Pouch-Shaped Secondary Battery with Improved Safety and Battery Module Including the Same

Abstract

The present invention relates to a pouch-shaped secondary battery with improved safety including a gas pocket disposed on an electrode lead and a current sensing portion configured to move in response to expansion of the gas pocket. The pouch-shaped secondary battery may be capable of indicating the extent of gas in a receiving portion of the case in advance. A battery module may include the pouch-shaped secondary battery.

Claims

1. A pouch-shaped secondary battery comprising: an electrode assembly having an electrode lead protruding therefrom; a case comprising a receiving portion configured to receive the electrode assembly; and a danger sensing device comprising a gas pocket disposed on the electrode lead and a current sensing portion configured to move in response to an expansion or a contraction of the gas pocket.

2. The pouch-shaped secondary battery according to claim 1, wherein the current sensing portion comprises: an electrode lead contact portion in contact with the electrode lead; and a gas pocket contact portion abutting the gas pocket, the gas pocket contact portion being configured to move the current sensing portion using an expansion or contraction force of the gas pocket.

3. The pouch-shaped secondary battery according to claim 2, wherein a distance between the electrode lead contact portion and the electrode lead increases due to the expansion of the gas pocket.

4. The pouch-shaped secondary battery according to claim 2, wherein the gas pocket contact portion contacts the gas pocket along a direction in which the gas pocket expands or contracts.

5. The pouch-shaped secondary battery according to claim 4, wherein the gas pocket contact portion has a larger sectional width than the electrode lead contact portion.

6. The pouch-shaped secondary battery according to claim 2, wherein at least the electrode lead contact portion is a conductor.

7. The pouch-shaped secondary battery according to claim 6, wherein at least an outer surface of the gas pocket contact portion is made of an insulation material.

8. The pouch-shaped secondary battery according to claim 7, wherein the insulation material has an adhesive force.

9. The pouch-shaped secondary battery according to claim 1, wherein a side of the current sensing portion is connected to a voltage measurement device.

10. The pouch-shaped secondary battery according to claim 1, wherein a portion at which the gas pocket and the receiving portion are connected to each other is sealed with lower sealing force than a sealed portion of the case.

11. The pouch-shaped secondary battery according to claim 10, wherein when pressure in the receiving portion is equal to or higher than a predetermined threshold the gas pocket expands.

12. The pouch-shaped secondary battery according to claim 1, wherein a first surface of the gas pocket contacts the electrode lead, and wherein a second surface of the gas pocket contacts the current sensing portion.

13. The pouch-shaped secondary battery according to claim 1, wherein the gas pocket includes first and second gas pockets disposed at opposite sides of the current sensing portion.

14. The pouch-shaped secondary battery according to claim 1, wherein the gas pocket is provided above a terraced portion formed by a sealed portion where the electrode lead protrudes or is disposed at least on the electrode lead.

15. A battery module comprising the pouch-shaped secondary battery according to claim 1.

16. The battery module according to claim 15, wherein the pouch-shaped secondary battery is connected in parallel.

Description

DESCRIPTION OF DRAWINGS

[0037] FIG. 1 is a plan view of a pouch-shaped secondary battery having a gas pocket.

[0038] FIG. 2 is a plan view of a pouch-shaped secondary battery having a gas discharge induction portion.

[0039] FIG. 3 is a perspective view of a pouch-shaped secondary battery according to a first embodiment of the present invention.

[0040] FIG. 4 is a plan view of the pouch-shaped secondary battery of FIG. 3.

[0041] FIG. 5 is a side sectional view of the pouch-shaped secondary battery of FIG. 3.

[0042] FIG. 6 is a perspective view of a pouch-shaped secondary battery according to a second embodiment of the present invention.

[0043] FIG. 7 is a plan view of the pouch-shaped secondary battery of FIG. 6.

[0044] FIG. 8 is a plan view of a pouch-shaped secondary battery according to a third embodiment of the present invention.

[0045] FIG. 9 is a side sectional view of the pouch-shaped secondary battery of FIG. 8.

