KR20070101569A - Lithium rechargeable battery - Google Patents

Abstract

A lithium secondary battery is provided to prevent the separation of a protection circuit part from a bare cell due to the external impact or twisting. A lithium secondary battery comprises an electrode assembly; a can which accommodates the electrode assembly; and a cap assembly which is provided with a cap plate(140) and seals the can, wherein a projected part(144) is formed at the one part of the cap plate. Preferably the cap plate comprises a terminal penetration hole and an electrolyte injection hole, and the projected part is formed between the terminal penetration hole and the electrolyte injection hole.

Description

Lithium rechargeable battery

1 is an exploded perspective view of a bare cell and a protection circuit unit according to an embodiment of the present invention;

Figure 2 is an exploded perspective view of the bare cell of Figure 1

3A is a perspective view of the cap plate of FIG. 2

3B is a cross-sectional view taken along the line A-A of FIG. 3A

4 is a cross-sectional view of the cap plate with protrusions formed in different ways;

5A and 5B are perspective views of the anode lead plate according to an embodiment of the present invention.

6A and 6B are perspective views of a lead plate according to another embodiment of the present invention.

Figure 7a is a perspective view of a cap plate according to another embodiment of the present invention

FIG. 7B is a perspective view of the positive lead plate attached to the cap plate of FIG. 7A

<Description of Symbols for Main Parts of Drawings>

100-bare cell 112-electrode assembly

120-Can 130-Cap Assembly

140, 240, 340-Capplates 144, 244, 344-Protrusions

144a-Top 144b-Side

180, 280-Anode Lead Plate 181, 281-Fixture

184, 284-Connections 188-Negative Lead Plate

190-Protective circuit part 192-Anode terminal

194-negative terminal

The present invention relates to a lithium secondary battery, and more particularly, to a lithium secondary battery capable of improving the adhesion strength of the lead plate by increasing the contact area between the cap plate and the lead plate by forming a protrusion on the cap plate and attaching the lead plate. It is about.

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.

The lithium secondary battery generally includes a bare cell and a protection circuit part. The bare cell is formed by inserting an electrode assembly in which a positive electrode plate, a negative electrode plate, and a separator are wound into a can, and sealing an upper end of the can with a cap plate. When the internal temperature of the battery increases, the bare cell shuts down the pores of the separator so that no more current flows, thereby preventing overcharge, overcurrent, and overdischarge. In addition, when a large amount of gas is generated inside the battery, the safety cell formed on one side of the cap plate may be damaged to release the gas to the outside, thereby preventing explosion. In addition, in addition to the safety device at the bare cell level, the lithium secondary battery is equipped with a protection circuit unit to improve safety.

The electrode terminals of the protective circuit part are electrically connected to the bare cell through a separate lead plate. That is, the cap plate of the bare cell and the positive terminal of the protective circuit part are connected by the positive lead plate, and the negative terminal of the bare cell and the negative terminal of the protective circuit part are connected by the negative electrode lead plate. The anode lead plate has a substantially L-shape, one surface is attached to the cap plate and the other surface is attached to the anode terminal of the protective circuit portion. The protective circuit part is electrically connected to the bare cell and then fixed to the bare cell by hot melting resin. At this time, when the hot-melting resin portion is warped or impacted from the outside, the force is transmitted to the positive lead plate. Although one surface of the anode lead plate is attached to the cap plate by a welding method, there is a problem that the anode lead plate may be detached from the cap plate by an external impact. When the welding site is detached, the anode lead plate and the cap plate can be electrically connected only by contact. This increases the contact resistance between the anode lead plate and the cap plate has a problem that a lot of heat can be generated. In addition, when the positive electrode lead plate is completely separated from the cap plate, there is a problem in that an electric circuit is disconnected and a lithium secondary battery can no longer be used.

The present invention has been made to solve the above problems, and in particular, by forming a protrusion on the cap plate and attaching the lead plate, the lithium secondary battery that can increase the adhesion strength of the lead plate by increasing the contact area between the cap plate and the lead plate The purpose is to provide.

