KR20220041728A - Button type secondary battery - Google Patents

Abstract

The present invention relates to a button-type secondary battery and relates to a button-type secondary battery that can significantly improve welding strength in which an electrode tab is welded to a can case, and thus has a high level of impact resistance to pass a mechanical welding strength test. The button-type secondary battery according to the present invention comprises: an electrode assembly formed by alternately stacking an electrode and a separator; a can case in which the electrode assembly is accommodated in the inner accommodation space; and an electrode tab having one side connected to the electrode of the electrode assembly and the other side connected to the can case through welding. A welding pattern appearing at a welding part where the electrode tab is welded to the can case includes a circular shape and an additional shape added to the circular shape.

Description

Button type secondary battery {BUTTON TYPE SECONDARY BATTERY}

The present invention relates to a button-type secondary battery, which can significantly improve the welding strength in which an electrode tab is welded to a can case, and thus has a high level of impact resistance, so that it can pass a mechanical welding strength test (Mechanical test) It relates to a button-type secondary battery having a.

In recent years, the increase in the price of energy sources due to the depletion of fossil fuels and the interest in environmental pollution are increasing, and the demand for eco-friendly alternative energy sources is becoming an indispensable factor for future life. Accordingly, research on various power generation technologies such as solar power, wind power, and tidal power continues, and power storage devices such as batteries for more efficient use of the generated electrical energy are also of great interest.

Furthermore, as technology development and demand for electronic mobile devices and electric vehicles using batteries increase, the demand for batteries as an energy source is rapidly increasing, and accordingly, a lot of research on batteries that can meet various needs is being conducted. there is.

In particular, in terms of materials, there is a high demand for lithium secondary batteries such as lithium ion batteries and lithium ion polymer batteries having advantages such as high energy density, discharge voltage, and output stability.

According to the shape of the battery case, secondary batteries are classified into cylindrical batteries and prismatic batteries in which the electrode assembly is embedded in a cylindrical or prismatic metal can, and pouch-type batteries in which the electrode assembly is embedded in a pouch-type case of an aluminum laminate sheet. can be And recently, in line with the trend of miniaturization of wearable devices, the importance of developing small batteries such as button-type secondary batteries has been highlighted.

In the conventional button-type secondary battery, the electrode tab protruding from the electrode assembly was simply welded to the metal battery case without a special shape and electrically connected. In this type of welding, there is a problem that the electrode tab is easily detached from the metal battery case or the electrical resistance is increased because the welding strength is weak. That is, the impact resistance was very weak. As a result, it was difficult to pass the mechanical weld strength test to ensure the excellent quality of the secondary battery. Therefore, it was necessary to develop a welding pattern that satisfies the needs of consumers and has stability and high quality impact resistance.

The present invention has been devised to solve the above problems, and the object of the present invention is to significantly improve the welding strength in which the electrode tab is welded to the can case, and thus has a high level of impact resistance to test the mechanical welding strength ( To provide a button-type secondary battery having a condition that can pass the mechanical test).

A button-type secondary battery according to the present invention includes an electrode assembly formed by alternately stacking electrodes and separators; a can case in which the electrode assembly is accommodated in the inner accommodating space; And one side is connected to the electrode of the electrode assembly, the other side comprises an electrode tab connected to the can case through welding, the welding pattern appearing in the weld where the electrode tab is welded to the can case is in addition to the circular shape and the circular shape includes shape.

In the button-type secondary battery according to the present invention, the circular shape may be a circular shape in which one side is open.

In the circular shape of the welding pattern, the opening angle of the open portion may be 30 degrees or more and less than 120 degrees.

The additional shape may be in the form of a line segment.

The additional shape may be inside the circular shape.

The circular shape may be a circular shape in which one side is open, and the additional shape may be formed inside the circular shape in the form of a line segment, and one end of the line segment may be directed toward the open part of the circular shape.

The diameter of the circular shape may have a value between 1.0 mm and 2.0 mm.

