A potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based positive electrode material, a preparation method and application thereof

Abstract

The application discloses a kind of vanadic potassium oxide-vanadium sulfide heterostructure vanadium-based positive electrode materials and preparation method and application, it is related to zinc ion battery positive electrode material technical field.The application is first obtained AKVO using solvothermal method, subsequently in-situ growth is introduced higher Fermi level VS2 on AKVO surface using impregnation method, constructs built-in electric field from VS2 to AKVO, so as to realize the diffusion of positive carrier to positive electrode material inside.The vanadium-based positive electrode material obtained by the method has the advantages of low cost, stable structure, sufficient active material exposure, and can overcome the slow diffusion kinetics of carriers in aqueous zinc ion battery, while inhibiting the dissolution of active material in the positive electrode material.The preparation method of the application has the advantages of simple process, wide applicability, high safety, low cost of raw materials, low operation and equipment requirements, and can be widely promoted and applied.

Description

Technical Field

[0001] This invention relates to the field of zinc-ion battery cathode materials, and in particular to a vanadium-based cathode material with a potassium aluminum vanadate oxide-vanadium sulfide heterostructure, its preparation method, and its application. Background Technology

[0002] Rechargeable aqueous zinc-ion batteries (AZIBs) have attracted significant attention in the field of large-scale energy storage due to their outstanding advantages such as low cost, high safety, and environmental friendliness. Zinc metal is abundant on Earth, has a low redox potential, and a high theoretical specific capacity (820 mAh / g), making it a highly promising anode material. The appropriate selection of cathode materials is a core element in improving battery energy density and cycle life, and is crucial for promoting the commercialization of AZIBs.

[0003] Vanadium oxides, with their open framework structure, unique microstructure, and the multivalent nature of vanadium, can undergo multi-step redox reactions from V2+ to V5+, providing abundant active sites for Zn2+ storage and becoming a research hotspot for AZIBs cathode materials. However, the practical applications of vanadium oxides are still limited by their slow reaction kinetics and unstable crystal structure: during long-term cycling, the repeated insertion and extraction of Zn2+ into and out of the vanadium oxide lattice induces significant structural deformation and lattice stress, ultimately leading to severe structural collapse and vanadium dissolution, thus restricting their electrochemical performance.

[0004] To address the aforementioned issues and improve the Zn2+ storage performance of vanadium oxides, researchers have developed various modification strategies, primarily including pre-intercalated guest substances (such as metal ions, structured water, or polymer molecules) to support the interlayer structure, constructing crystal defects, and combining with other materials. Among these, the interlayer support strategy for layered vanadium oxides can effectively expand the interlayer spacing and stabilize the crystal structure, thereby improving the cycle stability of the battery; however, the occupation of active sites by guest species hinders Zn2+ intercalation and transport, leading to a decrease in the material's specific capacity. In contrast, combining vanadium oxides with other materials to construct heterostructures is considered an effective way to optimize their electrochemical performance. Unlike simple physical mixing, the construction of heterostructures can achieve close contact between the two phase interfaces and induce the formation of a built-in electric field, thereby accelerating charge transfer and ion diffusion processes and synergistically improving the electrochemical performance of the material. Therefore, developing high-performance heterostructure vanadium-based cathode materials is key to improving the electrochemical performance of vanadium-based cathode materials and promoting the further development and application of aqueous zinc-ion batteries. Summary of the Invention

[0005] The purpose of this invention is to provide a vanadium-based cathode material with a potassium aluminum vanadate oxide-vanadium sulfide heterostructure, its preparation method, and its application, so as to solve the problems existing in the prior art.

