Preparation method and application of vanadium oxide anode and cathode materials in zinc ion battery

Abstract

The invention discloses a process for preparing a V2O3 / ZnV2O3 total battery by simultaneously using vanadium oxide in a zinc ion battery as a positive electrode material and a negative electrode material, which comprises the following steps: reacting ammonium metavanadate with absolute ethyl alcohol by adopting a solvothermal synthesis method, washing, drying, and calcining in a tubular furnace to obtain V2O3; in the preparation process of the V2O3 positive electrode material, only V2O3, acetylene black serving as a conductive agent and PVDF serving as a binder are mixed in proportion and then are coated on graphite paper, other coating protection materials do not need to be introduced into a V2O3 / Zn negative electrode, and V2O3 is used as a protection layer to inhibit growth of zinc dendrites, relieve hydrogen evolution side reaction of the zinc negative electrode and reduce corrosion of zinc. Vanadium oxide V2O3 is directly used as a core positive electrode material, the zinc negative electrode coating is developed by utilizing the characteristics of the vanadium oxide V2O3, a material is formed, meanwhile, the performance optimization of the positive electrode and the negative electrode is realized, the used raw materials are simple and easy to obtain, the process is simple and easy to implement, and the preparation process is simple and easy to implement from V2O3 raw material synthesis to positive and negative electrode piece preparation to V2O3 / ZnV2O3 total battery assembly. And comprehensive improvement of positive and negative electrode performances of zinc ions is simultaneously realized by a single material.

Description

Technical Field

[0001] This invention relates to the field of zinc-ion battery technology, and in particular to a method for preparing vanadium oxide positive and negative electrode materials in zinc-ion batteries and their applications. Background Technology

[0002] With the transformation of the global energy structure and the rapid development of renewable energy, the development of safe, low-cost, and environmentally friendly large-scale energy storage systems has become a key research focus. Among numerous energy storage technologies, aqueous zinc-ion batteries (AZIBs) have shown great application potential due to their advantages such as high safety, abundant zinc resources, high theoretical capacity, and environmental friendliness. However, the further development of zinc-ion batteries is still limited by two key challenges: first, the lack of cathode materials that combine high capacity and long lifespan; and second, the dendrite growth and side reaction problems faced by zinc metal anodes. Currently, zinc materials used as anodes are usually zinc foil or multidimensional porous zinc structures, but the stability of zinc anode materials is affected by multiple factors. During the deposition process, zinc ions are easily affected by the uneven distribution of electric field on the electrode surface, tending to preferentially nucleate and grow rapidly in protruding areas, eventually forming dendrites. The growth of zinc dendrites can pierce the separator made of glass fiber or polyethylene, leading to internal short circuits in the battery, which in turn can cause thermal runaway or even battery failure.

[0003] Vanadium-based oxides are considered promising cathode materials for zinc-ion batteries due to their multiple valence states, high theoretical capacity, abundant reserves, and low cost. Vanadium trioxide (V₂O₃) possesses a high theoretical specific capacity due to its lower valence state and potentially high electron transfer number. However, current research primarily focuses on modifying V₂O₃ as a cathode active material, employing various modification, doping, and composite methods to improve its performance as a cathode. This approach easily introduces impurities, triggering side reactions that negatively impact battery performance. Furthermore, the influence of V₂O₃ on the anode has not been considered, limiting its application to a single scenario and failing to fully leverage the material's multifunctionality.

[0004] Therefore, using only one substance can reduce the complexity of the process, reduce the generation of side reactions, and simultaneously improve the performance of the positive and negative electrode materials, thereby improving the overall performance of the zinc-ion battery and extending its lifespan. This is a technical problem that the zinc-ion battery industry urgently needs to solve. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing vanadium oxide positive and negative electrode materials in zinc-ion batteries and their application, so as to solve the problems mentioned in the background art.

[0006] In a first aspect, the present invention provides a method for preparing vanadium oxide positive and negative electrode materials in zinc-ion batteries, comprising the following preparation steps:

[0007] Preparation of S1.V2O3: Add 40 mL of anhydrous ethanol and 0.2–0.4 g of ammonium metavanadate to 100 mL of polytetrafluoroethylene inner liner, mix and stir for 5–10 min, then place the mixture along with the inner liner in a stainless steel reactor. Keep it in an oven at 200–250 °C for 10–12 h and then cool naturally to obtain a mixture. Wash the mixture sequentially with deionized water and anhydrous ethanol, and centrifuge 2–3 times until colorless to obtain a precipitate. Place the precipitate in a vacuum drying oven at 60–80 °C for 10–12 h to obtain a V2O3 precursor. Place the precursor in a tube furnace and heat it to 600–700 °C at a heating rate of 5 °C / min under a nitrogen atmosphere. Keep it at this temperature for 2–3 h and then cool it to room temperature to obtain vanadium oxide V2O3.