The lithium secondary battery of the present invention devised to solve the above problems is an electrode assembly; A can containing the electrode assembly; And a cap assembly having a cap plate and sealing the can, wherein the cap plate has a protrusion formed on one side thereof.

The cap plate may include a terminal through hole and an electrolyte injection hole, and the protrusion may be formed between the terminal through hole and the electrolyte injection hole. In addition, the cap plate may include a terminal through-hole and a safety vent, and the protrusion may be formed between the terminal through-hole and the safety vane.

In addition, the protrusion may be formed in an outward direction of the can.

The protrusion may include an upper surface and a side surface, and the upper surface may be formed in any one of a rectangular shape, an elliptical shape, a circular shape, and a polygonal shape. In addition, the protrusion may include an upper surface and a side surface, and a lead plate may be welded to the protrusion.

In addition, the lead plate may be formed to be in contact with at least one surface and the upper surface of the side surface of the protrusion. In addition, the lead plate may include a connection part electrically connected to the protection circuit part and a fixing part electrically connected to the protrusion part.

In addition, the fixing portion may be formed in a can shape of which one side is open. In addition, the protrusion may be inserted into the fixing part.

The cap plate may include a pair of opposite long sides and a pair of short sides facing each other, and at least two protrusions may be formed to be parallel to the long sides, and a lead plate may be inserted between the protrusions.

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

1 is an exploded perspective view of a bare cell and a protection circuit unit according to an exemplary embodiment of the present invention. FIG. 2 is an exploded perspective view of the bare cell of FIG. 1. 3A is a perspective view of the cap plate of FIG. 2, and FIG. 3B is a sectional view taken along line A-A of FIG. 3A. 4 shows a cross-sectional view of a cap plate in which protrusions are formed in different ways. 5A and 5B illustrate perspective views of a positive electrode lead plate according to an embodiment of the present invention.

A lithium secondary battery according to an embodiment of the present invention, referring to FIG. 1, includes a bare cell 100 and a protection circuit unit 190. The bare cell 100 includes an electrode terminal 135, an electrolyte injection hole 142, and a jaw 144. In addition, the bare cell 100 may further include a safety vent 143. A protection circuit is formed in the protection circuit unit 190, and a positive electrode terminal 192 and a negative electrode terminal 194 are formed. The anode terminal 192 is electrically connected to the cap plate 140 including the jaw 144 through the anode lead plate 180. In addition, the negative electrode terminal 194 is electrically connected to the electrode terminal 135 through the negative lead plate 188. Although not shown, the protection circuit 190 may be fixed to the bare cell 100 by a hot melting resin or the like.

Referring to FIG. 2, the bare cell 100 receives the electrode assembly 112 including the positive electrode plate 113, the negative electrode plate 115, and the separator 114 together with the electrolyte in the can 120. The upper opening 120a of the 120 is formed by sealing the cap assembly 130. The bare cell 100 includes a front side and a rear side including a long side and formed to face each other, both sides formed to face each other and facing each other, and an upper surface facing the cap plate 140 and the top surface. Including the lower surface.

The electrode assembly 112 is formed by winding a separator 114 between the positive electrode plate 113 and the negative electrode plate 115.

The positive electrode plate 113 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 113, 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 116 protruding a predetermined length to the upper portion of the electrode assembly 112 is bonded.

The negative electrode plate 115 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 115 are provided with 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), and the negative electrode tab 117 protruding a predetermined length to the lower portion of the electrode assembly 112 is bonded. In addition, an insulating plate for preventing contact with the can 120 may be further included below the electrode assembly 112.

The separator 114 may be interposed between the positive electrode plate 113 and the negative electrode plate 115 and extend to surround the outer circumferential surface of the electrode assembly 112. The separator 114 prevents a short circuit between the positive electrode plate 113 and the negative electrode plate 115 and is formed of a porous membrane polymer material to allow lithium ions to pass therethrough.

