Patent Description:
Unlike a primary battery that cannot be charged, a secondary battery is a rechargeable and dischargeable battery. A low-capacity secondary battery comprised of one single cell packaged in the form of a pack may be used for various portable small-sized electronic devices, such as cellular phones or camcorders. In addition, a high-capacity secondary battery in which several tens of cells are connected in a battery pack is widely used as a power source for motor drives, such as those in hybrid vehicles or electric vehicles.

A secondary battery may be configured by embedding a stacked or wound electrode assembly with a separator interposed between positive and negative plates and an electrolyte in a case, and installing a cap plate on the case. In such an electrode assembly, an uncoated portion tab may protrude in a lateral or upper direction, and a current collecting structure may be connected to the uncoated portion tab.

However, due to a thickness or size of the current collecting structure, the capacity of the secondary battery is reduced by as much as the space occupied by the current collecting structure.

The above information disclosed in this Background section is provided for enhancement of understanding of the background of the invention.

From <CIT> there is known a secondary battery as defined in the preamble of claim <NUM>.

According to an aspect of embodiments of the present disclosure, a secondary battery capable of improving the welding strength of a current collector plate is provided.

According to one or more embodiments of the present disclosure, a secondary battery includes: an electrode assembly including an electrode uncoated portion protruding toward at least one side, a current collector plate electrically connected to the electrode uncoated portion of the electrode assembly, a case to accommodate the electrode assembly and the current collector plate, and a cap assembly to seal the case, wherein the current collector plate includes an upper coupling portion and a lower coupling portion coupled to the electrode uncoated portion, and a protrusion protruding toward the case between the upper coupling portion and the lower coupling portion.

The current collector plate may include an electrode connection part including the upper coupling portion, the lower coupling portion and the protrusion, welded to the electrode uncoated portion of the electrode assembly and extending along a side of the electrode assembly, and a terminal connection part including an end coupled to the upper end of the electrode connection part, and another end coupled to a terminal protruding through the cap assembly.

The electrode connection part may be plate-shaped and may include a weld portion coupled to the terminal connection part by welding, the upper coupling portion extending downward from a lower end of the weld portion and being welded in contact with the electrode uncoated portion, the protrusion extending downward from a lower end of the upper coupling portion and protruding toward the case, the lower coupling portion extending downward from a lower end of the protrusion, recessed toward the electrode assembly, and welded in contact with the electrode uncoated portion, and a bent portion extending downward from a lower end of the lower coupling portion and protruding toward the case.

The terminal connection part may include an upper portion between the electrode assembly and the cap assembly, and a side portion bent from the upper portion, extending downward, and coupled to the electrode connection part by welding.

The terminal connection part may include a welding groove having a shape corresponding to the weld portion on an outer surface of the side portion, and the weld portion may be coupled to the side portion of the terminal connection part by welding in a state of being inserted in the welding groove.

In the electrode connection part, a weld region may be formed along a width direction of the electrode connection part by welding the weld portion in a state of being in contact with the side portion of the terminal connection part.

The weld region may have an end bent in an upward direction.

The electrode assembly may include electrode plates and separators alternately stacked, and an insulating tape attached and fixed to an outer surface thereof, and the protrusion may be positioned to correspond to the insulating tape.

The secondary battery may further include a terminal protruding upward through the cap assembly and coupled to the current collector plate under the cap assembly.

A width of the upper coupling portion may be greater than that of other regions of the electrode connection part.

The lower coupling portion and the upper coupling portion may be coupled to the electrode uncoated portion by laser welding in a state of being in contact with the electrode uncoated portion and may be formed to be straight along a width direction of the electrode connection part, and a plurality of straight weld regions may be spaced apart from each other in a vertical direction.

Herein, a secondary battery according to some embodiments of the present disclosure will be described in further detail with reference to the accompanying drawings.

Some examples of the present invention are provided to more completely explain the present invention to those skilled in the art; however, the following examples may be modified in various other forms. That is, the present invention may be embodied in many different forms and should not be construed as being limited to the example embodiments set forth herein. Rather, these example embodiments are provided so that this disclosure will be thorough and complete and will convey the aspects and features of the present invention to those skilled in the art.

