Polymer gel electrolyte for metal air cell and method for manufacturing the same, and flexible metal air cell using the same

Abstract

A polymer gel electrolyte for a metal-air battery and a method for manufacturing the same, which can lower the overpotential of oxygen reduction and oxygen evolution reactions and exhibit excellent stability of the metal-air battery during long-term charge-discharge cycles by using a redox medium, are disclosed, as well as a flexible metal-air battery using the same. The polymer gel electrolyte for a metal-air battery according to the present invention comprises a polymer having hydrophilic groups; a redox medium; and a hydroxide salt; and is characterized by having a gel form.

Description

Technology Field

[0001] The present invention relates to a polymer gel electrolyte for a metal-air battery comprising an organic acid chelating agent and a method for manufacturing the same. Background Technology

[0003] A metal-air battery refers to a battery in which a metal such as lithium, zinc, magnesium, or aluminum is used for the anode, and an air diffusion electrode such as an oxygen electrode is used for the cathode.

[0004] In a zinc-air battery, during discharge, the zinc anode is oxidized to zinc ions (Zn 2+ ) and electrons are generated, and at the anode, external oxygen is reduced to hydroxide ions (OH - ) is generated.

[0005] Hydroxide ions generated by the oxygen reduction reaction (ORR) at the anode move through the electrolyte to the cathode and are used in the oxidation reaction of zinc at the cathode.

[0006] For example, a zinc-air battery enables the generation of electricity through the following reactions at the negative and positive electrodes.

[0007] [discharge of electricity]

[0008] Cathode: Zn + 4OH - → Zn(OH)4 2- + 2e - (E0= -1.25 V)

[0009] Zn(OH)4 2- → ZnO + H2O + 2OH -

[0010] Anode: O2 + 2H2O + 4e - → 4OH - (E0= +0.40 V)

[0011] (Oxygen reduction reaction)

[0012] Overall reaction: 2Zn + O2 → 2ZnO (E0=1.65 V)

[0014] During charging, conversely, zinc ions are reduced to zinc metal at the cathode, and hydroxide ions are oxidized at the anode to generate oxygen (OER, Oxygen evolution reaction).

[0015] [charge]

[0016] Cathode: Zn 2+ + 2e - → Zn

[0017] Anode: 4OH - → O2 + 2H2O + 4e - (Oxygen evolution reaction)

[0019] As such, a metal-air battery generates electricity by collecting electrons produced when a metal reacts with oxygen in the air within an electrolyte.

[0020] Metal-air batteries generate an electric current as electrons collected at the negative electrode move to the positive electrode.

[0021] Metal-air batteries have the advantage of being lightweight by using oxygen from the air as the active material for the positive electrode.

[0022] Metal-air batteries have a structure similar to fuel cells, and because they utilize relatively safe and inexpensive metals for their negative electrode materials, they possess a capacity of up to tens of times greater than that of conventional lithium-ion-based batteries.

[0023] In addition, metal-air batteries not only possess characteristics suitable for high capacity required for electrical energy storage and transportation equipment such as automobiles, but also have the advantage of being environmentally friendly.

[0024] However, despite having high energy density, metal-air batteries have difficulty practically realizing their full theoretical energy density.

[0025] For example, metal-air batteries have a problem in that charging and discharging do not occur smoothly due to the slow redox reaction rate of oxygen gas.

[0026] In particular, metal-air batteries have a problem in that the efficiency of the battery is reduced due to a low discharge voltage (< 1.2 V) and a high charge voltage (>2.0 V) caused by high overpotential due to polarization during the oxygen reduction reaction (ORR) or oxygen evolution reaction (OER).

[0027] To address this, solid oxygen evolution catalysts were previously used in the oxygen electrode; however, there is a problem in that it is difficult to solve the polarization issue due to the small reaction surface area of ​​the catalyst particles and low catalytic activity.