The can 120 is formed in a substantially box shape including a pair of long side walls 122 having a substantially rectangular shape, a pair of short side walls 124 and a bottom plate 120b, and an upper portion thereof is opened to open an upper end thereof. It forms 120a. In addition, when the can 120 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 112 is inserted into the upper opening 120a. In addition, an electrolyte solution is impregnated between the electrode assemblies 112 to enable the movement of lithium ions. The material of the can 120 is mainly light aluminum (Al). The upper portion of the can 120 is sealed by the cap assembly 130, the leakage of the electrolyte is prevented. The long side wall 122 and the short side wall 124 of the can 120 have a thickness of 0.2 to 0.4 mm, and the bottom plate 120b has a thickness of 0.2 to 0.7 mm. The can 120 is preferably formed by a deep drawing method, and the long side wall 122, the short side wall 124, and the bottom plate 120b are integrally formed.

The cap assembly 130 includes a cap plate 140, an insulation plate 160, a terminal plate 165, and an electrode terminal 135. The cap assembly 130 is combined with a separate insulating case 170 to be coupled to the top opening 120a of the can 120 to seal the can 120.

3A and 3B, the cap plate 140 is welded to the upper end opening 120a of the can 120 to seal the can 120. The terminal hole 1 141 is formed in the center of the cap plate 140, and the electrode terminal 135 insulated by the gasket tube 174 is inserted into the terminal hole 1 141. The cap plate 140 has an electrolyte injection hole 142 formed at one side thereof, and the electrolyte injection hole 142 is press-fitted or welded with a ball or the like. In addition, a safety vent 143 may be further formed on the other side of the cap plate 140. The safety vent 143 is formed thinner than other portions of the cap plate 140 is made to break when the internal pressure rises. However, the safety vent 143 may not be formed depending on the design of the battery and may be formed in the can 120.

In addition, a protrusion 144 is formed between the terminal through-hole 1 141 and the electrolyte injection hole 142. Although not shown, the protrusion 144 may be formed between the terminal hole 1 141 and the safety vent 143. Thus, the protrusion 144 is not limited to a specific position. The protrusion 144 is formed to protrude in an outward direction of the can 120. That is, the protrusion 144 is formed in a direction opposite to the direction in which the electrode assembly 112 is located. The protrusion 144 includes an upper surface 144a and a side surface 144b. The upper surface 144a may be formed to be substantially parallel to the upper surface of the cap plate 140 and may have a square shape. When the upper surface 144a is formed in a square shape, the side surface 144b is formed in four surfaces. Although not shown, the upper surface 144a may be formed in an oval shape, a circular shape, or a polygonal shape. The protrusion 144 may be formed by pressing by pressing, as shown in FIG. 3B. That is, the protrusion 144 is applied to the upper surface direction from the lower surface of the cap plate 140 to form a concave portion on the lower surface of the cap plate 140, the protrusion 144 is formed on the upper surface. At this time, the thickness of the protrusion 144 is formed to be substantially similar to the thickness of the other portion of the cap plate 140. Meanwhile, referring to FIG. 4, the protrusion 244 may be formed in a manner different from that of FIG. 3B. That is, the protrusion 244 may be formed together when manufacturing the cap plate 240 as shown in FIG. 4. In this case, the protrusion 244 is formed thicker than other portions of the cap plate 240. The positive lead plate 180 is welded to the protrusions 144 and 244, but the negative lead plate may be welded according to the design of the battery.

Subsequently, the insulating plate 160 is formed of an insulating material such as a gasket and is coupled to the lower surface of the cap plate 140. The insulating plate 160 has a terminal through hole 2 161 into which the electrode terminal 135 is inserted at a position corresponding to the terminal through hole 1 141 of the cap plate 140. A mounting groove 162 corresponding to the size of the terminal plate 165 is formed on the bottom surface of the insulating plate 160 so that the terminal plate 165 is seated.

The terminal plate 165 is generally formed of Ni alloy and is mounted on the bottom surface of the insulating plate 160. The terminal plate 165 has a terminal through hole 3 167 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 174 and coupled through the terminal through hole 1 141 of the cap plate 140, so that the terminal plate 165 is electrically insulated from the cap plate 140, and the electrode terminal 135. Is electrically connected).

