Rectangular rechargeable battery

Abstract

In a rectangular secondary battery, the connection structure between the positive and negative electrode leads of the electrode assembly and the terminal portion of the secondary battery is improved to maximize battery capacity while reducing the risk of wire breakage. [Solution] The disclosed invention relates to a rectangular secondary battery and includes an electrode assembly comprising a first electrode lead portion formed in a first lateral direction and a second electrode lead portion formed in a second lateral direction opposite to the first lateral direction; a lower case having an open upper surface and housing the electrode assembly inside; and an upper case covering the open upper surface of the lower case, wherein the upper case includes a first terminal portion bent at a top surface corresponding to the upper surface of the lower case and extended downward in the first lateral direction, and a second terminal portion bent at the top surface and extended downward in the second lateral direction, wherein the first electrode lead portion is electrically connected to the first terminal portion and the second electrode lead portion is electrically connected to the second terminal portion.

Description

Technical Field

[0001] The present invention relates to a rectangular secondary battery, and more particularly to a rectangular secondary battery with an improved connection structure of positive and negative electrodes of an electrode assembly to a terminal portion of the secondary battery.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0042009, filed on April 5, 2022, and all the contents disclosed in the document of the Korean Patent Application are incorporated herein by reference.

Background Art

[0003] Unlike primary batteries, secondary batteries can be recharged and have been extensively studied and developed in recent years due to their potential for miniaturization and high capacity. With the increasing technological development and demand for mobile devices, as well as the emergence of electric vehicles and energy storage systems in response to the contemporary requirements of environmental protection, the demand for secondary batteries as an energy source has been increasing even more rapidly.

[0004] Secondary batteries are classified into coin-type batteries, cylindrical batteries, rectangular batteries, and pouch-type batteries according to the shape of the battery case. The electrode assembly installed inside the battery case in a secondary battery is a power generation element capable of charge and discharge, which consists of a laminated structure of electrodes and a separator.

[0005] The electrode assembly can be roughly classified into a Jellyroll type in which a separator is interposed between sheet-shaped positive and negative electrodes coated with an active material and wound, a stack type in which a large number of positive and negative electrodes are sequentially laminated with a separator interposed therebetween, and a Stack&Folding type in which unit cells of the stack type are wound with a long separation film.

[0006] Conventionally, when manufacturing medium to large rectangular secondary batteries, the electrode assembly with bidirectional terminals was inserted into a rectangular parallelepiped case with an open top. The positive and negative electrode leads on both sides were then pulled out to the top and welded to the positive and negative terminals of the cap plate, and finally the cap plate was welded to the case.

[0007] However, with conventional rectangular rechargeable batteries, the attachments that bring the positive and negative electrode leads out to the top occupy space, which inevitably reduces the battery's capacity. Furthermore, there was a risk of wire breakage at the connection point between the positive and negative electrode leads. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Korean Published Patent No. 10-2019-0024290 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] The present invention aims to improve the connection structure between the positive and negative electrode leads of the electrode assembly and the terminal portion of the secondary battery in a rectangular secondary battery, thereby maximizing the battery capacity while reducing the risk of wire breakage.

[0010] However, the technical problems that this invention aims to solve are not limited to those described above, and other problems not mentioned can be clearly understood by an ordinary person of the art from the description of the invention below. [Means for solving the problem]

[0011] The prismatic secondary battery according to the present invention includes, in one example, an electrode assembly including a first electrode lead portion formed in a first lateral direction and a second electrode lead portion formed in a second lateral direction opposite to the first lateral direction; a lower case having an open upper surface and housing the electrode assembly inside; and an upper case covering the open upper surface of the lower case, wherein the upper case includes a first terminal portion bent at a top surface corresponding to the upper surface of the lower case and extending downward in the first lateral direction, and a second terminal portion bent at the top surface and extending downward in the second lateral direction, wherein the first electrode lead portion is electrically connected to the first terminal portion, and the second electrode lead portion is electrically connected to the second terminal portion.

[0012] Furthermore, a gas venting section may be formed on the top surface of the upper case described above.

[0013] In one embodiment of the present invention, the upper case includes a top surface that covers the open upper surface of the lower case, and four skirts that are bent and extended downward from the top surface.

[0014] Furthermore, of the four skirts mentioned above, the side skirt on which the first and second terminal portions are formed may be extended further downward than the other two front and rear skirts.

