Bipolar plate for nickel-metal hydride battery

Abstract

The bipolar polar plate comprises a conductive substrate, and a first conductive layer and a second conductive layer are respectively arranged on the front surface and the back surface of the conductive substrate; a first porous layer is fixedly arranged on the surface of the first conductive layer, and a positive active material layer is loaded on the first porous layer; a second porous layer is fixedly arranged on the surface of the second conductive layer, and the second porous layer is loaded with a negative electrode active material layer and forms a whole through rolling treatment. By arranging the first porous layer and the second porous layer, the binding force between the positive and negative active substances and the conductive substrate is enhanced, and the positive and negative active substance layers are prevented from being stripped and falling off from the conductive substrate; meanwhile, when the nickel-metal hydride storage battery is overcharged, oxygen is generated from the positive electrode, and the oxygen easily penetrates through the second porous layer, is absorbed to the negative electrode active material layer and reacts with hydrogen in a preset negative electrode active material serving as charging reserve to become return water, so that the problem of rising of the internal pressure of the battery is solved; the first conductive layer and the second conductive layer are arranged on the conductive substrate, so that the conductivity and the heat dissipation performance of positive and negative active substances are improved, the rate capability of the nickel-metal hydride battery is improved, and the cycle life of the nickel-metal hydride battery is prolonged.

Description

Technical Field

[0001] The utility model belongs to the field of bipolar nickel-hydrogen batteries, and in particular relates to a bipolar plate used for nickel-hydrogen batteries. Background Art

[0002] In recent years, due to the dwindling availability of fossil fuels, the development and utilization of hydrogen energy has received increasing attention. Nickel-metal hydride batteries are gaining increasing attention as a key area of ​​hydrogen energy application. Currently, nickel-metal hydride batteries have a low energy density due to their voltage of 1.2 to 1.3V, while bipolar nickel-metal hydride batteries offer higher energy density.

[0003] In the prior art, the bipolar electrode used in nickel-hydrogen batteries comprises: a metal foil; a positive electrode active material layer, which is coated on one side of the metal foil; and a negative electrode active material layer, which is coated on the other side of the metal foil. The positive electrode active material layer contains nickel hydroxide Ni(OH)2 as a positive electrode active material. In addition, the negative electrode active material layer contains a hydrogen storage alloy as a negative electrode active material. In the bipolar electrode of the nickel-hydrogen battery, after coating the positive electrode active material layer and the negative electrode active material layer on the metal foil, these active material layers are pressurized to make them adhere tightly to the metal foil, thereby preventing the active material layers from peeling off and falling off from the metal foil and improving the charge and discharge performance.

[0004] When overcharged, nickel-metal hydride batteries generate oxygen from the positive electrode. This oxygen is typically absorbed into the negative electrode active material layer and then reacts with hydrogen in the negative electrode active material, which is pre-set as a charge reserve, to convert back into water. However, if the porosity of the negative electrode active material layer is low, the oxygen generated from the positive electrode has difficulty entering the negative electrode active material layer, resulting in oxygen accumulation within the battery. Furthermore, when the battery's internal pressure rises due to oxygen accumulation, the safety valve may activate, disrupting the balance between the charge reserve and discharge reserve, leading to battery degradation. Simply increasing the porosity of the negative electrode active material layer to avoid this problem can lead to problems such as the negative electrode active material layer easily peeling off the metal foil, causing a decrease in charge and discharge performance. Furthermore, due to the poor conductivity of the positive and negative electrode active materials, nickel-metal hydride batteries suffer from poor rate performance and cycle life that falls short of user expectations. Utility Model Content

[0005] The utility model discloses a bipolar plate for nickel hydrogen battery, which can solve the problems of poor rate performance of nickel hydrogen battery, large current charging and discharging, and short cycle life, and can improve the combination of positive and negative active materials and the conductivity and heat dissipation performance of positive and negative active materials.

[0006] The technical scheme of the utility model is as follows:

[0007] A bipolar plate for nickel hydrogen battery, comprising a conductive substrate, wherein the front and back surfaces of the conductive substrate are respectively provided with a first conductive layer and a second conductive layer.

