Zinc ion intercalated layered vanadium oxide nanomaterials, preparation and use thereof

Abstract

The application discloses a zinc ion intercalation layered vanadium oxide nanomaterial, preparation and application of the nanomaterial. 2+ Pre-intercalated H2V3O8 / V6O 13 , which is referred to as ZVO, when the ZVO is used as a positive electrode material of a calcium ion battery, V is used as an active element with variable valence states, can provide higher capacity. Meanwhile, corresponding potentials are suitable for organic or organic and water hybrid electrolytes. Zinc ions and solvent molecules pre-intercalated between layers can effectively expand the interlayer spacing, improve the ion diffusion kinetics, meanwhile, the pre-intercalated zinc ions and solvent molecules can produce a support effect, and stabilize the layered structure. Therefore, when the ZVO is used as a positive electrode active material of an organic or organic and water hybrid calcium ion battery, the long cycle life and high rate performance of the electrode can be ensured, and the problems of low diffusion rate caused by the large diameter of calcium ions and the direct influence of the intercalation of calcium ions into the electrode material / detachment of calcium ions from the electrode material on the cycle life of the battery in the charge / discharge process are solved.

Description

Technical Field

[0001] The present invention belongs to the field of nanomaterial and electrochemical research, and specifically relates to a zinc ion embedded layered vanadium oxide nanomaterial, its preparation and application. Background Art

[0002] In recent years, multivalent ion batteries have emerged as a promising class of batteries, such as calcium-ion batteries, magnesium-ion batteries, zinc-ion batteries, and aluminum-ion batteries. Compared to intercalation of equivalent monovalent ions, these multivalent ions require only half the number of monovalent ions to achieve the same amount of electron transfer. If the host structure can accommodate these divalent ions, then theoretically, the electrochemical capacity of the electrode can be doubled compared to the same intercalation material with monovalent ions (such as Li or Na). The theoretical capacity of the intercalation compound depends on the total number of electrons that can be transferred to the host cation, not the ion itself. On the other hand, the maximum reversible capacity is controlled by the number of vacancies available in the host and the structural changes that occur during the intercalation process. Therefore, if the host can accommodate these more polarizable ions, theoretically, higher capacities can be achieved. Compared to Mg and Al ions, Ca ions, due to their relatively large ionic radius, have a charge density and polarizability similar to those of Li ions. This lower charge density allows for better kinetics, potentially avoiding the kinetic issues associated with multivalent chemistry. The deposition potential of calcium is -2.9V, 0.1V higher than lithium and 0.5V lower than magnesium. Since battery voltage is determined by the difference between the anode and cathode potentials, this could lead to higher battery voltages and potentially higher energy density. Furthermore, calcium is the fifth most abundant element in the Earth's crust, more abundant than both sodium and magnesium and 2,500 times more abundant than lithium, meaning calcium resources are plentiful. Furthermore, calcium is a key component of human bone and is non-toxic, meaning its use in battery manufacturing poses no environmental risk. Furthermore, calcium's abundant reserves, low cost, and environmental friendliness make calcium-ion batteries highly promising. However, research on calcium-ion batteries remains in its early stages, primarily due to the lack of suitable electrode materials. Calcium ions have a larger diameter and higher charge density than monovalent ions. The resulting high polarization leads to strong binding between the ions and the negatively charged host lattice, significantly reducing their diffusion rate. Furthermore, the insertion and extraction of calcium ions into and out of the electrode material during discharge and charge can significantly damage the electrode structure, directly impacting the battery's cycle life. Therefore, finding suitable electrode materials is particularly important for the development of calcium-ion batteries.

