Title of Invention: Secondary battery and method for manufacturing the secondary battery
technical field
[One]
This application claims the benefit of priority based on Korean Patent Application No. 10-2019-0110276 on September 5, 2019 and Korean Patent Application No. 10-2020-0112507 on September 3, 2020, All content disclosed in the literature is incorporated as a part of this specification.
[2]
The present invention relates to a secondary battery and a method of manufacturing the secondary battery, and more particularly, to a secondary battery having a smaller radius of curvature than in the related art, and a manufacturing method of the secondary battery.
[3]
background
[4]
As demand for electronic devices and consumer demands for electronic devices are gradually diversifying, specifications required for secondary batteries that are mounted on electronic devices and can be repeatedly charged and discharged are also diversified.
[5]
For example, recently, the demand for VR devices in which users use electronic devices while wearing them on their heads is increasing. In order for the VR device to be mounted on the head, it is common for the VR device to have a curved surface having a shape corresponding to the shape of a human head. Alternatively, in order to maximize the utility of the internal space of the electronic device, the shape of the secondary battery is required to have an atypical shape, such as a curved shape, out of the conventional regular shape.
[6]
In order to manufacture a secondary battery having a curved surface, it is generally necessary to press the outer surface of the electrode assembly using a pressing press including a curved surface. However, according to the prior art, there are various problems in the process of forming a curved surface by pressing the outer surface of the electrode assembly using a pressure press.
[7]
For example, in the electrode assembly before being pressed by the pressure press, the electrode and the separator are in an adhesive state to each other. There was a problem in that the curved surface could not be maintained due to the adhesive force and returned to the state before being pressed. This problem tends to worsen as the radius of curvature of the curved surface formed by the pressure press decreases (that is, as the electrode assembly is bent more by the pressure press).
[8]
In addition, when a curved surface is formed by pressing a stacked electrode assembly manufactured by alternately stacking electrodes and separators, since there is no configuration for supporting the electrode assembly to maintain the curved shape of the stacked electrode assembly, the electrodes and separators in the electrode assembly There was a problem of peeling. This problem also tends to become more severe as the radius of curvature of the curved surface formed by the pressure press decreases.
[9]
The above problems act as obstacles in manufacturing an electrode assembly and a secondary battery having a curved surface having a smaller radius of curvature than in the related art.
[10]
DETAILED DESCRIPTION OF THE INVENTION
technical challenge
[11]
Accordingly, the problem to be solved by the present invention is to manufacture an electrode assembly in which a curved surface having a smaller radius of curvature is formed compared to the prior art, and the shape of the curved surface can be maintained constant even if time passes.
[12]
means of solving the problem
[13]
According to one aspect of the present invention for achieving the above object, an electrode assembly preparation step of preparing an electrode assembly having a structure in which electrodes and a separator are alternately arranged and having flat upper and lower surfaces; A first pressing for forming a curved surface having a shape corresponding to the curved surface formed in the first pressing apparatus on the upper surface and the lower surface of the electrode assembly by pressing the upper surface and the lower surface of the electrode assembly using the first pressing device having a curved surface step; accommodating step of accommodating the electrode assembly having a curved surface in a pouch-type casing having a concave cup; and a second pressing step of pressing the curved surface formed in the electrode assembly and the outer surface of the exterior material in the first pressing step using a second pressing device having a curved surface; There is provided a secondary battery manufacturing method comprising a.
[14]
a cup forming step of forming, on the exterior material, the cup having a curved surface having a shape corresponding to the curved surface formed on the upper and lower surfaces of the electrode assembly in the first pressing step before the receiving step; may further include.
[15]
a surface leveling step of leveling the curved surface formed on the exterior material formed in the second pressing step after the second pressing step; may further include.
[16]
In the step of leveling the surface, the cylindrical roller rotates on the surface of the curved surface formed on the exterior material, so that the evenness of the surface of the curved surface formed on the exterior material may be improved.
[17]
The electrode assembly has a lamination & stacking (L&S) structure in which a plurality of separate electrodes and a plurality of separate separators are alternately stacked in a thickness direction of the electrode assembly, or a plurality of electrodes including electrodes on a rectangular separation film It may have a stacking & folding (S&F) structure in which a basic unit of is disposed and the separation film is folded.
