A bimetallic ion co-intercalated vanadium-based oxide, its preparation method and application

Abstract

This invention belongs to the field of aqueous zinc-ion battery technology, and relates to a bimetallic ion co-intercalated vanadium-based oxide, its preparation method, and its application. The preparation method of the bimetallic ion co-intercalated vanadium-based oxide is as follows: divalent metal acetate and V₂O₅ powder are added to deionized water, stirred and mixed under a constant temperature water bath, cooled, centrifuged, washed, freeze-dried, and ground to obtain a precursor; the precursor is ground and mixed with a monovalent metal nitrate, annealed, and quenched by adding deionized water in a molten state, followed by solid-liquid separation, washing, and drying to obtain the final product. This invention, by controlling the type or content of divalent metal acetate or monovalent metal nitrate, adjusts the type and content of metal ions doped in V₂O₅ to obtain a bimetallic ion sequentially intercalated synergistically modified vanadium-based oxide cathode material, which helps improve the structural stability and rate performance of the cathode material and is beneficial for large-scale production and application.

Description

Technical Field

[0001] This invention belongs to the field of aqueous zinc-ion battery technology, specifically relating to a bimetallic ion co-intercalated vanadium-based oxide, its preparation method, and its application. Background Technology

[0002] Lithium-ion batteries face challenges such as limited resources, high costs, and safety concerns, driving the exploration of next-generation sustainable energy storage systems. Among these, aqueous zinc-ion batteries have attracted widespread attention due to abundant zinc resources, low cost, and inherent safety; however, their commercialization is limited by the insufficient electrochemical performance of cathode materials. Therefore, developing cathode materials with high specific capacity and excellent cycle stability is crucial for the practical application of aqueous zinc-ion batteries.

[0003] Vanadium oxides are considered highly promising cathode materials for aqueous zinc-ion batteries due to their rich structural diversity, the multivalent state of vanadium, and open layered structure. Their natural two-dimensional ion channels facilitate rapid ion transport, thus endowing the material with high theoretical specific capacity and abundant electrochemical active sites. However, the low intrinsic electronic conductivity of vanadium oxides, the uncontrolled dissolution of vanadium during cycling, and the stress instability of the layered structure during charge and discharge severely restrict their electrochemical performance and practical applications, becoming a critical technical bottleneck that urgently needs to be overcome in this field. Existing technologies disclose a stepwise hydrothermal ripening process to cure monovalent metal ions K+. + and divalent alkaline earth metal ions Ba 2+ Simultaneously, it is inserted into a layer of hydrated vanadium oxide (VOH) material and used in zinc-ion batteries. However, in addition to the problems of long processing time, high energy consumption, and low yield, the materials obtained cannot be mass-produced and applied in practice due to the inherent limitations of the reaction conditions. Summary of the Invention

[0004] The purpose of this invention is to provide a bimetallic ion co-intercalated vanadium-based oxide, its preparation method, and its application, thereby overcoming the shortcomings of the prior art. After reacting divalent metal ion acetate with commercial vanadium pentoxide in a water bath at the corresponding molar ratio, the precursor is used as a "quenching" operation with room temperature deionized water during the subsequent annealing of monovalent metal ion nitrate to achieve sequential intercalation of bimetallic ion synergistic modification of vanadium-based oxide materials. When used as an electrode material, it can achieve high electrochemical performance and significantly improve the electrochemical performance and cycle stability of the material.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] In a first aspect, the present invention provides a method for preparing a bimetallic ion co-intercalated vanadium-based oxide, comprising the following steps: (1) Divalent metal acetate and V2O5 powder were added to deionized water and stirred and mixed evenly under constant temperature water bath conditions. After cooling, the precursor was obtained by centrifugation, washing, freeze drying and grinding. (2) The precursor and monovalent metal nitrate are ground and mixed, annealed, and then deionized water is added in the molten state for quenching. After solid-liquid separation, washing and drying, bimetallic ion co-intercalated vanadium-based oxide is obtained.

[0007] This invention utilizes a preparation method involving "mild liquid-phase pretreatment - high-temperature solid-phase reaction - molten water quenching" to achieve precise and synergistic control over the interlayer chemistry and crystal structure of vanadium-based oxides. The mild liquid-phase pretreatment operates under gentle and safe conditions, effectively achieving the initial intercalation and uniform dispersion of divalent metal ions. The high-temperature solid-phase reaction ensures the recombination and stabilization of the crystal structure. The molten water quenching operation not only enables rapid and forced intercalation of monovalent metal ions, but the resulting thermal stress also helps introduce appropriate defects and metastable structures into the material, thereby synergistically improving ionic conductivity and structural stability. This preparation method uses readily available raw materials and has a simple and controllable process. While avoiding the use of complex equipment or high-risk reagents, it provides an efficient and reliable approach for the controllable preparation and large-scale production of high-performance, customizable bimetallic ion co-intercalated vanadium-based oxides.

