Electrode assembly and battery cell including the same

Abstract

According to one embodiment of the present invention, there is provided an electrode assembly in which electrodes and separator sheets are alternately stacked, the electrodes include a first electrode and a second electrode, the separator sheet has a zigzag shape formed by folding at least twice, the length of the second electrode is smaller than the length of the first electrode, and an adhesive member is positioned between one of both sides of the electrode assembly and the second electrode.

Description

Technical Field

[0001] [Cross - Reference to Related Applications] This application claims the benefit of priority based on Korean Patent Application No. 10 - 2021 - 0133372 filed on October 7, 2021, and Korean Patent Application No. 10 - 2022 - 0117985 filed on September 19, 2022, and all the contents disclosed in the documents of the Korean patent applications are incorporated herein by reference in their entirety.

[0002] The present invention relates to an electrode assembly and a battery cell including the same, and more specifically, to an electrode assembly in which electrodes and separator sheets are alternately laminated in a Z - folded type, and a battery cell including the same, which prevents the electrodes from detaching from a fixed position and improves the stiffness of the electrode assembly even when the adhesive force of the separator sheet itself is low.

Background Art

[0003] Generally, types of secondary batteries include nickel - cadmium batteries, nickel - metal hydride batteries, lithium - ion batteries, and lithium - ion polymer batteries. These secondary batteries are applied not only to small products such as digital cameras, P - DVDs, MP3Ps, mobile phones, PDAs (registered trademarks), Portable Game Devices, Power Tools, and E - bikes, but also to large products that require high power such as electric vehicles and hybrid vehicles, as well as power storage devices for storing surplus generated power and renewable energy, and backup power storage devices.

[0004] To manufacture such secondary batteries, first, an electrode active material slurry is applied to a positive electrode current collector and a negative electrode current collector to manufacture a positive electrode and a negative electrode, and these are laminated on both sides of a separator to form an electrode assembly of a predetermined shape. Then, the electrode assembly is housed in a battery case and sealed after liquid injection.

[0005] Electrode assemblies are classified into various types. For example, the Simple Stack Type in which the positive electrode, separator membrane, and negative electrode are simply crossed and laminated continuously without manufacturing a unit cell, the Lamination & Stack Type (L&S) in which unit cells are first manufactured using the positive electrode, separator membrane, and negative electrode and then these unit cells are laminated, the Stack & Folding Type (S&F) in which a plurality of unit cells are attached to one side of a separator membrane sheet having a long length on one side at intervals and the separator membrane sheet is repeatedly folded in the same direction from one end, and the Z-Folding Type in which a plurality of electrodes or unit cells are alternately attached to one side and the other side of a separator membrane sheet having a long length on one side, and after the separator membrane sheet is folded in a specific direction from one end, the method of folding in the opposite direction is repeatedly alternated. Among these, the Z-Folding Type is frequently used in recent years because of its high alignment degree and liquid impregnation degree.

[0006] However, conventionally, after laminating the electrodes and the separator membrane sheet in such a Z-Folding Type, since a separate lamination process is not performed, the electrodes and the separator membrane sheet are not adhered to each other and the electrodes are detached from their fixed positions, resulting in a problem that the stiffness of the electrode assembly decreases. To solve this problem, a separate lamination process was performed after laminating the electrodes and the separator membrane sheet. However, since the overall thickness of the laminate in which the electrodes and the separator membrane sheet are laminated becomes thick, heat is not transmitted to the inside of the laminate, resulting in a problem that the adhesive force decreases. Such problems tend to be aggravated depending on the material of the separator membrane sheet. For example, when the adhesive force of the separator membrane sheet itself is low, the above-described problems become more aggravated.

[0007] Therefore, it is necessary to develop a Z-Folding Type electrode assembly that prevents the electrodes from detaching from their fixed positions and improves the stiffness of the electrode assembly even when the adhesive force of the separator membrane sheet itself is low, and a battery cell including the same. Summary of the Invention Problems to be Solved by the Invention

[0008] The problem to be solved by the present invention is an electrode assembly in which an electrode and a separator sheet are alternately laminated in a Z-folded type, and a battery cell including the same, which prevents the electrode from detaching from a fixed position, and provides an electrode assembly in which the stiffness of the electrode assembly is improved even when the adhesive force of the separator sheet itself is low, and a battery cell including the same.