[18]
In the electrode assembly preparation step, a pressure for pressing the electrode assembly may be 180 kgf to 220 kgf, and a temperature for heating the electrode assembly may be 45 to 65 degrees Celsius.
[19]
In the first pressing step, the pressure for pressing the electrode assembly is 600 kgf to 1500 kgf, the temperature for heating the electrode assembly is 75 degrees to 85 degrees Celsius, and the time for pressing and heating the electrode assembly is 50 seconds to 110 can be seconds
[20]
In the first pressing step, the pressure for pressing the electrode assembly may be 950 kgf to 1050 kgf, and the time for pressing and heating the electrode assembly may be 55 seconds to 65 seconds.
[21]
In the first pressing step, the pressure for pressing the electrode assembly may be 900 kgf to 1000 kgf, and the time for pressing and heating the electrode assembly may be 55 seconds to 65 seconds.
[22]
In the second pressing step, a pressure for pressing the electrode assembly and the casing may be 200 kgf to 400 kgf, and a temperature for heating the electrode assembly and the casing may be 55 to 65 degrees Celsius.
[23]
a third pressing step of further pressing the curved surface formed in the electrode assembly and the curved surface formed in the exterior material formed in the second pressing step using a third pressing device having a curved surface; may further include.
[24]
In the third pressing step, the pressure for pressing the electrode assembly and the casing is 300 kgf to 400 kgf, the temperature for heating the electrode assembly and the casing is 75 to 85 degrees Celsius, and the electrode assembly and the casing are pressed And the heating time may be 8 seconds to 12 seconds.
[25]
After the third pressing step, the radius of curvature of the curved surface formed on the electrode assembly and the casing may be 70 mm to 150 mm, and more specifically, 80 mm to 100 mm.
[26]
According to another aspect of the present invention for achieving the above object, the electrode assembly having a structure in which electrodes and a separator are alternately arranged and having curved surfaces on upper and lower surfaces; a pouch-type packaging material accommodating the electrode assembly and having a curved surface having a radius of curvature corresponding to the radius of curvature of the curved surface formed on the upper and lower surfaces of the electrode assembly and having a cup having a concave shape; Including, a radius of curvature of the curved surface formed on the electrode assembly and the curved surface formed on the casing is 70 mm to 150 mm, respectively.
[27]
Effects of the Invention
[28]
According to the present invention, it is possible to manufacture an electrode assembly in which a curved surface having a smaller radius of curvature is formed than in the prior art, and the shape of the curved surface can be constantly maintained even if time passes.
[29]
Brief description of the drawing
[30]
1 is a cross-sectional view showing the structure of a first basic unit of a secondary battery according to the present invention.
[31]
2 is a cross-sectional view illustrating a structure of a second basic unit of a secondary battery according to the present invention.
[32]
3 is a cross-sectional view illustrating a structure of a third basic unit of a secondary battery according to the present invention.
[33]
4 is a plan view illustrating a state when an electrode assembly of a secondary battery according to an embodiment of the present invention is deployed.
[34]
5 is a cross-sectional view illustrating a structure of an electrode assembly of a secondary battery according to an embodiment of the present invention.
[35]
6 is a side view illustrating a state in which a curved surface is formed in the secondary battery after the second pressing step in the secondary battery manufacturing method according to the present invention.
[36]
7 is a side view illustrating a state in which the surface leveling step is performed in the secondary battery manufacturing method according to the present invention.
[37]
8 is a graph showing the results of Experimental Example 1 for Examples 1 to 4 of the present invention.
[38]
9 is a graph showing the results of Experimental Example 2 for Examples 1 to 4 of the present invention.
[39]
10 is a graph showing the results of Experimental Example 1 for Examples 1 and 5 of the present invention.
[40]
11 is a graph showing the results of Experimental Example 2 for Examples 1 and 5 of the present invention.
[41]
Modes for carrying out the invention
[42]
Hereinafter, a secondary battery and a secondary battery manufacturing method according to an example of the present invention will be described with reference to the drawings.
[43]
[44]
secondary battery
[45]
1 is a cross-sectional view illustrating a structure of a first basic unit of a secondary battery according to the present invention, and FIG. 2 is a cross-sectional view illustrating a structure of a second basic unit of a secondary battery according to the present invention. And, FIG. 3 is a cross-sectional view showing the structure of the third basic unit of the secondary battery according to the present invention.
