Foldable lithium-air battery and manufacturing method thereof

Abstract

The present invention discloses a foldable lithium-air battery and a method for manufacturing the same. The lithium-air battery is constructed such that a first electrolyte membrane and a second electrolyte membrane are formed, each including a reinforcement layer and an ionic liquid suitable for a positive electrode and a negative electrode, respectively, and a separator including a diffusion-preventing membrane is provided between the first electrolyte membrane and the second electrolyte membrane, thereby ensuring electrode stability and improving battery performance due to excellent ionic conductivity.

Description

Technical Field

[0001] The present invention relates to a foldable lithium-air battery and a method for manufacturing the same. The foldable lithium-air battery can prevent durability degradation and electrolyte volatilization, thereby ensuring electrode stability, and can have excellent ionic conductivity, thereby improving battery performance. Background Art

[0002] Lithium-air batteries consist of a positive electrode where oxygen reduction occurs, a negative electrode where lithium oxidation occurs, an electrolyte solution that transports lithium ions and electrons, and a separator that separates the positive and negative electrodes. Because lithium-air batteries offer higher energy density and improved safety than lithium-ion batteries, much research and development is underway on lithium-air batteries.

[0003] Unlike lithium-ion batteries, lithium-air batteries require a structure for supplying and exhausting air to and from the electrodes, and a structure for collecting current by connecting multiple electrodes to increase battery capacity. Batteries with multiple electrodes connected to each other are generally divided into pouch cells and stacked cells.

[0004] For example, pouch-type batteries are made by forming positive electrode oxygen inlet holes in the pouch. However, the problem is that the electrolyte leaks or evaporates from the holes, and the presence of the holes makes compression molding difficult.

[0005] In addition, stacked batteries have a structure in which multiple positive electrode and negative electrode unit cells are stacked in sequence. This stacked battery is easy to manufacture diamond-shaped batteries, but its problems are that the manufacturing process is complicated and applying an impact to the electrodes will push the electrodes, causing a short circuit.

[0006] Meanwhile, because lithium-air batteries operate in an open system, non-volatile electrolytes are used to prevent electrolyte volatilization. However, a problem with non-volatile electrolytes is that they can decompose due to chemical reactions with the lithium negative electrode or due to the high voltage of the positive electrode. Furthermore, if the electrolyte membrane containing the non-volatile electrolyte is a single layer, it is difficult to maintain the excellent stiffness of the positive and negative electrodes due to side reactions of the electrodes. Summary of the Invention

[0007] In a preferred aspect, a foldable lithium-air battery is provided, which may include a multilayer membrane, the multilayer membrane including a first electrolyte membrane, an anti-diffusion membrane and a second electrolyte membrane, the multilayer membrane containing a non-volatile electrolyte and an ionic liquid suitable for the positive electrode and the negative electrode, respectively.

[0008] In one aspect, a foldable lithium-air battery is provided in which a separator is bent to surround edges of a positive electrode composite and a negative electrode composite to have a zigzag shape.

[0009] As used herein, the term "foldable" refers to one or more components that can be bent, stacked, and / or rearranged into a flatter or more compact shape and / or form a stack. For example, a "foldable battery" can be a battery comprising one or more components (e.g., a separator, a positive electrode composite material, and a negative electrode composite material) forming a stack (the stack comprising multiple layers of these components). Preferably, one or more components of the foldable battery can be in the form of a layered or plate-like shape, thereby forming a stack in which these layers are in close contact with each other.

[0010] In one aspect, a foldable lithium-air battery is provided, comprising a positive electrode composite, a negative electrode composite, and a separator. The separator can be disposed between the positive electrode composite and the negative electrode composite, and can be bent to surround an edge of the positive electrode composite and an opposite edge of the negative electrode composite relative to an edge of the positive electrode composite, thereby forming a zigzag shape. The separator can include a first electrolyte membrane in contact with the positive electrode composite, a second electrolyte membrane in contact with the negative electrode composite, and an anti-diffusion membrane disposed between the first electrolyte membrane and the second electrolyte membrane.

[0011] The first electrolyte membrane may include a first reinforcement layer and a first electrolyte solution impregnated in the first reinforcement layer, and the second electrolyte membrane may include a second reinforcement layer and a second electrolyte solution impregnated in the second reinforcement layer.

[0012] The first electrolyte membrane may include a first reinforcement layer and a first electrolyte solution at a weight ratio of about 1:1 to 3, and the second electrolyte membrane may include a second reinforcement layer and a second electrolyte solution at a weight ratio of about 1:1 to 3.

[0013] The first electrolyte solution may include the first ionic liquid in an amount of about 45 wt % to 60 wt %, the first polymer in an amount of about 25 wt % to 30 wt %, and the first lithium salt in an amount of about 15 wt % to 25 wt %, and the second electrolyte solution may include the second ionic liquid in an amount of about 45 wt % to 60 wt %, the second polymer in an amount of about 25 wt % to 30 wt %, and the second lithium salt in an amount of about 15 wt % to 25 wt %.

[0014] The first ionic liquid may include 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMIm-TFSI), 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIm-FSI), N-trimethyl-N-propylammonium bis(trifluoromethanesulfonyl)imide (EMIm- 1113 -TFSI), N-trimethyl-N-propylammonium bis(fluorosulfonyl)imide (N 1113-FSI), N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide (DEME-TFSI), N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(fluorosulfonyl)imide (DEME-FSI), 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (P 14 -TFSI) and 1-butyl-1-methylpyrrolidinium bis(fluorosulfonyl)imide (P 14 -FSI) one or more.

[0015] The second ionic liquid may include N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide (P 13 -TFSI), N-methyl-N-propylpyrrolidinium bis(fluorosulfonyl)imide (P 13 -FSI), N-methyl-N-propylpiperidinium bis(trifluoromethanesulfonyl)imide (PP 13 -TFSI), N-methyl-N-propylpiperidinium bis(fluorosulfonyl)imide (PP 13 -FSI), 1-butyl-1-methylpiperidinium bis(trifluoromethanesulfonyl)imide (PP 14 -TFSI) and 1-butyl-1-methylpiperidinium bis(fluorosulfonyl)imide (PP 14 -FSI) one or more.

[0016] The first polymer or the second polymer may include one or more selected from polyvinylidene fluoride, polymethyl methacrylate, polyethylene oxide, polystyrene, poly(diallyldimethylammonium)bis(trifluoromethanesulfonyl)imide (PDDA-TFSI), and poly(diallyldimethylammonium)bis(fluorosulfonyl)imide (PDDA-FSI).

[0017] The first lithium salt or the second lithium salt may be selected from LiTFSI, LiFSI, LiNO 3 and LiBr.