[0008] The surface of the first conductive layer is fixedly provided with a first porous layer, and the first porous layer is loaded with a positive active material layer; the surface of the second conductive layer is fixedly provided with a second porous layer, and the second porous layer is loaded with a negative active material layer, and the first porous layer and the second porous layer are formed into an integral whole through rolling treatment.

[0009] Compared with the prior art, the utility model has the advantages of:

[0010] By setting the first porous layer and the second porous layer, the combination of positive and negative active materials and the conductive substrate is enhanced, and the positive and negative active material layers are prevented from peeling off or falling off from the conductive substrate; at the same time, oxygen is generated from the positive electrode of the nickel hydrogen battery during overcharging, the oxygen can easily penetrate through the second porous layer and be absorbed into the negative active material layer, and the hydrogen in the negative active material layer as the charging reserve reacts with the hydrogen to return to water, thereby solving the problem of the increase of the internal pressure of the battery; by setting the first conductive layer and the second conductive layer on the conductive substrate, the conductivity and heat dissipation performance of positive and negative active materials are improved, thereby improving the rate performance and cycle life of the nickel hydrogen battery.

[0011] As a further improvement of the above technical scheme, the first conductive layer comprises one of a nickel mesh, a copper mesh, a stainless steel mesh, a nickel-plated steel mesh, a titanium-plated steel mesh, a titanium mesh, and a carbon-plated steel mesh.

[0012] The second conductive layer comprises one of a nickel mesh, a copper mesh, a stainless steel mesh, a nickel-plated steel mesh, a titanium-plated steel mesh, a titanium mesh, and a carbon-plated steel mesh.

[0013] The technical effect of the above improvement is: the first conductive layer and the second conductive layer are made of conductive material into a mesh structure, which improves the conductivity and heat dissipation performance of the positive and negative active materials, and at the same time improves the bonding strength between the first porous layer, the second porous layer and the conductive substrate, thereby improving the rate performance and cycle life of the nickel-hydrogen battery.

[0014] As a further improvement of the above technical solution, the first conductive layer, the second conductive layer and the conductive substrate are fixed by welding.

[0015] As a further improvement of the above technical solution, the welding part between the first conductive layer and the conductive substrate is in the shape of an elongated strip, and there are several welding parts, which are arranged in the length direction of the conductive substrate; the cross-sectional area of ​​the first conductive layer is less than or equal to the cross-sectional area of ​​the conductive substrate.

[0016] As a further improvement of the above technical solution, the welding part between the second conductive layer and the conductive substrate is in the shape of an elongated strip, and there are several welding parts, which are arranged in the length direction of the conductive substrate; the cross-sectional area of ​​the second conductive layer is less than or equal to the cross-sectional area of ​​the conductive substrate.

[0017] The technical effect of the above improvement is: through multiple horizontally arranged welding parts, the first conductive layer, the second conductive layer and the conductive substrate are welded and fixed, thereby improving the connection stability of the first conductive layer, the second conductive layer and the conductive substrate, and at the same time dividing the conductive substrate into several areas. The area between the two welding parts is the active material loading area, and there is no active material in the welding part, which is conducive to shortening the electron transmission distance and improving its large current charging and discharging capability.

[0018] As a further improvement of the above technical solution, the first conductive layer includes one of a carbon coating, a metal coating, and a conductive polymer coating; the second conductive layer includes one of a carbon coating, a metal coating, and a conductive polymer coating.

[0019] As a further improvement of the above technical solution, the first conductive layer and the second conductive layer are prepared by spraying a glue solution containing a conductive agent onto the conductive substrate.

[0020] As a further improvement of the above technical solution, the first porous layer is made of metal, preferably one of foam nickel, perforated copper mesh, perforated nickel belt, woven copper mesh, and perforated steel belt.

[0021] As a further improvement of the above technical solution, the second porous layer is made of metal, preferably one of foam nickel, perforated copper mesh, perforated nickel belt, woven copper mesh, and perforated steel belt.

[0022] The technical effect of the above improvement is: by setting the first porous layer and the second porous layer, not only can the bonding force between the active material and the conductive substrate be enhanced, and the metal material with good conductivity be used, but the interface resistance can also be reduced; at the same time, the porosity between the negative electrode active material layer and the conductive substrate can be increased, solving the problem of easy accumulation of oxygen in nickel-hydrogen batteries.