In addition, in the accompanying drawings, sizes or thicknesses of various components may be exaggerated for brevity and clarity. In addition, it is to be understood that when an element A is referred to as being "connected to" an element B, the element A may be directly connected to the element B or one or more intervening elements C may be present therebetween such that the element A and the element B are indirectly connected to each other.

The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting of the disclosure. As used herein, the singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise. It is to be further understood that the terms "comprise" and/or "comprising" when used in this specification, specify the presence of stated features, numbers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, elements, components, and/or groups thereof.

It is to be understood that, although the terms "first," "second," etc. may be used herein to describe various members, elements, regions, layers, and/or sections, these members, elements, regions, layers, and/or sections should not be limited by these terms. These terms are used to distinguish one member, element, region, layer, and/or section from another. Thus, for example, a first member, a first element, a first region, a first layer, and/or a first section discussed below could be termed a second member, a second element, a second region, a second layer, and/or a second section without departing from the teachings of the present invention.

Spatially relative terms, such as "beneath," "below," "lower," "above," "upper," and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It is to be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the element or feature in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "on" or "above" the other elements or features.

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 shall not be interpreted in an ideal or overly formal sense, unless they are expressly defined herein.

Referring to <FIG>, a perspective view of a secondary battery according to an embodiment of the present disclosure is shown. Referring to <FIG>, a cross-sectional view taken along the line <NUM>-<NUM> of <FIG> is shown. Referring to <FIG>, an exploded perspective view before a current collector plate and an electrode assembly are coupled to each other in the secondary battery of <FIG> is shown.

As shown in <FIG>, a secondary battery <NUM> may include an electrode assembly <NUM>, a first current collector plate <NUM>, a second current collector plate <NUM>, a first terminal <NUM>, a second terminal <NUM>, a case <NUM>, and a cap assembly <NUM>. Here, the first terminal <NUM> may include a first terminal pole <NUM> and a first terminal plate <NUM>, and the second terminal <NUM> may include a second terminal pole <NUM> and a second terminal plate <NUM>.

In an embodiment, the electrode assembly <NUM> is formed by stacking a plurality of stacks of a first electrode plate, a separator, and a second electrode plate formed in a thin plate shape or a film shape. Here, the first electrode plate may operate as an electrode of a first polarity, for example, a positive electrode, and the second electrode plate may operate as an electrode of a second polarity, for example, a negative electrode. Of course, according to the selection of a person skilled in the art, the first electrode plate and the second electrode plate may be arranged with different polarities from each other.

The first electrode plate is formed by coating a first electrode active material, such as a transition metal oxide, on a first electrode current collector formed of a metal foil, such as aluminum, and includes a first electrode uncoated portion <NUM> that is a region to which the first electrode active material is not applied. The first electrode uncoated portion <NUM> provides a passage for current flow between the first electrode plate and the outside.

In an embodiment, the first electrode uncoated portion <NUM> has a multi-tab structure by being formed to overlap at a same position when the first electrode plates are stacked. The first electrode uncoated portion <NUM> is formed to protrude toward a side of the electrode assembly <NUM>, and, in one or more embodiments, a plurality of first electrode uncoated portions <NUM> may be welded to each other to form a first current collecting tab. The first electrode uncoated portion <NUM> is aligned to a side of the electrode assembly <NUM> and protrudes, and, in an embodiment, the plurality of first electrode uncoated portions <NUM> are aligned to a side of the electrode assembly <NUM> and protrude.

The second electrode plate is formed by coating a second electrode active material, such as graphite or carbon, on a second electrode current collector formed of a metal foil, such as copper or nickel, and includes a second electrode uncoated portion <NUM> that is a region to which the second electrode active material is not applied.

In an embodiment, the second electrode uncoated portion <NUM> also has a multi-tab structure by being formed to overlap at a same position when the second electrode plates are stacked. The second electrode uncoated portion <NUM> is formed to protrude toward the other side of the electrode assembly <NUM>, and, in one or more embodiments, a plurality of second electrode uncoated portions <NUM> may be welded to each other to form a second current collecting tab.

The separator is positioned between the first electrode plate and the second electrode plate to prevent or substantially prevent a short circuit and to enable movement of lithium ions. The separator may be made of polyethylene, polypropylene, or a composite film of polyethylene and polypropylene. However, a material of the separator is not limited thereto according to embodiments of the present disclosure.

