Stacked cell and method for manufacturing stacked cell

Abstract

The present invention discloses a stack cell. The stack cell of the present invention includes an electrode stack; at least one fixing tape wrapped around the electrode stack to secure the electrode stack; and a step-leveling tape attached to the edge of the upper surface of the electrode stack to eliminate the step between the fixing tape and the upper surface of the electrode stack.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0057695 filed on May 3, 2023, and the contents disclosed in the documents of the Korean Patent Application are all incorporated herein by reference.

[0002] The present invention relates to a stacked cell and a method for manufacturing the same, which can prevent damage or breakage of the stacked cell and prevent precipitation of lithium.

Background Art

[0003] Generally, a secondary battery includes a positive electrode, a negative electrode, and an electrolyte, and generates electrical energy by using a chemical reaction. The use of secondary batteries is gradually increasing due to their advantage of being rechargeable. Among these secondary batteries, lithium secondary batteries are widely used as power sources for electronic communication devices or as drive sources for high-output hybrid vehicles, electric vehicles, etc., because of their high energy density per unit weight.

[0004] From the aspect of the shape of these secondary batteries, the demand for prismatic secondary batteries and pouch-type secondary batteries that can be applied to products such as mobile phones due to their thinness and thickness is increasing. From the aspect of the materials of secondary batteries, the demand for lithium secondary batteries such as lithium-ion batteries and lithium-ion polymer batteries with high energy density, stable discharge voltage, and output is increasing.

[0005] Electrode stacks for secondary batteries are manufactured by lamination and stacking processes. In the lamination process, electrodes heated to a high temperature and a separation membrane are pressed together under strong pressure to produce monocells. In the stacking process, after stacking multiple monocells, halfcells are stacked on top of the uppermost monocell to form an electrode stack. At this time, because the stacked monocells and halfcells are very thin, both sides of multiple monocells and halfcells bend, causing them to lift or open. When taping both sides of an electrode stack that has bent and lifted, it is difficult to firmly tape the electrode stack. Furthermore, if a taping device taps the electrode stack while both sides are lifted or open, the outermost monocell or halfcell may crack, the separation membrane may fold, or wrinkles may form in the separation membrane.

[0006] To solve the above problem, a jig device pressurizes the edges on both sides of the electrode stack, and a taping device taps the electrode stack with fixing tape. However, because the electrode stack is taped while the edges on both sides of the electrode stack are pressed by the jig device, it was not possible to tape the edges on both sides of the electrode stack. As a result, a step equal to the thickness of the fixing tape is formed on the upper edge of the half cell.

[0007] Next, the pressure press applies pressure to the taped electrode stack, tightly sealing the electrodes and the separation membrane, thereby eliminating the space between the electrodes and the separation membrane of the electrode stack. At this time, although the pressure press directly contacts the fixing tape, it maintains a step-like separation from the upper edge of the half-cell, so the pressure of the pressure press is hardly applied to the edges on both sides of the electrode stack. Furthermore, even if the pressure of the pressure press is increased, it is difficult to apply sufficient pressure to the edges on both sides of the electrode stack. As a result, if gaps or spaces occur between the electrodes and the separation membrane at the edges on both sides of the electrode stack, lithium can be deposited in these gaps or spaces. Moreover, if lithium is deposited in a secondary battery, it can cause the secondary battery to explode.

[0008] Furthermore, sliding portions of the active material layer are formed on the edges on both sides of the electrode. These sliding portions are inclined portions that are pushed to both sides of the electrode by the pressure applied to the active material layer by the press roller during the coating process. Since these sliding portions are located on the edges on both sides of the electrode stack, gaps or spaces are likely to occur between the electrode and the separation film in these sliding portions. This significantly increases the possibility of lithium deposition in the sliding portions located on the edges on both sides of the electrode stack. Therefore, a technique is required to apply the pressure of a press to the edges on both sides of the electrode stack.

[0009] The background art of this invention is disclosed in Korean Published Patent Publication No. 2022-0103465 (published on July 22, 2022, title of invention: electrode assembly and secondary battery including the same). [Overview of the project] [Problems that the invention aims to solve]

[0010] The present invention was devised to solve the above-mentioned problems, and aims to provide a stack cell and a method for manufacturing a stack cell in which the same pressing force is applied to the upper surface of the electrode stack when the electrode stack is pressed together.

[0011] The present invention aims to provide a stack cell and a method for manufacturing a stack cell that can prevent the electrode stack from being damaged or broken.

[0012] The present invention aims to provide a stack cell and a method for manufacturing a stack cell, wherein the sliding portions on both sides of the electrode stack can be in close contact with the separation membrane.

[0013] The present invention aims to provide a stack cell and a method for manufacturing a stack cell that can virtually eliminate gaps and spaces between the sliding portion of the active material layer and the separation membrane.

[0014] The present invention aims to provide a stacked cell and a method for manufacturing a stacked cell that can prevent lithium deposition in the stacked cell and eliminate the cause of explosion in secondary batteries.

[0015] The technical problems of the present invention are not limited to the purposes mentioned above. Other purposes and advantages of the present invention not mentioned can be understood from the following description and will be more clearly understood from the embodiments of the present invention. Furthermore, it will be readily understood that the purposes and advantages of the present invention can be achieved by the means and combinations thereof described in the claims. [Means for solving the problem]

[0016] To solve the above-mentioned problems, the stack cell according to the present invention includes: an electrode stack; at least one fixing tape wrapped around the electrode stack to secure the electrode stack; and a step-reducing tape attached to the edge portion of the upper surface of the electrode stack to eliminate the step difference between the fixing tape and the upper surface of the electrode stack.

