KR100684848B1 - Secondary battery - Google Patents

Abstract

The secondary battery according to the present invention is an electrode group including a positive electrode and a negative electrode disposed on both sides of the separator and the separator so as to maximize the size of the gasket and to easily fix the case and the cap plate by laser welding. A case in which an electrode group is embedded, an electrode terminal electrically connected to the electrode group to protrude to the outside, a terminal insertion hole into which the electrode terminal is inserted is formed, and coupled to the case to seal the cap plate, and installed in the terminal insertion hole And a gasket having at least one evacuation portion mowed outside surface.

Secondary battery, electrolyte inlet, electrode terminal, cap plate

Description

Secondary Battery {SECONDARY BATTERY}

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

FIG. 2 is a cross-sectional view of the rechargeable battery taken along the line A-A of FIG. 1.

3 is a perspective view illustrating a process of fixing the cap plate according to the first embodiment of the present invention to a case by laser welding.

4 is a perspective view showing a gasket according to the second embodiment of the present invention.

5 is a cross-sectional view illustrating a gasket according to the second exemplary embodiment of the present invention.

6 is a perspective view illustrating a gasket according to a third exemplary embodiment of the present invention.

The present invention relates to a secondary battery. More specifically, the present invention relates to a secondary battery having an improved structure of a gasket installed in a terminal insertion hole.

A secondary battery is a battery that can be charged and discharged unlike a primary battery that is not rechargeable. Low-capacity secondary batteries are used in portable electronic devices such as mobile phones, notebook computers, and camcorders, and large-capacity batteries are widely used as power sources for driving motors in hybrid vehicles.

The secondary battery is manufactured in various shapes. Typical shapes include cylindrical and rectangular shapes.

Recently, the high-output secondary battery, which can be used for driving a motor requiring a large power, for example, an electric vehicle, connects a plurality of series in series to form a large capacity secondary battery.

As described above, one large capacity secondary battery (hereinafter, referred to as a battery module for convenience of description throughout) is made of a secondary battery (hereinafter, referred to as a unit cell for convenience of description throughout) of a plurality of connected in series or in parallel.

Each unit cell includes a case having an electrode group in which a cathode and a cathode are disposed with a separator interposed therebetween, and a space in which the electrode group is built, a cap plate coupled to the case and sealing the electrode group; The positive electrode terminal and the negative electrode terminal which are electrically connected and inserted into the terminal insertion hole formed in the cap plate and protrude outward, and a gasket inserted into the terminal insertion hole to ensure the tightness.

The positive electrode terminal and the negative electrode terminal protruding from the top of the cap plate in the battery module are cross-aligned with the positive terminal and the negative terminal of the neighboring unit cell, and the connector is connected between the screwed positive terminal and the negative terminal through a nut. Each unit cell is electrically connected.

That is, a washer is inserted into the terminal, and a nut is coupled to the washer to close the terminal insertion hole by bringing the gasket into close contact with the cap plate through the washer. In addition, the connector is installed on the nut to electrically connect the neighboring unit cells, and another nut is installed on the connector to fix the connector.

At this time, as the size of the nut is larger, it is preferable not only to reduce the contact resistance between the nut and the connector but also to improve the fastening force, thereby maximizing the size of the nut. In addition, to increase the size of the nut, the gasket for insulating the nut and the cap plate must also be increased in size.

However, the thickness of the unit cell is determined to be a constant size, and as the thickness of the unit cell is smaller, the heat dissipation performance and stability is improved, so it is necessary to maximize the size of the gasket in a given space.

In addition, the cap plate is fixed to the case by welding, and in general, the cap plate is fixed to the case by laser welding. When maximizing the size of the gasket, the cap plate is welded due to the interference of the laser and the gasket during the welding. There is a problem that a defect occurs. In laser welding, the laser beam becomes thinner toward the welding part and concentrates on the welding part. The laser beam becomes thicker as it moves away from the welding part. Due to this structure, the edge of the gasket located above the welding part may interfere with the laser beam, causing welding failure. In this way, if a welding defect occurs, the electrolyte may leak and a short circuit may occur.

