KR20090116450A - Rechargeabel battery - Google Patents

Abstract

PURPOSE: A rechargeable battery is provided to reduce stress between a core and an electrode group by forming an elastic deformation part, thereby minimizing output degradation of the rechargeable battery. CONSTITUTION: A rechargeable battery(100) comprises an electrode group(110) including a positive electrode(112), a negative electrode(113), and a separator(114) interposed between the positive electrode and negative electrode; a case(120) with a space containing the electrode group; a cap assembly(140) which is electrically connected to the electrode group and is coupled with the case; and a core(160) with an elastic deformation part having a hole(162), which is inserted into the electrode group.

Description

Secondary Battery {RECHARGEABEL BATTERY}

The present invention relates to a secondary battery, and more particularly, to a secondary battery having an improved structure of a core inserted into an electrode group.

A rechargeable battery is a battery that can be charged and discharged unlike a primary battery that is not rechargeable. Low-capacity secondary batteries consisting of one cell are used in portable electronic devices such as mobile phones, notebook computers, and camcorders. A large capacity secondary battery in which a plurality of cells are connected in a pack form is widely used as a motor driving power source for a hybrid electric vehicle.

Such secondary batteries are manufactured in various shapes, and typical shapes include cylindrical and rectangular shapes.

In addition, the secondary battery is connected in series so as to be used for driving a motor of an electric vehicle requiring a large power, thereby forming a large capacity secondary battery module.

The secondary battery includes a case having an electrode group in which a positive electrode and a negative electrode are positioned with a separator interposed therebetween, a case having a space in which the electrode group is built, and a cap assembly enclosing the case.

The positive electrode and the negative electrode have a strip shape extending in one direction, and a non-coating portion having no active material applied thereto is formed at one end in the longitudinal direction.

In a state where a separator is interposed between the positive electrode and the negative electrode, the electrode group forms a substantially cylindrical shape by winding spirally around a cylindrical core. At this time, the positive electrode uncoated portion and the negative electrode uncoated portion are arranged to face in different directions.

The core not only serves to support the electrode group in the winding process, but also maintains the shape of the wound electrode group.

The negative electrode non-coating portion is attached to the negative electrode current collector plate, the positive electrode non-coating portion is attached to the positive electrode current collector plate, the negative electrode current collector plate is electrically connected to the case, the positive electrode current collector plate is electrically connected to the cap assembly to induce a current to the outside.

As the secondary battery repeatedly charges and discharges, the electrode group gradually expands, and thus a phenomenon in which stress increases between the electrode group and the case and between the electrode group and the core occurs. There is a space fox between the case and the electrode group, so that a large stress does not occur. However, since there is little space between the electrode group and the core, a relatively large stress occurs.

If the stress is concentrated between the electrode group and the core, the charge and discharge efficiency is lowered, there is a problem that the output of the secondary battery is reduced. In addition, there is a problem in that life deterioration occurs in a portion where stress is concentrated, and an unstable reaction occurs to decrease the life of a secondary battery.

The present invention has been made to solve the above problems, an object of the present invention to provide a secondary battery that can minimize the generation of stress between the electrode group and the core.

In order to achieve the above object, a secondary battery according to an embodiment of the present invention includes an electrode group including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and a case having a space in which the electrode group is embedded. And a core coupled to the case and electrically connected to the electrode group, and a core inserted into the electrode group and having an elastic deformation portion formed in a hole on an outer circumference thereof.

The hole may be formed by connecting both ends thereof to the inner circumferential surface thereof, and the core may include a support part in which the hole is not formed at both ends in the longitudinal direction.

The hole may be formed to extend in the longitudinal direction of the core, a plurality of holes are formed in the core, the holes may be spaced apart along the circumferential direction of the core.

The inner surface of the core may have a polygonal cross section, and the outer surface of the core may have a circular shape. In addition, the hole may have a variable width portion that increases in width in the longitudinal direction of the core, the variable width portion may be formed at both ends of the hole. In addition, an equal width portion having a constant width may be formed between the variable width portions.

Since holes are formed in the core to easily elastically deform, the stress between the core and the electrode group can be reduced, thereby minimizing the output reduction of the secondary battery.

In addition, support portions are formed at both ends of the core, and elastic deformation portions are formed at the center thereof, thereby easily reducing stresses that are frequently applied in the central portion, and also support portions stably support the electrode group to maintain structural stability. Can be.

In addition, a variable width portion is formed at both ends of the hole and an equal width portion is formed between the variable width portions to stably reduce concentration of stress.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like elements throughout the specification.

1 is a cutaway perspective view illustrating a rechargeable battery according to an exemplary embodiment of the present invention.

Referring to the above drawings, the secondary battery 100 according to the present exemplary embodiment includes an electrode group 110 in which the positive electrode 112 and the negative electrode 113 are positioned with the separator 114 interposed therebetween, and the electrode group together with the electrolyte solution. It includes a case 120 formed with an opening at one end to accommodate the (110). In addition, a cap assembly 140 for sealing the case 120 is installed at the opening of the case 120 through the gasket 144.