[0008] In some other embodiments, in step (1), the molar ratio of divalent metal acetate to V2O5 powder is 1:(2-2.5). Divalent metal ion acetates are one or more selected from magnesium acetate, barium acetate, calcium acetate, manganese acetate, zinc acetate, and cobalt acetate. Choosing acetates allows for the efficient and uniform insertion of metal ions into the interlayer space without disrupting the V₂O₅ framework, utilizing their weak basicity and coordination guiding effect. This increases the interlayer spacing and facilitates easy decomposition and removal during subsequent water washing, preventing the introduction of impurities and resulting in a product with high crystallinity, high purity, and large interlayer spacing. Specific analysis follows: Other types of anions such as Cl - NO3 - SO4 2- Inorganic salts such as V₂O₅ have small anions with no coordination ability; therefore, at 90°C, the lamination of V₂O₅ requires a motive force. Acetate (CH₃COO₃) -Acetate is a bidentate ligand that can coordinate with metal ions and also interact with the hydroxyl groups on the surface of V₂O₅. Furthermore, the hydrolysis of acetate produces a weakly alkaline solution, which neutralizes the acidity of the metal ions and maintains the optimal pH window. Other types of anionic inorganic salts cannot buffer this, leading to excessively strong local acidity, which can dissolve V₂O₅, or excessive alkalinity may generate hydroxide precipitates (byproducts). Simultaneously, during the water bath process, acetate ions adsorbed on the nanosheet surface provide steric hindrance, preventing the product from recombining during growth. Other types of anionic inorganic salts lack this ability, causing the product to easily grow into large, bulk particles with low specific surface area.

[0009] Meanwhile, the inherent physicochemical properties of some inorganic salts containing divalent metal ions vary considerably, making it difficult to standardize the process steps. For example, calcium sulfate and barium sulfate have very low solubility, making it difficult to participate in the reaction and imposing more stringent process requirements, which does not meet the basic principles of high preparation yield and minimal energy waste in this invention. When magnesium chloride and zinc chloride participate in the water bath reaction, the pH becomes unbalanced, resulting in an incomplete final product and the destruction of the vanadium-oxygen structure. Magnesium nitrate has an excessively high hydration energy and is difficult to participate in the reaction under acidic conditions, making it impossible to overcome the energy barrier. Vanadium oxides fail to be stripped under water bath conditions with zinc, cobalt, and manganese nitrates due to acidic dissolution or redox side reactions.

[0010] The constant temperature water bath conditions are 85-95 ℃, and the time is 5-8 h.

[0011] Specifically, the molar ratio of divalent metal acetate to V2O5 powder is 1:2, 1:2.2, or 1:2.5; this ensures that the doped divalent metal ions can fully react with the vanadium-oxygen framework and act as interlayer "pillars" of V2O5, which is beneficial to maintaining the stability and electrochemical activity of the overall framework of the material after the introduction of "pillar" ions.

[0012] The divalent metal ion acetate is magnesium acetate or barium acetate; The constant temperature water bath conditions are 85, 90 or 95 ℃, and the time is 5, 6, 7 or 8 h.

[0013] In some other embodiments, in step (1), the centrifugation speed is 5000-10000 r / min and the time is 5-8 min; The freeze-drying temperature is -40~-60℃, and the time is 40-50 h; The grinding time is 10-15 minutes.

[0014] Specifically, the centrifugation speed is 5000, 8000 or 10000 r / min, and the time is 5, 6, 7 or 8 min; The freeze-drying temperature is -40, -50, or -60°C, and the time is 40, 48, or 50 hours. The grinding time is 10, 12 or 15 minutes.

[0015] In some other embodiments, in step (2), the mass ratio of the precursor to the monovalent metal nitrate is 1:(8-12). The monovalent metal nitrate is one or more of lithium nitrate, sodium nitrate, potassium nitrate, and silver nitrate. The nitrate decomposes completely at high temperatures (the product is gas), and does not introduce anionic impurities into the final material, thus ensuring the purity of the product. At the same time, the monovalent metal ions have a small radius and unique coordination ability, which can be embedded in specific sites to "tighten" or "lock" the VO layers and enhance interlayer bonding, thereby inhibiting structural collapse and vanadium dissolution during cycling. Together with divalent ions, they can achieve "layer expansion" and "structure stabilization".