[46]
The secondary battery according to the present invention may include a first basic unit 110 , a second basic unit 120 , and a third basic unit 130 including an electrode and a separator. Each of the first to third basic units 110 , 120 , and 130 may have a structure in which a cathode 142 , a separator 146 , and anodes 144 and 144 ′ are alternately disposed. In more detail, the first to third basic units may have a structure in which an anode, a separator, and a cathode are alternately stacked.
[47]
1, the first basic unit 110 has a five-layer structure in which a cathode 142, a separator 146, a cathode 144, a separator 146, and a cathode 142 are alternately stacked from the bottom. can have
[48]
In addition, as shown in FIG. 2 , the second basic unit 120 has five layers in which an anode 144 , a separator 146 , a cathode 142 , a separator 146 , and an anode 144 are alternately arranged from the bottom. can have a structure.
[49]
Similar to the case of the second basic unit 120 , the third basic unit 130 may also have a five-layer structure in which a positive electrode, a separator, a negative electrode, a separator, and a positive electrode are alternately disposed from below. However, as shown in FIG. 3 , one of the positive electrodes disposed at both ends of the third basic unit 130 may be a cross-sectional positive electrode 144 ′.
[50]
In general, an electrode generally has a structure in which an electrode active material layer is applied on both surfaces of an electrode sheet. However, the single-sided positive electrode according to the present invention has a structure in which the positive electrode active material layer is applied only on one surface of the positive electrode sheet. At this time, the side on which the positive electrode active material layer is applied among both surfaces of the positive electrode sheet of the single-sided positive electrode 144 ′ is the separator 146 and the
[51]
As shown in FIG. 4 , the electrode assembly 10 according to an embodiment of the present invention includes a separation film 150 and first to third basic units 110 , 120 , and 130 disposed on the separation film 150 . ) may be included. As shown in FIG. 4 , the widths of the first to third basic units 110 , 120 , and 130 may be the same.
[52]
As shown in FIG. 4 , when the electrode assembly 10 is deployed, the first basic unit 110 is disposed at one end of the separation film 150 , and the first basic unit 110 is disposed at the opposite end of the separation film 150 . After an empty space corresponding to the width of the to third basic units is formed, two second basic units 120 , two first basic units 110 , two second basic units 120 , and two first basic units The unit 110 and the two third basic units 130 may have a structure in which they are sequentially arranged. On the other hand, the two third basic units 130 may be disposed such that a cross-sectional anode contacts the separation film 150 (refer to FIG. 5 ).
[53]
Meanwhile, as shown in FIG. 5 , in the electrode assembly 10 according to an exemplary embodiment of the present invention, the first to third basic units 110 , 120 , and 130 are disposed on the separation film 150 , and then the separation film It can have this folded structure. Hereinafter, in the present specification, a structure in which the separation film is folded after a plurality of basic units including electrodes are disposed on the separation film will be referred to as a stacking & folding (S&F) structure.
[54]
On the other hand, the secondary battery according to the present invention has a structure in which electrodes and separators are alternately arranged, and accommodates an electrode assembly having a curved surface on an upper surface and a lower surface, and an electrode assembly, and is formed on the upper and lower surfaces of the electrode assembly. It may include a pouch-type exterior material in which a curved surface having a corresponding radius of curvature is formed and a cup having a concave shape is formed. In this case, the radius of curvature of the curved surface formed on the electrode assembly and the curved surface formed on the exterior material may be 70 mm to 150 mm, respectively. That is, the radius of curvature of the curved surface of the secondary battery according to the present invention may be 70 mm to 150 mm.
[55]
For reference, this secondary battery can be set in the range of 70mm to 150mm so that it can be mounted on a VR device worn on a person's head, but if it is a secondary battery mounted on a VR device that fits a normal adult's head, it will be set to about 80mm to 100mm will be able In addition, 70mm may be mounted on a small VR device for children or wearable by a person with a small head, and 150mm may be mounted on a large VR device that can be worn by a person with a large head.