[0023] As a further improvement of the above technical solution, the conductive substrate includes but is not limited to one of a nickel-plated steel plate, a nickel-plated copper plate, a nickel plate and a stainless steel plate.

[0024] The technical effect of the above improvement is that the raw materials of the conductive substrate are extensive and inexpensive, which can reduce production costs.

[0025] A nickel-hydrogen battery comprises a positive monopolar plate, the bipolar plate, a negative monopolar plate, and a separator arranged between the positive and negative electrodes.

[0026] The beneficial effects of the above scheme are: by adopting the bipolar plates described in the utility model to assemble a bipolar nickel-metal hydride battery, the energy density, high current charge and discharge performance, and cycle life of the nickel-metal hydride battery are significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] To more clearly illustrate the technical solutions implemented by the present invention, the following drawings are briefly introduced. The following drawings are only some implementation examples of the present invention, and those skilled in the art can apply them according to the drawings and actual production conditions without any creative work.

[0028] Figure 1 This is a front view of the conductive substrate on which the first conductive layer and the second conductive layer are welded in Example 1;

[0029] Figure 2 for Figure 1 Side view of;

[0030] Figure 3 is a cross-sectional view of the bipolar plate in Example 1;

[0031] Figure 4 for Figure 3 A partial enlarged view of

[0032] Figure 5 This is a front view of the conductive substrate on which the first conductive layer and the second conductive layer are sprayed in Example 3;

[0033] Figure 6 It is a cross-sectional view of the main body of a bipolar nickel-metal hydride battery;

[0034] Explanation of reference numerals: 1-conductive substrate, 2-first conductive layer, 3-second conductive layer, 4-first porous layer, 5-positive electrode active material layer, 6-second porous layer, 7-negative electrode active material layer, 8-welding portion, 9-sealing frame, 10-diaphragm, 11-positive monopolar plate, 12-negative monopolar plate. DETAILED DESCRIPTION

[0035] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0036] It should be noted that the terms "up," "down," "left," "right," "front," and "back" used herein to describe directions do not refer to specific directions unless otherwise specified. These terms are provided for convenience only. The descriptions may vary depending on the orientation of the product. Any directions that can be understood by a person of ordinary skill in the art without inventive effort are within the scope of protection of this utility model.

[0037] Example 1

[0038] like Figure 1-4 As shown, a bipolar plate for a nickel-hydrogen battery includes a conductive substrate 1, wherein a first conductive layer 2 and a second conductive layer 3 are provided on the front and back surfaces of the conductive substrate 1 respectively, and the first conductive layer 2, the second conductive layer 3 are fixed to the conductive substrate 1 by welding; a first porous layer 4 is fixed on the surface of the first conductive layer 2, and the first porous layer 4 is loaded with a positive electrode active material layer 5; a second porous layer 6 is fixed on the surface of the second conductive layer 3, and the second porous layer 6 is loaded with a negative electrode active material layer 7, and the plates are formed into a whole by rolling treatment.

[0039] In this embodiment, the welding part 8 between the first conductive layer 2 and the conductive substrate 1 is in the shape of an elongated strip, which is four transversely arranged areas, and the welding part passes through the first conductive layer 2 in the length direction; the cross-sectional area of ​​the first conductive layer 2 is less than or equal to the cross-sectional area of ​​the conductive substrate 1.

[0040] In this embodiment, the welding portion 8 between the second conductive layer 3 and the conductive substrate 1 is in the shape of an elongated strip, consisting of four transversely arranged areas, and the welding portion passes through the second conductive layer 3 in the length direction; the cross-sectional area of ​​the second conductive layer 3 is less than or equal to the cross-sectional area of ​​the conductive substrate 1.

[0041] In this embodiment, the first conductive layer 2 is a stainless steel mesh.

[0042] In this embodiment, the second conductive layer 3 is a stainless steel mesh.

[0043] In this embodiment, the conductive substrate 1 is a stainless steel plate.

[0044] In this embodiment, the first porous layer 4 is nickel foam.

[0045] In this embodiment, the second porous layer 6 is nickel foam.

