Secondary batteries and secondary battery modules

Abstract

The secondary battery according to the present invention includes an electrode assembly in which a positive electrode with a protruding positive electrode tab, a separator membrane, and a negative electrode with a protruding negative electrode tab are alternately stacked; and a pouch for housing the electrode assembly, wherein the pouch is formed by stacking an internal resin layer, a metal layer, and an external resin layer from the inside to the outside of the pouch housing the electrode assembly, and the pouch is characterized in that a part of the internal resin layer is open so that a first exposed portion of the metal layer is exposed to the inside of the pouch, a part of the external resin layer is open so that a second exposed portion of the metal layer is exposed to the outside of the pouch, and either the positive electrode tab or the negative electrode tab is in contact with the first exposed portion.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0083517 filed on Jun. 28, 2023, and all the contents disclosed in the Korean Patent Application are incorporated herein by reference in their entirety.

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

Background Art

[0003] The demand for secondary batteries as an energy source has been rapidly increasing in various fields, including personal mobile devices and the field of electric vehicles.

[0004] Secondary batteries can be classified in various ways according to the materials of the positive and negative electrodes and the external shape. Among them, lithium secondary batteries using lithium compound materials are widely used instead of conventional nickel-cadmium secondary batteries because of their large capacity and low self-discharge rate.

[0005] The lithium secondary batteries can be manufactured in various forms, and typically, they are generally manufactured in a cylindrical type, a prismatic type, or a pouch type.

[0006] Among them, the pouch-type secondary battery has a structure in which an electrode assembly is built into a pouch. At this time, each of the electrode tabs (negative electrode tab and positive electrode tab) of the electrode assembly is welded to each electrode lead (negative electrode lead and positive electrode lead) after the ones having the same polarity are gathered together. And one end of the lead has a structure protruding outside the pouch so as to be electrically connected to an external device.

[0007] The pouch has a structure in which an internal resin layer, a metal layer, and an external resin layer are laminated from the inside to the outside, containing the electrode assembly. Referring to Figure 1a, which illustrates the state of a conventional secondary battery before the electrode assembly is mounted in the pouch and the state after the electrode assembly is mounted and the terrace portion is sealed, the pouch has a concave cup portion 21 formed to a size that allows the electrode assembly to be inserted.

[0008] In addition, the terrace portion 20a is formed to have a certain area so that sealing can be performed along the edge of the cup portion 21. When the pouch 20 is folded along the fold line (dotted line in Figure 1a) with the electrode assembly 10 mounted on the cup portion 21, sealing is performed at the parts where the terrace portions abut each other (upper and lower end regions of the pouch in Figure 1a), and once sealing is performed, it is folded or cut to a certain length. At this time, the electrode lead 12 connected to the positive electrode tab 11 and the electrode lead 14 connected to the negative electrode tab 13 each protrude from the respective ends of the pouch 20.

[0009] In conventional secondary batteries having such a structure, as shown in Figure 1b which illustrates the state in which conventional secondary batteries are electrically connected to each other, electrode leads 14, 14 having the same polarity are connected in parallel, or electrode leads having different polarities are connected in series.

[0010] However, within a limited space, such a structure imposes spatial constraints proportional to the length of the electrode leads. Furthermore, when manufacturing secondary battery modules and stacking the batteries, spatial constraints are also proportional to the length of the electrode leads. [Overview of the project] [Problems that the invention aims to solve]

[0011] Therefore, the main object of the present invention is to provide a secondary battery that can increase the same area-to-energy density by removing one of the electrode leads, and a secondary battery module in which multiple such secondary batteries are connected. [Means for solving the problem]

[0012] To achieve the aforementioned objectives, the secondary battery provided in the present invention includes an electrode assembly in which a positive electrode with a protruding positive electrode tab, a separator membrane, and a negative electrode with a protruding negative electrode tab are alternately stacked; and a pouch for housing the electrode assembly, wherein the pouch is formed by stacking an internal resin layer, a metal layer, and an external resin layer from the inside to the outside of the pouch housing the electrode assembly, and the pouch is characterized in that a part of the internal resin layer is open so that a first exposed portion of the metal layer is exposed to the inside of the pouch, a part of the external resin layer is open so that a second exposed portion of the metal layer is exposed to the outside of the pouch, and either the positive electrode tab or the negative electrode tab is in contact with the first exposed portion.

[0013] One end is connected to either the positive or negative electrode tab, and the other end further includes an electrode lead that protrudes outside the pouch, with the other of the positive or negative electrode tab in contact with a first exposed portion of the metal layer.

