KR20100128679A - Secondary battery having a plastic-bag, and manufacturing the same - Google Patents

Abstract

PURPOSE: A method for manufacturing a secondary battery with a plastic-bag is provided to improve sealability of a sealing part and to increase the safety of the secondary battery. CONSTITUTION: A secondary battery is manufactured by sealing an electrode assembly laminated with a positive electrode, a separation film and a negative electrode, in a battery case. A method for manufacturing the secondary battery comprises the steps of: (i) putting an electrode assembly in a plastic bag in which the electrolyte inlet is included; (ii) injecting the electrolyte in the plastic bag through the electrolyte inlet; (iii) sealing the part excluding a degassing side when the plastic bag is installed in a battery case receiving portion; (iv) activating a battery and removing the gas; and (v) sealing the degassing side.

Description

Secondary battery having a plastic bag and a method of manufacturing the same {SECONDARY BATTERY HAVING A PLASTIC-BAG, AND MANUFACTURING THE SAME}

The present invention relates to a secondary battery and a method for manufacturing the same, and more particularly, to a secondary battery and a method for manufacturing the same, which can prevent incomplete sealing due to electrolyte leakage during the process.

Secondary batteries are classified according to the structure of the electrode assembly having a positive electrode / membrane / cathode structure. Typically, a long sheet-shaped positive electrode and negative electrode are wound with a separator interposed therein. (Winding type) electrode assembly, a stack (stacked type) electrode assembly in which a plurality of positive and negative electrodes cut in units of a predetermined size are sequentially stacked with a separator, and a positive and negative electrodes of a predetermined unit are separated through a separator And a stack / foldable electrode assembly having a structure in which bi-cell or full cells are stacked.

Recently, a battery having a structure in which a stacked or stacked / folding electrode assembly is incorporated in a battery case of an aluminum laminate sheet has attracted a lot of attention due to its low manufacturing cost, small weight, and easy shape deformation, and its usage amount. This is increasing gradually.

1 schematically illustrates a general structure of a conventional representative secondary battery as an exploded perspective view.

Referring to FIG. 1, the secondary battery 10 may include an electrode assembly 30, electrode tabs 31 and 32 extending from the electrode assembly 30, and electrode leads welded to the electrode tabs 31 and 32. 40 and 41, and a battery case 20 for accommodating the electrode assembly 30.

The electrode assembly 30 is a power generator in which a positive electrode and a negative electrode are sequentially stacked in a state where a separator is interposed therebetween, and has a stack type or a stack / fold type structure. The electrode tabs 31, 32 extend from each pole plate of the electrode assembly 30, and the electrode leads 40, 41 are welded, for example, with a plurality of electrode tabs 31, 32 extending from each pole plate. Each is electrically connected to each other, and part of the battery case 20 is exposed to the outside. In addition, an insulating film 50 is attached to upper and lower portions of the electrode leads 40 and 41 to increase the sealing degree with the battery case 20 and at the same time to secure an electrical insulation state.

The battery case 20 includes a case body 22 including a recess 23 having a concave shape in which the electrode assembly 30 can be seated, and a cover 21 integrally connected to the body 22. The battery is completed by adhering both sides 24 and the upper end 25, which are the contact portions, in the state in which the electrode assembly 30 is accommodated in the accommodating portion 23. The battery case 20 is formed of an aluminum laminate structure of a resin layer, a metal foil layer, and a resin layer, and applies heat and pressure to both side portions 24 and the upper end portion 25 of the cover 21 and the main body 22 which are in contact with each other. The resin layer is bonded by fusion bonding. Both sides 24 are in direct contact with the same resin layer of the upper and lower battery cases 20, so that uniform sealing is possible by melting. On the other hand, since the electrode leads 40 and 41 protrude from the upper end 25, the electrode leads 40 may be improved in consideration of the thickness of the electrode leads 40 and 41 and heterogeneity with the material of the battery case 20. The heat-sealing is carried out in the state which interposed the insulating film 50 between 40 and 41. FIG.