[0009] The problem to be solved by the present invention is not limited to the problems described above, and problems not mentioned will be clearly understood by those having ordinary knowledge in the technical field to which the present invention pertains from the present specification and the attached drawings.

Means for Solving the Problem

[0010] An electrode assembly according to an embodiment of the present invention is an electrode assembly in which an electrode and a separator sheet are alternately laminated, the electrode includes a first electrode and a second electrode, the separator sheet has a zigzag form formed by being folded at least twice, the length of the second electrode is smaller than the length of the first electrode, and an adhesive member is located between one of both side surfaces of the electrode assembly and the second electrode.

[0011] The adhesive member is located between the separator sheet in contact with the upper surface of the second electrode and the separator sheet in contact with the lower surface of the second electrode, and the adhesive member can be located between the opposite side surface of the side surface of the second electrode wrapped by the separator sheet and the outer surface of the electrode assembly.

[0012] The first electrode and the second electrode are aligned such that the opposite side surface of the side surface of the first electrode wrapped by the separator sheet and the opposite side surface of the side surface of the second electrode wrapped by the separator sheet are biased toward one side surface of the outer surface of the electrode assembly.

[0013] One side of the both side surfaces of the adhesive member facing one end of the second electrode may be separated from the second electrode.

[0014] The opposite side surface of one side surface of the both side surfaces of the adhesive member facing one end of the second electrode can be arranged side by side with the outer surface of the electrode assembly.

[0015] Among the both side surfaces of the second electrode, the side surface wrapped by the separation membrane sheet is in contact with the separation membrane sheet, and among the both side surfaces of the first electrode, the side surface wrapped by the separation membrane sheet can be in contact with the separation membrane sheet.

[0016] The opposite side surface of the side surface of the both side surfaces of the first electrode wrapped by the separation membrane sheet can be located on the same vertical line as the outer surface of the electrode assembly.

[0017] The adhesive force between the electrode and the separation membrane sheet may be 0 gf / mm or more and 0.05 gf / mm or less.

[0018] One end of the separation membrane sheet can extend along the outer surface of the electrode assembly.

[0019] One end of the separation membrane sheet can wrap the entire outer surface of the electrode assembly.

[0020] The electrode assembly may further include a wrapping member that wraps the outer surface.

[0021] The wrapping member includes a first wrapping member and a second wrapping member. The first wrapping member wraps the portion of the outer surface of the electrode assembly where the opposite side surface of the both side surfaces of the first electrode wrapped by the separation membrane sheet is located, and the second wrapping member can wrap the portion of the outer surface of the electrode assembly where the opposite side surface of one side surface of the both side surfaces of the adhesive member facing one end of the second electrode is located.

[0022] The first wrapping member extends along one of the upper and lower surfaces of the electrode assembly, and the second wrapping member extends along the remaining one of the upper and lower surfaces of the electrode assembly.

[0023] The wrapping member may be composed of at least one of a hot-melt film and an adhesive tape.

[0024] A battery cell according to another embodiment of the present invention includes the electrode assembly described above.

Advantages of the Invention

[0025] According to the embodiment, the present invention is an electrode assembly in which electrodes and separator sheets are alternately laminated in a Z-folded type, and an adhesive member is located between the electrodes positioned between the separator sheets and the outer surface of the electrode assembly, and a battery cell including the same. The electrodes can be prevented from detaching from their fixed positions, and the stiffness of the electrode assembly can be improved even if the adhesive force of the separator sheet itself is low.

[0026] The effects of the present invention are not limited to the effects described above, and the effects not mentioned should be clearly understood by those having ordinary knowledge in the technical field to which the present invention pertains from the present specification and the attached drawings.

Brief Description of the Drawings

[0027]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Best Mode for Carrying Out the Invention

[0028] Hereinafter, with reference to the accompanying drawings, various embodiments of the present invention will be described in detail so that those having ordinary knowledge in the technical field to which the present invention pertains can easily implement them. The present invention can be implemented in various different forms and is not limited to the embodiments described herein.

[0029] To clearly explain the present invention, parts not related to the explanation are omitted, and the same reference numerals are given to the same or similar components throughout the specification.

[0030] In addition, the sizes and thicknesses of the respective components shown in the drawings are arbitrarily shown for convenience of explanation, and the present invention is not necessarily limited to those shown in the drawings. In the drawings, the thickness is enlarged to clearly represent a plurality of layers and regions. Also, in the drawings, for convenience of explanation, the thicknesses of some layers and regions are exaggerated.