[0017] The step-eliminating tape may be attached so as to correspond to the sliding portion of the active material layer on the outer casing of the electrode laminate.

[0018] The step-leveling tape may be placed on the edge of the electrode laminate where the tab portion is located.

[0019] The thickness of the step-leveling tape may be the same as the thickness of the fixing tape.

[0020] The width of the step-eliminating tape may be wider than the width of the sliding portion of the electrode stack.

[0021] The end of the negative electrode slide portion in the electrode stack may be positioned further out than the end of the positive electrode slide portion.

[0022] The stacked cell according to the present invention includes an electrode laminate; at least one fixing tape that is wound around the electrode laminate to fix the electrode laminate; a first step-dissolving tape that adheres to an edge portion of the upper surface of the electrode laminate to eliminate a step between the fixing tape and the upper surface of the electrode laminate; and a second step-dissolving tape that adheres to an edge portion of the lower surface of the electrode laminate to eliminate a step between the fixing tape and the lower surface of the electrode laminate.

[0023] The first step-dissolving tape and the second step-dissolving tape may be attached so as to correspond to a sliding portion of an active material layer on the outer contour of the electrode laminate.

[0024] The first step-dissolving tape and the second step-dissolving tape may be arranged at an edge where a tab portion in the electrode laminate is arranged.

[0025] The thicknesses of the first step-dissolving tape and the second step-dissolving tape may be formed to be the same as the thickness of the fixing tape.

[0026] The widths of the first step-dissolving tape and the second step-dissolving tape may be formed to be wider than the width of the sliding portion of the electrode laminate.

[0027] An end portion of a negative electrode sliding portion in the electrode laminate may be arranged outside an end portion of a positive electrode sliding portion.

[0028] The method for manufacturing a stacked cell according to the present invention includes a stacking step of forming an electrode laminate; an adhering step of pressing both sides of the electrode laminate with a pressing jig to adhere them; a fixing step of winding a plurality of fixing tapes around the electrode laminate to fix the electrode laminate; a step-dissolving step of attaching a step-dissolving tape to an edge portion of the electrode laminate to eliminate a step between the fixing tape and the edge portion; and a crimping step of crimping the electrode laminate with a pressing device.

[0029] In the step of eliminating the step, a first step elimination tape can be attached to the edge portion of the upper surface of the electrode laminate.

[0030] The step elimination step may include a step of attaching a first step elimination tape to the edge portion of the upper surface of the electrode laminate and a step of attaching a second step elimination tape to the edge portion of the lower surface of the electrode laminate.

[0031] The step elimination tape may be attached so as to correspond to the slide portion of the active material layer on the outer contour of the separator of the electrode laminate.

[0032] The step elimination tape may be disposed at the edge portion where the tab portion in the electrode laminate is disposed.

[0033] The thickness of the step elimination tape may be formed in the same manner as the thickness of the fixing tape.

[0034] The width of the step elimination tape may be formed wider than the width of the slide portion of the electrode laminate.

[0035] The end portion of the negative electrode slide portion in the electrode laminate may be disposed outside the end portion of the positive electrode slide portion.

Advantages of the Invention

[0036] According to the present invention, since the step elimination tape eliminates the steps on both sides of the upper surface of the electrode laminate, when the pressing device presses the upper surface of the electrode laminate, the same pressing force is applied to the fixing tape and the step elimination tape.

[0037] According to the present invention, since the edge portions on both sides of the electrode laminate and the central portion side are pressed with the same pressing force, it is possible to prevent the electrode laminate from being damaged or broken.

[0038] According to the present invention, since the edge portions on both sides of the electrode laminate are pressed with a sufficient pressing force, the slide portions on both sides of the electrode laminate can be in close contact with the separator.

[0039] According to the present invention, the gaps and spaces between the sliding portion of the active material layer and the separation membrane can be almost completely eliminated or significantly reduced.

[0040] According to the present invention, since gaps and spaces between the active material layer and the separation membrane are removed, the deposition of lithium in the stacked cell can be prevented, thereby eliminating the cause of secondary battery explosion.

[0041] According to the present invention, the step-eliminating tape eliminates the step difference between the upper edge portion and the lower edge portion of the electrode laminate. When the pressurizing device pressurizes the electrode laminate, the same pressurizing force is applied to the fixing tape and the step-eliminating tape.

[0042] The effects described above, as well as the specific effects of the present invention, will be explained and described below in the following descriptions of embodiments for carrying out the invention. [Brief explanation of the drawing]

[0043] [Figure 1] This diagram schematically shows the state in which an active material is coated onto the electrode current collector according to the present invention. [Figure 2] This diagram schematically shows a state in which a sliding portion is formed at the end of the active material coated on the electrode current collector according to the present invention. [Figure 3] This figure schematically shows an electrode stack according to the present invention. [Figure 4] Figure 3 schematically shows a state in which the area of ​​the negative electrode active material in the electrode stack is larger than the area of ​​the positive electrode active material. [Figure 5] Figure 3 schematically shows a state in which the area of ​​the positive electrode active material in the electrode stack is larger than the area of ​​the negative electrode active material. [Figure 6] Figure 3 is a schematic diagram showing the electrode stack being taped with fixing tape. [Figure 7] This diagram schematically shows the state in which the taping device according to the present invention has attached a fixing tape. [Figure 8]Figure 7 is a schematic diagram showing the state in which the taping device taps the electrode stack with fixing tape. [Figure 9] This figure schematically shows the electrode stack according to the present invention in a state where it is taped with fixing tape. [Figure 10] This figure schematically shows a first embodiment of the electrode stack according to the present invention. [Figure 11] Figure 10 is a schematic perspective view showing the state in which the step-leveling tape is attached to the edge of the electrode stack. [Figure 12] Figure 10 is a schematic diagram showing the state in which the electrode stack is pressurized by a pressurizing device. [Figure 13] Figure 10 schematically shows the state in which the pressure device pressurizes the electrode stack with the step-leveling tape attached to the edge of the electrode stack. [Figure 14] This figure schematically shows a second embodiment of the electrode stack according to the present invention. [Figure 15] This is a flowchart illustrating a schematic method for manufacturing an electrode stack according to the present invention. [Modes for carrying out the invention]

