KR20230048940A - Pouch type secondary battery and battery module including the same - Google Patents

Abstract

According to an embodiment of the present disclosure, provided is a pouch-type secondary battery including: an electrode assembly including a positive electrode, a negative electrode, and a separator; a plurality of electrode leads extending from the electrode assembly; and a pouch for accommodating the electrode assembly, wherein the pouch includes: a body unit that has a cylindrical shape, is open at both ends, and has a space therein to accommodate the electrode assembly; a sealing unit that seals both ends of the body unit and the electrode lead; and an extension unit in which a part of the sealing unit extends in one direction and is sealed.

Description

Pouch type secondary battery and battery module including the same {POUCH TYPE SECONDARY BATTERY AND BATTERY MODULE INCLUDING THE SAME}

The present disclosure relates to a pouch-type secondary battery and a battery module including the same, and more particularly, to a pouch-type secondary battery including a sealing part and an extension part on both sides of the pouch and a battery module including the same.

As the electronics, communication and space industries develop, the demand for secondary batteries as an energy power source is rapidly increasing. In particular, as the importance of global eco-friendly policies is emphasized, the electric vehicle market is growing rapidly, and research and development on secondary batteries is being actively conducted at home and abroad.

A secondary battery includes an electrode assembly including a cathode, an anode, and a separator disposed therebetween, and a battery case, which is an exterior material for sealing and accommodating the electrode assembly together with an electrolyte solution. Such a secondary battery may be classified into a pouch type, a prismatic type, or a cylinder type according to the shape and structure of the battery case. In particular, pouch-type secondary batteries are widely used due to their relatively free shape, simple structure, and high electric capacity per unit volume.

A large electric device consuming a large amount of power requires a plurality of secondary batteries, and after manufacturing a battery module to easily move and install the plurality of secondary batteries, a battery pack may be assembled using the battery module. When a plurality of secondary batteries are installed in the battery module, the secondary batteries are fixed to stably supply electricity to the outside.

Meanwhile, in order to generate electricity in the electrode assembly of the secondary battery, a chemical reaction between the electrode and the electrolyte proceeds, and heat and gas are generated in this process. Since the high temperature and high pressure conditions inside the battery may affect the stability and lifespan of the secondary battery and electric devices in which it is installed, various methods for controlling it have been proposed.

Embodiments of the present disclosure provide a pouch-type secondary battery with improved stability and lifespan and a battery module including the same.

A pouch-type secondary battery according to an embodiment of the present disclosure includes an electrode assembly including a positive electrode, a negative electrode, and a separator; a plurality of electrode leads extending from the electrode assembly; and a pouch accommodating the electrode assembly, wherein the pouch has a cylindrical shape, both ends of which are open, and a space formed therein to accommodate the electrode assembly; a sealing portion sealing both ends of the body portion and the electrode lead; and an extension portion in which a portion of the sealing portion extends in one direction and is sealed.

In an embodiment, the extension part may be located on one side of a portion where the electrode lead is sealed.

In an embodiment, the extension part may be sealed with a sealing strength different from that of the sealing part.

In an embodiment, the extension part may be sealed with a lower sealing strength than the sealing part.

In an embodiment, the extension portion may be formed in a cylindrical shape wound from an end of the extension portion.

In an embodiment, the extension part may be formed in a form that is folded from an end of the extension part.

In an embodiment, the sealing part may include a curved surface on at least a portion of an inner surface of the sealing part.

In an embodiment, the electrode assembly may be formed by stacking electrodes and separators on each other.

A battery module according to an embodiment of the present disclosure may include the pouch-type secondary battery.

A battery pack according to an embodiment of the present disclosure may include the battery module.

According to one embodiment of the present disclosure, a pouch-type secondary battery having improved stability and lifespan and a battery module including the same may be provided.

1 is a plan view illustrating a pouch-type secondary battery in which an electrode assembly, an electrode lead, and a pouch are combined according to an embodiment.
2 is a perspective view illustrating an electrode assembly and an electrode lead according to an embodiment.
3 is a plan view illustrating a pouch according to an embodiment.
4 is a plan view illustrating a pouch-type secondary battery in which a sealing portion and an extension portion of the pouch are sealed according to an embodiment.
5 is a plan view illustrating a pouch-type secondary battery in which a sealing portion and an extension portion of a pouch are sealed with different sealing strengths according to an embodiment.
6 is a plan view illustrating a pouch-type secondary battery in which an extension of a pouch is rolled in a cylindrical shape according to an embodiment.
7 is a plan view illustrating a pouch-type secondary battery in which an extension of a pouch has a folded shape according to an embodiment.
8 is a perspective view illustrating a battery module including a plurality of pouch-type secondary batteries and a cooling unit according to an embodiment.

