Secondary button battery

Abstract

The present invention relates to a button secondary battery, and more particularly to a button secondary battery that has a strong bond that prevents excessive internal pressure caused by gas generated inside the battery from separating the battery due to the gas pressure, preventing gases harmful to the human body from leaking out of the battery, and preventing electrolyte from leaking out of the battery, and that can simplify and facilitate the battery manufacturing process, thereby increasing production efficiency. 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 lower can into which the electrode assembly is inserted and having a first thread formed on its outer peripheral surface, an upper can covering the top opening of the lower can and having a second thread formed on its inner peripheral surface corresponding to the first thread, and an insulator interposed between the upper can and the lower can to prevent a short circuit between the upper can and the lower can, and an electrode tab extending from an electrode of the electrode assembly contacts the upper can.

Description

[Technical field]

[0001] This application claims the benefit of priority to Korean Patent Application No. 10-2020-0119621, filed September 17, 2020, and Korean Patent Application No. 10-2021-0113894, filed August 27, 2021, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a button secondary battery, and more particularly to a button secondary battery that has a strong bond that prevents the battery from being separated by the gas pressure or the gas harmful to the human body from leaking out of the battery even if excessive internal pressure is generated due to gas generated inside the battery, and that prevents an electrolyte from leaking out of the battery, and that can simplify and facilitate the manufacturing process of the battery, thereby increasing production efficiency. [Background technology]

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

[0004] Furthermore, with 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 as a result, much research is being conducted into batteries that can meet various 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 the electrode assembly is built into a cylindrical or prismatic metal can, and pouch batteries in which the electrode assembly is built into a pouch-shaped case made of an aluminum laminate sheet, etc. In recent years, the importance of developing small batteries such as button-type secondary batteries has emerged in line with the trend of wearable devices becoming increasingly smaller.

[0007] FIG. 1 is a cross-sectional view showing a conventional button-type secondary battery. Referring to FIG. 1, a conventional button-type secondary battery 10 has separate upper and lower housings, and the upper and lower housings are tightly fitted with a cylindrical upper can 4 and a cylindrical lower can 3. That is, the outer diameter of the lower cylindrical can 3 is slightly larger than that of the upper can, and they are tightly fitted together. In the case of a tight fit, the button-type secondary battery maintains its shape due to the frictional force of the fit. In the conventional button-type secondary battery, the upper can 4 and the lower can 3 are manufactured according to the size of the internal electrode assembly 1 and fitted together, so there is no extra space inside.

[0008] However, in this type of structure, when the internal pressure increases due to internal gas generation, etc., there is a high possibility that the upper can 4 and the lower can 3 will separate because there is no force holding them together other than friction. The internal pressure may increase due to side reactions, but it can also increase during normal cycling. If the internal pressure increases too much, the upper can and the lower can will separate, and the battery will not function. Therefore, there was a need to research a product in which the upper and lower cans were strongly bonded together so that they could not be separated. Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been made to solve the above problems, and an object of the present invention is to provide a button-type secondary battery that has a strong bond that prevents the battery from being separated by the gas pressure or the gas harmful to the human body from leaking out of the battery even if excessive internal pressure is generated due to gas generated inside the battery, and that prevents the electrolyte from leaking out of the battery, and that can simplify and facilitate the manufacturing process of the battery to increase production efficiency. [Means for solving the problem]

[0010] The button type secondary battery of the present invention relates to a button type secondary battery whose diameter is greater than its height, and includes an electrode assembly, a lower can into which the electrode assembly is inserted and which has a first thread formed on its outer peripheral surface, an upper can which covers the top opening of the lower can and which has a second thread formed on its inner peripheral surface corresponding to the first thread, and an insulator interposed between the upper can and the lower can to prevent a short circuit between the upper can and the lower can, and an electrode tab extending from an electrode of the electrode assembly contacts the upper can.

[0011] The upper can may include an upper can electrode terminal portion that is connected to an electrode of the electrode assembly via an electrode tab to form a terminal that is connected to an external device and covers an upper end opening of the lower can, and the electrode tab may include a support portion that is connected to the electrode of the electrode assembly and a contact portion that extends from the support portion and contacts the upper can electrode terminal portion.

[0012] The support portion may be formed in a bar shape, and the contact portion may be formed in a ring shape. The thickness of the contact portion having an annular shape may be greater than the thickness of the support portion.

