Electrode assembly having compact electrode tabs and secondary battery using the same

Abstract

An embodiment of the present invention provides an electrode assembly in which a plurality of electrode tabs is made more compact inside an exterior case and a secondary battery using the same. An electrode assembly according to the embodiment of the present invention includes: a plurality of first plates of a first polarity; a plurality of second plates of a second polarity alternately arranged with the first plates; at least one of a plurality of first tabs or a plurality of second tabs extending from the first plates or the second plates, respectively, the at least one of the plurality of first tabs or the plurality of second tabs being together wound or bent more than once; a plurality of separators interposed between the first plates and the second plates; and a lead physically coupled to at least one of the first tabs or the second tabs.

Claims

1. An electrode assembly comprising: a plurality of first plates of a first polarity; a plurality of second plates of a second polarity alternately arranged with the first plates; at least one of a plurality of first tabs or a plurality of second tabs extending from the first plates or the second plates, respectively, the at least one of the plurality of first tabs or the plurality of second tabs being together wound or bent more than once; a plurality of separators interposed between the first plates and the second plates; and a lead physically coupled to at least one of the first tabs or the second tabs, wherein a first surface of the lead contacts an innermost tab and a second surface of the lead contacts an outermost tab of the at least one of the plurality of first tabs or the plurality of second tabs, the first surface and the second surface being opposite surfaces of the lead.

2. The electrode assembly of claim 1, wherein the first plates, the second plates and the separators between the first plates and the second plates are laminated together.

3. The electrode assembly of claim 1, wherein the at least one of the plurality of first tabs or the plurality of second tabs are wound.

4. The electrode assembly of claim 1, wherein the at least one of the plurality of first tabs or the plurality of second tabs extend from the first plates or the second plates, respectively, by different draw-out lengths.

5. The electrode assembly of claim 4, wherein the different draw-out lengths of the at least one of the plurality of first tabs or the plurality of second tabs sequentially increase from a first side of the electrode assembly to a second side of the electrode assembly.

6. The electrode assembly of claim 1, wherein the at least one of the plurality of first tabs or the plurality of second tabs is located between end points defining the thickness of the electrode assembly.

7. The electrode assembly of claim 1, wherein the lead is wound together with the at least one of the plurality of first tabs or the plurality of second tabs.

8. A secondary battery comprising the electrode assembly of claim 1 and a case enclosing the first plates, the second plates, the first tabs, the second tabs, and the separators and partially enclosing the lead, the lead being physically coupled to the at least one of the first tabs or the second tabs only at a region within the case.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The accompanying drawings, together with the specification, illustrate exemplary embodiments of the present invention, and, together with the description, serve to explain the principles of the present invention.

(2) FIG. 1 is an exploded perspective view of a secondary battery according to a first embodiment of the present invention.

(3) FIG. 2 is a perspective view of a secondary battery according to the first embodiment of the present invention.

(4) FIG. 3 is a cross-sectional view taken along line A-A′ of FIG. 2.

(5) FIG. 4 is an exploded cross-sectional view of an electrode assembly according to a second embodiment of the present invention.

(6) FIG. 5 is a cross-sectional view showing a wound electrode tab and a lead which are bonded to each other according to a third embodiment of the present invention.

(7) FIG. 6 is a cross-sectional view showing a bent electrode tab and a lead which are bonded to each other according to a fourth embodiment of the present invention.

(8) FIG. 7 is a cross-sectional view showing a bent electrode tab and a lead which are bonded to each other according to a fifth embodiment of the present invention.

(9) FIG. 8 is a cross-sectional view showing a bent and wound electrode tab and a lead which are bonded to each other according to a sixth embodiment of the present invention.

(10) FIG. 9 is a cross-sectional view showing a bent and wound electrode tab and a lead which are bonded to each other according to a seventh embodiment of the present invention.

(11) FIG. 10A is a cross-sectional view showing an electrode tab and a lead which are wound together according to an eighth embodiment of the present invention.

(12) FIG. 10B is a cross-sectional view showing a lead which is bent in a direction opposite to an electrode assembly according to the eighth embodiment of the present invention.

