A negative electrode symmetrically placed button cell and its assembling method

Abstract

The application relates to a negative electrode symmetrically placed button cell and an assembling method thereof, in particular to placing two thick electrodes with a certain thickness back to back, wherein a metal current collector with a tab is clamped; placing a diaphragm and a negative electrode on the two sides of the thick positive electrode in sequence, the two negative electrodes are bridged by a metal foil, a piece of insulating film is placed between the negative electrode on one side and the button cell shell, and the positive electrode tab is bent to the space between the insulating film and the button cell shell; the diffusion path of ions in the thick electrode can be shortened through the setting mode, and the battery performance and material utilization rate are improved.

Description

Technical Field

[0001] This invention relates to the field of batteries, and more specifically to a coin cell with symmetrically placed negative electrodes and its assembly method. Background Technology

[0002] For coin cells, their size is limited, and how to increase the capacity within this limited space has become a key issue for their further development. To maximize capacity within a limited volume, commercially available coin cells have opted to thicken the electrodes, which improves the utilization of internal space. However, the problem with ultra-thick electrodes is that the ion diffusion path becomes longer, leading to a decrease in the rate performance of this type of coin cell and rapid capacity decay in scenarios requiring high output.

[0003] To adapt to high-output scenarios, some primary batteries have opted to modify their internal structure, thinning ultra-thick electrodes and changing the cell configuration to a wound type, as described in patent document CN113809486B, or a folded type, as described in patent document CN108461820B. There are also solutions that stack multiple layers of thin electrodes to form a cell. This electrode stacking method makes full use of space and can improve the battery's rate performance to some extent. For example, patent document CN116722277A discloses a coin cell solution with a multi-electrode stacked cell, which mainly involves stacking circular negative and positive electrodes in an alternating manner. This allows the positive and negative electrodes to fit into the vertical space inside the cylindrical metal shell after stacking and assembly. The circular positive and negative electrodes fully utilize the horizontal and vertical space inside the cylindrical metal shell, thereby maximizing the energy density of the coin cell within limited installation space.

[0004] However, compared to simply using ultra-thick electrodes, the winding and stacking of cells with appropriately thinned electrodes still result in a loss of active material in the vertical direction, leading to a decrease in capacity. Therefore, in the field of coin cell construction, a new approach is still needed to improve capacity while maintaining rate performance. Summary of the Invention

[0005] This invention provides a novel structure for a coin cell that fully utilizes the internal space of the coin cell, increases capacity, and shortens the ion diffusion path to a certain extent, thereby improving the rate performance of the battery.

[0006] To achieve the above effects, the present invention provides a button cell battery, which includes a casing and cells symmetrically arranged with a negative electrode.

[0007] The housing includes a positive electrode housing and a negative electrode housing;

[0008] The positive electrode of the battery cell is a thick electrode with active material on both sides and tabs.

[0009] The battery cell has two sets of negative electrodes, symmetrically placed on both sides of the positive electrode set. The positive and negative electrodes are separated by a diaphragm, and the two sets of negative electrodes are connected by a negative electrode bridge.

[0010] The negative electrode on the negative electrode shell side of the battery cell is directly electrically connected to the negative electrode shell.

[0011] An insulating film is placed between the negative electrode on the positive side of the cell and the positive electrode shell of the button cell. The positive electrode tab is electrically connected to the positive electrode shell of the battery. The insulating film insulates and separates the negative electrode from the positive electrode tab and the positive electrode shell.

[0012] Furthermore, the thick electrode is composed of single-sided coated thick electrodes placed back-to-back on both sides of a metal sheet with tabs, or it is prepared by coating thick electrodes on both sides of a metal sheet, metal mesh, or metal foil with tabs.

[0013] Furthermore, the negative electrode bridge is a metal foil or a thin metal sheet.

[0014] Furthermore, the thickness of the thick electrode is between 200µm and 2000µm.

[0015] Furthermore, the electrodes of the thick electrode are placed on both sides of the metal sheet with tabs, forming a "positive electrode|metal sheet|positive electrode" structure.

[0016] Furthermore, the insulating film is larger than the diameter of the positive and negative electrodes, and its thickness is 20µm to 100µm.

[0017] Furthermore, the tab is bent to one side of the insulating film and makes contact with the positive electrode shell to conduct electricity.

[0018] Furthermore, the negative electrode is one of a lithium metal sheet, a sodium metal sheet, or a potassium metal sheet.

[0019] Furthermore, the positive electrode active material is composed of one or more of the following: carbon fluoride, manganese dioxide, silver oxide, silver vanadate, sulfur, and chromium oxide.

[0020] This invention provides a method for assembling a button cell battery as described above, comprising the following steps:

[0021] Place the insulating sheet at the bottom of the positive electrode casing of the battery;

[0022] The negative electrode, diaphragm, positive electrode with tabs, diaphragm, and negative electrode are stacked sequentially on the insulating sheet to form a multi-layer structure.

