Patent Application
20240097245
The present invention relates to a battery cell including a sealed portion having an embossed pattern formed thereon and a sealing block for manufacturing the same. More particularly, the present invention relates to a battery cell including a sealed portion having an embossed pattern formed thereon, wherein the embossed pattern is configured to prevent easy venting of a sealed portion of a pouch-shaped battery cell, and a sealing block for manufacturing the same.
A lithium secondary battery, which is capable of being charged and discharged, has been widely used as an energy source for wireless mobile devices or wearable devices, which are worn on bodies, and has also been used as an energy source for electric vehicles and hybrid electric vehicles presented as alternatives to existing gasoline and diesel vehicles, which cause air pollution.
Depending on the material and shape of a battery case, the lithium secondary battery may be classified as a cylindrical battery cell having an electrode assembly mounted in a metal can, a prismatic battery cell having an electrode assembly mounted in a metal can, or a pouch-shaped battery cell having an electrode assembly mounted in a battery case made of a laminate sheet. The pouch-shaped battery cell has advantages of easy deformation and high energy density.
In order to seal the pouch-shaped battery cell, a method of pressing an outer periphery of the battery case using a high-temperature sealing block to form a sealed portion is used. If such a sealing method is used, however, venting of the pouch-shaped battery cell easily occurs when internal pressure of the pouch-shaped battery cell is increased.
Accordingly, methods of improving sealability of the pouch-shaped battery cell have been devised.
Patent Document 1 discloses a power storage device configured such that, in a sealed container formed of a power storage device sheathing member including a metal foil layer, an anti-corrosion treatment layer, and a sealant layer, which are sequentially stacked, an edge portion at which the sealant layers contact each other is sealed by thermal sealing, and a thin concave portion is formed at the edge portion.
In Patent Document 1, the thin portion is formed at the sealed portion formed by thermal sealing, whereby the edge portion is easily bent.
Patent Document 2 discloses a film coated battery including a sheathing film configured such that at least a thermally fusible resin layer and a metal thin film layer are stacked, a battery element is surrounded in the state in which the thermally fusible resin layer faces inside, and a peripheral joining portion is thermally fused to seal the battery element, wherein at least one bent portion is formed at the joining portion, and the thickness of the bent portion is less than the thickness of the joining portion around the bent portion.
In Patent Document 2, the bent portion having a relatively small thickness is formed at the joining portion of the sheathing film, whereby formation of cracks at the bent portion due to difference in extension of the film inside and outside the joining portion is prevented.
Patent Document 3 discloses a sealing device for performing preliminary sealing, the preliminary sealing and main sealing being sequentially performed in order to seal a pouch-shaped battery case, wherein the sealing device includes a press configured to heat and press one surface and the other surface of an outer periphery of a sheet member for battery cases in order to form a preliminary sealed portion and a pair of sealing blocks, each including a fixing portion configured to fix the sheet member, a sealing protrusion is formed on the press so as to protrude outwards, and an outer end of the sealing protrusion is round when viewed in vertical section.
In Patent Document 3, the preliminary sealing is performed before the main sealing, whereby formation of wrinkles on an outer surface of a battery cell is reduced.
However, the above patent documents do not suggest technology capable of easily providing a structure capable of increasing sealing force of a pouch-shaped battery cell, and therefore there is a need to develop such technology.
The present invention has been made in view of the above problems, and it is an object of the present invention to provide a battery cell including a sealed portion having an embossed pattern formed thereon such that a structure in which sealing force of a sealed portion of a pouch-shaped battery cell is increased is applicable using a simple method.
A battery cell according to the present invention to accomplish the above object includes a pouch-shaped battery case configured to receive an electrode assembly therein, wherein the pouch-shaped battery case is provided at an outer periphery thereof surrounding an electrode assembly receiving portion with a sealed portion, and an embossed pattern is formed on the sealed portion in all directions.
The embossed pattern may be formed such that reliefs when viewed from above the sealed portion are intaglios when viewed from under the sealed portion and such that intaglios when viewed from above the sealed portion are reliefs when viewed from under the sealed portion.
The embossed pattern may be formed such that the reliefs and the intaglios are alternately repeated when viewed from above the sealed portion.
The embossed pattern may be formed at regular intervals while having regular sizes.
The intervals of the embossed pattern formed on the sealed portion in a direction in which an electrode lead protrudes may be less than the intervals of the embossed pattern formed on the sealed portion in a direction in which no electrode lead protrudes.
The vertical section of the embossed pattern may be polygonal, semicircular, or semielliptical.
The present invention provides a sealing block for manufacturing the battery cell. Specifically, the sealing block includes an upper sealing block disposed above a sealed portion of a pouch-shaped battery cell and a lower sealing block disposed under the sealed portion of the pouch-shaped battery cell, wherein the upper sealing block and the lower sealing block are provided with recesses and protrusions configured to be engaged with each other at positions at which the upper sealing block and the lower sealing block correspond to each other.
The protrusions may protrude toward the sealed portion of the pouch-shaped battery cell.
