Method for manufacturing secondary battery

Abstract

According to exemplary embodiments, a method for manufacturing a secondary battery is provided. The method comprises the steps of: accommodating an electrode assembly in a cell case, the electrode assembly including a cathode, an anode and a separator between the cathode and the anode, the cathode comprising a cathode current collector layer and a cathode active material layer, and the cathode active material layer comprising lithium iron phosphate and lithium iron oxide; and bonding a deoxidation sheet to the cell case.

Description

Method for manufacturing secondary batteries

[0001] The present invention relates to a method for manufacturing a secondary battery. The present application claims the benefit of Korean application No. 10-2024-0137457, filed on October 10, 2024, which is incorporated herein by reference in its entirety.

[0002] Unlike primary batteries, secondary batteries can be charged and discharged multiple times. Secondary batteries are widely used as energy sources for various wireless devices such as handsets, laptops, and cordless vacuum cleaners. Recently, as the manufacturing cost per unit capacity of secondary batteries has decreased dramatically due to improved energy density and economies of scale, and as the driving range of BEVs (battery electric vehicles) has increased to a level equivalent to that of fuel vehicles, the primary use of secondary batteries is shifting from mobile devices to mobility.

[0003] The manufacturing of a secondary battery includes an electrode process comprising mixing, coating, roll pressing, slitting, and notching processes; an assembly process for embedding the electrode assembly into a case; and an activation process for electrically activating and stabilizing the battery cells. After the activation process, the battery cells can be stacked to form a cell stack. The cell stack can be mounted in a housing together with a module frame, or directly mounted in a housing without a module frame.

[0004] The problem that the technical concept of the present invention aims to solve is to provide a method for manufacturing a secondary battery with improved yield and reliability.

[0005] According to exemplary embodiments of the present invention for solving the above-described problem, a method for manufacturing a secondary battery is provided. The method comprises the step of housing an electrode assembly in a cell case, wherein the electrode assembly comprises a positive electrode, a negative electrode, and a separator between the positive electrode and the negative electrode, wherein the positive electrode comprises a positive current collector layer and a positive active material layer, and the positive active material layer comprises lithium iron phosphate and lithium iron oxide; and the step of attaching a deoxygenation sheet to the cell case.

[0006] The above method further includes the step of injecting an electrolyte into the cell case after the step of bonding the deoxygenation sheet to the case.

[0007] The above method further includes the step of injecting an electrolyte into the cell case before bonding the deoxygenation sheet to the case.

[0008] The cell case includes an electrode receiving portion in which the electrode assembly is accommodated and a gas pocket to which the deoxygenation sheet is combined.

[0009] The above method further comprises the steps of: activating a battery cell comprising the cell case, the deoxygenation sheet, and the electrode assembly; and performing a degassing process on the battery cell.

[0010] The above method further includes the step of removing the gas pocket after the degassing process.

[0011] The above deoxygenation sheet is removed together with the above gas pocket.

[0012] The above deoxygenation sheet is iron oxide (Fe2O3, Fe3O4), iron carbonate (FeCO3), and iron gluconate (C 12 H 24 FeO 14 ), iron sulfide (Fe2(SO4)3), sodium iron ethylenediaminetetraacetate (NaFeEDTA), iron lactate (C6H 10It contains one or more of FeO6) and ammonium iron citrate (C6H8O7·Fe·NH3).

[0013] The above deoxygenated sheet contains ascorbic acid (C6H8O6).

[0014] The above deoxygenation sheet contains sodium bicarbonate (NaHCO3).

[0015] The above deoxygenation sheet comprises one or more of hydroquinone resin and polyphenol resin.

[0016] The above deoxygenated sheet comprises one or more of manganese dioxide (MnO2), titanium dioxide (TiO2), vanadium dioxide (VO2), copper oxide (CuO, Cu2O), nickel oxide (NiO) and cobalt oxide (Co3O4).

[0017] According to exemplary embodiments, a method for manufacturing a secondary battery is provided. The method comprises the steps of: preparing a cell case including a deoxygenation sheet; and receiving an electrode assembly in the cell case, wherein the electrode assembly comprises a positive electrode, a negative electrode, and a separator between the positive electrode and the negative electrode, wherein the positive electrode comprises a positive current collector layer and a positive active material layer, and the positive active material layer comprises lithium iron phosphate and lithium iron oxide.

