Electrode assembly three-dimensional

Abstract

The present application provides an electrode assembly.

Description

Technical Field

[0001] This application claims priority to Korean Patent Application Nos. 10-2021-0090596, filed on July 9, 2021, 10-2021-0090592, filed on July 9, 2021, 10-2021-0090597, filed on July 9, 2021, and 10-2021-0090598, filed on July 9, 2021, and all of the contents thereof are incorporated herein by reference.

[0002] The present invention relates to an electrode assembly.

Background Art

[0003] Unlike primary batteries, secondary batteries can be recharged and have been widely studied in recent years due to their potential for miniaturization and high capacity. As the technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source has been rapidly increasing.

[0004] Secondary batteries are classified into coin-type batteries, cylindrical batteries, prismatic batteries, and pouch-type batteries according to the shape of the battery case. An electrode assembly installed inside the battery case in a secondary battery is a power generation element capable of charge and discharge, which consists of a laminated structure of electrodes and a separator.

[0005] The electrode assembly can generally be classified into a jelly-roll type, a stack type, and a stack and folding type. In the jelly-roll type, a separator is interposed between sheet-shaped anodes and cathodes coated with active materials, and the overall arrangement is wound up. In the stack type, a number of anodes and cathodes are sequentially laminated with a separator interposed therebetween. In the stack and folding type, the laminated unit cells are wound up with a long separation film.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Korean Patent Application Publication No. 10-2013-0132230 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] First, the present invention provides an electrode assembly that reduces variations in adhesive strength and air permeability across each layer while maintaining appropriate adhesive strength and breathability. [Means for solving the problem]

[0008] An exemplary aspect of the present invention provides an electrode assembly. Such an electrode assembly preferably comprises a plurality of electrodes arranged within a laminate along the lamination axis, with each separation membrane portion located between each electrode in the laminate. The plurality of electrodes includes upper electrodes located at the top of the laminate along the lamination axis, and lower electrodes located at the bottom of the laminate along the lamination axis. The lower electrodes may have a thickness of 80% to 120% of the thickness of the upper electrodes along the lamination axis. Furthermore, the thickness of each electrode within the laminate may be less than 8.3 mm.

[0009] According to some aspects of the present invention, the separation membrane portion may be part of a long separation membrane sheet. Such a long separation membrane sheet may be folded between each separation membrane portion such that the long separation membrane sheet extends between each continuous electrode in the laminate along a winding path that traverses the lamination axis perpendicular to the orthogonal dimension. [Effects of the Invention]

[0010] An electrode assembly according to one embodiment of the present invention can prevent side effects such as lithium (Li) precipitation within the electrode assembly and non-filling of the electrode assembly. The electrode assembly according to one embodiment of the present invention is preferably structurally stable and highly safe to use. [Brief explanation of the drawing]

[0011] [Figure 1] This is a cross-sectional view showing an example of an electrode assembly according to one embodiment of the present invention. [Figure 2] Figure 1 is a cross-sectional view of the electrode assembly, showing the positions of the top, bottom, and middle sections of the electrode assembly. [Figure 3] A top view is shown illustrating an apparatus for manufacturing an electrode assembly according to the present invention. [Figure 4] Figure 3 shows a conceptual front elevation view illustrating the manufacturing apparatus for the electrode assembly. [Figure 5] These photographs show the results of disassembling the electrode assemblies of Comparative Example 1 and Example 1 after charging was complete, and checking for the presence or absence of lithium (Li) precipitate. [Figure 6] These photographs show the results of disassembling the electrode assemblies of Comparative Example 1 and Example 1 after charging was complete, and checking for the presence or absence of lithium (Li) precipitate. [Figure 7] A schematic diagram shows a method for manufacturing an electrode assembly according to the present invention. [Figure 8] A perspective view of the separation membrane heating section of the separation membrane supply section according to one embodiment of the present invention is shown. [Modes for carrying out the invention]

[0012] The object, specific advantages, and novel features of the present invention will become more apparent from the following detailed description in conjunction with the accompanying drawings and embodiments. Note that in this specification, when assigning reference numerals to components in each drawing, the same number is assigned even if the same component is shown in different drawings. Furthermore, the present invention may be embodied in several different forms and is not limited to the embodiments described herein. In describing the present invention, detailed descriptions of related prior art that could unnecessarily obscure the gist of the invention are omitted.

[0013] Figure 1 is a cross-sectional view showing an example of an electrode assembly according to one embodiment of the present invention. Specifically, referring to Figure 1, the electrode assembly 10 according to one embodiment of the present invention includes an electrode laminate in which one or more first electrodes 11 and one or more second electrodes 12 are alternated. Each electrode in the laminate is separated from one another by a separator membrane 14 interposed between them, which may be one long separator membrane 14 folded to repeat along a meandering or zigzag path around each of the consecutive electrodes.