[0008] Preparation of S2.V2O3 cathode material: V2O3 obtained in S1, acetylene black, and binder A are mixed in a mass ratio of 7:2:1, and solvent A is added and ground for 1 hour to obtain grinding slurry A; 0.4-0.6 g of grinding slurry A is uniformly coated onto graphite paper with a thickness of 100 μm using a coating machine, and then placed in a vacuum oven at 60-70℃ to dry for 10-12 hours; the dried graphite paper is cut into circular pieces with a diameter of 12 mm to obtain V2O3 cathode material with coating.

[0009] Preparation of S3.V2O3 / Zn anode material: V2O3 obtained in S1 and binder B are mixed at a mass ratio of 8:2, and solvent B is added and ground for 1 hour to obtain grinding slurry B; 0.4-0.6 g of grinding slurry B is uniformly coated on the surface of zinc foil with a thickness of 100 μm, and then placed in a vacuum oven at 60-70℃ to dry for 10-12 hours; the dried zinc foil is cut into circular pieces with a diameter of 12 mm to obtain the coated V2O3 / Zn anode material.

[0010] In a preferred embodiment of the present invention, the adhesive A is polyvinylidene fluoride (PVDF).

[0011] As a preferred embodiment of the present invention, solvent A is N-methylpyrrolidone (NMP), and the amount of solvent A added is 180-200% of the total mass of V2O3, acetylene black, and binder A.

[0012] In a preferred embodiment of the present invention, the binder B is carboxymethyl cellulose (CMC).

[0013] As a preferred embodiment of the present invention, solvent B is composed of anhydrous ethanol and deionized water in a mass ratio of 1:8.

[0014] As a preferred embodiment of the present invention, the amount of solvent B added is 180-200% of the total mass of V2O3 and binder B.

[0015] Secondly, this invention also provides the application of vanadium oxide positive and negative electrode materials in zinc-ion batteries, using the following method steps to assemble a CR2032 type V2O3 / Zn||V2O3 full cell:

[0016] Using the positive electrode shell as a substrate, 20-30 μL of electrolyte is first added. Then, the V2O3 positive electrode material is placed flat on the electrolyte, and another 20-30 μL of electrolyte is added to the coated surface of the V2O3 positive electrode material. Next, a glass fiber separator is laid on top, and 120-140 μL of electrolyte is added to fully wet it. The V2O3 / Zn negative electrode material is aligned and placed on the glass fiber separator with the coating facing the glass fiber separator. Stainless steel gaskets, spring sheets, and negative electrode shells are added in sequence. After the battery is stacked, it is placed in an electric encapsulation machine and encapsulated under a pressure of 28.1 MPa to obtain a V2O3 / Zn||V2O3 full cell.

[0017] As a preferred embodiment of the present invention, the electrolyte is Zn(CF3SO3)2 with a concentration of 3 mol / L.

[0018] As a preferred embodiment of the present invention, the glass fiber diaphragm has a diameter of 16 mm and a thickness of 675 μm.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] 1. This invention employs a hydrothermal synthesis method to obtain vanadium oxide (V2O3) by mixing and reacting ammonium metavanadate and anhydrous ethanol, washing, drying, and then calcining in a tube furnace. This preparation method uses only ammonium metavanadate and anhydrous ethanol as raw materials, is simple and reproducible, and produces V2O3 with a clean surface free of residual organic impurities. The V2O3 powder exhibits good dispersibility and is less prone to agglomeration when subsequently mixed with conductive agents and binders, easily forming a uniform slurry. Furthermore, the post-reaction washing with deionized water and ethanol aligns with the principles of green chemistry. In the preparation of the V2O3 cathode material, only a specific ratio of vanadium oxide (V2O3) to conductive agent acetylene black and binder polyvinylidene fluoride (PVDF) is required, followed by coating onto graphite paper. A small amount of this mixture is sufficient to form a continuous conductive network between V2O3 particles. Simultaneously, the high liquid absorption capacity of acetylene black adsorbs the electrolyte, improving electrode wettability and accelerating Zn absorption. 2+The V2O3 / Zn anode exhibits efficient ion transport without impurity contamination of the electrode or side reactions. No additional protective coating material is required; V2O3 is used as the protective layer to inhibit zinc dendrite growth, mitigate hydrogen evolution side reactions in the zinc anode, reduce zinc corrosion, and effectively minimize side reactions. The V2O3 / Zn anode is formed by mixing V2O3 with carboxymethyl cellulose (CMC) binder, adding anhydrous ethanol and deionized water as solvents to create a slurry, and then coating it onto the zinc sheet surface using a film-stretching process. The hydrophilicity of CMC enhances the electrolyte wettability of the anode, accelerating ion transport.

[0021] 2. The V₂O₃ / Zn||V₂O₃ / Zn symmetric cell constructed in this invention achieves a speed of 1 mA / cm². 2 At current density, 1 mAh / cm 2 It can achieve stable cycling for more than 1600 hours at the areal capacity, and the polarization voltage remains stable. Its nucleation overpotential is only 53.2 mV, which is significantly lower than 102.3 mV of the Zn||Zn symmetric cell with pure zinc electrode. This indicates that the vanadium oxide V2O3 coating effectively reduces the energy barrier for zinc deposition and guides the uniform nucleation of zinc.

