Plasma processing apparatus and lamination system for secondary batteries including the same

Abstract

The plasma processing apparatus for a unit cell of a secondary battery according to an embodiment of the present invention includes a discharge roller that transfers a separator of the unit cell of the secondary battery and houses a metal member, and a plasma processing member that generates plasma by mutual reaction with the metal member and irradiates the surface of the separator, and a pattern portion is formed on the outer surface of the discharge roller so as to have a predetermined step.

Description

[Technical Field]

[0001] The present invention relates to a plasma processing apparatus and a laminate system for secondary batteries including the same, and more particularly to a plasma processing apparatus and a laminate system for secondary batteries including the same that improve wettability by adjusting the adhesion strength between a separation film and an electrode.

[0002] This application claims priority based on Korean Patent Application No. 10-2022-0111700, filed on September 2, 2022, and all contents disclosed in the specification and drawings of said application are incorporated herein by reference. [Background technology]

[0003] Generally, a secondary battery, unlike a primary battery which cannot be recharged, is a battery that can be charged and discharged. Such secondary batteries are widely used in advanced electronic devices such as mobile phones, notebook PCs, and camcorders.

[0004] Secondary batteries are further classified into cylindrical secondary batteries in which the electrode assembly is housed in a metal can, pouch-type secondary batteries in which the electrode assembly is housed in a pouch, and prismatic secondary batteries, etc. The pouch-type secondary battery includes an electrode assembly, an electrolyte, and a pouch that houses the electrode assembly and the electrolyte. The electrode assembly has a positive electrode and a negative electrode arranged with a separator membrane in between, electrode tabs attached to the positive electrode and the negative electrode, and electrode leads connected to the electrode tabs.

[0005] On the other hand, the pouch-type secondary battery undergoes a lamination process to improve the adhesion of the electrode assembly, in which the electrodes and the separation film are stacked.

[0006] However, in conventional polymer cell manufacturing processes, the bicell is laminated at a constant temperature / pressure for process efficiency, which leads to a problem of reduced wettability at the interface between the electrode and the separation membrane.

[0007] In other words, if the adhesive force at the interface between the electrode and the separation membrane is constant and the electrode and the separation membrane are in uniform and completely tight contact overall, the electrolyte will not easily seep between the electrode and the separation membrane, making it difficult for the secondary battery to perform at its full potential.

[0008] In particular, under the same process conditions, the adhesive force at the interface between the positive electrode and the separation film becomes stronger, leading to a more significant decrease in wettability, and consequently, a noticeable deterioration in the performance of the secondary battery.

[0009] Furthermore, when the adhesive force between the electrode and the separation membrane interface is consistently high, it becomes difficult to smoothly discharge the gas generated during the formation process in the manufacturing of secondary batteries. If the gas is not discharged smoothly as a result, lithium plating occurs. [Overview of the project] [Problems that the invention aims to solve]

[0010] The present invention has been made in view of the above problems, and aims to provide a plasma processing apparatus and a laminate system for secondary batteries including the same, which improves the wettability of the electrolyte by partially weakening the adhesive force between the electrodes and the separation membrane of a unit cell used in the manufacture of a secondary battery, or by creating areas where adhesion does not occur.

[0011] Another objective of the present invention is to provide a plasma processing apparatus and a secondary battery lamination system including the same, which can minimize lithium plating phenomena by guiding the smooth discharge of gas from a unit cell.

[0012] However, the technical problems that this invention aims to solve are not limited to those described above, and other problems not mentioned will be clearly understood by those skilled in the art from the description of the invention below. [Means for solving the problem]

[0013] To achieve the above object, the present invention provides a plasma processing apparatus for a unit cell of a secondary battery, including a discharge roller that transfers a separation membrane of the unit cell of the secondary battery and incorporates a metal member, and a plasma processing member that generates plasma by mutual reaction with the metal member and irradiates the surface of the separation membrane. A pattern portion may be formed on the outer surface of the discharge roller so as to have a predetermined step.

[0014] Preferably, the pattern portion may include a contact portion that comes into close contact with the separation membrane during transfer of the separation membrane, and a non-contact portion that has a step of a predetermined depth from the contact portion and is separated from the separation membrane by a predetermined distance.