[0018] Based on 100 parts by weight of the first electrolyte solution, the first electrolyte membrane may further include one or more additives selected from CsI, LiI and LiNO3 in an amount of about 0.1 to 10 parts by weight, based on 100 parts by weight of the second electrolyte solution, and the second electrolyte membrane may further include one or more additives selected from CsI, LiI and LiNO3 in an amount of about 0.1 to 10 parts by weight.

[0019] The first electrolyte membrane and the second electrolyte membrane may each have a thickness of approximately 5 μm to 200 μm.

[0020] The first reinforcement layer and the second reinforcement layer may each have a porosity of about 30% to 90% and a thickness of about 3 μm to 100 μm.

[0021] The first reinforcement layer and the second reinforcement layer may each include one or more selected from the group consisting of polyethylene, polyethylene terephthalate, polypropylene, polytetrafluoroethylene, polyvinylidene fluoride, polyimide, cellulose, and glass fiber.

[0022] The diffusion prevention membrane may be selected from a sulfide-based solid electrolyte and an oxide-based solid electrolyte, which may have lithium ion conductivity.

[0023] The positive electrode composite may include a first positive electrode, a second positive electrode, and a porous structure disposed between the first and second positive electrodes, and the negative electrode composite may include a first negative electrode, a second negative electrode, and a negative electrode current collector disposed between the first and second negative electrodes.

[0024] The positive electrode composite material can be constructed so that the porous structure is stacked between the first positive electrode and the second positive electrode, or so that one surface and two edges of each of the first positive electrode and the second positive electrode are embedded in the porous structure, and the other surface of each of the first positive electrode and the second positive electrode forms the same layer with the porous structure.

[0025] The foldable lithium-air battery may have an electrode length ratio satisfying the following equation 1,

[0026] [Equation 1]

[0027] Electrode length ratio: positive electrode (L2) ≤ negative electrode (L4) < separator (L3) ≤ porous structure (L1)

[0028] (In Equation 1, the positive electrode (L2) is the first positive electrode or the second positive electrode, and the negative electrode (L4) is the first negative electrode or the second negative electrode).

[0029] In one aspect, a method for manufacturing a foldable lithium-air battery is provided, wherein the foldable lithium-air battery includes a positive electrode composite material, a negative electrode composite material, and a separator arranged between the positive electrode composite material and the negative electrode composite material, the method comprising: (a) preparing a separator; (b) bonding the separator to both surfaces of the positive electrode composite material by bending the separator to surround one edge of the positive electrode composite material; (c) bonding one surface of the negative electrode composite material to the separator; (d) bonding the separator to the other surface of the negative electrode composite material by bending the separator to surround an opposite edge of the negative electrode composite material opposite to one edge of the positive electrode composite material; (e) continuously stacking two or more positive electrode composite materials and negative electrode composite materials separated by separators by repeating (b) to (d) to manufacture a unit cell; and (f) manufacturing the foldable lithium-air battery by pressing the unit cell at a high temperature.

[0030] Preparing a separator may include: forming a first electrolyte membrane by impregnating a first electrolyte solution including a first ionic liquid, a first polymer, and a first lithium salt in a first reinforcement layer; forming an anti-diffusion membrane on the first electrolyte membrane; forming a second electrolyte membrane by impregnating a second electrolyte solution including a second ionic liquid, a second polymer, and a second lithium salt in a second reinforcement layer; and forming the second electrolyte membrane on the anti-diffusion membrane.

[0031] (f) may be performed by a hot pressing process at a temperature of about 70° C. to 100° C. and a pressure of about 1 bar to 5 bar.

[0032] The foldable lithium-air battery according to each exemplary embodiment of the present invention is configured so that a first electrolyte membrane and a second electrolyte membrane comprising ionic liquids suitable for the positive electrode composite material and the negative electrode composite material, respectively, can be formed, and a separator comprising an anti-diffusion membrane is applied between the first electrolyte membrane and the second electrolyte membrane. Therefore, electrode stability can be ensured, and a decrease in durability and electrolyte volatilization due to the transfer and diffusion of materials can be prevented. In addition, stability can be improved by reducing the risk of explosion and fire caused by existing volatile liquid electrolyte solutions.

[0033] The separator of the foldable lithium-air battery according to various exemplary embodiments of the present invention is configured such that the first electrolyte membrane and the second electrolyte membrane include a reinforcement layer, thereby improving durability and mechanical properties while enhancing battery performance due to excellent ion conductivity.

[0034] In addition, the foldable lithium-air battery according to each exemplary embodiment of the present invention is configured so that the positive electrode composite material and the negative electrode composite material separated by the separator are repeatedly stacked, and the separator is bent to surround the edges of the positive electrode composite material and the negative electrode composite material, thereby forming a zigzag-shaped battery. Therefore, due to the improved energy density, the battery capacity and battery life can be increased, while the electrode short circuit can be prevented, and the air can be smoothly supplied and exhausted, thereby improving the battery performance.

[0035] The effects of the present invention are not limited to the above-mentioned effects. It should be understood that the effects of the present invention include all effects derived from the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a cross-sectional view showing an exemplary separator of an exemplary foldable lithium-air battery according to an exemplary embodiment of the present invention;

[0037] Figure 2 is a plan view of an exemplary foldable lithium-air battery according to an exemplary embodiment of the present invention;

[0038] Figure 3is a cross-sectional view of an exemplary foldable lithium-air battery taken along line AA according to an exemplary embodiment of the present invention;

[0039] Figure 4 is a cross-sectional view of an exemplary foldable lithium-air battery taken along line BB according to an exemplary embodiment of the present invention;

[0040] Figure 5 is a cross-sectional view of an exemplary foldable lithium-air battery taken along line BB according to an exemplary embodiment of the present invention;

[0041] Figure 6 is a cross-sectional view showing an exemplary stacking structure of unit cells of an exemplary foldable lithium-air battery according to an exemplary embodiment of the present invention;

[0042] Figure 7 is a perspective view of a unit cell of an exemplary foldable lithium-air battery according to an exemplary embodiment of the present invention;

[0043] Figure 8 ion conductivity curves of foldable lithium-air batteries manufactured according to exemplary embodiments 1 and 2 of the present invention and comparative examples 1 and 2;

[0044] Figure 9 A charge and discharge curve diagram of a foldable lithium-air battery manufactured according to embodiment 1 of the present invention;

[0045] Figure 10 A charge and discharge curve diagram of a foldable lithium-air battery manufactured according to embodiment 2 of the present invention;

[0046] Figure 11 is a charge and discharge curve diagram of the foldable lithium-air battery manufactured according to Comparative Example 1;

[0047] Figure 12 is a charge and discharge curve diagram of the foldable lithium-air battery manufactured according to Comparative Example 2;

[0048] Figure 13 ion conductivity curves of foldable lithium-air batteries manufactured according to Embodiment 3 of the present invention and Comparative Examples 3 to 6;

[0049] Figure 14 Graph showing the number of charge and discharge cycles of foldable lithium-air batteries manufactured according to Embodiments 4 to 7 of the present invention and Comparative Example 7. DETAILED DESCRIPTION

[0050] The above and other objects, features and other advantages of the present invention will be more clearly understood by the following detailed description presented in conjunction with the accompanying drawings. However, the present invention should not be construed as being limited to the embodiments set forth herein. On the contrary, the embodiments described herein are provided to make the present invention thorough and complete, and to fully convey the spirit of the present invention to those skilled in the art.