[0016] The annealing process involves a heating rate of 5-15 ℃ / min, a temperature of 350-400 ℃, and a time of 15-30 min. At this temperature, monovalent / divalent metal ions are driven to overcome the diffusion barrier, effectively embedding into the V₂O₅ interlayer and promoting their stable occupancy in the crystal lattice.

[0017] Specifically, the mass ratio of the precursor to monovalent metal nitrate is 1:8, 1:10, or 1:12. This ratio ensures that at the heat treatment temperature, the nitrate forms a large amount of molten salt, in which the precursor powder is completely immersed. This facilitates the rapid and thorough intercalation of monovalent metal ions between or within the vanadium-oxygen layers, ensuring the efficiency and uniformity of the intercalation reaction. At the same time, the monovalent metal nitrate can also synergistically work with the introduced divalent metal ions to jointly optimize the crystal structure and electrochemical performance of the material.

[0018] The monovalent metal ion nitrate is lithium nitrate; The annealing process is performed at heating rates of 5, 8, 10, 12 or 15 °C / min, at temperatures of 350, 380 or 400 °C, and for durations of 15, 20 or 30 min.

[0019] In some other embodiments, the quenching time in step (2) is 20-40 min; The drying temperature is 55-65 ℃.

[0020] Specifically, the quenching time is 20, 30, or 40 minutes; the drying temperature is 55, 60, or 65 °C.

[0021] By combining the instantaneous physical quenching of high-temperature melts with the intense chemical action of water, a synergistic regulation of metastable structure locking, controllable defect introduction, dynamic hydration intercalation, and porous morphology construction was achieved in one step. Through this non-equilibrium process, the material is simultaneously endowed with increased interlayer spacing to facilitate ion diffusion, abundant active defects to enhance intrinsic conductivity, and a unique mesoscopic structure to alleviate volumetric strain. This synergistically optimizes its ion transport kinetics and structural stability, ultimately significantly improving the rate performance and cycle life of the electrode material.

[0022] In a second aspect, the present invention provides a bimetallic ion co-intercalated vanadium-based oxide prepared by the method of preparing bimetallic ion co-intercalated vanadium-based oxide of the first aspect.

[0023] In some other embodiments, the bimetallic ion co-intercalated vanadium-based oxide includes a vanadium-based oxide and divalent and monovalent metal ions embedded therein; Vanadium-based oxides have a layered structure; divalent and monovalent metal ions are embedded in the VO lattice.

[0024] In V₂O₅ cathode materials intercalated with monovalent and divalent metal ions, the intercalated divalent metal ions not only act as interlayer "pillars" of V₂O₅, further enhancing its internal active specific surface area and zinc ion storage capacity, but the intercalated monovalent metal ions also bring the V₂O₅ layers closer together, stabilizing the material structure and suppressing V dissolution during electrochemical processes such as cyclic charging and discharging. This synergistic effect of dual guest ion intercalation significantly improves the diffusion kinetics of zinc ions in the electrode material, mitigates the volume change of the cathode material during cycling, and thus enhances the actual rate performance and overall cycle life of the electrode material.

[0025] In some other embodiments, the divalent metal ion is Mg. 2+ Ba 2+ Ca 2+ Mn 2+ Zn 2+ and Co 2+ One or more of the following; The monovalent metal ion is Li + Na + K + and Ag + One or more of them.

[0026] Selected divalent metal ions (Mg 2+ Ba 2+ Ca 2+ Mn 2+ Zn 2+ and Co 2+It mainly acts as a structural pillar embedded in the V2O5 interlayer, and through its specific ionic radius and valence state, it synergistically regulates the interlayer spacing, stabilizes the crystal structure, and partially contributes additional capacity (such as Mn). 2+ Co 2+ It can participate in redox reactions); while the selected monovalent metal ion (Li) + Na + K + and Ag + ) utilizes its small ionic radius and high mobility to effectively enhance the bonding strength of the VO layer, suppress vanadium dissolution, and further optimize the ion diffusion channel (K) after insertion. + It can significantly expand the layers, Ag + It can generate conductive nanoparticles to improve conductivity. The two achieve complementary synergy between the "pillar effect" and the "stable structure effect" through sequential intercalation, which jointly improves the zinc storage performance and cycle stability of the material.

[0027] Thirdly, the present invention provides the application of the bimetallic ion co-intercalated vanadium-based oxide in an aqueous zinc-ion battery, as described in the second aspect.

