Button-type secondary battery

Abstract

The present invention relates to a button secondary battery, which has a strong bond that prevents the battery from separating due to gas pressure even when excessive internal pressure is generated due to gas generated inside the battery, prevents gas harmful to the human body from leaking out of the battery, and prevents electrolyte from leaking out of the battery. The present invention also relates to a button secondary battery that can maximize battery capacity and energy density by increasing the volume ratio of an electrode assembly within the battery, and can increase production efficiency by simplifying and conveniently manufacturing the battery. 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. The electrode assembly is formed by horizontally stacking a plurality of first electrodes, separators, and second electrodes, and a first electrode tab connected to and extending from the first electrode of the electrode assembly contacts the upper can.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2020-0119622 filed on September 17, 2020 and Korean Patent Application No. 10-2021-0109101 filed on August 18, 2021, and all the contents disclosed in the documents of the Korean patent applications are incorporated herein by reference in their entirety.

[0002] The present invention relates to a button-type secondary battery. Even when excessive internal pressure is generated by gas generated inside the battery, the battery is prevented from being separated by the gas pressure, or harmful gas to the human body does not leak out of the battery, and the electrolyte does not leak out of the battery. The present invention relates to a button-type secondary battery having a strong bond, which can improve the volume ratio occupied by the electrode assembly in the battery to maximize the battery capacity and energy density, and can simplify and facilitate the battery manufacturing process to increase production efficiency.

Background Art

[0003] In recent years, as the price of energy sources has increased due to the depletion of fossil fuels and the concern about environmental pollution has been amplified, the demand for environmentally friendly alternative energy sources has become an essential and indispensable factor for future life. Therefore, research on various power generation technologies such as solar power, wind power, and tidal power has been continuously conducted, and great attention has also been paid to power storage devices such as batteries for more efficiently using the electrical energy produced in this way.

[0004] Furthermore, as the technology development and demand for electronic mobile devices and electric vehicles using batteries increase, the demand for batteries as an energy source has increased rapidly. Therefore, many studies on batteries that can meet various requirements have been conducted.

[0005] In particular, 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 in terms of materials.

[0006] Secondary batteries can be classified into cylindrical batteries and prismatic batteries in which the electrode assembly is built into a cylindrical or rectangular metal can according to the shape of the battery case, and pouch-type batteries in which the electrode assembly is built into a pouch-shaped case of an aluminum laminate sheet, etc. In recent years, in line with the trend of the gradual miniaturization of wearable devices, the importance of developing small batteries such as button-type secondary batteries has emerged.

[0007] FIG. 1 is a cross-sectional view showing a conventional button-type secondary battery. Referring to FIG. 1, the conventional button-shaped secondary battery 10 has a form in which the upper and lower housings are separated, and its shape is a shrink-fit form of an upper cylindrical can 4 and a lower cylindrical can 3. That is, the outer diameter of the lower cylindrical can 3 is slightly larger than that of the upper one, and they are in a shrink-fit form with each other. In the case of the shrink-fit form, it is the principle that the form of the button-type secondary battery is maintained by the frictional force of the fit. And, in the conventional button-shaped secondary battery, since the upper can 4 and the lower can 3 were manufactured and fitted according to the size of the internal electrode assembly 1, there was some extra space inside.

[0008] However, in such a form, when the internal pressure increases due to gas generation inside, etc., since there is no force fixing it other than the frictional force, there was a high possibility that the upper can 4 and the lower can 3 would be separated. When the internal pressure rises, it may rise due to side reactions, but it can also rise during the progress of general cycles. At this time, if the internal pressure rises excessively, the upper can and the lower can are separated and cannot function as a battery. Therefore, it was a situation where research on products that are joined by strong bonds and in which the upper and lower cans cannot be separated was necessary.

[0009] Referring to FIG. 1, conventionally, the electrode assembly 1 inside the battery was a jelly-roll-shaped electrode assembly manufactured by winding an electrode and a separator. Such an electrode assembly 1 was arranged with the winding axis perpendicular to the ground. By the way, when the battery was formed in this way, a central hole was formed in the center of the electrode assembly by a winding core, which was a tool for winding. That is, a space where electricity was not produced was formed in the center of the electrode assembly. This was small in size and restrictive, and in a button-type battery widely used in the wearable device market, it could be an inefficient factor. Therefore, research was needed to ensure improved capacity.

