Electrode assembly, secondary battery and secondary battery module including the same

Abstract

An electrode assembly and a secondary battery and a secondary battery module including the electrode assembly are provided. The present invention provides an electrode assembly in which a negative electrode, on the surface of a negative current collector coated with a negative electrode active material, a separator, and a positive electrode, on the surface of a positive current collector coated with a positive electrode active material, are repeatedly laminated. The electrode assembly includes: a single cell in which the positive electrode, the separator, the negative electrode, and the separator are sequentially laminated, wherein at least two or more single cells are laminated, and the separator and the negative electrode are further sequentially laminated on the single cell laminated at the uppermost layer, wherein the separator, which is further laminated with the negative electrode, includes an extension extending to one side in length, and the extension surrounds the laminated single cell and the further laminated negative electrode to fix the single cell and the negative electrode.

Description

[0001] This application is a divisional application of the original invention patent application No. 201980005167.8 (International Application No.: PCT / KR2019 / 009040, Application Date: July 22, 2019, Invention Title: Electrode Assembly). Technical Field

[0002] This application claims priority to Korean Patent Application No. 10-2018-0112395, filed on September 19, 2018, the entire contents of which are hereby incorporated by reference.

[0003] The present invention relates to electrode assemblies embedded in secondary batteries, and more specifically, to electrode assemblies secured by extensions extending from a separator or from a current collector to address problems arising in electrode assemblies manufactured in the prior art by lamination and stacking followed by securing with a tape. Background Technology

[0004] Unlike primary batteries, secondary batteries are rechargeable and have a higher potential for compact size and high capacity. Therefore, much research is currently underway on rechargeable batteries. With technological advancements and increasing demand for mobile devices, the need for rechargeable batteries as an energy source is rapidly growing.

[0005] This type of secondary battery is configured such that the electrode assembly is embedded in the battery casing (e.g., a bag, can, etc.). Due to the positive / separator / negative electrode stacking structure, the electrode assembly mounted in the battery casing can be repeatedly charged and discharged.

[0006] Figure 1a This is a side view illustrating a process for manufacturing an electrode assembly by lamination and stacking according to the prior art. Figure 1b This is a side view illustrating a state in which multiple monocells, sequentially laminated with a positive electrode 1, a separator 3, a negative electrode 2, and a separator 3, are then fixed by a band 5. Figure 1c This is a plan view illustrating an electrode assembly in which multiple single cells are laminated and fixed in place.

[0007] Reference Figures 1a to 1c The positive electrode 1, separator 3, and negative electrode 2 are continuously unwound in a laminating and stacking manner, thus being supplied in a wound state. Here, each of the positive electrode 1 and negative electrode 2 is cut to a predetermined size from the separator 3 and moves through the laminating device. Figure 1bAs illustrated, in positive electrode 1 and negative electrode 2, positive electrode active material and negative electrode active material are respectively coated on the two surfaces of positive electrode current collector (the center is shown as part of the diagonal) and negative electrode current collector (the center is shown as part of the X shape).

[0008] While passing through the laminating device, heat and pressure can be applied between the positive electrode 1, the separator 3, and the negative electrode 2 to bond them together. In the bonded state, cutting is performed between adjacent positive electrodes 1 (and adjacent negative electrodes 2) to continuously manufacture a single cell 4 in which the positive electrode 1, the separator 3, the negative electrode 2, and the separator 3 are sequentially laminated downwards.

[0009] The individual cells 4 are laminated in a predetermined number and manufactured into an electrode assembly. When lamination is complete, the individual cells 4 are fixed in place, and the ends of the strips 5 are respectively attached to the uppermost and lowermost individual cells.

[0010] However, in the manner described above, where the single cell 4 is fixed using the strap 5, the ends of the strap 5 extend from the top and bottom layers, resulting in a thickness difference. Additionally, when the strap 5 is attached, a portion of the edge of the negative electrode 2 (which is cut to be relatively larger than the positive electrode for stability) is folded.

[0011] As mentioned above, due to the thickness difference and folding of the negative electrode, the internal resistance increases, thereby accelerating the degradation of the electrode. Summary of the Invention

[0012] Technical issues

[0013] Therefore, the main objective of this invention is to provide an electrode assembly in which laminated single cells are stably fixed to prevent folding of the negative electrode and increase in negative electrode resistance.

[0014] Technical solution

[0015] The present invention, for achieving the above objectives, provides an electrode assembly in which a negative electrode, on the surface of a negative current collector coated with a negative active material, a separator, and a positive electrode, on the surface of a positive current collector coated with a positive active material, are repeatedly laminated. The electrode assembly includes a single cell in which the positive electrode, the separator, the negative electrode, and the separator are sequentially laminated, wherein at least two or more single cells are laminated, and in any of the single cells, an extension extending to one side in length is formed on one of the separators, and the extension of the separator surrounds the single cell laminated as the outermost layer to fix the laminated single cell.

[0016] In an embodiment of the present invention, the single cell including the extension portion may be a single cell laminated at the top or bottom layer, and the separator including the extension portion may be a separator disposed between the positive electrode and the negative electrode in the corresponding single cell.

[0017] Each of the single cells may have a rectangular shape, with a positive terminal extending from the positive electrode and a negative terminal extending from the negative electrode protruding in opposite directions, and the extension of the diaphragm extending in a direction perpendicular to the protruding direction of the positive or negative terminal.

[0018] In the single cell, the positive electrode and the separator can be bonded to each other, and the separator and the negative electrode can be bonded to each other.

