Patent Description:
Unlike a primary battery that is incapable of being recharged, a rechargeable battery can be repeatedly charged and discharged. Low-capacity rechargeable batteries may be used for small electronic devices, such as mobile phones, laptop computers or camcorders, and large-capacity rechargeable batteries have been widely used as a power source for driving a motor, such as that of a hybrid vehicle. Such a secondary battery for electronic devices including a cap assembly, which has a minimum number of components and a simplified assembling process, for example, is disclosed in document <CIT>.

A representative rechargeable battery may include a nickel-cadmium (Ni-Cd) battery, a nickel-hydrogen (Ni-MH) battery, a lithium (Li) battery, or a lithium ion (Li-ion) rechargeable battery. Particularly, the lithium ion rechargeable battery, or secondary battery, that is mainly used as a portable electric equipment power source, has a higher operation voltage than the nickel-cadmium battery or the nickel-hydrogen battery by about three times. Also, the lithium ion secondary battery is widely used due to a high energy density per unit weight.

In particular, as a demand for wearable devices, such as headphones, earphones, smartwatches, and body-mounted medical devices which use Bluetooth has increased, the need for rechargeable batteries with high energy density and ultra-small size has been increasing.

The ultra-small rechargeable battery has important tasks of securing the required electrical capacity within a limited size, implementing an efficient structure while improving an effective low weight, and improving structural stability.

The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention, and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.

A rechargeable battery according to claim <NUM> is provided. According to an aspect of embodiments of the present invention, an ultra-small rechargeable battery is provided. According to another aspect of embodiments of the present invention, a rechargeable battery implementing an efficient structure, improving electrical capacity, improving low weight and securing structural stability is provided.

According to one or more embodiments of the present invention, a rechargeable battery includes: an electrode assembly including a first electrode, a second electrode, and a separator between the first electrode and the second electrode; a case having an opening and housing the electrode assembly; and a cap assembly sealing the opening of the case, wherein the cap assembly includes: a cap plate bonded to the case and covering the opening, a terminal plate bonded to the cap plate and a thermal fusion member between the terminal plate and the cap plate and thermally fused with the terminal plate and the cap plate.

The thermal fusion member is formed of an electrically insulating material.

In the terminal plate and the cap plate, a surface in contact with the thermal fusion member is etched such that the thermal fusion member is bonded thereto.

The rechargeable battery may further include a first electrode tab extending from the first electrode, and a second electrode tab extending from the second electrode, the case and the cap plate may be electrically connected to the first electrode through the first electrode tab, and the terminal plate may be electrically connected to the second electrode through the second electrode tab.

The cap plate may have a terminal hole, and the terminal plate may include: a tab bonding portion facing the terminal hole and bonded with the second electrode tab; and a flange portion around the tab bonding portion and bonded with the thermal fusion member.

The thermal fusion member may have a ring shape extending along the flange portion, and seals between the flange portion and the cap plate.

The terminal plate may be at an exterior side of the cap plate such that the flange portion is exposed outside.

In the terminal plate, the tab bonding portion may extend into the terminal hole, and the second electrode tab may be welded to an inside surface of the tab bonding portion through the terminal hole.

An insulating film may be disposed between the cap plate and the second electrode tab.

In the electrode assembly, the first electrode, the second electrode, and the separator may be spiral-wound around a center pin, an upper surface of the electrode assembly being arranged toward the cap assembly, a lower surface of the electrode assembly being arranged toward a bottom of the case, the first electrode tab may extend from the lower surface of the electrode assembly to be welded to a bottom of the case, and the second electrode tab may extend from the upper surface of the electrode assembly to be welded to the tab bonding portion.

The terminal hole may be at a center of the cap plate, the center pin may protrude from the upper surface of the electrode assembly toward the tab bonding portion, and the second electrode tab may be supported by an upper end of the center pin and welded to the tab bonding portion.

The cap plate may be welded to a side wall end where a rim surrounds the opening of the case.

