Modified positive electrode structure, method for preparing the same, zinc vanadium battery, and method for preparing the same

Abstract

This invention provides a modified positive electrode structure, a zinc-vanadium battery, and a method for preparing the same. [Solution] The zinc-vanadium battery comprises a modified positive electrode structure (including a positive electrode and a modified layer), a separator, a negative electrode, and an aqueous electrolyte. The positive electrode contains titanium. The modified layer is located on the positive electrode and contains 70-95 parts by weight of vanadium-based material, 3-45 parts by weight of conductive agent, and 3-45 parts by weight of binder. The separator is located on the modified layer. The negative electrode contains zinc and is located on the separator. The positive electrode, modified layer, separator, and negative electrode are all in the aqueous electrolyte. In the X-ray diffraction pattern of the vanadium-based material measured by XRD using CuKα1 rays, the peak intensity at 2θ=8°±1.0° is I8, and the peak intensity at 2θ=20°±1.0° is I 20 In that case, I8 and I 20 The ratio (I8 / I 20 ) is 0 <I8 / I 20 The condition ≤ 1.4 is satisfied. Furthermore, a modified cathode structure, a method for preparing the modified cathode structure, and a method for preparing a zinc-vanadium battery are also provided.

Description

[Technical Field]

[0001] The present invention relates to a modified cathode structure and a method for preparing the same, and more particularly to a modified cathode structure comprising a modified vanadium-based material and a method for preparing the same. The present invention also relates to a zinc-vanadium battery and a method for preparing the same, and more particularly to a zinc-vanadium battery comprising a modified cathode structure and a method for preparing the same. [Background technology]

[0002] Conventional batteries using zinc as the negative electrode have numerous structural and characteristic limitations. For example, the capacity per gram of a battery using zinc as the negative electrode is only about 100-200 mAh / g, and there is still room for improvement. Furthermore, in the initial stages of charging and discharging such batteries using zinc as the negative electrode, the discharge environment of the battery is not perfectly balanced, resulting in an unstable discharge reaction.

[0003] Furthermore, in batteries using zinc as the negative electrode, zinc plating products gradually accumulate on the negative electrode during use, and these then grow into dendritic crystals (also called dendrites) in the electrolyte. These dendrites then pierce the separator, causing battery failure. [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] To address the aforementioned problems, the inventors of this application recognize that electrolyte preparation is commonly used in their respective technical fields. However, while this improvement method can enhance the discharge performance of batteries, it results in relatively high process technology costs. [Means for solving the problem]

[0005] Therefore, some embodiments propose a modified cathode structure comprising a cathode and a modified layer. The cathode contains titanium. The modified layer is located on the cathode and contains 70-95 parts by weight of vanadium-based material, 3-45 parts by weight of conductive agent, and 3-45 parts by weight of binder. In the X-ray diffraction pattern of the vanadium-based material measured by an X-ray diffractometer (XRD) using CuKα1 rays, the peak intensity at 2θ = 8° ± 1.0° is I8, and the peak intensity at 2θ = 20° ± 1.0° is I 20 In that case, I8 and I 20 The ratio (I8 / I 20 ) is 0 <I8 / I 20 It satisfies ≤ 1.4.

[0006] Furthermore, some embodiments propose a method for preparing a modified cathode structure that includes a first homogenization step, a drying step, a second homogenization step, and a coating step. The first homogenization step includes mixing and homogenizing vanadium oxide, water, and hydrogen peroxide to obtain a vanadium-based homogeneous mixture. The drying step includes freeze-drying or heat-drying the vanadium-based homogeneous mixture to obtain a vanadium-based material. The second homogenization step includes mixing and homogenizing the vanadium-based material, a conductive agent, and a binder to obtain a modified material. The coating step includes coating the modified material onto the cathode to form a modified layer on the cathode, thereby obtaining a modified cathode structure.

[0007] Furthermore, some embodiments propose a zinc-vanadium battery comprising a modified cathode structure (including a cathode and a modified layer), a separator, a negative electrode, and an aqueous electrolyte. The cathode contains titanium. The modified layer is located on the cathode and contains 70-95 parts by weight of vanadium-based material, 3-45 parts by weight of conductive agent, and 3-45 parts by weight of binder. The separator is located on the modified layer. The negative electrode contains zinc and is located on the separator. The cathode, modified layer, separator, and negative electrode are in an aqueous electrolyte. In the X-ray diffraction pattern of the vanadium-based material measured by XRD using CuKα1 rays, the peak intensity at 2θ=8°±1.0° is I8, and the peak intensity at 2θ=20°±1.0° is I 20 In that case, I8 and I 20 The ratio (I8 / I 20 ) is 0 <I8 / I20 Satisfies ≤ 1.4.

[0008] Some embodiments also propose a method for preparing a zinc vanadium battery, including a first homogenization step, a drying step, a second homogenization step, a coating step, and an assembly step. The first homogenization step includes mixing vanadium oxide, water, and hydrogen peroxide and homogenizing them to obtain a vanadium-based homogeneous mixture. The drying step includes freeze-drying or heat-drying the vanadium-based homogeneous mixture to obtain a vanadium-based material. The second homogenization step includes mixing the vanadium-based material, a conductive agent, and a binder and homogenizing them to obtain a modified material. The coating step includes coating the modified material on the positive electrode to form a modified layer on the positive electrode. The assembly step includes sequentially assembling a separator and a negative electrode on the modified layer, and immersing the positive electrode, the modified layer, the separator, and the negative electrode in an aqueous electrolyte to obtain a zinc vanadium battery.