[0003] Vanadium oxide has a good layered structure, high theoretical capacity, rich reserves and other advantages, as the positive electrode material of lithium ion battery, zinc ion battery, alkali metal ion battery is widely studied. Because it has a larger interlayer spacing, it is also applicable as a positive electrode material for calcium ion battery. However, due to its large interlayer spacing, the layered structure is easy to distort and deform, the structure collapses, and the conductivity is poor, which makes its cycle performance poor when applied to calcium ion battery. The layered ultra-thin nanostructure and the intercalation of solvent molecules between the layers not only provide a very short calcium ion diffusion distance, but also a continuous electron transport path to ensure good electronic conductivity. Secondly, intercalating metal ions into the interlayer structure of vanadium oxide crystal can act as a support to stabilize the interlayer structure and prevent structure collapse, while improving the electronic conductivity of vanadium oxide. Therefore, developing new high-performance positive electrode materials is of great significance to the development of calcium ion batteries. SUMMARY

[0004] The present application aims at the above-mentioned existing scientific and technological problems, and provides a zinc ion intercalated layered vanadium oxide nanomaterial, a preparation method and applications thereof, to solve the problem that the diameter of calcium ions is large, and the charge density of calcium ions is higher than that of monovalent ions, which results in strong combination between ions and negatively charged host lattices due to high polarization intensity, thereby greatly reducing the diffusion rate; at the same time, the embedding of calcium ions into the electrode material and the extraction of calcium ions from the electrode material during the charging and discharging process can cause great damage to the structure of the electrode material, which directly affects the cycle life of the battery.

[0005] The technical scheme of the present application is: a zinc ion intercalated layered vanadium oxide nanomaterial, the material composition of which is Zn 2+ Pre-embedded H2V3O8 / V6O 13 , which is referred to as ZVO, wherein the actual embedded zinc vanadium ratio Zn / V = 0.025-0.1, the molar ratio H2V3O8 / V6O 13 = 0.8-12.8;

[0006] Further, the optimal molar ratio H2V3O8 / V6O 13 = 12.8.

[0007] Further, the diameter of the nanomaterial is 50-100 nm, and the length is 1-5 microns.

[0008] A preparation method of a zinc ion intercalated layered vanadium oxide nanomaterial, comprising the following steps:

[0009] S01, weigh the zinc source and add it to a mixed solution of deionized water and ketones, and stir to obtain a colorless and clear solution;

[0010] S02, weighing a vanadium source and adding it to the above colorless clear solution, wherein the molar ratio of the zinc source to the vanadium source is 0.005-0.025:2, and continuing stirring for 4-6 hours to obtain a uniform orange-red solution;

[0011] S03, transferring the orange-red solution obtained in S02 to a reactor for solvothermal reaction, and then taking it out and naturally cooling it to room temperature to obtain a dark green product;

[0012] S04, adding an appropriate amount of deionized water to the dark green product obtained in S03 and stirring to form a uniform suspension;

[0013] S05, filtering the suspension obtained in S04, washing it with deionized water and anhydrous ethanol, drying it, and finally grinding the product to obtain zinc ion pre-embedded layered vanadium oxide nanomaterials.

[0014] Furthermore, the zinc source in S01 is one of ZnSO4, Zn(CH3COO)2, and ZnCl2, and the ketone is one of acetone, butanone, and cyclohexanone.

[0015] Furthermore, the vanadium source in S02 is V2O5.

[0016] Furthermore, the solvent thermal temperature in S03 is 180-210° C., and the hydrothermal time is 48 h to 96 h.

[0017] A zinc-ion-embedded layered vanadium oxide nanomaterial is used as a positive electrode active material for a calcium ion battery. The calcium ion battery positive electrode active material comprises a working electrode, a counter electrode, a reference electrode, and an electrolyte. The working electrode is the zinc-ion-embedded layered vanadium oxide nanomaterial, and the counter electrode is platinum or activated carbon. The electrolyte is an organic-aqueous hybrid electrolyte containing calcium ions. The volume ratio of the organic-aqueous hybrid electrolyte is 4:1.