[0046] FIG. 10 is a schematic view showing a method to manufacture a pouch-shaped secondary battery according to the present invention.

BEST MODE

[0047] Now, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings such that the preferred embodiments of the present invention can be easily implemented by a person having ordinary skill in the art to which the present invention pertains. In describing the principle of operation of the preferred embodiments of the present invention in detail, however, a detailed description of known functions and configurations incorporated herein will be omitted when the same may obscure the subject matter of the present invention.

[0048] In addition, the same reference numbers will be used throughout the drawings to refer to parts that perform similar functions or operations. In the case in which one part is said to be connected to another part throughout the specification, not only may the one part be directly connected to the other part, but also, the one part may be indirectly connected to the other part via a further part. In addition, that a certain element is included does not mean that other elements are excluded, but means that such elements may be further included unless mentioned otherwise.

[0049] In addition, a description to embody elements through limitation or addition may be applied to all inventions, unless particularly restricted, and does not limit a specific invention.

[0050] Also, in the description of the invention and the claims of the present application, singular forms are intended to include plural forms unless mentioned otherwise.

[0051] Also, in the description of the invention and the claims of the present application, “or” includes “and” unless mentioned otherwise. Therefore, “including A or B” means three cases, namely, the case including A, the case including B, and the case including A and B.

[0052] In addition, all numeric ranges include the lowest value, the highest value, and all intermediate values therebetween unless the context clearly indicates otherwise.

[0053] FIG. 3 is a perspective view of a pouch-shaped secondary battery according to a first embodiment of the present invention, FIG. 4 is a plan view of the pouch-shaped secondary battery according to the first embodiment of the present invention, and FIG. 5 is a side sectional view of the pouch-shaped secondary battery according to the first embodiment of the present invention.

[0054] As shown in FIGS. 3 to 5, the pouch-shaped secondary battery according to the first embodiment of the present invention includes an electrode assembly 100 having electrode leads 110 protruding therefrom, a case 200 including a receiving portion 210 configured to receive the electrode assembly 100, and a danger sensing device 300 including a gas pocket 310 disposed on each of the electrode leads 110 and a current sensing portion 320 configured to move in response to expansion of the gas pocket 310.

[0055] The electrode assembly 100 may be a jelly-roll type assembly, which is configured to have a structure in which a long sheet type positive electrode and a long sheet type negative electrode are wound in the state in which a separator is interposed therebetween, a stacked type electrode assembly including unit cells, each of which is configured to have a structure in which a rectangular positive electrode and a rectangular negative electrode are stacked in the state in which a separator is interposed therebetween, a stacked and folded type assembly, which is configured to have a structure in which unit cells are wound using a long separation film, or a laminated and stacked type assembly, which is configured to have a structure in which unit cells are stacked in the state in which a separator is interposed therebetween and are then attached to each other. However, the present invention is not limited thereto.

[0056] The electrode leads 110 may be configured to have a structure in which the electrode leads are exposed out of the case after positive electrode tabs and negative electrode tabs of the electrode assembly 100 are electrically connected to the electrode leads or a structure in which the electrode leads 110 directly connect the electrode assembly 100 to the outside of the case 200 without positive electrode tabs and negative electrode tabs. However, the present invention is not limited thereto. The secondary battery described above is generally known, and therefore a more detailed description thereof will be omitted.

[0057] The case 200 is generally configured to have a laminate sheet structure including an inner layer, a metal layer, and an outer layer. The inner layer is disposed in direct contact with the electrode assembly, and therefore the inner layer must exhibit high insulation properties and high resistance to an electrolytic solution. In addition, the inner layer must exhibit high sealability in order to hermetically seal the case from the outside, i.e., a thermally-bonded sealed portion between inner layers must exhibit excellent thermal bonding strength. The inner layer may be made of a material selected from among a polyolefin-based resin, such as polypropylene, polyethylene, polyethylene acrylate, or polybutylene, a polyurethane resin, and a polyimide resin, which exhibit excellent chemical resistance and high sealability. However, the present invention is not limited thereto, and polypropylene, which exhibits excellent mechanical-physical properties, such as tensile strength, rigidity, surface hardness, and impact resistance strength, and excellent chemical resistance, is the most preferably used.