[56]
[57]
Secondary battery manufacturing method
[58]
[59]
The secondary battery manufacturing method according to the present invention may include an electrode assembly preparation step of preparing an electrode assembly having a structure in which electrodes and separators are alternately arranged. In this case, flat surfaces may be formed on the upper and lower surfaces of the electrode assembly prepared in the electrode assembly preparation step.
[60]
In this case, the electrode assembly prepared in the electrode assembly preparation step is (i) an electrode laminate having a lamination & stacking (L&S) structure in which a plurality of separate electrodes and a plurality of separate separators are alternately stacked in a thickness direction of the electrode assembly or (ii) an electrode laminate having a stacking & folding (S&F) structure in which a plurality of basic units including electrodes are disposed on a rectangular separation film and the separation film is folded.
[61]
In addition, in the electrode assembly preparation step, the pressure for pressing the basic unit to prepare the basic unit may be 180 kgf to 220 kgf, and the temperature for heating the basic unit may be 45 to 55 degrees Celsius.
[62]
On the other hand, when the electrode assembly prepared in the electrode assembly preparation step according to the present invention includes an electrode laminate having an S&F structure, such an electrode laminate is formed when the separation film is folded after placing the basic unit on the separation film. , the pressure for pressing the separation film and the basic unit may be 140 kgf to 160 kgf, and the heating temperature may be 65 to 75 degrees Celsius.
[63]
[64]
The secondary battery manufacturing method according to the present invention may be for manufacturing a secondary battery having a curved surface having a smaller radius of curvature than in the related art. The radius of curvature of the curved surface formed in the secondary battery manufactured by the secondary battery manufacturing method according to the present invention may be 70 mm to 150 mm, and more specifically, 80 mm to 100 mm.
[65]
On the other hand, in the secondary battery manufacturing method according to the present invention, the upper and lower surfaces of the electrode assembly are pressed by using the first pressing device having a curved surface, and thus the upper and lower surfaces of the electrode assembly have a shape corresponding to the curved surface formed in the first pressing device. It may include a first pressing step of forming a curved surface having a. Since curved surfaces are first formed on the upper and lower surfaces of the electrode assembly by the first pressing step in the method for manufacturing a secondary battery according to the present invention, the first pressing step according to the present invention can also be regarded as a curving process. there is.
[66]
In the first pressing step of the method for manufacturing a secondary battery according to the present invention, the pressure for pressing the upper and lower surfaces of the electrode assembly may be 600 kgf to 1500 kgf, and the temperature for pressing the upper and lower surfaces of the electrode assembly is 75 to 85 degrees Celsius The time for pressing and heating the electrode assembly may be 50 seconds to 110 seconds.
[67]
When the pressure for pressing the upper and lower surfaces of the electrode assembly in the first pressing step is less than 600 kgf, a curved surface having a radius of curvature in the range to be manufactured by the present invention may not be formed in the secondary battery, and the electrode assembly in the first pressing step When the pressure to press the upper and lower surfaces of the unit exceeds 1500 kgf, the air permeability may be excessively large.
[68]
The air permeability refers to a time for air to pass through a certain component (eg, an electrode assembly) under a predetermined condition, and the permeability of ions can be confirmed by measuring the air permeability of the electrode assembly. Therefore, the high air permeability of the electrode assembly means that it takes a long time for air to pass through the electrode assembly, particularly, the separator, and thus the ion permeability of the electrode assembly is low. Accordingly, when the air permeability of the electrode assembly is excessively high, the performance of the electrode assembly or the secondary battery may be deteriorated.
[69]
More preferably, the temperature for pressing the upper and lower surfaces of the electrode assembly in the first pressing step may be 950 kgf to 1050 kgf. Alternatively, more preferably, the temperature at which the upper and lower surfaces of the electrode assembly are pressed in the first pressing step may be 900 kgf to 1000 kgf. In addition, more preferably, the time for pressing the upper and lower surfaces of the electrode assembly in the first pressing step may be 55 seconds to 65 seconds. Alternatively, more preferably, the time for pressing the upper and lower surfaces of the electrode assembly in the first pressing step may be 95 seconds to 105 seconds.