The thickness of the circular-shaped line may have a value between 100 um and 150 um.

The end of the additional shape may be within an imaginary circle that the circular shape draws.

Based on the additional shape in the form of a line segment, the welding pattern may have a symmetrical shape.

At least two additional shapes in the form of line segments may be formed, and the additional shapes may be parallel to each other.

In the button-type secondary battery according to the present invention, the can case includes an upper can and a lower can, and the electrode assembly is a jelly roll-type electrode assembly in which electrodes and separators are alternately stacked and wound, and a center hole is located in the center of the jelly-roll-type electrode assembly. This is formed, and the welding pattern may be formed at a position corresponding to the position of the central hole.

The welding pattern may be formed on the bottom of the lower can.

The welding beads formed in the welding portion may be formed from the outside to the inside of the can case.

A button-type secondary battery according to the present invention includes an electrode assembly formed by alternately stacking electrodes and separators; a can case in which the electrode assembly is accommodated in the inner accommodating space; And one side is connected to the electrode of the electrode assembly, the other side comprises an electrode tab connected to the can case through welding, the welding pattern appearing in the weld where the electrode tab is welded to the can case is in addition to the circular shape and the circular shape A button type having a condition that includes a shape and thus can significantly improve the welding strength at which the electrode tab is welded to the can case, and as a result, has a high level of impact resistance and can pass the mechanical test A secondary battery can be implemented.

1 is a perspective view of a button-type secondary battery according to Example 1 of the present invention.
FIG. 2 is a cross-sectional view taken along line AA of FIG. 1 .
3 is a plan view illustrating a welding pattern in a button-type secondary battery according to Example 1 of the present invention.
4 is a plan view illustrating a welding pattern in a button-type secondary battery according to a second embodiment of the present invention.
5 is an experimental result table showing the welding strength test results.

Hereinafter, preferred 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 implemented in several different forms and is not limited or limited by the following examples.

In order to clearly explain the present invention, detailed descriptions of parts irrelevant to the description or related known technologies that may unnecessarily obscure the gist of the present invention have been omitted, and in the present specification, reference signs are added to the components of each drawing. In this case, the same or similar reference numerals are assigned to the same or similar elements throughout the specification.

In addition, the terms or words used in the present specification and claims should not be construed as being limited to conventional or dictionary meanings, and the inventor appropriately defines the concept of the term in order to best describe his invention. Based on the principle that it can be done, it should be interpreted as meaning and concept consistent with the technical idea of the present invention.

Example 1

1 is a perspective view of a button-type secondary battery according to Example 1 of the present invention. FIG. 2 is a cross-sectional view taken along line A-A of FIG. 1 . 3 is a plan view illustrating a welding pattern in a button-type secondary battery according to Example 1 of the present invention.

1 to 3 , the button-type secondary battery 100 according to Embodiment 1 of the present invention may be a battery having a cylindrical shape, and the diameter of the cylindrical battery may be larger than the height of the battery. there is.

The button-type secondary battery 100 according to Embodiment 1 of the present invention may include an electrode assembly 130 , a can case 110 , and an electrode tab 150 . The electrode assembly 130 may be formed by alternately stacking the electrodes 131 and the separator 133 . The can case 110 may be a metal case in which the electrode assembly 130 is accommodated in the inner accommodation space. The electrode tab 150 is a part for connecting the current of the electrode 131 of the electrode assembly 130 to an external terminal, one side of which is connected to the electrode 131 of the electrode assembly 130 , and the other side of the can case 110 . ) may have a form connected through welding.

In the button-type secondary battery 100 according to the first embodiment of the present invention, in particular, the electrode tab 150 is welded to the can case 110 , and the welding part 113 , which is a portion where the electrode tab 150 is welded to the can case 110 . The welding pattern 190 shown in ) includes a circular shape 191 and an additional shape 193 added to the circular shape 191 . The additional shape 193 may be formed to increase the welding strength of the electrode tab 150 .

