Foldable bag-shaped battery cell and method of manufacturing the same
Patent Information
- Application Number
- ES2021807925T
- Authority / Receiving Office
- ES · ES
- Patent Type
- Patents
- Current Assignee / Owner
- Priority Date
- 2020-05-22
- Filing Date
- 2021-05-24
- Publication Date
- 2026-09-15
- Estimated Expiration
- 2041-05-24
Smart Images
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Abstract
Description
Foldable bag-shaped battery cell and method of manufacturing the same Technology sector This application claims the benefit of priority over Korean patent application no. 2020-0061358 filed on May 22, 2020. The present invention relates to a foldable bag-shaped battery cell and a method of manufacturing the same, and more particularly to a foldable bag-shaped battery cell configured so that an uncoated portion, which is a portion not coated with an electrode mixture, is formed in a portion of the battery cell that is to be folded and a stepped structure is formed having a recessed shape in the portion of a bag-shaped battery housing corresponding to the uncoated portion, so that it is possible to prevent movement of the electrode assembly, and a method of manufacturing the same. Background of the invention A secondary lithium battery, which is capable of being charged and discharged, has been widely used as a power source for wireless mobile devices or portable devices, and has also been used as a power source for electric vehicles and hybrid electric vehicles presented as alternatives to existing gasoline and diesel vehicles, which cause air pollution. Furthermore, with an increase in the types of miniaturized multifunctional products and a trend to emphasize design in electronic devices, there has been an increase in the number of products based on new shapes, such as a shape that includes a curve or a geometric shape, distinct from conventional simple structures, such as a flat structure and a prismatic structure. Secondary lithium batteries have been developed that have various shapes, such as a stepped shape and a polygonal shape, distinct from a rectangular shape, to apply the secondary lithium batteries to such products that have various shapes. For example, for a smartphone, the side is curved to improve the grip, and flexible display products capable of bending or folding have entered the scene. When a rectangular battery cell is used in a device that can be bent or folded, a significant amount of dead space is created. Therefore, it is necessary to develop a battery cell that can maintain capacity while minimizing dead space, even when mounted in an atypically shaped device. In connection with this, patent document 1 discloses a secondary battery configured such that a layer of positive electrode active material and a layer of negative electrode active material are formed by coating so that they are spaced apart from each other by a predetermined distance and including a flexing region configured to bend into an uncoated portion, which is not coated with the layer of positive electrode active material and the layer of negative electrode active material. The secondary battery disclosed in patent document 1 is suitable for a long device but has the problem that a plurality of bending regions are formed, so the uncoated portion widens and thus the energy density decreases. Patent document 2 refers to a battery cell that includes a current collector having at least one uncoated portion that divides a mixture of electrodes, wherein the portion of a battery casing in which the uncoated portion is located is bent, thereby changing the shape of the battery cell. In patent document 2, an electrode assembly is separated from the battery housing, so there is the problem that a bent portion of the battery housing and a bent portion of the electrode assembly can become misaligned with each other when the battery cell is bent. Patent document 3 discloses a battery cell configured such that a recess is formed in a sealing portion to prevent wrinkling of the sealed portion when the battery cell is bent. In this structure, however, a layer of electrode mixture can separate from an electrode assembly when the electrode assembly is bent. Patent document 4 discloses an electrode assembly having flexing portions. Patent document 5 discloses a flexible electrode assembly including an alternately arranged uncoated portion and coated portion. Therefore, there is a great need for a battery cell applicable to devices that have various shapes, such as a battery cell that can be bent or folded, and technology capable of ensuring the safety of the battery cell while preventing a decrease in the battery cell's capacity. (Documents of the prior art) (Patent Document 1) Korean Patent Application Publication No. 2012-0022385 (12-03-2012) (Patent Document 2) Korean Patent Application Publication No. 2017-0033513 (27-03-2017) (Patent Document 3) Korean Patent Application Publication No. 2015-0096325 (24-08-2015) (Patent