The negative electrode tab 117 coupled to the negative electrode plate 115 is welded to one side of the terminal plate 165, and the positive electrode tab 116 coupled to the positive electrode plate 113 is welded to the other side of the cap plate 140. . Although not shown, the negative electrode tab 117 may be welded to the lower end of the electrode terminal 135 instead of the terminal plate 165. Resistance welding, laser welding, or the like is used as a welding method for bonding the negative electrode tab 117 and the positive electrode tab 116, and resistance welding is generally used.

The electrode terminal 135 is connected to the negative electrode tab 117 of the negative electrode plate 115 or the positive electrode tab 116 of the positive electrode plate 113 to act as a negative electrode terminal or a positive electrode terminal.

5A and 5B, the anode lead plate 180 includes a connection part 184 electrically connected to the protection circuit unit 190 and a fixing part 181 electrically connected to the protrusion 144. It is formed to include. The fixing part 181 may be formed in a can shape of which one side is open. Since the fixing part 181 is formed in a shape corresponding to the shape of the protrusion 144, it may be changed according to the shape of the protrusion 144. That is, when the protrusion 144 is formed in a rectangular pillar shape, the fixing portion 181 may also be formed in a rectangular can shape as shown in FIG. 5B. The fixing part 181 may be formed in a cylindrical can shape, an elliptic can shape, or a prismatic can shape according to the shape of the protrusion 144. The protrusion 144 is inserted into the fixing part 181. That is, the fixing part 181 is formed to contact the upper surface 144a and the side surface 144b of the protrusion 144. After the protrusions 144 are inserted into the fixing part 181, they are firmly fixed by welding to each other. At this time, the welding of the fixing portion 181 and the protrusion 144 is preferably made of a laser welding method. After welding of the fixing part 181, welding between the connection part 184 and the positive electrode terminal 192 of the protection circuit part 190 is performed.

In this way, since the positive electrode lead plate 180 is in contact with the protrusions 144 and 244 of the cap plates 140 and 240 in a large area, the anode lead plate 180 may be more firmly attached to the cap plates 140 and 240.

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

6A and 6B show perspective views of a lead plate according to another embodiment of the present invention. The embodiment of FIG. 6A is similar to the embodiment of FIG. 5A except that the fixing portion 281 is not formed in a can shape in which four directions are blocked, but is formed in an approximately C shape by being blocked in only two directions, and thus, the embodiment will be described based on differences. .

According to another embodiment of the present invention, a lithium secondary battery is formed including a bare cell and a protection circuit unit. The bare cell and the protection circuit of the lithium secondary battery are electrically connected by the positive lead plate 280 and the negative lead plate (not shown). The anode lead plate 280 is formed to include a fixing portion 281 and the connecting portion 284. 6A and 6B, the fixing part 281 is formed in a substantially C shape. That is, the fixing portion 281 is closed in only two opposite directions, and is open in the remaining two directions. Although not shown, the protrusion of the cap plate may be formed in a thin rectangular pillar form as in the embodiment of FIG. 3B or 4. Therefore, the fixing part 281 is formed to cover only the upper surface of the protrusion and two opposite sides of the four sides. In addition, the fixing part 281 may be attached to the upper surface and two side surfaces of the protrusion by laser welding.

Next, a lithium secondary battery according to still another embodiment of the present invention will be described.

FIG. 7A illustrates a perspective view of a cap plate according to still another embodiment of the present invention, and FIG. 7B illustrates a perspective view of a state in which a positive lead plate is attached to the cap plate of FIG. 7A. The embodiment of FIG. 7A is similar to the embodiment of FIG. 3A except that the protrusions 344 are formed in a wall shape parallel to each other, and thus description will be made mainly on differences.

