KR100896133B1 - Secondary Battery of Improved Stability - Google Patents

Abstract

The present invention relates to a secondary battery in which an electrode assembly having a positive electrode / membrane / cathode structure is built in a battery case, wherein an indentation portion and / or a protrusion having a predetermined size is formed on at least one side of an outer circumferential surface of the electrode assembly, and an electrode is formed in the battery case. It provides a secondary battery characterized in that the inner structure is formed that can be engaged with the indentation and / or protrusion of the assembly.

The secondary battery according to the present invention can prevent the occurrence of a short by suppressing the sliding phenomenon of the electrode assembly during the external force such as dropping of the battery, application of an external impact, without causing defects in the assembly process and degradation of battery performance. Can be. In addition, depending on the external shape of the secondary battery, a medium-large battery module may be effectively manufactured by not using a separate member or using only a member having a simple structure.

Description

Secondary Battery of Improved Stability

1 is a perspective view of an assembly process of a secondary battery according to one embodiment of the present invention;

2A-2C are schematic views of an electrode assembly in which indentations and protrusions are selectively formed at various locations in accordance with embodiments of the present invention;

3 is a schematic plan view of a battery case in which the electrode assembly A of FIG. 2A is mounted, and FIG. 4 is a schematic view of an assembled state thereof;

5 is a schematic view of a battery module according to an embodiment of the present invention;

6 is a schematic perspective view of a battery module according to another embodiment of the present invention.

The present invention relates to a secondary battery having improved safety, and more particularly, a secondary battery in which an electrode assembly having a cathode / separation membrane / cathode structure is built in a battery case, and having a predetermined size indented on at least one side of an outer circumferential surface of the electrode assembly. A portion, or a protrusion, or an indentation and a protrusion is formed, and the battery case has an internal structure that can engage with the indentation, or the protrusion, or the indentation and the protrusion of the electrode assembly. The present invention relates to a secondary battery capable of preventing the electrode assembly from being pushed and ensuring safety.

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

Typically, the demand for lithium secondary batteries such as high energy density, discharge voltage, output stability lithium ion battery, lithium ion polymer battery, etc. is high in terms of battery material, and in terms of shape, it can be applied to products such as mobile phones with a thin thickness. And there is a high demand for square cells and pouch cells that can be used as batteries of battery modules that are stacked and manufactured with high integration. In particular, a pouch type battery having an electrode assembly embedded in a battery case of a laminate sheet including a metal layer and a resin layer is light in weight and easy to manufacture, and its application fields and demands have recently increased.

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

In the case of manufacturing a pouch type battery using a stacked electrode assembly, a plurality of positive or negative electrode tabs are connected to the electrode leads to protrude out of the battery case to form electrode terminals. Thus, an inner upper end of the battery case, that is, an upper end of the electrode assembly. In this case, a space for the electrode tab-electrode lead connection is required. Therefore, the stacked electrode assembly tends to be pushed up and moved upward when an external force such as a drop or an external impact is applied due to the space. However, in this upward movement, the electrode tab or the electrode lead (eg, the positive electrode tab or the anode lead) may cause a short (internal short circuit) while contacting the electrode plate (eg, the negative electrode plate) of the opposite electrode. An internal short circuit is a very serious problem in terms of safety of the battery because the temperature of the battery is increased by energization of overcurrent, and the supply field may cause fire or explosion.

Therefore, in order to solve this problem, some prior art proposes a technique of inserting an object to prevent the movement of the electrode assembly in the empty space of the upper end of the electrode assembly or filling the insulating resin and then solidifying. However, such a fixture may damage the electrode tab during insertion or may damage the connection of the electrode tab to the electrode lead, and the insulating resin may flow into the electrode assembly during the filling process or operation of the battery to degrade the performance of the battery. There are drawbacks to this.

Accordingly, there is a high demand for a technology capable of suppressing the sliding phenomenon of the stacked electrode assembly while preventing defects in battery assembly and deterioration of battery performance.

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

After in-depth research and various experiments, the inventors have formed an indentation, or protrusions, or indentations and protrusions on at least one side thereof in a stacked electrode assembly, and the inner structure that can engage and engage the battery case. When forming the battery and assembling the battery, it is confirmed that the battery assembly can be secured by preventing the sliding of the electrode assembly against external force without incurring defects in the assembling process or degrading the battery performance. It came to the following.

