Modified ZnV2O4 nanosheet positive electrode material, preparation method thereof and application of modified ZnV2O4 nanosheet positive electrode material in battery

Abstract

The invention discloses a modified ZnV2O4 nanosheet positive electrode material, a preparation method thereof and application of the modified ZnV2O4 nanosheet positive electrode material to a battery, and the method comprises the following steps: dissolving 1mmol of NH4VO3 and 0.01-0.05 mmol of MoO3 in 40mL of a mixed solution of ultrapure water and ethylene glycol to obtain a mixed solution A; heating the mixed solution A to 80-120 DEG C, and violently stirring to obtain a transparent yellow solution; adding 0.2 to 0.5 mmol of Zn (NO3) 2.6 H2O into the transparent yellow solution, and stirring until a uniform golden yellow solution is formed; and transferring the uniform golden yellow solution into a reaction kettle, carrying out heat preservation at 180-220 DEG C for 25-35 hours, respectively washing the uniform golden yellow solution with ultrapure water and absolute ethyl alcohol for multiple times to obtain a dark green precipitate, putting the dark green precipitate into a vacuum drying oven, and carrying out vacuum drying at 60-80 DEG C for 8-12 hours to obtain the modified MoxZnV2O4 positive electrode material. According to the invention, the problem of low specific capacity caused by low conductivity and hindered zinc ion migration of a vanadium-based positive electrode material is solved, experiments prove that the Mo3ZnV2O4 positive electrode shows excellent electrochemical performance, the specific capacity reaches up to 636mAhg <-1 > in a range of 0.2-1.6 V and at 0.1 Ag <-1 >, and the Mo3ZnV2O4 positive electrode also has extremely long cycle life at 5 Ag <-1 >.

Description

Technical Field

[0001] This invention belongs to the field of zinc ion electrode cathode material preparation, specifically involving a modified ZnV2O4 nanosheet cathode material, its preparation method, and its application in batteries. Background Technology

[0002] Aqueous zinc-ion batteries are considered promising electrochemical energy storage devices due to their high safety, low cost, and environmental friendliness. However, aqueous zinc-ion batteries face severe challenges in practical applications, such as capacity decay caused by zinc dendrite growth, side reactions, slow kinetics, and dissolution of active materials. These problems hinder the commercial application of zinc-ion batteries.

[0003] In zinc-ion batteries, vanadium-based cathode materials have attracted much attention due to their high theoretical capacity. However, the low conductivity of vanadium-based cathode materials affects their electrochemical performance. The strong electrostatic interaction between zinc ions and the cathode material substrate inhibits zinc ion migration, resulting in the low specific capacity of vanadium-based cathode materials. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention aims to provide a modified ZnV2O4 nanosheet cathode material, its preparation method, and its application in batteries, thereby solving the problems of low conductivity and low specific capacity caused by the hindered migration of zinc ions in vanadium-based cathode materials.

[0005] This invention is achieved through the following technical solution:

[0006] A method for preparing a modified ZnV2O4 nanosheet cathode material includes the following steps:

[0007] S1, dissolve 1 mmol of NH4VO3 and 0.01-0.05 mmol of MoO3 in 40 mL of a mixed solution of ultrapure water and ethylene glycol to obtain mixed solution A;

[0008] S2, Heat the mixed solution A to 80-120℃ and stir vigorously until a transparent yellow solution is obtained;

[0009] S3, add 0.2-0.5 mmol Zn(NO3)2·6H2O to the transparent yellow solution and stir until a uniform golden yellow solution is formed;

[0010] S4. The uniform golden yellow solution is transferred to a reaction vessel and kept at 180-220℃ for 25-30 hours. It is then washed multiple times with ultrapure water and anhydrous ethanol to obtain a dark green precipitate. The dark green precipitate is placed in a vacuum drying oven and dried under vacuum at 60-80℃ for 8-12 hours to obtain the modified Mo. x ZnV2O4 cathode material.

[0011] Furthermore, in step S1, the ultrapure water and ethylene glycol are in a volume ratio of 1:1.

[0012] Furthermore, in step S2, the stirring time is specifically 5-10 minutes.

[0013] Furthermore, in step S4, the washing is performed three times using ultrapure water and anhydrous ethanol.

[0014] A modified ZnV2O4 nanosheet cathode material obtained by the preparation method described above.