[0014] The pouch includes a cup portion in which the electrode assembly is housed, and a terrace portion formed around the periphery of the cup portion, wherein the first exposed portion of the metal layer is located on the terrace portion.

[0015] The 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.

[0016] The first exposed portion is located on one side of the cup portion along the entire length of the secondary battery.

[0017] The terrace portion of the pouch has regions arranged on both sides of the cup portion along the overall length of the secondary battery, and the area on the side where the first exposed portion is located is formed to be even wider than the area on the opposite side.

[0018] The second exposed portion may be arranged on one surface of the cup portion, and multiple second exposed portions may be formed.

[0019] The second exposed portion may be formed on both sides of the cup portion, at least one on each side.

[0020] A conductor is bonded to the second exposed portion, and the conductor has a thickness that allows it to protrude outward from the surface of the outer resin layer.

[0021] Furthermore, the present invention provides a secondary battery module in which a plurality of secondary batteries having the above-described technical features are stacked.

[0022] The secondary battery module provided in the present invention is characterized in that a large number of secondary batteries are stacked, and adjacent secondary batteries are in contact with each other such that their second exposed portions are electrically connected to one another.

[0023] The secondary batteries included in the secondary battery module provided in the present invention have a pouch with two parallel planes, 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 insulating tape is attached to the second exposed portion of the outermost secondary battery that is exposed to the outside. [Effects of the Invention]

[0024] Since the metal layer of the pouch having the aforementioned technical characteristics can replace one of the electrode leads, either the negative or positive electrode, the area of ​​the secondary battery can be reduced, thereby reducing the volume when stacked in a secondary battery module.

[0025] In addition, since the welding process of welding the electrode tab and the electrode lead and the welding process of welding the electrode lead and the bus bar after stacking the secondary battery are reduced by deleting one side electrode lead, the production efficiency can be further increased. And since the size is reduced by the length of the deleted electrode lead, when having the same size, the energy density can be further improved compared with the conventional structure.

[0026] Since the first exposed portion of the metal layer is located in the terrace portion where sealing is performed, the conventional electrode assembly can be used as it is without deformation or movement of the electrode tab.

[0027] The first exposed portion is located on one side of the cup portion along the entire length direction among the terrace portions. Since the pouch is folded along a folding line parallel to the entire length direction, the first exposed portion can contact both surfaces of the electrode tab to increase the contact surface. Also, the area can be reduced compared to the case where it is formed at other positions of the terrace portion.

[0028] The terrace portion of the pouch has regions arranged on both sides sandwiching the cup portion along the entire length direction, and the width of the region on the side where the first exposed portion is located is formed wider than the width of the region on the opposite side. Thereby, an appropriate sealing area can be ensured even in the region where the first exposed portion is arranged.

[0029] The second exposed portions are formed in plural and the current can flow more smoothly. Also, a conductor is coupled to the second exposed portion, and the stability of the electrical connection between adjacent secondary batteries can be ensured.

[0030] In addition, an insulating tape is attached to the second exposed portions that are not electrically connected, and the safety can be further enhanced.

Brief Description of the Drawings

[0031] [Figure 1a]This diagram illustrates the state of a conventional secondary battery before the electrode assembly is mounted in the pouch, and the state after the electrode assembly has been mounted and the terrace portion has been sealed. [Figure 1b] This diagram illustrates a state in which two conventional rechargeable batteries are electrically connected to each other. [Figure 2] This diagram illustrates the secondary battery provided by the present invention, showing the state before the electrode assembly is mounted in the pouch, and the state after the electrode assembly is mounted and the terrace portion is sealed. [Figure 3] This is a magnified view of section A in Figure 2. [Figure 4] This is a magnified view of section B in Figure 2. [Figure 5] This is a drawing illustrating the inner and outer surfaces of the pouch provided in the present invention. [Figure 6] This diagram sequentially illustrates the process by which a secondary battery is manufactured according to the present invention. [Figure 7] This diagram illustrates a configuration in which secondary batteries are stacked alternately, with the electrode leads pointing in different directions. [Figure 8] Figure 7 is a diagram illustrating a stacked configuration in which a conductor is inserted between adjacent secondary batteries. [Figure 9] This diagram illustrates a stacked configuration of secondary batteries, with the electrode leads pointing in the same direction. [Figure 10] Figure 9 shows a stacked configuration in which insulating tape is attached to the second exposed portion of one of the outermost secondary batteries, and the terminals of an external device are connected to the other second exposed portion. [Modes for carrying out the invention]

[0032] The present invention will be described in detail below with reference to the attached drawings, so that it can be easily implemented by a person with ordinary skill in the art to which the invention pertains. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0033] To clearly explain the present invention, irrelevant parts have been omitted, and the same or similar reference numerals are used throughout the specification for identical or similar components.