The rechargeable battery may have a ratio of a height to a diameter of <NUM> or less.

According to an aspect of embodiments of the present invention, the rechargeable battery may be capable of realizing the effective structure, improving low weight, improving an electrical capacity, and securing the structural stability.

In the following detailed description, only certain example embodiments of the present invention are shown and described, simply by way of illustration.

The drawings and description are to be regarded as illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the specification.

In this specification, redundant description of the same constituent elements may be omitted.

Also, in this specification, it is to be understood that when one component is referred to as being "connected" or "coupled" to another component, it may be connected or coupled directly to the other component or connected or coupled to another component with one or more other components intervening there between. On the other hand, in this specification, it is to be understood that when one component is referred to as being "connected or coupled directly" to another component, it may be connected or coupled to the other component without another component intervening there between.

It is also to be understood that the terminology used herein is only for the purpose of describing particular embodiments, and is not intended to be limiting of the invention.

Singular forms are to include plural forms unless the context clearly indicates otherwise.

It is to be further understood that terms such as "comprises," "includes," or "have" used in the present specification specify the presence of stated features, numerals, steps, operations, components, parts, or a combination thereof, but do not preclude the presence or addition of one or more other features, numerals, steps, operations, components, parts, or a combination thereof.

Also, as used herein, the term "and/or" includes any plurality of combinations of items or any of a plurality of listed items. In this specification, "A or B" may include "A," "B," or "A and B".

It is to be understood that, although the terms "first," "second," etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used to distinguish one element from another. For example, a first element could be termed a "second" element, and, similarly, a second element could be termed a "first" element. The terms of a singular form may include plural forms unless the context clearly indicates otherwise.

In addition, terms such as "below," "lower," "above," "upper," and the like are used to describe the relationship of the configurations shown in the drawings. However, the terms are used as a relative concept and are described with reference to the direction indicated in the drawings.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the inventive concept pertains. It is also to be understood that terms defined in commonly used dictionaries should be interpreted as having meanings consistent with the meanings in the context of the related art, and are expressly defined herein unless they are interpreted in an ideal or overly formal sense.

Embodiments of the present invention relate to a rechargeable battery of which the size may vary; however, in one or more embodiments, an ultra-small rechargeable battery having a very small size is provided such that it may be used for headphones, earphones, smartwatches, and wearable devices.

In addition, embodiments of the present invention may be applied to various shapes and kinds of rechargeable batteries, such as square types, cylindrical types, and pin types; however, in one or more embodiments, a coin-type or button-type battery is provided. The coin-type or button-type battery has a shape of a thin coin or button and may be used as an ultra-small battery, and may be defined as a battery of which a ratio (a height/diameter) of a height (H) to a diameter (L) of the rechargeable battery is <NUM> or less.

In one or more embodiments, the coin-type or button-type battery may be cylindrical having a circular cross-sectional shape, but it is not limited thereto and may have an elliptical or polygonal cross-sectional shape.

Here, as shown in <FIG>, the diameter L refers to a maximum distance between the side surfaces of a case <NUM> where an electrode assembly <NUM> is embedded or housed, and the height H refers to a minimum distance from a flat bottom surface of the battery to a flat upper surface of the battery, and it may be understood as from the lower surface of the case <NUM> to the upper surface of the cap assembly <NUM>.

Rechargeable batteries according to embodiments of the present invention may be of various sizes, types, and shapes, but for convenience of explanation of an example embodiment of the present invention, the coin-type battery of which the cross-sectional shape is circular is described as an example.

<FIG> is a perspective view showing a rechargeable battery according to an example embodiment of the present invention; <FIG> is an exploded perspective view of the rechargeable battery of <FIG>; and <FIG> is a cross-sectional view of a rechargeable battery according to an example embodiment of the present invention.