[0028] In some other embodiments, the aqueous zinc-ion battery includes a bimetallic ion co-intercalated vanadium-based oxide positive electrode, an electrolyte, and a zinc negative electrode.

[0029] Specifically, zinc-ion batteries include zinc-ion pouch batteries, button batteries, cylindrical batteries, and prismatic batteries.

[0030] The electrolyte of aqueous zinc-ion button batteries is zinc perchlorate hexahydrate or Zn(CF3SO3)2; the electrolyte of aqueous zinc-ion pouch batteries is a gel electrolyte made by soaking in a solution of zinc perchlorate hexahydrate or Zn(CF3SO3)2 of appropriate concentration; the negative electrode of aqueous zinc-ion button batteries or aqueous zinc-ion pouch batteries is zinc foil.

[0031] The beneficial effects of this invention are: (1) This invention effectively regulates the content of metal ions intercalated between V₂O₅ layers by controlling the amount of divalent metal acetate or monovalent metal nitrate, thus achieving precise control over the material composition. Simultaneously, this method has good versatility; by changing the type of metal salt used, intercalated V₂O₅ materials containing different ion combinations (such as monovalent / divalent) can be flexibly prepared, providing a high-yield and universal preparation scheme for multi-ion synergistic modification strategies. Compared to traditional one-pot hydrothermal methods or simple solvothermal methods, the sequential intercalation method used in this invention uses readily available raw materials, offers high operational safety, and achieves a high product yield, providing a feasible path for mass production and broadening the application prospects of this material in practical electrochemical energy storage devices.

[0032] (2) The divalent metal ions embedded in this invention act as "pillars" to effectively increase the interlayer spacing, which not only increases the active specific surface area but also improves the zinc ion storage capacity. Meanwhile, the monovalent metal ions embedded at the same time can bring the VO layers closer together, playing a role in stabilizing the structure and inhibiting vanadium dissolution. This synergistic embedding of bimetallic ions optimizes the zinc ion diffusion kinetics and alleviates the volume strain during cycling, thereby enabling the material to exhibit excellent rate performance and cycling stability. Attached Figure Description

[0033] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0034] Figure 1 This is a scanning electron microscope image of the positive electrode material prepared in Example 1 of the present invention; Figure 2 This is a scanning electron microscope image of the positive electrode material prepared in Example 2 of the present invention; Figure 3 This is a scanning electron microscope image of the cathode material prepared in Comparative Example 2 of the present invention; Figure 4 The images show the overall and partial magnified X-ray diffraction patterns of the cathode materials prepared in Embodiment 1 and Comparative Examples 1-2 of this invention; where a is the overall X-ray diffraction pattern and b is the partial magnified X-ray diffraction pattern. Figure 5 The X-ray diffraction pattern of the cathode material prepared in Example 2 of this invention; Figure 6 The positive electrode materials prepared in Examples 1-2 and Comparative Examples 1-2 of this invention are in the range of 0.1-10 A g. -1 Ratio performance diagram; Figure 7 The positive electrode material prepared in Example 1 of this invention is in the range of 0.5-50 A g. -1 Rate performance versus coulomb efficiency at the following rates; Figure 8 The constant current charge-discharge performance diagrams of the cathode materials prepared in Example 1 and Comparative Examples 1-2 of this invention are shown. Figure 9 The diagram shows the cycle performance of the cathode materials prepared in Example 1 and Comparative Examples 1-2 of this invention. Detailed Implementation

[0035] Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be construed as limiting the scope of the invention. Specific conditions not specified in the embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Components whose manufacturers are not specified are all commercially available conventional products.

[0036] Example 1 This embodiment provides a lithium-ion and magnesium-ion co-intercalated vanadium oxide (LMVOH) and its preparation method, including the following steps: 1) Combine V2O5 and divalent metal acetate Mg(CH3COO)2 . Mix 4H2O in a molar ratio of 2:1, specifically weighing out 4.0 mmol V2O5 and 2.0 mmol Mg(CH3COO)2. . 4H2O and 80 mL of deionized water were placed in a 200 mL beaker and stirred in a 90 °C water bath for 6 h. After cooling to room temperature, the mixture was centrifuged at 5000 r / min (washed several times with deionized water and ethanol) for 5-8 min and then freeze-dried at -50 °C or below for 48 h. The resulting solid sample was ground into powder for use as precursor A (the powder obtained in this step is the precursor sample MVOH of magnesium ion intercalated vanadium oxide). 2) Weigh 0.5 g of the prepared precursor sample A (MVOH) from step 1) and 5 g of monovalent metal nitrate LiNO3 (mass ratio 1:10), grind and mix them evenly, and place them in a quartz crucible. Anneal the mixture in a muffle furnace at 380 ℃ for 15 min (heating rate of 10 ℃ / min) to transform it into a molten state. Then, quickly add 10-20 mL of room temperature deionized water. After the "quenching" reaction is carried out for 30 min, grind, filter and wash (wash several times with deionized water and ethanol), and finally dry at 60 ℃ to obtain lithium ion and magnesium ion co-intercalated vanadium oxide (LMVOH) cathode material.

