse 0.3 g of the obtained dendritic mesoporous SiO2 nanospheres and 28 mL of an aqueous ammonium molybdate tetrahydrate solution with a concentration of 1.0 mol / L evenly. Pour the evenly dispersed mixed solution into a Buchner funnel, perform vacuum filtration, and then place the obtained product in a drying oven for drying to obtain mesoporous SiO2@CTA + @MoO x composite material;

[0103] Place 0.5 g of the obtained mesoporous SiO2@CTA + @MoO x composite material and 1.0 g of thiourea in two adjacent corundum boats respectively. Place the corundum boats in the downstream and upstream of the gas flow in a tube furnace. After continuously introducing an inert gas, heat the tube furnace to 700 °C, react for 2 h, and then cool to room temperature to obtain mesoporous SiO2@MoS2 nanocomposite material;

[0104] Place the obtained mesoporous SiO2@MoS2 nanocomposite material in a sodium hydroxide solution with a concentration of 3 mol / L and stir for 6 h. After centrifugal drying, high-stability MoS2 negative electrode material 2 is obtained.

[0105] (2) Preparation of lithium-ion battery 2:

[0106] Thoroughly grind the high-stability MoS2 negative electrode material 2, PVDF, and Super P obtained in Example 2 of this embodiment according to a mass ratio of 7:2:1. Add NMP and continue grinding to mix evenly to obtain a black paste-like slurry. Coat the black slurry evenly on a copper foil, dry it, and cut it into an electrode sheet with a diameter of 10 mm as the negative electrode of the lithium-ion battery. Use a lithium sheet as the reference electrode, a PP film as the separator, and a mixed solution with 1M LiPF6 as the solute and a volume ratio of 1:1:1 of DMC:EC:EMC as the solvent as the electrolyte. Assemble a CR2032 type button battery in a glove box and test its electrochemical performance after standing for 8 h.

[0107] Example 3

[0108] This Example 3 provides a preparation method for a high-stability molybdenum sulfide MoS2 negative electrode material 3 and a lithium-ion battery 3, and the specific steps are as follows:

[0109] (1) Preparation of high-stability MoS2 negative electrode material 3:

[0110] Mix 6 g of CTAB and 0.75 mL of aqueous TEA solution in 60 mL of deionized water. Heat the mixed solution to 60 °C, stir for 0.5 h, then add the TEOS / cyclohexane solution and continue stirring for 12 h. Add anhydrous ethanol for centrifugal separation, and after drying, dendritic mesoporous SiO2 nanospheres are obtained;

[0111] Ultrasonically disperse 0.3 g of the obtained dendritic mesoporous SiO2 nanospheres and 42 mL of an aqueous ammonium molybdate tetrahydrate solution with a concentration of 1.0 mol / L evenly. Pour the evenly dispersed mixed solution into a Buchner funnel, perform vacuum filtration, and then place the obtained product in an oven for drying to obtain mesoporous SiO2@CTA + @MoO x composite material;

[0112] Place 0.5 g of the obtained mesoporous SiO2@CTA + @MoO x composite material and 1.0 g of thiourea in two adjacent corundum boats respectively. Place the corundum boats in the downstream and upstream of the gas flow in a tubular furnace respectively. After continuously introducing an inert gas, heat the tubular furnace to 700 °C, react for 2 h, and then cool to room temperature to obtain mesoporous SiO2@MoS2 nanocomposite material;

[0113] Place the obtained mesoporous SiO2@MoS2 nanocomposite material in a sodium hydroxide solution with a concentration of 3 mol / L and stir for 6 h. After centrifugal drying, a highly stable MoS2 negative electrode material 3 is obtained.

[0114] (2) Prepare lithium-ion battery 3:

[0115] Thoroughly grind the highly stable MoS2 negative electrode material 3, PVDF, and Super P obtained in Example 3 above in a mass ratio of 7:2:1. Add NMP and continue grinding to mix evenly to obtain a black paste-like slurry. Uniformly coat the black slurry on a copper foil, and after drying, cut it into an electrode sheet with a diameter of 10 mm as the negative electrode of the lithium-ion battery. Use a lithium sheet as the counter electrode, a PP film as the separator, and a mixed solution with 1 M LiPF6 as the solute and a volume ratio of 1:1:1 of DMC:EC:EMC as the solvent as the electrolyte. Assemble a CR2032 type button battery in a glove box, and test its electrochemical performance after standing for 8 h.

[0116] Comparative Example 1

[0117] In this Comparative Example 1, directly place 0.5 g of ammonium molybdate and 3.0 g of thiourea in two adjacent corundum boats respectively. Place the corundum boats in the downstream and upstream of the gas flow in a tubular furnace respectively. After continuously introducing an inert gas, heat the tubular furnace to 700 °C, react for 2 h, and then cool to room temperature to obtain MoS2 negative electrode material.

