A button battery with improved sealing properties

Abstract

According to the invention, a coin cell battery is provided, comprising a sealing assembly comprising one of the terminals of the battery, an electrically insulating portion and a peripheral wall portion. The electrically insulating portion forms an air-tight bond with the terminal and the peripheral wall portion obtainable by a method employed in glass-metal type technology. The sealing assembly is of a socket shape and one or more of the constituent parts of the battery, such as the anode, the separator and the cathode, can be inserted into the socket shape before assembling the battery. The peripheral wall portion forms a part of the second terminal and is attached to the rest of the second terminal by an electrically conductive and air-tight closed connection, such as a circumferential weld. The battery according to the invention can be produced by inserting one or more of the constituent parts of the battery into the sealing assembly and attaching the peripheral wall portion of the sealing assembly to the rest of the second terminal, for example by welding.

Description

Technical Field

[0001] This invention relates to button-shaped batteries, and more particularly to the sealing of these batteries. Background Technology

[0002] Button batteries, also known simply as "button cells," "coin cells," or "micro batteries," are widely used to power small electrical appliances and devices. Various types of button batteries exist, differing in size and the materials used for the electrodes and electrolyte. A common type used in low-voltage appliances such as watches is often called a "CR" type battery, where C indicates the chemical composition of the electrodes and R indicates the spherical shape of the battery. CR batteries consist of a lithium-based anode and a cathode containing manganese dioxide as the active material. The electrolyte can be a solid or liquid organic material. Other types are coded as LR, SR, or PR batteries, known as alkaline batteries, silver oxide batteries, and zinc-air batteries, respectively. The latter three battery types contain an aqueous electrolyte.

[0003] All button batteries include round metal terminals, one of which is usually called a cup and the other a cap, with the electrodes and electrolyte housed between them.

[0004] A common problem encountered in button batteries that contain liquid electrolytes is electrolyte leakage. Electrolyte leakage can occur when the battery is not properly sealed, allowing its electrolyte to leak from the inside into the atmosphere.

[0005] For silver oxide batteries, zinc-air batteries, and alkaline batteries, the electrolyte is typically a strongly alkaline solution containing NaOH and KOH, along with other chemicals. For lithium batteries, the electrolyte is typically one or more organic solvents containing dissolved lithium salts. Both types of electrolytes pose hazards to the environment and humans. Strongly alkaline solutions are highly corrosive; even small amounts can cause metal corrosion. If they get into the eyes, mouth, skin, or are even inhaled, they can cause serious damage to human organs.

[0006] Currently, button batteries are sealed by pressing a cup onto a plastic gasket, which separates the cup from the cap. However, especially for small button batteries, the pressing strength is often insufficient, increasing the risk of electrolyte leakage. Summary of the Invention

[0007] The present invention aims to provide a solution to the above-mentioned problems. This objective is achieved by a button cell battery and a method for producing the battery, as described below.

[0008] According to the present invention, a button cell battery is provided, comprising a sealing assembly including one of the cell's terminals, an electrically insulating portion, and a peripheral wall portion. The electrically insulating portion forms an hermetically sealed joint with the terminal and the peripheral wall portion, i.e., a gas- and liquid-sealed joint, which can be achieved by methods applied in glass-metal mold technology. The electrically insulating portion can therefore be, for example, a glass portion. The sealing assembly is in the shape of a socket, and one or more components of the cell, such as an anode, separator, and cathode, can be inserted into the socket shape prior to cell assembly. The peripheral wall portion of the sealing assembly forms part of a second terminal and is attached to the remainder of the second terminal via a conductive and hermetically sealed connection, such as a circumferential weld. These terminals can be formed of stainless steel or any other suitable metal.

[0009] The battery according to the invention can be manufactured by inserting one or more components of the battery into a socket-shaped sealing assembly, and attaching, for example by welding, a peripheral wall portion of the assembly to the remainder of a second terminal.