[0037] like Figure 1 Scanning electron microscope image of the prepared lithium-ion and magnesium-ion co-intercalated vanadium oxide (LMVOH) cathode material. Mg 2+ and Li + After embedding into the VO lattice, the material morphology gradually transforms into a stacked structure of nanoribbons, and the material surface becomes rougher. This rough surface is conducive to the adsorption of active substances. For example... Figure 4 The X-ray diffraction (XRD) pattern of the lithium-ion and magnesium-ion co-intercalated vanadium oxide (LMVOH) cathode material prepared in step a shows that divalent metal ions (Mg) can be found. 2+ ) and monovalent metal ions (Li + After the VO layers were successively inserted, the interlayer spacing first increased and then decreased, which confirms that the bimetallic ion-supported interlayer structure expands the zinc ion storage capacity and appropriately enhances the overall structural stability by “pulling together” the VOV chemical bonds, thereby improving the structural collapse problem that may occur during the zinc ion insertion / extraction reaction.

[0038] Example 2 This embodiment provides a lithium-ion and barium-ion co-intercalated vanadium oxide (LBVOH) and its preparation method, including the following steps: 1) Mix V2O5 and divalent metal acetate Ba(CH3COO)2 in a molar ratio of 2:1. Specifically, weigh 4.0 mmol of V2O5 and 2.0 mmol of Ba(CH3COO)2 and place them together in a 200 mL beaker. Add 80 mL of deionized water and stir in a 90 ℃ water bath for 6 h. After cooling to room temperature, centrifuge at 5000 r / min (wash several times with deionized water and ethanol) for 5-8 min, and freeze-dry at -50 ℃ or below for 48 h. Grind the obtained solid sample into powder for use as precursor B (the powder obtained in this step is the precursor sample BVOH of barium ion intercalated vanadium oxide). 2) Weigh 0.5 g of the prepared precursor sample B (BVOH) from step 1) and 5 g of monovalent metal nitrate LiNO3 (mass ratio 1:10), grind and mix them evenly, and place them in a quartz crucible. Anneal the mixture in a muffle furnace at 380 ℃ for 15 min (heating rate of 10 ℃ / min) to transform it into a molten state. Then, quickly add 10-20 mL of room temperature deionized water and perform the "quenching" reaction for 30 min. After that, grind, filter and wash (wash several times with deionized water and ethanol), and finally dry at 60 ℃ to obtain lithium ion and barium ion co-intercalated vanadium oxide (LBVOH) cathode material.

[0039] like Figure 2 Scanning electron microscope image of the prepared lithium-ion and barium-ion co-intercalated vanadium oxide (LBVOH) cathode material. 2+ and Li + After embedding into the VO lattice, the material morphology gradually transforms into a disordered stacking of nanorod-like materials. Through... Figure 5 The X-ray diffraction (XRD) pattern in the image demonstrates the successful synthesis of lithium-ion and barium-ion co-intercalated vanadium oxide (LBVOH) cathode material.

[0040] Example 3 Unlike Example 1, the Mg(CH3COO)2 in step (1) is... . 4H2O was replaced with an equal amount of calcium acetate, and LiNO3 in step (2) was replaced with an equal amount of sodium nitrate. The other steps were the same as in Example 1.

[0041] Example 4 Unlike Example 1, the Mg(CH3COO)2 in step (1) is... . 4H2O is replaced with an equal amount of manganese acetate, and LiNO3 in step (2) is replaced with an equal amount of potassium nitrate. The other steps are the same as in Example 1.

[0042] Example 5 Unlike Example 1, the Mg(CH3COO)2 in step (1) is... . 4H2O was replaced with an equal amount of zinc acetate, and LiNO3 in step (2) was replaced with an equal amount of silver nitrate. The other steps were the same as in Example 1.

[0043] Example 6 Unlike Example 1, the Mg(CH3COO)2 in step (1) is... . 4H2O is replaced with an equal amount of cobalt acetate, and LiNO3 in step (2) is replaced with an equal amount of potassium nitrate. The other steps are the same as in Example 1.