[70]
Meanwhile, the secondary battery manufacturing method according to the present invention may further include an accommodation step of accommodating the electrode assembly having a curved surface in a pouch-type exterior material (hereinafter, 'exterior material') having a concave cup. In this case, the shape of the cup formed on the exterior material may correspond to the shape of the electrode assembly in which the curved surface is formed by the first pressing step.
[71]
In addition, in order to form the cup on the exterior material, the secondary battery manufacturing method according to the present invention is made before the receiving step, and has a curved surface having a shape corresponding to the curved surface formed on the upper and lower surfaces of the electrode assembly in the first pressing step. The method may further include a cup forming step of forming the formed cup on the exterior material.
[72]
Meanwhile, the method for manufacturing a secondary battery according to the present invention may further include a second pressing step of pressing the curved surface formed on the electrode assembly and the outer surface of the exterior material in the first pressing step using a second pressing device having a curved surface. . That is, the second pressing step may be pressing the curved surface formed on the secondary battery.
[73]
The second pressing step may be performed after the receiving step. That is, in the second pressing step, it may be understood that the curved surface formed on the electrode assembly accommodated in the casing is also pressed together by pressing the outer surface of the casing after accommodating the electrode assembly in the cup formed in the casing. Therefore, according to the present invention, the shape of the curved surface of the electrode assembly formed in the first pressing step may be more firmly maintained by the second pressing step.
[74]
In the second pressing step, the pressure for pressing the electrode assembly and the exterior material (ie, the secondary battery) may be 200kgf to 400kgf, and the temperature for pressing the upper and lower surfaces of the secondary battery may be 55 to 65 degrees Celsius.
[75]
The second pressing step may be performed by inserting a casing material accommodating the electrode assembly between the first jig and the second jig having a curved surface, and then pressing the casing material in which the electrode assembly is accommodated by the first jig and the second jig. Accordingly, the second pressing step may also be viewed as a jig formation process. 6 is a side view showing a state in which a curved surface is formed on the secondary battery after the second pressing step in the method for manufacturing a secondary battery according to the present invention, and the curved surfaces C on the upper and lower surfaces of the secondary battery 1 after the first pressing step. ) is shown.
[76]
Meanwhile, the secondary battery manufacturing method according to the present invention may further include a surface leveling step of leveling the curved surface formed on the exterior material, which is formed after the second pressing step, and formed in the second pressing step. 7 is a side view illustrating a state in which the surface leveling step is performed in the secondary battery manufacturing method according to the present invention. 7 shows the rotation of the cylindrical roller 20 on the curved surface C formed on the upper surface of the secondary battery 1 .
[77]
In the surface leveling step, the cylindrical roller 20 rotates on the surface of the curved surface C formed in the secondary battery 1 , so that the evenness of the curved surface formed in the secondary battery 1 may be improved. More preferably, in the surface leveling step, when the roller 20 rotates on the surface of the curved surface formed in the secondary battery 1, the cylindrical roller and the surface of the curved surface C formed in the secondary battery 1 do not slide with each other. can This may be understood as a force of static friction acting between the roller and the curved surface formed on the secondary battery in the surface leveling step.
[78]
In addition, the method for manufacturing a secondary battery according to the present invention may further include a third pressing step of additionally pressing the curved surface formed on the electrode assembly and the curved surface formed on the exterior material using the third pressing device on which the curved surface is formed. That is, the third pressing step may be pressing the curved surface formed on the secondary battery. The third pressing step may be performed after the surface leveling step.
[79]
As described above, in the step of leveling the surface, evenness of the surface of the curved surface formed on the exterior material may be improved. However, since the cylindrical roller presses the surface of the curved surface formed on the secondary battery during this process, deformation may occur in the radius of curvature of the curved surface formed on the secondary battery.
[80]
Therefore, according to the present invention, since the curved surface formed in the secondary battery is additionally pressed by the third pressing step after the surface leveling step, the shape of the curved surface of the secondary battery formed in the first pressing step and the second pressing step is changed to the third pressing step. It can be held more firmly by steps.
[81]
In the third pressing step, the pressure for pressing the upper and lower surfaces of the electrode assembly and the casing (ie, the secondary battery) may be 300 kgf to 400 kgf, and the temperature for pressing the upper and lower surfaces of the secondary battery may be 75 to 85 degrees Celsius. And, the time for pressurizing and heating the upper and lower surfaces of the secondary battery may be 8 seconds to 12 seconds.
