A stable metal phase CoS2-MoS2 composite based on heterostructure and phase engineering cooperative regulation and a preparation method and rapid lithium storage application thereof
By synergistically regulating CoS2-MoS2 composite materials through heterostructure and phase engineering, the conductivity and stability issues of molybdenum disulfide-based anode materials have been solved, achieving a performance improvement in high-efficiency lithium-ion battery anode materials, suitable for rapid lithium storage applications.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- TARIM UNIV
- Filing Date
- 2026-04-20
- Publication Date
- 2026-07-14
Smart Images
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Abstract
Description
Technical Field
[0001] This invention relates to a stable metallic phase CoS2-MoS2 composite material based on the synergistic regulation of heterostructure and phase engineering, its preparation method and rapid lithium storage application, belonging to the fields of new energy materials and electrochemical energy storage technology. Background Technology
[0002] With the rapid development of portable electronic devices, electric vehicles, and large-scale energy storage systems, lithium-ion batteries are increasingly demanding higher energy density, higher power density, and longer cycle life. While traditional graphite-based anode materials exhibit good cycle stability, their theoretical capacity is relatively low, and they struggle to meet the requirements of novel energy storage devices for rapid energy storage and efficient energy conversion under high-rate charge-discharge conditions. Therefore, developing novel anode materials with higher capacity and superior kinetic characteristics has become a crucial research direction in the field of electrochemical energy storage.
[0003] Transition metal sulfides have shown significant application potential in lithium-ion battery anode materials due to their high theoretical specific capacity, abundant redox reactivity, and tunable layered or polycrystalline structures. Among them, molybdenum disulfide (MoS2), as a typical layered transition metal sulfide, possesses a large interlayer spacing and two-dimensional channels for lithium-ion insertion / extraction, making it a highly representative candidate material. However, conventional MoS2 mostly exists as a thermodynamically stable semiconductor (2H) phase, with low intrinsic electronic conductivity and limited interfacial charge transport capacity. In actual charge-discharge processes, it is prone to problems such as slow reaction kinetics, severe polarization, and insufficient structural stability, thus limiting its rate performance and cycle life.
[0004] To overcome these shortcomings, researchers have proposed various optimization strategies, including nanostructure manipulation, carbon composites, defect engineering, heterostructure construction, and phase engineering. Among these, phase engineering, by adjusting the crystal structure of MoS2 to transform it from the 2H phase to a metallic (1T) phase with higher electrical conductivity, is an important means to improve its intrinsic electronic structure and lithium storage kinetics. However, 1T-MoS2 is a metastable phase, which presents challenges such as difficult preparation, poor stability, and difficulty in precisely controlling the phase content. Therefore, how to effectively induce and stably construct the 1T-MoS2 phase remains a key scientific and technological problem in this field. Summary of the Invention
[0005] To address the shortcomings of existing technologies, this invention provides a stable CoS2-MoS2 composite material based on the synergistic regulation of heterostructure and phase engineering, its preparation method, and its application in rapid lithium storage. This addresses the problems of poor intrinsic conductivity, slow lithium-ion diffusion kinetics, insufficient rate performance, and limited structural stability during cycling of existing molybdenum disulfide-based anode materials. Furthermore, to address the deficiencies of existing technologies, such as the difficulty in stabilizing the MoS2 metallic phase, uneven heterostructure construction, limited interfacial coupling in the composite system, and insufficient synergistic lithium storage effect, this invention achieves uniform composite of CoS2 and MoS2 and stable regulation of the MoS2 metallic phase through precursor structure regulation and heterostructure construction. This improves the material's electron transport capability, interfacial charge transfer kinetics, and lithium-ion diffusion behavior, thereby enhancing its rapid lithium storage performance and cycle stability.
[0006] The heterostructure composite material of this invention can be prepared through precursor design combined with hydrothermal reaction. The core of this method lies in: firstly, constructing a molybdenum blue cluster precursor system by acidifying a molybdenum source solution, and introducing a cobalt source during this process to achieve uniform dispersion and effective coupling of molybdenum and cobalt components in the precursor stage; subsequently, adding a sulfur source, and generating a CoS2-MoS2 heterostructure composite material in situ via hydrothermal reaction. By controlling the types and ratios of the molybdenum, cobalt, and sulfur sources, and by regulating the pH, temperature, and reaction time of the reaction system, uniform distribution of molybdenum and cobalt elements is achieved in the precursor stage, and a CoS2-MoS2 composite structure is generated in situ during the subsequent reaction, while simultaneously inducing the transformation of MoS2 from a semiconductor phase to a metallic phase. Furthermore, by utilizing the high conductivity of CoS2 and the electronic coupling effect at the heterostructure interface, the metallic phase structure of MoS2 is stabilized, the interface electron distribution is optimized, and rapid electron migration within the material and lithium ion transport at the interface and between layers are promoted. The composite material can be used as a negative electrode active material for lithium-ion batteries. It can be mixed with conductive agents and binders to form a slurry and coated on the surface of the current collector to assemble into a half cell or a full cell, so as to realize lithium storage applications under rapid charge and discharge conditions.