[0015] Preferably, when the plasma of the plasma processing member is irradiated, an adhesion region may be formed on the surface of the separation membrane disposed on the contact portion side, and an unadhered region may be formed on the surface of the separation membrane disposed on the non-contact portion side.

[0016] Preferably, the pattern portion may include a connecting portion that connects the contact portion and the non-contact portion.

[0017] Preferably, the contact portion and the non-contact portion may be alternately arranged on the outer surface of the discharge roller.

[0018] Preferably, the contact portion and the non-contact portion may be provided in at least one of the longitudinal direction and the width direction of the discharge roller.

[0019] Preferably, the non-contact portion may be formed to be recessed from the outer surface of the discharge roller by a predetermined depth.

[0020] Preferably, the depth of the recess of the non-contact portion may be 2 mm.

[0021] Preferably, the pattern portion may include a plurality of patterns having different lengths or widths.

[0022] Preferably, the multiple patterns may have different recess depths.

[0023] Preferably, the pattern portion may be provided in a mosaic shape.

[0024] Furthermore, the present invention includes a laminating system for secondary batteries, characterized by including a plasma processing apparatus according to the embodiments described above. [Effects of the Invention]

[0025] Through the various embodiments of the present invention described above, it is possible to provide a plasma processing apparatus and a laminate system for secondary batteries that include the same, which improves the wettability of the electrolyte by partially weakening the adhesive force between the electrodes and the separation membrane of a unit cell used in the manufacture of a secondary battery, or by creating areas where adhesion does not occur.

[0026] Furthermore, through the various embodiments of the present invention described above, it is possible to provide a plasma processing apparatus and a secondary battery lamination system including the same, which can minimize the lithium plating phenomenon by guiding the smooth discharge of gas from the unit cell.

[0027] Furthermore, various embodiments of the present invention can achieve other additional effects. These various effects of the present invention will be described in detail in each embodiment, and effects that are easily understood by those skilled in the art will not be described.

[0028] The following drawings accompanying this specification illustrate preferred embodiments of the invention and, together with the detailed description of the invention, serve to further illustrate the technical idea of ​​the invention. Therefore, the invention should not be construed as being limited solely to what is shown in the drawings. [Brief explanation of the drawing]

[0029] [Figure 1] This figure shows a unit cell for a secondary battery according to one embodiment of the present invention. [Figure 2]This figure shows a unit cell for a secondary battery according to one embodiment of the present invention. [Figure 3] This figure shows a positive electrode and a negative electrode applied to a unit cell for a secondary battery according to one embodiment of the present invention. [Figure 4] This figure shows a positive electrode and a negative electrode applied to a unit cell for a secondary battery according to one embodiment of the present invention. [Figure 5] This is a schematic diagram showing a secondary battery lamination system for manufacturing a secondary battery unit cell according to the present invention. [Figure 6] Figure 5 shows a plasma processing device for a laminate system for secondary batteries. [Figure 7] Figure 6 is a schematic perspective view of the plasma processing apparatus. [Figure 8] Figure 6 is a schematic perspective view showing how the separation membrane passes through the plasma processing apparatus. [Figure 9] Figure 8 is a cross-sectional view of the main part of the plasma processing apparatus. [Figure 10] This figure illustrates a plasma processing apparatus according to another embodiment of the present invention. [Figure 11] This figure illustrates an adhesion strength measurement test using a plasma processing apparatus according to one embodiment of the present invention. [Figure 12] Figure 11 is a diagram illustrating the results of the adhesive strength measurement test. [Figure 13] Figure 11 is a diagram illustrating the results of the adhesive strength measurement test. [Figure 14] Figure 11 is a diagram illustrating the results of the adhesive strength measurement test. [Figure 15] Figure 11 is a diagram illustrating the results of the adhesive strength measurement test. [Modes for carrying out the invention]

[0030] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings. Prior to this, terms and words used in this specification and in the claims should not be interpreted in a manner limited to their ordinary or dictionary meanings, but rather in a manner and concept that is in line with the technical idea of ​​the present invention, in accordance with the principle that the inventor himself can appropriately define the concepts of terms in order to best describe the invention.

[0031] Therefore, it should be understood that the embodiments and configurations shown in the drawings described herein represent only one of the most preferred embodiments of the present invention and do not represent the entirety of the technical concept of the present invention, and that there are various equivalents and modifications that can be substituted for them at the time of this application.