The present invention is to solve the above problems, an object of the present invention includes a gasket formed to minimize the interference caused by welding while being spaced a predetermined distance from the end of the cap plate while maximizing the size of the nut fastened to the terminal It is to provide a secondary battery.

In order to achieve the above object, a secondary battery according to the present invention includes a gasket formed with an avoiding part at an edge thereof.

In addition, the secondary battery according to the present invention includes an electrode group including a separator and a cathode and a cathode disposed on both sides of the separator, a case into which the electrode group is inserted, an electrode terminal electrically connected to the electrode group and protruding to the outside, And a cap plate coupled to the case to form a terminal insertion hole into which the electrode terminal is inserted, and a gasket having at least one evacuation portion installed at the terminal insertion hole to seal the case and having an outer side cut off. Can be.

That is, the outer surface of the gasket is made of a cylindrical cylinder with the same distance from the center, and a portion of the outer gasket may be scraped off to form a avoiding portion having a relatively small distance from the center.

The avoidance part may be formed at an edge of the gasket, and four avoidance parts may be formed at symmetrical parts.

And this avoidance may be made of a surface having a radius of curvature larger than the circle forming the outer surface of the gasket, preferably as shown in Figure 1 may be made of a plane with an infinite radius of curvature. In addition, the avoiding portion may be formed as a recessed portion recessed inward.

In addition, the gasket may be formed with a through hole so that the terminal can be fitted in the center.

And an outer wall is formed at the edge of the gasket and the inner surface of the outer wall forms a circle so that the nut can be easily fastened to the terminal, the outer surface of the outer wall in a partially crushed circular shape by shaving part of the outer wall Can be done.

Therefore, a nut of sufficient size can be accommodated inside, and an avoidance is formed at a portion close to the end of the cap plate to prevent the gasket from interfering in the process of welding the cap plate to the case.

And the avoiding portion may be made of a predetermined inclined structure more toward the top. Since the laser beam becomes thicker toward the upper side, in the case of the structure in which the upper side is cut more, the distance between the gasket and the laser beam is farther apart so that the laser welding can be stably performed.

Here, the secondary battery (or battery module) is a device that operates by using a motor such as a HEV (hybrid car), an EV (electric vehicle), a wireless cleaner, an electric bicycle, an electric scooter, and the like to drive a motor of the device. It can be used as an energy source.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is an exploded perspective view of a rechargeable battery according to an exemplary embodiment of the present invention, and FIG. 2 is a cross-sectional view of the rechargeable battery taken along the line A-A of FIG. 1.

Referring to the drawings, the secondary battery 10 according to the present embodiment includes an electrode group 15 and an electrode group 15 in which the positive electrode 11 and the negative electrode 12 are positioned with the separator 13 interposed therebetween. A case 14 having one end open to accommodate the 15, a cap plate 17 coupled to the opening of the case 14, and having a terminal insertion hole 16 formed therein, and the electrode group 15. Electrode terminals 21 and 22 are connected and inserted into the terminal insertion hole 16.

Here, the electrode group 15 includes a separator 13 having a positive electrode 11 and a negative electrode 12 each including a coated portion coated with an active material on a current collector and non-coated portions 11a and 12a where an active material is not applied to a current collector. It may be made of a laminated configuration with the gap or in the state in which the positive electrode 11, the separator 13 and the negative electrode 12 are laminated, they may be of a jelly-roll type formed by winding in a vortex phase.

An electrode terminal is electrically connected to the electrode group 15. The positive electrode terminal 21 is electrically connected to the positive electrode uncoated portion 11a, and the negative electrode terminal 22 is electrically connected to the negative electrode uncoated portion 12a.

The electrode terminals 21 and 22 may be electrically connected to the electrode group 15 through lead tabs attached to the plain portions 11a and 11b. 21 and 22 and lead tabs may be integrally formed to directly connect the electrode terminals 21 and 22 to the electrode group 15. In addition, the electrode terminals 21 and 22 protrude to the outside and are installed to induce a current to the outside.

