KR102164973B1 - Pouch-typed Secondary Battery Comprising Jelly-Roll Electrode Assembly - Google Patents

Abstract

Jelly-roll consisting of a structure wound by means of a separator interposed between a sheet-shaped positive electrode and a sheet-shaped negative electrode to which the electrode active material is applied, and having a circular or elliptical horizontal cross-sectional shape; An open can consisting of a hollow structure in which the first and second surfaces opposing each other are opened, and the jelly-roll is embedded in the hollow part; And a pouch-shaped case made of a laminate sheet including a metal layer and a resin layer, and enclosing and sealing the outer surface of the open can in which the jelly-roll is embedded. It provides a cylindrical secondary battery comprising a.

Description

Pouch-typed Secondary Battery Comprising Jelly-Roll Electrode Assembly}

The present invention relates to a cylindrical secondary battery including a pouch-type case that wraps and seals the outer surface of an open can in which a jelly-roll is embedded.

As technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source is rapidly increasing, and among such secondary batteries, many studies have been conducted on lithium secondary batteries with high energy density and discharge voltage, and have been widely commercialized. Is being used.

When a secondary battery is used as a power source for a mobile phone or laptop, a secondary battery that stably provides a constant output is required, whereas when used as a power source for a power tool such as an electric drill, it vibrates while providing instantaneous high output. There is a need for a secondary battery that can be stable against external physical shocks such as falling, etc.

Depending on the shape of the battery case, secondary batteries are classified into cylindrical and prismatic batteries in which the electrode assembly is embedded in a cylindrical or rectangular metal can, and pouch-type batteries in which the electrode assembly is embedded in a pouch-shaped case of an aluminum laminate sheet. . Among them, cylindrical batteries have the advantages of relatively large capacity and structural stability against external physical shocks, and pouch-type batteries have the advantage of being small in weight compared to capacity, easy shape change, and low manufacturing cost. have.

In addition, the electrode assembly built into the battery case is a power plant capable of charging and discharging consisting of a stacked structure of a positive electrode/separator/cathode, and a jelly-roll type wound with a separator interposed between the positive electrode and the negative electrode of a long sheet type coated with an active material. And, a plurality of anodes and cathodes having a predetermined size are sequentially stacked with a separator interposed therebetween. Among them, the jelly-roll type electrode assembly is easy to manufacture and has the advantage of high energy density per weight.

In this regard, the structure of a conventional cylindrical secondary battery is shown in FIG. 1.

Referring to FIG. 1, the cylindrical secondary battery 100 is a jelly-roll type (wound type) electrode assembly 120 having a structure in which a positive electrode 121, a negative electrode 122, and a separator 123 are sequentially stacked and wound in a round shape. ) Is accommodated in the battery case 130, and after the electrolyte is injected into the battery case 130, the cap assembly 140 having an electrode terminal formed at the open top of the battery case 130 is combined to manufacture.

When manufacturing the cylindrical secondary battery 100 by coupling the cap assembly 140 to the open top of the cylindrical can, the weight of the battery increases due to the many components included in the cap assembly 140. In addition, the process of storing the jelly-roll 120 in the battery case 130 which is a cylindrical can is not easy, and the tension acting on the jelly-roll 120 in the process of storing the jelly-roll 120 in the cylindrical can Due to the uneven distribution, there is a problem that the thickness of the jelly-roll 120 is uneven.

On the other hand, in the case of pouch-type secondary batteries, the mechanical stiffness is low. Moreover, since the pouch-type secondary batteries are all injected into the integrated cell, when each cell is overcharged, the electrolyte inside the cell is decomposed and combustible gas. Occurs inside the cell, and a swelling phenomenon in which the pouch itself swells occurs.

Therefore, there is a high need for a secondary battery capable of solving the problems of the above-described contents.

An object of the present invention is to solve the problems of the prior art and technical problems that have been requested from the past.