[0022] 3. The V2O3 / Zn||V2O3 full cell constructed in this invention exhibits excellent electrochemical performance. After 300 cycles at a current density of 1.0 A / g, the specific capacity remains at 598 mAh / g; after 2000 cycles at a high current density of 5.0 A / g, the specific capacity is 472 mAh / g; even after 6000 cycles at a high current density of 10.0 A / g, it can still maintain a specific capacity of 337 mAh / g, demonstrating excellent high-current cycling stability.

[0023] 4. This invention proposes an innovative "dual-use" approach to V2O3 in aqueous zinc-ion batteries (AZIBs). It utilizes vanadium oxide (V2O3) directly as the core positive electrode material, and also leverages its properties to develop a zinc negative electrode coating, thus achieving optimized performance of both positive and negative electrodes with a single material. Furthermore, the raw materials used in this invention are simple and readily available, and the process is simple and easy to implement. From V2O3 raw material synthesis to positive and negative electrode preparation and the assembly of the V2O3 / Zn||V2O3 full cell, the entire process requires no complex equipment or stringent conditions, achieving a comprehensive improvement in zinc-ion battery performance by using a single material as both positive and negative electrodes. Attached Figure Description

[0024] Figure 1 This is a SEM image of the vanadium oxide V2O3 of this invention;

[0025] Figure 2 The XRD pattern of vanadium oxide V2O3 of this invention is shown.

[0026] Figure 3This is a SEM image of the V2O3 / Zn anode material coating of the present invention;

[0027] Figure 4 The diagram shows the electrochemical performance of the symmetrical cell V2O3 / Zn||V2O3 / Zn of this invention.

[0028] Figure 5 The graph shows the electrochemical performance of the Zn||V2O3 full cell of this invention.

[0029] Figure 6 The graph shows the electrochemical performance of the V2O3 / Zn||V2O3 full cell of this invention.

[0030] Figure 7 This is a quantitative analysis diagram of the GITT test of the V2O3 / Zn||V2O3 full cell of the present invention;

[0031] Figure 8 This is the EIS diagram of the V2O3 / Zn||V2O3 full cell of the present invention;

[0032] Figure 9 This is a CV cycle test diagram of the V2O3 / Zn||V2O3 full cell of the present invention;

[0033] Figure 10 This is a CV cycle test diagram of the Zn||V2O3 full cell of the present invention;

[0034] Figure 11 The discharge cycle curves of the V2O3 / Zn||V2O3 full cell of the present invention at different current densities are shown. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] All raw materials used in this invention are commercially available.

[0037] Example 1:

[0038] Preparation of vanadium oxide (V₂O₃): 40 mL of anhydrous ethanol and 0.234 g of ammonium metavanadate were added to 100 mL of polytetrafluoroethylene (PTFE) inner liner. After mixing and stirring for 10 min, the mixture, along with the inner liner, was placed in a stainless steel reactor. The reactor was then transferred to an oven and kept at 250 °C for 10 h before natural cooling to obtain a mixture. The mixture was washed sequentially with deionized water and anhydrous ethanol, and centrifuged three times to obtain a precipitate. The precipitate was dried in a vacuum oven at 60 °C for 12 h to obtain a V₂O₃ precursor. The precursor was placed in a tube furnace and heated to 600 °C at a heating rate of 5 °C / min under a nitrogen atmosphere. After holding at this temperature for 3 h, the mixture was cooled to room temperature to obtain vanadium oxide (V₂O₃).

[0039] Example 2:

[0040] The preparation of vanadium oxide (V₂O₃) differs from Example 1 in that the oven temperature is changed to 200℃. Specifically, 40 mL of anhydrous ethanol and 0.234 g of ammonium metavanadate are added to a 100 mL polytetrafluoroethylene inner liner. After mixing and stirring for 10 min, the mixture, along with the inner liner, is placed in a stainless steel reactor. The reactor is then transferred to an oven and kept at 200℃ for 10 h before natural cooling to obtain a mixture. The mixture is washed sequentially with deionized water and anhydrous ethanol, and centrifuged three times to obtain a precipitate. The precipitate is dried in a vacuum oven at 60℃ for 12 h to obtain a V₂O₃ precursor. The precursor is placed in a tube furnace and heated to 600℃ at a heating rate of 5℃ / min under a nitrogen atmosphere. After holding at this temperature for 3 h, it is cooled to room temperature to obtain vanadium oxide (V₂O₃).

[0041] Example 3:

[0042] Preparation of V2O3 cathode material: The vanadium oxide V2O3 prepared in Example 1 was mixed with acetylene black and PVDF in a mass ratio of 7:2:1. The mixture was ground in an agate mortar for 1 hour with NMP as solvent (the amount of NMP added was 180% of the total mass of V2O3, acetylene black and PVDF) to obtain grinding slurry A. Then, 0.4 g of grinding slurry A was uniformly coated on graphite paper with a thickness of 100 μm using a coating machine and dried in a vacuum oven at 60 °C for 12 hours. The dried graphite paper was cut into circular pieces with a diameter of 12 mm to obtain the V2O3 cathode material with coating.