[0013] The support portion may be formed in a bar shape, and the contact portion may be formed in a disk shape. The outer diameter of the contact portion formed in a circular ring shape and the outer diameter of the electrode assembly may have a size corresponding to each other.

[0014] An insulating plate may be provided between the contact portion and the upper surface of the electrode assembly. The insulator may be a PBT (polybutylene terephthalate) material.

[0015] The insulator may include an inner insulator located inside the lower can, an outer insulator located outside the lower can, and a connecting insulator connecting the inner insulator and the outer insulator.

[0016] The upper can and the lower can are screwed together by a first thread and a second thread, and the outer insulator is interposed between the first thread and the second thread, and the outer insulator has an uneven shape due to being compressed by the protruding shapes of the first thread and the second thread, and may be sandwiched between the first thread and the second thread.

[0017] An inner insulator may be positioned between the electrode tab and the lower can to prevent contact between the electrode tab and the lower can. A central hole may be formed in the center of the electrode assembly, and a center pin may be provided within the central hole to fill the central hole.

[0018] The end of the upper can may be bent toward the central axis of the lower can. The outer insulator extends downward along the outer wall of the lower can, and at this time, the end of the outer insulator can extend downward further than the end of the upper can. Effect of the Invention

[0019] 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 lower can into which the electrode assembly is inserted and having a first thread formed on an outer circumferential surface, an upper can covering an upper end opening of the lower can and having a second thread formed on an inner circumferential surface corresponding to the first thread, and an insulator interposed between the upper can and the lower can to prevent a short circuit between the upper can and the lower can, and an electrode tab extending from an electrode of the electrode assembly is in contact with the upper can. As a result, even if excessive internal pressure is generated due to gas generated inside the battery, the battery is separated due to the gas pressure, or a strong bond is provided that prevents gas harmful to the human body from leaking out of the battery and prevents electrolyte from leaking out of the battery, and the battery manufacturing process can be simplified and convenient, thereby increasing production efficiency. [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 is a cross-sectional view showing a conventional button-type secondary battery. [Diagram 2] 1 is a cross-sectional view showing a button-type secondary battery according to a first embodiment of the present invention. [Diagram 3] 3 is a perspective view showing only an electrode assembly and an electrode tab in the button-type secondary battery according to the first embodiment of the present invention shown in FIG. 2. FIG. [Figure 4] 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 PREFERRED EMBODIMENTS

[0021] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings, in order to enable those skilled in the art to easily carry out the present invention. However, the present invention may be realized in various different forms, and is not limited to the following embodiments.

[0022] In order to clearly explain the present invention, detailed descriptions of parts that are not relevant to the explanation or related known technologies that may unnecessarily obscure the gist of the present invention will be omitted, and when assigning reference symbols to components in each drawing in this specification, the same or similar reference symbols will be assigned to the same or similar components throughout the specification.

[0023] Furthermore, the terms and words used in this specification and the claims should not be interpreted in a limited manner to their ordinary or dictionary meanings, but should be interpreted in a manner that is consistent with the technical ideas of the present invention, based on the principle that the inventors can appropriately define the concepts of terms in order to best describe their invention.

[0024] First embodiment Fig. 2 is a cross-sectional view showing a button-type secondary battery according to a first embodiment of the present invention, and Fig. 3 is a perspective view showing only an electrode assembly and an electrode tab in the button-type secondary battery according to the first embodiment of the present invention shown in Fig. 2.

[0025] 2, the button secondary battery 100 according to the first embodiment of the present invention may be a cylindrical battery, and the diameter of the cylindrical battery may be greater than the height of the battery. The button secondary battery 100 according to the first embodiment of the present invention may include an electrode assembly 150, a lower can 110, and an upper can 130. The electrode assembly 150 may be formed by alternately stacking electrodes 151 and separators 152 and winding them up.

[0026] The electrode assembly 150 may be inserted into the lower can 110. The lower can 110 may be cylindrical with an open top. The electrode assembly 150 may be in the form of a jelly roll. When the electrode assembly 150 is placed in the lower can 110, the winding axis of the electrode assembly 150 may be arranged perpendicular to the ground.