As shown in <FIG>, a rechargeable battery according to an embodiment of the present invention includes an electrode assembly <NUM> in which a separator <NUM> is interposed between a first electrode <NUM> and a second electrode <NUM>, a case <NUM> having an opening at one side and housing the electrode assembly <NUM>, and a cap assembly <NUM> bonded to the opening and closing and sealing the case <NUM>, wherein the cap assembly <NUM> includes a cap plate <NUM> bonded to the case <NUM> and covering the opening, a terminal plate <NUM> bonded on the cap plate <NUM>, and a thermal fusion member <NUM> disposed between the terminal plate <NUM> and the cap plate <NUM> and thermally fused with the terminal plate <NUM> and the cap plate <NUM>.

The electrode assembly <NUM> includes the first electrode <NUM> and the second electrode <NUM> which may have a coated region and an uncoated region. The first electrode <NUM> may be a positive electrode and the second electrode <NUM> may be a negative electrode, or vice versa. The separator <NUM> to provide electrical insulation may be interposed between the first electrode <NUM> and the second electrode <NUM>.

In an embodiment of the present invention, the electrode assembly <NUM> may be provided in a stacked form, but, as shown in <FIG> or <FIG>, the first electrode <NUM>, the second electrode <NUM>, and the separator <NUM> may be spiral-wound together around a center pin <NUM>, thereby having a jelly-roll shape.

In an embodiment, when the electrode assembly <NUM> is a spiral-wound type, as shown in <FIG>, the electrode assembly <NUM> may have a flat upper surface and a lower surface may have a curved surface, and the center pin <NUM> may be parallel to the height direction of the rechargeable battery. That is, for the electrode assembly <NUM>, the upper surface may be arranged toward the cap assembly <NUM> and the lower surface may be arranged toward a bottom of the case <NUM>.

As shown in <FIG>, the rechargeable battery according to an embodiment of the present invention may include an insulating member <NUM> around (e.g., surrounding) the electrode assembly <NUM>. The insulating member <NUM> may be formed of an electrically insulating material to provide electrical insulation between the case <NUM> and the electrode assembly <NUM>.

In an embodiment, the first electrode <NUM> may be a negative electrode and formed in a belt shape that is elongated, and includes a negative electrode coated region as a region where a negative active material layer is coated on a current collector of a metal film (for example, a copper foil) and a negative uncoated region as a region where the active material is not coated. The negative uncoated region may be disposed at the end of a side of the negative electrode in the length direction.

In an embodiment, the second electrode <NUM> may be a positive electrode and formed in the belt shape that is elongated, and includes a positive electrode coated region as a region where a positive active material layer is coated on the current collector of a metal film (for example, an aluminum foil) and a positive electrode uncoated region as a region where the active material is not coated. The positive electrode uncoated region may be disposed at the end of a side of the positive electrode in the length direction.

The case <NUM> has an accommodation space in which the electrode assembly <NUM> is accommodated, and an opening may be formed at a side of the case <NUM>. In an embodiment of the present invention, the case <NUM> has an opening formed at an upper surface, as shown in <FIG> and <FIG>, and the electrode assembly <NUM> may be accommodated therein. The opening may be formed at the upper side or the bottom of the case <NUM>, but the following description is based on the opening being formed at the upper surface of the case <NUM>.

In an embodiment, the case <NUM> may be made of a metal material having electrical conductivity such as aluminum (Al) or stainless steel (SUS), and the shape of the case <NUM> may be varied according to a need, such as cylindrical or square, and, as an example embodiment of the present invention, <FIG> and <FIG> show the case <NUM> of a cylindrical shape in which the spiral-wound type electrode assembly <NUM> is accommodated.

As shown <FIG> and <FIG>, the cap assembly <NUM> is bonded to the opening of the case <NUM> ,and may close and seal the accommodation space of the case <NUM>. As the coupling method with the case <NUM>, any of various methods such as metal-to-metal welding, plastic welding, and bonding using a tape or an adhesive may be possible.

