Specification
Title of Invention: Electrode assembly and secondary battery and manufacturing method thereof
technical field
[One]
Cross Citation with Related Applications
[2]
This application claims the benefit of priority based on Korean Patent Application No. 10-2019-0165916 dated December 12, 2019, and all contents disclosed in the documents of the Korean patent application are incorporated as a part of this specification.
[3]
technical field
[4]
The present invention relates to an electrode assembly in which disconnection of an electrode tab is suppressed, a secondary battery, and a manufacturing method thereof.
background
[5]
In general, a secondary battery refers to a battery capable of charging and discharging unlike a primary battery that cannot be charged, and such secondary batteries are widely used in high-tech electronic devices such as phones, notebook computers, and camcorders.
[6]
The secondary battery is classified into a can-type secondary battery in which the electrode assembly is embedded in a metal can, and a pouch-type secondary battery in which the electrode assembly is embedded in a pouch.
[7]
On the other hand, the pouch-type secondary battery includes an electrode assembly, an electrode lead coupled to the electrode assembly, and a pouch accommodating the electrode assembly in a state in which the tip of the electrode lead is withdrawn to the outside, wherein the electrode assembly includes an electrode and a separator It has a structure that is alternately stacked. And the electrode includes a coating portion coated with an electrode active material and an electrode tab portion without an electrode active material.
[8]
However, in the pouch-type secondary battery, cracks occur at the interface between the coating part and the electrode tab part included in the electrode, and accordingly, the coating part and the electrode tab part are disconnected. That is, the electrode lead is fixed to the pouch, and the electrode tab portion is fixed to the electrode assembly, so that the electrode tab portion has a state in which tension is applied. In such a state, when the electrode assembly flows by an external force, there is a problem in that a crack is generated at the interface between the coating part included in the electrode and the electrode tab part, and disconnection occurs.
DETAILED DESCRIPTION OF THE INVENTION
technical challenge
[9]
The present invention was invented to solve the above problems, and the present invention includes a crack diffusion prevention part on the interface between the coating part provided on the electrode and the electrode tab part, thereby generating cracks on the interface between the coating part and the electrode tab part. An object of the present invention is to provide an electrode assembly, a secondary battery, and a method for manufacturing the same, which can prevent cracks, prevent diffusion even when cracks occur, and thus prevent disconnection of electrode tabs to increase safety.
means of solving the problem
[10]
The electrode assembly of the present invention includes an electrode having a coating portion coated with an electrode active material and an electrode tab without an electrode active material, wherein the electrode includes a crack diffusion prevention portion, and the crack diffusion prevention portion is on the electrode It may include a crack diffusion prevention hole to be formed, and an insulating coating layer provided on a main surface of the crack diffusion prevention hole.
[11]
The crack diffusion prevention hole may be formed on a boundary line between the coating portion provided on the electrode and the electrode tab.
[12]
The insulating coating layer may include an inner coating portion provided on the inner circumferential surface of the crack diffusion prevention hole, and an outer coating portion integrally connected to the inner coating portion and provided on upper and lower outer surfaces of the crack diffusion prevention hole.
[13]
The outer surface of the outer coating part may have a gear shape in which grooves and protrusions are alternately formed.
[14]
The insulating coating layer has a thickness of 10㎛ ~ 15㎛, the outer coating portion may have a greater thickness than the inner coating portion.
[15]
A curved portion is formed at both ends of the boundary line between the coating portion and the electrode tab,
[16]
The crack diffusion prevention hole may be provided at a point 2.0 to 5.0 mm apart from the curved portion where the end of the boundary line is located.
[17]
The crack diffusion prevention part may further include a reinforcing coating layer coated on a boundary line between the coating part and the electrode tab and connected to the insulating coating layer.
[18]
The crack diffusion prevention hole has a circular or oval shape with a size of 0.5 mm to 2.0 mm.
[19]
On the other hand, the secondary battery of the present invention includes an electrode assembly; an electrode lead coupled to the electrode tab of the electrode assembly; and a battery case accommodating the electrode assembly in a state in which the end of the electrode lead is drawn out.