3 is a top plan view of the secondary battery according to the first embodiment of the present invention of FIG. 1 , and shows the welding pattern 190 in detail. In the button-type secondary battery 100 according to the first embodiment of the present invention, the circular shape 191 may be a circular shape 191 having one side open. When the circular shape 191 is made into a circular shape with a closed curve so that one side is not opened, a double welding area is generated. To prevent this, the circular shape 191 is a circular shape with one side open. can

In addition, in the button-type secondary battery 100 according to Embodiment 1 of the present invention, the opening angle α of the open portion in the circular shape 191 of the welding pattern 190 may be less than 120 degrees. In FIG. 3 , alpha (α) is shown. The meaning that the opening angle of the open part is less than 120 degrees may mean that the alpha (α) shown in FIG. 3 is less than 120 degrees. The angle alpha (α) may be an angle formed by the two straight lines when a straight line is drawn from the center point of the circle to both ends of the circular shape 191 . When the opening angle α of the open portion in the circular shape 191 is less than 120 degrees, it means that the welding length of the circular shape becomes longer by that much, so that the effect of further improving welding strength can be obtained. In addition, the opening angle α of the part opened in the circular shape 191 of the welding pattern 190 may be 30 degrees or more. When the opening angle α is set to 30 degrees or more, the force of the circular shape 191 attached to the can case 110 may not be weakened. That is, as the opening angle α increases, the number of portions in which the circular shape 191 is connected to the can case 110 increases, so that the force that the circular shape 191 is attached to the can case 110 may be large. In the button-type secondary battery 100 according to Embodiment 1 of the present invention, the welding pattern 190 includes an additional shape 193 , and the additional shape 193 may be in the form of a line segment. This additional shape 193 may also be inside the circular shape 191 described above. The appearance of this additional shape 193 is illustrated in detail in FIG. 3 .

Specifically, in the button-type secondary battery 100 according to Embodiment 1 of the present invention, the circular shape 191 is a circular shape 191 with one side open, and the additional shape 193 is a circular shape in the form of a line segment ( 191) may be formed on the inside. In addition, one end of the additional shape 193 in the form of a line segment may face an open portion of the circular shape 191 . In addition, the additional shape 193 in the form of a line segment may have a shape passing through the center point of the circle of the circular shape 191 . Here, the diameter of the circular shape may have a value between 1.0 mm and 2.0 mm. In addition, the thickness of the circular-shaped line may have a value between 100 um and 150 um. And the end of the additional shape may be within the range of an imaginary circle drawn by the circular shape. Through this, the welding strength at which the electrode tab is welded to the can case can be remarkably improved.

In addition, based on the additional shape 193 in the form of a line segment, the welding pattern 190 may have a symmetrical shape. When the welding pattern 190 has a symmetrical shape, more robust and stable welding strength may be realized.

FIG. 2 is a cross-sectional view taken along line A-A of FIG. 1 in a state in which welding is performed on the can case 110 to form a welding pattern 190 . That is, the method and shape of the welding pattern 190 can be grasped in more detail through FIG. 2 .

In the button-type secondary battery 100 according to the first embodiment of the present invention, the can case 110 may include an upper can (not shown) and a lower can 111 . In FIG. 2 , the upper can is not shown, and only the lower can 111 is shown. The electrode assembly 130 is accommodated in the lower can 111 . The electrode assembly 130 may be a jelly roll type electrode assembly 130 in which the electrode 131 and the separator 133 are alternately stacked and wound.

The electrode assembly 130 may be disposed in a shape in which a winding axis is perpendicular to the bottom portion 114 of the lower can 111 . A center hole 135 may be formed in the center of the jelly roll type electrode assembly 130 . As shown in FIG. 2 , the lower can 111 in which the electrode assembly 130 is accommodated may be turned upside down. And it can be supported by using a jig (J) from below and welding can be performed.