[0018] The cell case includes an electrode receiving portion in which the electrode assembly is accommodated and a gas pocket to which the deoxygenation sheet is combined.

[0019] The above method further comprises the steps of: activating a battery cell including the cell case and the electrode assembly; and performing a degassing process on the battery cell.

[0020] The above method further includes the step of removing the gas pocket after the degassing process.

[0021] The above deoxygenation sheet is removed together with the above gas pocket.

[0022] According to exemplary embodiments of the present invention, a deoxygenation sheet configured to absorb oxygen generated from lithium iron oxide of an electrode assembly is provided. Accordingly, even when a secondary battery manufacturing facility for manufacturing lithium iron oxide-free battery cells is converted to a facility for manufacturing battery cells containing lithium iron oxide, no improvement or expansion of the facility is required, thereby reducing capital expenditure for secondary battery manufacturing.

[0023] The effects obtainable from the exemplary embodiments of the present invention are not limited to those mentioned above, and other unmentioned effects can be clearly derived and understood by those skilled in the art to which the exemplary embodiments of the present disclosure belong from the following description. That is, unintended effects resulting from the implementation of the exemplary embodiments of the present disclosure can also be derived by those skilled in the art from the exemplary embodiments of the present disclosure.

[0024] FIG. 1 is a flowchart illustrating a method for manufacturing a secondary battery according to exemplary embodiments.

[0025] FIGS. 2 to 4 are drawings for explaining a method of manufacturing a secondary battery according to exemplary embodiments.

[0026] FIG. 5 is a flowchart illustrating a method for manufacturing a secondary battery according to exemplary embodiments.

[0027] FIG. 6 is a flowchart illustrating a method for manufacturing a secondary battery according to exemplary embodiments.

[0028] FIG. 7 is a drawing for explaining a method of manufacturing a secondary battery according to exemplary embodiments.

[0029] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings. Instead, based on the principle that the inventor can appropriately define the concepts of terms to best describe his invention, they should be interpreted in a meaning and concept consistent with the technical spirit of the present invention.

[0030] Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are merely the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention; thus, it should be understood that various equivalents and modifications that can replace them may exist at the time of filing this application.

[0031] In addition, in describing the present invention, if it is determined that a detailed description of related known components or functions may obscure the essence of the invention, such detailed description is omitted.

[0032] Since embodiments of the present invention are provided to more fully explain the invention to those skilled in the art, the shapes and sizes of the components in the drawings may be exaggerated, omitted, or schematically depicted for clearer explanation. Accordingly, the size or proportion of each component does not entirely reflect the actual size or proportion.

[0033]

[0034] (1st embodiment)

[0035] FIG. 1 is a flowchart illustrating a method for manufacturing a secondary battery according to exemplary embodiments.

[0036] FIGS. 2 to 4 are drawings for explaining a method of manufacturing a secondary battery according to exemplary embodiments.

[0037] Referring to FIGS. 1 and FIGS. 2, in P110, an electrode assembly (11) can be accommodated in a cell case (12).

[0038] Hereinafter, the technical concept of the present invention will be explained with reference to an example in which the electrode assembly (11) comprises a plurality of positive electrodes, a plurality of negative electrodes, and a plurality of separators. A person skilled in the art can easily arrive at an embodiment in which the electrode assembly comprises a positive electrode, a negative electrode, and a winding structure of a separator interposed between them, based on what is described herein.

[0039] Each of the plurality of positives may include a positive current collector and a positive active material. The thickness of the positive current collector may be in the range from about 3 μm to about 500 μm. The positive current collector may not cause chemical changes in the secondary battery finally manufactured and may have high conductivity. The positive current collector may include, for example, any one of stainless steel, nickel, titanium, calcined carbon, and aluminum. The positive current collector may also include stainless steel surface-treated with carbon, nickel, titanium, silver, etc. The surface of the positive current collector may include a micro-irregular structure to increase the adhesion of the active material. The shape of the positive current collector may include any one of a film, sheet, foil, net, porous material, foam, and nonwoven fabric.