[20]
On the other hand, the secondary battery manufacturing method of the present invention comprises the steps of (a) preparing an electrode including a coating portion coated with an electrode active material and an electrode tab without an electrode active material; (b) manufacturing a crack diffusion prevention unit for preventing crack diffusion in the electrode; (c) manufacturing an electrode assembly by alternately stacking the electrode and the separator; (d) coupling an electrode lead to an electrode tab of an electrode included in the electrode assembly; (e) accommodating the electrode assembly in a battery case with the end of the electrode lead drawn out to the outside, wherein the crack diffusion prevention part in step (b) is between the coating part and the electrode tab included in the electrode It may be provided on the boundary line of
[21]
The step (b) is a process of drilling a crack diffusion prevention hole for preventing crack diffusion in a boundary line between the coating part and the electrode tab, and a process of coating an insulating coating layer in a form surrounding the inner circumferential surface of the crack diffusion prevention hole Through this, it is possible to manufacture a crack diffusion prevention unit.
[22]
A curved portion is formed at both ends of the boundary line between the coating portion and the electrode tab,
[23]
The crack diffusion prevention hole may be formed in a size of 0.5 to 2 mm at a point spaced apart by 2.0 mm to 5.0 mm from the curved portion where the end of the boundary line is located.
[24]
The step (b) may further include bonding the insulating coating layer to the electrode by simultaneously pressing the upper and lower surfaces of the electrode on which the insulating coating layer is located.
[25]
The step (b) may further include a step of coating a reinforcing coating layer along a boundary line between the coating part and the electrode tab after preparing an insulating coating layer on the electrode.
Effects of the Invention
[26]
The electrode assembly of the present invention includes a crack diffusion prevention part on the electrode, wherein the crack diffusion prevention part includes a crack diffusion prevention hole and an insulating coating layer. Due to such a characteristic, it is possible to prevent cracks from occurring in the electrode, and even when cracks occur, it is possible to prevent diffusion, and as a result, it is possible to prevent disconnection of the electrode, thereby improving safety. In particular, since the electrode assembly of the present invention includes an insulating coating layer for protecting the crack diffusion prevention hole, the external appearance of the crack diffusion prevention hole can be stably maintained, and as a result, crack generation and diffusion can be stably prevented.
[27]
In addition, in the electrode assembly of the present invention, the crack diffusion prevention hole is formed on the boundary line between the electrode tab and the coating portion provided on the electrode. That is, there is a high possibility of cracks occurring on the boundary line between the coating portion and the electrode tab provided on the electrode, and accordingly, by forming a crack diffusion prevention hole on the boundary line between the coating portion and the electrode tab, disconnection between the coating portion and the electrode tab is prevented. can be prevented
[28]
In addition, in the electrode assembly of the present invention, the insulating coating layer is characterized in that it includes an inner coating portion and an outer coating portion. Due to such a feature, both the inner peripheral surface and the outer surface of the crack diffusion prevention hole can be protected, and in particular, the external appearance of the crack diffusion prevention hole can be stably maintained.
[29]
In addition, in the electrode assembly of the present invention, the outer surface of the outer coating is characterized in that it has a gear shape in which grooves and protrusions are alternately formed. This characteristic induces cracks generated between the coating part and the electrode tab to flow into the grooves formed on the outside of the outer coating part. can
[30]
In addition, in the electrode assembly of the present invention, the outer coating portion is characterized in that it has a greater thickness than the inner coating portion. Due to these characteristics, it is possible to stably protect the crack diffusion prevention hole from external impact, and it is possible to stably maintain the external appearance of the crack diffusion prevention hole.
[31]
In addition, in the electrode assembly of the present invention, the crack diffusion prevention hole is formed at a position 2.0 to 5.0 mm apart from the curved portion where the end of the boundary line formed between the coating portion and the electrode tab is located. Due to such a feature, the crack diffusion occurring in the curved portion between the coating portion and the electrode tab can be quickly blocked while minimizing the weakening of strength between the coating portion and the electrode tab by the crack diffusion prevention hole.
[32]
In addition, in the electrode assembly of the present invention, it is characterized in that it includes a reinforcing coating layer coated on the boundary line between the coating part and the electrode tab. Due to such a feature, the strength of the boundary line between the coating part and the electrode tab can be reinforced, and as a result, cracks can be prevented.
Brief description of the drawing
[33]
1 is a perspective view showing an electrode assembly according to a first embodiment of the present invention.
[34]
Figure 2 is a perspective view showing an electrode of the electrode assembly according to the first embodiment of the present invention.
[35]
Figure 3 is a partially enlarged view of Figure 2;
[36]
Fig. 4 is a cross-sectional view of Fig. 3;
[37]
5 is a perspective view illustrating a secondary battery according to a second embodiment of the present invention;
[38]
6 is a flowchart illustrating a method for manufacturing a secondary battery according to a second embodiment of the present invention.
[39]
7 is a process diagram illustrating a method for manufacturing a secondary battery according to a second embodiment of the present invention.