[0044] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0045] The present invention is not limited to the embodiments disclosed below, and can be modified in various ways and embodied in various forms that are different from each other. However, these embodiments are provided to complete the disclosure of the present invention and to fully inform those in the ordinary skill of the scope of the invention. Therefore, the present invention should be understood to include not only the embodiments disclosed below, but also any modifications, equivalents, or substitutions that fall within the technical spirit and scope of the present invention, as well as the substitution or addition of configurations from one embodiment to another.

[0046] The accompanying drawings are provided to facilitate understanding of the embodiments disclosed herein, and should be understood not to limit the technical concept disclosed herein, but rather to include any modifications, equivalents, or substitutions that fall within the concept and technical scope of the present invention. Components in the drawings may be exaggerated in size or thickness for ease of understanding, but this should not restrict the scope of protection of the present invention.

[0047] The terms used herein are used solely to describe specific examples or embodiments and are not intended to limit the invention. Furthermore, singular expressions include plural expressions unless otherwise clearly indicated in the context. Terms such as "includes" and "contains" in the specification are intended to indicate the existence of features, figures, stages, operations, components, parts, or combinations thereof described herein. In other words, terms such as "includes" and "contains" in the specification should not be understood as preemptively excluding the existence or possibility of adding one or more other features, figures, stages, operations, components, parts, or combinations thereof.

[0048] Terms including ordinal numbers, such as "1st," "2nd," etc., are used to describe various components, but the components themselves are not limited by these terms. These terms are used solely to distinguish one component from another.

[0049] When it is mentioned that one component is “linked” or “connected” to another component, it must be understood that it is directly linked to or may be connected to the other component, but that other components may exist in between. On the other hand, when it is mentioned that one component is “directly linked” or “directly connected” to another component, it must be understood that there are no other components in between.

[0050] When one component is described as being "above" or "below" another component, it must be understood that this refers not only to its position directly above the other component, but also to the possibility of other components existing in between.

[0051] Unless otherwise defined, technical or scientific terms are used herein, and all terms used herein have the same meaning as those generally understood by a person of ordinary skill in the art to which the present invention pertains. Terms that are defined in a commonly used dictionary should be interpreted as having the meaning consistent with their meaning in the context of the relevant art, and not as ideal or overly formal unless expressly defined herein.

[0052] The following describes an apparatus according to an embodiment of the present invention.

[0053] Figure 1 is a schematic diagram showing the state in which an active material is coated onto the electrode current collector according to the present invention; Figure 2 is a schematic diagram showing the state in which a sliding portion is formed on the end of the active material coated onto the electrode current collector according to the present invention; Figure 3 is a schematic diagram showing the electrode stack according to the present invention; Figure 4 is a schematic diagram showing the state in which the area of ​​the negative electrode active material in the electrode stack of Figure 3 is formed to be larger than the area of ​​the positive electrode active material; and Figure 5 is a schematic diagram showing the state in which the area of ​​the positive electrode active material in the electrode stack of Figure 3 is formed to be larger than the area of ​​the negative electrode active material.

[0054] Referring to Figures 1 to 5, the stack cell 100 according to an embodiment of the present invention includes an electrode stack 110, a fixing tape 120, and a step-leveling tape 130.

[0055] The electrode stack 110 is manufactured by a coating process, a notching process, a lamination process, and a stacking process (Lamination and Stacking Process). The electrode stack 110 may also be formed by stacking a plurality of unit cells on a long sheet-like separation membrane with a fixed gap between them, and then winding the separation membrane in one direction (Stacking and Folding Process). Alternatively, the electrode stack 110 may also be formed by stacking a plurality of unit cells on a long sheet-like separation membrane, and then stacking the separation membrane in a zigzag pattern (Zigzag Stacking Process). According to the present invention, electrode stacks of various structures can be applied as long as the fixing tape and the step-leveling tape adhere to the electrode stack. In the following, the case in which the electrode stack 110 is manufactured by the lamination and stacking process will be described as the standard.

[0056] In the coating process, the active material 12 is applied to electrodes 111 and 112. Electrodes 111 and 112 include a positive electrode 112 and a negative electrode 111. The positive electrode 112 is manufactured by applying the positive electrode active material 12 to a positive electrode current collector 11. The positive electrode current collector 11 may contain aluminum. The negative electrode 111 is manufactured by applying the negative electrode active material 12 to a negative electrode current collector 11. The negative electrode current collector 11 may contain copper.

[0057] In the coating process, the active material is applied to the electrode current collector 11. The electrode current collector 11 includes a negative electrode current collector and a positive electrode current collector. When the electrode current collector 11 is transported, the press roller 20 pressurizes the high-temperature active material, causing it to adhere to the electrode current collector 11. As the active material adheres, it flows and spreads thinly on both sides of the electrode current collector 11. At this time, inclined portions of the active material are formed on the edges 118 on both sides of the electrode current collector 11, and these inclined portions of the active material are called sliding parts 13. The height (T: see Figure 2) of the sliding part 13 may gradually decrease as it moves outward from the electrodes 111 and 112. The sliding part 13 is formed by the distance between the electrode current collector 11 and the press roller 20. The sliding part 13 is formed on the edge 118 of the electrode current collector 11 with a width (W) of about several millimeters to several tens of millimeters. The width (W) of the sliding portion 13 can be varied depending on the composition of the active material 12, the viscosity of the active material, the pressure applied by the press roller 20, the thickness of the active material coating layer, and so on. The electrode is manufactured by passing the electrode current collector 11 coated with the active material 12 through a drying process. The electrode is formed with a coated portion coated with the active material and a plain portion where the active material is not coated. The plain portion is formed on the edge portions 118 on both sides of the electrode.