[0027] In the button secondary battery 100 according to the first embodiment of the present invention, the lower can 110 may have a first thread 111 formed on its outer circumferential surface. The upper can 130 may be configured to cover the upper end opening of the lower can 110. The upper can 130 may have a second thread 132 formed on its inner circumferential surface, which corresponds to the first thread 111. The first thread 111 and the second thread 132 may be in a relationship in which they are screwed together when the upper can 130 and the lower can 110 are joined together. That is, when the upper can 130 is to be joined to cover the lower can 110, the upper can 130 can be rotated relative to the lower can 110 to be screwed together, rather than being pushed together as it is. When the upper can 130 rotates relative to the lower can 110, the first thread 111 and the second thread 132 are screwed together, so that the upper can 130 and the lower can 110 approach each other, and when the screwing is completed, the button type secondary battery 100 in which the upper can 130 and the lower can 110 are completely connected can be manufactured. Figure 2 shows the state in which the screwing of the upper can 130 and the lower can 110 is completed.

[0028] The button secondary battery 100 according to the first embodiment of the present invention includes an insulator 170 that is interposed between the upper can 130 and the lower can 110 to prevent a short circuit between the upper can 130 and the lower can 110. The insulator 170 may include an inner insulator 171, a connecting insulator 172, and an outer insulator 173. The inner insulator 171 may be an insulator portion located inside the lower can 110. The outer insulator 173 may be an insulator portion located outside the lower can 110. And, the connecting insulator 172 may be an insulator portion that connects the inner insulator 171 and the outer insulator 173.

[0029] The insulator 170 may be disposed over the upper end of the lower can 110. That is, the connecting insulator 172 may be positioned to cover the upper end of the lower can 110, and the inner insulator 171 may be positioned to contact the inner circumference of the upper end of the lower can. Also, the outer insulator 173 may be positioned to contact the outer circumference of the upper end of the lower can 110. Also, the outer insulator 173 may be formed longer than the inner insulator 171.

[0030] Referring to FIG. 2 , the upper can 130 and the lower can 110 are screwed together by a first thread 111 and a second thread 132, while the outer insulator 173 is interposed between the first thread 111 and the second thread 132. The outer insulator 173 has an uneven shape due to pressure exerted by the protruding shapes of the first thread 111 and the second thread 132, and may be sandwiched between the first thread 111 and the second thread 132.

[0031] Meanwhile, the upper can end 131 may have the same height as the outer insulator end 173a (see FIG. 2), or the outer insulator end 173a may have a lower height than the upper can end 131. The outer insulator end 173a having a lower height than the upper can end 131 may mean that the outer insulator end 173a is located closer to the bottom surface of the lower can 110 than the upper can end 131.

[0032] The process of combining the upper can 130 and the lower can 110 is as follows. First, the lower can 110 in which the electrode assembly 150 is inserted is placed, and the insulator 170 is combined with the lower can 110 in a manner that covers the upper end of the lower can 110. The insulator 170 can be combined with the lower can 110 in a state in which the connecting insulator 172 is positioned in a manner that covers the upper end of the lower can 110, the inner insulator 171 is in contact with the inner circumference of the upper end of the lower can, and the outer insulator 173 is in contact with the outer circumference of the upper end of the lower can 110. Then, the upper can 130 can be rotated and combined thereon. That is, the inner circumference of the upper can 130 can be rotated and screwed into the outer circumference of the outer insulator 173. In this process, the first thread 111 and the second thread 132 form a protruding spiral, and the outer insulator 173 can be pressed by the protruding shapes of the first thread 111 and the second thread 132 to have an uneven shape. In FIG. 2, it is shown that the external thread has a concave-convex shape.

[0033] This is because the upper can 130 is firmly attached to the lower can 110, and is not easily separated from the lower can 110. As a result, even if excessive internal pressure is generated due to gas generated inside the battery, the battery is separated due to the gas pressure, gas that is harmful to the human body is prevented from leaking out of the battery, and electrolyte is prevented from leaking out of the battery.

[0034] Here, the insulator 170 may be made of a PBT (polybutylene terephthalate) material, which has good mechanical properties, particularly high rigidity, and therefore can realize a battery with excellent airtightness and durability.

[0035] The button type secondary battery 100 according to the first embodiment of the present invention may include an electrode tab 154 extending from the electrode 151 of the electrode assembly 150. The electrode tab 154 may extend from the electrode 151 of the electrode assembly 150 and contact the upper can 130. The electrode tab 154 may be a positive electrode tab. In this case, the electrode tab 154 may extend from the positive electrode of the electrode assembly 150 and contact the upper can 130.