Structural or functional descriptions of the embodiments disclosed in this specification or application are only illustrated for the purpose of explaining embodiments according to the technical spirit of the present disclosure, and embodiments according to the technical spirit of the present disclosure In addition to the embodiments disclosed in the application, it may be implemented in various forms, and the technical spirit of the present disclosure is not construed as being limited to the embodiments described in this specification or application.

The present disclosure relates to a pouch-type secondary battery including a sealing part and an extension part on both sides of the pouch, and a battery module including the same.

Hereinafter, a pouch-type secondary battery according to an embodiment and a battery module including the same will be described with reference to the accompanying drawings.

1 is a cross-sectional view showing a pouch-type secondary battery 100 in which an electrode assembly 101, an electrode lead 102, and a pouch 103 are combined according to an embodiment, and FIG. 2 is an electrode assembly 101 according to an embodiment And a perspective view showing the electrode lead 102, Figure 3 is a perspective view showing the pouch 103 according to the embodiment. When the electrode assembly 101 and electrode lead 102 of FIG. 2 and the pouch 103 of FIG. 3 are combined, the pouch type secondary battery 100 of FIG. 1 can be formed.

Referring to FIG. 1 , a pouch type secondary battery 100 may include a pouch 103, an electrode assembly 101 accommodated inside the pouch 103, and an electrode lead 102 extending from the electrode assembly 101. can

Referring to FIG. 2 , the electrode assembly 101 has a stacked (stacked) structure, and may be formed by alternately stacking positive and negative electrodes with a separator interposed therebetween. However, it is not limited thereto, and the electrode assembly 101 may be formed in various methods and shapes, such as a jelly roll (wound type) structure.

The electrode assembly 101 may include a plurality of electrode tabs (not shown), and the electrode tabs may be connected to an anode and a cathode, respectively, to serve as a path through which electrons may move. The plurality of electrode tabs may protrude in different directions from four side surfaces of the electrode assembly 101, but are not limited thereto, and may protrude side by side in the same direction from one side surface of the electrode assembly 101.

At least one electrode tab may be coupled to at least one electrode lead 102 . The electrode tab may include a positive electrode tab and a negative electrode tab, and the electrode lead 102 may include a positive electrode lead and a negative electrode lead. The positive tab may be bonded to the positive lead, and the negative tab may be bonded to the negative lead. The positive lead and the negative lead may be made of different materials. For example, the anode lead may be made of the same material as the anode, such as aluminum (Al), and the cathode lead may be made of the same material as the cathode, such as copper (Cu) or nickel (Ni) coated copper.

The electrode lead 102 may be connected to the electrode tab of the electrode assembly 101 using, for example, spot welding or the like. The electrode leads 102 may extend in opposite directions or in the same direction depending on where the electrode tabs are formed. The electrode lead 102 is electrically connected to the electrode assembly 101 and is exposed to the outside of the pouch 103 to serve as an electrode terminal that can be electrically connected to other batteries or external devices.

Although not shown in the drawings, the positive electrode may include a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector. A positive electrode uncoated portion may be formed in a portion of the positive electrode current collector on which the positive electrode active material layer is not formed. The positive electrode tab may be formed by cutting the positive electrode uncoated portion or by bonding a separate conductive member to the positive electrode uncoated portion. In the case of forming the anode tab by bonding a separate conductive member to the anode uncoated portion, a welding method, such as ultrasonic welding, may be used. The positive electrode uncoated portion may be electrically connected to the positive electrode tab so that electrons collected in the positive current collector may flow to an external circuit.

The cathode current collector may be formed of a material having excellent electrical conductivity, and the cathode tab may be formed of the same material as the cathode current collector. For example, the positive electrode current collector and the positive electrode tab may be formed of a material such as aluminum (Al). The positive electrode active material layer may use a chalcogenide compound so that lithium ions can be inserted or desorbed, and for example, a composite of LiCoO2, LiMn2O4, LiNiO2, LiNi1-xCoxO2 (0<x<1), LiMnO2, etc. It can be formed using metal oxides.

