KR102479303B1 - Jig press apparatus - Google Patents

Abstract

The present invention relates to a jig press device for detecting defective cells due to folding of a separator, comprising: a base plate on which battery cells are seated; a pressure plate installed above the bait plate so as to be able to move up and down and having a through hole formed therein; a guide part that moves horizontally along the through hole of the pressure plate; and a jig located on the lower end surface of the press plate, interlocked with the guide part, moving to a desired press part, and then pressurizing the upper surface of the battery cell. is a structure containing

Description

Jig press apparatus {Jig press apparatus}

The present invention relates to a jig press at room temperature and a method for detecting defective cells for detecting defective cells due to tearing or folding of a separator of an electrode assembly.

As technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source is rapidly increasing, and accordingly, a lot of research is being conducted on secondary batteries that can meet various needs.

Typically, in terms of the shape of secondary batteries, demand for prismatic secondary batteries and pouch-type secondary batteries that can be applied to products such as mobile phones with a thin thickness is high, and in terms of materials, advantages such as high energy density, discharge voltage, and output stability There is a high demand for lithium secondary batteries such as lithium ion batteries and lithium ion polymer batteries.

In addition, secondary batteries are classified according to the structure of the positive electrode, the negative electrode, and the electrode assembly of the separator structure interposed between the positive electrode and the negative electrode. Typically, long sheet-shaped positive electrodes and negative electrodes are separated by a separator. A jelly-roll (wound type) electrode assembly having a structure wound in an interposed state, a stack type (stack 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 predetermined A stack-folding type electrode assembly having a structure in which unit cells such as a bi-cell or a full cell are stacked in a state in which positive and negative electrodes of the unit are stacked with a separator interposed therebetween may be mentioned.

1 and 2 schematically illustrate an exemplary structure and manufacturing process of such a stack-folding type electrode assembly.

Referring to these figures, a plurality of full cells (10, 11, 12, 13, 14...) in which anode/separator/cathode are sequentially stacked as unit cells are overlapped, and a separator film ( 20) is interposed. The separation film 20 has a unit length capable of covering the full cell, and is bent inward at every unit length, starting from the central pull cell 10 and continuing to the outermost pull cell 14, wrapping each pull cell to overlap the pull cell are interposed in The distal end of the separation film 20 is finished by heat fusion or by attaching an adhesive tape 25 or the like.

In this stack-folding type electrode assembly, for example, full cells 10, 11, 12, 13, 14... are arranged on a long separation film 20, and one end of the separation film 20 is arranged. It is prepared by winding sequentially starting from (21).

At this time, looking at the arrangement and combination of the unit cells, the first pull cell 10 and the second pull cell 11 are located at a distance spaced apart by a width interval corresponding to at least one pull cell, so that during the winding process, the first pull cell 10 and the second pull cell 11 After the outer surface of (10) is completely coated with the separation film 20, the lower electrode of the first full cell 10 comes into contact with the upper electrode of the second full cell 11.

On the other hand, the stack-folding type electrode assembly may cause damage to the separator due to various causes such as negligence or error in operation during the process of mounting on the separator film and winding. In particular, one side of the separator at the start of winding Defects such as partial folding or straight folding occur, resulting in a problem in which a part of the electrode surface is exposed from the separator, and due to this defect, electrodes having the same polarity come into contact at the interface, resulting in deterioration in battery performance There is a problem.

Representatively, problems that may occur in the stack-folding type electrode assembly have been described, but the problem of folding or damage of the separator is not only the starting point of winding of the stack-folding type electrode assembly, but also the structure in which the separator is interposed between the positive electrode and the negative electrode. It may commonly occur in various parts such as a jelly-roll (wound type) electrode assembly and a stack type (stacked type) electrode assembly.

