Pouch-type battery cell, and battery module and device including the same

Abstract

A pouch-type battery cell includes an electrode assembly to which an electrode lead is joined, a pouch case configured to accommodate the electrode assembly, and a lead film interposed between the electrode lead and the pouch case, wherein the pouch-type battery cell includes a safety element interposed between the electrode lead and the lead film, the safety element being configured to absorb energy in the battery cell when the battery cell is overheated to a predetermined temperature or more, thereby discharging the battery cell.

Description

Technical Field

[0001] This application claims the benefit of priority to Korean Patent Application No. 2021-0121677, filed on September 13, 2021, the disclosure of which is incorporated herein by reference in its entirety.

[0002] This invention relates to a pouch cell battery cell having a safety element disposed between the electrode leads and the lead film, thereby preventing the risk of fire or explosion due to abnormalities in the battery cell. Background Technology

[0003] With the technological advancements and increasing demands of mobile devices such as smartphones, laptops, and digital cameras, research on rechargeable batteries has been actively pursued. Furthermore, rechargeable batteries, as an alternative energy source to fossil fuels that contribute to air pollution, have been applied to electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (P-HEVs), and energy storage systems (ESS).

[0004] Lithium-ion batteries, lithium polymer batteries, nickel-cadmium batteries, nickel-metal hydride batteries, and nickel-zinc batteries are currently widely used rechargeable batteries. The operating voltage of a single rechargeable battery cell (i.e., a single cell) is approximately 2.0V to 5.0V. Therefore, when an output voltage higher than this is required, multiple cells can be connected in series to form a cell module assembly. Furthermore, cell module assemblies can be connected in series or parallel to form a battery module, depending on the required output voltage or charge / discharge capacity. Typically, a battery pack is manufactured using at least one battery module and additional components.

[0005] Based on the shape of the casing, battery cells can generally be divided into prismatic battery cells, cylindrical battery cells, and pouch battery cells.

[0006] In these battery cells, pouch cells are typically manufactured using a pouch casing with a laminate structure that includes an inner layer, a metal layer, and an outer layer.

[0007] Figure 1 This is a schematic view of a conventional pouch cell, wherein the conventional pouch cell is manufactured by housing the electrode assembly 10 together with the electrolyte in a pouch housing 20 and sealing the edges of the pouch housing with heat fusion to form a seal 21.

[0008] In addition, a portion of the electrode lead 11 connected to the electrode assembly 10 protrudes outward from the soft housing 20 to be electrically connected to the busbar, and the lead film 30 is typically inserted between the electrode lead 11 and the soft housing 20 to improve the electrical insulation and adhesion between the two.

[0009] The advantage of pouch cell is that its shape and size can be changed as needed, thus increasing its capacity ratio. However, the disadvantage is that pouch cells have relatively low resistance to fire or explosion.

[0010] Therefore, various methods are used to improve the safety of pouch cell batteries.

[0011] Among these methods, the main approach is to use elements such as fuses to block the current flow in a battery cell when an abnormality occurs (e.g., overheating due to overcurrent).

[0012] In this method, an element configured to block overcurrent is placed at each battery cell, which increases manufacturing costs and reduces the capacity ratio of the battery cells. Furthermore, even if overcurrent is sensed and blocked, conventional battery cells have a high energy state due to the overcurrent, posing an additional risk of fire or explosion. Summary of the Invention

[0013] Technical issues

[0014] The present invention was made in view of the above problems, and the object of the present invention is to provide a pouch cell having a safety element disposed between the electrode leads and the lead film, thereby preventing the risk of fire or explosion due to abnormality of the cell.

[0015] Technical solution

[0016] A pouch cell according to the invention for achieving the above-mentioned objectives includes: an electrode assembly, electrode leads bonded to the electrode assembly; a pouch housing configured to house the electrode assembly; and a lead film inserted between the electrode leads and the pouch housing, wherein the pouch cell includes a safety element inserted between the electrode leads and the lead film, the safety element being configured to absorb energy from the cell when the cell overheats above a predetermined temperature, thereby discharging the cell.

