Secondary battery

Abstract

The present invention relates to a secondary battery in which an electrode assembly and a current collector can be easily welded and safety can be improved. As an embodiment, a secondary battery is disclosed, the secondary battery comprising: an electrode assembly formed by winding a first electrode plate having a first electrode uncoated portion, a separator, and a second electrode plate having a second electrode uncoated portion, the first electrode uncoated portion protruding upward, and the second electrode uncoated portion protruding downward; and a first current collector electrically connected to the first electrode uncoated portion and having a concave-convex portion protruding downward, wherein the width of the concave-convex portion widens from the center of the first current collector toward the periphery of the first current collector.

Description

Technical Field

[0001] The present invention relates to a secondary battery. Background Art

[0002] Unlike primary batteries that cannot be charged, secondary batteries can be repeatedly charged and discharged. Low-capacity batteries including battery cells in the form of a group can be used in small portable electronic devices such as cellular phones or cameras, while high-capacity batteries including dozens of battery cells connected to each other can be used as a power source for driving motors (e.g., hybrid vehicles, etc.).

[0003] Such secondary batteries are manufactured in various shapes, and representative examples of the shapes may include cylindrical shapes, prismatic shapes, and pouch shapes. The secondary battery is constructed by inserting an electrolyte and an electrode assembly into a case and installing a cover plate in the case, and the electrode assembly is formed by placing a separator as an insulator between a positive electrode plate and a negative electrode plate.

[0004] The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not constitute the prior art. Summary of the invention

[0005] Technical issues

[0006] The present invention provides a secondary battery in which an electrode assembly and a current collecting plate can be easily welded and safety can be improved.

[0007] Technical Solution

[0008] According to the present invention, a secondary battery is provided, which includes: an electrode assembly formed by winding a first electrode plate having a first electrode uncoated portion, a separator, and a second electrode plate having a second electrode uncoated portion, the first electrode uncoated portion protruding upward, and the second electrode uncoated portion protruding downward; and a first current collecting plate electrically connected to the first electrode uncoated portion and having a concave-convex portion protruding downward, wherein the width of the concave-convex portion widens from the center of the first current collecting plate toward the periphery of the first current collecting plate.

[0009] The first current collecting plate may include a first through hole formed in a center and a plurality of second through holes formed outside the first through hole.

[0010] The concavo-convex portion may have a plurality of concavo-convex portions formed to be spaced apart outside the first through hole.

[0011] The first electrode non-coating portion may include a pressurized region that is partially pressurized to be flatly formed, and the concavo-convex portion may be welded to the pressurized region.

[0012] The pressurized area may be formed to increase in width from the center of the electrode assembly toward the outer circumference of the electrode assembly to correspond to the concavo-convex portion.

[0013] The first current collecting plate may further include a position identification part formed at an outer side of the first through hole.

[0014] The position identification part may be formed with a plurality of grooves or holes, and may be located inside the second through hole.

[0015] The position identifying portion may be formed in an embossed shape.

[0016] The position identification part may be formed of marks having different shapes so as to be spaced apart from each other.

[0017] The secondary battery may further include a circular second current collecting plate electrically connected to the second electrode non-coating portion and having a concavoconvex portion protruding upward, and a width of the concavoconvex portion widens from a center toward an outer circumference of the second current collecting plate.

[0018] Disclosure of beneficial effects

[0019] The secondary battery according to the embodiment of the present invention includes a current collecting plate in which a concavo-convex portion widens from the center toward the periphery, so that the compaction level of the pressurized area to which the concavo-convex portion of the electrode uncoated portion is welded can be constant. Therefore, the weldability between the current collecting plate and the electrode assembly can be improved, and a short circuit of the electrode assembly can be prevented.

[0020] In addition, in the secondary battery according to the embodiment of the present invention, by forming the position recognition part on the current collecting plate, the scanning time for recognizing the welding position can be shortened, and the welding position accuracy can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a cross-sectional view showing a secondary battery according to an embodiment of the present invention.

[0022] Figure 2 is an exploded perspective view showing a portion of a secondary battery according to an embodiment of the present invention.

[0023] Figure 3 It is shown Figure 2 A plan view of the first current collecting plate shown in FIG.