The jig J is inserted into the center hole 135 of the electrode assembly 130, and the jig J supports the electrode tab 150 in contact with the inner surface of the bottom 114 of the lower can 111 from bottom to top. can support Through the support of the jig J, the electrode tab 150 may be in close contact with the inner surface of the lower can 111 . And by irradiating the laser L from the outside of the lower can 111 to the bottom 114 of the lower can 111 to perform welding of the electrode tab 150 and the bottom 114 of the lower can 111 . there is. When the welding pattern 190 is formed in this way, the welding pattern 190 may be formed on the bottom part 114 of the lower can 111 , and the welding pattern 190 is the center hole of the electrode assembly 130 . It may be formed at a position corresponding to the position of 135 . In this case, the bottom part 114 of the lower can 111 may form a negative electrode terminal, and the electrode tab 150 welded to the bottom part 114 may be a negative electrode tab.

In addition, welding beads formed on the welding part 113 may be formed from the outside of the can case 110 to the inside.

Specifically, since the laser L is irradiated to the outside of the lower can 111 to weld the electrode tab 150 inside the lower can 111 and the lower can 111, the welding beads are the lower can ( 111) It may be formed from the outside of the bottom part 114 to the inside.

As described above, in the button-type secondary battery 100 according to the first embodiment of the present invention, the welding strength at which the electrode tab 150 is welded to the can case 110 can be significantly improved. Accordingly, the button-type secondary battery 100 having a high level of impact resistance and conditions to pass a mechanical test can be implemented.

Example 2

4 is a plan view illustrating a welding pattern in a button-type secondary battery according to a second embodiment of the present invention. 4 is a plan view of a welding pattern of Example 2 shown in the same manner as in FIG. 3 .

Embodiment 2 of the present invention may be different from Embodiment 1 in that the additional shape 293 of the welding pattern 290 is formed differently.

The contents common to the first embodiment will be omitted as much as possible and the second embodiment will be described with a focus on the differences. That is, it is obvious that, if the content not described in the second embodiment is necessary, it may be regarded as the content of the first embodiment.

Referring to FIG. 4 , even in the button-type secondary battery according to the second embodiment of the present invention, the welding pattern 290 may have a circular shape 291 in which one side is open in a circular shape 291 . Also, in the button-type secondary battery according to the second embodiment of the present invention, the opening angle of the part open in the circular shape 291 of the welding pattern 290 may be less than 120 degrees. When the opening angle of the part open in the circular shape 291 is less than 120 degrees, it means that the length to be welded becomes longer by that amount, so that the effect of further improving welding strength can be obtained.

Also in the second embodiment, the welding pattern 290 includes an additional shape 293, which may be in the form of a line segment. However, in the second exemplary embodiment, two additional shapes 293 in the form of the line segments may be formed. Of course, more than two additional shapes 293 in the form of line segments may be formed. And these additional shapes 293 may be side by side with each other.

This additional shape 293 may also be inside the circular shape 291 described above. An example of the appearance of such an additional shape 293 is illustrated in detail in FIG. 4 .

Specifically, in the button-type secondary battery according to the second embodiment of the present invention, the circular shape 291 is a circular shape 291 with one side open, and the additional shape 293 is a circular shape 291 in the form of two line segments. may be formed on the inside of In addition, each of the additional shapes 293 in the form of line segments may have one end facing the open portion of the circular shape 291 . Also, the two additional shapes 293 in the form of line segments may have the same length.

In addition, the welding pattern 290 according to the second embodiment including the circular shape 291 and the additional shape 293 in the form of two line segments may have a left-right symmetric shape. That is, the left and right sides may be symmetrical with respect to the virtual central vertical line between the two additional shapes 293 . When the welding pattern 290 has a symmetrical shape, more robust and stable welding strength may be realized.

<Experiment result>

5 is an experimental result table showing the welding strength test results. It is the result of performing a tumble test for the mechanical strength test. The table of FIG. 5 shows the number of samples in which defective welding was found after performing a tumble test on about 10 samples.