[0017] Furthermore, in the pouch cell according to the present invention, a sealing portion for sealing is formed on the outside of the pouch casing, and a lead film is inserted between the electrode lead and the sealing portion of the pouch casing.

[0018] Furthermore, in the pouch cell according to the present invention, lead films may be disposed on each of the opposing surfaces of the electrode leads.

[0019] Furthermore, in the pouch cell according to the present invention, the safety element can be a sheet element made of semiconductor material that has low conductivity at room temperature and whose conductivity gradually increases with increasing temperature.

[0020] Furthermore, in the pouch cell according to the present invention, the thickness of the safety element may be less than the thickness of the lead film, or the thickness of the safety element may be equal to the thickness of the lead film.

[0021] Furthermore, in the pouch cell according to the present invention, the safety element may be disposed on one or both of the opposing surfaces of the electrode leads.

[0022] Furthermore, in the pouch cell according to the present invention, a portion of the safety element may be exposed outside the lead film.

[0023] Furthermore, in the pouch cell according to the present invention, the safety element may be located in the lead film.

[0024] Furthermore, in the pouch cell according to the present invention, the lead film may include: a first lead film configured to cover the safety element, a portion of the first lead film being exposed outside the sealing portion; and a second lead film connected to the first lead film, the second lead film being located in the sealing portion.

[0025] Furthermore, in the pouch cell according to the present invention, the first lead film may contain a material with a melting point lower than that of the second lead film.

[0026] Furthermore, in the pouch cell according to the present invention, the first lead film may be a film made of polyethylene (PE), and the second lead film may be a film made of polypropylene (PP).

[0027] Furthermore, the battery module according to the present invention includes a pouch-type battery cell according to the present invention.

[0028] Additionally, the device according to the invention includes a battery module according to the invention.

[0029] Beneficial effects

[0030] The advantage of the pouch cell according to the present invention is that a safety element is provided between the electrode lead and the lead film, so that the current in the cell is released when the cell malfunctions, thereby preventing the cell from catching fire or exploding.

[0031] Furthermore, the advantage of the pouch cell according to the present invention is that, due to the inclusion of safety elements, the safety of the cell can be improved without requiring complex process or design modifications. Attached Figure Description

[0032] Figure 1 This is a schematic view of a conventional pouch cell.

[0033] Figure 2This is a schematic view of a pouch cell including a safety element according to an embodiment of the present invention.

[0034] Figure 3 This is an enlarged view showing the portion of a pouch cell containing a safety element, according to an embodiment of the present invention.

[0035] Figure 4 This is an enlarged view showing the portion of a pouch cell containing a safety element, according to another embodiment of the present invention.

[0036] Figure 5 This is an enlarged view showing the portion of a pouch cell containing a safety element having a first lead film and a second lead film, according to yet another embodiment of the present invention. Detailed Implementation

[0037] In this application, the terms “comprising,” “having,” “including,” etc., should be understood to refer to the presence of features, numbers, steps, operations, elements, components, or combinations thereof, but do not exclude the presence of one or more other features, numbers, steps, operations, elements, components, or combinations thereof, or the addition of one or more other features, numbers, steps, operations, elements, components, or combinations thereof.

[0038] Furthermore, the same reference numerals will be used throughout the accompanying drawings to refer to components that perform similar functions or operations. In this specification, when a component is described as being connected to another component, this can mean not only that the component is directly connected to the other component, but also that the component is indirectly connected to the other component via another component. Moreover, unless otherwise stated, including an element does not exclude other elements, but rather indicates that these elements may be further included.

[0039] In the following description, the pouch cell according to the present invention will be described with reference to the accompanying drawings.

[0040] Figure 2 This is a schematic view of a pouch cell including a safety element according to an embodiment of the present invention.