[0028] Therefore, there is still a need for the development of metal-air batteries that can solve the problem of high overvoltage in oxygen reduction and oxygen evolution reactions and improve charge / discharge capacity and lifespan. The problem to be solved

[0030] The objective of the present invention is to provide a flexible metal-air battery and a polymer gel electrolyte that can increase the charge-discharge efficiency and capacity of the metal-air battery and exhibit excellent stability during long-term charge-discharge cycles by using a polymer gel electrolyte containing a redox mediator (RM).

[0031] In addition, the objective of the present invention is to provide a polymer gel electrolyte that enables self-charging of a metal-air battery.

[0032] In addition, the objective of the present invention is to provide a metal-air battery using a polymer gel electrolyte.

[0034] The objects of the present invention are not limited to those mentioned above, and other unmentioned objects and advantages of the present invention may be understood from the following description and will be more clearly understood by the embodiments of the present invention. Furthermore, it will be readily apparent that the objects and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims. means of solving the problem

[0036] The polymer gel electrolyte for a metal-air battery according to the present invention comprises a polymer having hydrophilic groups; a redox medium; and a hydroxide salt; and is characterized by having a gel form.

[0037] The polymer having the above hydrophilic group may include one or more of polyvinyl alcohol (PVA), polyacrylamide (PAM), polyacrylic acid (PAA), sodium polyacrylate (PANa), polyethylene oxide (PEO), polyethylene glycol, polyvinylpyrrolidone and copolymer thereof, alginate, chitosan, starch, dextran and glucan, and gelatin.

[0038] The above redox mediator may include a complex ion having a ring-shaped connection structure in which one ligand forms a coordinate bond with a metal ion at two or more sites.

[0039] The ligand of the above redox mediator may include one or more organic acids among ethylene diamine, ethylene diamine tetraacetic acid (EDTA), iminodiacetic acid, and phthalocyanine.

[0040] The above hydroxide salt may include one or more of sodium hydroxide (NaOH), potassium hydroxide (KOH), lithium hydroxide (LiOH), and ammonium hydroxide (NH4OH).

[0042] A method for preparing a polymer gel electrolyte for a metal-air battery according to the present invention is characterized by comprising: (a) a step of preparing an aqueous polymer electrolyte solution by adding a polymer having hydrophilic groups, a redox mediator, and a hydroxide salt to a solvent; and (b) a step of gelling the aqueous polymer electrolyte solution by crosslinking it.

[0043] In step (a) above, 1 to 100 parts by weight of an oxidation-reduction medium can be mixed with 100 parts by weight of a polymer having hydrophilic groups.

[0044] In step (a) above, the concentration of the hydroxide salt in the solvent may be 0.1 to 6 M.

[0046] A metal-air battery according to the present invention comprises an anode containing a metal; a cathode having oxygen as an active material; and a polymer gel electrolyte interposed between the anode and the cathode; wherein the polymer gel electrolyte comprises a polymer having hydrophilic groups, a redox medium, and a hydroxide salt, and wherein the polymer gel electrolyte has a gel form.

[0047] The above redox mediator may include a complex ion having a ring-shaped connection structure in which one ligand forms a coordinate bond with a metal ion at two or more sites.

[0048] The above cathode may include one or more of zinc, lithium, magnesium, and aluminum. Effects of the invention

[0050] The polymer gel electrolyte for a metal-air battery according to the present invention comprises a polymer having hydrophilic groups, a redox medium, and a hydroxide salt, thereby allowing physical properties to be maintained without change in performance even while the shape is deformed.

[0051] In addition, the metal-air battery of the present invention can be autonomously charged by facilitating reversible oxygen reduction and oxygen evolution reactions through a redox medium, and can exhibit excellent stability of the metal-air battery during long-term charge-discharge cycles.

[0052] In addition, the polymer gel electrolyte of the present invention has a simple manufacturing process and has the effect of enabling the metal-air battery to be used more than 500 times by replacing the negative electrode.

[0053] In addition, the polymer gel electrolyte of the present invention has excellent portability and flexibility, and a metal-air battery using it can directly generate electricity.

