Button cell

Abstract

The utility model discloses a button cell which comprises a shell, a positive plate, a diaphragm and a negative plate, a battery inner cavity is formed in the shell; the positive plate, the diaphragm and the negative plate are sequentially stacked in the battery inner cavity; the positive plate comprises a positive current collector and a positive active material layer, the positive current collector comprises foamed nickel and a metal foil, the metal foil is arranged on one side surface, far away from the negative plate, of the foamed nickel, and the foamed nickel is coated with the positive active material layer. Therefore, the adhesive force of the positive electrode active material layer on the foamed nickel can be improved, and meanwhile, the positive electrode active material can be effectively prevented from penetrating through the foamed nickel, so that the electric contact between the current collector and the shell is prevented from being influenced; therefore, the positive electrode structure of the button cell and the cell structure can be suitable for cell performance evaluation of the positive electrode active material of the alkaline nickel-zinc cell.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and in particular to a button cell battery. Background Technology

[0002] Button cells are small, high-efficiency energy storage devices characterized by their small size and stable voltage. They are widely used in various portable electronic devices, such as smartwatches, calculators, dictionaries, Bluetooth headsets, smart bracelets, and car keys. The performance of a button cell largely depends on the stability of its internal structure and the effectiveness of the active materials in its positive and negative electrodes. For example, the active material coated on the surface of the positive electrode, a crucial component of the button cell, not only determines the battery's discharge performance but also significantly impacts its cycle life, rate capability, and high / low temperature performance.

[0003] To better design full cells, coin cells are frequently used for evaluating positive electrode materials, negative electrode materials, separators, and electrolytes. For example, the positive electrode materials (lithium cobalt oxide, lithium iron phosphate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, etc.) and negative electrode materials (carbon-based materials, silicon-carbon materials, lithium titanate, tin-based materials, etc.) of lithium-ion batteries can be evaluated for electrochemical performance using standard coin cells (models: CR2016, CR2025, CR2032, etc.). Data obtained from coin cell testing, such as specific capacity, charge-discharge coulombic efficiency, cycle performance, and cycle stability, allows for more rational design of full cells. Because lithium-ion battery electrodes are prepared using a coating process, the electrode thickness is typically thin, with positive electrodes only 80-150 μm and negative electrodes only 60-120 μm. Currently, traditional coin cells can only be used to quickly evaluate battery systems with thin electrodes, but cannot evaluate battery systems with thicker electrodes.

[0004] Alkaline nickel-zinc batteries are an aqueous battery system characterized by high voltage, high energy density, good rate performance, and high safety, and are expected to find widespread application in consumer electronics, power tools, energy storage, medical devices, and transportation. It's worth noting that alkaline nickel-zinc batteries have a voltage exceeding 1.6V, significantly higher than alkaline nickel-metal hydride batteries; their actual energy density can reach up to 120Wh / kg, far exceeding lead-acid batteries (30-40Wh / kg); and their actual discharge power density can exceed 1000W / kg. Even with a high areal density, they can still achieve a discharge rate of ≥20C. For example, a discharge time of approximately 3 minutes can release ≥90% of the battery's rated capacity. Due to the use of an aqueous electrolyte, there are no safety issues such as thermal runaway, making them inherently safe. Typically, alkaline nickel-zinc battery electrodes are fabricated using a slurry drawing process, resulting in electrode thicknesses of 200-600μm, significantly greater than those of lithium-ion battery electrodes. Therefore, the traditional coin cell structure design cannot be used to evaluate the battery performance of alkaline nickel-zinc batteries.

