A magnesium ion-doped VO2(B) material, its preparation method and application

Abstract

The application discloses a magnesium ion doped VO2(B) material and a preparation method and application thereof. When the magnesium ion doped VO2(B) material is prepared, the molar ratio of a soluble magnesium salt to vanadium pentoxide is 5:65-40:65, and a regulation of regulating the morphology and electrochemical performance of the magnesium ion doped VO2(B) positive electrode material is provided. The magnesium ion is doped into the VO2(B) positive electrode material, so that the interlayer spacing of the material itself is increased and a more stable structure is provided, and the rate performance and cycle stability are greatly improved, which has important research significance.

Description

Technical Field

[0001] This invention relates to the field of battery materials technology, and more specifically, to a magnesium ion-doped VO2(B) material for the cathode of an aqueous zinc-ion battery, its preparation and application. Background Technology

[0002] In recent years, significant progress has been made in the development of new energy technologies, particularly rechargeable batteries. Currently, lithium-ion batteries are widely used in commercial energy storage devices due to their high energy transfer efficiency, high voltage, and long cycle life; however, their high cost and safety issues severely hinder large-scale application. Aqueous zinc-ion batteries, with their high conductivity, abundant zinc resources, high chemical and physical stability, environmental friendliness, and high safety, have broad application prospects and are considered a very promising alternative in next-generation energy storage technologies.

[0003] The performance of the cathode material in aqueous zinc-ion batteries has a significant impact on the overall performance of the battery. Developing high-performance cathode materials is crucial for the development of zinc-ion batteries. Currently, manganese-based, vanadium-based, and Prussian blue-like electrode materials are among the most researched cathode materials. However, all types of zinc-ion battery cathode materials share the common problem of poor conductivity, resulting in low cycle life and rate performance. This has become one of the bottlenecks restricting the widespread application of zinc-ion batteries.

[0004] VO2(B) possesses an open, tunnel-like framework, enabling rapid insertion and extraction of zinc ions, making it an ideal candidate cathode material for zinc-ion batteries. However, the development of VO2 / Zn batteries still faces some challenges:

[0005] 1) Solvable Zn with large ionic radius and high divalent charge 2+ Sufficient insertion space and a more stable cathode structure are required; otherwise, the cathode structure may collapse.

[0006] 2) Most vanadium-based materials have poor electrical conductivity and poor solubility in aqueous solutions, which directly leads to capacity loss and unsatisfactory electrochemical performance.

[0007] 3) The smaller specific surface area leads to a slower rate of zinc ion insertion / extraction.

[0008] There are generally two ways to solve these problems. One way is to increase the interlayer spacing by inserting ions / molecules to accelerate the insertion / extraction of zinc ions. The other way is to increase the conductivity of the material by coating it with conductive composite materials.

[0009] This invention synthesizes magnesium ion-doped VO2(B) cathode material using a hydrothermal method. It proposes adding different amounts of soluble magnesium salts to the hydrothermal process, allowing magnesium ions to be incorporated into the VO2(B) cathode material. This increases the interlayer spacing of the material and provides a more stable structure, significantly improving rate performance and cycle stability, and has important research significance. Summary of the Invention

[0010] The primary objective of this invention is to provide a method for preparing magnesium ion-doped VO2(B) cathode material, which expands the interlayer spacing of VO2 and provides a more stable structure, significantly improving capacity, rate performance and cycle stability. Furthermore, the invention proposes a method for regulating the morphology and electrochemical performance of magnesium ion-doped VO2(B) cathode material.

[0011] A method for preparing magnesium ion-doped VO2(B) materials involves a hydrothermal reaction of a mixed solution of a soluble reducing agent, vanadium pentoxide, and a soluble magnesium salt.

[0012] In the method described, the molar ratio of soluble magnesium salt to vanadium pentoxide is 5:65 to 40:65, preferably 10:65 to 20:65.

