Vanadium-based alloy compound composite material as well as preparation method and application thereof

Abstract

The invention discloses a preparation method of a vanadium-based alloy compound composite material and application of the vanadium-based alloy compound composite material in a neutral aqueous zinc ion battery. The positive electrode sequentially comprises a vanadium-based alloy compound / carbon nanomaterial, a conductive agent, a binder and a current collector, the vanadium-based alloy compound is vanadium carbide (VC) and vanadium boride (VB, VB2), the particle diameter of the vanadium carbide and the vanadium boride is 20 nm-10 microns, the thickness of a carbon layer is 1 nm-10 nm, the carbon layer is attached to the surface of a vanadium-based alloy compound layer, and the conductive agent is a conductive agent. The mass ratio of the vanadium-based alloy compound layer to the carbon layer is (10: 1)-(60000: 1), the vanadium-based alloy compound / carbon is selected as an active material of the positive electrode, and meanwhile, the specific capacity and the cycling stability of the positive electrode are improved by utilizing an in-situ electrochemical oxidation induction method. The specific capacity of the prepared positive electrode is improved by more than 75% compared with the specific capacity of V2O5 prepared in the prior art, and the positive electrode has the advantages of high conductivity and high capacity, and also has better cycle stability and longer service life.

Description

Technical Field

[0001] The present invention belongs to the field of new generation energy storage, and more specifically, relates to the preparation of vanadium-based alloy compound / carbon nanometer positive electrode and its application in neutral aqueous zinc ion battery. Background Art

[0002] Safe and reliable energy storage technology is the core of promoting the widespread application of intermittent renewable energy (such as solar energy, wind energy, etc.). Neutral aqueous zinc-ion batteries have shown great development potential in the large-scale energy storage market due to their excellent safety, environmental protection, low cost and simple manufacturing process. The theoretical capacity of the zinc negative electrode in zinc-ion batteries is 820mAh / g, but so far manganese-based oxides, Prussian blue analogs, vanadium-based oxides and certain organic substances as positive electrode materials for zinc-ion batteries are difficult to match the negative electrode capacity, and the instability of the material structure and partial solubility during the zinc ion insertion / extraction process cause the capacity to decay rapidly. Among them, transition metal vanadium-based oxides (V2O3, VO2, V6O 13 Sulfide (VS2) and vanadate compounds (ZnV2O4, KV3O8) have shown broad application prospects as electrode materials for neutral aqueous zinc ion batteries due to their excellent theoretical capacity for zinc ion storage. Unfortunately, the low intrinsic electronic conductivity and slow ion diffusion rate make the test capacity much lower than the theoretical capacity and the capacity decays rapidly.

[0003] In order to solve this problem, new negative electrode materials with high theoretical capacity, high conductivity and fast ion diffusion are urgently needed to be explored. Non-patent literature (Chemical Engineering Journal 2023, 451, 138809) discloses a positive electrode material for a zinc ion battery, V2O5 / C composite nanosheets, which are synthesized in situ by electrochemical etching of V4AlC3. The specific capacity of the positive electrode material can reach 287mAh / g (1A / g). Non-patent literature (Angew.Chem.Int.Ed.2018, 130, 4007-4012) discloses a positive electrode material Ca for a zinc ion battery. 0.25 V2O5·nH2O, calcium ions are inserted into V2O5 by hydrothermal synthesis, the interlayer spacing is increased, and the ion mobility is improved. The specific capacity of the positive electrode material can reach 289mAh / g(1C). The above preparation methods have the following defects: expensive raw materials, complex preparation methods, and limited theoretical specific capacity and test specific capacity, which greatly restricts the practical application of zinc ion batteries in hybrid electric vehicles and all-electric vehicles that require high-capacity energy storage devices. Summary of the invention

[0004] In view of the above defects or improvement needs of the prior art, the present invention provides a simple and efficient method for preparing the positive electrode material of a neutral aqueous zinc ion battery, that is, an in-situ high voltage solid-liquid-solid conversion method in an aqueous electrolyte, the purpose of which is to obtain a neutral aqueous zinc ion battery with high specific capacity and long cycle life. During the first charging process, the positive electrode material undergoes an in-situ electrochemical oxidation activation process under the participation of high voltage and water, and is transformed into an amorphous hydrous vanadium oxide nanosheet. The hydrous vanadium oxide nanosheet can reversibly embed / de-embed ions, and its amorphous and nanosheet structure gives it more channels and active sites, which is conducive to the rapid transmission of zinc ions. The water molecules between the layers act as pillars that not only stabilize its structure, but also effectively weaken electrostatic repulsion, thereby improving the reaction kinetics of zinc ions and the cyclic stability of the material.

