KR100601545B1 - cylinder type secondary battery - Google Patents

Abstract

A cylindrical secondary comprising an electrode assembly formed by stacking and winding two electrodes and a separator, a cylindrical can containing the electrode assembly and the electrolyte, and a cap assembly positioned at the top of the can to close the can opening that is an inlet through which the electrode assembly is introduced. In a battery, an electrode tab, which is part of an electrical passage connecting an electrode and an external circuit, is formed to be drawn out from both electrodes toward the can opening, and the conductor structure of the cap assembly is spaced and insulated by the opening of the can and an insulating gasket. Disclosed is a cylindrical secondary battery, wherein one of the electrode tabs is sandwiched between a sidewall of the can and an insulating gasket to be in electrical connection with the can.

Description

Cylindrical secondary battery {cylinder type secondary battery}

1 is a front sectional view showing a structure of an example of a conventional cylindrical secondary battery, Figure 2 is a perspective view showing a conventional conventional electrode assembly,

3 and 4 are a perspective view showing a schematic drawing form of the two electrode tabs in the electrode assembly according to an embodiment of the present invention and a front sectional view showing a connection form between the tabs and the two electrodes in the state of the cylindrical secondary battery to be.

5 and 6 are a perspective view showing a schematic drawing form of two electrode tabs in an electrode assembly formed according to another embodiment of the present invention and a connection form between the tabs and the two electrodes of the battery in the state of forming a cylindrical secondary battery Front section view.

* Explanation of symbols for the main parts of the drawings

10: can 13a, 13b: insulation plate

20: electrode assembly 27,29,27 ', 29': tab

30; Gasket 80: Cap Assembly

The present invention relates to a cylindrical secondary battery, and more particularly to a cylindrical secondary battery characterized by the electrode assembly tab forming structure of the cylindrical secondary battery.

Secondary batteries have been rapidly developed and used in recent years due to the advantages of being rechargeable and capable of miniaturization and large capacity. Secondary batteries may be divided into nickel-hydrogen (Ni-MH) batteries, lithium-ion (Li-ion) batteries, and the like according to electrode active materials.

Lithium secondary batteries may be divided into a case of using a liquid electrolyte and a case of using a solid polymer electrolyte or a gel electrolyte, depending on the type of electrolyte. Lithium secondary batteries can also be divided into cans and pouches according to the type of container in which the electrode assembly is accommodated.

In a can-type lithium secondary battery, an electrode assembly is embedded in a can formed of a metal such as an aluminum-containing metal through a deep drawing method. In general, a liquid electrolyte is used in a can type secondary battery structure.

On the other hand, the can-type secondary battery can be divided into a rectangular and a cylindrical battery according to the shape. The rectangular shape can be made thin by forming a container into a rectangular parallelepiped shape, thereby giving flexibility in mounting electronic and electronic devices such as a mobile phone using the same. Cylindrical is used in a relatively large amount of electronic and electrical equipment, a plurality is used in the form of a combination to form a battery pack.

1 is a front sectional view showing a structure of an example of a conventional cylindrical secondary battery, Figure 2 is a perspective view showing the form of electrode tab in the conventional electrode assembly.

Referring to FIGS. 1 and 2, a method of forming a cylindrical secondary battery will first be described. First, two electrodes 25 formed in a rectangular plate shape and separators 21 and 23 interposed between these electrodes to prevent a short circuit between the two electrodes. Are stacked, wound in a spiral to form an electrode assembly 20 collectively referred to as a jellyroll. Each electrode plate is made by coating an active material slurry on a current collector made of a metal foil.

In the direction in which the electrode plate is wound, there is a non-coated portion at which the slurry is not applied at the start end and the end of the current collector. In the uncoated portion, electrode tabs 27 and 29 are usually provided on one electrode plate one by one. The electrode tab is electrically connected to the cylindrical can 10 and the cap assembly 80 insulated from the can to form part of the passageway for connecting the electrode assembly and the external circuit during charging and discharging.

The electrode assembly is introduced into the cylindrical can through the can openings, which in turn are positioned up and down. Beads are formed in the can to prevent flow in the can of the electrode assembly, and the electrolyte is injected. An insulating gasket 30 is installed inside the opening of the can, and a cap assembly that closes the opening of the can is installed. As the cap assembly, a vent 40 welded to the tab, a current interrupt device (CID) 50, a positive thermal coefficient (PTC) 60, and a cap up 70 with an electrode terminal are inserted.