[0010] This invention enables the application of glass-metal type technology in the production process of button batteries of various shapes and sizes, including small batteries where current gasket seals pose a risk of electrolyte leakage. This risk is reduced or substantially eliminated by incorporating a higher-quality metal-glass type seal in the battery according to the invention. Attached Figure Description

[0011] - Figure 1a and 1b The front view and planar cross-section of a button cell known to date in the art are shown.

[0012] - Figure 2a and 2b The front view and planar cross-sectional view of a button battery according to an embodiment of the present invention are shown.

[0013] - Figures 3a to 3d It shows the production according to Figure 2a and 2b The battery method of the illustrated embodiment includes multiple steps.

[0014] - Figures 4a to 4d The steps of a method for producing a battery according to another embodiment of the present invention are shown. Detailed Implementation

[0015] Before describing the characteristic elements of the battery according to the present invention, prior art button batteries will first be described to define their various components. Figure 1a and 1bA button cell 1, as is currently known in the art, is shown. The cell includes a metal cup 2, typically made of stainless steel, which forms the positive terminal of the cell. A cathode 3 is placed inside the cup 2. Figure 1a The cathode shown is formed into a tablet, which can be obtained by pressing cathode powder into a metal retainer 4, which is a ring shape with a bottom strip 5 and sidewalls 6. Alternatively, the cathode powder can be pressed into a metal mesh. The retainer 4 or the mesh is designed to increase the mechanical stability of the compacted cathode powder.

[0016] like Figure 1a As shown, the compacted cathode material 3 is flush with the bottom surface of the annular strip 5, and these elements are all in physical contact with the bottom of the cup 2. Above the tablet 3 is a separator or partition 7, which separates the cathode tablet 3 from the battery anode 8 located on top of the partition 7. The anode 8 is covered by a metal cap 9, which forms the negative terminal of the battery 1 and is typically also made of stainless steel. The negative terminal 9 includes a circular planar contact surface 11 and an upright wall portion 12 oriented away from the contact surface 11. Similarly, the positive terminal 2 includes a circular planar contact surface 13 and a wall portion 14 oriented away from said contact surface 13. The contact surfaces 11 and 13 are configured to form corresponding contacts for electrical connection to a battery-powered device.

[0017] The separator 7 can be a sheet-like solid electrolyte laminated on the cathode 3, in which case the cathode 3 also includes a solid electrolyte mixed with the active material. Alternatively, the battery 1 can include a liquid electrolyte. In this case, the cathode 3 is immersed in such a liquid electrolyte, and the separator 7 can be a porous polymer membrane that is electrically insulating itself but can absorb the liquid electrolyte to conduct ions from the anode 8 to the cathode 3.

[0018] An electrical insulating gasket 10 is inserted between the outer edges of the cup 2 and the cap 9, thereby separating the positive and negative terminals and isolating the interior of the battery 1 from the external atmosphere. As described in the introduction, the sidewall 14 of the cup 2 is pressed against the gasket 10; however, this method of sealing the battery introduces a risk of electrolyte leakage when using a liquid electrolyte, especially for smaller batteries.

[0019] This invention addresses this problem by providing a method for applying a glass-metal type seal in a button cell. Since this invention is not limited to using glass as the sealing material, this type of seal will be referred to hereinafter as an "insulator-metal" seal. However, it should be understood that this term refers to known techniques in which an electrically insulating material—such as glass—is chemically bonded to a metal to form a hermetically tight seal between a solid insulator and a metal, and in which the coefficients of thermal expansion of the metal and the insulator are matched to maintain the seal within a given temperature range. This technique is known in applications in construction, automotive, optics, and many other fields.

[0020] Figure 2a and 2b An example of a button cell according to the invention is shown. Many of the aforementioned components can be identified and are indicated by the same reference numerals: a cup 2 having its contact surface 13 and sidewalls 14, a cathode 3, a separator 7, an anode 8, and a negative terminal 9 having its contact surface 11 and sidewalls 12. In this case, the cathode 3 may be a pressed tablet, which is not pressed into the annular retainer but rather into a mesh (not visible in the figure, but known to be so). For example, for a silver oxide battery, the cathode tablet may be pressed directly into the cup 2.