[0015] Furthermore, the first electrode lead portion and the second electrode lead portion of the electrode assembly may be located at the top, with reference to the central height of the electrode assembly.

[0016] Furthermore, the first terminal section and the second terminal section include a first internal terminal and a second internal terminal arranged inside the side skirt, and a first external terminal and a second external terminal that are electrically connected to the first internal terminal and the second internal terminal, respectively, and exposed to the outside of the upper case.

[0017] Furthermore, the first electrode lead portion and the second electrode lead portion of the electrode assembly are directly joined to the first internal terminal and the second internal terminal, respectively, and electrically connected.

[0018] In one embodiment of the present invention, the first external terminal and the second external terminal may be respectively located on the side skirt.

[0019] Alternatively, according to another embodiment of the present invention, the first external terminal and the second external terminal may be respectively located on the top surface of the upper case.

[0020] And the four skirts of the upper case can be joined to the upper surface of the lower case by welding.

[0021] And the upper case is inserted and coupled to the lower case in a state where the first electrode lead portion and the second electrode lead portion of the electrode assembly are joined to the first terminal portion and the second terminal portion to form an integral body.

[0022] The electrode assembly provided in the rectangular secondary battery of the present invention can be a laminated electrode assembly or a wound electrode assembly.

Effect of the Invention

[0023] In the rectangular secondary battery of the present invention having the above-described configuration, the electrode lead portions of the electrode assembly facing the terminal portions provided on both side surfaces of the upper case are electrically connected. As a result, accessories for pulling out the positive and negative electrode leads on the upper surface as in the conventional rectangular secondary battery are not required, so that the side space of the rectangular secondary battery can be sufficiently utilized, and an additional battery capacity can be secured accordingly.

[0024] In addition, in the rectangular secondary battery of the present invention, since the electrode lead portions of the electrode assembly are directly welded to the terminal portions provided on both side surfaces of the upper case, the risk of disconnection due to external impact or the like is significantly reduced.

[0025] However, the technical effects that can be obtained by the present invention are not limited to the above-described effects, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the invention described below.

[0026] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further understand the technical idea of the present invention together with the detailed description of the invention to be described later. Therefore, the present invention should not be construed as being limited only to the matters described in such drawings.

Brief Description of the Drawings

[0027] [Figure 1] It is an exploded perspective view of a rectangular secondary battery according to the present invention. [Figure 2] It is a perspective view showing the coupling structure between the upper case and the electrode assembly. [Figure 3] It is a drawing showing the structure in which the combined body of the upper case and the electrode assembly is housed in the lower case. [Figure 4] It is a drawing showing the state in which the upper case and the lower case are welded to each other. [Figure 5] It is a drawing showing another embodiment of the upper case. [Figure 6] It is a drawing showing the state in which the upper case of FIG. 5 is welded to the lower case.

Modes for Carrying Out the Invention

[0028] Since the present invention can be modified in various ways and can have various embodiments, specific embodiments will be described in detail below.

[0029] However, this is not intended to limit the present invention to specific embodiments, and should be understood as including all modifications, equivalents or alternatives included in the spirit and technical scope of the present invention.

[0030] In the present invention, terms such as "includes" and "have" are intended to specify the presence of features, numbers, stages, operations, components, parts, or combinations thereof as described in the specification, and should be understood as not preemptively excluding the presence or possibility of adding one or more other features, numbers, stages, operations, components, parts, or combinations thereof.

[0031] Furthermore, in this invention, when a part such as a layer, film, region, or plate is described as being "on top" of another part, this includes not only the case where it is "directly on top" of the other part, but also the case where another part is located in between. Conversely, when a part such as a layer, film, region, or plate is described as being "below" another part, this includes not only the case where it is "directly below" the other part, but also the case where another part is located in between. Also, in this application, being "on top" may include being located not only at the top but also at the bottom.

[0032] In one example, the prismatic secondary battery according to the present invention includes an electrode assembly, a lower case, and an upper case.

[0033] The electrode assembly includes a first electrode lead portion formed in the first lateral direction and a second electrode lead portion formed in the second lateral direction opposite to the first lateral direction.