[0005] To achieve the above-mentioned purpose, according to one aspect of the present invention, a vanadium-based positive electrode material is provided, comprising a vanadium-based alloy compound / carbon nanomaterial, wherein the vanadium-based alloy compound is vanadium carbide (VC) and vanadium boride (VB, VB2), and the particle size of the vanadium carbide and vanadium boride is 20nm to 10μm and the carbon layer has a thickness of 1nm to 10nm.

[0006] Preferably, the particle size of vanadium carbide and vanadium boride is 500 nm to 2 μm.

[0007] Preferably, the carbon layer has a thickness of 2 nm to 5 nm.

[0008] Preferably, the mass ratio of the vanadium-based alloy compound layer to the carbon layer is 10:1 to 60000:1.

[0009] Further preferably, the mass ratio of the vanadium-based alloy compound layer to the carbon layer is 500:1 to 6000:1.

[0010] According to another aspect of the present invention, there is also provided a method for preparing the above-mentioned positive electrode, comprising the following steps:

[0011] S1: Under sealed conditions, immerse the commercial vanadium-based alloy compound particles in a 0.02M-1M sugar solution for 1h-12h, so that the sugar solution is adsorbed on the surface of the vanadium-based alloy compound particles. S2: The vanadium-based alloy compound particles attached with the sugar solution obtained in step S1 are fully dried, and heated at 600°C-1000°C in a protective atmosphere for 0.5h-3h, so that the sugar in the sugar solution is carbonized into a carbon layer, and the vanadium-based alloy compound particles are embedded in the carbon layer, and the electrode material is obtained, which is composed of a carbon layer attached to the surface of the vanadium-based alloy compound layer.

[0012] S3: The vanadium-based alloy compound particles / carbon obtained in step S2 are mixed with a conductive agent and a binder and ground evenly to form a slurry, which is evenly coated on the current collector and placed in a vacuum drying oven at 80-120° C. to dry for later use.

[0013] S4: The vanadium-based alloy compound particles / carbon obtained in step S3 are used as the positive electrode, the zinc foil is used as the negative electrode, and the glass fiber is used as the separator. 2 mol L -1 ZnSO4 or 3 mol L -1 The Zn(CF3SO3)2 aqueous solution was used as the electrolyte to assemble the battery. -1 The current density is charged to 1.9~2.2V for activation.

[0014] Preferably, the sugar in the sugar solution is a disaccharide.

[0015] Further preferably, the disaccharide is glucose, sucrose, fructose or lactose.

[0016] Preferably, the conductive agent is acetylene black, highly conductive carbon quantum dots or conductive metal particles.

[0017] Preferably, the binder has a concentration of 20 mg mL -1 The polyvinylidene fluoride is dissolved in N-methylpyrrolidone to obtain a solution.

[0018] Preferably, the current collector is a stainless steel foil, a stainless steel mesh, a titanium sheet or a titanium foil.

[0019] Preferably, the battery has a capacity of 0.2 to 1A g -1 The current density is charged and activated.

[0020] Preferably, the battery charging voltage is 2-2.1V.

[0021] In general, the above technical scheme conceived by the present invention can achieve the following beneficial effects compared with the prior art by using vanadium-based alloy compound / carbon as the positive electrode material: 1. The present invention selects vanadium-based alloy compound as the active material of the positive electrode to address the disadvantage of low capacity of the current neutral aqueous zinc ion battery positive electrode material. It has been verified that its tested specific capacity can be as high as 508mAh / g (1A / g), which is 75% higher than the prior art.

[0022] above;

[0023] 2. The vanadium-based alloy compound is transformed into hydrous vanadium oxide nanosheets under the first high-voltage charge. This structure is conducive to the reversible embedding / de-embedding of zinc ions. Its amorphous structure and nanosheet structure provide more channels and active sites, which are conducive to rapid zinc ion transport and the cyclic stability of the material.

