Corrosion-resistant positive plate, preparation method thereof and aqueous zinc ion battery

Abstract

The invention relates to the technical field of batteries, in particular to a corrosion-resistant positive plate, a preparation method of the corrosion-resistant positive plate and an aqueous zinc ion battery. The corrosion-resistant positive plate comprises a positive plate and adhesive layers arranged on four side surfaces of the positive plate in the thickness direction, the positive plate comprises a positive current collector and an active material layer arranged on the surface of the positive current collector; and the positive current collector is a carbon-coated aluminum foil current collector. By adopting the process, the quality of the positive plate is reduced by about 20%. Meanwhile, the four side surfaces in the thickness direction of the positive plate prepared as the current collector are protected by adopting the adhesive layers, so that the contact between the electrolyte and the edge of the aluminum foil current collector can be effectively blocked, and the corrosion of the electrolyte to the current collector is inhibited from the source; and after the battery is subjected to charge-discharge circulation, the edge of the positive plate has no corrosion trace, and long-term stable operation of the aluminum current collector under aqueous electrolyte is ensured.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a corrosion-resistant positive electrode sheet, its preparation method, and an aqueous zinc-ion battery. Background Technology

[0002] Aqueous zinc-ion batteries typically use zinc metal as the negative electrode and a transition metal layered oxide (such as vanadium-based or manganese-based layered oxides) as the positive electrode. The electrolyte is based on an aqueous solution of zinc salts, supplemented with functional additives to optimize battery performance. As a novel electrochemical energy storage device, aqueous zinc-ion batteries have significant advantages such as low raw material costs, excellent safety performance, and good environmental compatibility, showing broad application prospects in large-scale energy storage and distributed power generation. Despite these advantages, the commercial application of aqueous zinc-ion batteries is still in its early stages, primarily due to challenges in the compatibility between the positive electrode current collector and the electrolyte. The current collector, as crucial for efficient electron transport, directly affects the battery's cycle stability, energy density, and manufacturing cost in aqueous electrolyte systems due to its corrosion resistance, density, and material price. In existing technologies, the positive electrode current collectors of aqueous zinc-ion batteries typically use inert metals such as stainless steel and titanium. Although these materials exhibit good corrosion resistance in electrolytes, inert metal current collectors suffer from several insurmountable technical drawbacks, severely hindering the industrialization of aqueous zinc-ion batteries: First, the material cost is high; the raw material price of inert metal foils such as stainless steel and titanium is much higher than that of aluminum foil, significantly increasing the unit production cost of batteries. Second, the density is high; compared to aluminum foil, the high density of stainless steel and titanium significantly affects the energy density of batteries. Third, there is poor compatibility with existing production processes; existing processes such as positive electrode coating, rolling, cutting, and welding are all designed based on the characteristics of aluminum foil. To adapt to inert metal current collectors, production process parameters need to be re-verified, further increasing initial investment costs and production complexity. Therefore, promoting the technological iteration of positive electrode current collectors is key to achieving large-scale production of aqueous zinc-ion batteries.

[0003] Aluminum foil is considered an ideal candidate material for positive electrode current collectors due to its excellent conductivity, ductility, and low density, as well as its significant cost advantage. However, there are currently few practical cases of its application in aqueous zinc-ion battery positive electrode current collectors. The core reason is that the loose passivation layer on the surface of the aluminum current collector is difficult to form an effective protection for the aluminum current collector in an aqueous electrolyte, making the aluminum current collector highly susceptible to corrosion by the aqueous electrolyte. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings and defects of the prior art and to provide a corrosion-resistant positive electrode sheet, its preparation method, and an aqueous zinc-ion battery.

[0005] To achieve the above objectives, this application adopts the following solution: A corrosion-resistant positive electrode includes a positive electrode and adhesive layers disposed on four sides in the thickness direction of the positive electrode; the positive electrode includes a positive current collector and an active material layer disposed on the surface of the positive current collector; the positive current collector is a carbon-coated aluminum foil current collector.

[0006] The adhesive layer covers the four sides of the positive electrode sheet in the thickness direction and extends to the surfaces adjacent to the four sides.

[0007] The width of the adhesive line forming the adhesive layer is 2-8 times the thickness of the positive electrode sheet; preferably, when the thickness of the positive electrode sheet is 0.12 mm, the width of the adhesive line forming the adhesive layer is 0.3-0.5 mm.