[0018] The beneficial effect of the present invention is that a layered structure Zn 2+ Pre-embedded H2V3O8 / V6O 13(Abbreviated as ZVO) nanorods. When zinc ions and solvent molecules are pre-embedded into layered vanadium oxide nanomaterials as the positive electrode active material of calcium ion batteries, V is the active element. Due to the variable valence state of V, multiple electron gains and losses can be achieved, thus providing a higher capacity. At the same time, the corresponding potential is suitable for organic or organic-water hybrid electrolytes. The pre-embedded zinc ions and solvent molecules (water and acetone) can effectively expand the interlayer spacing and improve the ion diffusion kinetics. At the same time, the pre-embedded zinc ions and solvent molecules can produce a pillar effect to stabilize the layered structure. Therefore, when zinc ions are pre-embedded in layered vanadium oxide nanomaterials (ZVO) as positive electrode active materials for organic or organic-water hybrid calcium ion batteries, long cycle life and high rate performance of the electrode can be guaranteed at the same time. This solves the problems of low diffusion rate caused by the large diameter of calcium ions and calcium ions being embedded in / out of electrode materials during discharge and charge, which will cause significant damage to the structure of the electrode material and directly affect the cycle life of the battery. It is a very promising high-performance positive electrode active material for calcium ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 : X-ray diffraction spectrum (XRD) of the ZVO electrode material of Example 1;

[0020] Figure 2 : SEM image of the ZVO electrode material of Example 1;

[0021] Figure 3 :The ZVO electrode material of Example 1 is at 0.2 mV s -1 Cyclic voltammogram below;

[0022] Figure 4 :The ZVO electrode material of Example 1 is 5Ag -1 The long cycle performance diagram of the battery at a current density of 1.5 V and in the potential range of -0.7 to 1.2 V;

[0023] Figure 5 : Battery rate performance diagram of the ZVO electrode material of Example 1 at different current densities and in the potential range of -0.7 to 1.2 V. DETAILED DESCRIPTION

[0024] In order to better understand the present invention, the content of the present invention is further described below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

[0025] Example 1:

[0026] The preparation method of ZVO nanorod material comprises the following steps:

[0027] 0.0184g (CH3COO)2Zn was weighed and added to a mixture of 30ml deionized water and 2ml acetone, and magnetically stirred to obtain a colorless clear solution. 0.3638g V2O5 was weighed and added to the colorless clear solution, and magnetic stirring was continued for 4-6 hours to obtain a uniform orange-red solution. The orange-red solution was transferred to a 50ml reactor and subjected to solvent heating at 200°C for 48 hours, then removed and naturally cooled to room temperature to obtain a dark green product. The dark green product was added to an appropriate amount of deionized water and magnetically stirred to obtain a uniform suspension. The suspension was filtered and washed three times with deionized water and anhydrous ethanol, then oven-dried. The product was ground to obtain zinc ion pre-embedded layered vanadium oxide nanomaterials. At this time, the molar ratio of Zn / V is 0.024, and the molar ratio of H2V3O8 / V6O is 0.024. 13 =12.8.

[0028] Take the zinc ion pre-embedded layered vanadium oxide nanorod material as an example. Figure 1 As shown, its structure was determined by X-ray diffractometer. XRD showed that the prepared material was mainly H2V3O8 (PDF#85-2401), V6O 13 (PDF#71-2235) mixture phase. The insertion of zinc ions and solvent molecules makes the interlayer spacing of vanadium oxide crystals Time is regulated. Figure 2 As shown, scanning electron microscope (SEM) images show that the ZVO nanorods are 1 to 5 μm in length and 50 to 100 nm in width, and their morphology and size are uniform.

[0029] The ZVO nanorod material prepared in this embodiment is used as the positive electrode active material of the calcium ion battery. The preparation method of the positive electrode sheet is as follows: ZVO nanorod material is used as the positive electrode active material, Ketjen black is used as the conductive agent, polyvinylidene fluoride is used as the binder, the mass ratio of the active material, acetylene black, and polyvinylidene fluoride is 7:2:1, they are fully mixed in proportion, N-methylpyrrolidone is added and stirred thoroughly to obtain an active slurry, the slurry is coated on a hydrophilic carbon cloth, and placed in a 60°C oven to dry for 12 hours for use. The electrochemical performance test of the ZVO nanorod material is carried out by assembling a half-cell and using a three-electrode beaker cell for testing. The working electrode uses the prepared layered zinc vanadate nanomaterial, the counter electrode uses a Pt electrode, and the reference electrode uses Ag / Ag. + , the electrolyte used is 1 mol L -1 Hybrid electrolyte with Ca(ClO4)2tetraethylene glycol dimethyl ether (TEGDME):H2O=4:1 (volume ratio).