[0036] In the button type secondary battery 100 according to the first embodiment of the present invention, the upper can 130 may include an upper can electrode terminal part 133. The upper can electrode terminal part 133 may be a part that is connected to the electrode 151 of the electrode assembly 150 via an electrode tab 154 to form a terminal that is connected to an external device. In particular, the upper can electrode terminal part 133 may be a part that covers an upper end opening of the lower can 110.

[0037] In this case, the electrode tab 154 may include a contact portion 154a that contacts the upper can electrode terminal portion 133. Specifically, the electrode tab 154 may include a support portion 154b and the contact portion 154a. The support portion 154b may be a portion that is connected to the electrode 151 of the electrode assembly 150. In the case of a positive electrode tab, the support portion 154b may be connected to the positive electrode. The connection may mean that the support portion 154b is bonded to the positive electrode, or that the support portion 154b and the positive electrode are integrally formed.

[0038] In the button type secondary battery 100 according to the first embodiment of the present invention, the support 154b may be connected to the outermost electrode 151 of the electrode assembly 150. In this case, the support 154b may come into contact with the lower can 110, which may cause a short circuit. To prevent this, the inner insulator 171 may be disposed between the electrode tab 154 and the lower can 110 so as to prevent the electrode tab 154 from coming into contact with the lower can 110. It can be seen from FIG. 2 that the support 154b and the upper end of the lower can 110 do not come into contact with each other because the inner insulator 171 is disposed therebetween.

[0039] Meanwhile, the contact portion 154a, which is a portion connected to the support portion 154b, may extend from the support portion 154b and contact the upper can electrode terminal portion 133. Specifically, an upper surface of the contact portion 154a may contact a lower surface of the upper can 130. In this case, the entire upper surface of the contact portion 154a may contact the lower surface of the upper can 130. Due to this contact, a current may flow between the electrode tab 154 and the upper can 130.

[0040] FIG. 3 shows only the electrode assembly 150 and the electrode tab 154 in the button type secondary battery 100 according to the first embodiment of the present invention. Referring to FIG. 3, the support portion 154b may be formed in a bar shape. Here, it may preferably mean various bar shapes. That is, it may be a thin cylindrical bar shape, or may be a rectangular prism bar shape or a triangular prism bar shape. And the contact portion 154a may be formed in a ring shape. The ring shape may mean the overall shape of the contact portion 154a. That is, the cross-sectional shape of the ring does not necessarily have to be a circle, and may be various shapes such as a square or a triangle. However, the cross-section may extend along a closed curve to form a ring shape overall. And the upper surface of the ring-shaped contact portion 154a may be a portion that contacts the upper can 130. In particular, the contact portion 154a may contact the upper can electrode terminal portion 133.

[0041] The contact portion 154a contacts the upper can 130 means that the contact portion 154a and the upper can 130 are not bonded to each other. It may simply mean that they are in contact with each other. In other words, it may mean that when the upper can 130 rotates, the upper can 130 and the contact portion 154a simply move relative to each other while in contact with each other, and the rotation of the upper can 130 does not act to rotate the contact portion 154a.

[0042] Conventionally, batteries have generally been manufactured by welding the electrode tab 154 to the upper can electrode terminal portion 133. That is, the electrode tab 154 is attached to the upper can 130. However, this method has a problem in that the electrode tab 154 is twisted and broken when the upper can 130 is turned to screw the upper can 130 and the lower can 110 together.

[0043] However, such a problem does not occur in the button secondary battery 100 according to the first embodiment of the present invention. In the present invention, since the electrode tab 154 is simply in contact with the upper can 130, even if the upper can 130 is rotated, the electrode tab 154 does not rotate in place.

[0044] In the button-type secondary battery 100 according to the first embodiment of the present invention, the contact portion 154a is formed in a ring shape to increase the contact area with the upper can 130. This reduces resistance and allows for a smooth current flow.

[0045] Another method for further increasing the contact area is to thicken the annular contact portion 154a. Here, the thickness can be expressed as the difference between the inner diameter and the outer diameter of the annulus. As an example of thickening the contact portion 154a, the thickness of the contact portion 154a can be made thicker than the thickness of the support portion 154b.