A crimping operation is performed to seal the can by applying pressure to the opening of the cylindrical can inward with a cap and the like injected into the gasket 30. A tubing operation is performed to coat the exterior of the battery.

By the way, in the conventional electrode assembly, the electrode tab is formed to be drawn out of the electrode, one upward in the direction of the opening of the cylindrical can, the other downward. The electrode tab 27 drawn upward is welded with the vent 40 and eventually electrically connected to the cap up 70 in which the electrode terminal is formed. The cap up 70 and the like are insulated from the cylindrical can 10 and the gasket 30, and the top surface of the electrode assembly is insulated from the insulating plate 13a.

Meanwhile, the electrode tab 29 drawn out downward is bent to be parallel to the bottom surface of the jellyroll-type electrode assembly and welded to the bottom surface of the cylindrical can. In this case, an insulating plate 13b is positioned between the electrode tab portion bent so as not to short-circuit with another electrode on the lower surface of the electrode assembly.

In order to weld the electrode tab to the bottom surface of the cylindrical can, a welding rod is inserted through the empty space in the center of the jelly roll-type electrode assembly and in the center of the lower insulating plate. Then, the electrode tab 29 and the bottom surface of the cylindrical can 10 are brought into close contact with the electrode, and a current is passed through the electrode to perform welding by the resistance welding method.

In this case, since the cylindrical can is filled by the electrode assembly, the welding state between the electrode tab and the cylindrical can bottom is difficult to be immediately determined.

For example, at the moment of welding, although the lower insulating plate 13b is interposed near the welding point, the electrode assembly is located. Accordingly, during the welding, welding splash may be attached to the bottom surface of the electrode assembly. And, depending on the attachment position, the welding dregs may bring a problem of shorting the two electrodes.

However, as mentioned above, the cylindrical can is then filled by the electrode assembly. Therefore, such a welding problem cannot be directly identified, and the battery production process proceeds as it is to identify the cause of the battery failure at a later stage, for example, the chemical conversion step.

On the other hand, when the empty space in the center of the cylindrical electrode assembly is reduced in accordance with the effort to reduce the empty space inside the battery for high capacity of the secondary battery may also be difficult to insert the welding rod.

The present invention is to solve the above problems of the conventional cylindrical secondary battery, a cylindrical secondary battery having an electrode tab forming structure that can eliminate the problems caused by welding the electrode tab and the bottom of the can of the jelly roll-type electrode assembly of the cylindrical secondary battery It is an object to provide a battery.

The present invention can easily confirm the welding state between the electrode tab and the cylindrical can in the cylindrical secondary battery, and the cylindrical secondary structure of the structure that can increase the possibility of introducing a welding method different from the conventional resistance welding between the electrode tab and the cylindrical can. It is an object to provide a battery.

An object of the present invention is to provide a cylindrical secondary battery that can reduce the process cost by eliminating the welding process between the electrode tab and the cylindrical can in the cylindrical secondary battery.

Cylindrical secondary battery of the present invention for achieving the above object,

A cylindrical assembly comprising an electrode assembly formed by stacking and winding two electrodes and a separator, a cylindrical can containing the electrode assembly and the electrolyte, and a cap assembly positioned at the top of the can to close the can opening that is an inlet through which the electrode assembly is introduced. In a secondary battery,

An electrode tab, which is part of an electrical passage connecting the electrode and an external circuit, is formed to be drawn out from the both electrodes toward the can opening portion,

The conductor structure of the cap assembly is insulated from the opening of the can by an insulating gasket,

One of the electrode tabs is sandwiched between the sidewall of the can and the insulating gasket to be electrically connected to the can.

In the present invention, the two electrode tabs may be formed in the center axis portion and the outer periphery of the jelly roll-type electrode assembly, respectively one by one or symmetrically with the outer periphery.

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

3 and 4 are front cross-sectional views showing a schematic drawing form of two electrode tabs in an electrode assembly and a connection form between the tabs and two electrodes in a state of forming a cylindrical secondary battery according to an embodiment of the present invention. .

Referring to FIGS. 3 and 4, two electrodes 25 formed in a rectangular plate shape are stacked and wound in a spiral shape to form a jelly roll type electrode assembly as in the related art. At this time, since the separators 21 and 23 are positioned one by one between these electrodes and below or above the two electrodes, the separators are interposed where the two electrodes to be wound are interposed to prevent a short circuit.

