KR100612236B1 - Secondary battery and electrodes assembly - Google Patents

Abstract

The present invention relates to a secondary battery having improved weldability, comprising an electrode group formed by winding a positive electrode plate and a negative electrode plate with a separator interposed therebetween, a case in which the electrode group is housed, and a cap assembly assembled to the case and sealed thereto. The anode plate and the cathode plate may be formed of a non-coated portion to selectively form a contact surface having a predetermined length, and a current collector plate may be electrically connected to the contact surface.

Plain area, current collector, contact, bending, planarization, secondary battery

Description

Secondary battery and electrode assembly for use {SECONDARY BATTERY AND ELECTRODES ASSEMBLY}

1 is a perspective view showing the overall appearance of a secondary battery manufactured in a cylindrical shape according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the rechargeable battery illustrated in FIG. 1.

3 is a view for explaining the position of the contact surface formed in the uncoated portion according to an embodiment of the present invention.

4 is a view showing a contact relationship between a current collector plate and a contact surface.

The present invention relates to a secondary battery, and more particularly, to a secondary battery having improved welding characteristics of a current collector plate to an uncoated portion, and an electrode assembly used therefor.

A secondary battery is a battery that can be charged and discharged unlike a primary battery that cannot be charged. In the case of a low-capacity battery in which one battery cell is packaged in a pack form, a secondary battery is portable such as a portable telephone, a notebook computer, and a camcorder. In the case of a large-capacity battery in a battery pack unit, which is used in small electronic devices and dozens of battery cells are connected, it is widely used as a power source for driving a motor such as a hybrid vehicle.

The secondary battery is manufactured in various shapes, and typical shapes include cylindrical and square shapes. An electrode group formed by alternately winding a positive electrode plate and a negative electrode plate is installed in a case, and an electrode terminal formed therefrom is formed. It consists of a form provided.

On the other hand, the positive and negative plates serve to collect current generated when the battery is in operation, and conductive tabs are attached to the respective conductive tabs, and the conductive tabs are attached to the electrode group by welding, respectively, to respectively generate the current generated in the positive and negative plates. It will lead to the positive and negative terminals.

In another aspect, in the current collector structure of the secondary battery, in the case of the high output secondary battery, a plate-shaped current collector plate instead of a tab has been proposed to reduce the resistance of the battery.

By the way, the secondary battery of such a collector plate structure poses the problem that a welding defect is caused between an electrode group and a collector plate.

That is, the electrode group is formed in the form of a jelly roll, and in welding the current collector plate with each other, an uncoated portion is formed at both ends of the electrode group to which the active material is not coated. Due to the step, the contact area with the current collector plate is reduced. There is a problem that welding is not made properly.

Furthermore, when the uncoated portion is formed at each corner of each of the electrode group and the negative electrode plate, the current collector plate and the uncoated portion are selectively in contact with each other due to the height difference of the uncoated portion. Accordingly, the contact area between the current collector plate and the electrode group is further reduced, resulting in poor welding and poor current collection efficiency.

This problem is more serious for high-output large-capacity secondary batteries for driving motors, such as for HEVs (hybrid electric vehicles). When these poor battery cells are assembled to form one battery pack, the distribution of internal resistance between each battery cell is reduced. Each sea's output state is unstable, making it difficult to apply to devices that require high output electrical energy.

Accordingly, the present invention is to solve the above problems, an object of the present invention is to increase the contact area between the current collector plate and the uncoated portion, to improve the welding defect between the two while adjusting the operation characteristics of the secondary battery to a large capacity high output An improved secondary battery is provided.

In order to achieve the above object, the secondary battery of the present invention,

An electrode group formed by winding a positive electrode plate and a negative electrode plate with a separator interposed therebetween, a case in which the electrode group is housed, and a cap assembly assembled to the case and sealing the electrode plate. The non-coated portion is formed, and the current collector plate is electrically connected to the contact surface.

In the present invention, the contact surface may be formed by bending a portion of the plain portion in the direction of the center of the electrode group.

In this case, the contact surface is preferably formed by bending the plain portion to 0.5 to 2.0 mm (mm).

In the present invention, it is preferable that an uncoated portion is formed at one end of the positive electrode plate, and a flat contact surface is formed while the uncoated portion is bent in the same direction, and the current collector plate is coupled thereon.

In addition, a non-coating portion may be formed at one end of the negative electrode plate, and a flat contact surface may be formed in a state in which the non-coating portion is bent in the same direction, and the current collecting plate may be coupled thereon.

In the present invention, the non-coating portion is formed without applying an active material to the end of the positive electrode plate and (and) negative electrode plate, and the electrode group may be formed by winding them in a state in which the non-coating portions are folded to each other in a direction facing each other.

Secondary battery electrode assembly provided in another embodiment of the present invention,

The positive electrode plate and the negative electrode plate formed by winding a separator between the electrode group, the negative electrode plate or the positive electrode plate is formed without applying an active material at one end in the longitudinal direction, and is formed with a constant length to form a contact surface for surface contact, And a current collector plate electrically connected to the contact surface.