In the conventional secondary battery production process, the voltage measured before and after the degassing process was compared to select defective batteries, but the voltage measured after the degassing process was affected by temperature, resulting in voltage hunting, resulting in accurate voltage measurement. this was difficult

In order to solve this problem, in some prior arts, a flat panel jig is used to pressurize the flat surface of the completed electrode assembly, and then a current is applied to induce a short circuit of the electrode exposed from the separator, suggesting a method of screening for defects. are doing However, when using a flat jig that presses the plane of the electrode assembly as in the above technique, it is difficult to cause a short circuit of the exposed electrode due to the relatively low pressing force due to the large pressing area. In particular, in the case of a stack-folding type electrode assembly, It has a problem in that it is difficult to effectively select defective electrode exposure due to the folding of the separator that may occur at the starting point of winding.

Therefore, there is a high need for a technology capable of fundamentally solving these problems.

Korean Patent Publication No. 2016-0068244 Korean Patent Publication No. 2015-0016671 Korean Patent Publication No. 2015-0054372 Korean Patent Publication No. 2009-0060186

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

An object of the present invention is to provide a jig press device for determining whether a battery cell has a defect due to tearing or folding of a separator.

Another object of the present invention is to provide a jig press device capable of intensively sorting out defects due to tearing or folding of the separator by pressing in close contact with the battery cell with high pressure in an area where the defect of the battery cell is concerned.

Another object of the present invention is to provide a method for screening defective battery cells by increasing the accuracy of the screening function of defective battery cells by pressurizing at room temperature.

A jig press device according to the present invention for achieving this object includes a base plate on which battery cells are seated; and a pressing plate installed above the bait plate so as to be able to move up and down and having a through hole formed therein. a guide part that moves horizontally along the through hole of the pressure plate; and a jig located on the lower end surface of the press plate, interlocked with the guide part, moving to a desired press part, and then pressurizing the upper surface of the battery cell. It is composed of a structure that includes.

Therefore, in the jig press device according to the present invention, the jig for pressing the upper surface of the battery cell is configured to be movable by the guide unit, so that the jig is moved to an area where defects due to tearing or folding of the separator are expected, Since defective parts are effectively pressurized, defective cells that may occur in the battery cell production process can be more accurately detected.

In one specific example, a voltage measurement unit for measuring the voltage of the battery cell before/during/after pressurization may be further included. By comparing voltages measured before/during/after pressurization, a cell in which a voltage drop is observed can be regarded as a defective cell.

The present invention is characterized in that in order to detect a defect due to tearing or folding of a separator of a battery cell, a region where tearing or folding of a separator is expected to occur is pressed in close contact with high pressure. To this end, the jig press device of the present invention has a structure in which a jig for pressurizing a battery cell can move in conjunction with a guide unit.

The guide part is designed to be movable along the shape of the through hole formed in the pressure plate, and when the guide part is moved to a region where tearing or folding of the separator is expected, the jig coupled with the guide part moves together.

In one specific example, the through hole may be extended in a straight line at the center of the pressing plate. A direction in which the through hole extends may be a horizontal direction or a vertical direction of the pressing plate.

In one specific example, the through hole may be extended crosswise at the center of the plate.

In one specific example, the jig may be made of natural rubber or a synthetic polymer material, and may have a structure attached by an adhesive to a portion in contact with the guide portion. The lower end of the jig may be in a flat shape, and may be 10% to 30%, more preferably 15% to 25% of the planar area of the battery cell. In addition, the jig may have a structure having a thickness ranging from 1 mm to 5 mm. If the thickness of the jig is too thin, it is not preferable to effectively pressurize areas where defects are possible, and if the thickness is too thick, the electrode exposed by damage to the surface of the separator in the area where the jig is not located can effectively cause a short circuit. It is not desirable because there is no

The electrode assembly included in the battery cell is not particularly limited as long as it has a structure comprising a positive electrode, a negative electrode, and a separator by connecting a plurality of electrode tabs, specifically, a jelly-roll type structure, a stacked structure, A stack-folding type structure and a lamination-stack type structure may be mentioned.

Specifically, the jelly-roll is coated with an electrode active material on a metal foil used as a current collector, dried and pressed, cut into a band of a desired width and length, and separated between the negative electrode and the positive electrode using a separator, and then spirals into a spiral. It is manufactured by winding it to form an oval shape on a horizontal cross section.