[82]
The third pressing step may be performed by inserting the secondary battery into a hot press jig heated to a high temperature and then heating and pressurizing the secondary battery by the jig. Accordingly, the third pressing step may also be referred to as a hot press process. A radius of curvature of the secondary battery after the third pressing step, that is, the hot pressing process, may be 70 mm to 150 mm.
[83]
On the other hand, according to the present invention, in the first pressing device for pressing the upper and lower surfaces of the electrode assembly in the first pressing step, the curved surface of the region pressing the center region of the electrode assembly and the curved surface of the region pressing both ends of the electrode assembly The radius of curvature may be different. More specifically, in the first pressing device, a radius of curvature of the curved surface of the region for pressing both ends of the electrode assembly may be smaller than the radius of curvature of the curved surface of the region for pressing on the center region of the electrode assembly.
[84]
An electrode assembly having a curved surface formed by a pressing device tends to be stretched again over time. This is because of the restoring force formed by the adhesion formed between the electrode and the separator in the electrode assembly. This tendency is relatively greater at the end of the curved surface among the curved surfaces formed in the electrode assembly.
[85]
In the first pressing device, the curvature radius of the curved surface of the region pressing both ends and the center region of the electrode assembly may be different from each other to offset this tendency. That is, in the first pressing step, by making the radius of curvature of the curved surface formed at both ends of the curved surface formed on the electrode assembly smaller than that of the curved surface formed on the electrode assembly, the deviation of the radius of curvature in the entire area of ​​the curved surface may be reduced.
[86]
[87]
Example 1
[88]
Separation films, 5 first basic units, 4 second basic units, and 2 third basic units were prepared. The first basic unit had a structure in which a negative electrode, a separator, a positive electrode, a separator, and a negative electrode were sequentially stacked, the second basic unit had a structure in which a positive electrode, a separator, a negative electrode, a separator, and a positive electrode were sequentially stacked, and the third basic unit body had a structure in which a single-sided positive electrode, a separator, a negative electrode, a separator, and a positive electrode were sequentially stacked.
[89]
In the process of manufacturing the first to third basic units, the pressure applied to the electrode and the separator to adhere the electrode and the separator was 200 kgf, and the temperature was 50 degrees Celsius.
[90]
Thereafter, the first to third basic units were disposed on the upper surface of the separation film. The first basic unit was disposed at one end of the separation film, and an empty space as much as the width of the first to third basic units was formed in the direction of the other end opposite to the separation film, and then, two second basic units and two first basic units were formed. A basic unit, two second basic units, two first basic units, and two third basic units were sequentially disposed. At this time, the two third basic units were arranged so that the single-sided positive electrode was in contact with the separation film.
[91]
After the separation film was disposed as described above, the separation film was folded to prepare an electrode assembly.
[92]
Thereafter, the electrode assembly was pressed using a first pressing device having a curved surface to form a curved surface on the electrode assembly (first pressing step). When the first pressing device pressed the electrode assembly, the pressing temperature was 80 degrees Celsius, the pressing pressure was 600 kgf, and the pressing time was 60 seconds.
[93]
Thereafter, a secondary battery was manufactured by accommodating the electrode assembly in a sheet-shaped casing having a cup having a shape corresponding to the shape of the electrode assembly having a curved surface formed by the first pressing device.
[94]
Thereafter, the curved surface formed on the secondary battery was additionally pressurized using the second pressing device having the curved surface (jig formation process). When the second pressurizing device pressurized the secondary battery, the pressurization temperature was 60 degrees Celsius, and the pressurization pressure was 300 kgf.
[95]
Thereafter, the curved surface formed on the secondary battery was additionally pressed (hot press process) using a third pressing device having a curved surface. When the third pressurizing device pressurized the secondary battery, the pressurization temperature was 80 degrees Celsius, the pressurization pressure was 350 kgf, and the pressurization time was 10 seconds.
[96]
[97]
Example 2
[98]
A secondary battery was manufactured in the same manner as in Example 1, except that the pressing pressure when the first pressing device pressed the electrode assembly was 900 kgf.
[99]
[100]
Example 3
[101]
A secondary battery was manufactured in the same manner as in Example 1, except that the pressing pressure when the first pressing device pressed the electrode assembly was 1000 kgf.