[0008] The thickness of the adhesive layer is 0.5-1 times the thickness of the positive electrode sheet; preferably, when the thickness of the positive electrode sheet is 0.12 mm, the thickness of the adhesive layer is 0.08-0.12 mm.

[0009] The adhesive layer is made of UV-curable acrylic adhesive or epoxy resin thermosetting adhesive; preferably, it is UV-curable acrylic adhesive.

[0010] The active material layer includes a positive electrode active material, a positive electrode conductive agent, and a positive electrode binder. Preferably, the positive electrode active material is at least one of V2O5 or Mn2O5. The positive electrode conductive agent is at least one of activated carbon, acetylene black, graphite, carbon nanotubes, graphene, and carbon fiber. Preferably, the positive electrode conductive agent is a mixture of conductive carbon black and carbon nanotubes. More preferably, the mass ratio of conductive carbon black to carbon nanotubes is 2:1. The positive electrode binder is polyvinylidene fluoride (PVDF). The mass ratio of the positive electrode active material, the positive electrode conductive agent, and the positive electrode binder is (91-95):(1-5):(2-6); preferably 93:3:4.

[0011] The present invention also includes a method for preparing the corrosion-resistant positive electrode sheet, comprising the following steps: placing the positive electrode sheet on the sample stage of the dispensing equipment, and using a dispensing machine to apply adhesive to the four sides of the positive electrode sheet in the width direction to obtain the corrosion-resistant positive electrode sheet; Preferably, the parameters of the dispensing machine are: nozzle temperature from room temperature to 80°C; pulse time 0.5-10ms; cycle time 10-50ms; and coating line speed 1-10mm / s.

[0012] When the adhesive layer is a UV-curable acrylic adhesive, the positive electrode sheet after adhesive coating is cured using a UV light source; preferably, the light intensity of the light source is 20-50 mW / cm². 2Wavelength: 365-435nm; Curing time: 5-30s; When the adhesive layer is an epoxy resin thermosetting adhesive, the positive electrode sheet that has been coated and protected is then thermosetting.

[0013] The present invention also includes an aqueous zinc-ion battery, comprising the aforementioned corrosion-resistant positive electrode, negative electrode, separator, and electrolyte; preferably, the negative electrode is a copper substrate plated with zinc, preferably, using copper foil as the substrate, ZnSO4·7H2O as the main salt of the electroplating solution, and a zinc plate as the anode, to prepare a zinc plating layer by electroplating, and then washing and drying to obtain a copper substrate zinc-plated negative electrode.

[0014] The present invention also includes an aqueous zinc-ion battery, wherein the electrolyte comprises a zinc salt and water; the zinc salt comprises at least one of zinc sulfate, zinc chloride, zinc nitrate, zinc bis(trifluoromethanesulfonyl)imide, or zinc fluoroborate.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention uses aluminum foil as the positive electrode current collector in an aqueous zinc-ion battery. The density of the aluminum foil is 2.7 g / cm³. 3 The concentration is far lower than that of titanium foil (4.5g / cm). 3 ), stainless steel (7.9g / cm) 3 This reduces the weight of the positive electrode sheet by approximately 20% and increases the battery energy density by 10%-15%. Furthermore, using aluminum foil as the positive electrode current collector can reduce the current collector cost by 20%-30%. Protecting the four sides of the positive electrode sheet using aluminum foil as the current collector with adhesive layers along its thickness direction effectively prevents contact between the electrolyte and the edges of the aluminum foil current collector, fundamentally inhibiting electrolyte corrosion of the current collector. After charge-discharge cycles, no corrosion marks are found on the edges of the positive electrode sheet, ensuring long-term stable operation of the aluminum current collector in aqueous electrolytes. The method in this application preferably uses UV-curable acrylic adhesive as the adhesive layer material. The second-level curing process is compatible with existing battery assembly production cycles, and the produced electrode sheets are compatible with existing assembly lines, avoiding equipment modification investment and fully meeting the cost control requirements for large-scale industrialization. Attached Figure Description

[0016] Figure 1 This is an overall schematic diagram of the positive electrode sheet of the present invention; Figure 2 This is a schematic diagram of the preparation process of the aqueous zinc-ion battery of the present invention. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0018] See appendix Figure 1As shown, a corrosion-resistant positive electrode includes a positive electrode 2 and adhesive layers 1 disposed on four sides of the positive electrode in the thickness direction. The positive electrode includes a positive current collector and an active material layer disposed on the surface of the positive current collector. The positive current collector is a carbon-coated aluminum foil current collector. The adhesive layers cover the four sides of the positive electrode in the thickness direction and extend to the adjacent surfaces of the four sides. The width of the adhesive lines forming the adhesive layers is 2-8 times the thickness of the positive electrode; in this application, the thickness of the positive electrode is taken as 0.12 mm; the width of the adhesive lines forming the adhesive layers is 0.3-0.5 mm. The thickness of the adhesive layers is 0.08-0.12 mm.

