An Al 3+ Coated sodium vanadate nanocomposite, preparation method and application thereof

Abstract

This invention belongs to the field of battery cathode material technology, specifically relating to an Al 3+ Sodium vanadate-coated nanocomposites, their preparation methods, and applications. The Al... 3+ Sodium vanadate-coated nanocomposite material, made of Al 3+ The sodium vanadate is coated to obtain the product. The vanadium in the sodium vanadate is pentavalent. Under bridging and coordination, the pentavalent vanadium self-assembles to form a polynuclear vanadium-oxygen cluster anion [V6O]. 16 ] 2‑ Al 3+ [V6O] on the surface of sodium vanadate 16 ] 2‑ The formation of surface complexes of the type =Al-O-V≡ coats sodium vanadate, forming Al 3+ Vanadic acid-coated nanocomposite materials. The Al of this invention... 3+ @NVO has a stable structure, and the batteries made from it have high discharge capacity and high rate performance.

Description

Technical Field

[0001] This invention belongs to the field of battery cathode material technology, specifically relating to an Al 3+ Sodium vanadate-coated nanocomposites, their preparation methods, and applications. Background Technology

[0002] Current electrode materials include Prussian blue analogues, manganese-based materials, vanadium-based materials, and metal sulfide materials. Among these, vanadium-based materials, when used as electrodes in zinc batteries, cause zinc ions to repeatedly insert and extract into the electrode during charge-discharge cycles. This makes the crystal structure of the cathode material prone to irreversible phase transitions, dissolution, or collapse, leading to rapid capacity decay and shortened cycle life. Furthermore, zinc ions carry two positive charges, resulting in strong electrostatic interactions with the cathode material's crystal lattice. This leads to a high ion diffusion barrier and slow migration rate, limiting the battery's rate performance and resulting in low rate capability.

[0003] Therefore, existing zinc battery electrode materials have short cycle life, resulting in low rate performance of the batteries they produce. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides an Al 3+ Sodium vanadate-coated nanocomposites, their preparation methods, and applications.

[0005] To facilitate understanding of this invention, the materials used in this invention and their abbreviations are listed below: Sodium vanadate hydrate, chemical formula Na₂V₆O 16 ·3H₂O, abbreviated as NVO₄. Al 3+ Vanadic acid nanocomposite material, abbreviated as Al 3+ @NVO.

[0006] The first objective of this invention is to provide an Al 3+ @NVO, by Al 3+ It is obtained by coating sodium vanadate hydrate.

[0007] Sodium vanadate hydrate is produced by reacting V2O5 and Na2C2O4.

[0008] The vanadium in the sodium vanadate is pentavalent. Under bridging and coordination, the pentavalent vanadium self-assembles to form a polynuclear vanadium-oxygen cluster anion [V6O]. 16 ] 2- Al 3+ [V6O] on the surface of sodium vanadate 16 ] 2- Forming a surface complex of type =Al-OV≡, coating sodium vanadate to form Al 3+ Vanadic acid-coated nanocomposite materials. Al 3+Sodium vanadate nanomaterials exist primarily as coordination bonds on their surface, providing more active sites for the composite material and improving interfacial kinetics. Simultaneously, the sodium vanadate surface acts as a barrier, reducing elemental dissolution during cycling.

[0009] Preferably, the preparation method of the hydrated sodium vanadate includes the following steps: dissolving V₂O₅ in a 1.5M~2.5M Na₂C₂O₄ solution, stirring at 300rpm~500rpm for 60h~84h in a water bath at 20℃~40℃, until the solution changes from orange-yellow to dark brown, filtering and washing, and drying at 70℃~85℃ for 8h~14h to obtain hydrated sodium vanadate. Oxalate reacts with V₂O₅ under acidic conditions: V₂O₅ + Na₂C₂O₄ + 4H⁺ + →2VO 2+ +2Na + +2CO2+2H2O, where the generated VO 2+ It will react with unreduced VO in the solution 3- A hydrolysis-condensation reaction occurs, and under the bridging and coordination of oxalate ions, it self-assembles to form a complex polynuclear vanadium-oxygen cluster anion [V6O]. 16 ] 2- It makes the solution turn dark brown.