Summary of the Invention

Problems to be Solved by the Invention

[0010] The present invention was made to solve the above problems, and the problem of the present invention was that even if excessive internal pressure was generated by gas generated inside the battery, the battery was not separated by gas pressure, or harmful gas to the human body did not leak outside the battery, and there was a strong bond to prevent the electrolyte from leaking outside the battery, and the volume ratio occupied by the electrode assembly in the battery was improved to maximize the battery capacity and energy density, and to provide a button-type secondary battery that could simplify and facilitate the manufacturing process of the battery and increase production efficiency.

Means for Solving the Problems

[0011] The button-type secondary battery according to the present invention relates to a button-type secondary battery whose diameter length is larger than its height, and includes an electrode assembly, a lower can into which the electrode assembly is inserted and a first thread is formed on the outer peripheral surface, an upper can that covers the upper end opening of the lower can and a second thread corresponding to the first thread is formed on the inner peripheral surface, 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. The electrode assembly is formed by horizontally laminating a plurality of first electrodes, a separator, and a second electrode, and a first electrode tab connected to and extending from the first electrode of the electrode assembly is in contact with the upper can.

[0012] The upper can is connected to the first electrode of the electrode assembly via the first electrode tab to form a terminal connected to an external device, and includes an upper can electrode terminal portion that covers the upper end opening of the lower can. The first electrode tab can include a support portion connected to a plurality of first electrodes of the electrode assembly, and a contact portion extending from the support portion and contacting the upper can electrode terminal portion.

[0013] The first electrode includes a first electrode base portion on which an electrode active material is coated on an electrode current collector, and a first electrode non-coated portion that extends laterally from the first electrode base portion and on which no electrode active material is coated and that consists only of the electrode current collector. The support portion can be connected to a plurality of first electrode non-coated portions.

[0014] A plurality of first electrode non-coated portions are joined to each other to form a first electrode non-coated portion bundle, and the support portion can be connected to the first electrode non-coated portion bundle. The support portion can be formed in a bar shape, and the contact portion can be formed in an annular shape.

[0015] The thickness of the contact portion having an annular shape may be even thicker than the thickness of the support portion. The support portion can be formed in a bar shape, and the contact portion can be formed in a disc shape.

[0016] The outer peripheral diameter of the contact portion formed in an annular shape and the outer peripheral diameter of the electrode assembly can have corresponding sizes. The insulator may be made of PBT (polybutylene terephthalate) material.

[0017] The insulator can 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.

[0018] The upper can and the lower can are screwed together by a first thread and a second thread. The outer insulator is interposed between the first thread and the second thread. The outer insulator is pressed by the protruding shapes of the first thread and the second thread to have an uneven shape and may be sandwiched between the first thread and the second thread.

[0019] The inner insulator can be positioned between the first electrode tab and the lower can so as to prevent the first electrode tab from contacting the lower can. The separator may be an SRS (safety reinforced separator) single-sided coated separator.

[0020] The plurality of first electrodes, the separator, and the second electrode may have a circular shape, be horizontally laminated, and the entire laminate may be joined vertically by heat and pressure. The outermost first electrode disposed on the outermost side of the electrode assembly may be in contact with the lower surface of the first electrode tab.

[0021] The outermost first electrode disposed on the outermost side of the electrode assembly may be in contact with the lower surface of the contact portion. The outermost first electrode may be a single-sided electrode in which the outer surface facing the upper can is not coated with the electrode active material and only the inner surface is coated with the electrode active material.

[0022] The end of the upper can may be bent in the central axis direction 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 further downward and longer than the end of the upper can.

Advantages of the Invention

[0023] The button-type secondary battery according to the present invention relates to a button-type secondary battery in which the length of the diameter is larger than the 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 upper end 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 short circuit between the upper can and the lower can. The electrode assembly is formed by horizontally laminating a plurality of first electrodes, a separator, and a second electrode, and a first electrode tab connected to and extending from the first electrode of the electrode assembly is in contact with the upper can. Thereby, even if excessive internal pressure is generated by the gas generated inside the battery, the battery is separated by the gas pressure, or harmful gas to the human body does not leak outside the battery, and a strong bond is provided to prevent the electrolyte from leaking outside the battery. The volume ratio of the electrode assembly in the battery can be improved to maximize the battery capacity and energy density, and the manufacturing process of the battery can be made simple and convenient to increase the production efficiency.

