Electrode assembly, zinc-nickel battery and electric equipment

Abstract

The invention provides an electrode assembly, a zinc-nickel battery and electric equipment, and belongs to the technical field of zinc-nickel battery manufacturing. The electrode assembly comprises a negative plate, a diaphragm and a positive plate; the diaphragm is positioned between the negative plate and the positive plate; a negative active layer in the negative plate comprises the following components in percentage by mass: 45-60% of ZnO, 15-30% of Zn, 1-7% of Bi2O3, 1-7% of a negative conductive agent, 1.5-10% of ceramic fibers and 0.7-15% of an auxiliary agent, the diameter of the ceramic fibers is 2-4 microns, the length of the ceramic fibers is 100-200 microns, and the zinc-nickel battery corresponding to the electrode assembly has relatively excellent high-rate discharge performance.

Description

Technical Field

[0001] The present application relates to the technical field of zinc-nickel battery manufacturing, and in particular to an electrode assembly, a zinc-nickel battery and an electrical device. Background Art

[0002] Nickel-zinc battery is a new type of battery that is expected to replace nickel-metal hydride battery. Compared with nickel-metal hydride battery, it has advantages such as high voltage and strong discharge current. However, the existing nickel-zinc battery has poor high-rate (5C and above) discharge performance and is difficult to meet application requirements. Therefore, it is urgent to develop a nickel-zinc battery with better high-rate discharge performance. Summary of the invention

[0003] The purpose of the present application is to provide an electrode assembly, a zinc-nickel battery and an electrical device. The zinc-nickel battery corresponding to the electrode assembly has relatively excellent high-rate discharge performance.

[0004] The embodiment of the present application is implemented as follows:

[0005] In a first aspect, an embodiment of the present application provides an electrode assembly, comprising a negative electrode sheet, a separator and a positive electrode sheet, wherein the separator is located between the negative electrode sheet and the positive electrode sheet; in terms of mass percentage, the negative electrode active layer in the negative electrode sheet comprises: ZnO 45-60%, Zn 15-30%, Bi2O3 1-7%, a negative electrode conductive agent 1-7%, ceramic fiber 1.5-10% and an additive 0.7-15%, wherein the diameter of the ceramic fiber is 2-4 μm, and the length of the ceramic fiber is 100-200 μm.

[0006] In the above technical solution, the negative electrode active layer in the negative electrode sheet contains the above-mentioned mass proportion of ceramic fibers and limits its diameter and length to the above-mentioned ranges respectively. On the one hand, the surface of the three-dimensional porous skeleton formed by the inorganic ceramic fibers has a large polarity, which helps the electrolyte to fully infiltrate the electrode sheet, thereby facilitating ion transmission; on the other hand, the ceramic fibers have a suitable diameter and length, so that the three-dimensional porous skeleton structure formed by the ceramic fibers contains abundant mesopores (pore size is 5-50nm), and the pores of suitable size can serve as ion diffusion channels, thereby promoting the reactivity and reversibility of the zinc negative electrode; at the same time, the pores of suitable size make the three-dimensional porous skeleton have a large specific surface area, which is conducive to the zincate ions (formed by the reaction of zinc oxide and hydroxide) in the negative electrode. Directed and uniform deposition in the negative electrode sheet, thereby effectively reducing the risk of deformation of the negative electrode sheet during operation. Through the combined effect of the two aspects, the corresponding zinc-nickel battery has a relatively excellent high-rate discharge performance (for example, a longer cycle life).

[0007] In some alternative embodiments, the ceramic fibers include alumina ceramic fibers.

[0008] In the above technical solution, alumina ceramic fiber has relatively excellent thermal conductivity, and can quickly transfer the internal high temperature generated during high-rate discharge to the external environment, thereby improving the safety and cycle performance of the corresponding battery.

[0009] In some optional embodiments, the positive electrode active layer in the positive electrode sheet includes: 87-95% cobalt-coated spherical Ni(OH)2, 1-10% positive electrode conductor and 1-5% rare earth metal oxide, wherein the mass proportion of cobalt in the cobalt-coated spherical Ni(OH)2 is 8-10%.