[0044] Comparative Example 1 Unlike Example 1, step (2) is omitted, and only divalent metal ion acetate (Mg(CH3COO)2) is used. . Vanadium oxide hydrate (MVOH) with divalent metal ion intercalation was prepared by 4H2O, and the other preparation steps were exactly the same as in Example 1.

[0045] like Figure 4 b in the figure shows Mg 2+ After the introduction of vanadium-oxygen interlayer, XRD showed that the peak of the (001) crystal plane shifted to a smaller diffraction angle, indicating that the interlayer spacing was increased.

[0046] Comparative Example 2 At room temperature, 1 mmol of vanadium pentoxide (V₂O₅) powder was added to 40 mL of deionized water and dissolved under vigorous magnetic stirring. Then, 1 mL of hydrogen peroxide (H₂O₂, 30 wt%) was slowly added to the solution. After obtaining a clear orange-red solution, the mixture was sealed in a 50 mL polytetrafluoroethylene-lined stainless steel autoclave and maintained at 140 °C for 12 h. After cooling to room temperature, the resulting gel was freeze-dried for 48 h to obtain the product VOH. The obtained product was a non-ion-intercalated vanadium oxide hydrate.

[0047] like Figure 3 The comparative example 2 sample obtained had a macroscopic nanosheet morphology.

[0048] Comparative Example 3 Unlike Example 1, 4.0 mmol V₂O₅ and 2.0 mmol Mg(CH₃COO)₂ were weighed out. .4H2O and 5 g of monovalent metal nitrate LiNO3 were placed together in a 200 mL beaker, 80 mL of deionized water was added, and the mixture was stirred in a 90 ℃ water bath for 6 h. After cooling to room temperature, the mixture was centrifuged at 5000 r / min (washed several times with deionized water and ethanol) for 5~8 min, and then freeze-dried at -50 ℃ or below for 48 h. The resulting solid sample was ground into powder for use as a precursor. The precursor was annealed in a muffle furnace at 380 °C for 30 min (heating rate of 10 °C / min). After the reaction was completed, it was ground, filtered and washed (washed several times with deionized water and ethanol), and finally dried at 60 °C to obtain the cathode material.

[0049] Comparative Example 4 Unlike Example 1, in step (1) Mg(CH3COO)2 . 4H2O was replaced with an equal amount of deionized water, and the other steps were the same as in Example 1. A monovalent lithium-ion intercalated vanadium oxide hydrate was obtained.

[0050] Comparative Example 5 Unlike Example 2, Ba(CH3COO)2 in step (1) is replaced with an equal amount of BaCl2, while the other steps are the same as in Example 1.

[0051] Comparative Example 6 Unlike Example 1, after the annealing treatment in step (2), no room temperature deionized water was added for quenching, and the mixture was directly cooled to room temperature. The other steps were the same as in Example 1.

[0052] Comparative Example 7 Unlike Example 3, sodium nitrate is not added in step (2), while the other steps are the same as in Example 3.

[0053] Comparative Example 8 Unlike Example 4, potassium nitrate is not added in step (2), while the other steps are the same as in Example 4.

[0054] Comparative Example 9 Unlike Example 5, silver nitrate is not added in step (2), while the other steps are the same as in Example 5.

[0055] Comparative Example 10 Unlike Example 6, potassium nitrate is not added in step (2), while the other steps are the same as in Example 6.

[0056] The test conditions for aqueous zinc-ion batteries are as follows: The assembled aqueous zinc-ion batteries were subjected to constant current charge-discharge tests on the Blue Battery Testing System. The electrolytes used in the examples and comparative examples are shown in Table 1. The test voltage range was 0.2-1.6V, and the test current density was 0.2-10 Ag. -1 Or 0.5-50 A g -1 .

[0057] Cyclic voltammetry tests were performed on the assembled aqueous zinc-ion battery using an electrochemical workstation. The test voltage range was 0.2–1.6 V, and the scan rate was 0.1–1.0 mV / s. -1 The data obtained from the tests were compared and analyzed.

[0058] When evaluating the specific capacity performance at different current densities, in the example samples, Example 1 was tested at 10 A g. -1 It exhibits the smallest specific capacity at the given current density, namely 223.1 mAh g. -1 However, this value is still higher than the corresponding values ​​in all comparative examples 1-2. Furthermore, at 50 A g... - ¹ At high current densities, the specific capacity of the Example 1 sample also significantly exceeded that of the comparative sample. Therefore, regardless of whether the current density is low or high, the performance of the Example samples is significantly better than that of the comparative sample. Example 2 at 10 A g -1 It exhibits the lowest specific capacity at the given current density, namely 169.5 mAh g. -1 However, this value is still higher than the corresponding values ​​in all comparative samples 1 and 2.