[0015] The application of a modified ZnV2O4 nanosheet cathode material in batteries, using synthesized Mo x ZnV2O4 cathode material, conductive carbon black, and polyvinylidene fluoride were mixed and ground in an agate mortar, and the Mo... x ZnV2O4 cathode material, conductive carbon black, and polyvinylidene fluoride were mixed in a mass ratio of 7:2:1, and an organic solvent was added. After grinding and homogenizing, the mixture was magnetically stirred to form a uniform paste. This paste was then coated onto carbon-coated aluminum foil and vacuum dried. The electrode sheets were then cut into circular electrode sheets using a cutting machine.

[0016] Furthermore, the organic solvent is one of N-methyl-2-pyrrolidone, N-dimethylamide, or dimethyl sulfoxide.

[0017] Furthermore, the vacuum drying conditions are: drying temperature of 80℃ and drying time of 12h.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] This invention pre-doped Mo 6+ ZnV₂O₄ exhibits a cross-linked nanosheet structure, compared to undoped ZV₂O₄, Mo₂O₄... 6+ The ionic radius is slightly larger than V. 4+ The octahedral structure of [VO6] was slightly extended, increasing the zinc ion transport channels. This increased channel size weakened the Zn... 2+ Electrostatic interaction with lattice oxygen lowers the diffusion barrier and improves rate performance; simultaneously, Mo 6+ The introduction of V 4+ / V 5+ Mixed valence states increase the concentration of free electrons, significantly improving electron hopping conduction efficiency.

[0020] This invention experimentally demonstrates that the Mo3ZnV2O4 cathode exhibits excellent electrochemical performance within the range of 0.2–1.6 V, with a capacitance of 0.1 Ag. -1 The specific capacity is as high as 636mAhg -1 In 5Ag-1 It also exhibits an extremely long cycle life (specific capacity remains at 80.5% after 2000 cycles). Kinetic tests have verified that the Mo3ZnV2O4 cathode can achieve faster ion diffusion kinetics. Attached Figure Description

[0021] Figure 1 The XRD patterns of the ZVO cathode material prepared in Comparative Example 1 and the Mo3ZnV2O4 cathode material prepared in Example 1 are shown.

[0022] Figure 2 Fourier transform infrared spectra of the ZVO cathode material prepared in Comparative Example 1 and the Mo3ZnV2O4 cathode material prepared in Example 1.

[0023] Figure 3 The V2p diagrams are for the ZVO cathode material prepared in Comparative Example 1 and the Mo3ZnV2O4 cathode material prepared in Example 1.

[0024] Figure 4 The O1s diagrams are for the ZVO cathode material prepared in Comparative Example 1 and the Mo3ZnV2O4 cathode material prepared in Example 1.

[0025] Figure 5 The image is a scanning electron microscope (SEM) image of Mo3ZnV2O4 prepared in Example 1 at 1 μm.

[0026] Figure 6 The scanning electron microscope (SEM) image of Mo3ZnV2O4 prepared in Example 1 at 5 μm.

[0027] Figure 7 The Mo3ZnV2O4 cathode material prepared in Example 1 was tested at 0.4 mV / s. -1 The cyclic voltammetry curve below.

[0028] Figure 8 The ZVO prepared for Comparative Example 1 and the Mo3ZnV2O4 cathode prepared for Example 1 were compared at 0.5 Ag. -1 The following is a comparison chart of the cycle performance.

[0029] Figure 9 The ZVO prepared in Comparative Example 1 and the Mo3ZnV2O4 cathode prepared in Example 1 were subjected to a 5Ag test. -1 The following is a comparison chart of the cycle performance.

[0030] Figure 10 A comparison chart of the rate performance of the ZVO prepared in Comparative Example 1 and the Mo3ZnV2O4 cathode prepared in Example 1. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0032] Commercially available Maclean NH4VO3, Zn(NO3)2·6H2O and MoO3 were selected as raw materials for this invention.

[0033] Comparative Example 1

[0034] 0.4860 g of NH4VO3 and 1.19 g of Zn(NO3)2·6H2O were weighed separately. The weighed NH4VO3 powder was added to a mixture of 60 mL of ultrapure water and ethylene glycol (volume ratio of ultrapure water to ethylene glycol: 1:1). The mixture was stirred vigorously at 80 °C for 30 min to form a yellow transparent solution. The weighed Zn(NO3)2·6H2O was added to the yellow transparent solution, and the mixture was stirred vigorously at 80 °C for 10 min. The mixture was then stirred at room temperature for 2 h, and finally placed in a 100 mL Teflon-lined autoclave and stored at 200 °C for 30 h. After cooling, the synthesized product was collected by centrifugation, washed several times with ultrapure water and ethanol, and finally dried under vacuum at 60 °C for 12 h to obtain ZnV2O4.