The cap assembly <NUM> may include the cap plate <NUM>, the terminal plate <NUM>, and the thermal fusion member <NUM>.

In an embodiment, the cap plate <NUM> is directly bonded to the case <NUM> and may be made of a metal material having electrical conductivity, such as aluminum or stainless steel, like the case <NUM>, and, as shown in <FIG>, it may be provided as a plate shape having a cross-section corresponding to the opening of the case <NUM>, but it is not limited thereto, and the material and shape thereof may be varied.

The cap plate <NUM> is bonded to the opening of the case <NUM>, and the coupling method may be any of various methods, and <FIG> shows a shape in which a circumference of the cap plate <NUM> is seated on a side wall of the case <NUM> and is mutually bonded by a manner such as welding.

The terminal plate <NUM> is bonded to the cap plate <NUM>. The terminal plate <NUM> is directly bonded to the cap plate <NUM> in an insulated state from the cap plate <NUM>; however, in an exemplary embodiment of the present invention, as shown in <FIG>, it is bonded to the cap plate <NUM> via the thermal fusion member <NUM>.

In an embodiment, the terminal plate <NUM> may be electrically connected to any one of the first electrode and the second electrode of the electrode assembly <NUM>, and may be electrically connected to a terminal provided in an external electronic device.

<FIG> is a view enlarging a region "B" in the rechargeable battery shown in <FIG>. The thermal fusion member <NUM> is disposed between the cap plate <NUM> and the terminal plate <NUM> and is thermally fused facing the cap plate <NUM> and the terminal plate <NUM>. That is, the thermal fusion member <NUM> is a medium for mutually coupling the cap plate <NUM> and the terminal plate <NUM>.

The thermal fusion member <NUM> is formed of an electrically insulating material, such as a polymer, and melted using a laser or the like to be fused to the cap plate <NUM> and the terminal plate <NUM>.

The terminal plate <NUM> is combined with the cap plate <NUM> through the thermal fusion member <NUM>, thereby forming a stable bonding structure while effectively insulating the terminal plate <NUM> and the cap plate <NUM> without adding a separate insulating configuration.

In the case of the coin-type battery, it may be manufactured to be ultra-small and have a design limitation in terms of space, and, accordingly, it is desired to secure functionality while simplifying the structure and the manufacturing process, and embodiments of the present invention are effective because the insulation and the bonding between the terminal plate <NUM> and the cap plate <NUM> is achieved together through the fusion member <NUM>.

In an embodiment of the present invention, as shown in <FIG> and <FIG>, the respective surfaces where the terminal plate <NUM> and the cap plate <NUM> are in contact with the thermal fusion member <NUM> are etched such that the thermal fusion member <NUM> is bonded.

That is, in an embodiment of the present invention, so as to improve a bonding force of the thermal fusion member <NUM> melted by a laser and the cap plate <NUM> and the terminal plate <NUM> made of a metal material, a bonding surface <NUM> with the thermal fusion member <NUM> in the terminal plate <NUM> and the cap plate <NUM> is etched.

The etching may be provided using a laser or chemicals, and the molten thermal fusion member <NUM> may penetrate into the etched bonding surface <NUM>, thereby forming a stronger bonding force.

<FIG> schematically shows a shape of which a bonding surface <NUM> to which the thermal fusion member <NUM> is bonded in the terminal plate <NUM> and the cap plate <NUM> is etched according to an embodiment of the present invention; and <FIG> schematically shows that the bonding force is increased due to the penetration of the thermal fusion member <NUM> on the etched bonding surface <NUM>, preferably comprising a plurality of indentations formed by the etching process (i.e., being roughened), thus advantageously having an increased surface area compared to a non-etched surface.

In an embodiment, the bonding surface <NUM> of the terminal plate <NUM> and the cap plate <NUM> may be coated with a metal, such as chromium, and corrosion resistance of the etched bonding surface <NUM> may be improved through this chromizing process.