[0034] The lower case has an open top surface, and a space for housing the electrode assembly is formed inside. The upper case covers the open top surface of the lower case, and the upper case includes a first terminal portion that is bent at the top surface corresponding to the top surface of the lower case and extends downward in the first lateral direction, and a second terminal portion that is bent at the top surface and extends downward in the second lateral direction.

[0035] The first electrode lead portion is electrically connected to the first terminal portion, and the second electrode lead portion is electrically connected to the second terminal portion.

[0036] In one embodiment of the present invention having the configuration described above, the electrode leads of the electrode assembly facing the terminals provided on both sides of the upper case are electrically connected. This eliminates the need for attachments to bring the positive and negative electrode leads to the top surface, as is the case with conventional rectangular secondary batteries, allowing for full utilization of the lateral space of the rectangular secondary battery and thereby securing additional battery capacity.

[0037] Specific embodiments of the present invention will be described in detail below with reference to the attached drawings.

[0038] (First Embodiment) Figure 1 is an exploded perspective view of a prismatic secondary battery 10 according to one embodiment of the present invention. Referring to Figure 1, the prismatic secondary battery 10 according to one embodiment of the present invention includes an electrode assembly 200, a lower case 300, and an upper case 100. The lower case 300 and the upper case 100 are interconnected to form a hexahedral case for the prismatic secondary battery 10, and the electrode assembly 200 has a size and shape suitable for being housed in the lower case 300 and the upper case 100.

[0039] The electrode assembly 200 is made up of multiple stacked unit cells and includes a first electrode lead portion 220 formed in the direction of the first side surface 210 and a second electrode lead portion 240 formed in the direction of the second side surface 230 facing the first side surface 210. Either the first electrode lead portion 220 or the second electrode lead portion 240 is a positive electrode lead portion, and the other is a negative electrode lead portion. If the first electrode lead portion is a positive electrode lead portion, it consists of a bundle of multiple positive electrode tabs formed by punching out the positive electrode of each unit cell of the electrode assembly 200. Similarly, the second electrode lead portion 240, which is a negative electrode lead portion, consists of a bundle of negative electrode tabs.

[0040] In one embodiment of the present invention, a bidirectional electrode assembly 200 is applied, in which a first electrode lead portion 220 and a second electrode lead portion 240 are arranged one on each of the opposing sides. As long as the bidirectional electrode assembly 200 has such a structure, a stacked electrode assembly, a wound electrode assembly, or a hybrid type electrode assembly combining these can be used in the prismatic secondary battery 10 according to one embodiment of the present invention.

[0041] The lower case 300 has an open top surface, and a space for housing the electrode assembly 200 is formed inside. Correspondingly, the upper case 100 covers the open top surface of the lower case 300, and the upper case 100 and the lower case 300 are interconnected, sealing the internal space.

[0042] As shown in Figure 1, the upper case 100 includes a first terminal portion 120 that is bent at the top surface corresponding to the upper surface of the lower case 300 and extended downward in the direction of the first side surface 210, and a second terminal portion 130 that is bent at the top surface and extended downward in the direction of the second side surface 230. As a result, two terminal portions that are bent downward are arranged on both sides of the upper case 100.

[0043] Figure 2 is a perspective view illustrating the coupling structure between the upper case 100 and the electrode assembly 200. Referring to Figure 2, the first terminal portion 120 of the upper case 100 faces the first electrode lead portion 220 of the electrode assembly 200, and similarly, the second terminal portion 130 faces the second electrode lead portion 240.

[0044] Therefore, the first electrode lead portion 220 can be electrically connected very easily by welding to the opposing first terminal portion 120 without any additional attachments. Similarly, the second electrode lead portion 240 is electrically connected by directly welding to the opposing second terminal portion 130.

[0045] Thus, in the rectangular secondary battery 10 according to one embodiment of the present invention, the first electrode lead portion 220 and the second electrode lead portion 240 of the electrode assembly 200 are directly welded to the first terminal portion 120 and the second terminal portion 130 provided on both sides of the upper case 100, thereby significantly reducing the risk of wire breakage due to external impacts or the like.

[0046] Furthermore, a gas venting section 140 may be formed on the top surface of the upper case 100. The gas venting section 140 is configured to rupture and release gas when the internal pressure of the prismatic secondary battery 10 increases above a certain level, and thus constitutes a safety device to prevent the explosion of the prismatic secondary battery 10. For example, the gas venting section 140 may be formed by creating a notch thinner than the surrounding thickness on the surface of the upper case 100, or by attaching a separate venting device.

