ELECTRICAL ENERGY STORAGE APPARATUS HAVING IMPROVED COUPLING STRUCTURE OF INTERNAL TERMINAL

Abstract

An electric energy storage device in which a cell assembly having electrode leads is installed in a metal case. The electric energy storage device includes an internal terminal formed with a support, connection ribs and thorough portions, and the electrode leads include a part of electrode leads compressed by the support and the connection ribs of the internal terminal and a part of electrode leads located at the thorough portions of the internal terminal to maintain a shape thereof.

Claims

1. An electric energy storage device in which a cell assembly having electrode leads is installed in a metal case, the electric energy storage device comprising: an internal terminal (120) formed with a support (121), connection ribs (122) and thorough portions (127) so that lower surfaces of the support (121) and the connection ribs (122) come into contact with a part of the electrode leads (110), wherein the electrode leads (110) include a part of electrode leads compressed by the support (121) and the connection ribs (122) of the internal terminal (120) and another part of electrode leads located at the thorough portions (127) of the internal terminal (120) to maintain a shape thereof.

2. The electric energy storage device according to claim 1, wherein the support (121) is located at a center of the internal terminal (120), and wherein the connection ribs (122) are arranged at a periphery of the support (121) at regular intervals with a rod shape.

3. The electric energy storage device according to claim 2, wherein an electrolyte impregnation hole (124) is formed at a center of the support (121).

4. The electric energy storage device according to claim 2, further comprising: at least one reinforcing rib (125) extending in a circumferential direction of the internal terminal (120) to connect the connection ribs (122) to each other.

5. The electric energy storage device according to claim 1, wherein the electrode leads (110) are compressed according to the shape of the internal terminal (120) after cutting a portion thereof corresponding to both side surfaces (122a) of the connection ribs (122) by a cutting device.

6. The electric energy storage device according to claim 2, wherein the plurality of connection ribs (122) have flanges (126) formed at ends thereof to correspond to an inner wall of the metal case (150).

7. The electric energy storage device according to claim 1, wherein a contact area of the internal terminal (120), which comes into contact with the electrode leads (110), is 60% or above of an entire sectional area of the electrode leads (110).

Description

BRIEF DESCRIPTION OF DRAWINGS

[0023] The accompanying drawings illustrate a preferred embodiment of the present disclosure and together with the foregoing disclosure, serve to provide further understanding of the technical features of the present disclosure, and thus, the present disclosure is not construed as being limited to the drawing.

[0024] FIG. 1 is a partial cross-sectional view showing an electric energy storage device of an existing technique.

[0025] FIG. 2 is a perspective view showing an appearance of an internal terminal depicted in FIG. 1.

[0026] FIG. 3 is a partial cross-sectional view showing an electric energy storage device according to an embodiment of the present disclosure.

[0027] FIG. 4 is a perspective view showing a coupling relation between the internal terminal and leads, depicted in FIG. 3.

[0028] FIG. 5 is a bottom view showing the internal terminal depicted in FIG. 3.

[0029] FIG. 6 is a perspective view of FIG. 5.

[0030] FIG. 7 is a bottom view showing a modification of FIG. 5.

[0031] FIG. 8 is a perspective view of FIG. 7.

[0032] FIG. 9 is a flowchart for illustrating a process of manufacturing an electric energy storage device according to an embodiment of the present disclosure.

[0033] FIG. 10 is a plane view schematically showing an example where a lead of a cell assembly is partially cut corresponding to a side of a connection rib.

[0034] FIG. 11 is a plane view schematically showing an example where the lead of the cell assembly is compressed.

[0035] FIG. 12 is a plane view showing an example where the internal terminal is disposed at the compressed portion of the lead depicted in FIG. 9.

DETAILED DESCRIPTION OF THE INVENTION

[0036] FIG. 3 is a cross-sectional view showing an electric energy storage device according to an embodiment of the present disclosure.

[0037] Referring to FIG. 3, the electric energy storage device according to an embodiment of the present disclosure includes a cell assembly 100, a cylindrical metal case 150 accommodating the cell assembly 100, an internal terminal 120 disposed inside an end of the metal case 150 and connected to the cell assembly 100 and having a radial body, and an external terminal 130 exposed to the outside in contact with the internal terminal 120.

