Spherical moolbdenum dioxide-molybdenum disulfide-carbon lithium-oxygen battery cathode catalytic material and preparation method thereof
By preparing a spherical MoO2@MoS2@C structured cathode catalytic material for lithium-oxygen batteries, the problems of insufficient catalytic performance and structural stability of existing catalysts were solved, achieving efficient electrochemical reactions and long cycle life, thus improving the electrochemical performance of lithium-oxygen batteries.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANDONG UNIV
- Filing Date
- 2024-01-11
- Publication Date
- 2026-07-03
AI Technical Summary
Existing lithium-oxygen battery cathode catalysts suffer from poor catalytic performance, insufficient structural stability, low battery specific capacity, and difficulty in ensuring cycle stability, resulting in lithium-oxygen batteries exhibiting high charge-discharge overpotential, poor rate performance, and limited cycle life.
A lithium-oxygen battery cathode catalyst material with a spherical MoO2@MoS2@C structure was constructed by hydrothermal and calcination post-treatment methods. The material's conductivity and catalytic activity were improved by utilizing the homologous heterostructure of MoO2 and MoS2 and the synergistic effect of the carbon layer. The material's monodispersity was achieved by microemulsion method.
It improves the cycle life and specific capacity of lithium-oxygen batteries, exhibiting high charge-discharge specific capacity and good cycle stability. The catalyst material can stably cycle for 64 cycles at a current density of 500 mA g⁻¹, with a charge-discharge specific capacity of 13511.5/18048.0 mAh g⁻¹.
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Figure CN117832519B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of battery cathode material technology, specifically relating to a spherical MoO2@MoS2@C lithium-oxygen battery cathode catalytic material and its preparation method. Background Technology
[0002] Today, the overuse of fossil fuels has led to a potentially irreversible resource crisis and severe environmental pollution. The relatively low energy density of lithium-ion batteries makes it difficult to meet the demands of modern society for high-power applications. Among various emerging energy technologies, rechargeable lithium-oxygen batteries have attracted considerable attention due to their ultra-high theoretical energy density and are considered a very promising battery system.
[0003] However, the kinetic lag in oxygen reduction and evolution reactions during the electrochemical process of lithium-oxygen batteries leads to problems such as high charge-discharge overpotential, poor rate performance, limited cycle life, and low energy density. Therefore, researchers are conducting research on highly efficient cathode catalyst materials to accelerate reaction kinetics and improve the performance of lithium-oxygen batteries.
[0004] Noble metals and their alloys possess excellent electrocatalytic properties; however, their widespread application is limited by high cost and scarce resources. Transition metal oxides and sulfides, due to their diverse structures and abundant abundance, exhibit excellent electrochemical activity and are widely used in the field of electrocatalysis. However, existing lithium-oxygen battery cathode catalysts suffer from the following problems: poor catalytic performance, failing to effectively alleviate the slow kinetics in lithium-oxygen batteries and easily generating side reactions; poor structural stability of the catalyst during long-term cycling, for example, incomplete decomposition of discharge products during cycling, with increasing accumulation of discharge products masking active sites and leading to low battery life; low specific capacity and difficulty in ensuring cycle stability, as the catalyst cannot efficiently catalyze electrochemical reactions, resulting in high overpotentials and electrolyte decomposition. Summary of the Invention
[0005] To address the shortcomings of existing technologies, the present invention aims to provide a spherical MoO2@MoS2@C lithium-oxygen battery cathode catalyst material, its preparation method, and a lithium-oxygen battery thereof.
[0006] To achieve the above objectives, the present invention is implemented through the following technical solution:
[0007] In a first aspect, the present invention provides a method for preparing a spherical MoO2@MoS2@C lithium-oxygen battery cathode catalyst material, comprising the following steps:
[0008] Thiourea, ethylene glycol, n-butanol, and a volatile acid solution were added to a mixed solution of molybdenum source and hexadecyltrimethylammonium bromide to obtain a mixed solution.
[0009] The resulting mixed solution was subjected to a hydrothermal reaction to obtain the precursor;
[0010] The prepared precursor is separated, dried, and calcined to obtain the final product.
