CN111989801A

CN111989801A - Secondary battery

Info

Publication number: CN111989801A
Application number: CN201980026476.3A
Authority: CN
Inventors: 许致熏; 郭承昊; 金范来; 金振焕; 金春淑; S.朴; 杨承勋; 吴龙昊; 李炳坤
Original assignee: Samsung SDI Co Ltd
Current assignee: Samsung SDI Co Ltd
Priority date: 2018-04-17
Filing date: 2019-03-15
Publication date: 2020-11-24
Also published as: KR102538094B1; KR20190121069A; WO2019203450A1

Abstract

A secondary battery (rechargeable battery) according to one embodiment of the present invention includes: a case housing an electrode assembly for performing charge and discharge and an electrolyte solution; a cap plate sealing the opening of the case and having an electrolyte solution injection hole; and a sealing cap sealing the electrolyte solution injection hole, wherein the sealing cap includes a first coupling part sealing an inside part of the electrolyte solution injection hole and a second coupling part connected to the first coupling part to seal an outside part of the electrolyte solution injection hole.

Description

Secondary battery

Technical Field

The present disclosure relates to a secondary battery. More particularly, the present invention relates to a secondary battery in which an electrolyte injection port provided in a cap plate is sealed with a sealing stopper.

Background

Unlike a primary battery, a secondary battery is a battery that repeatedly undergoes charge and discharge. Small-capacity secondary batteries are used for portable electronic devices such as mobile phones, laptop computers, and camcorders. Secondary batteries of large capacity and high density are used as power sources or energy storage devices for driving motors of hybrid vehicles and electric vehicles.

For example, the secondary battery includes an electrode assembly that performs charge and discharge, a case that houses the electrode assembly, and a cap plate that is coupled to an opening of the case and includes an electrolyte injection port and a sealing plug that seals the electrolyte injection port.

The manufacturing process of the secondary battery includes an electrode process, an assembly process, and a conversion process. The assembly process includes pre-charging directly after the secondary battery is assembled, and the pre-charging generates gas inside the secondary battery.

The conversion process is a process of making the assembled secondary battery function as a battery. The switching process is a charging process for shutting down and sealing the secondary battery after removing gas generated during the pre-charging.

That is, the conversion process is a process of converting chemical energy into electrochemical energy by supplying electrical energy to the secondary battery. During the switching process, the active materials of the positive and negative electrodes change from a low energy state to a high energy state.

During the conversion process, gas is generated again inside the secondary battery. For example, if the electrolyte solution is a carbonate-based organic solvent, gas is generated as a part of the electrolyte solution is decomposed during the pre-charging process and is discharged before the conversion process. After the pre-charging, since the secondary battery is closed and sealed before the conversion process, the internal pressure of the secondary battery is increased due to the gas generated by the conversion process.

When gas generated during the conversion process remains inside the secondary battery, the quality of the secondary battery is deteriorated. Therefore, it is necessary to remove the gas remaining inside the secondary battery after the conversion process.

Disclosure of Invention

Technical problem

An aspect of the present invention is to provide a secondary battery that seals an electrolyte injection port through a sealing stopper after gas generated during conversion is discharged through the electrolyte injection port.

Technical scheme

A secondary battery according to an exemplary embodiment of the present invention includes: a case accommodating an electrode assembly for charging and discharging and an electrolyte solution; a cover plate closing and sealing the opening of the case and having an electrolyte injection port; and a sealing plug sealing the electrolyte injection port, wherein the sealing plug includes a first coupling part sealing an inside part of the electrolyte injection port and a second coupling part connected to the first coupling part and sealing an outside part of the electrolyte injection port.

An electrolyte injection port according to an exemplary embodiment of the present invention may include: a first inlet formed with a first inner perimeter; and a second inlet connected to the first inlet and formed with a second inner circumference larger than the first inner circumference.

The first inlet according to an exemplary embodiment of the present invention may be formed as a cylindrical through hole having a first inner circumference, and the second inlet may be formed as an extended through hole gradually extended and having a second inner circumference.

The first coupling part according to an exemplary embodiment of the present invention may be formed as a cylinder corresponding to the cylindrical through hole, and the second coupling part may include a cylindrical part connected to the first coupling part and corresponding to the first inlet port and a tapered part connected to the cylindrical part and corresponding to the second inlet port.

The second coupling part according to an exemplary embodiment of the present invention may be filled into the second inlet to form the same plane as the outer surface of the cap plate.

The sealing plug according to an exemplary embodiment of the present invention may further include a fixing portion connected to the first coupling portion and fixed to the inside portion of the first inlet.