[0059] The lithium-ion and magnesium-ion co-intercalated vanadium oxide (LMVOH) obtained in Example 1 was used to fabricate an electrode sheet, which was then assembled into an aqueous zinc-ion battery. The aqueous zinc-ion battery prepared in Example 1 exhibited excellent electrochemical performance. After activation, it reached a speed of 0.2 A g. -1 It exhibits a current density of 543.1 mAh g⁻¹ -1 initial specific capacity ( Figure 8 ), at 50 A g -1 It still achieves 106.9 mAh g at a current density. -1 Specific capacity ( Figure 7 After 10,000 charge-discharge cycles, the capacity retention rate was 78.6%. Figure 9 It exhibits good cyclic stability.

[0060] The lithium-ion and barium-ion co-intercalated vanadium oxide (LBVOH) obtained in Example 2 was used to fabricate an electrode sheet, which was then assembled into an aqueous zinc-ion battery. Figure 6 As can be seen, the aqueous zinc-ion battery prepared in Example 2 exhibits excellent electrochemical performance. After activation, at 0.2 A g...-1 It exhibits a current density of 351.7 mAh g⁻¹. -1 The initial specific capacity at 10 A g -1 It still achieves 169.5 mAh g at a current density. -1 Its specific capacity is high, and its capacity retention exceeds 100% after 65 charge-discharge cycles, demonstrating good cycle stability.

[0061] The stability and rate performance of the examples and comparative examples are shown in Table 1.

[0062] Table 1 Rate Performance and Stability

[0063] As shown in Table 1, by comparing the data of Example 1 with those of Comparative Examples 1-2, it can be found that the rate capability and cycle stability of the bimetallic ion co-intercalated vanadium oxide cathode material are superior to those of its single-ion intercalated vanadium oxide and unintercalated vanadium oxide in the test. This illustrates the necessity of bimetallic ion synergistic intercalation modification. Although Comparative Example 3 also performed a water bath operation on the reactants in step (1), due to the inherent physicochemical properties of monovalent metal nitrates and Mg... 2+ Its high hydration energy makes it difficult to achieve co-intercalation. Only by appropriately extending the process time and undergoing the subsequent step (2) of "high temperature solid-state reaction-molten water quenching" can its structure be improved.

[0064] Similarly, Comparative Example 4 underwent "molten water quenching" intercalation with monovalent lithium ions. Combined with test results, it can be shown that its limited ionic radius has a limited effect on increasing the distance between the vanadium and oxygen layers. Its specific capacity is far lower than that of Example 1, and at 10 A g... -1 It is difficult to perform long-term cycling at high current densities.

[0065] Comparative Example 6 lost its internal structural water due to the absence of deionized water during the "molten state water quenching" operation. Some intercalated ions could not be compatible with the rigid structural buffer, and the overall structural toughness was weakened. The vanadium-oxygen layer structure may partially collapse, leading to an increase in the zinc ion storage barrier, which is not conducive to long-cycle testing.

[0066] Furthermore, the performance data from Comparative Example 5 show that the preparation of the precursor for divalent metal ion intercalation can be appropriately screened and adjusted to a chloride salt (such as barium chloride) suitable for the process conditions of this invention, based on its physicochemical properties. Although it can participate well in the intercalation reaction, it inevitably introduces impurity ions (Cl...). - and excessive Ba 2+Through repeated centrifugation and washing with deionized water and anhydrous ethanol, most impurity ions can be removed; however, its electrochemical performance will inevitably be affected to some extent. The "molten water quenching" stage uses nitrates with relatively low melting points, which will not introduce or generate impurities, and these impurities are easily removed by water washing later.

[0067] Therefore, the feasibility of the bimetallic ion co-intercalation strategy of this invention can be determined, and the synergistic necessity of each individual step in the preparation method of "mild liquid-phase pretreatment - high-temperature solid-phase reaction - molten water quenching" is also demonstrated. This preparation method can achieve precise and synergistic control of the interlayer chemistry and crystal structure of vanadium-based oxides. The mild liquid-phase pretreatment has mild operating conditions and high safety, effectively realizing the initial intercalation and uniform dispersion of divalent metal ions. The high-temperature solid-phase reaction ensures the recombination and stabilization of the crystal structure. The molten water quenching operation not only realizes the rapid and forced intercalation of monovalent metal ions, but the thermal stress generated also helps to introduce appropriate defects and metastable structures into the material, thereby synergistically improving the ionic conductivity and structural stability. This provides an effective route and idea for the modification of vanadium-based cathode materials for aqueous zinc-ion batteries.