Document 4) U.S. Patent No. 10,014,551 (03-07-2018) (Patent Document 5) Korean Patent Application Publication No. 2015-0128063 (11-18-2015) Explanation of the Invention Technical problem The present invention has been made in view of the above problems, and an object of the present invention is to provide a foldable pouch-shaped battery cell configured so that an uncoated portion, which is a portion not coated with an electrode mixture, is formed on an electrode and a stepped structure having a recessed shape is formed on the portion of a pouch-shaped battery casing corresponding to the uncoated portion, so that it is possible to avoid the dislocation of an electrode assembly and thus improve the safety of the pouch-shaped battery cell, and a method of manufacturing the same. Technical solution A bag-shaped battery cell according to the present invention for achieving the above object is a bag-shaped battery cell as defined in claim 1. In the bag-shaped battery cell according to the present invention, positive electrode tabs and negative electrode tabs can protrude from one of the outer peripheries of the electrode assembly in the direction of the overall width. In the bag-shaped battery cell according to the present invention, each of the positive and negative electrodes may have a first coated portion and a second coated portion formed symmetrically or asymmetrically with respect to the uncoated portion, and each of the positive and negative electrodes may be folded into the uncoated portion. Additionally, a positive electrode tab or a negative electrode tab may protrude from one of the first coated portion or the second coated portion. Additionally, the insulating member can be an insulating tape or an insulating solution. In the bag-shaped battery cell according to the present invention, a wrinkled fold line can be formed in the uncoated portion. In the pouch-shaped battery cell according to the present invention, the pouch-shaped battery housing may include a first battery housing and a second battery housing, and a stepped portion may be formed in a portion of at least one of the first battery housing and the corresponding second battery housing, corresponding to the uncoated portion, so that it is recessed inwards. In addition, the recessed stepped portion of the pouch-shaped battery housing can be attached to each of the highest and lowest electrodes of the electrode assembly. In the pouch-shaped battery cell according to the present invention, the pouch-shaped battery casing can be folded as a result of the electrode assembly being folded, and a notch can be formed in a sealed portion located in the portion of the pouch-shaped battery casing that is folded. Furthermore, the present invention provides a method for manufacturing the bag-shaped battery cell according to claim 10. In the method according to the present invention, an insulating tape can be attached or an insulating solution can be applied in step (b). The method according to the present invention may include a manufacturing process of an electrode assembly by stacking a positive electrode and a negative electrode manufactured by cutting the electrode foil slit in step (d) with a separator interposed between them, receiving the electrode assembly in a bag-shaped battery housing having a stepped portion formed therein, and hermetically sealing the bag-shaped battery housing. Furthermore, the method according to the present invention may further include a process of receiving the electrode assembly into a bag-shaped battery housing having stepped portions formed therein and joining each of the highest and lowest electrodes of the electrode assembly to a corresponding of the stepped portions of the bag-shaped battery housing. Advantageous effects As is evident from the above description, a bag-shaped battery cell according to the present invention is configured to have a structure in which an uncoated portion is formed, which is a portion not coated with an electrode mixture, in each of a positive electrode and a negative electrode, and an electrode assembly is folded into the uncoated portion, so that it is possible to avoid the separation of an electrode mixture layer from an electrode current collector as a result of folding. Furthermore, a stepped portion is formed that has a recessed shape in the portion of a pouch-shaped battery housing corresponding to the uncoated portion of the electrode assembly, so that it is possible to seat and fix a coated portion of the electrode assembly onto a protruding portion of the pouch-shaped battery housing, which protrudes relatively. Furthermore, when the uncoated portion of the electrode assembly is attached to the stepped portion of the pouch-shaped battery casing, the electrode assembly's position can be more securely fixed. This prevents the electrode assembly from separating and thus avoids damage to the electrode tabs and electrode wire. Brief description of the drawings Figure 1 is a plan