[40]
8 is a partial plan view showing an electrode assembly according to a third embodiment of the present invention.
[41]
9 is a partial plan view showing an electrode assembly according to a fourth embodiment of the present invention.
[42]
10 is a partial plan view showing an electrode assembly according to a fifth embodiment of the present invention.
[43]
11 is an image and graph showing the experimental results according to Experimental Example 1 of the present invention.
[44]
12 is an image and graph showing the experimental results according to Experimental Example 2 of the present invention.
[45]
13 is an image showing experimental results according to Experimental Example 3 of the present invention.
[46]
14 is an image showing experimental results according to Experimental Example 4 of the present invention.
Best mode for carrying out the invention
[47]
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art can easily carry out the present invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.
[48]
[Electrode assembly according to the first embodiment of the present invention]
[49]
The electrode assembly according to the first embodiment of the present invention has a structure including a crack diffusion prevention part, thereby suppressing the occurrence of cracks in the electrode assembly, and preventing the spread of cracks even when cracks occur, thereby preventing the occurrence of a disconnection accident. can be prevented
[50]
That is, the electrode assembly 100 according to the first embodiment of the present invention has a structure in which a plurality of electrodes 110 are alternately stacked with a separator interposed therebetween, as shown in FIGS. The electrode 110 includes a coating part 111 coated with an electrode active material, and an electrode tab 112 connected to one surface of the coating part 111 and having a width smaller than that of the coating part 111 and having no electrode active material. include A curved portion 113 is formed at both ends between the coating portion 111 and the electrode tab 112 to prevent cracks. The plurality of electrodes 110 may be an anode and a cathode, and the anode and the cathode are alternately stacked with a separator interposed therebetween.
[51]
On the other hand, the electrode 110 includes a crack diffusion prevention unit 130 for preventing crack diffusion on a surface with a high possibility of cracking, and the crack diffusion prevention unit 130 includes an effective stress generated in the electrode 110 . to suppress the occurrence of cracks, while preventing the spread of cracks generated in the electrode 110 to prevent disconnection of the electrode.
[52]
For example, the crack diffusion prevention part 130 includes a crack diffusion prevention hole 131 formed in the electrode 110 and an insulating coating layer 132 provided on an inner circumferential surface of the crack diffusion prevention hole 131 . . In particular, the crack diffusion prevention hole 131 is formed on the boundary line O between the coating portion 111 provided on the electrode 110 and the electrode tab 112 .
[53]
That is, the boundary line O between the coating portion 111 and the electrode tab 112 provided on the electrode 110 is easily cracked due to an external impact, and due to the crack, the coating portion 111 and the electrode There was a problem that the tab 112 was disconnected. In order to prevent this, the present application forms a crack diffusion prevention hole 131 on the boundary line O between the coating portion 111 and the electrode tab 112 , and in order to reinforce the strength of the crack diffusion prevention hole 131 . An insulating coating layer 132 is provided.
[54]
Accordingly, the crack diffusion prevention unit 130 prevents crack diffusion by blocking the diffusion of cracks generated at the boundary line O between the coating unit 111 and the electrode tab 112 through the crack diffusion prevention hole 131 . can do. In particular, cracks may occur in the crack diffusion prevention hole 131 by external force, but cracks are prevented from occurring in the crack diffusion prevention hole 131 by protecting the inner peripheral surface of the crack diffusion prevention hole 131 through the insulating coating layer 132 . can be prevented In particular, the insulating coating layer 132 may reinforce the strength of the boundary line O between the coating portion 111 and the electrode tab 112 , and accordingly, the boundary line O between the coating portion 111 and the electrode tab 112 . By preventing the deformation of cracks, the occurrence of cracks can be greatly reduced.
[55]
On the other hand, the insulating coating layer 132 is integrally connected to the inner coating portion 132a provided on the inner circumferential surface of the crack diffusion prevention hole 131 and the inner coating portion 132a, and the crack diffusion prevention hole 131 ) includes an outer coating portion (132b) provided on the outer upper and lower surfaces.
[56]
Accordingly, the insulating coating layer 132 can protect both the inner peripheral surface and the outer surface of the crack diffusion prevention hole 131, thereby effectively reinforcing the strength of the crack diffusion prevention hole 131, and in particular, the It is possible to significantly prevent cracks from occurring in the crack diffusion prevention hole 131 .