An inner surface around the electrolyte injection port according to an exemplary embodiment of the present invention may form one plane with the inner surface of the cap plate.

An inner surface around the electrolyte injection port according to an exemplary embodiment of the present invention may be formed with a protrusion protruding from an inner surface of the cap plate toward the inside of the case.

The first inlet according to an exemplary embodiment of the present invention may form a first inner circumference as a first cylindrical through hole, and the second inlet may form a second inner circumference as a second cylindrical through hole larger than the first cylindrical through hole.

The sealing plug may be formed of PE (polyethylene), PFA (perfluoroalkoxy) or PTFE (polytetrafluoroethylene).

A sealing stopper for closing and sealing an electrolyte injection port of a secondary battery according to an exemplary embodiment of the present invention includes: a first coupling part sealing an inside part of the electrolyte injection port; and a second coupling part connected to the first coupling part to seal an outer side portion of the first inlet.

Advantageous effects

According to an exemplary embodiment of the present invention, after the pre-charging, the switching process is performed in a state that the sealing plug is completely removed from the electrolyte injection port, and after the switching process (i.e., after the gas generated during the switching process is discharged to the dielectric injection port to remove the gas), the electrolyte injection port may be sealed by the sealing plug. Therefore, since the gas generated during the conversion process and may remain inside the secondary battery is discharged, the quality of the secondary battery may be improved.

Drawings

Fig. 1 is a perspective view of a secondary battery according to a first embodiment of the present invention.

Fig. 2 is a sectional view taken along line ii-ii of fig. 1.

Fig. 3 is a sectional view showing a state (after pre-charging and before a conversion process) where a sealing plug is pre-assembled to an electrolyte injection port provided at the cap plate of fig. 2.

Fig. 4 is a sectional view of a state in which gas is discharged to the electrolyte injection port (or before pre-assembly) by temporarily withdrawing the sealing plug from the electrolyte injection port during the conversion process in the state of fig. 3.

Fig. 5 is a sectional view of a state where the sealing plug is completely assembled to the electrolyte injection port after the gas generated during the conversion process is discharged as in fig. 4.

Fig. 6 is a sectional view illustrating a state in which a sealing plug is preassembled to an electrolyte injection port of a secondary battery (after pre-charging and before a conversion process) according to a second embodiment of the present invention.

Fig. 7 is a sectional view of a state where the sealing plug is completely assembled to the electrolyte injection port after gas is discharged to the electrolyte injection port by temporarily withdrawing the sealing plug from the electrolyte injection port during a conversion process in the state of fig. 6.

Fig. 8 is a sectional view illustrating a state in which a sealing plug is preassembled to an electrolyte injection port of a secondary battery (after pre-charging and before a conversion process) according to a third embodiment of the present invention.

Fig. 9 is a sectional view of a state where the sealing plug is completely assembled to the electrolyte injection port after gas is discharged to the electrolyte injection port by temporarily withdrawing the sealing plug from the electrolyte injection port during a conversion process in the state of fig. 8.

Fig. 10 is a sectional view of a secondary battery according to a third embodiment of the present invention in a state in which gas is discharged to an electrolyte injection port (or before pre-assembly) by temporarily withdrawing a sealing stopper from the electrolyte injection port during a conversion process.

Fig. 11 is a sectional view of a state where the sealing plug is completely assembled to the electrolyte injection port after the conversion process of fig. 10 (after the gas generated during the conversion process is discharged).

Detailed Description

The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. Those skilled in the art will recognize that the described embodiments can be modified in various different ways, all without departing from the spirit or scope of the present invention. The drawings and description are to be regarded as illustrative in nature, and not as restrictive. Like reference numerals refer to like elements throughout the specification.

Fig. 1 is a perspective view of a secondary battery according to a first embodiment of the present invention, and fig. 2 is a sectional view taken along line ii-ii of fig. 1.

Referring to fig. 1 and 2, the secondary battery 1 may include an electrode assembly 10 that charges and discharges current, a case 15 that houses the electrode assembly 10, a cap plate 20 coupled to an opening of the case 15, and a sealing plug 27 that seals an electrolyte injection port 29 provided at the cap plate 20.

The secondary battery 1 may further include electrode terminals (negative and positive terminals) 21 and 22 mounted at the cap plate 20 and an Overcharge Safety Device (OSD) 40.