In an embodiment, after the plurality of electrode plates are stacked, the electrode assembly <NUM> may maintain a stacked state through a separate insulating tape <NUM> attached to a partial region of the outer surface. Here, the insulating tape <NUM> maintains a shape of the electrode assembly <NUM> such that the electrode assembly <NUM> can be welded to the current collector plates <NUM> and <NUM> at a correct position, and even in a final secondary battery structure, the insulating tape <NUM> can fix the electrode assembly <NUM> so as to maintain the structure of the electrode assembly <NUM>.

In addition, the electrode assembly <NUM> is substantially accommodated in the case <NUM> together with an electrolyte. The electrolyte may include a lithium salt, such as LiPF<NUM> or LiBF<NUM> in an organic solvent, such as ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), or dimethyl carbonate (DMC). In addition, the electrolyte may be in the form of a liquid, a solid, or a gel.

The first current collector plate <NUM> is made of a conductive material, such as aluminum, and is electrically connected to the first electrode plate by being coupled to the first electrode uncoated portion <NUM> protruding from an end of the electrode assembly <NUM>. The first current collector plate <NUM> may be electrically connected to the first electrode uncoated portion <NUM> by welding. The first current collector plate <NUM> may include a first electrode connection part <NUM> extending in a vertical direction along a side of the electrode assembly <NUM>, and a first terminal connection part <NUM> extending between the electrode assembly <NUM> and the cap assembly <NUM>, and coupled to the first terminal <NUM>.

Referring to <FIG> and <FIG>, respectively, an exploded perspective view showing before the first electrode connection part <NUM> and the first terminal connection part <NUM> are coupled in the first current collector plate <NUM>, and a perspective view showing that the first electrode connection part <NUM> and the first terminal connection part <NUM> are coupled, are shown. In addition, referring to <FIG>, a side view of the first current collector plate <NUM> as viewed from the outside in which the case <NUM> is positioned is shown. Herein, the configuration of the first current collector plate <NUM> will be described with reference to <FIG>, <FIG>.

The first electrode connection part <NUM> may extend in the vertical direction along a side surface of the electrode assembly <NUM> and may have a substantially plate shape. The first electrode connection part <NUM> may be coupled through welding in a state of being in contact with the first electrode uncoated portion <NUM> of the electrode assembly <NUM> to have a same first polarity as the first electrode uncoated portion <NUM>. Herein, for convenience of description, in the first electrode connection part <NUM>, a surface opposite to a side of the electrode assembly <NUM> is referred to as an inner surface, and a surface opposite to an end surface of the case <NUM> is referred to as an outer surface.

In an embodiment, the first electrode connection part <NUM> may include a weld portion 121a, an upper coupling portion 121b, a protrusion 121c, a lower coupling portion 121d, and a bent portion 121e sequentially from the top to the bottom.

The weld portion 121a may be in contact with a side portion 122b of the first terminal connection part <NUM> to be coupled by welding. The weld portion 121a may be coupled by welding in a state of being inserted in a welding groove 122d provided on an outer surface of the side portion 122b of the first terminal connection part <NUM>. In an embodiment, welding between the weld portion 121a and the side portion 122b of the first terminal connection part <NUM> may be performed by a laser welding, and a weld region <NUM> may be formed along a first direction x, which is a width direction of the first electrode connection part <NUM>. In an embodiment, the weld region <NUM> may extend in a straight line along the first direction x, and may have an end bent in an approximately upward direction. As described above, the weld region <NUM> may have a bent portion at the end, thereby improving welding strength. In an embodiment, a width Wa of the weld portion 121a may correspond to the size of the welding groove 122d, and, to be welded with the first terminal connection part <NUM> in a state of being inserted in the welding groove 122d, the width Wa may be smaller than widths of other regions of the first electrode connection part <NUM>. In an embodiment, the width Wa of the weld portion 121a may be smaller than a width Wb of the upper coupling portion 121b.

