KR100880385B1 - Secondary battery including insulation member to improve safety - Google Patents

Abstract

The present invention provides a secondary battery having improved safety, comprising: a plate-shaped body having a shape corresponding to an inner surface of a metal can, a support part protruding from both ends of the body, and an electrode tab of an electrode assembly connected to a corresponding portion of a top cap. Provided is a secondary battery in which an insulating member including a shielding film extending from a side surface of the main body in a direction in which the electrode tab is bent and protrudes is mounted on an electrode assembly.

Description

Secondary Battery Containing Insulating Member Improving Safety {Secondary Battery Containing Insulating Member of Improving Safety}

1 is a plan view of the bottom surface of a top cap according to the prior art for use in prismatic batteries;

2 is a perspective view of an insulating member according to one embodiment used in the rectangular battery of the present invention;

3A is a vertical cross-sectional view of a secondary battery according to one embodiment of the present invention;

3B is a partially enlarged view of a secondary battery according to one embodiment of the present invention;

Figure 4 is a schematic diagram of the assembly process of the square battery according to an embodiment of the present invention.

The present invention relates to a secondary battery including an insulation member for improving safety, and more particularly, an electrode assembly including a cathode / separator / cathode structure is inserted into a rectangular metal can and is insulated on top of the electrode assembly. A secondary battery in which a member is mounted to maintain an electrical insulation state with respect to a top cap, wherein the insulation member includes a plate-shaped body corresponding to an inner surface of a metal can, a support part protruding from both ends of the body, and an electrode assembly. The secondary battery is configured to include a shielding film extending from the side of the main body in the direction in which the electrode tab is bent and protruded during the assembly process is connected to the corresponding portion of the top cap.

As technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source is rapidly increasing, and accordingly, a lot of researches on batteries that can meet various demands have been conducted.

Typically, there is a high demand for lithium secondary batteries such as high energy density, discharge voltage, and output stability lithium ion polymer battery in terms of battery material. There is a high demand for square batteries and pouch-type batteries that can also be used as batteries of stacked battery modules.

One of the major research challenges in these cells is to improve safety. For example, a lithium secondary battery may have high temperatures inside the battery, which may be caused by abnormal operating conditions of the battery, such as internal short circuits, overcharge conditions exceeding the allowed currents and voltages, exposure to high temperatures, dropping, or deformation from external shocks. And explosion of the battery by high pressure.

In particular, a secondary battery including a jelly-roll type electrode assembly wound by placing a separator between a positive electrode, a negative electrode, and a separator therebetween may have internal short-circuits due to structural weakness due to structural weakness. Is even higher.

The jelly-roll square cell is formed in a top cap after mounting an electrode assembly composed of a positive electrode, a negative electrode, and a separator inside an octagonal metal can, mounting an insulating member on an open top thereof, and then welding the top cap thereon again. The electrolyte is injected into the battery case through the electrolyte injection hole, and sealed by using a metal ball, and a safety device and a protection circuit are mounted thereon and then sealed with a housing (outer case).

In this structure, one electrode terminal (electrode tab) of the electrode assembly is welded to the bottom of the protruding terminal of the top cap, and the electrode tabs are bent while the top cap is mounted on the top of the can. The remaining electrode terminals (electrode tabs) of the electrode assembly are welded to the top cap itself and such top cap is welded to the metal cap. In general, the cathode of the electrode assembly is connected to the protruding terminal of the top cap, and the anode is connected to the top cap itself. The top cap of the positive electrode is kept insulated from the protruding terminal of the negative electrode.

However, the electrode tab of the negative electrode connected to the lower end of the protruding terminal is likely to be in contact with the metal can because its bent portion protrudes toward the side during the assembly of the battery, and the metal can itself acts as the positive electrode terminal. Contact causes a short circuit.

In order to solve this problem, Korean Patent Application Publication No. 2003-45961 proposes a structure in which a connection plate extending below the connection portion welded to the electrode tab of the electrode assembly coupled to the cap plate (top cap) is formed. have. However, since the connecting plate is formed in the connection portion coupled with the top cap, the above technique has a large void space between the top of the battery portion and the bottom of the top cap, so that the electrode assembly falls during the use of the battery. Or an external force may cause an internal short circuit, which may cause a serious problem in the safety of the battery.

In addition, Korean Patent Application Laid-Open No. 2004-58922 includes an insulating case and a battery, wherein the outer case extends downward from the bottom edge of the bottom surface and inserts an outer surface of the upper end of the battery part (electrode assembly) into a space formed therein. A possible bridge portion and a structure in which wall portions are formed at both edges of the upper main body are proposed. However, the insulating case is a rather large structure mounted on the upper end of the electrode assembly, and its bridge part is mounted in such a manner as to be inserted between the electrode assembly and the metal can, thereby reducing the size of the electrode assembly in a battery can of the same size. Is inevitable and has the disadvantage of causing a decrease in capacity of the battery.