[0043] Example 4:

[0044] Preparation of V2O3 / Zn anode material: The vanadium oxide V2O3 prepared in Example 1 was mixed with carboxymethyl cellulose (CMC) at a mass ratio of 8:2, and then solvent B (solvent B is composed of anhydrous ethanol and deionized water at a mass ratio of 1:8, and the amount of solvent B added is 200% of the total mass of V2O3 and CMC) was added and ground for 1 hour to obtain grinding slurry B; 0.6 g of grinding slurry B was uniformly coated on the surface of zinc foil with a thickness of 100 μm, and then placed in a vacuum oven at 60 °C to dry for 12 hours; the dried zinc foil was cut into circular pieces with a diameter of 12 mm to obtain the coated V2O3 / Zn anode material.

[0045] Example 5:

[0046] Preparation of V2O3 / Zn||V2O3 / Zn symmetric battery: First, add 20 μL of 3 mol / L Zn(CF3SO3)2 electrolyte to the positive electrode shell. Then, add 20-30 μL of 3 mol / L electrolyte to the coated surface of the V2O3 / Zn negative electrode material. Next, lay a glass fiber membrane (16 mm in diameter and 675 μm in thickness) and add 120 μL of 3 mol / L electrolyte to fully wet it. Place the V2O3 / Zn negative electrode material prepared in Example 4 on the glass fiber membrane with the coating facing the membrane. Add stainless steel gaskets, spring sheets, and negative electrode shell in sequence. After stacking the battery, place it in an electric encapsulation machine and encapsulate it at 28.1 MPa. Wipe away excess electrolyte around the shell with lint-free paper to obtain the V2O3 / Zn||V2O3 / Zn symmetric battery.

[0047] Example 6:

[0048] Preparation of V2O3 / Zn||V2O3 full cell: Using the positive electrode shell as a substrate, 20 μL of 3 mol / L Zn(CF3SO3)2 electrolyte was first added to the positive electrode shell. Then, 30 μL of 3 mol / L electrolyte was added to the coated surface of the V2O3 positive electrode material. After that, a glass fiber membrane (16 mm in diameter and 675 μm in thickness) was laid on top, and 120 μL of 3 mol / L Zn(CF3SO3)2 electrolyte was added to fully wet it. The V2O3 / Zn negative electrode material prepared in Example 4 was aligned and placed on the glass fiber membrane with the coating facing the glass fiber membrane. Stainless steel gaskets, spring sheets, and negative electrode shells were added in sequence. After the battery was stacked, it was placed in an electric sealing machine and sealed under a pressure of 28.1 MPa. The excess electrolyte around the shell was wiped off with lint-free paper to obtain the V2O3 / Zn||V2O3 full cell.

[0049] Comparative Example 1:

[0050] The preparation of the Zn||V2O3 full cell differs from that in Example 6 in that the V2O3 / Zn negative electrode material in Example 6 is replaced with a pure zinc sheet. Specifically, using the positive electrode shell as a substrate, 20 μL of a 3 mol / L Zn(CF3SO3)2 electrolyte is first added to the positive electrode shell. Then, 30 μL of a 3 mol / L electrolyte is added to the coated surface of the V2O3 positive electrode material. Next, a glass fiber separator (16 mm in diameter and 675 μm in thickness) is laid on top, and 120 μL of a 3 mol / L Zn(CF3SO3)2 electrolyte is added to fully wet it. A 12 mm diameter pure zinc sheet is placed on top of the glass fiber separator, followed by a stainless steel gasket, a spring sheet, and the negative electrode shell. After stacking the cells, they are placed in an electric sealing machine and sealed under a pressure of 28.1 MPa. Excess electrolyte around the outer shell is wiped away with lint-free paper to obtain the Zn||V2O3 full cell.

[0051] Comparative Example 2:

[0052] Preparation of Zn||Zn symmetric battery: The difference from Example 5 is that the V2O3 / Zn negative electrode material in Example 5 is replaced with a pure zinc sheet. The specific method is as follows: First, 20 μL of Zn(CF3SO3)2 electrolyte with a concentration of 3 mol / L is added to the positive electrode shell, a pure zinc sheet with a diameter of 12 mm is placed, and then 30 μL of Zn(CF3SO3)2 electrolyte with a concentration of 3 mol / L is added. Then, a glass fiber separator (diameter of 16 mm and thickness of 675 μm) is laid on top, and 120 μL of electrolyte with a concentration of 3 mol / L is added to fully wet it. Then, a pure zinc sheet with a diameter of 12 mm is placed on the glass fiber separator. Stainless steel gaskets, spring sheets and negative electrode shells are stacked in sequence. After the battery is stacked, it is placed in an electric packaging machine and packaged at 28.1 MPa. The excess electrolyte around the shell is wiped off with lint-free paper to obtain the Zn||Zn symmetric battery.