DETAILED DESCRIPTION

(13) In the following detailed description, only certain exemplary embodiments of the present invention have been shown and described, by way of illustration. As those skilled in the art would recognize, the described embodiments may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Accordingly, the drawings and description are to be regarded as illustrative in nature and not restrictive. In addition, when an element is referred to as being “on” another element, it can be directly on the another element or be indirectly on the another element with one or more intervening elements interposed therebetween. Also, when an element is referred to as being “connected to” another element, it can be directly connected to the another element or be indirectly connected to the another element with one or more intervening elements interposed therebetween. Like reference numerals refer to like elements throughout the specification.

(14) Hereinafter, an electrode assembly and a secondary battery using the same according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings illustrating embodiments of the present invention.

(15) Terms used in the embodiment of the present invention will first be defined before describing the drawings. In the context of the present application, bending refers to a state in which an electrode tab is bent, and winding refers to a state in which the electrode tab is spirally wound. In addition, a draw-out direction of the electrode tab refers to a direction where a lead is positioned (i.e., a direction heading away from the electrode assembly) and an inverse draw-out direction of the electrode tab refers to a direction where the electrode assembly is positioned (i.e., a direction heading toward the electrode assembly).

(16) FIG. 1 is an exploded perspective view of a secondary battery according to a first embodiment of the present invention.

(17) Referring to FIG. 1, in an electrode assembly 10, an anode plate 11 and a cathode plate 13 which are applied with active materials are alternately disposed and laminated with a separator 12 interposed therebetween. Anode tabs 11a which extend from one side are formed on the anode plate 11 and cathode tabs 13a which extend from the other side in the same direction as the anode tabs 11a are formed on the cathode plate 13.

(18) Although a laminate-type electrode assembly is shown in the first embodiment of the present invention, another electrode assembly having a structure in which a plurality of electrode tabs are overlapped with each other may also be formed.

(19) Although they may be formed in other ways, depending on the type of the secondary battery, the anode plate 11 and the cathode plate 13 are generally formed by applying and fixing the active materials to and/or into metallic materials, and drying, roll-pressing, and cutting the materials. In one embodiment, the anode plate 11 and the cathode plate 13 are fabricated by coating an aluminum metal foil and a copper metal foil, respectively, with slurries and drying them. The slurries include the active materials of the anode plate 11 and the cathode plate 13 and a fixing agent which allows the active materials to adhere to the metal foils. In the case of a lithium secondary battery, an oxide containing lithium may be primarily used as an anode active material and any one of hard carbon, soft carbon, graphite, and a carbon substance may be primarily used as a cathode active material, but the present invention is not limited to lithium secondary batteries.

(20) The separator 12 is interposed between the anode plate 11 and the cathode plate 13. An insulating thin film having high ion permeability and high mechanical strength is used. Diameters of pores of the separator 12 are generally in the range of 0.01 to 10 μm and the thickness of the separator 12 is generally in the range of 5 to 300 μm. A sheet or a non-woven fabric made of an olefinic polymer such as chemical-resistant and hydrophobic polypropylene, a glass fiber, or polyethylene may be used as the separator 12. In the case in which a solid electrolyte such as a polymer, etc. is used as an electrolyte, the solid electrolyte may also serve as the separator 12.

(21) In addition, a pouch case 20 has a receiving space which can house the electrode assembly 10. The pouch case 20 is generally formed on the top and bottom of an aluminum thin-film to have a laminate structure. An inner surface of the pouch case 20 is made of a heat adhesive resin.

(22) FIG. 2 is a perspective view of a secondary battery according to a first embodiment of the present invention and FIG. 3 is a cross-sectional view taken along line A-A′ of FIG. 2.

(23) Referring to FIGS. 2 and 3, when the electrode assembly 10 is received in the receiving space of the pouch case 20, a part of each of an anode lead 11b bonded to the anode tab 11a and a part of a cathode lead 13b bonded to the cathode tab 13a is exposed outside the pouch case 20. An insulating tape 30 for ensuring electrical insulation while increasing airtightness with the pouch case 20 is attached to the portions of the anode lead 11b and the cathode lead 13b that are in contact with the pouch case 20.