[0047] In one embodiment of the present invention, the upper case 100 includes a top surface that covers the open upper surface of the lower case 300, and four skirts 112 that are bent and extended downward at the top surface.

[0048] Furthermore, of the four skirts 112, the side skirt 113 on which the first terminal portion 120 and the second terminal portion 130 are formed can be extended further downward than the other two front skirts 114 and the rear skirt 115. By making the length of the front skirts 114 and the rear skirt 115 shorter than the length of the side skirts 113 in this way, sufficient space is secured for welding the first terminal portion 120 and the second terminal portion 130 to the first electrode lead portion 220 and the second electrode lead portion 240, thereby facilitating the welding work.

[0049] Furthermore, the first electrode lead portion 220 and the second electrode lead portion 240 of the electrode assembly 200 may be located above the center height of the electrode assembly 200. Correspondingly, the first terminal portion 120 and the second terminal portion 130 of the upper case 100, which face the first electrode lead portion 220 and the second electrode lead portion 240, will also be located above the overall height of the rectangular secondary battery 10. This is the simplest way to realize a structure in which the first terminal portion 120 and the second terminal portion 130 are located even more adjacent to the top surface in a bidirectional terminal arrangement of the rectangular secondary battery 10.

[0050] On the other hand, according to one embodiment of the present invention, the first terminal portion 120 and the second terminal portion 130 may include a first internal terminal 122 and a second internal terminal 132 arranged inside the side skirt 113, and a first external terminal 124 and a second external terminal 134 that are electrically connected to the first internal terminal 122 and the second internal terminal 132, respectively, and exposed to the outside of the upper case 100. By exposing only the first external terminal 124 and the second external terminal 134 to the outside, good sealing performance with respect to the electrode assembly 200 is maintained.

[0051] Furthermore, since the first terminal section 120 and the second terminal section 130 are divided into the first internal terminal 122 and the second internal terminal 132 which connect to the first electrode lead section 220 and the second electrode lead section 240 of the electrode assembly 200, and the first external terminal 124 and the second external terminal 134 which are exposed to the outside of the upper case 100, the degree of freedom in selecting the position of the first external terminal 124 and the second external terminal 134 is increased. In the first embodiment shown in Figures 1 to 4, the first external terminal 124 and the second external terminal 134 are located on the side skirt 113.

[0052] Figure 3 is a diagram illustrating a structure in which the upper case 100 and the electrode assembly 200 are housed in the lower case 300. The upper case 100 and the electrode assembly 200 are integrally formed by welding between the first terminal portion 120 and the second terminal portion 130 and the first electrode lead portion 220 and the second electrode lead portion 240. Therefore, the integral upper case 100 and the electrode assembly 200 can be easily inserted into the lower case 300.

[0053] Figure 4 is a diagram illustrating the state in which the upper case 100 and the lower case 300 are welded to each other. The four skirts 112 of the upper case 100 are welded to the upper surface of the lower case 300. The upper surface of the lower case 300 has a complementary shape corresponding to the length of the four skirts 112 of the upper case 100 extended downward, and the welded portion W is formed all around along the contact surface between the upper case 100 and the lower case 300, thereby tightly sealing the prismatic secondary battery 10.

[0054] (Second Embodiment) Figure 5 is a drawing illustrating a second embodiment of the upper case 100. The second embodiment differs from the first embodiment in the structure of the upper case 100, but the configuration of the electrode assembly 200 and the lower case 300 is the same as in the first embodiment.

[0055] In the second embodiment, the upper case 100 includes a top surface that covers the open upper surface of the lower case 300, and four skirts 112 that are bent downwards at the top surface. Of the four skirts 112, the side skirt 113, on which the first terminal portion 120 and the second terminal portion 130 are formed, extends further downwards than the other two front skirts 114 and the rear skirt 115.

[0056] The first terminal section 120 and the second terminal section 130 of the upper case 100 include a first internal terminal 122 and a second internal terminal 132 located inside the side skirt 113, and a first external terminal 124 and a second external terminal 134 that are electrically connected to the first internal terminal 122 and the second internal terminal 132, respectively, and exposed to the outside of the upper case 100.