view showing the stacked electrodes according to the present invention. Figure 2 is a side view of an electrode according to the present invention. FIG.3 is a side view of an electrode that has a fold line formed on it. FIG.4 is a side view of bag-shaped battery cells according to the present invention. FIG. 5 is a partial enlarged view of a vertical section of a bag-shaped battery cell according to the present invention. FIG.6 is a perspective view of a pouch-shaped battery cell having a notch formed in a sealed portion thereof. FIG. 7 is a perspective view showing an upward bending process of a bag-shaped battery cell according to the present invention based on an x-axis. FIG. 8 is a perspective view showing a downward bending process of the bag-shaped battery cell according to the present invention based on the x-axis. FIG. 9 is a perspective view showing an upward bending process of a bag-shaped battery cell according to the present invention based on a y-axis. Preferred embodiment of the invention Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings so that these preferred embodiments can be readily implemented by a person skilled in the art to which the present invention belongs. However, in describing the operating principle of the preferred embodiments of the present invention in detail, a detailed description of known functions and configurations incorporated herein will be omitted where such descriptions might obscure the subject matter of the present invention. Furthermore, the same reference numbers will be used on all drawings to refer to parts that perform similar functions or operations. When a part is described as being connected to another part in the description, the first part may be directly connected to the second, or it may be indirectly connected to the second by means of an additional part. Additionally, the inclusion of a certain element does not exclude other elements; it simply means that such elements may be included unless otherwise stated. Furthermore, in the description of the invention and the claims of this application, singular forms are intended to include plural forms unless otherwise stated. Furthermore, in the description of the invention and the claims of this application, "or" includes "and" unless otherwise stated. Therefore, "which includes A or B" means three cases, namely, the case which includes A, the case which includes B, and the case which includes both A and B. Furthermore, all numerical ranges include the lowest value, the highest value, and all intermediate values between them, unless the context clearly indicates otherwise. The embodiments of the present invention will be described in detail with reference to the accompanying drawings. A pouch-type battery cell according to the present invention is configured to have a structure in which an electrode assembly is received in a pouch-type battery housing made of a laminated sheet comprising an outer resin layer, a barrier layer, and an inner adhesive layer in a hermetically sealed state. The electrode assembly may be a stacked-type electrode assembly, configured to have a structure in which a positive electrode and a negative electrode are stacked in the state in which a separator is interposed between them, or a laminated-stacked-type electrode assembly, configured to have a structure in which two or more bi-cells, each of which has positive and negative electrodes arranged in the state in which two separators are respectively interposed between them, are laminated in a stacked state. Each of the positive and negative electrodes is configured to have a flat rectangular shape of a structure in which the length of the electrode in one direction of the overall width is less than the length of the electrode in one direction of the overall length, and has a structure in which an uncoated portion, which is a portion not coated with an electrode mixture, is formed parallel to the outer peripheries of the electrode in the direction of the overall width or the outer peripheries of the electrode in the direction of the overall length and a coated portion, which is coated with an electrode mixture, is formed in the remaining portion of the electrode excluding the uncoated portion. The bag-shaped battery cell according to the present invention is foldable, wherein the uncoated portion is folded, thus the bag-shaped battery cell is folded. In connection with this, an electrode mixture formed in an electrode current collector by coating can separate from the folded portion of the electrode current collector when the pouch-shaped battery cell is folded. To avoid this, in the present invention, the uncoated portion is formed, and the pouch-shaped battery cell is folded into the uncoated portion, thus preventing the aforementioned problem. FIG.1 is a plan view showing the state in which electrodes are stacked according to the present invention, and FIG.2 is a side view of an electrode according to the present invention. With