[0031] Also, throughout the specification, when a certain part "includes" a certain component, it means that other components can be further included, rather than excluding other components, unless otherwise stated to the contrary.

[0032] Also, throughout the specification, "on a plane" means when the target part is viewed from above, and "in a cross-section" means when the cross-section obtained by vertically cutting the target part is viewed from the side.

[0033] Hereinafter, the electrode assembly according to an embodiment of the present invention will be described. However, here, the description is based on a partial cross-section of the electrode assembly, but it is not necessarily limited thereto, and the same or similar content can be described with other cross-sections.

[0034] FIG. 1 is a drawing showing a final electrode assembly according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the electrode assembly cut along the A-A' axis of FIG. 1.

[0035] Referring to FIGS. 1 and 2, the final electrode assembly 100 according to this embodiment can mean a structure in which a fixing tape (fixing member 300) is attached to the outer surface of the electrode assembly 200. Thereby, the final electrode assembly 100 can maintain the laminated alignment state among the first electrode 210, the second electrode 220, and the separation membrane sheet 230 included in the electrode assembly 200. However, it is not limited thereto, and the fixing tape (fixing member 300) may be omitted in the final electrode assembly 100 or replaced with other members to maintain the laminated alignment state among the first electrode 210, the second electrode 220, and the separation membrane sheet 230.

[0036] In addition, the final electrode assembly 100 can include an electrode lead 400 to which electrode tabs extending from a plurality of the first electrodes 210 and a plurality of the second electrodes 220 included in the electrode assembly 200 are joined. For example, as shown in FIG. 1, the electrode lead 400 may extend to both ends of the electrode assembly 200, and the electrode lead 400 can be classified into a positive electrode lead or a negative electrode lead according to the polarities of the first electrode 210 and the second electrode 220. However, the position of the electrode lead 400 is not limited thereto, and different from FIG. 1, they may extend together to one end of the electrode assembly 200.

[0037] In addition, the final electrode assembly 100 can include lead films 500 positioned above and below the electrode lead 400. Here, when the final electrode assembly 100 is mounted on a battery case (not shown), the lead films 500 can be sealed at a seal portion (not shown) together with the outer periphery of the battery case (not shown).

[0038] Referring to FIGS. 1 and 2, the electrode assembly 200 according to an embodiment of the present invention may be an electrode assembly in which electrodes (first electrode 210, second electrode 220) and a separation membrane sheet 230 are alternately laminated.

[0039] The electrodes 210, 220 can include a first electrode 210 and a second electrode 220. Here, the first electrode 210 and the second electrode 220 can include electrode active materials having different polarities from each other. That is, the first electrode 210 and the second electrode 220 may be electrodes having different polarities from each other. As an example, if the first electrode 210 is a positive electrode, the second electrode 220 may be a negative electrode. As another example, if the first electrode 210 is a negative electrode, the second electrode 220 may be a positive electrode.

[0040] Also, the length of the second electrode 220 may be smaller than the length of the first electrode 210. In other words, the length of the first electrode 210 may be larger than the length of the second electrode 220. As shown in FIG. 2, along the first length direction L1, the first electrode 210 and the second electrode 220 have different lengths from each other, and there may be a difference in length between the first electrode 210 and the second electrode 220. Thereby, a tolerance (d) may be formed between the second electrode 220 and the outer surface of the electrode assembly 200. Here, the first length direction L1 may be the height direction or the length direction of the electrode assembly 200.

[0041] The separation membrane sheet 230 can have a zigzag form formed by being folded at least twice (Folding). More specifically, as shown in FIG. 2, the separation membrane sheet 230 may be folded in a direction covering the first electrode 210 in a state where the first electrode 210 is laminated. Also, it may be folded in a direction covering the second electrode 220 in a state where the second electrode 220 is laminated on the separation membrane sheet 230 covering the first electrode 210. Thereafter, it may be folded in a direction covering the first electrode 210 in a state where the first electrode 210 is laminated on the separation membrane sheet 230 covering the second electrode 220. That is, the electrode assembly 200 can be formed by repeatedly laminating the first electrode 210 or the second electrode 220 and folding the separation membrane sheet 230.

