Secondary battery and secondary battery module

Abstract

A secondary battery according to the present invention comprises: an electrode assembly in which a positive electrode having a positive electrode tab protruding therefrom, a separator, and a negative electrode having a negative electrode tab protruding therefrom are alternately stacked; and a pouch accommodating the electrode assembly. The pouch is formed by stacking an inner resin layer, a metal layer, and an outer resin layer from the inside of the pouch where the electrode assembly is accommodated toward the outside of the pouch. In the pouch, a part of the inner resin layer is opened to expose a first exposed part of the metal layer to the inside of the pouch, and a part of the outer resin layer is opened to expose a second exposed part of the metal layer to the outside of the pouch, and one of the positive electrode tab and the negative electrode tab is in contact with the first exposed part.

Description

Secondary batteries and secondary battery modules

[0001] This application claims the benefit of priority from Korean Patent Application No. 10-2023-0083517, filed June 28, 2023, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a secondary battery and a secondary battery module provided by stacking a plurality of the secondary batteries, and more particularly, to a secondary battery and a secondary battery module capable of increasing energy density per unit area by removing one of two electrode leads (positive electrode lead, negative electrode lead).

[0003]

[0004] Demand for secondary batteries as an energy source is rapidly increasing in various fields, including personal mobile devices and electric vehicles.

[0005] Secondary batteries can be classified in various ways depending on the materials of the positive and negative electrodes and their external shapes. However, among these, lithium secondary batteries using lithium compound materials have a large capacity and a low self-discharge rate, and are widely used as replacements for conventional nickel-cadmium secondary batteries.

[0006] In addition, the lithium secondary battery can be manufactured in various forms, and is typically manufactured in a cylindrical type, a prismatic type, or a pouch type.

[0007] In this case, the pouch-type secondary battery has a structure in which the electrode assembly is built into a pouch, and each of the electrode tabs (negative tab and positive tab) of the electrode assembly is grouped together with those having the same polarity and then welded to the respective electrode leads (negative lead, positive lead). In addition, one end of the electrode leads has a structure in which they protrude outside the pouch so as to enable electrical connection with an external device.

[0008] And, the pouch has a structure in which an inner resin layer, a metal layer, and an outer resin layer are laminated from the inside to the outside to accommodate the electrode assembly. And, referring to Fig. 1a, which shows the appearance of a conventional secondary battery before the electrode assembly is mounted on the pouch and the appearance of the terrace portion being sealed after the electrode assembly is mounted, the pouch is formed with a concave cup portion (21) of a size sufficient to allow the electrode assembly to be inserted.

[0009] In addition, the terrace portion (20a) is formed to have a constant area so that sealing can be achieved along the edge of the cup portion (21). When the pouch (20) is folded along the folding line (the dashed-dotted line in FIG. 1a) while the electrode assembly (10) is mounted on the cup portion (21), sealing is achieved at the part where the terrace portions touch each other (the upper and lower areas of the pouch in FIG. 1a), and when sealing is achieved, the pouch is folded or cut to have a constant length. At this time, the electrode lead (12) connected to the positive tab (11) and the electrode lead (14) connected to the negative tab (13) each protrude from each of the two ends of the pouch (20).

[0010] A conventional secondary battery having such a structure is such that electrode leads (14, 14) having the same polarity are connected in parallel or electrode leads having different polarities are connected in series, as shown in Fig. 1b, which illustrates how conventional secondary batteries are electrically connected to each other.

[0011] However, within a confined space, this structure imposes spatial constraints equal to the length of the electrode leads. Furthermore, when manufacturing secondary battery modules, stacking secondary batteries also imposes spatial constraints equal to the length of the electrode leads.

[0012]

[0013] Accordingly, the main purpose of the present invention is to provide a secondary battery capable of increasing energy density per unit area (by deleting one of the electrode leads) and a secondary battery module in which a plurality of the secondary batteries are connected.