reference to FIG. 1, electrodes (a) and electrodes (b) are shown. With reference to FIG. 2, a side view of the positive electrode (a) of FIG. 1 is shown. In FIG. 1, a separator interposed between a positive and a negative electrode is omitted for the sake of clarity. Electrodes (a) and (b) are stacks of positive electrodes 110 and 210 and negative electrodes 120 and 220 configured to have a structure in which the electrode length in the overall width direction, i.e., an x-axis direction, is less than the electrode length in the overall length direction, i.e., a y-axis direction. Each of the positive electrode tabs 112 and 212 and the negative electrode tabs 122 and 222 projects from one of the outer peripheries of a corresponding electrode in the overall width direction. Each of the electrodes (a) has a structure in which an uncoated portion, which is a portion not coated with an electrode mixture, is formed parallel to the outer peripheries of the electrode in the overall width direction. The positive electrode 110 has coated portions 111 formed symmetrically with respect to an uncoated portion 115 formed parallel to the outer peripheries of the electrode in the overall width direction, and the negative electrode 120 has coated portions 121 formed symmetrically with respect to an uncoated portion 125 formed parallel to the outer peripheries of the electrode in the overall width direction. For the positive electrode 110, an insulating member 113 is added to the external surfaces of a portion of the uncoated portion 115 and a portion of each coated portion 111 as a boundary portion between the uncoated portion 115 and the coated portion 111. For the negative electrode 120, an insulating member 123 is added to the external surfaces of a portion of the uncoated portion 125 and a portion of each coated portion 121 as a boundary portion between the uncoated portion 125 and the coated portion 121. Each of the electrodes (b) has a structure in which an uncoated portion, which is a portion not coated with an electrode mixture, is formed parallel to the outer peripheries of the electrode in the overall length direction. The positive electrode 210 has coated portions 211 formed symmetrically with respect to an uncoated portion 215 formed parallel to the outer peripheries of the electrode in the overall length direction, and the negative electrode 220 has coated portions 221 formed symmetrically with respect to an uncoated portion 225 formed parallel to the outer peripheries of the electrode in the overall length direction. For the positive electrode 210, an insulating member 213 is added to the external surfaces of a portion of the uncoated portion 215 and a portion of each coated portion 211 as a boundary portion between the uncoated portion 215 and the coated portion 211. For the negative electrode 220, an insulating member 223 is added to the external surfaces of a portion of the uncoated portion 225 and a portion of each coated portion 221 as a boundary portion between the uncoated portion 225 and the coated portion 221. Meanwhile, the present invention relates to a bag-shaped battery cell that folds based on an uncoated portion and, therefore, asymmetrical coated portions can be formed with respect to the uncoated portion, unlike what is shown in FIGS.1 and 2. Although the present invention relates to a foldable, pouch-shaped battery cell, it is preferable to understand that the pouch-shaped battery cell does not always remain folded when in use and can be folded or unfolded as required. Therefore, it is preferable that the electrode tabs protrude in one direction in the state where the pouch-shaped battery cell according to the present invention is not folded. The electrode tabs protrude from one of the outer peripheries of the electrode in the direction of the overall width. Furthermore, assuming that, for electrodes (a), the coated portions 111 and 121 located above the uncoated portions 115 and 125 are the first coated portions and the coated portions 111 and 121 located below the uncoated portions 115 and 125 are the second coated portions, the positive electrode tab 112 and the negative electrode tab 122 protrude from the first coated portions. Assuming that, for electrodes (b), the coated portions 211 and 221 located on the left sides of the uncoated portions 215 and 225 are the first coated portions and the coated portions 211 and 221 located on the right sides of the uncoated portions 215 and 225 are the second coated portions, the positive electrode tab 212 and the negative electrode tab 222 protrude from the first coated portions.Since the positive electrode tab or the negative electrode tab is formed on any coated portion, as described above, the positions of a positive electrode terminal and a negative electrode terminal can be fixed uniformly regardless of whether the pouch-shaped battery cell is folded or unfolded. Each of the insulating members 113 and 213 can be configured to have a structure in