In addition, since the insulating case surrounds the entire upper end of the electrode assembly together with the bridging part, there is no path through which the electrolyte can flow into the electrode assembly except for the opening located at the center of the insulating case when the electrolyte is introduced. This significantly reduces the manufacturing process of the battery is very long, and evenly impregnated electrolyte solution to the electrode assembly is not guaranteed.

Therefore, there is a high need for a technology that can prevent short circuit of the negative electrode tab by a simple process, further improve the safety of the battery, and further facilitate the addition of electrolyte.

The present invention aims to solve the problems of the prior art as described above and the technical problems that have been requested from the past.

Specifically, an object of the present invention is to mount on the top of the electrode assembly in a simple manner, does not cause a reduction in the capacity of the battery, the electrode terminal of the electrode assembly connected to the protruding terminal of the top cap is caused by contact with the metal can It is to provide a secondary battery including an insulating member that can effectively solve the problem of short circuit occurs.

Another object of the present invention, while ensuring the safety of the battery in the same manner as described above, including an insulating member that can be quickly injected and evenly impregnated electrolyte solution to the electrode assembly to reduce the manufacturing process time of the battery It is to provide a secondary battery.

In the secondary battery according to the present invention for achieving the above object, an electrode assembly including a cathode / separator / cathode structure is inserted into a metal can of a rectangular shape and an insulating member is mounted on the top of the electrode assembly to electrically insulate the top cap. A secondary battery that maintains a state, wherein the insulating member has a plate-shaped body having a shape corresponding to the inner surface of the metal can, a support portion protruding from both ends of the body, and an electrode tab of the electrode assembly connected to a corresponding portion of the top cap. The electrode tab is bent in the assembling process is configured to include a shielding film extending from the side of the main body in a direction protruding.

Therefore, the insulating member according to the present invention can be installed between the electrode assembly and the top cap by simply being mounted on the top of the electrode assembly, and insulates the electrodes of the electrode assembly from the top cap.

The plate-shaped main body of the insulating member has a shape corresponding to the inner surface of the metal can and thus surrounds the upper portion of the electrode assembly as a whole to mitigate external shock to the battery. On the other hand, the support parts protruding from both ends of the plate-shaped body of the insulating member stably supports between the top cap and the electrode assembly to further improve the safety of the battery.

The electrode terminal of the electrode assembly connected to the protruding terminal of the top cap is preferably a cathode terminal. In this structure, the cathode of the electrode assembly is connected to the bottom of the protruding terminal on the top cap or to the conductive connecting member attached to the bottom of the protruding terminal through its negative electrode tab, and the protruding terminal is connected to the top by an insulating plate on the top cap. Insulated from cap and metal can. Here, the top cap and the metal can are electrically connected to each other.

On the other hand, the anode of the electrode assembly is electrically connected to a top cap made of a conductive material such as aluminum, stainless steel or the like through its anode tab to form the anode terminal as the top cap and the metal can itself.

Therefore, when the negative electrode tab is severely bent during manufacturing or use of the battery, a part may be in contact with the metal can, which is a positive electrode, to cause a short circuit.

In order to prevent such a short circuit problem, in the secondary battery of the present invention, the shielding film extends from the plate-shaped main body of the insulating member in the direction in which the negative electrode tab is bent and protrudes. That is, the shielding film is located on the inner surface side of the metal can, whereby the bent protruding portion of the negative electrode tab is connected to the battery during the process of connecting the negative electrode tab from the electrode assembly to the corresponding portion of the top cap or the battery in such a connection state. Prevents contact with the cap to prevent short circuit.

Specifically, the shielding film has a structure extending from the side surface of the main body of the insulating member to a predetermined width and length. The length of the shielding film is not particularly limited as long as it can prevent the bending protrusion of the negative electrode tab from being connected to the metal can, and is equal to or slightly smaller than the separation distance L between the insulating member and the top cap. It can be size. However, when the length of the shielding film is larger than the separation distance L, it may not be easy to mount the insulating member on which the shielding film is formed at the correct position of the top surface of the battery unit. You can't. The width of the shielding film is also not particularly limited as long as it can prevent the bending protrusion of the negative electrode tab from being connected to the metal can. The width of the screen is not limited thereto. It may be the same size as, or slightly larger than, the width of the openings perforated.