In the conventional method of manufacturing a battery, an electrolyte solution is typically injected in a process of accommodating an electrode assembly in a laminate sheet and heat fusion. In other words, the electrode assembly is accommodated in a laminate sheet, and after the electrolyte is injected, it is thermally fused to finally manufacture a battery.

However, many problems may occur in the process of thermal fusion after the injection of the electrolyte. Since the electrolyte is a liquid, the electrolyte may be in contact with the heat-sealing portion (ie, the sealing surface). In this case, the sealing may be incompletely caused by the electrolyte and may adversely affect the safety of the battery. In particular, the repeated expansion and contraction of the battery body is repeated during repeated charging and discharging of the battery, and this incompletely sealed portion is very easily separated in this process.

In addition, when the electrolyte is in contact with the sealing surface, there is a problem that the internal electrode assembly is not completely insulated with respect to the outside, which may also adversely affect the safety of the battery.

Therefore, there is a demand for a method of manufacturing a battery that can improve the sealing property of the battery while simplifying the process. Accordingly, the present invention is to solve the above problems of the prior art by using a method of primary injection of the electrolyte into the plastic bag.

The present invention has been made to solve the above problems of the prior art,

In the method of manufacturing a secondary battery is prepared by sealing an electrode assembly formed by stacking a positive electrode, a separator, and a negative electrode in a battery case,

(a) placing the electrode assembly in a plastic bag equipped with an electrolyte injection hole;

(b) injecting electrolyte into the plastic bag through the electrolyte injection hole;

(c) first sealing the remaining portions except the degassing surface while the plastic bag is mounted in the battery case accommodating part;

(d) a degassing step of activating the cell and removing the generated gas; And

(e) sealing the degassing surface

It provides a secondary battery manufacturing method comprising a.

In another aspect, the present invention provides a method for manufacturing a secondary battery, characterized in that the plastic bag is mounted to the battery case accommodating portion so that the electrolyte injection hole of the plastic bag is located in a different direction from the degassing surface.

In another aspect, the present invention provides a method for manufacturing a secondary battery, characterized in that the plastic bag is mounted to the battery case housing so that the electrolyte injection port of the plastic bag is located in the opposite direction to the degassing surface.

In addition, in the present invention, the plastic bag provides a method for producing a secondary battery, characterized in that the polyethylene terephthalate (PET) material.

It also provides a secondary battery, characterized in that produced by the method of the present invention.

Also,

An electrode assembly formed by stacking an anode, a separator, and a cathode;

A plastic bag surrounding the electrode assembly;

An electrolyte injected into the plastic bag; And

Provided is a secondary battery including the electrode assembly, the plastic bag, and a battery case accommodating the electrolyte.

The secondary battery manufacturing method according to the present invention is easy to process, it is possible to further improve the sealing property of the sealing portion, thereby increasing the safety of the secondary battery accordingly.

Hereinafter, the present invention will be described in detail.

The present invention,

In the method of manufacturing a secondary battery is prepared by sealing an electrode assembly formed by stacking a positive electrode, a separator, and a negative electrode in a battery case,

(a) placing the electrode assembly in a plastic bag equipped with an electrolyte injection hole;

(b) injecting electrolyte into the plastic bag through the electrolyte injection hole;

(c) first sealing the remaining portions except the degassing surface while the plastic bag is mounted in the battery case accommodating part;

(d) a degassing step of activating the cell and removing the generated gas; And

(e) sealing the degassing surface

It relates to a secondary battery manufacturing method comprising a.

In the present invention, the material of the plastic bag may be used without particular limitation as long as it is made of a material that is stable in electrolyte and electrically insulating. Examples of such plastic materials include polyethylene terephthalate (PET).