[0032] Figures 1 and 2 show a unit cell for a secondary battery according to one embodiment of the present invention, and Figures 3 and 4 show the positive electrode and negative electrode applied to the unit cell for a secondary battery according to one embodiment of the present invention.

[0033] Referring to Figures 1 to 4, a unit cell for a secondary battery according to one embodiment of the present invention includes a central electrode having a first polarity, a pair of separation membranes 3 laminated to both sides of the central electrode, and an upper electrode and a lower electrode having a second polarity opposite to the first polarity, each laminated to the pair of separation membranes.

[0034] A unit cell configured in such a way that the outermost electrodes have the same polarity is usually called a bicell.

[0035] Such bicell-type unit cells can be divided into positive-electrode bicells, as shown in Figure 1, where the upper and lower electrodes are positive electrodes 1 and the central electrode is negative electrode 2, and negative-electrode bicells, as shown in Figure 2, where the upper and lower electrodes are negative electrodes 2 and the central electrode is positive electrode 1.

[0036] The secondary battery configured using such bicells may have a form in which the positive electrode bicells and the negative electrode bicells are alternately stacked with a separator interposed therebetween. As such a stacking method of the bicells, a simple stacking method, a stacking / folding method, or the like may be applied.

[0037] The positive electrode 1 applied to the unit cell for a secondary battery according to an embodiment of the present invention is configured to include a positive electrode current collector 1a and a positive electrode active material 1b laminated on the surface thereof, as shown in FIG. 3.

[0038] As the positive electrode current collector 1a, a foil made of aluminum, nickel, or a combination of these materials may be used.

[0039] As the positive electrode active material 1b, a normal positive electrode active material used for the positive electrode of a secondary battery in the art can be used. Non-limiting examples thereof include LiCoO2, LiNiO2, LiMnO2, LiMn2O4, Li(Ni a Co b Mn c )O2 (0 < a < 1, 0 < b < 1, a + b + c = 1), LiNi 1-Y Co Y O2, LiCo 1-y Mn y O2, LiNi 1-y Mn y O2 (0 ≤ y < 1), Li(Ni a Co b Mn c )O4 (0 < a < 2, 0 < b < 2, a + b + c = 2), LiMn 2-z Ni z O4, LiMn 2-Z Co Z O_{4} (where 0 < Z < 2), LiCoPO4, LiFePO4, and mixtures thereof.

[0040] ' Further, the negative electrode 2 applied to the unit cell for a secondary battery according to an embodiment of the present invention is configured to include a negative electrode current collector 2a and a negative electrode active material 2b laminated on the surface thereof, as shown in FIG. 4.

[0041] As the negative electrode current collector 2a, a foil made of stainless steel, nickel, copper, titanium, or an alloy thereof can be used.

[0042] As the negative electrode active material 2b, ordinary negative electrode active materials used for the negative electrode of secondary batteries in the art can be used. Non-limiting examples thereof include carbon such as graphitizable carbon and graphite carbon; Li x Fe2O3 (0 ≦ x ≦ 1), Li x WO2 (0 ≦ x ≦ 1), Sn x Me 1-x Me’ y O z (Me: Mn, Fe, Pb, Ge; Me’: Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, halogen; 0 < x ≦ 1; 1 ≦ y ≦ 3; 1 ≦ z ≦ 8), etc. metal composite oxides; lithium metal; lithium alloys; silicon-based alloys; tin-based alloys; metal oxides such as SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4 and Bi2O5; conductive polymers such as polyacetylene; Li-Co-Ni-based materials, etc. can be used.

[0043] On the other hand, the separator 3 interposed between the positive electrode 1 and the negative electrode 2 can be embodied to include a porous coating layer formed on one or both surfaces of a porous polymer substrate.

[0044] The porous polymer substrate used for the separator 3 is not particularly limited as long as it is a planar porous polymer substrate usually applied to secondary batteries. The porous polymer substrate can be in the form of a film or a non-woven fabric.

[0045] The porous coating layer is formed on one or both sides of a porous polymer substrate, and inorganic particles are linked and fixed by a binder polymer for the porous coating layer, with micro-sized pores formed by the interstitial volume between the inorganic particles. The binder polymer for the porous coating layer is not particularly limited as long as it has excellent bonding strength with inorganic particles and is not easily dissolved by the electrolyte.