[0010] Preferably, the molar ratio of V2O5, Na2C2O4 and [other substances] is 16:200.

[0011] Preferably, the concentration of the Na2C2O4 solution is 2M.

[0012] Preferably, the drying temperature is 80°C and the time is 12 hours.

[0013] The second objective of this invention is to provide an Al 3+ The preparation method of @NVO includes the following steps: Al(OH)3 and NVO were dissolved in water, stirred for 20-40 minutes, reacted at 100-140℃ for 2-5 hours, cooled, filtered and washed, and dried at 70-85℃ for 8-14 hours to obtain Al. 3+ @NVO. [V6O] 16 ] 2- The bridging oxygen or terminal oxygen in Al(OH)3 can react with Al on the surface of Al. 3+ Coordination forms surface complexes of the type =Al-OV≡.

[0014] The molar ratio of V2O5 to Na2C2O4 is 12~20:150~250.

[0015] The Al(OH)3 and Na2V6O 16The molar ratio of ·3H2O is 0.2~0.8:2.

[0016] Preferably, the concentration of sodium vanadate hydrate after Al(OH)3 and sodium vanadate hydrate are dissolved in water is 0.04M~0.06M.

[0017] Preferably, the molar ratio of Al(OH)3 to NVO is 0.4:1.

[0018] Preferably, the concentration of the NVO solution is 0.05M.

[0019] Preferably, the reaction temperature is 120°C and the reaction time is 3 hours.

[0020] The third objective of this invention is to provide an Al 3+ Application of @NVO in the preparation of positive electrode sheets for batteries.

[0021] Preferably, the positive electrode sheet is prepared by the following method: Nanocomposite materials, activated carbon, and polyvinylidene fluoride were ground and mixed in a mass ratio of 7:2:1 to obtain an active slurry. The active slurry was coated onto carbon paper and dried at 80°C for 12 hours to obtain a positive electrode sheet.

[0022] Compared with the prior art, the present invention has the following beneficial effects: 1. The Al of the present invention 3+ @NVO, by Al 3+ It is obtained by coating with sodium vanadate. (From Al) 3+ Sodium vanadate hydrate is obtained by coating. Sodium vanadate hydrate is prepared by the reaction of V₂O₅ and Na₂C₂O₄. Oxalate ions react with V₂O₅ under acidic conditions: V₂O₅ + Na₂C₂O₄ + 4H⁺ → 2VO⁻ 2+ +2Na + +2CO2+2H2O,VO 2+ It does not exist alone; it will combine with unreduced VO in the solution. 3- A hydrolysis-condensation reaction occurs, and under the bridging and coordination of oxalate ions, it self-assembles to form a polynuclear vanadium oxide cluster anion [V6O]. 16 ] 2- Al 3+ [V6O] on the surface of sodium vanadate 16 ] 2- Forming a surface complex of the type =Al-OV≡, sodium vanadate is coated to obtain Al 3+ @NVO. Al 3+ Sodium vanadate nanomaterials mainly exist in the form of coordination bonds on their surface, forming Al. 3+@NVO provides active sites, improving interfacial dynamics and enabling the material to maintain high capacity even at high current densities. Simultaneously, Al2O3 coated on the sodium vanadate surface... 3+ It acts as a barrier, helping to form a more stable electrode-electrolyte interface, reducing charge transfer resistance, lowering electrode polarization, and reducing element dissolution during cycling. 3+ The coating reduces the direct contact between the active material and the electrolyte, effectively inhibiting the dissolution of vanadium ions, thereby maintaining Al 3+ The structural integrity of @NVO. Therefore, the Al of the present invention 3+ The @NVO electrode has a long cycle life, with a capacity retention of about 96.6% after 1000 cycles, which is higher than the 69.6% capacity retention of the NVO electrode. The battery has high rate performance, and can still maintain 64.8% of the capacity at 1A / g under a high current density of 10A / g, which is better than the 59.3% of the NVO electrode.