[0058] The electrodes 111 and 112 are then transferred to a notching process. In the notching process, a notching device cuts the plain portion of the electrodes 111 and 112 at regular intervals to form tab portions 117. The tab portions 117 are arranged at regular intervals along the length of the electrodes 111 and 112. The tab portions 117 may have a constant width and length. After the tab portions 117 are formed on the electrodes 111 and 112, they are wound onto a rewinder and then transferred to a lamination process.

[0059] In the lamination process, battery cells are manufactured. Battery cells can be classified into mono-cells, bi-cells, full-cells, and half-cells. A mono-cell 115 has a structure in which a separator membrane 113, a negative electrode 111, another separator membrane 113, and a positive electrode 112 are sequentially laminated. A bi-cell has a structure in which electrodes of the same polarity are laminated on both sides of the outermost layer. A full-cell has a structure in which electrodes of different polarities are laminated on both sides of the outermost layer. A half-cell 116 has a structure in which a separator membrane 113, a negative electrode 111, and another separator membrane 113 are laminated. In the following explanation, the case in which the electrode laminate 110 is laminated with mono-cells 115 and half-cells 116 will be used as the basis. The battery cells are then transferred to the stacking process. Mono-cells 115 and half-cells 116 are transferred to the stacking process.

[0060] Multiple monocells 115 are stacked, and a halfcell 116 is stacked on the topmost monocell 115. The multiple monocells 115 and halfcells 116 constitute an electrode stack 110. Monocells 115 are placed in the bottom layer of the electrode stack 110, and halfcells 116 are placed in the top layer of the electrode stack 110.

[0061] In the electrode stack 110, the negative electrode active material 12 and the positive electrode active material 12 are attached to both sides of the separation membrane 113. At this time, the area of ​​the negative electrode active material 12 of the negative electrode 111 that is in contact with the separation membrane 113 is formed to be even larger than the area of ​​the positive electrode active material 12 of the positive electrode 112 (see Figure 4). In addition, the sliding portion 13 of the negative electrode active material 12 extends outward from the sliding portion of the positive electrode active material 12. This prevents the deposition of lithium in the monocell 115.

[0062] If the area of ​​the negative electrode active material 12 of the negative electrode 111 in contact with the separation membrane 113 is even smaller than the area of ​​the positive electrode active material 12 of the positive electrode 112 (see Figure 5), lithium may precipitate in the monocell 115, which could cause the battery cell to explode.

[0063] Next, we will describe a stack cell according to the first embodiment of the present invention.

[0064] Figure 6 is a schematic diagram showing the electrode stack in Figure 3 being taped with fixing tape, Figure 7 is a schematic diagram showing the taping device according to the present invention adsorbing the fixing tape, Figure 8 is a schematic diagram showing the taping device in Figure 7 taping the electrode stack with fixing tape, and Figure 9 is a schematic diagram showing the electrode stack according to the present invention being taped with fixing tape.

[0065] Referring to Figures 6 to 9, the stack cell 100 includes an electrode stack 110, at least one fixing tape 120, and a step-leveling tape 130.

[0066] The electrode stack 110 is transferred to the taping device 30. The taping device 30 includes a mounting base 31, a pressure jig 32, and a taping module 35. A mounting surface is formed on the upper surface of the mounting base 31 so as to support the electrode stack 110. The pressure jig 32 is installed above the mounting base 31 so as to be able to move up and down.

[0067] The taping module 35 includes a suction body 36, a plurality of taping levers 38, and a plurality of taping rollers 39. The suction body 36 includes a suction part 37 for adsorbing the fixing tape 120. The suction body 36 is movably mounted on the mounting base 31. The taping levers 38 are positioned above and below the suction body 36 and are mounted to reciprocate in the section between the mounting bases 31. The taping rollers 39 are mounted on the ends of the taping levers 38.

[0068] When the pressure jig 32 applies pressure to the edges 118 on both sides of the electrode stack 110, the suction body 36 adsorbs the fixing tape 120. Next, the suction body 36 and the taping lever 38 are moved toward the electrode stack 110 and stop at the taping position. At this time, the suction body 36 corresponds to one side in the width direction of the electrode stack 110, and the pair of taping lever 38 are positioned above and below the suction body 36. The taping roller 39 also contacts the upper and lower surfaces of the suction body 36, respectively. When the taping lever 38 are moved toward the upper and lower sides of the electrode stack 110, the taping roller 39 press the fixing tape 120 tightly against the upper and lower surfaces of the electrode stack 110. With the pressure jig 32 pressing and securing both sides of the electrode stack 110, the taping module 35 adheres the fixing tape 120 to the electrode stack 110. This prevents damage or cracking of the upper portion of the electrode stack 110, such as the outermost monocell 115 and halfcell 116. It also prevents the separation membrane 113, which is stacked on the outermost edge of the electrode stack 110, from folding, thus preventing wrinkles from forming in the separation membrane 113.