[0013] In the method described, the V / C molar ratio of the soluble reducing agent to vanadium pentoxide is 1:0.5 to 1:5, preferably 1:0.5 to 1:3.

[0014] The method comprises at least one of Mg(NO3)2, MgCl2·6H2O, MgSO4 and Mg(CH3COO)2 and their hydrates.

[0015] The method described herein uses a hydrothermal synthesis temperature of 120–220°C, preferably 150–180°C, and a time of 8–48 h, preferably 12–18 h.

[0016] The method comprises at least one of glucose, sucrose, oxalic acid, hydrazine hydrate, fructose, and vitamin C.

[0017] The product after hydrothermal reaction is washed, filtered, and dried.

[0018] The product washing reagents include deionized water, methanol, ethanol, and N,N dimethylamide, with water and ethanol being preferred.

[0019] Furthermore, the washed product needs to be filtered and then vacuum dried at a temperature of 60-100℃ for 12-24 hours.

[0020] Preferred method: Preparation method of magnesium ion-doped VO2(B) nanomaterials, comprising the following steps:

[0021] 1) Dissolve the soluble magnesium salt in 10 ml of deionized water and sonicate until completely dissolved to prepare solution A;

[0022] 2) Dissolve the soluble reducing agent in 20 ml of deionized water and sonicate until completely dissolved to prepare solution B;

[0023] 3) Dissolve commercial vanadium pentoxide in 20 ml of deionized water and sonicate until completely dissolved to prepare solution C;

[0024] 4) Mix liquids A, B and C, heat in an oil bath for 2 hours, and then transfer to a stainless steel reactor with a polytetrafluoroethylene liner for a one-step hydrothermal reaction.

[0025] 5) After the reaction process is complete, the solution is centrifuged, washed three times with water and ethanol respectively, and dried at 80℃ for 24h to obtain magnesium ion-doped VO2(B) nanomaterials.

[0026] Preferably, the soluble magnesium salt in step 1) is one or more of Mg(NO3)2·6H2O, MgCl2·6H2O and MgSO4·7H2O;

[0027] Preferably, the soluble reducing agent in step 2) is one or more of glucose, sucrose, and oxalic acid;

[0028] Preferably, the hydrothermal synthesis temperature in step 4) is 160℃~180℃, and the time is 12h~18h.

[0029] A second objective of this invention is to provide a magnesium ion-doped VO2(B) material prepared by the method described above. This material is based on zinc-based VO2(B), with magnesium ions inserted into the crystal lattice of the host material. The particle size range of the nanomaterial is 100 nm to 2000 nm.

[0030] A third objective of this invention is to provide the application of the aforementioned magnesium ion-doped VO2(B) material, characterized in that it is used to prepare battery cathode materials; and used to prepare zinc ion battery cathode materials.

[0031] Furthermore, the following steps are taken to prepare the zinc-ion battery cathode sheet:

[0032] 1) Mix magnesium ion-doped VO2(B) nanomaterials, acetylene black and polyvinylidene fluoride in a ratio of 7:2:1, and then apply the mixture evenly onto titanium foil after preparing it into a paste with N-methylpyrrolidone.

[0033] 2) Dry in a vacuum oven at 100°C for 12 hours.

[0034] The testing methods for the electrochemical performance of electrode materials are as follows:

[0035] 1) The simulated battery adopts the CR2025 button cell system, the electrolyte is a 1M zinc sulfate aqueous solution, the negative electrode is a circular zinc sheet, and the battery separator is glass fiber;

[0036] 2) The reversible capacity and cycle performance of the electrode material were tested and analyzed using constant current charge and discharge. The charge and discharge regime was as follows: voltage range: 0.3 to 1.4V; cycle number: generally 1 to 1000 times.

[0037] The fourth objective of this invention is to provide a battery or zinc-ion battery prepared from a cathode made of the aforementioned magnesium ion-doped VO2(B) material.