[57]
The insulating coating layer 132 has a thickness of 10㎛ ~ 15㎛, the outer coating portion 132b has a greater thickness than the inner coating portion (132a). That is, cracks are generated by deformation such as torsion of the electrode, and accordingly, the thickness of the outer coating portion 132b coated on the outer surface of the crack diffusion prevention hole 131 is formed to be large, so that the crack diffusion prevention hole 131 is formed. The strength of the outer circumferential surface is greatly increased, thereby preventing the crack diffusion prevention hole 131 from being deformed. On the other hand, since the inner coating portion 132a is for reinforcing the insulation of the crack diffusion prevention hole 131 , it is formed to have a smaller thickness than the outer coating portion 132b to reduce costs.
[58]
Meanwhile, the crack diffusion prevention hole 131 is provided at a point spaced apart by a predetermined distance α from the curved portion 113 formed at both ends of the boundary line O between the coating portion 111 and the electrode tab 112 . do. That is, the crack diffusion prevention hole 131 is provided at a point 2.0 to 5.0 mm apart from the curved portion 113 where the end of the boundary line O is located. That is, when the position of the crack diffusion prevention hole 131 is provided at a point spaced apart from the curved portion 113 by 2.0 mm or less, the curved portion 113 and the crack diffusion prevention hole ( 131), there is a problem that the gap is easily cut. In addition, when the crack diffusion prevention hole 131 is positioned at a point more than 5.0 mm apart from the curved portion 113 , there is a problem in that irregular cracks occurring in the curved portion 113 cannot be blocked. Accordingly, the crack diffusion prevention hole 131 is provided at a point 2.0 to 5.0 mm apart from the curved portion 113 where the end of the boundary line O is located, and accordingly, the curved portion 113 and the crack diffusion prevention hole 131 are provided. ), and at the same time, it is possible to stably block even the irregular cracks generated in the curved portion 113 at the same time.
[59]
Meanwhile, the crack diffusion prevention hole 131 may be formed in a circular shape having a size of 0.5 mm to 2.0 mm. Accordingly, even irregular cracks generated in the curved portion 113 can be stably blocked.
[60]
Therefore, since the electrode assembly 100 of the present invention includes the crack diffusion prevention unit 130, it is possible to suppress the occurrence of cracks in the electrode, and even if cracks occur, the diffusion can be blocked, thereby preventing the disconnection accident in advance.
[61]
Hereinafter, in describing another embodiment of the present invention, the same reference numerals are used for components having the same functions as those of the above-described embodiment, and overlapping descriptions are omitted.
[62]
[Secondary battery according to the second embodiment of the present invention]
[63]
As shown in FIG. 5 , the secondary battery 10 according to the second embodiment of the present invention has an electrode assembly 100 and an electrode lead 200 coupled to the electrode tab 112 of the electrode assembly 100 . , and a battery case 300 accommodating the electrode assembly 100 in a state in which the end of the electrode lead 200 is withdrawn to the outside.
[64]
On the other hand, in a secondary battery, since the electrode lead is coupled to the battery case, when the electrode assembly accommodated in the battery case moves up and down or left and right, the electrode tab located between the electrode lead and the electrode assembly is deformed (for example, twisted). There is a problem in that a crack is generated at the boundary line between the coating part and the electrode tab of the , and the coating part and the electrode tab are cut as the crack spreads.
[65]
In order to solve the above problems, the secondary battery 10 according to the second embodiment of the present invention includes a crack diffusion prevention unit for preventing the spread of cracks generated in the electrode included in the electrode assembly, and safety through the crack diffusion prevention unit can increase
[66]
For example, the electrode assembly 100 of the secondary battery 10 according to the second embodiment of the present invention has a structure in which a plurality of electrodes 110 are alternately stacked with a separator interposed therebetween, the electrodes 110 It includes a coating part 111 coated with a silver electrode active material, and an electrode tab 112 connected to one surface of the coating part 111 and having a width smaller than that of the coating part 111 and having no electrode active material. A curved portion 113 is formed at both ends between the coating portion 111 and the electrode tab 112 to prevent cracks.
[67]
Here, the electrode 110 includes a crack diffusion prevention part 130 at a boundary line O between the coating part 111 and the electrode tab 112 , and the crack diffusion prevention part 130 is the electrode 110 . ) to prevent crack spread by blocking the progress of cracks generated at the boundary line (O), thereby preventing disconnection of the electrode.
[68]
Meanwhile, the electrode assembly 100 has the same configuration and function as the electrode assembly described in the first embodiment, and thus overlapping description will be omitted.
[69]
Therefore, the secondary battery 10 according to the second embodiment of the present invention can block the spread of cracks generated in the electrode 110, thereby preventing disconnection of the electrode.
