KR100719734B1 - Lithium rechargeable battery and method of making the same - Google Patents

Abstract

The present invention relates to a lithium secondary battery and a method for manufacturing the same. More specifically, instead of a method of press-fitting and welding a ball to seal the electrolyte inlet, the metal plate is surrounded by the electrolyte inlet and the metal plate is surrounded by the laser welding. The present invention relates to a lithium secondary battery and a method for manufacturing the same, which are melted and adhered to an electrolyte injection hole by using a roller, thereby eliminating the need for a separate ball indentation process.

Lithium Secondary Battery, Electrolyte Injection, Laser Welding, Sealability

Description

Lithium secondary battery and method of manufacturing the same {Lithium rechargeable battery and Method of making the same}

1A is an exploded perspective view of a typical lithium secondary battery

FIG. 1B is a vertical sectional view of the cap plate of FIG. 1A

Figure 2a is an exploded perspective view of a lithium secondary battery according to an embodiment of the present invention

FIG. 2B is a vertical sectional view of the cap plate of FIG. 2A

Figure 3a is a cross-sectional view of the electrolyte inlet sealing process according to an embodiment of the present invention

3B is a plan view of a cap plate made of laser welding according to an embodiment of the present invention;

 <Description of Symbols for Main Parts of Drawings>

200-Lithium Secondary Battery 210-Can

220-electrode assembly 230-cap assembly

240-Cap plate 242-Electrolyte inlet

244-metal

The present invention relates to a lithium secondary battery and a method for manufacturing the same. More specifically, instead of a method of press-fitting and welding a ball to seal the electrolyte inlet, the metal plate is surrounded by the electrolyte inlet and the metal plate is surrounded by the laser welding. The present invention relates to a lithium secondary battery and a method for manufacturing the same, which are melted and adhered to an electrolyte injection hole by using a roller, thereby eliminating the need for a separate ball indentation process.

In general, as the light weight and high functionality of portable wireless devices such as a video camera, a portable telephone, a portable computer, and the like progress, a lot of researches have been conducted on secondary batteries used as driving power. Such secondary batteries include, for example, nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, and lithium secondary batteries. Among them, lithium secondary batteries are rechargeable, compact, and large-capacity, and are widely used in advanced electronic devices because of their high operating voltage and high energy density per unit weight.

1A is an exploded perspective view of a typical lithium secondary battery, and FIG. 1B is a vertical cross-sectional view of the cap plate of FIG. 1A.

Referring to FIG. 1A, the lithium secondary battery 100 receives an electrode assembly 120 including an anode plate 123, an anode plate 125, and a separator 124 together with an electrolyte in a can 110. The upper end opening 110a of the can 110 is formed by sealing the cap assembly 130.

The can 110 is generally formed of aluminum or an alloy thereof, and manufactured by a deep drawing method. The lower surface 110b of the can 110 is generally formed in a substantially planar shape.

The electrode assembly 120 is formed by winding a separator 124 between the positive electrode plate 123 and the negative electrode plate 125. The positive electrode tab 126 is coupled to the positive electrode plate 123 to protrude to the upper end of the electrode assembly 120, and the negative electrode tab 127 is coupled to the negative electrode plate 125 to protrude to the upper end of the electrode assembly 120. In the electrode assembly 120, the positive electrode tab 126 and the negative electrode tab 127 are formed to be electrically separated from each other by a predetermined distance. The positive electrode tab 126 and the negative electrode tab 127 are generally formed of nickel metal.

The cap assembly 130 includes a cap plate 140, an insulating plate 150, a terminal plate 160, and an electrode terminal 135. Cap assembly 130 is coupled to a separate insulating case 170 is coupled to the top opening portion 110a of the can 110 to seal the can 110.

Referring to FIG. 1B, the cap plate 140 is formed of a metal plate having a size and shape corresponding to that of the upper opening 110a of the can 110. The terminal plate hole 1 141 of a predetermined size is formed in the center of the cap plate 140, and when inserted into the terminal hole hole 1 (141), the electrode terminal (135) for insulation of the electrode terminal 135 and the cap plate 140 The tubular gasket tube 146 is coupled to the outer surface of the 135 and inserted together. On the other hand, one side of the cap plate 140 is the electrolyte injection hole 142 is formed to a predetermined size. In addition, the other side of the cap plate 140, the safety vent 143 is formed in a predetermined size. The safety vent 143 is thinner than other parts so as to be damaged by the gas generated inside the battery to prevent explosion of the battery. After the cap assembly 130 is assembled to the upper opening 110a of the can 110, the electrolyte is injected through the electrolyte inlet 142, and the electrolyte inlet 142 is a separate sealing means to the ball 144. Sealed.