[0038] Due to the implementation of the above technical solutions, the present invention has the following advantages compared with the prior art:

[0039] The magnesium ion-doped VO2(B) nanomaterials obtained in this invention expand the interlayer spacing of VO2, increase the specific surface area of ​​the electrode material in contact with the electrolyte, provide more active sites for the insertion and extraction of zinc ions, significantly improve the capacity and rate performance of the cathode material, and the addition of magnesium ions provides support for the material, improves the stability of the material structure, and improves the cycle stability of the cathode material. Attached Figure Description

[0040] Figure 1 XRD patterns of magnesium ion-doped VO2(B) nanomaterials prepared with different doping amounts.

[0041] Figure 2 SEM images of magnesium ion-doped VO2(B) nanomaterials prepared with different doping amounts: (ab) 0.5 mmol magnesium salt doping; (cd) 1 mmol magnesium salt doping; (ef) 2 mmol magnesium salt doping; (gh) 3 mmol magnesium salt doping; (ij) 4 mmol magnesium salt doping.

[0042] Figure 3 EDS image of magnesium ion-doped VO2(B) nanomaterials prepared in Example 1.

[0043] Figure 4 The figures show the electrochemical performance characterization of the materials prepared in Example 1 and Comparative Example 1.

[0044] Figure 5 Electrochemical performance characterization diagrams of magnesium ion-doped VO2(B) nanomaterials prepared with different doping amounts. Figure 5 (a) Different magnesium ion doping concentrations in 1Ag -1 Electrochemical cycling performance at current density; Figure 5 (b) Electrochemical impedance at different magnesium ion doping levels; Figure 5 (c) Different magnesium ion doping concentrations in 1Ag -1Initial specific capacity plot at current density; Figure 5 (d) Different magnesium ion doping concentrations in 1 Ag -1 Capacity retention rate after 100 cycles at current density. Detailed Implementation

[0045] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field.

[0046] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0047] Example 1

[0048] A method for preparing magnesium ion-doped VO2(B) nanomaterials includes the following steps:

[0049] Step 1: Dissolve 2 mmol Mg(NO3)2·6H2O in 10 ml deionized water and sonicate until completely dissolved to prepare solution A;

[0050] Step 2: Dissolve 1.8g of soluble reducing agent oxalic acid in 20ml of deionized water and sonicate until completely dissolved to prepare solution B;

[0051] Step 3: Dissolve 1.2g of commercial vanadium pentoxide in 20ml of deionized water and sonicate until completely dissolved to prepare solution C;

[0052] Step 4: Mix liquids A, B and C, heat in an oil bath for 2 hours, then transfer to a stainless steel reactor with a polytetrafluoroethylene liner, and carry out a one-step hydrothermal reaction at 160℃ for 12 hours.

[0053] Step 5: After the reaction process is complete, centrifuge the solution, wash it three times with water and ethanol respectively, and dry it at 80℃ for 24 hours to obtain magnesium ion-doped VO2(B) nanomaterials.

[0054] To verify the electrochemical performance of magnesium ion-doped VO2(B) nanomaterials, their application as a positive electrode material in zinc-ion batteries was further investigated. The prepared magnesium ion-doped VO2(B) nanomaterials, along with a binder and a conductive agent, were dissolved in N-methylpyrrolidone to form a slurry. This slurry was then coated onto stainless steel foil, vacuum dried, and used as an electrode material to assemble zinc-ion batteries. Electrochemical performance testing revealed an activated capacity of 315.4 mAh g at a current density of 1 A / g. -1 After 100 cycles, the capacity retention rate was 92.73%.

[0055] Example 2

[0056] A method for preparing magnesium ion-doped VO2(B) nanomaterials includes the following steps:

[0057] Step 1: Dissolve 0.5 mmol Mg(NO3)2·6H2O in 10 ml of deionized water and sonicate until completely dissolved to prepare solution A;

[0058] Step 2: Dissolve 1.8g of soluble reducing agent oxalic acid in 20ml of deionized water and sonicate until completely dissolved to prepare solution B;

[0059] Step 3: Dissolve 1.2g of commercial vanadium pentoxide in 20ml of deionized water and sonicate until completely dissolved to prepare solution C;

[0060] Step 4: Mix liquids A, B and C, heat in an oil bath for 2 hours, then transfer to a stainless steel reactor with a polytetrafluoroethylene liner, and carry out a one-step hydrothermal reaction at 160℃ for 12 hours.