In addition, a plurality of electrodes or unit cells in a stack-folding structure electrode assembly with an anode, a cathode, and a separator interposed are overlapped, and a continuous separator sheet is interposed and wound in each overlapping portion. . Details of the electrode assembly of the stack-folding structure are disclosed in Korean Patent Application Publication Nos. 2001-0082058, 2001-0082059, and 2001-0082060 of the present applicant, and these applications are related to the content of the present invention. incorporated as a reference.

In one specific example, the unit cell has a structure in which one or more positive electrodes and one or more negative electrodes are stacked with a separator interposed therebetween, in which the type of electrodes located on both sides is the same, or the type of electrodes located on both sides is It may be another full cell.

The electrode plates or unit cells may have a stacked structure such that electrode terminals are arranged together on the upper or lower sides, or the electrode terminals are arranged on the upper side and the first electrode terminal is arranged on the lower side opposite to the upper side. It may also have a structure in which two electrode terminals are stacked so as to be arranged.

On the other hand, the present invention is a method for determining whether a battery cell is defective due to tearing or folding of a separator of a battery cell using the jig press device, and after placing the battery cell on the jig press device, the voltage (V1) process of measuring; moving a jig to a region where tearing of the separator or folding of the separator is expected to occur using the guide of the jig press device; pressing process; The process of measuring the voltage (V2); It provides a method for determining whether or not a battery cell is defective, comprising:

In one specific example, a case in which ΔOCV (V1-V2) is 3 mV or more may be determined to be defective.

In one specific example, the above processes may be performed at room temperature.

In one specific example, the pressure during pressurization may be 500 to 4000 kgf, more preferably 1000 to 3000 kgf, and most preferably 1500 to 2500 kgf. If the pressure at the time of pressurization is too low, it is difficult to detect defects due to folding or tearing of the separator, which is not preferable, and if the pressure is too high, it is not preferable because it may damage the electrode.

The battery cell to be selected may be a lithium secondary battery, and a typical lithium secondary battery is composed of a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte solution containing lithium salt.

The positive electrode is prepared, for example, by coating a mixture of a positive electrode active material, a conductive material, and a binder on a positive electrode current collector and then drying the mixture. If necessary, a filler may be further added to the mixture.

The cathode active material may include layered compounds such as lithium cobalt oxide (LiCoO ₂ ) and lithium nickel oxide (LiNiO ₂ ), or compounds substituted with one or more transition metals; lithium manganese oxides such as Li _1+x Mn _2-x O ₄ (where x is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ , LiMnO ₂ ; lithium copper oxide (Li ₂ CuO ₂ ); vanadium oxides such as LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ , and Cu ₂ V ₂ O ₇ ; Ni site type lithium nickel oxide represented by the formula LiNi _{1 - x} M _x O ₂ (where M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, and x = 0.01 to 0.3); Formula LiMn _{2 - x} M _x O ₂ where M = Co, Ni, Fe, Cr, Zn or Ta and x = 0.01 to 0.1 or Li ₂ Mn ₃ MO ₈ where M = Fe, Co, Ni, Cu or Zn) lithium manganese composite oxide; LiMn ₂ O ₄ in which Li part of the formula is substituted with an alkaline earth metal ion; disulfide compounds; Fe ₂ (MoO ₄ ) ₃ etc. are mentioned, but it is not limited only to these.

The conductive material is typically added in an amount of 1 to 30% by weight based on the total weight of the mixture including the cathode active material. Such a conductive material is not particularly limited as long as it has conductivity without causing chemical change in the battery, and examples thereof include graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and summer black; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskeys such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives may be used.

The binder is a component that assists in the binding of the active material and the conductive material and the binding to the current collector, and is typically added in an amount of 1 to 30% by weight based on the total weight of the mixture including the positive electrode active material. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene , polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butyrene rubber, fluororubber, various copolymers, and the like.

The filler is selectively used as a component that suppresses expansion of the positive electrode, and is not particularly limited as long as it is a fibrous material without causing chemical change in the battery, and examples thereof include olefinic polymers such as polyethylene and polypropylene; Fibrous materials such as glass fibers and carbon fibers are used.

The negative electrode is manufactured by coating and drying an anode active material on a negative electrode current collector, and, if necessary, the components described above may be selectively further included.

