Negative current collector of zinc-nickel battery and application of negative current collector

Abstract

The invention discloses a zinc-nickel battery negative electrode current collector and application thereof, and belongs to the technical field of energy storage. The invention provides a zinc-nickel battery negative electrode current collector. The zinc-nickel battery negative electrode current collector comprises a current collection region and a current distribution region, the current collection area and the current distribution area are independently rectangular; one short side of the current collection area is flush with one long side of the current distribution area; one long side of the current collection area is attached to one short side of the current distribution area to form an electronic path; the long side of the current collection area is larger than the short side of the current distribution area. The current distribution area is provided with a through hole. Compared with a structure without through holes in a current distribution area, the zinc-nickel battery negative electrode current collector provided by the invention has the advantages that the mass of the negative electrode current collector is reduced, and the effects of uniformly distributing charging and discharging current and slowing down the deformation of negative electrode zinc can be achieved. When the zinc-nickel battery negative electrode current collector provided by the invention is applied to the preparation process of a cylindrical zinc-nickel battery, the reliability of the battery can be effectively improved.

Description

Technical Field

[0001] This application belongs to the technical field of energy storage, and particularly relates to a negative current collector for a zinc-nickel battery and its application. Background Art

[0002] Aqueous zinc-nickel secondary batteries have broad application prospects due to their high safety, high working voltage, high energy density, high power density, wide applicable temperature range, etc. However, the short cycle life of zinc-nickel batteries has become the main obstacle to their rapid development.

[0003] During the charge and discharge process of an aqueous zinc-nickel battery, a metal zinc deposition / dissolution reaction occurs at the negative electrode. After multiple battery cycles, uneven deposition of metal zinc is likely to occur at the negative electrode, leading to the aggregation and dendrite growth of metal zinc, causing a significant change in the macroscopic morphology of the negative electrode, and ultimately resulting in battery failure. When using a zinc foil in the preparation process of the negative electrode, it can not only provide zinc for the battery reaction but also carry active substances and other additive materials. However, the negative electrode zinc is prone to react in an alkaline electrolyte, affecting electron conduction and directly affecting the performance of the battery. Summary of the Invention

[0004] To solve the above technical problems, this application provides a negative current collector for a zinc-nickel battery and its application, which can effectively conduct electrons, prevent deformation of the negative electrode, and effectively improve the reliability of the battery.

[0005] To achieve the above invention objective, this application provides the following technical solutions:

[0006] On the one hand, this application provides a negative current collector for a zinc-nickel battery, including a current collection area and a current distribution area;

[0007] The current collection area and the current distribution area are independently rectangular;

[0008] One short side of the current collection area is flush with one long side of the current distribution area;

[0009] One long side of the current collection area is attached to one short side of the current distribution area to form an electron path;

[0010] The long side of the current collection area is longer than the short side of the current distribution area;

[0011] The current distribution area is provided with through holes.

[0012] Optionally, there is an overlapping part between the projected areas of the current collection area and the current distribution area;

[0013] The overlapping part is rectangular;

[0014] The long side of the overlapping part is equal to the length of the short side of the current distribution area;

[0015] The short side of the overlapping part is equal to the short side length of the current collection area.

[0016] Optionally, the thickness of the current collection area is 20 - 200 μm.

[0017] Preferably, the thickness of the current collection area is 80 - 150 μm.

[0018] Optionally, the thickness of the current collection area is independently selected from any value of 20 μm, 50 μm, 100 μm, 150 μm, 200 μm or the range value between any two of them.

[0019] Optionally, the thickness of the current distribution area is 6 - 20 μm.

[0020] Preferably, the thickness of the current distribution area is 8 - 20 μm.

[0021] Optionally, the thickness of the current distribution area is independently selected from any value of 6 μm, 8 μm, 10 μm, 12 μm, 14 μm, 16 μm, 18 μm, 20 μm or the range value between any two of them.

[0022] Optionally, the short side length of the current collection area is 1 - 4 mm.

[0023] Preferably, the short side length of the current collection area is 2 - 3 mm.

[0024] Optionally, the short side length of the current collection area is independently selected from any value of 1 mm, 2 mm, 3 mm, 4 mm or the range value between any two of them.