[0007] The technical solution adopted in this invention is as follows:
[0008] A stable metallic phase CoS2-MoS2 composite material based on the synergistic regulation of heterostructure and phase engineering, the composite material is composed of CoS2 and MoS2, wherein a tightly coupled heterogeneous interface is formed between CoS2 and MoS2, and the MoS2 contains a stable MoS2 metallic phase structure.
[0009] The above-mentioned method for preparing stable metallic CoS2-MoS2 composite materials based on the synergistic regulation of heterostructure and phase engineering includes the following steps:
[0010] (1) Dissolve the molybdenum source in water, adjust the pH, and then add the cobalt source to obtain a molybdenum blue cluster precursor solution through reaction;
[0011] (2) The sulfur source was dissolved in the molybdenum blue cluster precursor solution, and after hydrothermal reaction, the mixture was filtered, washed and dried to obtain a stable metal phase CoS2-MoS2 composite material based on the synergistic regulation of heterostructure and phase engineering.
[0012] According to a preferred embodiment of the present invention, in step (1), the molybdenum source is one or a combination of two or more of ammonium molybdate, sodium molybdate, potassium molybdate, or molybdic acid, preferably ammonium molybdate.
[0013] According to a preferred embodiment of the present invention, in step (1), the molar ratio of the molar amount of the molybdenum source to the volume ratio of water is 0.01-0.1 mol / L.
[0014] According to a preferred embodiment of the present invention, in step (1), an acidifying agent is added to adjust the pH to 1-2; the acidifying agent is one or a combination of two or more of hydrochloric acid, nitric acid, sulfuric acid or organic acid, preferably an aqueous solution of hydrochloric acid with a mass concentration of 20-40%.
[0015] According to a preferred embodiment of the present invention, in step (1), the cobalt source is one or a combination of two or more of cobalt nitrate, cobalt chloride, cobalt acetate or cobalt sulfate, with cobalt nitrate being preferred.
[0016] According to a preferred embodiment of the present invention, in step (1), the molar ratio of the molybdenum source to the cobalt source is 1:0.8-2.4.
[0017] According to a preferred embodiment of the present invention, in step (1), the reaction temperature is room temperature, the reaction time is 0.5-3 h, and the reaction is carried out under stirring conditions. The solution color gradually changes from colorless or light color to blue or dark blue, thereby forming a molybdenum blue cluster precursor solution.
[0018] According to the present invention, the concentration of molybdenum source, the degree of acidification, and the amount of cobalt source added in step (1) can be adjusted according to the ratio of CoS2 to MoS2 in the target product and the final phase structure. For example, appropriately increasing the amount of cobalt source added is beneficial to increasing the CoS2 content and enhancing the interfacial coupling effect; adjusting the amount of acid helps to affect the degree of formation of molybdenum blue clusters and the behavior of subsequent sulfidation reactions.
[0019] According to a preferred embodiment of the present invention, in step (2), the sulfur source is one or a combination of two or more of thiourea, thioacetamide, sodium sulfide, thiosulfate or cysteine, preferably thiourea.
[0020] According to a preferred embodiment of the present invention, in step (2), the molar ratio of the sulfur source to the molybdenum source in step (1) is 90-110:1, preferably 100:1. The molar ratio of the sulfur source to the metal ions can be adjusted according to the degree of sulfidation and crystallization behavior of the target product. Generally, a higher amount of sulfur source is beneficial to promoting complete sulfidation, but excessive sulfur source may also affect the morphology and particle size of the product, so it can be optimized according to actual needs.
[0021] According to a preferred embodiment of the present invention, in step (2), the hydrothermal reaction temperature is 160–220 °C, preferably 180–210 °C; the reaction time is 6–36 h, preferably 12–24 h. The volume of the reactor used for the hydrothermal reaction can be adjusted according to the amount of material fed, for example, 25 mL, 40 mL, 50 mL, 100 mL, etc. can all be used. The drying method can be vacuum drying, forced air drying, freeze drying, etc., among which vacuum drying is preferred to reduce the risk of oxidation or agglomeration on the material surface.
[0022] According to the present invention, the preparation method of the present invention can also adopt other variations. For example, after obtaining the molybdenum blue cluster precursor solution, a pre-aging treatment can be performed first, followed by step (2), that is, adding a sulfur source for hydrothermal reaction to further regulate the nucleation process; or after obtaining the product in step (2), a post-treatment annealing under an inert or reducing atmosphere can be performed to optimize the material's crystallinity, interfacial bonding state, and metallic phase stability. The pre-aging treatment conditions are standing at room temperature for 10-15 hours; the annealing atmosphere can be argon, nitrogen, a hydrogen-argon mixture, sulfur vapor atmosphere, etc., the annealing temperature can be 200-800 ℃, and the annealing time can be 0.5-6 h. Through the above post-treatment, the defect concentration, crystal phase ratio, and conductivity of the material can be further adjusted.