(24) In the electrode assembly 10, the anode plates 11 with the extending anode tab 11a and the cathode plates 13 with the extending cathode tab 13a are alternately disposed and the separators 12 are interposed therebetween. The anode tabs 11a and the cathode tabs 13a are connected to the anode lead 11b and the cathode lead 13b, respectively, the anode tabs and the cathode tabs each being wound together (e.g., in a clockwise direction). After the anode tabs 11a and the cathode tabs 13a are wound, a wound section 14 may be positioned inside a width B or between end points defining the thickness of the electrode assembly 10.

(25) Accordingly, a space occupied by the anode tabs 11a and the cathode tabs 13a is reduced in an inner space of an airtight section 21 of the pouch case 20, thereby improving spatial utilization. That is, a battery capacity may be improved by increasing the sizes of the anode plate 11 and the cathode plate 13 in the remaining space (or the space that would otherwise have been occupied by the anode and cathode tabs) of the airtight section 21 and the size of a final product may be reduced by forming the pouch case 20 smaller.

(26) As described above, the pouch case 20 is generally formed on the top and bottom of the aluminum thin-film to have a laminate structure covered with nylon, a synthesis resin such as polypropylene or polyethylene, etc. The inner surface of the pouch case 20 is made of a heat adhesive resin for airtightness. As a result, the heat adhesive resin coated on the inner surface of the pouch case 20 is fused with the pouch case 20 by heating and pressing to make the pouch case 20 airtight.

(27) FIG. 4 is an exploded cross-sectional view of an electrode assembly according to a second embodiment of the present invention.

(28) Referring to FIG. 4, draw-out lengths of the anode tabs 11a are different from each other. Herein, when the anode tabs 11a are wound or bent, an anode tab 11a-5 positioned at the innermost side has the shortest length and an anode tab 11a-1 positioned at the outermost side has the longest length for convenience of a process (e.g., a manufacturing process). That is, the anode tab 11a-5 positioned at the innermost side and the anode tab 11a-1 positioned at the outermost side and anode tabs 11a-4, 11a-3, and 11a-2 sequentially positioned therebetween have lengths in which the length of the anode tab 11a-1 is longer than that of the anode tab 11a-2, the length of the anode tab 11a-2 is longer than that of the anode tab 11a-3, the length of the anode tab 11a-3 is longer than that of the anode tab 11a-4, and the length of the anode tab 11a-4 is longer than that of the anode tab 11a-5.

(29) Although the cathode tabs 13a drawn out from the cathode plate 13 are not shown, draw-out lengths of the cathode tabs 13a may be different from each other in a manner identical or substantially identical to that of the anode tabs 11a.

(30) FIG. 5 is a cross-sectional view showing a wound electrode tab and a lead which are bonded to each other according to a third embodiment of the present invention.

(31) Referring to FIG. 5, electrode tabs 15a drawn out from an electrode plate are wound in a counterclockwise direction and thereafter, a lead 15b is electrically connected to the bottom of the wound section 14. The lead 15b is connected with the wound section 14 on the top of the wound section 14. The wound section 14 and the lead 15b may be connected to each other by welding and the electrode tabs 15a are positioned inside the width of the electrode assembly or between end points defining the thickness of the electrode assembly.

(32) FIG. 6 is a cross-sectional view showing a bent electrode tab and a lead which are bonded together according to a fourth embodiment of the present invention.

(33) Referring to FIG. 6, in the fourth embodiment of the present invention, electrode tabs 21a extended from an electrode plate (not shown) are bent once and are connected with a lead 21b. Herein, the electrode tabs 21a are bent downward in an inverse draw-out direction of the electrode tabs 21a, that is, a direction where the electrode assembly is positioned (or toward the electrode assembly) to form a bent section 22. In addition, the lead 21b is welded onto the top of the bent electrode tabs 21a.

(34) Here, in one embodiment, the electrode tabs 21a may be bent upward in the inverse draw-out direction of the electrode tabs 21a, and the lead 21b may be welded onto the top or the bottom of the electrode tabs 21a. Further, the draw-out lengths of the electrode tabs 21a may be formed to increase from the inside to the outside of a bent portion so that the electrode tabs 21a are easily bent and the electrode tabs 21a may be formed to be positioned inside the width of the electrode assembly or between endpoints defined by the thickness of the electrode assembly.