For example, the electrode assembly 10 may be formed by: negative electrode 11 and positive electrode 12 are provided on respective surfaces of separator 13 of an electrically insulating material; and the negative electrode 11, the separator 13, and the positive electrode 12 are spirally wound in a jelly-roll state. Although not shown in the drawings, the electrode assembly may be formed in a stack type in which a negative electrode, a separator, and a positive electrode are stacked.

The negative electrode 11 and the positive electrode 12 respectively include:

coating portions

11a and 12a in which an active material is coated to a current collector of a metal plate; and

uncoated portions

11b and 12b formed as exposed current collectors because the active material is not coated thereto.

The uncoated portion 11b of the negative electrode 11 may be formed at one end of the negative electrode 11 along the wound negative electrode 11. The uncoated portion 12b of the positive electrode 12 may be formed at one end of the positive electrode 12 along the positive electrode 12 that is wound. Further, uncoated

portions

11b and 12b are disposed at opposite ends of the electrode assembly 10.

For example, the case 15 is shaped substantially in a rectangular parallelepiped so as to provide a space for accommodating the electrode assembly 10, and an opening of the case 15 is formed at one side of the rectangular parallelepiped to connect an external space and an internal space of the rectangular parallelepiped. The opening may enable the electrode assembly 10 to be inserted into the case 15.

A cover plate 20 may be mounted to the opening of the housing 15 to close and seal the housing 15. For example, the case 15 and the cap plate 20 may be formed of aluminum such that they may be welded to each other.

In addition, the cap plate 20 may be provided with an electrolyte injection port 29, a gas discharge hole 24, and terminal holes H1 and H2. The vent hole 24 may be closed and sealed with a vent plate 25 to release the internal pressure of the secondary battery 1 in the event of a failure.

When the internal pressure of the secondary battery 100 reaches a predetermined pressure (excessive pressure), the vent plate 25 may rupture to open the vent hole 24. Vent plate 25 includes a notch 25a that initiates the rupture.

The negative and

positive terminals

21 and 22 may be provided in the terminal holes H1 and H2 of the cap plate 20, respectively, and electrically connected to the electrode assembly 10. That is, the negative terminal 21 is electrically connected to the negative electrode 11 of the electrode assembly 10, and the positive terminal 22 is electrically connected to the positive electrode 12 of the electrode assembly 10. Accordingly, the electrode assembly 10 may be drawn out to the outside of the case 15 through the negative electrode terminal 21 and the positive electrode terminal 22.

The negative terminal 21 and the positive terminal 22 may have the same structure as each other inside the cap plate 20. Therefore, the same structures are illustrated together, and since different structures are formed outside the cap plate 20, different structures are separately described.

The negative and

positive terminals

21 and 22 may include

rivet terminals

21a and 22a mounted at terminal holes H1 and H2 of the cap plate 20, respectively, flanges 21b and 22b formed to be wide integral with the

rivet terminals

21a and 22a inside the cap plate 20, and

plate terminals

21c and 22c provided outside the cap plate 20 to be connected to the

rivet terminals

21a and 22a by riveting or welding.

The negative and

positive gaskets

36 and 37 are mounted between the

rivet terminals

21a and 22a of the positive and

negative terminals

21 and 22 and the inner surfaces of the terminal holes H1 and H2 of the cap plate 20, respectively, to seal and establish electrical insulation between the

rivet terminals

21a and 22a of the negative and

positive terminals

21 and 22 and the cap plate 20.

The negative electrode gasket 36 and the positive electrode gasket 37 extend between the flanges 21b and 22b and the inner surface of the cap plate 20, and they may further seal the space between the flanges 21b and 22b and the cap plate 20 and electrically insulate the flanges 21b and 22b from the cap plate 20 b. That is, when the negative and

positive terminals

21 and 22 are mounted in the cap plate 20, the negative and

positive gaskets

36 and 37 may prevent the electrolyte solution from leaking through the terminal holes H1 and H2.

The negative and positive

lead tabs

51 and 52 electrically connect the negative and

positive terminals

21 and 22 to the negative and positive electrodes 11 and 12 of the electrode assembly 10, respectively. That is, by coupling the

lead tabs

51 and 52 to the lower end portions of the

rivet terminals

21a and 22a and by caulking the lower end portions, the

lead tabs

51 and 52 can be connected to the lower end portions of the

rivet terminals

21a and 22a while being supported by the flanges 21b and 22 b.

The negative and positive insulating

members

61 and 62 may be separately installed between the negative and positive

lead tabs

51 and 52 and the cap plate 20 to electrically insulate the negative and positive

lead tabs

51 and 52 from the cap plate 20.