Alternatively, the protrusions may be configured such that shapes protruding upwards toward the sealed portion of the pouch-shaped battery cell and shapes protruding downwards toward the sealed portion of the pouch-shaped battery cell are alternately repeatedly arranged.
The present invention provides a battery module including the battery cell as a unit battery.
In addition, the present invention may provide various combinations of the above solving means.
As is apparent from the above description, a battery cell according to the present invention is configured such that an embossed pattern is formed on the entirety of a sealed portion, whereby the total surface area of the sealed portion is increased. Consequently, contact area between an upper case and a lower case may be increased, and therefore sealing force of the battery cell may be increased.
Even when a pouch-shaped battery cell is deformed, therefore, it is possible to prevent opening of the sealed portion, and even when internal pressure of the battery cell is increased, it is possible to inhibit explosion of the battery cell.
In addition, it is possible to form the embossed pattern on the sealed portion during a conventional battery cell manufacturing process, and therefore expansion of production facilities is unnecessary.
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.
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.
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.
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.
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.
Embodiments of the present invention will be described in detail with reference to the accompanying drawings.
The battery cell 100 is a pouch-shaped battery cell including a pouch-shaped battery case 110 made of a laminate sheet. The pouch-shaped battery case 110 includes an upper case 111 having an electrode assembly receiving portion 114 configured to receive an electrode assembly formed therein and a lower case 112 located under the upper case 111.
The battery case may be made of a laminate sheet configured such that an outer resin layer, an air and moisture blocking metal layer, and a thermally fusible inner resin layer are stacked.
It is required for the outer resin layer to exhibit excellent tolerance to an external environment, and therefore more than predetermined tensile strength and weather resistance are necessary. For example, the outer resin layer may include polyethylene naphthalate (PEN), polyethylene terephthalate (PET), or oriented nylon.
The metal layer may be made of aluminum (Al) or an aluminum alloy in order to exhibit a function of improving strength of the battery case in addition to a function of preventing introduction of foreign matter, such as gas and moisture, or leakage of an electrolytic solution.
A polymer resin that exhibits thermal fusibility, has low hygroscopicity to the electrolytic solution, and is not expanded or eroded by the electrolytic solution may be used as the inner resin layer. For example, the inner resin layer may be made of a cast polypropylene (CPP) film.
The upper case 111 and the lower case 112 contact each other at outer peripheries thereof that surround the electrode assembly receiving portion. When the outer peripheries are heated and pressed, the inner resin layer of the upper case and the inner resin layer of the lower case are melted and coupled to each other to form a sealed portion 115.
In the battery cell 100, the upper case 111 and the lower case 112 are connected to each other, and the sealed portion 115 is formed at three direction outer peripheries thereof excluding a bent portion.
That is, the sealed portion formed at the three-way outer peripheries includes overall width direction (W) sealed portions located at opposite ends of the battery cell and an overall length direction (H) sealed portion, and an embossed pattern 116 is formed on all of the sealed portions.
The embossed pattern 116 may be formed on all of the sealed portions so as to have regular sizes and to be disposed at regular intervals such that all of the sealed portions have the same sealing force.
Alternatively, since internal pressure is most greatly increased in an overall length direction middle part of the overall length direction (H) sealed portion, the embossed pattern may be formed on the overall length direction middle part at smaller intervals.
Alternatively, electrode leads 120 extend outwards from the battery case at the overall width direction (W) sealed portions, and sealing force at parts from which the electrode leads 120 protrude is further reduced. In order to prevent reduction in sealing force at the parts from which the electrode leads 120 protrude, therefore, the embossed pattern formed on the sealed portions in directions in which the electrode leads 120 protrude may be formed at smaller intervals than the embossed pattern formed on the sealed portion in a direction in which the electrode leads 120 do not protrude. This construction may also be equally applied to a unidirectional battery cell configured such that electrode leads protrude from one direction sealed portion.
The embossed pattern formed on the battery cell 100 generally has a cylindrical shape and a circular shape when viewed in plan. However, the shape of the embossed pattern is not particularly restricted as long as it is possible to increase the adhesion area between the upper case and the lower case. For example, the vertical section of the embossed pattern may be polygonal, semicircular, or semielliptical.
In the present invention, the embossed pattern is formed in order to increase the adhesion area of the battery case on the sealed portion. The embossed pattern may be formed such that relief parts when viewed from above the sealed portion are intaglio parts when viewed from under the sealed portion and such that intaglio parts when viewed from above the sealed portion are relief parts when viewed from under the sealed portion.
Referring to
The battery cell 200 is configured to have a structure in which an electrode assembly receiving portion 214 is formed in each of the upper case 211 and the lower case 212 in order to receive a bidirectional electrode assembly having electrode leads 220 protruding in opposite directions, which may be more suitable to manufacture a high-capacity battery cell.
The battery cell 200 is different in shape of an embossed pattern from the battery cell 100. Specifically, the embossed pattern 216 generally has a quadrangular prism shape and a quadrangular shape when viewed in plan. In addition, the embossed pattern 216 is formed up to the end of a sealed portion. Consequently, the adhesion area between the upper case 211 and the lower case 212 on the sealed portion 215 may be wider, whereby sealing force may be further improved.