[0042] Referring to FIG. 2, the first electrode 210 and the second electrode 220 may be aligned such that the side surfaces of the first electrode 210 that are not covered by the separation membrane sheet 230 among both side surfaces of the first electrode 210 and the side surfaces of the second electrode 220 that are covered by the separation membrane sheet 230 are biased to one side surface of the outer surface of the electrode assembly 200. In other words, within the zigzag-shaped structure formed by folding the separation membrane sheet 230, one end portion of the first electrode 210 and one end portion of the second electrode 220 can be aligned to be biased to one side surface of the electrode assembly 200. That is, the electrode assembly 200 according to the present embodiment may be aligned based on one side surface of the electrode assembly 200 instead of the first electrode 210 and the second electrode 220 being aligned based on the center of the electrode assembly 200.

[0043] Thereby, in the present embodiment, it is possible to prevent the second electrode 220 from being distorted within the separation membrane sheet 230, and the area of the adhesive member 250 located between the second electrode 220 and the outer surface of the electrode assembly 200, which will be described later, can be made larger.

[0044] Also, among the two side surfaces of the second electrode 220, the side surface wrapped by the separation membrane sheet 230 can be in contact with the separation membrane sheet 230, and among the two side surfaces of the first electrode 210, the side surface wrapped by the separation membrane sheet can be in contact with the separation membrane sheet 230. Here, the meaning that the side surface of the first electrode 210 or the second electrode 220 is in contact with the separation membrane sheet 230 can mean that the separation membrane sheet 230 extends along the side surface of the first electrode 210 or the second electrode 220, or the separation membrane sheet 230 can mean that it wraps the side surface of the first electrode 210 or the second electrode 220.

[0045] Thereby, in this embodiment, it is possible to more effectively prevent the first electrode 210 and the second electrode 220 from being distorted within the separation membrane sheet 230.

[0046] Also, among the two side surfaces of the first electrode 210, the opposite side surface of the side surface wrapped by the separation membrane sheet 230 can be located on the same vertical line as the outer surface of the electrode assembly 200. In other words, among the two side surfaces of the first electrode 210, the opposite side surface of the side surface wrapped by the separation membrane sheet 230 does not protrude or sink toward the outer surface of the electrode assembly 200.

[0047] Thereby, in this embodiment, it is possible to prevent the separation membrane sheet 230 located above the first electrode 210 and the separation membrane sheet 230 located below the first electrode 210 from being folded in the process.

[0048] Referring to FIG. 2, the adhesive member 250 is located between the second electrode 220 and the outer surface of the electrode assembly 200. In other words, the adhesive member 250 can be located within the tolerance (d) between the second electrode 220 and the outer surface of the electrode assembly 200. More specifically, the adhesive member 250 can be located between the separation membrane sheet 230 in contact with the upper surface of the second electrode 220 and the separation membrane sheet 230 in contact with the lower surface of the second electrode 220. Also, the adhesive member 250 can be located between the opposite side surface of the side surface of the second electrode 220 wrapped by the separation membrane sheet 230 and the outer surface of the electrode assembly 200.

[0049] Thus, in this embodiment, the adhesive member 250 is located in the space formed between the second electrode 220 and the outer surface of the electrode assembly 200, has a structure for improving space efficiency, and can complement the adhesive force between the electrodes (the first electrode 210 and the second electrode 220) and the separation film (the separation film sheet 230) to improve the stiffness of the electrode assembly 200.

[0050] Also, one side surface of the two side surfaces of the adhesive member 250 facing the second electrode 220 and one end portion can be separated from the second electrode 220. In other words, one of the two side surfaces of the adhesive member 250 adjacent to the second electrode 220 may not be in contact with the second electrode 220.

[0051] Thus, in this embodiment, since the adhesive member 250 is not in contact with the second electrode 220, it is possible to prevent the adhesive substance contained in the adhesive member 250 from obstructing the movement path of lithium ions formed between the first electrode 210 and the second electrode 220. At this time, the second electrode 220 may be a positive electrode, and the movement of lithium ions can be determined according to the position of the positive electrode, which is generally smaller in size than the negative electrode. Here, the separation distance (s) between one end portion of the second electrode 220 facing each other and one side surface of the adhesive member 250 is at least 0.5 mm or more, preferably 0.6 mm or more, and more preferably 1 mm or more. The reason is that as one method of forming the adhesive member 250, the line width of the adhesive applied by a dispenser is at the level of 0.4 - 0.6 mm. When such conditions are satisfied, the adhesive member 250 can be coated with the adhesive without causing interference on the positive electrode side. Also, since the adhesive may become a foreign substance, it is necessary to avoid applying too much.