[0023] The above-mentioned stable metallic phase CoS2-MoS2 composite material based on the synergistic regulation of heterostructure and phase engineering is used in rapid lithium storage.
[0024] According to a preferred embodiment of the present invention, a stable metallic phase CoS2-MoS2 composite material is used as a negative electrode active material in lithium-ion batteries. Its application can employ conventional electrode fabrication processes in the art. Generally, the obtained active material, conductive agent, and binder are mixed in a mass ratio to form a uniform slurry, which is then coated onto the surface of a copper foil current collector. After drying, rolling, and stamping, a negative electrode sheet is formed. The conductive agent can be one or more of acetylene black, Super P, conductive carbon black, carbon nanotubes, graphene, etc.; the binder can be one or more of polyvinylidene fluoride, sodium carboxymethyl cellulose, styrene-butadiene rubber, polyacrylic acid, etc. Preferably, the mass ratio of the active material, conductive agent, and binder can be 70–90:5–20:5–15, for example, 80:10:10. The prepared negative electrode sheet can be assembled with a lithium metal counter electrode, a separator, and an electrolyte to form a coin cell for testing its charge-discharge performance, rate performance, and cycle stability; it can also be matched with commercial positive electrode materials to form a full cell for evaluating its practical energy storage performance.
[0025] The working principle of this invention lies in achieving uniform coupling of molybdenum and cobalt components during the precursor stage through a molybdenum blue cluster precursor. This allows CoS2 and MoS2 to form a tightly contacted heterogeneous interface in situ during subsequent hydrothermal sulfidation. Simultaneously, the introduction of CoS2 and its interfacial electronic coupling with MoS2 helps to regulate the local electronic structure of MoS2 and promotes the formation and stabilization of the metallic phase. In the resulting composite material, CoS2 improves overall electronic conductivity, the layered structure of MoS2 facilitates lithium-ion insertion / extraction, and the heterogeneous interface promotes interfacial charge transfer and reduces lithium-ion migration resistance, thereby achieving rapid lithium storage. Furthermore, the heterogeneous structure can alleviate volume changes and particle agglomeration during charge and discharge processes to some extent, improving electrode structural stability and cycle reversibility.
[0026] Technical features and beneficial effects of the present invention:
[0027] 1. This invention utilizes a precursor structure regulation strategy, employing molybdenum blue clusters as the reaction precursor. This facilitates the uniform dispersion and effective coupling of the molybdenum and cobalt sources during the precursor stage, thus providing a sound compositional basis for the subsequent in-situ formation of CoS2-MoS2 heterostructures. Compared to traditional simple mixing or post-composite methods, the precursor design method employed in this invention improves the uniformity of the distribution of each component at the microscale, enhances the interfacial contact between CoS2 and MoS2, and helps construct a structurally stable and clearly defined heterocomposite system, thereby addressing the problem of insufficient interfacial synergy in composite materials.
[0028] 2. In the CoS2-MoS2 heterostructure composite material constructed in this invention, CoS2 exhibits high electronic conductivity, while MoS2 possesses a layered structure and a high theoretical lithium storage capacity. The combination of these two materials achieves a synergistic match between conductivity and capacity characteristics. On one hand, the introduction of CoS2 helps improve the overall electron transport capability of the composite material, reduces charge transfer impedance, and alleviates the polarization problem caused by the poor conductivity of traditional MoS2. On the other hand, the layered structure of MoS2 provides diffusion channels for lithium-ion insertion and extraction, which is beneficial for maintaining high lithium storage activity. Therefore, this invention, through heterostructure design, can balance the conductivity and energy storage performance of the material, which is beneficial for improving the overall electronic conductivity of the material and reducing charge transfer impedance, providing an effective way to improve the comprehensive electrochemical performance of lithium-ion battery anode materials.
[0029] 3. This invention can induce and stabilize the metallic phase structure in MoS2, improve its intrinsic electronic structure, and enhance its electrochemical reactivity. Compared with the conventional thermodynamically stable 2H semiconductor phase MoS2, the metallic phase MoS2 has higher electronic conductivity and better interfacial charge transfer kinetics, which is more conducive to lithium storage reactions under rapid charge-discharge conditions. However, the metallic phase MoS2 is usually metastable, and suffers from high preparation difficulty, insufficient stability, and susceptibility to phase transition. This invention improves the formation conditions and stability retention of the metallic phase MoS2 to a certain extent through the regulation of the molybdenum blue cluster precursor and the coupling effect of the CoS2-MoS2 heterostructure interface. The resulting composite material combines the advantages of both metallic phase regulation and heterostructure synergy, thereby improving the intrinsic electronic structure and reactivity of the material.