The electrode terminal 135 is connected to the negative electrode tab 127 of the negative electrode plate 125 or the positive electrode tab 126 of the positive electrode plate 123 to act as a negative electrode terminal or a positive electrode terminal.

The insulating plate 150 is formed of an insulating material such as a gasket and is coupled to the bottom surface of the cap plate 140. The insulating plate 150 has a terminal through-hole 2 151 into which the electrode terminal 135 is inserted at a position corresponding to the terminal through-hole 1 141 of the cap plate 140. A mounting groove 152 corresponding to the size of the terminal plate 160 is formed on the bottom surface of the insulating plate 150 so that the terminal plate 160 is seated.

The terminal plate 160 is generally formed of a nickel alloy, and is mounted on the bottom surface of the insulating plate 150. The terminal plate 160 is provided with a terminal through hole 3 161 into which the electrode terminal 135 is inserted at a position corresponding to the terminal through hole 1 141 of the cap plate 140, and the electrode terminal 135. Is insulated by the gasket tube 146 and coupled through the terminal through hole 1 141 of the cap plate 140, so that the terminal plate 160 is electrically insulated from the cap plate 140 and the electrode terminal 135. Is electrically connected).

The negative electrode tab 127 coupled to the negative electrode plate 125 is welded to one side of the terminal plate 160, and the positive electrode tab 126 coupled to the positive electrode plate 123 is welded to the other side of the cap plate 140. . Resistance welding, laser welding, or the like is used as a welding method for coupling the negative electrode tab 127 and the positive electrode tab 126, and resistance welding is generally used.

The insulating case 170 is responsible for the insulation between the cap assembly 130 and the electrode assembly 120, the positive electrode tab hole 172 and the negative electrode tab hole 174 are formed.

In general, the electrolyte inlet is closed by injecting the electrolyte and then injecting the ball at a predetermined pressure, and laser welding the area around the ball and the electrolyte inlet. In this case, the electrolyte inlet is buried in the inlet and the side when the electrolyte is injected. Therefore, in the electrolyte injection hole, the dried electrolyte layer is formed between the side of the electrolyte injection hole and the ball after the ball is press-fitted. Such an electrolyte layer has a problem in that the adhesion between the ball and the electrolyte inlet side is reduced. In addition, since the process of press-fitting the ball and the process of welding are performed separately, there is a problem that the process becomes complicated.

The present invention has been made to solve the above problems, in particular, instead of the method of pressing and welding the ball in order to seal the electrolyte inlet while covering the metal plate around the electrolyte inlet while melting the metal plate around the electrolyte inlet by laser welding and roller By using in close contact with the electrolyte inlet, there is no need for a separate ball indentation process is to provide an improved lithium secondary battery and its manufacturing method.

In order to solve the above problems, the lithium secondary battery of the present invention includes an electrode assembly, a can accommodating the electrode assembly, a cap plate having an electrolyte inlet formed on one side, and sealing an upper opening of the can. In a lithium secondary battery comprising a cap assembly, the electrolyte inlet is sealed with a metal plate, the sealing is characterized in that the surface welding is performed by laser welding.

In this case, the metal plate may be formed of a material including aluminum. In addition, the metal plate is preferably formed to a thickness of 2.5% to 25% of the cap plate thickness. In addition, the metal plate is preferably formed to a thickness of 20 to 200㎛.

In addition, the surface welding may be made by scanning the welding site by firing a laser in a zigzag shape can be a surface welding.

In addition, the method of manufacturing a lithium secondary battery of the present invention comprises the steps of preparing a bare cell, a metal plate, a laser welder including a cap plate formed with an electrolyte inlet; A welding step of placing a metal plate in an area to be sealed including the electrolyte injection hole and welding the surface between the area to be sealed and the metal plate by a laser welder; And it is characterized in that it comprises a pressing step of pressing by pressing the welded portion through the welding step.

At this time, the welding step may be made as a scan in a zigzag shape to the area to be sealed. In addition, the pressing step is preferably made in a manner to rotate while pressing the roller.

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

First, a lithium secondary battery according to an embodiment of the present invention will be described.