[0051] In the accompanying drawings, the same reference numerals represent the same elements. In the accompanying drawings, the size of the structure may be exaggerated for clarity. Terms such as "first" and "second" may be used to describe various components, but they should not limit the various components. These terms are only used to distinguish one component from other components. For example, a first component may be referred to as a second component, and a second component may be referred to as a first component, etc., without departing from the spirit and scope of the present invention. A singular form may include a plural form as long as it is not specifically mentioned in a sentence.

[0052] Here, terms such as "including" or "having" indicate the presence of one or more features, values, steps, operations, elements, components, or combinations described in this specification, but do not exclude the possibility of the presence or addition of one or more other features, values, steps, operations, elements, components, or combinations thereof. In addition, when a part (such as a layer, film, region, or sheet) is "on" another part, it means that the part is "directly above" the other part and that an intermediate part is provided between the parts. On the other hand, when a part (such as a layer, film, region, or sheet) is "under" another part, it means that the part is "directly under" the other part and that an intermediate part is provided between the parts.

[0053] Unless otherwise defined, all numbers, values and / or expressions used in this specification to represent the amounts of components, reaction conditions, polymer compositions and formulations are essentially approximate values, which reflect the various uncertainties that arise when obtaining these values, and, among other things, these values are modified by the term "about". Unless otherwise stated or obvious from the context, the term "about" as used herein is understood to be within the normal tolerance range of this field, for example, within 2 average standard deviations. "About" can be understood to be within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05% or 0.01% of the specified value. Unless obvious from the context, all numerical values provided herein are modified by the term "about".

[0054] In addition, in the case of numerical ranges disclosed herein, unless otherwise stated, these ranges are continuous and cover all values from the minimum value to the maximum value. In addition, in the case of integers represented by these ranges, unless otherwise stated, all integers from the minimum value to the maximum value are included.

[0055] Hereinafter, the present invention will be described in more detail.

[0056] The present invention relates to a foldable lithium-air battery 100 or 100' and a method for manufacturing the same. The foldable lithium-air battery 100 or 100' comprises a first electrolyte membrane 131 and a second electrolyte membrane 133 comprising ionic liquids suitable for the positive electrode and the negative electrode, respectively. A separator 130 comprising an anti-diffusion membrane 132 is applied between the first electrolyte membrane 131 and the second electrolyte membrane 133, thereby ensuring electrode stability and preventing a decrease in durability and electrolyte volatilization due to material transfer and diffusion. In addition, stability can be improved by reducing the risk of explosion or fire caused by existing volatile liquid electrolyte solutions.

[0057] The first electrolyte membrane 131 and the second electrolyte membrane 133 of the separator 130 may include a reinforcement layer to improve durability and mechanical properties while enhancing battery performance due to excellent ionic conductivity. In addition, the positive electrode composite material 110 or 110 ' and the negative electrode composite material 120 separated by the separator 130 can be repeatedly stacked. The separator 130 can be bent to surround the edges of the positive electrode composite material 110 or 110 ' and the negative electrode composite material 120, thereby forming a zigzag-shaped battery. Therefore, due to the improved energy density, the battery capacity and battery life can be increased, while the electrode short circuit can be prevented, and the air can be smoothly supplied and exhausted, thereby improving battery performance.

[0058] Preferably, the foldable lithium-air battery 100 or 100' may include a positive electrode composite material 110 or 110', a negative electrode composite material 120, and a separator 130. The separator 130 is disposed between the positive electrode composite material 110 or 110' and the negative electrode composite material 120, and may be bent to surround one edge of the positive electrode composite material 110 or 110' and an opposite edge of the negative electrode composite material 120 that is opposite to one edge of the positive electrode composite material 110 or 110', thereby forming a zigzag shape. The separator 130 may include a first electrolyte membrane 131 in contact with the positive electrode composite material 110 or 110', a second electrolyte membrane 133 in contact with the negative electrode composite material 120, and an anti-diffusion membrane 132 disposed between the first electrolyte membrane 131 and the second electrolyte membrane 133.

[0059] Figure 1 FIG. 1 is a cross-sectional view showing an exemplary separator 130 of a foldable lithium-air battery 100 or 100 ′ according to an exemplary embodiment of the present invention. Figure 1As shown, the separator 130 includes a first electrolyte membrane 131 bonded to the positive electrode composite material 110 or 110', a second electrolyte membrane 133 bonded to the negative electrode composite material 120, and an anti-diffusion membrane 132 formed between the first electrolyte membrane 131 and the second electrolyte membrane 133. In addition, since the first electrolyte membrane 131 and the second electrolyte membrane 133 include the first reinforcement layer 134 and the second reinforcement layer 135, the mechanical properties and ionic conductivity of the electrolyte membrane can be improved at the same time.

[0060] The first electrolyte membrane 131 may include a first reinforcement layer 134 and a first electrolyte solution impregnated in the first reinforcement layer 134. The second electrolyte membrane 133 may include a second reinforcement layer 135 and a second electrolyte solution impregnated in the second reinforcement layer 135. Here, the first electrolyte membrane 131 may include the first reinforcement layer 134 and the first electrolyte solution at a weight ratio of about 1:1 to 3, and the second electrolyte membrane 133 may include the second reinforcement layer 135 and the second electrolyte solution at a weight ratio of about 1:1 to 3.

[0061] When the mixing ratio by weight of the first reinforcement layer 134 and the first electrolyte solution in the first electrolyte membrane 131 is less than about 1:1, the ion conductivity of the electrode can be improved, but the weight of the battery increases, and thus the fuel efficiency may be reduced. The mixing ratio of the second reinforcement layer 135 and the second electrolyte solution in the second electrolyte membrane 133 may have the same significance as that of the first electrolyte membrane 131.