The secondary battery provided in this embodiment is preferably composed of a battery module configured in a pack unit by connecting a plurality of secondary batteries to each other. In this case, the plurality of secondary batteries connected to each other are packaged in a housing in a state connected to a battery management system (BMS) that controls and manages operation and temperature.

In addition, the secondary battery (or the battery module) of the present invention is a device that operates by using a motor such as a HEV (hybrid car), an EV (electric vehicle), a wireless cleaner, an electric bicycle, an electric scooter, and the like. Can be used as an energy source for driving

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

1 is a cross-sectional view showing a secondary battery formed in a cylindrical shape according to an embodiment of the present invention, Figure 2 is a cross-sectional view thereof. In the following description, for example, the present invention is applied to a cylindrical battery based on this, but the present invention is not limited thereto.

1 and 2, the secondary battery according to the present exemplary embodiment includes the electrode group 10 in which the positive electrode plate 11 and the negative electrode plate 12 are positioned with the separator 13 interposed therebetween, and the electrode group 10 together with the electrolyte solution. A cylindrical case 20 having one end open to accommodate the cap, a cap assembly 30 installed at an upper end of the opening of the case 20 through a gasket 31 and sealing the case 20; The electrode group 10 includes a positive and negative electrode current collector plates 40 and 50 electrically connected to the positive and negative portions 11a and 12a formed on the negative electrode plates 11 and 12, respectively. The non-coated portions 11a and 12a formed on each pole plate are bent toward the horizontal crimp center to form a uniform contact surface 11b and 12b of a constant length.

In more detail, the case 20 is made of a conductive metal such as aluminum, an aluminum alloy or nickel plated steel, and the shape is formed in a cylindrical shape having an inner space part in which the electrode group 10 is located.

In addition, the cap assembly 30 includes a cap plate 32 having an external terminal 32a and a gasket 31 that insulates the case 20 from the cap plate 32 and is broken under a set pressure condition. A vent plate 33 may be further included to prevent explosion of the battery by releasing gas, which is electrically connected to the positive electrode current collector plate 40 through the lead wire 35. The vent plate 33 is not limited to the illustrated shape as long as it can block electrical connection between the electrode assembly 10 and the external terminal 32a through the lead wire 35 under a set pressure condition. Can be.

Here, the electrode group 10 is formed of a structure in which the positive electrode plate 11 and the negative electrode plate 12 are formed by coating each active material on the current collector, with the separator 13 interposed therebetween, or the positive electrode plate 11 and the separator. (13) and the negative electrode plate 12 are laminated | stacked and it consists of a jelly roll type formed by winding in vortex form.

The electrode group 10 configured as described above comprises one current collector plate 40 and 50 electrically connected to the positive electrode plate 11 and the negative electrode plate 12, which will be described in more detail. Same as

The uncoated portions 11a and 12a are disposed at each end of the positive electrode 11 plate and the negative electrode plate 12, and the positive electrode plate 11 and the negative electrode plate are placed between the separators so that the uncoated portion comes out of the electrode group 10 in this state. It is wound up to form a cylindrical electrode group 10. As a result, both ends of the electrode group 10 are protruded from each other.

In this state, the electrode group 10 is placed upright so that the anode uncoated portion 11a faces upward, and the anode uncoated portion 11a is positioned upward.

Subsequently, the positive electrode non-coating portion 11a is bent in the direction of the center of the transverse crimp, thereby forming the flat portion 11a into a flat plate shape, thereby increasing the contact area with the current collecting plate, thereby increasing the area of the current collector plate by welding. Fixing can be made easy.

Further, by uniformly bending the uncoated portion in the direction of the center of the transverse crimp, the uncoated portion 11a itself is bent uniformly, and thus the uncoated portion can make the contact surfaces 11b and 12b themselves flat.

At this time, in the present invention, in forming the contact surface 11b, the length h of the non-coated portion is bent in the range of 0.5 to 2.0 mm (mm) (see Fig. 3). In general, in the case of a large capacity secondary battery used for driving a motor, the thickness of the current collector and the separator 13 is 50 micrometers (µm) to 500 micrometers. And the active material layer applied to both sides of the current collector is made of 350 micrometers to 500 micrometers. Meanwhile, since two separators 13 and a negative electrode plate 12 are positioned between the positive electrode plate 11 and the positive electrode plate 11, the distance between the positive electrode plate 11 and the positive electrode plate 11 is 0.5 mm to 2.0 mm. Since the negative electrode plate 12 also has the same structure as the positive electrode plate 11, the interval between the negative electrode plates 12 is also 0.5 mm to 2.0 mm. Therefore, if the length h of the plain portion to be bent is smaller than 0.5 mm, the contact surface becomes smaller than the minimum distance between the pole plates 11 and 12 so that the plain portions 11a and 12b partially contact the current collector plates 40 and 50. Problem occurs that the current collection efficiency is lowered, and when the length of the plain sheet to be bent (h) is greater than 2.0 mm, the length (h) of the plain sheet to be bent is greater than the maximum interval between the pole plates 11 and 12, Since the current collector plates 40 and 50 contact only the stepped projections 11 and 12 overlapping each other, the uncoated parts 11a and 12a and the current collector plates 40 and 50 partially contact each other, thereby lowering current collection efficiency. Occurs.

