Metal-air battery positive electrode structure with rough surface metal current collector and battery thereof

Abstract

The application discloses a metal-air battery positive electrode structure of a rough-surface metal current collector and a battery thereof, which comprises, in sequence along an oxygen entering direction, a rough-surface porous conductive metal current collector layer, a waterproof and air-permeable conductive layer and a catalytic layer; the current collector is in contact with the waterproof and air-permeable conductive layer on the side of a rough surface, and the roughness Rz is greater than or equal to 3 microns. The second waterproof and air-permeable layer and the conductive adhesive are cancelled in the scheme, direct and firm combination is realized through the rough-surface structure, and the scheme has the advantages of low cost, simple process, small interface resistance, stable discharge performance and the like, and is suitable for various metal-air batteries, and is especially suitable for disposable portable zinc-air batteries.

Description

Technical Field

[0001] This invention relates to the field of metal-air battery technology, and more specifically to a metal-air battery positive electrode structure with a textured metal current collector and a metal-air battery including the positive electrode structure. Background Technology

[0002] Metal-air batteries have broad application prospects in energy storage and portable power sources due to their advantages such as high energy density, environmental friendliness, and readily available raw materials. Traditional air cathodes typically consist of a catalyst layer, a current collector layer, and a waterproof and breathable conductive layer. In conventional structures, the current collector is placed between the catalyst layer and the waterproof and breathable conductive layer. However, the electrolyte can easily penetrate along the catalyst layer to the surface of the current collector, causing corrosion and shortening the battery life.

[0003] To address the aforementioned issues, existing technologies typically place the permeable layer between the catalyst layer and the metal current collector layer. This can be achieved using a double-layer waterproof, breathable, and conductive layer structure, or by using conductive adhesive to bond the current collector and the waterproof, breathable, and conductive layer (e.g., patent CN211480186U). While these methods can improve corrosion issues, they significantly increase material costs and manufacturing process complexity. Furthermore, the conductive adhesive can increase interfacial resistance, affecting battery discharge performance. Therefore, developing a metal-air battery cathode structure that is simple in structure, low in cost, firmly bonded, and stable in performance is of significant practical value. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a metal-air battery positive electrode structure with a textured metal current collector. By optimizing the stacking sequence and using a textured porous conductive metal substrate, the current collector and the waterproof and breathable conductive layer are directly and firmly bonded, eliminating the need for a second waterproof and breathable conductive layer and conductive adhesive. This reduces costs and simplifies the process while ensuring battery performance.

[0005] The technical solution adopted by this invention to solve the technical problem is as follows:

[0006] A positive electrode structure for a metal-air battery includes a catalyst layer, a waterproof and breathable conductive layer, and a current collector layer; the current collector layer, the waterproof and breathable conductive layer, and the catalyst layer are arranged sequentially along the direction in which oxygen enters the metal-air battery; the current collector layer is a rough-surfaced porous conductive metal substrate, and the side of it in contact with the waterproof and breathable conductive layer is a rough surface.

[0007] Preferably, the roughness Rz of the side of the textured porous conductive metal substrate in contact with the waterproof and breathable conductive layer is ≥3 μm.

[0008] Preferably, the textured porous conductive metal substrate is a porous metal foil, including inclined metal mesh, perforated metal mesh, or microporous metal foil, etc.

[0009] Preferably, the textured porous conductive metal substrate is made of copper, copper alloy, nickel, stainless steel, or aluminum.

[0010] Preferably, the rough surface is obtained by electrolysis, etching or mechanical roughening.

[0011] Preferably, the current collector layer, the waterproof, breathable, and conductive layer, and the catalyst layer are integrally bonded together by hot pressing or roll pressing.

[0012] The present invention also provides a metal-air battery comprising the above-described metal-air battery positive electrode structure.

[0013] The beneficial effects of this invention are:

[0014] 1. The layer structure is simplified, eliminating the second waterproof, breathable, and conductive layer and conductive adhesive, significantly reducing material and manufacturing costs;

[0015] 2. The textured porous current collector has strong adhesion to the waterproof, breathable, and conductive layer, resulting in low interfacial resistance and high structural stability;

[0016] 3. When the roughness Rz≥3μm, the discharge performance is comparable to that of the traditional double-layer waterproof membrane structure, making it highly practical;

[0017] 4. The preparation process is simple and suitable for large-scale production. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of an air positive electrode structure for a textured metal current collector.

[0019] The annotations in the attached figures are explained as follows:

[0020] 1: Current collector layer; 2: Waterproof, breathable, and conductive layer; 3: Catalytic layer. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to specific embodiments.

[0022] Overall structure

[0023] This invention discloses a positive electrode structure for a metal-air battery, which consists of, in sequence along the oxygen entry direction: a current collector layer 1, a waterproof and breathable conductive layer 2, and a catalyst layer 3; the three layers are firmly bonded together by hot pressing / rolling.

[0024] Current collector layer 1

[0025] Preferably, the current collector layer 1 is made of a metal foil with a rough surface, preferably copper or copper alloy, and can be perforated copper foil, inclined copper mesh, microporous copper mesh, etc.; the thickness is preferably 0.001–0.1 mm; at least one side is rough surface, which is bonded to the waterproof, breathable and conductive layer, and the roughness Rz≥3 μm; the rough surface can be obtained by electrolytic roughening, etching or mechanical roughening.