[0062] Based on the total weight of the first electrolyte solution, the first electrolyte solution may include a first ionic liquid in an amount of approximately 45% to 60% by weight, a first polymer in an amount of approximately 25% to 30% by weight, and a first lithium salt in an amount of approximately 15% to 25% by weight. Based on the total weight of the second electrolyte solution, the second electrolyte solution may include a second ionic liquid in an amount of approximately 45% to 60% by weight, a second polymer in an amount of approximately 25% to 30% by weight, and a second lithium salt in an amount of approximately 15% to 25% by weight. The first electrolyte solution can inhibit the polymer decomposition reaction caused by active oxygen radicals on the positive electrode, and the second electrolyte solution can inhibit the reductive decomposition reaction of lithium on the negative electrode, thereby extending battery life. When the content of both the first ionic liquid and the second ionic liquid is less than approximately 45% by weight, ionic conductivity may decrease, and thus battery performance may decline. Conversely, when the content of both the first ionic liquid and the second ionic liquid is greater than approximately 60% by weight, ionic conductivity may increase, but the properties of the electrolyte may decline, making it difficult to form the appearance of the electrolyte membrane.

[0063] The first ionic liquid may be an ionic liquid that is resistant to the high voltage of the positive electrode composite material 110 or 110' and has strong corrosion resistance to the intermediate reaction product oxygen free radicals. The first ionic liquid may be appropriately selected from 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMIm-TFSI), 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIm-FSI), N-trimethyl-N-propylammonium bis(trifluoromethanesulfonyl)imide (EMIm-TFSI), 1113 -TFSI), N-trimethyl-N-propylammonium bis(fluorosulfonyl)imide (N 1113 -FSI), N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide (DEME-TFSI), N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(fluorosulfonyl)imide (DEME-FSI), 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (P 14 -TFSI) and 1-butyl-1-methylpyrrolidinium bis(fluorosulfonyl)imide (P 14 The first electrolyte solution including the first ionic liquid can prevent polymer decomposition reactions caused by active oxygen radicals generated at the positive electrode composite material 110 or 110' during charge and discharge, thereby improving battery life characteristics.

[0064] The second ionic liquid may have excellent chemical resistance to the negative electrode composite material 120 without damaging the surface bonded to the second electrolyte membrane 133 (even when the volume of the negative electrode composite material 120 changes). The second ionic liquid may suitably include a bis(trifluoromethanesulfonyl)imide (P 13 -TFSI), N-methyl-N-propylpyrrolidinium bis(fluorosulfonyl)imide (P 13 -FSI), N-methyl-N-propylpyridinium bis(trifluoromethanesulfonyl)imide (PP 13 -TFSI), N-methyl-N-propylpyridinium bis(fluorosulfonyl)imide (PP 13 -FSI), 1-butyl-1-methylpiperidinium bis(trifluoromethanesulfonyl)imide (PP 14 -TFSI) and 1-butyl-1-methylpiperidinium bis(fluorosulfonyl)imide (PP 14 When the second electrolyte solution including the second ionic liquid contacts the negative electrode composite material 120, it can prevent the reduction decomposition reaction of lithium, thereby improving battery life characteristics.

[0065] The polymer (i.e., the first polymer and the second polymer) can have excellent chemical resistance and corrosion resistance to the positive electrode composite material 110 or 110 'and the negative electrode composite material 120, and can be excellent in preventing fluidity and maintaining the shape of the electrolyte membrane. The polymer may appropriately include one or more selected from polyvinylidene fluoride, polymethyl methacrylate, polyethylene oxide, polystyrene, poly(diallyldimethylammonium)bis(trifluoromethanesulfonyl)imide (PDDA-TFSI), poly(diallyldimethylammonium)bis(fluorosulfonyl)imide (PDDA-FSI) and combinations thereof. The polymers contained in the first electrolyte solution and the second electrolyte solution may be the same or different from each other. When the content of the polymer is less than about 45% by weight, it is difficult to prevent the fluidity of the electrolyte membrane. On the contrary, when the content of the polymer is greater than about 60% by weight, the ionic conductivity may be significantly reduced.

[0066] The lithium salt (i.e., the first lithium salt and the second lithium salt) may suitably include one or more selected from LiTFSI, LiFSI, LiNO3, and LiBr. The lithium salts contained in the first electrolyte solution and the second electrolyte solution may be the same as or different from each other. When the content of the lithium salt is less than about 15 wt%, the battery performance may decrease. On the contrary, when the content of the lithium salt is greater than about 25 wt%, the lithium salt may no longer dissolve in the ionic liquid, making it difficult to prepare the electrolyte solution.

[0067] The first electrolyte membrane 131 may further include one or more additives selected from CsI, LiI, and LiNO3 in an amount of about 0.1 to 10 parts by weight based on 100 parts by weight of the first electrolyte solution. The second electrolyte membrane 133 may further include one or more additives selected from CsI, LiI, LiNO3, and combinations thereof in an amount of about 0.1 to 10 parts by weight based on 100 parts by weight of the second electrolyte solution. The additives may be mixed with each other to improve the durability of the first electrolyte membrane 131 and the second electrolyte membrane 133. When the content of the additive is less than about 0.1 parts by weight, the effect of improving durability may be insufficient. Conversely, when the content of the additive is greater than about 10 parts by weight, the effect of improving durability may not be obtained.

[0068] The first electrolyte membrane 131 and the second electrolyte membrane 133 may each have a thickness of approximately 5 μm to 200 μm. In this regard, when the thickness of each of the first electrolyte membrane 131 and the second electrolyte membrane 133 is less than approximately 5 μm, it may be difficult to ensure the mechanical strength of the electrolyte membrane, and short circuits may occur during operation. Conversely, when the thickness is greater than approximately 200 μm, battery performance may be reduced due to reduced ionic conductivity.

[0069] The first and second reinforcement layers 134 and 135 can have a porosity of approximately 30% to 90% and a thickness of approximately 3 μm to 100 μm, allowing for smooth impregnation with the first and second electrolyte solutions and excellent mechanical strength. In this regard, when the thickness of each of the first and second reinforcement layers 134 and 135 is less than approximately 3 μm, ensuring mechanical rigidity is difficult. Conversely, when the thickness is greater than approximately 100 μm, ionic conductivity may decrease. Furthermore, when the porosity of each of the first and second reinforcement layers 134 and 135 is less than approximately 30%, impregnation of the first and second ionic liquids may become difficult, and ionic conductivity may be low. Conversely, when the porosity of each of the first and second reinforcement layers 134 and 135 is greater than approximately 95%, ensuring mechanical rigidity is difficult, and short circuits may occur due to the formation of lithium dendrites during charging and discharging. Preferably, the porosity is suitably within the range of approximately 45% to 90%.