[0061] Step 5: After the reaction process is complete, centrifuge the solution, wash it three times with water and ethanol respectively, and dry it at 80℃ for 24 hours to obtain magnesium ion-doped VO2(B) nanomaterials.

[0062] To verify the electrochemical performance of magnesium ion-doped VO2(B) nanomaterials, their application as a positive electrode material in zinc-ion batteries was further investigated. The prepared magnesium ion-doped VO2(B) nanomaterials, along with a binder and conductive agent, were dissolved in N-methylpyrrolidone to form a slurry. This slurry was then coated onto stainless steel foil, vacuum dried, and used as an electrode material to assemble zinc-ion batteries. Electrochemical performance testing revealed an activated capacity of 244.7 mAh g at a current density of 1 A / g. -1 After 100 cycles, the capacity retention rate was 60.48%.

[0063] Example 3

[0064] A method for preparing magnesium ion-doped VO2(B) nanomaterials includes the following steps:

[0065] Step 1: Dissolve 1 mmol Mg(NO3)2·6H2O in 10 ml deionized water and sonicate until completely dissolved to prepare solution A;

[0066] Step 2: Dissolve 1.8g of soluble reducing agent oxalic acid in 20ml of deionized water and sonicate until completely dissolved to prepare solution B;

[0067] Step 3: Dissolve 1.2g of commercial vanadium pentoxide in 20ml of deionized water and sonicate until completely dissolved to prepare solution C;

[0068] Step 4: Mix liquids A, B and C, heat in an oil bath for 2 hours, then transfer to a stainless steel reactor with a polytetrafluoroethylene liner, and carry out a one-step hydrothermal reaction at 160℃ for 12 hours.

[0069] Step 5: After the reaction process is complete, centrifuge the solution, wash it three times with water and ethanol respectively, and dry it at 80℃ for 24 hours to obtain magnesium ion-doped VO2(B) nanomaterials.

[0070] To verify the electrochemical performance of magnesium ion-doped VO2(B) nanomaterials, their application as a positive electrode material in zinc-ion batteries was further investigated. The prepared magnesium ion-doped VO2(B) nanomaterials, along with a binder and conductive agent, were dissolved in N-methylpyrrolidone to form a slurry. This slurry was then coated onto stainless steel foil, vacuum dried, and used as an electrode material to assemble zinc-ion batteries. Electrochemical performance testing revealed an activated capacity of 277.8 mAh g at a current density of 1 A / g. -1 After 100 cycles, the capacity retention rate was 65.15%.

[0071] Example 4

[0072] A method for preparing magnesium ion-doped VO2(B) nanomaterials includes the following steps:

[0073] Step 1: Dissolve 3 mmol Mg(NO3)2·6H2O in 10 ml deionized water and sonicate until completely dissolved to prepare solution A;

[0074] Step 2: Dissolve 1.8g of soluble reducing agent oxalic acid in 20ml of deionized water and sonicate until completely dissolved to prepare solution B;

[0075] Step 3: Dissolve 1.2g of commercial vanadium pentoxide in 20ml of deionized water and sonicate until completely dissolved to prepare solution C;

[0076] Step 4: Mix liquids A, B and C, heat in an oil bath for 2 hours, then transfer to a stainless steel reactor with a polytetrafluoroethylene liner, and carry out a one-step hydrothermal reaction at 160℃ for 12 hours.

[0077] Step 5: After the reaction process is complete, centrifuge the solution, wash it three times with water and ethanol respectively, and dry it at 80℃ for 24 hours to obtain magnesium ion-doped VO2(B) nanomaterials.