[0040] The positive electrode active material is a material capable of causing an electrochemical reaction. The positive electrode active material may be a lithium transition metal oxide. The positive electrode active material is, for example, with the chemical formula Li 1+x M 1-y M' y PO 4-z X zIt may include any one of the olivine-based lithium metal phosphates represented by (where M is a transition metal, more specifically one of Fe, Mn, Co, and Ni; M' is one of Al, Mg, and Ti; X is one of F, S, and N; -0.5≤x≤+0.5; 0≤y≤0.5; and 0≤z≤0.1). The positive electrode active material may include, for example, lithium iron phosphate. The positive electrode active material is Li 1+x M 1-y M'yO 2-z X z It may further include a lithium metal oxide represented by (where M is a main metal one of Fe, Mn, Co, and Ni, M' is a substitutional metal element different from M among Fe, Mn, Co, and Ni, and X is a substitutional non-metal element or defect). The positive electrode active material may include, for example, lithium iron oxide.

[0041] According to exemplary embodiments, when the positive electrode active material comprises a first active material comprising lithium iron phosphate (e.g., LiFePO4) and a second active material comprising lithium iron oxide (e.g., LiFeO2), the mass ratio of the first positive electrode active material in the positive electrode active material may be in the range of about 0.1 wt% to about 10 wt%, and the mass ratio of the second positive electrode active material in the positive electrode active material may be in the range of about 80 wt% to about 99 wt%.

[0042] Each of the plurality of negative electrodes may include a negative current collector and a negative active material. The thickness of the negative current collector may be in the range of about 3 μm to about 500 μm. The negative current collector may not cause chemical changes in the secondary battery finally manufactured and may have high conductivity. The negative current collector may include any one of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, and aluminum-cadmium alloy. The negative current collector may also include stainless steel surface-treated with carbon, nickel, titanium, silver, etc. The surface of the negative current collector may include a micro-irregular structure to increase the adhesion of the active material. The shape of the negative current collector may include any one of a film, sheet, foil, net, porous material, foam, and nonwoven fabric.

[0043] The negative electrode active material may include carbon, for example, non-graphitizable carbon, graphite-based carbon, etc. The negative electrode active material is, for example, Li x Fe2O3(0≤x≤1), LixWO2(0≤x≤1), Sn x Me 1-x Me y O z (wherein Me is any one of Mn, Fe, Pb, and Ge, and Me' is any one of Al, B, P, Si, Group 1, Group 2, and Group 3 elements of the periodic table, and halogens; 0 <x≤1 이고; 1≤y≤3 이며; 1≤z≤8) 등의 금속 복합 산화물을 포함할 수 있다. 음극 활물질은, 예컨대, 리튬 금속; 리튬 합금; 규소계 합금; 및 주석계 합금 중 어느 하나를 포함할 수 있다. 음극 활물질은, 예컨대, SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4및 Bi2O5등의 금속 산화물을 포함할 수 있다. 음극 활물질은, 예컨대, 폴리아세틸렌 등의 도전성 고분자; Li-Co-Ni 계 재료 등을 포함할 수도 있다.

[0044] Each of the plurality of anodes may include an anode tab (11T1), and each of the plurality of cathodes may include a cathode tab (11T2). The anode tab (11T1) of each of the plurality of anodes may be coupled to an anode lead (11P). The anode tab (11T1) of each of the plurality of anodes may be welded to an anode lead (11P). The cathode tab (11T2) of each of the plurality of cathodes may be coupled to a cathode lead (11N). The cathode tab (11T2) of each of the plurality of cathodes may be welded to a cathode lead (11N).

[0045] After the electrode assembly (11) is received in the cell case (12), the positive lead (11P) and the negative lead (11N) may protrude outside the cell case (12). According to exemplary embodiments, the positive lead (11P) may be on the first side (12S1) of the cell case (12) and the negative lead (11N) may be on the second side (12S2) opposite to the first side (12S1) of the cell case (12). Unlike in FIG. 2, the positive lead (11P) and the negative lead (11N) may be on the same sides of the cell case (12), and the positive lead (11P) and the negative lead (11N) may protrude in the same direction.