[0006] To achieve the above objectives, the present invention provides the following solution: One of the technical solutions of the present invention: a method for preparing a vanadium-based cathode material with a potassium aluminum vanadate oxide-vanadium sulfide heterostructure, comprising the following steps: Vanadium pentoxide (V2O5), H2O2 solution and solvent are mixed to obtain solution A; potassium salt and aluminum salt are dissolved in solvent to obtain solution B; solution A and solution B are mixed and subjected to hydrothermal reaction to obtain potassium aluminum vanadate oxide (AKVO). The potassium aluminum vanadate oxide was immersed in a thioacetamide (CH3CSNH2) solution and heated and stirred to obtain the potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based cathode material (abbreviated as AKVO-VS2).

[0007] AKVO was first obtained using a solvothermal method. Then, an impregnation method was used to grow VS2, which has a higher Fermi level, in situ on the AKVO surface, constructing a built-in electric field pointing from VS2 towards AKVO. This accelerated the diffusion of positively charged carriers into the cathode material. The vanadium-based cathode material obtained by this method has the advantages of low cost, stable structure, and sufficient exposure of active materials. It also overcomes the problem of slow carrier diffusion kinetics in aqueous zinc-ion batteries, while suppressing the dissolution of active materials in the cathode material.

[0008] Furthermore, the concentration of the H2O2 solution is 30 vol%.

[0009] Furthermore, the solvents are all mixtures of anhydrous ethanol (C2H5OH) and water.

[0010] Furthermore, the ratio of vanadium pentoxide to the H2O2 solution is 1 mmol: 1~4 mL.

[0011] Furthermore, the ratio of vanadium pentoxide to solvent in solution A is 1 mmol: 10~20 mL.

[0012] Furthermore, the volume ratio of anhydrous ethanol to water in the mixed solvent used to prepare solution A is 1:0.5~1.5, that is, it is made by mixing anhydrous ethanol and water in a volume ratio of 1:0.5~1.5.

[0013] Furthermore, the potassium salt includes potassium chloride (KCl).

[0014] Furthermore, the aluminum salt includes aluminum nitrate, preferably aluminum nitrate nonahydrate (Al(NO3)3·9H2O).

[0015] Furthermore, the ratio of aluminum salt to solvent in solution B is 2 mmol: 5~15 mL.

[0016] Furthermore, the volume ratio of anhydrous ethanol to water in the mixed solvent used to prepare solution B is 1:0.5~1.5, that is, it is made by mixing anhydrous ethanol and water in a volume ratio of 1:0.5~1.5.

[0017] Furthermore, the composition of the mixed solvent (i.e., the volume ratio of anhydrous ethanol to water) used in preparing solution A and solution B can be the same or different.

[0018] Furthermore, the molar ratio of vanadium pentoxide contained in solution A, potassium salt contained in solution B, and aluminum salt contained in solution B is 1:0.1~0.5:1~3.

[0019] Furthermore, the hydrothermal reaction is carried out at a temperature of 100~160 ℃ for a time of 24~48 h.

[0020] Furthermore, the concentration of the thioacetamide solution is 0.5~2 mol / L.

[0021] Furthermore, the heating and stirring temperature is 50~80 ℃, and the time is 20~60 min.

[0022] Preferably, the heating and stirring temperature is 70 °C and the time is 40 min.

[0023] Further, the preparation steps of solution A include: adding vanadium pentoxide to a mixed solvent of anhydrous ethanol and water, dispersing it, adding H2O2 solution, and stirring evenly (stirring time is preferably 30~60 min) to obtain solution A.

[0024] Furthermore, after the hydrothermal reaction is completed, the process also includes centrifugation, washing, and drying.

[0025] Furthermore, after the heating and stirring are completed, the process also includes centrifugation, washing, and drying.

[0026] Preferably, the washing is performed using ethanol and deionized water.

[0027] Preferably, the drying temperature is 40~80 ℃ and the drying time is 8~24 h.

[0028] The second technical solution of the present invention: A vanadium-based cathode material with a potassium aluminum vanadate oxide-vanadium sulfide heterostructure prepared by the above-described method.