[0070] The first and second reinforcement layers 134 and 135 can be configured such that the contact angles of the first and second electrolyte solutions with the surfaces of the first and second reinforcement layers 134 and 135 are approximately 5° to 90°. When the contact angle is less than approximately 5°, the fluidity of the electrolyte solution is too high to form an electrolyte membrane. Conversely, when the contact angle is greater than 90°, impregnation of the ionic liquid may become difficult, and the ionic conductivity may be low. Preferably, the contact angle may be in the range of approximately 20° to 80°.

[0071] Each of the first reinforcement layer 134 and the second reinforcement layer 135 may suitably include one or more selected from polyethylene, polyethylene terephthalate, polypropylene, polytetrafluoroethylene, polyvinylidene fluoride, polyimide, cellulose, and glass fiber.

[0072] The diffusion barrier 132 can be used to prevent the first electrolyte solution of the first electrolyte membrane 131 and the second electrolyte solution of the second electrolyte membrane 133 from mixing with each other, or to prevent the diffusion of organic ion components. In addition, it can be a lithium ion conductor of an organic component or an inorganic component, thereby preventing electrochemical decomposition at the positive electrode and the negative electrode. The diffusion barrier 132 can appropriately include one or more of a sulfide-based solid electrolyte and an oxide-based solid electrolyte. The sulfide-based solid electrolyte and the oxide-based solid electrolyte can use any material known to those skilled in the art. For example, the sulfide-based solid electrolyte may suitably include a sulfide-based solid electrolyte selected from the group consisting of Li2S-P2S5, Li2S-P2S5-LiI, Li2S-P2S5-LiCl, Li2S-P2S5-LiBr, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (m and n are positive numbers, Z is one of Ge, Zn and Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li x MO y (x and y are positive numbers, M is one of P, Si, Ge, B, Al, Ga and In) and Li 10 GeP2S 12 In addition, the oxide-based solid electrolyte may suitably include a garnet-type solid electrolyte (e.g., Li7La3Zr2O 12 (LLZO)), NASICON-type solid electrolytes (e.g., Na 1+x Zr2Si2P 3-x O 12 (0≤x≤3)), LISICON type solid electrolyte (for example, γ-Li3PO4), perovskite type solid electrolyte, etc.

[0073] Figure 2 1 is a plan view of an exemplary lithium-air battery 100 according to an exemplary embodiment of the present invention. Separator 130 is formed between positive electrode composite material 110 and negative electrode composite material 120. In addition, in the case of positive electrode composite material 110, it is shown that the length of porous structure 113 is greater than that of negative electrode composite material 120 and separator 130. In addition, current collector 140 protrudes from negative electrode composite material 120.

[0074] Figure 31 is a cross-sectional view of an exemplary lithium-air battery 100 according to an exemplary embodiment of the present invention, taken along line AA. Positive electrode composite materials 110 and negative electrode composite materials 120 are alternately stacked, separated by separators 130. Separator 130 is in contact with one surface of positive electrode composite material 110, curved to surround one edge, and then in contact with the other surface of positive electrode composite material 110. Furthermore, negative electrode composite material 120 is stacked on separator 130, and separator 130 is in contact with one surface of negative electrode composite material 120, curved to surround an edge of negative electrode composite material 120 opposite to one edge of positive electrode composite material 110, and then in contact with the other surface of negative electrode composite material 120.

[0075] Two or more positive electrode composite materials 110 and negative electrode composite materials 120 separated by separators 130 may be stacked in succession. When the positive electrode composite materials 110 and negative electrode composite materials 120 separated by separators 130 in a zigzag shape are alternately stacked, the adhesion between the electrodes can be increased. Therefore, even if an impact is applied to the battery, a short circuit caused by pushing the electrodes can be prevented.

[0076] The positive electrode composite material 110 or 110' may include a first positive electrode 111 or 111', a second positive electrode 112 or 112', and a porous structure 113 or 113' disposed between the first positive electrode 111 or 111' and the second positive electrode 112 or 112'. Preferably, the positive electrode composite material 110 or 110' may be configured such that the porous structure 113 is stacked between the first positive electrode 111 and the second positive electrode 112, or such that one surface and both edges of each of the first positive electrode 111' and the second positive electrode 112' are embedded in the porous structure 113', and the other surface of each of the first positive electrode 111' and the second positive electrode 112' forms the same layer as the porous structure 113'.

[0077] Figure 4 1 is a cross-sectional view of a lithium-air battery 100 according to an exemplary embodiment of the present invention taken along line BB. The separator 130 is bonded between the positive electrode composite material 110 and the negative electrode composite material 120. In particular, Figure 4 The positive electrode composite material 110 is configured such that the porous structure 113 is stacked between the first positive electrode 111 and the second positive electrode 112. In this regard, it is shown that the first positive electrode 111 or the second positive electrode 112 has the same length as the negative electrode composite material.

[0078] Figure 5 FIG is a cross-sectional view of a lithium-air battery 100' taken along line BB according to an exemplary embodiment of the present invention. Figure 3 The overall structure is the same. However, Figure 5Positive electrode composite material 110' is constructed such that one surface and both edges of each of first positive electrode 111' and second positive electrode 112' are embedded in porous structure 113'. In this regard, the other surfaces of each of first positive electrode 111' and second positive electrode 112' form a common layer with porous structure 113'. Therefore, positive electrode composite material 110' has the advantage that first positive electrode 111' and second positive electrode 112' are embedded in porous structure 113', thereby reducing battery thickness and volume.

[0079] The foldable lithium-air battery 100 or 100 ′ may have an electrode length ratio satisfying Equation 1 below.

[0080] [Equation 1]

[0081] Electrode length ratio: positive electrode L2 ≤ negative electrode LA < separator L3 ≤ porous structure L1

[0082] (In Equation 1, the positive electrode L2 is the length of the first positive electrode or the second positive electrode, and the negative electrode L4 is the length of the first negative electrode or the second negative electrode).

[0083] like Figure 4 and Figure 5 As shown, the electrode length L1 of the porous structure formed should be greater than the length L3 of the diaphragm. Therefore, when the length L1 of the porous structure formed is longer, this enables the supply of reaction gas and the discharge of product gas to be carried out smoothly, thereby improving battery performance. The length L3 of the diaphragm can be equal to or less than the length L1 of the porous structure, thereby forming a longer porous structure L1. In addition, in order to prevent a short circuit between the diaphragm of length L3 and the positive electrode of length L2 or the negative electrode of length L4, the diaphragm length is preferably greater than the length L2 of the positive electrode and the length L4 of the negative electrode. In addition, the electrode length L2 of the positive electrode can be equal to or less than the electrode length L4 of the negative electrode. In particular, when the electrode length L2 of the positive electrode is less than the electrode length L4 of the negative electrode, a short circuit due to the growth of lithium dendrites on the negative electrode can be prevented.

