KR102386690B1 - Method for making pouch-typed secondary batteries controlling discharge of electrolyte solution and apparatus therefor - Google Patents

Abstract

The present invention provides a method for manufacturing a pouch-type secondary battery, comprising: injecting an electrolyte into a pouch case; applying a temporary stopper to the extension sheet opening of the pouch case; applying a vacuum to the inside of the pouch case; and removing the temporary stopper and sealing the pouch case at a predetermined position; to prevent the electrolyte from being discharged during the process of applying a vacuum in the pouch.

Description

Method for making pouch-typed secondary batteries controlling discharge of electrolyte solution and apparatus therefor

The present invention relates to a method for manufacturing a pouch-type secondary battery in which electrolyte discharge is controlled, and an apparatus used therefor.

Recently, interest in energy storage technology is increasing. Efforts for research and development of electrochemical devices are becoming more concrete as the field of application expands to cell phones, camcorders, notebook PCs, and even the energy of electric vehicles.

Electrochemical devices are receiving the most attention in this aspect, and among them, the development of rechargeable lithium batteries that can be charged and discharged is the focus of interest.

In general, a lithium secondary battery can supply electrical energy including a positive electrode and a negative electrode separated from each other by a separator, and an electrolyte that enables ion transfer between the two electrodes, and a typical battery including a lithium ion battery is used in the battery. A liquid electrolyte is used as an electrolyte that enables ion movement.

In addition, lithium secondary batteries are manufactured and used by inserting a separator that blocks the positive and negative electrodes and between the positive and negative electrodes into the battery case, injecting electrolyte into the battery case, and then sealing the battery case. Secondary batteries are classified according to the structure of the electrode assembly of the positive electrode/separator/negative electrode structure. Typically, a jelly-roll structure in which a long sheet-shaped positive electrode and negative electrode are wound with a separator interposed therebetween. (winding type) electrode assembly, a stack type (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 interposed therebetween, a state in which positive and negative electrodes of a predetermined unit are interposed with a separator and a stack/folding type electrode assembly having a structure in which bi-cells or full cells stacked with a single layer are wound.

Recently, a pouch-type battery having a structure in which a stack-type or stack/folding-type electrode assembly is embedded in a pouch-type battery case of an aluminum laminate sheet is attracting a lot of attention due to low manufacturing cost, small weight, easy shape deformation, etc. Also, its usage is gradually increasing.

In general, a pouch-type secondary battery has, for example, a structure in which an electrode assembly is embedded in a housing portion of a pouch-type battery case made of an aluminum laminate sheet. That is, the pouch-type secondary battery forms a accommodating part for mounting the electrode assembly on a laminate sheet, and heat-seals a separate sheet separated from the sheet or a sheet extending therefrom in a state where the electrode assembly is mounted in the accommodating part. It is manufactured by sealing.

1 schematically shows a cross-sectional structure of a laminate sheet generally used in a pouch-type battery, and FIG. 2 is an exploded perspective view of a pouch-type secondary battery including a battery case made of the laminate sheet according to FIG. shown negatively.

First, looking at the pouch laminate sheet with reference to FIG. 1 , the laminate sheet 10 includes an outer coating layer 11 forming the outermost layer, a barrier layer 12 preventing penetration of a material, an adhesive layer 14 , and sealing for It is composed of an inner resin layer (13).

Since the outer coating layer 11 serves to protect the battery from the outside, excellent tensile strength and weather resistance compared to its thickness are required, and ONy (stretched nylon film) is widely used. The barrier layer 12 serves to prevent air, moisture, etc. from entering the inside of the battery, and aluminum (Al) is mainly used. The inner resin layer 13 is heat-sealed to each other by heat and pressure applied in a state in which the electrode assembly is embedded, thereby providing sealing properties, and is mainly made of CPP (non-stretched polypropylene film). The adhesive layer 14 serves to compensate for the low adhesion of the CPP inner resin layer 13 to the barrier layer 12 .

In addition, referring to FIG. 2 , the battery case 15 is integrated with the main body 20 in which the receiving part 21 for mounting the electrode assembly 50 is formed, and the body 20 and the receiving part 21 . It consists of a cover 30 in a form that can seal the.