The negative and positive insulating

members

61 and 62 are connected to the cap plate 20 at one side and cover the negative and positive

lead tabs

51 and 52, the

rivet terminals

21a and 22a, and the flanges 21b and 22b at the other side, so that their connection structure is stable.

The overcharge safety device 40 is described with respect to the plate terminal 21c of the negative terminal 21, and the top plate 46 is described with respect to the plate terminal 22c of the positive terminal 22.

The overcharge safety device 40 on the negative terminal 21 side may be configured to realize an external short circuit when gas is internally generated due to overcharge of the secondary battery 1 and thus the internal pressure is increased.

For example, the overcharge safety device 40 can include a separate or shorted shorting tab 41 and shorting member 43. The shorting tab 41 may be electrically connected to the rivet terminal 21a of the negative terminal 21 and disposed outside the cap plate 20 through the interposed insulating member 31.

The insulating member 31 may be installed between the shorting tab 41 and the cap plate 20 to electrically insulate the shorting tab 41 from the cap plate 20. That is, the cap plate 20 may maintain its state of being electrically insulated from the negative terminal 21.

By coupling the shorting tab 41 and the plate terminal 21c to the upper end of the rivet terminal 21a and caulking the upper end, the shorting tab 41 and the plate terminal 21c may be joined to the upper end of the rivet terminal 21 a. Accordingly, the short circuit tab 41 and the board terminal 21c may be fixed to the cap plate 20 with the insulating member 31 interposed therebetween.

The short circuit member 43 may be installed in the short circuit hole 42 formed in the cap plate 20. The shorting tab 41 may be connected to the negative terminal 21 and extend along the outside of the shorting member 43.

Accordingly, the short tab 41 and the short member 43 correspond to each other in the short hole 42 and face each other to maintain the separated state (solid line state), and when the internal pressure of the secondary battery 1 increases due to overcharge and reaches an excessive pressure, the short state (imaginary line state) may be formed by the inversion of the short member 43.

The top plate 46 adjacent to the positive terminal 22 may be electrically connected to the plate terminal 22c of the positive terminal 22 and the cap plate 20. For example, the top plate 46 may be interposed between the board terminal 22c and the cap plate 20, and may penetrate the rivet terminal 22 a.

By coupling and caulking the top plate 46 and the board terminal 22c to the upper end of the rivet terminal 22a, the top plate 46 and the board terminal 22c are coupled to the upper end of the rivet terminal 22 a. The board terminal 22c may be mounted on the outer side of the cap plate 20 with the top plate 46 interposed therebetween.

Meanwhile, the positive electrode gasket 37 may be further extended and mounted between the rivet terminal 22a and the top plate 46. Therefore, the positive gasket 37 prevents the rivet terminal 22a and the top plate 46 from being electrically and directly connected to each other. That is, the rivet terminal 22a may be electrically connected to the top plate 46 through the plate terminal 22 c.

On the other hand, the electrolyte injection port 29 provided in the cap plate 20 allows an electrolyte solution to be injected into the case 15 after the cap plate 20 is coupled to the case 15. After the injection of the dielectric solution, the electrolyte injection port 29 may be sealed by a sealing plug 27.

Referring to fig. 3, the electrolyte injection port 29 is considered as a pre-assembled sealed state by means of the sealing plug 27 after pre-charging and before the switching process.

That is, after discharging the gas generated during the pre-charging, the sealing plug 27 may be pre-assembled to the electrolyte injection port 29. The sealing plug 27 may be coupled to be withdrawn from the electrolyte injection port 29 by opening the electrolyte injection port 29 to discharge gas during the conversion process. The preassembly of the sealing plug 27 makes it possible to withdraw it from the electrolyte injection opening 29 after the precharging and before the switching process.

Referring to fig. 4, during the conversion process, the electrolyte injection port 29 may release gas generated during the conversion process to be removed by temporary opening of the pre-assembled sealing plug 27. The pre-assembled sealing plug 27 can be reused or replaced with a new product after the conversion process.

Referring to fig. 5, after venting and removing the gases generated during the conversion process, the electrolyte injection port 29 may be resealed by the sealing plug 27 which has been preassembled. At this point, the sealing plug 27 can be replaced with a new product.

As shown in fig. 3 to 5, after the pre-charging, by temporarily withdrawing the sealing plug 27 from the electrolyte injection port 29 during the switching process, after the gas generated inside the secondary battery 1 is discharged, the gas may not remain inside the secondary battery 1 because the electrolyte injection port 29 is sealed by the sealing plug 27 again. That is, the quality of the secondary battery 1 can be improved.

