KR20090021482A - Rechargeabel battery - Google Patents

Abstract

A secondary battery is provided to separate a convex part of a bent plate and a sub plate by forming protrusion between a sub plate and a middle plate, and to improve stability by preventing the generation of spark between the sub plate and bent plate. A secondary battery(100) comprises an electrode group(110) including a cathode(112), anode(113), and a separator(114) interposed between the anode and cathode; a case(120) receiving the electrode group; a cap-plate(143) combined with a case; a vent plate(160) installed under the cap-plate; a sub-plate(147) which is installed unter the bent plate, is welded with the bent plate, and is electrically connected to the electrode group; a middle plate(146) arranged between the bent plate and sub plate; and protrusions installed between the middle plate and sub plate.

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 cap assembly.

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 may be connected in series to form a large capacity secondary battery module so that the secondary battery may be used for driving a motor such as an electric vehicle requiring a large power.

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.

When the secondary battery is formed in a cylindrical shape, a non-coating portion to which the active material is not coated is formed on the positive electrode and the negative electrode of the electrode group, and the positive electrode non-coating portion and the negative electrode non-coating portion are disposed to face in different directions.

A negative electrode current collector plate is attached to the negative electrode non-coated portion, and a positive electrode current collector plate is attached to the negative electrode non-coated portion. The negative electrode current collector plate is electrically connected to the case, and the positive electrode current collector plate is electrically connected to the cap assembly to induce current to the outside. Therefore, the case serves as the negative terminal, and the cap plate installed in the cap assembly serves as the positive terminal.

While the secondary battery is repeatedly charged and discharged, gas is generated inside the secondary battery to increase the internal pressure, and if the pressure rise inside the secondary battery is left as it is, there is a risk of the secondary battery exploding. In order to prevent this, a vent plate having a notch is installed under the cap plate so as to break at a predetermined pressure.

The vent plate has a convex portion projecting downward and the convex portion is welded to the sub plate electrically connected to the electrode group. When the pressure inside the secondary battery rises, the convex portion is first released from the subplate to block the current between the vent plate and the subplate. Subsequently, if the pressure continues to rise, the notch formed in the vent plate breaks and releases gas to the outside.

Sparks may occur between the convex portion and the subplate due to the high voltage in the process of leaving the convex portion from the subplate. The higher the voltage and the narrower the gap between the subplate and the convex portion, the more likely the spark is to escape from the subplate.

If a spark occurs and persists, the ambient temperature rises due to the spark, and the component melts and there is a risk of explosion of the secondary battery.

The present invention has been made to solve the above problems, an object of the present invention is to provide a secondary battery including a vent plate that can ensure a stable gas passage passage.

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, a case in which the electrode group is built, and a cap plate and the cap plate coupled to the case. A vent plate installed under the vent plate and a sub plate installed under the vent plate and welded to the vent plate and electrically connected to the electrode group, a middle plate disposed between the vent plate and the sub plate, and the middle plate And a projection provided between the sub plate.

The protrusion may be fixed to the middle plate, and the protrusion may be fixed to the sub plate.

The middle plate may be electrically connected to the electrode group through a lead member electrically connected to the electrode group, and the subplate may be electrically connected to the electrode group through the middle plate.

An insulation plate may be installed between the middle plate and the vent plate. The vent plate may be convex toward the inside of the case,

The subplate may be convex toward the outside of the case.

When the distance from the center of the convex portion to the protrusion X and the distance from the center of the convex portion to the center of the welded portion of the subplate and the middle plate may be R, 0.62 ≦ X / R ≦ 0.72.

The protrusions may be formed along a circumference of the convex portion to have a rib shape, and the protrusions may be arranged in plurality. The subplate may have an outlet for discharging gas generated from the electrode group.

A secondary battery according to an exemplary 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, a case in which the electrode group is embedded, a cap plate coupled to the case, and the cap. A secondary battery including a vent plate installed under the plate and a sub plate disposed under the vent plate and welded to the vent and electrically connected to the electrode group, and a middle plate disposed between the vent plate and the sub plate. In the above, the sub plate is characterized in that it has an elastic force toward the inside of the case.

As described above, according to the present invention, a protrusion is formed between the subplate and the middle plate so that the convex portion of the vent plate and the subplate can be spaced more quickly.

In addition, since the subplate is bent convex downward by the projection, the separation distance between the convex portion of the vent plate and the subplate increases.

In addition, since the sub plate has an elastic force toward the inside of the case, it is possible to prevent the spark from being spaced apart more quickly from the vent plate.

In addition, sparks are prevented from occurring between the subplate and the vent plate, thereby improving stability of the secondary battery.

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 can 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.