In addition, when the indentations and protrusions are formed not only on the inner surface of the battery case, but also on the outer surface, it was confirmed that such an outer structure is used as a binding site between the battery cells to facilitate the manufacture of a medium-large battery pack.

Accordingly, the secondary battery according to the present invention is a secondary battery in which an electrode assembly having a cathode / separation membrane / cathode structure is built in a battery case, and an indentation portion and / or protrusion having a predetermined size is formed on at least one side of an outer circumferential surface of the electrode assembly. The battery case is characterized in that the inner surface structure is formed that can be engaged with the indentation and / or protrusion of the electrode assembly.

That is, the secondary battery according to the present invention is fixed while engaging the indentation and / or protrusion of the outer peripheral surface of the electrode assembly in engagement with the indentation and / or protrusion of the inner structure of the battery case during the assembly of the battery, even if an external force such as drop, impact It is possible to prevent the electrode assembly from moving upward (sliding phenomenon) to prevent the internal short circuit as described above.

Some prior arts disclose examples of making the outer circumferential surface of the electrode assembly into an indented or projecting type (see Japanese Patent No. 3531552, Japanese Patent Application Laid-Open No. 1998-027602, Japanese Patent Application Laid-Open No. 1997-259859, etc.). As in the present invention, there is no known technique for forming a corresponding structure on the inner surface of the battery case so that they are engaged with each other.

The stacked electrode assembly is an electrode assembly having a structure in which a plurality of positive electrode plates and negative electrode plates having a predetermined size are sequentially stacked with a separator interposed therebetween, and electrode active materials are coated on both surfaces of the positive electrode plate and the negative electrode plate. The shape of such an electrode plate may vary, and an electrode plate having a substantially rectangular structure is frequently used.

In the secondary battery of the present invention, an indentation portion, a protrusion portion, or an indentation portion and a protrusion portion having a predetermined size is formed on at least one side of the outer circumferential surface of the electrode assembly. For example, an electrode assembly composed of electrode plates having a substantially rectangular structure has four outer circumferential surfaces thereof, so that the indentation portion, or the protrusion portion, or the indentation portion and the protrusion portion is formed on one side or two or more sides of the four sides. do. In this case, it is preferable that the indents, or the protrusions, or the indents and the protrusions are formed at both sides thereof with respect to the side (upper side) on which the electrode tab is formed. However, they may be formed on the upper side or the lower side, or may be formed only on one side of both sides. In the present invention, the outer circumferential side of the electrode assembly includes a corner thereof, and the indentation and the protrusion may be formed at one or two or more of four corners in the electrode assembly having four sides.

The indentation and / or protrusion may be formed together, for example, after applying the electrode active material to a metal foil as a current collector and then cutting it into an electrode plate using a die or the like.

The shape of the indents and protrusions is not particularly limited, and may be, for example, various shapes such as triangles, squares, semi-circles, etc., and may smooth edges such as edges thereof.

The size of the indentation and the protrusion is not particularly limited as long as it can prevent movement of the electrode assembly when an external force is applied. For example, a width of 10 to 50% and a depth of 5 to 30% (or Height).

Corresponding to the indentation or protrusion of the electrode assembly, the indentation or protrusion of the corresponding structure is formed on the inner surface of the battery case.

The indentation and the protrusion on the inner surface of the battery case may be formed in one of two ways. First, the battery case itself is deformed to form an indentation or protrusion, and the second is a method of installing a fixing member having an indentation or a protrusion formed on the inner surface of the battery case. The fixing member may be a frame structure fixed to the inner surface of the battery case by insertion, or may be in the form of a compact structure bonded or bonded to a part of the inner surface of the battery case. In view of the manufacturing process, the former method of deforming the battery case itself to form an indentation and a protrusion is more preferable.

The indents and protrusions on the battery case do not have to be completely identical in shape and size to the indents and protrusions of the electrode assembly, and may be any shape and size that can prevent an internal short circuit caused by the sliding of the electrode assembly. Do.

The battery case may be made of various materials, for example, a metal sheet, a polymer sheet, a laminate sheet including a metal layer and a resin layer, and the like. Especially, the battery case of a laminated sheet structure is especially preferable.