[0014] The electrode assembly 10 is a rechargeable power generation element, and the first electrode may be an anode and the second electrode may be a cathode. However, alternatively, the first electrode may be a cathode and the second electrode may be an anode. The electrode assembly 10 may also be provided in a form in which the outermost layer is surrounded by a separation membrane 14, for example, in a form in which the separation membrane surrounds the assembled electrode assembly 10 as shown in Figure 1. Commonly used materials can be used for the electrode assembly and the separation membrane, including the electrode assembly.

[0015] As further discussed herein, the “top surface” of the electrode assembly 10 refers to the uppermost position in the stacking direction of the electrode assembly 10, designated as reference numeral 2 in Figure 2. Thus, the “top surface air permeability” referred to below relates to the air permeability of the separation membrane 14 in contact with the uppermost electrode in the electrode assembly. Similarly, the “top surface adhesion” referred to below refers to the adhesion between the contact portion of the uppermost electrode in the electrode assembly and the separation membrane 14.

[0016] Furthermore, as discussed herein, the “bottom surface” of the electrode assembly 10 refers to the lowest point in the stacking direction of the electrode assembly 10, designated as reference numeral 3 in Figure 2. Thus, the “bottom surface air permeability” referred to below relates to the air permeability of the separation membrane 14 in contact with the lowest electrode in the electrode assembly. Similarly, the “bottom surface adhesion” referred to below refers to the adhesion between the contact portion of the lowest electrode in the electrode assembly and the separation membrane 14.

[0017] Finally, as discussed herein, the "middle" of the electrode assembly 10 means an intermediate position between the upper and lower surfaces of the electrode assembly 10 in the stacking direction of the electrode assembly 10, as designated by reference numeral 1 in FIG. 2. For example, as in FIG. 2, when the electrode assembly 10 composed of nine electrodes is viewed from the side, the "middle" position is related to the position of the fifth electrode in the stack. Therefore, the "intermediate air permeability" mentioned subsequently relates to the air permeability of the separator film 14 contacting the middle electrode in the electrode assembly. Similarly, the "intermediate adhesive force" mentioned subsequently means the adhesive force between the middle electrode in the electrode assembly and the portion where the separator film 14 abuts.

[0018] Referring to FIGS. 3 and 4, an apparatus 100 for manufacturing an electrode assembly according to an embodiment of the present invention includes a stack table 110; a separator film supply unit 120 for supplying the separator film 14; a first electrode supply unit 130 for supplying the first electrode 11; a second electrode supply unit 140 for supplying the second electrode 12; a first electrode stacking unit 150 for stacking the first electrode 11 on the stack table 110; a second electrode stacking unit 160 for stacking the second electrode 12 on the stack table 110; and a press unit 180 for joining the first electrode 11, the separator film 14, and the second electrode 12 to each other. Further, the apparatus 100 for manufacturing an electrode assembly according to an embodiment of the present invention includes a holding mechanism 170 for fixing the stack (including the first electrode 11, the second electrode 12, and the separator film 14) to the stack table 110 when the stack is assembled.

[0019] The separator film supply unit 120 may have a passage through which the separator film 14 passes toward the stack table 110. In particular, the separator film supply unit 120 may include a separator film heating unit 121 that defines a passage through which the separator film 14 passes toward the stack table 110. As shown in FIG. 8, the separator film heating unit 121 may include a pair of bodies 121a, and the bodies 121a may each be configured in a rectangular block shape, and the bodies 121a may be separated by a distance that defines one of the dimensions of the passage through which the separator film 14 passes. At least one or both of the bodies 121a may further include a separator film heater 121b that transfers heat to the separator film 14 by heating each body 121a.

[0020] The separation membrane supply unit 120 may further include a separation membrane roll 122 around which the separation membrane 14 is wound. Therefore, the separation membrane 14 wound around the separation membrane roll 122 can be gradually unwound, pass through the formed passage, and be supplied to the stack table 110.

[0021] The first electrode supply unit 130 further includes a first electrode roll 133 around which the first electrode 11 is wound in a sheet form, a first cutter 134 that cuts at a constant interval to form the first electrode 11 of a predetermined size when the sheet-like first electrode 11 wound around the first electrode roll 133 is unwound and supplied, a first conveyor belt 135 that moves the first electrode 11 cut by the first cutter 134, and a first electrode supply head 136 that picks up (for example, vacuum-sucks) the first electrode 11 conveyed by the first conveyor belt 135 and attaches it to the first electrode mounting table 131.

[0022] The second electrode supply unit 140 further includes a second electrode roll 143 around which the second electrode 12 is wound in a sheet form, a second cutter 144 that cuts at a constant interval to form the second electrode 12 of a predetermined size when the sheet-like second electrode 12 wound around the second electrode roll 143 is unwound and supplied, a second conveyor belt 145 that moves the second electrode 12 cut by the second cutter 144, and a second electrode supply head 146 that picks up (for example, vacuum-sucks) the second electrode 12 conveyed by the second conveyor belt 145 and attaches it to the second electrode mounting table 141.