[0019] In another embodiment, the single cell including the separator on which the extension is formed may be a single cell laminated on the topmost layer, and the positive electrode may be laminated on the separator on which the extension is formed, wherein the negative electrode may be additionally laminated on the extension when the extension surrounds the entire electrode assembly such that the end of the extension covers the positive electrode disposed on the separator on which the extension is formed.

[0020] In another embodiment, the single cell including the separator on which the extension is formed can be a single cell laminated on the topmost layer, and the positive electrode can be laminated on the separator on which the extension is formed. The separator can be additionally laminated on the positive electrode, and the negative electrode can be additionally laminated on the separator. That is, this structure is similar to the structure according to the above embodiment in that the negative electrode is on the topmost layer, but differs from the structure according to the above embodiment in that a separator is additionally laminated.

[0021] In another embodiment, the single cell including the separator on which the extension is formed can be a single cell laminated at the top layer, and the positive electrode can be laminated on the separator on which the extension is formed, wherein the positive electrode laminated on the separator on which the extension is formed is a one-sided positive electrode with a positive active material coated only on one surface of the positive current collector, and the surface not coated with the positive active material can be set to face upward.

[0022] Furthermore, the present invention can also provide embodiments that can be readily applied to electrode assemblies according to the prior art. In one embodiment, a single cell in which the positive electrode, the separator, the negative electrode, and the separator are sequentially laminated can be provided, wherein at least two or more single cells can be laminated, and the separator and the negative electrode can be sequentially additionally laminated on the single cell laminated on the uppermost layer. Here, the separator, additionally laminated with the negative electrode, may include an extension extending to one side in length, and the extension may surround the laminated single cell and the additionally laminated negative electrode to secure the single cell and the negative electrode.

[0023] As described above, the extension can surround the laminated single cell, and its ends can be joined and secured to predetermined points by applying heat and pressure. Furthermore, the thickness of the extension can differ from the thickness of other portions of the separator that contact the positive or negative electrode. Alternatively, the composition of the extension can differ from the composition of other portions of the separator that contact the positive or negative electrode.

[0024] Furthermore, with the plate inserted into one or both sides of the positive and negative electrodes, the extension of the separator surrounds the single cell such that the plate stands upright in a direction perpendicular to the lamination direction of the positive and negative electrodes.

[0025] Here, the plate can be made of a non-conductive material, and when sealing is performed after the electrode assembly is inserted into the bag, it can prevent the diaphragm from rolling up or being compressed into the narrowed portion of the bag.

[0026] Alternatively, the extension of the separator may surround the single cell twice, and the plate may be positioned between the layer first surrounded by the extension plate and the layer secondly surrounded by the extension, and is made of a thermally conductive metallic material. Here, the plate can serve as a cooling plate to absorb heat generated in the electrodes and reduce the temperature.

[0027] Furthermore, the present invention also provides an electrode assembly in which an extension portion (separate from the positive and negative terminals) can be formed on the extension portion of the current collector rather than the separator constituting the negative and / or positive terminals of the single cell, and the extension portions can be combined with each other to fix the single cell.

[0028] That is, the present invention provides an electrode assembly according to this embodiment, wherein a negative electrode with a negative electrode active material coated on the surface of a negative electrode current collector, a separator, and a positive electrode with a positive electrode active material coated on the surface of a positive electrode current collector are repeatedly laminated. The electrode assembly includes a single cell in which the positive electrode, the separator, the negative electrode, and the separator are sequentially laminated, wherein at least two or more single cells are laminated, wherein each of the two or more single cells includes a positive electrode extension portion extending to one side in length of the positive electrode current collector and a negative electrode extension portion extending to the other side in length of the negative electrode current collector, and the positive electrode extension portion and the negative electrode extension portion are respectively coupled to the positive electrode extension portion and the negative electrode extension portion to fix the laminated single cell.

[0029] Here, the positive electrode extension and the negative electrode extension can be formed separately from the positive electrode connector extending from the positive electrode and the negative electrode connector extending from the negative electrode, respectively.

[0030] Each of the single cells may have a rectangular shape, the positive terminal and the negative terminal may protrude in opposite directions, and the portions of the positive extensions that are joined to each other and the portions of the negative extensions that are joined to each other protrude in opposite directions, that is, in a direction perpendicular to the positive terminal and the negative terminal.

[0031] In another embodiment, the single cell including the positive electrode extension and the negative electrode extension can be any laminated single cell, and in all laminated single cells, the positive electrode extensions can be combined with each other, and the negative electrode extensions can be combined with each other.

[0032] In another embodiment, the positive electrode may be disposed on the top layer of the single cell laminated on the topmost layer, and the separator and the negative electrode may be additionally laminated sequentially on the positive electrode located on the topmost layer.

[0033] In another embodiment, the single cell including the positive electrode extension and the negative electrode extension may be a single cell laminated at the uppermost layer and a single cell laminated at the lowermost layer, and a sub-electrode assembly in which a plurality of single cells are laminated may be inserted between the single cells laminated at the uppermost layer and the single cells laminated at the lowermost layer, wherein in any of the single cells constituting the sub-electrode assembly, an extension extending to one side in length may be formed on one of the separators, and the extension of the separator may surround all the single cells of the sub-electrode assembly so as to be located at the outermost layer of the sub-electrode assembly.

[0034] As described above, in the positive current collector, the thickness of the positive electrode extension portion may be different from the thickness of the portion coated with the positive electrode active material, and in the negative current collector, the thickness of the negative electrode extension portion may be different from the thickness of the portion coated with the negative electrode active material.