[0046] In this embodiment, the first conductive layer, the second conductive layer and the conductive substrate are welded and fixed through multiple horizontally arranged welding parts, thereby improving the connection stability of the first conductive layer, the second conductive layer and the conductive substrate. At the same time, the conductive substrate is divided into several areas. The area between the two welding parts is the active material loading area. The welding parts are free of active materials, which is conducive to shortening the electron transmission distance and improving its large current charging and discharging capability.

[0047] In this embodiment, the cross-sectional area of ​​the first conductive layer 2 is greater than or equal to the cross-sectional area of ​​the first porous layer 4 .

[0048] In this embodiment, the cross-sectional area of ​​the second conductive layer 3 is greater than or equal to the cross-sectional area of ​​the second porous layer 6 .

[0049] In this embodiment, the cross-sectional area of ​​the first porous layer 4 is greater than or equal to the area of ​​the region where the positive electrode active material layer 5 is supported.

[0050] In this embodiment, the cross-sectional area of ​​the second porous layer 6 is greater than or equal to the area of ​​the region where the negative electrode active material layer 7 is supported.

[0051] Example 2

[0052] The production process of the bipolar plates of the nickel-metal hydride battery comprises the following steps:

[0053] (1) The first conductive layer 2 and the second conductive layer 3 are respectively placed on both sides of the conductive substrate, and the first conductive layer 2, the second conductive layer 3 and the conductive substrate are welded and fixed by welding; the welding portion 8 is in the shape of a long strip and is composed of four transversely arranged areas. The positions of the welding portions 8 on the front and back sides of the conductive substrate correspond to each other. The welding portions 8 pass through the first conductive layer 2 and the second conductive layer 3 in the length direction, and the cross-sectional areas of the first conductive layer 2 and the second conductive layer 3 are equal to the cross-sectional area of ​​the conductive substrate 1;

[0054] (2) coating the first porous layer 4 and the second porous layer 6 with a positive electrode active material and a negative electrode active material, respectively, to prepare a first porous layer 4 loaded with a positive electrode active material and a second porous layer 6 loaded with a negative electrode active material, and drying the layers;

[0055] (3) The first porous layer 4 loaded with the positive electrode active material obtained in step (2) is attached to the surface of the first conductive layer 2, and the second porous layer 6 loaded with the negative electrode active material obtained in step (2) is attached to the surface of the second conductive layer 3, specifically:

[0056] Three first porous layers 4 are arranged between two adjacent welding locations 8 on the surface of the first conductive layer 2, and three second porous layers 6 are arranged between two adjacent welding locations 8 on the surface of the second conductive layer 3. Then, they are rolled to form a whole, and then cut to obtain a bipolar plate.

[0057] Example 3

[0058] A bipolar plate for a nickel-hydrogen battery comprises a conductive substrate 1, wherein the front and back surfaces of the conductive substrate 1 are coated with a first conductive layer 2 and a second conductive layer 3. Figure 5 As shown;

[0059] The surface of the first conductive layer 2 is fixed with a first porous layer 4, which is loaded with a positive electrode active material layer 5; the surface of the second conductive layer 3 is fixed with a second porous layer 6, which is loaded with a negative electrode active material layer 7, and they are formed into a whole by rolling treatment.

[0060] In this embodiment, the first conductive layer 2 is a carbon coating.

[0061] In this embodiment, the second conductive layer 3 is a carbon coating.

[0062] The remaining process parameters are the same as in Example 1.

[0063] Example 4

[0064] The production process of the bipolar plates of the nickel-metal hydride battery comprises the following steps:

[0065] (1) Spraying a PVDF glue containing conductive carbon black onto the front and back surfaces of the conductive substrate 1 and drying to 80% to 90% to prepare a semi-solid to fully solid first conductive layer 2 and a second conductive layer 3;

[0066] (2) coating the first porous layer 4 and the second porous layer 6 with a positive electrode active material and a negative electrode active material, respectively, to prepare a first porous layer 4 loaded with a positive electrode active material and a second porous layer 6 loaded with a negative electrode active material, and drying the layers;

[0067] (3) The first porous layer 4 loaded with the positive electrode active material is adhered to the surface of the first conductive layer 2, and the second porous layer 6 loaded with the negative electrode active material is adhered to the surface of the second conductive layer 3. The two layers are rolled to form a whole, and then dried to obtain a bipolar plate for a nickel-hydrogen battery.