[0009] The following drawings are only used for detailed description for illustrative purposes so as to understand some embodiments of the present invention more comprehensively, but are not intended to limit the scope of the present invention by these embodiments.

Brief Description of Drawings

[0010] [Figure 1] It is a schematic configuration diagram of a zinc vanadium battery including a modified positive electrode structure according to some embodiments. [Figure 2] It is a flowchart of a method for preparing a zinc vanadium battery including a modified positive electrode structure according to some embodiments. [Figure 3A] It is an X-ray diffraction pattern of a vanadium-based material of a comparative example (known to the inventors of the present application) measured by XRD using CuKα1 line. [Figure 3B] It is an X-ray diffraction pattern of a vanadium-based material of Example 1 (some embodiments of the present invention) measured by XRD using CuKα1 line. [Figure 3C]X-ray diffraction pattern of the vanadium-based material of Example 2 (another embodiment of the present invention) measured by XRD using CuKα1 line. [Figure 4] Comparison diagram of discharge capacities of zinc-vanadium batteries containing the vanadium-based material of the comparative example and zinc-vanadium batteries containing the vanadium-based material of Example 2. [Figure 5] Comparison diagram of average lifetimes of zinc-vanadium batteries containing the vanadium-based material of the comparative example and zinc-vanadium batteries containing the vanadium-based material of Example 2.

Embodiments for Carrying out the Invention

[0011] The term "about" may vary depending on different techniques and within the range of deviations understood by those skilled in the art. The term "about" associated with a specific distance or dimension may be interpreted as not excluding a slight deviation from the specified distance or dimension. For example, the term "about" may include a deviation of up to 10% of the specified amount, but the embodiments of the present disclosure are not limited thereto. The term "about" associated with a numerical value x may indicate x ± 5 or 10% of the specified amount, but the embodiments of the present disclosure are not limited thereto.

[0012] Referring to FIG. 1, FIG. 1 is a schematic configuration diagram of a zinc-vanadium battery 1 including a modified positive electrode structure according to some embodiments. In FIG. 1, the modified positive electrode structure includes a positive electrode 10 and a modified layer 12. The positive electrode 10 contains titanium (Ti), and the modified layer 12 is located on the positive electrode 10. The modified layer includes a vanadium-based material, a conductive agent, and a binder. In the X-ray diffraction pattern of the vanadium-based material measured by an X-ray diffractometer (XRD) using CuKα1 line, the peak intensity at 2θ = 8° ± 1.0° is I8, and the peak intensity at 2θ = 20° ± 1.0° is I 20 When taken as 20 The ratio (I8 / I 20 ) where 0 < I8 / I 20The condition ≤1.4 is satisfied (details will be described later). In Figure 1, the zinc-vanadium battery 1 includes the above-mentioned modified positive electrode structure (including the positive electrode 10 and the modified layer 12), a separator 14, a negative electrode 16, and an aqueous electrolyte 18. The separator 14 is located on the modified layer 12, and the negative electrode 16 contains zinc (Zn) and is located on the separator 14. The positive electrode 10, the modified layer 12, the separator 14, and the negative electrode 16 are all in the aqueous electrolyte 18. As a result, compared to zinc-vanadium batteries known to the inventors (without the above-mentioned modified positive electrode structure), the zinc-vanadium battery 1 including the above-mentioned modified positive electrode structure can have more stable charge and discharge performance, higher battery capacity, and a longer lifespan (details will be described later).

[0013] The positive electrode 10 may be a metal foil or a metal material having a porous structure (e.g., a metal mesh). The positive electrode 10 may be a titanium-containing metal foil (e.g., titanium foil) or a metal material having a porous structure (e.g., a titanium mesh with a mesh size of about 100 to 500 nm). The thickness of the positive electrode 10 may be 5 to 50 μm, or for example, about 10 to 50 μm, but is not limited thereto. The thickness can be adjusted according to requirements such as physical properties such as tensile strength.

[0014] The modified layer 12 described above comprises 70 to 95 parts by weight of vanadium-based material, 3 to 45 parts by weight of conductive agent, and 3 to 45 parts by weight of binder. The total weight of the vanadium-based material, conductive agent, and binder is not limited to 100 parts by weight, but can be adjusted to less than 100 parts by weight or more than 100 parts by weight as needed. In some embodiments, the weights of the vanadium-based material, conductive agent, and binder are 80 parts by weight, 10 parts by weight, 10 parts by weight, or 90 parts by weight, 5 parts by weight, 5 parts by weight, or 92 parts by weight, 5 parts by weight, and 3 parts by weight, respectively, but are not limited to these. If the vanadium-based material, conductive agent, and binder are not added in the respective weight parts described above, even if the modified cathode structure contains the vanadium-based material, at least one of the charge / discharge performance, battery capacity, and lifespan of a zinc-vanadium battery manufactured according to the above weight ratio cannot be significantly better than the performance of a zinc-vanadium battery known to the inventors (without the above modified cathode structure). The thickness of the modified layer 12 is 50 to 90 μm, but is not limited thereto.