[0046] On the other hand, in a secondary battery unit cell according to one embodiment of the present invention, the adhesive force at the interface between the positive electrode 1 and the separation membrane 3 and / or the interface between the negative electrode 2 and the separation membrane 3 is not uniform overall, but rather has a patterned adhesive force. That is, the interface between electrodes 1 and 2 and the separation membrane 3 has different adhesive forces in different regions, resulting in different degrees of adhesion between electrodes 1 and 2 and the separation membrane 3 in different regions. The method for forming such a patterned adhesive force will be described in more detail below with reference to the drawings.

[0047] Figure 5 is a schematic diagram showing a secondary battery lamination system for manufacturing a secondary battery unit cell according to the present invention.

[0048] Referring to Figure 5, the secondary battery lamination system 10 may include a central electrode supply roller 100, a plasma processing device 200, an upper electrode supply roller 320, a lower electrode supply roller 330, a heater unit 400, a laminating roller 500, and cutter units 610, 620, 630, and 640.

[0049] The central electrode supply roller 100 can supply the central electrode E1 for the manufacture of unit cells. For this purpose, the central electrode supply roller 100 has a long, woven central electrode E1 wound around it so that it can be supplied.

[0050] The plasma processing apparatus 200 is for improving the adhesion, electrolyte impregnation, and gas discharge of the basic unit, which is the unit cell. Separation membranes S1 and S2 are supplied onto both sides of the central electrode E1, and plasma treatment is performed on the surfaces of the supplied separation membranes S1 and S2 to modify the surface of the separation membranes S1 and S2, thereby increasing the adhesion force with electrodes E1, E2, and E3.

[0051] The plasma processing apparatus 200 of the aforementioned secondary battery laminating system 10 will be described in more detail below.

[0052] Figure 6 shows the plasma processing apparatus for the secondary battery lamination system shown in Figure 5; Figure 7 is a schematic perspective view of the plasma processing apparatus shown in Figure 6; Figure 8 is a schematic perspective view showing the passage of the separation membrane in the plasma processing apparatus shown in Figure 6; and Figure 9 is a cross-sectional view of the main part of the plasma processing apparatus shown in Figure 8.

[0053] Referring to Figures 6 to 9, the plasma processing apparatus 200 may include discharge rollers 220 and 230, each containing a metal member 240, which transport the separation membranes S1 and S2 of the secondary battery unit cell, and a plasma processing member 260 that generates plasma through interaction with the metal member 240 and irradiates the surface of the separation membranes S1 and S2. Here, a pattern portion 250 (see Figures 7 to 9) having a predetermined step can be formed on the outer surface of the discharge rollers 220 and 230.

[0054] The pattern portion 250, which is provided on the outer surface of the discharge rollers 220 and 230 to have a predetermined step, allows the plasma processing apparatus 200 according to this embodiment to perform a patterned plasma treatment in which plasma treatment is performed on a portion of the surface of the separation membranes S1 and S2, while the remaining portion is not treated. That is, the plasma processing apparatus 200 can activate a uniform and patterned adhesive force on the surface of the separation membranes S1 and S2 so that the electrodes E1, E2, and E3 and the separation membranes S1 and S2 are pattern-bonded.

[0055] The discharge rollers 220 and 230 may include a first discharge roller 220 and a second discharge roller 230.

[0056] The first discharge roller 220 is for transporting one separation membrane S1 and may have the metal member 240 inside. The second discharge roller 230 is for transporting another separation membrane S2 and may have the metal member 240 inside.

[0057] The plasma processing member 260 is provided so as to be separated from the separation membranes S1 and S2, and can generate plasma P through interaction with the metal member 240 and irradiate the surfaces of the separation membranes S1 and S2.

[0058] Such a plasma processing member 260 may include a processing member body 261, an electrode piece 264, and a switch 265.

[0059] The processing member body 261 is provided so as to be separated from the respective separation membranes S1 and S2, and may be provided in the width direction of the separation membranes S1 and S2. Such a processing member body 261 may be made of a non-metallic material, thereby preventing the generation of resistance between the metal member 240 and the electrode piece 264. As a result, plasma P can be stably generated between the metal member 240 and the processing member body 261.

