KR102578859B1 - Rechargeable battery - Google Patents

Abstract

One embodiment of the present invention is to provide a secondary battery that can safely discharge cells when overcharged, without being limited to the number of cells connected in parallel. A secondary battery according to an embodiment of the present invention includes an electrode assembly formed by disposing a first electrode and a second electrode on both sides of a separator, a case for accommodating the electrode assembly, and a case that is coupled to an opening of the case to seal the case. A cap plate, a first electrode terminal electrically connected to the first electrode and provided in an insulated state on the cap plate, a second electrode terminal electrically connected to the second electrode and provided in an energized state to the cap plate, and a membrane electrically separating or connecting the first electrode terminal and the cap plate, wherein the plate terminal of the first electrode terminal disposed outside the cap plate is a first plate connected to the first electrode, It includes a second plate spaced apart from the first plate, and a short circuit connected to the second plate and the first plate on both sides by a first fuse and a second fuse, respectively, and shorted to the inverted membrane.

Description

Secondary battery {RECHARGEABLE BATTERY}

This description relates to secondary batteries, and more specifically, to secondary batteries equipped with overcharge safety devices.

Unlike primary batteries, secondary batteries (rechargeable batteries) are batteries that repeatedly charge and discharge. Small-capacity secondary batteries are used in small, portable electronic devices such as mobile phones, laptop computers, and camcorders, and large-capacity secondary batteries can be used as a power source for driving motors in hybrid vehicles and electric vehicles.

For example, a secondary battery includes an electrode assembly that charges and discharges, a case that accommodates the electrode assembly, a cap plate coupled to the opening of the case, an electrode terminal that draws the electrode assembly to the outside of the cap plate, and an external short circuit when overcharged. It includes an overcharge safety device (OSD) that discharges the current charged in the electrode assembly.

For example, the overcharge safety device is provided at the negative terminal and includes a shorting tab and a membrane that are spaced apart or shorted depending on the internal pressure generated during overcharging and are normally operated or shorted externally. The shorting tab is electrically connected to the negative terminal and is disposed on the outside of the cap plate through an insulating member. The membrane is installed in the shorting hole of the cap plate, which is positively charged towards the shorting tab.

When forming secondary battery modules in parallel, one bus bar is connected to the negative terminals of the cells. That is, the connection point between the bus bar and the negative terminal is located on one side of the junction point between the shorting tab and the membrane.

This relationship between connection points and junction points makes it possible to form a secondary battery module capable of discharging a very limited number of cells connected in parallel, about 1 to 3, depending on the length of time for which the membrane is melted.

One embodiment of the present invention is to provide a secondary battery that can safely discharge cells when overcharged, without being limited to the number of cells connected in parallel.

A secondary battery according to an embodiment of the present invention includes an electrode assembly formed by disposing a first electrode and a second electrode on both sides of a separator, a case for accommodating the electrode assembly, and a case that is coupled to an opening of the case to seal the case. A cap plate, a first electrode terminal electrically connected to the first electrode and provided in an insulated state on the cap plate, a second electrode terminal electrically connected to the second electrode and provided in an energized state to the cap plate, and a membrane electrically separating or connecting the first electrode terminal and the cap plate, wherein the plate terminal of the first electrode terminal disposed outside the cap plate is a first plate connected to the first electrode, It includes a second plate spaced apart from the first plate, and a short-circuiting portion connected to the second plate and the first plate on both sides with a first fuse and a second fuse, respectively, and shorted to the inverted membrane.

The second plate may be connected to a bus bar when forming a module.

The short circuit part may be provided between the first fuse and the second fuse.

The membrane may be installed in the short-circuit hole of the cap plate and may have a protrusion facing the short-circuit portion.

The membrane is formed in a circular shape, and the protrusion may have a length set in the width direction of the cap plate.

The first fuse and the second fuse may be formed to have a thickness smaller than that of the first plate and the second plate.

The short circuit portion may be formed with an area larger than that of each of the first fuse and the second fuse.

The first electrode terminal further includes a rivet terminal connecting the plate terminal to the uncoated tab of the first electrode, and the plate terminal may be disposed on the outer surface of the cap plate through an insulating member.

The insulating member may form a through hole between the short-circuiting portion and the membrane facing each other.

The second electrode terminal is formed integrally with the cap plate, and the second electrode may be connected to the inner surface of the cap plate with a non-coated tab.

According to an embodiment of the present invention, the plate terminal of the first electrode terminal is provided with first and second fuses and a short circuit, so that when the membrane is inverted due to overcharge and comes into contact with the short circuit, the first and second fuses are By melting at different times, the current charged in the electrode assembly can be completely discharged.