[0011] The resulting MoO2@MoS2 is a homologous heterostructure. Due to the difference in Fermi levels between the different materials, electrons can migrate from the high Fermi level region to the low Fermi level region through the heterostructure interface, thereby improving the conductivity of the material. The synergistic effect between the highly conductive MoO2 and the highly catalytically active MoS2 can also promote the electrochemical reaction process, thereby improving the performance of lithium-oxygen batteries. The spherical structure is composed of stacked nanosheets, with abundant space on the surface for storing discharge products, which also facilitates electrolyte wetting and mass transfer processes, thus improving the cycle life and specific capacity of lithium-oxygen batteries.
[0012] Although MoO2 also has good electrical conductivity, the structural stability of the material is mainly provided by the carbon layer. In addition, the carbon layer can also improve the conductivity of the material. The improved conductivity of the material can also reduce the amount of conductive agent added during the preparation of the slurry, thus better leveraging the catalytic ability of the catalyst.
[0013] The method used in this invention is the microemulsion method, the purpose of which is to improve the monodispersity of the material and obtain well-dispersed microspheres.
[0014] The purpose of adding hydrochloric acid is to adjust the pH of the solution to a slightly acidic level.
[0015] In some embodiments, the concentration of the molybdenum source in the mixed solution is 3-5 mmol / L, the concentration of hexadecyltrimethylammonium bromide is 40-60 mmol / L, the concentration of thiourea is 40-70 mmol / L, the concentration of ethylene glycol is 15-20%, the concentration of n-butanol is 30-40%, and the concentration of the volatile acid solution is 0.1-0.5%, where % is a mass percentage.
[0016] Preferably, in the mixed solution, the concentration of the molybdenum source is 3.33 mmol / L, the concentration of hexadecyltrimethylammonium bromide is 50 mmol / L, the concentration of thiourea is 41.67-66.67 mmol / L, the concentration of ethylene glycol is 16.67%, the concentration of n-butanol is 33.33%, and the concentration of the volatile acid solution is 0.3%.
[0017] In some embodiments, hydrochloric acid is selected as the volatile acid solution.
[0018] In some embodiments, the hydrothermal reaction temperature is 200-240°C, and the hydrothermal reaction time is 20-24 hours.
[0019] In some embodiments, the separation is a centrifugal separation step, and the centrifugal speed is 4000-6000 rpm. -1 .
[0020] Preferably, the process also includes a step of repeatedly washing the precursor obtained by centrifugation with alcohol and deionized water.
[0021] In some embodiments, the drying temperature is 40-60°C and the drying time is 10-14 hours.
[0022] In some embodiments, the calcination temperature is 700-900℃ and the calcination time is 2-3h.
[0023] Preferably, the heating rate during calcination is 3-4°C / min. -1 .
[0024] Secondly, the present invention provides a spherical MoO2@MoS2@C lithium-oxygen battery cathode catalyst material, which is prepared by the aforementioned preparation method.
[0025] Thirdly, the present invention provides a lithium-oxygen battery, wherein the positive electrode catalyst material is the spherical MoO2@MoS2@C lithium-oxygen battery positive electrode catalyst material.
[0026] The beneficial effects achieved by one or more embodiments of the present invention described above are as follows:
[0027] (1) The present invention uses a simple hydrothermal and calcination post-treatment method to construct a spherical MoO2@MoS2@C cathode catalyst material. This material is made of stacked nanosheets. The surface of the sphere has abundant space for storing discharge products, which is beneficial to the decomposition of discharge products and can also promote the wetting and mass transfer process of electrolyte.
[0028] (2) MoO2 has good electrical conductivity and good catalytic activity. When combined with MoS2, which has excellent catalytic activity, they form a homologous heterostructure, which can synergistically accelerate the reaction kinetics of lithium-oxygen batteries. The MoS2 crystal faces that are mainly exposed in the material can provide more catalytic active sites, thereby improving the catalytic performance of the material. The carbon layer structure can also enhance the structural stability of the material during long-cycle processes and extend the battery life.