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

Referring to FIG. 1, the secondary battery 100 according to the present exemplary embodiment includes an electrode group 110 in which a positive electrode 112 and a negative electrode 113 are positioned with a separator 114 interposed therebetween, and an electrode together with an electrolyte. The case 120 includes an opening formed at one end thereof to accommodate the group 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. The cap assembly 140 is inserted into the case 120 and clamped to fix the cap assembly 140. In this process, the beading part 123 and the crimping part 125 are formed in the case 120.

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 may be made of other structures.

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.

The cap assembly 140 includes a cap plate 143 having a protruding outer terminal 143a and an exhaust port 143b and a cap plate 143 installed below the cap plate 143 that are broken under a set pressure condition to release gas. 163 includes a vent plate 160 formed thereon. The vent plate 160 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 may be installed between the cap plate 143 and the vent plate 160, and the positive temperature element 141 may have an electrical resistance that increases to almost infinity after a predetermined temperature. As a device, when the secondary battery 100 reaches a temperature higher than a predetermined value, it serves to block the flow of current.

A convex portion 166 protruding downward is formed at the center of the vent plate 160, and a sub plate 147 is attached to the lower surface of the convex portion 166 by welding.

In the present exemplary embodiment, a structure in which the convex portion 166 is formed in the center of the vent plate 147 is illustrated. However, the present invention is not limited thereto, and the sub plate may be convex toward the outside of the case.

Below the vent plate 160, the middle plate 146 and the middle plate 146 and the vent plate 160 are electrically connected to the electrode group 110 through the lead member 150 and fixed to the sub plate 147. Insulation plate 145 to insulate the middle plate 146 and the vent plate 160 is installed between.

The middle plate 146 and the insulating plate 145 are formed in a disc shape, and a hole is formed in the center to fit the convex portion 166. Although the middle plate 146 is made of a conductive material and the lead member 150 is connected to the middle plate 146 in this embodiment, the present invention is not limited thereto.

Therefore, the lead member may be configured to be directly connected to the sub plate and the middle plate is made of an insulator. In this case, the insulation plate installed on the middle plate may be removed.

As shown in FIG. 2, the protrusion 146a is integrally formed at a portion of the middle plate 146 which is in contact with the sub plate 147.

The protrusion 146a extends in the circumferential direction of the convex portion 166 to form a rib shape, and serves to separate a portion of the sub plate 147 from the middle plate 146.

The sub plate 147 is formed in a disc shape and has a discharge port (not shown) for discharging the gas generated from the electrode group. The edge of the subplate 147 is fixed by welding to the middle plate 146 and the center part is fixed by welding to the convex portion 166, wherein the projection 146a is located between the welded portions and a part between the welded portions. Is spaced apart from the middle plate 146.

When the protrusion 146a is formed on the middle plate 146 as described above, an elastic force acts on the sub plate 147 in the direction in which the protrusion 146a protrudes. That is, the sub plate 147 is convexly curved toward the inside of the case by the protrusion 146a. Since the center of the convex portion is welded to the vent plate 160 and arranged to be bent toward the upper part of the case 120. The central portion of the sub plate 147 is to have an elastic force toward the inside of the case 120.

As such, when the subplate 147 has an elastic force, when the convex portion 166 is spaced up from the subplate 147 due to the increase in the internal pressure, the central portion of the subplate 147 may be a protrusion due to the above stress. 146a) down. Accordingly, the convex portion 166 and the sub plate 147 may be spaced more quickly, and the separation distance also increases as compared with the conventional art.

The sub-plate 147 is fixed to the lower surface of the convex portion 166 by resistance welding or the like while the edge is fixed to the middle plate 146, and the center portion according to the formation position of the projection 146a. Not only the pressing force to press up changes but also the stress acting on the subplate 147 after being welded.

If the pressing force or the stress is large, the restoring force of the subplate 147 also increases, but there is a problem that the convex portion 166 detaches early from the subplate 147. The subplate 147 can be easily restored even with a small stress, but when the stress becomes larger than necessary, a problem occurs that the life of the secondary battery is shortened.

3 is a graph showing the pressing force acting on the subplate when the subplate is welded to the convex portion, and FIG. 4 is a graph showing the maximum stress acting on the subplate when the subplate and the convex portion are welded.

On the basis of the above description with reference to Figures 3 and 4 will be described with respect to the formation position of the projection.

The distance from the center of the welding portion W of the subplate 147 and the middle plate 146 to the central axis O is referred to as R, and the distance from the center of the protrusion 146a to the central axis O is referred to as X. At the time, the projections are formed at portions where X / R is 0.61 to 0.72.

