Button cell with symmetrically placed negative electrodes and assembly method thereof

Abstract

The invention relates to a button cell with symmetrically placed cathodes and an assembling method thereof, and the assembling method is characterized in that two thick anodes with certain thickness are placed back to back, and a metal current collector with a tab is clamped between the two thick anodes; diaphragms and negative electrodes are sequentially arranged on two sides of the thick positive electrode, the two negative electrodes are bridged by using a metal foil, an insulating film is arranged between the negative electrode on one side and a button cell shell, and a positive electrode lug is bent between the insulating film and the cell shell; through the arrangement mode, the diffusion path of ions in the thick electrode can be shortened, and the battery performance and the material utilization rate are improved.

Description

Technical Field

[0001] The invention relates to the field of batteries, and in particular to a button-type battery with symmetrically placed negative electrodes and an assembling method thereof. Background Art

[0002] For button batteries, their volume is limited, and how to increase the battery capacity within the limited volume has become a problem for the further development of button batteries. In order to increase the battery capacity as much as possible within the limited volume, commercialized button batteries choose to thicken the electrodes, which can improve the internal space utilization of the battery; however, one problem caused by the ultra-thick electrodes is that the ion diffusion path becomes longer, resulting in poor rate performance of this type of button battery, and rapid capacity decay in scenarios that require high output.

[0003] In order to adapt to high-output scenarios, some primary batteries choose to change the internal structure of the battery, thin the ultra-thick electrodes, and change the cell configuration to a winding type, such as the technical solution described in patent document CN113809486B, or a folding type, such as the technical solution described in patent document CN108461820B. There is also a solution of stacking multiple layers of thin electrodes into a cell, which makes full use of space by stacking electrodes and can improve the battery rate performance to a certain extent. For example, patent document CN116722277A discloses a button battery solution for multi-electrode stacked cells, which mainly stacks circular negative electrode sheets and circular positive electrode sheets in an interlaced manner, so that the positive and negative electrode sheets can correspond to the space inside the cylindrical metal shell in the vertical direction after stacking and assembling; the setting of the circular positive and negative electrode sheets makes full use of the space inside the cylindrical metal shell in the horizontal and vertical directions, thereby maximizing the energy density of the button battery under limited installation space.

[0004] However, compared with the pure ultra-thick electrode solution, the wound cell and stacked cell solutions with appropriately thinned electrode thickness still lose a lot of active materials in the vertical direction, resulting in a decrease in capacity. Therefore, in the field of button cell construction, a new solution is still needed to increase capacity while taking into account rate performance. Summary of the invention

[0005] The present invention provides a new button battery structure, which can fully utilize the internal space of the button battery and improve the capacity, and at the same time can shorten the ion diffusion path to a certain extent and improve the battery rate performance.

[0006] In order to achieve the above effect, the present invention provides a button-type battery, which includes a shell and a battery cell with a negative electrode symmetrically placed. The shell includes a positive electrode shell and a negative electrode shell; The positive electrode of the battery cell is a thick electrode with active materials on both sides and tabs; The negative electrode of the battery cell is divided into two groups, which are symmetrically placed on both sides of the positive electrode group. The positive and negative electrodes are separated by a separator, and the two groups of negative electrodes are conductively bridged by a negative electrode bridge. The negative electrode on the negative electrode shell side of the battery cell is directly conductively connected to the negative electrode shell; An insulating film is placed between the negative electrode on the positive electrode shell side of the battery cell and the button-type battery positive electrode shell, the positive electrode tab is conductively connected to the battery positive electrode shell, and the insulating film insulates and separates the negative electrode and positive electrode tab from the positive electrode shell. Furthermore, the thick electrode is composed of single-sidedly coated thick electrodes placed back-to-back on both sides of a metal sheet with a tab, or is prepared by coating thick electrodes on both sides of a metal sheet, metal mesh, or metal foil with a tab.

[0007] Furthermore, the negative electrode bridge is a metal foil or a metal sheet.

[0008] Furthermore, the thickness of the thick electrode is between 200µm and 2000µm.

[0009] Furthermore, the thick electrodes are placed on both sides of the metal sheet with the tabs to form a "positive electrode|metal sheet|positive electrode" structure.

[0010] Furthermore, the size of the insulating film is larger than the diameter of the positive and negative electrodes, and the thickness is 20µm to 100µm.