(35) FIG. 7 is a cross-sectional view showing a bent electrode tab and a lead which are bonded to each other according to a fifth embodiment of the present invention.

(36) Referring to FIG. 7, in the fifth embodiment of the present invention, electrode tabs 31a extended from an electrode plate are bent twice and are connected with a lead 31b. Herein, the electrode tabs 31a are bent in an inverse draw-out direction of the electrode tabs 31a to form a first bent section 32 and in addition, they are bent in a draw-out direction of the electrode tabs 31a (or away from the electrode assembly) to form a second bent section 33.

(37) That is, the electrode tabs 31a are bent (or bent upward) in the direction where the electrode assembly is positioned to form the first bent section 32 and in addition, they are bent (or bent upward) in the direction where the lead 31b is positioned to form the second bent section 33. In addition, the lead 31b is welded onto the top of the electrode tabs 31a which are bent twice. Herein, although not shown in the figure, the lead 31b may be welded onto the bottom of the electrode tabs 31a which are bent twice.

(38) FIG. 8 is a cross-sectional view showing a bent and wound electrode tab and a lead which are bonded to each other according to a sixth embodiment of the present invention.

(39) Referring to FIG. 8, in the sixth embodiment of the present invention, electrode tabs 41a extended from an electrode plate are bent once in an inverse draw-out direction of the electrode tabs 41a and thereafter, are wound (e.g., in the clockwise direction) and are connected with a lead 41b. Herein, the electrode tabs 41a are bent upward in the direction where the electrode assembly is positioned to form a bent section 42 and wound in the clockwise direction to form a wound section 43. In addition, the lead 41b is welded between the bent section 42 and the wound section 43. Further, the lead 41b may alternatively be welded onto the top of the wound section 43.

(40) Also, in one embodiment, the draw-out lengths of the electrode tabs 41a may be formed to increase from the inside to the outside of a bent and wound portion so that the electrode tabs 41a are easily bent and wound and the electrode tabs 41a may be formed to be positioned inside the width of the electrode assembly or between endpoints defined by the thickness of the electrode assembly.

(41) FIG. 9 is a cross-sectional view showing a bent and wound electrode tab and a lead which are bonded to each other according to a seventh embodiment of the present invention.

(42) Referring to FIG. 9, in the seventh embodiment of the present invention, electrode tabs 51a extended from an electrode plate are bent once in an inverse draw-out direction of the electrode tabs 51a and thereafter, they are wound (e.g., in the clockwise direction) and connected with a lead 51b. The electrode tabs 51a are bent (or bent downward) in the direction where the electrode assembly is positioned to form a bent section 52 and wound in the counterclockwise direction to form a wound section 53. In addition, the lead 51b is welded between the bent section 52 and the wound section 53. Further, the lead 51b may alternatively be welded onto the top of the wound section 53.

(43) FIG. 10A is a cross-sectional view showing an electrode tab and a lead which are wound together according to an eighth embodiment of the present invention and FIG. 10B is a cross-sectional view showing a lead which is bent in a direction opposite to (or away from) an electrode assembly according to an eighth embodiment of the present invention.

(44) Referring to FIGS. 10A and 10B, after a lead 61b is positioned on the top of electrode tabs 61a drawn out from an electrode plate, the lead 61b and the electrode tabs 61a are together wound in the counterclockwise direction to form a wound section 62 so that the lead 61b is positioned at the innermost side. In addition, the end (the end of a lead positioned at the electrode assembly side) of an unwound portion of lead 61b is pulled in a direction (direction C) opposite to (or away from) the electrode assembly to form a bent section 63 where the end of the unwound lead 61b is bent in the direction opposite to the electrode assembly. Thereafter, a bonding strength is reinforced by welding the electrode tabs 61a and the lead 61b to each other.

(45) According to the eighth embodiment of the present invention, it is possible to improve the utilization of the inner space of the exterior case by winding the electrode tabs 61a and the lead 61b together, and it is possible to reduce the number of processes (or to simplify manufacturing) by winding the electrode tabs 61a and the lead 61b together.

(46) While the present invention has been described in connection with certain exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, and equivalents thereof.