[0035] Example 1

[0036] A method for preparing a modified ZnV2O4 nanosheet cathode material includes the following steps:

[0037] S1, Dissolve 1 mmol of NH4VO3 and 0.03 mmol of MoO3 in a mixed solution of 20 mL of ultrapure water and 20 mL of ethylene glycol to obtain mixed solution A;

[0038] S2, Heat the mixed solution A to 80℃ and stir vigorously for 30 minutes to obtain a transparent yellow solution;

[0039] S3, add 0.2 mmol Zn(NO3)2·6H2O to the transparent yellow solution and stir until a uniform golden yellow solution is formed;

[0040] S4, the uniform golden yellow solution is transferred to a reaction vessel and kept at 200°C for 30 hours. It is then washed three times with ultrapure water and anhydrous ethanol to obtain a dark green precipitate. The dark green precipitate is placed in a vacuum drying oven and dried under vacuum at 60°C for 12 hours to obtain the modified Mo3ZnV2O4 cathode material.

[0041] like Figure 1 As shown, X-ray diffraction (XRD) was used to analyze ZVO and Mo doped with different types of Mo. 6+The crystal phase and phase purity of the Mo3ZnV2O4 sample were evaluated. Five peaks were observed at 30.03°, 35.37°, 42.98°, 56.84°, and 62.42°, corresponding to the (220), (311), (400), (511), and (440) planes of ZnV2O4, consistent with ZVO. A new diffraction peak was observed at 31.97° in Mo3ZnV2O4, which is consistent with Mo 6+ This is related to the introduction of [something].

[0042] like Figure 2 As shown, Fourier transform infrared spectroscopy (FTIR) was used to analyze the internal chemical bonds and functional groups of ZVO and Mo3ZnV2O4. Except for some significant differences in peak intensity, the trends of the two samples were basically the same. Firstly, the most prominent OH bond infrared peaks in ZVO and Mo3ZnV2O4 are located at 3445 cm⁻¹. -1 and 1640cm -1 However, these two peaks did not change significantly, 2911cm -1 The CH bond peak intensity at this location is relatively low, showing almost no change. The most significant change among all samples is observed at 1433 cm⁻¹. -1 Mo=O bond and 617cm -1 The infrared peak at the VO bond also indicates that Mo 6+ Successfully integrated into ZVO.

[0043] like Figure 3 As shown, the high-resolution V2p spectra of the two samples were decomposed into two pairs of peaks near 524.9 / 517.2 eV and 522.9 / 515.6 eV, representing V2p and V2p, respectively. 5+ and V 4+ Bending energy (2p) 3 / 2 -2p 1 / 2 Transformation). V in Mo3ZnV2O4 5+ With V 4+ The peak area (0.40) is smaller than the original ZVO ratio (0.61), indicating that the peak area is smaller than the original ZVO ratio. This phenomenon suggests that the peak area is smaller than the original ZVO ratio due to the successful pre-insertion of Mo. 6+ Ions, part of V 5+ The ions were reduced to V 4+ Mo 6+ The introduction of V 4+ The ability to significantly shift towards directions with higher binding energy indicates that ZVO and Mo 6+ There are electronic interactions between them, which causes changes in the electronic structure of V.

[0044] like Figure 4As shown, in the O1s spectrum, the three peaks observed at 530.2, 531.6, and 532.8 eV represent VO bonds, oxygen vacancies, and HOH bonds, respectively. It is worth noting that the oxygen vacancy content in Mo3ZnV2O4 is significantly increased compared to ZVO. This indicates that the Mo-doped... 6+ It can also effectively increase the concentration of oxygen vacancies, thereby effectively improving reaction kinetics. The absorption of CO2 from the air may be the reason for the C1s XPS peaks in ZVO and Mo3ZnV2O4.

[0045] like Figure 5 and Figure 6 As shown, the SEM image of Mo3ZnV2O4 reveals a cross-interlocked nanosheet structure.

[0046] like Figure 7 As shown, the CV curve of Mo3ZnV2O4 exhibits four similar redox peaks, located at 1.09 / 0.87V, 0.74 / 0.50V, 1.12 / 0.89V, and 0.70 / 0.53V, respectively. These peaks are similar to those of Zn. 2+ V during the intercalation / deintercalation process is determined by V. 3 + / V 4+ and V 4+ / V 5+ This corresponds to a multi-step redox reaction.