[0068] By comparing and analyzing the data of Examples 3-6 with their corresponding Comparative Examples 7-10, the universality of the strategy of the present invention for modifying vanadium oxide as a cathode material for aqueous zinc-ion batteries is further demonstrated. It also further proves that other types of bimetallic ion co-intercalated vanadium oxide cathode materials have similar "double strong, single weak" modification rules in terms of rate performance and cycle stability compared with their comparative examples, which also shows that they have broad application prospects.

[0069] Based on the above research, this invention utilizes divalent metal ion acetate and monovalent metal ion nitrate as raw materials, and successfully prepares a material with high active sites, high specific capacity, and high cycle stability through sequential pre-intercalation technology. The interlayer distance and interlayer stress of this material can be modified and optimized by setting parameters such as different bimetallic ion co-intercalation layers or changing their molar ratio, thereby greatly improving the zinc ion storage capacity and fast ion migration kinetics. This sequentially pre-intercalated bimetallic ion synergistic modification of vanadium-based oxide cathode material can achieve high electrochemical performance as an electrode material in aqueous zinc-ion batteries or other alkali metal ion aqueous batteries and their pouch secondary energy storage devices, significantly improving the problems of insufficient electrochemical performance and cycle stability.

[0070] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a bimetallic ion co-intercalated vanadium-based oxide, characterized in that, Includes the following steps: (1) Add divalent metal acetate and V2O5 powder to deionized water, stir and mix evenly under constant temperature water bath conditions, cool and then centrifuge, wash, freeze dry and grind to obtain the precursor; the molar ratio of the divalent metal acetate to V2O5 powder is 1:(2-3). (2) The precursor and monovalent metal nitrate are ground and mixed, annealed, and then deionized water is added in the molten state for quenching. After solid-liquid separation, washing and drying, bimetallic ion co-intercalated vanadium-based oxide is obtained; the mixing mass ratio of the precursor and monovalent metal nitrate is 1: (8-15).

2. The method for preparing bimetallic ion co-intercalated vanadium-based oxides according to claim 1, characterized in that, In step (1), the molar ratio of divalent metal acetate to V2O5 powder is 1:(2-2.5). The divalent metal ion acetate is one or more of magnesium acetate, barium acetate, calcium acetate, manganese acetate, zinc acetate, and cobalt acetate; The constant temperature water bath conditions are 85-95 ℃, and the time is 5-8 h.

3. The method for preparing bimetallic ion co-intercalated vanadium-based oxides according to claim 1, characterized in that, In step (1), the centrifugation speed is 5000-10000 r / min and the time is 5-8 min; The freeze-drying temperature is -40 to -60 ℃, and the time is 40-50 h; The grinding time is 10-15 minutes.

4. The method for preparing bimetallic ion co-intercalated vanadium-based oxides according to claim 1, characterized in that, In step (2), the mass ratio of the precursor to the monovalent metal nitrate is 1:(8-12). Monovalent metal ion nitrates are one or more of lithium nitrate, sodium nitrate, potassium nitrate, and silver nitrate; The annealing process involves a heating rate of 5-15 ℃ / min, a temperature of 350-400 ℃, and a time of 15-30 min.

5. The method for preparing bimetallic ion co-intercalated vanadium-based oxides according to claim 1, characterized in that, In step (2), the quenching time is 20-40 min; The drying temperature is 55-65 ℃.

6. A bimetallic ion co-intercalated vanadium-based oxide prepared by the method of any one of claims 1-5.

7. The bimetallic ion co-intercalated vanadium-based oxide according to claim 6, characterized in that, This includes vanadium-based oxides and their internally embedded divalent and monovalent metal ions; The vanadium-based oxide has a layered structure; divalent metal ions and monovalent metal ions are embedded in the VO lattice.

8. The bimetallic ion co-intercalated vanadium-based oxide according to claim 6, characterized in that, The divalent metal ion is Mg. 2+ Ba 2+ Ca 2+ Mn 2+ Zn 2+ and Co 2+ One or more of the following; The monovalent metal ion is Li + Na + K + and Ag + One or more of them.

9. The application of the bimetallic ion co-intercalated vanadium-based oxide according to any one of claims 6-8 in an aqueous zinc-ion battery.

10. The application according to claim 9, characterized in that, The aqueous zinc-ion battery comprises a bimetallic ion co-intercalated vanadium-based oxide positive electrode, an electrolyte, and a metallic zinc negative electrode.

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