[0052] Further, of the two side surfaces of the adhesive member 250, the opposite side surface to the one side surface facing the one end portion of the second electrode 220 can be arranged side by side with the outer side surface of the electrode assembly 200. In other words, of the two side surfaces of the adhesive member 250, the opposite side surface to the one side surface facing the one end portion of the second electrode 220 does not protrude or sink based on the outer side surface of the electrode assembly 200.

[0053] Thereby, in this embodiment, while maximizing the area of the adhesive member 250, it is possible to more effectively prevent the separation film sheet 230 located above the second electrode 220 and the separation film sheet 230 located below the second electrode 220 from being folded in the process.

[0054] For example, the adhesive member 250 may be made of an adhesive material containing one or more components selected from the group consisting of olefin, acrylate, urethane, ester, amide, vinyl acetate, and rubber-based polymers. However, it is not limited thereto, and any material that can adhere between the electrodes (the first electrode 210 and the second electrode 220) and the separation film sheet 230 can be included in this embodiment.

[0055] Further, it is preferable that the adhesive member 250 is uniformly applied to the tolerance (d) formed between the second electrode 220 and the outer side surface of the electrode assembly 200. However, if the adhesive is applied to the entire surface of the tolerance (d) formed between the adhesive member 250 and the outer side surface of the electrode assembly 200, the amount of adhesive applied may be too much. In such a case, the adhesive may flow outside the separation film sheet 230 and contaminate other parts, and the function of producing electricity when the secondary battery is manufactured may not be smooth.

[0056] On the contrary, if the amount of adhesive applied is too small, the electrodes (the first electrode 210 and the second electrode 220) may not be fixed to the separation film sheet 230 while the cell moves, and may be detached from the fixed position. That is, it is preferable that the interval of the regions where the adhesive is applied is not excessively wide.

[0057] Accordingly, in this embodiment, the adhesive member 250 is preferably applied in a spot coating method where it is applied in a dot form or a line coating method where it is applied in a line form to the tolerance (d) formed between the second electrode 220 and the outer surface of the electrode assembly 200. For example, the diameter of the dot in the spot coating method or the width of the line in the line coating method may be 100 μm or more and 800 μm or less. However, the diameter of the dot in the spot coating method or the width of the line in the line coating method is not limited to the above-described range, and can be adjusted to have an appropriate diameter or width as needed.

[0058] Here, the spot coating or line coating of the adhesive member 250 can be performed in a pneumatic type or a piezoelectric type. However, it is not limited thereto, and any method that can apply an adhesive to a local site is included in this embodiment.

[0059] Also, in the electrode assembly 200 of this embodiment, even if the adhesive force between the electrodes (the first electrode 210 and the second electrode 220) and the separator sheet 230 varies depending on the material of the separator sheet 230, since the adhesive member 250 is formed between the second electrode 220 and the outer surface of the electrode assembly 200, it is possible to prevent the electrodes (the first electrode 210 and the second electrode 220) from detaching from their fixed positions and to maintain a high stiffness of the electrode assembly.

[0060] More specifically, the separator sheet 230 can be an inexpensive separator with a relatively low adhesive force. For example, the separator sheet 230 may be a CCS (Ceramic Coated Seperator) separator. However, the separator sheet 230 is not limited thereto, and any separator having an adhesive force similar to that of the CCS separator is included in this embodiment.

[0061] Here, when using such a separation membrane sheet 230, the adhesive force between the electrodes (the first electrode 210 and the second electrode 220) of this embodiment and the separation membrane sheet 230 may be 0 gf / mm or more and 0.05 gf / mm or less. More specifically, the adhesive force between the electrodes (the first electrode 210 and the second electrode 220) and the separation membrane sheet 230 may be 0 gf / mm or more and 0.045 gf / mm or less. For example, the adhesive force between the electrodes (the first electrode 210 and the second electrode 220) and the separation membrane sheet 230 may be 0 gf / mm or more and 0.04 gf / mm or less.

