button-type secondary battery

Abstract

The present invention relates to a button secondary battery, and more particularly to a button secondary battery in which a strong bonding force is formed between the base plate, the electrode terminal, and the insulating gasket while being able to reduce the thickness of a top plate assembly formed by bonding a base plate covering an opening of a can body into which an electrode assembly is inserted, an electrode terminal coupled to the base plate, and an insulating gasket that insulates the base plate and the electrode terminal. The button type secondary battery according to the present invention relates to a button type secondary battery having a diameter greater than its height, and includes an electrode assembly, a can body into which the electrode assembly is inserted, a base plate covering an upper end opening of the can body and coupled to the can body, an electrode terminal at least partially inserted into a through hole formed inside the base plate to cover the through hole, and an insulating gasket for insulating the electrode terminal from the base plate, and the electrode terminal, the insulating gasket, and the base plate are joined by thermal fusion.

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0013206, filed on January 29, 2021, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a button secondary battery, and the present invention relates to a button secondary battery in which a strong bonding force is formed between the base plate, the electrode terminal, and the insulating gasket while being able to reduce the thickness of a top plate assembly formed by joining a base plate that covers an opening of a can body into which an electrode assembly is inserted, electrode terminals that are coupled to the base plate, and an insulating gasket that insulates the base plate from the electrode terminal. [Background technology]

[0003] In recent years, with rising energy prices due to the depletion of fossil fuels and growing concerns about environmental pollution, the demand for environmentally friendly alternative energy sources has become an essential factor for future life. Accordingly, research into various power generation technologies, such as solar, wind, and tidal power, has been ongoing, and there has also been great interest in power storage devices, such as batteries, to more efficiently use the electrical energy produced in this way.

[0004] Furthermore, with the increasing technological development and demand for battery-based electronic mobile devices and electric vehicles, the demand for batteries as an energy source is rapidly increasing, and a great deal of research is being conducted into batteries that can meet the resulting diverse demands.

[0005] In particular, in terms of materials, there is a high demand for lithium secondary batteries such as lithium ion batteries and lithium ion polymer batteries, which have advantages such as high energy density, discharge voltage, and output stability.

[0006] Depending on the shape of the battery case, secondary batteries can be classified into cylindrical batteries and prismatic batteries in which an electrode assembly is housed in a cylindrical or prismatic metal can, and pouch batteries in which an electrode assembly is housed in a pouch-shaped case made of an aluminum laminate sheet, etc. Recently, with the gradual trend toward miniaturization of wearable devices, the development of small batteries such as button-type secondary batteries has become increasingly important.

[0007] FIG. 1 is a cross-sectional view showing a conventional button-type secondary battery.

[0008] 1, a button-type secondary battery 1, which is one type of conventional button cell, has a structure in which an electrode assembly 10 is inserted into the internal space of a body 20, and the opening of the body is covered by a base plate 30. The bottom of a positive electrode terminal 40 of the button-type secondary battery is riveted into a through-hole 31 formed in the center of the base plate 30, and is connected to the base plate 30.

[0009] The base plate 30, which is connected to the main body of the can body 20, which is the negative electrode, carries the negative electrode, and the positive electrode terminal 40 carries the positive electrode, so a structure is needed to insulate the positive electrode terminal from the base plate, and this structure is the gasket 50.

[0010] Conventionally, there is a limit to how thin a battery can be made because the positive terminal is rivet-connected to the base plate as shown in Fig. 1. Therefore, the thickness of the top plate assembly 90, which is a combination of the base plate, the positive terminal, and the gasket, must be kept thicker than a predetermined thickness, resulting in a secondary battery with relatively low energy density and space efficiency, which has been problematic.

[0011] Furthermore, there is a problem in that the joint surfaces of the base plate, the positive electrode terminal, and the gasket are not tightly and strongly joined, which may result in leakage of internal gas or electrolyte. Summary of the Invention [Problem to be solved by the invention]

[0012] The present invention has been devised to solve the above problems, and an object of the present invention is to provide a button secondary battery in which a strong bonding force is formed between the base plate, the electrode terminal, and the insulating gasket while being able to reduce the thickness of a top plate assembly formed by bonding a base plate that covers an opening of a can body into which an electrode assembly is inserted, electrode terminals that are coupled to the base plate, and an insulating gasket that insulates the base plate from the electrode terminal. [Means for solving the problem]

[0013] The button secondary battery according to the present invention relates to a button secondary battery having a diameter greater than its height, and includes an electrode assembly, a can body into which the electrode assembly is inserted, a base plate that covers an upper opening of the can body and is coupled to the can body, an electrode terminal that is at least partially inserted into a through-hole formed inside the base plate to cover the through-hole, and an insulating gasket for insulating the electrode terminal from the base plate, and the electrode terminal, insulating gasket, and base plate are joined by thermal fusion.