The upper coupling portion 121b may be a portion extending downward from a lower end of the weld portion 121a. The upper coupling portion 121b may be coupled to the first electrode uncoated portion <NUM> by welding in a state in which an inner surface of the upper coupling portion 121b is in contact with the first electrode uncoated portion <NUM>. The upper coupling portion 121b may be depressed relative to the weld portion 121a and the protrusion 121c in a direction toward the electrode assembly <NUM>. With this structure, the upper coupling portion 121b can easily come into contact with the first electrode uncoated portion <NUM>, such that welding can be easily performed. In addition, the width Wb of the upper coupling portion 121b may be greater than widths of other regions of the first electrode connection part <NUM>. As described above, in an embodiment, the width Wb of the upper coupling portion 121b is larger the widths of other regions, and a heat dissipation effect against heat generated in the electrode assembly <NUM> may be improved. In an embodiment, for the upper coupling portion 121b to be welded to the first terminal connection part <NUM> in a state of the weld portion 121a being inserted into the welding groove 122d, the width Wb of the upper coupling portion 121b may be greater than the width Wa of the weld portion 121a having a smaller width than other regions. In an embodiment, the weld portion 121a may be located at the center of the upper coupling portion 121b. That is, the upper coupling portion 121b may further extend to both sides along the width direction from the lower end of the weld portion 121a.

The protrusion 121c may be a portion extending downward from a lower end of the upper coupling portion 121b. The protrusion 121c may be shaped to protrude, relative to the upper coupling portion 121b and the lower coupling portion 121d, toward an exterior side where the case <NUM> is positioned. The protrusion 121c may be positioned to correspond to the insulating tape <NUM> of the electrode assembly <NUM>. Due to a thickness deviation that may be generated by the insulating tape <NUM> attached to the electrode assembly <NUM>, the protrusion 121c may prevent or substantially prevent the first current collector plate <NUM> from contacting the first electrode uncoated portion <NUM>. In an embodiment, the protrusion 121c may be located approximately at the center of the first electrode connection part <NUM>. That is, the upper coupling portion 121b and the lower coupling portion 121d may be respectively positioned at upper and lower portions with respect to the protrusion 121c.

The lower coupling portion 121d may be a portion extending downward from a lower end of the protrusion 121c. The lower coupling portion 121d may be coupled to the first electrode uncoated portion <NUM> by welding in a state in which an inner surface of the lower coupling portion 121d is in contact with the first electrode uncoated portion <NUM>. That is, the first electrode connection part <NUM> may be electrically connected by welding while the upper coupling portion 121b and the lower coupling portion 121d are in contact with the first electrode uncoated portion <NUM>. In an embodiment, the lower coupling portion 121d and the upper coupling portion 121b may have inner surfaces facing the electrode assembly <NUM> on a same plane. The lower coupling portion 121d may be depressed relative to the protrusion 121c and the bent portion 121e in a direction toward the electrode assembly <NUM>. With this structure, the upper coupling portion 121b and the lower coupling portion 121d can easily come into contact with the first electrode uncoated portion <NUM>, such that welding can be easily performed. In an embodiment, the lower coupling portion 121d and the upper coupling portion 121b may be welded and coupled to the first electrode uncoated portion <NUM> on the outer surface of the first electrode connection part <NUM> by lasers in a state of being in contact with the first electrode uncoated portion <NUM>. In an embodiment, the lower coupling portion 121d and the upper coupling portion 121b may be formed to be straight along a width direction of the first electrode connection part <NUM>. In an embodiment, the welding by lasers may extend in a straight line along the first direction x, and a plurality of straight welding regions may be formed to be spaced apart from each other in the upper and lower directions (i.e., in a vertical direction).

In an embodiment, a width Wd of the lower coupling portion 121d may be smaller than the width Wb of the upper coupling portion 121b. Also, the width Wd of the lower coupling portion 121d may be greater than the width Wa of the weld portion 121a. In addition, the width Wd of the lower coupling portion 121d may be the same as a width of the protrusion 121c and the bent portion 121e.

The bent portion 121e may be a portion extending downward from a lower end of the lower coupling portion 121d. The bent portion 121e may protrude, relative to the lower coupling portion 121d, toward an exterior side where the case <NUM> is positioned. The bent portion 121e can improve the straight welding efficiency and the welding depth by allowing the first electrode uncoated portion <NUM> to maintain parallelism with the upper coupling portion 121b and the lower coupling portion 121d.