[0053] Figure 1 Figure 1 shows scanning electron microscope (SEM) images of V₂O₃ prepared in Examples 1 and 2. Images a and b show the morphology and structure of V₂O₃ at 250℃, while images c and d show the morphology and structure of V₂O₃ at 200℃. As shown in Figure 1, the V₂O₃ consists of uniform nanoflora composed of nanosheets. This nanoflora structure provides a large specific surface area, which can be used for Zn... 2+ The storage provides a large number of active sites, and also facilitates the wetting of the electrolyte, providing a large contact area between the electrode and the electrolyte.

[0054] Figure 2 The XRD patterns of V2O3 prepared in Examples 1 and 2 are shown. The composition and crystal structure of the vanadium oxide V2O3 material were determined by X-ray diffraction (XRD). Figure 2 The XRD diffraction peak positions shown correspond perfectly to the standard card (PDF#34-0187) of V2O3. The diffraction peaks are sharp and have high intensity, indicating that V2O3 has good crystallinity. The main diffraction peaks include 2θ=24.3°, 33.0°, 36.2°, 38.5°, 41.2°, 44.1°, 49.8°, 53.9°, 58.3°, 63.1°, 65.2°, 70.7°, 76.9° and 78.3°, and the corresponding crystal planes are (012), (104), (110), (006), (113), (202), (024), (116), (122), (214), (300), (1010), (220) and (036), respectively.

[0055] Figure 3 This is a SEM image of the V2O3 / Zn anode material coating prepared in Example 4 of the present invention. Figure 3 The true microstructure of the V2O3 / Zn anode material coating was revealed. Figure 3 Figures a and b in the figure are cross-sectional views. Figure a shows the relationship between the zinc sheet and the V2O3 coating. Figure a shows that V2O3 is coated relatively uniformly on the surface of the zinc sheet. Figure b shows that the coating thickness is about 37 μm. Figure 3 Images c and d are front views. Image c shows that the coating consists of a continuous, porous network structure of V₂O₃, which is beneficial for ion transport and electric field homogenization. Enlarging image c to obtain image d clearly shows the morphology of V₂O₃ in image d. Figure 1 Consistent.

[0056] The electrochemical performance of the symmetrical battery V2O3 / Zn||V2O3 / Zn prepared in Example 5 was tested. Figure 4 The symmetrical cell test results verified the protective effect of the V2O3 coating on the zinc anode. Figure 4 Figure a shows a symmetrical V₂O₃ / Zn||V₂O₃ / Zn cell at 1 mAh / cm². 2 At its areal capacity, it can achieve stable cycling for over 1600 hours, and the polarization voltage remains stable throughout. In contrast, the Zn||Zn symmetric cell in Comparative Example 2 fails after about 60 hours due to internal short circuits caused by zinc dendrite growth. (Enlarged view of a single cycle is shown.) Figure 4 As shown in Figure b), the charge-discharge plateau of the symmetric cell V2O3 / Zn||V2O3 / Zn protected by the V2O3 coating is flatter, indicating that its zinc deposition and dissolution process is more reversible. Nucleation overpotential tests were performed on the V2O3 / Zn||V2O3 / Zn symmetric cell (…). Figure 4(Figure c in the figure) The results show that the nucleation overpotential of the symmetric cell V2O3 / Zn||V2O3 / Zn is only 53.2mV, which is significantly lower than the 102.3mV of the Zn||Zn symmetric cell with pure zinc electrode. This indicates that the vanadium oxide V2O3 coating effectively reduces the energy barrier for zinc deposition and guides the uniform nucleation of zinc. Figure 4 The d-plot in the figure represents the symmetrical cell V₂O₃ / Zn||V₂O₃ / Zn at 1, 2, 3, 4, 5, and 8 mA / cm². 2 At current density and 1mAh / cm 2 Rate performance tests at areal capacity showed that the symmetric cell V2O3 / Zn||V2O3 / Zn exhibited lower polarization voltage and better stability, further confirming that the V2O3 coating can not only effectively suppress dendrites and extend cycle life, but also improve the rate performance and electrochemical reversibility of the zinc anode, providing an effective anode modification strategy for the development of high-performance aqueous zinc-ion batteries.

[0057] Figure 5 The image shows the electrochemical performance of the Zn||V₂O₃ full cell prepared in Comparative Example 1. Figure 5 As shown in Figure a, at a current density of 1.0 A / g, the maximum discharge specific capacity of V₂O₃ reaches 665 mAh / g, and it retains a capacity of 444 mAh / g after 300 cycles. When the current density is increased to 5.0 A / g ( Figure 5 (See Figure b in the figure) The cycling stability of the material is further highlighted, reaching a peak specific capacity of 459 mAh / g after 76 cycles and maintaining 355 mAh / g after 2000 cycles. At a high current density of 10.0 A / g ( Figure 5 (See Figure c in the original text). This V2O3 cathode material still exhibits good performance, maintaining a capacity of 287 mAh / g after 6000 cycles. Rate performance testing shows (…). Figure 5 (Figure d in the figure) At different current densities from 0.1 to 10.0 A / g, the discharge specific capacities are 655, 642, 612, 588, 479, 374 and 274 mAh / g, respectively. When the current density returns to 0.2 A / g, the specific capacity can be restored to 608 mAh / g, indicating that the battery assembled with V2O3 cathode material has certain structural stability and cycle reversibility.