[0069] At least one fixing tape 120 may be attached between the edges 118 on both sides of the electrode stack 110. The fixing tape 120 is wrapped around the electrode stack 110 to fix the multiple monocells 115 and halfcells 116. Although Figure 9 shows a configuration in which three fixing tapes 120 are attached to the electrode stack 110, the number of fixing tapes 120 attached can be varied depending on the length and stacking height of the electrode stack 110.

[0070] Furthermore, the fixing tape 120 may be made of a porous material that allows lithium ions to pass through. This prevents a decrease in the charging and discharging performance of the secondary battery due to lithium ions passing through the fixing tape 120 during charging and discharging of the secondary battery.

[0071] Figure 10 is a schematic diagram showing a first embodiment of the electrode stack according to the present invention, Figure 11 is a schematic perspective view showing the electrode stack in Figure 10 with step-leveling tape attached to the edge, Figure 12 is a schematic diagram showing the electrode stack in Figure 10 being pressurized by a pressurizing device, and Figure 13 is a schematic diagram showing the electrode stack in Figure 10 with step-leveling tape attached to the edge and the pressurizing device pressurizing the electrode stack.

[0072] Referring to Figures 10 to 13, a step is formed on both sides of the upper surface of the electrode stack 110 by the thickness (H1) of the fixing tape 120. The fixing tape 120 protrudes above the upper surface of the half cell 116 by its thickness (H1). The fixing tape 120 has a width of approximately 30 mm. At this time, the step is formed on the edges 118 on both sides of the upper surface of the half cell 116, which is stacked on the uppermost layer of the electrode stack 110.

[0073] The step-leveling tapes 130 adhere to the edges 118 on the upper surface of the electrode stack 110, respectively, to eliminate the step between the fixing tape 120 and the upper surface of the electrode stack 110. The step-leveling tapes 130 may be made of the same material as the fixing tape 120. Alternatively, the step-leveling tapes 130 may be the same tape as the fixing tape 120, differing only in their attachment positions. Of course, the step-leveling tapes 130 may also be made of a different material than the fixing tape 120.

[0074] Furthermore, the step-leveling tape 130 may be made of a porous material that allows lithium ions to pass through. This prevents a decrease in the charge and discharge performance of the secondary battery due to lithium ions passing through the step-leveling tape during charging and discharging.

[0075] As the step-leveling tape 130 eliminates the step difference on both sides of the upper surface of the electrode stack 110, the pressurizing device 40 pressurizes the upper surface of the electrode stack 110, applying the same pressure to both the fixing tape 120 and the step-leveling tape 130. This ensures that the edges 118 on both sides of the electrode stack 110 are pressurized with sufficient pressure, allowing the sliding portions 13 on both sides of the electrode stack 110 to adhere closely to the separation membrane 113. Furthermore, the gaps and spaces between the sliding portions 13 of the active material 12 and the separation membrane 113 can be almost completely eliminated or significantly reduced. By eliminating the gaps and spaces between the active material 12 and the separation membrane 113, lithium deposition in the stack cell 100 can be prevented, thus eliminating the cause of secondary battery explosion.

[0076] The step-leveling tape 130 adheres to the outer casing of the electrode stack 110 so as to correspond to the sliding portion 13 of the active material 12. For example, if the electrode stack 110 consists of multiple monocells 115 and halfcells 116, the step-leveling tape 130 adheres to the outer casing of the monocells 115 so as to correspond to the sliding portion 13 of the active material 12. This allows the step-leveling tape 130 to sufficiently transmit pressure to the entire sliding portion 13 when the pressurizing device 40 pressurizes the upper surface of the electrode stack 110. The pressure applied to the sliding portion 13 via the step-leveling tape 130 can increase the adhesion area between the sliding portion 13 and the separation membrane 113. Furthermore, by pressurizing the sliding portion 13 with sufficient pressure, the sliding portion 13 can adhere to the separation membrane 113 in a flattened, compressed state.

[0077] The step-leveling tape 130 is positioned on the edge of the electrode stack 110 where the tab portion 117 is located. In this case, the tab portion 117 and the step-leveling tape 130 are positioned on both sides of the electrode stack 110 in the longitudinal direction.

[0078] The thickness (H1) of the leveling tape 130 is formed to be the same as the thickness (H1) of the fixing tape 120. The upper surface of the leveling tape 130 and the upper surface of the fixing tape 120 are on the same plane. As a result, the pressurizing force of the pressurizing device 40 is applied uniformly to the leveling tape 130 and the fixing tape 120, so that the sliding portion 13 of the active material 12 and the portion of the active material 12 inside it are pressurized with the same pressure. In addition, since a uniform pressure is applied to the electrode stack 110 as a whole, it is possible to prevent the electrode stack 110 from being damaged or broken. In particular, it is possible to prevent damage to the half cell 116 located in the uppermost layer of the electrode stack 110.

[0079] The width of the step-leveling tape 130 is wider than the width (W: see Figure 2) of the sliding portion 13 of the electrode stack 110. This allows the step-leveling tape 130 to sufficiently transmit the pressure to the entire sliding portion 13 when the pressurizing device 40 pressurizes the upper surface of the electrode stack 110. In addition, the adhesion area between the sliding portion 13 and the separation membrane 113 may be increased.

[0080] The end of the negative electrode slide portion 13 in the electrode stack 110 is positioned outside the end of the positive electrode slide portion 13 (see Figure 4). As a result, the area of ​​the negative electrode active material 12 is formed to be larger than the area of ​​the positive electrode active material 12, thereby preventing lithium deposition in the secondary battery.

[0081] Next, a stack cell according to a second embodiment of the present invention will be described. In the second embodiment, except for the step-leveling tape, it is substantially the same as in the first embodiment, so the same components will be denoted by the same reference numerals and their descriptions will be omitted.