[0034] Furthermore, the terms and words used in this specification and the claims shall not be interpreted in a manner limited to their ordinary or dictionary meanings, but rather in a manner consistent with the technical idea of ​​the present invention, in accordance with the principle that inventors may appropriately define the concepts of terms in order to best describe their invention.

[0035] The present invention relates to a secondary battery and a secondary battery module that can increase the energy density relative to the same area by removing one of the two electrode leads. Preferred embodiments of the present invention will be described in more detail below with reference to the attached drawings.

[0036] First Embodiment In the present invention, as a first embodiment, a pouch-type secondary battery is provided in which one of the two electrode leads is removed, thereby increasing the energy density relative to the same area.

[0037] Figure 2 is a diagram illustrating the secondary battery provided by the present invention, showing the state before the electrode assembly is mounted on the pouch and the state after the electrode assembly is mounted and the terrace portion is sealed. Figure 3 is an enlarged view of portion A in Figure 2. Figure 4 is an enlarged view of portion B in Figure 2. Figure 5 is a diagram showing the inner and outer surfaces of the pouch provided by the present invention. Figure 6 is a diagram illustrating the manufacturing process of the secondary battery according to the present invention in sequence.

[0038] 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 membrane, and a negative electrode with a protruding negative electrode tab 13, similar to the conventional structure.

[0039] In this configuration, the positive electrode tab 11 and the negative electrode tab 13 are positioned so as to face opposite directions along their entire length. The positive electrode tab 11 is then attached to the pouch 20 in a bonded state to the electrode lead 12, which will become the positive electrode lead, while the negative electrode tab 13 is attached to the pouch 20 without being bonded to the electrode lead.

[0040] In other words, the electrode assembly 10 is fixed to the cup portions 21 and 22 of the pouch 20, and the electrode lead 12 connected to the positive electrode tab 11 and the negative electrode tab 13 are fixed so that they are placed on the terrace portion 20a of the pouch 20. At this time, the end of the electrode lead 12 joined to the positive electrode tab 11 protrudes from the terrace portion 20a of the pouch 20. The electrode lead may be provided joined to the negative electrode tab 13 instead of the positive electrode tab 11.

[0041] The pouch 20 that houses the electrode assembly 10 is formed by laminating an internal resin layer 25, a metal layer 26, and an external resin layer 27 from the inside to the outside, with the electrode assembly 10 being housed within it.

[0042] As shown in Figure 3, the pouch 20 has a portion of the internal resin layer 25 open, exposing the first exposed portion 23 of the metal layer 26 to the inside of the pouch 20, and as shown in Figure 4, a portion of the external resin layer 27 open, exposing the second exposed portion 24 of the metal layer 26 to the outside of the pouch 20.

[0043] When the electrode assembly 10 is fixed in place, the negative electrode tab 13 is fixed in place so as to be in contact with the first exposed portion 23. Conversely, when the electrode lead is joined to the negative electrode tab 13, the electrode lead is removed from the positive electrode tab and the positive electrode tab is fixed in place so as to be in contact with the first exposed portion 23. That is, the electrode assembly 10 provided in this embodiment has one end connected to either the positive electrode tab 11 or the negative electrode tab 13, and the other end includes an electrode lead that protrudes outside the pouch 20, and the other of the positive electrode tab 11 or the negative electrode tab 13 is fixed to the pouch 20 so as to be in contact with the first exposed portion 23 of the metal layer 26.

[0044] The pouch 20 provided in this embodiment includes cup portions 21 and 22 having a recessed shape so as to accommodate the electrode assembly 10, and a terrace portion 20a extending to a certain area along the edges of the cup portions 21 and 22. The first exposed portion 23 is located on the terrace portion 20a rather than the cup portion, as shown in Figure 5.

[0045] In this case, the first exposed portion 23 may be formed inside the cup portion so that the negative electrode tab 13, which does not have an electrode lead attached, is connected to the inside of the cup portion in a bent state rather than being placed on the terrace portion. However, in this case, there is a possibility of the negative electrode tab breaking due to bending of the negative electrode tab 13, or of a short circuit occurring due to contact with the positive electrode. Therefore, in the embodiment provided by the present invention, the negative electrode tab 13 is located on the terrace portion 20a without bending occurring.