[0014] At least one of the electrode terminal and the base plate may have a surface that comes into contact with the insulating gasket and that is chromate-treated.

[0015] The electrode terminals and the base plate may be surface-treated with chromate on the surfaces that come into contact with the insulating gasket.

[0016] The electrode terminals and the base plate are made of a metal material, and the metal material may be at least one selected from the group consisting of SUS, nickel-plated carbon steel, and Al.

[0017] The insulating gasket may have a PP-MAH (maleic anhydride-modified polypropylene) layer formed on the surface.

[0018] The insulating gasket may have a three-layer structure of a PP-MAH layer, a PP (polypropylene) layer, and a PP-MAH layer.

[0019] In the electrode terminal, the chromate surface-treated portion and the PP-MAH layer of the insulating gasket may include portions that are hydrogen-bonded to each other.

[0020] The electrode terminal includes an insertion portion inserted into the through hole and a terminal plate portion extending outward from an upper end of the insertion portion and having a plate shape, and the lower surface of the terminal plate portion that contacts the insulating gasket may be surface-treated with chromate.

[0021] The upper surface of the base plate facing the insulating gasket may be chromate surface treated.

[0022] The outer peripheral surface of the insert that comes into contact with the insulating gasket may be chromate surface treated.

[0023] The inner surface of the base plate, which contacts the insulating gasket and forms the through-hole, may be surface-treated with chromate.

[0024] The thickness (h) of the top plate assembly to which the electrode terminal, the insulating gasket, and the base plate are joined may be 0.4 to 0.8 mm.

[0025] The edge of the base plate and the opening of the can body may be joined by laser welding.

[0026] An insulating tape may be attached to the lower surface of the base plate, and the insulating tape may insulate the base plate from the electrode assembly.

[0027] The electrode terminal may form the positive electrode, and the can body and base plate may form the negative electrode. [Effects of the Invention]

[0028] The button secondary battery according to the present invention relates to a button secondary battery having a diameter greater than its height, and includes an electrode assembly, a can body into which the electrode assembly is inserted, a base plate coupled to the can body and covering an upper opening of the can body, an electrode terminal at least partially inserted into a through-hole formed inside the base plate to cover the through-hole, and an insulating gasket for insulating the electrode terminal from the base plate. The electrode terminal, insulating gasket, and base plate are joined by thermal fusion, which allows for a thin top plate assembly formed by joining the base plate covering the opening of the can body into which the electrode assembly is inserted, the electrode terminal coupled to the base plate, and the insulating gasket insulating the base plate from the electrode terminal, while also allowing for a strong bond between the base plate, the electrode terminal, and the insulating gasket. [Brief explanation of the drawings]

[0029] [Figure 1] FIG. 1 is a cross-sectional view showing a conventional button-type secondary battery. [Figure 2] 1 is a cross-sectional view showing a button-type secondary battery according to Example 1 of the present invention. [Figure 3] 1 is a cross-sectional view of an insulating gasket showing a three-layer structure of the insulating gasket in a button-type secondary battery according to Example 1 of the present invention. [Figure 4] FIG. 2 is a diagram showing hydrogen bonding between a chromate surface-treated portion and a PP-MAH layer in the button-type secondary battery according to Example 1 of the present invention. [Figure 5] FIG. 4 is a cross-sectional view showing a button-type secondary battery according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0030] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The present invention will now be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily understand the preferred embodiments of the present invention. However, the present invention may be embodied in various different forms and should not be construed as being limited to the following embodiments.

[0031] In order to clearly explain the present invention, detailed descriptions of parts that are not relevant to the explanation or of related known technologies that may obscure the gist of the present invention will be omitted, and when adding reference symbols to components in each drawing in this specification, the same or similar reference symbols will be used throughout the specification for the same or similar components.