[0021] Furthermore, it can be seen that the cup 2 is welded to the metal ring 15, which is partially inserted into the cup 2 and welded to the cup 2 through the weld 16.

[0022] An electrically insulating portion 17 exists between the upright wall 12 of the negative terminal 9 and the metal ring 15. The joints between the electrically insulating portion 17 and the terminal 9 on one hand, and between the electrically insulating portion 17 and the metal ring 15 on the other hand, belong to the insulator-metal type as defined above; that is, the ring 15, the electrically insulating portion 17 (e.g., a glass portion), and the negative terminal 9 form an assembly of tightly bonded materials, wherein the electrically insulating portion 17 is tightly bonded to the negative terminal 9 and the metal ring 15, and wherein the coefficient of thermal expansion of the electrically insulating portion 17 matches that of the metal component within a given temperature range. This tightly bonded material assembly is referred to as a "sealed assembly" in the appended claims.

[0023] In the assembled battery shown in Figure 2, the positive terminal is formed by the cup 2 and the metal ring 15. The metal ring 15, together with the weld 16 and the upright wall of the cup 2, defines the upright wall of the positive terminal. The insulator 17 forms electrical insulation between the two terminals 9 and 2+15, while also sealing the battery interior relative to the atmosphere. Compared to... Figure 1a and 1b The gasket seal shown is of a much higher quality than the hermetic seal achieved through the insulator-metal joint. Through this hermetic seal, and through the weld 16 forming an equally hermetic but conductive connection, the battery is reliably isolated from the atmosphere, thus ensuring that no electrolyte can leak out.

[0024] Several key process steps required to produce the battery in Figure 2 are described in detail below. Figures 3a to 3d As shown in the diagram, the sealing assembly formed by the negative terminal 9, the insulator 17, and the metal ring 15 is... Figure 3a As shown in the diagram, this component can be produced using techniques known from insulator-metal type bonding techniques.

[0025] Depending on the materials used, the metal surface to be bonded to the insulator may need to be pretreated, such as by cleaning, oxidation, or by applying a reactive layer to the metal surface to be bonded to the insulator.

[0026] like Figure 3b As shown, the anode 8 is then inserted into the sealing assembly. The anode 8 can be a solid anode material, such as lithium in the case of a CR battery, or it can be a slurry of negative electrode active material particles, as in a silver oxide battery where zinc slurry is used as the anode. In the latter case, the anode material fills the internal volume of the sealing assembly (i.e., there is no gap between the sidewall 12 of the negative terminal and the anode 8).

[0027] like Figure 3c As shown, the cathode plate 3 and the separator 7 are placed inside the cup 2. When using a liquid electrolyte, the liquid electrolyte is added to the cup 2, allowing the liquid to be absorbed by the cathode 3 and the separator 7. Figure 3d As shown, the sealing assembly containing the anode 8 is then inserted into the upright wall 14 of the cup 2 until the anode 8 contacts the partition 7. The heights of the upright wall 14 and the metal ring 15 are configured such that the wall 14 and the metal ring 15 overlap each other at this point. A weld 16 is then applied using a suitable welding process to obtain... Figure 2a and 2b The battery shown is completely sealed.

[0028] This invention is not limited to batteries having the geometries shown in Figures 2 and 3. A key feature of this invention is the production of a sealing assembly prior to battery assembly. Both terminals of the assembled battery have a socket shape, comprising a planar circular contact surface and upright sidewalls oriented away from this contact surface. The sealing assembly includes one terminal of the battery, an insulating portion, and a peripheral wall portion that becomes part of the other terminal of the assembled battery. The terminal portions of the sealing assembly are electrically insulated from each other by an insulating material tightly bonded to the terminal portions, thereby forming an hermetically tight seal between the insulating material and the respective terminal portions. The peripheral wall portion of the sealing assembly is attached to the remainder of the other terminal via a conductive and hermetically sealed connection (e.g., a circumferential weld).