[0118] To verify the relevant properties of the highly stable MoS2 anode materials 1-3 prepared in the above Examples 1-3, performance tests were carried out on the highly stable MoS2 anode materials 1-3 prepared in Examples 1-3, and the test results are as Figures 1 to 6 shown. Figure 1 It is the X-ray diffraction pattern of the highly stable MoS2 anode materials 1-3 prepared in Examples 1-3. Figure 2 It is the X-ray diffraction pattern of the MoS2 anode material prepared in Comparative Example 1. Figure 3 It is the scanning electron microscope image of the highly stable MoS2 anode material 2 prepared in Example 2. Figure 4 It is the transmission electron microscope image of the highly stable MoS2 anode material 2 prepared in Example 2. Figure 5 It is the scanning electron microscope image of the anode material when the SiO2 hard template is not etched. Figure 6 It is the elemental surface distribution result map of the highly stable MoS2 anode material prepared in Example 2. Figure 7 It is the galvanostatic charge-discharge performance curves of the first, second, third, and fifth cycles of the highly stable MoS2 anode materials 1-3 prepared in Examples 1-3. Figure 8 It is the rate performance diagram of the highly stable MoS2 anode materials 1-3 prepared in Examples 1-3. Figure 9 It is the cycling performance diagram of the highly stable MoS2 anode materials 1-3 prepared in Examples 1-3 at a current density of 0.1 A / g. Figure 10 It is the cycling performance diagram of the highly stable MoS2 anode material 1 prepared in Example 1 at a current density of 1.0 A / g. Figure 11 It is the cycling performance diagram of the MoS2 anode material prepared in Comparative Example 1 at a current density of 1.0 A / g.

[0119] According to Figure 1 it can be seen that the highly stable MoS2 anode materials prepared in Examples 1, 2, and 3 all have relatively high crystallinity, and all diffraction peaks correspond well to the 2H-phase MoS2. Among them, the intensity of the characteristic diffraction peak of the (002) crystal plane near 14.2° is very weak, indicating fewer layers.

[0120] According to Figure 2 it can be seen that the MoS2 anode material prepared in Comparative Example 1 has relatively high crystallinity, and all diffraction peaks correspond well to the 2H-phase MoS2. Among them, the intensity of the characteristic diffraction peak of the (002) crystal plane near 14.2° is significantly stronger than that of the materials in Examples 1, 2, and 3, indicating a significant increase in the number of layers.

[0121] According to Figure 3 it can be seen that the highly stable MoS2 anode material prepared in Example 2 is composed of numerous MoS2 nanosheets with a size of 20-150 nm stacked on each other.

[0122] According toFigure 4 It can be seen that the highly stable MoS2 anode material prepared in Example 2 is "divided" into numerous MoS2 nanosheets with a size of 20-150 nm by being confined by the mesoporous SiO2 template.

[0123] According to Figure 5 It can be seen that in the MoS2 anode material without etching the SiO2 hard template in Example 2, MoS2 is uniformly filled in the mesopores of the SiO2 template.

[0124] According to Figure 6 It can be seen that this indicates that some silicon atoms derived from the SiO2 template are uniformly doped in the MoS2 material.

[0125] According to Figure 7 It can be seen that the initial discharge specific capacity of the highly stable MoS2 anode material 1 prepared in Example 1 is as high as 696.1 mAh / g at a current density of 0.1 A / g, which is equivalent to the theoretical specific capacity; the initial discharge specific capacity of the highly stable MoS2 anode material 2 prepared in Example 2 is 822.8 mAh / g at a current density of 0.1 A / g, exceeding the theoretical specific capacity; the initial discharge specific capacity of the highly stable MoS2 anode material 3 prepared in Example 3 is 613.3 mAh / g at a current density of 0.1 A / g, which is very close to the theoretical specific capacity.

[0126] According to Figure 8 It can be seen that the specific capacities of the highly stable MoS2 anode material 1 prepared in Example 1 at current densities of 0.1, 0.2, 0.5, 1.0, 2.0, and 5.0 A / g are 696.1, 648.1, 582.4, 519.1, 444.1, and 323.5 mAh / g respectively, indicating that the material has excellent rate performance; the specific capacities of the highly stable MoS2 anode material 2 prepared in Example 2 at current densities of 0.1, 0.2, 0.5, 1.0, 2.0, and 5.0 A / g are 822.8, 814.7, 731.8, 647.8, 540.4, and 350.0 mAh / g respectively, indicating that the material has excellent rate performance; the specific capacities of the highly stable MoS2 anode material 3 prepared in Example 3 at current densities of 0.1, 0.2, 0.5, 1.0, 2.0, and 5.0 A / g are 626.5, 598.1, 540.6, 475.8, 404.3, and 293.6 mAh / g respectively, indicating that the material has excellent rate performance.