Brief Description of the Drawings

[0024]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0025] Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail so that those having ordinary knowledge in the technical field to which the present invention pertains can easily implement it. However, the present invention may be realized in various different forms and is not limited or restricted by the following embodiments.

[0026] To clearly explain the present invention, detailed descriptions of parts not related to the explanation or of related known technologies that may unnecessarily obscure the gist of the present invention are omitted. In this specification, when attaching reference numerals to the components of each drawing, the same or similar reference numerals shall be attached to the same or similar components throughout the specification.

[0027] Also, the terms and words used in this specification and the claims should not be construed as being limited to their ordinary or dictionary meanings. In accordance with the principle that the inventors can appropriately define the concepts of the terms in order to explain their invention in the best way, they should be construed in meanings and concepts consistent with the technical idea of the present invention.

[0028] First Embodiment FIG. 2 is a cross-sectional view showing a button-type secondary battery according to the first embodiment of the present invention. FIG. 3 is a perspective view separately showing only the electrode assembly and the first electrode tab in the button-type secondary battery according to the first embodiment of the present invention shown in FIG. 2. FIG. 4 is a plan view separately showing only the first electrode and the second electrode in the button-type secondary battery according to the first embodiment of the present invention.

[0029] Referring to FIG. 2, the button-type secondary battery 100 according to the first embodiment of the present invention may be a battery having a cylindrical shape, or may be in a form in which the diameter length of the cylindrical battery is even larger than the height of the battery. And the button-type secondary battery 100 according to the first embodiment of the present invention can include an electrode assembly 150, a lower can 110, and an upper can 130. The electrode assembly 150 can be formed by alternately arranging electrodes 151, 152 and a separator. In particular, the electrode assembly 150 can be formed by horizontally laminating a plurality of first electrodes 151, a separator 153, and a second electrode 152.

[0030] And the electrode assembly 150 can be inserted into the lower can 110. The lower can 110 may be in a form with an open upper end in a cylindrical shape. The electrode assembly 150 may be in the form of a laminate in which disk-shaped electrodes 151, 152 and a separator 153 are laminated (see FIGS. 3 and 4). When the electrode assembly 150 is disposed in the lower can 110, the first electrode 151 and the second electrode 152 of the electrode assembly 150 can be disposed in a form horizontal to the ground.

[0031] In the button-type 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 peripheral surface. And the upper can 130 may be in a form that covers the upper end opening of the lower can 110. A second thread 132 corresponding to the first thread 111 may be formed on the inner peripheral surface of the upper can 130. The first thread 111 and the second thread 132 may be in a relationship of screwing together when the upper can 130 and the lower can 110 are joined. That is, when covering and joining the upper can 130 to the lower can 110, instead of simply pressing and joining them, the upper can 130 can be rotated relative to the lower can 110 so as to be screwed together. When the upper can 130 makes a relative rotational movement with respect to the lower can 110, the first thread 111 and the second thread 132 will be screwed together, and the upper can 130 and the lower can 110 will approach each other. When the screwing connection is completed, a button-type secondary battery 100 in which the upper can 130 and the lower can 110 are completely joined can be manufactured. FIG. 2 shows a state in which the screwing connection between the upper can 130 and the lower can 110 is completed.

[0032] An insulator 170 is interposed between the upper can 130 and the lower can 110 of the button-type secondary battery 100 according to the first embodiment of the present invention 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.

[0033] The insulator 170 can be interposed over the upper end portion of the lower can 110. That is, the connecting insulator 172 can be positioned in a form that covers the upper end portion of the lower can 110, and the inner insulator 171 can be positioned so as to contact the inner periphery of the upper end portion of the lower can. Also, the outer insulator 173 can be positioned so as to contact the outer periphery of the upper end portion of the lower can 110. And the outer insulator 173 can be formed to be even longer than the inner insulator 171.

[0034] 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. However, the outer insulator 173 is interposed between the first thread 111 and the second thread 132. The outer insulator 173 has a concavo-convex shape due to being pressed 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.