[0011] Furthermore, the tab is bent to one side of the insulating film and is in contact and conduction with the positive electrode shell.

[0012] Furthermore, the negative electrode is one of a metal lithium sheet, a metal sodium sheet, and a metal potassium sheet.

[0013] Furthermore, the positive electrode active material is composed of one or more of carbon fluoride, manganese dioxide, silver oxide, silver vanadate, sulfur, and chromium oxide.

[0014] The present invention provides an assembly method of the button battery as described above, comprising the following steps: Place the insulating sheet at the bottom of the battery positive electrode shell; The negative electrode, the separator, the positive electrode with the tab, the separator, and the negative electrode are sequentially stacked 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 groups of negative electrodes electrically, and on the other side of the multilayer structure, the tab of the positive electrode is bent to one side of the insulating film to contact and conduct with the positive electrode shell; Cover the battery negative electrode shell on the multilayer structure to complete the battery assembly.

[0015] Beneficial effects of the present invention: (1) By adopting a cell structure with symmetrically placed negative electrodes and a thick electrode design, the limited space inside the button 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 button cell configuration, a higher capacity output can be achieved under the same battery volume. 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, and reducing production costs. It also helps to reduce the potential impact of battery waste on the environment.

[0016] (2) The unique symmetrical layout of the negative electrode enables ions to diffuse from both sides to the positive electrode during the reaction, effectively shortening the diffusion path of ions in the thick electrode compared to the traditional single-pole or asymmetric structure. This improvement significantly improves the rate performance of the battery. In high-output scenarios, it can reduce the rapid attenuation of capacity, ensure the stable power supply capability of the battery, and improve the battery's charge and discharge efficiency and response speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings: Figure 1 A schematic diagram of the button battery structure provided in Example 1; Figure 2 A schematic diagram of the button battery structure provided in Example 2; Figure 3 A discharge curve diagram of a button cell provided in Example 1; Figure 4 A discharge curve diagram of a button cell provided in Example 2; Figure 5 A discharge curve diagram of a button cell provided for comparative example 1; Figure 6 A discharge curve diagram of a button cell provided for comparative example 2; DETAILED DESCRIPTION The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0018] It should be understood that when used in this specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or collections.

[0019] In order to simplify the drawings, only the parts related to the present invention are schematically shown in each figure, and they do not represent the actual structure of the product. In addition, in order to simplify the drawings and facilitate understanding, in some figures, only one of the parts with the same structure or function is schematically drawn or marked. In this article, "one" not only means "only one", but also means "more than one".

[0020] It should be further understood that the term “and / or” used in the specification and appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0021] In the embodiments shown in the drawings, the indications of directions (such as up, down, left, right, front and back) used to explain the structure and movement of the various components of the present invention are not absolute but relative. 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, the indications of these directions also change accordingly.

[0022] In addition, in the description of the present application, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings and other implementation methods can be obtained based on these drawings without creative work.

[0024] Example 1 refer to Figure 1 As shown, the present invention provides a button battery, which is composed of a positive and negative electrode shell and a battery cell. The battery shell is a conventional CR2032; and the battery cell is composed of a positive electrode, an aluminum sheet, a diaphragm, a metal lithium sheet, a thin copper strip, an electrolyte and an insulating sheet. Among them, the positive electrode is a fluorinated carbon thick electrode with a thickness of 1400µm to 1500µm and a diameter of 1cm. The thickness of the aluminum sheet is 200µm, and a small section of 25µm thick aluminum foil is welded on the aluminum sheet as a pole ear. The diaphragm adopts a PP diaphragm, and the thin copper strip is cut from a 15µm thick copper foil and used as a negative electrode bridge, and the insulating sheet is a PE film.

[0025] During assembly, the thick positive electrode is first soaked in electrolyte, and then Figure 1The structure shown is assembled from bottom to top in sequence; it should be noted that the positive electrode tab aluminum foil and the negative electrode bridge are placed separately on both sides of the battery cell to avoid touching and short circuiting, and the positive and negative electrodes should also be prevented from touching and short circuiting when bending.

[0026] Example 2 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, its size is 0.8×0.9 cm, and the mass of active material per unit area coated is about twice that of embodiment 1. Its efficacy is the same as that of the positive electrode group in which the thick electrodes coated on one side are placed back to back on both sides of the metal sheets with tabs.