[70]
Hereinafter, a method for manufacturing a secondary battery according to a second embodiment of the present invention will be described.
[71]
[Method for manufacturing secondary battery according to the second embodiment of the present invention]
[72]
As shown in FIGS. 6 and 7 , the method for manufacturing a secondary battery according to a second embodiment of the present invention includes (a) preparing an electrode including a coating portion coated with an electrode active material and an electrode tab without an electrode active material , (b) manufacturing a crack diffusion prevention part for preventing crack diffusion in the electrode, (c) manufacturing an electrode assembly by alternately stacking the electrode and a separator, (d) an electrode included in the electrode assembly coupling the electrode lead to the electrode tab of the , (e) accommodating the electrode assembly in a battery case in a state in which the end of the electrode lead is withdrawn to the outside.
[73]
(a) step
[74]
Step (a) is to prepare an electrode, and a current collector having an uncoated region formed on one surface is prepared. In this case, the connection part between the uncoated part and the current collector is formed as the curved part 113 . Next, the electrode active material is coated on the surface of the current collector except for the uncoated region. Then, the electrode 110 including the coating portion 111 coated with the electrode active material and the electrode tab 112 as the uncoated portion without the electrode active material may be manufactured. Meanwhile, in the electrode 110 , a boundary line 0 is formed while a step (ie, a step formed by the thickness of the electrode active material) is formed between the coating part 111 and the electrode tab 112 .
[75]
Meanwhile, the electrode 110 may include a first electrode 110A and a second electrode 110B, wherein the first electrode 110A may be an anode and the second electrode 110B may be a cathode.
[76]
(b) step
[77]
Step (b) is for manufacturing a crack diffusion prevention part, and drilling a crack diffusion prevention hole 131 for preventing crack diffusion in the boundary line O between the coating part 111 and the electrode tab 112 . and coating the insulating coating layer 132 by applying an insulating coating material to surround the inner circumferential surface of the crack diffusion prevention hole 131 . Through this process, the crack diffusion prevention part 130 including the crack diffusion prevention hole 131 and the insulating coating layer 132 may be manufactured.
[78]
In particular, the crack diffusion prevention part 130 is provided on the boundary line O between the coating part 131 and the electrode tab 112 included in the electrode 110 in which cracks easily occur due to deformation.
[79]
Meanwhile, the crack diffusion prevention part 130 is positioned to be spaced apart from the curved part formed at both ends of the boundary line O between the coating part 111 and the electrode tab 112 by a predetermined distance. For example, the crack diffusion prevention hole 131 of the crack diffusion prevention unit 130 is formed in a size of 0.5 to 2 mm at a point 2.0 mm to 5.0 mm apart from the curved portion 113 where the end of the boundary line O is located. .
[80]
On the other hand, the step (b) further includes a step of bonding the insulating coating layer 132 to the electrode 110 by simultaneously pressing the upper and lower surfaces of the electrode 110 on which the insulating coating layer 132 is located. Accordingly, the bonding strength between the electrode 110 and the crack diffusion prevention unit 130 may be increased.
[81]
On the other hand, in step (b), referring to FIG. 10 , after manufacturing the insulating coating layer 132 on the electrode, the process of coating the reinforcement coating layer 133 along the boundary line between the coating part and the electrode tab. Further, it is possible to greatly reinforce the strength of the electrode located on the boundary line O, and in particular, it is possible to remove the step formed on the boundary line O, thereby preventing damage to the separator facing the electrode.
[82]
(c) step
[83]
Step (c) is for manufacturing the electrode assembly, and the electrode assembly 100 is manufactured by alternately stacking the electrode 110 and the separator.
[84]
(d) step
[85]
Step (d) is for manufacturing a secondary battery. The electrode lead 200 is coupled to the end of the electrode tab 112 included in the electrode assembly 100, and the end of the electrode lead 200 is pulled out. By accommodating the electrode assembly 100 in the battery case 300 in this state, the finished secondary battery 10 can be manufactured.
[86]
[Electrode assembly according to the third embodiment of the present invention]
[87]
As shown in FIG. 8 , the electrode assembly 100 according to the third embodiment of the present invention includes a crack diffusion prevention part 130 including a crack diffusion prevention hole 131 and an insulating coating layer 132 . .
[88]
Here, the crack diffusion prevention hole 131 is provided in an elliptical shape at the boundary line O between the coating part 111 and the electrode tab 112 . Of course, the insulating coating layer 132 is also provided in an elliptical shape.
