Unit electrode, method for manufacturing same, and stacked cell including same

Abstract

An embodiment of the present invention provides a unit electrode, a method for manufacturing same, and a stack cell including same, in which the unit cell facilitates storage and transportation and reduces process defects such as winding misalignment and positional errors in an alignment process, and comprises: a current collector; a first active material layer located on the current collector; a second active material layer located under the current collector; an upper separator including a first upper separator located on the first active material layer and second upper separators extending outward from both sides of the first upper separator, respectively; and a lower separator including a first lower separator located under the second active material layer and second lower separators extending outward from both sides of the first lower separator, respectively, wherein the second upper separators and the second lower separators are coupled to each other while surrounding the sides of the current collector, the first active material layer, and the second active material layer.

Description

Unit electrode, method of manufacturing the same, and stacked cell including the same

[0001] The present invention relates to a unit electrode, and more specifically, to a unit electrode manufactured by wrapping it with a separator, a method for manufacturing the same, and a stacked cell including the same.

[0002] The battery assembly process is a core process that combines electrodes and separators to form a cell, thereby enabling electrochemical performance. Currently, the assembly processes commercialized for lithium-ion batteries mainly consist of winding and stacking processes.

[0003] The winding process involves aligning the anode, cathode, and separator into long strips and then winding them like a roll to form a stack. While this method offers the advantage of high processing speed and suitability for mass production due to the ability to perform a roll-to-roll process, it poses a risk of separator damage. This is because the structural stress distribution between electrodes is asymmetric, and bending at corners can lead to microcracks or wrinkles. Such separator damage is a major cause of internal short circuits and reduced safety. Furthermore, as the cell size increases, there is a risk of cell expansion or internal short circuits due to pressure differences between the center and the outer edges of the wound structure. Additionally, there are limitations to improving energy density due to the limited planar contact surface area.

[0004] The stacking process is a method of forming a cell by cutting unit electrodes and separators into individual sheets and stacking them sequentially. While it has the advantage of high energy density and efficient space utilization due to the large planar contact surface, it has the disadvantages of slow process speed and difficulty in high-speed automation. In particular, during the process of transporting or stacking thin, electrostatically sensitive separators at high speeds, the process defect rate can increase due to disturbances such as minute positional errors, static electricity, or the ingress of foreign substances. Furthermore, as the cell size increases, the cumulative alignment error rate may increase due to the increase in the number of stacks, which directly leads to problems such as increased defect rates, reduced uniformity of cell quality, and reduced cell safety.

[0005] Although the separator is thin and flexible, allowing for smooth ion diffusion within the cell, it is difficult to achieve precise alignment with the electrode in conventional winding and stacking processes, and there is a high possibility of structural problems such as wrinkling or creasing.

[0006] These issues hinder the electrodes and separators from maintaining a consistent gap, which can lead to adverse effects such as increased internal cell resistance, localized current concentration (hot spots), and electrochemical reaction imbalances. Additionally, as the separator deforms, electrolyte penetration becomes non-uniform in specific areas, potentially degrading the cell's thermal stability during long-term charging and discharging cycles.

[0007] These drawbacks not only degrade battery performance but also lead to reduced productivity and increased defect rates in the manufacturing process, thereby raising manufacturing costs. Therefore, there is a need for technology that can ensure separator stability and enhance productivity while maintaining battery performance. To overcome the problems of existing processes, there is a growing need for a new assembly method suitable for automation and mass production, while ensuring separator stability and a more precise and consistent stacking structure.

[0008] [Prior Art Literature]

[0009] (Patent Document 0001) Republic of Korea Published Patent No. 10-2023-0134049

[0010] The technical problem to be solved by the present invention is to provide a unit electrode. More specifically, the present invention provides a method for manufacturing a unit electrode capable of securing a precise and consistent stacked structure by wrapping the unit electrode with a separator, and a unit electrode manufactured by said method.

[0011] Another technical objective of the present invention is to provide a stacked cell comprising the unit electrode described above.

[0012] The technical problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned technical problems will be clearly understood by those skilled in the art to which the present invention belongs from the description below.