More specifically, the case 120 is made of a conductive metal such as aluminum, aluminum alloy or nickel plated steel.

And the shape of the case 120 according to the present embodiment is made of a cylindrical shape having an internal space in which the electrode group 110 is located. After the cap assembly 140 is inserted into the case 120, the cap assembly 140 is fixed to the case 120 by clamping. In this process, the case 120 has a beading part 123 and a crimping part 125. Is formed.

The electrode group 110 according to the present embodiment is formed of a cylindrical type wound in a vortex after the anode 112, the separator 114, and the cathode 113 are stacked, but the structure of the electrode group 110 must be It is not limited to this, but can also be made with other structures, such as a square. A space is formed at the center of the electrode group 110, and a core CORE 160 is installed in the space to maintain the cylindrical shape of the electrode group 110.

In addition, the positive electrode non-coating portion 112a on which the positive electrode active material is not coated is formed at the upper end of the positive electrode 112 and is electrically connected to the positive electrode current collector plate 138. In addition, a negative electrode uncoated portion 113a is formed at the bottom of the negative electrode 113 to which the negative electrode active material is not coated, and is electrically connected to the negative electrode current collector plate 132.

In this embodiment, the positive electrode current collector plate 138 is located at the top and the negative electrode current collector plate 132 is described as an example, but the present invention is not limited thereto, and the positive electrode current collector plate 138 is located at the bottom. The negative electrode current collector plate 132 may be located at the top.

The cap assembly 140 may include a cap plate 143 having a protruding external terminal 143b and an exhaust port 143a, and a vent plate installed under the cap plate 143 and broken under a set pressure condition to release gas. 142). The vent plate 142 serves to block electrical connection between the electrode group 110 and the cap plate 143 under a set pressure condition.

A positive temperature element 141 is installed between the cap plate 143 and the vent plate 142. The positive temperature element 141 is a device in which the electrical resistance increases to almost infinity after a predetermined temperature. As a secondary battery 100, the secondary battery 100 serves to block the flow of charge and discharge current when the temperature reaches a predetermined value or more.

The vent plate 142 is formed to protrude downward, and the sub plate 147 is attached to the bottom surface of the protruding portion.

The middle plate 146 and the middle plate 146 and the vent plate 142 electrically connected to the electrode group 110 through the lead part 150 and fixed to the sub plate 147 at the edge of the vent plate 142. Insulator 145 is insulated between the middle plate 146 and the vent plate 142 between.

2 is a perspective view illustrating a core according to a first embodiment of the present invention, and FIG. 3 is a cross-sectional view taken along line III-III of FIG. 2.

Referring to FIGS. 2 and 3, the core 160 has a substantially cylindrical shape, and a hollow portion 165 penetrating the core 160 in the longitudinal direction is formed inside the core 160. The outer circumference of the 160 is formed with a hole 162 penetrating the outer surface and the hollow portion.

The hollow portion 165 has a substantially hexagonal cross section. However, the present invention is not limited thereto, and the hollow part 165 may have a cross-sectional shape other than a circle such as a polygon or an ellipse.

The core 160 has an elastic deformation portion 163, which is a portion where the hole 162 is formed, and a support 161, which is a portion where the hole 162 is not formed.

The hole 162 has a rectangular shape extending in the longitudinal direction of the core 160. The hole 162 is positioned at the center in the longitudinal direction of the core 160, and both ends of the hole 162 in the longitudinal direction are blocked. Accordingly, the elastic deformation portion 163 is formed at the central portion of the core 160, and the support portions 161 are formed at both ends in the longitudinal direction of the core 160.

In addition, three holes 162 are formed at the outer circumference of the core 160, and the holes 162 are spaced at equal intervals along the outer circumference of the core 160.

As the hole 162 is formed in the core 160 as described above, when the electrode group 110 expands, the core 160 elastically deforms to reduce the stress between the electrode group 110 and the core 160. Can be. In addition, the electrode group 110 expands inwardly in the longitudinal direction, and both ends of the up and down directions are smaller in expansion than the inside, and the support part 161 is provided at a portion of the core that is in contact with both ends of the electrode group 110 in the up and down direction. It can be formed to stably support the electrode group 110, the inner elastic deformation portion 163 can be formed to easily reduce the stress.

In particular, both ends of the electrode group 110 are fixed to the positive electrode current collector plate 138 and the negative electrode current collector plate 132 by welding, respectively, and both ends of the core 160 are deformed, so that the longitudinal ends of the electrode group 110 are inward. When the expansion and deformation of the electrode group 110 and the current collector plates 132 and 138 are welded, a portion may be dropped. In this embodiment, the structural stability is maintained by forming the support part 161 at the end of the electrode group 110 to prevent the end of the electrode group 110 from being deformed.