Examples of the negative electrode active material include carbon such as non-graphitizable carbon and graphite-based carbon; Li _x Fe ₂ O ₃ (0≤x≤1), Li _x WO ₂ (0≤x≤1), Sn _x Me _{1 - x} Me' _y O _z (Me: Mn, Fe, Pb, Ge; Me' : Metal composite oxides such as Al, B, P, Si, elements of groups 1, 2, and 3 of the periodic table, halogens, 0<x≤1;1≤y≤3;1≤z≤8); lithium metal; lithium alloy; silicon-based alloys; tin-based alloys; SnO, SnO ₂ , PbO, PbO ₂ , Pb ₂ O ₃ , Pb ₃ O ₄ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₅ , GeO, GeO ₂ , Bi ₂ O ₃ , Bi ₂ O ₄ , metal oxides such as and Bi ₂ O ₅ ; conductive polymers such as polyacetylene; A Li-Co-Ni-based material or the like can be used.

The separator is interposed between an anode and a cathode, and an insulating thin film having high ion permeability and mechanical strength is used. The pore diameter of the separator is generally 0.01 to 10 μm, and the thickness is generally 5 to 300 μm. Examples of such a separator include olefin-based polymers such as chemical-resistant and hydrophobic polypropylene; A sheet or non-woven fabric made of glass fiber or polyethylene is used. When a solid electrolyte such as a polymer is used as the electrolyte, the solid electrolyte may serve as a separator.

The lithium salt-containing non-aqueous electrolyte solution is composed of a polar organic electrolyte solution and a lithium salt. As the electrolyte, a non-aqueous liquid electrolyte, an organic solid electrolyte, an inorganic solid electrolyte, and the like are used.

Examples of the non-aqueous liquid electrolyte include N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, and gamma -Butylolactone, 1,2-dimethoxyethane, tetrahydroxy franc, 2-methyl tetrahydrofuran, dimethylsulfoxide, 1,3-dioxorane, formamide, dimethylformamide, dioxolane , acetonitrile, nitromethane, methyl formate, methyl acetate, phosphoric acid triesters, trimethoxy methane, dioxolane derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbo An aprotic organic solvent such as nate derivative, tetrahydrofuran derivative, ether, methyl propionate, or ethyl propionate may be used.

Examples of the organic solid electrolyte include polyethylene derivatives, polyethylene oxide derivatives, polypropylene oxide derivatives, phosphoric acid ester polymers, poly agitation lysine, polyester sulfide, polyvinyl alcohol, polyvinylidene fluoride, A polymer containing an ionic dissociation group or the like can be used.

Examples of the inorganic solid electrolyte include Li ₃ N, LiI, Li ₅ NI ₂ , Li ₃ N-LiI-LiOH, LiSiO ₄ , LiSiO ₄ -LiI-LiOH, Li ₂ SiS ₃ , Li ₄ SiO ₄ , Nitride, halide, sulfate, and the like of Li such as Li ₄ SiO ₄ -LiI-LiOH, Li ₃ PO ₄ -Li ₂ S-SiS ₂ , etc. may be used.

The lithium salt is a material that is easily soluble in the non-aqueous electrolyte, and is, for example, LiCl, LiBr, LiI, LiClO ₄ , LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiAsF ₆ , LiSbF ₆ , LiAlCl ₄ , CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, (CF ₃ SO ₂ ) ₂ NLi, lithium chloroborane, lithium lower aliphatic carbonate, lithium 4 phenyl borate, imide, etc. can be used. there is.

In addition, for the purpose of improving charge and discharge characteristics, flame retardancy, etc. in the non-aqueous electrolyte solution, for example, pyridine, triethyl phosphite, triethanolamine, cyclic ether, ethylene diamine, n-glyme (glyme), hexaphosphoric acid triamide , nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N,N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxy ethanol, aluminum trichloride, etc. may be added. may be In some cases, halogen-containing solvents such as carbon tetrachloride and ethylene trifluoride may be further included to impart incombustibility, and carbon dioxide gas may be further included to improve high-temperature storage properties.