[0078] To verify the electrochemical performance of magnesium ion-doped VO2(B) nanomaterials, their application as a positive electrode material in zinc-ion batteries was further investigated. The prepared magnesium ion-doped VO2(B) nanomaterials, along with a binder and conductive agent, were dissolved in N-methylpyrrolidone to form a slurry. This slurry was then coated onto stainless steel foil, vacuum dried, and used as an electrode material to assemble zinc-ion batteries. Electrochemical performance testing revealed an activated capacity of 205.4 mAh g at a current density of 1 A / g. -1 After 100 cycles, the capacity retention rate was 91.41%.

[0079] Example 5

[0080] A method for preparing magnesium ion-doped VO2(B) nanomaterials includes the following steps:

[0081] Step 1: Dissolve 4 mmol Mg(NO3)2·6H2O in 10 ml of deionized water and sonicate until completely dissolved to prepare solution A;

[0082] Step 2: Dissolve 1.8g of soluble reducing agent oxalic acid in 20ml of deionized water and sonicate until completely dissolved to prepare solution B;

[0083] Step 3: Dissolve 1.2g of commercial vanadium pentoxide in 20ml of deionized water and sonicate until completely dissolved to prepare solution C;

[0084] Step 4: Mix liquids A, B and C, heat in an oil bath for 2 hours, then transfer to a stainless steel reactor with a polytetrafluoroethylene liner, and carry out a one-step hydrothermal reaction at 160℃ for 12 hours.

[0085] Step 5: After the reaction process is complete, centrifuge the solution, wash it three times with water and ethanol respectively, and dry it at 80℃ for 24 hours to obtain magnesium ion-doped VO2(B) nanomaterials.

[0086] To verify the electrochemical performance of magnesium ion-doped VO2(B) nanomaterials, their application as a positive electrode material in zinc-ion batteries was further investigated. The prepared magnesium ion-doped VO2(B) nanomaterials, along with a binder and a conductive agent, were dissolved in N-methylpyrrolidone to form a slurry. This slurry was then coated onto stainless steel foil, vacuum dried, and used as an electrode material to assemble zinc-ion batteries. Electrochemical performance testing revealed an activated capacity of 171.6 mAh g at a current density of 1 A / g. -1 After 100 cycles, the capacity retention rate was 91.49%.

[0087] Comparative Example 1

[0088] A method for preparing VO2 nanomaterials includes the following steps:

[0089] Step 1: Dissolve 1.8g of soluble reducing agent (oxalic acid) in 25mL of deionized water and stir until homogeneous to obtain solution A.

[0090] Step 2: Dissolve 1.2g of commercial vanadium pentoxide in 25mL of deionized water and stir until homogeneous to obtain solution B.

[0091] Step 3: Mix solution A and solution B to obtain solution D, stir at room temperature for 2 hours, then transfer solution C to a stainless steel reactor with a polytetrafluoroethylene liner and carry out hydrothermal reaction at 160°C for 12 hours. After the reaction is completed, wash the product three times with deionized water, twice with ethanol, filter, dry at 60°C for 12 hours to obtain pure VO2 nanomaterials.

[0092] To verify the electrochemical performance of pure VO2 nanomaterials, their application as a positive electrode material in zinc-ion batteries was further investigated: the prepared VO2 nanomaterials, binder, and conductive agent were dissolved in N-methylpyrrolidone to prepare a slurry, which was then coated onto titanium foil. After vacuum drying, the slurry was used as an electrode material to assemble a zinc-ion battery. Electrochemical performance testing revealed an activated capacity of 250.7 mAh g at a current density of 1 A / g. -1 After 100 cycles, the capacity retention rate was 66.62%.