That is, after the first fuse melts due to an external short circuit due to overcharge, the second fuse remains connected for a set time, allowing the current charged in the electrode assembly to be completely discharged.

Therefore, in a parallel connection module using a secondary battery in one embodiment, the connection between the membrane and the short circuit is maintained until one cell is completely discharged, and after one cell is discharged, the remaining cells can be sequentially discharged.

That is, in one embodiment, an external short circuit occurs when overcharging, and the current charged in all cells connected in parallel can be safely discharged without being limited to the number of cells connected in parallel.

1 is a perspective view of a secondary battery according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1.
Figure 3 is a perspective view of the electrode assembly applied to Figure 2.
FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. 1.
Figure 5 is a plan view of a plate terminal applied to the first electrode terminal of Figures 1 and 2.
Figure 6 is a cross-sectional view showing the normal state of the membrane with respect to the short circuit.
FIG. 7 is a cross-sectional view taken along line VII-VII of FIG. 1.
Figure 8 is a cross-sectional view showing the external short-circuit state of the membrane with respect to the short-circuit portion.
Figure 9 is a cross-sectional view showing a state in which the first fuse of the plate terminal is melted due to an external short circuit.
Figure 10 is a cross-sectional view showing a state in which the second fuse is melted after the first fuse of the plate terminal is melted.

Hereinafter, with reference to the attached drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. In order to clearly explain the present invention in the drawings, parts not related to the description are omitted, and identical or similar components are given the same reference numerals throughout the specification.

Figure 1 is a perspective view of a secondary battery according to an embodiment of the present invention, and Figure 2 is a cross-sectional view taken along line II-II of Figure 1. Referring to Figures 1 and 2, the secondary battery according to one embodiment includes an electrode assembly 10 for charging and discharging current, a case 30 containing the electrode assembly 10, and an opening 31 of the case 30. ) and a cap plate 40 coupled to the cap plate 40, and a first electrode terminal 51 and a second electrode terminal 52 electrically connected to the electrode assembly 10.

The first electrode terminal 51 (e.g., negative terminal) is provided in an insulated state on the cap plate 40, and the second electrode terminal 52 (e.g., positive terminal) is provided in an energized state on the cap plate 40. It is provided with Therefore, the cap plate 40 is positively charged. In addition, the secondary battery further includes a membrane 60 that electrically separates the first electrode terminal 51 and the cap plate 40 (normal operation) or connects them (in case of external short circuit due to overcharge).

The case 30 sets up a space to accommodate the plate-shaped electrode assembly 10 and the electrolyte solution. For example, the case 30 is formed as a substantially rectangular parallelepiped and has a square opening 31 on one side for inserting the electrode assembly 10.

The cap plate 40 is coupled to the opening 31 of the case 30 to seal the case 30. As an example, the case 30 and the cap plate 40 may be made of aluminum and welded to each other at the opening 31.

A top insulator 20 is disposed between the electrode assembly 10 and the cap plate 40. The top insulator 20 is made of an electrical insulating material that is durable against electrolyte, and can electrically insulate the electrode assembly 10 and the cap plate 40.

Figure 3 is a perspective view of the electrode assembly applied to Figure 2. Referring to Figures 2 and 3, the electrode assembly 10 includes a first electrode (11, for example, a cathode) and a second electrode (12, for example, an anode) on both sides of a separator (13), which is an electrical insulating material. It is formed by winding or stacking (not shown) the first electrode 11, the separator 13, and the second electrode 12. The first and second electrodes 11 and 12 are electrically connected to the first and second electrode terminals 51 and 52, respectively.

The first and second electrodes 11 and 12 each have coating portions 111 and 121 in which an active material is applied to a current collector of a metal foil (e.g., Cu or Al foil), and a current collector exposed by not applying the active material. It includes non-coated tabs 112 and 122 formed by . The non-coated tabs 112 and 122 are disposed at one end of the electrode assembly 10.

That is, the uncoated tabs 112 of the first electrode 11 are disposed on one side (left side of FIG. 3) from one end (top of FIG. 3) of the electrode assembly 10 and connected to the current collector 113, and the second The uncoated tabs 122 of the electrode 12 are spaced apart from the same end (top of FIG. 3) of the electrode assembly 10 and are disposed on the other side (right side of FIG. 3) and connected to the current collecting member 123.