Therefore, in the pouch-type secondary battery, after the electrode assembly is mounted in the receiving portion 21 of the battery case 15 , bending is performed at the connection portion between the main body 20 and the cover 30 , and the receiving portion 21 is sealed. In order to do this, it is manufactured by heat-sealing three surfaces of the sealing part 22 and the cover 30 of the main body 20 except for the bent part.

That is, when heat is applied to the sealing portion of the main body 20 and the cover 30 that are facing each other with the inner resin layer corresponding to the innermost layer, the main body 20 and the cover 30 are fused while the inner resin layer is melted. combined and sealed by

Then, after the electrolyte is injected into the battery case, a primary vacuum is applied to the battery case so that the electrolyte is sufficiently wetted on the electrode assembly electrode. Subsequently, charging, aging, and discharging processes are performed to activate the secondary battery. A secondary vacuum is applied to the battery case to remove gas generated in the battery during the charging and discharging process. However, when such a vacuum is applied, not only the gas but also the electrolyte is discharged, and as a result, a problem occurs in that the capacity of the electrolyte becomes smaller than the capacity intended for design.

The electrolyte serves to provide a path for the movement of ions so that the battery reaction can occur smoothly. there is. Therefore, it is desirable to prevent discharge of electrolyte from occurring or to minimize discharge of electrolyte during gas removal.

The present invention is to solve the above problems, and in the process of injecting electrolyte into the pouch and evacuating the inside of the pouch, a method of manufacturing a pouch-type secondary battery that solves the problem that the electrolyte is unintentionally discharged to the outside of the pouch to provide.

Another object to be solved by the present invention is to provide a method of manufacturing a pouch-type secondary battery that solves the problem of discharging electrolyte in the process of removing gas generated after the battery activation process.

Another object to be solved by the present invention is to provide an apparatus for controlling discharge of an electrolyte.

Other objects and advantages of the present invention will be understood by the following description. In addition, it will be readily apparent that the objects and advantages of the present invention can be realized by means or methods and combinations thereof recited in the claims.

In order to solve the above problems, according to an embodiment of the present invention, there is provided a method for manufacturing a pouch-type secondary battery, the method comprising: injecting an electrolyte into the pouch case; applying a temporary stopper to the extension sheet opening of the pouch case; applying a vacuum to the inside of the pouch case; and removing the temporary stopper and sealing the extension sheet opening of the pouch case.

After the temporary stopper is applied in the opening, the method may further include pressing the periphery of the opening with a press unit so that a gap is not generated between the opening and the temporary stopper.

The temporary stopper may have a structure including an outer frame, an inner frame fitted within the outer frame, and a filter sandwiched between the inner frame and the outer frame and having one or more pores.

The filter may be in the form of a film formed of a hydrophobic material.

The filter may have one or more micrometer-level pores formed therein.

A step may be formed at an upper end inside the outer frame or a lower end outside the inner frame so that the inner frame is fixed.

In the temporary stopper removed from the opening, the filter may be replaceable.

According to one aspect of the present invention, after injecting the electrolyte into the pouch for secondary batteries, the filter is applied within the opening of the pouch extension sheet to vacuum the inside of the pouch after the electrolyte discharge path is substantially eliminated from the opening, so that the electrolyte is intended during the vacuuming process. The problem of not being discharged can be solved.

In addition, according to an aspect of the present invention, since the temporary stopper used to prevent the discharge of the electrolyte can be recycled in a simplified way, the process is simplified and economically advantageous during mass production.

The drawings accompanying the present specification illustrate preferred embodiments of the present invention, and serve to better understand the technical spirit of the present invention together with the above-described content of the present invention, so the present invention is limited only to the matters described in such drawings is not interpreted as
1 is a schematic diagram schematically showing the cross-sectional structure of a laminate sheet generally used in a pouch case of a pouch-type secondary battery.
FIG. 2 is an exploded perspective view of a pouch-type secondary battery including a battery case made of the laminate sheet according to FIG. 1 .
Figure 3a schematically shows a step before inserting a temporary stopper into the opening of the pouch extension sheet after injecting the electrolyte in one embodiment of the present invention.
Figure 3b schematically shows a state before applying the press unit to the periphery of the temporary stopper inserted into the opening of the pouch extension sheet and the pouch extension sheet enclosing the temporary stopper in one embodiment of the present invention.
Figure 3c schematically shows a state in which the press unit is applied to the periphery of the temporary stopper inserted into the opening of the pouch extension sheet and the pouch extension sheet covering the temporary stopper.
3D schematically shows a state in which a temporary stopper is inserted into the opening of the pouch extension sheet without a press unit.
Figure 4a is a perspective view schematically showing the main components of the temporary stopper according to an aspect of the present invention.
4B is a schematic representation of a temporary closure assembled in accordance with an aspect of the present invention.