Referring to FIG. 7A, the cap plate 340 according to another embodiment of the present invention is formed to include a pair of opposite long sides and a pair of opposite short sides. In addition, the cap plate 340 has a protrusion 344 formed on the upper surface. At least one protrusion 344 may be formed to be parallel to the long side. Of course, the protrusion 344 may be formed to be parallel to the short side. However, the protrusion 344 is preferably formed in plurality in parallel with the long side in terms of ensuring a sufficient length. The protrusion 344 may be formed in two wall shapes parallel to each other. Between the protrusions 344, referring to FIG. 7B, an anode lead plate 180 is inserted and attached. As shown in FIG. 7B, an anode lead plate 180 according to the embodiment of FIG. 5A may be inserted and attached between the protrusions 344. In addition, although not shown, the positive lead plate 280 according to the embodiment of FIG. 6A may be inserted and attached between the protrusions 344. Laser welding may be performed between the inner surface of the protrusions 344 and the fixing portion 181 of the anode lead plate 180.

Next, the operation of the lithium secondary battery to which the cap plate and the positive electrode lead plate according to the embodiment of the present invention are applied will be described. In the following description, a case where the cap plate 140 and the anode lead plate 180 according to the embodiment of FIG. 1 are applied will be described.

1, a lithium secondary battery according to an exemplary embodiment of the present invention includes a bare cell 100 and a protection circuit unit 190. The bare cell 100 and the protection circuit unit 190 are electrically connected to each other by the positive lead plate 180 and the negative lead plate 188. The bare cell 100 and the protection circuit unit 190 may be coupled to each other by a hot melt resin.

When the lithium secondary battery receives an external impact or distortion force such as a drop, the force is transmitted to the protection circuit unit 190 attached by the hot melt resin. The protection circuit 190 is fixed to the bare cell 100 by the positive lead plate 180, the negative lead plate 188, and a hot melt resin. Therefore, the force transmitted to the protection circuit unit 190 is directly transmitted to the anode lead plate 180. The anode lead plate 180 is formed in a rectangular can shape, and is bonded and welded to the square pillar-shaped protrusion 144 formed on the cap plate 140 with a wide contact area. Therefore, even when an external impact or twisting force such as a drop is applied, the positive lead plate 180 is firmly coupled to the cap plate 140 so as not to be separated from the cap plate 140. As a result, the protection circuit unit 190 may be separated from the bare cell 100 to prevent the electric circuit is disconnected.

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, the positive electrode lead plate is welded to the protruding portion with a wide contact area, thereby preventing the protection circuit from being detached from the bare cell by external impact or twisting force.

Claims (11)

Electrode assembly; A can containing the electrode assembly; And a cap assembly having a cap plate and sealing the can, the lithium secondary battery comprising: The cap plate is a lithium secondary battery, characterized in that a protrusion formed on one side. The method of claim 1, The cap plate includes a terminal through the electrolyte injection hole, The protruding portion is a lithium secondary battery, characterized in that formed between the terminal hole and the electrolyte inlet. The method of claim 1, The cap plate includes a terminal hole and a safety band, The protrusion is a lithium secondary battery, characterized in that formed between the terminal hole and the safety vent. The method of claim 1, The protrusion is a lithium secondary battery, characterized in that formed in the outward direction of the can. The method of claim 1, The protrusion includes an upper surface and a side surface, wherein the upper surface is formed in any one of a rectangular shape, an elliptical shape, a circular shape, and a polygonal shape. The method of claim 1, The protrusion includes an upper surface and a side surface, and the lead plate is welded to the protrusion. The method of claim 6, The lead plate is a lithium secondary battery, characterized in that formed in contact with at least one side and the upper surface of the side of the protrusion. The method of claim 7, wherein The lead plate is a lithium secondary battery characterized in that it comprises a connecting portion electrically connected to the protective circuit portion, and a fixing portion electrically connected to the protrusion. The method of claim 8, The fixing part is a lithium secondary battery, characterized in that formed in a can shape of one side is open. The method of claim 9, Lithium secondary battery, characterized in that the protrusion is inserted into the fixing portion. The method of claim 1, The cap plate includes a pair of opposing long sides and a pair of short sides facing each other, wherein at least two protrusions are formed to be parallel to the long sides, and a lead plate is inserted between the protrusions. Secondary battery.

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