Zinc ion pre-intercalation type molybdenum trioxide electrode material, preparation method and application thereof

Abstract

The application discloses a zinc ion pre-embedded molybdenum trioxide electrode material, a preparation method and application thereof. The method is characterized in that alpha-MoO3 is placed in a tartaric acid / zinc chloride solution for hydrothermal treatment, so that part of zinc ions enter the interlayer of molybdenum trioxide to obtain the zinc ion pre-embedded molybdenum trioxide with interlayer. x When the molybdenum trioxide is used as a positive electrode, the problem of a large capacity attenuation of an alpha-MoO3 lithium ion battery in an early stage is effectively solved, the interface impedance is reduced, the electronic conductivity of the electrode material is increased, and the capacity of the assembled lithium ion battery in a stable state is increased by more than 50%.

Description

Technical Field

[0001] This invention belongs to the field of electrode material technology, and relates to a zinc ion pre-intercalated molybdenum trioxide electrode material (Zn x MoO3), its preparation method and its application in lithium-ion batteries. Background Technology

[0002] Lithium-ion batteries, as energy storage devices, have prominent applications in mobile electronic devices and electric vehicles due to their high energy density and relatively long lifespan. However, currently used cobalt-containing cathode materials suffer from problems such as high cost, environmental unfriendliness, and toxicity, thus necessitating the search for alternative materials.

[0003] Molybdenum trioxide (MoO3) possesses a unique layered structure and excellent two-electron redox capability, making it a promising candidate for lithium-ion battery cathode materials. Its theoretical energy density reaches 930 Wh / kg, offering a significant commercial advantage over LiCoO2 and LiFePO4 (500–600 Wh / kg), and it is also environmentally friendly and abundant. However, its low conductivity, slow reaction kinetics, and large volume expansion during charge and discharge hinder its widespread application. Furthermore, α-MoO3 exhibits low conductivity during the first discharge cycle at 2.7V (vs. Li / Li). + Around 100°C, irreversible phase transitions occur due to the irreversible insertion of lithium ions, causing rapid capacity decay and affecting its cycle stability.

[0004] To address the aforementioned issues, a traditional approach is to improve early-stage battery degradation through pre-intercalation of metal cations, such as pre-intercalation of Na. + This method suppresses the irreversible phase transition during the first discharge cycle and expands the interlayer spacing, thereby effectively improving the electrochemical performance of MoO3 batteries. After 150 cycles, the capacity retention rate increased from 26% to 53%, but the improvement was limited. (Liqiang Mai: Inhibiting effect of Na...) + (Pre-intercalation in MoO3 nanobelts with enhanced electrochemical performance). Another approach is to introduce oxygen vacancies between the material layers. The introduction of oxygen vacancies can improve the conductivity of transition metal oxides and expand the interlayer spacing, allowing Li... +It enables better interlayer embedding / extraction, improving the structure and reaction kinetics of α-MoO3 (Hyung-Seok Kim: Oxygen vacancies enhance pseudocapacitive charge storage properties of MoO). 3-x In addition, another approach is to improve electronic conductivity by forming a MoO3 and MoO2 heterojunction, and the heterojunction interface can form an internal driving force to enhance ion / electron transfer, making it suitable as an anode material (Junnan Hao: Heterostructure Manipulation via in Situ Localized Phase Transformation for High-Rate and Highly Durable Lithium Ion Storage). However, the conditions for introducing oxygen vacancies are quite demanding, and the MoO2-based heterojunction material is not suitable for the battery cathode. Furthermore, previous cation pre-intercalation work has not completely solved the first-cycle irreversible phase transition of MoO3. Summary of the Invention

[0005] The purpose of this invention is to provide a zinc ion pre-intercalated molybdenum trioxide electrode material (Zn x MoO3), its preparation method and its application in lithium-ion batteries.