[0029] The third technical solution of the present invention: the application of the above-mentioned potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based cathode material in the preparation of cathode electrode sheets or aqueous zinc-ion batteries.

[0030] The fourth technical solution of the present invention: a positive electrode sheet, wherein the raw material of the positive electrode sheet includes the above-mentioned potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based positive electrode material.

[0031] The fifth technical solution of the present invention: an aqueous zinc-ion battery, wherein the raw materials of the aqueous zinc-ion battery include the above-mentioned potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based cathode material.

[0032] Furthermore, the negative electrode of the aqueous zinc-ion battery is zinc foil, the electrolyte is zinc trifluoromethanesulfonate solution, and the separator is a glass fiber separator.

[0033] Furthermore, the concentration of zinc trifluoromethanesulfonate in the electrolyte is 1~3 mol / L.

[0034] Furthermore, the preparation steps of the positive electrode sheet of the aqueous zinc-ion battery include: uniformly mixing the potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based positive electrode material, conductive carbon black, polyvinylidene fluoride (PVDF) and N-methylpyrrolidone to form a slurry, coating it on titanium foil, and drying it to obtain the positive electrode sheet.

[0035] Preferably, the mass ratio of the potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based cathode material, conductive carbon black, and polyvinylidene fluoride is 7:2:1.

[0036] Preferably, the positive electrode material loading of the positive electrode sheet is 1.5~3 mg / cm³. 2 .

[0037] The sixth technical solution of the present invention: a method for improving the zinc ion transport dynamics of vanadium-based cathode materials by constructing a built-in electric field in a heterojunction, wherein the zinc ion transport dynamics of vanadium-based cathode materials are improved by constructing a potassium aluminum vanadate oxide-vanadium sulfide heterostructure. The steps for constructing the potassium aluminum vanadate oxide-vanadium sulfide heterostructure include: Vanadium pentoxide, H2O2 solution, and solvent are mixed to obtain solution A; potassium salt and aluminum salt are dissolved in solvent to obtain solution B; solution A and solution B are mixed and subjected to a hydrothermal reaction to obtain potassium aluminum vanadate oxide; The potassium aluminum vanadate oxide was immersed in a thioacetamide solution and heated and stirred to obtain a vanadium-based cathode material with a potassium aluminum vanadate oxide-vanadium sulfide heterostructure.

[0038] To address the sluggish carrier diffusion kinetics problem faced by current aqueous zinc-ion battery cathode materials, this invention provides a method for improving the zinc-ion transport kinetics of vanadium-based cathode materials by constructing a built-in electric field in a heterojunction. This method utilizes an electric field to drive the rapid diffusion of positively charged zinc ions into the cathode material. This process is not only simple and controllable, but also effectively improves the sluggish carrier insertion kinetics without compromising the intrinsic electrochemical activity of the cathode material, while significantly enhancing the cycle stability of the cathode material. This invention provides a novel approach for the design and development of high-performance aqueous zinc-ion batteries, possessing significant scientific research value and broad practical application prospects.

[0039] The present invention discloses the following technical effects: 1. The preparation method provided by this invention first obtains AKVO using a solvothermal method, and then uses an impregnation method to grow VS2 with a higher Fermi level in situ on the surface of AKVO, constructing a built-in electric field from VS2 towards AKVO, thereby accelerating the diffusion of positively charged carriers into the cathode material. The vanadium-based cathode material obtained by this method has the advantages of low cost, stable structure, and sufficient exposure of active materials, and can overcome the problem of slow carrier diffusion kinetics in aqueous zinc-ion batteries, while suppressing the dissolution of active materials in the cathode material.

[0040] 2. The preparation method of the present invention is simple, widely applicable, safe, and has low raw material cost and low operation and equipment requirements, and can be promoted and applied on a large scale. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 The XRD patterns are of the potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based cathode materials prepared in Examples 1-3 and the potassium aluminum vanadate oxide cathode material prepared in Comparative Example 1.