[0024] Figure 4 is a plan view showing a first current collecting plate according to another embodiment of the present invention.

[0025] Figure 5 is a plan view showing a first current collecting plate according to another embodiment of the present invention. DETAILED DESCRIPTION

[0026] Hereinafter, exemplary embodiments of the present invention will be described in detail.

[0027] However, the subject matter of the present invention can be implemented in many different forms and should not be interpreted as being limited to the example (or exemplary) embodiments set forth herein. On the contrary, these example embodiments are provided so that this disclosure will be thorough and complete, and will convey aspects and features of the present invention to those skilled in the art.

[0028] In addition, in the accompanying drawings, the size or thickness of various components is exaggerated for simplicity and clarity. The same reference numerals always refer to the same elements. As used herein, the term "and / or" includes any and all combinations of one or more of the related listed items.

[0029] The terms used herein are only used for the purpose of describing specific embodiments and are not intended to limit disclosure. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. It will also be understood that when used in this specification, the term "comprise or include" and / or its variations indicate the presence of stated features, numbers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, numbers, steps, operations, elements, components and / or their groups.

[0030] Figure 1 is a cross-sectional view showing a secondary battery according to an embodiment of the present invention. Figure 2 is an exploded perspective view showing a portion of a secondary battery according to an embodiment of the present invention. Figure 3 It is shown Figure 2 A plan view of the first current collecting plate shown in FIG.

[0031] Reference Figure 1 and Figure 2 , a secondary battery according to an embodiment of the present invention includes an electrode assembly 110 , a first current collecting plate 120 , a second current collecting plate 130 , a case 140 , and a cap assembly 150 .

[0032] The electrode assembly 110 includes a first electrode plate 111, a second electrode plate 112, and a separator 113 disposed between the first electrode plate 111 and the second electrode plate 112. The electrode assembly 110 may be formed by winding a stack of the first electrode plate 111, the separator 113, and the second electrode plate 112 into a jelly roll form. Here, the first electrode plate 111 may be used as a positive electrode, and the second electrode plate 112 may be used as a negative electrode.

[0033] The first electrode plate 111 is formed by coating a first electrode active material such as a transition metal oxide on a first electrode current collector formed of a metal foil such as aluminum. A first electrode uncoated portion 111a not coated with the first electrode active material is formed on the first electrode plate 111, and the first current collector 120 is electrically connected to the first electrode uncoated portion 111a.

[0034] The second electrode plate 112 is formed by coating a second electrode active material such as graphite or carbon on a second electrode current collector formed of a metal foil such as copper or nickel. A second electrode non-coating portion 112a to which the second electrode active material is not applied is formed on the second electrode plate 112, and the second current collecting plate 130 is electrically connected to the second electrode non-coating portion 112a.

[0035] The first current collecting plate 120 is coupled to the upper portion of the electrode assembly 110 and is electrically connected to the first electrode non-coating portion 111a. The first current collecting plate 120 is formed of a circular plate to correspond to the transverse cross-section of the electrode assembly 110. The first current collecting plate 120 includes concavo-convex portions 121 and through holes 122.

[0036] The concavo-convex part 121 is formed in the form of a groove protruding downward from the first current collecting plate 120, and a plurality of concavo-convex parts 121 may be formed. Figure 2 As shown in , the concavoconvex portion 121 is composed of four grooves and may be arranged in a "+" shape. That is, each concavoconvex portion 121 may be arranged to be spaced apart at intervals of 90 degrees relative to the center of the first current collecting plate 120. At the same time, in the present invention, the number of concavoconvex portions 121 is not limited, and four or more concavoconvex portions 121 or less than four concavoconvex portions 121 may be formed. The concavoconvex portion 121 may be welded to the first electrode uncoated portion 111a of the electrode assembly 110. Here, the concavoconvex portion 121 may be connected to the first electrode uncoated portion 111a by laser welding, ultrasonic welding, resistance welding, or the like. In addition, before the concavoconvex portion 121 is connected to the first electrode uncoated portion 111a, a compaction process that flattens the first electrode uncoated portion 111a is performed by pressing a portion of the first electrode uncoated portion 111a, and the first electrode uncoated portion 111a may be easily welded to the concavoconvex portion 121. Here, a region flatly formed by pressing the first electrode non-coated portion 111 a is defined as a pressurized region 111 b .