[0047] like Figure 8 As shown, the maximum discharge specific capacities of ZVO and Mo3ZnV2O4 are 251.7 mAh g, respectively. -1 and 480.3mAh g -1 It can be seen that Mo3ZnV2O4 enhances the specific capacity. After 100 cycles, the capacity of Mo3ZnV2O4 remains at 451.6 mAh g⁻¹. -1 The specific discharge capacity.

[0048] like Figure 9 As shown, in 5Ag -1 At a current density of [value missing], the Mo3ZnV2O4 cathode can generate 338.2 mAh g⁻¹. -1 It exhibits a high initial discharge specific capacity, still providing 275.1 mAh g⁻¹ after 2000 cycles. -1 The discharge specific capacity retains 81%. Therefore, the pre-doped Mo... 6+ It plays a key role in improving the cycling performance and specific capacity of materials, promoting rapid diffusion kinetics of ion and electron migration, and maintaining a robust mechanical framework.

[0049] like Figure 10As shown, when the current density is 0.1, 0.2, 0.3, 0.5, 1, 2, 3 and 5 Ag, respectively... -1 Under these conditions, the discharge specific capacities of Mo3ZnV2O4 were 665.4, 645.1, 605.2, 554.4, 509.5, 453.2, 426.9, and 416.7 mAh g, respectively. -1 This is higher than the pure ZVO corresponding to 331.7, 307.9, 284.5, 261.4, 234.6, 209.3, 194.8 and 178.9 mAh g. -1 .

[0050] Example 2

[0051] A method for preparing a modified ZnV2O4 nanosheet cathode material includes the following steps:

[0052] S1, Dissolve 1 mmol of NH4VO3 and 0.02 mmol of MoO3 in a mixed solution of 20 mL of ultrapure water and 20 mL of ethylene glycol to obtain mixed solution A;

[0053] S2, Heat the mixed solution A to 90℃ and stir vigorously for 28 minutes to obtain a transparent yellow solution;

[0054] S3, add 0.3 mmol Zn(NO3)2·6H2O to the transparent yellow solution and stir until a uniform golden yellow solution is formed;

[0055] S4, the uniform golden yellow solution is transferred to a reaction vessel and kept at 180°C for 35 hours. It is then washed three times with ultrapure water and anhydrous ethanol to obtain a dark green precipitate. The dark green precipitate is placed in a vacuum drying oven and dried under vacuum at 65°C for 11 hours to obtain the modified Mo3ZnV2O4 cathode material.

[0056] Example 3

[0057] A method for preparing a modified ZnV2O4 nanosheet cathode material includes the following steps:

[0058] S1, Dissolve 1 mmol of NH4VO3 and 0.01 mmol of MoO3 in a mixed solution of 20 mL of ultrapure water and 20 mL of ethylene glycol to obtain mixed solution A;

[0059] S2, Heat the mixed solution A to 100℃ and stir vigorously for 25 minutes to obtain a transparent yellow solution;

[0060] S3, add 0.4 mmol Zn(NO3)2·6H2O to the transparent yellow solution and stir until a uniform golden yellow solution is formed;

[0061] S4, the uniform golden yellow solution is transferred to a reaction vessel and kept at 190°C for 33 hours. It is then washed three times with ultrapure water and anhydrous ethanol to obtain a dark green precipitate. The dark green precipitate is placed in a vacuum drying oven and dried under vacuum at 70°C for 10 hours to obtain the modified Mo3ZnV2O4 cathode material.

[0062] Example 4

[0063] A method for preparing a modified ZnV2O4 nanosheet cathode material includes the following steps:

[0064] S1, Dissolve 1 mmol of NH4VO3 and 0.04 mmol of MoO3 in a mixed solution of 20 mL of ultrapure water and 20 mL of ethylene glycol to obtain mixed solution A;

[0065] S2, Heat the mixed solution A to 110℃ and stir vigorously for 23 minutes to obtain a transparent yellow solution;

[0066] S3, add 0.5 mmol Zn(NO3)2·6H2O to the transparent yellow solution and stir until a uniform golden yellow solution is formed;

[0067] S4, the uniform golden yellow solution is transferred to a reaction vessel and kept at 210°C for 28 hours. It is then washed three times with ultrapure water and anhydrous ethanol to obtain a dark green precipitate. The dark green precipitate is placed in a vacuum drying oven and dried under vacuum at 75°C for 9 hours to obtain the modified Mo3ZnV2O4 cathode material.