[0041] When reference Figure 2 When describing the pouch cell 100 according to the present invention, the pouch cell 100 includes an electrode assembly 110, a pouch housing 120, a lead film 130, and a safety element 140.

[0042] First, the electrode assembly 110 can be: a jelly-roll type assembly, configured to have an elongated positive electrode and an elongated negative electrode wound together with a separator inserted between them; a stacked electrode assembly, configured to have a rectangular positive electrode and a rectangular negative electrode stacked together with a separator inserted between them; a stacked folded electrode assembly, configured to have a single cell wound with a long separator; or a layered stacked assembly, configured to have battery cells stacked and attached to each other with a separator inserted between them. However, the present invention is not limited thereto.

[0043] A positive terminal and a negative terminal are formed at the electrode assembly 110, and the positive lead 111 and the negative lead 111 are typically connected to the positive terminal and the negative terminal, respectively.

[0044] like Figure 2 As shown, the positive lead 111 and the negative lead 111 can be formed to protrude in opposite directions. However, the invention is not limited to this, and various configuration options are possible. For example, the positive lead 111 and the negative lead 111 can protrude in the same direction.

[0045] The electrode assembly 110 and the electrolyte are housed in the soft housing 120. The edge of the soft housing housing containing the electrode assembly 110 is sealed airtightly by thermal fusion, thereby providing a sealing part 121 at the soft housing.

[0046] The flexible housing 120 is typically configured as a laminate structure comprising an inner layer, a metal layer, and an outer layer. The inner layer is positioned to be in direct contact with the electrode assembly 110, therefore the inner layer must exhibit high insulation properties and high resistance to electrolyte. Furthermore, the inner layer must exhibit high sealing performance to hermetically seal the flexible housing from the outside; that is, the thermally bonded seal between the inner layers must exhibit excellent thermal bonding strength.

[0047] The inner layer may be made of a material selected from polyolefin-based resins (e.g., polypropylene, polyethylene, polyethylene acrylate, or polybutene), polyurethane resins, and polyimide resins that exhibit excellent chemical resistance and high sealing performance.

[0048] The metal layer adjacent to the inner layer corresponds to a barrier layer configured to prevent moisture or various gases from permeating into the battery from the outside. Lightweight and easily moldable aluminum films are preferred materials for the metal layer.

[0049] An outer layer is disposed on the other surface of the metal layer. The outer layer may be made of a heat-resistant polymer exhibiting excellent tensile strength, moisture resistance, and air permeability, thus providing high heat and chemical resistance while protecting the electrode assembly 110. As an example, the outer layer may be made of nylon or polyethylene terephthalate. However, the invention is not limited thereto.

[0050] Meanwhile, the lead film 130 is located between the electrode lead 111 and the sealing part 121 of the soft housing 120 to prevent short circuit between the electrode lead 111 and the metal layer of the soft housing 120, and to increase the sealing force, thereby preventing electrolyte leakage.

[0051] The lead film 130 may contain at least one material selected from polyimide (PI), polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), and epoxy resin, each of which has high insulation properties and heat-melting properties.

[0052] Furthermore, the lead film 130 can typically be configured such that a pair of films are located on opposite surfaces of the electrode leads 111, and the portions of the films not adjacent to the electrode leads 111 are joined together by thermal fusion to encapsulate the electrode leads 111. For preventing short circuits, preferably, after sealing the soft housing 120, the lead film is formed to protrude outward from the soft housing 120.

[0053] Meanwhile, the pouch cell 100 according to the present invention also includes a safety element 140 disposed between the electrode lead 111 and the lead film 130 to absorb the energy (i.e., current) in the pouch cell 100, thereby discharging the pouch cell 100 when the pouch cell overheats to above a predetermined temperature due to overcurrent.

[0054] Preferably, the safety element 140 is a sheet made of semiconductor material that has low conductivity at room temperature and whose conductivity gradually increases with increasing temperature.