[0038] The cell assembly 100 may adopt a general cell for an ultra-capacitor, in which a positive electrode plate and a negative electrode plate are wound together with a separator being interposed therebetween to form a jelly-roll shape. Electrode leads 110 respectively connected to the positive electrode plate and the negative electrode plate are located at both end surfaces of the cell assembly 100.

[0039] The metal case 150 has a cylindrical body with an internal space for accommodating the cell assembly 100. Preferably, the metal case 150 may be provided using an aluminum cylinder.

[0040] The internal terminal 120 connected to the electrode leads 110 of the cell assembly 100 is disposed adjacent to both longitudinal ends of the metal case 150, and the external terminal 130 coming into contact with the internal terminal 120 is disposed outside the internal terminal 120. Though FIG. 3 shows only the internal terminal 120 and the external terminal 130 disposed at the upper side of the metal case 150, an internal terminal and an external terminal are also provided at the lower side of the metal case 150.

[0041] The external terminal 130 is exposed out of the metal case 150 and has a circular outer circumferential surface corresponding to the inner circumferential surface of the metal case 150, and its overall shape may be configured with various three-dimensional shapes.

[0042] A hollow 140 extending in a thickness direction is formed at the center of the upper external terminal 130. The hollow 140 is used, for example, as a space for installing an automatic reset safety valve 141 as well as a path for injecting an electrolyte and an air vent for vacuum operation.

[0043] A curling portion 151 is provided at the upper end of the metal case 150 near the external terminal 130, and the curling portion 151 is formed to slightly curl toward the inside of the metal case 150 and prevents the external terminal 130 from being deviated.

[0044] As shown in FIG. 4, the internal terminal 120 is coupled to the cell assembly 100. In other words, the internal terminal 120 is disposed on the cell assembly 100 and is compressed by and welded to some electrode leads 110, while allowing other some electrode leads 110 to pass therethrough in the thickness direction of the body so as to maintain the shape thereof. The degree of compression of the electrode leads 110 and the thickness of the internal terminal 120 determine a top position of the electrode leads 110 which moves up through the internal terminal 120. Accordingly, the upper end of the electrode leads 110 moving up through the internal terminal 120 may be positioned higher than the upper surface of the internal terminal 120, or may be positioned at the same point as or a slightly lower point than the upper surface of the internal terminal 120.

[0045] In order to implement the coupling relation between the internal terminal 120 and the electrode leads 110, as shown in FIGS. 5 and 6, the internal terminal 120 includes a support 121 of a predetermined shape and a plurality of connection ribs 122 extending radially from the support 121. Preferably, the support 121 and the connection ribs 122 are integrally formed using a metal plate.

[0046] The support 121 has a plate-shaped body of a predetermined shape with an electrolyte impregnation hole 124 formed at the center thereof.

[0047] Each connection rib 122 is in the form of a bar, and the connection ribs 122 are arranged at regular intervals around the support 121 such that the bottom of the support 121 and the plurality of connection ribs 122 are in contact with a part of the electrode leads 110.

[0048] Empty spaces 123 are naturally formed between the connection ribs 122 due to the structure in which the plurality of connection ribs 122 are radially arranged at predetermined intervals. The empty space 123 serves as a thorough portion 127 (see FIG. 11) that maintains the shape of some electrode leads 110 when the internal terminal 120 is coupled to the electrode leads 110. In other words, the empty space 123 is the thorough portion 127.

[0049] The internal terminal 120 has a flange 126 formed to extend vertically upward so that the end of the connection rib 122 corresponds to the inner wall of the cylindrical metal case 150. The flange 126 is tightly coupled by wrapping the lower edge of the external terminal 130.