[0023] The first electrode stacking unit 150 may be configured to stack the first electrodes 11 on the stacking table 110. The first electrode stacking unit 150 may include a first suction head 151 and a first moving unit 153. The first suction head 151 picks up the first electrodes 11 that have been secured to the first electrode securing table 131 through vacuum suction via one or more vacuum suction ports (not shown) formed on the bottom surface 151b. The first moving unit 153 can then move the first suction head 151 to the stacking table 110 so that the first suction head 151 can stack the first electrodes 11 on the stacking table 110.

[0024] The second electrode stack section 160 may be configured to stack the second electrode 12 on the stack table 110. The second electrode stack section 160 may have the same structure as the first electrode stack section 150 described above. In this case, the second electrode stack section 160 may include a second suction head 161 and a second moving section 163. The second suction head 161 can pick up the second electrode 12 that has been secured to the second electrode attachment table 141 through vacuum suction. The second moving section 163 can then move the second suction head 161 to the stack table 110 so that the second suction head 161 can stack the second electrode 12 on the stack table 110.

[0025] The stack table 110 may be rotatable between positions facing the first electrode stack section 150 and the second electrode stack section 160. The rotation of the stack table 110 allows the holding mechanism 170 to grip the stack being assembled (including the first electrode 11, the second electrode 12, and the separation membrane 14) to fix the stack's position relative to the stack table 110. For example, the holding mechanism 170 can apply downward pressure to the upper surface of the stack towards the stack table 110. The holding mechanism 170 may include, for example, a first holder 171 and a second holder 172 for fixing opposing sides of the first electrode 11 or the second electrode 12. Each of the holders 171 and 172 may be in the form of one or more clamps or other clamping mechanisms.

[0026] As a result, the first electrode 11 is supplied from the first electrode supply unit 130 to the first electrode stack unit 150, and the first electrode stack unit 150 stacks the first electrode 11 on the upper surface of the separation membrane 14 stacked on the stack table 110. The holding mechanism 170 then presses the upper surface of the first electrode 11 to fix its position on the stack table 110. Subsequently, the separation membrane 14 is continuously supplied, rotating the stack table 110 toward the second electrode stack unit 160 to cover the upper surface of the first electrode 11. Meanwhile, the second electrode 12 is supplied from the second electrode supply unit 140, and the second electrode stack unit 160 stacks it on the portion of the separation membrane 14 that covers the upper surface of the first electrode 11. After that, the holding mechanism 170 releases the upper surface of the first electrode 11, and then presses the upper surface of the second electrode 12 to fix the position of the stacked product S relative to the stack table 110. Subsequently, by repeating the process of stacking the first electrode 11 and the second electrode 12, the separation membrane 14 is folded in a zigzag pattern, forming a laminate S located between the continuous first electrode 11 and the second electrode 12. As a result, when the first electrode 11 is supplied from the first electrode supply unit 130 to the first electrode stack unit 150, the first electrode stack unit 150 stacks the first electrode 11 on the upper surface of the separation membrane 14 stacked on the stack table 110. Subsequently, the holding mechanism 170 pressurizes the upper surface of the first electrode 11 to fix its position on the stack table 110. After this, as the stack table 110 rotates toward the second electrode stack unit 160, the separation membrane 14 is continuously supplied so as to cover the upper surface of the first electrode 11. Next, the second electrode 12 supplied from the second electrode supply unit 140 is stacked by the second electrode stack unit 160 on the portion that covers the upper surface of the separation membrane 14. After that, the holding mechanism 170 releases its grip on the upper surface of the first electrode 11 and then pressurizes the upper surface of the second electrode 12 to fix the position of the stacked product S constructed on the stack table 110. Subsequently, by repeating the process of stacking the first electrode 11 and the second electrode 12, the separation membrane 14 can be folded in a zigzag pattern to form a laminate S located between the continuous first and second electrodes 11 and 12.

[0027] After the components of the electrode assembly are stacked, the electrode assembly can undergo one or more heat press operations. In particular, the electrode assembly can be moved to a press section 180 where heated pressure blocks 181 and 182, which are positioned on either side of the stack, move forward toward each other to apply heat and pressure to the stack. As a result, the components of the stack (i.e., electrodes and separator membranes) are thermally bonded to each other, which preferably prevents the completed electrode assembly from coming apart or the components of the electrode assembly from shifting position within the stack.

[0028] The heat press operation applied to the electrode assembly may include a first heat press operation and a second heat press operation. The first heat press operation involves the first electrode and the second electrode being alternately stacked between folded separation membranes to form a laminate, and the laminate being heated and pressurized after being gripped by a gripper. The second heat press operation relates to the operation after the first heat press operation, and involves the laminate being heated and pressurized again after the gripper's grip on the stack is interrupted.