[0024] 3. The carbon layer attached to the surface of the vanadium-based alloy compound is conducive to slowing down the material dissolution caused by the structural collapse during the cyclic charge and discharge process, thereby improving the cycle stability of the positive electrode material. After 10,000 cycles of charge and discharge, its specific capacity still maintains about 78.5% of the initial state;

[0025] 4. The method of using sugar solution to hydrothermally prepare vanadium-based alloy compounds / carbon nanomaterials and then preparing high-performance zinc-ion battery positive electrodes through an in-situ electrochemical oxidation-induced activation process is simple, low-cost, and suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The X-ray diffraction pattern of the commercial VC powder used in Example 1 of the present invention;

[0027] Figure 2 A scanning electron microscope photograph of the commercial VC / C powder used in Example 1 of the present invention;

[0028] Figure 3 A transmission electron microscope image of the commercial VC / C powder used in Example 1 of the present invention;

[0029] Figure 4 This is an X-ray diffraction pattern of the VC / C electrode prepared in Example 1 of the present invention after the first charge;

[0030] Figure 5 This is a scanning electron microscope photograph of the VC / C electrode prepared in Example 1 of the present invention after the first charge;

[0031] Figure 6 This is the XPS spectrum of the VC / C electrode prepared in Example 1 of the present invention after the first charge;

[0032] Figure 7 The VC / C electrode prepared in Example 1 of the present invention is used as an aqueous zinc ion battery at 1Ag -1 Performance test diagram of 1000 cycles at a current density of;

[0033] Figure 8 The VC / C electrode prepared in Example 1 of the present invention is used as an aqueous zinc ion battery at 10Ag -1 Performance test diagram of 10,000 cycles at a current density of;

[0034] Fig. 9 The VC / C electrode prepared in Example 1 of the present invention is used as a rate performance diagram of an aqueous zinc ion battery tested at different current densities. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. 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. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] The new application of the vanadium-based alloy compound / carbon directly used for the positive electrode material of aqueous zinc ion battery with high capacity and long cycle stability provided by the embodiment of the present invention includes:

[0037] 1. Use commercial vanadium-based alloy compounds / carbon directly as the active material of the positive electrode material of aqueous zinc-ion batteries;

[0038] 2. A vanadium-based alloy compound / carbon is mixed with a conductive agent and a binder and coated on a current collector to prepare a vanadium-based alloy compound positive electrode;

[0039] 3. Use zinc sheet as negative electrode, glass fiber as separator, ZnSO4 or Zn(CF3SO3)2 aqueous solution as electrolyte and package into battery.

[0040] The present invention also provides a commercial vanadium-based alloy compound / carbon for use in an aqueous zinc ion battery positive electrode, and the assembled aqueous zinc ion battery has excellent performance, including cycle stability and specific capacity.

[0041] The present invention will be further described below in conjunction with specific embodiments.

[0042] Example 1

[0043] This case uses commercial vanadium-based metal compounds / carbon to make the positive electrode of an aqueous zinc-ion battery, assembles it into a button cell and tests it.

[0044] 1. Preparation of Electrodes

[0045] First, prepare the binder. Take 5 ml of N-methylpyrrolidone and put it into a beaker. Weigh 100 mg of polyvinylidene fluoride and add it to the beaker. Stir it magnetically until it is completely dissolved. Take 140 mg of commercial vanadium-based metal compound / carbon and 40 mg of acetylene black and mix them evenly. Then add 500 μL of the prepared polyvinylidene fluoride binder and 200 μL of N-methylpyrrolidone and mix them evenly to form an electrode slurry. Then, coat the slurry on a stainless steel mesh or stainless steel foil current collector. Finally, put it in a vacuum drying oven at 120°C for 12 hours to dry it for use.

[0046] 2. Packaging test

[0047] Prepare 2 mol L -1 ZnSO4 or 3 mol L-1 Zn(CF3SO3)2 is used as the electrolyte, the electrode obtained in step 1 is used as the positive electrode, zinc foil is used as the negative electrode, and glass fiber is used as the separator to assemble into a button cell.

[0048] 3.Battery pre-activation charging

[0049] The battery is charged at 0.1Ag -1 The cell was charged to 2.0 V at a current density of 1.50 volts for activation.