[0043] Figure 2 The image shows a SEM image of the potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based cathode material prepared in Example 1.

[0044] Figure 3 The image shows the elemental mapping of the potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based cathode material prepared in Example 1.

[0045] Figure 4The graph shows the cycling performance of an aqueous zinc-ion battery assembled using the potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based cathode material prepared in Example 1 at a constant current of 5 A / g.

[0046] Figure 5 The graph shows the cycling performance of an aqueous zinc-ion battery assembled using the potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based cathode material prepared in Example 2 at a constant current of 5 A / g.

[0047] Figure 6 The graph shows the cycling performance of an aqueous zinc-ion battery assembled using the potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based cathode material prepared in Example 3 at a constant current of 5 A / g.

[0048] Figure 7 The graph shows the cycling performance of an aqueous zinc-ion battery assembled using the potassium aluminum vanadate oxide cathode material prepared in Comparative Example 1 at a constant current of 5 A / g. Detailed Implementation

[0049] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0050] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0051] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0052] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0053] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0054] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0055] Unless otherwise specified, the room temperature mentioned in the following examples and comparative examples refers to 20-30 ℃.

[0056] Unless otherwise specified, the experimental methods used in the following examples and comparative examples are conventional methods; and the reagents, materials and equipment used are commercially available unless otherwise specified.

[0057] Example 1 1. Preparation of vanadium-based cathode material with potassium aluminum vanadate oxide-vanadium sulfide heterostructure, the steps are as follows: Preparation of S1, potassium aluminum vanadate oxide (AKVO): 2 mmol V₂O₅ was added to a mixed solvent of 16 mL C₂H₅OH and 15 mL deionized water, dispersed, and then 5 mL of 30 vol% H₂O₂ solution was added and stirred for 30 min until homogeneous, yielding solution A. 0.2 mmol KCl and 2 mmol Al(NO₃)₃·9H₂O were dissolved in a mixed solvent of 5 mL C₂H₅OH and 4 mL deionized water, yielding solution B. Solution B was added dropwise to solution A and stirred to disperse evenly. The homogeneous mixture was then transferred to a 100 mL Teflon-lined stainless steel autoclave and heated at 160 °C for 24 h. After the reaction, the mixture was cooled to room temperature, centrifuged, washed with ethanol and deionized water, and then vacuum dried at 60 °C for 12 h to obtain AKVO powder.

[0058] S2. Preparation of vanadium-based cathode materials with potassium aluminum vanadate oxide-vanadium sulfide heterostructure: All the AKVO powder obtained in step S1 was immersed in 30 mL of 1 mol / L CH3CSNH2 solution (solvent is water) at 70 ℃, stirred at 70 ℃ for 40 min, cooled to room temperature, centrifuged, washed with ethanol and deionized water, and vacuum dried at 60 ℃ for 12 h to obtain potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based cathode material (abbreviated as AKVO-VS2-4).

[0059] The X-ray diffraction (XRD) pattern of the potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based cathode material prepared in this embodiment is shown below. Figure 1As shown, the heterostructure sample contains a distinct VS2 peak, proving the presence of VS bonds, and its structure (chemical formula) is H. 11 Al2V6O 23.2 (AKVO)-VS2.

[0060] Figure 2 The image shown is a scanning electron microscope (SEM) image of the potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based cathode material prepared in this embodiment. It can be seen that the microstructure of the obtained cathode material is sheet-like.

[0061] Figure 3 The mapping elemental analysis diagram of the potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based cathode material prepared in this embodiment shows that V, Al, K, S and O elements are uniformly distributed.

[0062] 2. The preparation steps of a rechargeable aqueous zinc-ion battery are as follows: (1) Preparation of the positive electrode sheet: The potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based cathode material prepared above, conductive carbon black (acetylene black), polyvinylidene fluoride (PVDF), and N-methylpyrrolidone were mixed uniformly to form a slurry (the mass ratio of cathode material, conductive carbon black, and PVDF was 7:2:1). This slurry was coated onto a titanium foil (the thickness of the titanium foil was 20 μm), and after drying, a cathode electrode sheet (the cathode material loading was 1.5 mg / cm³) was obtained. 2 ).

