A zinc-based battery positive electrode material and its preparation method and use method

Abstract

The present invention belongs to the field of zinc-based battery electrode materials and discloses a zinc-based battery positive electrode material, its preparation method, and its use method. A zinc-based battery positive electrode material is provided, wherein the positive electrode material is one of vanadium-based oxide nanoribbons, sodium-doped vanadium-based oxide nanoribbons, and a vanadium-based oxide nanoribbon / graphene composite material, wherein the vanadium-based oxide nanoribbons in the vanadium-based oxide nanoribbon / graphene composite material have mesopores extending through the thickness of the vanadium-based oxide nanoribbons. The present invention uses readily available vanadium powder and hydrogen peroxide as raw materials and utilizes a simple hydrothermal method to prepare the vanadium-based oxide. Further sodium doping or graphene modification can be performed by adding various additives. The positive electrode material of the present invention exhibits superior high-rate performance and good cycle stability, making it an ideal positive electrode material for zinc-based batteries.

Description

Technical Field

[0001] The present invention belongs to the field of zinc-based battery electrode materials, and in particular relates to a zinc-based battery positive electrode material and a preparation method and a use method thereof. Background Art

[0002] With the increasing severity of environmental pollution and the depletion of fossil energy, the demand for new renewable energy sources for sustainable development is constantly increasing. Rechargeable zinc-based batteries, due to their excellent properties, have become the preferred choice for energy storage devices such as electric vehicles, emergency energy, and energy storage power stations. They are also an ideal potential power source for future space technology and high-end energy storage systems. Rechargeable zinc-based batteries are mainly composed of a positive electrode, a negative electrode, a separator, and an electrolyte. The preparation of new positive electrode materials for rechargeable zinc-based batteries with high charge storage density, rapid charge and discharge characteristics, good charge and discharge efficiency, long cycle life, and low cost is currently one of the most dynamic branches of this research direction.

[0003] Vanadium-based oxides have excellent electrochemical performance as cathodes for aqueous zinc-ion batteries, but their rate capability and cycling stability need improvement. Therefore, current research in this field focuses on the research, development, and preparation of novel zinc-based battery cathode materials with high capacity, high power, long life, and low cost.

[0004] For vanadium-based oxide cathode materials, how to achieve high capacity while maintaining structural stability and improving Zn 2+ The migration rate in it, which enables it to have better long-term cycle stability and better rate performance, will become an issue that requires long-term attention and research. Summary of the Invention

[0005] In order to overcome the deficiencies in the prior art, the present invention aims to provide a zinc-based battery positive electrode material and a preparation method and a use method thereof.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A zinc-based battery positive electrode material, wherein the positive electrode material is one of vanadium-based oxide nanoribbons, sodium-doped vanadium-based oxide nanoribbons, and vanadium-based oxide nanoribbon / graphene composite materials, and the vanadium-based oxide nanoribbons in the vanadium-based oxide nanoribbon / graphene composite materials have mesopores running through the thickness direction of the vanadium-based oxide nanoribbons.

[0008] Preferably, the positive electrode material is VO2 nanobelt, Na-VO2 nanobelt, V3O7 nanobelt or VO2 nanobelt / RGO composite material, and the VO2 nanobelt in the VO2 nanobelt / RGO composite material has mesopores running through its thickness direction.

[0009] When the positive electrode material is VO2 nanobelt, the preparation steps are as follows:

[0010] (1) Disperse vanadium powder evenly in water, add hydrogen peroxide, stir evenly, and then hydrothermally react at 120-200 °C for 6-48 h; wherein the raw material dosage ratio is vanadium powder: water: hydrogen peroxide = 0.2 g: (20-40) mL: (0.9-1.3) mL;

[0011] (2) Dry the product obtained in step (1) to obtain VO2 nanobelts.

[0012] When the positive electrode material is Na-VO2 nanobelt, the preparation steps are as follows:

[0013] (1) Disperse vanadium powder and anhydrous sodium sulfate uniformly in water, add hydrogen peroxide, stir evenly, and then hydrothermally react at 120-200 °C for 6-48 h; wherein the raw material dosage ratio is vanadium powder: anhydrous sodium sulfate: water: hydrogen peroxide = 0.2 g: (0.01-0.05) g: (20-40) mL: (0.9-1.3) mL;

[0014] (2) Drying the product obtained in step (1) to obtain Na-VO2 nanobelts (Na-doped VO2 nanobelts).