[0068] Example 5

[0069] A method for preparing a modified ZnV2O4 nanosheet cathode material includes the following steps:

[0070] S1, Dissolve 1 mmol of NH4VO3 and 0.05 mmol of MoO3 in a mixed solution of 20 mL of ultrapure water and 20 mL of ethylene glycol to obtain mixed solution A;

[0071] S2, Heat the mixed solution A to 120℃ and stir vigorously for 20 minutes to obtain a transparent yellow solution;

[0072] S3, add 1.5 mmol Zn(NO3)2·6H2O to the transparent yellow solution and stir until a uniform golden yellow solution is formed;

[0073] S4, the uniform golden yellow solution is transferred to a reaction vessel and kept at 220°C for 25 hours. It is then washed three times with ultrapure water and anhydrous ethanol to obtain a dark green precipitate. The dark green precipitate is placed in a vacuum drying oven and dried under vacuum at 80°C for 8 hours to obtain the modified Mo3ZnV2O4 cathode material.

[0074] The application of a modified ZnV2O4 nanosheet cathode material in batteries, using synthesized Mo x ZnV2O4 cathode material, conductive carbon black, and polyvinylidene fluoride (PVDF) are mixed and ground in an agate mortar at a mass ratio of 7:2:1. An organic solvent is added to help the material components mix more evenly, effectively reduce the particle size, and improve the energy density and cycle performance of the battery. The organic solvent can be N-methyl-2-pyrrolidone, N-dimethylamide (DMF), or dimethyl sulfoxide (DMSO), etc. After grinding for 30 minutes to achieve uniformity, the mixture is magnetically stirred for 10 hours to form a uniform paste mixture. This paste is then coated onto carbon-coated aluminum foil and vacuum dried at 80°C for 12 hours. The electrode sheet is then cut into circular electrode sheets with a diameter of 12 mm using a cutting machine.

Claims

1. A method for preparing a modified ZnV₂O₄ nanosheet cathode material, characterized in that, Includes the following steps: S1, dissolve 1 mmol of NH4VO3 and 0.01-0.05 mmol of MoO3 in 40 mL of a mixed solution of ultrapure water and ethylene glycol to obtain mixed solution A; S2, Heat the mixed solution A to 80-120℃ and stir vigorously until a transparent yellow solution is obtained; S3, add 0.2-0.5 mmol Zn(NO3)2·6H2O to the transparent yellow solution and stir until a uniform golden yellow solution is formed; S4, the uniform golden yellow solution is transferred to a reaction vessel and kept at 180-220℃ for 25-35 hours. It is then washed multiple times with ultrapure water and anhydrous ethanol to obtain a dark green precipitate. This dark green precipitate is placed in a vacuum drying oven and dried under vacuum at 60-80℃ for 8-12 hours to obtain the modified Mo. x ZnV2O4 cathode material.

2. The method for preparing a modified ZnV₂O₄ nanosheet cathode material according to claim 1, characterized in that, In step S1, the ultrapure water and ethylene glycol are in a volume ratio of 1:

1.

3. The method for preparing a modified ZnV₂O₄ nanosheet cathode material according to claim 1, characterized in that, In step S2, the stirring time is specifically 20-30 minutes.

4. The method for preparing a modified ZnV₂O₄ nanosheet cathode material according to claim 1, characterized in that, In step S4, the washing process involves washing three times with ultrapure water and anhydrous ethanol.

5. A modified ZnV2O4 nanosheet cathode material obtained by any one of the preparation methods described in claims 1-4.

6. An application of the modified ZnV₂O₄ nanosheet cathode material as described in claim 5 in a battery, characterized in that, The synthesized Mo x ZnV2O4 cathode material, conductive carbon black, and polyvinylidene fluoride were mixed and ground in an agate mortar, and the Mo... x ZnV2O4 cathode material, conductive carbon black, and polyvinylidene fluoride were mixed in a mass ratio of 7:2:1, and an organic solvent was added. After grinding and homogenizing, the mixture was magnetically stirred to form a uniform paste. This paste was then coated onto carbon-coated aluminum foil and vacuum dried. The electrode sheets were then cut into circular electrode sheets using a cutting machine.

7. The application of the modified ZnV₂O₄ nanosheet cathode material according to claim 6 in a battery, characterized in that, The organic solvent is one of N-methyl-2-pyrrolidone, N-dimethylamide, or dimethyl sulfoxide.

8. The application of the modified ZnV2O4 nanosheet cathode material according to claim 6 in a battery, characterized in that, The vacuum drying conditions are: drying temperature of 80℃ and drying time of 12h.

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