[0057] In the second embodiment, the first external terminal 124 and the second external terminal 134 are both located on the top surface of the upper case 100. That is, in the first embodiment, the first external terminal 124 and the second external terminal 134 are arranged on both sides of the upper case 100, whereas in the second embodiment, they are both located on the top surface of the upper case 100.

[0058] The second embodiment is one in which the first external terminals 124 and 2 external terminals 134, which are electrically connected to the first internal terminal 122 and 2 internal terminal 132 respectively, are moved to the top surface of the upper case 100. This can be easily implemented because the first terminal portion 120 and 2 terminal portion 130 of the upper case 100 are divided into the inner first internal terminals 122 and 2 internal terminals 132 that connect to the first electrode lead portion 220 and 2 electrode lead portion 240 of the electrode assembly 200, and the first external terminals 124 and 2 external terminals 134 that are exposed to the outside of the upper case 100.

[0059] In other words, the present invention can be realized in its second embodiment by moving only the first external terminal 124 and the second external terminal 134 to the top surface of the upper case 100 without changing the joining structure of the first electrode lead portion 220 and the second electrode lead portion 240 of the electrode assembly 200. Therefore, by changing only the upper case 100, it is possible to manufacture a bidirectional secondary battery 10 as a unidirectional secondary battery 10.

[0060] Figure 6 is a diagram illustrating the state in which the upper case 100 of Figure 5 is welded to the lower case 300. When compared with the first embodiment in Figure 4, only the positions of the first external terminal 124 and the second external terminal 134 are different; all other configurations are the same. Therefore, the present invention has the same effect of significantly reducing the risk of wire breakage due to external impacts, etc., while making full use of the lateral space of the rectangular secondary battery 10, and is also versatile in that it can be applied to both bidirectional secondary batteries 10 and unidirectional secondary batteries 10.

[0061] The present invention has been described in more detail above with reference to the drawings and embodiments. However, the configurations described in the drawings or embodiments described herein are merely one embodiment of the present invention and do not represent the entire technical concept of the present invention. It should be understood that there are various equivalents and modifications that can substitute for them at the time of filing this application. [Industrial applicability]

[0062] This invention is a useful technology for improving the capacity and safety of prismatic rechargeable batteries.

[0063] Furthermore, the present invention may also preferably include the following examples. [Section 1] An electrode assembly including a first electrode lead portion formed in a first lateral direction and a second electrode lead portion formed in a second lateral direction opposite to the first lateral direction, The structure has an open top surface and includes a lower case that houses the electrode assembly inside, Includes an upper case that covers the open upper surface of the lower case, The aforementioned upper case is The first terminal portion is bent at the top surface corresponding to the upper surface of the lower case and is extended downward in the first lateral direction, The second terminal portion is bent on the top surface and extends downward in the second side direction, Includes, A rectangular secondary battery in which the first electrode lead portion is electrically connected to the first terminal portion, and the second electrode lead portion is electrically connected to the second terminal portion. [Section 2] The prismatic secondary battery according to item 1, including a gas vent portion formed on the top surface of the upper case. [Section 3] The aforementioned upper case is The top surface covers the open upper surface of the lower case, A prismatic secondary battery according to claim 1 or 2, comprising four skirts that are bent and extended downward from the top surface. [Section 4] Of the four skirts mentioned above, The prismatic secondary battery according to item 3, wherein the side skirt on which the first and second terminal portions are formed extends further downward than the other two front and rear skirts. [Section 5] The first electrode lead portion and the second electrode lead portion of the electrode assembly are A rectangular secondary battery as described in item 4, located at the top of the electrode assembly with respect to its central height. [Section 6] The first terminal section and the second terminal section are, The prismatic secondary battery according to claim 5, comprising: a first internal terminal and a second internal terminal disposed on the inside of the side skirt; and a first external terminal and a second external terminal electrically connected to the first internal terminal and the second internal terminal, respectively, and exposed on the outside of the upper case. [Section 7] The first electrode lead portion and the second electrode lead portion of the electrode assembly are The prismatic secondary battery according to item 6, wherein the first internal terminal and the second internal terminal are directly joined and electrically connected, respectively. [Section 8] The first external terminal and the second external terminal are located on the side skirt, respectively, in the rectangular secondary battery as described in item 7. [Section 9] The prismatic secondary battery as described in item 7, wherein the first external terminal and the second external terminal are each located on the top surface of the upper case. [Section 10] The prismatic secondary battery according to item 3, wherein the four skirts of the upper case are welded to the upper surface of the lower case. [Section 11] The aforementioned upper case is The prismatic secondary battery according to item 1 or 2, wherein the first electrode lead portion and the second electrode lead portion of the electrode assembly are joined to the first terminal portion and the second terminal portion and are inserted and coupled into the lower case in a state where they form a single unit. [Section 12] The prismatic secondary battery according to item 1 or 2, wherein the electrode assembly is a stacked electrode assembly or a wound electrode assembly. [Explanation of Symbols]