[0055] In addition to the effects described above, the specific effects of the present invention are described together with the specific details for implementing the invention below. Brief explanation of the drawing

[0057] Figure 1 is a process diagram showing a method for manufacturing a metal-air battery according to the present invention. Figure 2 shows the mechanism of a metal-air battery according to the present invention. Figure 3 shows the flexibility of a metal-air battery according to the present invention. Figure 4 compares the charge / discharge cycle results (A) to (C) of a metal-air battery according to the present invention when oxygen is supplied from the outside and when oxygen is cut off from the outside. FIG. 5 shows the voltage and capacity, charge / discharge cycle characteristics, and charge / discharge cycle characteristics (A) to (D) under deformation conditions of a metal-air battery according to the present invention. Figure 6 shows actual photos of a metal-air battery according to the present invention operating under various deformation conditions and the operating voltages at each condition (A) to (E). Specific details for implementing the invention

[0058] The aforementioned objectives, features, and advantages are described in detail below with reference to the attached drawings, thereby enabling those skilled in the art to easily implement the technical concept of the present invention. In describing the present invention, detailed descriptions of known technologies related to the present invention are omitted if it is determined that such descriptions would unnecessarily obscure the essence of the invention. Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the attached drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

[0059] In the following, the statement that any configuration is placed on the "upper (or lower)" of a component or on the "upper (or lower)" of a component may mean not only that any configuration is placed in contact with the upper (or lower) surface of said component, but also that another configuration may be interposed between said component and any configuration placed on (or below) said component.

[0060] In addition, where it is stated that one component is "connected," "combined," or "connected" to another component, it should be understood that while the components may be directly connected or connected to each other, another component may be "interposed" between each component, or each component may be "connected," "combined," or "connected" through another component.

[0061] Hereinafter, a polymer gel electrolyte for a metal-air battery according to an embodiment of the present invention, a method for manufacturing the same, and a metal-air battery using the same will be described.

[0063] In the present invention, a metal-air battery refers to a secondary battery that generates electricity by combining a metal such as zinc, lithium, magnesium, aluminum, etc. with oxygen in the air.

[0064] Such metal-air batteries include a negative electrode containing metal, a positive electrode using oxygen as an active material, and a polymer gel electrolyte interposed between the negative electrode and the positive electrode.

[0066] First, we will describe a polymer gel electrolyte that can be applied to the metal-air battery and a method for manufacturing the same.

[0067] The term "air" as used herein is not limited to atmospheric air and may include a combination of gases containing oxygen or pure oxygen gas.

[0069] Polymer gel electrolyte for metal-air batteries

[0070] The polymer gel electrolyte for a metal-air battery according to the present invention is characterized by comprising a polymer having hydrophilic groups, a redox medium, and a hydroxide salt.

[0071] The polymer gel electrolyte for metal-air batteries is a space where electrochemical reactions of the electrodes take place and ions are exchanged.

[0072] The above polymer gel electrolyte not only acts as an ion conductor for the movement of metal cations and hydroxide anions between the anode and the cathode, but also acts as a separator to block mechanical contact between the cathode and the anode.

[0074] The "gel" of the present invention is a solid or semi-solid state that has some elasticity and firmness.

[0075] The polymer gel electrolyte of the present invention is formed by polymer chains becoming thicker than a certain concentration through a cross-linking reaction, forming a network structure or mesh structure, and solidifying, and an alkaline solution such as a hydroxide salt penetrates into the spaces of the network structure or mesh structure and swells.

[0076] This gel-type electrolyte has excellent adhesion to the electrode, contributing to the stabilization of the electrolyte-electrode interface, as well as excellent mechanical and electrochemical properties.

[0077] When applied to flexible batteries such as metal-air batteries, stable battery performance can be achieved even under deformation caused by various external forces, and risks such as battery ignition and explosion caused by battery deformation can be suppressed.

[0079] Polymers having hydrophilic groups are cross-linked polymers and may include synthetic polymers and derivatives thereof.