[0029] As shown in Figure 7, the method may first include a stacking step in which a stack of first and second electrodes are alternately stacked on a separation membrane to assemble a stack on a stack table. In this step, the separation membrane is continuously supplied and folded sequentially on top of the pre-stacked layers. One of the first and second electrodes is stacked before the subsequent electrode is stacked. After the stacking step, the stack can be moved away from the stack table. During this time, the separation membrane is pulled, and after the separation membrane has been pulled for a certain length, the separation membrane is cut. Then, a predetermined length of the cut end of the separation membrane is wound around the stack cell. The movement of the stack away from the stack table may preferably be performed by a gripper, which is a movable part that, after gripping the stack on the stack table, can move the stack to a press section 180 where a heat press operation is performed. Then, with the wound stack cell held by the gripper, a first heat press operation is performed. When the first heat press operation is completed, the gripper releases its grip on the stack cell. After removing the gripper, a second heat press operation is performed. Once the second heat press operation is complete, the finished electrode assembly can be completed.

[0030] If the temperature, pressure, and time conditions described herein are not met, the components of the electrode assembly may not adhere properly, causing the electrode assembly to detach or its components to shift within the assembly, especially when the electrode assembly is moved before being inserted into the battery case. Additionally, the separation membrane may become too permeable.

[0031] On the other hand, when the heat pressing operations disclosed herein are performed (including satisfying each pressure, temperature, and time condition), the electrode assembly may be manufactured without the need to individually heat and / or pressurize each stage of the electrode assembly (i.e., heating and / or pressurizing each electrode and separator membrane pair at each stage of the process) to join the components together. Such individual heating and pressurizing at each stage can be detrimental because the effects of heat and / or pressure can accumulate in the lower separator membrane of the laminate, as the already laminated layers subsequently experience the heat and / or pressure applied to them. This can adversely affect such parts of the separator membrane, for example, by reducing porosity (and permeability). In contrast, the present invention allows the entire electrode assembly to be joined simultaneously, and above all, improves uniformity. Thus, it is possible to simultaneously achieve a separator membrane with an appropriate level of adhesion between electrodes and appropriate permeability, while minimizing damage to the unit electrodes.

[0032] In this application, "air permeability" of the electrode assembly means the air permeability of the separation membrane component of the electrode assembly. Furthermore, unless otherwise specified, "air permeability" means the air permeability of all separation membranes, including the electrode assembly, where the air permeability of each separation membrane may be the same or different independently.

[0033] Generally, when the air permeability is less than 40 sec / 100 ml, the lithium ion transfer rate within the separation membrane increases, but there is a problem that the safety of the electrode assembly may rapidly decrease, and the lithium ion transfer rate within the electrode within the electrode assembly may not match the lithium ion transfer rate within the separation membrane. Also, when the air permeability is 120 sec / 100 ml or higher, the lithium ion transfer rate within the separation membrane decreases, which may reduce the efficiency and performance of the charge-discharge cycle.

[0034] Therefore, regardless of its position within the electrode assembly, the separation membrane preferably has a permeability in the range of 40 sec / 100 ml to 120 sec / 100 ml.

[0035] The electrode assembly according to the present invention preferably has higher air permeability than conventional electrode assemblies, thereby improving the safety of the electrode assembly. Specifically, the air permeability of the top surface and the air permeability of the bottom surface of the electrode assembly according to the present invention may be independently 80 sec / 100 ml to 120 sec / 100 ml.

[0036] In the present invention, the method for measuring the permeability of the separation membrane is not particularly limited. Methods further utilized and discussed herein can be measured using methods commonly used in the industry. For example, the permeability was measured using the JIS Gurley measurement method of the Japanese Industrial Standards using a Gurley densimeter (No. 158) manufactured by Toyo Seiki. That is, the permeability of the separation membrane can be obtained by measuring the time it takes for 100 ml (or 100 cc) of air to pass through a 1 square inch of separation membrane at room temperature (i.e., 20°C to 25°C) and a pressure of 0.05 MPa.

[0037] According to one embodiment of the present invention, the intermediate air permeability of the electrode assembly may be in the range of 70 sec / 100 ml to 85 sec / 100 ml, preferably 75 sec / 100 ml to 85 sec / 100 ml.

[0038] According to one embodiment of the present invention, the air permeability of the top surface of the electrode assembly may be in the range of 80 sec / 100 ml to 120 sec / 100 ml, preferably 80 sec / 100 ml to 110 sec / 110 ml, and more preferably 80 sec / 100 ml to 100 sec / 100 ml.

[0039] According to one embodiment of the present invention, the air permeability of the bottom surface of the electrode assembly may be in the range of 80 sec / 100 ml to 120 sec / 100 ml, preferably 80 sec / 100 ml to 110 sec / 110 ml, and more preferably 80 sec / 100 ml to 100 sec / 100 ml.