Hereinafter, the present invention will be described in detail. Prior to this, the terms or words used in the present specification and claims should not be construed as being limited to conventional or dictionary meanings, and the inventor may properly define the concept of the term in order to best describe his invention. It should be interpreted as meaning and concept consistent with the technical idea of the present invention based on the principle that it can be. Therefore, the configuration shown in the embodiments and drawings described in the present specification is only the most preferred embodiment of the present invention, and does not represent all the technical spirit of the present invention, so at the time of the present application, they can be replaced It should be understood that there are many possible equivalents and variations.

The pouch-type secondary battery applicable to the present invention may be formed of an electrode assembly, an electrolyte, and a pouch case for accommodating the electrode assembly.

The electrode assembly is configured in a form in which a positive electrode and a negative electrode are disposed with a separator interposed therebetween. In this case, the electrode assembly may have various structures such as a structure in which one positive electrode and one negative electrode are wound with a separator interposed therebetween, or a structure in which a plurality of positive electrodes and a plurality of negative electrodes are stacked with a separator interposed therebetween.

The positive electrode and the negative electrode may be formed in a structure in which a slurry of an electrode active material is applied to an electrode current collector, respectively, and such a slurry is typically formed by stirring a granular electrode active material, an auxiliary conductor, a binder, and a plasticizer in a state in which a solvent is added. it could be

As used herein, the term 'electrolyte' is understood to encompass not only an electrolyte in a completely liquid state, but also all types of electrolytes or electrolytes for secondary batteries that can cause electrolyte discharge.

The pouch exterior material may be in any form, including an integral type in which the upper pouch and the lower pouch are connected on one side, or a form in which the upper pouch and the lower pouch are separated. The upper pouch and the lower pouch have a concave interior space formed therein, so that the electrode assembly and the electrolyte can be accommodated.

In addition, the pouch case material may contain the electrode assembly and the electrolyte while maintaining the sealed state by sealing the sealing parts to each other. That is, the upper pouch and the lower pouch have a sealing part formed on the outer circumferential surface to seal the inner space, and these sealing parts are adhered (sealed) to each other. can be a structure.

The position at which the extension sheet is formed in the pouch is not particularly limited, but it is preferable to exclude the edge at which the electrode tab extends to the outside. All of the extended sheet ends may be prepared open to allow for more rapid evacuation.

In general, the manufacturing process of a pouch-type secondary battery includes ① injecting electrolyte into the pouch case, ② applying a vacuum to help with electrolyte wetting and sealing the end of the pouch, ③ room temperature or high temperature for sufficient wetting An aging step of storing the secondary battery in the , ④ primary charging step, ⑤ a degassing step of removing gas generated due to decomposition of electrolyte during primary charging, etc., the present invention includes steps ① and ② It may be applied to step ⑤, but may also be applicable to step ⑤.

More specifically, in a method for manufacturing a pouch-type secondary battery according to an aspect of the present invention, the method comprising: injecting an electrolyte into a pouch case; applying a temporary stopper to the extension sheet opening of the pouch case; applying a vacuum to the inside of the pouch case; and removing the temporary stopper and sealing the pouch case edge after the vacuum is completed. Thereafter, the pouch extension sheet may be cut and trimmed after degassing in a subsequent process.

As used herein, the term 'pouch extension sheet' refers to a pouch laminate sheet extending to perform a pouch vacuuming process, which is provided in addition to the portion in which the electrode assembly is accommodated and the portion in which the pouch edge is sealed, that is, the ' 120' is understood to mean the part.

First, a step of inserting the temporary stopper into the pouch extension sheet will be described with reference to FIG. 3A .

The pouch 100 for a secondary battery of FIG. 3A is configured to include a pouch receiving part 110 in which an electrode assembly and an electrolyte are accommodated, a pouch laminate sheet extending, and an extension sheet 120 having an open end. , 'temporary stopper' 200 is inserted through the open end.