2A is an exploded perspective view of a lithium secondary battery according to an exemplary embodiment of the present invention, and FIG. 2B is a vertical cross-sectional view of the cap plate of FIG. 2A.

In the lithium secondary battery 200 according to an embodiment of the present invention, referring to FIG. 2A, an electrode assembly 220 including the positive electrode plate 223, the negative electrode plate 225, and the separator 224 may be filled with an electrolyte ( And the upper end opening 210a of the can 210 is sealed with the cap assembly 230. The lithium secondary battery 200 includes a long side and a front surface and a rear surface formed to face each other, a short side, and both sides formed to face each other, a top surface on which the cap plate 240 is located and a bottom surface facing the top surface. And 210b.

The electrode assembly 220 is formed by winding a separator 224 between the positive electrode plate 223 and the negative electrode plate 225.

The positive electrode plate 223 includes a positive electrode current collector made of a thin metal plate having excellent conductivity, for example, aluminum (Al) foil, and a positive electrode active material layer coated on both surfaces thereof. Lithium oxides, such as LiCoO2, LiMn2O4, LiNiO2, LiMnO2, are used as the said positive electrode active material. At both ends of the positive electrode plate 223, a positive electrode current collector region in which a positive electrode active material layer is not formed, that is, a positive electrode non-coating portion is formed. One end of the positive electrode non-coating portion is generally formed of aluminum (Al), and the positive electrode tab 226 protruding a predetermined length to the upper portion of the electrode assembly 220 is bonded.

The negative electrode plate 225 includes a negative electrode current collector made of a conductive metal plate, for example, copper (Cu) or nickel (Ni) foil, and a negative electrode active material layer coated on both surfaces thereof. Both ends of the negative electrode plate 225 have a negative electrode current collector region, that is, a negative electrode non-coating portion, in which a negative electrode active material layer is not formed. One end of the negative electrode non-coating portion is generally formed of nickel (Ni) material, and a negative electrode tab 227 protruding a predetermined length to the lower portion of the electrode assembly 220 is bonded. In addition, a lower portion of the electrode assembly 220 may further include an insulating plate for preventing contact with the can 210.

The separator 224 may be interposed between the positive electrode plate 223 and the negative electrode plate 225 and extend to surround the outer circumferential surface of the electrode assembly 220. The separator 224 is formed of a porous membrane polymer material to prevent short circuit between the positive electrode plate 223 and the negative electrode plate 225 and to allow lithium ions to pass therethrough.

The can 210 is formed in a substantially box shape including a pair of long side walls 212 having a substantially rectangular shape, a pair of short side walls 213 and a bottom plate 210b, and an upper portion thereof is opened to open an upper end thereof. (210a). In addition, when the can 210 is formed in a substantially box shape, the cross section in the horizontal direction may be formed in various shapes such as a rectangular shape or an elliptical shape. The electrode assembly 220 is inserted into the upper opening 210a. In addition, an electrolyte solution is impregnated between the electrode assemblies 220 to enable the movement of lithium ions. The material of the can 210 is mainly light aluminum (Al). The upper portion of the can 210 is sealed by the cap assembly 230, the leakage of the electrolyte is prevented. The long side wall 212 and the short side wall 213 of the can 210 have a thickness of about 0.2 to 0.4 mm, and the thickness of the bottom plate 210b is about 0.2 to 0.7 mm. However, the thickness of the long side wall 212, the short side wall 213, and the bottom plate 210b is not limited thereto. The can 210 is preferably formed by a deep drawing method, and the long side wall 212, the short side wall 213, and the bottom plate 210b are integrally formed. However, the method of forming the can 210 is not limited thereto.

The cap assembly 230 includes a cap plate 240, an insulating plate 250, a terminal plate 260, and an electrode terminal 235. The cap assembly 230 is coupled to a separate insulating case 270 is coupled to the upper opening 210a of the can 210 to seal the can 210.

2B, the cap plate 240 is welded to the upper end opening 210a of the can 210 to seal the can 210. The cap plate 240 has an electrolyte injection hole 242 formed at one side thereof, and a terminal through hole 1 241 is formed at an approximately center of the cap plate 240, and a gas cat is formed at the terminal through hole 1 241. The electrode terminal 235 insulated by the tube 246 is inserted.