After in-depth research and various experiments, the inventors of the present application can maintain the shape of the battery and prevent swelling by embedding the jelly-roll in the hollow part of the open can, as described later. , It was confirmed that the inner space of the secondary battery was secured and the capacity of the battery was increased, as well as the weight of the cylindrical secondary battery can be minimized by enclosing the outer surface of the open can with a built-in jelly-roll with a pouch-type case, The present invention has been completed.

Cylindrical secondary battery according to the present invention for achieving this purpose,

Jelly-roll consisting of a structure wound by means of a separator interposed between a sheet-shaped positive electrode and a sheet-shaped negative electrode to which the electrode active material is applied, and having a circular or elliptical horizontal cross-sectional shape;

An open can consisting of a hollow structure in which the first and second surfaces opposing each other are opened, and the jelly-roll is embedded in the hollow part; And

A pouch-shaped case made of a laminate sheet including a metal layer and a resin layer, and enclosing the outer surface of an open can in which a jelly-roll is embedded;

It consists of a structure including.

In the cylindrical secondary battery of the present invention, the open can can be manufactured by a simple process. For example, the open can is manufactured in a tube shape through extrusion molding, or the metal plate is bent to surround the outer surface of the jelly-roll. After that, it can be manufactured by bonding or welding the ends.

In one specific example, the length between the first side and the second side of the open can is less than the length between the first end and the second end of the jelly-roll facing each of the first side and the second side of the open can It can be made of a relatively long structure.

In the above structure, by the difference in length of the open can and the jelly-roll, between the first side of the open can and the first end of the jelly-roll, and between the second side of the open can and the second end of the jelly-roll There may be separations in each longitudinal direction.

Specifically, the separation length between the first side of the open can and the first end of the jelly-roll and the separation length between the second side of the open can and the second end of the jelly-roll are, for example, first It may range from 1% to 10% of the length between the side and the second side.

If the length of the open can outside the above range is shorter than or equal to the length of the jelly-roll, the first end or the second end of the jelly-roll is exposed to the outside of the open can, thereby swelling the jelly-roll The phenomenon cannot be effectively suppressed, and it can become vulnerable from external shocks. On the other hand, when the separation length is too large, unnecessary space is occupied inside the open can, and thus the efficiency of the battery may be degraded.

These open cans may be made of various materials, and preferably, stainless steel, aluminum, and nickel-plated mild steel having high mechanical rigidity may be preferably used in order to secure stability against external physical impact. .

In addition, the open can may have a structure having a uniform thickness and cross-sectional area on a vertical cross-section in the longitudinal direction.

The pouch-type case may have a structure surrounding the outer surface of the open can while being in close contact with the first and second surfaces of the open can.

A device including a conventional cylindrical secondary battery required an internal space equal to the total length including the cylindrical can in which the jelly-roll is accommodated and the cap assembly coupled to the top thereof, so that the battery capacity is reduced as much as the space occupied by the cap assembly. There was a downside to being.

On the other hand, the cylindrical secondary battery according to the present invention has a structure in which the open can in which the jelly-roll is embedded is sealed with a pouch-shaped case without using such a cap assembly. Since the sealing portion formed in the sealing process can be bent in a state in close contact with the first or second surface of the open can, the internal space occupied by the conventional cap assembly can be reduced. That is, by reducing the internal space as described above, the battery capacity per volume of the battery can be increased.

In one specific example, the first electrode tab and the second electrode tab of the jelly-roll may have a structure protruding toward the first and second surfaces of the open can, respectively. In some cases, a structure in which the first electrode tab and the second electrode tab of the jelly-roll protrude side by side toward the first surface or the second surface of the open can may be possible.

In one specific example, the pouch-shaped case is made of a tube of a laminate sheet, and has a structure in which a first sealing part and a second sealing part are formed at regions corresponding to the first and second surfaces of the open can, respectively. I can.

In a cylindrical secondary battery having such a structure, each of the sealing parts may function as a safety vent for discharging gas generated inside the battery.

The first sealing portion and the second sealing portion may have a structure in which both ends of a tube are heat-sealed and sealed, respectively.