Referring again to fig. 3 to 5, in detail, the electrolyte injection port 29 may include a first inlet 291 formed with a first inner circumference and a second inlet 292 formed with a second inner circumference. The second inlet 292 is connected to the first inlet 291, and is formed to be larger than the first inner circumference.

The sealing plug 27 may be formed to be sealed in correspondence with the first inlet 291 and the second inlet 292 of the electrolyte injection port 29. For example, the sealing plug 27 may include a first coupling portion 271 and a second coupling portion 272.

The first coupling part 271 may seal the outer part 91a of the first inlet 291 (in a pre-assembled state) after pre-charging and before the switching process, and may seal the inner part 91b of the first inlet 291 after the switching process. That is, after the conversion process, when the sealing plug 27 is completely assembled to the electrolyte injection port 29, the first coupling part 271 may seal the inside part 91 b.

The second coupling portion 272 is connected to the first coupling portion 271 after precharging and before the switching process so as to be separated from the second inlet 292 (in a pre-assembled state), and after the switching process, seals the second inlet 292 and the outer portion 91a of the first inlet 291. That is, after the conversion process, when the sealing plug 27 is completely assembled to the electrolyte injection port 29, the second coupling portion 272 may seal the second inlet 292 and the outer portion 91 a.

In the first inlet 291, the boundary between the outer part 91a and the inner part 91b may be determined within a range, which may have a mutual fastening force to the extent that the sealing stopper 27 does not separate from the electrolyte injection port 29 when the secondary battery 1 is disposed, after the pre-charging and before the conversion process.

For example, the first inlet 291 may form a first inner circumference as a cylindrical through hole, and the second inlet 292 may be formed of an extended through hole that gradually expands the second inner circumference from the first inlet 291 to the outside.

The first coupling part 271 may be formed of a cylinder corresponding to the cylindrical through hole. The second coupling portion 272 may include: a cylindrical portion 721 connected to the first coupling portion 271 and corresponding to the first inlet 291; and a tapered portion 722 connected to the cylindrical portion 721 and corresponding to the second inlet 292.

The taper 722 may fill in the second inlet 292 after the conversion process to form the same plane as the outer surface of the cover plate 20. The taper portion 722 can preassemble the sealing plug 27 to the electrolyte injection port 29, withdraw the preassembled sealing plug 27 from the electrolyte injection port 29 during the conversion process, or easily dispose the sealing plug 27 when the sealing plug 27 is completely assembled to the electrolyte injection port 29 after gas is discharged by withdrawing the sealing plug 27.

The first coupling part 271 may be coupled to the outer part 91a of the first inlet 291 by press-fitting (force fitting) when the sealing plug 27 is pre-assembled in the electrolyte injection port 29 after the pre-charging and before the conversion process, and may be coupled to the inner part 91b of the first inlet 291 by press-fitting when the sealing plug 27 is completely assembled to the electrolyte injection port 29 after the conversion process. Therefore, the first coupling part 271 of the sealing plug 27 may maintain the sealed state of the electrolyte injection port 29 after the pre-charging and before the switching process.

The second coupling portion 272 may be separated from the second inlet 292 when the sealing plug 27 is preassembled to the electrolyte injection port 29 after the pre-charging and before the conversion process, and may be coupled to the outer part 91a of the first inlet 291 and the second inlet 292 by press-fitting when the sealing plug 27 is completely assembled to the electrolyte injection port 29 after the conversion process. Therefore, the first and

second coupling parts

271 and 272 of the sealing plug 27 can stably maintain the sealed state of the electrolyte injection port 29 after the switching process.

The inner surface of the cap plate 20 around the electrolyte injection port 29 may form a plane with the inner surface of the cap plate 20. Further, the end 273 of the first coupling part 271 is formed to be smaller than the inner diameter of the first inlet 291, and thus the insertion of the sealing member 27 into the electrolyte injection port 29 can be facilitated.

The end 273 may be disposed in a space between the case 15 and the cover plate 20 outside the first inlet 291. Therefore, the coupling range between the first coupling part 271 and the first inlet 291 is ensured to be the maximum, thereby ensuring coupling and sealing performance.

As an embodiment, the sealing plug 27 is formed of Polyethylene (PE), Perfluoroalkoxy (PFA), or Polytetrafluoroethylene (PTFE) so as to have a predetermined elastic restoring force. That is, the sealing plug 27 can maintain the elastic restoring force even after the conversion process.