[0019] Example 1: A method for preparing a corrosion-resistant positive electrode sheet, comprising the following steps: 1. Preparation of positive electrode sheet: The positive electrode active material (V2O5), conductive agent (conductive carbon black, carbon nanotubes 2:1) and binder (PVDF) are mixed and homogenized in a ratio of 93:3:4, coated on the surface of a 16μm carbon-coated aluminum foil (including a 4μm carbon coating layer) current collector, dried, and the electrode sheet is cut to obtain a positive electrode sheet with a thickness of 0.12mm. 2. Preparation of the corrosion-resistant coating: The positive electrode sheet is placed on the sample stage of the dispensing equipment. UV-curable acrylic adhesive (Tianci High-Adhesion TCS-1130UV-Ⅰ) is used to dispense the adhesive onto the four sides of the positive electrode sheet along its thickness. The parameters of the high-precision dispensing machine are adjusted, including a pulse time of 1.5ms, a cycle time of 20ms, a needle stroke of 90%, and a nozzle temperature of 60℃. The pre-programmed coating program is started, and the positive electrode sheet, now coated on all four sides, is cured using a UV light source with a light intensity of 20mW / cm². 2 The ultraviolet light wavelength was 365 nm; the curing time was 10 s. The resulting adhesive line width was 0.5 mm and the thickness was 120 μm. The positive electrode prepared in Example 1 had neat edges and no cracking.

[0020] 3. Preparation of negative electrode: Using 10μm copper foil as substrate, ZnSO4·7H2O as main salt of electroplating solution, zinc plate as anode, zinc plating layer is prepared by electroplating, and after washing and drying, a copper substrate zinc-plated negative electrode with a thickness of 50μm is obtained. 4. Preparation of aqueous zinc-ion batteries ( Figure 2 (Flowchart shown): Aqueous zinc-ion battery cells are prepared by assembling positive electrode, negative electrode, and separator, followed by liquid injection and encapsulation to finally obtain an aqueous zinc-ion battery.

[0021] Example 2: The difference between Example 2 and Example 1 is that the width of the adhesive line obtained is 0.3 mm and the thickness is 120 μm. The positive electrode of the aqueous zinc-ion battery prepared in Example 2 has a neat edge and no cracking of the electrode sheet.

[0022] Example 3 The difference between Example 3 and Example 1 is that the width of the adhesive line obtained is 0.5 mm and the thickness is 80 μm. The positive electrode of the aqueous zinc-ion battery prepared in Example 3 has a neat edge and no cracking of the electrode sheet.

[0023] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that no glue is applied to the edges of the positive electrode sheet. In addition, the rest of the part is prepared by the same process. After the cell is assembled, the liquid injection, encapsulation and formation processes are carried out directly.

[0024] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that the edges of the positive electrode are protected by PE tape with a tape width of 1 mm and a tape thickness of 16 μm.

[0025] The positive electrode samples obtained in Examples 1-3 of this invention were immersed in a 3 mol / L ZnSO4 electrolyte and left at room temperature for 7 days. The adhesive layer showed no swelling, no peeling, and no significant change in morphology, indicating that the cured adhesive layer can effectively block the contact between the electrolyte and the edge of the aluminum current collector, thus inhibiting the corrosion of the current collector by the electrolyte from the source. After the battery underwent charge and discharge cycles, there were no corrosion marks on the edge of the current collector, ensuring the long-term stable operation of the aluminum current collector under aqueous electrolyte.

[0026] Meanwhile, the batteries obtained in Examples 1-3 were tested, and the results are shown in Table 1.