The negative electrode may include a negative electrode current collector that collects electrons generated by a chemical reaction and a negative electrode active material layer formed on the negative electrode current collector. An anode uncoated portion may be formed in a portion of the anode current collector on which the anode active material layer is not formed. The negative electrode tab may be formed by cutting the negative electrode uncoated portion or by bonding a separate conductive member to the negative electrode uncoated portion. In the case of forming the negative electrode tab by bonding a separate conductive member to the negative electrode uncoated portion, a welding method, such as ultrasonic welding, may be used. The negative electrode uncoated portion may be electrically connected to the negative electrode tab so that electrons collected in the negative electrode current collector may flow to an external circuit.

The anode current collector may be formed of a material having excellent electrical conductivity, for example, copper (Cu) or nickel (Ni). The negative electrode tab may be formed of, for example, nickel (Ni). The anode active material layer includes a carbon (C)-based material capable of intercalating and deintercalating lithium ions, for example, silicon (Si), tin (Sn), tin oxide, and tin alloy composite. , transition metal oxide, lithium metal nitride, or lithium metal oxide.

The separator may be formed between the positive electrode and the negative electrode to prevent direct contact between the positive electrode and the negative electrode. That is, the separator can block the positive electrode and the negative electrode, thereby preventing a short circuit that may occur between the positive electrode and the negative electrode. The separator may have a porous structure capable of transferring charges (eg, lithium ions). For example, the separator may be formed of a thermoplastic resin such as polyethylene (PE) or polypropylene (PP). When the temperature inside the battery rises and approaches the melting point of the thermoplastic resin, the porous separator melts and the pores are blocked to become an insulating film (Separator sealing or shutdown phenomenon). By changing the separator to an insulating film, the movement of lithium ions between the positive electrode and the negative electrode is blocked, and no more current flows, so that the temperature rise inside the battery can be stopped.

The pouch 103 may accommodate the electrode assembly 101 and an electrolyte solution (not shown) in an internal space, and may be made of a flexible material. The pouch 103 may be formed of, for example, an outer layer, a metal layer, and an inner layer. The outer layer is a substrate and a protective layer, and can primarily protect the electrode assembly 101 from external impact. The outer layer may be formed of, for example, a polymer material such as nylon or polyethylene terephthalate (PET), but is not limited thereto. The metal layer may serve as a substrate maintaining mechanical strength and a barrier layer preventing penetration of moisture and oxygen, and may be formed of a material such as aluminum (Al), but is not limited thereto. The inner layer is also referred to as a heat sealing layer, and has heat sealing properties to serve as a sealing agent. The inner layer may be formed of a polyolefin (Polyolepin)-based resin material, and may act as an adhesive layer using a modified polypropylene, CPP (Casted Polypropylene). The inner layer may be formed of a material selected from the group consisting of polyolefin-based resins such as chlorinated polypropylene, polyethylene, ethylene propylene copolymers, polyethylene and acrylic acid copolymers, and polypropylene and acrylic acid copolymers, but is not limited thereto.

The pouch 103 may protect internal components such as the electrode assembly 101 and the electrolyte solution, and perform a function of supplementing electrochemical properties by the electrode assembly 101 and the electrolyte solution and dissipating heat.

Referring to FIG. 3 , the pouch 103 may include a body portion 103_1, a sealing portion 103_2, and an extension portion 103_3. The body portion 103_1 may have a cylindrical shape, open at both ends and formed with a space therein. Since the body portion 103_1 has a cylindrical shape and only both ends are open, sealing can be performed only on two sides of both ends.

The pouch of the prior art combines upper and lower pouches and performs sealing on at least three sides, resulting in errors in alignment such as misalignment of the upper and lower pouches, difficulties in the process due to multiple sealings, and sealing part Problems such as weakening of adhesive strength may occur. In addition, by forming a folding portion that folds at least one side surface among at least three or more sealing surfaces, the side surface on which the folding portion is formed and the side surface on which the folding portion is not formed may have different thicknesses. there is. For example, in a pouch-type secondary battery in which both sides facing each other have different thicknesses, in a battery module including a cooling system for both sides facing each other, the cooling effect of both sides facing each other is may be different. The side on which the folding portion is formed has a lower cooling effect than the side on which the folding portion is not formed, and thus temperature control of the battery module may not be efficient. However, since the pouch-type secondary battery according to an embodiment of the present disclosure has a cylindrical shape and only seals both ends, an alignment error can be reduced, a sealing process can be simplified, and sealing force can be increased. In addition, both sides of the pouch facing each other are formed identical to each other (for example, both sides facing each other may be sealed parts, or both sides facing each other may be unsealed parts) , the cooling effect is the same, so temperature control can be efficient. Accordingly, the rapid charging time of the secondary battery may be shortened and the lifespan of the secondary battery may be increased.