[0035] In another embodiment, each of the single cells may have a rectangular shape, with a positive terminal extending from the positive current collector integrated with the positive extension portion, and a negative terminal extending from the negative current collector integrated with the negative extension portion, wherein the positive extension portion may have a shape protruding from both sides of the single cell, and the negative extension portion may have a shape protruding from both sides opposite to the protruding sides of the positive extension portion.

[0036] Here, in the portions where the positive electrode extensions are joined together and in the portions where the negative electrode extensions are joined together, patterned grooves recessed in the direction of lamination of the positive electrode and the negative electrode are formed, respectively.

[0037] Here, the patterned groove formed in the portion where the positive electrode extensions are joined together can be located at a position symmetrical to the patterned groove formed in the portion where the negative electrode extensions are joined together.

[0038] Furthermore, in the single cell, the positive electrode and the separator can be bonded to each other, and the separator and the negative electrode can be bonded to each other.

[0039] Beneficial effects

[0040] With the above-described structure, the laminated single cell can be secured because the extended portion of the separator surrounds it. Therefore, the problem of increased internal resistance and electrode degradation due to differences in the thickness and folding of the negative electrode, as described in the prior art, can be solved without the need for the tape used in the prior art.

[0041] By applying heat and pressure, the extension can be joined at a predetermined point to form a smooth surface.

[0042] The thickness and / or composition of the extended portion of the diaphragm may differ from the thickness and / or composition of other portions in order to improve adhesion and electrolyte impregnation.

[0043] Because the positive electrode and the separator are bonded together, and the separator and the negative electrode are bonded together, the single cell has high stability.

[0044] Additionally, the plate can be selectively inserted into the area surrounded by the extension to prevent damage to the diaphragm when the bag is sealed. When the plate is made of metal, cooling efficiency can be improved by increasing the heat dissipation area.

[0045] Furthermore, as an alternative to the diaphragm, in an electrode assembly in which the positive and negative current collectors can be elongated to be fixed, the strip according to the prior art can be omitted to solve the problem of increased internal resistance and electrode deterioration caused by the thickness difference and folding of the negative electrode. Attached Figure Description

[0046] Figure 1a This is a side view illustrating the process of manufacturing an electrode assembly by lamination and stacking in accordance with the prior art.

[0047] Figure 1b This is a side view illustrating a state in which multiple single cells 4, in which a positive electrode 1, a separator 3, a negative electrode 2, and a separator 3 are sequentially laminated and then fixed by a belt 5.

[0048] Figure 1c This is a plan view illustrating an electrode assembly in which multiple single cells are laminated and fixed in place.

[0049] Figure 2 This is a side view illustrating a single cell where the positive and negative electrodes are respectively laminated on the upper and lower sides of a separator with extended portions to form the cell.

[0050] Figure 3a This is a side view illustrating the state of multiple single-cell laminates according to Embodiment 1, wherein, Figure 2 The single cell is laminated on the top layer, and the separator extension of the top single cell surrounds the entire single cell.

[0051] Figure 3b This is a plan view of the state shown in Figure 3 when viewed from above and looking down.

[0052] Figure 3c This is a side view illustrating the state of multiple single-cell laminates according to Embodiment 3 of the present invention, wherein, Figure 2 The single cell is laminated on the top layer, and the separator extension of the top single cell surrounds the entire single cell. Then the negative electrode is laminated on the separator extension.

[0053] Figure 3d The following is a side view illustrating the following state according to Embodiment 4 of the present invention: a negative electrode is laminated on a separator including an extension portion, and then the extension portion of the separator surrounds the entire single cell to form a structure in which a plurality of single cells 101 excluding the extension portion are laminated, a separator including the extension portion is laminated on the single cell 101, and a separator including the extension portion and the negative electrode is further laminated to form an auxiliary unit.

[0054] Figure 4a This is a side view illustrating the following state according to embodiment 5 of the present invention: a flat plate is inserted into... Figure 3aIn the state of the extension portion surrounding each of the single cells on both sides (i.e., the edge portion is in contact with the bag inside the bag).

[0055] Figure 4b This illustrates the method according to embodiment 6 of the present invention. Figure 3a A side view of a single cell in a state where the extension surrounds the entire cell twice (i.e., the plate is inserted between the overlapping portions of the extension on both sides of the single cell).

[0056] Figure 5a This is a side view illustrating a single cell formed by laminating a positive electrode with a positive electrode extension on one side, a separator, a negative electrode with a negative electrode extension on the other side, and a separator.

[0057] Figure 5b The following side view illustrates the following states according to Embodiment 7 of the present invention: Figure 5a The single-cell laminate, wherein the positive electrode extensions are bonded and fixed to each other on one side, and the negative electrode extensions are bonded and fixed to each other on the other side.

[0058] Figure 5c The following side view illustrates the following states according to Embodiment 8 of the present invention: Figure 5a The single-cell lamination involves bonding and fixing the positive electrode extensions together on one side and bonding and fixing the negative electrode extensions together on the other side, followed by lamination of the separator and the negative electrode on the top layer.

[0059] Figure 5d The following side view illustrates the following states according to Embodiment 9 of the present invention: Figure 5a Single cells are laminated at the top and bottom layers. In these single cells, the positive electrode extensions are bonded and fixed to each other on one side, and the negative electrode extensions are bonded and fixed to each other on the other side. Then, [the cells are] combined with... Figure 3a Sub-electrode assemblies with the same structure as the electrode assemblies are inserted between the single cells located at the top and bottom layers.