[0014]

[0015] In order to achieve the above-described object, the secondary battery provided in the present invention comprises an electrode assembly in which a positive electrode with a protruding positive electrode tab, a separator, and a negative electrode with a protruding negative electrode tab are alternately laminated; and a pouch for accommodating the electrode assembly, wherein the pouch is formed by laminating an inner resin layer, a metal layer, and an outer resin layer from an inner side accommodating the electrode assembly to an outer side, and wherein the pouch is characterized in that a part of the inner resin layer is opened so that a first exposed portion of the metal layer is exposed to the inner side of the pouch, a part of the outer resin layer is opened so that a second exposed portion of the metal layer is exposed to the outer side of the pouch, and either the positive electrode tab or the negative electrode tab is in contact with the first exposed portion.

[0016] And, it further includes an electrode lead whose end is connected to one of the positive and negative tabs and whose other end protrudes outside the pouch, and the other of the positive and negative tabs is in contact with the first exposed portion of the metal layer.

[0017] The pouch includes a cup portion in which the electrode assembly is accommodated; and a terrace portion formed along the periphery of the cup portion; and the first exposed portion of the metal layer is located in the terrace portion.

[0018] The above terrace portion includes a first region between the first exposed portion and the cup portion; and a second region located outside the first exposed portion.

[0019] The above first exposure portion is located on one side of the cup portion along the longitudinal direction.

[0020] The terrace portion of the above pouch has regions arranged on both sides with the cup portion in between along the longitudinal direction, and the area on the side where the first exposed portion is located is formed to be wider than the area on the opposite side.

[0021] The second exposed portion is arranged on one surface of the cup portion. In addition, a plurality of second exposed portions are formed.

[0022] The above second exposure portion may be formed at least once on both sides of the cup portion.

[0023] A conductor is bonded to the second exposed portion, and the conductor has a thickness that can protrude outward from the surface of the outer resin layer.

[0024] In addition, the present invention additionally provides a secondary battery module in which a plurality of secondary batteries having the above-described technical characteristics are stacked.

[0025] The secondary battery module provided in the present invention is characterized in that a plurality of secondary batteries are stacked, and adjacent secondary batteries are electrically connected to each other through their second exposed portions.

[0026] The secondary battery included in the secondary battery module provided in the present invention has two parallel planes of pouches, and adjacent secondary batteries are stacked so that the planes of the pouches are in contact with each other, and at least one second exposed portion is formed on each plane, and an insulating tape is attached to the second exposed portion exposed to the outside of the outermost secondary battery.

[0027]

[0028] Since the metal layer of the pouch having the above technical characteristics can replace the electrode lead of either the negative electrode or the positive electrode, the width of the secondary battery can be reduced, and thus the volume can be reduced when stacked into a secondary battery module.

[0029] Furthermore, with the removal of one electrode lead, the welding process for welding the electrode tabs and the electrode lead, as well as the welding process for welding the electrode leads and the busbar after stacking the secondary batteries, are reduced, thereby further increasing production efficiency. Furthermore, since the size is reduced by the length of the removed electrode lead, the energy density can be further improved compared to the conventional structure with the same size.

[0030] The first exposed portion of the metal layer is located on the terrace portion where sealing is performed, so that a conventional electrode assembly can be used as is without deformation or movement of the electrode tab.

[0031] The first exposed portion is positioned on one side of the cup portion along the longitudinal direction among the terrace portions. Accordingly, since the pouch is folded along a folding line parallel to the longitudinal direction, the first exposed portion can contact both sides of the electrode tab, thereby increasing the contact surface area. Furthermore, the area can be reduced compared to when formed at another location on the terrace portion.

[0032] The terrace portion of the above pouch has regions arranged on both sides with the cup portion in the longitudinal direction, and the area on the side where the first exposed portion is located is formed to be wider than the area on the opposite side. Accordingly, an appropriate sealing area can be secured even in the area where the first exposed portion is located.

