KR20180072934A - Process for Preparation of Pouch-typed Battery Cell Using Member for Preventing Electrolyte Leakage - Google Patents

Abstract

The present invention relates to a method for manufacturing a battery cell in which an electrode assembly and an electrolyte are embedded in a storage portion formed in a battery case of a laminate sheet, comprising the following steps of: (a) mounting an electrode assembly to a storage portion of a battery case, injecting an electrolyte, and forming a gas collection portion on one side of an outer peripheral sealing portion; (b) mounting a member for preventing electrolyte discharge in a boundary part in the gas collection portion adjacent to the storage portion; (c) activating the electrode assembly by performing charging and discharging; (d) discharging gas generated inside the battery case by perforating at least one through-hole in the gas collection portion; and (e) cutting and removing the gas collection portion including the member for preventing electrolyte discharge after discharging gas through the through-hole in the step (d).

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of manufacturing a battery cell using an electrolyte discharge preventing member,

The present invention relates to a method of manufacturing a battery cell using a member for preventing electrolyte discharge.

As technology development and demand for mobile devices are increasing, the demand for secondary batteries as energy sources is rapidly increasing. Among such secondary batteries, many studies have been made on lithium secondary batteries having high energy density and discharge voltage, It has been commercialized and widely used.

Generally, a lithium secondary battery includes an electrode assembly composed of a cathode, a cathode, and a separator interposed between the anode and the cathode, and the electrolyte is injected or impregnated after the electrode assembly is placed in a battery case of a metal can or a laminate sheet Consists of.

In recent years, due to the high capacity of the battery, a large-sized case and a thin material have been attracting much attention. Accordingly, a stacked or stacked / folded type electrode assembly is embedded in a pouch-shaped battery case of an aluminum laminate sheet. The pouch-type battery is gradually increasing in use due to low manufacturing cost, small weight, and easy shape deformation.

FIG. 1 schematically shows a general structure of a typical conventional pouch-type secondary battery as an exploded perspective view.

1, the pouch type secondary battery 10 includes an electrode assembly 30, electrode leads 60 and 70 welded to electrode taps 40 and 50 extending from the electrode assembly 30, And a battery case 20 for accommodating the electrode assembly 30.

The electrode assembly 30 is a power generation element in which an anode (not shown) and a cathode (not shown) are sequentially stacked with a separation membrane interposed therebetween. The power generation element has a stacked or stacked / folded structure.

The electrode tabs 40 and 50 extend from each electrode plate of the electrode assembly 30 and the electrode leads 60 and 70 have a plurality of electrode tabs 40 and 50 extending from each electrode plate, Respectively, and are partially exposed to the outside of the battery case 20. An insulating film 80 is attached to a portion of the upper and lower surfaces of the electrode leads 60 and 70 in order to increase the degree of sealing with the battery case 20 and at the same time to secure an electrically insulated state.

The battery case 20 is made of an aluminum laminate sheet including a resin layer and a metal layer, and provides a space for accommodating the electrode assembly 30, and has a pouch shape as a whole.

Generally, the lithium secondary battery is activated during the manufacturing process of the battery, and the activation process is performed by applying a current to a predetermined voltage to the electrode assembly impregnated with the electrolyte. During the initial charge and discharge process, a protective coating is formed on the surface of the electrode, and a part of the electrolyte is decomposed to generate a large amount of gas. Therefore, the battery assembly is completed through the degassing process for removing the generated gas to produce the finished product.

However, such a degassing process is performed under a predetermined vacuum and pressure, and due to a sudden change in pressure, some of the electrolyte in the battery cell is discharged together with the gas, so that contamination by the electrolyte occurs, The residual amount of the electrolytic solution is reduced due to the discharge, and an excessive amount of the electrolytic solution is injected in order to solve the problem.

In order to solve this problem, the present applicant has proposed a technique disclosed in Korean Patent Application Laid-open No. 10-2016-005424, but the auxiliary sealing portion included in the above description only functions when the electrode assembly is uprighted with the electrode terminal facing upward There is a risk that the electrolytic solution can still be discharged through the portion where the auxiliary sealing portion is not formed.

Therefore, there is a high need for a technology that can fundamentally solve these problems.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and the technical problems required from the past.

