A method for processing the edge of a zinc-nickel battery negative electrode

Abstract

The present application relates to a kind of zinc-nickel battery negative electrode edge processing method, negative electrode is made of negative electrode material loaded on current collector, 1) the positive and negative sides of the current collector are coated with negative electrode material, and electrode is prepared;2) edge processing: after coating negative electrode material, the area of the edge of electrode 1-3mm (preferably 1.5-2.5mm) from the edge of electrode on the positive and negative sides is coated with glue, and the side of the edge of electrode is also coated with glue treatment, and the glue material is solidified.The method aims to inhibit the electrochemical deposition of zinc at the edge of electrode, thereby improving the capacity retention of zinc-nickel battery, and prolonging the service life of battery.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically a method for coating and protecting the edge of the current collector in a zinc-nickel battery mesh negative electrode. Background Technology

[0002] Zinc-nickel batteries maintain their advantages in traditional fields such as consumer electronics, smart homes, and toys due to their high energy density, excellent safety, and long cycle life, and even show great application potential in new energy vehicles and energy storage systems. However, further enhancing the market competitiveness of zinc-nickel batteries and improving their cycle stability, efficiency, and capacity retention remain key research and development tasks.

[0003] Brass mesh or copper mesh possesses excellent electrical conductivity, mechanical properties, and corrosion resistance, making it suitable as a carrier material for the current collector in zinc-nickel batteries. The main active materials for the negative electrode include zinc oxide, zinc powder, and other functional powders. During charging, metallic zinc deposits on the negative electrode, while during discharging, it oxidizes into other forms of divalent zinc. However, during the cutting process of the zinc-nickel battery negative electrode, the current collector fibers are easily exposed on the electrode surface or edges. This causes zinc to easily deposit on the exposed, unloaded current collector fibers, resulting in reduced zinc utilization and ultimately rapid capacity decay, significantly hindering its large-scale adoption. Therefore, developing a method to effectively control the deposition behavior of zinc on the negative electrode, ensuring that metallic zinc deposits at the location coated with the active material to improve the utilization rate of zinc deposited on the negative electrode, is crucial for improving the overall performance and lifespan of the battery. Summary of the Invention

[0004] This invention provides a method for treating the edge of a negative electrode coated with active material. This method aims to suppress the electrochemical deposition of zinc at the electrode edge, thereby improving the capacity retention of zinc-nickel batteries and extending their lifespan.

[0005] Specifically, the technical solution of the present invention includes the following steps:

[0006] A method for processing the edge of a zinc-nickel battery negative electrode, wherein the negative electrode is composed of a negative electrode material loaded on a current collector;

[0007] 1) A negative electrode material was coated on both sides of the current collector to prepare an electrode;

[0008] 2) Edge treatment: Apply adhesive to both sides of the electrode around the perimeter of the electrode after coating the negative electrode material, within a distance of 1-3 mm (preferably 1.5-2.5 mm) from the electrode edge. Also apply adhesive to the sides of the electrode around the perimeter of the electrode. The adhesive material is then cured.

[0009] Furthermore, a tab is provided on one edge of the current collector; when the zinc-nickel battery is packaged into a battery, the outer surface of the tab portion inside the packaging shell is coated with adhesive.

[0010] Furthermore, the thickness of the adhesive coating is 50–200 micrometers (preferably 70–150 micrometers).

[0011] Furthermore, the current collector includes 80-300 mesh brass mesh and / or copper mesh current collector.

[0012] Furthermore, the adhesive includes one or more of epoxy resin adhesives and methacrylate adhesives.

[0013] Further, in step 1), after obtaining the electrode, the electrode is pressed to the required thickness by a roller press and / or a flatbed hydraulic press, and then cut into a predetermined shape for edge treatment in step 2); the pressure is 2 to 10 MPa (preferably 5 to 8 MPa).

[0014] Further, in step 2), the curing process of the colloidal material is as follows: after applying the adhesive protective material to the negative electrode, the electrode is placed at 30-80°C (preferably 40-60°C) and dried for 4-24 hours (preferably 8-16 hours) to ensure that the colloidal material is fully cured and forms a stable protective layer.