[89]
Therefore, the crack diffusion prevention unit 130 of the electrode assembly 100 according to the third embodiment of the present invention can effectively block cracks occurring at the boundary line O between the coating unit 111 and the electrode tab 112 . .
[90]
On the other hand, the crack diffusion prevention hole 131 may be provided in a geometric shape connected only with a curve, and accordingly, the shape of the crack diffusion prevention hole is adjusted to fit the boundary line O between the coating part 111 and the electrode tab 112 . can be adjusted
[91]
[Electrode assembly according to the fourth embodiment of the present invention]
[92]
As shown in FIG. 9 , the electrode assembly 100 according to the fourth embodiment of the present invention includes a crack diffusion prevention part 130 including a crack diffusion prevention hole 131 and an insulating coating layer 132 and , the insulating coating layer 132 includes an inner coating portion (132a) and an outer coating portion (132b).
[93]
Here, the outer surface of the outer coating portion 132b has a gear shape in which grooves and protrusions are alternately formed. That is, when the crack diffusion prevention unit 130 introduces a crack generated at the boundary line O between the coating unit 111 and the electrode tab 112 into a groove formed outside the outer coating unit 132b, the crack is coated on the outside. It can be blocked so that it does not spread outside the department.
[94]
Therefore, the electrode assembly 100 according to the fourth embodiment of the present invention can greatly prevent the spread of cracks generated in the electrode.
[95]
[Electrode assembly according to the fifth embodiment of the present invention]
[96]
As shown in FIG. 10 , the electrode assembly 100 according to the fifth embodiment of the present invention includes a crack diffusion prevention part 130 including a crack diffusion prevention hole 131 and an insulating coating layer 132 . .
[97]
Here, the crack diffusion prevention part 130 further includes a reinforcing coating layer 133 coated on the boundary line O between the coating part 111 and the electrode tab 112 and connected to the insulating coating layer 132 . .
[98]
Meanwhile, the reinforcing coating layer 133 may be formed of the same material as the insulating coating layer 132 . For example, the reinforcing coating layer 133 may be formed of SBR (tyrene-butadiene rubber) or CMC (Ceramic Matrix Composite), thereby minimizing the reaction with the electrolyte inside the secondary battery, and peeling from the tab during charging and discharging. can prevent
[99]
Therefore, the electrode assembly according to the fifth embodiment of the present invention can prevent cracks by reinforcing the strength of the boundary line O between the coating part 111 and the electrode tab 112, and in particular, the coating part and the electrode By removing the step difference between the tabs, it is possible to prevent damage to the separator facing the electrode.
[100]
[Experimental example]
[101]
Experimental Example 1
[102]
A secondary battery including an electrode assembly, an electrode lead, and a battery case is prepared. In this case, the electrode assembly includes an electrode and a separator, the electrode includes a coating part and an electrode tab, and the electrode lead is coupled to the electrode tab. Here, a crack diffusion prevention hole is provided at the boundary line between the coating part and the electrode tab to prevent crack diffusion.
[103]
That is, Experimental Example 1 has a structure in which the insulating coating layer is excluded from the secondary battery described in the second embodiment of the present invention.
[104]
At this time, in Experimental Example 1, a plurality of secondary batteries having different diameters of crack diffusion prevention holes were prepared, and then tension was applied to the electrode tab of the secondary battery in the X-axis in the width direction or in the Y-axis in the longitudinal direction to generate stress. experiment with As a result, a result as shown in FIG. 11 can be obtained.
[105]
Experimental result of Experimental Example 1
[106]
Referring to (a) of FIG. 11 , as a result of applying tension to the electrode tab 112 of the secondary battery along the X-axis, effective stress is generated in the curved portion (round portion, 113) and the crack diffusion prevention hole (131). , it can be seen that, as the diameter of the crack diffusion prevention hole 131 increases, the effective stress increases due to a decrease in the effective area of ​​the tension. In particular, it can be seen that the maximum effective stress is generated in the curved portion 113 .
[107]
Referring to (b) of FIG. 11 , as a result of applying tension to the electrode tab 112 of the secondary battery along the Y-axis, as the diameter of the crack diffusion prevention hole 131 increases, the effective stress increases due to a decrease in the effective area of ​​the tension. can confirm that In particular, it can be seen that the maximum stress is generated in the crack diffusion prevention hole 131 .
[108]
Therefore, in Experimental Example 1, when the crack diffusion prevention hole 131 is formed to have a diameter of 1 to 2 mm, the occurrence of cracks can be prevented.