The plastic bag is provided with an electrolyte injection hole. It is preferable to mount the plastic bag in the battery case accommodating part so that the electrolyte injection hole of the plastic bag is located in a direction different from that of the degassing surface, so as to mitigate electrolyte leakage in the degassing step. In particular, it is more preferable to mount the plastic bag in the battery case accommodating part so that the electrolyte injection hole of the plastic bag is located in the opposite direction to the degassing surface.

The degassing surface refers to an unsealed portion formed for the purpose of degassing. The battery is manufactured and has an initial charging and discharging process, which is called an activation process of the battery. Gas is usually generated during the activation process, which is called degassing.

In addition, the present invention,

An electrode assembly formed by stacking an anode, a separator, and a cathode;

A plastic bag surrounding the electrode assembly;

An electrolyte injected into the plastic bag; And

It relates to a secondary battery including the electrode assembly, the plastic bag, and a battery case for receiving the electrolyte.

The secondary battery of the present invention may be manufactured according to the manufacturing method of the present invention, but is not limited thereto.

Hereinafter, the manufacturing method of the present invention will be described with reference to the drawings, but this is for easier understanding of the present invention, and the scope of the present invention is not limited thereto.

2A to 2E show a series of schematic diagrams of a manufacturing process of a battery.

First, referring to FIG. 2A, an electrode assembly formed by stacking an anode, a separator, and a cathode is placed in an insulating PET plastic bag, and an electrode assembly 200 stacked in a plastic bag is placed in the plastic bag through an electrolyte injection hole. Make.

Referring to FIG. 2B, the sheet-shaped battery case 100 formed of an aluminum laminate sheet has an electrode assembly accommodating part 110 formed at a lower end thereof on a virtual horizontal center line X in a drawing process. The accommodating part 110 has a size that substantially corresponds to the shape of the electrode assembly 200 stacked on the plastic bag.

In the state in which the electrode assembly 200 stacked on the plastic bag is mounted on the accommodating part 110, the remaining outer peripheral parts 114, 116, and 118 except for the bent part 112 of the virtual horizontal center line X are ultimately formed. Sealing is performed by thermal fusion.

After attaching the electrode assembly 200 stacked on the plastic bag to the accommodating part 110, the battery case 100 is bent along the virtual horizontal center line X to cover the accommodating part 110, as shown in FIG. 2C. The structure is obtained, and sealing is performed by heat fusion except for one side degassing surface 118 of the outer peripheral surface portions 114, 116, 118.

The degassing surface 118 remains unsealed, through which a degassing process is performed. The degassing surface 118 includes a surplus portion 120 having a larger width than the other outer circumferential portions 114 and 116, and this surplus portion 120 is useful in the process of activating the battery as described in FIG. 2D. Used.

Referring to FIG. 2D, an end portion 122 of the excess portion 120 is sealed by heat fusion, and an activation process of charging and discharging the battery is performed. The activation process of the battery is performed for the purpose of forming a protective film by the electrolyte solution on the surface of the electrode (particularly the negative electrode) to suppress the decomposition reaction of the electrolyte solution in the finished battery, and a large amount of gas is generated in this process.

The generated gas is collected in the surplus portion 120 through the degassing surface 118, and after the activation process, the surplus portion 120 is cut along the virtual vertical center line Y to discharge the gas.

Then, as in FIG. 2E, the secondary battery is completed by heat sealing the degassing surface 118.

3 schematically shows a structure of a lithium secondary battery having a plastic bag according to an embodiment of the present invention.

Hereinafter, according to the manufacturing method of the present invention, a battery was prepared as follows.

Example  One

The electrode assembly formed by stacking the positive electrode, the separator, and the negative electrode was placed in an insulating PET plastic bag, and the electrolyte was put into the plastic bag through an electrolyte injection hole to make an electrode assembly stacked on the plastic bag.

The electrode assembly stacked on the plastic bag was mounted on the battery case so that the electrolyte injection hole of the plastic bag was positioned on the degassing surface.

