WO2017179768A1

WO2017179768A1 - Secondary battery

Info

Publication number: WO2017179768A1
Application number: PCT/KR2016/008011
Authority: WO
Inventors: 이원진
Original assignee: 삼성에스디아이(주)
Priority date: 2016-04-11
Filing date: 2016-07-22
Publication date: 2017-10-19
Also published as: KR102518352B1; KR20170116510A

Abstract

The present invention relates to a secondary battery which is manufactured in a manner that a case is sealed by bonding. The secondary battery may comprise: an electrode assembly including a cathode plate, an anode plate, and a separator; a case having a hexahedron shape with an opened side for housing the electrode assembly; a cap assembly which is bonded to the opened side of the case and seals the electrode assembly against the outside; and a protective cover which is made of a heat insulating material and is disposed between the cap assembly and the electrode assembly inside the case, wherein an edge of the protective cover near the cap assembly is chamfered or a region of the side facing the case corresponding to the bonding line of the case is recessed toward the electrode assembly, to thereby form a disengaging section.

Description

Secondary battery

The present invention relates to a secondary battery, and more particularly, to a secondary battery manufactured by sealing a case by bonding.

With the emergence of new electronic devices such as wearable devices and drones, as well as the high performance and light weight of existing electronic devices such as mobile phones, notebook computers and camcorders, many studies are being conducted on the batteries used as driving power sources. . In particular, rechargeable batteries capable of charging and discharging, such as lithium secondary batteries, have an energy per unit weight compared to conventional lead acid batteries, nickel-cadmium (Ni-Cd) batteries, nickel-hydrogen (Ni-MH) batteries, and nickel-zinc batteries. As the density is about three times higher and faster charging is possible, the field of application is expanding not only for the energy source of electric vehicles but also for the auxiliary power of smart grid.

The secondary battery includes an electrode assembly in which a positive electrode plate and a negative electrode plate are laminated with a separator interposed therebetween, a case in which a side is opened, and a case accommodating the electrode assembly together with an electrolyte through an opening, and one side opening of the case in a state in which the electrode assembly is accommodated. And a cap plate for closing the cap plate, and an electrode terminal coupled to the cap plate and electrically connected to the electrode assembly. An insulating case may be intervened to maintain electrical insulation between the electrode assembly and the cap plate. Here, the electrode assembly has a structure in which a positive electrode plate and a negative electrode plate, and separators disposed therebetween are sequentially stacked, and the separator is usually made larger than the two electrode plates to prevent energization between the positive electrode plate and the negative electrode plate. Therefore, the separator may be partially exposed in the axial direction of the roll in the case of the jelly-roll type, or in the thickness direction of the stacked positive and negative plates in the case of the stack type. to be.

On the other hand, the case and the cap plate need to seal the inner space in order to prevent leakage of electrolyte, etc., thus ensuring a reliable bonding through a process such as laser welding. In the welding process between the case and the cap plate, heat is generated, which causes a problem that the electrode assembly, especially the separator exposed between the two electrode plates, is damaged by the heat, so that electricity may be generated between the positive electrode plate and the negative electrode plate. This problem can occur similarly when the insulating case covers the exposed separator, since the insulating case is only intended for the electrical insulation between the electrode assembly and the cap assembly.

An object of the present invention is to provide a secondary battery that can prevent the electrode assembly from being damaged by heat in the process of bonding the case by welding.

Other objects, specific advantages and novel features of the invention will become more apparent from the following detailed description and preferred embodiments in conjunction with the accompanying drawings.

A secondary battery according to the present invention includes an electrode assembly including a positive electrode plate, a negative electrode plate, and a separator, a case accommodating the electrode assembly in an open hexahedral shape, and a surface bonded to one opened surface of the case to externally attach the electrode assembly. A cap assembly sealing against the cap assembly, and a protective cover made of a heat insulating material and disposed between the cap assembly and the electrode assembly in the case, the edge of the side close to the cap assembly being chamfered to form an evacuation portion. Can be.

In the secondary battery according to the present invention, an inner surface of the chamfered edge of the protective cover may be substantially parallel to the chamfered surface. In addition, the electrode assembly may include a positive electrode tab and a negative electrode tab respectively extending from the positive electrode plate and the negative electrode plate, and the protective cover may have a through hole through which the positive electrode tab and the negative electrode tab respectively pass.