[0062] At this time, in the case of this embodiment, even if the adhesive force between the electrodes (the first electrode 210 and the second electrode 220) and the separation membrane sheet 230 is within the above-described range, an adhesive member 250 is formed between the second electrode 220 and the outer surface of the electrode assembly 200, which complements the adhesive force between the electrodes (the first electrode 210 and the second electrode 220) and the separation membrane sheet 230, prevents the electrodes (the first electrode 210 and the second electrode 220) from detaching from their fixed positions, and can maintain a high stiffness of the electrode assembly. At the same time, this embodiment can use a separation membrane sheet 230 with a relatively low adhesive force, reducing costs, and thus having the advantage of improving economic efficiency.

[0063] In addition, in this embodiment, since there is no need to perform a lamination process as in the prior art through the adhesive member 250, the process defect rate generated by high heat and pressure can be reduced. In addition, since the laminator can be removed, the volume of the manufacturing apparatus can be reduced and the manufacturing process can be simplified.

[0064] FIG. 3 and FIG. 4 are cross-sectional views of an electrode assembly according to another embodiment of the present invention.

[0065] Referring to FIGS. 3 and 4, the electrode assemblies 201 and 202 according to another embodiment of the present invention can be described substantially in the same manner as the above-described electrode assembly 200. Hereinafter, only the parts different from the electrode assembly 200 will be described.

[0066] Referring to FIG. 3, one end of the separation membrane sheet 230 of the electrode assembly 201 according to this embodiment can extend along the outer surface of the electrode assembly 201. More specifically, one end of the separation membrane sheet 230 can wrap around the entire outer surface of the electrode assembly 201. That is, one end of the separation membrane sheet 230 can wrap around both side surfaces and the upper and lower surfaces of the electrode assembly 201.

[0067] As an example, as shown in FIG. 3, the end of the separation membrane sheet 230 that wraps around the outer surface of the electrode assembly 201 may be the end of the separation membrane sheet 230 adjacent to the bottommost surface. As another example, different from FIG. 3, the end of the separation membrane sheet 230 that wraps around the outer surface of the electrode assembly 201 may be the end of the separation membrane sheet 230 adjacent to the upper end of the electrode assembly 201.

[0068] Thereby, in the electrode assembly 201 according to this embodiment, the separation membrane sheet 230 can wrap around the outer surface of the electrode assembly 201 to prevent the first electrode 210 from protruding to the outside. At the same time, the separation membrane sheet 230 that wraps around the outer surface of the electrode assembly 201 can further improve the stiffness of the electrode assembly 201 and effectively prevent the folding of the separation membrane sheet 230. In addition, in this embodiment, since no separate member is required, cost reduction and economic efficiency can be improved.

[0069] Referring to FIG. 4, the electrode assembly 202 according to this embodiment may further include a wrapping member 270 that wraps the outer surface of the electrode assembly 202. More specifically, the wrapping member 270 includes a first wrapping member and a second wrapping member. The first wrapping member can wrap a portion of the outer surface of the electrode assembly 202 where the opposite side of the side surfaces of the first electrode 210 wrapped by the separation membrane sheet 230 is located. The second wrapping member can wrap a portion of the outer surface of the electrode assembly 202 where the opposite side of the side surface facing one end of the second electrode 220 among the two side surfaces of the adhesive member 250 is located. That is, the first wrapping member can wrap one side surface of the electrode assembly 202, and the second wrapping member can wrap the other side surface of the electrode assembly 202.

[0070] In addition, the first wrapping member extends along one of the upper and lower surfaces of the electrode assembly 202, and the second wrapping member can extend along the remaining one of the upper and lower surfaces of the electrode assembly 202. For example, as shown in FIG. 4, one of the wrapping members 270 can extend along one side surface of the electrode assembly 202 and extend to the upper surface of the electrode assembly 202. Also, the other one of the wrapping members 270 can extend along the other side surface of the electrode assembly 202 and extend to the lower surface of the electrode assembly 202. However, it is not limited thereto, and the first wrapping member and the second wrapping member may be integrated with each other.

[0071] As an example, the wrapping member 270 may be a hot-melt film including one or more components selected from the group consisting of olefins, acrylates, urethanes, esters, amides, vinyl acetates, and rubber-based polymers. As another example, the wrapping member 270 may be an adhesive tape. However, it is not limited thereto, and any polymer material having elasticity and adhesive force sufficient to wrap the outer surface of the electrode assembly 202 is included in this embodiment.

[0072] As a result, in the electrode assembly 202 according to this embodiment, the wrapping member 270 can wrap the outer surface of the electrode assembly 201 to prevent the first electrode 210 from protruding to the outside. At the same time, the wrapping member 270 that wraps the outer surface of the electrode assembly 201 can further improve the stiffness of the electrode assembly 201 and effectively prevent the folding of the separation membrane sheet 230.