Each electrode plate is made of an active material slurry coated on a current collector made of aluminum or copper metal foil or metal mesh. The slurry is usually formed by stirring a granular active material, auxiliary conductor, binder, and the like in a state where a solvent is added. The solvent is removed in the subsequent electrode formation process.

In the direction in which the electrode plate is wound, there is a non-coated portion at which the slurry is not applied at the start end and the end of the current collector. The electrode tabs 27 ', 29, are provided at end ends of the two electrode plates one by one. However, the length of the uncoated portion forming of the two electrode plates is longer in the outer negative electrode so that the electrode tab of the negative electrode plate is welded to the position half a turn further away from the jelly roll type electrode assembly. Thus, in the completed electrode assembly, the negative electrode tab is installed to face the positive electrode tab with respect to the central axis.

The lower insulating plate 13b is provided in the can 10, and the electrode assembly 20 and the upper insulating plate 13a are installed in this order. The lower insulating plate 13 is installed in a disc shape without a central hole, and the upper insulating plate 13a is installed in a disc shape in which at least one hole is formed, including a hole for an anode on the outside.

In this embodiment, the positive electrode tab 27 ′ is drawn out through the through hole of the phase insulating plate, and the negative electrode tab 29 ′ is drawn out in contact with the inner wall of the can 10 to the outside of the phase insulating plate. The negative electrode tab may be drawn out through the through hole when a separate through hole of the phase insulating plate is formed. Of course, according to the embodiment, the cathode and the anode may be formed by changing the polarity.

The subsequent process can be made similar to the conventional method of forming a cylindrical secondary battery. That is, beads for preventing flow in the can of the electrode assembly are formed in the can, and the electrolyte is injected. It is also preferable to form a support inside the can in which the negative electrode tab is in close contact to prevent the negative electrode tab from bending in the direction of the center axis of the can by the bead when the bead is formed.

An insulating gasket 30 is installed inside the can opening and has a vent assembly welded to the tab 27 'with a cap assembly 80 closing the opening of the can, a PTC (Positive Thermal Coefficient) 60, and an electrode terminal. The cap up 70 is inserted. At this time, the positive electrode tab 27 ′ is welded to the vent 40 when the vent assembly is inserted, and is bent in parallel with the upper insulation plate 13 a, and the negative electrode tab 29 ′ is positioned outside the gasket 30. That is, the negative electrode tab is tightly sandwiched between the side wall forming the opening of the can and the insulating gasket. However, the formation length of the negative electrode tab should be adjusted so that the negative electrode tab does not protrude beyond the cap up.

A crimping operation is performed to seal the can by applying an internal pressure to the opening of the cylindrical can with a cap and the like injected into the gasket. A tubing operation is performed to coat the exterior of the battery. When the crimping operation is performed, the negative electrode tab is more tightly fitted between the sidewall of the can and the gasket. The flexibility of the gasket allows the seal to be maintained even when the negative electrode tab is between the gasket and the can sidewall of the opening.

According to this embodiment, the negative electrode tab is in contact with the side wall in a large area and in contact with the can with pressure through the clamping process, although welding is not made but there is no problem in the electrical connection.

In addition, since there is no welding between the negative electrode tab and the can wall, there is no risk of splashing when the negative electrode tab welding is performed and falling short between two electrodes of the electrode assembly as in the prior art.

5 and 6 are cross-sectional front views showing a schematic drawing form of two electrode tabs in an electrode assembly and a connection form between the tabs and two electrodes in a state of forming a cylindrical secondary battery in accordance with another embodiment of the present invention. .

5 and 6, the overall cell formation method is similar to the embodiment shown in Figs. That is, the jelly roll electrode assembly 20 is formed by stacking two electrodes 25 formed in a rectangular plate shape with the separators 21 and 23 interposed therebetween.

In one of the two electrode plates, the electrode tabs 27 and 29 'are provided at the end end uncoated portion and at the other end. The electrode tab is bonded to the metal foil forming the current collector of the electrode plate by ultrasonic welding or the like. Thus, in the completed electrode assembly, for example, the negative electrode tab 29 'is drawn out from the periphery of the electrode assembly, and the positive electrode tab 27 is directed toward the opening of the can at the central axis portion.

The lower insulating plate 13a, the electrode assembly 20, and the upper insulating plate 13b are sequentially installed in the can. At this time, the phase insulation plate is installed in the shape of a disc including at least one through-hole including a through hole for the anode in the center. The positive electrode tab is drawn out through the through hole of the phase insulating plate.