In an embodiment of the present invention, a first electrode tab <NUM> extends from the first electrode <NUM> and a second electrode tab <NUM> extends from the second electrode <NUM>, and the case <NUM> and the cap plate <NUM> may be electrically connected to the first electrode <NUM> through the first electrode tab <NUM>, while the terminal plate <NUM> may be electrically connected to the second electrode <NUM> through the second electrode tab <NUM>.

The first electrode tab <NUM> extends from the first electrode <NUM> of the electrode assembly <NUM> and may be bonded to the case <NUM> or the cap plate <NUM>. <FIG> shows a shape in which the first electrode tab <NUM> is bonded to the bottom of the case <NUM> according to an embodiment of the present invention, but embodiments are not limited thereto.

The first electrode tab <NUM> may be made of a metal material having electrical conductivity and may be integrally provided with the first electrode <NUM> or separately manufactured to be bonded to the first electrode <NUM> by welding, etc., and is electrically connected to the first electrode <NUM>, thereby having the same polarity.

In an embodiment, the case <NUM>, which is bonded and electrically connected to the first electrode tab <NUM>, may have the same polarity as the first electrode <NUM>, and the cap plate <NUM>, which is bonded to the case <NUM> by welding, has the same polarity as the first electrode <NUM> along with the case <NUM>.

The second electrode tab <NUM> may extend from the second electrode <NUM> of the electrode assembly <NUM> to be bonded to the terminal plate <NUM>. The second electrode tab <NUM> may be integrally provided with the second electrode <NUM> or separately manufactured to be bonded to the second electrode <NUM> by welding, etc..

The second electrode tab <NUM> may be made of a metal material having electrical conductivity and may be electrically connected to the second electrode <NUM>, thereby having the same polarity. In addition, the terminal plate <NUM>, which is electrically connected to the second electrode tab <NUM>, may have the same polarity as the second electrode <NUM>.

The second electrode tab <NUM> and the terminal plate <NUM> may have a mutual coupling relationship using a separate media, or may be directly bonded to each other by a method such as welding, as shown in <FIG>.

Referring to <FIG>, in an embodiment, the first electrode tab <NUM> and the second electrode tab <NUM> may require electrical insulation with the case <NUM>, etc., and may be used in a form of which an electrically insulating material is coated on a surface for the electrical insulation with the case <NUM>.

In an embodiment, an insulating film <NUM> may be disposed between the cap plate <NUM> and the second electrode tab <NUM> such that the electrical insulation is provided between the cap plate <NUM> and the second electrode tab <NUM> bonded with the terminal plate <NUM>.

In an embodiment, the insulating film <NUM> may be provided on an entire inside surface of the cap plate <NUM>, and, in an embodiment, as shown in <FIG>, the insulating film <NUM> may be provided on one side facing the second electrode tab <NUM>.

Since the cap plate <NUM> electrically connected to the first electrode <NUM> through the first electrode tab <NUM> and the terminal plate <NUM> electrically connected to the second electrode <NUM> through the second electrode tab <NUM> have different polarities from each other, in order to prevent or substantially prevent a short circuit, the electrical insulation of each is provided, and, in an exemplary embodiment of the present invention, the electrical insulation between the terminal plate <NUM> and the cap plate <NUM> may be achieved through the thermal fusion member <NUM>.

In an embodiment of the present invention, a terminal hole <NUM> is formed in the cap plate <NUM>, and the terminal plate <NUM> may include a tab bonding portion <NUM> disposed to face the terminal hole <NUM> and bonded with the second electrode tab <NUM>, and a flange portion <NUM> around (e.g., enclosing) the tab bonding portion <NUM> and bonded with the thermal fusion member <NUM>.

The terminal hole <NUM> in the cap plate <NUM> may be formed in any of various sizes and shapes. The terminal plate <NUM> may have a larger diameter than the terminal hole <NUM>, and may include the tab bonding portion <NUM> facing the terminal hole <NUM> and the flange portion <NUM> around (e.g., surrounding) the tab bonding portion <NUM>.