The electrolyte injection hole 242 is formed on one side of the cap plate 240 and is sealed by a separate metal plate 244. In this case, the sealing may be made by a welding method such as laser welding, or may be made by using an adhesive material such as an adhesive. Preferably, the sealing method is made by laser welding. Laser welding may be simultaneously performed on the peripheral portion of the electrolyte injection hole 242 corresponding to the area to be welded, for example, the area of the metal plate 244 including the electrolyte injection hole 242 and one side of the metal plate 244. have. The laser welding is preferably performed simultaneously on the peripheral portion of the electrolyte injection hole 242 and one side of the metal plate 244. That is, the laser welding is made to contact the one side of the metal plate 244 to the peripheral portion of the electrolyte inlet 242, the contact portion is made. In this case, one side surface of the metal plate 244 and the peripheral portion of the electrolyte injection hole 242 are melted by the laser is attached to each other. At the same time as the laser welding, it is preferable to press the welded portion sufficiently with a pressing tool such as a jig or a roller. At this time, the laser welding is preferably concentrated in the peripheral portion of the electrolyte injection hole 242 relative to one side of the metal plate 244. Since the metal plate 244 uses a thin thickness, the metal plate 244 may be deformed when the laser welding is excessive. On the other hand, the metal plate 244 is preferably made of a material containing aluminum. Since the cap plate 240 is generally made of aluminum, the metal plate 244 may be made of the same or similar material. In addition, the metal plate 244 may be formed in any one of a rectangular shape, an elliptical shape, and a circular shape, but the metal plate 244 is not limited to the planar shape of the metal plate 244. In addition, the metal plate 244 is preferably formed to a thickness of 2.5% to 25% of the thickness of the cap plate 240. In addition, the metal plate 244 is preferably formed to a thickness of 20 to 200㎛. When the thickness of the metal plate 244 is less than 2.5% of the thickness of the cap plate 240, since the thickness becomes too thin, the metal plate 244 may be deformed even after a minute impact after the laser welding, and the electrolyte may leak. On the other hand, if the thickness of the metal plate 244 is formed to exceed 25% of the thickness of the cap plate 240, there is a problem that the adhesion by the laser welding is reduced and the appearance of the bare cell is not neat. On the other hand, after the laser welding is finished, a photocurable material may be applied around the metal plate 244 to more thoroughly prevent leakage of the electrolyte. The sealing method does not require a separate ball press process compared to the conventional sealing method, and since the side of the electrolyte inlet is not used for sealing, welding may be performed after removing the electrolyte around the inlet after the electrolyte is injected. Sealability can be further improved.

The insulating plate 250 is formed of an insulating material such as a gasket, and is coupled to the bottom surface of the cap plate 240. The insulating plate 250 is formed with a terminal through-hole 2 251 into which the electrode terminal 235 is inserted at a position corresponding to the terminal through-hole 1 241 of the cap plate 240. A mounting groove 252 corresponding to the size of the terminal plate 260 is formed on the bottom surface of the insulating plate 250 so that the terminal plate 260 is seated.

The terminal plate 260 is generally formed of Ni alloy, and is mounted on the bottom surface of the insulating plate 250. The terminal plate 260 is provided with a terminal through hole 3261 into which the electrode terminal 235 is inserted at a position corresponding to the terminal through hole 1 241 of the cap plate 240, and the electrode terminal 235. Is insulated by the gasket tube 246 and coupled through the terminal through hole 1 241 of the cap plate 240, so that the terminal plate 260 is electrically insulated from the cap plate 240 while the electrode terminal 235 is insulated from the cap plate 240. Is electrically connected).

The negative electrode tab 227 coupled to the negative electrode plate 225 is welded to one side of the terminal plate 260, and the positive electrode tab 226 coupled to the positive electrode plate 223 is welded to the other side of the cap plate 240. . Resistance welding, laser welding, or the like is used as a welding method for bonding the negative electrode tab 227 and the positive electrode tab 226, and resistance welding is generally used.

The electrode terminal 235 is connected to the negative electrode tab 227 of the negative electrode plate 225 or the positive electrode tab 226 of the positive electrode plate 223 to act as a negative electrode terminal or a positive electrode terminal.

Next, a method of manufacturing a lithium secondary battery according to an embodiment of the present invention will be described.

Figure 3a shows a cross-sectional view of the electrolyte inlet sealing process according to an embodiment of the present invention, Figure 3b is a plan view of a cap plate made of laser welding according to an embodiment of the present invention. 3A and 3B, only the cap plate part is illustrated for the sake of convenience and omitting other parts of the bare cell.