Specifically, the first sealing part and the second sealing part may have a structure in which the first electrode tab and the second electrode tab of the jelly-roll protrude, and the heat-sealing width is formed in the radial direction of the tube. .

Cylindrical secondary batteries having such a structure block the penetration of moisture from the outside through a safety vent that forms a cap assembly in a conventional cylindrical secondary battery, an upper cap connected thereto, and a gasket mounted on the outer peripheral surface of the upper cap. Functions such as preventing electrolyte leakage can be performed instead.

In addition, in the conventional cap assembly, the previously described functions were performed by a mechanical sealing method by a crimping process.This sealing method is not only difficult to apply to a miniaturized cylindrical secondary battery, and even if applied, there is a problem in the sealing area. There was a fear of occurrence, but the cylindrical secondary battery according to the present invention having a sealing portion structure is suitable for miniaturization and thus these problems can be solved.

Moreover, the conventional cylindrical secondary battery has a structure in which the positive electrode tab bonded to the positive electrode is connected to the cap assembly, and the negative electrode tab bonded to the negative electrode is connected to the lower end of the can, so that a significant dead space around the connection part is Therefore, if an external impact is repeatedly applied, the jelly-roll may rotate locally, and when the jelly-roll rotates, damage to the cap assembly and the electrode tab attached to the inner surface of the cylindrical can There was a problem that occurred.

On the other hand, according to the present invention, since the first electrode tab and the second electrode tab are fixed in position by the first sealing part and the second sealing part, the above-described phenomenon can be prevented.

In addition, when the internal pressure of the cylindrical secondary battery increases, at least one of the first sealing unit and the second sealing unit may be opened and high-pressure gas may be discharged.

This is different from a structure in which high-pressure gas is discharged while the safety vent of the cap assembly is ruptured when the pressure inside the battery increases in the conventional cylindrical secondary battery.

In the same structure as the present invention, the first sealing part, the second sealing part, or the first sealing part and the second sealing part may be opened, and in particular, when the first sealing part and the second sealing part are opened at the same time, the conventional Unlike the cylindrical secondary battery of, high-pressure gas can be discharged in both directions.

Specifically, in the conventional cylindrical secondary battery, safety vents are formed only in one direction, so that while high-pressure gas is discharged, there is a problem that a driving force is generated in the jelly-roll, so that safety cannot be guaranteed. This problem can be solved because the flow of the jelly-roll can be suppressed by discharging the high-pressure gas in the direction.

In one specific example, an insulating film may be interposed at an interface between the first electrode tab and the first sealing unit and an interface between the second electrode tab and the second sealing unit.

With this structure, sealing properties between the first electrode tab and the second electrode tab and the pouch-shaped case can be improved, and an electrical insulation state can be secured at the same time.

The present invention also provides a method of manufacturing the cylindrical secondary battery.

The manufacturing method of the cylindrical secondary battery,

(a) preparing a jelly-roll by winding up with a separator interposed between a positive electrode sheet and a negative electrode sheet to which the active material is respectively applied;

(b) inserting the jelly-roll into the hollow of the open can; And

(c) inserting the open can in which the jelly-roll is inserted into the pouch-shaped case, and then sealing the pouch-shaped case with the electrode tabs of the jelly-roll exposed;

Includes.

In the process (c), after sealing one end of the pouch-type case, an electrolyte solution is injected, and a process of activating by applying a voltage to the jelly-roll may be further included, and after the activation, the other side of the pouch-type case The ends can be sealed.

Since the cylindrical secondary battery according to the present invention has a high capacity compared to the weight, it can be applied to a high-power, high-capacity battery pack, which has a high need in recent years, and also, as described above, because it has a structure suitable for miniaturization, it can be applied to an ultra-small battery pack.

Accordingly, the present invention provides a battery pack including the cylindrical secondary battery in one or more pack cases, and a device including the battery pack as a power source.

The device is selected from, for example, a mobile phone, a wearable electronic device, a portable computer, a smart pad, a Netbug Light Electronic Vehicle (LEV), an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, and a power storage device. Can be.