[0035] On the other hand, the end 131 of the upper can may have the same height as the end 173a of the outer insulator (see FIG. 2), or the end 173a of the outer insulator may have a lower height than the end 131 of the upper can. That the end 173a of the outer insulator has a lower height than the end 131 of the upper can may mean that the end 173a of the outer insulator is located closer to the bottom surface of the lower can 110 than the end 131 of the upper can.

[0036] The process of connecting the upper can 130 and the lower can 110 is as follows. First, place the lower can 110 with the electrode assembly 150 inserted therein, and the insulator 170 can be connected to the lower can 110 in a manner that covers the upper end of the lower can 110. The connecting insulator 172 is positioned to cover the upper end of the lower can 110, the inner insulator 171 is in contact with the inner periphery of the upper end of the lower can, and the outer insulator 173 is in contact with the outer periphery of the upper end of the lower can 110. In this state, the insulator 170 can be connected to the lower can 110. Then, the upper can 130 can be rotated and connected thereon. That is, the inner peripheral surface of the upper can 130 can be in contact with the outer peripheral surface of the outer insulator 173 and rotate to be screwed together. In this process, since the first thread 111 and the second thread 132 form a protruding helix, the outer insulator 173 can have a concavo-convex shape due to being pressed by the protruding shapes of the first thread 111 and the second thread 132. In FIG. 2, it is shown that the outer thread has a concavo-convex shape.

[0037] Since this involves applying a very strong pressure for bonding, the upper can 130 is prevented from being easily separated from the lower can 110, enabling a firm bond. As a result, even if excessive internal pressure is generated by the gas generated inside the battery, the battery will not be separated by the gas pressure, or harmful gas to the human body will not leak outside the battery, and the electrolyte can be prevented from leaking outside the battery.

[0038] Here, the insulator 170 may be made of PBT (polybutylene terephthalate) material. In the case of PBT material, since it has good mechanical properties and particularly high rigidity, a battery with excellent airtightness and durability can be realized.

[0039] The button-type secondary battery 100 according to the first embodiment of the present invention may include a first electrode tab 154 extending from the first electrode 151 of the electrode assembly 150. The first electrode tab 154 may extend from the first electrode 151 of the electrode assembly 150 and contact the upper can 130. At this time, the first electrode 151 may be a positive electrode, and the first electrode tab 154 may be a positive electrode tab. In this case, the first electrode tab 154 may extend from the positive electrode of the electrode assembly 150 and contact the upper can 130.

[0040] 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 portion 133. The upper can electrode terminal portion 133 may be a portion that is connected to the first electrode 151 of the electrode assembly 150 via the first electrode tab 154 and forms a terminal (particularly a positive electrode terminal) connected to an external device. In particular, the upper can electrode terminal portion 133 may be a portion that covers the upper end opening of the lower can 110.

[0041] At this time, the first electrode tab 154 can include a contact portion 154a that contacts the upper can electrode terminal portion 133. Specifically, the first electrode tab 154 can include a support portion 154b and a contact portion 154a. The support portion 154b may be a portion connected to the plurality of first electrodes 151 of the electrode assembly. When the first electrode is a positive electrode, the support portion 154b can be connected to the positive electrode. The connection may mean that the support portion 154b is adhered to the first electrode (positive electrode), or that the support portion 154b and the first electrode (positive electrode) are integrally formed.

[0042] In the button-type secondary battery 100 according to the first embodiment of the present invention, the support portion 154b can be connected to the first electrode 151 of the electrode assembly 150. However, in this case, there is a risk of a short circuit accident due to the contact between the support portion 154b and the lower can 110. To prevent this, the inner insulator 171 can be positioned between the first electrode tab 154 and the lower can 110 so as to prevent the first electrode tab 154 and the lower can 110 from contacting each other. In FIG. 2, since the support portion 154b and the upper end portion of the lower can 110 have the inner insulator 171 therebetween, it can be seen that they do not contact each other.

[0043] On the other hand, the contact portion 154a, which is a portion connected to the support portion 154b, may extend from the support portion 154b and be a portion that contacts the upper can electrode terminal portion 133. Specifically, the upper surface of the contact portion 154a can contact the lower surface of the upper can 130. In this case, the entire upper surface of the contact portion 154a may be in contact with the lower surface of the upper can 130. Due to such contact, current can flow between the first electrode tab 154 and the upper can 130.