[0068] Example 5

[0069] like Figure 6As shown, a bipolar nickel-hydrogen battery comprises a positive single pole plate 11, the bipolar pole plate, a negative single pole plate 12, and a separator 10 arranged between the positive and negative poles. The rest of the technology is well known in the art, and will not be repeated here.

[0070] The above only describes preferred embodiments of the present application, and the protection scope of the present application is not limited to the above. Improvements and changes obtained by those skilled in the art without departing from the technical concept of the present application should also be considered as the protection scope of the present application.

Claims

1. A bipolar plate for a nickel-hydrogen battery, comprising a conductive substrate (1), characterized in that: The front and back surfaces of the conductive substrate (1) are respectively provided with a first conductive layer (2) and a second conductive layer (3); A first porous layer (4) is fixedly provided on the surface of the first conductive layer (2), and the first porous layer (4) is loaded with a positive electrode active material layer (5); a second porous layer (6) is fixedly provided on the surface of the second conductive layer (3), and the second porous layer (6) is loaded with a negative electrode active material layer (7), and the two layers are formed into a whole through rolling treatment.

2. A bipolar plate for a nickel-hydrogen battery according to claim 1, characterized in that: The first conductive layer (2) includes but is not limited to one of nickel mesh, copper mesh, stainless steel mesh, nickel-plated steel mesh, titanium-plated steel mesh, titanium mesh, and carbon-plated steel mesh; The second conductive layer (3) includes but is not limited to one of a nickel mesh, a copper mesh, a stainless steel mesh, a nickel-plated steel mesh, a titanium-plated steel mesh, a titanium mesh, and a carbon-plated steel mesh.

3. A bipolar plate for a nickel-hydrogen battery according to claim 2, characterized in that: The first conductive layer (2), the second conductive layer (3) and the conductive substrate (1) are fixed by welding.

4. A bipolar plate for a nickel-hydrogen battery according to claim 3, characterized in that: The welding portion (8) between the first conductive layer (2) and the conductive substrate (1) is in the shape of a long strip, the number of welding portions (8) is several, and the welding portions (8) are arranged in the length direction of the conductive substrate (1); The cross-sectional area of ​​the first conductive layer (2) is smaller than or equal to the cross-sectional area of ​​the conductive substrate (1).

5. The bipolar plate for nickel-hydrogen batteries according to claim 3, characterized in that: The welding portion (8) between the second conductive layer (3) and the conductive substrate (1) is in the shape of a long strip, the number of welding portions (8) is several, and the welding portions (8) are arranged in the length direction of the conductive substrate (1); The cross-sectional area of ​​the second conductive layer (3) is smaller than or equal to the cross-sectional area of ​​the conductive substrate (1).

6. A bipolar plate for a nickel-hydrogen battery according to claim 1, characterized in that: The first conductive layer (2) comprises one of a carbon coating, a metal coating, and a conductive polymer coating; The second conductive layer (3) comprises one of a carbon coating, a metal coating, and a conductive polymer coating.

7. A bipolar plate for a nickel-hydrogen battery according to claim 6, characterized in that: The preparation process of the first conductive layer (2) and the second conductive layer (3) is as follows: a glue solution containing a conductive agent is sprayed onto the conductive substrate (1).

8. The bipolar plate for nickel-hydrogen batteries according to claim 1, characterized in that: The first porous layer (4) is made of metal material, selected from one of foam nickel, punched copper mesh, punched nickel strip, woven copper mesh, and punched steel strip; The second porous layer (6) is made of metal material, selected from one of foam nickel, punched copper mesh, punched nickel strip, woven copper mesh, and punched steel strip.

9. The bipolar plate for nickel-hydrogen batteries according to claim 1, characterized in that: The conductive substrate (1) includes but is not limited to one of a nickel-plated steel plate, a nickel-plated copper plate, a nickel plate and a stainless steel plate.

10. A nickel-metal hydride battery, characterized in that: The invention comprises a positive monopolar plate, a bipolar plate according to any one of claims 1 to 7, a negative monopolar plate, and a separator arranged between the positive and negative electrodes.

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