[0046] A plurality of anodes and a plurality of cathodes may alternate with separators. Accordingly, one of a plurality of anodes and a plurality of cathodes may be interposed between two adjacent separators. Each of the separators may be in contact with at least one of a plurality of anodes and a plurality of cathodes. Each of the separators can isolate a plurality of anodes and a plurality of cathodes by preventing direct contact between the plurality of anodes and a plurality of cathodes, and thereby prevent the formation of an unwanted closed loop caused by a short circuit between the plurality of anodes and a plurality of cathodes. Each of the plurality of anodes and a plurality of cathodes may have a flat film shape.

[0047] The electrode assembly (11) may further include insulating layers (11I) applied to the positive lead (11P) and the negative lead (11N). Each of the insulating layers (11I) may be an insulating tape, but is not limited thereto. The insulating layers (11I) may also be an insulating coating. The insulating layers (11I) may provide electrical isolation between the positive lead (11P) and the cell case (12) and electrical isolation between the negative lead (11N) and the cell case (12).

[0048] The cell case (12) may be any one of a pouch case, a cylindrical can, and a rectangular can. Hereinafter, the technical concept of the present invention is described based on an example in which the cell case (12) is an aluminum laminate sheet, but a person skilled in the art will be able to easily arrive at an example in which the cell case (12) is one of a cylindrical can and a rectangular can based on what is described herein.

[0049] The cell case (12) may include a cup-shaped receiving portion (12R) and a gas pocket (12G). The receiving portion (12R) may be formed by a pouch forming process. An electrode assembly (11) may be received in the receiving portion (12R). The gas pocket (12G) may be connected to the receiving portion (12R). The gas pocket (12G) may be located on one side of the receiving portion (12R).

[0050] The cell case (12) may include an inner resin layer, a metal layer, and an outer resin layer. There may also be an adhesive and an anti-corrosion layer between the inner resin layer and the metal layer and between the outer resin layer and the metal layer.

[0051] The inner resin layer may have heat-sealability and may be referred to as a sealant layer. The inner resin layer enables sealing of the cell case (12). The inner resin layer may include a polyolefin-based resin, such as polypropylene (PP) and polyethylene (PE), for example. The metal layer may include one of an alloy of iron, carbon, chromium, and manganese, an alloy of iron, chromium, and nickel, and aluminum. The metal layer may be a gas barrier. The metal layer may block the entry and exit of gas from the cell case (12). The outer resin layer may be a surface protection layer. The outer resin layer may include a material having wear resistance and heat resistance, such as nylon resin.

[0052]

[0053] Next, referring to FIGS. 1 and FIGS. 3, in P120, an electrolyte (EL) can be injected into the cell case (12).

[0054] The electrolyte (EL) may be any one of a non-aqueous electrolyte, an aqueous electrolyte, an ionic electrolyte, and a gel electrolyte. The electrolyte (EL) may also be a solid electrolyte. The non-aqueous electrolyte may include organic solvents such as ethylene carbonate and dimethyl carbonate, and lithium salts such as LiPF6 and LiBF4 dissolved in organic solvents. The non-aqueous electrolyte may also include ethylene carbonate dissolved in tetraethylammonium salts. The aqueous electrolyte may include sodium sulfate solution, sulfuric acid solution, hydrochloric acid solution, and sodium hydroxide solution. The ionic electrolyte is an ionic compound that is in a liquid state at room temperature, such as ethylmethylimidazolidium bis(trifluoromethylsulfonyl)amide, and has high thermal stability. The gel electrolyte may be provided by treating the liquid electrolyte using polyacrylonitrile and PVA, etc. The solid electrolyte may include a polymer material doped with a lithium salt (e.g., polyethylene oxide (PEO)) and a ceramic electrolyte composed of ceramic materials such as NASICON and LLZO.

[0055]

[0056] Next, in P130, the deoxygenation sheet (13) can be attached to the cell case (12). The deoxygenation sheet (13) can be attached to the gas pocket (12G) of the cell case (12). The deoxygenation sheet (13) can be attached to the cell case (12). The deoxygenation sheet (13) can be attached to the cell case (12) using an adhesive or by a heat fusion agent. The deoxygenation sheet (13) can also be simply sandwiched between the gas pockets (12G) without any fixing means such as an adhesive.