[0082] Figure 14 is a schematic diagram showing a second embodiment of the electrode stack according to the present invention.

[0083] Referring to Figure 14, the stack cell 100 includes an electrode stack 110, at least one fixing tape 120, a first step-leveling tape 131, and a second step-leveling tape 132.

[0084] At least one fixing tape 120 may be attached between the edges 118 on both sides of the electrode stack 110. The fixing tape 120 is wrapped around the electrode stack 110 to fix the multiple monocells 115 and halfcells 116. Although Figure 14 shows a configuration in which three fixing tapes 120 are attached to the electrode stack 110, the number of fixing tapes 120 attached can be varied depending on the length and stacking height of the electrode stack 110.

[0085] Steps are formed on the upper and lower surfaces of the electrode stack 110 by the thickness (H1, H2) of the fixing tape 120. The fixing tape 120 protrudes above the upper surface of the electrode stack 110 by its thickness (H1), and the fixing tape 120 protrudes below the lower surface of the electrode stack 110, for example, below the lower surface of the bottommost monocell 115, by its thickness (H2). The fixing tape 120 has a width of about 30 mm. At this time, the steps are formed on the edges 118 on both sides of the halfcell 116 stacked on the uppermost layer of the electrode stack 110, and on the edges 118 on both sides of the bottommost monocell 115.

[0086] The first step-leveling tape 131 adheres to the upper surface edges 118 located on both sides of the upper surface of the electrode stack 110, eliminating the step between the fixing tape 120 and the upper surface of the electrode stack 110. When the pressurizing device 40 pressurizes the upper surface of the electrode stack 110 so that the first step-leveling tape 131 eliminates the step on the upper surface, the same pressurizing force is applied to the fixing tape 120 and the first step-leveling tape 131. As a result, the upper surface edges 118 on both sides of the electrode stack 110 are pressurized with sufficient pressure, so that the sliding portions 13 on both sides of the electrode stack 110 can adhere closely to the separation membrane 113. Furthermore, the gaps and spaces between the sliding portions 13 of the active material 12 and the separation membrane 113 can be almost completely eliminated or significantly reduced. By eliminating the gaps and spaces between the active material 12 and the separation membrane 113, the deposition of lithium in the stack cell 100 can be prevented, and the cause of secondary battery explosion can be eliminated.

[0087] The second step-leveling tape 132 adheres to the edges 118 on the lower surface of the electrode stack 110, respectively, eliminating the step between the fixing tape 120 and the lower surface of the electrode stack 110. When the pressurizing device 40 pressurizes the upper surface of the electrode stack 110 so that the second step-leveling tape 132 eliminates the step on the lower surface, the same reaction force is applied to the fixing tape 120 and the second step-leveling tape 132. As a result, the edges 118 on the lower surface of both sides of the electrode stack 110 are pressurized with sufficient pressure, so that the sliding parts 13 on both sides of the electrode stack 110 can adhere closely to the separation membrane 113. Furthermore, the gaps and spaces between the sliding parts 13 of the active material 12 and the separation membrane 113 can be almost completely eliminated or significantly reduced. By eliminating the gaps and spaces between the active material 12 and the separation membrane 113, the deposition of lithium in the stack cell 100 can be prevented, and the cause of secondary battery explosion can be eliminated.

[0088] The first step-leveling tape 131 and the second step-leveling tape 132 may be made of the same material as the fixing tape 120. Alternatively, the first step-leveling tape 131 and the second step-leveling tape 132 may be the same tape as the fixing tape 120, differing only in their attachment positions. Of course, the first step-leveling tape 131 and the second step-leveling tape 132 may be made of a different material than the fixing tape 120.

[0089] The first leveling tape 131 and the second leveling tape 132 may be made of a porous material that allows lithium ions to pass through. This prevents a decrease in the charge / discharge performance of the secondary battery due to lithium ions passing through the leveling tape during charging and discharging.

[0090] As described above, the first step-leveling tape 131 and the second step-leveling tape 132 eliminate the step between the upper edge portion 118 and the lower edge portion 118 of the electrode laminate 110, thereby increasing the adhesion area between the sliding portion 13 of the electrode laminate 110 and the separation film 113.

[0091] The first step-leveling tape 131 and the second step-leveling tape 132 are attached to the outer casing of the monocell 115 so as to correspond to the sliding portion 13 of the active material 12. As a result, when the pressurizing device 40 pressurizes the upper surface of the electrode stack 110, the first step-leveling tape 131 and the second step-leveling tape 132 can sufficiently transmit the pressurizing force to the entire sliding portion 13. By pressurizing the sliding portion 13 via the step-leveling tape 130, the adhesion area between the sliding portion 13 and the separation membrane 113 can be increased. Furthermore, by pressurizing the sliding portion 13 with sufficient pressure, the sliding portion 13 can adhere to the separation membrane 113 in a flattened, compressed state.

[0092] The first step-leveling tape 131 and the second step-leveling tape 132 are positioned on the edge of the electrode stack 110 where the tab portion 117 is located. At this time, the tab portion 117, the first step-leveling tape 131, and the second step-leveling tape 132 are positioned on both sides of the electrode stack 110 in the longitudinal direction.

[0093] The thickness (H1) of the first step-leveling tape 131 and the second step-leveling tape 132 is formed to be the same as the thickness (H1) of the fixing tape 120. The upper surface of the first step-leveling tape 131 and the upper surface of the fixing tape 120 are on the same plane, and the lower surface of the second step-leveling tape 132 and the lower surface of the fixing tape 120 are on the same plane. As a result, the pressurizing force of the pressurizing device 40 is applied uniformly to the first step-leveling tape 131, the second step-leveling tape 132 and the fixing tape 120, so that the sliding portion 13 of the active material 12 and the portion of the active material 12 inside it can be pressurized with the same pressure.