In the method of manufacturing a lithium secondary battery according to an exemplary embodiment of the present invention, referring to FIG. 2A, forming the electrode assembly 220 and opening the electrode assembly 220 to the upper opening 210a of the can 210.

Inserting through the cap assembly 230, sealing the upper opening 210a of the can 210 with the cap assembly 230, injecting electrolyte through the electrolyte injection hole 242, sealing the electrolyte injection hole 242. It is made, including. Hereinafter, the step of sealing the electrolyte injection hole 242 will be described.

Sealing the electrolyte injection hole 242, referring to Figures 3a and 3b, comprises a preparation step, a welding step and a pressing step.

The preparation step is a process of preparing a bare cell, a metal plate 244 and a laser welder (not shown) including a cap plate 240 having an electrolyte injection hole 242 formed therein. The bare cell is a state in which the electrolyte is injected. The metal plate 244 is used by cutting to a size suitable for the region to be welded. In addition, in the preparation step, the electrolyte from the inlet of the electrolyte inlet 242 is removed for welding.

The welding step is a process of placing a metal plate 244 in an area to be sealed including the electrolyte injection hole 242 and welding the laser plate between the area to be sealed and the metal plate 244. The welding step is performed by contacting one side of the metal plate 244 with a region to be sealed, and then firing a laser on the contact portion. At this time, the welding step, referring to Figure 3b, it is preferably made in a zigzag shape to the area to be sealed in a surface welding method. Curved arrows in Fig. 3b mean welding paths. When the welding step is made by spot welding, there is a fear that the electrolyte is leaked due to the drop in sealing degree.

The pressing step is a process of pressing and pressing the welded part through the welding step. At this time, the pressing step is made using a pressing tool such as a jig or a roller, preferably made in a manner of rotating while pressing the roller (R) as shown in Figure 3a. In FIG. 3A, the arrow between the metal plate 244 and the top surface of the cap plate 240 means laser welding. The pressing step may be performed after the welding step is completed, it may be made at the same time as the welding step, of course.

According to the electrolyte injection opening sealing method, since the metal plate 244 serving as the sealing means does not come into contact with the side surface of the electrolyte injection opening 242, there is no fear that the sealing degree may be degraded by the electrolyte remaining on the side of the electrolyte injection opening 242. In addition, since the welding portion is sufficiently compressed using the roller R at the same time as the laser welding or after the laser welding, the sealing property may be improved.

As described above, the present invention is not limited to the specific preferred embodiments described above, and any person having ordinary skill in the art to which the present invention pertains without departing from the gist of the present invention claimed in the claims. Various modifications are possible, of course, and such changes are within the scope of the claims.

According to the lithium secondary battery according to the present invention and a method for manufacturing the same, a separate ball press-in process is not required, and thus the process is simplified, and the sealing property can be improved since the laser welding using a metal plate on the upper part of the electrolyte injection hole and the adhesion by using a roller. It can be effective.

Claims (8)

An electrode assembly, A can housing the electrode assembly; In the lithium secondary battery comprising a cap plate having an electrolyte injection hole formed on one side, the cap assembly for sealing the top opening of the can, The electrolyte injection hole is sealed with a metal plate, the sealing is a lithium secondary battery, characterized in that the surface welding is made by laser welding. The method of claim 1, The metal plate is a lithium secondary battery, characterized in that formed of a material containing aluminum. The method according to claim 1 or 2, The metal plate is a lithium secondary battery, characterized in that formed to a thickness of 2.5% to 25% of the cap plate thickness. The method according to claim 1 or 2, The metal plate is a lithium secondary battery, characterized in that formed in a thickness of 20 to 200㎛. The method of claim 1, The surface welding is a lithium secondary battery, characterized in that the surface welding is made by scanning a welding site by firing a laser in a zigzag shape. A preparation step of preparing a bare cell, a metal plate, and a laser welder including a cap plate having an electrolyte injection hole formed therein; A welding step of placing a metal plate in an area to be sealed including the electrolyte injection hole and welding the surface between the area to be sealed and the metal plate by a laser welder; And Method of manufacturing a lithium secondary battery characterized in that it comprises a pressing step of pressing by pressing the welded portion through the welding step. The method of claim 6, The welding step is a manufacturing method of a lithium secondary battery, characterized in that made as scanning in a zigzag shape to the area to be sealed. The method of claim 6, The pressing step is a method of manufacturing a lithium secondary battery, characterized in that made in a way to rotate while pressing the roller.

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