[0057] According to exemplary embodiments, the deoxygenation sheet may be configured to absorb oxygen. According to exemplary embodiments, the deoxygenation sheet (13) may have a sheet shape. The deoxygenation sheet (13) may be manufactured using oxygen scavenger powder. According to exemplary embodiments, the deoxygenation sheet (13) may be provided by any one of the processes of powder compression molding, powder rolling, electroplating and coating, and thermal spraying.

[0058] According to exemplary embodiments, the deoxygenation sheet (13) may be an iron-containing sheet. According to exemplary embodiments, the deoxygenation sheet (13) may be manufactured based on iron-based powder. According to exemplary embodiments, the deoxygenation sheet (13) may be iron oxide (Fe2O3, Fe3O4), iron carbonate (FeCO3), or iron gluconate (C 12 H 24 FeO 14 ), iron sulfide (Fe2(SO4)3), sodium iron ethylenediaminetetraacetate (NaFeEDTA), iron lactate (C6H 10 It may include one or more of FeO6) and iron ammonium citrate (C6H8O7·Fe·NH3).

[0059] According to exemplary embodiments, the deoxygenation sheet (13) may be an iron-free (Fe-free) sheet. According to exemplary embodiments, the deoxygenation sheet (13) may be manufactured based on non-ferrous powder. According to exemplary embodiments, the deoxygenation sheet (13) may include zeolite. According to exemplary embodiments, the deoxygenation sheet (13) may include ascorbic acid (C6H8O6). According to exemplary embodiments, the deoxygenation sheet (13) may include sodium bicarbonate (NaHCO3).

[0060] According to exemplary embodiments, the deoxygenation sheet (13) may include a deoxygenation resin. According to exemplary embodiments, the deoxygenation sheet (13) may include one or more of a hydroquinone resin and a polyphenol resin.

[0061] According to exemplary embodiments, the deoxygenation sheet (13) may comprise a high-potential metal oxide. According to exemplary embodiments, the deoxygenation sheet (13) may comprise one or more of manganese dioxide (MnO2), titanium dioxide (TiO2), vanadium dioxide (VO2), copper oxide (CuO, Cu2O), nickel oxide (NiO) and cobalt oxide (Co3O4).

[0062]

[0063] Next, referring to FIGS. 1 and FIGS. 4, an activation process can be performed on a battery cell (10) in P140. The battery cell (10) may include an electrode assembly (11), a cell case (12), a deoxygenation sheet (13), and an electrolyte (EL, see FIG. 3). The activation process may include a formation process, an aging process, and a charge / discharge process.

[0064] The formation process is the initial charging process of the battery cell (10). The formation process can induce a reaction between a plurality of positive electrodes and an electrolyte, and a reaction between a plurality of negative electrodes and an electrolyte. A CEI (Cathode Electrolyte Interphase) layer can be formed by the reaction between a plurality of positive electrodes and an electrolyte. A SEI (Solid Electrolyte Interphase) layer can be formed by the reaction between a plurality of negative electrodes and an electrolyte.

[0065] The CEI layer can improve the lifespan and performance of the battery cell (10) by maintaining the stability of the anode surface, preventing oxidation of the electrolyte, and stabilizing the electrochemical reaction inside the battery cell (10). Furthermore, the CEI layer can prevent corrosion of multiple anodes by blocking electron conduction and allowing the movement of lithium ions.

[0066] The SEI layer can protect the electrode surface by preventing further decomposition of the electrolyte in the electrolyte, allow the movement of lithium ions, and block the movement of electrolyte molecules, thereby enhancing the stability of the battery cell (10). In addition, the SEI layer can mitigate (or minimize) self-discharge and capacity loss.

[0067] The formation process can be performed by an energy source, such as an electric current source. While the formation process is being performed, the battery cell (10) can be pressed by pressure plates. By uniformly pressurizing the battery cell (10), gas trapping and lithium plating can be prevented, and the uniformity of the SEI film can be enhanced. A battery cell (10) having a uniform SEI film can have a relatively short charging time. The pressure plates can be configured to heat the battery cell (10). Heating the battery cell (10) can promote the formation of the SEI layer and the CEI layer.

[0068] After the formation process, an aging process may be performed on the battery cell (10) at a high temperature and / or room temperature. The aging process can stabilize the electrochemical properties of the battery cell (10) after the formation process, monitor the performance of the battery cell to identify and remove defective products, and fully carry out chemical reactions inside the cell to improve long-term performance and lifespan.