The second electrode tab <NUM> may be bonded to the tab bonding portion <NUM>. In an embodiment, for example, when the terminal plate <NUM> is disposed on the inside surface of the cap plate <NUM>, the second electrode tab <NUM> may be welded to the tab bonding portion <NUM> by performing laser welding through the terminal hole <NUM>, and when the terminal plate <NUM> is disposed on the exterior side of <NUM>, the second electrode tab <NUM> may contact and be welded to the tab bonding portion <NUM> through the terminal hole <NUM>.

In an embodiment, the flange portion <NUM> may have the bonding surface <NUM> surrounding the tab bonding portion <NUM> and contacting the thermal fusion member <NUM>. That is, in the terminal plate <NUM>, the tab bonding portion <NUM> of the center may be bonded to the second electrode tab <NUM>, and the flange portion <NUM> of the circumference side may be bonded with the thermal fusion member <NUM>.

In the case of the coin-type battery of the ultra-small size, the size is small, such that there may be a spatial limitation in design; however even if there may be the spatial limitation as described above, in an embodiment of the present invention, as shown in <FIG>, by separately setting the tab bonding portion <NUM> and the flange portion <NUM> in the terminal plate <NUM>, a structure in which the combination between the terminal plate <NUM> and the cap plate <NUM> and the combination between the terminal plate <NUM> and the second electrode tab <NUM> are concurrently (e.g., simultaneously) possible may be effectively realized.

In an embodiment, the thermal fusion member <NUM>, as shown in <FIG>, has a ring shape extending along the flange portion <NUM> and seals between the flange portion <NUM> and the cap plate <NUM>. Due to the formation of the terminal hole <NUM>, a space between the terminal plate <NUM> and the cap plate <NUM> may communicate with an internal space of the case <NUM>, and, accordingly, a sealing structure for sealing the interior of the case <NUM> may be required.

In an embodiment of the present invention, as the thermal fusion member <NUM> has the ring shape to correspond to the flange portion <NUM> enclosing the tab bonding portion <NUM> and is disposed between the flange portion <NUM> and the cap plate <NUM>, the terminal hole <NUM> may be formed in the cap plate <NUM> and the terminal plate <NUM> may be bonded to the cap plate <NUM>, and concurrently (e.g., simultaneously) the stable sealing structure may be formed.

In an embodiment, as shown in <FIG>, the terminal plate <NUM> is disposed on the exterior side of the cap plate <NUM> such that the flange portion <NUM> may be exposed outside.

That is, the terminal plate <NUM> is disposed on the exterior side corresponding to the opposite side of the inside surface toward the electrode assembly <NUM> from the cap plate <NUM> and is exposed outside. In this case, as shown in <FIG>, the tab bonding portion <NUM> and the second electrode tab <NUM> may be bonded to each other through the terminal hole <NUM>, and the flange portion <NUM> may have the structure surrounding a periphery of the tab bonding portion <NUM>.

The tab bonding portion <NUM> may have a shape and size corresponding to the terminal hole <NUM> and the flange portion <NUM> encloses the circumference of the tab bonding portion <NUM>, thereby having a diameter that is larger than the terminal hole <NUM>.

For the terminal plate <NUM> exposed to the outside, the flange portion <NUM> may also function as a terminal as well as the tab bonding portion <NUM>. For example, when the rechargeable battery according to an embodiment of the present invention is inserted into an external electronic device, even if the terminal of the external electronic device is spaced from the tab bonding portion <NUM> to which the second electrode tab <NUM> is bonded, the terminal of the external electronic device may be in contact with the flange portion <NUM> of the terminal plate <NUM>, thereby easily using the rechargeable battery.

That is, as an embodiment of the present invention disposes the terminal plate <NUM> including the flange portion <NUM> at the outside of the cap plate <NUM>, it is possible to increase a contact area with a terminal of the external electronic device on the terminal plate <NUM>, thereby being advantageous in terms of design.