[0013] To achieve the above technical objective, one embodiment of the present invention provides a unit electrode comprising: a current collector; a first active material layer located above the current collector; a second active material layer located below the current collector; an upper separator comprising a first upper separator located above the first active material layer and a second upper separator extending outwardly from both sides of the first upper separator; and a lower separator comprising a first lower separator located below the second active material layer and a second lower separator extending outwardly from both sides of the first lower separator.

[0014] The above-mentioned second upper separator and second lower separator may be characterized by a structure in which they are mutually bonded while wrapping around the sides of the current collector, the first active material layer, and the second active material layer.

[0015] The structure in which the second upper separator and the second lower separator are mutually coupled may be characterized in that the lower part of the second upper separator and the upper part of the second lower separator are heat-pressed together to be mutually coupled.

[0016] The structure in which the second upper separator and the second lower separator are interconnected may be characterized by blocking direct contact between the anode and the cathode.

[0017] The above unit electrode may be characterized as being a negative unit electrode or a positive unit electrode.

[0018] When the above unit electrode is a negative unit electrode, the above current collector is characterized as being a negative current collector, and the above first active material layer and the above second active material layer may be characterized as including a negative active material.

[0019] When the above unit electrode is a positive unit electrode, the above current collector is characterized as being a positive current collector, and the above first active material layer and the above second active material layer may be characterized as including a positive active material.

[0020] To achieve the above technical objective, another embodiment of the present invention provides a method for manufacturing a unit electrode comprising: a step of preparing a current collector; a step of forming a first active material layer on the upper part of the current collector; a step of forming a second active material layer on the lower part of the current collector; a step of forming an upper separator on the upper part of the first active material layer, comprising a first upper separator and a second upper separator extending outwardly from both sides of the first upper separator; a step of forming a lower separator on the lower part of the second active material layer, comprising a first lower separator and a second lower separator extending outwardly from both sides of the first lower separator; and a step of combining the second upper separator and the second lower separator.

[0021] The step of mutually combining the second upper separator and the second lower separator may be characterized by combining the lower part of the second upper separator and the upper part of the second lower separator by heat-pressing so as to surround the side of the current collector, the first active material layer, and the second active material layer.

[0022] The above unit electrode may be characterized as being a negative unit electrode or a positive unit electrode.

[0023] When the above unit electrode is a negative unit electrode, the above current collector is characterized as being a negative current collector, and the above first active material layer and the above second active material layer may be characterized as including a negative active material.

[0024] When the above unit electrode is a positive unit electrode, the above current collector is characterized as being a positive current collector, and the above first active material layer and the above second active material layer may be characterized as including a positive active material.

[0025] To achieve the above technical objective, another embodiment of the present invention provides a stacked cell comprising: the above-described cathode unit electrode; the above-described anode unit electrode located on the cathode unit electrode; and an electrolyte.

[0026] The above electrolyte may be characterized by being located between the above cathode unit electrode and the above anode unit electrode.

[0027] The unit electrode of the present invention can block direct contact between the positive and negative electrodes by wrapping both sides of the battery electrode with a separator and packaging it. Since it is individually packaged with a separator, storage and transportation are easy, and accurate alignment can be achieved without creasing during the assembly process, thereby reducing the defect rate.

[0028] In addition, since two structurally thin layers of separators are placed at the locations where the anode and cathode cause electrochemical reactions, the cell internal resistance is lower than that of a conventional single separator, so the electrochemical reaction can be induced uniformly and stably.

[0029] The effects of the present invention are not limited to the effects described above, and should be understood to include all effects that can be inferred from the configuration of the invention described in the detailed description of the invention or the claims.

[0030] Figure 1 is a cross-sectional view showing the cathode unit electrode of the present invention.

[0031] FIG. 2 is a cross-sectional view showing the anode unit electrode of the present invention.

[0032] FIG. 3 is a cross-sectional view showing a stacked cell in which the unit electrodes of the present invention are continuously stacked.

[0033] FIG. 4 is a cross-sectional view showing a unit cell, which is the minimum unit in which the positive and negative electrodes react in a battery to which the unit electrode of the present invention is applied.