[0005] Currently, the cathode material for alkaline nickel-zinc batteries is spherical nickel hydroxide, which may be doped with trace elements such as Zn, Co, Al, Mg, and Ti. Its surface is usually coated with cobalt compounds to enhance its electron transport performance. However, there are few reports on the electrochemical performance evaluation of alkaline nickel-zinc battery cathode materials. The specific capacity, coulombic efficiency, and cycle performance of the cathode material are crucial for the design of full cells, and their evaluation methods are borrowed from those for alkaline nickel-metal hydride batteries, mainly relying on beaker batteries or half-cell devices. With excess alkaline electrolyte and a large distance between the positive and negative electrodes, it is difficult to accurately reflect the electrochemical performance of the cathode material, especially issues such as gas evolution side reactions and zinc dendrite growth during the charge-discharge process of alkaline nickel-zinc batteries. Therefore, battery performance data obtained from beaker batteries or half-cell devices cannot be applied to the product design of alkaline nickel-zinc batteries.

[0006] Using coin cells for battery material evaluation offers numerous advantages. Their performance data can be directly applied to the design of full-cell batteries, such as cylindrical cells (AAA, AA, SubC, D models) or prismatic cells. The closed-loop environment of a coin cell allows for accurate reflection of the impact of gas evolution side reactions on battery performance. Furthermore, the small distance between the positive and negative electrodes, separated only by a single separator (typically only 100-150 μm thick), accurately reflects the potential for short circuits caused by zinc dendrite growth.

[0007] Traditional coin cell batteries typically consist of a metal current collector and an active material layer. The active material layer is coated on one side of the metal current collector. However, the surface of the metal foil is usually quite smooth, which can lead to poor adhesion of the active material, resulting in problems such as detachment and powdering. Since the positive electrode of alkaline nickel-zinc batteries is typically thick (200-600 μm), metal foil current collectors are not suitable for evaluating the electrochemical performance of positive electrode active materials with high areal density. More importantly, the positive electrode active material in alkaline nickel-zinc batteries is prone to volume expansion during charge and discharge, making it easier for the active material to detach from the surface of the metal current collector. This detachment not only reduces the battery's discharge capacity and charge / discharge efficiency but also poses a risk of internal short circuits, severely impacting the cycle stability and lifespan of alkaline nickel-zinc batteries. Utility Model Content

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a button cell battery that can effectively avoid the problem of positive electrode active material falling off and shedding powder during charging and discharging, thereby effectively improving the adhesion between the positive electrode active material and the current collector.

[0009] The objective of this utility model is achieved through the following technical solution:

[0010] A button cell battery includes: a casing, a positive electrode, a separator, and a negative electrode; a battery cavity is formed on the casing; the positive electrode, the separator, and the negative electrode are stacked sequentially in the battery cavity; the positive electrode includes a positive current collector and a positive active material layer, the positive current collector includes nickel foam and a metal foil, the metal foil is disposed on the side of the nickel foam away from the negative electrode, and the positive active material layer is coated on the nickel foam.

[0011] In one embodiment, the metal foil is a nickel foil.

[0012] In one embodiment, the nickel foam is connected to the metal foil by ultrasonic welding.

[0013] In one embodiment, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer. The negative electrode current collector includes copper foam and a copper sheet. The copper sheet is disposed on the side of the copper foam away from the positive electrode sheet, and the negative electrode active material layer is disposed on the copper foam.

[0014] In one embodiment, the foamed copper is tin-plated foamed copper, and the metal copper sheet is tin-plated copper sheet.

[0015] In one embodiment, the housing includes a positive electrode cover and a negative electrode cover, the positive electrode cover and the negative electrode cover being fastened together to form the battery cavity.

[0016] In one embodiment, the surface of the positive electrode cap is plated with a layer of metallic nickel.

[0017] In one embodiment, the surface of the negative electrode cap is plated with a layer of tin.

[0018] In one embodiment, a spring sheet is further included, the spring sheet being disposed on the side of the positive electrode sheet away from the negative electrode sheet.

[0019] In one embodiment, a tin sheet is further included, which is disposed on the side of the negative electrode away from the positive electrode.