In the first electrode connection part <NUM>, the upper coupling portion 121b and the lower coupling portion 121d that are inwardly recessed may be positioned in the upper and lower portions with respect to the protrusion 121c. In addition, the weld portion 121a and the bent portion 121e protruding outwardly may be located at an upper end of the upper coupling portion 121b and the lower end of the lower coupling portion 121d, respectively.

The first terminal connection part <NUM> is formed in an approximately "┌" shape, and may include an upper portion 122a having an approximately plate shape and interposed between the cap assembly <NUM> and the electrode assembly <NUM>, and the side portion 122b downwardly bent and extending from the upper portion 122a (e.g., an outer end of the upper portion 122a). Here, the side portion 122b may extend in the vertical direction along a side surface of the electrode assembly <NUM>.

In an embodiment, the upper portion 122a may be positioned parallel to a cap plate <NUM> to be described later. A terminal hole 122c penetrating between an upper surface and a lower surface may be formed in the upper portion 122a. A first terminal pole <NUM> to be described below may be inserted into the terminal hole 122c to be riveted and/or welded.

The side portion 122b may have the welding groove 122d concave inwardly formed at the lower end of the outer surface. Here, the welding groove 122d may be shaped to correspond to the weld portion 121a of the first electrode connection part <NUM>. In an embodiment, the welding groove 122d may be located at the center of the lower end of the side portion 122b. The side portion 122b may be electrically and mechanically coupled to the first electrode connection part <NUM> by welding in a state in which the weld portion 121a is inserted into the welding groove 122d. In addition, the lower end of the side portion 122b may be in contact with the upper end of the upper coupling portion 121b extending further to both sides from the lower end of the weld portion 121a in the width direction. The side portion 122b, including the welding groove 122d, may prevent or substantially prevent position misalignment when being coupled to the first electrode connection part <NUM> and may improve bonding strength.

In an embodiment, the first terminal connection part <NUM> is coupled to the first electrode connection part <NUM> by laser welding to be formed into the first current collector plate <NUM>.

The second current collector plate <NUM> is made of a conductive material, such as nickel, and comes into contact with the second electrode uncoated portion <NUM> protruding from another end of the electrode assembly <NUM> to be electrically connected to the second electrode plate. The second current collector plate <NUM> includes a second electrode connection part <NUM> and a second terminal connection part <NUM>. In an embodiment, the shape of the second current collector plate <NUM> is the same as that of the first current collector plate <NUM>, and repeated description will be omitted.

The first terminal <NUM> is made of a conductive material, such as aluminum, and may be electrically connected to the first current collector plate <NUM>. The first terminal <NUM> includes the first terminal pole <NUM> and the first terminal plate <NUM>.

The first terminal pole <NUM> protrudes and extends upward by a length (e.g., a predetermined length) through the cap plate <NUM> of the cap assembly <NUM>, and may be electrically connected to the first current collector plate <NUM> under the cap plate <NUM>. In addition, in one or more embodiments, the first terminal pole <NUM> protrudes and extends to the upper portion of the cap plate <NUM> by a length (e.g., a predetermined length), and a flange 141a may be formed on the cap plate <NUM> such that the first terminal pole <NUM> does not come off from the cap plate <NUM>. The flange 141a may protrude between the first terminal plate <NUM> and the cap plate <NUM>. A lower portion of the first terminal pole <NUM> may be riveted and/or welded after being fitted into the first terminal hole 122c of the first current collector plate <NUM>.

The first terminal plate <NUM> has a terminal hole 142a, and the upper portion of the first terminal pole <NUM> may be coupled to the terminal hole 142a to then be riveted and/or welded. The first terminal plate <NUM> may be positioned on the cap plate <NUM>. In one or more embodiments, interfaces of the first terminal pole <NUM> exposed upward and the first terminal plate <NUM> may be welded to each other. For example, a laser beam may be provided to a boundary region between the first terminal pole <NUM> exposed upward and the first terminal plate <NUM>, and the boundary region may be melted and then cooled and welded. In some examples, the first terminal pole <NUM> and the first terminal plate <NUM> may be electrically insulated from the cap plate <NUM>.