If X / R is smaller than 0.61, a large pressing force must be applied as shown in FIG. 3, and the subplate 147 may be deformed in this process. If X / R is larger than 0.72, not only a large pressing force as shown in FIG. 3 should be applied, but also the maximum stress acting on the subplate 147 as shown in FIG. A problem arises in that the sub plate 147 is separated early.

In addition, the projection 146a may be formed at a position where X / R is 0.67. As shown in FIG. 3, the pressing force is minimized at the position where X / R is 0.67. As shown in FIG. 4, the maximum stress acting on the subplate 147 at the position where X / R is 0.67 is shown. It can be seen that the minimum. As such, when the protrusion is formed at the position where X / R is 0.67, the stress acting on the subplate 147 can be minimized to stably secure the time for the convex portion 166 to be spaced apart from the subplate 147. Rather, the subplate 147 may have an appropriate restoring force.

5 is a cross-sectional view showing a portion of a cap assembly according to a second embodiment of the present invention.

Referring to FIG. 5, the cap assembly according to the present exemplary embodiment has a notch 263 and a vent plate 260 and a convex portion having a convex portion 266 protruding downward to be determined at a constant pressure. A subplate 247 disposed below the 266 and fixed to the convex portion 266, a middle plate 246 disposed over the subplate 247, and between the middle plate 246 and the vent plate 260. It is disposed on the insulating plate 245 to block the flow of current.

The subplate 247 according to the present embodiment is fixed by welding to the convex portion 266 through the central welding portion and welded to the middle plate 246 through the outer circumferential welding portion. The protrusion 247a is integrally formed on the upper surface of the sub plate 247, and the protrusion 247a is formed inside the outer circumferential weld portion facing the middle plate 246.

The protrusion 247a causes the subplate 247 to be spaced apart from the middle plate 246 and stress is generated in the subplate 247. When the convex portion 266 is spaced apart from the subplate 247 and rises upward, , The subplate 247 is lowered due to the stress. As described above, in the present embodiment, the protrusion 247a is formed on the subplate 247 so that the subplate 247 and the convex portion 266 are quicker and more spaced apart from the convex portion 266 and the subplate 247. Can be spaced away.

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 cross-sectional view of a portion of a cap assembly in a first embodiment of the present invention.

3 is a graph showing the pressing force acting when the subplate according to the first embodiment of the present invention is welded to the vent plate according to the position of the protrusion.

4 is a graph showing the stress acting on the sub-plate according to the first embodiment of the present invention.

5 is a cross-sectional view showing a portion of a cap assembly according to a second embodiment of the present invention.

<Description of reference numerals for the main parts of the drawings>

100: secondary battery 110: electrode group

120: case 140: cap assembly

143: cap plate 160: vent plate

145: insulation plate 146: middle plate

146a: projection 147: middle plate projection

166: convex portion 247a: projection

Claims (12)

An electrode group including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode; A case in which the electrode group is built; A cap plate coupled to the case; A vent plate installed below the cap plate; A sub plate installed under the vent plate and welded to the vent plate and electrically connected to the electrode group; A middle plate disposed between the vent plate and the sub plate; And A protrusion provided between the middle plate and the sub plate; Secondary battery comprising a. According to claim 1, The protrusion is a secondary battery fixed to the middle plate. According to claim 1, The protrusion is a secondary battery fixed to the sub plate. The method according to any one of claims 1 to 3, The middle plate is electrically connected to the electrode group through a lead member electrically connected to the electrode group, The secondary plate is a secondary battery electrically connected to the electrode group via the middle plate. The method of claim 4, wherein The secondary battery is provided between the middle plate and the vent plate. The method of claim 1,       The vent plate is a secondary battery convex toward the inside of the case.     The method of claim 1,     The sub plate is a secondary battery convex toward the outside of the case. The method according to claim 6 or 7, A secondary battery satisfying the following conditions when X is a distance from the center of the convex portion to the protrusion and a distance from the center of the convex portion to the center of the welded portion of the subplate and the middle plate is R. 0.62 ≤ X / R ≤ 0.72 According to claim 1, The protrusion is a secondary battery formed along the circumference of the convex portion (rib) shape. According to claim 1, The protrusion is a secondary battery is arranged a plurality of spaced apart. The method of claim 1, The subplate has a secondary battery for discharging the gas generated in the electrode group. An electrode group including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode; A case in which the electrode group is built; A cap plate coupled to the case; A vent plate installed below the cap plate; A sub plate installed under the vent plate and welded to the vent and electrically connected to the electrode group; In the secondary battery comprising a middle plate disposed between the vent plate and the sub plate, The sub-plate is a secondary battery having an elastic force toward the inside of the case.

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