[0015] When the positive electrode material is a VO2 nanobelt / RGO composite material, the preparation steps are as follows:

[0016] (1) Disperse vanadium powder and graphene oxide (GO) uniformly in water, add hydrogen peroxide, stir evenly, and then hydrothermally react at 120-200 °C for 6-48 h; wherein the raw material dosage ratio is vanadium powder: graphene oxide: water: hydrogen peroxide = 0.2 g: (0.005-0.05 g): (20-40) mL: (0.3-0.7) mL;

[0017] (2) Drying the product obtained in step (1) to obtain a VO2 nanobelt / RGO composite material (graphene RGO is used as a substrate, and VO2 nanobelts are deposited on the graphene RGO sheet).

[0018] When the positive electrode material is V3O7 nanobelt, the preparation steps are as follows:

[0019] (1) Disperse vanadium powder evenly in water, add hydrogen peroxide, stir evenly, and then hydrothermally react at 120-200 °C for 6-48 h; wherein the raw material dosage ratio is vanadium powder: water: hydrogen peroxide = 0.2 g: (20-40) mL: (1.5-2.0) mL;

[0020] (2) Dry the product obtained in step (1) to obtain V3O7 nanobelts.

[0021] Preferably, in step (1), the concentration of hydrogen peroxide is 30-50 wt.%, and the stirring time is 0.5-2 h.

[0022] Preferably, in step (2), the drying is vacuum drying, freeze drying or supercritical drying.

[0023] Method for using zinc-based battery positive electrode materials: Mix the positive electrode material, adhesive, and conductive agent evenly, prepare a paste with N-methylpyrrolidone, and apply it on the current collector. Set the first-cycle charging cutoff voltage to 1.55-1.85 V for in-situ activation. The activated positive electrode material is used as the positive working electrode of the zinc-based battery.

[0024] Preferably, by mass ratio, the positive electrode material: conductive agent: binder = (6-9): (1-3): 1, the positive electrode material: N-methylpyrrolidone = 1: (1-2); the binder is PVDF, the conductive agent is acetylene black or super carbon black, and the current collector is stainless steel mesh or titanium foil.

[0025] Beneficial effects: The present invention uses easily available vanadium powder and hydrogen peroxide as raw materials, and utilizes a simple hydrothermal method to prepare vanadium-based oxides. Na doping or graphene modification can be further performed by adding different additives. The positive electrode material of the present invention has superb high-rate performance and good cycle stability, and is an ideal positive electrode material for zinc-based batteries. It can be widely used in various portable electronic devices, electric vehicles, aerospace and other fields. In addition, the positive electrode material of the present invention can be prepared from easily available raw materials through a process with high repeatability, simple process and low time consumption, and is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 : Scanning electron microscope photograph of VO2 nanobelts obtained in Example 1.

[0027] Figure 2 : Transmission electron microscope photograph of VO2 nanobelts obtained in Example 1.

[0028] Figure 3 : XRD pattern of VO2 nanoribbons obtained in Example 1.

[0029] Figure 4 : Scanning electron microscope photograph of the VO2 nanobelt / RGO composite material obtained in Example 3.

[0030] Figure 5 : Transmission electron microscope photograph of the VO2 nanobelt / RGO composite material obtained in Example 3.

[0031] Figure 6 : XRD pattern of V3O7 nanobelts obtained in Example 4.

[0032] Figure 7 : In-situ activation curve and charge-discharge curve of VO2 nanobelt obtained in Example 1.

[0033] Figure 8 : In-situ activation curve and charge-discharge curve of Na-VO2 nanobelt obtained in Example 2.

[0034] Figure 9 : In-situ activation curve and charge-discharge curve of the VO2 nanobelt / RGO composite material obtained in Example 3.

[0035] Figure 10 : In-situ activation curve and charge-discharge curve of V3O7 nanobelt obtained in Example 4.

[0036] Figure 11 : Cyclic performance curves of the VO2 nanobelts obtained in Example 1 and the VO2 nanobelt / RGO composite material obtained in Example 3. DETAILED DESCRIPTION

[0037] To make the present invention clearer and more specific, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0038] Example 1

[0039] A method for preparing VO2 nanoribbons as a positive electrode material for zinc-based batteries, the preparation steps are as follows:

[0040] (1) Disperse 0.2 g of vanadium powder in 30 mL of water and stir at room temperature for 2 h. Then, add 1 mL of H2O2 (30 wt.%) dropwise into the mixture and stir for further 1.5 h.

[0041] (2) The system obtained in step (1) was transferred to a 50 mL autoclave and subjected to hydrothermal reaction at 180 °C for 12 h, and then naturally cooled to ambient temperature;

[0042] (3) The solid product obtained by freeze-drying at -40 °C is VO2 nanobelt.