[0044] FIG. 3 shows only the electrode assembly 150 and the first 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 can be formed in a bar shape. Here, preferably, it can mean various rod shapes. That is, it may be a thin rod shape with a cylindrical shape, and in addition to this, it may be a rod shape with a quadrangular prism shape or a rod shape with a triangular prism shape. And the contact portion 154a may be formed in an annular shape. The annular shape can mean the overall shape of the contact portion 154a. That is, the cross-sectional shape of the annulus does not necessarily have to be a circle, and it may be various shapes such as a quadrilateral or a triangle. However, its cross-section extends along a closed curve and can form an annular shape as a whole. And the upper surface of the annular contact portion 154a may be the portion that contacts the upper can 130. In particular, the contact portion 154a can contact the upper can electrode terminal portion 133.

[0045] That the contact portion 154a contacts the upper can 130 means that the contact portion 154a and the upper can 130 are not adhered to each other. It can simply mean that they are in contact. That is, when the upper can 130 rotates, the upper can 130 and the contact portion 154a only move relative to each other in a state of being in contact with each other, and it can mean that the rotation of the upper can 130 does not act to rotate the contact portion 154a.

[0046] Conventionally, generally, the battery was manufactured by a method of adhering the first electrode tab 154 to the upper can electrode terminal portion 133 by welding. That is, the first electrode tab 154 was adhered to the upper can 130. By the way, in this method, when turning the upper can 130 to screw-couple the upper can 130 and the lower can 110, a problem occurs that the first electrode tab 154 is twisted and broken.

[0047] However, in the button-type secondary battery 100 according to the first embodiment of the present invention, such a problem does not occur. In the present invention, since the first electrode tab 154 is configured to simply contact the upper can 130, even when the upper can 130 is turned, the first electrode tab 154 does not rotate on the spot.

[0048] In the button-type secondary battery 100 according to the first embodiment of the present invention, the contact portion 154a can be formed in an annular shape to increase the contact area with the upper can 130. As a result, the resistance is reduced and a smooth current flow is possible.

[0049] Also, as a method of further increasing the contact area, there may be a method of increasing the thickness of the contact portion 154a having an annular shape. Here, the thickness can be expressed as the difference between the inner diameter and the outer diameter of the ring. As an example of increasing the thickness of the contact portion 154a, the thickness of the contact portion 154a can be made even thicker than the thickness of the support portion 154b.

[0050] Furthermore, in the present invention, the outer peripheral diameter of the contact portion 154a formed in an annular shape and the outer peripheral diameter of the electrode assembly 150 can have corresponding sizes. In this case, since it means that the diameter of the contact portion 154a becomes maximally large, a battery with the lowest resistance can be manufactured with the same thickness.

[0051] In addition to this, in order to reduce the magnitude of the resistance, the shape of the contact portion 154a may be realized in other shapes. Specifically, the support portion 154b may be formed in a bar shape, and the contact portion 154a may be formed in a disc shape. When formed in a disc shape, surface contact with the upper can can be achieved, so that the contact area can be further increased and the resistance can be further reduced.

[0052] In the button-type secondary battery according to the first embodiment of the present invention, specifically, the electrode assembly 150 can include a first electrode 151, a separator 153, and a second electrode 152. A plurality of the first electrodes 151, the separator 153, and the second electrodes 152 can be horizontally stacked and formed.

[0053] Referring to FIGS. 2 and 4, the first electrode 151 can include a first electrode base portion 151a on which an electrode active material is coated on an electrode current collector, and a first electrode non-base portion 151b that extends laterally from the first electrode base portion 151a and consists only of the electrode current collector without the electrode active material being coated thereon. The first electrode base portion 151a may have a thin disk shape that is circular in a plan view.

[0054] The first electrode non-base portion 151b may have a rectangular shape and extend beside the first electrode base portion 151a. The first electrode non-base portion 151b may be one in which the electrode current collector extends.

[0055] In the same manner, the second electrode 152 can include a second electrode base portion 152a on which an electrode active material is coated on an electrode current collector, and a second electrode non-base portion 152b that extends laterally from the second electrode base portion 152a and consists only of the electrode current collector without the electrode active material being coated thereon. The second electrode base portion 152a may have a thin disk shape that is circular in a plan view.