In addition, since a plurality of uncoated tabs 112 and 122 are provided in the electrode assembly 10 to allow charging and discharging current to flow, the overall resistance of the uncoated tabs 112 and 122 is reduced. Accordingly, the electrode assembly 10 can charge and discharge high current through the uncoated tabs 112 and 122.

The electrode assembly 10 may be formed as one (not shown), but in this embodiment, it is formed as two. The electrode assembly 10 may be formed in a plate shape forming a semicircle at both ends in the y-axis direction so that it can be accommodated in the case 30 having a substantially rectangular parallelepiped shape.

FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. 1. 1 to 4, the first electrode terminal 51 is installed in the terminal hole (H) provided in the cap plate 40, and is connected to the electrode through the uncoated tab 112 of the first electrode 11. It is electrically connected to the assembly (10).

The non-coated tabs 112 are connected to the first electrode terminal 51 in the width direction (x-axis direction) via the outside of the top insulator 20 in the width direction (x-axis direction) of the cap plate 40. .

The first electrode terminal 51 includes a plate terminal 511 disposed outside the cap plate 40 and a rivet terminal 512 installed in the terminal hole (H). The plate terminal 511 is disposed on the outer surface of the cap plate 40 with an insulating member 513 interposed therebetween.

Figure 5 is a plan view of a plate terminal applied to the first electrode terminal of Figures 1 and 2, and Figure 6 is a cross-sectional view showing the normal state of the membrane for the short circuit. Referring to FIGS. 1, 2, and 4 to 6, the plate terminal 511 includes a first plate 531 connected to the first electrode 11, and a second plate spaced apart from the first plate 531 ( 532), and a short circuit 533.

The second plate 532 is connected to the bus bar (B) when forming a module that connects a plurality of cells in parallel. The short-circuiting portion 533 is connected to the second and first plates 532 and 531 on both sides with a first fuse 541 and a second fuse 542, respectively, and is in contact with and short-circuited to the inverted membrane 60.

The short circuit portion 533 is provided between the first fuse 541 and the second fuse 542 in the y-axis direction. The membrane 60 is installed in the short-circuiting hole 62 penetrating the cap plate 40 and has a protrusion 61 facing the short-circuiting portion 533.

For example, the membrane 60 is formed in a concave circular shape toward the short circuit 533, and the protrusion 61 is set in the width direction (x-axis direction) of the cap plate 40 at the concave center of the membrane 60. It has length.

Therefore, when the membrane 60 is inverted, the protrusion 61 may be in long contact with the short circuit portion 533. Although not shown, when the membrane is inverted, the protrusion may be in line contact parallel to the short circuit or may be in convex line contact toward the short circuit.

The first and second fuses 541 and 542 are formed to have a thickness smaller than that of the first and second plates 531 and 532. The short-circuiting portion 533 is formed with an area larger than that of the first and second fuses 541 and 542, respectively. Therefore, when the membrane 60 is in contact with the short circuit 533, the first and second fuses 541 and 542 may be melted sequentially while maintaining the set time.

The insulating member 513 forms a through hole 515 between the short-circuiting portion 533 and the membrane 60 that face each other. In the overcharge mode, when the membrane 60 is inverted, the protrusion 61 may contact the short circuit 533 located on the outside of the cap plate 40 through the through hole 515.

Additionally, the first electrode terminal 51 is electrically insulated from the cap plate 40 with a gasket 514 interposed therebetween. The gasket 514 is installed between the rivet terminal 512 of the first electrode terminal 51 and the inner surface of the terminal hole (H) of the cap plate 40 to seal between the rivet terminal 512 and the terminal hole (H). and electrically insulate.

Insert the rivet terminal 512 into the terminal hole (H) through the gasket 514, insert it into the coupling hole of the first plate 531 through the insulating member 513, and then caulk around the coupling hole ( The rivet terminal 512 is coupled to the first plate 531 by caulking or welding. As a result, the first electrode terminal 51 can be installed on the cap plate 40.

In this way, the rivet terminal 512 is installed in the terminal hole H, protrudes to the outside of the cap plate 40, is connected to the first plate 531, and is connected to the current collector 113 on the inside of the cap plate 40. connected to That is, the rivet terminal 512 mechanically and electrically connects the current collecting member 113 and the first plate 531 to each other.

The current collecting member 113 is connected to the non-coated tab 112. That is, the uncoated tab 112 is welded to the current collecting member 113, and the current collecting member 113 is welded to the rivet terminal 512. Accordingly, the electrode assembly 10 can be pulled out of the case 30 through the uncoated tab 112 of the first electrode 11, the current collector 113, and the first electrode terminal 51.