[0030] When ZVO nanorods are used as the positive electrode active material for calcium ion batteries, the scan rate is 0.2 mV s -1 Cyclic voltammograms such as Figure 3As shown in Figure 2, after the first activation cycle, the oxidation peak and reduction peak are basically the same, with good reversibility, and calcium ions can be reversibly removed and embedded in the ZVO material lattice. Figure 4 As shown, the ZVO nanorod material has excellent rate performance, with a current density from 0.2 A g -1 Gradually increase to 5A -1 , in 5A -1 The specific capacity remains stable at 61.0 mAh g at high current density. -1 , and the current density returns to 1A g -1 and 0.5A g -1 The specific capacity is not much different from that at the initial stage. Figure 5 As shown in the constant current charge and discharge test, the ZVO nanorod material was -1 After 5 cycles of activation, the initial specific capacity is 76.4 mAh g at a current density of 5Ag-1. -1 After 1000 cycles, the specific capacity is 59.8 mAh g -1 The capacity retention rate was 78.3%. These results indicate that calcium ion embedded ZVO nanorods have good rate performance and good high-rate cycling stability, making them potential application materials for calcium ion batteries.

[0031] Example 2:

[0032] The preparation method of ZVO nanorod material comprises the following steps:

[0033] 0.0368g of (CH3COO)2Zn was weighed and added to a mixture of 30ml of deionized water and 2ml of acetone. The mixture was magnetically stirred to obtain a colorless, clear solution. 0.3638g of V2O5 was weighed and added to the colorless, clear solution. Magnetic stirring was continued for 4-6 hours to obtain a uniform orange-red solution. The orange-red solution was transferred to a 50ml reactor and solvothermally heated at 200°C for 48 hours. The mixture was then removed and naturally cooled to room temperature to obtain a dark green product. The dark green product was added to an appropriate amount of deionized water and magnetically stirred to obtain a uniform suspension. The suspension was filtered and washed three times with deionized water and three times with anhydrous ethanol. The product was then oven-dried and ground to obtain a zinc ion pre-embedded layered vanadium oxide nanomaterial. At this point, the molar ratio of Zn / V was 0.044, and the molar ratio of H2V3O8 / V6O was 0. 13 =0.8.

[0034] Take the zinc ion pre-embedded layered vanadium oxide nanorod material as an example. Its structure was determined by X-ray diffractometer. XRD showed that the prepared material was mainly V6O 13 (PDF#71-2235), H2V3O8(PDF#85-2401). The insertion of zinc ions and solvent molecules makes the interlayer spacing of vanadium oxide crystals The scanning electron microscope (SEM) pictures show that the length of the ZVO nanorod is 1-5 μm and the width is 50-100 nm, and the size of the morphology is uniform.

[0035] The ZVO nanorod material prepared in the embodiment is used as a positive active material of a calcium ion battery. The preparation method of the positive electrode sheet is as follows: the ZVO nanorod material is used as the positive active material, the Ketjen black is used as the conductive agent, and the polyvinylidene fluoride is used as the binder. The mass ratio of the active material, the Ketjen black, and the polyvinylidene fluoride is 7:2:1. The materials are mixed in proportion, and N-methylpyrrolidone is added to fully stir and uniformly obtain an active slurry. The slurry is coated on a hydrophilic carbon cloth, and is placed in a 60°C oven for drying for 12 h for standby. The electrochemical performance test of the ZVO nanorod material is performed by assembling a half battery, and a three-electrode beaker battery is used for the test. The working electrode is the prepared layered ZVO nanomaterial, the counter electrode is a Pt electrode, the reference electrode is an Ag / Ag + The electrolyte is selected from 1 mol / L Ca(ClO4)2, 0.5 mol / L LiPF6, and 1 mol / L LiClO4. -1 Ca(ClO4)2 is dissolved in a hybrid system with a volume ratio of 4:1 of tetraethylene glycol dimethyl ether (TEGDME) and deionized water.