which an insulating layer is bonded to an adhesive substrate layer, such as insulating tape. Accordingly, the insulating tape is added to the edge portion between the coated and uncoated portions by bonding, or an insulating solution obtained by dissolving an insulating material in a solvent is added to the edge portion between the coated and uncoated portions by coating. The insulating layer of the insulating tape can be made of cast polypropylene (CPP) or poly(ethylene terephthalate) (PET). The insulating solution can be manufactured, for example, by mixing styrene-butadiene rubber (SBR), alumina (Al2O3) and carboxymethylcellulose (CMC) in a weight ratio of 80:20:0.008 to prepare a mixture and adding 40% by weight of distilled water to the mixture. A method of manufacturing a pouch-shaped battery cell according to the present invention may include (a) a step of coating an electrode foil to form a coated portion, which is a portion coated with an electrode mixture, and an uncoated portion, which is a portion not coated with an electrode mixture; (b) a step of adding an insulating member to the external surfaces of a portion of the coated portion and a portion of the uncoated portion as a rim portion between the coated and uncoated portions; (c) a step of rolling the electrode foil; and (d) a step of cutting the electrode foil from step (c). The insulating member may be formed in the coated portion by coating to a size of at least 0.1 mm. Preferably, the insulating member is formed in the coated portion by coating to overlap the coated portion by less than 0.4 mm. To avoid an increase in the overall thickness of the electrode due to the addition of the insulating member, however, it is preferable that the thickness of the insulating member not be greater than the thickness of the coated portion based on the insulating member formed in the uncoated portion. Since the insulating member is added to the edge portion between the uncoated portion and the coated portion, as in the present invention, it is possible to prevent the occurrence of a short circuit due to contact between the positive electrode and the negative electrode even if the separator interposed between the positive electrode and the negative electrode contracts. In connection with this, since the area of the coated portion of the negative electrode is generally designed to be larger than the area of the coated portion of the positive electrode, the coated portion of the negative electrode is arranged in contact with the coated portion of the positive electrode in the stacking direction. Therefore, if the separator contracts due to overheating of the electrode assembly, a short circuit can occur due to contact between the coated portion of the negative electrode and the coated portion of the positive electrode. In the present invention, since the insulating member is added to the edge between the coated portion and the uncoated portion, it is possible to prevent contact between the coated portion of the negative electrode and the coated portion of the positive electrode even if the separator contracts. In the electrode according to the present invention, it is preferable that the height of the uncoated portion, which corresponds to the distance between the first coated portion and the second coated portion, be uniformly formed in a lateral direction perpendicular to the uncoated portion. To prevent the coated portion from separating from the electrode current collector even if the electrode assembly is folded 180 degrees, the height of the uncoated portion can be determined by considering the thickness of the electrode current collector and the thickness of the coated portion formed on one or more opposite surfaces of the electrode current collector by coating. FIG.3 is a side view of an electrode that has a fold line formed on it. With reference to FIG.3, the electrode in FIG.3 is similar to the electrode in FIG.2 but differs from the electrode in FIG.2 in that a wrinkled fold line 318 is formed in an uncoated portion 315. In the case where the 318 fold line is formed, as described above, the stress concentrated in a folded portion when the electrode is folded is dispersed, so it is possible to avoid damage to the folded portion. The above description of the electrode in FIG. 2 can be applied equally to an electrode tab, a coated portion, an uncoated portion, and an insulating member of the electrode in FIG. 3. Meanwhile, the method of manufacturing the bag-shaped battery cell according to the present invention may include a manufacturing process of an electrode assembly by stacking a positive electrode and a negative electrode manufactured by cutting the electrode foil slit in step (d) in the state in which a separator is interposed between them, receiving the electrode assembly in a bag-shaped battery housing having a stepped portion formed therein, and hermetically sealing the bag-shaped battery housing. FIG.4 is a side view of bag-shaped battery