[0084] In the positive electrode composite material 110 or 110', the first positive electrode 111 or 111' and the second positive electrode 112 or 112' each include a carbon material and a binder. In this regard, the first positive electrode 111 or 111' and the second positive electrode 112 or 112' can be used to reduce oxygen.

[0085] The carbon material may suitably include one or more carbons selected from activated carbon, carbon nanotubes, carbon nanofibers, and supported metal oxide-based catalysts. In particular, the carbons supported metal oxide-based catalysts may include carbons supported metal oxide-based catalysts selected from cobalt oxide, ruthenium oxide, iridium oxide, magnesium oxide, nickel oxide, and titanium oxide.

[0086] The binder may suitably include one or more selected from polyvinylidene fluoride, polytetrafluoroethylene, styrene-butadiene rubber, and ethylene oxide.

[0087] The porous structure 113 or 113' can be used to supply or exhaust oxygen or air. For example, the porous structure 113 or 113' can include a carbon porous body or foam metal.

[0088] The carbon porous body may suitably include one or more of carbon felt, carbon paper, and carbon cloth. The carbon cloth may be a sheet-like fabric using carbon fibers.

[0089] The negative electrode composite material 120 may include a first negative electrode 121, a second negative electrode 122, and a negative electrode current collector 123 disposed between the first negative electrode 121 and the second negative electrode 122. In this regard, the first negative electrode 121 and the second negative electrode 122 may each be lithium metal. The negative electrode current collector 123 may serve as a movement path for the battery. The negative electrode current collector 123 may be selected from copper, nickel, stainless steel, molybdenum, tungsten, and tantalum. The negative electrode current collector 123 may also include a collector tab 140 protruding in one direction.

[0090] Provided is a method for manufacturing a foldable lithium-air battery 100 or 100 ′ including a positive electrode composite material, a negative electrode composite material 120 , and a separator 130 disposed between the positive and negative electrode composite materials 120 . The method may include: (a) a step of preparing a separator 130; (b) a step of bonding the separator 130 to both surfaces of the positive electrode composite material by bending the separator to surround one edge of the positive electrode composite material; (c) a step of bonding one surface of the negative electrode composite material 120 to the separator 130; (d) a step of bonding the separator 130 to the other surface of the negative electrode composite material 120 by bending the separator to surround an opposite edge of the negative electrode composite material 120 opposite to one edge of the positive electrode composite material; (e) a step of continuously stacking two or more positive electrode composite materials and negative electrode composite materials 120 separated by separators 130 by repeating steps (b) to (d) to manufacture a unit cell; and (f) a step of manufacturing a foldable lithium-air battery 100 or 100' by pressing the unit cell at a high temperature.

[0091] The unit cell manufactured by repeatedly performing steps (b) to (d) may be configured such that the separator 130 may be stacked between the positive electrode composite material 110 or 110 ′ and the negative electrode composite material 120 in a zigzag shape, as shown in FIG. Figure 2 As shown in section AA.

[0092] Figure 6is a cross-sectional view showing an exemplary stacking structure of unit cells of an exemplary lithium-air battery 100 according to an exemplary embodiment of the present invention. Figure 7 FIG. 1 is a perspective view of an exemplary unit cell of an exemplary lithium-air battery 100 according to an exemplary embodiment of the present invention. Figure 6 and Figure 7 It is shown that a unit cell manufactured by stacking two or more positive electrode composite materials 110 and negative electrode composite materials 120 separated by a zigzag-shaped separator 130 is inserted into a through-type casing 150 so that a cross section AA is exposed at the inlet end a and the outlet end b. Although the inlet end a and the outlet end b may penetrate in the corresponding directions, the present invention is not limited thereto, and various structures that can easily supply and exhaust the reaction gas are possible. Figure 7 Reference numeral a denotes an inlet end for supplying reaction gas, and reference numeral b denotes an outlet end for discharging product gas. Depending on the structure, it may be arranged in a vertical direction. In addition, the unit cell may further include a separator cover, which closes the inlet end a and the outlet end b to maintain the pressure in the battery, thereby forming an airtight structure. Preferably, the pressure in the battery may preferably range from about 1 bar to 10 bar. In addition, the collector sheet 140 may protrude from one surface of the housing 150. The collector sheet 140 includes a positive electrode collector sheet and a negative electrode collector sheet. The collector sheet 140 of the unit cell may be arranged in various directions that are convenient for use of the battery. The unit cells manufactured by step (e) may be assembled in various structures and configurations to manufacture the lithium-air battery 100.

[0093] The structure in which one surface and both edges of each of the first positive electrode 111' and the second positive electrode 112' are embedded in the porous structure 113' can be manufactured by the following steps: bonding the first positive electrode 111' and the second positive electrode 112' to both surfaces of the porous structure; bonding the porous structure to both edges of each of the first positive electrode 111' and the second positive electrode 112'. In this regard, the porous structure 113' can have the same height as the two edges of the first positive electrode 111' and the second positive electrode 112'. Alternatively, the structure can be manufactured by directly forming the first positive electrode 111' and the second positive electrode 112' embedded in the porous structure 113'.

[0094] The steps of preparing the separator 130 may include the following steps: forming a first electrolyte membrane 131 by impregnating a first electrolyte solution including a first ionic liquid, a first polymer and a first lithium salt in a first reinforcement layer 134; forming an anti-diffusion membrane 132 on the first electrolyte membrane 131; forming a second electrolyte membrane 133 by impregnating a second electrolyte solution including a second ionic liquid, a second polymer and a second lithium salt in a second reinforcement layer 135; and forming the second electrolyte membrane 133 on the anti-diffusion membrane 132.

[0095] The step (f) may be performed by a hot pressing process at a temperature of about 70 to 100° C. and a pressure of about 1 to 5 bar.

[0096] Example

[0097] Hereinafter, although the present invention is described in detail based on preferred embodiments, the present invention is not limited to the following embodiments.

[0098] Embodiments 1 and 2 and Comparative Examples 1 and 2

[0099] Porous carbon nanotubes impregnated with polyvinylidene fluoride binder were used as the positive electrode, a lithium negative electrode was used as the negative electrode, porous carbon felt was used as the porous structure 113, and SUS was used as the negative electrode current collector.