[0034] FIG. 5 is a flowchart showing the method for manufacturing a unit electrode of the present invention.

[0035] Figure 6 is a graph showing the results of a symmetric cell test prepared according to Comparative Example 1 and Manufacturing Example 1 of the present invention.

[0036] FIG. 7 is a graph showing (a) average charging voltage and (b) average discharging voltage in a symmetric cell test prepared according to Comparative Example 1 and Manufacturing Example 1 of the present invention.

[0037] FIG. 8 is a graph showing the half-cell test results prepared according to (a) Comparative Example 2 and (b) Manufacturing Example 2 of the present invention.

[0038] Figure 9 is a graph showing the long-life characteristic test results of half cells manufactured according to Comparative Example 2 and Manufacturing Example 2 of the present invention.

[0039] Figure 10 is a graph showing the results of a rate capability test of a half cell prepared according to Comparative Example 2 and Manufacturing Example 2 of the present invention.

[0040] The present invention will be described below with reference to the attached drawings. However, the present invention may be implemented in various different forms and is therefore not limited to the embodiments described herein. Furthermore, in order to clearly explain the present invention in the drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification have been given similar reference numerals.

[0041] Throughout the specification, when it is stated that a part is "connected (connected, in contact, combined)" with another part, this includes not only cases where they are "directly connected," but also cases where they are "indirectly connected" with other members interposed between them. Furthermore, when it is stated that a part "includes" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but rather allows for the inclusion of additional components.

[0042] The terms used herein are merely for describing specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as “comprising” or “having” are intended to indicate the presence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0043] Embodiments of the present invention will be described in detail below with reference to the attached drawings.

[0044]

[0045] A unit electrode according to an embodiment of the present invention will be described with reference to FIGS. 1 to 4.

[0046] FIG. 1 is a cross-sectional view showing the cathode unit electrode (1) of the present invention.

[0047] FIG. 2 is a cross-sectional view showing the positive unit electrode (2) of the present invention.

[0048] FIG. 3 is a cross-sectional view showing a stacked cell in which the unit electrodes of the present invention are continuously stacked.

[0049] FIG. 4 is a cross-sectional view showing a unit cell, which is the minimum unit in which the positive and negative electrodes react in a battery to which the unit electrode of the present invention is applied.

[0050] Referring to FIGS. 1 to 4, the unit electrode of the present invention comprises: a current collector (100 or 400); a first active material layer (200 or 500) in close contact with the upper portion of the current collector (100 or 400); a second active material layer (300 or 600) in close contact with the lower portion of the current collector (100 or 400); and an upper separator (210 or 510) comprising a first upper separator (211 or 511) in close contact with the upper portion of the first active material layer (200 or 500) and a second upper separator (212 or 512) extending outwardly from each side of the first upper separator (211 or 511). It may include a lower separator (310 or 610) comprising a first lower separator (311 or 611) that is in close contact with the lower part of the second active material layer (300 or 600) and a second lower separator (312 or 612) that extends outwardly from each side of the first lower separator (311 or 611).

[0051] The unit electrode described above may be a negative unit electrode (1) or a positive unit electrode (2).

[0052] The case where the above unit electrode is a negative unit electrode (1) is explained.

[0053] The current collector (100) may be selected from the group consisting of copper (Cu), aluminum (Al), nickel (Ni), iron (Fe), zinc (Zn), tungsten (W), palladium (Pd), silver (Ag), gold (Au), platinum (Pt), lithium (Li), tin (Sn), chromium (Cr), molybdenum (Mo), germanium (Ge), zirconium (Zr), niobium (Nb), tantalum (Ta), indium (In), titanium (Ti), and stainless steel (SUS), their oxides, nitrides, carbides, alloys thereof, and combinations thereof. Additionally, the current collector may include a current collector that has undergone surface treatment such as plasma treatment, electrochemical treatment, or metal or ceramic coating to improve mechanical strength, electrical conductivity, and electrode stability. In addition, various forms may be used, such as films, sheets, foils, nets, porous materials, foams, nonwoven materials, woven fibers, three-dimensional structures, or laminate structures, with or without fine irregularities formed on the surface. However, it is not limited to the above examples.