[102]
[103]
Example 4
[104]
A secondary battery was manufactured in the same manner as in Example 1, except that the pressing pressure when the first pressing device pressed the electrode assembly was 1500 kgf.
[105]
[106]
Example 5
[107]
A secondary battery was manufactured in the same manner as in Example 1, except that the pressing time when the first pressing device pressed the electrode assembly was 100 seconds.
[108]
[109]
Experimental Example 1
[110]
The radius of curvature of the curved surface formed in the secondary batteries prepared according to Examples 1 to 5 was measured. After taking an image of the secondary battery using Keyence's 3D measuring device, both ends and the middle point of the secondary battery were set to measure the positions of the three points, and then the radius of curvature was measured based on the three points.
[111]
The results of measuring the radius of curvature of the curved surface formed in the secondary batteries manufactured according to Examples 1 to 4 are shown in FIG. 8, and the radius of curvature of the curved surface formed in the secondary batteries manufactured according to Examples 1 and 5. The measurement result is shown in FIG. 9 .
[112]
[113]
Experimental Example 2
[114]
The air permeability of the secondary batteries prepared according to Examples 1 and 5 was measured. The results of measuring the air permeability of the secondary batteries prepared according to Examples 1 to 4 are shown in FIG. 10, and the results of measuring the air permeability of the secondary batteries prepared according to Examples 1 and 5 are shown in FIG. is shown. The air permeability was measured by calculating the time (seconds) it takes for 100 ml of air to pass through the secondary battery.
[115]
[116]
Looking at Experimental Example 1 and Experimental Example 2, the following results can be derived.
[117]
It can be seen that as the pressure applied to the electrode assembly in the first pressing step increases, the radius of curvature of the secondary battery tends to decrease. That is, it can be seen that as the pressure applied to the electrode assembly in the first pressing step increases, the shape of the curved surface formed in the secondary battery is well maintained. However, when the pressure is 1000 kgf (Example 3) and 1500 kgf (Example 4), it can be seen that the difference in the radius of curvature of the curved surface formed in the secondary battery is not large.
[118]
On the other hand, it can be seen that as the pressure applied to the electrode assembly in the first pressing step increases, the air permeability of the secondary battery increases. That is, it can be seen that as the pressure applied to the electrode assembly in the first pressurization step increases, the performance of the secondary battery decreases. In particular, it can be seen that when the pressure is 1500 kgf (Example 4) compared to the case where the pressure is 1000 kgf (Example 3), the air permeability increases rapidly.
[119]
On the other hand, comparing Example 1 and Example 5, when the pressing time in the first pressing step is 60 seconds (that is, in Example 1), the radius of curvature of the secondary battery is 100 seconds in the pressing time in the first pressing step It can be seen that the radius of curvature of the secondary battery in the case (ie, Example 5) is significantly larger than that of the secondary battery. On the other hand, the air permeability of the secondary battery when the pressurization time in the first pressurization step is 100 seconds (ie, Example 5) is that of the secondary battery when the pressurization time in the first pressurization step is 60 seconds (ie, Example 1). It can be seen that there is no significant difference between the air permeability and the air permeability (that is, it can be confirmed that the air permeability of both Examples 1 and 5 is about 250 seconds).
[120]
[121]
Although the present invention has been described with reference to limited examples and drawings, the present invention is not limited thereto, and it is described below with the technical idea of ​​the present invention by those of ordinary skill in the art to which the present invention pertains. It goes without saying that various implementations are possible within the equivalent scope of the claims.
[122]
[123]
[Explanation of code]
[124]
1: secondary battery
[125]
10: electrode assembly
[126]
110: first basic unit
[127]
120: second basic unit
[128]
130: third basic unit
[129]
142: cathode
[130]
144: positive
[131]
144': single-sided anode
[132]
146: separator
[133]
150: separation film
[134]
20: roller
[135]
C: curved surface
Claims
[Claim 1]
An electrode assembly preparation step of preparing an electrode assembly having a structure in which electrodes and separators are alternately arranged and having flat upper and lower surfaces; A first pressing for forming a curved surface having a shape corresponding to the curved surface formed in the first pressing apparatus on the upper surface and the lower surface of the electrode assembly by pressing the upper surface and the lower surface of the electrode assembly using the first pressing device having a curved surface step; accommodating step of accommodating the electrode assembly having a curved surface in a pouch-type casing having a concave cup; and a second pressing step of pressing the curved surface formed in the electrode assembly and the outer surface of the exterior material in the first pressing step using a second pressing device having a curved surface; A secondary battery manufacturing method comprising a.