[0058] The metal layer, which is disposed so as to abut the inner layer, corresponds to a barrier layer configured to prevent moisture or various kinds of gas from permeating into the battery from the outside. An aluminum thin film, which is light and easily shapeable, may be used as a preferred material for the metal layer.

[0059] The outer layer is provided on the other surface of the metal layer. The outer layer may be made of a heat-resistant polymer that exhibits excellent tensile strength, resistance to moisture permeation, and resistance to air permeation such that the outer layer exhibits high heat resistance and chemical resistance while protecting the electrode assembly. As an example, the outer layer may be made of nylon or polyethylene terephthalate. However, the present invention is not limited thereto.

[0060] The receiving portion 210 may be formed in each of the upper part and the lower part of the case 200, or may be formed in any one of the upper part and the lower part of the case.

[0061] In addition, the outside surface of the receiving portion 210 is hermetically sealed in order to prevent a material in the receiving portion 210 from being discharged from the case 200. At this time, a sealed portion 220 formed as the result of hermetically sealing is bent in a direction toward the receiving portion 210 in order to increase energy density of a battery module. At this time, a terraced portion, which is a part of the sealed portion 220 and from which the electrode lead 110 protrudes in one direction or in opposite directions, is formed so as to protrude from the receiving portion 210.

[0062] The danger sensing device 300 may be located at the terraced portion of the sealed portion 220 or at the electrode lead 110 adjacent to the terraced portion. That is, the danger sensing device 300 may extend from the terraced portion and may be located on the electrode lead, may be located at a part of the terraced portion, or may be located on the electrode lead.

[0063] The gas pocket 310 of the danger sensing device 300 may be connected to the receiving portion 210 and the sealed portion 220. That is, the gas pocket 310 may be connected to the receiving portion 210 with lower sealing force than the sealed portion 220.

[0064] In the case in which pressure in the receiving portion 210 is equal to or higher than a predetermined range, the portion of the gas pocket that is connected to the receiving portion 210 with low sealing force may be damaged, whereby gas may move into the gas pocket 310, and therefore the gas pocket may be expanded. At this time, the gas pocket 310 may be expanded at once, or may be divided into several sections and thus may be expanded twice or more.

[0065] The gas pocket 310 may be disposed at the portion of the sealed portion 220 from which the electrode lead 110 protrudes, i.e., above the terraced portion or at least on the electrode lead 110.

[0066] The gas pocket 310 according to the first embodiment of the present invention may be a part of the sealed portion 220. As shown in FIGS. 3 and 5, the gas pocket 310 may be a part of the sealed portion 220 formed at the portion at which the electrode lead 110 protruding from the electrode assembly 100 extends through the case 200.

[0067] When the sealed portion 220 is divided into three equal parts, the gas pocket 310 according to the first embodiment may be located at the outer ⅓ point of the sealed portion 220, i.e., the farthest side of the receiving portion 210.

[0068] In addition, the gas pocket 310, which is connected to the case 200, may be made of the same material as the case 200. In order to secure sealing force, one surface of the gas pocket 310 may be laminated like the electrode tabs, and the other surface of the gas pocket may be in contact with the current sensing portion 320.

[0069] At least one gas pocket 310 may be provided in a single pouch-shaped secondary battery. As an example, the gas pocket 310 may assist in movement of the current sensing portion 320 at each of opposite sides of the current sensing portion 320 such that the current sensing portion 320 is easily operated.

[0070] In addition, the pouch-shaped secondary battery according to the present invention may include a gas receiving portion configured to receive a predetermined amount of gas in addition to the gas pocket 310. Consequently, it is possible to prevent breakage of the pouch-shaped secondary battery, and when pressure in the gas receiving portion exceeds a predetermined range, it is possible to indicate a danger through the gas pocket 310. On the contrary, after the gas pocket 310 is operated by a one-way valve of the gas receiving portion, the gas receiving portion may receive gas generated in the pouch-shaped secondary battery.