[0029] In the embodiments of Figures 2 and 3, the sealing assembly includes a negative terminal 9, an electrically insulating portion 17, and a metal ring 15. The metal ring represents the aforementioned peripheral wall portion, which in this case is part of the positive terminal. The positive terminal is formed by a cup 2 and the metal ring 15 welded together by a circumferential weld 16.

[0030] The method for producing batteries according to the present invention generally includes the following steps:

[0031] - Producing a sealing assembly as described above. This assembly includes a socket-shaped terminal and a surrounding wall portion. Therefore, the assembly itself is also socket-shaped.

[0032] - Place one or more components of the battery in a socket formed by a sealing assembly, and / or if the remainder of another terminal is socket-shaped, place it in a socket formed by said remainder, said components including a cathode, an anode, and a separator.

[0033] - If a liquid electrolyte is used, it is added to the socket formed by the sealing assembly, or if the remainder of the other terminal is socket-shaped, it is added to the socket formed by the remainder. The liquid electrolyte is added to the socket containing electrode material capable of absorbing the electrolyte. This can be a sealing assembly including an anode paste (e.g., zinc paste in the case of a silver oxide battery), or... Figure 3c The cup 2 in the illustrated embodiment, wherein the electrolyte is absorbed by the cathode tablet 3, or a sealed assembly including an anode, a cathode, and a separator, such as... Figure 4b The illustrated embodiment. The liquid electrolyte can be added in multiple steps, such as before and after adding the separator 7 to one of the sockets. Only one of the sockets is added to the liquid electrolyte; otherwise, the liquid electrolyte would leak out during the assembly of these sockets.

[0034] - Assemble the sealing assembly onto the remainder of the other terminal. When using a liquid electrolyte, this means that the socket containing the liquid electrolyte (which can be the sealing assembly or the remainder of the other terminal) is positioned with the socket face up, and then the other component is placed on top of the socket.

[0035] In the embodiments of Figures 2 and 3, the anode 8 is inserted into the sealing assemblies 9, 17, and 15, while the cathode 3 and the separator 7 are inserted into the cup 2, and then these components are brought together to assemble the finished battery.

[0036] Figures 4a to 4d The method of the present invention and another embodiment of the battery according to the present invention produced by said method are illustrated. The sealing assembly is in... Figure 4a As shown, it also includes a negative battery terminal 9 with a contact surface 11 and sidewalls 12, an electrically insulating portion 17, and a peripheral wall portion 15. The upright wall 12 of the negative terminal 9 is inclined relative to the contact surface 11 of the terminal, and the peripheral wall portion 15 includes an inclined portion 15a and a straight portion 15b that are generally parallel to the wall 12 of the negative terminal. The sealing assemblies 9, 17, and 15 form a socket capable of accommodating all three main battery components, such as... Figure 4bAs shown: anode 8, separator 7, and cathode 3. Liquid electrolyte can be added at this point, or it can be added between the separator 7 and cathode 3, and a second time after the cathode 3 is inserted. Then, as... Figure 4c As shown, a circular metal plate portion 2', whose outer diameter corresponds to the outer diameter of the peripheral wall portion 15 of the sealing assembly, is assembled onto the peripheral wall portion 15, and hermetically connected to the peripheral wall portion 15 by a circumferentially welded sealing portion 16, thereby forming... Figure 4d The finished battery is shown. Therefore, in this embodiment, the peripheral wall portion 15 of the sealing assembly forms the entire sidewall of the positive terminal 2'+15 of the assembled battery. The shape of this battery, characterized by its sloping sidewalls, conforms to the standard shape used for certain battery types such as CR batteries and silver oxide batteries.

[0037] Other variations are also within the scope of this invention. For example, according to an embodiment of the invention, the sealing assembly includes a positive terminal instead of a negative terminal. For example, the sealing assembly may include a cup 2 that engages with the insulating portion and at least a portion of the sidewall of the negative terminal.