[Claim 2]
The method according to claim 1, It is made before the receiving step, the cup forming step of forming the cup having a curved surface having a shape corresponding to the curved surface formed on the upper and lower surfaces of the electrode assembly in the first pressing step on the exterior material; A secondary battery manufacturing method further comprising a.
[Claim 3]
The method according to claim 1, After the second pressing step, the surface leveling step of leveling the surface of the curved surface formed on the exterior material formed in the second pressing step; A secondary battery manufacturing method further comprising a.
[Claim 4]
The method according to claim 3, wherein in the step of leveling the surface, the cylindrical roller rotates on the curved surface formed on the exterior material, thereby improving the evenness of the curved surface formed on the exterior material.
[Claim 5]
The method according to claim 1, The electrode assembly, has an L&S (lamination & stacking) structure in which a plurality of separate electrodes and a plurality of separate separators are alternately stacked in a thickness direction of the electrode assembly, or an electrode on a rectangular separation film A method of manufacturing a secondary battery having a stacking & folding (S&F) structure in which a plurality of basic units comprising
[Claim 6]
The method according to claim 1, wherein, in the electrode assembly preparation step, the pressure for pressing the electrode assembly is 180kgf to 220kgf, and the temperature for heating the electrode assembly is 45°C to 65°C.
[Claim 7]
The method according to claim 1, In the first pressing step, the pressure for pressing the electrode assembly is 600kgf to 1500kgf, the temperature for heating the electrode assembly is 75 to 85 degrees Celsius, the time for pressing and heating the electrode assembly is A secondary battery manufacturing method of 50 seconds to 110 seconds.
[Claim 8]
The method according to claim 7, wherein in the first pressing step, the pressure for pressing the electrode assembly is 950 kgf to 1050 kgf, and the time for pressing and heating the electrode assembly is 55 seconds to 65 seconds.
[Claim 9]
The method of claim 7 , wherein in the first pressing step, the pressure for pressing the electrode assembly is 900 kgf to 1000 kgf, and the time for pressing and heating the electrode assembly is 55 seconds to 65 seconds.
[Claim 10]
The method according to claim 1, wherein in the second pressing step, the pressure for pressing the electrode assembly and the casing is 200kgf to 400kgf, and the temperature for heating the electrode assembly and the casing is 55 to 65 degrees Celsius.
[Claim 11]
The method according to claim 1, A third pressing step of further pressing the curved surface formed on the electrode assembly and the curved surface formed on the exterior material formed in the second pressing step using a third pressing device having a curved surface; A secondary battery manufacturing method further comprising a.
[Claim 12]
The method according to claim 11, In the third pressing step, the pressure for pressing the electrode assembly and the casing is 300kgf to 400kgf, the temperature for heating the electrode assembly and the casing is 75 to 85 degrees Celsius, the electrode assembly and The time for pressurizing and heating the exterior material is 8 seconds to 12 seconds secondary battery manufacturing method.
[Claim 13]
The method of claim 11 , wherein, after the third pressing step, a radius of curvature of a curved surface formed on the electrode assembly and the exterior material is 70 mm to 150 mm.
[Claim 14]
The method of claim 13 , wherein, after the third pressing step, a radius of curvature of a curved surface formed on the electrode assembly and the exterior material is 80 mm to 100 mm.
[Claim 15]
an electrode assembly having a structure in which electrodes and a separator are alternately disposed and curved surfaces are formed on upper and lower surfaces; a pouch-type packaging material accommodating the electrode assembly and having a curved surface having a radius of curvature corresponding to the radius of curvature of the curved surface formed on the upper and lower surfaces of the electrode assembly and having a cup having a concave shape; A secondary battery comprising: a radius of curvature of the curved surface formed on the electrode assembly and the curved surface formed on the exterior material is 70 mm to 150 mm, respectively.