[0036] When the ZVO nanorod material is used as a positive active material of a calcium ion battery, the scanning rate is 0.2 mV s -1 The cyclic voltammogram shows that, after the first cycle of activation, the oxidation peak and the reduction peak are basically the same, and the reversibility is good. The calcium ions can be reversibly extracted and embedded in the lattice of the ZVO nanorod material. The ZVO nanorod material has excellent rate performance. The current density is gradually increased from 0.2 A / g -1 to 5 A / g -1 . The specific capacity is still stable at 58.7 mAh / g -1 at the large current density of 5 A / g -1 , and the specific capacity has little difference when the current density returns to 1 A / g -1 and 0.5 A / g -1 compared with the initial specific capacity. The results show that the calcium ion embedding in the ZVO nanorod has good rate performance, and is a potential application material of the calcium ion battery.

[0037] Comparative embodiment:

[0038] The preparation method of the ZVO nanorod material comprises the following steps:

[0039] According to the raw material ratio of Zn:V2O5=0.25:2, 0.0458g (CH3COO)2Zn was weighed and added to a mixed solution of 30ml deionized water and 2ml acetone, and magnetically stirred to obtain a colorless clear solution; 0.3638V2O5 was weighed and added to the above colorless clear solution, and magnetic stirring was continued for 4-6h to obtain a uniform orange-red solution; the orange-red solution was transferred to a 50ml reactor and solvent-heated at 200°C for 48h. Then it was taken out and naturally cooled to room temperature to obtain a dark green product; the dark green product was added to an appropriate amount of deionized water, and magnetically stirred to obtain a uniform suspension. The suspension was filtered and washed with deionized water and anhydrous ethanol 3 times each, and then dried in an oven. The product was ground to obtain zinc ion pre-embedded layered vanadium oxide nanomaterials. When the raw material ratio of Zn:V2O5 in this application is 0.1:2-0.2:2, the phase composition is Zn 2+ Pre-embedded H2V3O8 / V6O 13 When the raw material ratio Zn:V2O5=0.25:2, the composition of the phase changes to Zn 0.22 V2O5·0.94H2O. Take the zinc ion pre-embedded layered vanadium oxide nanorod material of the comparative example as an example. Its structure is determined by X-ray diffractometer. XRD shows that the prepared material is mainly Zn 0.22 V2O5·0.94H2O(PDF#88-0580). Zn 0.22 V2O5·0.94H2O is a monoclinic phase with lattice parameters Layer spacing Zn prepared in Comparative Example 0.22 V2O5·0.94H2O nanorods are used as the positive electrode active material for calcium ion batteries. The preparation method of the positive electrode sheet is as follows: Zn 0.22 V2O5·0.94H2O nanorods were used as the positive electrode active material, Ketjen black as the conductive agent, and polyvinylidene fluoride as the binder. The mass ratio of active material, acetylene black, and polyvinylidene fluoride was 7:2:1. They were fully mixed according to the proportion, and N-methylpyrrolidone was added and stirred thoroughly to obtain an active slurry. The slurry was coated on a hydrophilic carbon cloth and placed in a 60°C oven to dry for 12 hours before use. Zn 0.22 The electrochemical performance test of V2O5·0.94H2O nanorod material was carried out by assembling a half-cell and using a three-electrode beaker cell. The working electrode was the prepared layered Zn 0.22 V2O5·0.94H2O nanomaterials, Pt electrode as counter electrode, Ag / Ag as reference electrode + , the electrolyte is 1 mol L -1 Ca(ClO4)2 was dissolved in a hybrid system of tetraethylene glycol dimethyl ether (TEGDME) and deionized water in a volume ratio of 4:1.

[0040] Zn used 0.22 When V2O5·0.94H2O nanorods are used as positive electrode active materials for calcium ion batteries, Zn 0.22 V2O5·0.94H2O nanorods have excellent rate performance, with current densities of 0.2, 0.5, 1, 2, and 5 A g -1 The corresponding specific capacities are 106, 85, 72, 60, and 37 mAh g -1 , and the current density returns to 1A g -1 The specific capacity is 70 mAh g -1 , which is not much different from the initial specific capacity. This result shows that calcium ions are embedded in Zn 0.22 The rate performance of V2O5·0.94H2O nanorods is inferior to that of Zn in Examples 1 and 2. 2+ Pre-embedded H2V3O8 / V6O 13 Nanorods.