[0015] Further, the negative electrode after curing the colloidal material obtained in step 2) is compacted again by a flatbed hydraulic press and / or a roller press, with a pressure of 2 to 10 MPa (preferably 5 to 8 MPa).

[0016] The beneficial effects of the present invention: The method provided by the present invention can achieve the following beneficial effects:

[0017] 1. After applying adhesive for protection, the exposed current collector fibers at the edges are insulated and fixed to the electrodes, which alleviates the problem of conductive fibers piercing the separator and effectively prevents short circuits in the mesh negative electrode current collector during battery assembly, thereby improving the success rate of battery assembly.

[0018] 2. The current-current-density concentrated areas are the unloaded conductive fibers of the current collector exposed at the electrode edges, where zinc readily deposits, and the deposited zinc dendrites grow significantly, easily detaching from the current collector during discharge. Covering these fibers with adhesive prevents zinc deposition at the edges, reduces the formation of dead zinc, improves the utilization rate of zinc in the negative electrode, and thus enhances the battery's capacity retention. Attached Figure Description

[0019] Figure 1 Schematic diagram of double-sided coating of active material negative electrode.

[0020] Wherein: 1: Coated part, 2: Current collector, 2-1: Current collector without active material loaded on both sides inside the battery, 2-2: Current collector without active material loaded on both sides outside the battery, 3: Active material. Detailed Implementation

[0021] Zinc-nickel batteries mainly consist of a positive electrode, a separator, a negative electrode, and an electrolyte, all encapsulated in an aluminum-plastic film. The negative electrode material, by mass, comprises ZnO (67%), Zn (24%), In₂O₃ (1%), and Bi₂O₃ (1%).

[0022] Composed of CNT (2%) and PTFE (5%), the negative electrode current collector is a brass mesh (120 mesh), with double-sided coating loadings of 9–12 g / cm³. -2 (Here, 10g cm) -2 The coated surface area is length * width = 4 * 4 cm. 2 .

[0023] The positive electrode material, by mass, consists of Ni(OH)₂ (93%), CNT (2%), and PTFE (5%). The positive electrode current collector is nickel foam, and the single-sided coating loading is 19–21 g cm⁻¹. -2 (Here, 20g cm) -2 ).

[0024] The negative electrode is covered by a membrane on both sides, and the positive and negative electrode laminations are placed on both sides of the membrane, respectively. The assembly is placed in an aluminum-plastic membrane shell, and saturated zinc oxide KOH (4 mol / L) is injected. -1 The battery is encapsulated in an aqueous solution. After activation, it is charged at 2C to 1.9V, maintains a constant voltage of 1.9V, and has a cutoff current of 0.1C; it is discharged at 2C.

[0025] A tab is provided on one edge of the negative electrode current collector;

[0026] The adhesive used is epoxy resin AB glue (3M DP100).

[0027] The specific processing procedure for the negative electrode is as follows:

[0028] 1) Coat the negative electrode material on both sides of the current collector to obtain the electrode; after the electrode is pressed to the required thickness by a roller press and / or a flat hydraulic press, and cut into a predetermined shape, perform the edge treatment in step 2); the pressure is 6MPa.

[0029] 2) Edge treatment: Apply adhesive to both sides of the electrode 2mm away from the electrode edge after coating the negative electrode material, and also apply adhesive to the sides of the electrode edges.

[0030] A tab is provided on one edge of the current collector; when the zinc-nickel battery is packaged into a battery, the outer surface of the tab portion inside the packaging shell is coated with adhesive.

[0031] Curing of colloidal material: After applying the protective material to the negative electrode, place the electrode at 50°C and dry for 10 hours to ensure that the colloidal material is fully cured and forms a stable protective layer.

[0032] 3) The negative electrode after the colloidal material obtained in step 2) is cured is compacted again by a roller press at a pressure of 6 MPa.