[0020] Compared with the prior art, the present invention has at least the following advantages:

[0021] 1. The coin cell of this invention uses nickel foam and metal foil to form the positive electrode current collector. Utilizing the three-dimensional porous network structure of nickel foam, the adhesion of the positive electrode active material layer to the nickel foam is improved. Simultaneously, a metal foil is placed on the side of the nickel foam away from the negative electrode, effectively preventing the positive electrode active material from penetrating the nickel foam and thus avoiding interference with the electrical contact between the positive electrode current collector and the casing. This not only effectively prevents the active material from detaching and shedding powder, but also effectively prevents the active material from penetrating the nickel foam, thereby avoiding interference with the electrical contact between the positive electrode current collector and the casing. This makes the positive electrode structure and battery structure of the coin cell suitable for evaluating the positive electrode material of alkaline nickel-zinc batteries.

[0022] 2. The button cell of this utility model improves the contact tightness between the electrode and the casing by adding spring plates and gaskets, thereby improving the electrical contact capability between the electrode and the casing and reducing the internal resistance of the button cell.

[0023] 3. The coin cell of this invention can accurately reflect the electrochemical performance of the cathode material in alkaline nickel-zinc batteries, and the measured performance data can be used for the design of alkaline nickel-zinc full cells. Even with a relatively thick electrode, and considering both gas evolution side reactions and zinc dendrite growth, it accurately reflects the specific capacity, charge-discharge coulombic efficiency, and cycle performance of the battery material. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of this utility model, the accompanying drawings used in the embodiments will be briefly described below.

[0025] Figure 1This is a schematic diagram of the structure of a button battery in one embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of the structure of a button battery in another embodiment of the present invention;

[0027] Figure 3 for Figure 1 A schematic diagram of the positive electrode of a coin cell.

[0028] Figure 4 for Figure 1 A schematic diagram of the spring sheet structure of a button cell;

[0029] Figure 5 Battery performance data for evaluating commercial nickel hydroxide cathode materials in a coin cell according to one embodiment of this utility model. Detailed Implementation

[0030] To facilitate understanding of this utility model, a more comprehensive description of this utility model will be given below with reference to the accompanying drawings.

[0031] Please see Figure 1 , Figure 2 and Figure 3 As shown, a button cell 10 includes: a casing 100, a positive electrode 200, a separator 300, and a negative electrode 400; a battery cavity is formed on the casing 100; the positive electrode 200, separator 300, and negative electrode 400 are stacked sequentially within the battery cavity; the positive electrode 200 includes a positive current collector 210 and a positive active material layer 220, the positive current collector 210 includes nickel foam 211 and a metal foil 212, the metal foil 212 is disposed on the side of the nickel foam 211 away from the negative electrode 400, and the positive active material layer 220 is coated on the nickel foam 211. It should be noted that the casing 100 can be made of stainless steel. The positive electrode 200 contains nickel hydroxide, nickel powder, binder, thickener, and other substances. The nickel hydroxide can have a spherical structure and can be doped with elements such as cobalt, zinc, titanium, magnesium, and aluminum; the surface of the nickel hydroxide can be coated with a cobalt compound. The separator is a porous polyethylene or polypropylene plastic film with a surface treated with hydrophilic agents such as sulfonation or grafting, and its thickness ranges from 100-250 μm. The negative electrode 400 contains nano zinc oxide, metallic zinc powder, nano bismuth oxide, conductive additives, binders, thickeners, and other substances.