The electrode assembly 101 may be accommodated in the space formed inside the body portion 103_1. A part of the electrode assembly 101 and the electrode lead 102 is disposed in the space formed inside the body part 103_1 through both open ends of the body part 103_1, and the other part of the electrode lead 102 is placed on the body. It may be arranged to be exposed to the outside through both open ends of the unit 103_1.

Sealing parts 103_2 may be formed at both ends of the body part 103_1 to seal the electrode assembly 101 accommodated inside the body part 103_1 from escaping from the pouch 103. There is a heat bonding layer on the inner surface of the sealing part 103_2, and it is bonded by heat and pressure, thereby sealing the body part 103_1. The sealing portion 103_2 is formed evenly and evenly throughout the sealing portion 103_2 to prevent leakage of electrolyte inside the battery and to prevent exposure to the external environment.

At least a portion of the inner surface of the sealing unit 103_2 may include a curved surface (not shown). When sealing the sealing part 103_2, the sealing can be performed more easily by the curved surface and the adhesive strength can be improved. The pouch 103 in a sealed state by the sealing portion 103_2 may be formed in various shapes depending on the shape of the electrode assembly 101 or the pouch 103 . For example, the pouch 103 may have a polygonal shape.

A portion of the sealing portion 103_2 may extend in one direction (eg, the x direction) to form an extension portion 103_3 to be sealed. The extension part 103_3 is formed on one side of the portion where the electrode lead 102 is disposed, and may act as a venting part. For example, the extension part 103_3 may be formed close to the part where the electrode lead 102 is disposed, and extends in a direction perpendicular to the side where the electrode lead 102 is disposed (eg, in the x direction). can be formed The pressure inside the battery where the electrode lead 102 is formed is relatively weak, and a certain portion of space is formed between the electrode assembly 101 and the electrode lead 102, so that the gas generated inside can accumulate the most. . Accordingly, the extension 103_3 formed close to the electrode lead 102 can vent more effectively.

The extension part 103_3 may be formed on at least one side of the sealing part 103_2. For example, the extension part 103_3 may be formed on one side of the sealing part 103_2 or may be formed on both sides of the sealing part 103_2. The extension part 103_3 may be included and formed when the shape of the pouch 103 is cut, or may be manufactured separately and combined with the sealing part 103_2 of the pouch 103. The length and width of the extension part 103_3 are not particularly limited, and may be formed in various sizes according to the shape of the pouch 103. In addition, the extension part 103_3 may be formed with a value that can sufficiently and efficiently act as a venting part.

4 is a cross-sectional view showing a pouch-type secondary battery 100 in which the sealing portion 103_2a and the extension portion 103_3a of the pouch 103 according to the embodiment are sealed, and FIG. 5 is a view of the pouch 103 according to the embodiment. A cross-sectional view showing the pouch-type secondary battery 100 in which the sealing portion 103_2a and the extension portion 103_3a are sealed with different strengths.

Referring to FIG. 4 , the pouch 103 may accommodate the electrode assembly 101 and the electrode lead 102 and seal the sealing portion 103_2a and the extension portion 103_3a so that a portion of the electrode lead 102 is exposed. there is.

Referring to FIG. 5 , the sealing portion 103_2a and the extension portion 103_3a may be sealed with different strengths. For example, the extension part 103_3a may be sealed with a lower sealing strength than the sealing part 103_2a. By sealing the extension part 103_3a weaker than the sealing part 103_2a, the vent direction can be predicted more easily. For example, it can be predicted that the gas generated inside the battery will not be vented through the more strongly sealed sealing portion 103_2a, but will be vented through the weakly sealed extension portion 103_3a. By directing the gas generated inside the battery to the extension part 103_3a, the vent direction can be freely controlled.

6 is a cross-sectional view illustrating a pouch-type secondary battery 100 in which an extension 103_3b of the pouch 103 according to the embodiment is rolled in a cylindrical shape, and FIG. 7 is an extension of the pouch 103 according to the embodiment. A cross-sectional view showing the pouch-type secondary battery 100 in which the portion 103_3c is folded.

Referring to FIGS. 6 and 7 , the sealed extension 103_3a may be formed in a cylindrical shape wound from an end of the extension 103_3a or folded in the direction of the body 103_1.

By winding or folding the extension part 103_3a in a cylindrical shape, the pouch-type secondary battery 100 can have a more compact structure, and space arrangement can be made more efficient when manufacturing a battery module or battery pack. . In addition, as gas is generated inside the battery, the cylindrically wound or folded extension 103_3 gradually unfolds, so that the vent lasts longer and the lifespan performance of the battery can be improved.