[0060] Figure 6 When viewed from above and below Figure 5b The plan view when in the state.

[0061] Figure 7 It is a plan view illustrating the modified shape of the positive and negative electrode extension sections.

[0062] Figure 8 This is a plan view illustrating the state in which patterned grooves are formed in each of the positive electrode extension section and the negative electrode extension section. Detailed Implementation

[0063] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, enabling those skilled in the art to readily implement the inventive concept. However, the present invention may be embodied in different ways and should not be construed as limited to the embodiments set forth herein.

[0064] For the purpose of clearly illustrating the invention, parts that are not relevant to the description have been omitted, and the same or similar parts are indicated by the same reference numerals throughout the specification.

[0065] Furthermore, the terms or words used in this specification and claims should not be construed as having a general meaning or a dictionary-based meaning, but should be interpreted as meanings and concepts that are appropriate for the inventor to define in order to best describe and illustrate the principles of his or her invention and are thus within the scope of this invention.

[0066] This invention relates to an electrode assembly in which a negative electrode 20, a separator 30, and a positive electrode 10 are repeatedly laminated, wherein a negative electrode active material 22 is coated onto the surface of a negative electrode current collector 21 in the negative electrode 20, and a positive electrode active material 12 is coated onto the surface of a positive electrode current collector 11 in the positive electrode 10. Here, the laminated structure is fixed by a separator including an extension disposed in one of the laminated single cells, or by bonding a single cell including an extension to the current collector, thus omitting the straps used for fixing according to the prior art. Hereinafter, embodiments according to the invention will be described with reference to the accompanying drawings.

[0067] [ Fixation via diaphragm ]

[0068] The present invention provides an electrode assembly that can be fixed by a diaphragm 30 including an extension portion 31.

[0069] Figure 2 The following is a side view illustrating the following configuration: a positive electrode 10 and a negative electrode 20 are respectively laminated onto the upper and lower sides of a separator 30 having an extension 31 to form a single cell on which a lower separator 30 (having a conventional size as in the prior art) is laminated. An electrode assembly fixed by the separator 30 is provided with one or more separators 30 including extensions 31.

[0070] (Implementation Method 1)

[0071] Figure 3a This is a side view illustrating the state of lamination of multiple single cells 100 and 101 according to Embodiment 1, wherein, Figure 2 The single cell 100 is laminated on the top layer, and the separator extension 31 of the top single cell 100 surrounds the entire single cell 100 and 101. Figure 3b This is a plan view of Figure 3 when viewed from above and looking down. For example... Figure 3a and Figure 3b As illustrated, the electrode assembly according to Embodiment 1 of the present invention is manufactured by laminating multiple single cells 100 and 101. In the remaining single cells 101, excluding the uppermost single cell 100, a positive electrode 10, a separator 30, a negative electrode 20, and a separator 30 are sequentially laminated from top to bottom, and heat and / or pressure can be applied to each of the contact surfaces to which they are to be bonded. However, the single cell 100 laminated at the uppermost layer is similar to the single cell 101 in that the positive electrode 10, separator 30, negative electrode 20, and separator 30 are sequentially laminated. However, as... Figure 2 As illustrated, the single cell 100 has a structure with an extension 31 having a length extending toward the separator 30.

[0072] When all predetermined numbers of individual cells 100 and 101 are laminated, the extension 31 may have a length sufficient to surround the individual cells 101 and the uppermost individual cell 100. In this embodiment, although the individual cell 100 including the extension 31 is laminated at the uppermost layer when the individual cells 100 are laminated to manufacture an electrode assembly, the individual cells 100 may be laminated at the middle and lower layers.

[0073] As illustrated in Figure 3, after the corresponding single cells (including the single cells with extensions) are laminated on the top layer, the extension 31 surrounds all the laminated single cells 100 and 101 and is located on the outermost layer (so that the extension passes under the bottommost single cell, allowing the end of the extension to be disposed on the topmost single cell). Additionally, as... Figure 3a and Figure 3b As illustrated, the end is attached to the top surface of the uppermost single cell 100 (i.e., the top surface of the positive electrode in the figure) by applying heat and pressure.

[0074] Here, the position of the end of the extension portion 31 can be adjusted according to the thickness of the extension portion 31, so that the height difference on the uppermost surface can be minimized or eliminated. For example, if the thickness of the extension portion 31 is very thin as illustrated in FIG3, the end of the extension portion 31 can preferably be configured to cover only about half of the positive electrode disposed at the uppermost layer, and if there is a considerable height difference corresponding to the thickness of the extension portion 31, the end of the extension portion 31 can preferably be configured to cover the entire coating portion of the positive electrode 10 or the positive electrode active material 12 disposed at the uppermost layer (here, if the single cell is disposed at the lowermost layer, the end of the extension portion 31 is preferably configured to cover the entire coating portion of the negative electrode 20 or the negative electrode active material 22 disposed at the uppermost layer).

[0075] The diaphragm 30 needs to have an appropriate thickness to separate the negative electrode 20 from the positive electrode 10. However, since the extension 31, which is detached from the positive electrode 10 and the negative electrode 20, does not need to have the thickness required by the diaphragm 30, the thickness of the extension 31 can be different from the thickness of the portion of the diaphragm 30 including the extension 31 that is in contact with the positive electrode 10 or the negative electrode 20.