[0069] The aging process may include storing the battery cell (10) in an environment having controlled temperature and humidity. Through the aging process, the electrolyte (EL, see FIG. 3) may be more evenly dispersed within the battery cell (10). During the storage period of the battery cell (10), the voltage, capacity, and internal resistance of the battery cell (10) may be measured, and accordingly, the quality and defects of the battery cell (10) may be determined.

[0070] After the aging process, an additional charging and discharging process can be performed on the battery cell (10).

[0071] According to exemplary embodiments, during the formation process, the capacity of the lithium iron oxide of the electrode assembly (11) of the battery cell (10) can be expressed. According to exemplary embodiments, during the formation process, the lithium iron oxide of the electrode assembly (11) of the battery cell (10) can react according to the following Equations 1 and 2.

[0072] [Equation 1]

[0073] Li5FeO4 → Li3FeO 3.5 + 0.25O2(g) + 2Li + + 2e -

[0074] [Equation 2]

[0075] Li3FeO 3.5 → LiFeO2 + 0.75O2(g) + 2Li + + 2e -

[0076] Accordingly, an excess amount of oxygen may be generated from the lithium iron oxide of the electrode assembly (11) of the battery cell (10). According to exemplary embodiments, the deoxygenation sheet (13) may be configured to absorb the oxygen generated from the lithium iron oxide. Accordingly, even when a secondary battery manufacturing facility for manufacturing lithium iron oxide-free battery cells is converted to a facility for manufacturing battery cells containing lithium iron oxide, no improvement or expansion of the facility is required, so capital expenditure for secondary battery manufacturing can be reduced.

[0077]

[0078] Subsequently, at P150, a degassing process may be performed on the battery cell (10). The degassing process may include discharging the gas trapped in the gas pocket (12G). According to exemplary embodiments, the battery cell (10) may be loaded into a vacuum chamber and the gas trapped in the gas pocket (12G) may be discharged by piercing the gas pocket (12G) of the cell case (12).

[0079]

[0080] Next, in P160, the gas pocket (12G) can be removed. The gas pocket (12G) can be removed by a cutting means such as a blade (BL). When the gas pocket (12G) is removed, the deoxygenation sheet (13) can be removed. Accordingly, during the operation of the finished battery cell (10), the gas generated from the deoxygenation sheet (13) can be prevented from being introduced into the receiving portion (11R, see FIG. 2) of the battery cell (10).

[0081]

[0082] (2nd Example)

[0083] FIG. 5 is a flowchart illustrating a method for manufacturing a secondary battery according to exemplary embodiments.

[0084] Referring to FIGS. 3 and FIGS. 5, after the decarbonized sheet is bonded to the cell case in P130, the electrolyte (EL) can be injected into the cell case (120) in P120. Except for a change in the order of P120 and P130, the method of manufacturing the secondary battery of FIG. 5 is substantially the same as that described with reference to FIGS. 1 to 5.

[0085]

[0086] (3rd Example)

[0087] FIG. 6 is a flowchart illustrating a method for manufacturing a secondary battery according to exemplary embodiments.

[0088] FIG. 7 is a drawing for explaining a method of manufacturing a secondary battery according to exemplary embodiments.

[0089] Referring to FIGS. 6 and 7, in P100, a cell case (12) including a decarbonized sheet (13) may be prepared. According to exemplary embodiments, the decarbonized sheet (13) may be bonded to the cell case (12) after the step of preparing the cell case (12) from a pouch roll and before the forming process of the cell case (12). According to exemplary embodiments, the decarbonized sheet (13) may be bonded to the cell case (12) after the forming process and before receiving the electrode assembly (11).

[0090] Unlike the method for manufacturing a secondary battery of FIG. 1, the method for manufacturing a secondary battery of FIG. 6 involves preparing a cell case (12) to which a decarbonization sheet (13) is attached, so in P130, the deoxygenation sheet (13) may be omitted from being bonded to the cell case (12). Since the processes of P110, P120, P140, P150, and P160 are substantially the same as those described with reference to FIG. 1 to 4, a redundant description thereof is omitted.