[0026] Waterproof, breathable, and conductive layer 2

[0027] Preferably, a waterproof, breathable, and conductive membrane is used, which is made by rolling a mixture of conductive carbon powder and polytetrafluoroethylene emulsion. The thickness is preferably 0.1–1 mm, and it has waterproof, breathable, and conductive functions.

[0028] Catalyst layer 3

[0029] Preferably, the catalytic membrane is made by rolling a mixture of catalyst, conductive agent and polytetrafluoroethylene emulsion in an aqueous system, and the thickness is preferably 0.05–0.5 mm.

[0030] Preparation method

[0031] The current collector layer 1, the waterproof, breathable and conductive layer 2, and the catalyst layer 3 are stacked in sequence and then bonded together by hot pressing or roller pressing. The hot pressing temperature can be around 60℃ and the pressure should be moderate to ensure a strong bond between the layers.

[0032] Understandably, the current collector layer 1 contains tabs.

[0033] Furthermore, to explore the effect of surface roughness on the positive electrode, different embodiments were carried out. To explore the effect of reducing the outermost waterproof and breathable conductive film and smooth copper foil on the air battery, a control experiment was conducted.

[0034] Example 1

[0035] Using the standard profile of rough copper foil with a radius of 8 μm and a thickness of 18 μm, a porous copper foil with a porosity of 50% is obtained by punching.

[0036] Example 2

[0037] A porous copper foil with a porosity of 50% is obtained by punching holes in a low profile rough copper foil with a radius of 5µm and a thickness of 18µm.

[0038] Example 3

[0039] Using ultra-low profile copper foil with a Rz of 3µm and a thickness of 18µm, a porous copper foil with a porosity of 50% is obtained by punching.

[0040] Example 4

[0041] Using ultra-low profile copper foil with a Rz of 1.5µm and a thickness of 18µm, a porous copper foil with a porosity of 50% is obtained by punching.

[0042] Comparative Example 1

[0043] Using double-sided polished porous copper foil with the same porosity as the comparative sample, and adding a second waterproof, breathable, and conductive membrane, an air positive electrode is formed under the same pressure and temperature.

[0044] Comparative Example 2

[0045] An air positive electrode is formed by pressing a double-sided smooth porous copper foil under the same pressure and temperature.

[0046] Performance testing

[0047] Table 1 shows the voltage plateau of the three-electrode test system prepared with the above-mentioned air positive electrode, using 30% KOH solution and zinc as the reference electrode, under a discharge current density of 100 mA / cm².

[0048] Table 1

[0049] Voltage / V Example 1 1.18 Example 2 1.18 Example 3 1.18 Example 4 1.1 Comparative Example 1 1.17 Comparative Example 2 1.05

[0050] As can be seen from the table, compared with Comparative Example 1, the performance of the copper foil with a rough surface is similar to that of the copper foil without the waterproof and breathable conductive membrane. When the roughness Rz of the rough surface is greater than 3 μm, the positive electrode performance is still very high. When a smooth surface is used, its performance is greatly reduced.

[0051] Conclusion: When the surface roughness Rz ≥ 3 μm, the positive electrode discharge performance is comparable to that of the traditional double-layer waterproof membrane structure; the performance of the smooth current collector decreases significantly without a second waterproof membrane. This invention simplifies the structure and reduces costs while maintaining excellent discharge performance.

[0052] Furthermore, any metal-air battery can be made using this textured air positive electrode.

[0053] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0054] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims, and the specification and drawings can be used to interpret the content of the claims.

Claims

1. A metal-air battery positive electrode structure with a textured metal current collector, comprising a catalyst layer, a waterproof and breathable conductive layer, and a current collector layer, characterized in that: Along the direction in which oxygen enters the metal-air battery, a current collector layer, a waterproof and breathable conductive layer, and a catalyst layer are sequentially arranged; the current collector layer is a rough-surfaced porous conductive metal substrate, and the side of the rough-surfaced porous conductive metal substrate in contact with the waterproof and breathable conductive layer is a rough surface.

2. The metal-air battery positive electrode structure with a textured metal current collector according to claim 1, characterized in that, The roughness Rz of the porous conductive metal substrate with a rough surface in contact with the waterproof and breathable conductive layer is ≥3μm.

3. The metal-air battery positive electrode structure with a textured metal current collector according to claim 1, characterized in that, The textured porous conductive metal is one of the following porous metal meshes: inclined metal mesh, perforated metal mesh, or microporous metal mesh.

4. The metal-air battery positive electrode structure with a textured metal current collector according to claim 1, characterized in that, The textured porous conductive metal substrate is made of at least one of copper, copper alloy, nickel, stainless steel, or aluminum.

5. The metal-air battery positive electrode structure with a textured metal current collector according to claim 1, characterized in that, The rough surface of the porous conductive metal substrate is obtained by at least one of electrolysis, etching or mechanical roughening.

6. The metal-air battery positive electrode structure with a textured metal current collector according to claim 1, characterized in that, The current collector layer, waterproof, breathable, and conductive layer are bonded together by hot pressing or roll pressing.

7. A metal-air battery, characterized in that, The metal-air battery comprises the metal-air battery positive electrode structure according to any one of claims 1-6.

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