[0032] It should be noted that by combining nickel foam 211 and metal foil 212 to form a positive electrode current collector 210, the three-dimensional porous network structure of the nickel foam 211 can enhance the adhesion of the positive electrode active material layer 220 to the positive electrode current collector 210, effectively preventing problems such as active material detachment during charging and discharging. Furthermore, for alkaline nickel-zinc batteries, since their electrolyte contains substances such as sodium hydroxide, potassium hydroxide, and lithium hydroxide, with a hydroxide ion concentration of 6-12 mol / L, the electrolyte of alkaline nickel-zinc batteries is alkaline, and the alkaline electrolyte is mainly stored in a separator 300 with liquid absorption and anti-dendrying capabilities. The separator 300 can be made of polyethylene or polypropylene plastic film. To enhance the wettability of the alkaline electrolyte, the separator 300 needs to undergo sulfonation or grafting treatment, giving it strong electrolyte absorption capacity and the ability to prevent zinc dendrite puncture. Meanwhile, the nickel foam 211 not only facilitates the loading of active materials but also improves the penetration and electron transport capabilities of the alkaline electrolyte, thus further enhancing the performance of the alkaline nickel-zinc battery. Furthermore, the positive electrode active material layer 220 is generally coated on the side of the nickel foam 211 away from the metal foil 212, but the nickel foam 211... The porous structure of electrode 11 makes it easy for the positive electrode active material layer 220 to penetrate through the nickel foam 211 to the back side of the nickel foam 211, thus affecting the electrical contact between the positive electrode current collector 210 and the casing 100. Therefore, by placing a metal foil 212 on the side of the nickel foam 211 away from the negative electrode 400, the metal foil 212 prevents the positive electrode active material layer 220 from penetrating through the nickel foam 211 and contacting the casing 100, thereby ensuring good electrical contact between the casing 100 and the positive electrode 200. Thus, by using the positive electrode 200 structure of this invention, the electrochemical performance of the positive electrode active material can be rapidly evaluated in a coin-type alkaline nickel-zinc battery, considering gas evolution side reactions and zinc dendrite growth, without relying on a beaker battery or half-cell device, improving the effectiveness of performance evaluation of alkaline nickel-zinc battery positive electrode materials. In this embodiment, the areal density of the nickel foam 211 is 150-320 g / m³. 2 For the design of high-capacity alkaline nickel-zinc batteries, foamed nickel 211 can use a lower areal density of 150-250 g / m³. 2 For the design of power-type (also known as rate-type) alkaline nickel-zinc batteries, foamed nickel 211 can use a higher areal density of 250-320 g / m³. 2 .

[0033] Preferably, the metal foil 212 is a nickel foil. Nickel foil not only possesses excellent electrical conductivity but also exhibits good corrosion resistance in alkaline electrolyte environments. Using nickel foil greatly ensures the charge-discharge performance of alkaline nickel-zinc batteries and also helps improve their cycle stability, lifespan, and reliability.

[0034] Preferably, the nickel foam 211 and the metal foil 212 are joined by ultrasonic welding. Ultrasonic welding does not require preheating and cooling processes, thus avoiding the generation of high temperatures that traditional welding can cause to the nickel foam 211 and the metal foil 212. Furthermore, it ensures the tightness and strength of the weld between the nickel foam 211 and the metal foil 212, thereby ensuring the conductivity of the positive current collector 210. Preferably, the thickness of the metal foil is 5-30 μm.

[0035] In one embodiment, the negative electrode 400 includes a negative electrode current collector 410 and a negative electrode active material layer 420. The negative electrode current collector 410 includes a copper foam 411 and a copper sheet 412. The copper sheet 412 is disposed on the side of the copper foam 411 away from the positive electrode 200, and the negative electrode active material layer 420 is disposed on the copper foam 411.

