Patent Application
20240421423
The present invention relates to a secondary battery and a battery module including the same, and more particularly, to a pouch-type secondary battery with improved safety, and a battery module including the same.
As development of technologies and demands for mobile devices are increased, there is a rapidly increasing demand for rechargeable batteries as energy sources. Therefore, many studies are being conducted on the rechargeable batteries in order to meet various needs.
The rechargeable battery is attracting lots of interest as an energy source for a power device such as an electric bicycle, an electric vehicle, and a hybrid electric vehicle as well as a mobile device such as a mobile phone, a digital camera, and a notebook computer.
A small-sized battery pack, in which one battery cell is packed, is used for a small-sized device such as a mobile phone or a camera. However, a middle-sized or large-sized battery pack, in which two or more battery cells are packed and connected in parallel and/or in series, is used for a middle-sized or large-sized device such as a notebook computer or an electric vehicle.
Regarding a shape of the secondary battery, there is a high demand for an angular or pouch-type secondary battery that may have a small thickness and be applied to products such as mobile phones. The angular lithium secondary battery is advantageous in protecting an electrode assembly from external impact, and it is easy to inject a liquid into the angular lithium secondary battery. However, because a shape of the angular lithium secondary battery is fixed, which makes it difficult to reduce a volume. However, because the pouch-type lithium secondary battery is not restricted in shape and size, the pouch-type lithium secondary battery is suitable for manufacturing a cell with a small thickness and is easily assembled by means of thermal bonding. Further, the pouch-type lithium secondary battery provides an effect of discharging gas or a liquid in the event of an abnormal motion, which provides high safety.
However, an electrolyte in the pouch-type secondary battery may be decomposed because of causes such as overcharging, exposure to high temperature, an internal short circuit, and the like. For this reason, a large amount of gas may be produced, or internal pressure may increase because of internal ignition.
The present invention has been made in an effort to provide a secondary battery capable of preventing explosion by safely discharging gas in an intended direction even though a large amount of gas is generated in a pouch-type secondary battery.
However, the object to be achieved by the embodiments of the present invention is not limited to the above-mentioned object but may be variously expanded without departing from the technical spirit of the present invention.
An exemplary embodiment of the present invention provides a secondary battery including: an electrode assembly; and a pouch-type casing in which the electrode assembly is embedded, the pouch-type casing including upper and lower casings thermally bonded to each other, in which the pouch-type casing includes a sealing part formed along at least a part of an edge of the pouch-type casing and formed as the upper and lower casings are thermally bonded, in which electrode leads connected to the electrode assembly protrude from sides of the pouch-type casing, in which the sealing part includes a notch portion formed at an end of any one of the sides from which the electrode leads protrude, and in which the notch portion has a curvature and is recessed toward the inside of the pouch-type casing.
The notch portion may not be formed at another end positioned opposite to the end at which the notch portion is formed with the electrode lead interposed therebetween.
A width of the notch portion may be equal to or smaller than a width of another portion of the sealing part, except for the notch portion.
The electrode leads may protrude from two opposite sides based on a longitudinal direction of the pouch-type casing.
Notch portions may be respectively provided at the two opposite sides from which the electrode leads protrude, and the notch portions may be respectively provided at ends in the same direction based on the electrode leads.
A radius of curvature of the notch portion may be 2 mm or less.
A portion where the upper casing and the lower casing are not thermally bonded may be disposed between the notch portion and an edge of the pouch-type casing.
The upper casing and the lower casing may be integrated with a folding line interposed therebetween, and the notch portion may be disposed adjacent to the folding line.
Another exemplary embodiment of the present invention provides a battery module including a plurality of secondary batteries described above.
All the notch portions of the plurality of secondary batteries may be arranged in the same direction.
According to the embodiments, it is possible to prevent explosion by safely guiding and discharging gas in the intended direction even though a large amount of gas is generated in the pouch-type secondary battery, thereby providing the secondary battery with improved safety.
Hereinafter, several exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those with ordinary skill in the art to which the present invention pertains may easily carry out the exemplary embodiments. The present invention may be implemented in various different ways and is not limited to the embodiments described herein.