[0015] The vanadium-based materials described above, as measured by XRD using CuKα1 radiation, showed a peak intensity of I8 at 2θ = 8° ± 1.0° and a peak intensity of I8 at 2θ = 20° ± 1.0° in their X-ray diffraction patterns. 20 In that case, I8 and I 20 The ratio (I8 / I 20 ) is 0 <I8 / I 20 The condition ≤ 1.4 is satisfied (details below). In some embodiments, I8 / I 20 is 1.1 ≤ I8 / I 20 Satisfying ≤1.4. In some embodiments, I8 / I 20 is 1.13 ≤ I8 / I 20 The condition satisfies ≤1.35. In some embodiments, I8 / I 20I8 is any value between 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, or 0 and any of the above values, or any value between any two of the above values. In some embodiments, I8 refers to the peak intensity at 2θ = 8° ± 0.5°, and I 20 This refers to the peak intensity at 2θ = 20° ± 0.5°. I8 / I for vanadium-based materials. 20 If the value is not within the above range (for example, below the lower limit of the above range or above the upper limit of the above range), even if the modified cathode structure contains vanadium-based material, at least one of the charge / discharge performance, battery capacity, and lifespan of a zinc-vanadium battery manufactured according to the above weight ratio cannot be significantly better than the performance of a zinc-vanadium battery known to the inventors (without the above modified cathode structure).

[0016] Referring to Figure 2, Figure 2 is a flowchart of a method 2 for preparing a zinc-vanadium battery 1 including a modified cathode structure according to several embodiments. The vanadium-based material may be a vanadium-based material prepared through some steps of method 2 in Figure 2, for example, obtained through step S20 or steps S20-S21 in Figure 2 (details will be described later). Therefore, the vanadium-based material may include vanadium oxide or its derivatives, which are the initial material used in step S20 in Figure 2, and the vanadium-based material I8 and I 20 The ratio to the aforementioned relationship is also given by, for example, 0 <I8 / I 20 The above vanadium oxide satisfies ≤ 1.4. x O y The compound may contain any compound represented by (x and y are both positive numbers), and the possibility of doping with impurities that do not affect the physicochemical properties of vanadium oxide is not ruled out. For example, the vanadium oxide or its derivatives may include V2O5, VO2, NaV3O8·1.5H2O, LiV3O8, Na2V6O 16 • 1.63H2O, Fe5V 15 O 39 (OH)9·9H2O, Zn3V2O7(OH)2·2H2O, and a mixture of two or more of their derivatives may be used.

[0017] The conductive agent may include at least one selected from conductive carbon black and carbon nanotubes (CNTs). The conductive carbon black may be any commercially available conductive carbon black, but may include at least one selected from, for example, acetylene black, Ketjenblack, Super P, XC-72, N220, N330, N550, S204, FW200, VGCF, and KS6. In other words, the conductive carbon black may be a mixture of one or more of acetylene black, Ketjenblack, Super P, XC-72, N220, N330, N550, S204, FW200, VGCF, and KS6. In some embodiments, the conductive carbon black includes Super P or a mixture thereof. The above-mentioned CNTs may be various commercially available CNTs, and may include, for example, at least one selected from single-walled carbon nanotubes (SCNTs) and multi-walled carbon nanotubes (MCNTs). In other words, the CNTs may be a mixture of one or more types of SCNTs and MCNTs.

[0018] The above binder may contain at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), and polyimide (PI). In other words, the binder may be a mixture of one or more of PVDF, PTFE, CMC, SBR, and PI. In some embodiments, the binder contains at least one selected from PVDF and PTFE. In some embodiments, the binder contains PVDF or a mixture thereof.

[0019] Please refer to Figure 1. The separator 14 may contain at least one selected from cellulose, synthetic fibers, and glass fibers. Examples of synthetic fibers include polyester fibers or polyaramid fibers. In some embodiments, the separator 14 contains at least one selected from cellulose and glass fibers. The thickness of the separator 14 is 30 to 400 μm, but is not limited thereto.

[0020] Please continue to refer to Figure 1. The negative electrode 16 may be a metal foil or a metal material having a porous structure (e.g., a metal mesh). The negative electrode 16 may be a metal foil containing zinc (e.g., zinc foil) or a metal material having a porous structure (e.g., a zinc mesh with a mesh size not exceeding 1 μm). The purity of the zinc is, for example, 95 wt% or more relative to the metal foil or metal material. The thickness of the negative electrode 16 may be, but is not limited to, 10 to 50 μm, or for example, about 20 to 50 μm. In some embodiments, the negative electrode 16 is a metal foil containing zinc (e.g., zinc foil), and the positive electrode 10 is a metal foil containing titanium (e.g., titanium foil).

[0021] Please continue to refer to Figure 1. The aqueous electrolyte 18 may be various organic or inorganic salts that dissolve in water and release the same metal ions as the metal contained in the negative electrode 16. For example, when a metal foil containing zinc is used for the negative electrode 16, the aqueous electrolyte 18 must be selected to contain an organic or inorganic salt that can release zinc ions (the same as the metallic zinc ions contained in the negative electrode 16) after dissolving in water. In this case, the aqueous electrolyte 18 may contain at least one selected from, for example, zinc triflate (Zn(OTf)2) and zinc sulfate (ZnSO4). In some embodiments, the aqueous electrolyte 18 is an aqueous solution containing Zn(OTf)2 and water, and the weight ratio of Zn(OTf)2 to water may be 1:1 to 3:7, for example about 4:6, but is not limited thereto. In some embodiments, the aqueous electrolyte 18 is an aqueous solution containing 1 to 5 M Zn(OTf)2, for example an aqueous solution containing 2 M Zn(OTf)2. In some embodiments, the aqueous electrolyte 18 is an aqueous solution containing ZnSO4 and water. In some embodiments, the aqueous electrolyte 18 is an aqueous solution containing 0.5 to 3 M ZnSO4.