[0093] Figure 1 XRD patterns of VO2(B) doped with different amounts of Mg are presented. It can be seen that the 25.6° diffraction peak corresponds to the main peak of each sample, indicating the synthesis of VO2(B). No diffraction peak of MgV2O5 is observed when the magnesium doping concentration is 0.5 mmol and 1 mmol, indicating that magnesium ions exist in the vacancy of VO2(B) in a free form. When the magnesium doping concentration reaches 2 mmol, a diffraction peak of MgV2O5 at the 18.2° position begins to appear, and with the increase of magnesium doping concentration, the 25.6° diffraction peak shifts to the right, indicating the presence of free Mg ions in the vacancy. 2+ By combining with O to form Mg-O bonds, the intensity of the diffraction peak of MgV2O5 continuously increases.

[0094] Figure 2 SEM images of VO2(B) doped with different amounts of Mg are presented. When the doping concentration is 0.5 mmol and 1.0 mmol, the primary particles are all composed of elongated nanosheets with some agglomeration, formed by the stacking of nanosheet particles. When the doping concentration is 2.0 mmol, the primary particles are composed of nanosheets, which expand outwards to form nanoflower-like particles, greatly increasing the contact area with the electrolyte. When the doping concentration is 3.0 mmol and 4.0 mmol, the primary particles transform into small nanobulb particles with more agglomeration, also composed of small nanobulb particles. With increasing magnesium doping concentration, Mg... xThe morphology of HVO exhibits a phenomenon of first agglomeration, then dispersion, and then agglomeration again. The composition morphology changes from solid to nano-flower-like and then back to solid, indicating that changes in magnesium doping content have a significant impact on VO2(B) modification.

[0095] In addition, EDS-mapping images such as Figure 3 As shown, V, O, and Mg elements can be observed to be uniformly distributed in Mg. 2.0 In HVO.

[0096] Mg 2.0 HVO and VO2 in 1A g -1 The discharge curve below is as follows Figure 4 As shown, after 100 cycles, Mg 2.0 The capacity retention rates of HVO and VO2 were 92.73% and 66.62%, respectively, and Mg... 2+ The insertion significantly improved the first-cycle specific capacity and cycling stability.

[0097] Figure 5 Different Mg 2+ The doping amount affects its electrochemical performance. When the doping amount is 2 mmol, the MgHVO / Zn battery achieves the lowest impedance, the highest initial capacity, and the highest capacity retention. When the doping amount is less than 2 mmol, it has a high capacity but a low capacity retention; when the doping amount is greater than 2 mmol, it has a high capacity retention but a low capacity.

Claims

1. A method for preparing magnesium ion-doped VO2(B) materials, characterized in that, The solution is obtained by hydrothermal reaction of a mixed solution of soluble reducing agent, vanadium pentoxide, and soluble magnesium salt; the molar ratio of soluble magnesium salt to vanadium pentoxide is 5:65~40:65, and the V / C molar ratio of soluble reducing agent to vanadium pentoxide is 1:0.5~1:

5.

2. The method according to claim 1, characterized in that, The molar ratio of soluble magnesium salt to vanadium pentoxide is 10:65 to 20:

65.

3. The method according to claim 1, characterized in that, The V / C molar ratio of the soluble reducing agent to vanadium pentoxide is 1:0.5~1:

3.

4. The method according to claim 1, characterized in that, Soluble magnesium salts include at least one of Mg(NO3)2, MgCl2·6H2O, MgSO4, and Mg(CH3COO)2 and their hydrates.

5. The method according to claim 1, characterized in that, The hydrothermal synthesis temperature is 120~220℃, and the time is 8~48h.

6. The method according to claim 1, characterized in that, Soluble reducing agents include at least one of glucose, sucrose, oxalic acid, hydrazine hydrate, fructose, and vitamin C.

7. The magnesium ion-doped VO2(B) material prepared by the method according to any one of claims 1-6.

8. The application of the magnesium ion-doped VO2(B) material according to claim 7, characterized in that, Used to prepare battery cathode materials.

9. The application according to claim 8, characterized in that, Used to prepare positive electrode materials for zinc-ion batteries.

10. A battery, characterized in that, It is prepared from the positive electrode made of the magnesium ion-doped VO2(B) material as described in claim 7.

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