[0060] The processing member body 261 may be made of a nonmetallic material, specifically a ceramic. This ceramic is a nonmetallic inorganic material obtained through a heat treatment process, possessing heat resistance, high strength, and corrosion resistance, and is particularly lightweight, which can improve efficiency of use.

[0061] The electrode piece 264 may be a corona discharge electrode, and the corona discharge electrode can stably generate plasma P between the metal member 240 and the processing member body 261.

[0062] The electrode piece 264 may be formed from a plurality of unit electrode pieces, and the plurality of unit electrode pieces can be connected on the processing member body 261 along the width direction of the separation membranes S1 and S2 to form a single electrode piece 264, thereby enabling interchangeable use for separation membranes having various widths.

[0063] On the other hand, the multiple unit electrode pieces may be provided spaced apart on the main body 261 of the processing member along the width direction of the separation films S1 and S2. This feature allows for partial generation of plasma P between the metal member 240 and the main body 261 of the processing member, and as a result, it is possible to realize a patterned adhesive force on the surface of the separation films S1 and S2.

[0064] The plurality of unit electrode pieces may be provided with the same length, width, and thickness, or they may be provided with one or more of the length, width, and thickness differing, thereby enabling the realization of diverse patterns of adhesive force on the surfaces of the separation films S1 and S2.

[0065] On the other hand, the processing member body 261 has an insertion groove 263 that is elongated in the width direction of the separation membranes S1 and S2, and the electrode piece 264 can be inserted into and fixed in the insertion groove 263, thereby preventing damage to the electrode piece 264 from external objects, and as a result, plasma P can be generated stably.

[0066] The switch 265 can apply power to the electrode piece 264. The switch 265 can easily adjust whether or not the electrode piece 264 is used by controlling the power supplied to the electrode piece 264, thereby preventing unnecessary power consumption.

[0067] In the plasma processing member 260 with this configuration, plasma P is generated with the metal member 240 and the electrode piece 264 in correspondence, and the plasma P is irradiated onto the surface of the separation films S1 and S2 between the metal member 240 and the electrode piece 264, thereby creating an adhesive force on the separation films S1 and S2.

[0068] The specific configuration and related mechanisms for realizing the patterned adhesive force by the plasma processing apparatus 200 according to this embodiment will be described in more detail below.

[0069] The pattern portion 250 is formed on the surface 221 of the discharge roller 220 and may be provided in a mosaic shape. Although not shown, the pattern portion 250 is also formed on the surface of the second discharge roller 230 that transports the other separation membrane S2. On the other hand, for the sake of explanation, the following description will focus on the pattern portion 250 provided on the first discharge roller 220 corresponding to the one separation membrane S1.

[0070] Such a pattern portion 250 may include a contact portion 252 and a non-contact portion 254.

[0071] The contact portion 252 is provided on the surface of the discharge roller 220 and can be in close contact with the separation membrane S1 when the separation membrane S1 is being transported. The non-contact portion 254 has a step of a predetermined depth h from the contact portion 252 and can be separated from the separation membrane S1 by a predetermined distance.

[0072] For this purpose, the non-contact portion 254 may be formed as a recess in the outer surface 221 of the discharge roller 220 to a predetermined depth h. For example, the depth of the recess of the non-contact portion 254 may be approximately 2 mm.

[0073] The contact portion 252 and the non-contact portion 254 are alternately arranged on the outer surface of the discharge roller 220, specifically the first discharge roller 220, and can form a predetermined pattern on the surface of the discharge roller 220. The predetermined pattern can be provided in various ways according to pre-set design conditions depending on the shape and size of the separation membrane S1.

[0074] For example, the contact portion 252 and the non-contact portion 254 may be provided in at least one direction of the longitudinal and width directions of the discharge roller 220. Furthermore, a plurality of contact portions 252 and non-contact portions 254 may be provided. The plurality of contact portions 252 may be spaced apart from each other by a predetermined distance and may have a preset separation distance. The plurality of non-contact portions 254 may be formed by etching from the outer surface 221 of the discharge roller 220 and may have a preset etching length, etching width, and etching depth. At least some of the plurality of non-contact portions 254 may have different etching lengths and etching widths.

[0075] Depending on the various arrangements and shapes of the contact portion 252 and the non-contact portion 254, a variety of patterns can be realized on the surface 221 of the discharge roller 220, and it can be applied to separation films S1 of various sizes, and various adhesive strengths of different patterns can be realized depending on the required design.