[0076] Alternatively, the extension 31 and the portion of the diaphragm 30 including the extension 31 that contacts the positive electrode 10 or the negative electrode 20 can be manufactured using different components. For example, the extension 31 can have the same thickness as the portion that contacts the positive electrode 10 and the negative electrode 20, but the difference is that additives are added during manufacturing to make it more durable and easier to thermally bond.

[0077] like Figure 3b As illustrated, when viewed from above, the uppermost single cell 100 has a rectangular or square shape. Here, the positive electrode connector 10a extending from the positive electrode 10 and the negative electrode connector 20a extending from the negative electrode 20 protrude in opposite directions to each other, and the extension 31 of the diaphragm 30 extends in a direction perpendicular to the protruding direction of the positive electrode connector 10a or the negative electrode connector 20a (see [reference]). Figure 3a and Figure 3b ).

[0078] (Implementation Method 2)

[0079] In the electrode assembly, it is preferable that no double-sided positive electrode is provided on the outermost layer to minimize the precipitation of lithium (Li) contained in the positive electrode active material. More specifically, a single-sided positive or negative electrode can be provided on the outermost layer to prevent the positive electrode active material from being exposed from the outermost layer. Therefore, in this invention, as embodiment 2, a structure in which a single-sided positive electrode is provided on the outermost layer is provided, and as embodiment 3, a structure in which a negative electrode 20 is provided on the outermost layer is provided.

[0080] That is, as with the electrode assembly according to Embodiment 1, in the electrode assembly according to Embodiment 2, a single cell 100 including a separator 30 on which an extension portion 31 is formed is laminated as the uppermost layer, and a positive electrode 10 is laminated on the separator 30 on which the extension portion 31 is formed. Here, the uppermost positive electrode 10, which is laminated on the separator 30 on which the extension portion 31 is formed, is a one-sided positive electrode on which only one surface of the positive electrode current collector 11 is coated with a positive electrode active material 12. Here, the uppermost positive electrode 10 is configured such that the surface on which the positive electrode active material 12 is not coated faces upward. That is, the electrode assembly according to Embodiment 2 has the same characteristics as the single cell 100. Figure 3a The same structure as the electrode assembly, that is, having a structure that removes the positive electrode active material 12 from the positive electrode current collector 11 laminated on the topmost positive electrode.

[0081] (Implementation Method 3)

[0082] In the electrode assembly according to Embodiment 3 of the present invention, a negative electrode 20 is further laminated in the electrode assembly according to Embodiment 1, such that the negative electrode 20 is disposed on the uppermost layer.

[0083] Right now, Figure 3c This is a side view illustrating the state of a plurality of single cells 100 and 101 laminated according to embodiment 3 of the present invention, wherein, Figure 2 The single cell 100 is laminated on the top layer, and the separator extension 31 of the top single cell 100 surrounds the entire single cell 100 and 101. Then, the negative electrode 20 is further laminated on the separator extension. As illustrated in the figure, the electrode assembly according to embodiment 3 has a structure in which the end of the extension 31 of the separator 30 surrounds and covers the entire uppermost positive electrode 10 in the structure according to embodiment 1. Alternatively, in the third embodiment, if the end of the extension 31 of the separator does not cover the entire uppermost positive electrode 10, the separator 30 can be further laminated on the uppermost positive electrode 10, and then the negative electrode 20 can be laminated on the separator 30.

[0084] (Implementation Method 4)

[0085] Furthermore, as embodiment 4, the present invention provides a structure that can be more easily applied to electrode assemblies (laminated and stacked types) according to the prior art. Figure 3d The side view illustrates the following state: multiple single cells 101 without extensions are laminated, a separator 30 including only extensions is laminated on the single cells 101 (instead of the single cells laminated at the top in embodiments 1, 2 and 3), a negative electrode 20 is further laminated on the separator 30 including extensions 31, and the extensions 31 of the separator 30 surround the entire single cell 101.

[0086] That is, in this embodiment, the diaphragm 30, including the extension portion 31, is additionally laminated onto the topmost layer, rather than on top of the diaphragm 30. Figure 1b In the electrode assembly, the strip 5 is removed, the separator 30 is additionally laminated on the top layer, the negative electrode 20 is laminated on the separator 30, and the extension 31 surrounds the entire single cell 101 and is additionally laminated on the top negative electrode 20 to fix the electrode assembly.

[0087] (Implementation Method 5)

[0088] In addition, the present invention provides the following structures as embodiments 5 and 6: the plate 40 is embedded to make the structure of the electrode assembly more robust, and the electrode assembly is embedded in the bag 50 to prevent the diaphragm 30 from being stuck in the space that narrows when the bag 50 is sealed or damaged.

[0089] That is, in the electrode assembly according to embodiment 5, the plate 40 is additionally installed in the internal space surrounded by the extension 31. Figure 4a This illustrates that the flat plate 40 according to embodiment 5 of the present invention is inserted into a position... Figure 3a The figure shows a side view of each of the single cells in the space enclosed by the extension 31 in the state of (i.e., the edge portion is in contact with the bag 50 inside the bag 50). Referring to the figure, since the plate 40 is fixed to stand vertically in the negative electrode 20 and the positive electrode 10, the plate 40 can support pressure in the vertical direction when the bag 50 is collected, and can be used as a support when surrounded by the extension 31. Since the plate 40 has a plate shape, the plate 40 also has the effect of improving the alignment of the electrode assembly.

[0090] In this embodiment, plate 40 is made of a non-conductive material to prevent short circuits. That is, plate 40 can be configured as an insulating plate. In some cases, aluminum inside the bag is exposed within the seal. Providing such an insulating plate prevents the exposed aluminum from contacting the electrode components.