[0030] 4. The heterostructure formed between CoS2 and MoS2 in this invention helps to redistribute electrons at the interface and create a localized environment conducive to charge migration, thereby promoting rapid electron transport within the material and at the interface (facilitating lithium-ion diffusion and interfacial reaction kinetics) and reducing the diffusion barrier of lithium ions in the interfacial region. Compared with single-component materials, this heterostructure can more effectively accelerate electrochemical reaction kinetics during charge and discharge, improving the material's capacity retention and rate response performance under high current density conditions. Therefore, this invention has significant advantages in rapid lithium storage applications and can better meet the requirements of high-power lithium-ion batteries for rapid charge and discharge performance.
[0031] 5. This invention also exhibits good structural stability. Traditional MoS2 is prone to volume expansion, interlayer stacking, particle agglomeration, and local structural collapse during repeated lithium insertion / extraction processes, leading to a reduction in active sites, intensified interfacial side reactions, and accelerated capacity decay. This invention, by constructing a tightly coupled CoS2-MoS2 composite structure, not only helps disperse active components and inhibit material agglomeration, but also mitigates stress changes, volume changes, and structural decay during charge and discharge processes through the support and synergistic effect of the heterogeneous interface, enhancing electrode structural integrity and improving reversibility and stability during cycling. Therefore, the composite material prepared by this invention is beneficial in maintaining good structural stability and capacity retention under long-term cycling conditions.
[0032] 6. The preparation method of this invention also has the advantages of relatively simple process, readily available raw materials, well-defined reaction process, and good reproducibility. The synthetic route adopted is based on common molybdenum, cobalt, and sulfur sources. Precursor construction and composite material growth can be achieved through solution reaction and hydrothermal treatment, without the need for complex equipment or harsh conditions, which facilitates laboratory preparation and subsequent process scale-up. Compared with some preparation methods that require multi-step processing, high-temperature vapor deposition, or complex template assistance, the process of this invention is more operable, which is conducive to improving the consistency of material preparation and its potential for widespread application.
[0033] 7. This invention is not only applicable to the development of lithium-ion battery anode materials, but also provides ideas for the design and preparation of other transition metal sulfide heterostructure materials. By combining precursor regulation with interface engineering, it can be extended to other energy storage systems or related functional materials, possessing certain versatility and methodological reference value.
[0034] 8. This invention effectively improves the problems of insufficient conductivity, limited interfacial transport, difficulty in stabilizing the metal phase, and poor rate performance and cycle stability of existing MoS2-based anode materials through the synergistic effect of molybdenum blue cluster precursor regulation, CoS2-MoS2 heterostructure construction, and MoS2 metal phase stabilization. As a result, the composite material exhibits better comprehensive performance in rapid lithium storage applications, such as excellent rate performance, reversible specific capacity, and cycle stability, which has clear technological progress significance and application value. Attached Figure Description
[0035] Figure 1 The images show the scanning electron microscope (SEM) morphology (a), transmission electron microscope (TEM) morphology (b), elemental distribution (c), and high-resolution transmission electron microscope (HEM) images (d) of the composite material prepared in Example 1.
[0036] Figure 2 The XRD patterns (a) and Raman spectra (b) of the CoS2-MoS2 composite material, pure CoS2, and pure MoS2 prepared in Example 1 are shown.
[0037] Figure 3 The cyclic voltammetry curves are shown for batteries assembled from the CoS2-MoS2 composite material (a) prepared in Example 1, the CoS2 material (b) prepared in Comparative Example 3, and the MoS2 material (c) prepared in Comparative Example 1.
[0038] Figure 4 The figures show the cycle performance test curves (a) and rate performance test curves (b) of batteries assembled from the CoS2-MoS2 composite material prepared in Example 1, the CoS2 material prepared in Comparative Example 3, and the MoS2 material prepared in Comparative Example 1 at 1 A / g.
[0039] Figure 5 Impedance diagrams (a), constant current intermittent titration test diagrams (b), and lithium ion diffusion coefficient diagrams (c) and (d) are obtained from batteries assembled from the CoS2-MoS2 composite material prepared in Example 1, the CoS2 material prepared in Comparative Example 3, and the MoS2 material prepared in Comparative Example 1.
[0040] Figure 6 These are XPS spectra of the CoS2-MoS2 composite materials prepared in Examples 1-3.
[0041] Figure 7 This is the XPS Mo 3d spectrum of the composite material prepared in Comparative Example 2.
[0042] Figure 8 This is the cycle performance test curve of the battery assembled from the composite material prepared in Comparative Example 2 at 1A / g. Detailed Implementation
[0043] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. Equivalent substitutions, simple modifications, or combined optimizations made by those skilled in the art based on the content of the present invention without departing from the concept and essence of the present invention should all fall within the scope of protection of the present invention.