[0023] 2. The Al of the present invention 3+ The preparation method of @NVO includes the following steps: Al(OH)3 and Na2V6O 16 Dissolve 3H₂O in water, stir for 20-40 minutes, react at 100-140℃ for 2-5 hours, cool, filter and wash, and dry at 70-85℃ for 8-14 hours to obtain the nanocomposite material. [V₆O] 16 ] 2- The bridging oxygen or terminal oxygen in Al(OH)3 can react with Al on the surface of Al. 3+ Coordination forms a surface complex of the type =Al-OV≡. The molar ratio of V₂O₅ to Na₂C₂O₄ is 12-20:2000. The Al(OH)₃ and Na₂V₆O₄... 16 The molar ratio of ·3H₂O is 0.2~0.8:2. The Al of this invention... 3+ The preparation method of @NVO uses widely available and easily obtained raw materials, and the reaction conditions are simple and easy to control. Therefore, the Al of this invention... 3+ The preparation method of @NVO can be easily realized for large-scale commercial production. Attached Figure Description

[0024] Figure 1 Al prepared in Example 1 of this invention 3+ SEM images of NVO and NVO prepared in Comparative Example 1. Where a is the SEM image of NVO, and b is the SEM image of Al. 3+ SEM image of @NVO.

[0025] Figure 2 Al prepared in Example 1 of this invention 3+ XRD patterns of NVO and NVO prepared in Comparative Example 1.

[0026] Figure 3 Al prepared in Example 1 of the present invention 3+ Discharge cycle test diagrams of zinc batteries made from NVO and NVO prepared in Comparative Example 1.

[0027] Figure 4 Al prepared in Examples 1 to 3 of this invention 3+ The charge-discharge cycle rate performance of zinc batteries prepared with @NVO and NVO prepared in Comparative Example 1.

[0028] Figure 5 Al of the present invention 3+ High-resolution XPS spectra of elemental Al.

[0029] Figure 6 Al prepared in Example 1 of the present invention 3+ Zn in zinc batteries made from NVO and NVO prepared in Comparative Example 1 2+ The diffusion coefficient diagram during the discharge process.

[0030] Figure 7 Al prepared in Example 1 of the present invention 3+ Zn in zinc batteries made from NVO and NVO prepared in Comparative Example 1 2+ The diffusion coefficient diagram during the charging process. Detailed Implementation

[0031] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the following detailed description, in conjunction with preferred embodiments and accompanying drawings, provides a clear and complete account of the technical solutions of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0032] It should be noted that all technical terms used in this invention are for the purpose of describing specific embodiments only and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the following embodiments of this invention can be purchased from the market or prepared by existing methods.

[0033] The main materials used in this invention are V2O5, Na2C2O4, Al(OH)3, activated carbon, polyvinylidene fluoride, carbon paper, glass fiber diaphragm, and Zn(CF3SO3)2 electrolyte.

[0034] Among them, V₂O₅, purity ≥ 99%, CAS No. 1314-62-1, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. Na₂C₂O₄, purity ≥ 99%, CAS No. 62-76-0, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. Al(OH)₃, purity ≥ 99.9%, CAS No. 21645-51-2, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. Activated carbon, purchased from Timcal, with a specific surface area of ​​60 m², was also purchased. 2 / g, trade name is Super P. Polyvinylidene fluoride, molecular weight 1 million, purchased from AKEMA, model HSV900, trade name is polyvinylidene fluoride. Carbon paper, purchased from Toray Industries, Inc., thickness 280um, trade name is Toray carbon paper. Glass fiber diaphragm, purchased from Gleisey Life Sciences Co., Ltd., specification GF / D 19mm, trade name is glass fiber diaphragm Whatman. Zn(CF3SO3)2 electrolyte, purchased from Suzhou Duoduo Chemical Technology Co., Ltd., specification 2M, trade name is zinc ion electrolyte (ZN-001).