[0029] (3) The morphology and electrochemical performance of the cathode catalyst material prepared by this invention exhibit good reproducibility, demonstrating high specific capacity and good cycle stability. In one specific embodiment, the described catalyst material at 500 mAg... -1 Current density and cutoff specific capacity are 1000 mAh g. -1 Under certain conditions, it can stably cycle for 64 times. At 500 mAg... -1Under current density and a voltage window of 2.35-4.50V, it can reach 13511.5 / 18048.0 mAh g. -1 The charge / discharge specific capacity. Attached Figure Description
[0030] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.
[0031] Figure 1 This is a SEM image of MoO2@MoS2@C synthesized by the method of this invention;
[0032] Figure 2 This is a particle size distribution diagram of MoO2@MoS2@C synthesized by the method of this invention;
[0033] Figure 3 The present invention provides an EDS-Mapping map of MoO2@MoS2@C synthesized by the method of the present invention, wherein (a) is the SEM image of MoO2@MoS2@C, (b) is a summary of the EDS-Mapping map of each element of MoO2@MoS2@C, (c) is the Mapping map of the Mo element, (d) is the Mapping map of the O element, (e) is the Mapping map of the S element, and (f) is the Mapping map of the C element.
[0034] Figure 4 These are TEM images of MoO2@MoS2@C synthesized by the method of this invention;
[0035] Figure 5 The XRD pattern of MoO2@MoS2@C synthesized by the method of this invention;
[0036] Figure 6 This is a cycle performance diagram of MoO2@MoS2@C synthesized by the method of this invention for lithium-oxygen battery testing, where the current density is 500 mAg. -1 The cutoff specific capacity is 1000mAh g. -1 ;
[0037] Figure 7 This is a graph showing the first charge-discharge performance of MoO2@MoS2@C synthesized by the method of this invention for use in lithium-oxygen batteries, with a current density of 500 mAg. -1 The voltage window is 2.35-4.50V.
[0038] Figure 8 This is a rate performance graph of MoO2@MoS2@C synthesized by the method of this invention for lithium-oxygen battery testing, where the current density is 200 mAg. -1 400mAg-1 600mAg -1 800mAg -1 1000mA g -1 and 200mAg -1 . Detailed Implementation
[0039] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.
[0040] The present invention will be further described below with reference to the embodiments.
[0041] Example 1
[0042] Spherical MoO2@MoS2@C is prepared through the following steps:
[0043] (1) Dissolve 1 mmol sodium molybdate and 15 mmol CTAB in 300 mL of deionized water and stir to obtain a homogeneous solution. Then add 15 mmol thiourea, 50 mL ethylene glycol, 100 mL n-butanol and 1 mL hydrochloric acid to the solution and stir for 2 h to obtain a white solution.
[0044] (2) The white solution obtained in step (1) was transferred into a hydrothermal reactor with a Teflon liner and hydrothermally reacted at 220°C for 24 hours. After cooling to room temperature, it was washed and centrifuged, and then transferred to a vacuum drying oven and dried at 60°C overnight to obtain the precursor.
[0045] (3) Transfer the precursor powder obtained in step (2) into a tube furnace under a protective atmosphere and heat it at 3°C for 3 minutes. -1 By adjusting the heating rate, spherical MoO2@MoS2@C was obtained by holding at 800℃ for 3 hours.
[0046] Figure 1 The image shows a SEM image of MoO2@MoS2@C synthesized by the method of this invention, exhibiting a typical spherical morphology. Figure 2 For based on Figure 1 The resulting particle size analysis chart shows that the maximum particle size is 0.64 μm and the minimum particle size is 0.43 μm. Figure 3 The EDS-Mapping pattern of MoO2@MoS2@C shows that the elements are uniformly distributed on the material surface. Figure 4 The TEM image of MoO2@MoS2@C clearly shows that the spherical structure is composed of nanosheets stacked together. Figure 5The XRD pattern of MoO2@MoS2@C is shown. Its diffraction data are consistent with those of MoO2 (JCPDS#32-0671) and MoS2 (JCPDS#37-1492), indicating that the material is a two homologous heterostructure.