In addition, the secondary battery according to the present invention includes an electrode assembly including a positive electrode plate, a negative electrode plate, and a separator, a case in which the first part and the second part are bonded to each other and sealed to the outside, and the housing containing the electrode assembly; And a protective cover disposed between the case and the electrode assembly inside the case, wherein a region corresponding to a junction line of the case of one surface facing the case is recessed toward the electrode assembly to form an avoidance part. Can be.

In the secondary battery according to the present invention, one side of the avoiding part may be formed as a groove having a U-shaped or V-shaped cross section. In addition, the electrode assembly may include a positive electrode tab and a negative electrode tab respectively extending from the positive electrode plate and the negative electrode plate, and the protective cover may have a through hole through which the positive electrode tab and the negative electrode tab respectively pass. In this case, the other surface of the protective cover facing the electrode assembly may be formed as a protrusion having a shape in which a cross section matches a shape of one surface of the avoiding portion. Meanwhile, the protective cover has a hexahedron shape having one surface open and has one horizontal surface and four vertical surfaces, and the avoiding part may extend along four vertical surfaces of the protective cover, and the protective cover may have a hexahedron having one surface open. The shape may have one horizontal plane and four vertical planes, and the avoidance portion may extend along an edge between the horizontal plane and the vertical plane.

According to the present invention, even if the case is joined by welding, it is possible to prevent the electrode assembly housed therein from being damaged by heat.

1 is an exploded perspective view of an embodiment of a secondary battery according to the present invention.

2 is a partial cross-sectional view of the embodiment of FIG. 1.

3 is a cross-sectional view of a protective cover of another embodiment of a secondary battery according to the present invention.

4 is a partial cross-sectional view of another embodiment of a secondary battery according to the present invention.

5 is a cross-sectional view of a protective cover of another embodiment of a secondary battery according to the present invention.

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 one embodiment of a secondary battery according to the present invention, and FIG. 2 is a partial cross-sectional view of the embodiment of FIG. 1.

The electrode assembly 110 includes a positive electrode plate 111, a negative electrode plate 112, and a separator 113 interposed between the positive electrode plate 111 and the negative electrode plate 112. In the electrode assembly 110, the positive electrode plate 111, the negative electrode plate 112, and the separator 113 may be wound in the shape of a jelly roll. Unlike the illustrated example, the electrode assembly 110 may have another form such as a stacked type or a folded type.

More specifically, the electrode assembly 110 is positioned between the positive electrode plate 111 coated with the positive electrode active material, the negative electrode plate 112 coated with the negative electrode active material, and the positive electrode plate 111 and the negative electrode plate 112 to prevent a short. The separator 113 may allow the movement of lithium ions only. Here, the positive electrode plate 111 may be an aluminum (Al) foil, the negative electrode plate 112 may be a copper (Cu) foil, and the separator 113 may be polyethylene (PE) or polypropylene (PP), but the present invention is limited to these materials. It doesn't happen. In addition, the positive electrode tab 114 protruding a predetermined length upward may be connected to the positive electrode plate 111, and the negative electrode tab 115 protruding a predetermined length upward may also be connected to the negative electrode plate 112. The positive electrode tab 114 may be made of aluminum (Al) and the negative electrode tab 115 may be made of nickel (Ni), but the present invention is not limited thereto.

The case is divided into two parts, the first part 120 and the second part 130, and these two parts are later joined to each other. In the illustrated example, the first part 120 has an opening at one side thereof. 120a is formed in a substantially rectangular parallelepiped shape, and the second portion 130 is coupled to the opening 120a of the first portion 130.

The first portion 120 of the case is spaced apart from each other by a pair of long sides 121 having a relatively large area, and a pair of short sides having a relatively small area with respect to the pair of long sides 121. A bottom portion 123 is formed at the lower portion of the portion 122, the long side portion 121 and the short side portion 122 perpendicular to these portions.

The first part 120 of the case is manufactured by a deep drawing method, and the long side part 121, the short side part 122, and the bottom part 123 are integrally formed. Here, the first portion 120 may be formed using any one selected from steel, aluminum, or equivalents thereof, but the material of the first portion 120 is not limited thereto.

An electrolyte (not shown) is accommodated together with the electrode assembly 110 in the first portion 120. This electrolyte serves as a moving medium of lithium ions generated by the electrochemical reaction in the positive electrode plate 111 and the negative electrode plate 112 inside the battery 100 during charge and discharge, which is a mixture of lithium salts and high purity organic solvents. It may be a water-based organic electrolyte solution. In addition, the electrolyte may be a polymer using a polymer electrolyte.