After forming the contact surface 11b by bending the uncoated portion 11a to a predetermined length as described above, the current collector plate on the plate is placed thereon and fixed by welding.

At this time, the welding between the current collector plate and the contact surface 11b is preferably fixed by laser welding. In the case where the contact surface is formed in the plain portion as in the present invention, the house naturally contacts the contact surface 11b within the focal length of the laser gun for laser welding. Since the front plate can be positioned, there is an advantage that welding can be uniformly applied over the entire contact surface (see FIG. 4).

After the contact surface 11b is formed on the positive electrode non-coated portion 11a and the current collector plate 40 is fixed, the negative electrode current collector plate 50 is coupled to the negative electrode non-coated portion 12a in the same manner. Optionally, the negative electrode non-coating portion 12a may be brought into contact with the case 20 as it is without forming a current collector plate, and only the contact surface 11b is formed.

In this way, the electrode assembly 10 is coupled to the current collector plate to form an electrode assembly, and the electrode assembly is accommodated in the case to complete the secondary battery, which will be described in more detail as follows.

After assembling the electrode assembly as described above, the electrode assembly is inserted and seated in the open direction of the case. At this time, the electrode assembly is accommodated in the case such that the positive electrode current collector plate 40 of the electrode assembly faces upward, that is, the direction in which the cap assembly is coupled.

Accordingly, the negative electrode current collector plate contacts the bottom surface of the case to form the negative electrode of the secondary battery. In this case, the cathode collector plate and the bottom surface of the case may be fixed by welding.

After accommodating the electrode assembly inside the case 20, the cap assembly is coupled to the opening. In this case, the lead assembly is connected to the positive electrode current collector plate 40 to couple the cap assembly to the case while being connected to the cap assembly, and the electrolyte is injected into the case 20 to impregnate the electrode assembly. Accordingly, the cap assembly forms the positive electrode of the battery.

In this state, the secondary battery according to the present embodiment is completed by fixing the cap assembly to the case by placing the cap assembly in the opening of the case and beading the case while the cap assembly and the case are insulated from each other by a gasket.

As described above, although the present invention has been described by way of limited embodiments and drawings, the present invention is not limited thereto and is intended by those skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of equivalents of the claims to be described.

According to the present invention, there is an effect of improving the welding characteristics between the two while improving the above-mentioned problems to increase the contact area between the current collector plate and the plain portion. In addition, by increasing the contact area between the uncoated portion and the current collector plate, the internal resistance and the output are improved, thereby increasing the reliability of the product.

Claims (11)

An electrode group formed by winding a positive electrode plate and a negative electrode plate with a separator interposed therebetween; A case accommodating the electrode group; And, A cap assembly assembled to the case to seal the cap assembly; Including, A secondary battery having a structure in which the positive electrode and the negative electrode plate is formed with a non-coated portion to form a contact surface bent (optionally) to 0.5 to 2.0 mm (mm), the current collector plate is electrically connected to the contact surface. The method of claim 1, A secondary battery, wherein the contact surface is formed by bending a portion of the plain portion toward the center of the electrode group. delete The method of claim 2, A rechargeable battery is formed at one end of the positive electrode plate, and a flat contact surface is formed in a state in which the non-coating portion is bent in the same direction, and the current collector plate is coupled thereon. The method of claim 2, A rechargeable battery is formed at one end of the negative electrode plate, and a flat contact surface is formed in a state in which the non-coating portion is bent in the same direction, and the current collector plate is coupled thereon. The method according to any one of claims 1 to 5, A secondary battery, wherein the non-coating portion is formed without applying an active material to an end portion of the positive electrode plate and / or the negative electrode plate, and the electrode group is formed by winding them in a state where the non-coating portion is folded with each other in a direction facing each other. The method of claim 1, Secondary battery is secondary battery is formed in a cylindrical shape. The method of claim 1, A secondary battery, wherein the secondary battery is for driving a motor. An electrode group in which a positive electrode plate and a negative electrode plate are wound around a separator; An uncoated portion formed on the positive electrode plate or the negative electrode plate without applying an active material at one end thereof in a longitudinal direction; And, A current collector plate electrically connected to the contact surface; Including; The non-coating portion is bent to 0.5 to 2.0 mm (mm) to form a contact surface in contact with the current collector plate, and the non-coating portion is bent toward the center of the electrode group electrode assembly. delete delete

Images