[0022] Next, please refer to Figure 2 in conjunction with Figure 1. Figure 2 shows a method for preparing a modified positive electrode structure and a method 2 for preparing a zinc vanadium battery 1 including the modified positive electrode structure. It should be noted that before preparing a zinc vanadium battery 1 including the modified positive electrode structure, it is necessary to first prepare the modified positive electrode structure. In other words, the method for preparing the modified positive electrode structure can be included in method 2 for preparing a zinc vanadium battery 1 including the modified positive electrode structure. For example, the method for preparing the modified positive electrode structure may be steps S20 to S23 of method 2, and method 2 for preparing a zinc vanadium battery 1 including the modified positive electrode structure can be completed by assembling the modified positive electrode structure, separator 14 and negative electrode 16 obtained through steps S20 to S23 according to step S24, and immersing these structures in an aqueous electrolyte 18.

[0023] For more details, please refer to Figure 2. The method 2 for preparing a zinc-vanadium battery 1 including a modified cathode structure may include steps S20 to S24.

[0024] Step S20 is a first homogenization step, which includes mixing and homogenizing vanadium oxide, water, and hydrogen peroxide to obtain a vanadium-based homogeneous mixture. For example, step S20 involves homogenizing (e.g., stirring) vanadium oxide, water, and hydrogen peroxide in a weight ratio of 7:120:2 to 7:120:12 for 12 to 15 hours under normal conditions to obtain a vanadium-based homogeneous mixture. The above normal conditions may be a process environment with a humidity of 40% or less. In some embodiments, step S20 is carried out at room temperature and atmospheric pressure. In some embodiments, the weights of vanadium oxide, water, and hydrogen peroxide are 35g, 600g, and 10g (i.e., 7:120:2), or 35g, 600g, and 20g (i.e., 7:120:4), or 35g, 600g, and 60g (i.e., 7:120:12). In other words, the weight ratio of water to hydrogen peroxide may be 60:1, 30:1, or 10:1. Specific embodiments of the vanadium oxide described above can be found in the preceding text, so a detailed explanation is omitted here. The water and hydrogen peroxide may be, but are not limited to, commercially available or laboratory-grade water and hydrogen peroxide available to a person with ordinary skill in the art. In step S20, the reaction between hydrogen peroxide and vanadium oxide forms a layered structure in which the crystals of vanadium oxide itself are stacked, and the interlayer spacing of these layered structures is expanded and further enlarged. Because the interlayer spacing between these layered structures is enlarged, it is possible to provide greater charge storage during the subsequent charge-discharge process of the zinc-vanadium battery 1, and the difficulty of ion exchange between these layered structures can also be reduced. This makes it possible to extend the battery life of the zinc-vanadium battery 1 by avoiding the problem of power decay after multiple charge-discharge cycles in some embodiments.

[0025] Step S21 is a drying step that includes further freeze-drying or heat-drying the vanadium-based homogeneous mixture obtained in step S20 to obtain a vanadium-based material.

[0026] In some embodiments, the heating and drying in step S21 involves first removing the solvent contained in the vanadium-based homogeneous mixture obtained in step S20, then placing it in an oven and drying it under vacuum and high temperature to obtain a vanadium-based material. The above step of removing the solvent contained in the vanadium-based homogeneous mixture can be carried out by a filtration step and / or a concentration step. The above filtration step can be carried out by, for example, vacuum filtration, gravity filtration, pressure filtration, or centrifugal filtration, but is not limited to these. The above concentration step can be carried out by, for example, cyclotron concentration or reduced-pressure concentration, but is not limited to these. In some embodiments, the above step of drying the vanadium-based material under vacuum and high temperature can be carried out by heating it to about 50-70°C (e.g., about 60°C) and maintaining that temperature overnight. In some embodiments, in step S20, an organic solvent (e.g., N-methyl-2-pyrrolidone (NMP)) is added to the vanadium-based material to improve the vacuum filtration efficiency by substituting NMP for water, and then the process proceeds to step S21, where the material is dried, for example, by the above-described heating and drying method, to obtain the vanadium-based material. In some embodiments, the vanadium-based material obtained by the above-described heating and drying method can be further pulverized as appropriate to further refine the vanadium-based material that has aggregated after drying.

[0027] In some embodiments, freeze-drying in step S21 means first freezing the vanadium-based homogeneous mixture obtained in step S20 into a frozen state before heating and drying, then applying a vacuum and heating to directly sublimate the water molecules in the vanadium-based homogeneous mixture from a solid state. Therefore, in some embodiments, drying by the above freeze-drying method can avoid the aggregation phenomenon of the vanadium-based material after drying and provide a softer dried powder.

[0028] After completing step S21, the obtained vanadium-based material can be measured by XRD using CuKα1 radiation. In the X-ray diffraction pattern of this vanadium-based material, a peak of intensity I8 appears at 2θ = 8° ± 1.0°, and a peak of intensity I8 appears at 2θ = 20° ± 1.0°. 20 A peak appears, and I8 and I 20 The ratio (I8 / I 20 ) is 0 <I8 / I 20 ≤ 1.4, for example 1.1 ≤ I8 / I 20 The condition ≤1.4 is satisfied. In some embodiments, the above XRD measurement allows for early confirmation of whether the vanadium-based material prepared in step S21 can subsequently be used in the manufacture of the zinc-vanadium battery 1, thereby saving manufacturing costs.