[0063] (2) Preparation of negative electrode sheet: The negative electrode is a zinc foil with a thickness of 20 μm. The oxide layer is removed by sonication with acetone for 20 min, then rinsed with ethanol and dried to obtain the negative electrode sheet.

[0064] (3) Preparation of electrolyte: Weigh 2 mmol of zinc trifluoromethanesulfonate (Zn(CF3SO3)2) and dissolve it in 1 mL of deionized water to prepare an electrolyte (concentration of 2 mol / L).

[0065] (4) Battery fabrication: The electrode plates are placed in the battery case, and a Whatman glass fiber (GF / D) separator is placed between the positive and negative electrode plates. 70 μL of electrolyte is added, and then the battery is encapsulated to obtain a rechargeable aqueous zinc-ion battery (specifically a CR2032 coin cell).

[0066] 3. Battery performance test: The cycle performance of zinc-ion batteries was tested under a constant temperature environment of 25 ℃, with a current density of 5 A / g and a cutoff voltage of 0.2-1.6 V.Figure 4 The graph shows the cycling performance of an aqueous zinc-ion battery assembled using the potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based cathode material prepared in this embodiment under a constant current of 5 A / g. It can be seen that at a current density of 5 A / g, the initial discharge specific capacity of the potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based cathode material prepared in this embodiment is 126.7 mAh / g, the discharge specific capacity after 10,000 cycles is 138.5 mAh / g, and the discharge specific capacity remains at 106.8 mAh / g after 40,000 cycles, with a capacity retention rate of 84.3% during 40,000 cycles. This indicates that the potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based cathode material prepared in this embodiment exhibits a large specific capacity and a high capacity retention rate when applied to zinc-ion batteries.

[0067] Example 2 1. Preparation of vanadium-based cathode materials with potassium aluminum vanadate oxide-vanadium sulfide heterostructure: The preparation steps are the same as in Example 1, except that in step S2, the stirring time of AKVO powder in CH3CSNH2 solution is adjusted to 60 min. The final product is referred to as AKVO-VS2-6.

[0068] The XRD pattern of the potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based cathode material prepared in this embodiment is as follows: Figure 1 As shown, its structure is AKVO-VS2 after XRD analysis.

[0069] 2. Preparation of rechargeable aqueous zinc-ion batteries: The preparation steps are the same as in Example 1, except that the vanadium-based cathode material with a potassium aluminum vanadate oxide-vanadium sulfide heterostructure prepared in this example is used as the cathode material.

[0070] 3. Battery performance test: The cycle performance of zinc-ion batteries was tested under a constant temperature environment of 25 ℃, with a current density of 5 A / g and a cutoff voltage of 0.2-1.6 V. Figure 5 The graph shows the cycling performance of an aqueous zinc-ion battery assembled using the potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based cathode material prepared in this embodiment at a constant current of 5 A / g. It can be seen that at a current density of 5 A / g, the initial discharge specific capacity of the potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based cathode material prepared in this embodiment is 94.9 mAh / g, and the discharge specific capacity after 5000 cycles is 82.5 mAh / g.

[0071] Example 3 1. Preparation of vanadium-based cathode materials with potassium aluminum vanadate oxide-vanadium sulfide heterostructure: The preparation steps are the same as in Example 1, except that in step S2, the stirring time of AKVO powder in CH3CSNH2 solution is adjusted to 20 min. The final product is referred to as AKVO-VS2-2.

[0072] The XRD pattern of the potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based cathode material prepared in this embodiment is as follows: Figure 1 As shown, its structure is AKVO-VS2 after XRD analysis.