A part irrelevant to the description will be omitted to clearly describe the present invention, and the same or similar constituent elements will be designated by the same reference numerals throughout the specification.
In addition, a size and thickness of each constituent element illustrated in the drawings are arbitrarily shown for convenience of description, but the present invention is not limited thereto. In order to clearly describe several layers and regions, thicknesses thereof are enlarged in the drawings. In the drawings, the thicknesses of some layers and regions are exaggerated for convenience of description.
In addition, when one component such as a layer, a film, a region, or a plate is described as being positioned “above” or “on” another component, one component can be positioned “directly on” another component, and one component can also be positioned on another component with other components interposed therebetween. On the contrary, when one component is described as being positioned “directly on” another component, there is no component therebetween. In addition, when a component is described as being positioned “above” or “on” a reference part, the component may be positioned “above” or “below” the reference part, and this configuration does not necessarily mean that the component is positioned “above” or “on” the reference part in a direction opposite to gravity.
Throughout the specification, unless explicitly described to the contrary, the word “comprise/include” and variations such as “comprises/includes” or “comprising/including” will be understood to imply the inclusion of stated elements, not the exclusion of any other elements.
Throughout the specification, the word “in a plan view” means when an object is viewed from above, and the word “in a cross-sectional view” means when a cross section made by vertically cutting an object is viewed from a lateral side.
Hereinafter, a secondary battery according to an embodiment of the present invention will be described with reference to
Referring to
The electrode assembly 200 may be provided in the form in which a positive plate and a negative plate are disposed with a separator interposed therebetween. In this case, the electrode assembly 200 may have a structure in which one positive plate and one negative plate are wound with a separator interposed therebetween or a structure in which a plurality of positive plates and a plurality of negative plates are stacked with separators interposed therebetween. The positive plate and the negative plate may each have a structure in which an electrode current collector is coated with active material slurry. The slurry may be typically formed by stirring an active material, a conductive material, a binder, and a plasticizer in a state in which a solvent is added.
The electrode plate of the electrode assembly 200 may have a non-coated portion on which no slurry is applied. An electrode tab, which corresponds to the electrode plate, may be formed on the non-coated portion. That is, the plurality of positive electrodes and the plurality of negative electrodes included in the electrode assembly 200 respectively include positive electrode tabs and negative electrode tabs, and electrode leads 210 and 220 are connected to the electrode assembly 200. Specifically, the electrode leads 210 and 220 include a positive electrode lead 210 and a negative electrode lead 220. The electrode leads 210 and 220 connected to the electrode assembly 200 protrude from two opposite ends of the pouch-type casing 300 and are exposed to the outside of the pouch-type casing 300. Meanwhile, in the present embodiment, the positive electrode lead 210 and the negative electrode lead 220 protrude in opposite directions. However, the protruding direction is not particularly limited. That is, the positive electrode lead 210 and the negative electrode lead 220 may be exposed together in the same direction from one side of the secondary battery 100.
The pouch-type casing 300 includes the upper casing 310 and the lower casing 320 that are thermally bonded to each other. Although not specifically illustrated, the pouch-type casing 300 including the upper casing 310 and the lower casing 320 may be a laminated sheet including a resin layer and a metal layer. Specifically, the upper casing 310 and the lower casing 320 may each include an inner resin layer for sealing, a metal layer configured to prevent penetration of a material, and an outer resin layer disposed at an outermost side.
The outer resin layer may have tensile strength excellent with respect to a thickness and have weather resistance and electrical insulation to protect the secondary battery 100 from the outside. The outer resin layer may include polyethylene terephthalate (PET) resin or nylon resin. The metal layer May prevent air, moisture, or the like from being introduced into the secondary battery 100. The metal layer may include aluminum (Al). The inner resin layers may be thermally bonded by heat and pressure applied thereto in a state in which the electrode assembly 200 is embedded. The inner resin layer may include thermoplastic resin such as casted polypropylene (CPP) or polypropylene (PP).