FIG. 7 is a cross-sectional view taken along line VII-VII of FIG. 1. Referring to FIGS. 1, 2, and 7, the second electrode terminal 52 is formed integrally with the cap plate 40, and the second electrode 12 is connected to the cap plate 40 with an uncoated tab 122. It is connected to the inner side of. That is, the second electrode terminal 52 is electrically connected to the electrode assembly 10 through the cap plate 40, the current collector 123, and the non-coated tab 122.

In this embodiment, a current collector 124 is further provided on the cap plate 40 in order to weld the current collector member 123. The current collector 124 may be formed on the cap plate 40 through a coining process and protrudes toward the electrode assembly 10. Although not shown, when a current collector is not applied, the second electrode may be connected directly to the inner surface of the cap plate or to the current collector through a non-coated tab.

The non-coated tabs 122 pass through the outside of the top insulator 20 in the width direction (x-axis direction) of the cap plate 40, and connect the current collector 123 and the cap plate 40 in the width direction (x-axis direction). ) is connected to the second electrode terminal 52.

The current collecting member 123 is connected to the non-coated tab 122. That is, the uncoated tab 122 is welded to the current collector 123, and the current collector 123 is welded to the current collector 124. Accordingly, the electrode assembly 10 is pulled out of the case 30 through the uncoated tab 122, the current collector 123, the current collector 124, and the second electrode terminal 52 of the second electrode 12. It can be.

As an example, the second electrode terminal 52 may be formed on the cap plate 40 through a coining process. That is, the second electrode terminal 52 protrudes toward the outside of the cap plate 40 in a direction opposite to the protrusion direction of the current collector 124.

The current collector 124 and the second electrode terminal 52, which are formed integrally through a coining process, are different from the current collector 113 and the first electrode terminal 51 connected to the first electrode 11. Reduce the number of components and simplify the structure.

Figure 8 is a cross-sectional view showing an external short-circuit state of the membrane with respect to the short-circuit portion, Figure 9 is a cross-sectional view showing a state in which the first fuse of the plate terminal is melted due to an external short-circuit, and Figure 10 is a cross-sectional view showing the first fuse of the plate terminal melted due to an external short-circuit. This is a cross-sectional view showing the second fuse in a melted state after melting.

Referring to FIGS. 6 and 8 to 10, when a module is formed by connecting a plurality of secondary batteries (cells) in parallel in one embodiment and the cell is operated normally, the plate terminal of the first electrode terminal 51 (51) and the membrane 60 remain in the same state as shown in FIG. 6. That is, the positively charged membrane 60 remains spaced apart from the short-circuiting portion 533 of the plate terminal 51 within the short-circuiting hole 62.

During normal operation, when one cell switches to overcharge mode, as shown in FIG. 8, the membrane 60 is reversed within the short-circuit hole 62 due to internal pressure, and the short-circuit becomes negative with the protrusion 61. It contacts the portion 533 to form an external short circuit.

At this time, the current amount divided by the total current amount of the module by the number of cells acts on the externally short-circuited cell. As an example, when a current of 20,000 A is applied to an externally short-circuited cell, a current of 16,000 A is applied to the second plate 532 to which the bus bar (B) is connected, and the first plate ( 531), a current of 4000A is applied.

When discharged due to an external short circuit, resistance is released between the protrusion 61 of the membrane 60 and the short circuit portion 533, heat is generated, and as shown in FIG. 9, a large current is applied to the second plate 532. ) The first fuse 541 on the side melts first.

Therefore, the current of 16000A acting on the second plate 532 is discharged while melting the first fuse 541, and only the current of 4000A acting on the first plate 531 acts on the cell.

During the set time, the second fuse 542 operates further to further maintain the external short circuit and discharge more current through the external short circuit, and then melts as shown in FIG. 10. Therefore, the current of 4000A acting on the first plate 531 is discharged while melting the second fuse 542. As a result, the current charged in the electrode assembly 10 of the cell is completely discharged.

In this way, the cells externally short-circuited by the membrane 60 and the short-circuiting portion 533 are sequentially melted while the first and second fuses 541 and 542 maintain the time difference, thereby discharging the cells charged in the electrode assembly 10. Discharge the current completely. Additionally, in a module that connects a plurality of cells in parallel, after discharge of one cell is completed, discharge of the remaining cells may be completed sequentially.