[0054] For example, the current collector (100) of the cathode unit electrode (1) according to the present invention may be a copper metal foil.

[0055] The first active material layer (200) and the second active material layer (300) are graphite, hard carbon, soft carbon, silicon, silicon-carbon composite, graphite-silicon composite, tin, tin-cobalt alloy, tin-copper alloy, lithium metal, lithium-metal alloy, titanate-based (Li4Ti5O) 12It may include carbon nanotube composites, graphite-metal composites, graphite-conductive polymer composites, or combinations thereof (e.g., TiO2), graphite-metal composites, graphite-conductive polymer composites, or combinations thereof. Additionally, the active material layer may include a binder and a conductive material, may further form an inactive or protective layer, may include a structure coated on a current collector or may include a pre-lithiated active material, and may be formed to have a nanostructure or a porous structure. However, it is not limited to the above examples.

[0056] For example, the first active material layer (200) and the second active material layer (300) of the cathode unit electrode (1) according to the present invention may be formed of a carbon-based active material such as graphite.

[0057] The upper separator (210) and the lower separator (310) may include polyethylene (PE), polypropylene (PP), polyimide (PI), polybenzimidazole (PBI), aramid, cellulose, glass fiber, polymer ceramic composite membrane, alumina (Al₂O₃) coated separator, silica (SiO₂) coated separator, boron-based (BN, etc.) inorganic coating membrane, ceramic-polymer hybrid separator, PVDF (Polyvinylidene fluoride), PAN (Polyacrylonitrile), PEO (Polyethylene oxide), polysulfone, PVDF-HFP copolymer, nitrogen-doped polymer separator, electrolyte-impregnated solid polymer membrane, porous nanofiber-based separator, CNT composite separator, ion-conducting polymer separator, polymer-ionic liquid composite membrane, metal oxide coated separator, multilayer sandwich separator, thermal insulation functional separator, functional surface-modified separator, etc. However, it is not limited to the examples above.

[0058] For example, the upper separator (210) and lower separator (310) of the cathode unit electrode (1) according to the present invention may be polyethylene (PE).

[0059] The case where the above unit electrode is a positive unit electrode (2) is explained.

[0060] The current collector (400) may be selected from the group consisting of copper (Cu), aluminum (Al), nickel (Ni), iron (Fe), zinc (Zn), tungsten (W), palladium (Pd), silver (Ag), gold (Au), platinum (Pt), lithium (Li), tin (Sn), chromium (Cr), molybdenum (Mo), germanium (Ge), zirconium (Zr), niobium (Nb), tantalum (Ta), indium (In), titanium (Ti), and stainless steel (SUS), their oxides, nitrides, carbides, alloys thereof, and combinations thereof. Additionally, the current collector may include a current collector that has undergone surface treatment such as plasma treatment, electrochemical treatment, or metal or ceramic coating to improve mechanical strength, electrical conductivity, and electrode stability. In addition, various forms may be used, such as films, sheets, foils, nets, porous materials, foams, nonwoven materials, woven fibers, three-dimensional structures, or laminate structures, with or without fine irregularities formed on the surface. However, it is not limited to the above examples.

[0061] For example, the current collector (400) of the positive unit electrode (2) according to the present invention may be an aluminum metal foil.

[0062] The first active material layer (500) and the second active material layer (600) are lithium cobalt oxide (LiCoO₂) and nickel manganese cobalt oxide (NMC). 111 , NMC 532 , NMC 622 , NMC 811 ), nickel cobalt aluminum oxide (NCA), lithium manganese oxide (Spinel LMO), lithium iron phosphate (LFP), lithium-rich oxide (Li 1.2 Mn 0.6 Ni 0.2It may be selected from the group consisting of O2, etc., lithium nickel oxide, lithium sulfur (Li-S), lithium air (Li-air), high manganese oxide, high nickel oxide, high voltage spinel-based cathode material, fluorine-doped oxide, cathode composite structure, and combinations thereof. In addition, the active material layer may include treatments such as surface coating, ion doping, nano-sizing, pore control, and additive mixing to improve electrochemical properties. However, it is not limited to the above examples.