[0040] According to one embodiment of the present invention, the air permeability at the bottom surface may be less than or equal to the air permeability at the top surface. Also, the air permeability in the middle may be less than or equal to the air permeability at the bottom surface.

[0041] In other words, the magnitudes of the top air permeability, bottom air permeability, and intermediate air permeability can satisfy the following mathematical formula 1.

[0042] [Mathematical formula 1] Top surface ventilation ≥ Bottom surface ventilation ≥ Intermediate ventilation The permeability value in mathematical formula 1 relates to the permeability of the separation membrane within the electrode assembly after the completion of the heating and pressurizing stages.

[0043] According to one embodiment of the present invention, the adhesion force between the separation membrane and the electrode at any position within the electrode assembly (i.e., the top, middle, and bottom surfaces) is 5 gf / 20 mm to 75 gf / 20 mm. (0.049N / 20mm~0.74N / 20mm) It may also be within that range.

[0044] The method for measuring the adhesive strength of the separation membrane in the present invention is not particularly limited. For example, the lower, middle, and upper samples of the electrode assembly may be separated from the laminate. Such samples may include an anode and a separation membrane, or a cathode and a separation membrane. Samples that may be 55 mm wide and 20 mm long are mounted on their respective glass slides with the electrodes positioned on the adhesive surface of the glass slides. Next, each sample was tested by performing a 90° peel test at a speed of 100 mm / min according to the test method explicitly stated in ASTM-D6862. That is, the edge of the separation membrane was pulled 90° upward relative to the glass slide at a speed of 100 mm / min, and the separation membrane was peeled from the electrodes along the width direction of the sample (i.e., peeling from 0 mm to 55 mm).

[0045] According to one embodiment of the present invention, the intermediate adhesive strength of the electrode assembly is 5gf / 20mm to 35gf / 20mm (0.049N / 20mm~0.34N / 20mm) Preferably 5gf / 20mm to 15gf / 20mm (0.029N / 20mm~0.15N / 20mm) That's fine.

[0046] According to one embodiment of the present invention, the adhesive strength of the upper surface of the electrode assembly is 5gf / 20mm to 75gf / 20mm (0.049N / 20mm~0.74N / 20mm) Preferably 6gf / 20mm to 30gf / 20mm (0.059N / 20mm~0.29N / 20mm) That's fine.

[0047] According to one embodiment of the present invention, the adhesive force on the bottom surface of the electrode assembly is 5gf / 20mm to 75gf / 20mm (0.049N / 20mm~0.74N / 20mm) Preferably 9gf / 20mm to 30gf / 20mm (0.088N / 20mm~0.29N / 20mm) That's fine.

[0048] According to one embodiment of the present invention, the bottom adhesive strength and the top adhesive strength may be greater than the intermediate adhesive strength.

[0049] According to one embodiment of the present invention, the adhesive force between the anode and the separation membrane and the adhesive force between the cathode and the separation membrane may be the same or different.

[0050] According to one embodiment of the present invention, the deviation between the intermediate adhesive strength of the electrode assembly and the upper or lower adhesive strength of the electrode assembly is 10 gf / 20 mm to 35 gf / 20 mm. (0.088N / 20mm~0.29N / 20mm) Preferably 10gf / 20mm to 20gf / 20mm (0.098N / 20mm~0.20N / 20mm) That's fine.

[0051] According to one embodiment of the present invention, the deviation between the intermediate air permeability of the electrode assembly and either the top surface air permeability or the bottom surface air permeability of the electrode assembly may be between 3 sec / 100 ml and 15 sec / 100 ml.

[0052] When the aforementioned air permeability and adhesion conditions are met, not only is cleaning and handling of the process easy, but wetting of the separation membrane with the electrolyte is also easy, and an electrode assembly with uniform performance can be manufactured. In addition, side effects such as lithium (Li) deposition of the electrode assembly and the electrode assembly becoming uncharged can be prevented.

[0053] The dielectric strength of the electrode assembly of the present invention may be between 1.56kV and 1.8kV. Since the electrode assembly of the present invention is manufactured by a method of manufacturing an electrode assembly that includes a first heat press and a second heat press, it is possible to obtain both superior adhesive strength and superior dielectric strength simultaneously compared to the case where only the first heat press is performed.

[0054] According to an exemplary embodiment of the present invention, assuming the thickness of the uppermost electrode is 100%, an electrode assembly can be provided in which the thickness of all electrodes is 70% to 120% of the thickness of the uppermost electrode.

[0055] According to an exemplary embodiment of the present invention, the minimum thickness of the electrodes in the electrode assembly may be 8.2 mm or more.

[0056] According to an exemplary embodiment of the present invention, the thickness deviation of the electrodes in the electrode assembly may be 0.013 mm to 0.035 mm.