[0033] The second exposed portions are formed in multiple numbers to facilitate smooth current flow. In addition, a conductor is coupled to the second exposed portions to ensure stable electrical connection between adjacent secondary batteries.

[0034] Additionally, insulation tape can be attached to the second exposed portion that is not electrically connected to further enhance safety.

[0035]

[0036] Figure 1a is a drawing showing the appearance of a conventional secondary battery before the electrode assembly is mounted on the pouch and the appearance of the terrace portion being sealed after the electrode assembly is mounted.

[0037] Figure 1b is a drawing showing a conventional secondary battery electrically connected to each other.

[0038] Figure 2 is a drawing showing the appearance of the secondary battery provided in the present invention before the electrode assembly is mounted on the pouch and the appearance of the terrace portion being sealed after the electrode assembly is mounted.

[0039] Figure 3 is an enlarged view of part A in Figure 2.

[0040] Figure 4 is an enlarged view of part B in Figure 2.

[0041] Figure 5 is a drawing showing the inner and outer surfaces of the pouch provided in the present invention.

[0042] Figure 6 is a drawing sequentially showing the steps of manufacturing a secondary battery according to the present invention.

[0043] Figure 7 is a drawing showing secondary batteries alternately stacked with electrode leads facing different directions.

[0044] Fig. 8 is a drawing showing a conductor inserted between adjacent secondary batteries in the stacked configuration of Fig. 7.

[0045] Figure 9 is a drawing showing secondary batteries stacked so that the electrode leads face the same direction.

[0046] FIG. 10 is a drawing showing an insulating tape attached to the second exposed portion of one of the secondary batteries located at the outermost end in the stacked form of FIG. 9, and a terminal of an external device connected to the second exposed portion of the other.

[0047]

[0048] Hereinafter, the present invention will be described in detail with reference to the attached drawings so that those skilled in the art can easily practice the present invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0049] In order to clearly explain the present invention, parts that are not related to the description are omitted, and the same reference numerals are used for identical or similar components throughout the specification.

[0050] In addition, terms and words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0051] The present invention relates to a secondary battery and a secondary battery module capable of increasing energy density per unit area by removing one of two electrode leads. Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the attached drawings.

[0052]

[0053] First embodiment

[0054] In the present invention, a pouch-type secondary battery capable of increasing energy density per unit area by removing one of two electrode leads is provided as a first embodiment.

[0055] FIG. 2 is a drawing showing the appearance of the secondary battery provided in the present invention before the electrode assembly is mounted on the pouch and the appearance of the terrace portion being sealed after the electrode assembly is mounted. FIG. 3 is an enlarged drawing of part A in FIG. 2, and FIG. 4 is an enlarged drawing of part B in FIG. 2. FIG. 5 is a drawing showing the inner and outer sides of the pouch provided in the present invention, and FIG. 6 is a drawing sequentially showing the appearance of the secondary battery being manufactured according to the present invention.

[0056] Referring to the drawings, the electrode assembly (10) provided in this embodiment is manufactured by alternately stacking a positive electrode with a protruding positive electrode tab (11), a separator, and a negative electrode with a protruding negative electrode tab (13), as in a conventional structure.

[0057] At this time, the positive electrode tab (11) and the negative electrode tab (13) are arranged to face opposite to each other along the electric field direction. Then, the positive electrode tab (11) is placed in the pouch (20) in a state in which it is connected to the electrode lead (12), which becomes the positive lead, while the negative electrode tab (13) is placed in the pouch (20) without being connected to the electrode lead.

[0058] That is, the electrode assembly (10) is mounted on the cup portion (21, 22) of the pouch (20), and the electrode lead (12) and the negative electrode tab (13) connected to the positive electrode tab (11) are mounted so as to be placed on the terrace portion (20a) of the pouch (20). At this time, the end of the electrode lead (12) connected to the positive electrode tab (11) protrudes from the terrace portion (20a) of the pouch (20). The electrode lead may also be provided in a state of being connected to the negative electrode tab (13) instead of the positive electrode tab (11).