[0063] For example, the first active material layer (500) and the second active material layer (600) of the positive unit electrode (2) according to the present invention may be lithium iron phosphate (LFP).

[0064] The upper separator (510) and the lower separator (610) may include polyethylene (PE), polypropylene (PP), polyimide (PI), polybenzimidazole (PBI), aramid, cellulose, glass fiber, polymer ceramic composite membrane, alumina (Al₂O₃) coated separator, silica (SiO₂) coated separator, boron-based (BN, etc.) inorganic coating membrane, ceramic-polymer hybrid separator, PVDF (Polyvinylidene fluoride), PAN (Polyacrylonitrile), PEO (Polyethylene oxide), polysulfone, PVDF-HFP copolymer, nitrogen-doped polymer separator, electrolyte-impregnated solid polymer membrane, porous nanofiber-based separator, CNT composite separator, ion-conducting polymer separator, polymer-ionic liquid composite membrane, metal oxide coated separator, multilayer sandwich separator, thermal insulation functional separator, functional surface-modified separator, etc. However, it is not limited to the examples above.

[0065] For example, the upper separator (510) and lower separator (610) of the anode unit electrode (2) according to the present invention may be polyethylene (PE).

[0066] The second upper separator (212 or 512) and the second lower separator (312 or 612) may be characterized by having a structure that is mutually coupled while wrapping around the sides of the current collector (100 or 400), the first active material layer (200 or 500), and the second active material layer (300 or 600).

[0067] The structure in which the second upper separator (212 or 512) and the second lower separator (312 or 612) are joined together may be characterized by the lower portion of the second upper separator (212 or 512) and the upper portion of the second lower separator (312 or 612) being heat-pressed together to be joined together. By heat-pressing the lower portion of the second upper separator (212 or 512) and the upper portion of the second lower separator (312 or 612), contact with the outside is blocked, thereby reducing the process defect rate caused by external disturbances such as the inflow of foreign substances or static electricity.

[0068] The structure in which the second upper separator (212 or 512) and the second lower separator (312 or 612) are combined may be characterized by blocking direct contact between the anode and the cathode. By individually packaging the cathode unit electrode (1) and the anode unit electrode (2) with separators to block direct contact, storage and transportation are facilitated, and accurate alignment is facilitated.

[0069] In addition, when the cathode unit electrode (1) and the anode unit electrode (2), which are individually packaged with a separator, are sequentially stacked, there are substantially two layers of separators between the anode and the cathode, so no creasing occurs during the assembly process, and because it has a low cell internal resistance compared to the case where there is a thin single layer of separator, it is possible to induce an electrochemical reaction uniformly and stably.

[0070]

[0071] Referring to FIG. 5, a method for manufacturing a unit electrode according to another embodiment of the present invention will be described.

[0072] FIG. 5 is a flowchart showing the method for manufacturing a unit electrode of the present invention.

[0073] Referring to FIG. 5, a method for manufacturing a unit electrode (1 or 2) according to an embodiment of the present invention comprises the steps of: preparing a current collector (100 or 400); forming a first active material layer (200 or 500) on the upper portion of the current collector (100 or 400); forming a second active material layer (300 or 600) on the lower portion of the current collector (100 or 400); and forming an upper separator (210 or 510) on the upper portion of the first active material layer (200 or 500), the upper separator (211 or 511) comprising a first upper separator (211 or 511) and a second upper separator (212 or 512) extending outwardly from each side of the first upper separator (211 or 511). The method may include the step of forming a lower separator (310 or 610) comprising a first lower separator (311 or 611) and a second lower separator (312 or 612) extending outwardly from both sides of the first lower separator (311 or 611) at the bottom of the second active material layer (300 or 600); and the step of mutually combining the second upper separator (212 or 512) and the second lower separator (312 or 612).

[0074] The step of mutually combining the second upper separator (212 or 512) and the second lower separator (312 or 612) may be characterized by combining the lower part of the second upper separator (212 or 512) and the upper part of the second lower separator (312 or 512) by heat pressing so as to surround the sides of the current collector (100 or 400), the first active material layer (200 or 500), and the second active material layer (300 or 600).