[0057] When the thickness of the electrodes constituting the electrode assembly is small and the variation in thickness between electrodes is small, the electrode assembly becomes more structurally stable and tends to be more stable during use. As a result of the present invention, it is advantageously possible to manufacture an electrode assembly in which the thickness of the electrodes including the electrode assembly is small and the variation in thickness between electrodes is small.

[0058] While the present invention has been described in detail with specific exemplary embodiments, it is not limited thereto. Within the technical concept of the present invention, various implementations are possible by those with ordinary skill in the art.

[0059] 1) Example 1 Nineteen anode sheets, twenty cathode sheets, and a long separation membrane were supplied to the stack table from the anode supply unit, cathode supply unit, and separation membrane supply unit, respectively.

[0060] More specifically, the anode and cathode were supplied in the form of cuts from anode sheets and cathode sheets, respectively, and the long separation membrane was supplied in the form of a separation membrane sheet. Subsequently, as described above, the anode and cathode were stacked while the supplied separation membrane was folded as the stacking table was rotated. At this time, a holding mechanism was used to press and stabilize the stack on the stacking table to produce a stack containing 39 electrodes.

[0061] After manufacturing the laminate, the laminate was grasped with a gripper, and the first heat press stage was carried out by heating the laminate under a temperature of 70°C and a pressure of 1.91 MPa while applying pressure for 15 seconds.

[0062] Following the first heat press stage, the stack table was heated to a temperature of 70°C as shown in Table 1 below, and a pressure of 2.71 MPa (pressure condition) was applied to the laminate using the press's pressure block for 10 seconds (press time). This second heat press stage was then carried out to produce the electrode assembly of Example 1.

[0063] The above-described provisions regarding the present invention can be applied in the process of manufacturing electrode assemblies.

[0064] 2) Examples 2 and 3 The electrode assemblies of Examples 2 and 3 were manufactured in the same manner as in Example 1, except that the method of Example 1 was performed under the temperature, pressure, and pressing time conditions shown in Table 1 below.

[0065] [Table 1]

[0066] 3) Comparative Examples 1-7 In Example 1, the temperature, pressure, and pressing time for the first heat press stage were carried out as shown in Table 2 below, and the electrode assemblies of Comparative Examples 1 to 7 were manufactured in the same manner as in Example 1, except that the second heat press stage was not carried out.

[0067] [Table 2]

[0068] 4) Experimental Example 1 - Thickness Measurement The maximum, minimum, and average thicknesses of the electrodes constituting the electrode assemblies of Examples 1-3 and Comparative Example 1, as well as the deviation of the electrode thicknesses, were measured using a plate thickness measuring instrument with a load cell.

[0069] Specifically, the thickness at which the upper plate of the flat plate thickness gauge contacts the lower plate was defined as the 0 mm reference. Then, the electrode assembly to be measured was positioned inside the flat plate thickness gauge, and the plate was lowered to 90 kgf. (883N) The pressure was applied for 3 seconds with the force of 90 kgf in Example 1. (883N) The area over which the force was applied was 554.1 cm². 2 That is the case.

[0070] The results are shown in Table 3.

[0071] [Table 3]

[0072] From the results in Table 3 above, it was confirmed that the electrode assembly according to the present invention has a thin electrode thickness and maintains an appropriate level of variation in thickness between electrodes.

[0073] This is determined to be because the electrode assembly of the present invention was manufactured by a manufacturing method that includes a first and second heat pressing step.

[0074] 5) Experimental Example 2 - Evaluation of Air Permeability The air permeability of the electrode assemblies in Examples 1-3 and Comparative Example 1 was evaluated.

[0075] Specifically, after recovering the separation membranes from the electrode assemblies of Examples 1-3 and Comparative Example 1, the separation membranes were cut to prepare separation membrane samples measuring 5 cm x 5 cm (width x length). These separation membrane samples were then washed with acetone.

[0076] Subsequently, the air permeability of Examples 1-3 and Comparative Example 1 was measured using a Toyoseiki Gurley type densometer (No. 158) in accordance with the Japanese Industrial Standard (JIS) Gurley measurement method, by measuring the time it took for 100 ml (or 100 cc) of air to pass through a 1 square inch of the separation membrane at room temperature and a pressure of 0.05 MPa.

[0077] The results are shown in Table 4.

[0078] [Table 4]

[0079] From the results in Table 4 above, it was confirmed that the top and bottom air permeability of the electrode assembly according to the present invention were independently 80 sec / 100 ml or more. Furthermore, it was confirmed that the top and bottom air permeability of the electrode assembly according to the present invention did not exceed 120 sec / 100 ml. In other words, it was confirmed that the electrode assembly according to the present invention has an appropriate level of air permeability for use as an electrode assembly.

[0080] Furthermore, we confirmed that the air permeability deviation between each position was less than 20 sec / 100 ml, and determined that it was substantially uniform.