[0027] During assembly, the thick positive electrode is first soaked in electrolyte, and then Figure 2 The structure shown is assembled from bottom to top in sequence; it should be noted that the positive electrode tab aluminum foil and the negative electrode bridge are placed separately on both sides of the battery cell to avoid touching and short circuiting, and the positive and negative electrodes should also be prevented from touching and short circuiting when bending.

[0028] Comparative Example 1 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 the present invention is not used. The positive electrode, separator, lithium sheet, gasket and spring are packaged in a CR2032 button battery shell in the traditional order.

[0029] Comparative Example 2 This reference example uses a thick electrode similar to that of Example 1, except that the active material loading per unit area is twice that of the thick electrode of Example 1. It is packaged into a CR2032 button battery in the order of a traditional positive electrode, a separator, a lithium sheet, a gasket, and a spring.

[0030] Implementation Effect It can be seen that when Examples 1 and 2 are discharged at the same current density as Comparative Example 1, the capacity is twice that of Comparative Example 1, proving that the present invention can effectively utilize the internal space of the button battery shell and increase the capacity of the battery. By comparing Examples 1 and 2 with Comparative Example 2, the area specific capacity provided by Examples 1 and 2 is 204.2 mAh / cm 2 、208.5mAh / cm 2 , while the comparative example 2 is only 146.6 mAh / cm 2It can be seen that under the same current density, the rate of the traditional battery configuration using a single ultra-thick electrode is inferior to that of the present invention. It can be seen that by adopting a cell structure with symmetrically placed negative electrodes and a thick electrode design, the limited space inside the button battery is fully utilized. The thick electrode can accommodate more active substances, thereby increasing the energy storage capacity of the battery. Compared with the traditional button battery configuration, a higher capacity output can be achieved under the same battery volume. The unique symmetrical layout of the negative electrode allows ions to diffuse from both sides to the inside of the positive electrode at the same time during the reaction, which effectively shortens the diffusion path of ions in the thick electrode compared to the traditional single-pole or asymmetric structure. This improvement significantly improves the rate performance of the battery. In high-output scenarios, it can reduce the rapid attenuation of capacity, ensure the stable power supply capacity of the battery, and improve the charging and discharging efficiency and response speed of the battery.

[0031] Table 1 Battery discharge data between different examples

[0032] The above embodiments only represent the implementation mode of the present invention, which is only used to help understand the method of the present invention and its core idea. For those skilled in the art, according to the idea of ​​the present invention, the changes in the specific implementation mode and the scope of application all belong to the disclosure scope and protection scope of the present invention.

Claims

1. A button battery, characterized in that: The button battery comprises a shell and a battery cell with a negative electrode symmetrically placed. The shell includes a positive electrode shell and a negative electrode shell; The positive electrode of the battery cell is a thick electrode with active materials on both sides and tabs; The negative electrode of the battery cell is divided into two groups, which are symmetrically placed on both sides of the positive electrode group. The positive and negative electrodes are separated by a separator, and the two groups of negative electrodes are conductively bridged by a negative electrode bridge. The negative electrode on the negative electrode shell side of the battery cell is directly conductively connected to the negative electrode shell; An insulating film is placed between the negative electrode on the positive electrode shell side of the battery cell and the positive electrode shell, the positive electrode tab is conductively connected to the positive electrode shell of the battery, and the insulating film insulates and separates the negative electrode and the positive electrode tab from the positive electrode shell.

2. The button battery according to claim 1, characterized in that: The thick electrode is formed by placing thick electrodes coated on one side back to back on both sides of a metal sheet with a tab, or by coating thick electrodes on both sides of a metal sheet, metal mesh or metal foil with a tab.

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

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

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

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

7. The button cell according to claim 1, characterized in that: The pole ear is bent to one side of the insulating film and is in contact with and conductive with the positive electrode shell.

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

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

10. A method for assembling a button cell according to any one of claims 1 to 9, characterized in that: The following steps are involved: Place the insulating sheet at the bottom of the battery positive electrode shell; The negative electrode, the separator, the positive electrode with the tab, the separator, and the negative electrode are sequentially stacked 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 groups of negative electrodes electrically, and on the other side of the multilayer structure, the tab of the positive electrode is bent to one side of the insulating film to contact and conduct with the positive electrode shell; The battery negative electrode shell is covered on the multilayer structure to complete the battery assembly.

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