[0029] Step S22 is a second homogenization step that includes mixing the vanadium-based material, conductive agent, and binder obtained in step S21 and homogenizing them to obtain a modified material. For example, step S22 involves homogenizing (e.g., stirring) the vanadium-based material, conductive agent, and binder in a weight ratio of 70-95:3-45:3-45 under normal conditions for 1-15 hours to obtain a modified material. The above-mentioned normal conditions may be a process environment with a humidity of 40% or less. In some embodiments, step S22 is carried out at room temperature and atmospheric pressure. In some embodiments, the weights of the vanadium-based material, conductive agent, and binder are 70-95 parts by weight, 3-45 parts by weight, and 3-45 parts by weight, respectively. For example, the weights of the vanadium-based material, conductive agent, and binder are 80 parts by weight, 10 parts by weight, and 10 parts by weight, respectively. Specific embodiments of the vanadium-based material, conductive agent, and binder described above can be found by referring to the above description, so a detailed explanation is omitted here. In some embodiments, the vanadium-based material, conductive agent, and binder from step S22 are homogenized by adding them to an organic solvent (e.g., NMP), which ensures that the vanadium-based material, conductive agent, and binder are sufficiently and uniformly dispersed by the organic solvent, preventing aggregation and particle generation. In some embodiments, the modified material obtained in step S22 must satisfy particle size requirements; for example, the particle size of the modified material must be less than 60 μm.

[0030] Step S23 is a first coating step that includes coating the modified material obtained in step S22 onto the positive electrode 10 (Figure 1) to form a modified layer 12 on the positive electrode 10. For example, the modified material can be coated onto the positive electrode 10 using a frame-type four-sided applicator. In some embodiments, after coating the modified material onto the positive electrode 10, the modified material and the positive electrode 10 can be subjected to a further drying step to complete the modified layer 12. For example, step S23 is completed by drying the modified layer 12 and the positive electrode 10 on the positive electrode 10 at about 80-100°C (e.g., about 100°C) for about 1 hour. Specific embodiments of the positive electrode 10 and modified layer 12 can be found in the above description, so a detailed explanation is omitted here.

[0031] After completing step S23 in Figure 2, the modified layer 12 on the obtained positive electrode 10 can be used as the modified positive electrode structure described above. In some embodiments, the obtained modified positive electrode structure can be further subjected to step 24 according to Figure 2 to obtain a zinc vanadium battery 1.

[0032] Please refer to Figure 2. Step S24 is an assembly step that includes assembling the separator 14 and the negative electrode 16 sequentially on the modified layer 12, and immersing the positive electrode 10, modified layer 12, separator 14 and negative electrode 16 in an aqueous electrolyte 18 (Figure 1) to obtain a zinc vanadium battery 1. For example, after assembling the modified positive electrode structure (including the positive electrode 10 and the modified layer 12), the separator 14 and the negative electrode 16 sequentially, the final zinc vanadium battery 1 can be obtained by sealing it with a hydraulic press in accordance with the specifications for a CR2032 button cell battery. Specific embodiments of the positive electrode 10, modified layer 12, separator 14, negative electrode 16 and aqueous electrolyte 18 can be found in the previously described content, so a detailed explanation is omitted here. In some embodiments, the thickness of the positive electrode 10 is approximately 5 to 50 μm, the thickness of the modified layer 12 is approximately 70 to 90 μm, the thickness of the separator 14 is approximately 30 to 400 μm, and the thickness of the negative electrode 16 is approximately 10 to 50 μm.

[0033] The following shows the X-ray diffraction patterns of the I8 / I vanadium-based materials of the unmodified and modified vanadium-based materials through comparative examples and Examples 1-2. 20 Explain.

[0034] (Comparative example: Unmodified vanadium-based material (I8 / I 20 (Zinc-vanadium batteries including =0) [Selection of materials] (1) Positive electrode: Contains titanium foil and has a thickness of approximately 50 μm. (2) Unmodified layer: Contains vanadium oxide (V2O5), conductive agent (conductive carbon black), binder (PVDF), and organic solvent (NMP), with a thickness of approximately 88 μm. Specifications of the vanadium oxide used in this comparative example: CAS No. 1314-62-1, average particle size 50 μm, purity > 99%. This vanadium oxide has a peak at 2θ = 20° ± 1.0°, but no peak corresponding to 2θ = 8° ± 1.0° (i.e., I8 = 0), indicating I8 / I 20 = 0, (3) Separator: Contains glass fibers and has a thickness of approximately 350 μm. (4) Negative electrode: Contains zinc foil and has a thickness of approximately 50 μm. (5) Aqueous electrolyte: Contains 2M Zn(OTf)2 and water, with weight proportions of 42.28 parts by weight and 57.72 parts by weight, respectively.

[0035] [Manufacturing method] (1) Mix 80 parts by weight of vanadium oxide (V2O5), 10 parts by weight of a conductive agent, and 10 parts by weight of a binder in an organic solvent and homogenize to obtain a vanadium-based material (without obvious aggregated particles and with a particle size of less than 60 μm). (2) The vanadium-based material is applied onto the titanium foil serving as the positive electrode using a frame-type four-sided applicator, and the titanium foil and vanadium-based material are dried at 100°C for 1 hour to obtain a coating layer. (3) After assembling the positive electrode, coating layer, separator and negative electrode, immerse them in an aqueous electrolyte solution. (4) A zinc-vanadium battery was obtained as a comparative example by sealing it with a hydraulic press in accordance with the specifications of a CR2032 button battery.