[0056] The second electrode non-base portion 152b may have a rectangular shape and extend beside the second electrode base portion 152a. The second electrode non-base portion 152b may be one in which the electrode current collector extends.

[0057] In the button-type secondary battery according to the first embodiment of the present invention, the support portion 154b of the first electrode tab 154 can be connected to a plurality of the first electrode non-base portions 151b.

[0058] In particular, as shown in FIG. 2, a plurality of the first electrode non-base portions 151b can be joined to each other to form a first electrode non-base portion bundle 151c, and here, the support portion 154b may be connected to the first electrode non-base portion bundle 151c.

[0059] By manufacturing the button-type secondary battery according to the first embodiment of the present invention in such a shape, the volume ratio occupied by the electrode assembly 150 in the battery can be improved, and the battery capacity and energy density can be maximized.

[0060] Specifically, conventionally, the electrode assembly 150 inside the battery is a jelly roll-shaped electrode assembly 150 manufactured by winding an electrode and a separator, and such an electrode assembly 150 has a central hole formed at the center of the electrode assembly by a core which is a tool for winding. As a result, a space where electricity is not produced is formed at the center of the electrode assembly 150.

[0061] In contrast, the present invention can eliminate waste space such as such a central hole, so that the battery capacity and energy density can be maximized. And, in the electrode assembly 150 of the button-type secondary battery according to the first embodiment of the present invention, the separator 153 may be an SRS (safety reinforced separator) single-sided coated separator. The SRS separator may mean that the surface of the separator 153 is thinly coated with a ceramic material. When using an SRS single-sided coated separator, a thinner separator 153 can be used, and for this reason, more electrodes can be stacked, so that it is possible to ensure a further increased battery capacity.

[0062] And, in the button-type secondary battery according to the first embodiment of the present invention, the plurality of first electrodes 151, the separator 153, and the second electrode 152 have a circular shape and are horizontally stacked, but the entire stacked body may be joined vertically by heat and pressure. That is, the stacked body can exist in the form of a single unit by adhesion. In this case, since the first electrode 151 and the second electrode 152 do not move relative to each other, a short circuit can be prevented, and the effect that the electrode assembly 150 can be stably maintained can be obtained.

[0063] And, in the button-type secondary battery according to the first embodiment of the present invention, another electrode tab of the electrode assembly 150 is the second electrode tab 156, and the second electrode tab 156 can be connected to the second electrode 152. The second electrode 152 also includes a second electrode grounded portion 152a and a second electrode ungrounded portion 152b, and the second electrode tab 156 can be connected to a plurality of second electrode ungrounded portions 152b.

[0064] And the method of connecting the second electrode tab 156 to the lower can 110 may be by welding. Since the second electrode tab 156 connected to the lower can 110 is not configured to rotate by screw connection, there will be no problem even if it is connected to the lower can 110 by welding. That is, different from the case of connecting the first electrode tab 154 to the upper can 130 in a contacting manner, the second electrode tab 156 can be connected by a joining method.

[0065] Second Embodiment FIG. 5 is a cross-sectional view showing a button-type secondary battery according to the second embodiment of the present invention. In the second embodiment of the present invention, it is different from the first embodiment in that the form of the end 231 of the upper can is formed differently, and the outermost first electrode 251-1 contacts the upper can 130.

[0066] The content common to the first embodiment will be omitted as much as possible, and the second embodiment will be described centering on the differences. That is, it is obvious that the content not described in the second embodiment will be regarded as the content of the first embodiment when necessary.

[0067] Referring to FIG. 5, in the button-type secondary battery 200 according to the second embodiment of the present invention, the end 231 of the upper can may be bent in the central axis direction of the lower can 110. When the end 231 of the upper can is bent in this way, the bonding force between the upper can 130 and the lower can 110 can be further significantly improved. The method of manufacturing the button-type secondary battery 200 according to the second embodiment of the present invention may be a method of first turning the non-bent upper can 130 and screwing it to the lower can 110, and then bending the end 231 of the upper can in the central axis direction of the lower can 110 after the screw connection is completed.

[0068] Figure 5 shows a state where 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 at this time, the end 273a of the outer insulator may extend further downward than the end 231 of the upper can. Thereby, the effect of preventing short - circuit between the upper can 130 and the lower can 110 can be enhanced.