[0073] FIG. 5 is a cross-sectional view of an electrode assembly according to a comparative example.

[0074] Referring to FIG. 5, in the electrode assembly 20 according to the comparative example, the first electrode 21 and the second electrode 22 are alternately stacked between the separation membranes 23. In the comparative example, due to the tolerance between the separation membrane 23 and the electrodes (the first electrode 21 and the second electrode 22), the end portion of the separation membrane 23 may protrude to the outside with reference to the outer surface of the electrode assembly 20. As a result, the end portion of the separation membrane 23 may be folded during the process, and there is a problem that a short circuit occurs when the separation membrane 23 shrinks at a high temperature.

[0075] In addition, in the case of the comparative example, since no separate adhesive member is formed between the separation membrane 23 and the electrodes (the first electrode 21 and the second electrode 22), in order to prevent the electrodes (the first electrode 210 and the second electrode 220) from detaching from their fixed positions within the electrode assembly 20, a separation membrane 23 having a high adhesive force must be used. However, in the case of the separation membrane 23 having a high adhesive force, as described above, there is a problem that relatively high costs are required, and the economic efficiency decreases as the cost increases.

[0076] In contrast, referring to FIGS. 1 to 4, in the electrode assemblies 200, 201, and 202 according to this embodiment, an adhesive member 250 is formed between the second electrode 220 and the outer surface of the electrode assembly 200. There is an advantage that a separation membrane sheet 230 having a relatively low adhesive force can be used, the electrodes (the first electrode 210 and the second electrode 220) can be prevented from detaching from their fixed positions, and the stiffness of the electrode assembly can be maintained high.

[0077] A battery cell according to another embodiment of the present invention includes the electrode assembly described above. The battery cell may include a battery case (not shown) that houses the electrode assemblies 200, 201, and 202 described above together with an electrolyte. At this time, the electrode assemblies 200, 201, and 202 are manufactured with the final electrode assembly 100 described above and can be received in the battery case (not shown).

[0078] Here, the battery case (not shown) may be a laminate sheet including a resin layer and a metal layer. More specifically, the battery case (not shown) may be made of a laminate sheet and may be composed of an outer resin layer forming the outermost corner, a barrier metal layer for preventing the penetration of substances, and an inner resin layer for sealing.

[0079] Hereinafter, the content of the present invention will be described through more specific examples. However, the following examples are for illustrative purposes of the present invention, and the scope of rights of the present invention is not limited thereto.

[0080] <Comparative Example> An electrode assembly was manufactured by alternately laminating a positive electrode and a negative electrode between separator sheets, where the separator sheets have a zigzag form formed by being folded at least twice. Here, the separator sheet is a CCS (Ceramic Coated Seperator) separator. Also, the size of the electrode assembly is 510 mm × 97 mm.

[0081] <Example> In Comparative Example 1, an electrode assembly was manufactured in the same manner as in Comparative Example 1, except that the length of the positive electrode was smaller than the length of the negative electrode, and an adhesive was applied between the positive electrode and the outer surface of the electrode assembly to form an adhesive member.

[0082] <Experimental Example - Comparison of Stiffness> FIG. 6 is a drawing showing an experimental example for measuring the stiffness of the electrode assembly. As shown in FIG. 6, after placing the center of the electrode assembly 200 on a bar with a thickness of 50 mm, the bending degree (L) of the electrode assembly 200 was measured with reference to the upper end of the bar, and the results are shown in Table 1.

[0083]

Table 1

[0084] <Analysis of Experimental Results> Referring to Table 1, it can be confirmed that when no separate adhesive member is formed as in the comparative example, both ends of the electrode assembly 200 are bent relatively more with reference to the center of the electrode assembly 200. In contrast, when an adhesive member with an adhesive applied between the positive electrode and the outer surface of the electrode assembly is formed as in the example, it can be confirmed that both ends of the electrode assembly 200 are bent relatively less with reference to the center of the electrode assembly 200.

[0085] Thus, even in the case of an electrode assembly including a separator with a relatively low adhesive force as in the example, it can be confirmed that the stiffness of the electrode assembly is improved through the adhesive member with an adhesive applied between the positive electrode and the outer surface of the electrode assembly.