Meanwhile, the battery cell 200 is configured such that the embossed pattern formed on the overall width direction (W) sealed portion and the embossed pattern formed on the overall length direction (H) sealed portion are different in size and interval from each other. Consequently, it is possible to freely set the size and interval of the embossed pattern in order to secure desired sealing force.
A description of the battery cell 100 may be equally applied to the other parts of the battery cell 200, and therefore a detailed description thereof will be omitted.
Referring to
The embossed pattern shown in (a) of
The embossed pattern shown in (b) of
The embossed pattern shown in (c) of
The embossed pattern according to the present invention is not limited to the shapes shown in
Referring to
The upper sealing block 310 and the lower sealing block 320 are configured to be engaged with each other at positions at which the upper sealing block and the lower sealing block correspond to each other. Concave recesses 340 are formed based on a sealing surface 301, and convex protrusions 330 are formed based on the sealing surface 301.
When the sealed portion of the pouch-shaped battery cell is disposed between the upper sealing block 310 and the lower sealing block 320 and the sealed portion is pressed and heated, the embossed pattern shown in (a) of
Referring to
The upper sealing block 410 and the lower sealing block 420 are configured to be engaged with each other at positions at which the upper sealing block and the lower sealing block correspond to each other. Concave recesses 440 are formed based on a sealing surface 401, and convex protrusions 430 are formed based on the sealing surface 401.
The protrusions 430 are configured such that portions protruding upwards toward the sealed portion of the pouch-shaped battery cell and portions protruding downwards toward the sealed portion of the pouch-shaped battery cell are alternately repeatedly arranged, and the recesses 440 are formed in the sealing blocks that face each other so as to be engaged with the protrusions 430.
In the battery cell according to the present invention, the sealing force of the sealed portion is increased. In a battery module including the battery cell as a unit battery, therefore, the battery cell may not be vented even at larger internal pressure. Consequently, safety of the battery module may be improved.
Hereinafter, the present invention will be described with reference to examples. These examples are provided only for easier understanding of the present invention and should not be construed as limiting the scope of the present invention.
A pouch-shaped battery cell was prepared, and an outer periphery of the pouch-shaped battery cell was sealed such that an embossed pattern was formed on the entirety of the sealed portion.
A pouch-shaped battery cell was prepared, and an outer periphery of the pouch-shaped battery cell was sealed such that the sealed portion was flat.
<Maximum Deformation Amount and Maximum Stress Measurement 1>
The maximum deformation amount and the maximum stress of each of the battery cells manufactured according to Experimental Example 1 and Experimental Example 2 were measured while an internal pressure of 0.01 MPa was applied thereto. The results of the maximum deformation amount structure simulation of Experimental Example 1 are shown in
Structure simulation was performed using Meshfree, which is a CAE tool developed by Midas IT Co., Ltd. Three-dimensional shapes were implemented using SolidWorks, which is a CAD program, and then structure simulation was performed on the respective shapes using Meshfree.
Referring to
Referring to
Experimental Example 1, in which the embossed pattern was formed on the entirety of the sealed portion, exhibited a maximum deformation amount smaller than the maximum deformation amount of Experimental Example 2, in which the sealed portion was flat, and therefore it can be seen that the pouch-shaped battery cell having the embossed pattern formed on the entirety of the sealed portion thereof has a harder structure having a small deformation amount with respect to an increase in internal pressure.
In addition, when the same internal pressure was applied, the maximum stress of Experimental Example 1 was measured to be smaller than the maximum stress of Experimental Example 2. Consequently, it can be seen that the pouch-shaped battery cell having the embossed pattern formed on the entirety of the sealed portion thereof is capable of withstanding larger internal pressure.
It can be seen from the above results that, when the embossed pattern is formed on the entirety of the sealed portion of the pouch-shaped battery cell, sealing force is increased.
<Maximum Deformation Amount and Maximum Stress Measurement 2>
The maximum deformation amount and the maximum stress of each of the battery cells manufactured according to Experimental Example 1 and Experimental Example 2 were measured while an internal pressure of 0. 1 MPa was applied thereto. The results of the maximum deformation amount structure simulation of Experimental Example 1 are shown in
Structure simulation was performed using the same method as in the maximum deformation amount and maximum stress measurement of Experimental Example 1 and Experimental Example 2.
Referring to
Experimental Example 1, in which the embossed pattern was formed on the entirety of the sealed portion, exhibited the maximum deformation amount and the maximum stress smaller than the maximum deformation amount and the maximum stress of Experimental Example 2, in which the sealed portion was flat.
When the embossed pattern is formed on the entirety of the sealed portion of the pouch-shaped battery cell, therefore, the pouch-shaped battery cell may have a harder structure, and sealing force may be maintained even when internal pressure is more greatly increased.
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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2021-0138266 | Oct 2021 | KR | national |
This application is a national phase entry under 35 U.S.S. § 317 of International Application No. PCT/KR2022/015812 filed on Oct. 18, 2022, which claims the benefit of priority to Korean Patent Application No. 2021-0138266 filed on Oct. 18, 2021, all of which is incorporated herein by reference in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/KR2022/015812 | 10/18/2022 | WO |