[0038] Similarly, compared to the embodiment shown in the accompanying drawings, the positions of electrodes 3 and 8 can be reversed. For example, in Figure 2a and 2b In the case of the embodiment, component 2+15 thus becomes the negative terminal and cover 9 becomes the positive terminal. The above description is valid after necessary modifications to this situation.

[0039] exist Figure 2a and 2b In this embodiment, wall portions 14 and 15 may abut rather overlap along the circumference of the battery. Many other configurations are also possible within the scope of this invention; the illustrated embodiments are merely examples.

[0040] Although the invention has been illustrated and described in detail in the accompanying drawings and the foregoing description, these illustrations and descriptions should be considered illustrative or exemplary rather than restrictive. By studying the drawings, the disclosure, and the appended claims, those skilled in the art will be able to understand and implement other variations of the disclosed embodiments in practicing the claimed invention. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality. The mere fact that certain measures are enumerated in mutually different dependent claims does not indicate that combinations of these measures cannot be used advantageously. Any reference marks in the claims should not be construed as limiting the scope.

Claims

1. A button cell (1', 1'') comprising a socket-shaped metal positive terminal and a socket-shaped metal negative terminal, each of the positive and negative terminals comprising a circular contact surface (13, 11) and a sidewall (14, 15; 12) extending in a direction opposite to the contact surface, wherein the contact surface is configured to be electrically connected to a corresponding contact of a device powered by the button cell, the button cell further comprising a cathode (3) electrically contacting the positive terminal, an anode (8) electrically contacting the negative terminal, a separator (7) disposed between the anode and the cathode, and an electrolyte configured to conduct current between the anode and the cathode, wherein: - The button battery includes a socket-shaped sealing assembly, the sealing assembly comprising: • The first terminal of the positive terminal and the negative terminal, • Zhoubi section (15), • Electrically insulating portion (17), which separates and electrically insulates the first terminal from the peripheral wall portion (15), - The electrically insulating portion (17) is joined to the first terminal and the peripheral wall portion (15, 15') through an airtight sealing joint. - The peripheral wall portion (15, 15') is part of the second terminal and is attached to the remainder of the second terminal via an hermetically sealed conductive connection portion (16). Wherein, the first terminal is the negative terminal (9), and the remaining portion of the positive terminal is a cup-shaped element (2) with an upright wall (14), such that the sidewall of the positive terminal is formed by the upright wall (14) and the peripheral wall portion (15) connected to each other by the conductive connection portion (16), and wherein the conductive connection portion is a circumferential weld (16).

2. The button cell (1', 1'') according to claim 1, wherein, The electrically insulating part (17) is a glass part.

3. The button cell (1', 1'') according to claim 1 or 2, wherein, The positive and negative terminals are made of stainless steel.

4. The button cell (1', 1'') according to claim 1 or 2, wherein, The electrolyte is a liquid electrolyte.

5. The button cell (1', 1'') according to claim 1 or 2, wherein, The button cell battery is selected from the following groups: CR battery, SR battery, LR battery, PR battery.

6. A method for producing a button cell (1', 1'') according to any one of claims 1-5, comprising the following steps: - The socket-shaped sealing assembly is manufactured using a bonding technique that combines the material of the electrical insulation portion (17) with the material of the first terminal and the material of the peripheral wall portion (15). - Place one or more components of the button cell into a socket formed by the sealing assembly, and / or place the remaining portion of the second terminal into a socket formed by the remaining portion if the second terminal is socket-shaped, the components including a cathode (3), an anode (8), and a separator (7), - If a liquid electrolyte is used, the liquid electrolyte is added to the socket formed by the sealing assembly, or if the remainder of the second terminal is socket-shaped, it is added to the socket formed by the remainder. - Assemble the sealing assembly onto the remainder of the second terminal. - The peripheral wall portion (15) of the sealing assembly is attached to the remainder of the second terminal via the hermetically sealed conductive connection portion (16).

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