[0044] Example 1
[0045] A method for preparing a stable metallic phase CoS2-MoS2 composite material based on the synergistic regulation of heterostructure and phase engineering includes the following steps:
[0046] Weigh 0.196 g (0.001 mol) of ammonium molybdate and add it to 30 mL of deionized water. Stir magnetically at room temperature for 20 min until completely dissolved. Add 2 mL of 30% hydrochloric acid aqueous solution to acidify the system to pH 1. Then add 0.146 g (0.0008 mol) of cobalt nitrate and continue stirring at room temperature for 1 h until the solution turns dark blue, thus obtaining the molybdenum blue cluster precursor solution.
[0047] 0.8 g (0.1 mol) of thiourea was added to the precursor solution, and the mixture was stirred for 20 min. The mixture was then transferred to a 40 mL polytetrafluoroethylene-lined stainless steel reactor and reacted at 200 °C for 24 h. After natural cooling, the mixture was filtered, washed with deionized water and ethanol, and dried under vacuum at 60 °C for 6 h to obtain CoS2-MoS2 composite material sample S1.
[0048] Figure 1 (a) and (b) are scanning electron microscope and transmission electron microscope images of the CoS2-MoS2 composite material prepared in this embodiment, respectively. As can be seen from the figures, the composite material has a uniform morphology and forms a sheet-like structure. This structure provides a large number of lithium-ion reactive sites, which ensures excellent lithium storage performance.
[0049] Figure 1 (c) is the elemental distribution diagram of the CoS2-MoS2 composite material prepared in this embodiment. As can be seen from the figure, the heterostructure prepared by this method has a uniform elemental distribution and no agglomeration phenomenon.
[0050] Figure 1 (d) is a high-resolution transmission electron microscope image of the CoS2-MoS2 composite material prepared in this embodiment. As can be seen from the figure, the heterostructure crystal structure is complete, and a clear two-phase structure can be observed, indicating the presence of a large number of heterostructure interfaces.
[0051] Figure 2 (a) shows the XRD patterns of the CoS2-MoS2 composite material (CoS2-MoS2) prepared in this embodiment, as well as CoS2 (prepared in Comparative Example 3) and MoS2 (prepared in Comparative Example 1). As can be seen from the figure, the heterostructure was successfully constructed. No other diffraction peaks were detected in the XRD patterns, indicating that there are no other crystalline phases or contaminants in the heterostructure. The (002) diffraction peak of MoS2 shifts to a smaller angle, indicating that its interlayer spacing increases. This result is consistent with the HRTEM image.
[0052] Figure 2 (b) shows the Raman spectra of the CoS2-MoS2 composite materials prepared in Examples 1 (CM1), 2 (CM2), and 3 (CM3) and the MoS2 prepared in Comparative Example 1. As can be seen from the figure, the Raman spectrum of the CoS2-MoS2 heterostructure differs significantly from that of MoS2 in Comparative Example 1. At 146.0 cm⁻¹... -1 194.1 cm -1 280.1 cm -1 and 335.0 cm -1Characteristic peaks originating from the MoS2 1T phase were detected at [a specific location], corresponding to the J1, J2, E1g, and J3 vibrational modes, respectively; while the Raman spectrum of MoS2 only reached [a specific value] at 376.4 cm⁻¹. -1 and 402.6 cm -1 There are two peaks at this point, corresponding to the E2g and A1g modes of the 2H phase MoS2. This result proves that CoS2 induces the phase transition of MoS2, thereby ensuring the existence of the 1T phase in the heterostructure.
[0053] Example 2
[0054] A method for preparing a stable metallic phase CoS2-MoS2 composite material based on the synergistic regulation of heterostructure and phase engineering is disclosed. As described in Example 1, the difference is that the amount of cobalt nitrate added is adjusted to 0.291 g (0.0016 mol), while the remaining steps and conditions are the same as in Example 1, yielding a CoS2-MoS2 composite material sample S2. This example illustrates the effect of different cobalt contents on the formation of heterostructures and material properties.
[0055] Example 3
[0056] A method for preparing a stable metallic CoS2-MoS2 composite material based on the synergistic regulation of heterostructure and phase engineering is disclosed. As described in Example 1, the difference is that the amount of cobalt nitrate added is adjusted to 0.437 g (0.0024 mol), while the remaining steps are the same as in Example 1, yielding the CoS2-MoS2 composite material sample S3. This example further illustrates the regulatory effect of changes in the amount of cobalt source added on the phase composition, microstructure, and lithium storage performance of the material.
[0057] Comparative Example 1
[0058] A method for preparing MoS2 material, comprising the following steps:
[0059] Weigh 0.196 g (0.001 mol) of ammonium molybdate and add it to 30 mL of deionized water. Stir magnetically at room temperature for 20 min until completely dissolved. Add 2 mL of 30% hydrochloric acid aqueous solution to acidify the system to pH 1, and continue stirring at room temperature for 1 h to obtain the precursor solution.