[0025] Optionally, the materials of the current collection area and the current distribution area independently include at least one of copper, brass, copper tin, and copper indium alloy.

[0026] Optionally, the shape of the through hole includes one of a circle, a quadrilateral, a triangle, and a special-shaped through hole.

[0027] The above-mentioned special-shaped through hole refers to any through hole with a shape other than a circle, a quadrilateral, and a triangle.

[0028] Optionally, the distance between two adjacent through holes is 1 - 15 mm.

[0029] Preferably, the distance between two adjacent through holes is 3 - 10 mm.

[0030] Optionally, the distance between two adjacent through holes is independently selected from any value of 1 mm, 3 mm, 5 mm, 7 mm, 9 mm, 11 mm, 13 mm, 15 mm or the range value between any two of them.

[0031] Optionally, the total area of the through holes accounts for 10% to 50% of the area of the current distribution region.

[0032] Preferably, the total area of the through holes accounts for 20% to 40% of the area of the current distribution region.

[0033] Optionally, the total area of the through holes is independently selected from any value of 10%, 20%, 30%, 40%, 50% of the area of the current distribution region or a range value between any two of them.

[0034] In a second aspect, the present application provides the use of the negative electrode current collector of the above zinc-nickel battery in the preparation of a cylindrical zinc-nickel battery.

[0035] Optionally, the negative electrode current collector of the zinc-nickel battery is attached to the negative electrode in the cylindrical zinc-nickel battery.

[0036] In the present application, the cylindrical zinc-nickel battery includes the above negative electrode current collector of the zinc-nickel battery, and further includes a nickel positive electrode, a zinc negative electrode, a separator, an alkaline electrolyte, a cylindrical battery case, and a battery case upper cover; the positive electrode active material is coated on both sides of the nickel positive electrode, and the negative electrode active material paste is coated on one side of the zinc foil negative electrode; the side of the zinc foil negative electrode with the active material is attached to the separator; after the rectangular negative electrode and the rectangular separator are folded face to face along the perpendicular line of the long side of the active material surface, the other side of the separator is attached to both sides of the nickel positive electrode; the negative electrode current collector is closely attached to one side of the folded negative electrode without the coated active material, and after winding the positive electrode, the negative electrode, and the separator together into a cylindrical battery core at the folding line, it is placed inside the cylinder of the cylindrical battery case.

[0037] Optionally, the long side of the rectangular current collection region without the current distribution region coincides with the negative electrode folding line.

[0038] Optionally, the area of the rectangular outer contour of the current distribution region of the negative electrode current collector accounts for 80% to 100% of the area from the short side of the attached negative electrode to the folding line.

[0039] Optionally, the short side of the rectangular current distribution region is 0 to 5 mm shorter than the short side of the zinc negative electrode.

[0040] Preferably, the short side of the rectangular current distribution region is 0 to 3 mm shorter than the short side of the zinc negative electrode.

[0041] Compared with the prior art, the present application includes the following beneficial effects:

[0042] (1) The negative electrode current collector of the zinc-nickel battery provided by the present application reduces the mass of the negative electrode current collector compared with the structure without through holes in the current distribution region.

[0043] (2) Applying the negative electrode current collector of the zinc-nickel battery provided in this application to the preparation process of cylindrical zinc-nickel batteries can effectively improve the reliability of the batteries; compared with directly welding the current collector to the zinc foil, in this application, the negative electrode current collector is closely attached to the negative electrode, avoiding the occurrence of the phenomenon that the current collector directly welded to the zinc foil falls off, and extending the service life of the battery.

[0044] (3) This current collector can play a role in evenly distributing the charge and discharge current, alleviating the uneven deposition of zinc caused by the serious corrosion of the zinc foil current collector. Description of the Drawings

[0045] In order to more clearly illustrate the technical solutions of the embodiments of this application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0046] Figure 1 Schematic diagram of the negative electrode current collector of the zinc-nickel battery in Embodiment 1 of this application (Note: 1 represents the current collection area; 2 represents the current distribution area; 3 represents the through hole);

[0047] Figure 2 Performance test results of the cylindrical zinc-nickel battery in Embodiment 1 of this application. Detailed Embodiments

[0048] The following combines specific embodiments to further elaborate on this application. The following descriptions are only several embodiments of this application and do not impose any form of limitation on this application. Although this application is disclosed with preferred embodiments, it is not used to limit this application. Any person skilled in the relevant art, without departing from the scope of the technical solutions of this application, making some changes or modifications using the technical content disclosed above is equivalent to equivalent implementation cases and all belong to the scope of the technical solutions.