[0010] In the above technical scheme, the mass proportion of cobalt in the cobalt-coated spherical Ni(OH)2 is limited to the above range, so that the cobalt-coated spherical Ni(OH)2 has a higher cobalt content. The higher cobalt content makes the spherical nickel have higher conductivity, which in turn helps the corresponding battery to perform high-rate discharge.

[0011] In some optional embodiments, the positive electrode active layer further includes 1-5% of a positive electrode additive, and the positive electrode additive includes metal cobalt and / or cobalt oxide.

[0012] In the above technical solution, adding a suitable mass proportion of metal cobalt and / or cobalt oxide to the positive electrode active layer can further improve the conductivity of the spherical nickel and is more conducive to high-rate discharge of the corresponding battery.

[0013] In some optional embodiments, the thickness of the negative electrode sheet is 0.32-0.34 mm, and the thickness of the positive electrode sheet is 0.3-0.32 mm.

[0014] In the above technical solution, the thickness of the negative electrode sheet and the positive electrode sheet are respectively limited to the above range. Compared with the conventional electrode sheet thickness, it is equivalent to thinning the negative electrode sheet and the positive electrode sheet at the same time. After the electrode sheet is thinned, the time for ions to migrate from the inside of the corresponding electrode sheet to the surface of the electrode sheet can be reduced, so that more ions can migrate in the same time, which helps the corresponding battery to discharge at a high rate.

[0015] In some optional embodiments, the area of ​​the negative electrode sheet close to the positive electrode sheet is 0.051 to 0.054 m 2 The area of ​​the positive electrode sheet close to the negative electrode sheet is 0.044 to 0.048 m 2 .

[0016] In the above technical solution, the areas of the negative electrode sheet and the positive electrode sheet are respectively limited to the above ranges. Compared with the area of ​​conventional electrode sheets, it is equivalent to increasing the areas of the negative electrode sheet and the positive electrode sheet at the same time. The facing area between the positive and negative electrode sheets is increased (when the amount of ion migration per unit area is constant, the larger the area, the greater the amount of ion migration). More ions can be migrated in the same time, which helps the corresponding battery to discharge at a high rate.

[0017] In some optional embodiments, the pore size of the membrane is 3-4 μm.

[0018] In the above technical solution, the pore size of the diaphragm is limited to the above range, which is equivalent to increasing the pore size of the diaphragm compared to conventional diaphragms. The larger pore size is conducive to the rapid passage of ions, thereby facilitating the corresponding battery to perform high-rate discharge.

[0019] In a second aspect, an embodiment of the present application provides a zinc-nickel battery, comprising an electrode assembly as provided in the embodiment of the first aspect.

[0020] In some optional embodiments, the mass of the electrolyte in the zinc-nickel battery is not less than 26 g.

[0021] In the above technical solution, the mass of the electrolyte in the zinc-nickel battery is relatively large, which helps to increase the ion transport performance of the diaphragm, thereby facilitating the battery to discharge at a high rate.

[0022] In a third aspect, an embodiment of the present application provides an electrical device, including a zinc-nickel battery as provided in the embodiment of the second aspect. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0024] It should be noted that “and / or” in this application, such as “Feature 1 and / or Feature 2”, refers to the three situations of “Feature 1” alone, “Feature 2” alone, or “Feature 1” plus “Feature 2”.

[0025] In addition, in the description of the present application, unless otherwise specified, the meaning of "multiple" in "one or more" refers to two or more; the range of "value a ~ value b" includes the two end values ​​"a" and "b", and the "unit" in "value a ~ value b + unit of measurement" represents the "unit of measurement" of both "value a" and "value b".

[0026] The following is a detailed description of an electrode assembly, a zinc-nickel battery, and an electrical device according to an embodiment of the present application.