[0076] The pattern portion 250 may include a connecting portion 256 that connects the contact portion 252 and the non-contact portion 254. The connecting portion 256 can guide the pattern portion 250 so that a pattern with an uneven surface can be formed while connecting the contact portion 252 and the non-contact portion 254.

[0077] Therefore, in this embodiment, the pattern portion 250 formed on the surface 221 of the first discharge roller 220 can divide the separation membrane S1 being transported on the first discharge roller 220 into a region in close contact with the pattern portion 250 and a region separated from the pattern portion 250. In the separation membrane S1, the region in close contact with the pattern portion 250 is the region located in the contact portion 252, and the region separated from the pattern portion 250 may be the region located in the non-contact portion 254.

[0078] Here, the region of the separation film S1 positioned on the contact portion 252 is in closer contact with the first discharge roller 220 than the region of the separation film S1 positioned on the non-contact portion 254. Therefore, when the plasma P is irradiated, it exhibits smoother interaction with the metal member 240, making it possible to form an adhesive region with high adhesive strength. On the other hand, the region of the separation film S1 positioned on the non-contact portion 254 is separated from the surface of the first discharge roller 220. Therefore, when the plasma P is irradiated, the interaction with the metal member 240 weakens, resulting in an unadhered region with low adhesive strength.

[0079] Thus, when the plasma of the plasma processing member 260 is irradiated with plasma through the pattern portion 250, an adhesive region A1 may be formed on the surface of the separation film S1 located on the contact portion 252 side, and an unadhered region A2 may be formed on the surface of the separation film located on the non-contact portion 254 side.

[0080] The bonded areas A1 and the unbonded areas A2 are arranged alternately, thereby creating a mosaic-like patterned adhesive force in which the bonded areas A1 and the unbonded areas A2 are formed alternately.

[0081] As a result, the plasma processing apparatus 200 according to this embodiment can form a mask with patterned adhesive strength by forming an adhesive region A1 and an unadhered region A2 on the surface of the separation films S1 and S2 using the patterned portion 250 formed on the surfaces of the discharge rollers 220 and 230.

[0082] Adhesion between materials can be divided into chemical adhesion and mechanical interlocking. The improvement in adhesive strength by plasma treatment, as in this invention, is a phenomenon that occurs when chemical adhesion is strengthened. Examples of chemical adhesion include electrostatic attraction, chemical adsorption, and chemical bonding. When a part of the surface of the separation membrane S1 is treated with plasma P, as in this invention, the treated region A1 undergoes surface modification, such as changing bonding structures from CH, C=C, CC to CO, C=O, OCO, OC=O, thereby strengthening electrostatic attraction, chemical adsorption, and chemical bonding. On the other hand, the region A2 that has not been treated with plasma P has relatively weaker adhesive strength, and the impregnation of the electrolyte is improved in that region.

[0083] Figure 10 is a diagram illustrating a plasma processing apparatus according to another embodiment of the present invention.

[0084] Since the plasma processing apparatus 205 according to this embodiment is similar to the plasma processing apparatus 200 of the previously described embodiment, redundant explanations of configurations that are substantially the same or similar to those of the previously described embodiment will be omitted, and the following explanation will focus on the differences from the previously described embodiment.

[0085] Referring to Figure 10, the plasma processing apparatus 205 can form patterned portions 290 having different lengths, widths, separation distances, and etching depths, as described above, by designing the unit cells in advance.

[0086] Specifically, the pattern portion 290 may include a plurality of patterns having different lengths and widths. Here, the plurality of patterns may be formed to have different recess depths.

[0087] As described above, the plasma processing apparatus 200 according to one embodiment of the present invention, by forming a mosaic-shaped set of steps on the surfaces of the discharge rollers 220 and 230, performs plasma processing with a uniform distribution throughout the longitudinal and widthwise directions of the separation membranes S1 and S2, thereby realizing a uniform mosaic pattern corona treatment and significantly improving the adhesion of the basic unit cells, the impregnation of the electrolyte, and the gas discharge performance.

[0088] Furthermore, the plasma processing apparatus 200 according to one embodiment of the present invention can significantly improve gas discharge performance as described above, and therefore can effectively prevent lithium plating (Li plating) phenomena.