[0086] As described above, the preferred embodiments of the present invention have been described in detail. However, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention defined in the following claims also belong to the scope of the present invention.

Explanation of Reference Numerals

[0087] 100: Final Electrode Assembly 200, 201, 202: Electrode Assembly 210: First Electrode 220: Second Electrode 230: Separation membrane sheet 250: Adhesive member 270: Wrapping member 300: Fixing member 400: Electrode lead 500: Lead film

Claims

1. An electrode assembly in which electrodes and separation membrane sheets are alternately laminated, wherein the electrodes include a first electrode and a second electrode, the separation membrane sheet has a zigzag form formed by being folded at least twice, the length of the second electrode is smaller than the length of the first electrode, an adhesive member is located between one of the two side surfaces of the electrode assembly and the second electrode, the adhesive member is located between the separation membrane sheet in contact with the upper surface of the second electrode and the separation membrane sheet in contact with the lower surface of the second electrode, the second electrode is located between the adhesive member and the separation membrane sheet wrapping one side surface of the second electrode, Electrode assembly.

2. The electrode assembly according to claim 1, wherein the adhesive member is located between the outer surface of the electrode assembly and the opposite side surface of the two side surfaces of the second electrode that is wrapped by the separation membrane sheet.

3. The electrode assembly according to claim 2, wherein the opposite side surfaces of the two side surfaces of the first electrode that are wrapped by the separation membrane sheet and the opposite side surfaces of the two side surfaces of the second electrode that are wrapped by the separation membrane sheet are aligned so as to be biased toward one side surface of the outer surface of the electrode assembly.

4. The electrode assembly according to claim 3, wherein one side surface of the two side surfaces of the adhesive member facing one end portion of the second electrode is spaced apart from the second electrode.

5. The electrode assembly according to claim 4, wherein the opposite side surface of one side surface of the two side surfaces of the adhesive member facing one end portion of the second electrode is arranged side by side with the outer surface of the electrode assembly.

6. The side surfaces of the two side surfaces of the second electrode that are wrapped by the separation membrane sheet are in contact with the separation membrane sheet, The electrode assembly according to claim 3, wherein the side surfaces of the two side surfaces of the first electrode that are wrapped by the separation membrane sheet are in contact with the separation membrane sheet.

7. The electrode assembly according to claim 6, wherein the opposite side surfaces of the two side surfaces of the first electrode that are wrapped by the separation membrane sheet are located on the same vertical line as the outer surface of the electrode assembly.

8. The electrode assembly according to claim 1, wherein the adhesive force between the electrode and the separation membrane sheet is 0 gf / mm or more and 0.05 gf / mm or less.

9. One end of the separation membrane sheet extends along the outer surface of the electrode assembly. The electrode assembly according to claim 1.

10. One end of the separation membrane sheet wraps the entire outer surface of the electrode assembly. The electrode assembly according to claim 9.

11. The electrode assembly according to claim 1, further comprising a wrapping member that wraps the outer surface of the electrode assembly.

12. An electrode assembly in which electrodes and separation membrane sheets are alternately laminated, The electrodes include a first electrode and a second electrode, The separation membrane sheet has a zigzag shape formed by being folded at least twice, The length of the second electrode is smaller than the length of the first electrode, An adhesive member is located between one of the two side surfaces of the electrode assembly and the second electrode, The electrode assembly according to claim 1, further comprising a wrapping member that wraps the outer surface of the electrode assembly. The wrapping member includes a first wrapping member and a second wrapping member, The first wrapping member wraps a portion of the outer surface of the electrode assembly where the opposite side surface of the two side surfaces of the first electrode, which is wrapped by the separation membrane sheet, is located. The second wrapping member wraps a portion of the outer surface of the electrode assembly where the opposite side surface of one of the two side surfaces of the adhesive member, which faces the end portion of the second electrode, is located. The electrode assembly.

13. The first wrapping member extends along one of the upper and lower surfaces of the electrode assembly, The second wrapping member extends along the remaining one of the upper and lower surfaces of the electrode assembly. The electrode assembly according to claim 12.

14. The wrapping member is made of at least one of a hot-melt film and an adhesive tape. The electrode assembly according to claim 11.

15. The wrapping member is made of at least one of a hot-melt film and an adhesive tape. The electrode assembly according to claim 12.

16. A battery cell including the electrode assembly according to any one of claims 1 to 15.

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