Therefore, after the pre-charging and before the conversion process, the sealing plug 27 may be pre-assembled in the electrolyte injection port 29, and during the conversion process, the sealing plug 27 may be temporarily withdrawn from the electrolyte injection port 29 to discharge the internal gas generated during the conversion process. After the conversion process, the sealing plug 27 can be completely assembled into the electrolyte injection opening 29 again elastically. That is, the sealing performance between the sealing plug 27 and the electrolyte injection port 29 can be ensured.

Further, when the sealing plug 27 is used as a temporary sealing plug after the precharge and before the transfer process, it can be manufactured by injection molding to reduce the manufacturing cost. The sealing plug 27 is made to have a predetermined diameter larger than the electrolyte injection port 29, and thus press fitting can be easily achieved to achieve desired sealing performance.

Further, the sealing plug 27 may be applied to a work of removing internal gas of the secondary battery 1 or injecting an electrolyte solution, and may be repeatedly reused many times in a product of the same specification.

Further, the sealing plug 27 enables supply and process management in the process of assembling the secondary battery 1, and thus it can be added as an automated process during the production process of the secondary battery 1.

Further, the sealing plug 27 is temporarily withdrawn from the electrolyte injection port 29 of the secondary battery 1 at the point where the gas is finally generated to remove the gas, thereby greatly improving the quality of the secondary battery 1.

Hereinafter, various exemplary embodiments of the present invention are described. Hereinafter, description of the same configuration is omitted by comparing the exemplary embodiment with the first embodiment and the previously described embodiments, and a different configuration is described.

Fig. 6 is a sectional view illustrating a state in which a sealing plug is preassembled to an electrolyte injection port of a secondary battery according to a second embodiment of the present invention (after pre-charging and before a conversion process), and fig. 7 is a sectional view illustrating a state in which the sealing plug is completely assembled to the electrolyte injection port after gas is discharged to the electrolyte injection port by temporarily withdrawing the sealing plug from the electrolyte injection port during the conversion process in the state of fig. 6.

Referring to fig. 6 and 7, in the cap plate 220 of the secondary battery 2 according to the second embodiment of the present invention, the inner surface around the electrolyte injection port 48 may be formed with a protrusion 48P protruding from the inner surface of the cap plate 20 toward the inside of the case 15.

Compared to the first inner circumference of the first inlet 291 according to the first embodiment of the present invention being formed of a cylindrical through hole, the cylindrical through hole of the first inlet 481 of the second embodiment may extend through the protrusion 48P.

In the sealing plug 56, the first coupling portion 561 may be formed as a cylindrical body corresponding to a cylindrical through hole further extending to the protrusion 48P. The cylinder of the first coupling part 561 of the second embodiment may be formed to be longer corresponding to the extended cylindrical through hole, compared to the first coupling part 271 according to the first embodiment of the present invention formed to be a cylinder corresponding to the cylindrical through hole.

The second coupling portion 562 may include: a cylindrical portion 621 connected to the first coupling portion 561 and corresponding to the first inlet 481 further extending in the protruding portion 48P; and a tapered part 622 connected to the cylindrical part 621 and corresponding to the second inlet 482.

The taper 622 may be filled in the second inlet 482 after the conversion process to form the same plane as the outer surface of the cap plate 220. The taper 622 can pre-assemble the sealing plug 56 to the electrolyte injection port 48, withdraw the pre-assembled sealing plug 56 from the electrolyte injection port 48 during the conversion process, or easily dispose of the sealing plug 56 when the sealing plug 56 is fully assembled to the electrolyte injection port 48 after venting gas by withdrawing the sealing plug 56.

In the sealing plug 56, the first coupling part 561 may be coupled to the outer part 81a of the first inlet 481 by press-fitting when the sealing plug 56 is pre-assembled in the electrolyte injection port 48 after pre-charging and before the conversion process, and may be coupled to the inner part 81b of the first inlet 481 extending in the protrusion 48P by press-fitting when the sealing plug 56 is completely assembled to the electrolyte injection port 48 after the conversion process. Therefore, the first coupling part 561 of the sealing plug 56 can maintain the sealed state of the electrolyte injection port 48 after the pre-charging and before the switching process.

In the second embodiment of the present invention, when the cap plate 20 has the same thickness as the cap plate 20 of the first embodiment, the protrusion 48P and the inner side part 81b of the first inlet 481 may further improve fastening and sealing performance with the first coupling part 561 after the conversion process, compared to the first embodiment.

The second coupling portion 562 is separated from the second inlet 482 when the sealing plug 56 is pre-assembled to the electrolyte injection port 48 after the pre-charging and before the switching process, and may be coupled to the outer portion 81a of the first inlet 481 and the second inlet 482 by press-fitting when the sealing plug 56 is fully assembled to the electrolyte injection port 48 after the switching process. Therefore, the first and

second coupling parts

561 and 562 of the sealing plug 56 can firmly maintain the sealed state of the electrolyte injection port 48 after the switching process.