[0059] The pouch (20) that accommodates the electrode assembly (10) is formed by laminating an inner resin layer (25), a metal layer (26), and an outer resin layer (27) from the inside to the outside where the electrode assembly (10) is accommodated.

[0060] And, as shown in FIG. 3, a part of the inner resin layer (25) of the pouch (20) is opened so that the first exposed portion (23) of the metal layer (26) is exposed to the inside of the pouch (20), and as shown in FIG. 4, a part of the outer resin layer (27) is opened so that the second exposed portion (24) of the metal layer (26) is exposed to the outside of the pouch (20).

[0061] When the electrode assembly (10) is installed, the negative electrode tab (13) is installed so as to be in contact with the first exposed portion (23). Conversely, if the electrode lead is connected to the negative electrode tab (13), the positive electrode tab has the electrode lead removed and the positive electrode tab is installed so as to be bonded to the first exposed portion (23). That is, the electrode assembly (10) provided in this embodiment includes an electrode lead whose end is connected to one of the positive electrode tab (11) and the negative electrode tab (13) and whose other end protrudes outside the pouch (20), and the other of the positive electrode tab (11) and the negative electrode tab (13) is installed in the pouch (20) so as to be in contact with the first exposed portion (23) of the metal layer (26).

[0062] The pouch (20) provided in this embodiment is configured to include a cup portion (21, 22) having a concave fine shape so that an electrode assembly (10) can be accommodated, and a terrace portion (20a) extended to a certain area along the edge of the cup portion (21, 22). In addition, the first exposed portion (23) is located in the terrace portion (20a) and not in the cup portion, as illustrated in FIG. 5.

[0063] At this time, the first exposed portion (23) may be formed inside the cup portion so that the negative tab (13) to which the electrode lead is not connected is not placed on the terrace portion but is connected to the inside of the cup portion in a bent state. However, in this case, there is a possibility that the negative tab (13) may be disconnected due to bending and a short circuit may occur due to contact with the positive electrode. Therefore, in the embodiment provided by the present invention, the negative tab (13) is positioned on the terrace portion (20a) without being bent.

[0064] Meanwhile, the first exposed portion (23) is located on one side of the cup portion (21) along the longitudinal direction. And, as shown in Fig. 6, the area where the first exposed portion (23) is located in the terrace portion (20a) can be divided into a first area (c) between the first exposed portion (23) and the cup portion (21), a middle area (d) where the first exposed portion (23) is located, and a second area (e) located outside the first exposed portion (23).

[0065] At this time, although it may vary depending on the area and shape of the first exposed portion (23), it is preferable that the first region (c) and the second region (e) be formed smaller than the middle region (d) in consideration of the sealing performance and the total length of the secondary battery. In addition, the area of ​​the first region (c) and the area of ​​the second region (d) may be designed such that one is formed wider than the other in consideration of the sealing performance.

[0066] In addition, the terrace portion (20a) of the pouch has regions (a, b) arranged on both sides with the cup portion (21) in between along the longitudinal direction, and in order to secure appropriate sealing performance, the area (b) on the side where the first exposed portion (23) is located is formed to be wider than the area (a) on the opposite side.

[0067] And, the second exposed portion (24) is arranged on one surface of the cup portion (21, 22) spaced apart from the opposite part (F) of the position where the first exposed portion (23) is formed. More specifically, as shown in Fig. 4, it is formed on the outer surface of each of the two cup portions (21, 22). However, when stacked as a secondary battery module, if it is a secondary battery arranged at the outermost end, the second exposed portion (24) may be formed on only one of the two cup portions (21, 22).