[0075] In the step of combining the second upper separator (212 or 512) and the second lower separator (312 or 612), the lower part of the second upper separator (212 or 512) and the upper part of the second lower separator (312 or 612) are heat-pressed, thereby blocking contact with the outside, which has the effect of lowering the process defect rate caused by the ingress of foreign substances or static electricity, and by packaging the positive and negative electrodes individually, storage and transportation become easier and accurate alignment becomes easier.

[0076]

[0077] A stacked cell according to another embodiment of the present invention will be described.

[0078] A stacked cell according to one embodiment of the present invention may be characterized by the above-described cathode unit electrode (1); and the above-described anode unit electrode (2) located above or below the cathode unit electrode (1) being repeatedly stacked.

[0079] When the above-mentioned cathode unit electrode (1) and the above-mentioned anode unit electrode (2), which are individually packaged with a separator, are repeatedly stacked, there are substantially two layers of separators between the anode and the cathode, so no creasing occurs during the assembly process, and compared to the case where there is a thin single layer of separator, it has a low cell internal resistance, so it has the effect of inducing an electrochemical reaction uniformly and stably.

[0080] At this time, the electrolyte (3) may be characterized by being located between the cathode unit electrode (1) and the anode unit electrode (2).

[0081] The above electrolyte (3) can be injected during the cell assembly process or after assembly is completed. The injected electrolyte (3) seeps into the space between the two layers of separators interposed between the positive unit electrode (2) and the negative unit electrode (1), and further, is absorbed into the pore structure of the separator itself to form an ion conduction path. In this way, the electrolyte (3) is evenly distributed within the separator and between the separators, thereby ensuring the continuity of the electrolyte medium between the electrodes, which can contribute to inducing a stable and uniform electrochemical reaction when the cell is operated.

[0082]

[0083] <Preparation Example 1> Symmetric cell using the unit electrode of the present invention

[0084] Lithium metal foil (Neba Co., Ltd.) was punched into a Ø shape and used for both the positive and negative electrodes, and a PE separator (Hebei Gellec New Energy Science & Technology Joint Stock Co., Ltd.) with a thickness of 5 μm was used as the separator to wrap the positive and negative electrodes, respectively. In addition, an electrolyte was used in which 1 M LiTFSI was dissolved in DOL / DME (1:1, v / v) and 2 wt% LiNO3 was added, and a symmetric cell was constructed using the 2032 coin cell standard.

[0085]

[0086] <Preparation Example 2> Half cell using the unit electrode of the present invention

[0087] First, an electrode with a composition of LFP:Super P:PVDF (8:1:1) is placed at the anode at 5 mg cm⁻¹. -2It was fabricated with a loading level and used by punching it into a Ø shape. For the cathode, a lithium metal foil (Neba Co., Ltd.) was used by punching it into a Ø shape, and for the separator, a 5 μm thick PE separator (Hebei Gellec New Energy Science & Technology Joint Stock Co., Ltd.) was used to wrap the anode and cathode respectively. In addition, an electrolyte was used in which 1 M LiPF6 was dissolved in EC:DEC (1:1, v / v) and 10 wt% FEC was added, and a half-cell was constructed using the 2032 coin cell standard.

[0088]

[0089] <Comparative Example 1>

[0090] A symmetric cell was constructed by manufacturing under the same conditions as in Example 1, but using a single layer of separator between a general anode and a cathode instead of the unit electrode of the present invention.

[0091]

[0092] <Comparative Example 2>

[0093] A half-cell was constructed by manufacturing under the same conditions as in Example 2, but using a single layer of separator between a general anode and a cathode instead of the unit electrode of the present invention.

[0094]

[0095] <Experimental Example 1> Symmetrical Cell Charge / Discharge Test

[0096] Figure 6 is a graph showing the results of a symmetric cell test prepared according to Comparative Example 1 and Manufacturing Example 1 of the present invention.