[0035] Example 1 A kind of Al 3+ The preparation method of @NVO includes the following steps: 16 mmol of V2O5 was dissolved in 100 mL of 2 M Na2C2O4 solution and stirred at 400 rpm for 72 h in a water bath at 30 °C. The solution changed from orange-yellow to dark brown. After filtration and washing, the solution was dried at 80 °C for 12 h to obtain NVO.

[0036] 0.4 mmol of Al(OH)3 and 2 mmol of NVO were dissolved in 40 mL of water, stirred for 30 min, reacted at 120 °C for 3 h, cooled, filtered and washed, and dried at 80 °C for 12 h to obtain Al. 3+ @NVO.

[0037] Example 2 A kind of Al 3+ The preparation method of @NVO includes the following steps: 12 mmol of V2O5 was dissolved in 100 mL of 1.5 M Na2C2O4 solution and stirred at 300 rpm for 60 h in a water bath at 20 °C. The solution changed from orange-yellow to dark brown. After filtration and washing, the solution was dried at 70 °C for 8 h to obtain NVO.

[0038] 0.2 mmol of Al(OH)3 and 2 mmol of NVO were dissolved in 40 mL of water, stirred for 20 min, reacted at 100 °C for 2 h, cooled, filtered and washed, and dried at 70 °C for 8 h to obtain Al. 3+ @NVO.

[0039] Example 3 A kind of Al 3+ The preparation method of @NVO includes the following steps: 20 mmol of V2O5 was dissolved in 100 mL of 2.5 M Na2C2O4 solution and stirred at 500 rpm for 84 h in a water bath at 40 °C. The solution changed from orange-yellow to dark brown. After filtration and washing, the solution was dried at 85 °C for 14 h to obtain NVO.

[0040] 0.8 mmol of Al(OH)3 and 2 mmol of NVO were dissolved in 40 mL of water, stirred for 40 min, reacted at 140 °C for 5 h, cooled, filtered and washed, and dried at 85 °C for 14 h to obtain Al. 3+ @NVO.

[0041] Comparative Example 1 A kind of Al 3+ The preparation method of @NVO includes the following steps: 16 mmol of V2O5 was dissolved in 100 mL of 2 M Na2C2O4 solution and stirred at 400 rpm for 72 h in a water bath at 30 °C. The solution changed from orange-yellow to dark brown. After filtration and washing, the solution was dried at 80 °C for 12 h to obtain NVO.

[0042] 2 mmol of NVO was dissolved in 40 mL of water, stirred for 30 min, reacted at 120 °C for 3 h, cooled, filtered and washed, and dried at 80 °C for 12 h to obtain the nanocomposite material, denoted as NVO.

[0043] Comparative Example 2 A kind of Al 3+ The preparation method of @NVO includes the following steps: 16 mmol of V2O5 was dissolved in 100 mL of 2 M Na2C2O4 solution and stirred at 400 rpm for 72 h in a water bath at 30 °C. The solution changed from orange-yellow to dark brown. After filtration and washing, the solution was dried at 80 °C for 12 h to obtain NVO.

[0044] 1.2 mmol of Al(OH)3 and 2 mmol of NVO were dissolved in 40 mL of water, stirred for 30 min, reacted at 120 °C for 3 h, cooled, filtered, washed, and dried at 80 °C for 12 h to obtain the nanocomposite material. The nanocomposite material exhibited lower discharge specific capacity and rate performance than the material without Al(OH)3 due to excessive aluminum addition.

[0045] To illustrate the beneficial effects of the present invention, the following experiments were also conducted.

[0046] I. Experimental Methods 1. Zinc-ion battery preparation The Al prepared in Examples 1 to 3 were respectively 3+ @NVO and NVO prepared in Comparative Example 1, activated carbon, and polyvinylidene fluoride are ground and mixed in a mass ratio of 7:2:1 until a viscous consistency is reached, thus obtaining an activated slurry.

[0047] The active slurry was coated onto the surface of carbon paper with a side length of 1 cm, with a coating amount of 1 mg / cm². 2 The carbon paper is dried at 80°C for 12 hours to form an active material layer, thus obtaining the positive electrode sheet.