cells according to the present invention. With reference to FIG. 4, a pouch-shaped battery cell (a) and a pouch-shaped battery cell (b) include first battery casings 431 and 531 and second battery casings 432 and 532, respectively. The first battery casing 431 of the pouch-shaped battery cell (a) has a receiving portion 433 formed thereon, configured to receive an electrode assembly, and a stepped portion 436 is formed in the receiving portion 433 so that it is recessed inward. The stepped portion 436 is formed in a portion corresponding to the portion of the electrode assembly in which an uncoated portion is located. The second battery casing 432 has a flat shape and no receiving portion formed thereon. A receiving portion 533 is formed configured to receive an electrode assembly in each of the first battery housing 531 and the second battery housing 532 of the pouch-shaped battery cell (b), and a stepped portion 536 is formed in the receiving portion 533 so that it is recessed inward. The stepped portion 536 is formed in a portion corresponding to the portion of the electrode assembly in which an uncoated portion is located. Since the pouch-shaped battery cell (a) and the pouch-shaped battery cell (b) are configured respectively such that the stepped portions 436 and 536 are formed to correspond to the portions of the electrode assemblies in which the uncoated portions are located, as described above, the coated portions of the electrode assemblies are received respectively in the protruding portions 437 and 537, which protrude relatively, so that the electrode assemblies can be fixed in position in the battery housings. Furthermore, the method of manufacturing the bag-shaped battery cell according to the present invention may further include a process of receiving the electrode assembly in a bag-shaped battery housing having a stepped portion formed therein and attaching the highest and lowest electrodes of the electrode assembly to the stepped portion of the bag-shaped battery housing. In connection with this, FIG. 5 is a partial enlarged view of a vertical section of a bag-shaped battery cell according to the present invention. With reference to FIG. 5, an electrode assembly is the electrode assembly (a) of FIG. 1, and the separator is omitted for convenience of description. A battery casing is the battery casing of the pouch-shaped battery cell (b) shown in FIG. 4. The electrode assembly is a stacked-type electrode assembly, configured with a structure in which positive electrodes 110 and negative electrodes 120 are alternately stacked, with separators interposed between the positive and negative electrodes, respectively. Each of the positive electrodes 110 and negative electrodes 120 is provided with a coated portion and an uncoated portion. A stepped portion of a first battery casing 531 is attached to the uncoated portion of the negative electrode 120 located at the upper end of the electrode assembly, and a stepped portion of a second battery casing 532 is attached to the uncoated portion of the positive electrode 110 located at the lower end of the electrode assembly. Since the electrode assembly is attached to the battery casing in a pouch-like fashion, as described above, movement of the electrode assembly within the battery casing due to external impacts is prevented. Consequently, damage to the electrode tabs and electrode wire caused by movement of the electrode assembly is avoided. Figures 6 to 9 show pouch-shaped battery cells manufactured using the pouch-shaped battery cell manufacturing method described above. FIG.6 is a perspective view of a pouch-shaped battery cell having a notch formed in a sealed portion thereof. In the pouch-shaped battery cell according to the present invention, a notch can be formed in a battery housing to prevent damage to the battery housing due to the tensile force generated in the folding portion of the battery housing at the time of folding. With reference to FIG. 6, a stepped portion 636 and receiving portions 633 are formed on each of a first battery housing 631 and a second battery housing 632. When the pouch-shaped battery housing is folded upwards based on the stepped portion 636, as shown in FIG. 6, a sealed portion of the pouch-shaped battery housing can be extended by means of the two protruding receiving portions 633. Consequently, a notch 660 is formed in the sealed portion of the folded pouch-shaped battery housing, as in the pouch-shaped battery housing of FIG. 6, thus preventing damage to the pouch-shaped battery housing or the release of the seal from the sealed portion. FIG. 7 is a perspective view showing an upward bending process of a pouch-shaped battery cell according to the present invention based on an x-axis, and FIG. 8 is a perspective view showing a downward bending process of the pouch-shaped battery cell according to the present invention based on the x-axis. With reference to FIGS. 7 and 8, the pouch-shaped battery cell has a structure