[0027] Table 1

[0028] In summary, the four sides of the positive electrode sheet along its thickness are protected with adhesive layers, effectively preventing contact between the electrolyte and the edge of the aluminum foil current collector, thus inhibiting electrolyte corrosion of the current collector at its source. After charge-discharge cycles, no corrosion marks are found on the edges of the positive electrode sheet, ensuring the long-term stable operation of the aluminum current collector in aqueous electrolyte conditions. The method in this application preferentially uses UV-curable acrylic adhesive as the adhesive layer material. The second-level curing process is compatible with existing battery assembly production cycles, and the produced electrode sheets are compatible with existing assembly lines, avoiding equipment modification investment and fully meeting the cost control requirements for large-scale industrialization.

[0029] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of the equivalents of the claims be included within the invention.

[0030] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A corrosion-resistant positive electrode, characterized in that, It includes a positive electrode sheet and adhesive layers disposed on four sides in the thickness direction of the positive electrode sheet; the positive electrode sheet includes a positive current collector and an active material layer disposed on the surface of the positive current collector; the positive current collector is a carbon-coated aluminum foil current collector.

2. The corrosion-resistant positive electrode sheet according to claim 1, characterized in that, The adhesive layer covers the four sides of the positive electrode sheet in the thickness direction and extends to the surfaces adjacent to the four sides.

3. The corrosion-resistant positive electrode sheet according to claim 1, characterized in that, The width of the adhesive line forming the adhesive layer is 2-8 times the thickness of the positive electrode sheet; preferably, the thickness of the positive electrode sheet is 0.12 mm; and the width of the adhesive line forming the adhesive layer is 0.3-0.5 mm.

4. The corrosion-resistant positive electrode sheet according to claim 1, characterized in that, The thickness of the adhesive layer is 0.08-0.12 mm.

5. The corrosion-resistant positive electrode sheet according to claim 1, characterized in that, The adhesive layer is made of UV-curable acrylic adhesive or epoxy resin thermosetting adhesive; preferably, it is UV-curable acrylic adhesive.

6. The corrosion-resistant positive electrode sheet according to claim 1, characterized in that, The active material layer includes a positive electrode active material, a positive electrode conductive agent, and a positive electrode binder. Preferably, the positive electrode active material is at least one of V2O5 or Mn2O5. The positive electrode conductive agent is at least one of activated carbon, acetylene black, graphite, carbon nanotubes, graphene, and carbon fiber. Preferably, the positive electrode conductive agent is a mixture of conductive carbon black and carbon nanotubes. More preferably, the mass ratio of conductive carbon black to carbon nanotubes is 2:

1. The positive electrode binder is polyvinylidene fluoride (PVDF). The mass ratio of the positive electrode active material, the positive electrode conductive agent, and the positive electrode binder is (91-95):(1-5):(2-6); preferably 93:3:

4.

7. A method for preparing a corrosion-resistant positive electrode sheet according to any one of claims 1-6, characterized in that, The process includes the following steps: placing the positive electrode sheet on the sample stage of the dispensing equipment, and using the dispensing machine to apply adhesive to the four sides of the positive electrode sheet in the thickness direction to obtain a corrosion-resistant positive electrode sheet; Preferably, the parameters of the dispensing machine are: nozzle temperature from room temperature to 80°C; pulse time 0.5-10ms; cycle time 10-50ms; and coating line speed 1-10mm / s.

8. The method for preparing the corrosion-resistant positive electrode sheet according to claim 7, characterized in that, When the adhesive layer is a UV-curable acrylic adhesive, the positive electrode sheet after adhesive coating is cured using a UV light source; preferably, the light intensity of the light source is 20-50 mW / cm². 2 Wavelength: 365-435nm; Curing time: 5-30s; When the adhesive layer is an epoxy resin thermosetting adhesive, the positive electrode sheet that has been coated and protected is then thermosetting.

9. An aqueous zinc-ion battery, characterized in that, The invention includes the corrosion-resistant positive electrode, negative electrode, separator, and electrolyte as described in any one of claims 1-6; preferably, the negative electrode is a copper substrate plated with zinc, preferably, copper foil is used as the substrate, ZnSO4·7H2O is used as the main salt of the electroplating solution, zinc plate is used as the anode, a zinc plating layer is prepared by electroplating, and the copper substrate zinc-plated negative electrode is obtained by washing and drying.

10. An aqueous zinc-ion battery according to claim 9, characterized in that, The electrolyte comprises a zinc salt and water; the zinc salt comprises at least one of zinc sulfate, zinc chloride, zinc nitrate, zinc bis(trifluoromethanesulfonyl)imide, or zinc fluoroborate.

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