The shielding film may be integrally manufactured with the insulating member by a method such as injection molding, or may be manufactured by separately manufacturing the shielding film and then bonding or thermally bonding the insulating film to the insulating member.

As described above, according to the present invention, the insulating member having the shielding film formed at a predetermined portion has a simple structure and is easy to manufacture, and the mounting to the electrode assembly can be easily performed, and the safety of the battery can be improved.

In one preferred example, the support preferably has a height in contact with or less than the bottom surface of the top cap. If the height of the support is greater than the height from the bottom surface of the top cap to the battery compartment, the top cap is not easily adhered to the top of the metal can and is not easy to seal. This is because an empty space is formed between the lower ends of the battery, which is not preferable for the safety of the battery.

Therefore, the support part formed on both ends of the insulating member and the shielding film formed on one side of the insulating member are stably mounted between the top cap and the electrode assembly to prevent short circuit, thereby improving battery safety.

In addition, in the present invention, a predetermined vertical through hole may be formed in the insulating member in order to more easily inject the electrolyte into the metal can. This facilitates the injection of the electrolyte solution has the economic advantages, such as reducing the manufacturing time of the battery.

In a specific example, the insulating member may have a structure in which upwardly protruding supports are formed at both end portions of the plate-shaped body corresponding to the horizontal inner surface structure of the metal can, and a vertical through hole is formed in the protruding support. .

The vertical through hole of the insulating member not only provides a flow path in which the electrolyte falls in the direction of the electrode assembly when the electrolyte is injected, but also serves as an additional accommodation space of the electrolyte. The area of the vertical through hole is preferably formed in a size of 20 to 70%, preferably 30 to 40% based on the horizontal cross-sectional area of the protruding support of the insulating member.

In some cases, as disclosed in Korean Patent Application No. 2005-112886 of the applicant, a vertical through hole may be formed in the center of the insulating member to facilitate the injection of the electrolyte solution. The contents of this application are incorporated herein by reference.

In the secondary battery according to the present invention, for example, the electrode assembly is inserted into the metal can, the insulating member is mounted on the electrode assembly, the top cap is coupled to the open top of the metal can, and then a predetermined amount of electrolyte is injected. And, after applying the current for battery activation, it can be prepared by replenishing the electrolyte again, sealing the electrolyte inlet.

The electrode assembly in which the battery reaction occurs in the secondary battery generally has a structure in which an electrolyte solution is impregnated into a cathode plate coated with a cathode active material, an anode plate coated with an anode active material, and a separator. The electrode assembly of the secondary battery is classified into a jelly-roll type (wound) electrode assembly and a stacked type (laminated) electrode assembly according to its structure. In one preferred example, the electrode assembly is a jelly-roll type electrode assembly.

Since other components constituting the secondary battery according to the present invention are known in the art, a detailed description thereof will be omitted herein.

Hereinafter, the content of the present invention will be described with reference to the drawings, but the scope of the present invention is not limited thereto.

1 is a plan view of a top cap of a secondary battery according to the prior art.

Referring to FIG. 1, the top cap 100 is made of a metal plate such as aluminum or stainless steel, and a connection member 110 for a protruding terminal is electrically insulated by a gasket 120 made of an insulating material at the center thereof. Formed from. Such a connection member 110 is welded to the cathode of the electrode assembly (not shown), the anode of the electrode assembly is welded to the top cap 100 itself.

The electrolyte injection hole 130 is perforated on one side of the top cap 100, and the electrolyte injection hole 130 is coupled to the top cap 100 while being coupled to an open upper end of a metal can (not shown) incorporating an electrode assembly. The electrolyte is injected through.

2 is a perspective view of an insulating member according to one embodiment used in the square battery of the present invention.

Referring to FIG. 2, the insulating member 300 includes a plate-shaped body 310 corresponding to a horizontal inner surface structure of a metal can (not shown), an upwardly projecting support 320, and a plate-shaped body 310 at both end portions thereof. It consists of a shielding film 350 extending vertically from the edge of one side of. The plate-shaped body 310 is formed with a pair of openings 330 into which the positive electrode tab and the negative electrode tab of the electrode assembly (not shown) may be inserted, respectively. The positive and negative tabs inserted through these openings 330 are connected by welding to corresponding portions of the top cap. The opening 330 also serves as a flow path when the electrolyte is injected.

Protruding support 320 is formed with a vertical through hole 340 of a predetermined size, such a vertical through hole 340 facilitates the injection of electrolyte into the metal can more easily and in the initial charging process for battery activation It also plays a role in suppressing electrolyte ejection.

3A schematically illustrates a vertical cross-sectional view of a secondary battery according to an exemplary embodiment of the present invention, and FIG. 3B illustrates a partially enlarged view thereof.