[0050] As shown in FIGS. 7 and 8, the internal terminal 120 further include at least one reinforcing rib 125 connecting the connection ribs 122 to each other. The reinforcing rib 125 provides a function of regulating a contact area with the electrode leads 110 together with a reinforcement function for the internal terminal 120. Preferably, the reinforcing rib 125 is integrally formed with the connection ribs 122 and extends circularly in the circumferential direction of the internal terminal 120 to connect the plurality of connection ribs 122 to each other.

[0051] FIG. 9 shows a main process for manufacturing an electric energy storage device according to an embodiment of the present disclosure.

[0052] Referring to FIG. 9, in the method of manufacturing an electric energy storage device according to an embodiment of the present disclosure, first, a jelly-roll-type cell assembly 100 is prepared, and then processes such as a lead cutting process (Step S100), a partial lead compressing process (Step S110), an internal terminal arranging process (Step S120), and a laser welding process (Step S130) are performed in order.

[0053] In the lead cutting process (Step S100), by using a predetermined cutting device, as shown in FIG. 10, a portion 101 of the electrode lead 110 corresponding to both side surfaces 122a of the connection rib 122 of the internal terminal 120 is cut, and the electrode lead 110 corresponding to the support 121 proceeds to a following process without being cut.

[0054] In the partial lead compressing process (Step S110), a physical pressure is applied to the partially cut region by using a predetermined pressing device to form a compressed portion 102 as shown in FIG. 11. Here, the overall shape of the compressed portion 102 coincides with the shape of the internal terminal 120.

[0055] In the internal terminal arranging process (Step S120), as shown in FIG. 12, the internal terminal 120 is placed at the compressed portion 102. At this time, the portion of the electrode lead 110 other than the compressed portion 102 passes through the empty spaces 123 between the connection ribs 122 formed at the internal terminal 120, thereby maintaining the shape thereof without being pressed by the internal terminal 120. Here, in the internal terminal 120, the number and area of the connection ribs 122 should be are determined to maintain the shape of the electrode leads 110 as much as possible and have an appropriate contact area with respect to the electrode lead 110. Considering the contact resistance characteristics between the internal terminal 120 and the electrode leads 110, the contact area of the internal terminal 120 contacting the electrode leads 110 may be 60% or above of the entire sectional area of the electrode lead 110 exposed out of the cell assembly 100. If the contact area is less than 60%, the contact resistance between the internal terminal 120 and the electrode leads 110 is excessively increased.

[0056] In the laser welding process (Step S130), laser welding is performed to the support 121 and the connection ribs 122 of the internal terminal 120 to completely couple between the internal terminal 120 and the electrode leads 110.

[0057] After the internal terminal 120 and the electrode leads 110 are completely coupled as described above, the external terminal 130 is coupled to the outside of the internal terminal 120, and the electric energy storage device is sealed after assembling and curling the metal case 150.

[0058] Even though it has been illustrated in the present disclosure that after the lead cutting process (Step S100) is performed, the partial lead compressing process (Step S110) is performed and then the internal terminal arranging process (Step S120) is performed. However, it is also possible that after the lead cutting process (Step S100), the internal terminal arranging process (Step S120) may be performed by partially compressing the leads using the internal terminal 120 without the partial lead compressing process (Step S110).

[0059] As described above, in the electric energy storage device according to the present disclosure, the shape of a part of the electrode leads 110 may be maintained when the internal terminal 120 and the electrode leads 110 are coupled, and thus electrolyte penetration and internal gas release may be smoothly performed, which is a remarkable effect.

[0060] Although the present disclosure has been described by way of the limited embodiments and drawings, the present disclosure is not limited thereto, and it will be understood by those skilled in the art that various modifications and changes can be made without departing from the scope of the appended claims. For example, even though it has been illustrated and explained in the above embodiments and the accompanying drawings that the internal terminal 120 and the electrode leads 110 are disposed at the upper side of the metal case 150, the structure and the coupling relation of the internal terminal 120 and the electrode leads 110 are also applicable to an internal terminal and electrode leads disposed at the lower side of the metal case 150.

INDUSTRIAL APPLICABILITY

[0061] If the present disclosure is applied, it is possible to implement an electric energy storage device with improved process efficiency and safety by means of enhanced electrolyte impregnation and internal gas release performance.