In the first inlet 481, the boundary between the outer part 81a and the inner part 81b may be determined within a range, which may have a mutual fastening force to such an extent that the sealing stopper 56 is not separated from the electrolyte injection port 38 when the secondary battery 2 is disposed, after the pre-charging and before the conversion process.

Since the first inlet 481 includes the protrusion 48P and the cylindrical through hole extending further, in the second embodiment, the boundary of the outer part 81a and the inner part 81b can be moved further toward the inside of the housing 15 than in the first embodiment.

Fig. 8 is a sectional view illustrating a state in which a sealing plug is preassembled to an electrolyte injection port of a secondary battery according to a third embodiment of the present invention (after pre-charging and before a conversion process), and fig. 9 is a sectional view illustrating a state in which the sealing plug is completely assembled to the electrolyte injection port after gas is discharged to the electrolyte injection port by temporarily withdrawing the sealing plug from the electrolyte injection port during the conversion process in the state of fig. 8.

Referring to fig. 8 and 9, in the secondary battery 3 according to the third embodiment of the present invention, the first inlet 551 of the electrolyte injection port 55 may have a first inner circumference formed of a first cylindrical through-hole, and the second inlet 552 may have a second inner circumference formed of a second cylindrical through-hole larger than the first cylindrical through-hole.

The inner surface around the electrolyte injection port 55 in the cap plate 320 may form a protrusion 58P protruding from the inner surface of the cap plate 320 toward the inside of the case 15. The first cylindrical through hole of the first inlet 551 further extends through the projection 58P.

In the sealing plug 54, the first coupling portion 541 may be formed as a cylinder corresponding to the first cylindrical through hole further extending to the projection 58P. The second coupling portion 542 may include: a first cylindrical portion 421 connected to the first coupling portion 541 and corresponding to a first entrance 551 extending further to the projection 58P; and a second cylindrical portion 422 connected to the first cylindrical portion 421 and corresponding to the second inlet 552.

The second cylindrical portion 422 may be filled in the second inlet 552 after the conversion process to form the same plane as the outer surface of the cap plate 320. The second cylindrical portion 422 may preassemble the sealing plug 54 to the electrolyte injection port 55, withdraw the preassembled sealing plug 54 from the electrolyte injection port 55 during the conversion process, or may easily dispose of the sealing plug 54 when the sealing plug 54 is completely assembled to the electrolyte injection port 55 after gas is exhausted by withdrawing the sealing plug 54.

In the sealing plug 54, the first coupling portion 541 may be coupled to the outside portion 51a of the first inlet 551 by press-fitting when the sealing plug 54 is pre-assembled in the electrolyte injection port 55 after the pre-charging and before the conversion process, and may be coupled to the inside portion 51b of the first inlet 551 extending to the protrusion 58P by press-fitting when the sealing plug 54 is completely assembled to the electrolyte injection port 55 after the conversion process. Therefore, the first coupling portion 541 of the sealing plug 54 can maintain the sealed state of the electrolyte injection port 55 after the pre-charging and before the switching process.

In the third embodiment of the present invention, when the cap plate 320 has the same thickness as the cap plate 20 of the first embodiment, the protrusion 58P and the inner portion 51b of the first inlet 551 may further improve fastening and sealing performance with the first coupling part 571 after the conversion process, compared to the first embodiment.

The second coupling portion 542 is separated from the second inlet 552 when the sealing plug 54 is preassembled to the electrolyte injection port 55 after the precharging and before the conversion process, and may be coupled to the outside portion 51a of the first inlet 551 and the second inlet 552 by press-fitting when the sealing plug 54 is completely assembled to the electrolyte injection port 55 after the conversion process. Therefore, the first and

second coupling parts

541 and 542 of the sealing plug 54 can firmly maintain the sealed state of the electrolyte injection port 55 after the conversion process.

Fig. 10 is a sectional view of a secondary battery according to a third embodiment of the present invention in a state in which gas is discharged to an electrolyte injection port (or before pre-assembly) by temporarily withdrawing a sealing stopper from the electrolyte injection port during a conversion process, and fig. 11 is a sectional view of a state in which the sealing stopper is completely assembled to the electrolyte injection port after the conversion process of fig. 10 (after gas generated during the conversion process is discharged).