[0097] FIG. 7 is a graph showing (a) average charging voltage and (b) average discharging voltage in a symmetric cell test prepared according to Comparative Example 1 and Manufacturing Example 1 of the present invention.

[0098] The symmetrical cell test is 1 mAh / cm² 2 At a current density of 1 mAh / cm² 2 The process was performed by repeatedly charging and discharging according to the capacity per area.

[0099] Referring to Fig. 6, it was confirmed that the overvoltage during charging and discharging of Example 1 was reduced compared to the overvoltage of Comparative Example 1.

[0100] Referring to FIG. 7, it was confirmed that the average charging overpotential of Example 1 is lower than that of Comparative Example 1 (23.42 V < 32.23 V), and the average discharging overpotential of Example 1 is also lower than that of Comparative Example 1 (-23.39 V < -32.24 V).

[0101]

[0102] <Experimental Example 2> Half-cell Charge / Discharge Test

[0103] FIG. 8 is a graph showing the half-cell test results prepared according to (a) Comparative Example 2 and (b) Manufacturing Example 2 of the present invention.

[0104] Figure 9 is a graph showing the long-life characteristic test results of half cells manufactured according to Comparative Example 2 and Manufacturing Example 2 of the present invention.

[0105] Half-cell tests were performed by repeatedly charging and discharging within a current density of 1 C and a voltage range of 2.5-4.0 V.

[0106] Referring to FIG. 8a, it was confirmed that Comparative Example 3 exhibits a stable charge-discharge plateau during the initial 1 cycle, but after 500 cycles, the flatness of the voltage curve deteriorates and the capacity decreases. This suggests that there are limitations in maintaining long-term structural stability and cell performance. On the other hand, Manufacturing Example 2, illustrated in FIG. 8b, was confirmed to maintain the shape of the charge-discharge curve well not only during the 1 cycle but also after 500 cycles, and to have stable plateau voltage and capacity retention characteristics. Through this, it was confirmed that Manufacturing Example 2 of the present invention can achieve excellent electrochemical characteristics even under long-term cycle conditions by maintaining inter-electrode interface stability and lowering the internal cell resistance.

[0107] Referring to FIG. 9, it was confirmed that while Comparative Example 2 showed a rapid decrease in capacity after 300 cycles, Example 2 showed a stable capacity retention rate for more than 500 cycles.

[0108]

[0109] <Experimental Example 3> Rate Competence Test of Half-Cell

[0110] Figure 10 is a graph showing the results of the rate capability test of half cells manufactured according to Comparative Example 2 and Manufacturing Example 2 of the present invention. The rate capability evaluation was performed by repeating charging and discharging for 5 cycles each while varying the current density to 0.05 C, 1 C, 2 C, 3 C, and 0.05 C within a voltage range of 2.5-4.0 V.

[0111] Referring to FIG. 10, it was confirmed that the stacked cell of the present invention, assembled by stacking the unit electrodes of the present invention, does not impair cell performance even at high current densities, as Comparative Example 2 and Example 2 showed similar capacity retention rates at high rate speeds (1-3 C).

[0112]

[0113] It was confirmed that the stacked cell of the present invention, assembled by repeatedly stacking the unit electrodes of the present invention, exhibits uniform and stable electrochemical performance by having two layers of separators structurally placed at the location where electrochemical reactions occur, thereby lowering the internal resistance of the cell.

[0114]

[0115] The foregoing description of the present invention is for illustrative purposes only, and those skilled in the art will understand that other specific forms can be easily modified without altering the technical spirit or essential features of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. For example, each component described as a single unit may be implemented in a distributed manner, and components described as distributed may likewise be implemented in a combined form.

[0116] The scope of the present invention is defined by the claims set forth below, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof should be interpreted as being included within the scope of the present invention.