[0049] Unless otherwise specified, the raw materials in the embodiments of this application are purchased through commercial channels and used directly without any special treatment.

[0050] Unless otherwise specified, the analysis methods in the embodiments adopt the conventional settings and conventional analysis methods of instruments or equipment.

[0051] Embodiment 1

[0052] The negative electrode current collector used in this embodiment is composed of a rectangular current collection area and a rectangular current distribution area. The current distribution area is provided with rectangular through-holes; one short side of the rectangular current collection area is flush with one long side of the rectangular current distribution area; the projected areas of the current collection area and the current distribution area have an overlapping part, and the overlapping part is still rectangular. The long side of the overlapping part is equal to the short side length of the current distribution area, and the short side of the overlapping part is equal to the short side length of the current collection area. Moreover, the long side of the rectangular current collection area is attached to the short side of the current distribution area; the current collection area and the current distribution area are welded by ultrasonic welding to form an electronic path; the length of the rectangular through-holes in the current distribution area along the short side of the current distribution area is 5 mm, and the length along the long side of the current distribution area is 10 mm. The distance between two adjacent through-holes is 5 mm both along the long side and the short side directions of the current distribution area; the total area of the through-holes accounts for ~27.5% of the area of the current distribution area; the short side length of the rectangular current distribution area is 55 mm, the long side is 165 mm, and the material is a copper foil with a thickness of 8 μm; the short side length of the rectangular current collection area is 3 mm, the long side is 80 mm, and the material is a copper material with a thickness of 100 μm.

[0053] The above negative electrode current collector of the present application is applied to a cylindrical 18650 zinc-nickel battery. The battery further includes a nickel positive electrode, a zinc negative electrode, a separator, an alkaline electrolyte (6M potassium hydroxide), a cylindrical battery case, and a battery case cover; the positive electrode active material nickel hydroxide is coated on both sides of nickel foam, and the negative electrode active material zinc oxide and zinc powder (mass ratio 5:3) slurry is coated on one side of a 50-μm-thick zinc foil; the length of the negative electrode zinc foil is 34 cm and the width is 5.5 cm; the side of the negative electrode zinc foil with the active material is attached to the separator; after the rectangular negative electrode and the rectangular separator are folded face-to-face along the perpendicular line of the long side with the active material facing each other, the other side of the separator is attached to both sides of the positive electrode; the negative electrode current collector is closely attached to one side of the folded negative electrode without the coated active material; after winding it together with the positive electrode, the negative electrode, and the separator at the folding line to form a cylindrical battery core, it is placed inside the cylinder of the cylindrical battery case; the long side of the rectangular current collection area without the current distribution area coincides with the negative electrode folding line.

[0054] The positive electrode active material is nickel hydroxide (92%), and also includes cobalt oxide (2%), carbon nanotubes (2%), and a binder (4%). The negative electrode active material is zinc oxide and zinc powder (accounting for 88% in total), and also includes carbon nanotubes (5%), indium hydroxide (2%), and a binder (5%).

[0055] This cylindrical battery is charged and discharged in a constant current of 0.2 A. The discharge cut-off voltage is 1.2 V, the Coulomb efficiency is greater than 95%, the energy efficiency is greater than 90%, the discharge capacity is greater than 1.2 Ah, and it can be cycled more than 40 times.