[0037] In addition, refer to Figure 3, the uneven portion 121 is formed in a trapezoidal shape in which its width becomes wider from the center of the first current collector plate 120 toward the outer periphery of the first current collector plate 120. That is, the uneven portion 121 is formed such that the width D1 at the center of the first current collector plate 120 is narrower than the width D2 at the outermost side (D1 < D2). This is for the purpose of evenly pressing the pressurized area 111b to a predetermined depth in the compaction process of pre-pressing the uncoated portion 111a of the first electrode to make it flat. Generally, since the electrode assembly 110 wound in the form of a gel roll has a larger curvature at the center of the winding than at the end of the winding, if the electrode assembly 110 is pressed with the same area and the same force from the center of the winding to the end of the winding, the electrode assembly 110 is pressed more at the end of the winding. Therefore, in the present invention, the width of the uneven portion 121 is formed such that the width gradually becomes wider (increases) from the center to the outermost part, and the pressurized area 111b to which the uneven portion 121 of the uncoated portion 111a of the first electrode is welded is also formed to become wider (increase) in width from the center to the outermost part of the electrode assembly 110, so as to make the compaction level of the pressurized area 111b constant. That is, even when the uncoated portion 111a of the first electrode is pressed with the same force during the compaction process, the pressurized area 111b has a shape in which the area of the pressurized area 111b becomes wider (increases) toward the outer periphery of the electrode assembly 110, so that the depth of the pressurized area 111b in the uncoated portion 111a of the first electrode can be the same. Therefore, according to the present invention, the weldability between the first current collector plate 120 and the electrode assembly 110 can be improved, and short circuits of the electrode assembly 110 can be prevented.

[0038] The through hole 122 is a hole into which an electrolyte is injected, and a plurality of through holes may be formed in the first current collector plate 120. Specifically, the through hole 122 may include a first through hole 123 formed in the center of the first current collector plate 120 and a second through hole 124 formed between the uneven portions 121. In addition, the number of the second through holes 124 may be smaller than the number of the uneven portions 121. Therefore, there is at least a region where the second through hole 124 is not formed between the uneven portions 121. The lead tab 125 may be bonded to the region where the second through hole 124 is not formed. The lead tab 125 may be connected to the lid assembly 150 to electrically connect the first current collector plate 120 to the lid assembly 150. That is, one end of the lead tab 125 is electrically connected to the first current collector plate 120, and the other end of the lead tab 125 is electrically connected to the lid assembly 150. Of course, the lead tab 125 may be integrally formed with the first current collector plate 120. For example, a part of the first current collector plate 120 may be formed to extend to constitute the lead tab 125, and the lead tab 125 may be bent to be electrically connected to the lid assembly 150.

[0039] The second current collecting plate 130 is coupled to the lower portion of the electrode assembly 110 and is electrically connected to the second electrode non-coating portion 112a. The second current collecting plate 130 is formed of a circular plate to correspond to the transverse cross-section of the electrode assembly 110. The second current collecting plate 130 includes a concavo-convex portion 131, a through hole 132, and a connection portion 135.

[0040] The concavo-convex part 131 is formed in the form of a groove protruding upward from the second current collecting plate 130, and a plurality of concavo-convex parts 131 may be formed. Figure 2 As shown in , the concavo-convex part 131 may have four grooves and may be arranged in a "+" shape. That is, the concavo-convex part 131 of the second current collecting plate 130 and the concavo-convex part 121 of the first current collecting plate 120 are formed in the same manner, but are different from each other only in that their protruding directions are opposite to each other. Therefore, the following description will focus on the difference between them.

[0041] The concavoconvex portion 131 may be welded to the second electrode uncoated portion 112a of the electrode assembly 110. In addition, as with the first electrode uncoated portion 111a, a compaction process for flattening the second electrode uncoated portion 112a may be performed by pressing a portion of the second electrode uncoated portion 112a, and the concavoconvex portion 131 may be easily welded to the second electrode uncoated portion 112a. In addition, the concavoconvex portion 131 is formed in a trapezoidal shape in which the width of the concavoconvex portion 131 widens from the center of the second current collecting plate 130 to the periphery of the second current collecting plate 130. The concavoconvex portion 131 may be welded to the second electrode uncoated portion 112a of the electrode assembly 110.