Since the structure of these battery packs and devices and a method of manufacturing the same are known in the art, detailed descriptions thereof are omitted herein.

As described above, in the cylindrical secondary battery according to the present invention, the shape of the battery is changed by embedding a jelly-roll in the hollow part of the open can made of a hollow structure in which the first and second surfaces facing each other are opened, respectively. The inner space of the secondary battery is secured by sealing the outer surface of the open can with a built-in jelly-roll and sealing it with a pouch-shaped case to increase the battery capacity per volume of the battery, and to increase the battery capacity per volume of the battery. It provides a lightweight cylindrical secondary battery by minimizing the weight of the secondary battery.

1 is a vertical cross-sectional perspective view of a conventional cylindrical secondary battery;
2 is a schematic diagram showing a process of inserting a jelly-roll into a hollow portion of an open can according to an embodiment of the present invention;
3 is a schematic diagram showing a process of inserting an open can with a built-in jelly-roll obtained in the process of FIG. 2 into a pouch-shaped case;
4 is a schematic diagram schematically showing a cylindrical secondary battery in a state in which the pouch-shaped case is sealed after the process of FIG. 3; And
5 is an enlarged view as viewed from one side adjacent to the heat fusion width of the first sealing portion.

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

FIG. 2 is a schematic diagram showing a process of inserting a jelly-roll into the hollow part of an open can according to an embodiment of the present invention, and FIGS. 3 and 4 contain a jelly-roll obtained in the process of FIG. A schematic diagram showing a process of sealing the opened open can by inserting it into a pouch-shaped case is shown.

2, 3, and 4 together, the jelly-roll 200 is inserted through the open first side 211 of the open can 210, and is not shown in FIG. It may also be inserted into the open can 210 through the two sides 212.

The method of embedding the jelly-roll 200 in the hollow part of the open can 210 is not only a method of inserting the jelly-roll 200 into the open can 210 already manufactured as described above, but also a jelly-roll After placing the jelly-roll 200 on a metal plate (not shown) in which the electrode tabs of 200 are spread parallel to the protruding direction, the metal plate is rounded to surround the outer surface of the jelly-roll 200 It is also possible to incorporate or weld the ends of the metal plates after bending, thereby embedding them in the open can 210.

The length between the first end 201 and the second end 202 of the jelly-roll 200 is d, and the length between the first side 211 and the second side 212 of the open can 210 is d When', d'is relatively longer than d, and when the jelly-roll 200 is embedded in the open can 210, there is a distance equal to the difference in length between d and d'.

The distance between the first end 201 of the jelly-roll 200 and the first side 211 of the open can 210 and the second end 202 of the jelly-roll 200 and the open can 210 The separation length between the second sides 212 of each has a value in the range of 1% to 10% of d'. However, the separation length is not limited to a value within the above range.

The first electrode tab 203 and the second electrode tab 204 protrude toward the first surface 201 and the second surface 202 of the jelly-roll 200, respectively.

Since the first electrode tab 203 and the second electrode tab 204 are formed in a position where there is no fear of contacting, it is possible to prevent a problem such as a short circuit due to contact between the electrode tabs 203 and 204. have.

5 is an enlarged view as viewed from one side adjacent to the heat fusion width of the first sealing portion.

Referring to FIGS. 4 and 5 together, the pouch-shaped case 230 is made of a laminate sheet, and is provided at positions corresponding to the protruding portions of the first electrode tab 203 and the second electrode tab 204. A first sealing part 231 and a second sealing part 232 are formed.

When viewed from the side surface 300A adjacent to the heat fusion width of the first sealing portion 231, the pouch-shaped case 230 is in close contact with the first surface 201 of the open can 210, It surrounds the outer surface of the open can 210.

The first sealing part 231 can be bent in a state in close contact with the first surface 211 of the open can, and the length of the first sealing part 231 and the length of the first electrode tab 203 are summed. It is possible to secure as much internal space as H.

When the internal pressure of the first sealing part 231 and the second sealing part 232 is increased, at least one sealing part is opened to discharge the high-pressure gas to secure the safety of the secondary battery. I can.