[0036] (XRD measurement results: vanadium-based material used in the comparative example) Referring to Figure 3A, Figure 3A shows the X-ray diffraction pattern of a comparative example (known to the inventors of this invention) vanadium-based material measured by XRD using CuKα1 rays. As can be seen from the XRD measurement results in Figure 3A, when vanadium oxide (V2O5) is not modified with hydrogen peroxide and water, even if the other materials and processes used are the same as in Examples 1 and 2 of the present invention (details described later), this vanadium-based material does not show a peak corresponding to the position 2θ = 8° ± 1.0° (i.e., I8 = 0), and therefore I8 / I 20 = 0.

[0037] (Example 1: Modified vanadium-based material of several embodiments of the present invention (I8 / I 20 Zinc-vanadium battery containing =1.13) 1) [Selection of materials] (1) Positive electrode: Contains titanium foil and has a thickness of approximately 50 μm. (2) Vanadium-based homogeneous mixture: containing vanadium oxide (V2O5), water, and hydrogen peroxide, in weight proportions of 35 parts by weight, 600 parts by weight, and 10 parts by weight, respectively. Specifications of the vanadium oxide used in this example: CAS No. 1314-62-1, average particle size 50 μm, purity >99%. This vanadium oxide has a peak at 2θ = 20° ± 1.0°, but no peak corresponding to 2θ = 8° ± 1.0° (i.e., I8 = 0), indicating I8 / I 20 = 0, (3) Modified layer 12: Contains vanadium-based material (obtained by drying the above vanadium-based homogeneous mixture), conductive agent (conductive carbon black), binder (PVDF), and organic solvent (NMP), and has a thickness of approximately 88 μm. (4) Separator 14: Contains cellulose and has a thickness of approximately 50 μm. (5) Negative electrode 16: Contains zinc foil and has a thickness of approximately 50 μm. (6) The aqueous electrolyte consisted of 18 parts by weight of Zn(OTf)2 (2M Zn(OTf)2 was used in this example) and water, with weight ratios of 42.28 parts by weight and 57.72 parts by weight, respectively.

[0038] [Manufacturing method] (1) Mix 35 parts by weight of vanadium oxide (V2O5), 600 parts by weight of water, and 60 parts by weight of hydrogen peroxide, and homogenize to obtain a vanadium-based homogeneous mixture. (2) After freezing a vanadium-based homogeneous mixture into a frozen state, a vacuum is applied and it is heated to 40°C and the temperature is maintained for 12 hours or more (in this embodiment, it was maintained for about 12 hours) to obtain a dry vanadium-based powder, and then the vanadium-based material is measured by XRD to obtain the I8 / I X-ray diffraction pattern. 20 Check, (3) Mix 80 parts by weight of vanadium-based material, 10 parts by weight of conductive agent, and 10 parts by weight of binder in an organic solvent and homogenize to obtain a modified material (without obvious aggregated particles and with a particle size of less than 60 μm). (4) The modified material is applied onto the titanium foil serving as the positive electrode using a frame-type four-sided applicator, and the titanium foil and modified material are dried at 100°C for 1 hour to obtain a modified layer 12. (5) After assembling the positive electrode 10, the reformed layer 12, the separator 14, and the negative electrode 16, they are immersed in the aqueous electrolyte 18. (6) By sealing the battery with a hydraulic press in accordance with the specifications for a CR2032 button cell, a zinc vanadium battery 1 as Example 1 was obtained.

[0039] (XRD measurement results: Vanadium-based material used in Example 1) Referring to Figure 3B, Figure 3B shows the X-ray diffraction pattern of the vanadium-based material of Example 1 (several embodiments of the present invention) measured by XRD using CuKα1 rays. As can be seen from the XRD measurement results in Figure 3B, the vanadium-based material used in Example 1 is a vanadium-based material obtained by modifying vanadium oxide (V2O5) with hydrogen peroxide and water, and therefore the peak corresponding to the position 2θ = 20° ± 1.0° (I 20 In addition to the possibility of the following appearing, a peak (I8) also appears at the position 2θ = 8° ± 1.0°, and I8 / I 20 = 1.13 was calculated.

[0040] (Example 2: Modified vanadium-based material of several embodiments of the present invention (I8 / I 20Zinc-vanadium battery containing (=1.35) Selection of materials: Since the materials are the same as in Example 1 described above, please refer to the description of Example 1, and a detailed explanation will be omitted here.

[0041] Manufacturing method: Since it is the same as in Example 1 described above, please refer to the description of Example 1, and a detailed explanation will be omitted here.

[0042] (XRD measurement results: Vanadium-based material used in Example 2) Referring to Figure 3C, Figure 3C shows the X-ray diffraction pattern of the vanadium-based material of Example 2 (another embodiment of the present invention) measured by XRD using CuKα1 rays. As can be seen from the XRD measurement results in Figure 3C, similar to Example 1, the vanadium-based material used in Example 2 is a vanadium-based material obtained by modifying vanadium oxide (V2O5) with hydrogen peroxide and water, and therefore the peak corresponding to the position 2θ = 20° ± 1.0° (I 20 In addition to the possibility of the following appearing, a peak (I8) also appears at the position 2θ = 8° ± 1.0°, and I8 / I 20 = 1.35 was calculated.