[0060] 0.8 g (0.1 mol) of thiourea was added to the precursor solution, and the mixture was stirred for 20 min. The mixture was then transferred to a 40 mL polytetrafluoroethylene-lined stainless steel reactor and reacted at 200 °C for 24 h. After natural cooling, the mixture was filtered, washed with deionized water and ethanol, and dried under vacuum at 60 °C for 6 h to obtain MoS2 material.
[0061] Comparative Example 2
[0062] A method for preparing a CoS2-MoS2 composite material, comprising the following steps:
[0063] 0.196 g (0.001 mol) of ammonium molybdate was weighed and added to 30 mL of deionized water. The mixture was magnetically stirred at room temperature for 20 min until completely dissolved. Then, 0.146 g (0.0008 mol) of cobalt nitrate and 0.8 g (0.1 mol) of thiourea were added, and stirring was continued for another 20 min. The mixture was then transferred to a 40 mL polytetrafluoroethylene-lined stainless steel reactor and reacted at 200 ℃ for 24 h. After natural cooling, the mixture was filtered, washed with deionized water and ethanol, and vacuum dried at 60 ℃ for 6 h to obtain the CoS2-MoS2 composite material sample C1. This comparative example illustrates the role of precursor regulation strategies in the uniform dispersion of components, the formation of heterogeneous interfaces, and the stabilization of the metal phase.
[0064] Comparative Example 3
[0065] A method for preparing CoS2 material, comprising the following steps:
[0066] Weigh 0.146 g (0.0008 mol) of cobalt nitrate and add it to 30 mL of deionized water. Stir magnetically at room temperature for 20 min until completely dissolved. Add 2 mL of 30% hydrochloric acid aqueous solution to acidify the system to pH 1, and continue stirring at room temperature for 1 h to obtain the precursor solution.
[0067] 0.8 g (0.1 mol) of thiourea was added to the precursor solution, and the mixture was stirred for 20 min. The mixture was then transferred to a 40 mL polytetrafluoroethylene-lined stainless steel reactor and reacted at 200 °C for 24 h. After natural cooling, the mixture was filtered, washed with deionized water and ethanol, and dried under vacuum at 60 °C for 6 h to obtain the CoS2 material sample.
[0068] Experimental Example 1
[0069] Battery assembly and performance testing
[0070] The samples obtained from the examples and comparative examples, conductive carbon black, and polyvinylidene fluoride were mixed at a mass ratio of 8:1:1, and a slurry was prepared using N-methylpyrrolidone as a solvent. This slurry was uniformly coated onto the surface of copper foil, vacuum dried at 80–120 °C for 8–12 h, and then punched into discs to serve as the working electrode. A CR2032 coin cell was assembled in a glove box using a lithium metal sheet as the counter electrode, a polypropylene microporous membrane as the separator, and a conventional lithium-ion electrolyte (lithium hexafluorophosphate). The lithium storage performance of the material was evaluated by constant current charge-discharge, cyclic voltammetry, and AC impedance testing.
[0071] Figure 3The cyclic voltammetry (1A g) curves of batteries assembled from the CoS2-MoS2 composite material prepared in Example 1 (a), the CoS2 material prepared in Comparative Example 3 (b), and the MoS2 material prepared in Comparative Example 1 (c) are shown below. -1 ).like Figure 3 (a) During the first discharge cycle, three peaks appear at 1.15 V, 0.95 V, and 0.61 V. The peak at 1.15 V corresponds to the MoS2 phase transition caused by lithium-ion intercalation. The peak at 0.95 V is attributed to the conversion of CoS2 to Co. The broad peak at 0.61 V indicates the conversion of LixMoS2 to Li2S and Mo, accompanied by the formation of a solid electrolyte interfacial film. During charging, three distinct peaks at 1.91 V, 2.01 V, and 2.28 V correspond to the conversion reactions of Mo to MoS2, Co to CoS2, and Li2S to S, respectively. The third CV curve highly overlaps with the second, indicating that the CoS2-MoS2 heterostructure has a highly reversible lithium storage reaction. Figure 3 As shown in (b), the CV curves of CoS2 reveal a clear reaction mechanism. The three peaks at 1.30 V, 0.87 V, and 0.69 V are attributed to the reduction of CoS2 to Co and the formation of the SEI film. Subsequent CV curves show significant differences, indicating that the lithium storage reaction of the prepared CoS2 material is unstable, which may lead to capacity decay during long-term cycling. The CV curve of 2H MoS2 shows a large peak at 0.90 V, representing the process of lithium-ion intercalation into 2H MoS2. The difference in the first-cycle CV curves between CoS2-MoS2 and MoS2 confirms the presence of the 1T phase MoS2 in the heterostructure.