As shown in FIG. 4A , the temporary stopper may include an outer frame 210 , a filter 220 and an inner frame 230 , but the method for fixing the filter is not limited to using the outer frame and the inner frame.

The outer frame 210 and the inner frame 230 have a shape such as a kind of embroidery frame, so that the inner frame is inserted into the outer frame and fixed. To this end, a kind of step 211 may be formed at the upper end of the inner frame 210 or the lower end outside the inner frame 230 to prevent the inner frame 230 from moving. is not limited thereto.

The outer frame should have a size smaller than the opening of the pouch extension sheet so that it can be easily inserted into the opening of the pouch extension sheet.

In addition, the depth of the outer frame and/or inner frame ( FIGS. 4a , 210d , 230d ) is not particularly limited as long as it meets the object of the present invention, but it should be designed so that it does not come into contact with the electrode assembly past the extended sheet portion.

In addition, the thickness of each of the outer frame and inner frame (FIG. 4a, 210w, 230w, 230w') is also not particularly limited as long as it meets the purpose of the present invention. However, since a step may be formed in the outer frame 210 or the inner frame 230 so that the inner frame 230 does not move further forward, for example, the thickness of the side located closer to the electrode assembly is closer to the pouch extension sheet opening. It may be thicker than the thickness of the side where it is located.

The outer frame and/or inner frame may be formed in a shape similar to the opening of the case extension sheet suitable for application to the case extension sheet. For example, the pouch case extension sheet opening may have a non-rectangular lip shape or an elliptical shape because both end portions of the opening part are fused. In this case, the outer frame and/or inner frame are not only rectangular but also oval may be in the same form as

The material of the outer frame and/or inner frame may be the same or different from each other. The material of the outer frame and/or inner frame is not particularly limited as long as it does not react with the electrolyte and meets the purpose of the present invention, and non-limiting examples may be plastics, heat-resistant plastics, elastic polymers, and rubber. An elastic polymer can be used to prevent the filter from rupturing and causing defects in the process of attaching the film-type filter to the outer frame/inner frame.

In the present specification, the 'filter' 220 is understood to have air permeability because pores 220p through which gas can be discharged are formed without causing an electrochemical reaction and absorbing an electrolyte.

The filter may be in the form of a film, and the thickness is not particularly limited as long as it meets the purpose of the present invention. For example, it may have a thickness of 10 μm to 1 mm or 10 μm to 100 μm so that the filter does not rupture when a vacuum is applied inside the pouch case.

The material of the filter does not react with the electrolyte and does not absorb the electrolyte, and it is preferable that it is hydrophobic.

As a non-limiting example, the filter may be formed from one or a mixture of two or more selected from the group consisting of a polyolefin-based resin, a polyester-based resin, a polyacrylonitrile resin, and a cellulose-based material, for example, the filter is made of polyethylene terephthalate. can be manufactured. In addition, hydrophobic treatment may be added to the film made of the resin to obtain a filter having more hydrophobicity than the polyolefin resin.

Alternatively, the filter may include, but is not limited to, natural rubber having excellent elasticity, vulcanized natural rubber, butadiene polymer, butadiene-styrene interpolymer, butadiene-acrylonitrile interpolymer, butadiene-styrene-acrylonitrile interpolymer, and thermoplastic polyurethane. It may be formed from one type or a mixture of two or more types selected from among.

Alternatively, the filter is a non-limiting example, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-trichloroethylene, polyvinylidene fluoride- Chlorotrifluoroethylene, polymethyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, ethylene vinyl acetate copolymer, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, One selected from the group consisting of cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, carboxymethyl cellulose, acrylonitrile styrene-butadiene copolymer, and polyimide Or it may be formed from a mixture of two or more.

One or more pores may be formed in the filter to allow gas to be discharged, and two or more pores may be formed in the filter. If the gas can be smoothly discharged, the number of pore shapes is not particularly limited, but the film should not be ruptured when vacuum is applied. In this aspect, for example, 100 or less, 50 or less, 10 or less pores may be formed. The shape of the pores is not particularly limited, and for example, may have a circular, oval, or polygonal shape. The pores may be formed to have a size of 1 μm or more and less than 1 mm based on the longest diameter, so that the gas may be smoothly discharged while preventing the discharge of the electrolyte.