The case 14 is made of a conductive metal such as aluminum, an aluminum alloy, or nickel plated steel, and the shape of the case 14 has an inner space in which the electrode group 15 is located, and is formed in an open corner. . In the present embodiment, the rectangular secondary battery 10 is described as an example, but the present invention is not limited thereto and may be formed in a cylindrical or other shape in addition to the rectangular.

The cap plate 17 is coupled to the open end of the case 14 to seal the cap plate 17. The electrode plate 21 and 22 are inserted into the cap plate 17 to protrude out of the case 14. An insertion hole 16 is formed.

In addition, the electrode terminal insertion hole 16 has a gasket 23 that insulates the electrode terminals 21 and 22 from the cap plate 17 and seals the electrode terminal insertion hole 16 with the electrode terminals 21 and 22. It is interposed between the electrode terminal insertion openings 16.

The gasket 23 is composed of a lower portion 23a fitted to the electrode terminal insertion hole 16 and an upper portion 23b protruding upward of the cap plate 17, and electrode terminals 21 and 22 at the center thereof. The through hole is formed to be fitted. And the upper portion 23b is composed of a bottom and the outer wall, the bottom is in close contact with the upper surface of the cap plate 17, the washer 24 and the nut 25 is fitted inside the outer wall.

And the outer wall is made of a hollow hollow body so that the nut 25 can be easily fitted to the terminals (21, 22) while rotating. In addition, when the washer 24 and the nut 25 are fitted to the gasket 23 and the nut 25 is coupled to the terminals 21 and 22, the nut 25 is connected to the bottom of the gasket 23. The terminal insert 16 is sealed by pressing.

In addition, an outer side of the outer wall is formed with an evacuation portion 23c shaved to have a larger radius of curvature than a circle constituting the outer wall. As shown in FIG. 1, the evacuation portion 23c has a planar radius of infinity. Can be done.

The avoidance part 23c has a structure in which the distance from the center of the gasket 23 is smaller than that of the other part, and the avoidance part 23c according to the present embodiment has an outer wall of the gasket 23 having a cap plate 17. It is made of a structure cut vertically with respect to the upper surface of the).

3 is a perspective view illustrating a process of fixing the cap plate 17 according to the first embodiment of the present invention to the case 14 by laser welding.

Referring to the drawings described above, the laser beam 51 passes through the lens 52 and proceeds to the welded portion. The farther away from the lens 52, the width decreases and the laser beam 51 is concentrated at the welded portion. In addition, the heat is generated in the place where the laser beam 51 is concentrated to melt the base material and the two members are joined in the process of melting the base material.

As shown in FIG. 3, the laser beam 51 becomes thinner toward the welding part and has a thicker upper shape. If the outer end surface of the gasket 23 is circular, the upper end of the outer wall of the gasket 23 and the laser beam 51 are formed. Although there is a possibility of interference, when the avoidance part 23c is formed in the gasket 23 as in this embodiment, the distance between the laser beam 51 and the gasket 23 is separated by a predetermined distance so that the laser beam 51 And gasket 23 do not interfere.

4 is a perspective view illustrating a gasket according to the second embodiment of the present invention, and FIG. 5 is a cross-sectional view illustrating the gasket according to the second embodiment of the present invention.

Referring to the drawings described above, the gasket 23 according to the present embodiment is a lower portion (32) to be fitted to the terminal insertion hole formed in the cap plate 17 and the upper portion protruding upward of the cap plate 17 ( 31). In addition, a through hole 36 is formed in the center of the gasket 30 to allow the electrode terminals 21 and 22 to be fitted, and an upper portion of the bottom portion 34 and the bottom portion that are in close contact with the cap plate 17. And an outer wall 35 consisting of a hollow cylinder projecting upward along the edge of 34.

The outer wall 35 has a circular inner cross section so that the nut 25 is rotated so as to be coupled to the terminals 21 and 22 to be easily fitted to the gasket 30. However, the avoidance part 37 in which the part adjacent to the edge part of the cap plate 17 was cut off is formed.