[0081] On the other hand, in Comparative Example 1, although the positional air permeability deviation was smaller compared to the Example, it was confirmed that the safety was lower than that of the electrode assembly according to the present invention, as the upper and lower surface air permeability were independently less than 80 sec / 100 ml. This is judged to be because only the first heat press operation was performed.

[0082] 6) Experimental Example 3 - Evaluation of Adhesion Strength and Dielectric Strength After disassembling the electrode assemblies of Examples 1-3 and Comparative Examples 1-7, the separated layers were analyzed to measure the adhesion strength of the top, bottom, and intermediate layers. Specifically, the adhesion strength between the separation membrane located at the bottom of the laminate and the cathode was measured. The adhesion strength between the cathode located at the top of the laminate and the separation membrane was also measured. Finally, the adhesion strength between the cathode located at an intermediate position along the lamination direction of the laminate and the separation membrane was measured.

[0083] The cathode and separation membrane sampled from each separated electrode assembly had a width of 55 mm and a length of 20 mm. The sampled samples were bonded to a glass slide so that the electrodes were positioned on the adhesive surface of the slide. After that, the glass slide with the bonded samples was placed in an adhesion strength measuring device, and a 90° peel test was performed at a speed of 100 mm / min according to the test method specified in ASTM-D6862 as described above. That is, the edge of the separation membrane was pulled 90° upward relative to the glass slide at a speed of 100 mm / min, and the separation membrane was peeled from the electrode along the width direction of the sample (i.e., peeling from 0 mm to 55 mm). After discounting for initial meaningful variation, the force (g / mm) applied per sample width while the separation membrane was peeled from the electrode was measured. The value was measured when the separation membrane was pulled perpendicular to the plane on which the glass slide was placed and peeled from the electrode.

[0084] The results are shown in Table 5 below.

[0085] [Table 5]

[0086] Furthermore, the dielectric strength of the electrode assemblies of Examples 1 to 3 and Comparative Example 1 was also measured.

[0087] The results are shown in Table 6 below.

[0088] [Table 6]

[0089] As can be seen from the results in Table 5 above, it was confirmed that the adhesive strength of Examples 1 to 3 was superior to that of Comparative Example 1, which was conducted under the same conditions as the Examples but with only the first heat press performed.

[0090] Furthermore, the results in Table 6 show that the withstand voltage of Examples 1 to 3, which underwent primary heat pressing under higher and higher pressure conditions than the comparative example, was in the range of 1.56kV or higher and 1.8kV or lower.

[0091] In other words, the electrode assembly of the present invention possesses excellent adhesive strength and also has characteristics suitable for use as an electrode assembly, and we were able to confirm that it has a voltage resistance of 1.8kV or less.

[0092] This is determined to be because the electrode assembly of the present invention was manufactured by a manufacturing method that includes a first and second heat pressing step.

[0093] 5) Experimental Example 4 After filling the electrode assemblies of Example 1 and Comparative Example 1, they were disassembled to check for the presence or absence of lithium (Li) deposition. The results are shown in Figures 5 and 6 below.

[0094] In the case of the electrode assembly of Comparative Example 1, it was confirmed that lithium (Li) was deposited during disassembly after the electrode assembly was fully filled, as shown in Figure 5.

[0095] On the other hand, in the case of the electrode assembly of Example 1, it was confirmed that lithium (Li) was not deposited during disassembly after the electrode assembly was fully filled, as shown in Figure 6.

[0096] This is determined to be because the electrode assembly of the present invention was manufactured by a manufacturing method that includes a first and second heat pressing step.

[0097] Through the aforementioned experimental examples 1 to 3, it was confirmed that the electrode assembly according to the present invention has excellent stability and adhesive strength while also possessing appropriate voltage resistance, and that it can prevent side effects such as lithium (Li) deposition within the electrode assembly and incomplete filling of the electrode assembly. [Explanation of symbols]

[0098] 10...electrode assembly 11...1st electrode 11a ···First electrode tab 12...Second electrode 12a ···Second electrode tab 14...Separation membrane 100 ··· Electrode assembly manufacturing equipment 110 ···Stackable Table 120...Separation membrane supply section 121...Separation membrane heating section 121a ···Furrow 121b ···Separation membrane heater 122 ···Separation membrane roll 130...First electrode supply section 131 ···First electrode mounting table 133 ···First electrode roll 134 ···First Cutter 135 ···First conveyor belt 136 ···First electrode supply head 140...Second electrode supply section 141 ···Second electrode mounting table 143 ···Second electrode roll 144 ···Second Cutter 145 ···Second conveyor belt 146 ···Second electrode supply head 150 ···First electrode stack section 151 ···First suction head 151a ···Vacuum Inlet 151b...Bottom surface 153 ···First Mobile Unit 160 ···Second electrode stack section 161 ···Second suction head 163 ···Second Mobile Unit 170 ···Holding mechanism 171 ···First Holder 172 ···Second Holder 180 ···Press Department 181, 182... Pressurized block S ···Laminate