[0094] The widths of the first step-leveling tape 131 and the second step-leveling tape 132 are formed to be wider than the width (W: see Figure 2) of the sliding portion 13 of the electrode laminate 110. This allows the step-leveling tape 130 to sufficiently transmit the pressure force to the entire sliding portion 13 when the pressurizing device 40 pressurizes the upper surface of the electrode laminate 110. In addition, the adhesion area between the sliding portion 13 and the separation membrane 113 may be increased.

[0095] The end of the negative electrode slide portion 13 in the electrode stack 110 is positioned outside the end of the slide portion 13 of the positive electrode 112. As a result, the area of ​​the negative electrode active material 12 is formed to be larger than the area of ​​the positive electrode active material 12, thereby preventing lithium deposition in the secondary battery.

[0096] The method for manufacturing stack cells according to the present invention, configured as described above, will now be explained.

[0097] Figure 15 is a flowchart illustrating a schematic method for manufacturing an electrode stack according to the present invention.

[0098] Referring to Figure 15, in the manufacturing method of the stack cell 100 according to the present invention, multiple battery cells are stacked to form an electrode stack (S11). For example, a half cell 116 is stacked on top of multiple mono cells 115 to form an electrode stack 110.

[0099] The pressure jig 32 applies pressure to both sides of the electrode stack 110, causing them to adhere tightly (S12). This allows the edges 118 on both sides of the electrode stack 110 to adhere closely together.

[0100] The taping module 35 wraps multiple fixing tapes 120 around the electrode stack 110 to secure it (S13). At this time, the suction body 36 attracts the fixing tapes 120, and the suction body 36 and the taping lever 38 stop at the taping position of the electrode stack 110. As the taping lever 38 moves to the upper and lower sides of the electrode stack 110, the taping roller 39 adheres the fixing tapes 120 to the upper and lower surfaces of the electrode stack 110. The number of fixing tapes 120 attached can be varied depending on the length and stacking height of the electrode stack 110.

[0101] The taping module 35 attaches the step-leveling tape 130 to the edge portion 118 of the electrode stack 110, eliminating the step between the fixing tape 120 and the edge portion 118 (S14). When the pressure device 40 applies pressure to the upper surface of the electrode stack 110 so that the step-leveling tape 130 can eliminate the step, the same pressure is applied to the fixing tape 120 and the step-leveling tape 130.

[0102] The pressurizing device 40 presses the electrode stack 110 to remove any gaps or spaces between the separation membrane 113 and the active material 12 (S15). As a result, the edges 118 on both sides of the electrode stack 110 are pressurized with sufficient pressure, allowing the sliding portions 13 on both sides of the electrode stack 110 to adhere closely to the separation membrane 113. Furthermore, the gaps or spaces between the sliding portions 13 of the active material 12 and the separation membrane 113 can be almost completely removed or significantly reduced.

[0103] In the step-elimination stage (S14), the first step-eliminating tape 131 is attached to the edge portion 118 of the upper surface of the electrode stack 110 to eliminate the step between the fixing tape 120 and the half cell 116. As the first step-eliminating tape 131 eliminates the step, the pressurizing device 40 pressurizes the upper surface of the electrode stack 110, applying the same pressure to both the fixing tape 120 and the first step-eliminating tape 131. As a result, the edge portions 118 on both sides of the electrode stack 110 are pressurized with sufficient pressure, allowing the sliding portions 13 on both sides of the electrode stack 110 to adhere closely to the separation membrane 113. Furthermore, the gaps and spaces between the sliding portions 13 of the active material 12 and the separation membrane 113 can be almost completely eliminated or significantly reduced. By eliminating the gaps and spaces between the active material 12 and the separation membrane 113, lithium deposition in the stack cell 100 can be prevented, eliminating the cause of secondary battery explosion.

[0104] Furthermore, in the step-eliminating stage (S14), the first step-eliminating tape 131 can be attached to the edge portion 118 of the upper surface of the electrode stack 110, and the second step-eliminating tape 132 can be attached to the edge portion 118 of the lower surface of the electrode stack 110. As a result, when the pressurizing device 40 pressurizes the upper surface of the electrode stack 110, the first step-eliminating tape 131 and the second step-eliminating tape 132 can sufficiently transmit the pressurizing force to the entire slide portion 13. By pressurizing the slide portion 13 via the step-eliminating tape 130, the adhesion area between the slide portion 13 and the separation membrane 113 can be increased. In addition, by pressurizing the slide portion 13 with sufficient pressure, the slide portion 13 can adhere to the separation membrane 113 in a flattened, compressed state.

[0105] The step-leveling tape 130 is attached to the outer casing of the monocell 115 so as to correspond to the sliding portion 13 of the active material 12. This allows the step-leveling tape 130 to transmit almost all of the pressure to the entire sliding portion 13 when the pressurizing device 40 pressurizes the upper surface of the electrode stack 110.

[0106] The step-leveling tape 130 is positioned on the edge of the electrode stack 110 where the tab portion 117 is located. In this case, the tab portion 117 and the step-leveling tape 130 are positioned on both sides of the electrode stack 110 in the longitudinal direction.

[0107] The thickness of the step-leveling tape 130 is formed to be the same as the thickness of the fixing tape 120. The upper surface of the step-leveling tape 130 and the upper surface of the fixing tape 120 form the same plane. As a result, the pressure applied by the pressurizing device 40 is applied uniformly to the step-leveling tape 130 and the fixing tape 120, so that the sliding portion 13 of the active material 12 and the active material portion on the central side can be pressurized with the same pressure.