[0064] 10: Rectangular rechargeable battery 100: Upper case 110: Top surface 112: Skirt 113: Side skirt 114: Front skirt 115: Rear skirt 120: 1st terminal part 122: 1st internal terminal 124: First external terminal 130: 2nd terminal part 132: 2nd internal terminal 134: Second external terminal 140: Gas Venting Section 200: Electrode assembly 210: 1st side 220: First electrode lead section 230:Second side 240: Second electrode lead section 300: Lower case W: Welded section

Claims

1. An electrode assembly including a first electrode lead portion formed in a first lateral direction and a second electrode lead portion formed in a second lateral direction opposite to the first lateral direction, The structure has an open top surface and includes a lower case that houses the electrode assembly inside, Includes an upper case that covers the open upper surface of the lower case, The aforementioned upper case is A side skirt that is bent at the top surface covering the upper surface of the lower case, and a first terminal portion provided on one of the side skirts that extends downward in the first lateral direction, A side skirt bent from the top surface, the other of which is a side skirt extending downward in the second side direction, Includes, A rectangular secondary battery in which the first electrode lead portion is electrically connected to the first terminal portion, and the second electrode lead portion is electrically connected to the second terminal portion.

2. The rectangular secondary battery according to claim 1, including a gas vent portion formed on the top surface of the upper case.

3. The aforementioned upper case is The top surface covers the open upper surface of the lower case, A prismatic secondary battery according to claim 1 or 2, comprising four skirts that are bent and extended downward from the top surface.

4. An electrode assembly including a first electrode lead portion formed in a first lateral direction and a second electrode lead portion formed in a second lateral direction opposite to the first lateral direction, The structure has an open top surface and includes a lower case that houses the electrode assembly inside, Includes an upper case that covers the open upper surface of the lower case, The aforementioned upper case is The top surface covers the open upper surface of the lower case, Four skirts that are bent downward from the top surface, The skirt, which is bent at the top surface covering the upper surface of the lower case, has a first terminal portion provided on one of the side skirts of the skirt that extends downward in the first lateral direction, The skirt, which is bent at the top surface covering the upper surface of the lower case, and which extends downward in the second side direction, has a second terminal portion provided on the other side skirt, Includes, A rectangular secondary battery wherein the first electrode lead portion is electrically connected to the first terminal portion, and the second electrode lead portion is electrically connected to the second terminal portion, A rectangular secondary battery in which the side skirt on which the first and second terminal portions are formed extends further downward than the other two front and rear skirts.

5. The first electrode lead portion and the second electrode lead portion of the electrode assembly are A rectangular secondary battery according to claim 4, positioned at the top of the electrode assembly with respect to its central height.

6. The first terminal section and the second terminal section are, The prismatic secondary battery according to claim 5, comprising: a first internal terminal and a second internal terminal disposed on the inside of the side skirt; and a first external terminal and a second external terminal electrically connected to the first internal terminal and the second internal terminal, respectively, and exposed on the outside of the upper case.

7. The first electrode lead portion and the second electrode lead portion of the electrode assembly are The prismatic secondary battery according to claim 6, wherein the first internal terminal and the second internal terminal are directly joined and electrically connected, respectively.

8. The rectangular secondary battery according to claim 7, wherein the first external terminal and the second external terminal are each located on the side skirt.

9. The prismatic secondary battery according to claim 7, wherein the first external terminal and the second external terminal are each located on the top surface of the upper case.

10. The four skirts of the upper case are joined to the upper surface of the lower case by welding, as described in claim 3.

11. The prismatic secondary battery according to claim 1 or 2, wherein the electrode assembly is a stacked electrode assembly or a wound electrode assembly.

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