The present invention also provides a battery pack including two or more of the battery cells as unit cells, and provides a device including the battery pack as a power source, such as a mobile phone, a portable computer, a smart phone, or a mobile phone. It may be one selected from the group consisting of a fleet PC, a smart pad, a netbook, a light electronic vehicle (LEV), an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, and a power storage device.

Since structures and manufacturing methods of these devices are well known in the art, detailed descriptions thereof are omitted herein.

The jig press device according to the present invention has an effect of effectively and accurately sorting out defective cells by moving a jig to an area where a defect is expected and pressing it in close contact with the area with high pressure.

In addition, since the method for determining the presence or absence of defects in a battery cell according to the present invention uses the jig press device at room temperature to determine whether or not the voltage drops before and after pressurization, accurate data collection is possible and the accuracy of defect selection is improved. has the effect of

1 is a schematic diagram of an exemplary structure of a stack-folding type electrode assembly.
FIG. 2 is a schematic diagram exemplarily illustrating an arrangement and combination of unit cells in a manufacturing process of the stack-folding type electrode assembly of FIG. 1 .
3a and 3b are schematic diagrams of a jig press device according to the present invention.
4 is a schematic diagram of a pressure plate according to an embodiment of the present invention.
5 is a schematic diagram of a pressure plate according to another embodiment of the present invention.
6 is a schematic diagram of a pressure plate according to another embodiment of the present invention.
FIG. 7 is a schematic diagram showing a pressurizing plate and a jig according to FIG. 4 together.
FIG. 8 is a schematic diagram showing a pressurizing plate and a jig according to FIG. 5 together.

Hereinafter, description will be made with reference to drawings according to embodiments of the present invention, but this is for easier understanding of the present invention, and the scope of the present invention is not limited thereto.

3a and 3b are schematic diagrams of a jig press device according to an embodiment of the present invention. 3a and 3b, in the jig press device according to the present invention, a base plate 110 mounted so that one surface of both sides of a battery cell 150 is in contact with the upper surface, and the upper part of the base plate 110 can be moved up and down. The installed pressure plate 120, the guide part 130 that horizontally moves along the through hole (not shown) formed in the pressure plate 120, and the battery cell ( 150) is configured to include a jig 140 that presses the upper surface.

The jig press device moves the jig 140 to a desired pressurized area by manipulating the guide part 130 in order to intensively pressurize the area where the separator is expected to be folded or torn, and then presses the battery cell 150 is configured to

The end of the base plate 120 has a flat shape, the jig 140 is coupled to the lower surface of the guide part 130 with a thickness of 1 mm, and the end pressing the battery cell 150 is vertically cross-sectioned. It can have a circular arc, square or rectangular shape.

4 is a schematic diagram of a pressure plate in a jig press device according to an embodiment of the present invention, and FIG. 7 is a schematic diagram of a lower surface of the pressure plate according to FIG. 4 .

Referring to FIG. 4 , a through hole 121 extending in the longitudinal direction of the pressing plate is formed at the center of the pressing plate 120 . The guide part 130 is inserted into the through hole 121, and the guide part 130 is configured to reciprocate along the extending direction of the through hole 121.

4 and 7, the guide part 130 is coupled to the jig 140, the guide part penetrates the pressure plate 120 through the through hole 121 of the pressure plate 120, and the pressure The jig 140 is coupled to a point where the plate 120 penetrates and reaches the pressing surface of the pressing plate, so that the upper surface of the jig 140 and the lower surface of the pressing plate 120 come into contact with each other. Since the jig 140 is coupled to the guide unit, it can move together when the guide unit moves in the direction of the arrow along the through hole. The width of the through hole 121 is sufficient as long as there is no problem in moving the guide part inside the through hole.

The guide part 130 is designed to be movable along the through hole 121 formed in the pressure plate 120, and when the guide part 130 is moved to a region where tearing or folding of the separator is expected, the guide part 130 The jig 140 coupled to will also move together.