[0091]

[0092] The present invention has been described in more detail above through drawings and embodiments. However, the configurations described in the drawings or embodiments described in this specification are merely one embodiment of the present invention and do not represent all technical concepts of the present invention; therefore, it should be understood that various equivalents and modifications that can replace them may exist at the time of filing this application.

Claims

1. A step of housing an electrode assembly in a cell case, wherein the electrode assembly comprises a positive electrode, a negative electrode, and a separator between the positive electrode and the negative electrode, wherein the positive electrode comprises a positive current collector layer and a positive active material layer, and the positive active material layer comprises lithium iron phosphate and lithium iron oxide; and A method for manufacturing a secondary battery comprising the step of bonding a deoxygenation sheet to the cell case.

2. In Paragraph 1, A method for manufacturing a secondary battery, comprising the step of injecting an electrolyte into the cell case after the step of bonding the deoxygenation sheet to the case.

3. In Paragraph 1, A method for manufacturing a secondary battery, further comprising the step of injecting an electrolyte into the cell case before bonding the deoxygenation sheet to the case.

4. In Paragraph 1, A method for manufacturing a secondary battery, characterized in that the cell case comprises an electrode receiving portion in which the electrode assembly is received and a gas pocket combined with the deoxygenation sheet.

5. In Paragraph 4, A step of activating a battery cell comprising the cell case, the deoxygenation sheet, and the electrode assembly; and A method for manufacturing a secondary battery comprising the step of performing a degassing process on the battery cell.

6. In Paragraph 5, A method for manufacturing a secondary battery, comprising the step of removing the gas pocket after the above degassing process.

7. In Paragraph 6, A method for manufacturing a secondary battery characterized in that the above-mentioned deoxygenation sheet is removed together with the above-mentioned gas pocket.

8. In Paragraph 1, The above deoxygenation sheet is iron oxide (Fe2O3, Fe3O4), iron carbonate (FeCO3), and iron gluconate (C 12 H 24 FeO 14 ), iron sulfide (Fe2(SO4)3), sodium iron ethylenediaminetetraacetate (NaFeEDTA), iron lactate (C6H 10 A method for manufacturing a secondary battery characterized by comprising one or more of FeO6) and iron ammonium citrate (C6H8O7·Fe·NH3).

9. In Paragraph 1, A method for manufacturing a secondary battery characterized in that the above-mentioned deoxygenation sheet contains ascorbic acid (C6H8O6).

10. In Paragraph 1, A method for manufacturing a secondary battery characterized in that the above-mentioned deoxygenation sheet comprises sodium bicarbonate (NaHCO3).

11. In Paragraph 1, A method for manufacturing a secondary battery characterized in that the above-mentioned deoxygenation sheet comprises one or more of a hydroquinone resin and a polyphenol-based resin.

12. In Paragraph 1, A method for manufacturing a secondary battery characterized in that the above-mentioned deoxygenation sheet comprises one or more of manganese dioxide (MnO2), titanium dioxide (TiO2), vanadium dioxide (VO2), copper oxide (CuO, Cu2O), nickel oxide (NiO), and cobalt oxide (Co3O4).

13. A step of preparing a cell case including a deoxygenation sheet; and The method includes the step of housing the electrode assembly in a cell case, A method for manufacturing a secondary battery characterized in that the electrode assembly comprises a positive electrode, a negative electrode, and a separator between the positive electrode and the negative electrode, wherein the positive electrode comprises a positive current collector layer and a positive active material layer, and the positive active material layer comprises lithium iron phosphate and lithium iron oxide.

14. In Paragraph 13, A method for manufacturing a secondary battery, characterized in that the cell case comprises an electrode receiving portion in which the electrode assembly is received and a gas pocket combined with the deoxygenation sheet.

15. In Paragraph 14, A step of activating a battery cell comprising the cell case and the electrode assembly; and A method for manufacturing a secondary battery comprising the step of performing a degassing process on the battery cell.

16. In Paragraph 15, A method for manufacturing a secondary battery, comprising the step of removing the gas pocket after the above degassing process.

17. In Paragraph 16, A method for manufacturing a secondary battery characterized in that the above-mentioned deoxygenation sheet is removed together with the above-mentioned gas pocket.

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