[0071] FIG. 6 is a perspective view of a pouch-shaped secondary battery according to a second embodiment of the present invention, and FIG. 7 is a plan view of the pouch-shaped secondary battery according to the second embodiment of the present invention.

[0072] As shown in FIGS. 6 and 7, in the pouch-shaped secondary battery according to the second embodiment of the present invention, the gas pocket 310 may be formed independent of the sealed portion 220. The gas pocket 310 is located adjacent to the sealed portion 220, which hermetically seals the electrode lead 110, i.e., at the distance at which the gas pocket 310 abuts the electrode lead 110 while securing force of sealing the electrode lead 110. The connection sealed portion 221 connected to the gas pocket 310 has lower sealing force than other portions. When gas is generated in the receiving portion 210, therefore, the connection sealed portion 221 is broken first, and then the gas moves into the gas pocket 310.

[0073] As shown in FIGS. 6 and 7, the gas pocket 310 may be partially curved so as to be located on the electrode lead 110.

[0074] FIG. 8 is a plan view of a pouch-shaped secondary battery according to a third embodiment of the present invention.

[0075] As shown in FIG. 8, the pouch-shaped secondary battery according to the third embodiment of the present invention may be configured to have a structure in which the gas pocket 310 is integrally formed with the sealed portion 220, similarly to the pouch-shaped secondary battery according to the first embodiment.

[0076] In order to prevent flow or movement of gas from being disturbed in the case in which the gas pocket 310 is bent as in the second embodiment, the gas pocket 310 according to the third embodiment of the present invention may be formed so as to simply cover the electrode lead 110.

[0077] The surplus portion of the gas pocket 310 that covers the leads may be formed in the shape of a pouch, which is a space that is capable of being filled with unsealed gas, and the portion of the gas pocket 310 that abuts the sealed portion 220 may be divided into two parts having different sealing forces. The portion of the gas pocket that abuts the sealed portion 220 may include a connection sealed portion 221 having lower sealing force than the sealed portion 220 and a peripheral sealed portion 222 having the same sealing force as the sealed portion 220.

[0078] The connection sealed portion 221 may be located at a region other than a contour portion of the electrode lead 110 that affects force of sealing between the electrode lead 110 and the case 200. At this time, in order to maintain the force of sealing between the electrode lead 110 and the case 200 while smoothly supplying gas to the gas pocket 310, the connection sealed portion 221 may be formed in a state of being divided into at least two parts based on the electrode lead 110.

[0079] A one-way valve configured to allow gas in the receiving portion 210 to move only in one direction may be provided at the outermost contour portion of the connection sealed portion 221, i.e., at the point farthest from the sealed portion.

[0080] In the case in which a gas passage is integrally formed with the connection sealed portion 221, the peripheral sealed portion 222, which is the sealed portion 220 that is not the gas passage, and the sealed portion around the gas passage in the gas pocket 310 may be more strongly sealed than other sealed portions. In the case in which the peripheral sealed portion 222 has higher sealing force than other sealed portions, it is possible to solve a problem in that sealing force around the electrode lead 110 is reduced.

[0081] FIG. 9 is a side sectional view of the pouch-shaped secondary battery according to the present invention.

[0082] As shown in FIG. 9, the current sensing portion 320 according to the present invention may include an electrode lead contact portion 321 disposed in contact with the electrode lead 110 and a gas pocket contact portion 322 disposed abutting the gas pocket 310, the gas pocket contact portion being configured to move the current sensing portion 320 using expansion force of the gas pocket 310.

[0083] The electrode lead contact portion 321 may become far away from the electrode lead due to expansion of the gas pocket. To this end, the gas pocket contact portion 322 comes into contact with the gas pocket 310 in the direction in which the gas pocket 310 is expanded. In addition, to this end, the gas pocket contact portion 322 may have a larger sectional width than the electrode lead contact portion 321. That is, the current sensing portion 320 may be configured to have a structure in which the electrode lead contact portion 321 is disposed between the gas pockets 310 and in which the gas pocket contact portion 322 is disposed in contact with the gas pocket 310 disposed beside the electrode lead contact portion 321. The current sensing portion 320 may have a T-shaped form, a conical form, or a section climbing form so as to be operated as described above.