[0046] On the other hand, the first exposed portion 23 is located along the entire length of the cup portion 21 on one side. As shown in Figure 6, the area in the terrace portion 20a where the first exposed portion 23 is located may be divided into a first region c between the first exposed portion 23 and the cup portion 21, an intermediate region d where the first exposed portion 23 is located, and a second region e located outside the first exposed portion 23.

[0047] In this case, 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 intermediate region d, taking into consideration the sealing performance and the total length of the secondary battery. Furthermore, the areas of the first region c and the second region d may be designed so that one of them is larger than the other, taking into consideration the sealing performance.

[0048] In addition, the terrace portion 20a of the pouch has regions a and b arranged on both sides of the cup portion 21 along its entire length, and in order to ensure proper sealing performance, the area b on the side where the first exposed portion 23 is located is formed to be even wider than the area a on the opposite side.

[0049] The second exposed portion 24 is positioned on one surface of the cup portions 21 and 22, separated from the portion F opposite to the position where the first exposed portion 23 is formed. More specifically, as shown in Figure 4, it is formed on the outer surfaces of each of the two cup portions 21 and 22. However, when stacked into a secondary battery module, if it is the outermost secondary battery, the second exposed portion 24 may be formed at only one of the two cup portions 21 and 22.

[0050] In this case, the second exposed portion 24 may be formed in multiple locations spaced apart from each other, and its area and shape may change depending on the capacity of the secondary battery. In addition, since the entire metal layer 26 is electrically conductive, the second exposed portion 24 may be selectively formed anywhere on the terrace portion 20a, excluding the area where the electrode leads 12 protrude, rather than on the cup portions 21 and 22.

[0051] Furthermore, when stacked as shown in Figure 7, at least one cup portion may be formed on each of the top and bottom surfaces of the cup portions 21 and 22, respectively, so that they can be electrically connected to the secondary batteries placed in the upper and lower layers.

[0052] Furthermore, since the pouch 20 has a structure in which an internal resin layer 25, a metal layer 26, and an external resin layer 27 are laminated, although the thickness of the external resin layer 27 is sufficiently thin (as shown in Figure 4), interference may occur in the contact between the opposing metal layers 26 due to the external resin layer 27.

[0053] To prevent this, a conductor 30 may be bonded to the second exposed portion 24, as shown in Figure 8. In this case, the conductor 30 has a thickness such that it can protrude outward from the surface of the outer resin layer 27 when bonded to the second exposed portion 24, and is limited to a thickness that does not create gaps when the secondary batteries are stacked together.

[0054] Second Embodiment In the present invention, a secondary battery module is provided as a second embodiment, in which multiple secondary batteries provided in the first embodiment are stacked.

[0055] Figure 7 is a diagram illustrating a state in which secondary batteries are stacked alternately so that the electrode leads are oriented in different directions. Figure 8 is a diagram illustrating a state in which a conductor is inserted between adjacent secondary batteries in the stacked state shown in Figure 7. And Figure 9 is a diagram illustrating a state in which secondary batteries are stacked so that the electrode leads are oriented in the same direction. Figure 10 is a diagram illustrating a state in which, in the stacked state shown in Figure 9, an insulating tape 50 is attached to the second exposed portion 24 of one of the outermost secondary batteries, and the terminal 40 of an external device is connected to the other second exposed portion 24.

[0056] In this embodiment, the secondary battery module is made up of multiple secondary batteries stacked together, and as shown in the figure, adjacent secondary batteries are electrically connected to each other by the contact of their second exposed portions 24.

[0057] In other words, the secondary battery has two parallel planes on both sides of the cup portions 21 and 22, and adjacent secondary batteries are stacked so that their planar outer surfaces 21 and 22 touch each other. At least one second exposed portion 24 is formed on each plane and comes into contact with the second exposed portion 24 of adjacent secondary batteries.

[0058] In this case, as described above, a conductor 30 may be connected to the second exposed portion 24. One of the outermost second exposed portions 24 of the secondary battery may be electrically connected to the terminal 40 of an external device, and an insulating tape 50 having electrical insulating properties may be attached to the other externally exposed second exposed portion 24 to prevent short circuits.

[0059] For reference, as shown in Figures 8 and 9, the electrode leads 12 may all be connected with protrusions in the same direction, or they may be configured to be connected separately in opposite directions.