The second terminal <NUM> is made of a conductive material, such as nickel, and is electrically connected to the second current collector plate <NUM>. The second terminal <NUM> includes the second terminal pole <NUM> and the second terminal plate <NUM>. In an embodiment, the shape of the second terminal <NUM> is the same as that of the first terminal <NUM>, and repeated description will be omitted.

The case <NUM> is made of a conductive metal, such as aluminum, aluminum alloy, or nickel-plated steel, and may have a substantially hexahedral shape with an opening into which the electrode assembly <NUM>, the first current collector plate <NUM> and the second current collector plate <NUM> can be inserted and seated. The cap plate <NUM> may be coupled to the opening of the case <NUM> to seal the case <NUM>. An inner surface of the case <NUM> may be insulated to prevent or substantially prevent an electrical short circuit from occurring therein.

The cap assembly <NUM> may be coupled to the case <NUM>. In an embodiment, the cap assembly <NUM> may include the cap plate <NUM>, a seal gasket <NUM>, a stopper <NUM>, a safety vent <NUM>, an upper coupling member <NUM>, and a lower insulating member <NUM>. The cap plate <NUM> may seal an opening <NUM> of the case <NUM>. The seal gasket <NUM> is made of an insulating material between the cap plate <NUM> and the first terminal pole <NUM> of the first terminal <NUM>, and between the cap plate <NUM> and the second terminal pole <NUM> of the second terminal <NUM>, respectively, to seal a portion between each of the first terminal pole <NUM> and the second terminal pole <NUM> and the cap plate <NUM>. The seal gasket <NUM> prevents or substantially prevents external moisture from penetrating into the secondary battery <NUM> or the electrolyte contained in the secondary battery <NUM> from leaking to the outside.

A plug <NUM> seals an electrolyte injection hole 171a of the cap plate <NUM>, and a safety vent <NUM> may be installed in a vent hole 171b of the cap plate <NUM> and have a notch 174a installed so as to be opened at a set pressure.

An upper coupling member <NUM> may be formed between the cap plate <NUM> and each of the first and second terminal poles <NUM> and <NUM> at the upper portion of the cap plate <NUM>. In addition, the upper coupling member <NUM> is in close contact with the cap plate <NUM>. Further, the upper coupling member <NUM> may also be close contact with the seal gasket <NUM>. The upper coupling member <NUM> may insulate the first and second terminal poles <NUM> and <NUM> from the cap plate <NUM>. In one or more embodiments, the upper coupling member <NUM> formed on the first terminal pole <NUM> may electrically connect the first terminal plate <NUM> and the cap plate <NUM> to each other, and, thus, the cap plate <NUM> may be connected to the first terminal to have the same polarity as the first terminal <NUM>. In this case, the case <NUM> may also have the same polarity as the cap plate <NUM>, and an electrical short circuit with the electrode assembly <NUM> may be prevented or substantially prevented by an internal insulation treatment.

As described above, the secondary battery according to one or more embodiments of the present disclosure is capable of improving the welding strength of a current collector plate.

Claim 1:
A secondary battery (<NUM>) comprising:
an electrode assembly (<NUM>) comprising an electrode uncoated portion (<NUM>) exposed to at least one side;
a current collector plate (<NUM>, <NUM>) electrically connected to the electrode uncoated portion of the electrode assembly (<NUM>);
a case (<NUM>) to accommodate the electrode assembly (<NUM>) and the current collector plate (<NUM>, <NUM>); and
a cap assembly (<NUM>) to seal the case (<NUM>),
wherein the current collector plate (<NUM>, <NUM>) comprises an upper coupling portion (121b) and a lower coupling portion (121d) coupled to the electrode uncoated portion, and a protrusion (121c) protruding toward the case (<NUM>) between the upper coupling portion (121b) and the lower coupling portion (121d), wherein the current collector plate (<NUM>, <NUM>) comprises:
an electrode connection part (<NUM>, <NUM>) welded to the electrode uncoated portion of the electrode assembly (<NUM>) and extending along a side of the electrode assembly (<NUM>); and
a terminal connection part (<NUM>, <NUM>) comprising an end coupled to an upper end of the electrode connection part, and another end coupled to a terminal protruding through the cap assembly (<NUM>), characterised in that
a width of the upper coupling portion (121b) is greater than that of other regions of the electrode connection part (<NUM>).