[0072] Figure 4 (a) shows the cycle performance test curves at 1 A / g for batteries assembled from the CoS2-MoS2 composite material prepared in Example 1, the CoS2 material prepared in Comparative Example 3, and the MoS2 material prepared in Comparative Example 1. The reversible capacity of the CoS2-MoS2 sample after 1000 cycles is 776.3 mAh g. -1 The capacity retention rate was 84.2%. The capacity of MoS2 after 1000 cycles was 512.2 mAh g⁻¹. -1 The capacity was 59.1% of its initial capacity; the capacity of CoS2 after 1000 cycles was 470.2 mAh g. -1 The capacity retention rate is 76.2% of the initial capacity. The excellent cycling performance and capacity retention rate of CoS2-MoS2 are attributed to the construction of the heterostructure, which introduces more interfaces and lithium storage active sites.
[0073] Figure 4(b) shows the rate performance test curves of batteries assembled from the CoS2-MoS2 composite material prepared in Example 1, the CoS2 material prepared in Comparative Example 3, and the MoS2 material prepared in Comparative Example 1. The capacities of the CoS2-MoS2 samples at 0.1, 0.2, 0.5, 1, 2, and 5 A / g were 1162.2, 1075.3, 934.8, 805.3, 592.3, and 333.7 mAh g, respectively. -1 When the current density recovers to 1 A g -1 Afterwards, the capacity rebounded to 700.1 mAh g. -1 The CoS2-MoS2 hybrid exhibits superior rate performance. In contrast, both CoS2 and MoS2 show inferior rate performance, with lower rate capacity and capacity retention. The enhanced rate performance of CoS2-MoS2 reflects the advantages of the designed heterostructure. The 1T phase and the built-in electric field together improve conductivity and lithium-ion diffusion capability, contributing to rapid lithium storage.
[0074] Figure 5 (a) is an impedance diagram of a battery assembled from the CoS2-MoS2 composite material prepared in Example 1, the CoS2 material prepared in Comparative Example 3, and the MoS2 material prepared in Comparative Example 1, showing that the heterostructure has the lowest battery internal resistance.
[0075] Figure 5 (b) shows the constant current (0.1, 0.2, 0.5, 1, 2, 5, 0.1 A g) of batteries assembled from the CoS2-MoS2 composite material prepared in Example 1, the CoS2 material prepared in Comparative Example 3, and the MoS2 material prepared in Comparative Example 1. -1 Intermittent titration tests showed that the heterostructure had the best lithium storage capacity. In the same low-current intermittent charge-discharge test, the heterostructure had more charge-discharge cycles and a higher total charge-discharge capacity than the control sample, demonstrating enhanced electrochemical performance.
[0076] Figure 5 (c) and (d) are lithium-ion diffusion coefficient diagrams of batteries assembled from the CoS2-MoS2 composite material prepared in Example 1, the CoS2 material prepared in Comparative Example 3, and the MoS2 material prepared in Comparative Example 1 (current density 0.05 A g). -1 Charging time: 60 seconds; resting time: 20 minutes. During lithiation (c) and delithiation (d), the lithium diffusion coefficient is within 10... -13 Up to 10 -11 cm 2 s -1Within the range, the diffusion coefficient is higher than that of MoS2 and CoS2. The increased conductivity and lithium-ion diffusion coefficient indicate that the combination of heterostructure design and 1T phase MoS2 significantly improves the electrochemical performance of the composite material, making the CoS2-MoS2 structure a promising anode material for lithium-ion batteries.
[0077] Figure 8 The figures show the cycle performance test curves of the battery assembled from the composite material prepared in Comparative Example 2 at 1 A / g. -1 The capacity is 500 mAh g after 200 cycles at current density. -1 The capacity retention rate is 83%.
[0078] Test results show that the CoS2-MoS2 heterostructure composite material prepared in this invention exhibits superior overall performance in terms of rate capability, cycle stability, and charge transfer impedance compared to the pure control sample and the composite sample without the molybdenum blue cluster precursor.
[0079] Experimental Example 2
[0080] XPS tests were performed on the materials obtained in Examples 1 (CM1), 2 (CM2), and 3 (CM3). The XPS spectra are shown below. Figure 6 As shown, the Mo 3d XPS spectrum of sample CM1 can be deconvolved into four peaks, indicating that MoS2 simultaneously contains both the 1T and 2H phases. The two peaks at 229.1 eV and 232.2 eV correspond to the Mo 3d phase in 1T MoS2, respectively. 5 / 2 and Mo 3d 3 / 2 The two peaks at 230.3 eV and 233.5 eV correspond to Mo 3d in the 2H phase. 5 / 2 and Mo 3d 3 / 2 The specific peaks at 226.5 eV and 236.4 eV are attributed to S 2s and Mo, respectively. 6+ The presence of slight surface oxidation in the heterostructure was observed. Calculations based on the peak area integration showed that the 1T phase content in the CM1 sample was 50.2%. The S 2p XPS spectrum yielded the same result, confirming the successful preparation of 1T MoS2. The S 2p phase attributed to the 1T phase... 1 / 2 and S 2p 3 / 2 The peaks are located at 163.1 eV and 161.7 eV, respectively; the other two peaks of the 2H phase are located at 163.8 eV and 162.2 eV, respectively. The Co 2p spectrum shows two characteristic peaks that can be decomposed into two pairs of peaks and two companion peaks: the first pair of peaks is located at 781.0 eV and 797.3 eV, which belong to Co 3+ 2p 3 / 2 and 2p 1 / 2The other pair of peaks, located at 782.6 eV and 798.8 eV, are attributed to Co. 2+ Co 3+ and Co 2+ The characteristic peaks indicate the presence of the cubic phase CoS2 in the heterostructure. Figure 6 (df) shows the same trend in the XPS spectra of Mo 3d, S 2p, and Co 2p in samples CM2 and CM3. In samples CM2 and CM3, the Mo 3d and S 2p XPS spectra show the same peaks, indicating that MoS2 contains both 1T and 2H phases. The calculated 1T phase contents in samples CM2 and CM3 are 61.3% and 48.6%, respectively. The difference in 1T phase content stems from the different Co contents in the precursors, indicating that the proportion of Co species controls the 1T phase content in the heterostructure.