[0042] The through hole 132 is a hole through which the electrolyte moves, and a plurality of through holes may be formed in the second current collecting plate 130. The through hole 132 may be formed between the concave and convex parts 131. In addition, a connection part 135 is formed in the center of the second current collecting plate 130. That is, the connection part 135 is formed in a portion corresponding to the position where the first through hole 123 is formed in the first current collecting plate 120. The connection part 135 is formed to protrude downward from the second current collecting plate 130. The connection part 135 is electrically connected to the lower surface plate 142 of the housing 140 to be described later. For example, the connection part 135 may be electrically connected to the housing 140 by laser welding, ultrasonic welding, resistance welding, etc.

[0043] The case 140 includes a side plate 141 as a cylindrical body having a predetermined diameter to form a space in which the electrode assembly 110 is accommodated, and a lower surface plate 142 that seals the lower portion of the side plate 141. The upper opening of the case 140 is opened to be sealed after the electrode assembly 110 is inserted. In addition, a crimping portion 143 for preventing the electrode assembly 110 from moving is formed on the upper portion of the case 140. A pleated portion 144 for fixing the cap assembly 150 is formed at the uppermost end of the case 140.

[0044] The cap assembly 150 includes an upper cap 151, a safety vent 152 coupled to a lower portion of the upper cap 151, a lower cap 153 coupled to a lower portion of the safety vent 152, an insulator 154 positioned between the safety vent 152 and the lower cap 153, a sub-plate 155 coupled to a lower portion of the lower cap 153 and electrically connected to the safety vent 152, and a gasket 156 interposed between an outer periphery of the safety vent 152 and the case 140. The sub-plate 155 is electrically connected to the lead tab 125 of the first current collecting plate 120.

[0045] A method for manufacturing the secondary battery having the above configuration will now be briefly described.

[0046] First, the electrode assembly 110 is formed by winding a stack of a first electrode plate 111, a second electrode plate 112, and a separator 113 disposed between the first electrode plate 111 and the second electrode plate 112. In addition, a pressurized region 111b is formed in the first electrode uncoated portion 111a protruding upward of the electrode assembly 110. Here, the pressurized region 111b has a "+" shape to correspond to the concavo-convex portion 121 of the first current collecting plate 120, and is formed so that its width widens from the central region toward the outermost portion. Similarly, a pressurized region is also formed in the second electrode uncoated portion 112a protruding downward from the electrode assembly 110.

[0047] Next, the first current collecting plate 120 is coupled to the upper portion of the electrode assembly 110, and the second current collecting plate 130 is coupled to the lower portion of the electrode assembly 110. Specifically, the pressurized area 111b formed on the first electrode non-coating portion 111a of the electrode assembly 110 and the concavo-convex portion 121 of the first current collecting plate 120 are welded to each other, and the concavo-convex portion 131 of the second current collecting plate 130 is welded to the pressurized area formed in the second electrode non-coating portion 112a.

[0048] Then, the electrode assembly 110 to which the first current collecting plate 120 and the second current collecting plate 130 are coupled is inserted into the case 140, the connection portion 135 of the second current collecting plate 130 and the lower surface plate 142 of the case 140 are electrically connected to each other by welding, and the lead tab 125 of the first current collecting plate 120 is electrically connected to the sub-plate 155 of the cap assembly 150 by welding. Next, an electrolyte solution is injected into the case 140, and the cap assembly 150 is coupled to the upper end of the case 140, thereby completing the secondary battery 100 according to the present invention.

[0049] Figure 4 is a plan view showing a first current collecting plate according to another embodiment of the present invention.

[0050] Reference Figure 4 , the first current collecting plate 220 according to another embodiment of the present invention includes a concavo-convex portion 121 , a through hole 122 , and a position identification portion 226 .