[0091] (Implementation Method 6)

[0092] In this invention, the electrode assembly according to Embodiment 6 is similar to the electrode assembly of Embodiment 5 in that a plate 40 is provided. However, the plate 40 is made of a thermally conductive metallic material to provide the same function as a cooling plate that absorbs heat generated in the negative electrode 20 and the positive electrode 10 to reduce the temperature. In addition, the plate 40 is arranged separately from the positive electrode 10 and the negative electrode 20 to prevent short circuits caused by the plate 40.

[0093] Figure 4b This illustrates the method according to embodiment 6 of the present invention. Figure 3a The figure shows a side view of the single cell in a state where the extension portion 31 surrounds the entire single cell twice (i.e., the plate 40 is inserted into each of the sides of the single cell between the overlapping portions of the extension portion 31). As illustrated in the figure, the extension portion 31 has a double-enclosing structure, such that the plate 40 is disposed in a space separate from the positive electrode 10 and the negative electrode 20, and the plate is configured to be formed by rotating the extension portion 31.

[0094] In the structure according to this embodiment, the plate 40 can improve the cooling performance of the negative electrode 20 and the positive electrode 10 without increasing the height of the electrode assembly.

[0095] As described above, when the plate 40 is vertically positioned, the positive current collector 11 and the negative current collector 21, each made of a different metallic material, can conduct heat to the plate 40 (because even though the positive current collector 11 and the negative current collector 21 are separated by a diaphragm, they are positioned close together). Therefore, compared to a structure where the plate 40 is laminated in the same direction as the electrodes, heat dissipation efficiency can be improved. That is, in a structure where the plate 40 is laminated in the same direction as the electrodes, only the electrodes located at the upper and lower layers can absorb heat. However, in a structure where the plate 40 is vertically positioned, all ends of the positive current collector 11 and the negative current collector 21 are in contact with each other, thereby improving cooling performance.

[0096] [ Fixed by current collector ]

[0097] In addition, the present invention provides the following structure: the positive current collector 11 and the negative current collector 21 (instead of the extension portion 31 of the diaphragm 30) extend such that the extension portion 11a of the positive current collector 11 is joined and fixed to each other, and the extension portion 21a of the negative current collector 21 is joined and fixed to each other. Figure 5a This is a view illustrating a state in which a positive electrode 10 with a positive electrode extension 11a formed on one side, a separator 30, a negative electrode 20 with a negative electrode extension 21a formed on the other side, and a separator 30 are laminated to form a single cell 200. That is, the electrode assembly having the above structure is characterized in that at least two or more single cells 200 including positive electrode extensions 11a and negative electrode extensions 21a are laminated. Here, the positive electrode extensions 11a are joined and fixed to each other, and the negative electrode extensions 21a are joined and fixed to each other.

[0098] Here, the positive electrode extension 11a and the negative electrode extension 21a can be as follows: Figure 6 The example shown is formed separately from the positive terminal 10a and the negative terminal 20a, or it can be formed as follows: Figure 7 The positive terminal 10a and the negative terminal 20a are formed integrally as shown in the example. Here, even though they are formed integrally, the area of ​​the positive terminal 10a and the negative terminal 20a can be increased (i.e., the bonding area is increased) to provide a more stable fixing force.

[0099] (Implementation Method 7)

[0100] Figure 5b The following side view illustrates the following states according to Embodiment 7 of the present invention: Figure 5a The single-cell laminate, wherein the positive electrode extension 11a is bonded and fixed to each other on one side, and the negative electrode extension 21a is bonded and fixed to each other on the other side.

[0101] As illustrated in the figure, the electrode assembly according to this embodiment is constructed by laminating multiple single cells 200, in which a positive electrode 10, a separator 30, a negative electrode 20, and a separator 30 are sequentially laminated. Furthermore, each of at least the uppermost and lowermost single cells 200 includes a positive electrode extension 11a and a negative electrode extension 21a. In the positive electrode extension 11a, a positive current collector 11 extends lengthwise to one side, and in the negative electrode extension 21a, a negative current collector 21 extends lengthwise to the other side. The positive electrode extension 11a and the negative electrode extension 21a are respectively coupled to the positive electrode extension 11a and the negative electrode extension 21a of the other single cells 200 to fix the laminated single cells. Here, as... Figure 6 As illustrated in this embodiment, the positive electrode extension 11a and the negative electrode extension 21a are formed separately from the positive electrode connector 10a extending from the positive electrode 10 and the negative electrode connector 20a extending from the negative electrode 20, respectively.

[0102] That is, in this embodiment, the single battery 200 has a rectangular shape. Furthermore, the positive electrode connector 10a and the negative electrode connector 20a protrude in opposite directions, and the portions where the positive electrode extension 11a joins with each other and the portions where the negative electrode extension 21a joins with each other protrude in opposite directions. Additionally, the positive electrode connector 10a and the negative electrode connector 20a protrude in directions perpendicular to each other.

[0103] In this embodiment, at least the uppermost and lowermost single cells can be single cells in which positive electrode extension 11a and negative electrode extension 21a are formed. That is, positive electrode extension 11a and negative electrode extension 21a are formed in all laminated single cells 200. In addition, all positive electrode extensions 11a can be combined with each other, and all negative electrode extensions 21a can be combined with each other.