The jig is made of natural rubber or synthetic polymer material, is coupled to the guide part, and is mechanically coupled by a fixing device such as a bolt or nut, or the lower surface of the guide part and the upper surface of the jig are attached by an adhesive. may be a rescue. The lower end of the jig may be in a flat shape, and may be 10% to 30%, more preferably 15% to 25% of the planar area of the battery cell. In addition, the jig may have a structure having a thickness ranging from 1 mm to 5 mm. If the thickness of the jig is too thin, it is not preferable to effectively pressurize areas where defects are possible, and if the thickness is too thick, the electrode exposed by damage to the surface of the separator in the area where the jig is not located can effectively cause a short circuit. It is not desirable because there is no

5 is a schematic diagram of a pressure plate according to another embodiment of the present invention, and FIG. 8 is a schematic diagram of a lower surface of the pressure plate according to FIG. 5 .

Referring to FIGS. 5 and 8 , a through hole 121 extending in the width direction of the pressure plate is formed at the center of the pressure plate 120 . The guide part 130 is inserted into the through hole 121, and the guide part 130 is configured to reciprocate along the extending direction of the through hole 121.

6 is a schematic diagram of the press plate 120 in the jig press device according to another embodiment of the present invention. The through hole 121 may have a rectangular shape as shown in FIGS. 4 and 5 or a cross shape as shown in FIG. 6 .

The jig press device according to the present invention is configured such that a jig for pressurizing the upper surface of a battery cell is movable by a guide unit, so that the jig is moved to an area where defects due to tearing or folding of the separator are expected, and defects are possible Since the area is effectively pressurized, defective cells that may occur in the battery cell production process can be more accurately detected. In addition, by applying natural rubber or synthetic polymer material as the material of the jig, it is possible to pressurize the battery cell with a higher pressure by closely contacting it.

In one specific example, the jig press device of the present invention may further include a voltage measuring unit for measuring the voltage of the battery cell before/during/after pressing. By comparing voltages measured before/during/after pressurization, a cell in which a voltage drop is observed can be selected as a defective cell.

On the other hand, the present invention is a method for determining whether a battery cell is defective due to tearing or folding of a separator of a battery cell using the jig press device, and after placing the battery cell on the jig press device, the voltage (V1) process of measuring; moving a jig to a region where tearing of the separator or folding of the separator is expected to occur using the guide of the jig press device; pressing process; The process of measuring the voltage (V2); It provides a method for determining whether or not a battery cell is defective, comprising:

In one specific example, the above processes may be performed at room temperature. Conventionally, during the production process of a battery cell, a method of comparing a voltage measured before and after a degassing process to select a battery with a voltage drop as a defective one has been used. However, since the voltage measured after degassing is usually measured at a higher temperature than room temperature, the accuracy is lowered due to the voltage hunting phenomenon, which is measured at a higher value than the actual voltage. there was.

By using the jig press device of the present invention, voltages measured before/during/after pressing at room temperature can be compared to select defective cells based on whether or not the voltage drops and the degree thereof.

In one specific example, the pressure during pressurization may be 500 to 4000 kgf, more preferably 1000 to 3000 kgf, and most preferably 1500 to 2500 kgf. If the pressure at the time of pressurization is too low, it is difficult to detect defects due to folding or tearing of the separator, which is not preferable, and if the pressure is too high, it is not preferable because it may damage the electrode.

The pressing time may be 1 second to 60 seconds, more preferably 5 seconds to 40 seconds, and most preferably 10 seconds to 30 seconds. If the pressurization time is too short, a voltage drop sufficient to detect defects may not occur, and if the pressurization time is too long, the time required to detect defects increases, which is not preferable in terms of productivity.

Hereinafter, the present invention will be described in detail with reference to examples.

<Comparative Example>

An electrode assembly in which a separator was interposed between the positive and negative electrodes was inserted into a pouch case of a PET/Al/PE laminate sheet, and an electrolyte was injected and sealed to manufacture a battery cell. Thereafter, through a battery cell activation process, the manufacture of the battery cell was completed. Ten cells classified as normal cells with a voltage drop of 3 mV or less were selected.