[0043] When the XRD measurement results of the above comparative examples and Examples 1-2 are combined, only the X-ray diffraction patterns of Examples 1-2 (vanadium-based materials are vanadium-based materials obtained by modifying vanadium oxide (V2O5) with at least hydrogen peroxide and water) show simultaneous peaks at positions 2θ=8°±1.0° and 2θ=20°±1.0°, and the two resulting peaks are 0 <I8 / I 20 The peak intensity relationship ≤ 1.4 is satisfied, and 1.1 ≤ I8 / I 20 It can be seen that the peak intensity relationship of ≤1.4 is also satisfied.

[0044] The discharge capacity and average lifespan of the batteries in the comparative example and Examples 1 and 2 will be explained below through Experimental Examples 1 and 2.

[0045] (Experimental Example 1: Battery Discharge Capacity) [Test Method] The battery test method used in this experiment was a constant current charge-discharge test. Each battery under test was discharged via a charge-discharge device at a pre-set constant current (usually called current density, which can be set to 100 mA / g or 200 mA / g using the weight of the electrode reactants as a reference value (in this experiment, the current density was set to 200 mA / g)), and the discharge time and total discharge capacity were recorded. Furthermore, dividing the product of this time and total discharge capacity by the weight of the positive electrode yields the capacity per gram of battery in milliampere-hours per gram (mAh / g).

[0046] [Test Results] Referring to Table 1 and Figure 4 below, Figure 4 is a comparison diagram of the discharge capacities of a zinc-vanadium battery containing a vanadium-based material of the comparative example and a zinc-vanadium battery 1 containing a vanadium-based material of Example 2. As can be seen from the battery discharge capacity test results in Table 1 and Figure 4, the average discharge capacities of the batteries in Examples 1 and 2 were approximately 217 mAh / g and 203 mAh / g, respectively. Compared to the average discharge capacity of the comparative example battery (approximately 116 mAh / g), the average discharge capacities of the batteries in Examples 1 and 2 increased by approximately 87.1% and 75.0%, respectively. In other words, since the modified layer 12 of the zinc-vanadium battery 1 in Examples 1 and 2 is a modified vanadium-based material obtained by modifying vanadium oxide (V2O5) with at least hydrogen peroxide and water, the average discharge capacity of the battery was significantly improved. Therefore, in some embodiments, I8 / I 20 is at least 1.13 to 1.35 (i.e., 1.1 ≤ I8 / I) 20 A zinc-vanadium battery 1 containing vanadium-based material of ≤1.4) was able to reliably achieve a significantly improved average discharge capacity.

[0047] [Table 1]

[0048] (Experimental Example 2: Average Battery Life) [Test Method] In this experiment, the battery's operating voltage range was set to 0.2~2.0V via a charge / discharge device (the battery's operating voltage in this experiment was set to 2.0V), and the batteries of the comparative example, Example 1, and Example 2 were continuously charged at least 30 times with a fixed current density of 100mA / g or 200mA / g (the current density in this experiment was set to 200mA / g) to test the average cycle life of the batteries.

[0049] [Test Results] Referring to Table 2 and Figure 5 below, Figure 5 is a comparison chart of the average lifespan of a zinc-vanadium battery containing a vanadium-based material of the comparative example and a zinc-vanadium battery 1 containing a vanadium-based material of Example 2. As can be seen from the average lifespan test results of the batteries in Table 2 and Figure 5, the average lifespan of the batteries in Examples 1 and 2 were approximately 75 cycles and 54 cycles, respectively. Compared to the average lifespan of the comparative example battery (approximately 45 cycles), the average lifespan of the batteries in Examples 1 and 2 increased by approximately 66.7% and 20.0%, respectively. In other words, since the modified layer 12 of the zinc-vanadium battery 1 in Examples 1 and 2 is a modified vanadium-based material obtained by modifying vanadium oxide (V2O5) with at least hydrogen peroxide and water, the average lifespan of the battery was significantly improved. Therefore, in some embodiments, I8 / I 20 is at least 1.13 to 1.35 (i.e., 1.1 ≤ I8 / I) 20 A zinc-vanadium battery 1 containing vanadium-based material ≤1.4) was able to reliably achieve a significantly improved average battery life.

[0050] [Table 2]

[0051] In short, in some embodiments, the modified cathode structure includes a vanadium-based material obtained by modifying vanadium oxide with hydrogen peroxide and water. Compared to conventional zinc-vanadium batteries that do not include this modified vanadium-based material, in some embodiments, zinc-vanadium batteries including this modified cathode structure (i.e., including the modified vanadium-based material) can have significantly improved average discharge capacity and average battery life. Since the above modified cathode structure is used as the positive electrode of a zinc-vanadium battery, the solutions provided in some embodiments differ from currently common methods for preparing aqueous electrolytes, yet they were still able to produce the effect of significantly improving the average discharge capacity and average battery life.

[0052] While examples have been disclosed in this invention as described above, these are by no means limiting to the present invention. Anyone familiar with the art may make various modifications and embellishments without departing from the spirit and scope of the invention. Therefore, the scope of protection of this invention shall be based on the claims attached herein. [Explanation of Symbols]

[0053] 10 positive electrode 1. Zinc-vanadium battery 12 Modified layer 14 Separator 16 negative electrode 18 Aqueous electrolyte 2. Method for preparing a zinc-vanadium battery containing a modified cathode structure. S20~S24 process

Claims

1. A positive electrode containing titanium, Located on the positive electrode, Vanadium-based material 70 to 95 parts by weight, 3 to 45 parts by weight of conductive agent, and Binder 3-45 weight units A modified cathode structure comprising a modified layer containing, In the X-ray diffraction pattern of the vanadium-based material measured by an X-ray diffractometer (XRD) using CuKα1 rays, the peak intensity at 2θ = 8° ± 1.0° is I ８ The peak intensity at 2θ = 20° ± 1.0° is I ２０ In that case, the above I ８ and the aforementioned I ２０ Ratio to (I ８ / I ２０ ) is 0 < I ８ / I ２０ A modified cathode structure that satisfies ≤ 1.