[0027] In a first aspect, an embodiment of the present application provides an electrode assembly, comprising a negative electrode sheet, a separator and a positive electrode sheet, wherein the separator is located between the negative electrode sheet and the positive electrode sheet; the negative electrode active layer in the negative electrode sheet comprises, by mass percentage: ZnO 45-60%, Zn 15-30%, Bi2O3 1-7%, a negative electrode conductive agent 1-7%, ceramic fiber 1.5-10% and an additive 0.7-15%, wherein the diameter of the ceramic fiber is 2-4 μm, for example but not limited to any point value of 2 μm, 2.5 μm, 3 μm, 3.5 μm and 4 μm or a range value between any two of the diameters; the length of the ceramic fiber is 100-200 μm, for example but not limited to any point value of 100 μm, 120 μm, 140 μm, 160 μm, 180 μm and 200 μm or a range value between any two of the lengths.

[0028] In the present application, the negative electrode active layer in the negative electrode sheet contains the above-mentioned mass proportion of ceramic fibers and limits its diameter and length to the above-mentioned ranges, respectively. On the one hand, the surface of the three-dimensional porous skeleton formed by the inorganic ceramic fibers has a large polarity, which helps the electrolyte to fully infiltrate the electrode sheet, thereby facilitating ion transmission; on the other hand, the ceramic fibers have a suitable diameter and length, so that the three-dimensional porous skeleton structure formed by the ceramic fibers contains abundant mesopores (pore size is 5-50nm), and the pores of suitable size can act as ion diffusion channels, thereby promoting the reactivity and reversibility of the zinc negative electrode; at the same time, the pores of suitable size make the three-dimensional porous skeleton have a large specific surface area, which is conducive to the zincate ions (formed by the reaction of zinc oxide and hydroxide) in the negative electrode. Directed and uniform deposition in the negative electrode sheet, thereby effectively reducing the risk of deformation of the negative electrode sheet during operation. Through the combined effect of the two aspects, the corresponding zinc-nickel battery has a relatively excellent high-rate discharge performance (for example, a longer cycle life).

[0029] It should be noted that in the prior art, the fibers in the negative electrode active layer are usually made of organic materials (the surface polarity of the skeleton formed by the organic material is relatively small, which is not conducive to the infiltration of the electrolyte and the ion transmission is limited), and the diameter (not less than 6 μm) and length (not less than 300 μm) of the fibers are usually relatively large. Correspondingly, the pores in the skeleton are relatively large, which makes the specific surface area of ​​the three-dimensional porous skeleton relatively small, which is not conducive to the directional and uniform deposition of zincate ions in the negative electrode in the negative electrode sheet, making the negative electrode sheet prone to deformation during operation, resulting in the battery's cycle performance being affected, which is particularly obvious under high-rate discharge.

[0030] It should be noted that the composition of the negative electrode auxiliary agent is not limited and can be set according to conventional selection in the art.

[0031] As an example, based on mass percentage, the negative electrode auxiliary agent includes 0.5-5% of a binder, 0.1-5% of a dispersant, and 0.1-5% of a thickener.

[0032] It should be noted that the specific types of various components in the negative electrode auxiliary agent are not limited and can be set according to the conventional selection in the art.

[0033] It should be noted that the material of the ceramic fiber is not limited and can be selected and configured according to conventional methods in the art.

[0034] As an example, the ceramic fibers include alumina ceramic fibers.

[0035] In this embodiment, the alumina ceramic fiber has relatively excellent thermal conductivity, and can quickly transfer the internal high temperature generated during high-rate discharge to the external environment, thereby improving the safety and cycle performance of the corresponding battery.

[0036] As an example, the positive electrode active layer in the positive electrode sheet includes: cobalt-coated spherical Ni(OH)287-95%, positive electrode conductive agent 1-10% and rare earth metal oxide 1-5%, wherein the mass proportion of cobalt in the cobalt-coated spherical Ni(OH)2 is 8-10%, for example but not limited to any one of 8%, 8.5%, 9%, 9.5% and 10% or a range value between any two of them.

[0037] In this embodiment, the mass proportion of cobalt in the cobalt-coated spherical Ni(OH)2 is limited to the above range, so that the cobalt-coated spherical Ni(OH)2 has a higher cobalt content. The higher cobalt content makes the spherical nickel have a higher conductivity, which in turn helps the corresponding battery to perform high-rate discharge.