[0055] When the pouch cell 100 is operating normally, due to the low conductivity of the semiconductor material, almost no current flows in the safety element 140 made of semiconductor material compared to the electrode leads 111.

[0056] However, when the pouch cell 100 overheats due to overcurrent, the temperature of the safety element 140 rises, thereby causing a sharp increase in the amount of current flowing in the safety element 140.

[0057] Therefore, the current in the pouch cell 100 is forcibly released, thereby preventing the additional risk of fire or explosion.

[0058] Furthermore, when excessive current flows in the safety element 140, the temperature of the safety element 140 will rise due to the heat generated by the internal resistance, and this temperature rise may degrade the lead film 130 and the inner layer of the soft housing 120 used to insulate the electrode lead 111 from the soft housing 120.

[0059] Therefore, a short circuit may occur between the electrode lead 111 and the metal layer of the pouch casing 120, which may accelerate the discharge of the pouch cell 100.

[0060] Figure 3 This is an enlarged view showing the portion of a pouch cell containing a safety element, according to an embodiment of the present invention. Figure 4 This is an enlarged view showing the portion of a pouch cell containing a safety element, according to another embodiment of the present invention.

[0061] When reference Figure 3 and Figure 4 When describing the location of electrode lead 111 and safety element 140, a portion of safety element 140 may protrude outward from lead film 130 (e.g. Figure 3 (as shown), or the safety element 140 can be configured to be fully inserted into the lead film 130 (as shown). Figure 4 (As shown).

[0062] Since the degree of degradation of the lead film 130 varies depending on the contact area between the safety element 140 and the lead film 130 and the heat generated by the safety element 140, the degree of degradation of the lead film 130 can be adjusted to a certain extent by appropriately adjusting the contact area.

[0063] Of course, the degree of degradation of lead film 130 varies depending on its material.

[0064] The safety element 140 is located at a position that partially or completely overlaps with the sealing portion 121 and / or lead film 130 of the pouch cell 100; therefore, the safety element preferably has the smallest possible thickness.

[0065] Specifically, the thickness of the safety element 140 is preferably equal to or less than the thickness of the lead film 130 covering the safety element.

[0066] Furthermore, although safety element 140 is in Figure 2 and Figure 4 As shown in the diagram, located on one surface of the electrode lead 111, the pouch cell 100 according to the invention can be configured such that a plurality of safety elements are disposed on opposite surfaces of the electrode lead 111.

[0067] Meanwhile, although in the present invention Figures 2 to 4 The example describes the case where the lead film 130 is formed of a uniform material over the entire lead film 130, but the lead film 130 according to the invention can be formed of different materials depending on the region.

[0068] Figure 5This is an enlarged view showing the portion of a pouch cell containing a safety element having a first lead film and a second lead film, according to yet another embodiment of the present invention.

[0069] When reference Figure 5 In describing another example of the lead film 130 according to the invention, the lead film 130 having two regions includes a first lead film 131 and a second lead film 132, a portion of the first lead film 131 being exposed outside the sealing portion 121, the first lead film being configured to cover the safety element 140, and the second lead film 132 being connected to the first lead film and located in the sealing portion 121.

[0070] Here, the first lead film 131 is made of a material with a melting point lower than that of the second lead film 132.

[0071] For example, the first lead film 131 may be made of polyethylene (PE), and the second lead film 132 may be made of polypropylene (PP).

[0072] As described above, when using a lead film 130 with two regions, the first lead film 131 may degrade at a lower temperature due to the heat generated by the safety element 140. Therefore, a short circuit between the electrode lead 111 and the metal layer of the pouch casing 120 can occur earlier, thereby further accelerating the discharge of the pouch cell 100.

[0073] When briefly describing the manufacturing method of the pouch cell 100 according to the present invention, the method includes the steps of forming an electrode assembly 110 and engaging the electrode leads 111 with the electrode terminals of the formed electrode assembly 110.