Those of ordinary skill in the field to which the present invention belongs will be able to perform various applications and modifications within the scope of the present invention based on the above contents.

Claims (18)

Jelly-roll consisting of a structure wound by means of a separator interposed between a sheet-shaped positive electrode and a sheet-shaped negative electrode to which the electrode active material is applied, respectively, and having a circular or elliptical horizontal cross-sectional shape;
An open can consisting of a hollow structure in which the first and second surfaces opposing each other are opened, and the jelly-roll is embedded in the hollow part; And
A pouch-shaped case made of a laminate sheet including a metal layer and a resin layer, and enclosing the outer surface of an open can in which a jelly-roll is embedded;
Including ,
The length between the first side and the second side of the open can is relatively longer than the length between the first end and the second end of the jelly-roll facing each of the first side and the second side of the open can,
Due to the difference in length between the open can and the jelly-roll, a gap exists between the first side of the open can and the first end of the jelly-roll, and between the second side of the open can and the second end of the jelly-roll. And
A cylindrical secondary battery, characterized in that the pouch-type case is bent and sealed in a state in which the pouch-type case is in close contact parallel to the open first and second surfaces without using a cap assembly . delete delete The method of claim 1 , wherein the distance between the first side of the open can and the first end of the jelly-roll and the distance between the second side of the open can and the second end of the jelly-roll are each of the first side and Cylindrical secondary battery, characterized in that the range of 1% to 10% of the length between the second side. The cylindrical secondary battery according to claim 1, wherein the open can is made of stainless steel, aluminum, and nickel-plated mild steel. The cylindrical secondary battery according to claim 1, wherein the open can has a uniform thickness and a cross-sectional area on a vertical cross-section in a longitudinal direction. The cylindrical secondary battery according to claim 1, wherein the pouch-type case surrounds the outer surface of the open can in a state in close contact with the first and second surfaces of the open can. The cylindrical secondary battery of claim 1, wherein the first electrode tab and the second electrode tab of the jelly-roll protrude toward the first and second surfaces of the open can, respectively. The method of claim 1, wherein the pouch-shaped case is made of a tube of a laminate sheet, and a first sealing portion and a second sealing portion are formed at portions corresponding to the first and second surfaces of the open can, respectively. Cylindrical secondary battery. The cylindrical secondary battery according to claim 9, wherein the first sealing part and the second sealing part have a structure in which both ends of the tube are heat-sealed and sealed, respectively. The structure of claim 10, wherein the first sealing part and the second sealing part are formed in a state in which the first electrode tab and the second electrode tab of the jelly-roll protrude, and the heat-sealing width is formed in the radial direction of the tube. Cylindrical secondary battery, characterized in that made. The cylindrical secondary battery according to claim 9, wherein when the internal pressure of the battery is increased, the high-pressure gas is discharged while at least one of the first sealing part and the second sealing part is opened. The cylindrical secondary battery according to claim 11, wherein an insulating film is interposed at an interface between the first electrode tab and the first sealing unit and an interface between the second electrode tab and the second sealing unit. As a method of manufacturing a cylindrical secondary battery according to any one of claims 1 and 4 to 13,
(a) preparing a jelly-roll by winding up with a separator interposed between a positive electrode sheet and a negative electrode sheet to which the active material is respectively applied;
(b) inserting the jelly-roll into the hollow of the open can; And
(c) inserting the open can in which the jelly-roll is inserted into the pouch-shaped case, and then sealing the pouch-shaped case with the electrode tabs of the jelly-roll exposed;
Cylindrical secondary battery manufacturing method comprising a. The cylindrical secondary according to claim 14, wherein in the step (c), an electrolyte is injected after sealing one end of the pouch-shaped case, and the process of activating by applying a voltage to the jelly-roll is further included. Battery manufacturing method. The method of claim 15, wherein the other end of the pouch-shaped case is sealed after the activation. A battery pack comprising at least one cylindrical secondary battery according to any one of claims 1 and 4 to 13. A device comprising the battery pack according to claim 17.

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