[0056] Example 2

[0057] The negative electrode current collector used in this embodiment is composed of a rectangular current collection area and a rectangular current distribution area. The current distribution area is provided with circular through holes; one short side of the rectangular current collection area is flush with one long side of the rectangular current distribution area; the projection areas of the current collection area and the current distribution area have an overlapping part, and the overlapping part is still rectangular. The long side of the overlapping part is equal to the short side length of the current distribution area, and the short side of the overlapping part is equal to the short side length of the current collection area. Moreover, the long side of the rectangular current collection area is attached to the short side of the current distribution area; the current collection area and the current distribution area are welded by ultrasonic welding to form an electronic path; the circular through holes in the current distribution area have a through hole diameter of 6 mm; the center-to-center distance between the through holes is 10 mm along the long side direction of the current distribution area and 10 mm along the short side direction; the total area of the through holes accounts for ~23.4% of the area of the current distribution area; the short side length of the rectangular current distribution area is 55 mm, the long side is 165 mm, and the material is a copper foil with a thickness of 8 μm; the short side length of the rectangular current collection area is 3 mm, the long side is 80 mm, and the material is a copper material with a thickness of 100 μm.

[0058] The above negative electrode current collector of the present application is applied to a cylindrical 18650 zinc-nickel battery. The battery further includes a nickel positive electrode, a zinc negative electrode, a separator, an alkaline electrolyte (6M potassium hydroxide), a cylindrical battery case, and a battery case upper cover; the positive electrode active material nickel hydroxide is double-sidedly coated on nickel foam, and the negative electrode active material zinc oxide and zinc powder (mass ratio 5:3) slurry is single-sidedly coated on a 50-μm-thick zinc foil; the length of the negative electrode zinc foil is 34 cm and the width is 5.5 cm; the side of the negative electrode zinc foil with the active material is attached to the separator; after the rectangular negative electrode and the rectangular separator are folded face-to-face along the perpendicular line of the long side with the active material facing each other, the other side of the separator is attached to both sides of the positive electrode; the negative electrode current collector is closely attached to one side of the folded negative electrode without the active material coated; at the folding line, it is wound together with the positive electrode, negative electrode, and separator into a cylindrical battery core and placed inside the cylinder of the cylindrical battery case. The long side of the rectangular current collection area without the current distribution area is coincident with the negative electrode folding line.

[0059] The positive electrode active material is nickel hydroxide (92%), and also includes cobalt oxide (2%), carbon nanotubes (2%), and a binder (4%). The negative electrode active material is zinc oxide and zinc powder (accounting for 88% in total), and also includes carbon nanotubes (5%), indium hydroxide (2%), and a binder (5%).

[0060] This cylindrical battery is charged and discharged in a constant current of 0.2 A. The discharge cut-off voltage is 1.2 V, the Coulomb efficiency is greater than 95%, the energy efficiency is greater than 90%, the discharge capacity is greater than 1.2 Ah, and it can be cycled more than 40 times.

[0061] Comparative Example 1

[0062] Use a copper rectangular tab with a long side of 40 mm, a short side of 3 mm, and a thickness of 100 μm. Weld the tab to the negative zinc foil by ultrasonic welding. The long side of the tab coincides with the fold line perpendicular to the long side of the zinc foil, and the length of the long side of the tab in contact with the zinc foil is 10 mm. It is used in a cylindrical 18650 zinc-nickel battery, which also includes a nickel positive electrode, a zinc negative electrode, a separator, an alkaline electrolyte (6M potassium hydroxide), a cylindrical battery case, and a battery case cover; the positive active material nickel hydroxide is double-sidedly coated on nickel foam, and the negative active material zinc oxide and zinc powder (mass ratio 5:3) slurry is single-sidedly coated on a 50-μm-thick zinc foil; the length of the negative zinc foil is 34 cm and the width is 5.5 cm; the side of the negative zinc foil with active material is in contact with the separator; after the rectangular negative electrode and the rectangular separator are folded face-to-face along the perpendicular to the long side with the active material surfaces facing each other, the other side of the separator is in contact with both sides of the positive electrode; the copper rectangular tab is closely attached to one of the sides of the folded negative electrode without coated active material; at the fold line, it is wound together with the positive electrode, negative electrode, and separator into a cylindrical battery core and placed inside the cylinder of the cylindrical battery case.

[0063] The positive active material is nickel hydroxide (92%), and also includes cobaltous oxide (2%), carbon nanotubes (2%), and binder (4%); the negative active material is zinc oxide and zinc powder (accounting for 88% in total), and also includes carbon nanotubes (5%), indium hydroxide (2%), and binder (5%).

[0064] The cylindrical battery is charged and discharged in a constant current of 0.2 A, the discharge cut-off voltage is 1.2 V, the Coulomb efficiency is greater than 95%, the energy efficiency is greater than 90%, the discharge capacity is greater than 1.2 Ah, and the number of cycles is less than 20 times.