[0033] Example 1:

[0034] Following the above procedure, the negative electrode is coated with active material on both sides. After coating the negative electrode current collector with negative electrode material on both sides, the electrode is obtained. Adhesive is applied to both sides of the electrode in an area 2mm from the electrode edge, and also to the sidewalls (thickness direction) around the electrode for protection. The adhesive layer thickness is approximately 100 micrometers. Adhesive is also applied to the unloaded active material portion inside the aluminum-plastic film encapsulation (the outer surface of the tab portion inside the aluminum-plastic film encapsulation), with a thickness of approximately 100 micrometers. The zinc-nickel pouch battery retains approximately 71% of its capacity after 200 cycles.

[0035] Comparative Example 1:

[0036] The negative electrode is a double-sided coated active material electrode, without adhesive protection (only step 1 of the above-described negative electrode processing procedure is performed to obtain the negative electrode). The remaining process conditions are the same as in Example 1. The zinc-nickel pouch cell retains approximately 50% of its capacity after 200 cycles. Without adhesive protection on the negative electrode, some zinc will deposit on the edge side of the current collector, as well as on the exposed metal parts of the current collector or the tab, resulting in significant negative electrode deformation, forming a large amount of dead zinc, and ultimately leading to rapid capacity decay.

[0037] Comparative Example 2:

[0038] The electrode is a double-sided coated active material electrode. Adhesive is applied to both sides of the electrode in a region 2mm from the electrode edge, ensuring that the electrode sides are also coated with adhesive in the thickness direction. The adhesive layer thickness is approximately 100 micrometers. No adhesive is applied to the portion of the aluminum-plastic film encapsulation not loaded with active material (step 2 of the aforementioned negative electrode processing procedure, "adhesive coating treatment on the outer surface of the tab portion within the encapsulation shell during zinc-nickel battery encapsulation"), and the remaining process conditions are the same as in Example 1. The zinc-nickel soft-pack battery retains approximately 66% of its capacity after 200 cycles. In this comparative example, a small amount of zinc deposits on the exposed metal parts of the tab, forming a large amount of dead zinc, ultimately leading to a decrease in capacity retention.

[0039] Comparative Example 3:

[0040] The negative electrode is coated with active material on both sides. Adhesive is applied to both sides of the electrode in a region 2mm from the electrode edge, with a thickness of approximately 100 micrometers. The sides of the electrode are not protected with adhesive (the step 2 of the specific negative electrode processing described above, "and also applying adhesive to the sides of the electrode edges," is not performed). Adhesive is applied to the unloaded portion inside the aluminum-plastic film encapsulation, with a thickness of approximately 100 micrometers. The remaining process conditions are the same as in Example 1. The zinc-nickel soft-pack battery retains approximately 53% of its capacity after 200 cycles. Some zinc deposits on the edge sides of the current collector, leading to significant negative electrode deformation, forming a large amount of dead zinc, and ultimately causing rapid capacity decay.

[0041] Comparative Example 4:

[0042] The negative electrode is a double-sided coated active material electrode (without step 2 of the specific negative electrode processing described above), which involves applying adhesive to both sides of the electrode within a 2mm radius around the electrode edge after coating the negative electrode material. Adhesive is applied along the thickness of the electrode side, with a thickness of approximately 100 micrometers. Adhesive is also applied to the unloaded portion inside the aluminum-plastic film encapsulation, with a thickness of approximately 100 micrometers. The remaining process conditions are the same as in Example 1. The zinc-nickel soft-pack battery retains approximately 58% of its capacity after 200 cycles. Some zinc deposits on the exposed brass mesh fibers extending to the surface of the coated active material at the edge of the negative electrode, leading to micro-short circuits and dead zinc formation, thus reducing the capacity retention after multiple cycles. Comparative Example 5:

[0043] The negative electrode is a double-sided coated active material electrode. After coating the negative electrode material on both sides of the negative electrode current collector, the electrode is obtained. Adhesive is applied to both sides of the electrode in a region 2mm from the electrode edge, and also to the sidewalls (thickness direction) around the electrode for protection. The adhesive layer thickness is approximately 10 micrometers. Adhesive is also applied to the unloaded active material portion inside the aluminum-plastic film encapsulation (the outer surface of the tab portion inside the aluminum-plastic film encapsulation), with a thickness of approximately 10 micrometers. The zinc-nickel soft-pack battery retains approximately 63% of its capacity after 200 cycles. Compared to the example, the adhesive layer in this comparative example is too thin and cannot effectively prevent zinc from depositing on the edge sides of the current collector and on the brass mesh fibers extending to the surface of the negative electrode coated with active material, resulting in a relatively large amount of dead zinc.