[0084] The current sensing portion 320 may sense current that moves in the electrode lead 110 through the electrode lead contact portion 321. When the electrode lead contact portion 321 is separated from the electrode lead 110 due to expansion of the gas pocket 310, the electrode lead contact portion 321 cannot sense current any more, and therefore it is possible to determine whether gas has been generated in the receiving portion 21.

[0085] In addition, one side of the current sensing portion 320 may be connected to a voltage measurement device, which may convert the current sensed by the electrode lead contact portion 321 into a numerical value or a signal.

[0086] It is preferable for the current sensing portion 320 to be a conductor in order to measure current through contact with the electrode lead 110, as described above. That is, it is preferable for at least the electrode lead contact portion 321 of the current sensing portion 320 to be a conductor. Although the entirety of the current sensing portion 320 is a conductor, the outer surface of the current sensing portion 320, i.e., at least the outer surface of the gas pocket contact portion 322, may be wrapped with an insulation material such that no current flows in another portion of the pouch-shaped secondary battery, e.g. the gas pocket 310.

[0087] The insulation material may be a material that has adhesive force in order to fix the current sensing portion 320. As an example, the insulation material may be at least one selected from the group consisting of polyethylene, polypropylene, polyvinyl fluoride, polyvinyl alcohol, polyvinyl polyamide imide, an epoxy-based material, an acrylic-based material, a silicone-based material, a urethane-based material, a thermoplastic urethane-based material, and a thermoplastic ether ester-based material.

[0088] In addition, the current sensing portion 320 according to the present invention may be provided in one or more in order to measure the amount of gas depending on the extent to which the gas pocket 310 having several sealed portions is opened.

[0089] The present invention may provide a battery module including at least one pouch-shaped secondary battery. The battery module may be configured such that pouch-shaped secondary batteries are connected to each other in parallel. The reason for this is that, in the case in which the pouch-shaped secondary batteries are connected to each other in series, it is possible to easily recognize one unit cell, when the unit cell is abnormal, whereas, in the case unit cells are connected to each other in parallel, it is difficult to find abnormality of one of the unit cells.

[0090] In addition, the present invention may provide a battery pack including the pouch-shaped secondary battery.

[0091] FIG. 10 is a schematic view showing a pouch-shaped secondary battery manufacturing method according to the present invention.

[0092] In the pouch-shaped secondary battery according to the present invention, the portion of the case that will become the gas pocket 310 and the electrode lead 110 may be bonded to each other first, and then the remaining portions may be bonded. After bonding, the portion that will become the gas pocket 310 may be folded such that no empty space is formed, as shown in FIG. 10, and then the portion that contacts the remaining portion of the electrode lead 110 may be further welded.

[0093] In addition, the present invention provides a battery pack including the pouch-shaped secondary battery and a device including the battery pack. The battery pack and the device are well known in the art to which the present invention pertains, and thus a detailed description thereof will be omitted.

[0094] For example, the device may be a laptop computer, a netbook computer, a tablet PC, a mobile phone, an MP3 player, a wearable electronic device, a power tool, an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), an electric bicycle (E-bike), an electric scooter (E-scooter), an electric golf cart, or an energy storage system. However, the present invention is not limited thereto.

[0095] Those skilled in the art to which the present invention pertains will appreciate that various applications and modifications are possible within the category of the present invention based on the above description.

DESCRIPTION OF REFERENCE NUMERALS

[0096] 10, 100: Electrode assemblies [0097] 11, 110: Electrode leads [0098] 20, 200: Cases [0099] 21, 210: Receiving portions [0100] 22, 220: Sealed portions [0101] 221: Connection sealed portion [0102] 222: Peripheral sealed portion [0103] 23: Gas discharge induction portion [0104] 300: Danger sensing device [0105] 310: Gas pocket [0106] 320: Current sensing portion [0107] 321: Electrode tab contact portion [0108] 322: Gas pocket contact portion