The filters may be used to manufacture more than one pouch per one, and may be replaced as needed.

Referring to FIGS. 4A and 4B , in an embodiment of the present invention, after the filter 220 in the form of a film is placed on the inner frame 230 , the temporary stopper can be assembled by inserting it into the outer frame 210 . At this time, the position of the inner frame 230 can be adjusted by forming a step 231 at the upper end of the inner frame 210 or at the lower end of the outer frame 230 . The formed aspect is shown. Even if the electrolyte in the pouch case receiving part is not discharged by the temporary stopper of the present invention, the part to be used as the sealing part may be contaminated by contaminating the inside of the pouch extension sheet. If it is made closer, the portion of the pouch extension sheet that is contaminated by the electrolyte may be reduced.

A method of inserting the temporary stopper into the pouch extension sheet 120 is not particularly limited. For example, by installing jigs on both sides of the temporary stopper and lowering the jig, the temporary stopper can be inserted into the opening of the pouch extension sheet.

Then, the temporary stopper 200 may be pressed around the pouch extension sheet 120 is inserted with the press unit 300 .

The press unit is not particularly limited in terms of size or shape as long as the extension sheet and the filter are in close contact to prevent the electrolyte from being discharged to the outside of the pouch during vacuum. For example, as shown in Figure 3b, it may be made of two parts in the shape of a 'C'. Referring to FIG. 3B , a jig may be installed in the press unit 300 and may be moved up and down together with the jig. The press unit 300 is tightened so that the opening of the pouch extension sheet and the temporary stopper 200 are in close contact after descending to the portion where the temporary stopper 200 is inserted among the pouch extension sheet openings. To this end, when both ends of the press unit composed of two parts in the shape of a 'U' come into contact with the pouch extension sheet opening, the inner circumference of the press unit may be substantially the same as or slightly smaller than the outer circumference of the temporary stopper. The extent to which the extension sheet and the temporary stopper are pressed by the press unit is sufficient if the extension sheet and the temporary stopper are in close contact, and the temporary stopper should not be pressed excessively to impede vacuumization.

A vacuum is then applied to the pouch by conventional methods practiced in the art.

Then, after the electrolyte wetting process is completed, the inserted temporary stopper is removed, and the end of the pouch extension sheet is sealed. Alternatively, the temporary stopper may be removed after heat-sealing a predetermined position of the pouch extension sheet.

In order to replace the filter among the temporary stoppers, the inner frame and filter are removed from the outer frame of the temporary stopper, and a new filter is placed on the inner frame and then applied to the outer frame again.

As described above with reference to the drawings according to the embodiment of the present invention, those skilled in the art to which the present invention pertains will be able to make various applications and modifications within the scope of the present invention based on the above content.

Claims (7)

In the method of manufacturing a pouch-type secondary battery,
manufacturing an electrode assembly and inserting the electrode assembly into a pouch case;
injecting an electrolyte into the pouch case;
applying a temporary stopper to the extension sheet opening of the pouch case;
applying a vacuum to the inside of the pouch case; and
removing the temporary stopper and sealing the opening of the extension sheet of the pouch case;
including,
The temporary stopper is a method of manufacturing a pouch-type secondary battery having a structure including an outer frame, an inner frame fitted within the outer frame, and a filter sandwiched between the inner frame and the outer frame and having one or more pores formed therein.
The method of claim 1,
After the temporary stopper is applied in the opening, the method further comprising the step of pressing the periphery of the opening with a press unit so that a gap is not generated between the opening and the temporary stopper.
The temporary stopper according to claim 1, characterized in that it has a structure comprising an outer frame, an inner frame fitted within the outer frame, and a filter sandwiched between the inner frame and the outer frame and having one or more pores formed therein.
4. The method of claim 3,
The filter is a temporary stopper, characterized in that in the form of a film formed of a hydrophobic material.
4. The method of claim 3,
The filter is a temporary stopper, characterized in that one or more micrometer-level pores are formed.
4. The method of claim 3,
A temporary stopper, characterized in that a step is formed at the upper end of the inner frame or the lower end outside the inner frame so that the inner frame is fixed.
4. The method of claim 3,
Temporary plug, characterized in that the filter is replaceable.

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