[0104] The bonding between the positive electrode extensions 11a and between the negative electrode extensions 21a can be performed by welding. Alternatively, laser welding can be performed, but it is preferred to perform ultrasonic welding according to the thickness of the positive electrode current collector 11a and the negative electrode current collector 21a (typically, this is the welding method for welding positive and negative electrode connectors).

[0105] (Implementation Method 8)

[0106] As described above, in this embodiment, for the purpose of minimizing the precipitation of lithium (Li) contained in the positive electrode active material, the separator 30 and the negative electrode 20 are additionally disposed at the uppermost layer so that the arrangement of the double positive electrode is not included at each of the outermost layers.

[0107] Figure 5c This is a side view illustrating the following states: Figure 5aIn the single-cell lamination, the positive electrode extension 11a is bonded and fixed to each other on one side, and the negative electrode extension 21a is bonded and fixed to each other on the other side. Then, the separator 30 and the negative electrode 20 are further laminated on the top layer. As illustrated in the figure, the electrode assembly according to this embodiment has the same structure as the electrode assembly according to embodiment 7, except that a separator 30 and a negative electrode 20 are added on the top layer. That is, in this embodiment, the positive electrode 10 is located on the top layer of the single cell 200 laminated on the top layer, and the separator 30 and the negative electrode 20 are sequentially stacked on the positive electrode 10 located on the top layer.

[0108] For this purpose, an auxiliary unit can be used. An auxiliary unit can be provided in which one of the negative electrodes and one of the separators are combined with each other. Then, the auxiliary unit can also be laminated on the top layer of the laminated single cell 200.

[0109] (Implementation Method 9)

[0110] Furthermore, the present invention provides a structure in which the fixing method performed by the extension portion of the current collector and the fixing method performed by the extension portion of the diaphragm are combined with each other as Embodiment 9. Figure 5d This is a side view illustrating the following states: Figure 5a Single cells 200 are laminated at the top and bottom layers. In the single cells 200 laminated at the top and bottom layers, the positive electrode extensions 11a are joined and fixed to each other on one side, and the negative electrode extensions 21a are joined and fixed to each other on the other side. Then, [the following is a description of a process involving...] Figure 3a Sub-electrode assemblies with the same structure as the electrode assemblies are inserted between the single cells 200 located at the top and bottom layers.

[0111] In this embodiment, the single cell having the positive electrode extension 11a and the negative electrode extension 21a is a single cell 200 laminated at the uppermost layer and a single cell 200 laminated at the lowermost layer. A sub-electrode assembly having multiple single cells laminated together is inserted between the uppermost and lowermost single cells 200. Here, the sub-electrode assembly has the same structure as the electrode assembly according to Embodiment 1.

[0112] That is, in the sub-electrode assembly, an extension 31 extending to one side is formed on the separator 30 laminated in the uppermost single cell, and the extension 31 of the separator 30 surrounds all the single cells of the sub-electrode assembly so as to be located at the outermost layer in the sub-electrode assembly. In this configuration, the positive electrode extension 11a or the negative electrode extension 21a can be prevented from contacting the individual electrodes (positive or negative electrodes) within the electrode assembly. When the positive electrode extension 11a or the negative electrode extension 21a contacts the individual electrodes within the electrode assembly, a short circuit fault may occur. Therefore, the above configuration can prevent short circuits from occurring.

[0113] In the electrode assembly according to embodiments 7 to 9, which is fixed by extensions formed on the current collector, since the same positive extension 11a and negative extension 21a are concentrated to be joined together, the positive extension 11a and negative extension 21a can provide a fixing force that is separate from the fixing force of the corresponding positive terminal 10a and the corresponding negative terminal 20a that are concentrated to be joined together as described above.

[0114] Furthermore, in the above embodiments, the positive current collector 11 and the negative current collector 21 are designed according to the thickness and characteristics of the active materials 12 and 22 to be coated, and the positive current collector 11 and the negative current collector 21 are manufactured to meet the conditions required for the electrode assembly. Therefore, it is difficult to change the thickness. However, the thickness limitation of the uncoated positive electrode extension 11a and negative electrode extension 21a is relatively small.

[0115] Therefore, in this invention, the thicknesses of the positive electrode extension 11a and the negative electrode extension 21a in the positive electrode current collector 11 and the negative electrode current collector 21 can be different from the thicknesses of those portions coated with active materials 12 and 22, respectively. That is, each of the positive electrode extension 11a and the negative electrode extension 21a can have a thin thickness at the bonding portion, or be manufactured to be thinner than the thickness of the portion coated with active material, so as to bend vertically after bonding. On the other hand, each of the positive electrode extension 11a and the negative electrode extension 21a can be manufactured to be thicker than the thickness of the portion coated with active material, so as to more firmly support the movement of the single cell.

[0116] Figure 6 When viewed from above and below Figure 5b A plan view of the state. Figure 7 It is a plan view illustrating the modified shapes of the positive and negative electrode extension sections, and Figure 8 This is a plan view illustrating the state in which patterned grooves are formed in each of the positive electrode extension section and the negative electrode extension section.

[0117] As illustrated in the figure, the single cell 200 according to embodiments 7 to 9 may also have a rectangular or square shape like the single cell 100 according to embodiment 1.

[0118] Here, as Figure 6As illustrated, the positive terminal 10a extending from the positive electrode 10 and the negative terminal 20a extending from the negative electrode 20 protrude in opposite directions, and the portions of the positive extension 11a that connect with each other and the portions of the negative extension 21a that connect with each other protrude in opposite directions. Furthermore, the positive terminal 10a and the negative terminal 20a protrude in directions perpendicular to each other. Like the positive terminal 10a and the negative terminal 20a, since the positive extension 11a and the negative extension 21a are portions extending from the positive current collector 11 and the negative current collector 21 respectively, the positive extension 11a and the negative extension 21a can also serve as terminals through which current flows to the electrode assembly. That is, as alternatives to the positive terminal 10a and the negative terminal 20a, the points for electrical connection to external devices can be the positive extension 11a and the negative extension 21a respectively.