4.

2. The above-mentioned I ８ and the above-mentioned I ２０ The ratio (I ８ / I ２０ ) satisfies 1.1 ≤ I ８ / I ２０ ≤ 1.

4. The modified positive electrode structure according to claim 1

3. The modified cathode structure according to claim 1, wherein the conductive agent contains at least one of conductive carbon black and carbon nanotubes.

4. The modified cathode structure according to claim 1, wherein the binder contains at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), carboxymethylcellulose (CMC), styrene-butadiene rubber (SBR), and polyimide.

5. The modified positive electrode structure according to claim 1, wherein the thickness of the positive electrode is 10 to 50 μm and the thickness of the modified layer is 50 to 90 μm.

6. A first homogenization step includes mixing vanadium oxide, water, and hydrogen peroxide and homogenizing them to obtain a vanadium-based homogeneous mixture, A drying step comprising freeze-drying or heat-drying the aforementioned vanadium-based homogeneous mixture to obtain the vanadium-based material, A second homogenization step includes mixing the vanadium-based material, the conductive agent, and the binder to homogenize them and obtain a modified material, A coating step including applying the modifying material onto the positive electrode to form the modified layer on the positive electrode. A method for preparing a modified cathode structure according to any one of claims 1 to 5, including the following:

7. The first homogenization step includes homogenizing the vanadium oxide, water, and hydrogen peroxide in a weight ratio of 7:120:2 to 12 at room temperature and atmospheric pressure to obtain the vanadium-based homogeneous mixture. The method according to claim 6, wherein the second homogenization step includes homogenizing the vanadium-based material, the conductive agent, and the binder in a weight ratio of 70-95:3-45:3-45 under normal temperature and pressure to obtain the modified material.

8. A positive electrode containing titanium, Located on the positive electrode, Vanadium-based material 70 to 95 parts by weight, 3 to 45 parts by weight of conductive agent, and Binder 3-45 weight units Modified layer containing A separator located on the aforementioned modified layer, A negative electrode containing zinc and located on the separator, An aqueous electrolyte containing the positive electrode, the reforming layer, the separator, and the negative electrode inside, A zinc vanadium battery containing, In the X-ray diffraction pattern of the vanadium-based material measured by an X-ray diffractometer (XRD) using CuKα1 rays, the peak intensity at 2θ = 8° ± 1.0° is I ８ The peak intensity at 2θ = 20° ± 1.0° is I ２０ In that case, the above I ８ and the aforementioned I ２０ Ratio to (I ８ / I ２０ ) is 0 < I ８ / I ２０ A zinc-vanadium battery that satisfies ≤ 1.

4.

9. The above I ８ and the aforementioned I ２０ Ratio to (I ８ / I ２０ ) but 1.1 ≤ I ８ / I ２０ A zinc-vanadium battery according to claim 8, satisfying ≤ 1.

4.

10. The zinc vanadium battery according to claim 8, wherein the conductive agent contains at least one of conductive carbon black and carbon nanotubes.

11. The zinc vanadium battery according to claim 8, wherein the binder contains at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), carboxymethylcellulose (CMC), styrene-butadiene rubber (SBR), and polyimide.

12. The zinc vanadium battery according to claim 8, wherein the separator contains cellulose or glass fiber.

13. The aforementioned aqueous electrolyte is zinc triflate (Zn(OTf)) ２ The zinc vanadium battery according to claim 8, which is an aqueous solution containing ).

14. The aforementioned Zn(OTf) ２ The aqueous solution contains Zn(OTf) ２ and water, and the Zn(OTf) ２ The zinc vanadium battery according to claim 13, wherein the weight ratio of the zinc vanadium to water is 1:1 to 3:

7.

15. The zinc vanadium battery according to claim 8, wherein the thickness of the positive electrode is 10 to 50 μm, the thickness of the modified layer is 50 to 90 μm, the thickness of the separator is 30 to 400 μm, and the thickness of the negative electrode is 10 to 50 μm.

16. A first homogenization step includes mixing vanadium oxide, water, and hydrogen peroxide and homogenizing them to obtain a vanadium-based homogeneous mixture, A drying step comprising freeze-drying or heat-drying the aforementioned vanadium-based homogeneous mixture to obtain the vanadium-based material, A second homogenization step includes mixing the vanadium-based material, the conductive agent, and the binder to homogenize them and obtain a modified material, A coating step including applying the modifying material onto the positive electrode to form the modified layer on the positive electrode. A method for preparing a zinc vanadium battery according to any one of claims 8 to 15, comprising an assembly step of assembling the separator and the negative electrode in order on the modified layer, and immersing the positive electrode, the modified layer, the separator and the negative electrode in the aqueous electrolyte to obtain the zinc vanadium battery.

17. The first homogenization step includes homogenizing the vanadium oxide, water, and hydrogen peroxide in a weight ratio of 7:120:2 to 12 at room temperature and atmospheric pressure to obtain the vanadium-based homogeneous mixture. The method according to claim 16, wherein the second homogenization step includes homogenizing the vanadium-based material, the conductive agent, and the binder in a weight ratio of 70-95:3-45:3-45 under normal temperature and pressure to obtain the modified material.

Images