[0038] It is understandable that, in addition to the above components, the positive electrode active layer also includes some auxiliary components, and the specific composition and mass proportion of the auxiliary components can be set according to the conventional selection in the art.

[0039] As an example, the positive electrode active layer further includes 0.05-1% I2O3, 0.05-5% binder and 0.2-5% thickener.

[0040] It should be noted that the specific types of various components in the positive electrode active layer are not limited and can be set according to conventional selection in the art.

[0041] As an example, the rare earth metal oxide includes Y2O3.

[0042] In this embodiment, the use of the above-mentioned types of rare earth metal oxides helps to reduce the oxygen evolution potential of the positive electrode, thereby inhibiting oxygen evolution at the positive electrode and increasing the positive electrode capacity.

[0043] As an example, the positive electrode active layer also includes 1 to 5% of positive electrode additives, such as but not limited to any one of 1%, 2%, 3%, 4% and 5% by mass or a range between any two of them; the positive electrode additives include metallic cobalt and / or cobalt oxide.

[0044] In this embodiment, adding a suitable mass proportion of metal cobalt and / or cobalt oxide to the positive electrode active layer can further enhance the conductivity of the spherical nickel and facilitate high-rate discharge of the corresponding battery.

[0045] As an example, the thickness of the negative electrode sheet is 0.32-0.34 mm, for example but not limited to the thickness of any one of 0.32 mm, 0.325 mm, 0.33 mm, 0.335 mm and 0.34 mm or a range between any two of them; the thickness of the positive electrode sheet is 0.3-0.32 mm, for example but not limited to the thickness of any one of 0.3 mm, 0.31 mm, 0.315 mm and 0.32 mm or a range between any two of them.

[0046] In this embodiment, the thickness of the negative electrode sheet and the positive electrode sheet are respectively limited to the above ranges. Compared with the conventional electrode sheet thickness (the thickness of the negative electrode sheet is usually not less than 0.45 mm, and the thickness of the positive electrode sheet is usually not less than 0.38 mm), it is equivalent to thinning the negative electrode sheet and the positive electrode sheet at the same time. After the electrode sheet is thinned, the time for ions to migrate from the inside of the corresponding electrode sheet to the surface of the electrode sheet can be reduced, so that more ions can migrate in the same time, which helps the corresponding battery to discharge at a high rate.

[0047] As an example, the area of ​​the negative electrode sheet close to the positive electrode sheet is 0.051 to 0.054 m 2 , for example but not limited to an area of ​​0.051m 2 、0.052m 2 、0.053m 2 and 0.054m 2 Any point value or any range value between the two; the area of ​​the positive electrode sheet close to the negative electrode sheet is 0.044~0.048m 2 , for example but not limited to an area of ​​0.044m 2 、0.045m 2 、0.046m 2 、0.047m 2 and 0.048m 2 Any point value in or any range of values ​​between them.

[0048] In this embodiment, the area of ​​the negative electrode sheet and the positive electrode sheet are respectively limited to the above ranges, compared with the conventional electrode sheet area (the negative electrode sheet area is usually not more than 0.05m2 、The positive electrode area is usually not more than 0.04m 2 ), which is equivalent to increasing the area of ​​the negative electrode and the positive electrode at the same time. The area facing each other is increased (when the amount of ion migration per unit area is constant, the larger the area, the greater the ion migration). More ions can migrate in the same time, which helps the corresponding battery to discharge at a high rate.

[0049] As an example, the pore size of the diaphragm is 3-4 μm, for example but not limited to any one of 3 μm, 3.2 μm, 3.4 μm, 3.6 μm, 3.8 μm and 4 μm or a range between any two of the pore sizes.

[0050] In this embodiment, the pore size of the diaphragm is limited to the above range, which is equivalent to increasing the pore size of the diaphragm compared to conventional diaphragms (the pore size of the diaphragm is usually not higher than 2 μm). The larger pore size is conducive to the rapid passage of ions, thereby facilitating the corresponding battery to perform high-rate discharge.