[0127] According to Figure 9It can be seen that the capacity retention rate of the highly stable MoS2 anode material 1 prepared in Example 1 can reach 111.2% after 100 stable cycles at a current density of 0.1 A / g; the capacity retention rate of the highly stable MoS2 anode material 2 prepared in Example 2 can reach 108.3% after 100 stable cycles at a current density of 0.1 A / g; the capacity retention rate of the highly stable MoS2 anode material 3 prepared in Example 3 can reach 115.1% after 100 stable cycles at a current density of 0.1 A / g.

[0128] According to Figure 10 It can be seen that the capacity of the highly stable MoS2 anode material 1 prepared in Example 1 shows basically no obvious attenuation after 500 stable cycles at a current density of 1.0 A / g, and the capacity retention rate is still 70.8% even after 1000 cycles.

[0129] According to Figure 11 It can be seen that the cycling stability of the MoS2 anode material prepared in Comparative Example 1 is very poor at a current density of 1.0 A / g. The specific capacity decays rapidly in the initial few cycles. The capacity retention rate after 50 cycles is only 32.9%, and the capacity retention rate is only 19.4% after 250 cycles.

[0130] As described above, the above are only specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed in the present application can easily think of changes or substitutions, which should all be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A high-stability MoS2 anode material, characterized in that, The crystallization is a thermodynamically stable pure 2H phase, which is stacked by nano-fragments with a size of 20 - 150 nm, has abundant edge sites, and at the same time, silicon atoms derived from the SiO2 template are incorporated to stabilize the MoS2 lattice structure; The preparation method of the high-stability MoS2 anode material comprises the following steps: dispersing a surfactant containing cetyltrimethylammonium cation CTA + and triethanolamine in water, adding a tetraethyl orthosilicate / cyclohexane mixed solution, carrying out a stirring reaction and a purification treatment, and collecting dendritic mesoporous SiO2 nanospheres surface-modified with CTA + ; Modify the surface with CTA + Disperse the dendritic mesoporous SiO2 nanospheres modified with CTA in an aqueous molybdate solution, perform vacuum filtration and drying to obtain the mesoporous SiO2@CTA + @MoO x composite material; Subject the mesoporous SiO2@CTA + @MoO x composite material and thiourea to a confined vulcanization reaction under an inert gas atmosphere to obtain a mesoporous SiO2@MoS2 composite material; After dispersing the mesoporous SiO2@MoS2 composite material in an aqueous sodium hydroxide solution for etching and purification, a high-stability MoS2 negative electrode material is obtained; Wherein, when the surface-modified CTA + dendritic mesoporous SiO2 nanospheres are dispersed in an aqueous molybdate solution, the mass ratio of the mesoporous SiO2 nanospheres to the molybdate is 1:8 to 25.

2. The high-stability MoS2 negative electrode material according to claim 1, characterized in that, The surfactant containing CTA + is one or more of cetyltrimethylammonium bromide and cetyltrimethylammonium chloride; and / or, the addition amount of the surfactant containing CTA + is 4 to 6 g; And / or, the addition amount of the triethanolamine is 0.5 - 1.0 mL, and the concentration is 0.35 g / mL.

3. The high-stability MoS2 negative electrode material according to claim 1, characterized in that, The addition amount of the tetraethyl orthosilicate is 3 - 5 mL; And / or, the addition amount of the cyclohexane is 15 - 25 mL; And / or, the stirring reaction time is 12 - 20 h.

4. The high-stability MoS2 negative electrode material according to claim 1, characterized in that, The collected surface-modified CTA + dendritic mesoporous SiO2 nanospheres, comprising: performing three centrifugal separations on the intermediate product using absolute ethanol to retain CTA on the surface of the mesoporous SiO2 pores + .

5. The high-stability MoS2 negative electrode material according to claim 1, wherein The molybdate is one or several of ammonium molybdate and sodium molybdate; And / or, the concentration of the molybdate aqueous solution is 1.0 mol / L.

6. The high-stability MoS2 negative electrode material according to claim 1, characterized in that, The mesoporous SiO2@CTA + @MoO x The mass ratio of the composite material to the thiourea is 1:1 to 3; And / or, the temperature of the confined sulfidation is 500 - 800 °C, the heating rate is 5 - 10 °C / min, and the sulfidation time is 2 - 5 h; And / or, the inert gas is one or several of nitrogen and argon, and the flow rate of the introduced gas is 20 - 60 mL / min.

7. The high-stability MoS2 negative electrode material according to claim 1, characterized in that, The concentration of the aqueous sodium hydroxide solution is 2 - 4 mol / L, and the etching time is 5 - 8 h.

8. The high-stability MoS2 negative electrode material according to any one of claims 1 - 7 is applied to a lithium-ion battery.

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