Claims

1. The laminate includes a plurality of electrodes arranged along the stacking axis of the laminate, with each electrode having a separation membrane portion located between them, the plurality of electrodes including an upper electrode located at the top of the laminate along the stacking axis, and the plurality of electrodes including a lower electrode located at the bottom of the laminate along the stacking axis, the lower electrode having a thickness of 80% to 120% of the thickness of the upper electrode along the stacking axis, and the thickness of each electrode in the laminate is less than 8.3 mm. The aforementioned plurality of electrodes include intermediate electrodes among the plurality of electrodes between the upper electrode and the lower electrode along the stacking axis, The upper surface air permeability of the separation membrane in contact with the uppermost electrode in the electrode assembly, and the lower surface air permeability of the separation membrane in contact with the lowest electrode in the electrode assembly, are independently 80 sec / 100 ml to 120 sec / 100 ml, and the intermediate air permeability of the intermediate separation membrane in contact with the intermediate electrode in the electrode assembly is 70 sec / 100 ml to 85 sec / 100 ml, and the magnitudes of the upper surface air permeability, lower surface air permeability and intermediate air permeability satisfy the following mathematical formula 1. Electrode assembly. [Mathematical formula 1] Top surface ventilation > Bottom surface ventilation > Intermediate surface ventilation.

2. The electrode assembly according to claim 1, wherein the separation membrane portion is a portion of a long separation membrane sheet, and the long separation membrane sheet is folded between each separation membrane portion such that it extends between each continuous electrode in the laminate along a winding path that traverses the long separation membrane sheet from front to back along an orthogonal dimension perpendicular to the lamination axis.

3. The electrode assembly according to claim 1, wherein the thickness of the electrodes along the lamination axis within the laminate is 70% to 120% of the thickness of the upper electrode along the lamination axis.

4. The electrode assembly according to claim 3, wherein the minimum thickness of each electrode within the electrode assembly is 8.2 mm.

5. The electrode assembly according to claim 1, wherein the intermediate separation membrane portion is adhered to the intermediate electrode to such an extent that a peeling force of 5 gf / 20 mm to 35 gf / 20 mm (0.049 N / 20 mm to 0.34 N / 20 mm) is required to peel the intermediate separation membrane portion from the intermediate electrode at a speed of 100 mm / min along the stacking axis.

6. The electrode assembly according to claim 1, wherein the separation membrane portion includes an upper separation membrane portion in contact with the upper electrode, and the upper separation membrane portion is adhered to the upper electrode to such an extent that a peeling force of 5 gf / 20 mm to 75 gf / 20 mm (0.049 N / 20 mm to 0.74 N / 20 mm) is required to peel the upper separation membrane portion from the upper electrode at a speed of 100 mm / min along the stacking axis.

7. The electrode assembly according to claim 1, wherein the separation membrane portion includes a lower separation membrane portion in contact with the lower electrode, and the lower separation membrane portion is adhered to the lower electrode to such an extent that a peeling force of 5 gf / 20 mm to 75 gf / 20 mm (0.049 N / 20 mm to 0.74 N / 20 mm) is required to peel the lower separation membrane portion from the lower electrode at a speed of 100 mm / min along the stacking axis.

8. The electrode assembly according to claim 1, wherein the separation membrane portion includes an intermediate separation membrane portion in contact with the intermediate electrode, an upper separation membrane portion in contact with the upper electrode, and a lower separation membrane portion in contact with the lower electrode, the intermediate separation membrane portion is adhered to the intermediate electrode to such an extent that a first peeling force per 20 mm width is required to peel the intermediate separation membrane portion from the intermediate electrode at a speed of 100 mm / min along the stacking axis, and the upper separation membrane portion and the lower separation membrane portion are adhered to the upper electrode and the lower electrode, respectively, to such an extent that a second peeling force per 20 mm width is required to peel the upper separation membrane portion and the lower separation membrane portion from the upper electrode and the lower electrode, respectively, at a speed of 100 mm / min along their respective stacking axes, and the deviation between the first peeling force and the second peeling force is 3 gf / 20 mm to 15 gf / 20 mm (0.029 N / 20 mm to 0.15 N / 20 mm).

9. The electrode assembly according to claim 1, wherein the separation membrane portion includes an intermediate separation membrane portion in contact with an intermediate electrode, an upper separation membrane portion in contact with an upper electrode, and a lower separation membrane portion in contact with a lower electrode, the intermediate separation membrane portion has a second air permeability value per square inch of each separation membrane portion at a pressure of 0.05 MPa and room temperature, and the second air permeability value has an air permeability value of 10 sec / 100 ml to 35 sec / 100 ml for the deviation of the air permeability values ​​per square inch of each separation membrane portion at a pressure of 0.05 MPa and room temperature of the upper and lower separation membrane portions.

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