Further, in the case of ultra-small rechargeable batteries requiring precision in terms of design, for example, ultra-small coin-type batteries as described above, design precision may be required in relation to the external electronic devices, such as the terminal positions, and an embodiment of the present invention exposes the flange portion <NUM> outside, thereby being advantageous in increasing the contact area with the terminal.

In an embodiment, unlike the rechargeable battery shown in <FIG>, in the rechargeable battery of <FIG>, the tab bonding portion <NUM> of the terminal plate <NUM> is disposed parallel to the flange portion <NUM>, and <FIG> shows a cross-section of the rechargeable battery of <FIG>, taken along the line A-A, and shows a structure in which the tab bonding portion <NUM> of the terminal plate <NUM> is indented toward the terminal hole <NUM> side with respect to the flange portion <NUM>.

Referring to <FIG> and <FIG>, in an embodiment of the present invention, in the terminal plate <NUM>, the tab bonding portion <NUM> may be inserted into the terminal hole <NUM> side, and the second electrode tab <NUM> may be welded to the inside surface of the tab bonding portion <NUM> through the terminal hole <NUM>.

Referring to <FIG>, the tab bonding portion <NUM> disposed at a center side of the terminal plate <NUM> may have a shape that is recessed downward relative to the surrounding flange portion <NUM>. Accordingly, it is advantageous that a distance between the lower surface of the tab bonding portion <NUM> and the second electrode tab <NUM> may be reduced, effective welding using a laser may be performed, and the laser welding for the second electrode tab <NUM> may be performed even if the bonding between the case <NUM> and the cap plate <NUM> is preceded.

In an embodiment, in the electrode assembly <NUM>, the first electrode <NUM>, the second electrode <NUM>, and the separator <NUM> may be spiral-wound around the center pin <NUM>, an upper surface of the electrode assembly <NUM> may be arranged toward the cap assembly <NUM>, a lower surface of the electrode assembly <NUM> may be arranged toward the case <NUM>, the first electrode tab <NUM> may extend from the lower surface of the electrode assembly <NUM> to be welded to the bottom of the case <NUM>, and the second electrode tab <NUM> may extend from the upper surface of the electrode assembly <NUM> to be welded to the tab bonding portion <NUM>.

<FIG>, <FIG>, and <FIG> show the spiral-winding-type electrode assembly <NUM> in which the first electrode <NUM>, the second electrode <NUM>, and the separator <NUM> are spiral-wound around the center pin <NUM> corresponding to a winding shaft as an embodiment of the present invention. Referring to <FIG> and <FIG>, the upper surface of the electrode assembly <NUM> may be arranged toward the cap assembly <NUM>, and the lower surface of the electrode assembly <NUM> may be arranged toward the bottom of the case <NUM>.

As described above, by using the spiral-winding type of electrode assembly <NUM> of the state that the center pin <NUM> extends upward and downward, the energy density may be improved by effectively utilizing the accommodation space of the case <NUM>, and, further, it may be effective in realizing the flat and thin rechargeable battery such as the coin-type battery.

In an embodiment, the first electrode tab <NUM>, as shown in <FIG>, may extend from the lower surface of the electrode assembly <NUM>, and, accordingly it may extend and be welded to the bottom of the case <NUM> facing the lower surface of the electrode assembly <NUM> along a simple and effective path.

Also, the second electrode tab <NUM> may extend from the upper surface of the electrode assembly <NUM>, as shown in <FIG>, and may reduce the distance with the tab bonding portion <NUM> and extend along a simple and effective path to be welded to the tab bonding portion <NUM>.

In an embodiment, the terminal hole <NUM> may be disposed in the center of the cap plate <NUM>, the center pin <NUM> may be protruded from the upper surface of the electrode assembly <NUM> toward the tab bonding portion <NUM>, and the second electrode tab <NUM> may be supported by the upper end of the center pin <NUM> and welded to the tab bonding portion <NUM>.