[0081] XPS testing was performed on the material obtained in Comparative Example 2. The XPS Mo 3d spectrum is shown below. Figure 7 As shown, this indicates that without the introduction of the molybdenum blue structure, the metallic phase molybdenum disulfide cannot be formed.
Claims
1. A stable metallic phase CoS2-MoS2 composite material based on the synergistic regulation of heterostructure and phase engineering, characterized in that, The composite material is composed of CoS2 and MoS2, wherein a tightly coupled heterogeneous interface is formed between CoS2 and MoS2, and MoS2 contains a stable MoS2 metallic phase structure.
2. The preparation method of the stable metallic phase CoS2-MoS2 composite material based on the synergistic regulation of heterostructure and phase engineering as described in claim 1, comprising the steps of: (1) Dissolve the molybdenum source in water, adjust the pH, and then add the cobalt source to obtain a molybdenum blue cluster precursor solution through reaction; (2) The sulfur source was dissolved in the molybdenum blue cluster precursor solution, and after hydrothermal reaction, the mixture was filtered, washed and dried to obtain a stable metal phase CoS2-MoS2 composite material based on the synergistic regulation of heterostructure and phase engineering.
3. The method for preparing stable metallic phase CoS2-MoS2 composite material based on the synergistic regulation of heterostructure and phase engineering according to claim 2, characterized in that, In step (1), the molybdenum source is one or a combination of two or more of ammonium molybdate, sodium molybdate, potassium molybdate, or molybdic acid, preferably ammonium molybdate.
4. The method for preparing stable metallic phase CoS2-MoS2 composite material based on the synergistic regulation of heterostructure and phase engineering according to claim 2, characterized in that, In step (1), the molar ratio of the molar amount of the molybdenum source to the volume ratio of water is 0.01-0.1 mol / L; Preferably, in step (1), an acidifying agent is added to adjust the pH to 1-2; the acidifying agent is one or more of hydrochloric acid, nitric acid, sulfuric acid or organic acid, preferably a hydrochloric acid aqueous solution with a mass concentration of 20-40%.
5. The method for preparing stable metallic phase CoS2-MoS2 composite material based on the synergistic regulation of heterostructure and phase engineering according to claim 2, characterized in that, In step (1), the cobalt source is one or a combination of two or more of cobalt nitrate, cobalt chloride, cobalt acetate or cobalt sulfate, with cobalt nitrate being preferred.
6. The method for preparing stable metallic CoS2-MoS2 composite materials based on the synergistic regulation of heterostructure and phase engineering according to claim 2, characterized in that, In step (1), the molar ratio of molybdenum source to cobalt source is 1:0.8-2.
4.
7. The method for preparing stable metallic CoS2-MoS2 composite materials based on the synergistic regulation of heterostructure and phase engineering according to claim 2, characterized in that, In step (1), the reaction temperature is room temperature, the reaction time is 0.5-3h, and the reaction is carried out under stirring conditions.
8. The method for preparing stable metallic CoS2-MoS2 composite materials based on the synergistic regulation of heterostructure and phase engineering according to claim 2, characterized in that, In step (2), the sulfur source is one or a combination of two or more of thiourea, thioacetamide, sodium sulfide, thiosulfate or cysteine, preferably thiourea.
9. The method for preparing stable metallic CoS2-MoS2 composite materials based on the synergistic regulation of heterostructure and phase engineering according to claim 2, characterized in that, In step (2), the molar ratio of the sulfur source to the molybdenum source in step (1) is 90-110:1, preferably 100:1; Preferably, in step (2), the hydrothermal reaction temperature is 160–220 °C, more preferably 180–210 °C; and the reaction time is 6–36 h, more preferably 12–24 h.
10. The application of the stable metallic phase CoS2-MoS2 composite material based on the synergistic regulation of heterostructure and phase engineering as described in claim 1 in rapid lithium storage.