[0023] A negative electrode bridge is placed on one side of the multilayer structure to connect the two sets of negative electrodes. On the other side of the multilayer structure, the tab of the positive electrode is bent to the side of the insulating film to make contact with the positive electrode shell and conduct electricity.

[0024] The battery negative electrode casing is placed on the multi-layer structure to complete battery assembly.

[0025] The beneficial effects of this invention are:

[0026] (1) By adopting a cell structure with symmetrical placement of the negative electrode and a thick electrode design, the limited space inside the coin cell is fully utilized. The thick electrode can accommodate more active materials, thereby increasing the energy storage capacity of the battery. Compared with the traditional coin cell configuration, a higher capacity output can be achieved with the same battery volume. The reasonable structural design and electrode configuration enable the materials inside the battery to participate more fully in the electrochemical reaction, reducing material waste, improving material utilization, reducing production costs, and also helping to reduce the potential environmental impact of battery waste.

[0027] (2) The unique symmetrical layout of the negative electrode allows ions to diffuse simultaneously from both sides into the positive electrode during the reaction, effectively shortening the diffusion path of ions within the thick electrode compared to traditional unipolar or asymmetric structures. This improvement significantly enhances the rate performance of the battery, reduces rapid capacity decay in high-output scenarios, ensures stable power supply, and improves the battery's charging and discharging efficiency and response speed. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0029] Figure 1 This is a schematic diagram of the button cell structure provided in Example 1;

[0030] Figure 2 This is a schematic diagram of the button cell structure provided in Example 2;

[0031] Figure 3 The discharge curve of the button cell provided in Example 1;

[0032] Figure 4 The discharge curve of the button cell provided in Example 2;

[0033] Figure 5 The discharge curve of the coin cell provided for Comparative Example 1;

[0034] Figure 6 The discharge curve of the coin cell provided for Comparative Example 2; Detailed Implementation

[0035] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0036] It should be understood that, when used in this specification and the appended claims, the term "comprising" indicates the presence of a descriptive feature, integral, step, operation, element, and / or component, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or sets.

[0037] To keep the drawings concise, only the parts relevant to the invention are shown schematically in each figure, and they do not represent the actual structure of the product. Furthermore, for ease of understanding, in some figures, only one of components with the same structure or function is shown schematically, or only one is labeled. In this document, "one" can mean not only "only one" but also "more than one".

[0038] It should also be further understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0039] In the embodiments shown in the accompanying drawings, the directional indications (such as up, down, left, right, front, and back) used to explain the structure and movement of the various components of the invention are relative rather than absolute. These descriptions are appropriate when these components are in the positions shown in the drawings. If the descriptions of the positions of these components change, these directional indications also change accordingly.

[0040] Furthermore, in the description of this application, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without any creative effort.

[0042] Example 1

[0043] refer to Figure 1As shown, this invention provides a button cell battery, which consists of a positive and negative electrode casing and a cell. The battery casing is made of conventional CR2032 aluminum alloy; the cell consists of a positive electrode, an aluminum sheet, a separator, a lithium metal sheet, a thin copper strip, an electrolyte, and an insulating sheet. The positive electrode is a fluorinated carbon electrode with a thickness of 1400µm to 1500µm and a diameter of 1cm. The aluminum sheet is 200µm thick, and a short section of 25µm thick aluminum foil is welded onto the aluminum sheet as a tab. The separator is a PP separator, the thin copper strip is cut from 15µm thick copper foil and serves as the negative electrode bridge, and the insulating sheet is a PE film.

[0044] During assembly, the thick positive electrode is first immersed in the electrolyte, and then assembled according to... Figure 1 The structure shown is assembled sequentially from bottom to top. It should be noted that the positive electrode tab aluminum foil and the negative electrode bridge are placed separately on both sides of the cell to avoid short circuits. When bending, the positive and negative electrodes should also be kept away from short circuits.

[0045] Example 2

[0046] refer to Figure 2 As shown, the difference between this embodiment and Embodiment 1 is that the positive electrode used is a thick electrode with tabs coated on both sides, with a size of 0.8 × 0.9 cm. The mass of active material per unit area of ​​the coating is about twice that of Embodiment 1. Its function is the same as that of the positive electrode group with a single-sided coated thick electrode placed back to back on both sides of the tab metal sheet.

[0047] During assembly, the thick positive electrode is first immersed in the electrolyte, and then assembled according to... Figure 2 The structure shown is assembled sequentially from bottom to top. It should be noted that the positive electrode tab aluminum foil and the negative electrode bridge are placed separately on both sides of the cell to avoid short circuits. When bending, the positive and negative electrodes should also be kept away from short circuits.

[0048] Comparative Example 1

[0049] This reference example uses the same single-layer coated thick electrode as Example 1, except that only one thick electrode is used and the configuration described in this invention is not used. It is packaged into the CR2032 button cell in the traditional order of positive electrode, separator, lithium sheet, gasket, and spring sheet.