More specifically, it is an object of the present invention to provide a battery capable of preventing the over discharge of the electrolyte generated in the degassing process by mounting a member for preventing the discharge of electrolyte to the inside of the battery cell and the portion contacting the gas collecting portion, Cell.

In order to achieve the above object, the present invention provides a battery cell in which an electrode assembly and an electrolyte are embedded in a housing portion formed in a battery case of a laminate sheet,

(a) a process of attaching an electrode assembly to a storage portion of a battery case, injecting an electrolyte, and forming a gas trapping portion at one side of the outer peripheral sealing portion;

(b) a step of mounting an electrolyte discharge preventing member on a boundary portion in a gas trapping portion adjacent to the storage portion;

(c) activating the electrode assembly by performing charging and discharging;

(d) discharging the gas generated in the battery case by puncturing at least one through-hole in the gas collecting part; And

(e) cutting out the gas collecting part including the electrolyte injection preventing member after discharging the gas through the through hole in the step (d), and removing the gas collecting part;

.

Therefore, in the battery cell manufactured by the manufacturing method according to the present invention, the electrolyte discharge preventing member is attached to the boundary portion in the gas collecting portion adjacent to the storage portion of the battery case to discharge the gas generated in the activation process to the outside, It is not necessary to inject an excessive amount of the electrolytic solution and it is possible to secure a sufficient amount of electrolytic solution in the battery cell.

Specifically, in the step (a)

(a1) preparing a laminated sheet having a receiving portion having a shape corresponding to the electrode assembly;

(a2) attaching the electrode assembly to the housing part, and then thermally fusing the outer periphery of the laminate sheet except for one side where the gas collecting part is to be positioned, thereby forming a sealing part; And

(a3) injecting an electrolytic solution through the one side of the unsealed state;

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After the step (b), the open end of the gas collecting part may be sealed by thermal welding.

And further performing a clamping and baking process of adjusting the thickness of the battery cell by applying heat and pressure after the process (c) or the process (d).

Conventionally, there has been a problem that the performance of the battery is reduced due to the fact that gas generated during the activation process can not be sufficiently removed due to over discharge of the electrolyte, and some gas remains in the storage portion of the battery cell.

Therefore, the electrolyte injection preventing member may be composed of a nanofilter having a pore size that allows the gas phase component to pass through and the liquid component to pass through, so as to block or reduce the discharge of the electrolyte during the gas discharge process.

Under such a structure, the gas inside the battery cell can be sufficiently removed, so that the swelling phenomenon that the battery cell swells up due to repetitive charging and discharging of the battery can be alleviated, and the problem of deterioration of the performance of the battery due to the residual gas can be prevented can do.

For example, the nanofilter has a mesh structure, and the mesh structure may have a porous mesh or net shape, and the pores may have a uniform size.

In addition, the nano-filter may be made of any one of a fiber glass net, a stainless steel net, a polypropylene net net, an aluminum net net, and a polyester net net. An insulating material is applied to the entire surface of the filter, It is possible to maintain an electrically insulated state.

In one specific example, the nanofilter may have a structure in which one end of the nanofilter is fixed to one side of the outer periphery of the accommodating portion and a portion of the gas collecting portion in contact with each other, and the other end is fixed to the inner surface of the gas collecting portion.

Specifically, the nanofilter is fixed to one side of the outer periphery of the accommodating portion and the inner surface of the gas collecting portion so as to block the electrolyte flow path from the accommodating portion to the gas collecting portion. Lt; / RTI >

In other words, the nanofilter mounted at the boundary portion in the gas trapping portion adjacent to the storage portion can block the flow path for the electrolyte to move to the gas trapping portion. Therefore, even if the electrode assembly is not placed in the upright state, It is possible to perform the gas discharging process of FIG.

In other words, the arrangement state of the electrode assembly has an advantage that it does not act as a limiting factor in achieving the object of the present invention through the electrolyte discharge preventing member.

At this time, one end and the other end of the nanofilter may be fixed by adhesion, heat fusion, or welding.

The nano-filter may have a structure having a mounting angle of 10 to 90 degrees with respect to one surface of the gas collecting part.

The present invention also provides a battery cell manufactured by the above manufacturing method, a battery pack including at least one battery cell, and a device including the battery pack as a power source.