[0006] The technical solution for achieving the objective of this invention is as follows:

[0007] A method for preparing zinc ion pre-intercalated molybdenum trioxide involves hydrothermal reduction of α-MoO3 to obtain the heterojunction electrode material Zn. x MoO3, including the following steps:

[0008] α-MoO3 powder and tartaric acid / zinc chloride solution were mixed evenly, and then a hydrothermal reaction was carried out at 80-100℃ in air atmosphere. After the reaction was completed, zinc ion pre-intercalated molybdenum trioxide was obtained, wherein the mass ratio of tartaric acid to zinc chloride was 1:2 to 2:1.

[0009] Preferably, the mass-to-volume ratio of α-MoO3 powder to tartaric acid / zinc chloride solution is 15:1, g:L.

[0010] Preferably, in the tartaric acid / zinc chloride solution, the mass ratio of tartaric acid to zinc chloride is 1:1.

[0011] Preferably, in the tartaric acid / zinc chloride solution, the concentration of zinc chloride is 15–45 g / L.

[0012] Preferably, the hydrothermal reaction time is 12–20 h.

[0013] The present invention also provides zinc ion pre-intercalated molybdenum trioxide prepared by the above preparation method.

[0014] Furthermore, the present invention provides a zinc ion pre-intercalated molybdenum trioxide cathode material, which is prepared by mixing zinc ion pre-intercalated molybdenum trioxide powder, a conductive agent and a binder, and then preparing it through a wet film process.

[0015] Preferably, the mass ratio of zinc ion pre-intercalated molybdenum trioxide powder, conductive agent, and binder is 7:2:1.

[0016] In this invention, the conductive agent is a conductive agent conventionally used in the art, such as Super-P.

[0017] In this invention, the adhesive is a conventional adhesive used in the art, such as polyvinylidene fluoride.

[0018] Furthermore, the present invention provides the application of the above-mentioned zinc ion pre-intercalated molybdenum trioxide cathode material in lithium-ion batteries.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] This invention, based on high-capacity α-MoO3 electrode materials, stabilizes the interlayer structure during lithium-ion insertion and extraction by pre-intercalating zinc ions. Zinc ions act as "pillars" within the MoO3 interlayers, thus stabilizing the material's structure. Furthermore, the combined effect of oxygen vacancies and zinc ions intercalating within the layers expands the interlayer spacing of the (0k0) crystal planes of the MoO3 material, enabling lithium-ion intercalation and deintercalation to proceed smoothly during battery charging and discharging. + It can better insert / extract materials, and due to the generation of zinc ions and pentavalent molybdenum ions, the material exhibits an uneven charge distribution, forming an internal electric field that generates an internal driving force to enhance charge transfer capability. This improves the problem of significant capacity decay in the early stage. Compared with MoO3 electrode materials with pre-inserted group 1 metal ions, it further improves the reversible capacity, rate performance and cycle stability of the material. Attached Figure Description

[0021] Figure 1 The image shows the XRD pattern of α-MoO3 powder prepared according to the reference.

[0022] Figure 2 This is a SEM image of α-MoO3 powder prepared according to the reference.

[0023] Figure 3 This is a zinc ion pre-intercalated Zn prepared in Example 1 with a mass ratio of tartaric acid and zinc chloride of 1:1. x XRD pattern of MoO3.

[0024] Figure 4 This is a zinc ion pre-intercalated Zn prepared in Example 1 with a mass ratio of tartaric acid and zinc chloride of 1:1. x SEM image of MoO3 powder.

[0025] Figure 5 This is a zinc ion pre-intercalated Zn prepared in Example 1 with a mass ratio of tartaric acid and zinc chloride of 1:1. x XRD pattern of MoO3 powder compared with standard card No. 76-1003, where the (020) main peak on the standard card is located at 12.8 degrees.

[0026] Figure 6 This is a zinc ion pre-intercalated Zn prepared in Example 1 with a mass ratio of tartaric acid and zinc chloride of 1:1. x XRD pattern of MoO3 powder compared with standard card No. 76-1003, where the (040) main peak on the standard card is located at 25.7 degrees.