[0047] The MoO2@MoS2@C catalyst obtained in Example 1 was prepared into an electrode according to the following method:
[0048] MoO2@MoS2@C catalyst, conductive carbon KB, and binder PTFE were weighed in a 7:2:1 mass ratio and dissolved in an appropriate amount of isopropanol, then ultrasonically dissolved to obtain an electrode material slurry. The slurry was then uniformly sprayed onto a 19mm diameter circular carbon paper using a spraying machine and vacuum dried overnight at 120℃ to obtain the positive electrode sheet for the lithium-oxygen battery. Electrochemical testing of the lithium-oxygen battery used a 2032-type button cell with a perforated positive electrode shell, a lithium metal sheet as the negative electrode, 1M LiTFSI / TEGDME as the electrolyte, and Whatman GF / D glass fiber as the separator. Battery assembly was performed in an argon-filled glove box, and charge-discharge tests were conducted at room temperature in a pure oxygen atmosphere using a LAND CT 2001A multichannel battery tester.
[0049] Figure 6 This is a cycle performance diagram of the MoO2@MoS2@C electrode material prepared in this invention for use in a lithium-oxygen battery, with a test current density of 500 mAg. -1 The cutoff specific capacity is 1000mAh g. -1 It can achieve a cycle life of 64 revolutions.
[0050] Figure 7 This is a graph showing the first charge-discharge performance of the MoO2@MoS2@C electrode material prepared in this invention in a lithium-oxygen battery test, with a test current density of 500 mAg. -1 Charge / discharge specific capacity: 13511 / 18048mAhg -1 .
[0051] Figure 8 The graph shows the rate performance of the MoO2@MoS2@C electrode material prepared in this invention in a lithium-oxygen battery test. The results show that the charge / discharge terminal voltage changes little with the increase of current density, and when it returns to the initial current density, the terminal voltage can almost return to the value measured at the initial current density, indicating that the catalytic material has good rate performance.
[0052] Example 2
[0053] Spherical MoO2@MoS2@C is prepared through the following steps:
[0054] (1) Dissolve 1 mmol sodium molybdate and 15 mmol CTAB in 300 mL of deionized water and stir to obtain a homogeneous solution. Then add 15 mmol thiourea, 50 mL ethylene glycol, 100 mL n-butanol and 1 mL hydrochloric acid to the solution and stir for 2 h to obtain a white solution.
[0055] (2) The white solution obtained in step (1) was transferred into a hydrothermal reactor with a Teflon liner and hydrothermally reacted at 210°C for 24 hours. After cooling to room temperature, it was washed and centrifuged, and then transferred to a vacuum drying oven and dried at 60°C overnight to obtain the precursor.
[0056] (3) Transfer the precursor powder obtained in step (2) into a tube furnace under a protective atmosphere and heat it at 3°C for 3 minutes. -1 By adjusting the heating rate, spherical MoO2@MoS2@C was obtained by holding at 800℃ for 3 hours.
[0057] Example 3
[0058] Spherical MoO2@MoS2@C is prepared through the following steps:
[0059] (1) Dissolve 1 mmol sodium molybdate and 15 mmol CTAB in 300 mL of deionized water and stir to obtain a homogeneous solution. Then add 15 mmol thiourea, 50 mL ethylene glycol, 100 mL n-butanol and 1 mL hydrochloric acid to the solution and stir for 2 h to obtain a white solution.
[0060] (2) The white solution obtained in step (1) was transferred into a hydrothermal reactor with a Teflon liner and hydrothermally reacted at 230°C for 24 hours. After cooling to room temperature, it was washed and centrifuged, and then transferred to a vacuum drying oven and dried at 60°C overnight to obtain the precursor.
[0061] (3) Transfer the precursor powder obtained in step (2) into a tube furnace under a protective atmosphere and heat it at 3°C for 3 minutes. -1 By adjusting the heating rate, spherical MoO2@MoS2@C was obtained by holding at 800℃ for 3 hours.
[0062] Example 4
[0063] Spherical MoO2@MoS2@C is prepared through the following steps:
[0064] (1) Dissolve 1 mmol sodium molybdate and 15 mmol CTAB in 300 mL of deionized water and stir to obtain a homogeneous solution. Then add 15 mmol thiourea, 50 mL ethylene glycol, 100 mL n-butanol and 1 mL hydrochloric acid to the solution and stir for 2 h to obtain a white solution.