[0100] Positive electrode composite material 110 is manufactured by bonding first positive electrode 111 and second positive electrode 112 to both surfaces of porous structure 113. Furthermore, negative electrode composite material 120 is manufactured by bonding first negative electrode 121 and second negative electrode 122 to both surfaces of negative electrode current collector 123. Separator 130 is then bonded to both surfaces of positive electrode composite material 110 by bending the separator around one edge of positive electrode composite material 110. Subsequently, one surface of negative electrode composite material 120 is bonded to separator 130, which is bent around one edge of negative electrode composite material 120 before being bonded to the other surface of negative electrode composite material 120. By repeating these steps, a unit cell is manufactured, in which two positive electrode composite materials 110 and two negative electrode composite materials 120 are sequentially stacked, separated by separator 130. The unit cell is then subjected to a hot pressing process at 80°C and 2 bar, thereby manufacturing lithium-air battery 100. In this regard, the length of each electrode of the manufactured lithium-air battery 100 is set to satisfy the following length ratio: positive electrode ≤ negative electrode < separator ≤ porous structure.

[0101] Separator 130 was manufactured using the following method. The first and second reinforcement layers were impregnated with the first and second electrolyte solutions having the compositions shown in Table 1, respectively, to form first and second electrolyte membranes. EMIm-TFSI was used as the first and second electrolyte solutions. A diffusion barrier containing a sulfide-based solid electrolyte was formed between the first and second electrolyte membranes to produce the separator.

[0102] Table 1

[0103]

[0104]

[0105] Embodiments 3 to 7 and Comparative Examples 3 to 7

[0106] 50 wt % of a first ionic liquid, 30 wt % of a polymer, and 20 wt % of a lithium salt were mixed to prepare a first electrolyte solution, and 50 wt % of a second ionic liquid, 30 wt % of a polymer, and 20 wt % of a lithium salt were mixed to prepare a second electrolyte solution. A lithium-air battery was manufactured by the same method as in Embodiment 1, except that the types of the first ionic liquid and the second ionic liquid were changed to those shown in Tables 2 and 3 below.

[0107] Table 2

[0108] category The first ionic liquid Second ionic liquid Implementation Plan 3 EMIm-TFSI <![CDATA[P 13 -TFSI]]> Implementation Plan 4 EMIm-TFSI EMIm-TFSI Implementation Plan 5 EMIm-TFSI <![CDATA[PP 14 -TFSI]]> Implementation Plan 6 EMIm-TFSI <![CDATA[N 1113 -TFSI]]> Implementation Plan 7 EMIm-TFSI DEME-TFSI

[0109] Table 3

[0110] category The first ionic liquid Second ionic liquid Comparative Example 3 EMIm-TFSI <![CDATA[P 13 -FSI]]> Comparative Example 4 <![CDATA[P 14 -TFSI]]> <![CDATA[P 13 -FSI]]> Comparative Example 5 DEME-TFSI <![CDATA[P 13 -FSI]]> Comparative Example 6 <![CDATA[N 1113 -TFSI]]> <![CDATA[P 13 -FSI]]> Comparative Example 7 <![CDATA[P 13 -FSI]]> <![CDATA[P 13 -FSI]]>

[0111] Experimental Example 1: Evaluation of ionic conductivity and charge / discharge cycle number as a function of the content of the first ionic liquid

[0112] In Embodiments 1 and 2 and Comparative Examples 1 and 2, after the fabricated foldable lithium-air batteries were charged and discharged, the ionic conductivity and the number of charge and discharge cycles were evaluated. The results are shown in FIG. Figures 8 to 12 middle.

[0113] Figure 8 Graphs showing ionic conductivity of foldable lithium-air batteries manufactured according to Embodiments 1 and 2 and Comparative Examples 1 and 2.

[0114] Figures 9 to 12 Graphs showing charge and discharge curves of foldable lithium-air batteries manufactured according to Embodiments 1 and 2 and Comparative Examples 1 and 2.

[0115] like Figures 8 to 12 As shown, as the ionic liquid content increases, the ionic conductivity and battery life are excellent. However, Comparative Example 2 shows the most excellent ionic conductivity, but due to the high content of the first and second ionic liquids, the physical properties of the first and second electrolyte membranes are weak, making it difficult to form an appearance. In addition, Comparative Example 1 shows the lowest ionic conductivity and exhibits a very short battery life due to the low content of the ionic liquid.

[0116] In contrast, it was confirmed that the electrolyte membranes of Embodiments 1 and 2 had smooth appearance and were well formed, while having excellent ion conductivity and battery life.

[0117] Experimental Example 2: Evaluation of ionic conductivity and charge / discharge cycles depending on the types of the first ionic liquid and the second ionic liquid

[0118] In Embodiments 3 to 7 and Comparative Examples 3 to 7, after the fabricated foldable lithium-air batteries were charged and discharged, ionic conductivity and charge-discharge cycle numbers were evaluated. The results are shown in FIG. Figure 13 and Figure 14 middle.

[0119] Figure 13 Graph showing the ionic conductivity of the foldable lithium-air batteries manufactured according to Embodiment 3 and Comparative Examples 3 to 6. Figure 13 As shown, it was confirmed that compared with Comparative Examples 3 to 6, the use of P 13- Embodiment 3, in which TFSI is used as the second ionic liquid, exhibits extremely excellent ionic conductivity.

[0120] Figure 14 Graph showing the number of charge and discharge cycles of the foldable lithium-air batteries manufactured according to Embodiments 4 to 7 and Comparative Example 7. Figure 14 , when using P 13- In the case of Comparative Example 7 in which TFSI was used as the first ionic liquid, the number of charge and discharge cycles was very low.

[0121] Therefore, since the first ionic liquid and the second ionic liquid selectively use components suitable for the positive electrode composite material and the negative electrode composite material, respectively, the ionic conductivity and battery performance can be significantly improved.

[0122] Although the present invention has been described with reference to the various exemplary embodiments shown in the accompanying drawings, it will be understood by those skilled in the art that the present invention may be changed and modified in various ways without departing from the scope of the invention described in the claims. Therefore, it should be understood that the above embodiments are only exemplary and not restrictive.