[0050] In order to simplify the description, the preparation conditions of Examples 2-11 are listed in Table 1.

[0051] Table 1

[0052]

[0053]

[0054] Experimental results analysis

[0055] The X-ray diffraction peaks, scanning electron microscope and transmission microscope photos of the positive electrode material VC / C used in this embodiment 1 are as follows: Figure 1 , 2 and 3. The X-ray diffraction peaks of the VC / C electrode after the first charge are as follows Figure 4 As shown in Figure 2, VC is transformed into a new amorphous phase. The scanning electron microscope photo of the VC / C electrode after the first charge is shown in Figure 2. Figure 5 As shown in the figure, the XPS of the VC electrode with a nanosheet structure after the first charge is as follows: Figure 6 As shown, the results show that VC is converted to V 5+ Compound.

[0056] The VC / C positive electrode prepared in Examples 1-4 was used in aqueous zinc ion button cells. The electrochemical performance test showed that the cycle stability was Figure 7 , 8 As shown. In 1Ag -1 After 1000 cycles of charge and discharge at a current density of -1 ; at 10Ag -1 After 10,000 cycles of charge and discharge at a current density of -1 In addition, the rate performance of button cells at different current densities is shown in Figure 2. Fig. 9 As shown, it exhibits excellent capacity and rate performance. The positive electrodes prepared in Examples 5-11 can also obtain similar results as those in Examples 1-4.

[0057] It is easy for those skilled in the art to understand that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement and improvement made within the spirit and principle of the present invention shall be included in the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A positive electrode material for a neutral aqueous zinc ion battery, characterized in that: The present invention comprises a vanadium-based alloy compound composite carbon material, wherein the vanadium-based alloy compound is vanadium carbide (VC) or vanadium boride (VB or VB2), and the particle diameter of the vanadium carbide or vanadium boride is 20nm to 10nm. μm and a carbon layer with a thickness of 1nm to 10nm.

2. The positive electrode material according to claim 1, characterized in that The particle size of the vanadium carbide and vanadium boride is 500nm-2μm.

3. The positive electrode material according to claim 1, characterized in that The carbon layer thickness is 2 nm~5nm.

4. The positive electrode material according to claim 1, characterized in that The mass ratio of the vanadium-based alloy compound layer to the carbon layer is 10:1 to 60000:

1.

5. The positive electrode material according to claim 4, characterized in that The mass ratio of the vanadium-based alloy compound layer to the carbon layer is 500:1 to 6000:

1.

6. The method for preparing a positive electrode according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1: Under sealed conditions, immersing the commercial vanadium-based alloy compound particles in a 0.02M to 1M sugar solution for 1 hour to 12 hours, so that the sugar solution is adsorbed on the surface of the vanadium-based alloy compound particles; S2: the vanadium-based alloy compound particles attached to the sugar solution obtained in step S1 are fully dried, and heated at 600° C. to 1000° C. in a protective atmosphere for 0.5 h to 3 h, so that the sugar in the sugar solution is carbonized into a carbon layer, and a carbon layer is attached to the surface of the vanadium-based alloy compound particles, so that the positive electrode material is composed of a vanadium-based alloy compound composite carbon material; S3: the vanadium-based alloy compound composite carbon material obtained in step S2 is mixed with a conductive agent and a binder and ground evenly to form a slurry, which is evenly coated on the current collector and placed in a vacuum drying oven at 80-120° C. for drying for later use; S4: The vanadium-based alloy compound composite carbon material obtained in step S3 is used as the positive electrode material, the zinc foil is used as the negative electrode, and the glass fiber is used as the separator. -1 ZnSO4 or 3 mol L -1 The Zn(CF3SO3)2 aqueous solution was used as the electrolyte to assemble the battery. -1 The current density is charged to 1.9~2.2V for activation.

7. The preparation method according to claim 6, characterized in that: The sugar solution is glucose, sucrose, fructose or lactose; the conductive agent is acetylene black, highly conductive carbon quantum dots or conductive metal particles; the binder is a solution obtained by dissolving polyvinylidene fluoride in N-methylpyrrolidone; the current collector is stainless steel foil, stainless steel mesh, titanium sheet or titanium foil; the battery is 0.2-1Ag -1 The battery is charged and activated by a current density of 2 to 2.1 V.

Images