[0027] Figure 7 This is a zinc ion pre-intercalated Zn prepared in Example 1 with a mass ratio of tartaric acid and zinc chloride of 1:1. x XRD pattern of MoO3 powder compared with standard card No. 76-1003, where the (060) main peak on the standard card is located at 38.9 degrees.

[0028] Figure 8 This is a zinc ion pre-intercalated Zn prepared in Example 2 with a tartaric acid to zinc chloride mass ratio of 2:1. x XRD pattern of MoO3 powder.

[0029] Figure 9 This is a zinc ion pre-intercalated Zn prepared in Example 2 with a tartaric acid to zinc chloride mass ratio of 2:1. x SEM image of MoO3 powder.

[0030] Figure 10 This is a zinc ion pre-intercalated Zn prepared in Example 3 with a tartaric acid to zinc chloride mass ratio of 1:2. x XRD pattern of MoO3 powder.

[0031] Figure 11 This is a zinc ion pre-intercalated Zn prepared in Example 3 with a tartaric acid to zinc chloride mass ratio of 1:2. x SEM image of MoO3 powder.

[0032] Figure 12 This is a charge-discharge cycle diagram of the MoO3 electrode material without hydrothermal treatment at a current density of 200 mA / g in the potential range of 1.5-3.5V.

[0033] Figure 13 The Zn prepared in Example 1 x Charge-discharge cycle diagram of MoO3 electrode material at a current density of 200 mA / g in the potential range of 1.5-3.5V.

[0034] Figure 14 The Zn prepared in Example 2 x Charge-discharge cycle diagram of MoO3 electrode material at a current density of 200 mA / g in the potential range of 1.5-3.5V.

[0035] Figure 15 This is a charge-discharge cycle diagram of the α-MoO3 electrode material prepared in Example 3 at a current density of 200 mA / g in the potential range of 1.5-3.5V.

[0036] Figure 16 Zn prepared in Comparative Example 1 x Charge-discharge cycle diagram of MoO3 electrode material at a current density of 200 mA / g in the potential range of 1.5-3.5V. Detailed Implementation

[0037] The preparation of α-MoO3 powder is referenced in [Minghao Yu: Interlayer gap widened α-phase molybdenum trioxide as high-rate anodes for dual-ion intercalation energy storage devices], and the specific method is as follows:

[0038] 1.3g of (NH4)6Mo7O 24 • 4H2O was dissolved in 36 mL of deionized water, and then 6 mL of concentrated nitric acid was added and stirred evenly. The resulting solution was transferred to a 50 mL hydrothermal reactor and subjected to a hydrothermal reaction at 180 °C for 12 h in a forced-air oven. After the reaction was completed, the reactor was allowed to cool completely to room temperature, the supernatant was discarded, and the obtained milky white viscous substance was washed with deionized water and ethanol three times and centrifuged. Finally, the centrifuged product was dried for 12 h to obtain dry α-MoO3 powder.

[0039] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings.

[0040] Example 1

[0041] (1)Zn xPreparation of MoO3: 2g of zinc chloride powder and 2g of tartaric acid powder were dissolved together in 70ml of deionized water to prepare a zinc chloride / tartaric acid solution. 800mg of α-MoO3 powder was mixed thoroughly with the zinc chloride / tartaric acid solution and then placed in a 100ml tetrachlorofluoroethylene hydrothermal tank. The mixture was subjected to a hydrothermal reaction at 80℃ for 20 hours. After the reaction was completed, the hydrothermal tank was cooled to room temperature, and the obtained Zn was removed. x MoO3 powder.

[0042] (2) Preparation of positive electrode material: The active material Zn x MoO3 powder, conductive agent Super-P, and binder polyvinylidene fluoride were mixed in a mass ratio of 7:2:1 and ground for half an hour until the particles were uniform. The resulting powder mixture was dissolved in N-methylpyrrolidone solvent and stirred for 12 hours. Then, it was coated onto stainless steel foil using a wet film preparation process. Subsequently, it was dried in a vacuum oven at 80°C for 12 hours and cut into pieces using a 12mm diameter cutting machine to produce Zn. x MoO3 electrode.