[0046] Furthermore, in the present invention, the outer diameter of the contact portion 154a formed in a ring shape and the outer diameter of the electrode assembly 150 may have sizes corresponding to each other. In this case, the diameter of the contact portion 154a is maximized, which means that a battery with the lowest resistance can be manufactured for the same thickness.

[0047] In addition, the contact portion 154a may be shaped in another way to reduce the resistance. Specifically, the support portion 154b may be shaped in a bar, and the contact portion 154a may be shaped in a disk. If the contact portion 154a is shaped in a disk, it can come into surface contact with the upper can, thereby further increasing the contact area and further reducing the resistance.

[0048] Meanwhile, although not shown in the drawing, an insulating plate may be provided between the contact portion 154a and the upper surface of the electrode assembly 150. If the electrode tab 154 is a positive electrode tab, a short circuit may occur when the lower surface of the contact portion 154a comes into contact with the negative electrode of the electrode assembly 150, but the insulating plate can prevent this. The insulating plate may be formed in a disk-shaped plate and may have a diameter corresponding to the diameter of the electrode assembly 150. Alternatively, the diameter of the insulating plate may have a size corresponding to the diameter of the contact portion 154a.

[0049] In the button-type secondary battery 100 according to the first embodiment of the present invention, the other electrode tab of the electrode assembly 150 may be connected to the lower can 110 by welding. The electrode tab connected to the lower can 110 is not configured to rotate by screwing, so there is no problem even if it is connected to the lower can 110 by welding. That is, unlike when the electrode tab is connected to the upper can 130 by a contact method, it can be connected by a bonding method.

[0050] Meanwhile, in the button-type secondary battery 100 according to the first embodiment of the present invention, a central hole 153 may be formed in the center of the electrode assembly 150. A center pin 190 may be provided in the central hole 153 so as to fill the central hole 153. When the center pin 190 is formed to fill the central hole 153, the electrode assembly 150 can be prevented from being deformed. When the battery reaction proceeds, the core part of the electrode assembly 150, which has a particularly weak supporting force, may be deformed due to the generated internal heat and internal gas, and when the core part is deformed in this way, the separator 152 separating the positive electrode and the negative electrode may be deformed, which may cause a short circuit accident such as the positive electrode and the negative electrode coming into contact with each other. However, in the present invention, the center pin 190 is provided so as to fill the central hole 153, so that the occurrence of such a short circuit accident can be prevented in advance.

[0051] Second embodiment FIG. 4 is a cross-sectional view showing a button-type secondary battery according to a second embodiment of the present invention. The second embodiment of the present invention differs from the first embodiment in that the configuration of the upper can end 231 is formed differently.

[0052] The second embodiment will be described by focusing on the differences and omitting the contents common to the first embodiment as much as possible. In other words, it is clear that the contents not explained in the second embodiment can be regarded as the contents of the first embodiment, if necessary.

[0053] 4, in the button secondary battery 200 according to the second embodiment of the present invention, the end 231 of the upper can may be bent in the direction of the central axis of the lower can 110. When the end 231 of the upper can is bent in this manner, the bonding strength between the upper can 130 and the lower can 110 may be significantly improved. A method for manufacturing the button secondary battery 200 according to the second embodiment of the present invention may include a method in which the upper can 130, which is not bent at first, is rotated and screwed to the lower can 110, and after the screwing is completed, the end 231 of the upper can is bent in the direction of the central axis of the lower can 110.

[0054] 4 shows that the end 273a of the outer insulator extends further downward than the end 231 of the upper can. That is, the outer insulator 273 extends downward along the outer wall of the lower can 110, and in this case, the end 273a of the outer insulator may extend further downward than the end 231 of the upper can. This can enhance the effect of preventing short circuits between the upper can 130 and the lower can 110.

[0055] In addition, the end 273a of the outer insulator may extend long enough to surround the lower edge of the lower can so as to contact the bottom of the lower can. If the end 273a of the outer insulator extends long in this manner, the effect of preventing short circuits between the upper can 130 and the lower can 110 can be further improved.

[0056] Also, the surface of the upper can end 231 that contacts the outer insulator 273 may be a flat surface. This can prevent the upper can end 231 from damaging the outer insulator 273. If the upper can end 231 is not flat but has a protruding shape, the surface that contacts the outer insulator 273 may be dented or punched out when the upper can end 231 is pressurized and bent to contact the outer insulator 273. However, in the present invention, the upper can end 231 is flat, so that such problems can be prevented from occurring.