[0048] The zinc foil is used as the negative electrode after the oxide layer on the surface is removed by sanding.

[0049] A zinc-ion battery is prepared by sequentially assembling the negative electrode, glass fiber separator, Zn(CF3SO3)2 electrolyte, positive electrode, and CR2032 battery casing.

[0050] 2. Discharge capacity test The zinc-ion battery was cycled 5 times at each current density within the voltage range of 0.2V to 1.6V, and at current densities of 0.1A / g, 0.5A / g, 1A / g, 2A / g, 4A / g, 6A / g, 8A / g, and 10A / g.

[0051] 3. Discharge cycle test The zinc-ion battery was activated by first cycling it 5 times at a current density of 0.1 A / g within a voltage range of 0.2 V to 1.6 V, and then by charge-discharge cycling at a current density of 1 A / g.

[0052] 4. Zn 2+ Diffusion coefficient during charging and discharging process The zinc-ion battery was charged and discharged within a voltage range of 0.2V to 1.6V and a low current density of 0.05A / g. A constant current pulse was applied for 5 minutes, followed by a 30-minute relaxation period until the charging and discharging process was completed.

[0053] The diffusion coefficient of zinc ions is calculated using the linear change of the potential with time square root during the pulse phase, according to formula (1).

[0054] Formula (1): In the formula, D is the diffusion coefficient. τ is the relaxation time. m It is the number of moles. m It is the molar volume. It refers to the potential change during the pulse. It is the equilibrium potential difference before and after relaxation.

[0055] II. Experimental Results 1. Material structure characterization Al prepared in Example 1 3+ Scanning electron microscope images of @NVO and NVO prepared in Comparative Example 1 are shown below. Figure 1 As shown. The results show that the NVO prepared in Comparative Example 1 has a nanorod structure with a diameter of 150 nm and a length of 1000 nm, and there is a lot of adhesion between the nanorods. The Al prepared in Example 1 3+ @NVO nanorods adhere less to each other.

[0056] Al prepared in Example 1 3+ The XRD patterns of @NVO and NVO prepared in Comparative Example 1 are shown below. Figure 2 As shown. The results show that Al 3+ The coating did not alter the crystal structure of NVO. There is an Al at 18.32°. 3+ The peak proves that Al 3+ Successfully coated onto the surface of NVO material. Through the study of Al... 3+ High-resolution XPS spectra of Al in the @NVO composite nanomaterials revealed a large amount of Al around 74.5 eV. 3+ ,like Figure 5 As shown. This mainly originates from Al in Al(OH)3. 3+ With [V6O] 16 The ≡Al-OV≡ coordinate bonds formed by ]³⁻.

[0057] 2. Zinc-ion battery test Al prepared in Example 1 3+ The charge-discharge cycles and cycle rates of zinc batteries prepared with NVO and NVO prepared in Comparative Example 1 are as follows: Figure 3 , Figure 4 , Figure 6 and Figure 7 As shown. The results show that the Al prepared in Example 1 3+ The zinc-ion battery made of @NVO and the zinc-ion battery made of NVO prepared in Comparative Example 1 were cycled 1000 times at a current density of 1 A / g. The Al prepared in Example 1 3+ The zinc-ion battery made with @NVO retained 96.6% of its capacity, while the zinc-ion battery made with NVO in Comparative Example 1 only retained 69.6% of its capacity. 3+ After the introduction of Al 3+ @NVO nanocomposites have a more stable structure, such as Figure 3 As shown. Rate performance tests were conducted at current densities of 0.1 A / g, 0.5 A / g, 1 A / g, 2 A / g, 4 A / g, 6 A / g, 8 A / g, and 10 A / g, respectively. Al 3+The discharge capacity of the @NVO nanocomposite material was increased by 102.4%, 102.3%, 103.5%, 104.2%, 106.8%, 111.3%, 116.5%, and 122.7%, respectively. Figure 4 As shown. Al was calculated using the constant current intermittent titration method. 3+ @NVO nanocomposite Zn 2+ The diffusion coefficient during the charging and discharging process is 10. -10 cm 2 The diffusion coefficient of / s is higher than that of NVO materials, which is 10. -11 cm 2 / s, such as Figure 6 and Figure 7 As shown, the Al(OH)3 layer provides more active interface sites, improves the transport path of zinc ions at the interface, enhances ion diffusion dynamics by 10 times, and improves rate performance.