The avoiding portion 37 has a structure that is cut more and more toward the upper portion, and as a result, the avoiding portion 37 has a predetermined inclination.

The upper part of the avoiding part 37 is relatively cut off, and the bottom part 34 can maintain a large area, thereby stably sealing the terminal insertion hole 16.

In addition, although the upper part of the laser beam is emitted in a relatively thick structure, the upper part of the avoidance part 37 is also cut off a lot to maintain a constant distance from the laser beam, so that the laser beam and the gasket 30 do not interfere even during welding. do.

6 is a perspective view showing a gasket 40 according to the third embodiment of the present invention.

Referring to the drawings described above, the gasket 40 according to the present embodiment protrudes from the lower portion 42 fitted into the terminal insertion hole 16 formed in the cap plate 17 and the cap plate 17. It consists of an upper portion 41. In addition, a through hole 46 is formed at the center of the gasket 40 so that the electrode terminals 21 and 22 can be fitted, and the upper part 41 has the bottom part 44 closely contacting the cap plate 17 and the bottom part. An outer wall 45 consisting of a hollow cylinder projecting upward along the edge of 44.

The outer wall 45 has a circular inner cross-section so that the nut is coupled to the terminals (21, 22) to be easily fitted to the gasket (40), the outer is basically a circular cross-sectional structure, In the part adjacent to the end part of the cap plate 17, the avoidance part 47 in which one part of the outer wall 45 was cut off is formed.

And the avoiding portion 47 is made of a concave recessed structure inward, it is made of a structure that is concave curved inwardly of the gasket 40 to form a gentle arc.

In addition, the avoiding part 47 according to the present embodiment is illustrated as being formed in four places in a symmetrical structure, but the present invention is not limited thereto, and may be formed only at three places adjacent to the end of the cap plate 17. Alternatively, it may be formed only in a portion relatively close to the end of the cap plate 17.

In this way, the portion of the gasket 40 adjacent to the welded portion is concavely curved to remove the fear that the welding defect is generated due to the interference of the gasket 40 in the process of fixing the case 14 and the cap plate 17 by laser welding. can do.

The secondary battery of the present invention is a device that operates by using a motor such as a hybrid electric vehicle (HEV), an electric vehicle (EV), a wireless cleaner, an electric bicycle, an electric scooter, and the like, and is used as an energy source for driving a motor of the device. Can be used.

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

As described above, according to an exemplary embodiment of the present invention, an avoidance part may be formed on the outer side of the gasket to maximize the size of the gasket. In the process of fixing the cap plate and the case by welding, the gasket and the laser interfere with the welding defect. It can be prevented from occurring to improve the structural stability and reliability of the secondary battery.

Claims (11)

An electrode group including a separator and an anode and a cathode disposed on both sides of the separator; A case in which the electrode group is built; An electrode terminal electrically connected to the electrode group and protruding to the outside; A cap plate having a terminal insertion hole into which the electrode terminal is inserted and coupled to the case to seal the cap plate; And A gasket installed at the terminal insertion hole and formed at a portion adjacent to an edge of the cap plate, the avoiding portion having a shorter distance from the center to the outer peripheral surface than the other portion; Secondary battery comprising a. According to claim 1, The secondary battery is formed by cutting the outer circumference of the gasket. According to claim 1, The evacuation portion is a secondary battery formed in a portion in which two evasion portions are symmetrical with each other. According to claim 1, Secondary batteries are formed in each of the four avoiding gaskets According to claim 1, The gasket has a circular cross section of an outer circumferential surface, and the avoiding portion is formed of a surface having a curvature radius larger than that of the circle. According to claim 1, The secondary battery has a planar portion. The method according to any one of claims 1 to 5, A surface forming the avoiding portion is a secondary battery having an inclined structure. The method of claim 7, wherein The avoiding part is a secondary battery made of a downward slope along the welding direction. According to claim 1, The secondary battery is formed of a concave recessed structure. According to claim 1, The cap plate and the case is a secondary battery is fixed by laser welding. According to claim 1, The secondary battery is a secondary battery for driving a motor.

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