The negative electrode tab 29 'is drawn out of the phase insulating plate in contact with the inner wall of the can. Beads are formed in the can 10 to prevent flow in the can of the electrode assembly. At this time, it is also preferable to form a support inside the can in which the negative electrode tab is in close contact in order to prevent the negative electrode tab 29 'from being bent in the direction of the center axis of the can by the beads.

The electrolyte is injected through the opening of the can. An insulating gasket 30 is installed inside the opening of the can, and a cap assembly having a vent assembly welded to the tab, a positive thermal coefficient (PTC), and an electrode terminal is inserted into the cap assembly closing the opening of the can. The positive electrode tab is welded to the vent assembly when the vent assembly is inserted. In the gasket installation, of course, the negative electrode tab is located outside the gasket as in the above-mentioned embodiment, the forming length of which is adjusted so that the negative electrode tab does not protrude beyond the cap up.

The can is sealed through a crimping operation that pressurizes and deforms the sidewall constituting the can opening beyond the bead portion inward. An exterior material is formed on the outer wall of the can. When the crimping operation is made, the negative electrode tab is firmly held at a more constant pressure between the sidewall of the can and the gasket and can establish a stable electrical connection with the can. Since the sealing of the can is maintained by the elasticity or flexibility of the gasket, it is preferable to use a soft material having better elasticity and ductility than a conventional gasket. If the thickness of the tab in close contact with the can wall is too thick, sealing by the gasket becomes so difficult. Therefore, it is desirable to form the gasket thicker than the conventional gasket thickness for battery sealing.

On the other hand, even if the area of the tab in close contact with the can is large, it is preferable to apply plating or silver paste coating on the upper portion of the tab to reduce contact resistance. In addition, it is desirable that the tab be wider and thinner than the conventional one.

According to the present invention, in the cylindrical secondary battery, all the electrode tabs are formed toward the opening of the can, and there is no welding between the electrode tab and the cylindrical can, so that a phenomenon such as a short circuit between the two electrodes of the electrode assembly due to the splash from welding can be prevented.                     

In addition, since there is no need to insert a resistance electrode for welding the electrode tab and the bottom of the can in the center of the electrode assembly, the size of the empty space in the center can be reduced.

And the electrical connection between the can walls and one electrode tab is made together during the different process of cell formation, such as beading, gasketing and crimping, so that one welding step can be reduced, while the electrical connection has a large surface and sealing. There is an advantage that can be maintained stably through the pressure during the crimping operation, flexibility of the gasket.

Claims (8)

An electrode assembly formed by stacking and winding two electrodes and a separator, A cylindrical can containing the electrode assembly and the electrolyte solution, In the cylindrical secondary battery comprising a cap assembly positioned on the top of the can closing the can opening which is an inlet for the electrode assembly is inserted, An electrode tab provided on the electrode is drawn out from the both electrodes toward the can opening portion, The conductor structure of the cap assembly is insulated from the opening of the can by an insulating gasket, One of the electrode tabs is compressed between the sidewall of the can and the insulating gasket to be electrically connected to the can. The method of claim 1, The electrode tabs of the two electrodes, the cylindrical secondary battery, characterized in that each one is formed in the central axis portion and the outer peripheral portion of the electrode assembly. The method of claim 2, A disc insulator is interposed between the cap assembly and the electrode assembly. The disc-shaped insulator is a cylindrical secondary battery, characterized in that the central through hole is formed by the electrode tab formed in the central axis portion. The method of claim 1, Electrode tabs of the two electrodes are formed on the outer periphery of the electrode assembly, Cylindrical secondary battery, characterized in that formed on both sides with respect to the central axis. The method of claim 4, wherein A disc insulator is interposed between the cap assembly and the electrode assembly. And the at least one through hole is formed in the disc-shaped insulator, including a through hole penetrated by one of the electrode tabs. The method of claim 1, The cap assembly is a cylindrical secondary battery, characterized in that the vent assembly, PCM (Positive Thermal Coefficient), the cap up is provided in sequence. The method of claim 1, A disc insulator is interposed between the cap assembly and the electrode assembly. And the at least one through hole is formed in the disc-shaped insulator, including a through hole penetrated by one of the electrode tabs. The method of claim 1, The electrode tab electrically connected to the can wall has a gold plated portion or a silver paste coated on a portion in close contact with the can.

Images