The device may be any one selected from a smart phone, a mobile phone, a notebook, a tablet PC, a wearable electronic device, an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle or a system for power storage, The structures of these devices and their fabrication methods are well known in the art, and a detailed description thereof will be omitted herein.

As described above, according to the method of manufacturing a battery cell of the present invention, the electrolyte discharge preventing member is installed in the flow path from the inside of the battery cell to the gas collecting part, the electrolyte is overdosed in the process of discharging the gas to the outside in the degassing process It is not necessary to inject an excessive amount of electrolytic solution, and the amount of gas remaining in the battery cell is reduced to prevent the problem of deterioration of the battery performance, and the effect of the swelling phenomenon can be alleviated to provide.

1 is a schematic view of an exploded perspective view of a typical conventional pouch type secondary battery;
FIG. 2 is a schematic view showing a process of injecting an electrolytic solution in a state where an electrode assembly is mounted on a receiving portion of a battery case and forming a gas collecting portion; FIG.
Fig. 3 is a schematic view showing an electrolyte injection preventing member mounted inside a battery case including a gas collecting part; Fig.
Fig. 4 is a schematic view showing the state of Fig. 3 viewed from the direction of the arrow A; Fig.
5 is a schematic view of a process in which gas is discharged through a through-hole formed in a gas collecting portion after the open end of the gas collecting portion is sealed by heat welding;
6 is a schematic view of a process in which the gas collector is cut after the gas is discharged; And
7 is a schematic view of a battery cell manufactured by forming a sealing portion at a portion where the gas collecting portion is cut.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited by the scope of the present invention.

FIG. 2 schematically shows a process of injecting an electrolytic solution in a state where an electrode assembly is mounted on a storage portion of a battery case and before forming a gas collecting portion.

2, when the electrode assembly 120 is mounted on the receiving portion 110 of the battery case 100 of the laminate sheet, the entire outer circumferential surface excluding the one end portion 131 formed with the gas collecting portion 130 is opened The sealing part 101 is formed by fusing and an electrolyte solution (not shown) is injected in the direction of the arrow through one opened end part 131 of the gas trapping part 130 which is not thermally fused.

At this time, the one side portion 102 of the outer periphery adjacent to the open end 131 of the gas collecting portion 130 vertically corresponds to the folded portion of the laminate sheet, so that it is not necessary to perform the heat fusion .

Next, Fig. 3 shows a state in which the electrolyte discharge preventing member is mounted inside the battery case including the gas collecting portion, and Fig. 4 schematically shows a state in which Fig. 3 is viewed from the direction of arrow A

3, an electrolyte injection preventing member 140 is attached to a portion of the battery case 100 adjacent to the accommodating portion 110 or adjacent to one side or a boundary of the gas collecting portion.

The electrolyte discharge preventing member 140 is intended to prevent the electrolyte in the battery cell from being discharged together with the gas generated during the activation process of the electrode assembly 120 in the degassing process. And is located on the path through which the electrolyte flows from the storage portion 110 to the gas trapping portion 130.

Specifically, one side 132 located adjacent to the right side of the storage part 110 on which the electrode assembly 120 is mounted, or one side 132 located on the left side of the gas collection part 130, Corresponds to the boundary portion of the gas trapping portion 130 corresponding to the flow path through which the electrolyte flows from the gas trapping portion 110 to the gas trapping portion 130. Therefore, the electrolyte injection preventing member 140 is mounted at the above-described position and is shown mounted on the outer surface of the battery case 100 as shown in the figure, but it should be considered that the member is located inside the battery case 100.

4, an electrode assembly 120 is mounted inside the housing 110 and an electrolyte injection preventing member 140 is formed at a connection portion between the housing 110 and the gas collecting unit 130, Respectively.

The electrolyte discharge preventing member 140 is formed by welding or thermally fusing or adhering the one end portion 141 of the electrolyte discharge preventing member 140 in the battery case to a portion where the one end portion 141 is adjacent to the outer periphery of the receiving portion 110 and the gas collecting portion 130 And the other end 142 is fixed to the inner surface of the gas collecting part 130, which is located on the upper surface.

The open end 131 located at one side of the gas trapping unit 130 is in a state of being in communication with the outside without being thermally fused.