[0074] At this point, the electrode terminals and electrode leads 111 can be joined together using any of the various known welding methods (e.g., resistance welding, ultrasonic welding, and laser welding).

[0075] Subsequently, the lead film 130 is placed on the electrode lead 111, the safety element 140 is inserted between them, the electrode assembly 110 is housed in the soft-pack housing 120, so that a portion of the electrode lead 111 is exposed, electrolyte is injected, and the soft-pack housing is hermetically sealed to form a sealing portion 121, thereby forming a soft-pack battery cell 100.

[0076] In other words, apart from the safety element 140, the same process as conventional pouch cell manufacturing methods can be performed, thereby greatly reducing additional production costs and enabling the manufacture of pouch cell 100 with higher safety.

[0077] Furthermore, battery modules or battery packs comprising pouch-type battery cells 100 (including the safety element 140 according to the invention) can be manufactured, and the manufactured battery modules or battery packs can be used as power sources for various types of electronic equipment and various devices, such as electric vehicles (EVs), hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (P-HEVs).

[0078] While the specific details of the present invention have been described in detail, those skilled in the art will understand that the detailed description only discloses preferred embodiments of the invention and therefore does not limit the scope of the invention. Consequently, those skilled in the art will understand that various changes and modifications can be made without departing from the scope and technical concept of the invention, and such changes and modifications obviously fall within the scope of the appended claims.

[0079] (Explanation of reference numerals in the attached diagram)

[0080] 100: Soft-pack battery cell

[0081] 110: Electrode assembly

[0082] 111: Electrode lead

[0083] 120: Soft-pack housing

[0084] 121: Sealing part

[0085] 130: Lead film

[0086] 131: First lead film

[0087] 132: Second lead film

[0088] 140: Safety Component

Claims

1. A pouch-type battery cell, comprising: an electrode assembly to which an electrode lead is joined; a pouch case configured to accommodate the electrode assembly; and a lead film interposed between the electrode lead and the pouch case, wherein the pouch-type battery cell includes a safety element interposed between the electrode lead and the lead film, the safety element being configured to absorb energy in the battery cell when the battery cell is overheated to a predetermined temperature or more, thereby discharging the battery cell, wherein the safety element is a sheet-shaped element made of a semiconductor material having a low electrical conductivity at normal temperature and gradually increasing electrical conductivity as temperature increases. a sealing portion for sealing is formed on an outer side of the pouch case, and 2. The pouch-shaped battery cell according to claim 1, wherein, wherein the lead film is interposed between the electrode lead and the sealing portion of the pouch case. The lead film is provided on each of opposite surfaces of the electrode lead.

3. The pouch-shaped battery cell according to claim 1, wherein, The safety element has a thickness smaller than or equal to that of the lead film.

4. The pouch-shaped battery cell according to claim 1, wherein, The safety element is provided on one or both of the opposite surfaces of the electrode lead.

5. The pouch-shaped battery cell according to claim 1, wherein, A portion of the safety element is exposed outside the lead film.

6. The pouch-shaped battery cell according to claim 1, wherein, The safety element is located in the lead film.

7. The pouch-shaped battery cell according to claim 1, wherein, The lead film includes:

8. The pouch-shaped battery cell according to claim 2, wherein, a first lead film configured to cover the safety element, a portion of the first lead film being exposed outside the sealing portion; and a second lead film connected to the first lead film, the second lead film being located in the sealing portion. The first lead film contains a material having a lower melting point than the second lead film.

9. The pouch-shaped battery cell according to claim 8, wherein, 10.The pouch-type battery cell of claim 9, wherein: the first lead film is a film made of polyethylene (PE), and the second lead film is a film made of polypropylene (PP). 11.A battery module including the pouch-type battery cell according to any one of claims 1 to 10. 12.An apparatus including the battery module of claim 11. ​

Images