[0065] (2) The white solution obtained in step (1) was transferred into a hydrothermal reactor with a Teflon liner and hydrothermally reacted at 240°C for 24 hours. After cooling to room temperature, it was washed and centrifuged, and then transferred to a vacuum drying oven and dried at 60°C overnight to obtain the precursor.
[0066] (3) Transfer the precursor powder obtained in step (2) into a tube furnace under a protective atmosphere and heat it at 3°C for 3 minutes. -1 By adjusting the heating rate, spherical MoO2@MoS2@C was obtained by holding at 800℃ for 3 hours.
[0067] Example 5
[0068] Spherical MoO2@MoS2@C is prepared through the following steps:
[0069] (1) Dissolve 1 mmol sodium molybdate and 15 mmol CTAB in 300 mL of deionized water and stir to obtain a homogeneous solution. Then add 15 mmol thiourea, 50 mL ethylene glycol, 100 mL n-butanol and 1 mL hydrochloric acid to the solution and stir for 2 h to obtain a white solution.
[0070] (2) The white solution obtained in step (1) was transferred into a hydrothermal reactor with a Teflon liner and hydrothermally reacted at 220°C for 24 hours. After cooling to room temperature, it was washed and centrifuged, and then transferred to a vacuum drying oven and dried at 60°C overnight to obtain the precursor.
[0071] (3) Transfer the precursor powder obtained in step (2) into a tube furnace under a protective atmosphere and heat it at 3°C for 3 minutes. -1 By adjusting the heating rate, spherical MoO2@MoS2@C was obtained by holding at 700℃ for 3 hours.
[0072] Example 6
[0073] Spherical MoO2@MoS2@C is prepared through the following steps:
[0074] (1) Dissolve 1 mmol sodium molybdate and 15 mmol CTAB in 300 mL of deionized water and stir to obtain a homogeneous solution. Then add 15 mmol thiourea, 50 mL ethylene glycol, 100 mL n-butanol and 1 mL hydrochloric acid to the solution and stir for 2 h to obtain a white solution.
[0075] (2) The white solution obtained in step (1) was transferred into a hydrothermal reactor with a Teflon liner and hydrothermally reacted at 220°C for 24 hours. After cooling to room temperature, it was washed and centrifuged, and then transferred to a vacuum drying oven and dried at 60°C overnight to obtain the precursor.
[0076] (3) Transfer the precursor powder obtained in step (2) into a tube furnace under a protective atmosphere and heat it at 3°C for 3 minutes. -1By adjusting the heating rate, spherical MoO2@MoS2@C was obtained by holding at 900℃ for 3 hours.
[0077] Example 7
[0078] Spherical MoO2@MoS2@C is prepared through the following steps:
[0079] (1) Dissolve 1 mmol sodium molybdate and 15 mmol CTAB in 300 mL of deionized water and stir to obtain a homogeneous solution. Then add 12.5 mmol thiourea, 50 mL ethylene glycol, 100 mL n-butanol and 1 mL hydrochloric acid to the solution and stir for 2 h to obtain a white solution.
[0080] (2) The white solution obtained in step (1) was transferred into a hydrothermal reactor with a Teflon liner and hydrothermally reacted at 220°C for 24 hours. After cooling to room temperature, it was washed and centrifuged, and then transferred to a vacuum drying oven and dried at 60°C overnight to obtain the precursor.
[0081] (3) Transfer the precursor powder obtained in step (2) into a tube furnace under a protective atmosphere and heat it at 3°C for 3 minutes. -1 By adjusting the heating rate, spherical MoO2@MoS2@C was obtained by holding at 800℃ for 3 hours.
[0082] Example 8
[0083] Spherical MoO2@MoS2@C is prepared through the following steps:
[0084] (1) Dissolve 1 mmol sodium molybdate and 15 mmol CTAB in 300 mL of deionized water and stir to obtain a homogeneous solution. Then add 17.5 mmol thiourea, 50 mL ethylene glycol, 100 mL n-butanol and 1 mL hydrochloric acid to the solution and stir for 2 h to obtain a white solution.