[0068] At this time, the second exposed portions (24) may be formed in multiple numbers spaced apart from each other, and their area and shape may vary depending on the capacity of the secondary battery. In addition, since the entire metal layer (26) is electrically conductive, the second exposed portions (24) may be selectively formed anywhere on the terrace portion (20a) except for the area where the electrode lead (12) protrudes, even if it is not the cup portion (21, 22).

[0069] In addition, when stacked as in Fig. 7, at least one cup portion (21, 22) can be formed on both sides of the upper and lower surfaces, respectively, so that it can be electrically connected to the secondary batteries placed on the upper and lower layers.

[0070] In addition, since the pouch (20) has a structure in which an inner resin layer (25), a metal layer (26), and an outer resin layer (27) are laminated, the thickness of the outer resin layer (27) is sufficiently thin, but interference may occur in the contact of the facing metal layers (26) due to the outer resin layer (27) (as shown in FIG. 4).

[0071] To prevent this, as shown in Fig. 8, a conductor (30) may be coupled to the second exposed portion (24). At this time, the conductor (30) has a thickness that can protrude outward from the surface of the outer resin layer (27) when coupled to the second exposed portion (24), but is limited to a thickness that does not create a gap when secondary batteries are stacked.

[0072]

[0073] Second embodiment

[0074] In the present invention, a secondary battery module in which a plurality of secondary batteries provided in the first embodiment are stacked is provided as a second embodiment.

[0075] FIG. 7 is a drawing showing a state in which secondary batteries are alternately stacked so that their electrode leads face different directions, and FIG. 8 is a drawing showing a state in which a conductor is inserted between adjacent secondary batteries in the stacked state of FIG. 7. In addition, FIG. 9 is a drawing showing a state in which secondary batteries are stacked so that their electrode leads face the same direction, and FIG. 10 is a drawing showing a state in which an insulating tape (50) is attached to a second exposed portion (24) of one of the outermost secondary batteries in the stacked state of FIG. 9, and a terminal (40) of an external device is connected to the second exposed portion (24) of another one.

[0076] The secondary battery module provided in this embodiment is configured by stacking a plurality of secondary batteries, and as shown, the neighboring secondary batteries are electrically connected to each other by contacting each other's second exposed portions (24).

[0077] That is, the secondary batteries are formed with two planes in which the outer surfaces of the cup portions (21, 22) on both sides are parallel to each other, and the adjacent secondary batteries are stacked so that the outer surfaces of the cup portions (21, 22) that are flat are in contact with each other. In addition, the second exposed portions (24) are formed at least once on each plane and are in contact with the second exposed portions (24) of the adjacent secondary batteries.

[0078] At this time, as described above, a conductor (30) may be coupled to the second exposed portion (24). In addition, the second exposed portion (24) of one of the secondary batteries located at the outermost end may be electrically connected to a terminal (40) of an external device, and an insulating tape (50) having electrical insulation properties may be attached to the second exposed portion (24) of another externally exposed portion to prevent a short circuit from occurring.

[0079] For reference, as shown in FIGS. 8 and 9, the electrode leads (12) may all be connected by protruding in the same direction, or may be configured to be connected by dividing in opposite directions.

[0080]

[0081] Since the metal layer (26) of the pouch (20) having the above-described technical characteristics can replace one of the electrode leads of the negative electrode or the positive electrode, the width of the secondary battery can be reduced, and accordingly, the volume can be reduced when stacked as a secondary battery module.

[0082] Furthermore, with the removal of one electrode lead, the welding process for welding the electrode tabs and the electrode lead, as well as the welding process for welding the electrode leads and the busbar after stacking the secondary batteries, are reduced, thereby further increasing production efficiency. Furthermore, since the size is reduced by the length of the removed electrode lead, the energy density can be further improved compared to the conventional structure with the same size.

[0083] The first exposed portion of the metal layer is located on the terrace portion where sealing is performed, so that a conventional electrode assembly can be used as is without deformation or movement of the electrode tab.