[0060] Since the metal layer 26 of the pouch 20 having the aforementioned technical features can replace one of the electrode leads, either the negative or positive electrode, the area of ​​the secondary battery can be reduced, thereby reducing the volume when stacked in a secondary battery module.

[0061] Furthermore, by eliminating one electrode lead, the welding process for welding the electrode tab and electrode lead, and the welding process for welding the electrode lead and busbar after stacking the secondary battery, are reduced, thereby further increasing production efficiency. Also, since the size is reduced by the length of the removed electrode lead, the energy density can be further improved compared to conventional structures for the same size.

[0062] Since the first exposed portion of the metal layer is located in the terrace area where sealing is performed, the conventional electrode assembly can be used as is without deformation or movement of the electrode tab.

[0063] The first exposed portion is located along the entire length of the terrace portion, on one side of the cup portion. Since the pouch is folded along a fold line parallel to the entire length, the first exposed portion can contact both sides of the electrode tab, increasing the contact surface area. Furthermore, the area can be reduced compared to when it is formed at other locations on the terrace portion.

[0064] The terrace portion of the pouch has regions arranged on both sides of the cup portion along its entire length, and the region on the side where the first exposed portion is located is formed to be even wider than the region on the opposite side. This ensures that an appropriate sealing area can be secured even in the region where the first exposed portion is located.

[0065] The second exposed portion is formed in multiple units to allow current to flow even more smoothly. Furthermore, a conductor is coupled to the second exposed portion to ensure the stability of the electrical connection between adjacent secondary batteries.

[0066] Furthermore, insulating tape can be attached to the second exposed portion that is not electrically connected, further enhancing safety.

[0067] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and can be implemented in various ways by persons with ordinary skill in the art to which the present invention pertains, within the equivalent scope of the claims described separately from the technical concept of the present invention. [Explanation of Symbols]

[0068] 10 Electrode assembly 20 pouches 20a Terrace section 21, 22 Cup section 23 1st exposed part 24 2nd exposed part

Claims

1. An electrode assembly in which a positive electrode with a protruding positive electrode tab, a separator membrane, and a negative electrode with a protruding negative electrode tab are alternately stacked; and Includes a pouch for housing the electrode assembly, The aforementioned pouch is formed by laminating an internal resin layer, a metal layer, and an external resin layer from the inside outwards, which house the electrode assembly. The pouch is configured such that a portion of the inner resin layer is open, exposing a first exposed portion of the metal layer to the inside of the pouch, and a portion of the outer resin layer is open, exposing a second exposed portion of the metal layer to the outside of the pouch. A secondary battery in which either the positive electrode tab or the negative electrode tab is in contact with the first exposed portion.

2. One end is connected to either the positive or negative electrode tab, and the other end further includes an electrode lead that protrudes outside the pouch. The secondary battery according to claim 1, wherein one of the positive electrode tab and the negative electrode tab is in contact with a first exposed portion of the metal layer.

3. The aforementioned pouch is The cup portion in which the electrode assembly is housed; and Includes a terrace portion formed along the periphery of the cup portion; The secondary battery according to claim 2, wherein the first exposed portion of the metal layer is located in the terrace portion.

4. The aforementioned terrace section is The first region between the first exposed portion and the cup portion; and The secondary battery according to claim 3, comprising a second region located outside the first exposed portion.

5. The secondary battery according to claim 4, wherein the first exposed portion is located on one side of the cup portion along the overall length of the secondary battery.

6. The secondary battery according to claim 4, wherein the terrace portion of the pouch has regions arranged on both sides of the cup portion along the overall length direction of the secondary battery, and the area on the side where the first exposed portion is located is formed to be even wider than the area on the opposite side.

7. The secondary battery according to claim 3, wherein the second exposed portion is arranged on one surface of the cup portion.

8. The secondary battery according to claim 1, wherein a plurality of the second exposed portions are formed thereon.

9. The secondary battery according to claim 8, wherein the second exposed portion is formed on both sides of the cup portion, at least one of each.

10. The secondary battery according to claim 1, wherein a conductor is bonded to the second exposed portion, and the conductor has a thickness such that it can protrude outward from the surface of the outer resin layer.

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

12. The aforementioned secondary battery has a pouch with two parallel planes, and adjacent secondary batteries are stacked so that the planes of the pouches are in contact with each other. The second exposed portion is formed at least once on each plane, The secondary battery module according to claim 11, wherein insulating tape is attached to the second exposed portion of the outermost secondary battery that is exposed to the outside.

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