[0050] Comparative Example 2

[0051] This reference example uses a thick electrode similar to that of Example 1, except that its active material loading per unit area is twice that of the thick electrode of Example 1. It is packaged into a CR2032 coin cell in the traditional order of positive electrode, separator, lithium sheet, gasket, and spring sheet.

[0052] Implementation effect

[0053] As can be seen, Examples 1 and 2, when discharged at the same current density as Comparative Example 1, exhibit twice the capacity, demonstrating that the present invention effectively utilizes the internal space of the coin cell casing to increase battery capacity. Comparing Examples 1 and 2 with Comparative Example 2, the areal specific capacity provided by Examples 1 and 2 is 204.2 mAh / cm². 2 208.5mAh / cm 2 The comparative example 2 had a capacity of only 146.6 mAh / cm³. 2 It can be seen that, at the same current density, the rate performance of a traditional battery configuration using a single ultra-thick electrode is inferior to that of this invention. This demonstrates that by employing a symmetrically placed negative electrode cell structure and a thick electrode design, the limited internal space of the coin cell is fully utilized. The thick electrode can accommodate more active material, thereby increasing the battery's energy storage capacity. Compared to traditional coin cell configurations, a higher capacity output can be achieved within the same battery volume. The unique symmetrical negative electrode layout allows ions to diffuse simultaneously from both sides into the positive electrode during the reaction, effectively shortening the diffusion path of ions within the thick electrode compared to traditional unipolar or asymmetrical structures. This improvement significantly enhances the battery's rate performance, reducing rapid capacity decay in high-output scenarios, ensuring stable power supply, and improving the battery's charge / discharge efficiency and response speed.

[0054] Table 1 Battery discharge data between different examples

[0055]

[0056] The above embodiments merely illustrate implementation methods of the present invention and are only used to help understand the method and core ideas of the present invention. For those skilled in the art, any changes to the specific implementation methods and application scope based on the ideas of the present invention fall within the scope of disclosure and protection of the present invention.

Claims

1. A button cell battery, characterized in that, The button cell includes a casing and cells symmetrically arranged with a negative electrode. The housing includes a positive electrode housing and a negative electrode housing; The positive electrode of the battery cell is a set of thick electrodes with active materials on both sides and tabs. The battery cell has two sets of negative electrodes, symmetrically placed on both sides of the positive electrode set. The positive and negative electrodes are separated by a diaphragm, and the two sets of negative electrodes are connected by a negative electrode bridge. The negative electrode on the negative electrode shell side of the battery cell is directly electrically connected to the negative electrode shell. An insulating film is placed between the negative electrode on the positive electrode shell side of the cell and the positive electrode shell. The positive electrode tab is electrically connected to the positive electrode shell of the battery. The insulating film insulates and separates the negative electrode and the positive electrode tab from the positive electrode shell. The thick electrode is composed of a single-sided coated active material placed back to back on both sides of a metal sheet with tabs, or it is prepared by coating active material on both sides of a metal sheet, metal mesh, or metal foil with tabs.

2. The button cell battery according to claim 1, characterized in that, The negative electrode bridge is a thin metal sheet.

3. The button cell battery according to claim 1, characterized in that, The negative electrode bridge is a metal foil.

4. The button cell battery according to claim 1, characterized in that, The thickness of the thick electrode is between 200µm and 2000µm.

5. The button cell battery according to claim 1, characterized in that, The electrodes of the thick electrode are placed on both sides of the metal sheet with tabs, forming a "positive electrode|metal sheet|positive electrode" structure.

6. The button cell battery according to claim 1, characterized in that, The insulating film is larger than the diameter of the positive and negative electrodes, and its thickness is 20µm to 100µm.

7. The button cell battery according to claim 1, characterized in that, The tab is bent to one side of the insulating film and makes contact with the positive electrode shell to conduct electricity.

8. The button cell battery according to claim 1, characterized in that, The negative electrode is one of a lithium metal sheet, a sodium metal sheet, or a potassium metal sheet.

9. The button cell battery according to claim 1, characterized in that, The positive electrode active material is composed of one or more of the following: carbon fluoride, manganese dioxide, silver oxide, silver vanadate, sulfur, and chromium oxide.

10. A method for assembling a button cell as described in any one of claims 1-9, characterized in that, Includes the following steps: Place the insulating sheet at the bottom of the positive electrode casing of the battery; The negative electrode, diaphragm, positive electrode with tabs, diaphragm, and negative electrode are stacked sequentially on the insulating sheet to form a multi-layer structure. A negative electrode bridge is placed on one side of the multilayer structure to connect the two sets of negative electrodes. On the other side of the multilayer structure, the tab of the positive electrode is bent to the side of the insulating film to make contact with the positive electrode shell and conduct electricity. The battery negative electrode casing is placed on the multi-layer structure to complete battery assembly.

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