[0073] 2. Preparation of rechargeable aqueous zinc-ion batteries: The preparation steps are the same as in Example 1, except that the vanadium-based cathode material with a potassium aluminum vanadate oxide-vanadium sulfide heterostructure prepared in this example is used as the cathode material.

[0074] 3. Battery performance test: The cycle performance of zinc-ion batteries was tested under a constant temperature environment of 25 ℃, with a current density of 5 A / g and a cutoff voltage of 0.2-1.6 V. Figure 6 The graph shows the cycling performance of an aqueous zinc-ion battery assembled using the potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based cathode material prepared in this embodiment at a constant current of 5 A / g. It can be seen that at a current density of 5 A / g, the initial discharge specific capacity of the potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based cathode material prepared in this embodiment is 145.7 mAh / g, and the discharge specific capacity after 10,000 cycles is 80.3 mAh / g.

[0075] Comparative Example 1 1. Preparation of potassium aluminum vanadate oxide (AKVO) cathode material, the steps are as follows: 2 mmol V₂O₅ was added to a mixed solvent of 16 mL C₂H₅OH and 15 mL deionized water, dispersed, and then 5 mL of 30 vol% H₂O₂ solution was added and stirred for 30 min until homogeneous, yielding solution A. 0.2 mmol KCl and 2 mmol Al(NO₃)₃·9H₂O were dissolved in a mixed solvent of 5 mL C₂H₅OH and 4 mL deionized water, yielding solution B. Solution B was added dropwise to solution A and stirred to disperse evenly. The homogeneous mixture was then transferred to a 100 mL Teflon-lined stainless steel autoclave and heated at 160 °C for 24 h. After the reaction, the mixture was cooled to room temperature, centrifuged, washed with ethanol and deionized water, and then vacuum dried at 60 °C for 12 h to obtain AKVO powder.

[0076] The XRD pattern of the potassium aluminum vanadate oxide cathode material prepared in this comparative example is as follows: Figure 1 As shown, its structure is AKVO after XRD analysis.

[0077] 2. Preparation of rechargeable aqueous zinc-ion batteries: The preparation steps are the same as in Example 1, except that the potassium aluminum vanadate oxide cathode material prepared in this comparative example is used as the cathode material.

[0078] 3. Battery performance test: The cycle performance of zinc-ion batteries was tested under a constant temperature environment of 25 ℃, with a current density of 5 A / g and a cutoff voltage of 0.2-1.6 V. Figure 7 The graph shows the cycling performance of an aqueous zinc-ion battery assembled using the potassium aluminum vanadate cathode material prepared in this comparative example under a constant current of 5 A / g. It can be seen that at a current density of 5 A / g, the initial discharge specific capacity of the potassium aluminum vanadate cathode material is 79.8 mAh / g, and after 10,000 cycles, the discharge specific capacity is reduced to only 60.7 mAh / g, with a capacity retention rate of 76.1% during cycling. This indicates that the potassium aluminum vanadate cathode material prepared in this comparative example has poor specific capacity and capacity retention when applied to zinc-ion batteries.

[0079] Comparing Comparative Example 1 with Example 1, it can be seen that the potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based cathode material prepared in Example 1 exhibits better cycle stability and higher specific capacity. This is because introducing VS2, which has a higher Fermi level, onto the surface of potassium aluminum vanadate oxide can construct a built-in electric field pointing from VS2 towards AKVO, thereby accelerating the diffusion of positively charged carriers into the cathode material. The potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based cathode material obtained by the method of Example 1 can overcome the problem of slow carrier diffusion kinetics in aqueous zinc-ion batteries, while suppressing the dissolution of active materials in the cathode. In contrast, potassium aluminum vanadate oxide AKVO suffers from slow carrier diffusion kinetics and dissolution of active materials in the cathode.