The second portion 130 of the case is coupled to the upper portion of the first portion 120 serves to prevent the electrode assembly 110 from escaping to the outside and the electrolyte is not leaked, the upper portion of the first portion 120 Also referred to as cap assembly in that it covers. The cap assembly 130 fits into the opening 120a of the first portion 120 of the case and both are joined to each other by laser welding or the like. The resulting bond line is shown as WL in FIG. 2. The cap assembly 130 is formed by sequentially combining the cap plate 131, the insulating plate 132, and the terminal plate 133.

The cap plate 131 is formed of a metal plate having a size and a shape corresponding to the top opening 120a of the first portion 120, and preferably formed of aluminum or an aluminum alloy. A first terminal hole 131a is formed in the center of the cap plate 131, and an electrolyte injection hole 131b for electrolyte injection is formed at one side. An electrode terminal 134, which will be described later, is inserted into the first terminal hole 131a, and a tubular gasket 135 is interposed for insulation between the electrode terminal 134 and the cap plate 131. The electrolyte injection hole 131b is injected with electrolyte through the electrolyte injection hole 131b after the cap assembly 130 is assembled to the upper opening 120a of the case 110, and the plug 136 after the electrolyte is injected. It is sealed by).

The insulating plate 132 may be formed of an insulating material such as the gasket 135 and may be coupled to the bottom surface of the cap plate 131. The insulation plate 132 extends downward from the edge of the bottom plate 132a and the bottom plate 132a having the through hole 132b formed in a portion corresponding to the first terminal hole 131a of the cap plate 131. And a fixing part 132c. The through hole 132b is inserted with an electrode terminal 134 penetrating through the first terminal hole 131a when the insulating plate 132 and the cap plate 131 are coupled to each other. The fixing part 132c extends to surround both long sides and one short side of the terminal plate 133 so that the terminal plate 133 coupled to the bottom surface does not move relative to the insulating plate 132. The shape of the insulating plate 132 may be variously modified according to the shape of the terminal plate 133.

The terminal plate 133 may be formed of nickel (Ni) or a nickel alloy metal and may be coupled to the lower surface of the insulating plate 132. The terminal plate 133 has a size corresponding to the area of the bottom plate 132a from the first portion 1332 and the first portion 1332 seated on the bottom surface of the bottom plate 132a of the insulating plate 132. It is formed to have a substantially 'T' shape, including a second portion 1331 that extends to have a width greater than the width of the first portion 1332. The second portion 1331 serves to disperse the heat of resistance due to the flow of current that may be concentrated in the first portion 1332.

In the first portion 1332 of the terminal plate 133, a second terminal hole 1334 is formed in a portion corresponding to the through hole 132b of the insulating plate 132. Accordingly, the electrode terminal 134 is electrically connected to the negative electrode tab 115 through the cap plate 131, the insulating plate 132, and the terminal plate 132. The upper portion of the electrode terminal 134 is rotated and pressed by a spinning device (not shown) to be inserted into the first terminal hole 131a, the through hole 132b, and the second terminal hole 1334, and finally the terminal plate 133. ) Is fastened. In this case, when the electrode terminal 134 is fitted into the first terminal hole 131a, the through hole 132b, and the second terminal hole 1334 by rotation and pressure, the electrode terminal 134 may be disposed in the second terminal hole 1334. An end portion of 134 is fastened to the terminal plate 133 while spreading in the peripheral direction of the second terminal hole 1334. The anti-rotation groove 1333 is formed in the peripheral area of the second terminal hole 1334 so that the terminal plate 132 is fixed without being rotated by the electrode terminal 134 spreading in the peripheral direction of the second terminal hole 1334. can do. By making the inner wall of the anti-rotation groove 1333 and the outer circumferential surface of the end of the electrode terminal 134 contact at least one or more points, the contact area between the electrode terminal 134 and the terminal plate 133 is increased to increase the electrode terminal 134. ) And the fixing force between the terminal plate 133 can be improved, and the terminal plate 133 can be prevented from being rotated by the fixing force.