[0036] It should be noted that by setting the negative electrode 400 to a structure similar to that of the positive electrode 200, the adhesion of the negative electrode active material layer 420 to the negative electrode current collector 410 can be ensured, thereby preventing problems such as the negative electrode active material layer 420 falling off. Specifically, foamed copper 411 and metallic copper sheet 412 are combined to form a negative electrode current collector 410. The properties of foamed copper 411 can enhance the adhesion of the active material to the negative electrode current collector 410, reducing the risk of the negative electrode active material falling off. At the same time, the metallic copper sheet 412 prevents the negative electrode active material layer 420 from penetrating the foamed copper 411, so as not to affect the electrical contact effect between the negative electrode 400 and the housing 100. Among them, the foam copper 411 is tin-plated foam copper 411, that is, tin is plated on the surface of the foam copper 411. The thickness of the tin plating layer can be 1-5μm, which can improve the corrosion resistance and stability of the foam copper 411 in the alkaline environment. Similarly, the metal copper sheet 412 is preferably a tin-plated copper sheet. By plating a layer of tin on the surface of the copper sheet, the thickness of the tin plating layer can be 1-5μm. This can effectively prevent the negative electrode active material layer 420 from directly contacting the copper sheet, thereby suppressing the hydrogen evolution side reaction and improving the charge and discharge efficiency, cycle life and stability of the alkaline nickel-zinc battery.

[0037] In one embodiment, the casing 100 specifically includes a positive electrode cover 110 and a negative electrode cover 120, which are fastened together to form the battery cavity. The positive electrode cover 110 contacts the positive electrode plate 200 for electrical connection, and the negative electrode cover 120 contacts the negative electrode plate 400 for electrical connection. Both the positive electrode cover 110 and the negative electrode cover 120 are made of stainless steel. In this embodiment, the surface of the positive electrode cover 110 is plated with a nickel layer, the thickness of which can be 1-5 μm. This not only further improves the corrosion resistance of the positive electrode cover 110 but also further improves the electrochemical stability of the alkaline nickel-zinc battery during charge and discharge. Similarly, the surface of the negative electrode cover 120 is plated with a tin layer, the thickness of which can be 1-5 μm. This suppresses hydrogen evolution side reactions, thereby helping to improve the overall performance of the alkaline nickel-zinc battery.

[0038] To further improve the contact tightness between the positive electrode 200 and the positive electrode cap 110, and between the negative electrode 400 and the negative electrode cap 120, and to improve the electrical contact performance between the electrode and the casing 100, thereby reducing the internal resistance of the coin cell 10, in one embodiment, the coin cell 10 further includes a spring sheet 500 disposed on the side of the positive electrode 200 away from the negative electrode 400. The spring sheet 500 enhances the electrical contact performance between the electrode and the casing 100. See also... Figure 4 As shown, the cross-sectional view of the spring sheet 500 has an arched structure, thus forming an elastic structure to enhance electrical contact performance. In this embodiment, a nickel plating layer is provided on the surface of the spring sheet 500, wherein the thickness of the nickel plating layer can be 1-5 μm, thereby improving the corrosion resistance of the spring sheet 500 and thus increasing its service life.

[0039] Please see Figure 2 As shown, in one embodiment, the button cell 10 further includes a tin sheet 600, which is disposed on the side of the negative electrode 400 away from the positive electrode 200. The thickness of the tin sheet 600 can be 0.1-0.7 mm. Metallic tin, as a stable material with good conductivity and corrosion resistance, can further optimize electron transport capabilities and prevent gas evolution side reactions by adding the tin sheet 600 between the negative electrode 400 and the negative electrode cap 120, thereby further improving the charge-discharge coulombic efficiency, cycle life, and stability of the alkaline nickel-zinc battery.

[0040] Please see Figure 2As shown, in one embodiment, the button cell 10 further includes a gasket 700, which is disposed between the spring sheet 500 and the positive electrode 200. Thus, by adding a gasket 700 between the spring sheet 500 and the positive electrode 200, not only can the tightness of the contact between the electrode and the housing 100 be further ensured, but it also acts as a buffer and protects the electrode, thereby preventing the positive electrode 200 from deforming or being damaged under the pressure of the spring sheet 500, ensuring the stability and service life of the positive electrode 200. In this embodiment, the surface of the gasket 700 is plated with a layer of metallic nickel, wherein the thickness of the nickel plating layer can be 1-5 μm. The metallic nickel plating layer effectively improves the corrosion resistance of the gasket 700, thereby increasing its service life.