[0043] With Zn x A lithium-ion battery was assembled using a MoO3 electrode as the positive electrode, lithium metal as the negative electrode, and Celegard 2400 as the separator. Its performance was tested using a Newway battery testing device.

[0044] Example 2

[0045] This embodiment is basically the same as Example 1, except that the mass ratio of tartaric acid to zinc chloride is 2:1.

[0046] Example 3

[0047] This embodiment is basically the same as Example 1, except that the mass ratio of tartaric acid to zinc chloride is 1:2.

[0048] Example 4

[0049] This embodiment is basically the same as Embodiment 1, except that the hydrothermal reaction time is 12 hours.

[0050] Comparative Example 1

[0051] This embodiment is basically the same as Embodiment 1, except that the hydrothermal reaction temperature is 60°C.

[0052] Figure 1 The XRD pattern of the prepared α-MoO3 is in perfect agreement with standard card No. 76-1003 in the database, indicating that the crystal phase composition of the product is α-MoO3. In addition, the sharp peak shape and high intensity of the visible X-ray diffraction peaks indicate that the material has strong crystallinity.

[0053] Figure 2The image shows a SEM image of the prepared α-MoO3, which exhibits a nanorod morphology and is composed of countless disordered nanorods.

[0054] Figure 3 Zinc ion pre-intercalated Zn prepared in Example 1 x The XRD pattern of MoO3 matches the standard card No. 76-1003 in the database, indicating that the crystal phase of the product remains molybdenum trioxide. In addition, the sharp peak shape and high intensity of the visible X-ray diffraction peaks indicate that the material has a high degree of crystallinity.

[0055] Figure 4 Zn prepared in Example 1 x The SEM image of MoO3 shows the morphology of nanorods, indicating that the hydrothermal reaction did not change the nanowire morphology of molybdenum trioxide.

[0056] Figure 5 Zn prepared in Example 1 x The XRD pattern of MoO3, compared with the standard card No. 76-1003 in the database, shows a negative shift in the diffraction peak angle at 12.8 degrees (020), indicating that the zinc ion pre-intercalation increases the interlayer spacing.

[0057] Figure 6 Zn prepared in Example 1 x The XRD pattern of MoO3, compared with the standard card No. 76-1003 in the database, shows a negative shift in the angle of the (040) main diffraction peak at 25.7 degrees, indicating that the zinc ion pre-intercalation increases the interlayer spacing.

[0058] Figure 7 Zn prepared in Example 1 x The XRD pattern of MoO3, compared with the standard card No. 76-1003 in the database, shows a negative shift in the angle of the (060) main diffraction peak at 38.9 degrees, indicating that the zinc ion pre-intercalation increases the interlayer spacing.

[0059] Figure 8 Zinc ion pre-intercalated Zn prepared in Example 2 x The XRD pattern of MoO3 matches the standard card No. 76-1003 in the database, indicating that the crystal phase of the product remains molybdenum trioxide. In addition, the sharp peak shape and high intensity of the visible X-ray diffraction peaks indicate that the material has a high degree of crystallinity.

[0060] Figure 9 Zn prepared in Example 2 x The SEM image of MoO3 shows the morphology of nanorods, indicating that hydrothermal treatment under these conditions did not change the nanowire morphology of molybdenum trioxide.

[0061] Figure 10Zinc ion pre-intercalated Zn prepared in Example 3 x The XRD pattern of MoO3 matches the standard card No. 76-1003 in the database, indicating that the crystal phase of the product remains molybdenum trioxide. In addition, the sharp peak shape and high intensity of the visible X-ray diffraction peaks indicate that the material has a high degree of crystallinity.