The electrode terminal 134 is inserted into the first terminal hole 131a, the through hole 132b, and the second terminal hole 1334 formed in the cap plate 131, the insulating plate 132, and the terminal plate 133, respectively. The terminal plate 133 is electrically connected to the negative electrode tab 115 of the electrode assembly 110. The electrode terminal 134 is electrically insulated from the cap plate 131 by the gasket 135 when the electrode terminal 134 is inserted into the first terminal hole 131a of the cap plate 131. The electrode terminal 134 is generally formed as a negative electrode terminal, but may be formed in the reverse direction depending on the structure of the secondary battery. That is, the positive electrode tab 114 may be connected to the electrode terminal 134 according to the method of forming the electrode assembly 110.

The insulating case 140 is formed between the electrode assembly 110 and the cap assembly 130 inside the case 120. The insulating case 140 has a positive electrode tab hole 141 and a negative electrode tab hole 142 formed therein, and the positive electrode tab 124 is connected to the cap plate 131 through the positive electrode tab hole 141. The negative electrode tab 125 is connected to the terminal plate 133 through).

The protective cover 200 may be disposed between the insulating case 140 and the case inside the case. As long as the insulating case 140 provides electrical insulation between the electrode assembly 110 and the case including the cap assembly 130, it is possible for the protective cover 200 to perform the functions of the insulating case 140 together. If so, the insulating case 140 may be omitted or integrated into the protective cover 200. The protective cover 200 has a rectangular parallelepiped container shape in which one surface (a reference plane in the drawing direction) is opened, and a part of the electrode assembly 130 is disposed in the protective cover 200 through the opened surface. . In the example of FIG. 1, the protective cover 200 has a cap shape and is disposed to partially cover the electrode assembly 130 and the insulating case 140 from above. In this case, the negative electrode tab through hole 201 and the positive electrode tab through hole 202 may be formed in the protective cover 200 so that the positive electrode tab 114 and the negative electrode tab 115 may pass through the protective cover 200, respectively. have.

The protective cover 200 is made of a heat insulating material, which is to protect the electrode assembly 130, in particular the separator 113 from heat generated when the junction line WL of the case is formed. The protective cover 200 has four corners closest to the junction line WL of the case, that is, the corners of the upper corners are chamfered based on the drawing directions of FIGS. 1 and 2, respectively. The space outside the protective cover 200 formed by the chamfer is hereinafter referred to as the avoidance part 200a. The avoidance part 200a secures an empty space between the protective cover 200 and the junction line WL of the case. The direct contact with both is suppressed as much as possible, thereby making the heat protection effect of the electrode assembly 110 stronger. Meanwhile, in FIG. 1 and FIG. 2, the protective cover 200 is illustrated as a shape having one horizontal plane and four vertical planes extending vertically downward from the horizontal plane, and the shape of the protective cover 200 is necessarily limited thereto. In some cases, the shape may be flat. In any case, the inner surface of the protective cover 200 corresponding to the chamfered edges of the protective cover 200 is formed so as to prevent a difference in the thickness of the protective cover 200 by forming the avoiding part 200. It is desirable to be substantially parallel to the formed surface.

The example of FIG. 3 shows sectional drawing of the example which changed the shape of the protective cover from the example of FIG. 1 and FIG. In this example, the protective cover 210 has a rectangular parallelepiped shape in which one surface (the lower surface in the reference direction) is opened, that is, a shape having one horizontal plane and four vertical planes extending vertically therefrom, as shown in the example of FIG. When the junction line WL is formed closest to WL, for example, as shown in FIG. 2, all four corners of the upper side of the protective cover 200 are recessed toward the electrode assembly 130 to form the avoidance part 210a. . As a result, the avoiding part 210a has a shape of a groove formed along the upper edge of the protective cover 200, and the groove may be a groove having a U-shaped cross section as illustrated. As in the previous example, corresponding to the portion in which the avoidance portion 210a is formed becomes thinner than the other portions, the projection toward the electrode assembly 130 of the avoidance portion 210a has a U-shaped projection, that is, a cross-section U. It is preferable to form a projection having a shape matching with the groove having a shape.