Referring to fig. 10 and 11, in the secondary battery 4 according to the fourth embodiment of the present invention, the sealing plug 47 may further include a fixing portion 373 that is connected to the first coupling portion 271 and fixed to the inner portion 91b of the first inlet 291.

The fixing portion 373 may be deformed and coupled to the outer part 91a of the first inlet 291 by press-fitting when the sealing plug 47 is pre-assembled in the electrolyte injection port 29 after the pre-charging and before the conversion process.

Further, after the conversion process, when the sealing plug 47 is completely assembled to the electrolyte injection port 29, the fixing portion 373 penetrates the inside portion 91b of the first inlet 291 and is caught on the inner surface around the electrolyte injection port 29, so that the sealing plug 47 can be fixed to the electrolyte injection port 29.

Therefore, the fixing portion 373 of the sealing plug 27 can more firmly maintain the sealed state of the electrolyte injection port 29 after the conversion process.

While the invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not to be 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.

Description of the symbols-

1. 2, 3, 4: the secondary battery 10: electrode assembly

11. 12: negative and

positive electrodes

11a, 12 a: coating part

11b, 12 b: uncoated portion 13: partition board

15:

housing

20, 220, 320: cover plate

21. 22: negative and

positive terminals

21a and 22 a: rivet terminal

21b, 22 b:

flanges

21c, 22 c: plate terminal

24: exhaust hole 25: exhaust plate

25 a:

notches

27, 47, 54, 56: sealing plug

29. 48, 55: electrolyte injection port 31: insulating member

36. 37: negative electrode gasket, positive electrode gasket 40: overcharge Safety Device (OSD)

41: short-circuit tab 43: short-circuit component

46:

top plates

48P, 58P: projection part

51. 52: negative electrode lead tab, positive

electrode lead tab

51a, 81a, 91 a: outer part

51b, 81b, 91 b: inner portions 61, 62: negative electrode insulating member and positive electrode insulating member

271. 561, 541:

first coupling portions

272, 562, 542: second coupling part

273: end 291, 481, 551: first inlet

292. 482, 552: second inlet 373: fixing part

421. 522: first and second cylindrical portions 621 and 721: cylindrical part

622. 722: tapers H1, H2: terminal hole

Claims

1. A secondary battery comprising:

a case accommodating an electrode assembly for charging and discharging and an electrolyte solution;

a cover plate closing and sealing the opening of the case and having an electrolyte injection port; and

a sealing plug sealing the electrolyte injection port,

wherein the sealing plug comprises:

a first coupling part sealing an inside part of the electrolyte injection port, and

a second coupling part connected to the first coupling part and sealing an outer portion of the electrolyte injection port.

2. The secondary battery according to claim 1, wherein

The electrolyte injection port includes:

a first inlet formed with a first inner perimeter; and

a second inlet connected to the first inlet and formed with a second inner circumference larger than the first inner circumference.

3. The secondary battery according to claim 2, wherein

The first inlet is formed as a cylindrical through hole having the first inner periphery, an

The second inlet is formed as an extended through-hole gradually extending and having the second inner circumference.

4. The secondary battery according to claim 3, wherein

The first coupling portion is formed as a cylinder corresponding to the cylindrical through-hole, an

The second coupling part includes a cylindrical part connected to the first coupling part and corresponding to the first inlet, and a tapered part coupled to the cylindrical part and corresponding to the second inlet.

5. The secondary battery according to claim 2 or claim 4, wherein

The second coupling part is filled to the second inlet to form the same plane as the outer surface of the cap plate.

6. The secondary battery according to claim 1, wherein

The sealing plug further includes a fixing portion connected to the first coupling portion and fixed to an inside portion of the first inlet.

7. The secondary battery according to claim 1, wherein

The inner surface around the electrolyte injection port and the inner surface of the cap plate form a plane.

8. The secondary battery according to claim 2, wherein

An inner surface around the electrolyte injection port forms a protrusion protruding from an inner surface of the cap plate toward an inside of the case.

9. The secondary battery according to claim 2, wherein

The first inlet forms the first inner periphery as a first cylindrical through-hole, an

The second inlet forms the second inner periphery as a second cylindrical through hole that is larger than the first cylindrical through hole.

10. The secondary battery according to claim 1, wherein

The sealing plug is formed from PE (polyethylene), PFA (perfluoroalkoxy) or PTFE (polytetrafluoroethylene).

11. A sealing stopper for closing and sealing an electrolyte injection port of a secondary battery, comprising:

a first coupling part sealing an inside part of the electrolyte injection port; and

a second coupling part connected to the first coupling part to seal an outer side portion of the first inlet.