[0069] Also, 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. When the end 273a of the outer insulator extends further in this way, the effect of preventing short - circuit between the upper can 130 and the lower can 110 can be further increased.

[0070] And the surface where the end 231 of the upper can contacts the outer insulator 273 may be a flat surface. Thereby, it can be prevented that the end 231 of the upper can damages the outer insulator 273. If the end 231 of the upper can has a protruding shape instead of being flat, in the process where the end 231 of the upper can is pressurized and bent to contact the outer insulator 273, the contacting surface of the outer insulator 273 may be indented or penetrated. However, in the present invention, since the end 231 of the upper can is flat, such problems can be prevented from occurring.

[0071] And, as shown in FIG. 5, in the button-type secondary battery 200 according to the second embodiment of the present invention, the outermost first electrode 251-1 disposed on the outermost side of the electrode assembly 150 may be in contact with the lower surface of the first electrode tab 254. That is, the upper surface of the outermost first electrode 251-1 can be in contact with the lower surface of the first electrode tab 254. In particular, the upper surface of the outermost first electrode 251-1 may be in contact with the lower surface of the contact portion 254a of the first electrode tab 254. Here, since the outermost first electrode 251-1 and the contact portion 254a have the same polarity, contacting each other does not cause a problem. When the outermost first electrode 251-1 and the first electrode tab 254 are formed to be in contact with each other in this way, the space efficiency can be further improved. That is, the energy density can be further improved. And when the contact area becomes wider, the resistance can be reduced. And since the electrode assembly 150 can be completely prevented from shaking inside the battery, a more stable button-type secondary battery 200 can be realized.

[0072] Also, the bundle 251c of the first electrode non-coated portions where the first electrode non-coated portions are gathered can also be formed to be in contact with the first electrode tab 254. And, as shown in FIG. 5, the bundle 251c of the first electrode non-coated portions may be formed to be in contact with the lower surface of the contact portion 254a. Such a structure can also further improve the energy density.

[0073] And, in the button-type secondary battery 200 according to the second embodiment of the present invention, the outermost first electrode 251-1 may be a single-sided electrode in which the outer surface facing the upper can is not coated with the electrode active material and only the inner surface is coated with the electrode active material.

[0074] Since there are no corresponding second electrodes on the upper surface of the outermost first electrode 251-1, even if there is an electrode active material, it will be a non-reactive part. Therefore, if this non-reactive electrode active material is removed, that is, if the outermost first electrode 251-1 is configured as a single-sided electrode, the energy density can be further improved. This is because it is possible to prevent waste of space in the non-reactive part. And since waste of the electrode active material can be prevented, production costs can be reduced. Also, when the electrode current collector and the upper can are in direct contact, an effect of reducing resistance can also be obtained.

[0075] As described above, the present invention has been described with reference to the limited embodiments and drawings. However, the present invention is not limited thereto, and various implementations are possible within the scope equivalent to the technical idea of the present invention and the scope of the following claims by those having ordinary knowledge in the technical field to which the present invention pertains.

Explanation of Reference Numerals

[0076] 100: Button-type secondary battery 110: Lower can 111: First thread 130: Upper can 131: End of the upper can 132: Second thread 133: Upper can electrode terminal part 150: Electrode assembly 151: First electrode 151a: Grounded part of the first electrode 151b: Non-grounded part of the first electrode 151c: Bundle of non-grounded parts of the first electrode 152: Second electrode 152a: Grounded part of the second electrode 152b: Non-grounded part of the second electrode 153: Separator 154: First electrode tab 154a: Contact part 154b: Support part 156: Second electrode tab 170: Insulator 171: Inner insulator 172: Connecting insulator 173: Outer insulator 173a: End of outer insulator 200: Button-type secondary battery 231: End of upper can 251-1: Outermost first electrode 251c: First electrode plain part bundle 254a: Contact part 254b: Support part 273: Outer insulator 273a: End of outer insulator

Claims

1. A button-type secondary battery having a diameter length greater than the height, comprising: An electrode assembly; A lower can into which the electrode assembly is inserted and having a first thread formed on an outer peripheral surface thereof; An upper can covering an upper end opening of the lower can and having a second thread formed on an inner peripheral surface thereof 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; and The electrode assembly is formed by horizontally laminating a plurality of first electrodes, a separator, and a second electrode; A first electrode tab extending and connected to the first electrode of the electrode assembly contacts the upper can; The outermost first electrode disposed on the outermost side of the electrode assembly abuts against a lower surface of the first electrode tab; The upper can includes an upper can electrode terminal portion that forms a terminal connected to an external device through the first electrode of the electrode assembly and the first electrode tab and covers the upper end opening of the lower can; The first electrode tab includes a support portion connected to the plurality of first electrodes of the electrode assembly; and 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 an annular shape, a button-type secondary battery.