[0085] (2) The white solution obtained in step (1) was transferred into a hydrothermal reactor with a Teflon liner and hydrothermally reacted at 220°C for 24 hours. After cooling to room temperature, it was washed and centrifuged, and then transferred to a vacuum drying oven and dried at 60°C overnight to obtain the precursor.
[0086] (3) Transfer the precursor powder obtained in step (2) into a tube furnace under a protective atmosphere and heat it at 3°C for 3 minutes. -1 By adjusting the heating rate, spherical MoO2@MoS2@C was obtained by holding at 800℃ for 3 hours.
[0087] Example 9
[0088] Spherical MoO2@MoS2@C is prepared through the following steps:
[0089] (1) Dissolve 1 mmol sodium molybdate and 15 mmol CTAB in 300 mL of deionized water and stir to obtain a homogeneous solution. Then add 20 mmol thiourea, 50 mL ethylene glycol, 100 mL n-butanol and 1 mL hydrochloric acid to the solution and stir for 2 h to obtain a white solution.
[0090] (2) The white solution obtained in step (1) was transferred into a hydrothermal reactor with a Teflon liner and hydrothermally reacted at 220°C for 24 hours. After cooling to room temperature, it was washed and centrifuged, and then transferred to a vacuum drying oven and dried at 60°C overnight to obtain the precursor.
[0091] (3) Transfer the precursor powder obtained in step (2) into a tube furnace under a protective atmosphere and heat it at 3°C for 3 minutes. -1 By adjusting the heating rate, spherical MoO2@MoS2@C was obtained by holding at 800℃ for 3 hours.
[0092] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for preparing a spherical MoO2@MoS2@C lithium-oxygen battery cathode catalyst, characterized in that: Includes the following steps: Thiourea, ethylene glycol, n-butanol, and a volatile acid solution were added to a mixed solution of molybdenum source and hexadecyltrimethylammonium bromide to obtain a mixed solution. The resulting mixed solution was subjected to a hydrothermal reaction to obtain the precursor; The prepared precursor is separated, dried, and calcined to obtain the final product.
2. The method of claim 1, wherein: The hydrothermal reaction temperature is 200-240℃, and the hydrothermal reaction time is 20-24 h.
3. The method of claim 1, wherein: The separation is a centrifugal separation step, with a centrifugal rotation speed of 4000-6000 rpm.
4. The method of claim 1, wherein: In the mixed solution, the concentration of molybdenum source is 3-5 mmol / L, the concentration of hexadecyltrimethylammonium bromide is 40-60 mmol / L, the concentration of thiourea is 40-70 mmol / L, the concentration of ethylene glycol is 15-20%, the concentration of n-butanol is 30-40%, and the concentration of volatile acid solution is 0.1-0.5%, where % is by mass percentage.
5. The method of claim 4, wherein: In the mixed solution, the concentration of molybdenum source is 3.33 mmol / L, the concentration of hexadecyltrimethylammonium bromide is 50 mmol / L, the concentration of thiourea is 41.67-66.67 mmol / L, the concentration of ethylene glycol is 16.67%, the concentration of n-butanol is 33.33%, and the concentration of volatile acid solution is 0.3%.
6. The preparation method according to claim 4, characterized in that, The volatile acid is hydrochloric acid.
7. The method of claim 1, wherein: It also includes the step of repeatedly washing the precursor obtained by centrifugation with alcohol and deionized water.
8. The method of claim 1, wherein: The drying temperature is 40-60℃, and the drying time is 10-14h.
9. The method of claim 1, wherein: The calcination temperature is 700-900℃, and the calcination time is 2-3 h.
10. The method of claim 1, wherein: The temperature increase rate of the calcination is 3-4 °C min -1 .
11. A spherical MoO2@MoS2@C lithium-oxygen battery cathode catalyst material, characterized in that: Prepared by any of the preparation methods described in claims 1-10.
12. A lithium-oxygen battery, characterized by: Its positive electrode catalyst material is the spherical MoO2@MoS2@C lithium-oxygen battery positive electrode catalyst material as described in claim 11.