[0084] The first exposed portion is positioned on one side of the cup portion along the longitudinal direction among the terrace portions. Accordingly, since the pouch is folded along a folding line parallel to the longitudinal direction, the first exposed portion can contact both sides of the electrode tab, thereby increasing the contact surface area. Furthermore, the area can be reduced compared to when formed at another location on the terrace portion.

[0085] The terrace portion of the above pouch has regions arranged on both sides with the cup portion in the longitudinal direction, and the area on the side where the first exposed portion is located is formed to be wider than the area on the opposite side. Accordingly, an appropriate sealing area can be secured even in the area where the first exposed portion is located.

[0086] The second exposed portions are formed in multiple numbers to facilitate smooth current flow. In addition, a conductor is coupled to the second exposed portions to ensure stable electrical connection between adjacent secondary batteries.

[0087] Additionally, insulation tape can be attached to the second exposed portion that is not electrically connected to further enhance safety.

[0088] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and various embodiments are possible within the scope equivalent to the technical idea of ​​the present invention and the patent claims to be described below by a person having ordinary skill in the art to which the present invention pertains.

[0089]

[0090] [Explanation of symbols]

[0091] 10: Electrode assembly

[0092] 20: Pouch

[0093] 20a: Terrace

[0094] 21, 22: Cup

[0095] 23: First exposure

[0096] 24: Second exposure

Claims

1. An electrode assembly in which a positive electrode with a protruding positive tab, a separator, and a negative electrode with a protruding negative tab are alternately laminated; and A pouch for accommodating the electrode assembly is included, The above pouch is formed by laminating an inner resin layer, a metal layer, and an outer resin layer from the inside to the outside to accommodate the electrode assembly. The pouch has a part of the inner resin layer opened so that the first exposed portion of the metal layer is exposed to the inside of the pouch, and a part of the outer resin layer opened so that the second exposed portion of the metal layer is exposed to the outside of the pouch. A secondary battery in which either the positive tab or the negative tab is in contact with the first exposed portion.

2. In paragraph 1, First, it further includes an electrode lead that is connected to one of the positive and negative tabs and has the other end protruding outside the pouch. A secondary battery in which the other of the positive and negative tabs is in contact with the first exposed portion of the metal layer.

3. In paragraph 2, The above pouch is, A cup portion in which the electrode assembly is accommodated; and including a terrace portion formed along the perimeter of the cup portion; A secondary battery in which the first exposed portion of the metal layer is located on the terrace portion.

4. In paragraph 3, The above terrace section, A first region between the first exposed portion and the cup portion; and A secondary battery including a second region located outside the first exposed portion.

5. In paragraph 4, The above first exposure portion is a secondary battery located on one side of the cup portion along the longitudinal direction.

6. In paragraph 4, A secondary battery in which the terrace portion of the above pouch has regions arranged on both sides with the cup portion in between along the longitudinal direction, and the area of ​​the region on the side where the first exposure portion is located is formed wider than the area of ​​the opposite region.

7. In paragraph 3, The above second exposure portion is a secondary battery arranged on one side of the cup portion.

8. In paragraph 1, The above second exposed portion is a secondary battery formed in multiple numbers.

9. In paragraph 8, The above second exposure portion is a secondary battery formed at least once on both sides of the cup portion.

10. In paragraph 1, A secondary battery in which a conductor is bonded to the second exposed portion, and the conductor has a thickness that can protrude outward from the surface of the outer resin layer.

11. A secondary battery module including the secondary battery described in paragraph 1, wherein a plurality of the secondary batteries are stacked, and the adjacent secondary batteries are in contact with each other so that their second exposed portions are electrically connected to each other.

12. In paragraph 11, The above secondary battery has two planes of pouches that are parallel to each other, and adjacent secondary batteries are stacked so that the planes of the pouches touch each other. The above second exposure portion is formed at least once on each plane, A secondary battery module in which an insulating tape is attached to the second exposed portion of the secondary battery located at the outermost part.

Images