In the case where the extension 103_3b is wound in a cylindrical shape, the internal space of the battery module or battery pack can be used more effectively than in the case where the extension 103_3c is folded. For example, since the extension part 103_3b wound in a cylindrical shape is formed in a space where the electrode assembly 101 is not located, there is no concern about a problem caused by a phenomenon in which the battery becomes thick. In addition, even when the extension part 103_3a is gradually unfolded as gas is generated inside the battery, the shape of the extension part 103_3b wound in a cylindrical shape can be more smoothly unfolded than the shape of the extension part 103_3c that is folded, thereby preventing venting. This can be done more easily.

8 is a perspective view illustrating a battery module 200 including a plurality of pouch-type secondary batteries 100_1 and 100_2 and a cooling unit 201 according to an embodiment.

Referring to FIG. 8 , a battery module 200 may be assembled using a plurality of pouch-type secondary batteries 100_1 and 100_2, and although not shown in the drawing, a battery pack may be assembled using a plurality of battery modules 200. can The battery module 200 may include an upper cooling unit 201_1 and a lower cooling unit 201_2 on upper and lower sides facing each other, respectively. The upper cooling unit 201_1 and the lower cooling unit 201_2 may be formed to face each other with the plurality of pouch-type secondary batteries 100_1 and 100_2 interposed therebetween. The plurality of pouch-type secondary batteries 100_1 and 100_2 may be disposed side by side in one direction (eg, z direction) between the upper cooling unit 201_1 and the lower cooling unit 201_2 . Both sides of the pouch-type secondary battery 100 facing each other may be disposed to contact each other on one surface of the upper cooling unit 201_1 and the lower cooling unit 201_2 facing each other. For example, both sides of the pouch-type secondary battery 100 facing each other on which the electrode leads 102 are not disposed may be disposed to contact the upper cooling unit 201_1 and the lower cooling unit 201_2 , respectively. Both sides of the pouch-type secondary battery 100 that are in contact with the upper cooling unit 201_1 and the lower cooling unit 201_2, where the electrode leads 102 are not disposed, do not have a folded structure, and the sealing unit 103_2 And the extension part 103_3 may not be included. Therefore, since there are no obstacles in the heat transfer of the cooling unit 201, cold air from the cooling unit 201 is directly transferred to both sides of the pouch-type secondary battery 100, thereby increasing cooling efficiency. Also, both sides of the pouch-type secondary battery 100 may have the same structure. Therefore, in the heat transfer of the cooling unit 201, both sides of the pouch-type secondary battery 100 are equally applied to each other, so that cooling efficiency can be increased. In addition, the high-temperature gas is vented by the extension part 103_3 of the pouch 103, so that the cooling efficiency can be further increased. For example, since a temperature difference according to a position within the pouch-type secondary battery 100 is reduced, performance of rapid charging and battery life may be improved, and stability of the battery may be improved.

100: pouch type secondary battery
101: electrode assembly
102: electrode lead
103: pouch
103_1: body part
103_2: sealing part
103_3: extension
200: battery module
201: cooling unit

Claims (10)

An electrode assembly including an anode, a cathode, and a separator;
a plurality of electrode leads extending from the electrode assembly; and
Including a pouch accommodating the electrode assembly,
The pouch,
a body having a cylindrical shape, open at both ends and having a space formed therein to accommodate the electrode assembly;
a sealing portion sealing both ends of the body portion and the electrode lead; and
A pouch-type secondary battery comprising: an extension portion in which a portion of the sealing portion extends in one direction and is sealed. According to claim 1,
The extension part is located on one side of a portion where the electrode lead is sealed. According to claim 1,
The pouch-type secondary battery of claim 1 , wherein the extension portion is sealed with a sealing strength different from that of the sealing portion. According to claim 3,
The pouch-type secondary battery of claim 1 , wherein the extension portion is sealed with a lower sealing strength than the sealing portion. According to claim 1,
The extension part is in the form of a cylindrical shape wound from the end of the extension part, a pouch type secondary battery. According to claim 1,
The extension part is a pouch-type secondary battery in a form in which the extension part is folded in the direction from the end of the extension part toward the body part. According to claim 1,
The pouch-type secondary battery of claim 1 , wherein the sealing portion includes a curved surface on at least a portion of an inner surface of the sealing portion. According to claim 1,
The electrode assembly is a pouch-type secondary battery formed by stacking electrodes and separators on each other. A battery module comprising the pouch-type secondary battery according to claim 1 . A battery pack comprising the battery module according to claim 9.

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