[0058] Figure 6 The image shows the electrochemical performance of the V2O3 / Zn||V2O3 full cell prepared in Example 6 of this invention. In the rate performance test, as shown... Figure 6As shown in Figure a, the V₂O₃ / Zn||V₂O₃ full cell exhibits excellent capacity retention across a wide current density range of 0.1–10.0 A / g, with discharge specific capacities reaching 1050, 1023, 988, 959, 652, 461, and 323 mAh / g, respectively. Furthermore, when the current density recovers from 10.0 A / g to 0.2 A / g, the capacity reversibly recovers to 996 mAh / g, maintaining a retention rate of 97.4%, demonstrating outstanding structural reversibility and reaction kinetics. Regarding long-term cycling stability… Figure 6 Figure b shows that the V₂O₃ / Zn||V₂O₃ full cell reaches a peak discharge specific capacity of 735 mAh / g after 26 cycles at 1.0 A / g, and maintains 598 mAh / g after 300 cycles, demonstrating higher reversible capacity and cycle stability. At 5.0 A / g (… Figure 6 Under high-rate conditions (Figure c in the diagram), the V2O3 / Zn||V2O3 full cell maintained a specific capacity of 472 mAh / g after 2000 cycles; at 10.0 A / g (… Figure 6 Under high-rate conditions (Figure d in the diagram), the V2O3 / Zn||V2O3 full cell maintained a specific capacity of 337 mAh / g after 6000 cycles. The degradation rate of the V2O3 / Zn||V2O3 full cell was significantly lower than that of the Zn||V2O3 full cell prepared in Comparative Example 1. This demonstrates that the V2O3 / Zn||V2O3 full cell assembled with V2O3 cathode material and V2O3 / Zn anode material exhibits significantly superior electrochemical performance compared to the Zn||V2O3 full cell assembled with V2O3 cathode material and pure zinc sheet (Comparative Example 1). This fully verifies the effectiveness of the "dual-use" strategy of vanadium oxide V2O3. Furthermore, the V2O3 coating significantly improves the capacity output, cycle life, and structural reversibility of the full cell over a wide range of current densities by suppressing dendrite growth and side reactions in the zinc anode, providing an effective material and structural design method for the overall optimization of aqueous zinc-ion batteries.

[0059] Figure 7 This is a quantitative analysis chromatogram of the V2O3 / Zn||V2O3 full cell prepared in Example 6 using GITT (galvanostatic intermittent titration). The V2O3 / Zn||V2O3 full cell exhibits zinc ion transport kinetics significantly superior to those of the Zn||V2O3 full cell (Comparative Example 1). Figure 7 As shown, the charge-discharge time of the V₂O₃ / Zn||V₂O₃ full cell is much longer than that of the Zn||V₂O₃ full cell. Furthermore, the calculated zinc ion diffusion coefficient D clearly shows that the Zn||V₂O₃ full cell has the largest D value of 2.46 × 10⁻⁶. -11 cm 2 / s, while the D value of the V2O3 / Zn||V2O3 full cell with V2O3 coating modified on the negative electrode is increased to 7.02×10 / s. -11 cm 2 / s, directly demonstrating from a kinetic perspective that the V2O3 coating effectively promotes Zn by optimizing the zinc / electrolyte interface environment. 2+ The migration kinetics of vanadium oxide (V₂O₃) were improved, lowering the ion transport energy barrier. This result is consistent with the improvement in rate performance and long-cycle stability of the full cell, providing a key mechanistic explanation for the effective improvement of the overall performance of the full cell by using V₂O₃ as a "dual-purpose material".

[0060] Figure 8 The image shown is the EIS diagram of the V2O3 / Zn||V2O3 full cell prepared in Example 6 of this invention. Figure 8 Figures a and b in the figure are the electrochemical impedance spectroscopy (EIS) spectra of the V2O3 / Zn||V2O3 full cell after cycling 0, 1, 3, 5, 100, 200, and 500 times at a high current density of 10 A / g. As can be seen from Figures a and b, the impedance measured at the open circuit voltage and the impedance after 1, 3, 5, 100, 200, and 500 cycles have the characteristic of first significantly decreasing and then tending to stabilize. Figure 8 Figures c and d show the EIS comparison of the V2O3 / Zn||V2O3 full cell and the Zn||V2O3 full cell after 0, 1, and 200 cycles. As can be seen from figures c and d, the charge transfer impedance semicircle diameter of the V2O3 / Zn||V2O3 full cell in the high-frequency region is always smaller than that of the Zn||V2O3 full cell. This proves that the vanadium oxide V2O3 anode coating effectively improves the interfacial conductivity and reduces the charge transport resistance. This demonstrates the key role of the V2O3 vanadium oxide coating in promoting electrode activation, maintaining structural stability, and optimizing interfacial dynamics, providing strong evidence for the excellent high-rate long-cycle performance of the full cell.