[109]
Experimental Example 2
[110]
A secondary battery including an electrode assembly, an electrode lead, and a battery case is prepared. In this case, the electrode assembly includes an electrode and a separator, the electrode includes a coating part and an electrode tab, and the electrode lead is coupled to the electrode tab. Here, a crack diffusion prevention hole is provided at the boundary line between the coating part and the electrode tab to prevent crack diffusion.
[111]
That is, Experimental Example 2 has a structure in which the insulating coating layer is excluded from the secondary battery described in the second embodiment of the present invention.
[112]
At this time, in Experimental Example 2, a plurality of secondary batteries in which the positions of the crack diffusion prevention holes 131 gradually move away from the curved portion 113 are prepared, and then the generation of effective stress is tested. As a result, a result as shown in FIG. 12 can be obtained.
[113]
Experimental result of Experimental Example 2
[114]
Referring to (a) of FIG. 12 , in Experimental Example 2, it can be seen that the effective stress decreases as the position of the crack diffusion prevention hole 131 is further away from the curved portion 113, where the effective stress is 3.5 mm or more. It can be seen that this decrease is not large.
[115]
Therefore, in Experimental Example 2, it can be confirmed that the optimal position of the crack diffusion prevention hole is a point spaced apart by 3.5 mm from the curved portion.
[116]
Experimental Example 3
[117]
A secondary battery including an electrode assembly, an electrode lead, and a battery case is prepared. In this case, the electrode assembly includes an electrode and a separator, the electrode includes a coating part and an electrode tab, and the electrode lead is coupled to the electrode tab.
[118]
Here, Experimental Example 3 is a secondary battery in which only a crack diffusion prevention hole 131 is formed on the boundary line between the coating part and the electrode tab to prevent crack diffusion, and a secondary battery including a crack diffusion prevention hole 131 and an insulating coating layer 132 After preparing the electrode tab of the secondary battery, the effective stress is tested by applying tension along the X-axis, which is the width direction, or the tension along the Y-axis, which is the longitudinal direction, of the secondary battery.
[119]
On the other hand, the insulation coating minimizes the reaction with the electrolyte inside the secondary battery, and it is necessary to choose a material that does not peel off the tab during charging and discharging. 15㎛ thickness. As a result, a result as shown in FIG. 13 can be obtained.
[120]
Experimental result of Experimental Example 3
[121]
Referring to (a) and (b) of Figure 13, it can be seen that the effective stress is reduced in the secondary battery including the insulating coating layer. Here, FIG. 13(a) shows that tension is applied along the X-axis, and FIG. 13(b) shows that tension is applied along the Y-axis.
[122]
That is, there is an effective stress reduction effect due to an increase in thickness when the insulating coating layer is formed in the crack diffusion prevention hole. In other words, when the insulating coating layer is applied, it can be seen that the effective stress applied to the crack diffusion prevention hole is reduced by about 10% when the X-axis tension is applied, and by about 21% when the Y-axis tension is applied.
[123]
Therefore, it can be confirmed that Experimental Example 3 can reduce the effective stress generated on the electrode tab when the insulating coating layer is further included, and as a result, crack generation and diffusion can be prevented.
[124]
Experimental Example 4
[125]
A secondary battery including an electrode assembly, an electrode lead, and a battery case is prepared. In this case, the electrode assembly includes an electrode and a separator, the electrode includes a coating part and an electrode tab, and the electrode lead is coupled to the electrode tab. Here, a crack diffusion prevention hole is provided at the boundary line between the coating part and the electrode tab to prevent crack diffusion.
[126]
That is, Experimental Example 4 had a structure in which the insulating coating layer was excluded from the secondary battery described in the second embodiment of the present invention, and a secondary battery having a circular crack diffusion prevention hole and an oval crack diffusion prevention hole secondary battery prepare Then, stress generation is tested by applying tension to the electrode tab of the secondary battery in the X-axis in the width direction or in the Y-axis in the longitudinal direction. As a result, a result as shown in FIG. 14 can be obtained.
[127]
Experimental result of Experimental Example 4
[128]
Referring to (a) and (b) of Figure 14, it can be seen that the effective stress is reduced in the elliptical crack diffusion prevention hole than in the circular crack diffusion prevention hole. Here, FIG. 13(a) shows that tension is applied along the X-axis, and FIG. 13(b) shows that tension is applied along the Y-axis.
[129]
That is, it can be seen that there is an effective stress reduction effect due to an increase in the effective area of ​​tension when the shape is changed from a circular shape to an oval shape. In other words, when changing to an elliptical shape, it can be seen that the effective stress is reduced by about 27% when the X-axis tension is applied, and has an effect of about 1% when the Y-axis tension is applied.