4 is a cross-sectional view illustrating a core 210 of a rechargeable battery according to a modified example of the first embodiment of the present invention. As shown in FIG. 4, a hollow portion 215 having a hexagonal cross section is formed at the center of the core 210, and a plurality of holes 212 are formed at the outer circumference of the core 210. In the core 210 of the present embodiment, six holes 212 are formed, and one hole 212 is formed on one surface of the hollow part 215. Therefore, the core 210 can be elastically deformed more easily. In the present exemplary embodiment, six holes 212 are formed in the core 210, but the present invention is not limited thereto. The plurality of holes 212 may be formed according to the width and size of the holes 212. have.

5 is a perspective view illustrating a core of a rechargeable battery according to a third exemplary embodiment of the present invention. As shown in FIG. 5, the core 230 has a hollow portion 235 formed therein so as to penetrate in the longitudinal direction, and a plurality of holes 231 are formed at the outer circumference thereof.

The hollow part 235 has a rectangular cross section and is formed through both ends of the core 230.

On the other hand, the hole 231 is formed in the longitudinal direction of the core 230, it is located in the longitudinal center portion of the core 230. Accordingly, holes 231 are not formed at both ends of the core 230 in the longitudinal direction.

In addition, the hole 231 has a variable width portion 231a which increases in width toward the inside of the core 230, and an equal width portion 231b having a constant width and the same width as the maximum width of the variable width portion 231a. It includes. The variable width portion 231a is formed at both ends of the hole 231, and the equal width portion 231b is positioned between the variable width portions 231a.

Since the electrode group 110 expands more inwardly in the longitudinal direction, the width of the hole 231 is also increased inwardly so that the core 230 may be more deformed inwardly. Accordingly, the core 230 is also deformed from the inside as the electrode group 110 expands to prevent concentration of stress, and the outside of the core 230 stably supports the electrode group to secure structural stability of the secondary battery. can do.

6 is a graph showing a change in instantaneous output according to the capacity throughput of a secondary battery according to the first embodiment of the present invention, and FIG. 7 is an instantaneous capacity according to the capacity throughput of the secondary battery according to the first embodiment of the present invention. A graph showing the change in.

Referring to FIGS. 6 and 7, the capacity throughput is a sum of currents output as charging and discharging are repeated. Thus, increasing capacity throughput means more charging and discharging cycles.

As shown in FIG. 6, the instantaneous output of the secondary battery 100 gradually decreases as charging and discharging are repeated. The core 160 in which the hole 162 is formed as in the first embodiment of the present invention is compared with a general straight core. ), It can be seen that the instantaneous output decreases little.

In addition, as shown in FIG. 7, as the charge and discharge are repeated, the instantaneous capacity of the secondary battery 100 gradually decreases. In the general straight core, the initial instantaneous capacity has a large value but the instantaneous capacity decreases gradually. It's fast. However, the secondary battery 100 to which the core 160 having the hole 162 is formed according to the first embodiment of the present invention may have a smaller reduction rate of instantaneous capacity than the straight core.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings. Naturally, it belongs to the range of.

1 is a cutaway perspective view illustrating a rechargeable battery according to a first exemplary embodiment of the present invention.

2 is a perspective view illustrating a core of a rechargeable battery according to a first exemplary embodiment of the present invention.

3 is a cross-sectional view taken along the line III-III of FIG. 2.

4 is a longitudinal sectional view showing a core of a secondary battery according to a modification of the first embodiment of the present invention.

5 is a perspective view illustrating a core of a rechargeable battery according to a second exemplary embodiment of the present invention.

6 is a graph illustrating a change in instantaneous output according to a capacity throughput of a secondary battery according to a first exemplary embodiment of the present invention.

7 is a graph illustrating a change in instantaneous capacity according to capacity throughput of a secondary battery according to a first embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

100: secondary battery 110: electrode group

140: cap assembly 160, 210, 230: core

162, 212, 231: hole 161: support portion

165, 215, 235: hollow part 163: elastic deformation part

Claims (10)

An electrode group including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode; A case having a space in which the electrode group is built; A cap assembly coupled to the case and electrically connected to the electrode group; And A core inserted into the electrode group and having an elastic deformation part having a hole formed on an outer circumference thereof; Secondary battery comprising a. According to claim 1, The hole is a secondary battery formed by continuing the inner circumferential surface. The method of claim 2, The core is formed of a secondary battery having a support portion in which no holes are formed at both ends in the longitudinal direction. The method according to any one of claims 1 to 3, The hole is formed to continue in the longitudinal direction of the core. The method of claim 4, wherein A plurality of holes are formed in the core The holes are spaced apart along the circumferential direction of the core. The method according to any one of claims 1 to 3, The inner surface of the core has a polygonal cross section. The method according to any one of claims 1 to 3, An outer surface of the core has a circular cross section. The method according to any one of claims 1 to 3, The hole has a variable width portion that becomes wider toward the inner side in the longitudinal direction of the core. The method of claim 8, The variable width part is a secondary battery formed at both ends of the hole. The method of claim 9, A secondary battery having an equal width portion having a constant width between the variable width portions.

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