[0089] Referring also to Figure 5, the upper electrode supply roller 320 is for supplying the upper electrode E2 in the form of a long woven fabric, and can supply the upper electrode E2 onto the plasma-treated separation membranes S1 and S2.

[0090] The lower electrode supply roller 330 is for supplying a long, woven lower electrode E3, and is positioned opposite the upper electrode supply roller 320, and can supply the lower electrode E3 onto the plasma-treated separation membranes S1 and S2.

[0091] The heater unit 400 is for guiding the adhesion between the separation membranes S1 and S2 and the upper electrode E2 and the lower electrode E3, and can heat the upper electrode E2 and the lower electrode E3 placed on the separation membranes S1 and S2 by applying heat.

[0092] The laminating roller 500 can apply pressure to the upper electrode E2 and lower electrode E3, which are bonded to the separation membranes S1 and S2 heated by the heater unit 400, thereby pressing the electrodes together with the separation membranes.

[0093] The cutter units 610, 620, 630, and 640 can perform predetermined cutting on each of the supplied fabric-formed central electrode E1, upper electrode E2, lower electrode E3, and separation membranes S1 and S2.

[0094] Such cutter units 610, 620, 630, and 640 may include a first cutter 610, a second cutter 620, a third cutter 630, and a fourth cutter 640.

[0095] The first cutter 610 can cut the central electrode E1 to a predetermined size. The second cutter 620 can cut at least one of the upper electrode E2 and the separator membrane S1, and the third cutter 630 can cut at least one of the lower electrode E3 and the separator membrane S2. The fourth cutter 640 can cut electrodes E1, E2, E3 and separator membranes S1, S2 respectively so that a basic unit, a secondary battery unit cell, can be manufactured.

[0096] Although not shown in the diagram, the manufacturing process for the secondary battery unit cell may further include a step of inspecting and discharging the completed secondary battery unit cell after lamination is finished.

[0097] Here, unit cell inspection refers to inspections conducted during the lamination process for manufacturing unit cells, such as checking for the presence of foreign matter between the electrode and the separation membrane, and whether the unit cell was manufactured to the correct size.

[0098] As described above, the unit cells for secondary batteries manufactured by the plasma processing apparatus 200, 205 according to this embodiment do not have uniformly uniform adhesive forces at the interface between the positive electrode 1 and the separation membrane 3 and / or the interface between the negative electrode 2 and the separation membrane 3, and may have patterned adhesive forces. That is, the interface between the electrodes 1, 2 and the separation membrane 3 may have different adhesive forces in different regions, resulting in different degrees of adhesion between the electrodes 1, 2 and the separation membrane 3 in different regions.

[0099] The results of an adhesion strength measurement test using a plasma processing apparatus according to one embodiment of the present invention will be described below with reference to the drawings shown.

[0100] Figure 11 is a diagram illustrating an adhesion strength measurement test using a plasma processing apparatus according to one embodiment of the present invention, and Figures 12 to 15 are diagrams illustrating the adhesion strength measurement test results of Figure 11.

[0101] Referring to Figures 11 to 15, first, Reference (indicated as Ref. in Figures 12 and 15) represents corona treatment of the entire area, while Test #2 and Test #3 represent mosaic corona treatment. Figure 11 shows the measurement of the face-to-face adhesion force of the folded negative electrode on the products of Test #2 and Test #3. The adhesion force is measured at positions 1 to 5 in the drawing, with position 1 on the tab side, positions 2 to 4 in the center, and position 5 on the lower end. Also, in Figure 11, the corona-treated area, i.e., the mosaic corona-treated area, is shown as a rectangular box shape. The Bi-cell numbers 2, 3, 6, 7, 10, and 11 shown in Figure 15 are positions within the cell due to the Bi-cell lamination.

[0102] In Figure 11, in Test #2, mosaic corona processing was performed on a total of two regions: the tab side (No. 1) and the lower end side (No. 5). In Test #3, mosaic corona processing was performed on a total of six regions: the tab side (No. 1), the lower end side (No. 5), the central part (Nos. 2 and 4), the space between the central part (No. 2) and the tab side (No. 1), and the space between the central part (No. 4) and the lower end side (No. 5).