4 illustrates an example in which the positions of the junction line WL and the avoiding part of the case are modified from the examples of FIGS. 1 to 3, respectively. In this example, the second part of the case, that is, the cap assembly 130 has a rectangular parallelepiped shape in which one surface is opened instead of a plate shape, so that the joining line WL is further downward relative to the drawing direction compared to the example of FIG. 2. It is moved and formed. As such, the joint line WL may be formed at various positions as necessary. In this example, the avoiding part 220a of the protective cover 220 may be formed at a position corresponding to the transferred joint line WL. To this end, the protective cover 220 has a shape having a horizontal plane and four vertical planes extending vertically downward from the horizontal plane, and the avoidance unit 220a is formed by being recessed along these four vertical planes and has a U-shaped cross section. It may be provided in the form of an in groove. As in the previous example, the portion in which the avoidance portion 220a is formed becomes thinner than the other portions, so that the projections having the cross-section U-shape are formed on the surface facing the electrode assembly 130 of the avoidance portion 220a. It is preferable.

5 illustrates an example of the protective cover 230 modified from the protective cover 220 of FIG. 4. Here, the protective cover 200 has a shape having one horizontal plane and four vertical planes extending vertically from the horizontal plane as in the example of FIG. 4, and the avoidance part 230a formed along the four vertical planes has a cross-sectional shape. It is a V-shaped groove. Also in this example, in order to ensure a uniform thickness of the protective cover 230, it is preferable to form a projection having a V-shaped cross section on the surface facing the electrode assembly 130 of the portion where the avoidance portion 230a is formed.

In the above description, the case and the protective cover are all illustrated as having a substantially rectangular parallelepiped shape, but may not be a rectangular parallelepiped including a parallelepiped, and may further have other three-dimensional shapes such as cylinders, prisms, and ellipsoids. In addition, even if geometric terms such as hexahedron, cuboid, parallelepiped, right angle, etc. are used, these terms are for convenience of explanation only and are not to be interpreted according to the geometric definition of the terms in a strict sense. It should be interpreted to the extent that it can be seen as such. Similarly, expressions such as vertical and horizontal are only relative expressions based on the direction of the drawings.

Embodiments of the present invention described above and illustrated in the drawings should not be construed as limiting the technical spirit of the present invention. The protection scope of the present invention is limited only by the matters described in the claims, and those skilled in the art can change and change the technical idea of the present invention in various forms. Therefore, such improvements and modifications will fall within the protection scope of the present invention, as will be apparent to those skilled in the art.

Claims

An electrode assembly comprising a positive plate, a negative plate and a separator;

A case accommodating the electrode assembly having a hexahedron shape of which one side is opened;

A cap assembly bonded to one opened surface of the case to seal the electrode assembly to the outside;

A secondary battery comprising a protective cover made of a heat insulating material and disposed between the cap assembly and the electrode assembly in the case, and the corner of the side close to the cap assembly is chamfered to form an avoidance part.
The method of claim 1,

And an inner surface of the chamfered edge of the protective cover is substantially parallel to the chamfered surface.
The method of claim 1,

The electrode assembly includes a positive electrode tab and a negative electrode tab respectively extending from the positive electrode plate and the negative electrode plate,

The protective cover is a secondary battery having a through hole through which the positive electrode tab and the negative electrode tab respectively pass.
An electrode assembly comprising a positive plate, a negative plate and a separator;

A case formed by bonding the first portion and the second portion to each other and sealing against the outside and accommodating the electrode assembly;

A protective cover made of a heat insulating material and disposed between the case and the electrode assembly in the case, wherein an area corresponding to a junction line of the case of one surface facing the case is recessed toward the electrode assembly to form an evacuation part; Secondary battery included.
The method of claim 4, wherein

One side of the avoiding portion is a secondary battery formed of a groove having a U-shaped cross section.
The method of claim 4, wherein

One side of the evacuation unit is a secondary battery formed of a V-shaped groove.
The method of claim 4, wherein

The electrode assembly includes a positive electrode tab and a negative electrode tab respectively extending from the positive electrode plate and the negative electrode plate,

The protective cover is a secondary battery having a through hole through which the positive electrode tab and the negative electrode tab respectively pass.
The method according to any one of claims 4 to 7,

The other surface of the protective cover toward the electrode assembly of the avoiding part is formed of a protrusion having a shape in which a cross section matches a shape of one surface of the avoiding part.
The method according to any one of claims 4 to 7,

The protective cover has a hexahedron shape having one surface opened and has one horizontal surface and four vertical surfaces,

The evacuation unit extends along four vertical surfaces of the protective cover.
The method according to any one of claims 4 to 7,

The protective cover has a hexahedron shape having one surface opened and has one horizontal surface and four vertical surfaces,

The evacuation unit extends along a corner between the horizontal plane and the vertical plane.