[0043] The scanning electron microscope photograph of the VO2 nanobelt obtained in Example 1 is as follows Figure 1 As shown in the transmission electron microscope photos Figure 2 As shown, the XRD pattern is Figure 3 As shown. Figure 1 and Figure 2 It can be seen that the width of VO2 nanoribbons is 20-80 nm and the length is 0.5-3μm. Figure 3The XRD pattern of the VO2 was confirmed to be B phase.

[0044] Example 2

[0045] A method for preparing Na-VO2 nanobelts as a positive electrode material for zinc-based batteries, the preparation steps are as follows:

[0046] (1) Disperse 0.2 g of vanadium powder and 0.01 g of anhydrous sodium sulfate in 30 mL of water and stir at room temperature for 2 h. Then, add 1 mL of H2O2 (30 wt.%) dropwise to the mixture and stir for further 1.5 h.

[0047] (2) The system obtained in step (1) was transferred to a 50 mL autoclave and subjected to hydrothermal reaction at 180 °C for 12 h, and then naturally cooled to ambient temperature;

[0048] (3) The solid product obtained by freeze-drying at -40 °C is Na-VO2 nanobelt (sodium-doped VO2 nanobelt).

[0049] The element contents obtained from the EDS spectrum of the Na-VO2 nanobelts obtained in Example 2 are shown in Table 1, which confirms that sodium is successfully doped into the VO2 nanobelts.

[0050]

[0051] Example 3

[0052] A method for preparing a VO2 nanobelt / RGO composite material as a positive electrode material for a zinc-based battery, the preparation steps are as follows:

[0053] (1) Disperse 0.2 g of vanadium powder and 0.01 g of graphene oxide (GO) in 30 mL of water and stir at room temperature for 2 h. Then, 0.5 mL of H2O2 (30 wt.%) was added dropwise to the mixture, and then stirred for further 1.5 h.

[0054] (2) The system obtained in step (1) was transferred to a 50 mL autoclave and subjected to hydrothermal reaction at 180 °C for 12 h, and then naturally cooled to ambient temperature;

[0055] (3) The solid product obtained by freeze-drying at -40 °C is the VO2 nanobelt / RGO composite material.

[0056] The scanning electron microscope photograph of the VO2 nanobelt / RGO composite material obtained in Example 3 is as follows Figure 4 As shown in the transmission electron microscope photos Figure 5 As shown. Figure 4 and Figure 5It can be seen that VO2 nanoribbons are deposited on graphene RGO sheets. The VO2 nanoribbons have a large number of mesopores running through the thickness direction, with a pore size of about 2 nm.

[0057] Example 4

[0058] A method for preparing V3O7 nanobelts as a positive electrode material for zinc-based batteries, the preparation steps are as follows:

[0059] (1) Disperse 0.2 g of vanadium powder in 30 mL of water and stir at room temperature for 2 h. Then, add 1.6 mL of H2O2 (30 wt.%) dropwise to the mixture and stir for further 1.5 h.

[0060] (2) The system obtained in step (1) was transferred to a 50 mL autoclave and subjected to hydrothermal reaction at 180 °C for 12 h, and then naturally cooled to ambient temperature;

[0061] (3) The solid product obtained by freeze-drying at -40 °C is V3O7 nanobelt.

[0062] The XRD pattern of the V3O7 nanobelts obtained in Example 4 is as follows: Figure 6 As shown, the XRD of the obtained product is consistent with the standard card of V3O7•H2O, proving that the product obtained in Example 4 is V3O7•H2O. This indicates that relative to Example 1, the amount of hydrogen peroxide added is increased, and vanadium is oxidized to a higher valence state.

[0063] Charge and discharge performance test

[0064] The following steps are taken to prepare the positive working electrode of zinc-based battery:

[0065] (1) Mix 0.7 g of the product obtained in Example 1-4, 0.2 g of conductive carbon black, and 0.1 g of PVDF adhesive, and prepare a paste with 1 mL of N-methylpyrrolidone. Then, apply the paste evenly on the titanium foil.

[0066] (2) Dry in a vacuum oven at 80 °C for 8 h;

[0067] (3) Cut the titanium foil into discs to make working electrodes.

[0068] Electrochemical performance test method is as follows:

[0069] (1) The simulated battery uses a button-type CR2032 system, in which the negative electrode is a high-purity zinc sheet;

[0070] (2) The electrode material was charged and discharged for the first cycle at a current density of 0.1 A / g in the voltage range of 0.3-1.8 V, and in situ activation was performed during the charging process.