Claims

1. A foldable lithium-air battery, comprising: Positive electrode composite material; negative electrode composite material; as well as diaphragm, wherein the separator is disposed between the positive electrode composite material and the negative electrode composite material, the separator being bent to surround one edge of the positive electrode composite material and an opposite edge of the negative electrode composite material opposite to the one edge of the positive electrode composite material, thereby forming a zigzag shape, and The separator includes a first electrolyte membrane, a second electrolyte membrane and an anti-diffusion membrane, wherein the first electrolyte membrane contacts the positive electrode composite material, the second electrolyte membrane contacts the negative electrode composite material, and the anti-diffusion membrane is arranged between the first electrolyte membrane and the second electrolyte membrane. The first electrolyte membrane includes a first reinforcement layer and a first electrolyte solution impregnated in the first reinforcement layer, and the second electrolyte membrane includes a second reinforcement layer and a second electrolyte solution impregnated in the second reinforcement layer. The first electrolyte solution comprises a first ionic liquid, a first polymer and a first lithium salt, The second electrolyte solution comprises a second ionic liquid, a second polymer, and a second lithium salt, and The second ionic liquid is different from the first ionic liquid, The positive electrode composite material includes a first positive electrode, a second positive electrode and a porous structure, wherein the porous structure is disposed between the first positive electrode and the second positive electrode. The negative electrode composite material includes a first negative electrode, a second negative electrode and a negative electrode current collector, wherein the negative electrode current collector is disposed between the first negative electrode and the second negative electrode, The positive electrode composite material is configured such that the porous structure is stacked between the first positive electrode and the second positive electrode, or such that one surface and two edges of each of the first positive electrode and the second positive electrode are embedded in the porous structure, and the other surface of each of the first positive electrode and the second positive electrode forms the same layer with the porous structure, The foldable lithium-air battery has an electrode length ratio that satisfies the following equation 1, [Equation 1] Electrode length ratio: positive electrode L2 ≤ negative electrode L4 < diaphragm L3 ≤ porous structure L1 In Equation 1, the positive electrode L2 is the length of the first positive electrode or the second positive electrode, and the negative electrode L4 is the length of the first negative electrode or the second negative electrode.

2. The foldable lithium-air battery according to claim 1, wherein The first electrolyte membrane includes a first reinforcement layer and a first electrolyte solution in a weight ratio of 1:1 to 3, and The second electrolyte membrane includes a second reinforcement layer and a second electrolyte solution in a weight ratio of 1:1 to 3.

3. The foldable lithium-air battery according to claim 1, wherein The first electrolyte solution includes the first ionic liquid in an amount of 45 wt % to 60 wt %, the first polymer in an amount of 25 wt % to 30 wt %, and the first lithium salt in an amount of 15 wt % to 25 wt %, based on the total weight of the first electrolyte solution, and The second electrolyte solution includes the second ionic liquid in an amount of 45 to 60 wt %, the second polymer in an amount of 25 to 30 wt %, and the second lithium salt in an amount of 15 to 25 wt %, based on the total weight of the second electrolyte solution.

4. The foldable lithium-air battery according to claim 3, wherein: The first ionic liquid includes one or more selected from 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide, N-trimethyl-N-propylammonium bis(trifluoromethanesulfonyl)imide, N-trimethyl-N-propylammonium bis(fluorosulfonyl)imide, N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide, N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(fluorosulfonyl)imide, 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide and 1-butyl-1-methylpyrrolidinium bis(fluorosulfonyl)imide.

5. The foldable lithium-air battery according to claim 3, wherein: The second ionic liquid includes one or more selected from N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide, N-methyl-N-propylpyrrolidinium bis(fluorosulfonyl)imide, N-methyl-N-propylpiperidinium bis(trifluoromethanesulfonyl)imide, N-methyl-N-propylpiperidinium bis(fluorosulfonyl)imide, 1-butyl-1-methylpiperidinium bis(trifluoromethanesulfonyl)imide and 1-butyl-1-methylpiperidinium bis(fluorosulfonyl)imide.

6. The foldable lithium-air battery according to claim 3, wherein: The first polymer or the second polymer includes one or more selected from polyvinylidene fluoride, polymethyl methacrylate, polyethylene oxide, polystyrene, poly(diallyldimethylammonium)bis(trifluoromethanesulfonyl)imide, and poly(diallyldimethylammonium)bis(fluorosulfonyl)imide.

7. The foldable lithium-air battery according to claim 3, wherein: The first lithium salt or the second lithium salt includes one or more selected from LiTFSI, LiFSI, LiNO 3 and LiBr.

8. The foldable lithium-air battery according to claim 1, wherein: The first electrolyte membrane further comprises one or more additives in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the first electrolyte solution, the additives being selected from CsI, LiI, LiNO3, and The second electrolyte membrane further includes one or more additives selected from CsI, LiI, and LiNO 3 in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the second electrolyte solution.

9. The foldable lithium-air battery according to claim 1, wherein The first electrolyte membrane and the second electrolyte membrane each have a thickness of 5 μm to 200 μm.

10. The foldable lithium-air battery according to claim 1, wherein The first reinforcement layer and the second reinforcement layer each have a porosity of 30% to 90% and a thickness of 3 μm to 100 μm.

11. The foldable lithium-air battery according to claim 1, wherein: The first reinforcement layer and the second reinforcement layer are each selected from the group consisting of polyethylene, polyethylene terephthalate, polypropylene, polytetrafluoroethylene, polyvinylidene fluoride, polyimide, cellulose, and glass fiber.

12. The foldable lithium-air battery according to claim 1, wherein: The anti-diffusion membrane is selected from sulfide-based solid electrolytes and oxide-based solid electrolytes.

13. A method for manufacturing a foldable lithium-air battery, the foldable lithium-air battery comprising a positive electrode composite material, a negative electrode composite material, and a separator, wherein the separator is disposed between the positive electrode composite material and the negative electrode composite material, the method comprising: a) preparing a diaphragm; b) bonding the separator to both surfaces of the positive electrode composite by bending the separator to surround one edge of the positive electrode composite; c) bonding one surface of the negative electrode composite to the separator; d) bonding the separator to the other surface of the negative electrode composite by bending the separator to surround an opposite edge of the negative electrode composite that is opposite to one edge of the positive electrode composite; e) continuously stacking two or more positive electrode composite materials and negative electrode composite materials with a separator therebetween by repeating b) to d) to produce a unit cell; as well as f) Fabrication of foldable lithium-air batteries by pressing unit cells at high temperature, Wherein, preparing the diaphragm comprises: forming a first electrolyte membrane by impregnating a first electrolyte solution including a first ionic liquid, a first polymer, and a first lithium salt in the first reinforcement layer; forming an anti-diffusion film on the first electrolyte membrane; forming a second electrolyte membrane by impregnating a second electrolyte solution including a second ionic liquid, a second polymer, and a second lithium salt in the second reinforcement layer; and forming a second electrolyte membrane on the diffusion prevention membrane, The first electrolyte solution comprises a first ionic liquid, a first polymer and a first lithium salt, The second electrolyte solution includes a second ionic liquid, a second polymer, and a second lithium salt, and the second ionic liquid is different from the first ionic liquid.

14. The method for manufacturing a foldable lithium-air battery according to claim 13, wherein: f) is performed by a hot pressing process at a temperature of 70° C. to 100° C. and a pressure of 1 bar to 5 bar.

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