[0062] Figure 11 Zn prepared in Example 3 x The SEM image of MoO3 shows the morphology of nanorods, but the nanowire structure is somewhat damaged, indicating that at this ratio, increasing the zinc chloride concentration will lead to the collapse of the nanowire structure.

[0063] Figure 12 The charge-discharge cycle diagram of the untreated MoO3 electrode material at a current density of 200 mA / g in the potential range of 1.5-3.5V shows that the initial capacity of the material is 233 mAh / g. However, the capacity decay of the material is relatively severe in the early stage, and the capacity retention rate is only 52% after 50 cycles.

[0064] Figure 13 Zinc ion pre-intercalated Zn prepared in Example 1 x The charge-discharge cycle diagram of the MoO3 electrode material at a current density of 200 mA / g in the potential range of 1.5-3.5 voltammetry shows that the initial capacity of the material is 242 mAh / g, and the capacity retention rate after 50 cycles is 96%, which is higher than that in the reference. At the same time, the rapid capacity decay in the early stage of the material is also solved.

[0065] Figure 14 Zinc ion pre-intercalated Zn prepared in Example 2 x The charge-discharge cycle diagram of the MoO3 electrode material at a current density of 200 mA / g in the potential range of 1.5-3.5 voltammetry shows that the initial capacity of the material is 235 mAh / g, and the capacity retention rate after 50 cycles is 63%, indicating that the preparation method has the feasibility of improving battery performance.

[0066] Figure 15 Zinc ion pre-intercalated Zn prepared in Example 3 x The charge-discharge cycle diagram of the MoO3 electrode material at a current density of 200 mA / g in the potential range of 1.5-3.5 shows that the initial capacity of the material is 244 mAh / g, and the capacity retention rate after 50 cycles is 75%, indicating that the preparation method has the feasibility of improving battery performance.

[0067] Figure 16 Zinc ion pre-intercalated Zn prepared for Comparative Example 1 xThe charge-discharge cycle diagram of the MoO3 electrode material at a current density of 200 mA / g in the potential range of 1.5-3.5 voltammetry shows that the initial capacity of the material is 226 mAh / g, and the capacity retention rate after 50 cycles is 63%, indicating that the preparation method has the feasibility of improving battery performance.

Claims

1. A method for producing zinc ion pre-embedded molybdenum trioxide, characterized by, The method comprises the following steps: The alpha-MoO3 powder and the tartaric acid / zinc chloride solution are uniformly mixed, and then a hydrothermal reaction is carried out at 80-100 DEG C under an air atmosphere; after the reaction is completed, zinc ion pre-embedded molybdenum trioxide is obtained, wherein the mass ratio of the tartaric acid to the zinc chloride is 1:

1.

2. The production method according to claim 1, characterized by, The mass-volume ratio of the alpha-MoO3 powder to the tartaric acid / zinc chloride solution is 15:1, g:L.

3. The production method according to claim 1, characterized by, In the tartaric acid / zinc chloride solution, the concentration of the zinc chloride is 15-45 g / L.

4. The production method according to claim 1, characterized by, The hydrothermal reaction time is 12-20 h.

5. The zinc ion pre-embedded molybdenum trioxide prepared by the preparation method according to any one of claims 1-4.

6. The zinc ion pre-intercalation type molybdenum trioxide cathode material according to claim 5, characterized in that, The zinc ion pre-embedded molybdenum trioxide is prepared by mixing the zinc ion pre-embedded molybdenum trioxide powder, a conductive agent and a binder through a wet film preparation process.

7. The zinc ion pre-intercalation type molybdenum trioxide cathode material of claim 6, wherein, The mass ratio of the zinc ion pre-embedded molybdenum trioxide powder, the conductive agent and the binder is 7:2:

1.

8. The zinc ion pre-intercalation type molybdenum trioxide cathode material of claim 6, wherein, The conductive agent is Super-P, and the binder is polyvinylidene fluoride.

9. Application of the zinc ion pre-embedded molybdenum trioxide cathode material according to claim 6 in a lithium ion battery.

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