[0058] Table 1 shows the discharge capacity of batteries prepared from the materials used in the examples and comparative examples. It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described in this invention to avoid redundancy. Although preferred embodiments of this invention have been described, those skilled in the art, once they understand the inventive concept of this invention, can make other changes and modifications to these embodiments, and all such changes and modifications fall within the scope of this invention.

[0059] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. If such modifications and variations fall within the scope of equivalents of this invention, then this invention is also intended to include such modifications and variations.

Claims

1. An Al 3+ Sodium vanadate-coated nanocomposite material, characterized in that, By Al 3+ It is obtained by coating sodium vanadate hydrate; Sodium vanadate hydrate is produced by the reaction of V2O5 and Na2C2O4; The vanadium in the sodium vanadate is pentavalent. Under bridging and coordination, the pentavalent vanadium self-assembles to form a polynuclear vanadium-oxygen cluster anion [V6O]. 16 ] 2- Al 3+ [V6O] on the surface of sodium vanadate 16 ] 2- Forming a surface complex of type =Al-OV≡, coating sodium vanadate to form Al 3+ Vanadic acid-coated nanocomposite materials.

2. An Al according to claim 1 3+ Sodium vanadate-coated nanocomposite material, characterized in that, The method for preparing sodium vanadate hydrate includes the following steps: dissolving V2O5 in a 1.5M~2.5M Na2C2O4 solution, stirring at 300rpm~500rpm in a water bath at 20℃~40℃ for 60h~84h, the solution changes from orange-yellow to dark brown, filtering and washing, drying at 70~85℃ for 8~14h to obtain sodium vanadate hydrate.

3. An Al according to claim 2 3+ Sodium vanadate-coated nanocomposite material, characterized in that, The molar ratio of V2O5, Na2C2O4, and [other substances] is 16:

200.

4. An Al according to claim 3 3+ A method for preparing sodium vanadate-coated nanocomposite materials, characterized in that, The concentration of the Na2C2O4 solution is 2M.

5. An Al according to claim 2 3+ A method for preparing sodium vanadate-coated nanocomposite materials, characterized in that, The drying temperature is 80℃ and the time is 12 hours.

6. An Al according to claim 1 3+ A method for preparing sodium vanadate-coated nanocomposite materials, characterized in that, Includes the following steps: Al(OH)3 and sodium vanadate hydrate were dissolved in water, stirred for 20 min to 40 min, reacted at 100 ℃ to 140 ℃ for 2 h to 5 h, cooled, filtered and washed, and dried at 70 ℃ to 85 ℃ for 8 h to 14 h to obtain nanocomposite material. The molar ratio of V2O5 to Na2C2O4 is 12~20:150~250; The molar ratio of Al(OH)3 to sodium vanadate hydrate is 0.2~0.8:

2.

7. An Al according to claim 2 3+ A method for preparing sodium vanadate-coated nanocomposite materials, characterized in that, The molar ratio of Al(OH)3 to sodium vanadate hydrate is 0.4:

1.

8. An Al according to claim 2 3+ A method for preparing sodium vanadate-coated nanocomposite materials, characterized in that, The concentration of the hydrated sodium vanadate solution is 0.05M.

9. An Al according to claim 1 3+ Application of sodium vanadate-coated nanocomposite materials in the preparation of battery positive electrode sheets.

10. An Al according to claim 9 3+ The application of sodium vanadate-coated nanocomposite materials in the preparation of battery positive electrode sheets is characterized by, The positive electrode sheet is prepared according to the following method: Nanocomposite materials, activated carbon, and polyvinylidene fluoride were ground and mixed in a mass ratio of 7:2:1 to obtain an active slurry; the active slurry was coated onto carbon paper and dried to obtain a positive electrode sheet.

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