[0061] To further verify the effect of the vanadium oxide (V₂O₃) coating on the performance of the full cell, the V₂O₃ / Zn||V₂O₃ full cell prepared in Example 6 was subjected to cyclic voltammetry (CV) tests at 0.4, 0.6, 0.8, 1.0, 2.0, 4.0, and 6.0 mV / s (cyclic voltammetry curves). Figure 9 The Zn||V₂O₃ full cell prepared in Comparative Example 1 was subjected to CV cycling tests at 0.1, 0.2, 0.4, 0.6, and 0.8 mV / s. Figure 10 . Figure 9 Figure a shows the CV curves of the V₂O₃ / Zn||V₂O₃ full cell from 0.4 to 6.0 mV / s, and Figure b shows the peak redox currents i and v for each redox cycle. 1 / 2The linear relationship is shown in Figure c, which represents the capacitance ratio at 6.0 mV / s (shaded area), and Figure d, which represents the capacitance contribution ratio at different scan rates. Similar to the Zn||V₂O₃ full cell prepared in Comparative Example 1, the V₂O₃ / Zn||V₂O₃ full cell exhibits two pairs of redox peaks (e.g., ...). Figure 9 Figure a shows the peaks (Peak 1 (0.61–0.81 V), Peak 2 (0.99–1.11 V), Peak 3 (0.39–0.51 V), and Peak 4 (0.73–0.79 V), with curve shapes similar to those of a Zn||V₂O₃ full cell. The b-values ​​corresponding to the four peaks are 0.773, 0.911, 0.807, and 0.883, respectively (as shown in Figure a). Figure 9 (Figure b in the image) is larger than Zn||V₂O₃ ( Figure 10 This indicates that the pseudocapacitive response has a further expanding influence and has become dominant. Simultaneously, with increasing scan rate, the area under the CV curve increases, and the capacitance contribution increases from 67% at 0.4 mV / s to 97% at 6.0 mV / s (e.g., ...). Figure 9 (As shown in Figures c and d), the contribution of capacitance gradually increases.

[0062] GITT, EIS, and CV analyses demonstrate that the V2O3 / Zn||V2O3 full cell protected by the V2O3 coating exhibits good pseudocapacitive behavior and good charge transfer kinetics.

[0063] Figure 11 The figures show the discharge cycle curves of the V2O3 / Zn||V2O3 full cell of this invention at different current densities. The performance of the V2O3 / Zn||V2O3 full cell of this invention was compared with that of a previously reported single vanadium-based cathode. (V...) d -V₂O₃: Contains 5.7% V d The positive electrode of V2O3 cluster; V2O3-O d@PEDOT: V₂O₃ rich in oxygen vacancies coated with a poly(3,4-ethylenedioxythiophene) shell; VN-V₂O₃: porous nanosphere heterostructure material; V₂O₃@C: dopamine carbon and V₂O₅ V₂O₃ composite structures with carbon shells were synthesized by reduction reaction under an argon atmosphere; V₂O₃@NC: composed of V₂O₃ nanoparticles coated with a porous nitrogen-doped carbon layer; V₂O₃ / a-NVO: a crystalline-amorphous heterostructure material, with V₂O₃ as the crystalline phase and amorphous sodium vanadate (a-NVO) as the amorphous phase; V₂O₃@NC / CC: nitrogen-doped carbon-coated V₂O₃ nanospheres; V₂O₃-SP₂: a sulfur anion-doped tunnel structure V₂O₃ material; Se-V₂O₃@C-650: a selenium-doped carbon framework-supported V₂O₃ composite material; MgV₂O₄ / V₂O₃: a two-phase composite material composed of spinel phase MgV₂O₄ and V₂O₃, prepared by sol-gel method combined with calcination at 800℃ under an argon atmosphere. These studies on various vanadium-based cathodes only investigated the V₂O₃ composite materials as cathodes and did not discuss their impact on the anode or the full cell. Figure 11 It can be seen that, under the same current density, the V2O3 / Zn||V2O3 and Zn||V2O3 full cells exhibit higher specific capacity.

[0064] In summary, the vanadium oxide positive and negative electrode materials in the zinc-ion battery prepared by this invention exhibit stable performance. The use of V₂O₃ in the assembly of V₂O₃ / Zn||V₂O₃ full cells can improve the specific capacity of the zinc-ion battery, thereby enhancing its high-current cycling stability. This invention provides a green and simple new paradigm for "dual-purpose" materials in zinc-ion batteries, namely, vanadium oxide (V₂O₃) serving simultaneously as a high-performance positive electrode and an efficient negative electrode protective layer. This offers a more promising research direction for developing high-performance, low-cost, and long-life zinc-ion battery electrode materials. Furthermore, the preparation method is simple, easy to implement, and low-cost, making it suitable for large-scale production.