[0032] Furthermore, the terms and words used in this specification and claims should not be interpreted in a way that is limited to their ordinary and dictionary meanings, but should be interpreted in a way that is consistent with the technical idea of ​​the present invention, in accordance with the principle that the inventor himself / herself can appropriately define the concept of terms in order to explain the invention in the best possible way.

[0033] Example 1 Fig. 2 is a cross-sectional view showing a button secondary battery according to Example 1 of the present invention. Fig. 3 is a cross-sectional view of an insulating gasket showing the three-layer structure of the insulating gasket in the button secondary battery according to Example 1 of the present invention. Fig. 4 is a diagram showing hydrogen bonding between the chromate surface-treated portion and the PP-MAH layer in the button secondary battery according to Example 1 of the present invention.

[0034] 2, the button secondary battery 100 according to the first embodiment of the present invention may be a button secondary battery 100 having a diameter greater than a height. The button secondary battery 100 according to the first embodiment of the present invention may include an electrode assembly 110, a case body 120, a base plate 130, an electrode terminal 140, and an insulating gasket 150.

[0035] The electrode assembly 110 may be formed by stacking a positive electrode, a separator, and a negative electrode. The electrode assembly 110 may be a jelly roll type electrode assembly 110 in which electrodes and separators are alternately stacked and wound up.

[0036] The can body 120 may be configured to receive the electrode assembly 110. The can body 120 may have an internal space formed therein, into which the electrode assembly 110 may be inserted. The can body 120 may have an opening on the upper side. That is, the can body 120 may be configured to be open at the top and include a bottom and a sidewall.

[0037] The base plate 130 may be connected to the can body 120 by covering the top opening of the can body 120. This connection may be made by welding. Specifically, the edge 132 of the base plate and the opening 121 of the can body may be connected by laser welding. The form of this laser welding may be seam welding, which is advantageous for preventing welding pinholes. A through-hole 131 may be formed in the center of the inside of the base plate 130. Here, the base plate is made of a metal material, and this metal material may be any one or more selected from SUS, nickel-plated carbon steel, and Al.

[0038] The electrode terminal 140 may be a terminal coupled to the through-hole 131 formed inside the base plate 130. The electrode terminal 140 may be a positive electrode terminal forming a positive electrode. This may be the result of the positive electrode of the electrode assembly 110 being connected to the electrode terminal 140. When the electrode terminal 140 forms a positive electrode, the can body 120 and the base plate 130 may form a negative electrode. The negative electrode of the electrode assembly 110 is connected to the can body 120, so that the can body 120 has a negative electrode, and the base plate 130 may be welded to the can body 120, so that the base plate 130 has the same negative electrode as the can body 120.

[0039] The electrode terminal may be configured to be at least partially inserted into a through-hole formed inside the base plate to cover the through-hole, and may be made of a metal material, which may be at least one selected from the group consisting of SUS, nickel-plated carbon steel, and Al.

[0040] The insulating gasket 150 may be configured to insulate the electrode terminal 140 from the base plate 130. When the electrode terminal 140 forms a positive electrode, the base plate 130, which is connected to the main body of the can body 120, which is a negative electrode, has a negative electrode, and the electrode terminal 140 has a positive electrode. Therefore, a structure for insulating the electrode terminal 140 from the base plate 130 is required, and this structure may be the insulating gasket 150.

[0041] The electrode terminal 140, the insulating gasket 150, and the base plate 130 may be joined by thermal fusion. In the prior art, a rivet structure is used to join the electrode terminal 140, but in the button-type secondary battery 100 according to the first embodiment of the present invention, a thermal fusion structure may be used instead of the rivet structure.

[0042] 2, at least one of the electrode terminal 140 and the base plate 130 may be surface-treated with chromate on a surface that contacts the insulating gasket 150. Alternatively, to increase the bonding strength, the electrode terminal 140 and the base plate 130 may be surface-treated with chromate on all surfaces that contact the insulating gasket 150.

[0043] Chromate surface treatment may refer to the application of an anti-rust coating (chromate coating) to an article to be treated by placing it in a solution mainly containing chromate or dichromate. Chromate treatment can provide conductivity, form a corrosion-resistant coating, and improve adhesion. Chromate treatment also has the advantage of providing self-healing properties in areas where the coating is worn, forming a coating without flakes (plated layers).