[0071] The in-situ activation curve (1st) and charge-discharge curve (2nd) of the cathode materials obtained in Examples 1-4 are shown as follows: Figure 7-10 As shown, it can be seen that: when the positive electrode material of Example 1 is charged to ~1.48 V for the first time, in-situ electrochemical activation occurs, and the discharge capacity after activation is increased from 279 mAh / g in the first cycle to 431 mAh / g; when the positive electrode material of Example 2 is charged to ~1.5 V for the first time, in-situ electrochemical activation occurs, and the discharge capacity after activation is increased from 301 mAh / g in the first cycle to 572 mAh / g; when the positive electrode material of Example 3 is charged to ~1.47 V for the first time, in-situ electrochemical activation occurs, and the discharge capacity after activation is increased from 341 mAh / g in the first cycle to 731 mAh / g; when the positive electrode material of Example 4 is charged to ~1.46 V for the first time, in-situ electrochemical activation occurs, and the discharge capacity after activation is increased from 350 mAh / g in the first cycle to 466 mAh / g.

[0072] The discharge capacity and rate performance of the activated electrode material were tested and analyzed using constant current charge and discharge. The charge and discharge regime is: voltage range: 0.3-1.8 V; current density is 0.1 A / g and 5A / g respectively. The discharge capacity of the full battery composed of the positive electrode materials of Examples 1-4 above at different rate current densities is shown in Table 2. Among them, the positive electrode material VO2 nanobelt / RGO composite material of Example 3 has the highest capacity and rate performance, with a discharge capacity of up to 731mAh / g at a low rate current density of 0.1 A / g and a discharge capacity of up to 477mAh / g at a high rate current density of 5A / g. mAh / g. This is because Example 3 uses graphene oxide as a raw material. Graphene oxide can not only be reduced to graphene during the hydrothermal process, serving as a conductive matrix for VO2, improving the electrode conductivity and structural stability during the charge and discharge process, but more importantly, the oxygen-containing functional groups on it play a mild oxidizing role in the oxidation of vanadium powder to VO2, allowing B-phase VO2 to be obtained even with a reduced amount of hydrogen peroxide. The mild oxidizing effect of the oxygen-containing functional groups introduces a large number of oxygen vacancies into VO2, causing the lattice to expand, which is more conducive to the rapid migration of ions during the electrochemical reaction and improves the battery rate performance. Compared with the VO2 nanoribbons of Example 1, the discharge capacity of the positive electrode material Na-VO2 nanoribbons of Example 2 is significantly improved. This is because Na doping can open ion diffusion channels in VO2 and provide more electrochemically active sites. The initial discharge capacity of the positive electrode material V3O7 of Example 4 before activation is higher than that of the positive electrode material VO2 of Example 1, but there is no significant difference in the capacity between the two after activation. The results in Table 2 show that sodium ion doping and graphene oxide-assisted synthesis have a significant effect on improving the discharge capacity of the positive electrode after activation.

[0073]

[0074] The cycle performance of the positive electrode materials of Example 1 and Example 3 is as follows Figure 11 As shown. Figure 11 It can be seen that at a current density of 5 A / g, the discharge capacity of Example 1 after 1000 cycles is 150 mAh / g, while the discharge capacity of Example 3 after 1000 cycles can reach 350 mAh / g, indicating that the positive electrode material of the present invention has good cycle stability.

Claims

1. A method for preparing a zinc-based battery positive electrode material, characterized in that: The positive electrode material is a VO2 nanobelt / RGO composite material, and its preparation steps are as follows: (1) Disperse vanadium powder and graphene oxide uniformly in water, add hydrogen peroxide, stir evenly, and then hydrothermally react at 120-200°C for 6-48 hours; wherein the raw material dosage ratio is vanadium powder: graphene oxide: water: hydrogen peroxide = 0.2 g: (0.005-0.05 g): (20-40) mL: (0.3-0.7) mL; (2) Drying the product obtained in step (1) to obtain a VO2 nanobelt / RGO composite material.

2. The method for preparing the zinc-based battery positive electrode material according to claim 1, wherein: In step (1), the concentration of hydrogen peroxide is 30-50 wt.%, and the stirring time is 0.5-2 h.

3. The method for preparing the zinc-based battery positive electrode material according to claim 1, wherein: In step (2), the drying is vacuum drying, freeze drying or supercritical drying.

4. A zinc-based battery positive electrode material prepared by the preparation method according to any one of claims 1 to 3.

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