in which a stepped portion 736 is formed in a pouch-shaped battery shell so that it is parallel to the x-axis, i.e., a structure in which a stepped portion is formed in only a first battery shell, which is a top battery shell, as in the pouch-shaped battery cell (a) of FIG. 4. Consequently, in the case where the pouch-shaped battery cell is folded upwards, as shown in FIG. 7, the height of an uncoated portion of an electrode assembly and the distance between the protruding portions 737 must be established in consideration of the height of the protruding portions. However, in the case where the pouch-shaped battery cell is folded down, as shown in FIG. 8, the height of the uncoated portion of the electrode assembly and the distance between the protruding portions can be set to be less than the height of the uncoated portion of the electrode assembly in FIG. 7 and the distance between the protruding portions, since no protruding portions are formed in a second battery casing, which is a lower battery casing. Unlike what is shown in FIG.8, the pouch-shaped battery cell may have a structure in which a stepped portion and protruding portions are formed on each of the first battery shell and the second battery shell, as in the pouch-shaped battery cell (b) of FIG.4. FIG. 9 is a perspective view showing an upward bending process of a bag-shaped battery cell according to the present invention based on a y-axis. Referring to FIG. 9, a bag-shaped battery cell, which has a narrow and elongated shape depending on the device's configuration, can be applied. As shown in FIG. 9, the bag-shaped battery cell can be manufactured to fold along the y-axis, which is parallel to the overall length of the bag-shaped battery cell. The pouch-shaped battery cell of FIG.9 has a structure in which a stepped portion 836 is formed in a pouch-shaped battery shell so that it is parallel to the y-axis, i.e., a structure in which a stepped portion is formed in only a first battery shell, which is a top battery shell, as in the pouch-shaped battery cell (a) of FIG.4. Consequently, the height of an uncoated portion of an electrode assembly and the distance between protruding portions 837 must be established taking into consideration the height of the protruding portions. Although FIG. 9 shows the case where the pouch-shaped battery cell is folded upwards, the pouch-shaped battery cell can be folded downwards, as shown in FIG. 8. Furthermore, unlike what is shown in FIG. 9, the pouch-shaped battery cell may have a structure in which a stepped portion and protruding portions are formed on each of the first and second battery housings, as in the pouch-shaped battery cell (b) of FIG. 4. As described above, the pouch-shaped battery cell according to the present invention is configured so that the uncoated portion is formed on the electrode assembly and the stepped portion is formed on the pouch-shaped battery housing to correspond with the uncoated portion, so that a user can fold or unfold the pouch-shaped battery cell when in use.Furthermore, since the electrode assembly and the inner surface of the pouch battery casing are partially coupled together, it is possible to prevent movement of the electrode assembly within the pouch battery casing and thus improve the safety of the pouch battery cell. (Description of reference numbers) 110, 310: Positive electrodes 111, 121, 211, 221, 311: Coated portions 112, 212, 312: Positive electrode tabs 113, 123, 213, 223, 313: Insulating members 115, 125, 215, 225, 315: Uncoated portions 120, 220: Negative electrodes 122, 222: Negative electrode tabs 431, 531, 631: First battery cases 432, 532, 632: Second battery casings 433, 533, 633: Receiving portions 436, 536, 636, 736, 836: Staggered portions 437, 537, 737, 837: Outstanding portions 660: Notch Industrial applicability As is evident from the above description, a bag-shaped battery cell according to the present invention is configured to have a structure in which an uncoated portion is formed, which is a portion not coated with an electrode mixture, in each of a positive electrode and a negative electrode, and an electrode assembly is folded into the uncoated portion, so that it is possible to avoid the separation of an electrode mixture layer from an electrode current collector as a result of folding. Furthermore, a stepped portion is formed that has a recessed shape in the portion of a pouch-shaped battery housing corresponding to the uncoated portion of the electrode assembly, so that it is possible to seat and fix a coated portion of the electrode assembly onto a protruding portion of the pouch-shaped battery housing, which protrudes relatively. Furthermore, when the uncoated portion of the electrode assembly is attached to the stepped portion of the pouch-shaped battery casing, the electrode assembly's position can be more securely fixed. This prevents the electrode assembly from separating and thus avoids damage to the electrode tabs and electrode wire.