[0044] In the button secondary battery 100 according to the first embodiment of the present invention, the insulating gasket 150 may have a PP-MAH (maleic anhydride-modified polypropylene) layer formed on its surface, thereby improving the bonding strength when coupled with the metal electrode terminal 140 or the base plate 130. Specifically, the insulating gasket 150 may have a three-layer structure of a PP-MAH layer 152, a PP (polypropylene) layer 151, and a PP-MAH layer 152 (see FIG. 3).

[0045] 2 and 4, the chromate surface-treated portion of at least one of the electrode terminal 140 and the base plate 130 and the PP-MAH layer on the surface of the insulating gasket 150 may include portions that are hydrogen-bonded to each other.

[0046] 4, in the button-type secondary battery 100 according to the first embodiment of the present invention, hydrogen bonding may occur between the OH of the PP-MAH and the O doubly bonded to the chromium in the chromium oxide adhesive layer (the hydrogen bonding portion is indicated by a dotted square line in FIG. 4). Where hydrogen bonding is formed between the electrode terminal 140 and the insulating gasket 150, and between the base plate 130 and the insulating gasket 150, the adhesive strength can be significantly improved.

[0047] Referring to FIG. 2, the electrode terminal 140 may include an insertion portion 141 inserted into the through-hole 131, and a terminal plate portion 142 extending outward from an upper end of the insertion portion 141 and having a plate shape.

[0048] 2, in the button-type secondary battery 100 according to the first embodiment of the present invention, the lower surface of the terminal plate portion 142 that contacts the insulating gasket 150 may be surface-treated with chromate. The upper surface of the base plate 130 that faces the insulating gasket 150 may also be surface-treated with chromate. In FIG. 2, the chromate-surface-treated portion is indicated by C. A hydrogen bond may be formed in this portion C with the PP-MAH layer 152 of the insulating gasket 150. (In FIG. 2, which is a cross-sectional view of the button-type secondary battery 100, the chromate surface-treated portion indicated by C is shown only on the left side for ease of understanding. Therefore, the present invention should not be limited to the case where the chromate surface treatment is performed only on the left side as shown in FIG. 2.)

[0049] When such a heat-sealed structure and a hydrogen-bonded structure are used, it is possible to significantly reduce the thickness of the top plate assembly 190 formed by joining the base plate 130, which covers the opening 121 of the case body 120 into which the electrode assembly 110 is inserted, the electrode terminal 140 joined to the base plate 130, and the insulating gasket 150, which insulates the base plate 130 from the electrode terminal 140. Specifically, the thickness (h) of the top plate assembly 190, in which the electrode terminal 140, the insulating gasket 150, and the base plate 130 are joined, can be 0.4 to 0.8 mm (see FIG. 2).

[0050] Furthermore, the thickness of the top plate assembly 190 can be significantly reduced, and at the same time, the bond between the base plate 130, the electrode terminal 140, and the insulating gasket 150 can be formed with a strong bonding force.

[0051] 2, an insulating tape 160 may be attached to the lower surface of the base plate 130. The insulating tape 160 may insulate the base plate 130 from the electrode assembly 110. Because both the positive and negative electrodes are wound around the electrode assembly 110, contact between the base plate 130 and the positive electrode may cause a short circuit, but the insulating tape 160 can prevent this from occurring.

[0052] Example 2 FIG. 5 is a cross-sectional view showing a button-type secondary battery according to a second embodiment of the present invention.

[0053] Example 2 of the present invention differs from Example 1 in the range of the portion that is surface-treated with chromate.

[0054] The content common to Example 1 will be omitted as much as possible, and differences will be mainly described in Example 2. In other words, if content not described in Example 2 is necessary, it is obvious that the content of Example 1 may be regarded as that of Example 2.

[0055] Referring to FIG. 5, in the button-type secondary battery according to the second embodiment of the present invention, the outer circumferential surface 243 of the insertion portion that contacts the insulating gasket 250 may be surface-treated with chromate.

[0056] In this case, the chromate-treated portion of the outer peripheral surface 243 of the insertion portion and the chromate-treated portion of the underside of the terminal plate portion 242 may be connected to each other. When connected in this manner, a geometrically folded structure can be formed (i.e., the cross section is formed in an L-shape as shown in FIG. 5), which can further improve bonding strength and airtightness. As described above, the chromate-treated portion can come into contact with the PP-MAH on the surface of the insulating gasket to form hydrogen bonds.