<Example>

The battery cell classified as a normal cell in the comparative example was mounted in the jig press device of the present invention shown in FIG. 3 and the voltage was measured (V1). The resulting battery cell was then pressurized at room temperature with a pressure of 2000 kgf for 20 seconds. At this time, the jig was moved to the side of the battery cell where the separator was expected to be folded and pressurized. After the pressurization was completed, the voltage was measured (V2). The same operation was performed on 10 battery cells, and V1, V2 and the amount of voltage drop (V1-V2) of each battery cell were calculated, and the results are shown in Table 1. And those with a voltage drop of 3 mV or more were determined to be defective.

V1(V) V2(V) ΔOCV(mV,V1-V2) note One 3.55664 3.55573 0.91 error 2 3.56988 3.56984 0.04 3 3.56859 3.56864 -0.05 4 3.56964 3.56967 -0.03 5 3.56945 3.56956 -0.11 6 3.56874 3.56841 0.33 error 7 3.56599 3.56501 0.98 error 8 3.56948 3.56948 0.00 9 3.56924 3.56930 -0.06 10 3.57041 3.57037 0.04

<Experimental Example> Confirmation of separation membrane folding

All 10 battery cells of Comparative Examples and Examples were disassembled to determine whether the separator was folded. As a result, it was confirmed that the separator date was folded in battery cells No. 1, 6, and 7 that were determined to be defective according to the embodiment.

As described above, it can be seen that the method for screening whether the jig press device and the battery cell of the present invention have defects has an effect of detecting defective cells that could not be detected in the conventional screening process.

Claims (12)

A base plate on which a battery cell is seated;
a pressure plate installed above the base plate so as to be liftable and having a through hole;
a guide part that moves horizontally along the through hole of the pressure plate; and
a jig located on a lower end surface of the pressurization plate and coupled to a lower end surface of the guide part to move to a desired pressurized part in conjunction with the guide part and then pressurize the upper surface of the battery cell; including,
The through hole is formed at the center of the pressing plate and extends in a straight line in the width direction or the longitudinal direction of the pressing plate,
The jig press device having a structure in which the guide part is inserted into the through hole of the press plate, and the upper surface of the jig and the lower surface of the press plate are in contact with each other. A base plate on which a battery cell is seated;
a pressure plate installed above the base plate so as to be liftable and having a through hole;
a guide part that moves horizontally along the through hole of the pressure plate; and
a jig located on a lower end surface of the pressurization plate and coupled to a lower end surface of the guide part to move to a desired pressurized part in conjunction with the guide part and then pressurize the upper surface of the battery cell; including,
The through hole is formed in the center of the pressing plate and extends crosswise,
The jig press device having a structure in which the guide part is inserted into the through hole of the press plate, and the upper surface of the jig and the lower surface of the press plate are in contact with each other. According to claim 1 or 2,
A jig press device further comprising a voltage measuring unit for measuring the voltage of the battery cell before/during/after pressing. According to claim 1 or 2,
The jig press device, characterized in that the jig press device is made of natural rubber or synthetic polymer material, and has a structure attached by an adhesive to a portion in contact with the guide portion. According to claim 1 or 2,
The jig press device, characterized in that 10 to 30% of the flat area of the battery cell. According to claim 1 or 2,
The jig press device, characterized in that the jig has a thickness in the range of 1mm to 5mm. According to claim 1 or 2,
The pressurized portion is a jig press device, characterized in that the portion where tearing of the separator or folding of the separator of the battery cell is expected. A method for determining whether a battery cell is defective due to tearing or folding of a separator using the jig press device according to claim 1 or 2,
Step of measuring the voltage (V1) after positioning the battery cell on the jig press device;
moving a jig to a region where tearing of the separator or folding of the separator is expected to occur using the guide of the jig press device;
pressing process;
The process of measuring the voltage (V2);
A method for screening whether or not a battery cell is defective, comprising: According to claim 8,
A method for screening whether a battery cell is defective, characterized in that it is performed at room temperature. According to claim 8,
A method for determining whether a battery cell is defective, characterized in that the pressure at the time of pressurization is 1000 ~ 3000 kgf. According to claim 8,
A method for determining whether a battery cell is defective, characterized in that determining whether a battery cell is defective when a value obtained by subtracting the V2 from the V1 is 3 mV or more.
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