[0065] Comparative Example 2

[0066] Directly use the zinc foil with the single-sidedly coated active material exposed outside the wound battery core as the current collector, which is in direct contact with the 18650 nickel-plated battery case to conduct the current. The battery also includes a nickel positive electrode, a separator, an alkaline electrolyte (6M potassium hydroxide), a cylindrical battery case, and a battery case cover; the positive active material nickel hydroxide is double-sidedly coated on nickel foam, and the negative active material zinc oxide and zinc powder (mass ratio 5:3) slurry is single-sidedly coated on a 50-μm-thick zinc foil; the length of the negative zinc foil is 34 cm and the width is 5.5 cm; the side of the negative zinc foil with active material is in contact with the separator; after the rectangular negative electrode and the rectangular separator are folded face-to-face along the perpendicular to the long side with the active material surfaces facing each other, the other side of the separator is in contact with both sides of the positive electrode; at the fold line, it is wound together with the positive electrode, negative electrode, and separator into a cylindrical battery core and placed inside the cylinder of the cylindrical battery case.

[0067] The positive electrode active material is nickel hydroxide (92%), and also includes cobaltous oxide (2%), carbon nanotubes (2%) and binder (4%). The negative electrode active material is zinc oxide and zinc powder (accounting for 88% in total), and also includes carbon nanotubes (5%), indium hydroxide (2%) and binder (5%).

[0068] Serious hydrogen evolution reaction will occur in the battery. For this cylindrical battery, it is charged and discharged in a constant current of 0.2 A. The discharge cut-off voltage is 1.2 V, the Coulomb efficiency is greater than 95%, the energy efficiency is greater than 90%, the discharge capacity is greater than 1.2 Ah, and the number of cycles is less than 20 times.

[0069] The above are only several embodiments of the present application, and do not impose any form of limitation on the present application. Although the present application is disclosed above with preferred embodiments, it is not intended to limit the present application. Any person skilled in the art, without departing from the scope of the technical solution of the present application, makes some changes or modifications using the technical content disclosed above, which are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

Claims

1. A negative current collector for a zinc-nickel battery, characterized in that, It includes a current collection area and a current distribution area; The current collection area and the current distribution area are independently rectangular; One short side of the current collection area is flush with one long side of the current distribution area; One long side of the current collection area is attached to one short side of the current distribution area to form an electronic path; The long side of the current collection area is longer than the short side of the current distribution area; The current distribution area is provided with through holes; 2. The negative current collector for a zinc-nickel battery according to claim 1, characterized in that, The projection areas of the current collection area and the current distribution area have an overlapping part; The overlapping part is rectangular; The long side of the overlapping part is equal to the length of the short side of the current distribution area; The short side of the overlapping part is equal to the length of the short side of the current collection area; 3. The negative current collector for a zinc-nickel battery according to claim 1, characterized in that, The thickness of the current collection area is 20 - 200 μm; 4. The negative current collector for a zinc-nickel battery according to claim 1, characterized in that, The thickness of the current distribution area is 6 - 20 μm; 5. The negative current collector for a zinc-nickel battery according to claim 1, characterized in that, The length of the short side of the current collection area is 1 - 4 mm; 6. The negative current collector for a zinc-nickel battery according to claim 1, characterized in that, The materials of the current collection area and the current distribution area independently include at least one of copper, brass, copper tin, and copper indium alloy; 7. The negative current collector for a zinc-nickel battery according to claim 1, characterized in that, The shape of the through hole includes one of a circle, a quadrilateral, a triangle, and a special-shaped through hole; 8. The negative current collector for a zinc-nickel battery according to claim 1, characterized in that, The distance between two adjacent through holes is 1 - 15 mm; Preferably, the total area of the through holes accounts for 10 - 50% of the area of the current distribution area; 9. Application of the negative current collector for a zinc-nickel battery according to any one of claims 1 to 8 in the preparation of a cylindrical zinc-nickel battery.

10. The application according to claim 9, characterized in that, The negative electrode current collector of the zinc-nickel battery is attached to the negative electrode in the cylindrical zinc-nickel battery.

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