[130]
The scope of the present invention is indicated by the claims to be described later rather than the above detailed description, and various embodiments derived from the meaning and scope of the claims and their equivalent concepts are possible.
[131]
[Explanation of code]
[132]
10: secondary battery
[133]
100: electrode assembly
[134]
110: electrode
[135]
111: coating part
[136]
112: electrode tab
[137]
130: crack spread prevention unit
[138]
131: crack diffusion prevention hole
[139]
132: insulating coating layer
[140]
132a: inner coating surface
[141]
132b: outer coating surface
[142]
133: reinforcing coating layer
[143]
200: electrode lead
[144]
300: battery case

Claims

[Claim 1]
An electrode comprising an electrode having a coating portion coated with an electrode active material and an electrode tab without an electrode active material, wherein the electrode includes a crack diffusion prevention portion, and the crack diffusion prevention portion includes a crack diffusion prevention hole formed in the electrode; , An electrode assembly comprising an insulating coating layer provided on the main surface of the crack diffusion prevention hole.
[Claim 2]
The electrode assembly of claim 1 , wherein the crack diffusion prevention hole is formed on a boundary line between the coating part provided on the electrode and the electrode tab.
[Claim 3]
The electrode assembly of claim 1 , wherein the insulating coating layer includes an inner coating portion provided on an inner circumferential surface of the crack diffusion prevention hole, and an outer coating portion integrally connected to the inner coating portion and provided on the outer upper and lower surfaces of the crack diffusion prevention hole. .
[Claim 4]
The electrode assembly according to claim 3, wherein the outer surface of the outer coating part has a gear shape in which grooves and protrusions are alternately formed.
[Claim 5]
The electrode assembly of claim 3 , wherein the insulating coating layer has a thickness of 10 μm to 15 μm, and the outer coating portion has a greater thickness than the inner coating portion.
[Claim 6]
The electrode assembly according to claim 1, wherein curved portions are formed at both ends of the boundary line between the coating portion and the electrode tab, and the crack diffusion prevention hole is provided at a point 2.0 to 5.0 mm apart from the curved portion where the end of the boundary line is located. .
[Claim 7]
The electrode assembly of claim 1 , wherein the crack diffusion prevention part further comprises a reinforcing coating layer coated on a boundary line between the coating part and the electrode tab and connected to the insulating coating layer.
[Claim 8]
The electrode assembly of claim 1, wherein the crack diffusion prevention hole has a circular or oval shape with a size of 0.5 mm to 2.0 mm.
[Claim 9]
The electrode assembly according to claim 1; an electrode lead coupled to the electrode tab of the electrode assembly; and a battery case accommodating the electrode assembly in a state in which an end of the electrode lead is withdrawn to the outside.
[Claim 10]
(a) preparing an electrode including a coating portion coated with an electrode active material and an electrode tab without an electrode active material; (b) manufacturing a crack diffusion prevention unit for preventing crack diffusion in the electrode; (c) manufacturing an electrode assembly by alternately stacking the electrode and the separator; (d) coupling an electrode lead to an electrode tab of an electrode included in the electrode assembly; (e) accommodating the electrode assembly in a battery case with the end of the electrode lead drawn out to the outside, wherein the crack diffusion prevention part in step (b) is between the coating part and the electrode tab included in the electrode A method of manufacturing a secondary battery provided on the boundary line of
[Claim 11]
The method according to claim 10, wherein the step (b) comprises a step of drilling a crack diffusion prevention hole for preventing crack diffusion in a boundary line between the coating portion and the electrode tab, and insulating the inner circumferential surface of the crack diffusion prevention hole A secondary battery manufacturing method for manufacturing a crack diffusion prevention part through a process of coating a coating layer.
[Claim 12]
The method according to claim 10, wherein curved portions are formed at both ends of the boundary line between the coating portion and the electrode tab, and the crack diffusion prevention hole is 0.5 to 2 mm at a point 2.0 mm to 5.0 mm apart from the curved portion where the end of the boundary line is located. A method of manufacturing a secondary battery formed in size.
[Claim 13]
The method of claim 11 , wherein the step (b) further comprises bonding the insulating coating layer to the electrode by simultaneously pressing the upper and lower surfaces of the electrode on which the insulating coating layer is located.
[Claim 14]
The method according to claim 10, wherein the step (b) further comprises a step of coating a reinforcing coating layer along a boundary line between the coating part and the electrode tab after preparing an insulating coating layer on the electrode.