Other components constituting the secondary battery, that is, components of the electrode mixture including the electrode active material, components such as separators, electrolytes, and the like, are known in the art, the description thereof will be omitted in the present invention. .

The secondary battery according to the present invention can be preferably used as a unit battery, especially when manufacturing a large output medium-large battery module. That is, when the indentation or protrusion of the battery case is formed by the deformation of the battery case itself, such indentation or protrusion may be used as a binding portion for coupling the battery cells (unit cells) to each other.

Specifically, when the indentation is formed on one side of the battery cell, the protrusion is formed on the opposite side, and the protrusion has a size that can be inserted into the indentation, the second battery in the indentation of the first battery cell Engagement can be achieved by inserting the protrusions of the cell. This coupling method is preferable when the battery cells are arranged in a side to form a battery module. When stacking a plurality of battery cells in the lateral direction and the thickness direction, the binding portion is formed in two battery cells stacked in the thickness direction. It can also be arranged to be interconnected by.

In some cases, the battery module may be configured by stacking a plurality of battery cells in a thickness direction such that the indentations or protrusions are coaxially positioned, and coupling the frame member for manufacturing the battery module to the indentations or protrusions.

The medium-large battery module may be preferably used as a power source of an electric vehicle, a hybrid electric vehicle, and the like.

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

1 is a perspective view schematically illustrating a process of assembling a secondary battery according to one embodiment of the present invention.

Referring to FIG. 1, the secondary battery 100 has a structure in which a stacked electrode assembly 200 is embedded in a pouch type case 300 of an aluminum laminate sheet.

First, the electrode assembly 200 has a plurality of positive electrode plates and negative electrode plates of a substantially rectangular structure stacked with a separator interposed therebetween, and electrode tabs 210 and 212 from each electrode plate are disposed at the top thereof. 222). An electrically insulating film 230 is attached to the electrode leads 220 and 222. On both sides of the electrode assembly 200, indentations 240 of a predetermined size are formed symmetrically with each other.

The pouch-type case 300 includes a main body 310 in which an accommodating part 312 on which the electrode assembly 200 is seated is formed, and a cover 320 integrally connected to a lower end thereof. The receiving part 312 is formed with a protrusion 330 corresponding to the indentation part 240 of the electrode assembly 200.

Therefore, when the electrode assembly 200 is seated on the case 300, the protrusion 330 is inserted into the indentation 240 to be fixed, so that the electrode assembly receives an external force such as dropping of the assembled battery 100. An internal short circuit can be prevented by suppressing the sliding phenomenon of the 200.

2A to 2C are schematic views of an electrode assembly in which an indentation and a protrusion are selectively formed at various positions according to embodiments of the present invention.

Referring to these drawings, first, the electrode assembly A has a protrusion 250 formed on one side 202 with respect to the upper side 201 on which the electrode tab 210 is formed, and is indented on the opposite side 203. It consists of a structure in which the portion 240 is formed.

The electrode assembly B has a structure in which protrusions 250 are formed at both side edges 202 and 203, respectively, and the electrode assembly C has two protrusions 250 formed only at one side edge 202. It consists of a structure.

In addition, the electrode assembly D has a structure in which the protrusion 250 is formed only at the lower side 204, and the electrode assembly E has the protrusion 250 at one side 202 and the lower side 204, respectively. It consists of a structure that is formed.

In the secondary battery according to the present invention, the structure of the electrode plate may be other structures in addition to the above exemplary structures, and these are all included in the scope of the present invention.

3 is a schematic plan view of a battery case in which the electrode assembly A of FIG. 2A is mounted, and FIG. 4 is a schematic view of an assembled state thereof.

Referring to these drawings, the battery case 300 has an inner surface structure of the indentation portion 340 formed on one side wall corresponding to the protrusion 250 (FIG. 2A) of the electrode assembly A, and the indentation portion 240a (FIG. Corresponding to 2a), an inner surface structure of the protrusion 330 is formed on the opposite side wall. Since the indentation 340 and the protruding portion 330 are formed by the deformation of the battery case 200 itself, the indentation portion 340 is a protruding portion when the protruding portion 330 is a protruding portion based on the outer surface of the battery case 200. It may be expressed as an indentation.