[0041] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the foregoing embodiments. The foregoing embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A zinc ion embedded layered vanadium oxide nanomaterial, characterized in that: The material composition is Zn 2+ Pre-embedded H2V3O8 / V6O 13 , Among them, the actual embedded zinc-vanadium ratio Zn / V=0.025~0.1, the molar ratio H2V3O8 / V6O 13 = 0.8~12.8, the preparation method of the nano material comprises the following steps: S01, weighing a zinc source and adding it to a mixed solution of deionized water and ketone, stirring to obtain a colorless clear solution; S02, weighing a vanadium source and adding it to the above colorless clear solution, wherein the molar ratio of the zinc source to the vanadium source is 0.1-0.2:2, and continuing stirring for 4-6 hours to obtain a uniform orange-red solution; S03, transferring the orange-red solution obtained in S02 to a reactor for solvothermal reaction, and then taking it out and naturally cooling it to room temperature to obtain a dark green product; S04, adding an appropriate amount of deionized water to the dark green product obtained in S03 and stirring to form a uniform suspension; S05, filtering the suspension obtained in S04, washing it with deionized water and anhydrous ethanol, drying it, and finally grinding the product to obtain zinc ion pre-embedded layered vanadium oxide nanomaterials.

2. The zinc ion embedded layered vanadium oxide nanomaterial according to claim 1, characterized in that: The nanomaterial has a diameter of 50-100 nm and a length of 1-5 μm.

3. The method for preparing a zinc ion embedded layered vanadium oxide nanomaterial according to claim 1, characterized in that: The following steps are involved: S01, weighing a zinc source and adding it to a mixed solution of deionized water and ketone, stirring to obtain a colorless clear solution; S02, weighing a vanadium source and adding it to the above colorless clear solution, wherein the molar ratio of the zinc source to the vanadium source is 0.1-0.2:2, and continuing stirring for 4-6 hours to obtain a uniform orange-red solution; S03, transferring the orange-red solution obtained in S02 to a reactor for solvothermal reaction, and then taking it out and naturally cooling it to room temperature to obtain a dark green product; S04, adding an appropriate amount of deionized water to the dark green product obtained in S03 and stirring to form a uniform suspension; S05, filtering the suspension obtained in S04, washing it with deionized water and anhydrous ethanol, drying it, and finally grinding the product to obtain zinc ion pre-embedded layered vanadium oxide nanomaterials.

4. The method for preparing a zinc ion embedded layered vanadium oxide nanomaterial according to claim 3, characterized in that: The zinc source in S01 is one of ZnSO4, Zn(CH3COO)2, and ZnCl2, and the ketone is one of acetone, butanone, and cyclohexanone.

5. The method for preparing a zinc ion embedded layered vanadium oxide nanomaterial according to claim 3, characterized in that: The vanadium source in S02 is V2O5.

6. The method for preparing a zinc ion embedded layered vanadium oxide nanomaterial according to claim 3, characterized in that: The solvent thermal temperature in S03 is 180-210° C., and the solvent thermal time is 48 h-96 h.

7. The use of a zinc ion embedded layered vanadium oxide nanomaterial according to claim 1, characterized in that: The nanomaterial is used as a positive electrode active material for calcium ion batteries.

8. An application of zinc ion embedded layered vanadium oxide nanomaterials, characterized in that: The calcium ion battery consists of a working electrode, a counter electrode, a reference electrode and an electrolyte, wherein the working electrode is the zinc ion embedded layered vanadium oxide nanomaterial according to claim 1, and the counter electrode is Pt or activated carbon.

9. The use of the nanomaterial according to claim 8, characterized in that: The electrolyte is a hybrid electrolyte of an organic solvent containing calcium ions and water.

10. The use of the nanomaterial according to claim 9, characterized in that: The volume ratio of the organic solvent to water is 4:1.

Images