In an embodiment of the present invention, as the terminal hole <NUM> may be disposed at the center side of the cap plate <NUM>, it is easy for the second electrode tab <NUM> supported by the center pin <NUM> to face the tab bonding portion <NUM>.

Also, in an embodiment of the present invention, the electrode assembly <NUM> may include the center pin <NUM> at the center, and the center pin <NUM> may be made of any of various materials having electrical insulation. In the center pin <NUM>, the upper end arranged toward the cap assembly <NUM> may be protruded more toward the tab bonding portion <NUM> than the upper surface of the electrode assembly <NUM>.

The second electrode tab <NUM> is supported by the upper end of the center pin <NUM>, and may be in contact with the tab bonding portion <NUM> of the terminal plate <NUM>.

That is, in an embodiment of the present invention, the tab bonding portion <NUM> has a shape that is inserted into the terminal hole <NUM> side in relation to the flange portion <NUM>, and the center pin <NUM> is protruded from the upper surface of the electrode assembly <NUM> to support the second electrode tab <NUM>, thereby stably establishing the contact between the second electrode tab <NUM> and the tab bonding portion <NUM>.

Therefore, the second electrode tab <NUM> may be effectively combined with the tab bonding portion <NUM> through laser welding from the outside, even before and after the coupling between the case <NUM> and the cap assembly <NUM>.

As shown in <FIG>, in the rechargeable battery according to an embodiment of the present invention, the cap plate <NUM> may be welded to a side wall end where a rim surrounds the opening of the case <NUM>.

In an embodiment, as shown in <FIG> and <FIG>, the side wall surrounding the opening of the case <NUM> may include a seating groove for seating the rim of the cap plate <NUM> at the end, and the seating groove may be provided to be toward the inner space of the case <NUM> on the side wall.

Accordingly, the cap plate <NUM> may be seated on the side wall of the case <NUM> at the rim, and the welding may be performed while the rim of the cap plate <NUM> is seated in the seating groove.

The rechargeable battery according to one or more embodiments of the present invention may have the coin shape of which the ratio of the height H to the diameter L is <NUM> or less.

That is, in one or more embodiments of the present invention, the coin-type battery may be understood as the battery of the flat and thin shape having the ratio of the height H to the diameter L of <NUM> or less, and the coin-type battery may realize the ultra-small size.

That is, embodiments of the present invention may be applied to the ultra-small coin-type battery of the very small size, and, even in a rechargeable battery of a small size, the bonding and the insulation between the terminal plate <NUM> and the cap plate <NUM> may be concurrently (e.g., simultaneously) realized through the thermal fusion member <NUM>, and the bonding between the tab bonding portion <NUM> and the second electrode tab <NUM> may be easily performed.

Claim 1:
A rechargeable battery comprising:
an electrode assembly (<NUM>) comprising a first electrode (<NUM>), a second electrode (<NUM>), and a separator (<NUM>) between the first electrode (<NUM>) and the second electrode (<NUM>);
a case (<NUM>) having an opening and housing the electrode assembly (<NUM>); and
a cap assembly (<NUM>) sealing the opening of the case (<NUM>),
wherein the cap assembly (<NUM>) comprises:
a cap plate (<NUM>) bonded to the case (<NUM>) and covering the opening;
a terminal plate (<NUM>) bonded to the cap plate (<NUM>); and
a thermal fusion member (<NUM>) formed of an electrically insulating material, between the terminal plate (<NUM>) and the cap plate (<NUM>) and thermally fused with the terminal plate (<NUM>) and the cap plate (<NUM>),
wherein, in the terminal plate (<NUM>) and the cap plate (<NUM>), a surface (<NUM>) in contact with the thermal fusion member (<NUM>) is etched such that the thermal fusion member (<NUM>) is bonded thereto.