[0103] As shown in Figures 12 to 15, the adhesion strength of the folded separation membrane to the negative electrode in the untreated mosaic corona region of the Test #2 and Test #3 products is low, at approximately 5 gf. In Test #3, the adhesion strength improves in areas 2 and 4, i.e., the central area (areas 2 and 4), when the mosaic corona-treated region is present. The adhesion strength improves from approximately 5 gf to 16 gf.

[0104] From the various embodiments of the present invention described above, it is possible to provide plasma processing apparatuses 200, 205 and a secondary battery lamination system 10 including them, which can improve the wettability of the electrolyte by making the adhesive force between the electrodes and the separation membrane of a unit cell used in the manufacture of a secondary battery weak in some areas, or by making areas that are not adhered at all.

[0105] Furthermore, from the various embodiments of the present invention described above, it is possible to provide plasma processing apparatuses 200, 205 and a secondary battery lamination system 10 including them, which can minimize the lithium plating phenomenon by guiding the smooth discharge of gas from the unit cell.

[0106] As described above, the present invention has been explained with limited embodiments and drawings, but the present invention is not limited thereto, and of course, various modifications and variations are possible within the equivalent scope of the technical concept and claims of the present invention by persons with ordinary skill in the art to which the present invention belongs.

[0107] In this specification, terms indicating direction such as up, down, left, right, front, and back are used, but these terms are for the sake of convenience of explanation only, and it is obvious to those skilled in the art that the direction can change depending on the position of the object in question, the position of the observer, etc. [Explanation of symbols]

[0108] 1. Positive electrode, electrode 1a Positive electrode current collector 1b Cathode active material 2 Negative electrode, electrode 2a Negative electrode current collector 2b Anode active material 3 Separation membrane 10 Laminating systems for secondary batteries 100 Central electrode supply roller 200 Plasma Processing Equipment 205 Plasma Processing Equipment 220 First discharge roller 221 Surface 230 Second discharge roller 240 Metal parts 250 Pattern section 252 Contact area 254 Non-contact part 256 Connection section 260 Plasma-treated components 261 Processing component body 263 Insertion groove 264 Electrode piece 265 switches 290 Pattern section 320 Upper electrode supply roller 330 Lower electrode supply roller 400 Heater Unit 500 Laminating Rollers 610 First Cutter 620 Second Cutter 630 Third Cutter 640 No. 4 Cutter

Claims

1. A plasma processing apparatus for a unit cell of a secondary battery, The separation membrane of the secondary battery unit cell is transported by a discharge roller containing a metal component, A plasma processing member that generates plasma through interaction with the aforementioned metal member and irradiates the surface of the separation film with it, The outer surface of the discharge roller is formed with a patterned portion having a predetermined step, A plasma processing apparatus characterized in that the pattern portion includes a plurality of patterns having different lengths or widths.

2. The aforementioned pattern portion, A contact portion that comes into close contact with the separation membrane during transport, The plasma processing apparatus according to claim 1, characterized in that it includes a non-contact portion having a step of a predetermined depth from the contact portion and separated from the separation membrane at a predetermined distance.

3. The plasma processing apparatus according to claim 2, characterized in that when the plasma processing member is irradiated with plasma, an adhesive region is formed on the surface of the separation membrane located on the contact side, and an unadhered region is formed on the surface of the separation membrane located on the non-contact side.

4. The plasma processing apparatus according to claim 2, characterized in that the pattern portion includes a connecting portion that connects the contact portion and the non-contact portion.

5. The plasma processing apparatus according to claim 2, characterized in that the contact portion and the non-contact portion are alternately arranged on the outer surface of the discharge roller.

6. The plasma processing apparatus according to claim 2, characterized in that the contact portion and the non-contact portion are provided in at least one direction of the longitudinal direction and the width direction of the discharge roller.

7. The plasma processing apparatus according to claim 2, characterized in that the non-contact portion is formed by being recessed to a predetermined depth from the outer surface of the discharge roller.

8. The plasma processing apparatus according to claim 7, characterized in that the depth of the recess in the non-contact portion is 2 mm.

9. The plasma processing apparatus according to claim 1, characterized in that the plurality of patterns have different recess depths.

10. The plasma processing apparatus according to claim 1, characterized in that the pattern portion is provided in a mosaic shape.

11. A laminating system for secondary batteries, characterized by including the plasma processing apparatus described in claim 1.

Images