[0044] Comparative Example 6:

[0045] The negative electrode is a double-sided coated electrode with active material. After coating the negative electrode current collector with negative electrode material on both sides, the electrode is obtained. Adhesive is applied to both sides of the electrode in a region 2mm from the electrode edge, and also to the sidewalls (thickness direction) around the electrode for protection. The adhesive layer thickness is approximately 400 micrometers. Adhesive is also applied to the unloaded portion inside the aluminum-plastic film encapsulation (the outer surface of the tab portion inside the aluminum-plastic film encapsulation), with a thickness of approximately 400 micrometers. The zinc-nickel soft-pack battery retains approximately 57% of its capacity after 200 cycles. An excessively thick adhesive layer can increase polarization at the edge of the negative electrode during electrochemical reactions and can damage the separator during battery pressurization and assembly, leading to rapid capacity decay.

[0046] Comparative Example 7:

[0047] The negative electrode is a double-sided coated electrode with active material. After coating the negative electrode current collector with negative electrode material on both sides, the electrode is obtained. Adhesive is applied to both sides of the electrode in a region 5mm from the electrode edge, and also to the sidewalls (thickness direction) around the electrode for protection. The adhesive layer thickness is approximately 100 micrometers. Adhesive is also applied to the unloaded portion inside the aluminum-plastic film encapsulation (the outer surface of the tab portion inside the aluminum-plastic film encapsulation), with a thickness of approximately 100 micrometers. The zinc-nickel soft-pack battery retains approximately 55% of its capacity after 200 cycles. The relatively large distance between the adhesive edge and the electrode edge results in ineffective utilization of the active material in this area. Some electrodes undergoing electrochemical reactions experience charge-discharge reactions at relatively high depths, thus reducing the battery's capacity retention.

Claims

1. A method for processing the edge of a zinc-nickel battery negative electrode, wherein the negative electrode is composed of a negative electrode material loaded on a current collector, characterized in that: 1) A negative electrode material was coated on both sides of the current collector to prepare an electrode; 2) Edge treatment: Apply adhesive to both sides of the electrode around the perimeter of the electrode, 1-3 mm (preferably 1.5-2.5 mm) away from the edge of the coated negative electrode material. Also apply adhesive to the sides of the electrode around the perimeter of the electrode. The adhesive material is then cured.

2. The processing method according to claim 1, characterized in that: A tab is provided on one edge of the current collector; when the zinc-nickel battery is packaged into a battery, the outer surface of the tab portion inside the packaging shell is coated with adhesive.

3. The processing method according to claim 1 or 2, characterized in that: The thickness of the adhesive coating is 50–200 micrometers (preferably 70–150 micrometers).

4. The processing method according to claim 1 or 2, characterized in that: The current collector includes 80-300 mesh brass mesh and / or copper mesh current collector.

5. The processing method according to claim 1 or 2, characterized in that: The adhesive includes one or more of epoxy resin adhesives and methacrylate adhesives.

6. The processing method according to claim 1, characterized in that: Step 1): After obtaining the electrode, the electrode is pressed to the required thickness by a roller press and / or a flatbed hydraulic press, and then cut into a predetermined shape for edge treatment in step 2); the pressure is 2 to 10 MPa (preferably 5 to 8 MPa).

7. The processing method according to claim 1, characterized in that: In step 2), the curing process of the colloidal material is as follows: after applying the adhesive protective material to the negative electrode, the electrode is placed at 30-80°C (preferably 40-60°C) and dried for 4-24 hours (preferably 8-16 hours) to ensure that the colloidal material is fully cured and forms a stable protective layer.

8. The processing method according to claim 1, characterized in that: The negative electrode after curing the colloidal material obtained in step 2) is further compacted by a flatbed hydraulic press and / or a roller press at a pressure of 2 to 10 MPa (preferably 5 to 8 MPa).

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