Referring to these drawings, the top cap assembly 160 includes a top cap 100 coupled to the top of the metal can, a gasket 120 mounted on the top cap 100, and a terminal mounted below the top cap 100. The plate 140, the insulating plate 150, and the connection member 110 for the protruding terminal are mounted to the top cap 100 in an insulated state by the gasket 120. In order to form the top cap assembly 160, the lower end of the protruding terminal connecting member 110 is passed through an opening formed in the insulating plate 150, and inserted through the opening formed in the terminal plate 140. Deformed by spinning, the insulation plate 150 and the terminal plate 104 are fixed by pressing close contact with the top cap 100.

An insulating member 300 is mounted on an upper end of the electrode assembly 410, and a shielding film 350 is formed on one side of the insulating member 300. The shielding film 350 may be a portion A and a metal can 400 that are bent after the cathode tab 414 of the electrode assembly 410 is drawn out through the opening 330 that is perforated in the insulating member 300. ), Thus preventing the negative electrode tab 414 from contacting the metal can 100, thereby preventing a short circuit.

Since the end of the negative electrode tab 414 is welded to the terminal plate 140, an electrical connection is made between the negative electrode tab 414, the terminal plate 140, and the connection member 110 for the protruding terminal. The insulating plate 150 prevents the terminal plate 140 from contacting the top cap 100.

4 schematically illustrates an assembly process of a square battery according to an embodiment of the present invention.

The electrode assembly 410 is inserted into the rectangular metal can 400 in such a manner that the positive electrode 412 and the negative electrode 414 protrude upward. The electrode assembly 410 is made by winding the positive electrode sheet and the negative electrode sheet in a state in which a separator is interposed therebetween, and then compressing the electrode assembly 410 into a rectangular shape.

The insulating member 300 is mounted on the upper end of the electrode assembly 410 with both protruding supports 320 facing upwards. In this mounting process, the anode 412 and the cathode 414 of the electrode assembly 410 are inserted into the opening 330 to protrude from the insulating member 300.

The top cap 100 is coupled to the top of the metal can 400 by welding while the insulating member 300 is mounted.

After the assembly process is completed, a predetermined amount of electrolyte is injected through the electrolyte injection hole 130, and after the initial charging, the electrolyte is replenished, and the electrolyte injection hole 130 is sealed to complete the rectangular battery.

As described above, the secondary battery according to the present invention includes an insulating member having a specific structure that is mounted in a manner that is simply mounted on the upper end of the electrode assembly, which is easy to manufacture, does not cause a decrease in capacity of the battery, and a top cap The problem of a short circuit in which the electrode terminal of the electrode assembly connected to the protruding terminal of the contact with the metal can can be effectively solved. In addition, while ensuring the safety of the battery as described above, it is possible to rapidly inject and evenly impregnate the electrolyte solution to the electrode assembly has the effect of reducing the battery manufacturing process time.

Those skilled in the art to which the present invention pertains will be able to perform various applications and modifications within the scope of the present invention based on the above contents.

Claims (9)

An electrode assembly including an anode / membrane / cathode structure is inserted into a metal can of a rectangular shape, and an insulating member is mounted on an upper end of the electrode assembly to maintain an electrical insulation state with respect to a top cap. The positive electrode tab of the electrode assembly is connected to the top cap and the negative electrode tab is connected to the protruding terminal electrically insulated on the top cap, The insulating member may include a plate-shaped body having a shape corresponding to the inner surface of the metal can, a support part protruding from both ends of the body, and an electrode tab of the electrode assembly connected to a corresponding portion of the top cap. A secondary battery comprising a shielding film extending from the side of the main body in the bent and protruding direction. delete delete The secondary battery of claim 1, wherein a length of the shielding film is equal to or smaller than a separation distance between the insulating member and the top cap. The secondary battery of claim 1, wherein the support portion has a height that is in contact with or lower than a bottom surface of the top cap. The secondary battery of claim 1, wherein a vertical through hole is formed in the support part. The secondary battery of claim 6, wherein an area of the through hole is formed in a range of 30 to 40% based on a horizontal cross-sectional area of the support. The method according to claim 1, wherein the electrode assembly is inserted into the metal can, the insulating member is mounted on the electrode assembly, the top cap is coupled to the open top of the metal can, and a predetermined amount of electrolyte is injected thereinto to activate the battery. The secondary battery is characterized by refilling the electrolyte after applying a current, and sealing the electrolyte injection port. The secondary battery of claim 1, wherein the electrode assembly is a jelly-roll type electrode assembly.

Images