[0051] The position identification portion 226 is a mark for identifying the position to be welded when the welding device (not shown) welds the first current collecting plate 220 to the electrode assembly 110 by using the automatic position alignment (APA) technology. The position identification portion 226 is formed around the first through hole 123 and inside the second through hole 124. In addition, the position identification portion 226 is composed of four holes that can be arranged to be separated at intervals of 90 degrees. Moreover, the diameter of the hole 226 is smaller than the diameter of the second through hole 124. In addition, although shown in the drawings as having a circular shape, the hole 226 can be formed in various shapes such as a square shape, a pentagonal shape, etc.

[0052] For example, if the position identification portion 226 is not formed on the first current collecting plate 220, the welding device should scan the region S2 including the second through hole 124 to identify the welding position. However, as in the present invention, when the position identification portion 226 is formed on the first current collecting plate 220, only the region S1 including the position identification portion 226 needs to be scanned, thereby enabling fast and accurate welding. In addition, the position identification portion 226 can be formed not only on the first current collecting plate 220, but also on the second current collecting plate 130. In this case, the position identification portion 226 formed on the second current collecting plate 130 can be arranged around the connection portion 135.

[0053] As described above, according to the present invention, the first current collecting plate 220 having the position identifying portion 226 formed inside the second through hole 124 and having a plurality of holes having a diameter smaller than that of the second through hole 124 is provided, thereby shortening the scanning time for identifying the welding position and improving the welding position accuracy.

[0054] Figure 5 is a plan view showing a first current collecting plate according to another embodiment of the present invention.

[0055] Reference Figure 5 According to another embodiment of the present invention, the first current collecting plate 320 includes a concave-convex portion 121, a through hole 122, and a position identification portion 326. The position identification portion 326 may be formed by markings having different shapes. For example, the position identification portion 326 may be arranged with different numbers of holes or grooves outside the first through hole 123, and the holes or grooves have a substantially rectangular shape. Specifically, as Figure 5 As shown in , the position identification part 326 may be arranged outside the first through hole 123 in such a manner that the number of rectangular holes or grooves gradually increases. In addition, the position identification part 326 may be formed in an embossed shape to protrude from the first current collecting plate 320 .

[0056] Although the foregoing embodiments have been described to practice the secondary battery of the present invention, those skilled in the art will understand that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the claims.

Claims

1. A secondary battery, comprising: an electrode assembly formed by winding a first electrode plate having a first electrode uncoated portion, a separator, and a second electrode plate having a second electrode uncoated portion, the first electrode uncoated portion protruding upward, and the second electrode uncoated portion protruding downward; as well as a first current collecting plate electrically connected to the first electrode non-coating portion and having a concavo-convex portion protruding downward in the form of a groove, wherein the first electrode uncoated portion includes a pressurized area that is partially pressurized to be flatly formed, and the concavo-convex portion is welded to the pressurized area, wherein the width of the pressurized area of ​​the first electrode non-coating portion is formed such that the width gradually widens from the center of the electrode assembly to the outermost portion of the electrode assembly, and Among them, the flat lower surface of the pressed pressurized area of ​​the concavo-convex part widens from the center of the first current collecting plate toward the periphery of the first current collecting plate, and the width of the concavo-convex part is formed so that the width gradually widens from the center of the first current collecting plate to the outermost part of the first current collecting plate to correspond to the pressurized area.

2. The secondary battery according to claim 1, wherein The first current collecting plate includes a first through hole formed in a center and a plurality of second through holes formed outside the first through hole.

3. The secondary battery according to claim 2, wherein: The concavo-convex portion has a plurality of concavo-convex portions formed to be spaced apart outside the first through hole.

4. The secondary battery according to claim 2, wherein The first current collecting plate further includes a position identification portion formed outside the first through hole.

5. The secondary battery according to claim 4, wherein The position identification part is formed with a plurality of grooves or holes and is located at an inner side of the second through hole close to the first through hole.

6. The secondary battery according to claim 4, wherein The position recognition portion is formed in an embossed shape.

7. The secondary battery according to claim 4, wherein The position identification portion is formed of marks having different shapes so as to be spaced apart from each other.

8. The secondary battery according to claim 1, further comprising a circular second current collecting plate electrically connected to the second electrode non-coating portion and having a concavo-convex portion protruding upward in the form of a groove, wherein The width of the concavo-convex portion widens from the center of the second current collecting plate toward the outer periphery of the second current collecting plate.

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