[0041] The specific capacity, charge-discharge coulombic efficiency, and cycle performance of battery materials are crucial for the design of full cells (e.g., cylindrical and prismatic cells). To verify the effectiveness of coin cell evaluation of alkaline nickel-zinc battery cathode materials, two commercially available nickel hydroxide cathode materials were selected as active materials for charge-discharge testing. Figure 5 Battery performance data for evaluating a commercial nickel hydroxide cathode material in a coin cell according to one embodiment of this utility model. From Figure 5 As can be seen, the nickel hydroxide cathode material provided by Company A is significantly superior to that provided by Company B. Specifically, the initial specific capacity of the nickel hydroxide cathode material provided by Company A is 260 mAh / g, and the initial charge-discharge coulombic efficiency is ~95%. After 50 cycles, the specific capacity remains at 221 mAh / g, the charge-discharge coulombic efficiency is ~96%, and the corresponding discharge capacity retention rate is 85%. The initial specific capacity of the nickel hydroxide cathode material provided by Company B is 232 mAh / g, and the initial charge-discharge coulombic efficiency is ~96%. After 50 cycles, the specific capacity remains at 159 mAh / g, the charge-discharge coulombic efficiency is ~98%, but the corresponding discharge capacity retention rate is only 68%. The higher the specific capacity of the nickel hydroxide cathode material, the higher the energy density of the battery; the higher the discharge capacity retention rate, the slower the performance degradation of the alkaline nickel-zinc battery. For alkaline nickel-zinc batteries, since the actual capacity of the negative electrode is much higher than that of the positive electrode, it is evident that the discharge capacity of alkaline nickel-zinc batteries is mainly limited by the capacity of the positive electrode. Therefore, the button cell of this invention can conveniently, accurately, and realistically reflect the electrochemical performance of the positive electrode active material, facilitating reasonable full cell design.

[0042] The embodiments described above are merely illustrative of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A button cell, characterized by, The application relates to a battery, which comprises a shell, a positive electrode sheet, a diaphragm and a negative electrode sheet. The shell is provided with a battery cavity. The positive electrode sheet, the diaphragm and the negative electrode sheet are sequentially stacked in the battery cavity. The positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer, the positive electrode current collector comprises foamed nickel and a metal foil, the metal foil is arranged on a side of the foamed nickel far away from the negative electrode sheet, and the positive electrode active material layer is coated on the foamed nickel. The metal foil is a metal nickel foil.

2. The button cell of claim 1, wherein, The foamed nickel and the metal foil are connected through ultrasonic welding.

3. The button cell of claim 1, wherein, The negative electrode sheet comprises a negative electrode current collector and a negative electrode active material layer, the negative electrode current collector comprises foamed copper and a metal copper foil, the metal copper foil is arranged on a side of the foamed copper far away from the positive electrode sheet, and the negative electrode active material layer is arranged on the foamed copper.

4. The button cell of claim 1, wherein, The foamed copper is plated foamed copper, and the metal copper foil is plated copper foil.

5. The button cell of claim 4, wherein, The shell comprises a positive electrode cover and a negative electrode cover, the positive electrode cover and the negative electrode cover are connected through buckling to form the battery cavity.

6. The button cell of claim 1, wherein, The surface of the positive electrode cover is plated with a metal nickel layer.

7. The button cell of claim 6, wherein, The surface of the negative electrode cover is plated with a metal tin layer.

8. The button cell of claim 6, wherein, The battery further comprises a spring sheet arranged on a side of the positive electrode sheet far away from the negative electrode sheet.

9. The button cell battery of any of claims 1-8, wherein, The battery further comprises a tin sheet arranged on a side of the negative electrode sheet far away from the positive electrode sheet.

10. The button cell battery of any of claims 1-8, wherein, ​

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