[0057] Although the present invention has been described above using limited embodiments and drawings, the present invention is not limited thereto, and various implementations are possible within the scope of the technical concept of the present invention and the scope of the claims described below by a person having ordinary knowledge in the technical field to which the present invention belongs. [Explanation of symbols]

[0058] 100: Button type secondary battery 110: Lower can 111: 1st thread 130: Upper can 131: Upper can end 132: 2nd thread 133: Upper can electrode terminal 150: Electrode assembly 151: Electrode 152: Separator 153: Center hole 154: Electrode tab 154a: Contact part 154b: Support part 170: Insulator 171: Inner insulation 172: Interconnect insulator 173: Outer insulation 173a: Outer insulation termination 190: Center pin 200: Button type secondary battery 231: Upper can end 273a: Outer insulation termination

Claims

1. A button-type secondary battery having a diameter greater than its height, An electrode assembly; a lower can into which the electrode assembly is inserted and having a first thread formed on an outer circumferential surface; an upper can covering an upper end opening of the lower can and having a second thread formed on an inner circumferential surface thereof, the second thread corresponding to the first thread; an insulator interposed between the upper can and the lower can to prevent a short circuit between the upper can and the lower can; Including, an electrode tab extending from an electrode of the electrode assembly contacts the upper can; The upper can is an upper can electrode terminal part that is connected to the electrode of the electrode assembly through the electrode tab to form a terminal connected to an external device and covers an upper opening of the lower can; The electrode tab is a support connected to the electrode of the electrode assembly; a contact portion extending from the support portion and contacting the upper can electrode terminal portion, The support portion is formed in a bar shape, The contact portion is formed in a ring shape.

2. The button secondary battery according to claim 1 , wherein the thickness of the contact portion having the annular shape is greater than the thickness of the support portion.

3. A button-type secondary battery having a diameter greater than its height, An electrode assembly; a lower can into which the electrode assembly is inserted and having a first thread formed on an outer circumferential surface; an upper can covering an upper end opening of the lower can and having a second thread formed on an inner circumferential surface thereof, the second thread corresponding to the first thread; an insulator interposed between the upper can and the lower can to prevent a short circuit between the upper can and the lower can; Including, an electrode tab extending from an electrode of the electrode assembly contacts the upper can; The upper can is an upper can electrode terminal part that is connected to the electrode of the electrode assembly through the electrode tab to form a terminal connected to an external device and covers an upper opening of the lower can; The electrode tab is a support connected to the electrode of the electrode assembly; a contact portion extending from the support portion and contacting the upper can electrode terminal portion, The support portion is formed in a bar shape and is connected to an outermost electrode of the electrode assembly, The contact portion is formed in a disk shape.

4. The button-type secondary battery according to claim 1 , wherein an outer diameter of the contact portion formed in an annular shape and an outer diameter of the electrode assembly correspond to each other.

5. The button secondary battery according to claim 1 , further comprising an insulating plate between the contact portion and the upper surface of the electrode assembly.

6. The button-type secondary battery according to claim 1 , wherein the insulator is made of a PBT (polybutylene terephthalate) material.

7. The insulator is an inner insulator located inside the lower can; an outer insulator located outside the lower can; The button secondary battery according to claim 1 , further comprising: a connecting insulator that connects the inner insulator and the outer insulator.

8. the upper can and the lower can are screw-coupled to each other by the first thread and the second thread, the outer insulator is interposed between the first thread and the second thread, 8. The button-type secondary battery according to claim 7, wherein the outer insulator has an uneven shape due to pressure exerted by the protruding shapes of the first screw thread and the second screw thread, and is sandwiched between the first screw thread and the second screw thread.

9. The button secondary battery according to claim 7 or 8, wherein the inner insulator is located between the electrode tab and the lower can so as to prevent the electrode tab and the lower can from contacting each other.

10. A central hole is formed in the center of the electrode assembly, The button secondary battery according to claim 1 , wherein a center pin is provided in the central hole so as to fill the central hole.

11. The button-type secondary battery according to claim 1 , wherein an end of the upper can is bent toward a central axis of the lower can.

12. The outer insulator extends downward along the outer wall of the lower can, 8. The button-type secondary battery according to claim 7, wherein an end of the outer insulator extends downward further than an end of the upper can.

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