[0119] Furthermore, since the positive terminal 10a and negative terminal 20a can provide the same function as the positive terminal extension 11a and negative terminal extension 21a, the above-mentioned configurations can be integrated into a single unit without separate classification. That is, as... Figure 7 As illustrated, the positive terminal 10a extending from the positive current collector 11 and the positive extension portion 11a are integrally formed, and the negative terminal 20a extending from the negative current collector 21 and the negative extension portion 21a are integrally formed (conversely, either the positive terminal and the positive extension portion and only one of the negative terminal and the negative extension portion may be omitted).

[0120] Here, in order to ensure the fixing force of each single cell 200 (to provide sufficient bonding force), in this embodiment, the positive electrode extension 11a has a shape that protrudes from both sides of the single cell, and the negative electrode extension 21a has a shape that protrudes from both sides opposite to the protruding sides of the positive electrode extension 11a.

[0121] Furthermore, recessed patterned grooves 11b and 21b, extending along the lamination direction of the positive electrode 10 and the negative electrode 20 (i.e., in the thickness direction), are formed in the portions where the positive electrode extensions 11a and 21a interlock. That is, as... Figure 8 As illustrated, multiple patterned grooves 11b and 21b can be formed in the portions where the positive electrode extension 11a and the negative electrode extension 21a intersect. The patterned grooves 11b and 21b can be used as spaces for inserting devices providing additional functions, such as coolant, before the electrode assembly is embedded in the pouch. In this embodiment, the patterned groove 11b formed in the portions where the positive electrode extensions 11a intersect can be positioned symmetrically to the patterned groove 21b formed in the portions where the negative electrode extensions 21a intersect.

[0122] The present invention, having the technical features described above, is configured to fix the laminated single cell by surrounding the laminated single cell with the extension portion 31 of the separator 30, and to fix the single cell by joining the positive electrode extension portions 11a together and the negative electrode extension portions 21a together. Therefore, by omitting the strip according to the prior art, the problems of increased internal resistance and electrode degradation caused by thickness difference and negative electrode folding can be solved.

[0123] By applying heat and pressure, the extension 31 can be joined at a predetermined point to form a smooth surface.

[0124] The thickness and / or composition of the extended portion 31 of the diaphragm can differ from the thickness and / or composition of other portions to improve adhesion and electrolyte impregnation. Furthermore, the thickness of each of the positive electrode extended portion 11a and the negative electrode extended portion 21a can differ from the thickness of each of the other portions (the portions coated with active material), thus the welding performance and size of the welded portions can be varied in various ways as necessary.

[0125] Because the positive electrode and the separator are bonded together, and the separator and the negative electrode are bonded together, the single cell has high stability.

[0126] Additionally, the plate 40 can be selectively inserted into the area surrounded by the extension 31 to improve cooling efficiency and support. Furthermore, since the coolant is selectively inserted into the portions forming the patterned grooves 11b and 21b, cooling efficiency can be improved.

[0127] Furthermore, because an electrode assembly with the above-mentioned technical features is provided, the present invention can also provide a secondary battery in which the electrode assembly according to the present invention is embedded in a bag, and a secondary battery module in which multiple secondary batteries are electrically connected to each other.

[0128] Although embodiments of the invention have been described with reference to specific embodiments, those skilled in the art will understand that various changes and modifications can be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. An electrode assembly comprising: a negative electrode having a negative active material coated on the surface of a negative current collector, a separator, and a positive electrode having a positive active material coated on the surface of a positive current collector, the electrode assembly comprising: A single cell in which the positive electrode, the separator, the negative electrode, and the separator are sequentially laminated. The process involves laminating at least two or more individual cells, and further sequentially laminating the separator and the negative electrode onto the individual cell at the top layer. The separator, which is additionally laminated with the negative electrode, includes an extension portion extending to one side in length, and The extension surrounds the laminated single cell and the additionally laminated negative electrode to secure the single cell and the negative electrode. The thickness of the extended portion differs from the thickness of other portions of the diaphragm that contact the positive or negative electrode. In this configuration, with the plate inserted into one or both sides of the positive and negative electrodes, such that the plate is upright in the direction of lamination of the positive and negative electrodes, the extension portion of the separator surrounds the single cell.

2. The electrode assembly according to claim 1, wherein, The extension surrounds the laminated single cell, and By applying heat and pressure, the ends of the extension are joined and fixed to a predetermined point.

3. The electrode assembly according to claim 1, wherein, The composition of the extended portion is different from the composition of other parts of the diaphragm that are in contact with the positive or negative electrode.

4. The electrode assembly according to claim 1, wherein, The plate is made of a non-conductive material.

5. The electrode assembly according to claim 1, wherein, The extended portion of the diaphragm surrounds the single cell twice, and The plate is positioned between the layer first surrounded by the extension and the layer second surrounded by the extension, and is made of a thermally conductive metallic material.

6. A secondary battery in which the electrode assembly according to any one of claims 1-5 is embedded in a pouch.

7. A secondary battery module, the secondary battery module being mounted such that a plurality of secondary batteries according to claim 6 are electrically connected to each other.

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