[0051] It should be noted that any structural or functional unit not specifically described or limited in the electrode assembly may be arranged according to conventional selections in the art.

[0052] In a second aspect, an embodiment of the present application provides a zinc-nickel battery, comprising an electrode assembly as provided in the embodiment of the first aspect.

[0053] As an example, the mass of the electrolyte in the zinc-nickel battery is not less than 26 g, for example, the mass is any one of 27 g, 28 g, 29 g, 30 g, 31 g and 32 g or a range between any two of them.

[0054] In this embodiment, the mass of the electrolyte in the zinc-nickel battery is relatively large, which helps to increase the ion transport performance of the diaphragm, thereby facilitating the battery to perform high-rate discharge.

[0055] In a third aspect, an embodiment of the present application provides an electrical device, including a zinc-nickel battery as provided in the embodiment of the second aspect.

[0056] The features and performance of the present application are further described in detail below in conjunction with the embodiments.

[0057] Example 1

[0058] The present application embodiment provides an electrode assembly, specifically:

[0059] In the negative electrode sheet: the negative electrode current collector is a tinned copper mesh, the negative electrode active layer includes ZnO 60%, Zn 20%, Bi2O35%, negative electrode conductive agent (graphite) 5%, alumina ceramic fiber 3%, I2O3 1%, binder SBR 2%, dispersant (polyacrylic acid) 2% and thickener CMC 2%, wherein the diameter of the alumina ceramic fiber is 3μm and the length of the alumina ceramic fiber is 150μm; the thickness of the negative electrode sheet is 0.33mm and the area of ​​the negative electrode sheet is 0.052m 2 .

[0060] In the positive electrode sheet: the positive electrode current collector is nickel foam, the positive electrode active layer includes 90% cobalt-coated spherical Ni(OH)2, 5% positive electrode conductive agent (graphite), 2% metal cobalt, 1% rare earth metal oxide Y2O3, 1% thickener CMC and 1% binder PTFE, among which, the mass proportion of cobalt in the cobalt-coated spherical Ni(OH)2 is 8%; the thickness of the positive electrode sheet is 0.31mm, and the area of ​​the positive electrode sheet is 0.046m 2 .

[0061] Diaphragm: The pore size of the diaphragm is 3 microns.

[0062] Example 2

[0063] The embodiment of the present application provides an electrode assembly, which differs from Embodiment 1 only in that the diameter of the alumina ceramic fiber is 2 μm and the length of the alumina ceramic fiber is 100 μm.

[0064] Example 3

[0065] The embodiment of the present application provides an electrode assembly, which differs from Embodiment 1 only in that the diameter of the alumina ceramic fiber is 4 μm and the length of the alumina ceramic fiber is 200 μm.

[0066] Example 4

[0067] The embodiment of the present application provides an electrode assembly, which differs from Embodiment 1 only in that all alumina ceramic fibers are replaced with magnesium oxide ceramic fibers.

[0068] Comparative Example 1

[0069] The comparative example of the present application provides an electrode assembly, which is different from Example 1 only in that the diameter of the alumina ceramic fiber is 1 μm and the length of the alumina ceramic fiber is 50 μm.

[0070] Comparative Example 2

[0071] The comparative example of the present application provides an electrode assembly, which differs from Example 1 only in that the diameter of the alumina ceramic fiber is 6 μm and the length of the alumina ceramic fiber is 300 μm.

[0072] Comparative Example 3

[0073] The comparative example of the present application provides an electrode assembly, which differs from comparative example 2 only in that the fiber is PP fiber.

[0074] Test example

[0075] High rate discharge performance test

[0076] Test method:

[0077] The electrode assemblies of Examples 1 to 4 and Comparative Examples 1 to 3 were assembled into cylindrical zinc-nickel batteries according to the existing assembly process of zinc-nickel batteries, wherein the injection volume was 30 g, and then the number of cycles of 1C charging and 5C discharging of each sample at 25° C. was counted, wherein the test steps were: 1C (8A) constant current to a cut-off voltage of 1.9V, then constant voltage charging to a cut-off current of 0.4A, and standing for 1h; then discharging at 5C (40A) to a cut-off voltage of 1V, standing for 3h, corresponding to one charge and discharge cycle, and then counting the number of cycles in which the capacity decayed to 60% of the initial capacity and the total number of effective cycles, and the results were counted in Table 1.