Claims
1. A pouch-shaped battery cell having an electrode assembly housed in a pouch-shaped battery casing, wherein the electrode assembly comprises positive electrodes (110, 210) and negative electrodes (120, 220), each of the positive and negative electrodes having a structure in which an electrode length in a global width direction (x-axis) is less than an electrode length in a global length direction (y-axis), each of the positive and negative electrodes having an uncoated portion (115, 125, 215, 225), which is a portion not coated with an electrode mixture, extending parallel to the outer peripheries of the electrode in the global width direction or the outer peripheries of the electrode in the global length direction, and a coated portion (111, 121, 211, 221), which is coated with the electrode mixture,formed in a remaining portion of the electrode excluding the uncoated portion, wherein a stepped structure (436, 536) is formed in a portion of the pouch-shaped battery housing corresponding to the uncoated portion so that it is recessed into the pouch-shaped battery housing, and wherein an insulating member (113, 123, 213, 223) is added to the external surfaces of a portion of the uncoated portion (115, 125, 215, 225) and a portion of the coated portion (111, 121, 211, 221) that serves as a border portion between the uncoated portion and the coated portion.
2. The pouch-shaped battery cell according to claim 1, wherein positive electrode tabs (112, 212) and negative electrode tabs (122, 222) project from one of the outer peripheries of the electrode assembly in the overall width direction (x-axis).
3. The pouch-shaped battery cell according to claim 1,wherein each of the positive electrodes (110, 210) and the negative electrodes (120, 220) has a first coated portion and a second coated portion formed symmetrically or asymmetrically with respect to the uncoated portion (115, 125, 215, 225), and wherein each of the positive and negative electrodes is folded into the uncoated portion.
4. The pouch-shaped battery cell according to claim 3, wherein a positive electrode tab (112, 212) or a negative electrode tab (122, 222) projects from one of the first coated portion or the second coated portion.
5. The pouch-shaped battery cell according to claim 1, wherein the insulating member (113, 123, 213, 223) is an insulating tape or an insulating solution.
6. The bag-shaped battery cell according to claim 1,wherein a creased fold line (318) is formed in the uncoated portion (315).
7. The pouch-shaped battery cell according to claim 1, wherein the pouch-shaped battery housing comprises a first battery housing (431, 531) and a second battery housing (432, 532), and wherein a stepped portion (436, 536) is formed in a portion of at least one of the first battery housing (431, 531) and the corresponding second battery housing (432, 532) uncoated portion so that it is recessed inwards.
8. The pouch-shaped battery cell according to claim 7, wherein the recessed stepped portion (436, 536) of the pouch-shaped battery housing is attached to each of a higher and a lower electrode of the electrode assembly.
9. The pouch-shaped battery cell according to claim 1, wherein the pouch-shaped battery casing folds as a result of the electrode assembly folding,and wherein a notch (660) is formed in a sealed portion located in a portion of the folded pouch-shaped battery housing.
10. A method of manufacturing the pouch-shaped battery cell according to any one of claims 1 to 9, the method comprising: (a) coating an electrode sheet to form a coated portion (111, 121, 211, 221), which is a portion coated with an electrode mixture, and an uncoated portion (115, 125, 215, 225), which is a portion not coated with an electrode mixture; (b) adding an insulating member (113, 123, 213, 223) to the external surfaces of a portion of the coated portion and a portion of the uncoated portion as a rim portion between the coated and uncoated portions; (c) rolling the electrode sheet; (d) cutting the electrode foil of step (c); and providing a bag-shaped battery casing having a stepped portion (436,536) formed in a portion of the bag-shaped battery casing corresponding to the uncoated portion (115, 125, 215, 225) so that it is recessed inwards.
11. The method according to claim 10, wherein an insulating tape is attached or an insulating solution is applied in step (b).
12. The method according to claim 10, comprising a process of: manufacturing an electrode assembly by stacking a positive electrode (110, 210) and a negative electrode (120, 220) manufactured by cutting the electrode foil slit in step (d) with a separator interposed between them; receiving the electrode assembly in the bag-shaped battery casing having the stepped portion (436, 536) formed therein; and hermetically sealing the bag-shaped battery casing.
13. The method according to claim 12, further comprising a process of: receiving the electrode assembly in the bag-shaped battery casing having stepped portions (436,536) formed therein; and join each of a higher and lower electrode of the electrode assembly to a corresponding of the stepped portions of the pouch-shaped battery casing.