[0117]

[0118] [Explanation of the symbol]

[0119] 1: Cathode unit electrode

[0120] 100: Current collector of the cathode unit electrode

[0121] 200: First active material layer of the cathode unit electrode

[0122] 210: Upper separator of the cathode unit electrode

[0123] 211: First upper separator of the cathode unit electrode

[0124] 212: Second upper separator of the cathode unit electrode

[0125] 300: Second active material layer of the cathode unit electrode

[0126] 310: Lower separator of the cathode unit electrode

[0127] 311: First lower separator of the cathode unit electrode

[0128] 312: Second lower separator of the cathode unit electrode

[0129] 2: Positive unit electrode

[0130] 400: Current collector of the positive unit electrode

[0131] 500: First active material layer of the positive unit electrode

[0132] 510: Upper separator of the anode unit electrode

[0133] 511: First upper separator of the anode unit electrode

[0134] 512: Second upper separator of the anode unit electrode

[0135] 600: Second active material layer of the positive unit electrode

[0136] 610: Lower separator of the anode unit electrode

[0137] 611: First lower separator of the anode unit electrode

[0138] 612: Second lower separator of the anode unit electrode

[0139] 3: Electrolyte

Claims

1. Entire house; A first active material layer located on the upper part of the above-mentioned current collector; A second active material layer located at the bottom of the above-mentioned current collector; An upper separator comprising a first upper separator located above the first active material layer and a second upper separator extending outwardly from each side of the first upper separator; A lower separator comprising a first lower separator located below the second active material layer and a second lower separator extending outwardly from each side of the first lower separator; A unit electrode characterized in that the second upper separator and the second lower separator are mutually coupled while surrounding the sides of the current collector, the first active material layer, and the second active material layer.

2. In Paragraph 1, The structure in which the second upper separator and the second lower separator are mutually coupled is, A unit electrode characterized by the lower part of the second upper separator and the upper part of the second lower separator being heat-pressed together and mutually bonded.

3. In Paragraph 1, A unit electrode characterized by a structure in which the second upper separator and the second lower separator are interconnected, thereby blocking direct contact between the anode and the cathode.

4. In Paragraph 1, A unit electrode characterized in that the above unit electrode is a negative unit electrode or a positive unit electrode.

5. In Paragraph 1, When the above unit electrode is a negative unit electrode, The above current collector is characterized by being a negative current collector, A unit electrode characterized in that the first active material layer and the second active material layer comprise a negative active material.

6. In Paragraph 1, If the above unit electrode is a positive unit electrode, The above current collector is characterized by being a positive current collector, and A unit electrode characterized in that the first active material layer and the second active material layer comprise a positive active material.

7. The stage of preparing the entire house; A step of forming a first active material layer on the upper part of the above-mentioned current collector; A step of forming a second active material layer on the lower part of the above-mentioned current collector; A step of forming an upper separator comprising a first upper separator and a second upper separator extending outwardly from each side of the first upper separator on the upper part of the first active material layer; A step of forming a lower separator comprising a first lower separator and a second lower separator extending outwardly from each side of the first lower separator at the lower portion of the second active material layer; and A method for manufacturing a unit electrode characterized by including the step of mutually combining the second upper separator and the second lower separator.

8. In Paragraph 7, The step of mutually combining the second upper separator and the second lower separator is, A method for manufacturing a unit electrode characterized by heat-pressing and joining the lower part of the second upper separator and the upper part of the second lower separator so as to surround the side of the current collector, the first active material layer, and the second active material layer.

9. In Paragraph 7, A method for manufacturing a unit electrode characterized in that the above unit electrode is a negative unit electrode or a positive unit electrode.

10. In Paragraph 7, When the above unit electrode is a negative unit electrode, The above current collector is characterized by being a negative current collector, A method for manufacturing a unit electrode characterized in that the first active material layer and the second active material layer comprise a negative active material.

11. In Paragraph 7, If the above unit electrode is a positive unit electrode, The above current collector is characterized by being a positive current collector, and A method for manufacturing a unit electrode characterized in that the first active material layer and the second active material layer comprise a positive active material.

12. In a stacked cell in which a cathode and an anode are alternately arranged and stacked, A stacked cell characterized in that the above-mentioned cathode or anode is a unit electrode of claim 1.

13. The cathode unit electrode of paragraph 5; and The anode unit electrode of claim 6, located above or below the cathode unit electrode, is characterized by being repeatedly stacked. A stacked cell characterized by the electrolyte being located between the cathode unit electrode and the anode unit electrode.

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