The upper casing 310 and the lower casing 320 may each have an accommodation part 300ST having a concave shape on which the electrode assembly 200 may be seated. The upper casing 310 and the lower casing 320 may respectively include rim portions 300S1 and 300S2 provided along outer edges of the accommodation parts 300ST. The rim portions 300S1 and 300S2 may each include a region in which a sealing part 340 is formed. The regions corresponding to the sealing part 340 are thermally bonded in a state in which the rim portion 300S1 of the upper casing 310 and the rim portion 300S2 of the lower casing 320 are in contact with each other, such that the sealing part 340 may be formed, and the pouch-type casing 300 may be sealed.
The sealing part 340 may include a notch portion 330 formed at an end of any one of the sides of the pouch-type casing 300 from which the electrode leads 210 and 220 protrude outward. The notch portion 330 has a shape recessed toward the inside of the pouch-type casing 300. That is, as illustrated in
In this case, the notch portion 330 is formed only at the end of any one of the sides from which the electrode leads 210 and 220 protrude but not formed at the opposite end of the other of the sides from which the electrode leads 210 and 220 protrude. For example, in
As illustrated in
As described above, the notch portion 330, which has a curvature and is recessed toward the inside of the pouch-type casing 300, is provided only at the end of any one of the sides from which the electrode leads 210 and 220 protrude, such that the venting is induced to be performed through the notch portion 330 in case that gas is generated in the pouch-type casing 300 or pressure is raised by internal ignition. Therefore, it is possible to prevent rapid propagation of flame and delay heat propagation.
Next, first to third modified examples of the embodiment of the present invention will be described with reference to
Referring to
Referring to
Referring to
Next, results of testing the effect of guiding venting in accordance with the shapes of the notch portions will be described with reference to
In
As illustrated in
In the examples and the comparative examples, it was determined that the test passed in case that the venting occurred first at the notch portion 330 or the position corresponding to the notch portion 330 when the temperature in the secondary battery was raised and the internal pressure was raised. Further, it was determined that the test failed in case that the venting occurred first at another position such as the position corresponding to the electrode lead instead of the notch portion 330 or the position corresponding to the notch portion 330. Table 1 shows the dimensions of the respective parts, the pressure during the venting, and test results in the examples and the comparative examples.
As shown in Table 1, in Examples 1 to 4, it was ascertained that in case that the notch portion 330 having a curvature was formed, the venting occurred through the notch portion 330 first before the venting occurred at the other parts regardless of the widths of the sealing part and the notch portion. In contrast, in the case of Comparative Examples 1 and 2, it was ascertained that the effect of guiding the venting was not obtained because the venting occurred first at the other parts first before the venting occurred at the corresponding parts even though the corresponding part was deformed so that the width (b) of the corresponding part was smaller than the width (c) of the sealing part 34 in order to guide the venting to the edge portion (inclined portion).
Meanwhile, the plurality of pouch-type secondary batteries according to the embodiment of the present invention may be collected and constitute the battery module. In this case, in the battery module, the notch portions included in the secondary battery are aligned and disposed in the same direction (e.g., at the lower side of the battery module), such that the venting direction may be controlled to a predetermined direction in the event of thermal runaway. Therefore, it is possible to prevent rapid propagation of flame and delay heat propagation.
Further, one or more battery modules may be packaged in a pack casing and constitute a battery pack.
The above-mentioned battery module and the battery pack including the battery module may be applied to various devices. Examples of such devices may include transportation means such as an electric bicycle, an electric vehicle, and a hybrid vehicle, but the present invention is not limited thereto, and may be applied to various devices that may use the battery module and the battery pack including the battery module. These configurations may also belong to the scope of the present invention.
Although preferred examples of the present invention have been described in detail hereinabove, the right scope of the present invention is not limited thereto, and many variations and modifications of those skilled in the art using the basic concept of the present invention, which is defined in the following claims, will also belong to the right scope of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2021-0159972 | Nov 2021 | KR | national |
This application is a national phase entry under 35 U.S.C. § 371 of International Application No. PCT/KR2022/016497 filed on Oct. 26, 2022, which claims priority to and the benefit of Korean Patent Application No. 10-2021-0159972 filed in the Korean Intellectual Property Office on Nov. 19, 2021, the entire contents of which are incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/KR2022/016497 | 10/26/2022 | WO |