5 is a schematic view of a process of sealing the open end of the gas collecting part by thermal welding and piercing through the gas collecting part after the activation process of the electrode assembly to discharge the gas generated in the battery case In addition,

5, after the electrolyte injection preventing member 140 is mounted, a sealing part 102 formed by thermal fusion is formed at the open end 131 of the gas collecting part 130 so that the gas collecting part 130 And is sealed from the outside.

It is necessary to remove the gas generated in the activation process of the electrode assembly 120 to be performed thereafter so that three through holes 133a, 133b and 133c are formed in the gas trapping unit 130, 110 in the direction of the arrow X and collects the gas in the gas trapping unit 130.

Since some of the electrolytic solution which moves together with the gas in the process of collecting the gas by the gas collecting part 130 is blocked or reduced by the electrolyte discharge preventing member 140, the electrolytic solution flowing into the gas collecting part 130 .

Through this process, the gas collected in the gas trapping unit 130 is discharged to the outside Y through the through holes 133a, 133b, and 133c.

FIG. 6 schematically shows a process of cutting and removing a gas collecting portion including a member for preventing electrolyte discharge after the gas is discharged through the through-hole of FIG. 5, and FIG. 7 schematically shows a process of removing the gas collecting portion, A battery cell made of a finished product by forming a sealing part is shown.

7 and 8, after the gas collected in the gas trapping part 130 is removed through the through holes 133a, 133b and 133c, the gas trapping part 130 and the adjacent The gas collecting part 130 is cut along the boundary line 132 where the part contacts and the sealing part 103 is formed by heat fusion at the cut part.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (12)

A method of manufacturing a battery cell in which an electrode assembly and an electrolyte are embedded in a housing portion formed in a battery case of a laminate sheet,
(a) a process of attaching an electrode assembly to a storage portion of a battery case, injecting an electrolyte, and forming a gas trapping portion at one side of the outer peripheral sealing portion;
(b) a step of mounting an electrolyte discharge preventing member on a boundary portion in a gas trapping portion adjacent to the storage portion;
(c) activating the electrode assembly by performing charging and discharging;
(d) discharging the gas generated in the battery case by puncturing at least one through-hole in the gas collecting part; And
(e) cutting out the gas collecting part including the electrolyte injection preventing member after discharging the gas through the through hole in the step (d), and removing the gas collecting part;
And forming a battery cell. The method of claim 1, wherein the step (a)
(a1) preparing a laminated sheet having a receiving portion having a shape corresponding to the electrode assembly;
(a2) attaching the electrode assembly to the housing part, and then thermally fusing the outer periphery of the laminate sheet except for one side where the gas collecting part is to be positioned, thereby forming a sealing part; And
(a3) injecting an electrolytic solution through the one side of the unsealed state;
And forming a battery cell. The method for manufacturing a battery cell according to claim 1, further comprising, after the step (b), sealing the open end of the gas collecting part by thermal welding. The method of claim 1, further comprising performing a clamping & baking step of adjusting the thickness of the battery cell by applying heat and pressure after the step (c) or step (d) Gt; The apparatus according to claim 1, wherein the electrolyte injection preventing member is a nanofilter having a pore size that allows a gas phase component to pass through and a liquid component to pass therethrough so as to block or reduce the discharge of the electrolyte during the gas discharge process A method of manufacturing a battery cell. [6] The method of claim 5, wherein the nanofilter has a mesh structure. [7] The method of claim 6, wherein the mesh structure has a porous mesh or net shape, and the pores are uniform in size. 7. The battery cell manufacturing method according to claim 6, wherein the nanofilter is fixed to one side of the outer periphery of the housing part and a portion of the gas collecting part in contact with each other, and the other end is fixed to the inner surface of the gas collecting part Way. 9. The method of manufacturing a battery cell according to claim 8, wherein the nanofilter has a structure for blocking an electrolyte flow path from the accommodating portion to the gas collecting portion, wherein one end and the other end are fixed. The method according to claim 8, wherein the one end and the other end of the nanofilter are fixed by adhesion, heat fusion, or welding. 9. The method of claim 8, wherein the nanofilter has a mounting angle of 10 to 90 degrees with respect to a surface of the gas collecting part. A battery cell characterized by being manufactured by the method according to any one of claims 1 to 11.

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