[0065] The above are merely specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent substitutions, or modifications made based on the present invention to solve essentially the same technical problems and achieve essentially the same technical effects are all covered within the protection scope of the present invention.

Claims

1. A method for preparing vanadium oxide positive and negative electrode materials in a zinc-ion battery, characterized in that, The preparation steps include the following: Preparation of S1.V2O3: Add 40 mL of anhydrous ethanol and 0.2–0.4 g of ammonium metavanadate to 100 mL of polytetrafluoroethylene inner liner, mix and stir for 5–10 min, then place the mixture along with the inner liner in a stainless steel reactor, keep it in an oven at 200–250 °C for 10–12 h, and then cool it naturally to obtain a mixture; wash the mixture successively with deionized water and anhydrous ethanol, and centrifuge 2–3 times until colorless to obtain a precipitate; dry the precipitate in a vacuum drying oven at 60–80 °C for 10–12 h to obtain a V2O3 precursor; place the precursor in a tube furnace, heat it to 600–700 °C at a heating rate of 5 °C / min under a nitrogen atmosphere, keep it at this temperature for 2–3 h, and then cool it to room temperature to obtain vanadium oxide V2O3; Preparation of S2.V2O3 cathode material: V2O3 obtained in S1, acetylene black, and binder A are mixed in a mass ratio of 7:2:1, and solvent A is added and ground for 1 hour to obtain grinding slurry A; 0.4-0.6 g of grinding slurry A is uniformly coated onto graphite paper with a thickness of 100 μm using a coating machine, and then placed in a vacuum oven at 60-70℃ to dry for 10-12 hours; the dried graphite paper is cut into circular pieces with a diameter of 12 mm to obtain V2O3 cathode material with coating; Preparation of S3.V2O3 / Zn negative electrode material: V2O3 obtained in S1 and binder B are mixed at a mass ratio of 8:2, and then solvent B is added and ground for 1 hour to obtain grinding slurry B; 0.4–0.6 g of grinding slurry B is uniformly coated onto the surface of a zinc foil with a thickness of 100 μm, and then dried in a vacuum oven at 60–70 °C for 10–12 h. The dried zinc foil is then cut into circular pieces with a diameter of 12 mm to obtain a coated V2O3 / Zn anode material.

2. The method for preparing vanadium oxide positive and negative electrode materials in a zinc-ion battery according to claim 1, characterized in that, The adhesive A is polyvinylidene fluoride.

3. The method for preparing vanadium oxide positive and negative electrode materials in a zinc-ion battery according to claim 1, characterized in that, The solvent A is N-methylpyrrolidone, and the amount of solvent A added is 180-200% of the total mass of V2O3, acetylene black, and binder A.

4. The method for preparing vanadium oxide positive and negative electrode materials in a zinc-ion battery according to claim 1, characterized in that, The binder B is carboxymethyl cellulose.

5. The method for preparing vanadium oxide positive and negative electrode materials in a zinc-ion battery according to claim 1, characterized in that, Solvent B is composed of anhydrous ethanol and deionized water in a mass ratio of 1:

8.

6. The method for preparing vanadium oxide positive and negative electrode materials in a zinc-ion battery according to claim 1, characterized in that, The amount of solvent B added is 180-200% of the total mass of V2O3 and binder B.

7. An application of vanadium oxide positive and negative electrode materials in a zinc-ion battery, characterized in that, The application of the vanadium oxide positive and negative electrode materials in zinc-ion batteries is carried out using the following methods and steps to assemble CR2032 type V2O3 / Zn||V2O3 full cells: Using the positive electrode shell as a substrate, 20-30 μL of electrolyte is first added. Then, the V2O3 positive electrode material is placed flat on the electrolyte, and another 20-30 μL of electrolyte is added to the coated surface of the V2O3 positive electrode material. Next, a glass fiber separator is laid on top, and 120-140 μL of electrolyte is added to fully wet it. The V2O3 / Zn negative electrode material is aligned and placed on the glass fiber separator with the coating facing the glass fiber separator. Stainless steel gaskets, spring sheets, and negative electrode shells are added in sequence. After the battery is stacked, it is placed in an electric encapsulation machine and encapsulated under a pressure of 28.1 MPa to obtain a V2O3 / Zn||V2O3 full cell.

8. The application of vanadium oxide positive and negative electrode materials in a zinc-ion battery according to claim 7, characterized in that, The electrolyte is Zn(CF3SO3)2 with a concentration of 3 mol / L.

9. The application of vanadium oxide positive and negative electrode materials in a zinc-ion battery according to claim 7, characterized in that, The glass fiber diaphragm has a diameter of 16 mm and a thickness of 675 μm.

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