[0080] Furthermore, the discharge specific capacity of the potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based cathode material prepared in Example 1 began to decrease after more than 10,000 cycles, exhibiting a process of initial increase followed by decrease. This is because the potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based cathode material of the present invention undergoes a polarization process in the initial stage of cycling, followed by catalyst stabilization and built-in electric field stabilization. The capacity only begins to decrease after reaching its peak. AKVO, however, lacks this polarization-restabilization process, resulting in poor performance.

[0081] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing a vanadium-based cathode material with a potassium aluminum vanadate oxide-vanadium sulfide heterostructure, characterized in that, Includes the following steps: Vanadium pentoxide, H2O2 solution, and solvent are mixed to obtain solution A; potassium salt and aluminum salt are dissolved in solvent to obtain solution B; solution A and solution B are mixed and subjected to a hydrothermal reaction to obtain potassium aluminum vanadate oxide; The potassium aluminum vanadate oxide was immersed in a thioacetamide solution and heated and stirred to obtain the potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based cathode material.

2. The preparation method of the potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based cathode material as described in claim 1, characterized in that, The concentration of the H2O2 solution is 30 vol%. And / or, the solvents are all mixtures of anhydrous ethanol and water; And / or, the ratio of vanadium pentoxide to the H2O2 solution is 1 mmol: 1~4 mL.

3. The preparation method of the potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based cathode material as described in claim 1, characterized in that, The potassium salt includes potassium chloride; And / or, the aluminum salt includes aluminum nitrate; And / or, the molar ratio of vanadium pentoxide contained in solution A, potassium salt contained in solution B, and aluminum salt contained in solution B is 1:0.1~0.5:1~3; And / or, the hydrothermal reaction is carried out at a temperature of 100~160 ℃ for a time of 24~48 h.

4. The preparation method of the potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based cathode material as described in claim 1, characterized in that, The concentration of the thioacetamide solution is 0.5~2 mol / L; And / or, the heating and stirring temperature is 50~80 ℃, and the time is 20~60 min.

5. A vanadium-based cathode material with a potassium aluminum vanadate oxide-vanadium sulfide heterostructure prepared by the preparation method of the vanadium-based cathode material with a potassium aluminum vanadate oxide-vanadium sulfide heterostructure as described in any one of claims 1-4.

6. The application of the potassium aluminum vanadate oxide-vanadium sulfide heterostructure vanadium-based cathode material as described in claim 5 in the preparation of cathode electrode sheets or aqueous zinc-ion batteries.

7. A positive electrode sheet, characterized in that, The raw material for the positive electrode sheet includes the vanadium-based positive electrode material with a potassium aluminum vanadate oxide-vanadium sulfide heterostructure as described in claim 5.

8. An aqueous zinc-ion battery, characterized in that, The raw materials for the aqueous zinc-ion battery include the vanadium-based cathode material with a potassium aluminum vanadate oxide-vanadium sulfide heterostructure as described in claim 5.

9. A method for improving zinc ion transport dynamics in vanadium-based cathode materials by constructing a built-in electric field in a heterojunction, characterized in that, By constructing a potassium aluminum vanadate oxide-vanadium sulfide heterostructure, the zinc ion transport kinetics of vanadium-based cathode materials can be improved.

10. The method for improving zinc ion transport dynamics in vanadium-based cathode materials by constructing a built-in electric field in a heterojunction as described in claim 9, characterized in that... The steps for constructing the potassium aluminum vanadate oxide-vanadium sulfide heterostructure include: Vanadium pentoxide, H2O2 solution, and solvent are mixed to obtain solution A; potassium salt and aluminum salt are dissolved in solvent to obtain solution B; solution A and solution B are mixed and subjected to a hydrothermal reaction to obtain potassium aluminum vanadate oxide; The potassium aluminum vanadate oxide was immersed in a thioacetamide solution and heated and stirred to obtain a vanadium-based cathode material with a potassium aluminum vanadate oxide-vanadium sulfide heterostructure.

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