Referring again to FIGS. 1 to 3, the cap plate 40 further includes an electrolyte injection port 42 and a vent hole 41. The electrolyte injection port 42 allows the electrolyte to be injected into the case 30 after coupling and welding the cap plate 40 to the case 30. After electrolyte injection, the electrolyte injection port 42 is sealed with a sealing stopper 421.

The top insulator 20 has an internal electrolyte injection port 28. The internal electrolyte injection hole 28 is formed to correspond to the electrolyte injection hole 42 provided in the cap plate 40, so that the electrolyte solution via the electrolyte injection hole 42 can be smoothly injected into the interior of the top insulator 20.

The vent hole 41 is formed to discharge the internal pressure caused by the gas generated inside the secondary battery by the charging and discharging action of the electrode assembly 10, and is sealed with the vent plate 411.

As an example, the vent hole 41 and the vent plate 411 are formed integrally with the cap plate 40 through a coining process. The vent hole 41 and the bent plate 411 reduce the number of elements and simplify the structure compared to a configuration in which the bent plate is manufactured separately and welded to the vent hole.

When the internal pressure of the secondary battery reaches the set pressure, the vent plate 411 is cut to open the vent hole 41 to discharge gas and internal pressure. For this purpose, the bent plate 411 has a notch 412 that guides the incision.

The top insulator 20 has an internal vent hole 27. Since the internal vent hole 27 is formed to correspond to the vent hole 41 provided in the cap plate 40, the internal pressure increased by the gas generated in the electrode assembly 10 is transmitted to the vent hole 41 to smoothly allow it to be released.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and can be implemented with various modifications within the scope of the claims, the detailed description of the invention, and the accompanying drawings. It is natural that it falls within the scope of the invention.

10: Electrode assembly 11, 12: First and second electrodes (negative, positive)
13: Separator 20: Top insulator
27: Internal vent hole 28: Internal electrolyte injection port
30: case 31: opening
40: cap plate 41: vent hole
42: Electrolyte injection port 51: First electrode terminal (negative terminal)
52: Second electrode terminal (negative terminal) 60: Membrane
61: Protrusion 62: Short-circuit hole
111, 121: Coated portion 112, 122: Uncoated portion tab
113, 123: current collector member 124: current collector member
411: Bent plate 412: Notch
421: sealing stopper 511: plate terminal
512: Rivet terminal 513: Insulating member
514: gasket 515: through hole
531: first plate 532: second plate
533: short circuit 541: first fuse
542: Second fuse B: Busbar
H: terminal hole

Claims (10)

An electrode assembly formed by disposing a first electrode and a second electrode on both sides of a separator;
a case accommodating the electrode assembly;
a cap plate coupled to the opening of the case to seal the case;
a first electrode terminal electrically connected to the first electrode and provided in an insulated state on the cap plate;
a second electrode terminal electrically connected to the second electrode and provided in an energized state to the cap plate; and
A membrane electrically separating or connecting the first electrode terminal and the cap plate
Includes,
The plate terminal of the first electrode terminal disposed outside the cap plate is
A first plate connected to the first electrode,
a second plate spaced apart from the first plate, and
A short circuit connected to the second plate and the first plate on both sides with a first fuse and a second fuse, respectively, and shorted to the inverted membrane.
Including,
The membrane has a protrusion facing the short circuit,
The protrusion has a length set in the width direction of the cap plate,
The short circuit portion is formed with an area larger than the areas of each of the first fuse and the second fuse,
A secondary battery in which the length of the protrusion is set to be larger than the width of the first fuse and the second fuse and smaller than the length set in the width direction of the short-circuit part. According to paragraph 1,
The second plate is
When forming a module, a secondary battery is connected to the busbar. According to paragraph 1,
The paragraph section
A secondary battery provided between the first fuse and the second fuse. According to paragraph 1,
The membrane is
A secondary battery installed in the short-circuit hole of the cap plate. According to paragraph 4,
A secondary battery in which the membrane is formed in a circular shape. According to paragraph 1,
The first fuse and the second fuse are
A secondary battery formed with a thickness smaller than the thickness of the first plate and the second plate. delete According to paragraph 1,
The first electrode terminal is
It further includes a rivet terminal connecting the plate terminal to the uncoated tab of the first electrode,
The plate terminal is
A secondary battery disposed on the outer surface of the cap plate with an insulating member interposed therebetween. According to clause 8,
The insulating member is
A secondary battery forming a through hole between the short-circuiting portion and the membrane facing each other. According to paragraph 1,
The second electrode terminal is formed integrally with the cap plate,
The second electrode is connected to the inner surface of the cap plate through a non-coated tab.

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