Referring to FIG. 5 , ①, ②, and ⑤ are welding patterns of Comparative Examples, and ③ and ④ are welding patterns of Examples. ① denotes a welding pattern according to Comparative Example 1, ② denotes a welding pattern according to Comparative Example 2, and ⑤ denotes a welding pattern according to Comparative Example 3. ③ is a welding pattern according to Example 1 of the present invention, ④ is a welding pattern according to Example 2 of the present invention.

In the case of welding with the welding pattern of Comparative Example 1, no defective samples appeared until the second experiment, but 2 out of 10 samples were found in the 3rd time and 1 out of 9 defective samples were found in the 4th time.

In the case of welding with the welding pattern of Comparative Example 2, no defective samples appeared until the first experiment, but 1 out of 10 in the second, 3 out of 10 in the 3rd, and 2 out of 10 in the 4th failed samples.

In both Examples 1 and 2, no defective samples were found even when the experiment was performed up to the fourth time. That is, in Examples 1 and 2, it can be seen that the welding strength is remarkably improved.

In the case of Comparative Example 3, it is a case of a welding pattern without a circular shape, and in this case, it can be seen that defective samples appear from the first to the fourth times. And from the 3rd time or more, it can be seen that all 10 out of 10 are defective.

Through this, it can be seen that the welding pattern without a circular shape has the weakest welding bonding strength among the test subjects.

In the above, 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. Various implementations are possible within the scope of equivalents of the claims to be made.

100: button type secondary battery
110: can case
111: lower can
113: weld
114: bottom
130: electrode assembly
131: electrode
133: separator
135: central hall
150: electrode tab
190, 290: welding pattern
191, 291: circular shape
193, 293: additional shape
L: laser
J: Jig

Claims (14)

an electrode assembly formed by alternately stacking electrodes and separators;
a can case in which the electrode assembly is accommodated in an internal accommodating space; and
One side is connected to the electrode of the electrode assembly, the other side includes an electrode tab connected to the can case through welding,
A welding pattern appearing in a welding portion where the electrode tab is welded to the can case includes a circular shape and an additional shape added to the circular shape. The method according to claim 1,
The circular shape is a button type secondary battery, characterized in that the circular shape with one side open. 3. The method according to claim 2,
An opening angle of the part open in the circular shape of the welding pattern is 30 degrees or more and less than 120 degrees. The method according to claim 1,
The additional shape is a button type secondary battery, characterized in that the line segment shape. The method according to claim 1,
The additional shape is a button type secondary battery, characterized in that on the inside of the circular shape. The method according to claim 1,
The circular shape is a circular shape with one side open,
The additional shape is formed inside the circular shape in the form of a line segment,
A button-type secondary battery, characterized in that one end of the line segment is directed toward the open portion of the circular shape. 7. The method of claim 6,
The diameter of the circular shape is a button type secondary battery, characterized in that having a value between 1.0 mm ~ 2.0 mm. 7. The method of claim 6,
The thickness of the circular-shaped line is a button type secondary battery, characterized in that it has a value between 100 um ~ 150 um. 7. The method of claim 6,
The end of the additional shape is a button type secondary battery, characterized in that within the range of the virtual circle drawn by the circular shape. 7. The method of claim 6,
Based on the additional shape of the line segment, the welding pattern has a symmetrical shape. 7. The method of claim 6,
At least two additional shapes in the form of line segments are formed,
A button type secondary battery, characterized in that the additional shapes are side by side with each other. The method according to claim 1,
The can case includes an upper can and a lower can,
The electrode assembly is a jelly roll-type electrode assembly in which the electrode and the separator are alternately stacked and wound,
A central hole is formed in the center of the winding of the jelly roll type electrode assembly,
The welding pattern is a button type secondary battery, characterized in that formed in a position corresponding to the position of the center hole. 13. The method of claim 12,
The welding pattern is a button type secondary battery, characterized in that formed on the bottom of the lower can. The method according to claim 1,
Welding beads formed in the welding portion are button-type secondary battery, characterized in that formed from the outside to the inside of the can case.

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