[0108] The width of the step-leveling tape 130 is formed to be wider than the width (W) of the slide portion 13 of the monocell 115. This allows the step-leveling tape 130 to sufficiently transmit the pressure to the entire slide portion 13 when the pressurizing device 40 pressurizes the upper surface of the electrode laminate 110. In addition, the adhesion area between the slide portion 13 and the separation membrane 113 may be increased.

[0109] The end of the negative electrode slide portion 13 in the electrode stack 110 is positioned outside the end of the slide portion 13 of the positive electrode 112. As a result, the area of ​​the negative electrode active material 12 is formed to be larger than the area of ​​the positive electrode active material 12, thereby preventing lithium deposition in the secondary battery.

[0110] As described above, the present invention has been explained with reference to the illustrative drawings, but it is clear that the present invention is not limited to the embodiments and drawings disclosed herein, and that various modifications can be made by a person skilled in the art within the scope of the technical concept of the present invention. Furthermore, even if the effects of the configuration of the present invention are not explicitly described in the embodiments described above, it is natural that the effects that can be predicted by such configuration should also be recognized. [Explanation of Symbols]

[0111] 11 Current collector 12 Active material 13. Slide section 20 Press Rollers 30 Taping device 31 Mounting base 32 Pressurized Jig 35 Taping Modules 36 Suction body part 37 Adsorption part 38 Taping lever section 39 Taping roller section 40 Pressurizing device 100 stack cells 110 Electrode Stack 111 Negative electrode 112 Positive electrode 113 Separation membrane 115 Monocell 116 Half Cell 117 Tab section 118 Edge section 120 Fixing Tape 130 Step-Leveling Tape 131 First step-leveling tape 132 Second leveling tape

Claims

1. Electrode stack; At least one fixing tape that is wrapped around the electrode stack to secure the electrode stack; and Includes a step-reducing tape that adheres to the edges of the upper surface of the electrode stack to eliminate the step difference between the fixing tape and the upper surface of the electrode stack; Stacked cells.

2. The step-eliminating tape is attached so as to correspond to the sliding portion of the active material layer on the outer casing of the electrode laminate. The stack cell according to claim 1.

3. The step-leveling tape is positioned on the edge where the tab portion of the electrode laminate is located. The stack cell according to claim 1.

4. The thickness of the step-leveling tape is formed in the same way as the thickness of the fixing tape. The stack cell according to claim 1.

5. The width of the step-eliminating tape is formed to be wider than the width of the sliding portion of the electrode laminate. The stack cell according to claim 1.

6. The end of the negative electrode slide portion in the electrode stack is positioned outside the end of the positive electrode slide portion. The stack cell according to claim 1.

7. Electrode stack; At least one fixing tape that is wrapped around the electrode stack to secure the electrode stack; A first step-eliminating tape that adheres to the edge portion of the upper surface of the electrode stack to eliminate the step difference between the fixing tape and the upper surface of the electrode stack; and A second step-reducing tape that adheres to the edges of the lower surface of the electrode stack to eliminate the step difference between the fixing tape and the lower surface of the electrode stack; Stacked cell.

8. The first and second leveling tapes are attached to the outer casing of the electrode laminate so as to correspond to the sliding portion of the active material layer. The stack cell according to claim 7.

9. The first step-leveling tape and the second step-leveling tape are arranged on the edge of the electrode laminate where the tab portion is located. The stack cell according to claim 7.

10. The thickness of the first step-leveling tape and the second step-leveling tape are formed in the same way as the thickness of the fixing tape. The stack cell according to claim 7.

11. The widths of the first step-leveling tape and the second step-leveling tape are formed to be wider than the width of the sliding portion of the electrode laminate. The stack cell according to claim 7.

12. The end of the negative electrode slide portion in the electrode stack is positioned outside the end of the positive electrode slide portion. The stack cell according to claim 7.

13. The lamination step of forming the electrode stack, The pressure jig pressurizes both sides of the electrode stack to create a tight seal, A fixing step involves wrapping the electrode stack with multiple fixing tapes to secure the electrode stack, Step-eliminating step involves attaching a step-eliminating tape to the edge portion of the electrode stack to eliminate the step difference between the fixing tape and the edge portion. A pressing step in which the electrode laminate is pressed together with a pressurizing device, including, A method for manufacturing stacked cells.

14. In the step-eliminating step-eliminating step, the first step-eliminating tape is attached to the edge portion of the upper surface of the electrode stack. A method for manufacturing stacked cells according to claim 13.

15. The aforementioned step-leveling stage is, The steps include: attaching a first step-eliminating tape to the edge portion of the upper surface of the electrode stack; The steps include: attaching a second step-leveling tape to the edge portion of the lower surface of the electrode stack; including, A method for manufacturing stacked cells according to claim 13.

16. The step-eliminating tape is attached so as to correspond to the sliding portion of the active material layer on the outer casing of the separation membrane of the electrode laminate. A method for manufacturing stacked cells according to claim 13.

17. The step-eliminating tape is placed on the edge portion where the tab portion is located in the electrode laminate. A method for manufacturing stacked cells according to claim 13.

18. The thickness of the step-leveling tape is formed in the same way as the thickness of the fixing tape. A method for manufacturing stacked cells according to claim 13.

19. The width of the step-eliminating tape is formed to be wider than the width of the sliding portion of the electrode laminate. A method for manufacturing stacked cells according to claim 13.

20. The end of the negative electrode slide portion in the electrode stack is positioned outside the end of the positive electrode slide portion. A method for manufacturing stacked cells according to claim 13.

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