[0078] Table 1

[0079] sample Number of cycles at 60% capacity (times) Effective cycle times Example 1 571 700 Example 2 582 705 Example 3 560 687 Example 4 515 642 Comparative Example 1 475 533 Comparative Example 2 425 482 Comparative Example 3 328 385

[0080] Referring to Table 1, it can be seen from the test results of Examples 1 to 3 and Comparative Examples 1 to 2 that the electrode assembly provided in the embodiments of the present application, specifically, the alumina ceramic fiber with a diameter of 2 to 4 μm and a length of 100 to 200 μm is used in the negative electrode active layer. Compared with alumina ceramic fibers of other sizes, the three-dimensional porous structure formed by the former has a more suitable pore size, which facilitates ion transmission and can effectively inhibit electrode deformation, so that the corresponding battery has a more excellent high-rate discharge performance.

[0081] It can be seen from the test results of Example 1 and Example 4 that the battery using alumina ceramic fibers has better cycle performance than that using other types of ceramic fibers.

[0082] From the test results of Comparative Examples 2 and 3, it can be seen that the use of inorganic ceramic fibers, compared with the use of organic fibers, is more easily wetted by the electrolyte and is more conducive to ion transport, so that the corresponding battery has a better high-rate discharge performance.

[0083] The embodiments described above are part of the embodiments of the present application, rather than all of the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the present application for protection, but merely represents the selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application.

Claims

1. An electrode assembly, characterized in that: It includes a negative electrode sheet, a separator and a positive electrode sheet, wherein the separator is located between the negative electrode sheet and the positive electrode sheet; the negative electrode active layer in the negative electrode sheet includes, by mass percentage: ZnO 45-60%, Zn 15-30%, Bi2O3 1-7%, negative electrode conductive agent 1-7%, ceramic fiber 1.5-10% and auxiliary agent 0.7-15%, wherein the diameter of the ceramic fiber is 2-4μm, and the length of the ceramic fiber is 100-200μm.

2. The electrode assembly according to claim 1, characterized in that: The ceramic fibers include alumina ceramic fibers.

3. The electrode assembly according to claim 1, characterized in that: Calculated by mass percentage, the positive electrode active layer in the positive electrode sheet includes: 87-95% cobalt-coated spherical Ni(OH)2, 1-10% positive electrode conductor and 1-5% rare earth metal oxide, wherein the mass percentage of cobalt in the cobalt-coated spherical Ni(OH)2 is 8-10%.

4. The electrode assembly according to claim 3, characterized in that: The positive electrode active layer further comprises 1-5% of a positive electrode additive, wherein the positive electrode additive comprises metal cobalt and / or cobalt oxide.

5. The electrode assembly according to any one of claims 1 to 4, characterized in that: The thickness of the negative electrode sheet is 0.32-0.34 mm, and the thickness of the positive electrode sheet is 0.3-0.32 mm.

6. The electrode assembly according to claim 5, characterized in that: The area of ​​the negative electrode sheet close to the positive electrode sheet is 0.051 to 0.054 m 2 The area of ​​the positive electrode sheet close to the negative electrode sheet is 0.044 to 0.048 m 2 .

7. The electrode assembly according to any one of claims 1 to 4, characterized in that: The pore size of the diaphragm is 3-4 μm.

8. A zinc-nickel battery, characterized in that: The invention comprises the electrode assembly according to any one of claims 1 to 7.

9. The zinc-nickel battery according to claim 8, characterized in that: The mass of the electrolyte in the zinc-nickel battery is not less than 26 g.

10. An electrical device, characterized in that: Comprising the zinc-nickel battery as claimed in claim 8 or 9.