2. A button-type secondary battery having a diameter length greater than the height, comprising: An electrode assembly; A lower can into which the electrode assembly is inserted and having a first thread formed on an outer peripheral surface thereof; An upper can covering an upper end opening of the lower can and having a second thread formed on an inner peripheral surface thereof 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; and The electrode assembly is formed by horizontally laminating a plurality of first electrodes, separators, and second electrodes. A first electrode tab that is connected to and extends from the first electrode of the electrode assembly contacts the upper can. The outermost first electrode disposed on the outermost side of the electrode assembly abuts against the lower surface of the first electrode tab. The upper can forms a terminal that is connected to an external device through the first electrode of the electrode assembly and the first electrode tab, and includes an upper can electrode terminal portion that covers the upper end opening of the lower can. The first electrode tab includes a support portion connected to the plurality of first electrodes of the electrode assembly, and a contact portion that extends from the support portion and contacts the upper can electrode terminal portion. The support portion is formed in a bar shape. The contact portion is formed in a disc shape, a button-type secondary battery.

3. The first electrode includes a first electrode base portion on which an electrode active material is applied to an electrode current collector, and a first electrode non-coated portion that extends laterally from the first electrode base portion and on which the electrode active material is not applied and that consists only of the electrode current collector. The support portion is connected to the plurality of first electrode non-coated portions, the button-type secondary battery according to claim 1 or 2.

4. The plurality of first electrode non-coated portions are joined to each other to form a first electrode non-coated portion bundle. The support portion is connected to the first electrode non-coated portion bundle, the button-type secondary battery according to claim 3.

5. The thickness of the contact portion having the annular shape is further thicker than the thickness of the support portion, the button-type secondary battery according to claim 1.

6. The outer peripheral diameter of the contact portion formed in the annular shape and the outer peripheral diameter of the electrode assembly have corresponding sizes, the button-type secondary battery according to claim 1.

7. The button-type secondary battery according to any one of claims 1 to 6, wherein the insulator is made of PBT (polybutylene terephthalate).

8. The insulator is 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, and includes a button-type secondary battery according to any one of claims 1 to 7.

9. The upper can and the lower can are screwed together by the first thread and the second thread, the outer insulator is interposed between the first thread and the second thread, The outer insulator has a concavo-convex shape by being pressed by the protruding shapes of the first thread and the second thread, and is sandwiched between the first thread and the second thread. The button-type secondary battery according to claim 8.

10. The button-type secondary battery according to claim 8 or 9, wherein the inner insulator is located between the first electrode tab and the lower can so as to prevent the first electrode tab and the lower can from coming into contact with each other.

11. The button-type secondary battery according to any one of claims 1 to 10, wherein the separator is an SRS (safety reinforced separator) single-sided coated separator.

12. The plurality of first electrodes, the separator, and the second electrode have a circular shape, are horizontally laminated, and the entire laminate is joined vertically by heat and pressure. The button-type secondary battery according to any one of claims 1 to 11.

13. The outermost first electrode disposed on the outermost side of the electrode assembly abuts on the lower surface of the contact portion. The button-type secondary battery according to claim 1 or 2.

14. The outermost first electrode is a single-sided electrode in which the outer surface facing the upper can is not coated with an electrode active material, and only the inner surface is coated with an electrode active material. The button-type secondary battery according to any one of claims 1 to 13.

15. The end of the upper can is bent in the central axis direction of the lower can. The button-type secondary battery according to any one of claims 1 to 14.

16. The outer insulator extends downward along the outer wall of the lower can. At this time, The end of the outer insulator extends further downward and is longer than the end of the upper can. The button-type secondary battery according to claim 8.

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