[0057] In addition, in the button secondary battery 200 according to the second embodiment of the present invention, the inner surface 233 of the base plate that contacts the insulating gasket 250 and forms the through-hole may be surface-treated with chromate.

[0058] In this case, the chromate-treated portion of the inner surface 233 of the base plate and the chromate-surface-treated portion on the upper surface of the base plate 230 may be connected to each other. When connected in this manner, a geometrically folded structure (L-shaped) may be formed, which may further improve bonding strength and airtightness. Even in this case, hydrogen bonds may be formed between the chromate-treated portion and the surface of the insulating gasket.

[0059] Although the present invention has been described above using limited examples and drawings, the present invention is not limited thereto, and various embodiments can be made by a person having ordinary skill in the art to which the present invention pertains within the technical spirit of the present invention and the equivalent scope of the claims set forth below. [Explanation of symbols]

[0060] 1, 100, 200 Button-type secondary battery 110, 210 electrode assembly 120, 220 can body 121 Can body opening 130, 230 base plate 131 Through Hole 132 Base plate edge 140, 240 electrode terminal 141, 241 Insertion section 142, 242 Terminal plate part 150, 250 Insulation gasket 151 PP layer 152 PP-MAH layer 160 Electrical Tape 190 Top Plate Assembly 233 Inner surface of base plate 243 Outer surface of insertion part

Claims

1. A button-type secondary battery whose diameter is greater than its height, an electrode assembly; a can body into which the electrode assembly is inserted; a base plate that covers an upper end opening of the can body and is coupled to the can body; an electrode terminal at least partially inserted into a through hole formed inside the base plate to cover the through hole; an insulating gasket for insulating the electrode terminal from the base plate; the electrode terminal, the insulating gasket, and the base plate are joined by thermal fusion; the insulating gasket includes a PP (polypropylene) layer; The insulating gasket is It has a three-layer structure of a PP-MAH (maleic anhydride-modified polypropylene) layer, a PP (polypropylene) layer, and a PP-MAH (maleic anhydride-modified polypropylene) layer. Button-type secondary battery.

2. The button-type secondary battery according to claim 1 , wherein at least one of the electrode terminal and the base plate has a surface that is in contact with the insulating gasket and is chromate-treated.

3. The button-type secondary battery according to claim 2 , wherein the electrode terminals and the base plate have surfaces that are in contact with the insulating gasket and are chromate-treated.

4. the electrode terminal and the base plate are made of a metal material; 4. The button-type secondary battery according to claim 2, wherein the metal material is at least one selected from the group consisting of stainless steel, nickel-plated carbon steel, and aluminum.

5. 3. The button-type secondary battery of claim 2, wherein the chromate surface-treated portion of at least one of the electrode terminal and the base plate and the PP-MAH layer of the insulating gasket include mutual hydrogen-bonded portions.

6. The electrode terminal includes an insertion portion inserted into the through hole, and a terminal plate portion extending outward from an upper end of the insertion portion and having a plate shape, 6. The button-type secondary battery according to claim 2, wherein a lower surface of the terminal plate portion that contacts the insulating gasket is surface-treated with chromate.

7. The button-type secondary battery according to claim 6 , wherein the upper surface of the base plate facing the insulating gasket is surface-treated with chromate.

8. The button-type secondary battery according to claim 7 , wherein the outer peripheral surface of the insertion portion that contacts the insulating gasket is surface-treated with chromate.

9. The button secondary battery according to claim 8 , wherein an inner surface of the base plate that contacts the insulating gasket and forms the through-hole is surface-treated with chromate.

10. 10. The button-type secondary battery according to claim 1, wherein a thickness (h) of a top plate assembly to which the electrode terminal, the insulating gasket, and the base plate are joined is 0.4 to 0.8 mm.

11. The button secondary battery according to claim 1 , wherein the edge of the base plate and the opening of the can body are joined by laser welding.

12. An insulating tape is attached to the lower surface of the base plate, The button-type secondary battery according to claim 1 , wherein the insulating tape provides insulation between the base plate and the electrode assembly.

13. The electrode terminal forms a positive electrode, The button-type secondary battery according to claim 1 , wherein the can body and the base plate form a negative electrode.

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