The electrode assembly A mounted to the case 300 is fixed by engaging the protrusion 250 and the indentation 240 thereof with the indentation 340 and the protrusion 330 of the battery case inner structure. Therefore, since the electrode assembly A does not move upward even when an external force is applied, it is possible to prevent the occurrence of a short in the upper end space S of the electrode assembly A. FIG.

5 is a schematic view of a battery module according to an embodiment of the present invention.

Referring to FIG. 5, the battery module 400 has a structure in which the battery cells 100 as shown in FIG. 4, in which the electrode assembly A of FIG. 2A is built, are arranged in a lateral direction. Each of the battery cells 100 includes a protrusion 150 and an indentation 140 on the outer surface on both sides, and the protrusion 150 has a size that can be inserted into the indentation 140. Therefore, the continuously arranged battery cells 100 may achieve mechanical fastening without using a separate coupling member due to the insertion of the protrusion 150 to the indentation 140.

6 is a perspective view of a battery module according to another embodiment of the present invention.

Referring to FIG. 6, the battery module 401 has a structure in which battery cells 100 are stacked in the thickness direction as shown in FIG. 1. Since each of the battery cells 100 has indents 140 formed on both sides thereof on the outer surface thereof, when the battery cells 100 are sequentially stacked, long grooves are formed in the indents 140 in the thickness direction. Accordingly, the battery module 401 may be manufactured by combining the frame member 410 for manufacturing the battery pack, in which the groove 412 corresponding to the groove is formed.

Although some examples according to the present invention have been described with reference to the drawings, those skilled in the art will be able to perform various applications and modifications within the scope of the present invention based on the above contents.

As described above, the secondary battery according to the present invention suppresses the sliding phenomenon of the electrode assembly during external action such as dropping of the battery and application of an external impact without causing defects in the assembly process and deterioration of the battery performance. The occurrence of a short can be prevented. In addition, depending on the external shape of the secondary battery, a medium-large battery module may be effectively manufactured by not using a separate member or using only a member having a simple structure.

Claims (11)

A secondary battery in which an electrode assembly having a positive electrode / membrane / cathode structure is built in a battery case, wherein an indentation portion, a protrusion portion, or an indentation portion and a protrusion portion having a predetermined size are formed on at least one side of an outer circumferential surface of the electrode assembly. The secondary battery is characterized in that the inner structure which can be engaged with the indentation, or protrusions, or the indentation and the protrusions of the electrode assembly. The electrode assembly of claim 1, wherein the electrode assembly is formed of electrode plates having a rectangular structure, and the indentation part, or the protruding part, or the indentation part and the protruding part is formed on one side or two or more sides of four sides. Secondary battery. The secondary battery of claim 2, wherein the indented portion, or the protruding portion, or the indenting portion and the protruding portion are formed at both sides thereof on the side (upper side) on which the electrode tab is formed. The secondary battery of claim 1, wherein the indentation and the protrusion are triangular, square, or semicircular. The secondary battery of claim 1, wherein the indents and protrusions have a width of 10 to 50% and a depth (or height) of 5 to 30% with respect to the length of the sides. The secondary battery of claim 1, wherein the indentation and the protrusion on the inner structure of the battery case are formed by deforming the battery case itself. The secondary battery of claim 1, wherein the indentation and the protrusion on the inner surface of the battery case are formed by installing a fixing member having an indentation or a protrusion formed on an inner surface of the battery case. The secondary battery of claim 1, wherein the battery case is formed of a laminate sheet including a metal layer and a resin layer. A medium-large battery module including the secondary battery according to any one of claims 1 to 8 as a unit cell. The method of claim 9, wherein the indentation is formed on one side of the unit cell, the protrusion is formed on the opposite side, the protrusion has a size that can be inserted into the indentation, 2. The medium-large battery module of claim 2, wherein a plurality of unit cells are arranged on a side surface by inserting protrusions of the unit cells. 10. The method of claim 9, wherein the indentations or protrusions of the unit cell are laminated to a plurality of unit cells in the thickness direction so as to be located on the coaxial, and the indents or protrusions are configured by coupling the frame member for manufacturing a battery module Medium and large battery module.

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