The outer peripheral surface portions except for the bent portion and the degassed surface of the aluminum pouch were sealed by heat fusion.

Thereafter, the battery was charged and discharged to activate the degassing process, and the degassing surface was heat-sealed to finally manufacture a battery.

Example  2

In Example 1, a battery was manufactured in the same manner as in Example 1, except that the electrode assembly stacked on the plastic bag was installed in the battery case such that the electrolyte injection hole of the plastic bag was positioned in the opposite direction to the degassing surface.

Comparative example

The electrode assembly formed by stacking the positive electrode, the separator, and the negative electrode was mounted in a battery case pre-formed by a drawing process.

The outer peripheral surface portions except for the bent portion and the degassed surface of the aluminum pouch were sealed by heat fusion. At this time, the electrolyte was injected through the unsealed degassing surface.

Thereafter, the battery was charged and discharged to activate the degassing process, and the degassing surface was heat-sealed to finally manufacture a battery.

According to the comparative examples and examples, each of 10 batteries were manufactured and tested for sealing damage by the following method.

* Sealing part Damage  Test

Using a resistance meter (HIOKi) on a cell completed until the degassing process, the positive terminal of the resistance meter is contacted with a negative lead, and the negative terminal is connected to a pouch of aluminum (Al). The resistance value was measured by contacting the exposed part to determine whether the seal was damaged. Less than 100 mW was considered to be damaged and more than 100 mW were considered to be intact.

Test results are shown in Table 1 below.

Sealing Damage Example 1 1/10 Slashing Example 2 0/10 Comparative example 4/10

According to the manufacturing method according to the present invention as shown in Table 1 it can be seen that the sealing damage is significantly reduced. However, when the degassing surface and the surface of the electrolyte injection hole are the same, the electrolyte solution is relatively easy to be exposed during the degassing process as compared with the case where the degassing surface is the same.

Although described above with reference to embodiments and drawings of the present invention, those skilled in the art to which the present invention pertains will be able to perform various applications and modifications within the scope of the present invention based on the above contents.

1 is a perspective view of a general structure of a typical representative secondary battery.

2a to 2e is a series of schematic diagrams for the secondary battery manufacturing method of the present invention.

3 is a structural diagram of a secondary battery according to an embodiment of the present invention.

Explanation of the Main References

100: battery case 110: storage

118: degassing side 120: surplus part

200: electrode assembly stacked in a plastic bag

Claims (7)

In the method of manufacturing a secondary battery is prepared by sealing an electrode assembly formed by stacking a positive electrode, a separator, and a negative electrode in a battery case, (a) placing the electrode assembly in a plastic bag equipped with an electrolyte injection hole; (b) injecting electrolyte into the plastic bag through the electrolyte injection hole; (c) first sealing the remaining portions except the degassing surface while the plastic bag is mounted in the battery case accommodating part; (d) a degassing step of activating the cell and removing the generated gas; And (e) sealing the degassing surface Method of manufacturing a secondary battery comprising a. The method of claim 1, wherein the plastic bag is mounted on the battery case accommodating part so that the electrolyte injection hole of the plastic bag is located in a direction different from that of the degassing surface. The method of claim 1, wherein the plastic bag is mounted on the battery case accommodating part so that the electrolyte injection hole of the plastic bag is located in a direction opposite to the degassing surface. The method of claim 1, wherein the plastic bag is made of polyethylene terephthalate (PET). A secondary battery produced by the method of any one of claims 1 to 4. An electrode assembly formed by stacking an anode, a separator, and a cathode; A plastic bag surrounding the electrode assembly and having an electrolyte injection hole; An electrolyte injected into the plastic bag through an electrolyte injection hole; And Secondary battery comprising a battery case for storing the electrode assembly stacked on the plastic bag in which the electrolyte is injected. According to claim 6, wherein the plastic bag is a secondary battery, characterized in that the polyethylene terephthalate (PET) material.

Images