[0080] For example, polymers having hydrophilic groups may include one or more of polyvinyl alcohol (PVA), polyacrylamide (PAM), polyacrylic acid (PAA), sodium polyacrylate (PANa), polyethylene oxide (PEO), polyethylene glycol, polyvinylpyrrolidone, and copolymers thereof.

[0081] Preferably, the synthetic polymer having hydrophilic groups may include polyvinyl alcohol (PVA).

[0082] In addition, polymers having hydrophilic groups may include natural polymers and derivatives thereof.

[0083] For example, polymers having hydrophilic groups may include one or more of alginate, chitosan, starch, dextran, glucan, and gelatin.

[0085] Polymers having hydrophilic groups can be dissolved in a solvent containing water and then prepared into a gel-type electrolyte through physical crosslinking or chemical crosslinking.

[0086] Solvents for dissolving polymers having hydrophilic groups may include deionized water, distilled water, water, etc.

[0087] The mixed solvent may include a mixture of glycerol or / and ethylene glycol with one or more of deionized water, distilled water, and water.

[0088] For example, the mixed solvent may include deionized water : glycerol or / and ethylene glycol mixed in a weight ratio of 1 : 1 to 2.

[0089] Polymers having hydrophilic groups can be prepared in the form of a hydrogel by using a freezing-thawing cycle process for physical crosslinking reactions after being dissolved in a solvent. The freezing-thawing cycle process can be performed by repeating a cycle of freezing at 0°C or below for 5 to 20 hours and then thawing at room temperature about 3 to 10 times.

[0090] In addition, polymers having hydrophilic groups can be crosslinked by adding a crosslinking agent to an aqueous polymer electrolyte solution for a chemical crosslinking reaction.

[0091] As a crosslinking agent for a chemical crosslinking reaction, one or more of glutaraldehyde, 4-carboxybenzaldehyde, and 2,3-dialdehyde cellulose may be included.

[0093] The redox mediator may include a complex ion as a chelate.

[0094] Specifically, the redox mediator may be a complex ion having a ring-shaped linkage structure in which a single ligand acting as a chelating agent forms coordinate bonds with one or more metal ions among Ca, Cu, Co, Mn, Ni, and Fe at two or more sites.

[0095] As the chelating agent ligand forms a complex by coordinating with metal ions, the problem of significantly reducing the reactivity of conventional transition metal ions can be minimized.

[0096] In addition, it can suppress side reactions in which transition metal ions are reduced and precipitated as transition metals.

[0097] When transition metals precipitate, problems such as minute internal short circuits in the battery, resulting in voltage drop, reduced stability, and decreased performance occur.

[0098] However, in the present invention, the chelating agent ligand and the metal ion form a stable complex through coordination bonding, thereby minimizing these problems.

[0099] In the present invention, the redox mediator, which is coordinately bonded to an organic acid ligand acting as a chelating agent with a metal ion, may exist in a form dissolved and included in a polymer gel electrolyte.

[0100] Ligands, which act as chelating agents, are molecules or ions possessing non-covalent electron pairs that provide these pairs to metals and play a role in forming coordinate bonds.

[0101] In this regard, the ligand may include one or more of ethylenediamine, ethylenediaminetetraacetic acid (EDTA), iminodiacetic acid, and phthalocyanine.

[0102] Preferably, the redox medium may include NaFeEDTA (Ethyelendiaminetetraacetic acid iron(III) sodium salt).

[0104] Hydroxides can act as a buffer to maintain the concentration of hydroxide ions.

[0105] To this end, the hydroxide salt may include one or more of sodium hydroxide (NaOH), potassium hydroxide (KOH), lithium hydroxide (LiOH), and ammonium hydroxide (NH4OH).

[0106] The polymer gel electrolyte of the zinc-air battery system may include one or more of NaOH, KOH, LiOH, and NH4OH, and preferably may include KOH.

[0107] The concentration of the hydroxide salt can be controlled to the extent that the pH of the polymer gel electrolyte is 12 or higher, preferably to a basic condition of pH 12 to 13.

[0108] In this regard, the concentration of the hydroxide salt in the solvent can satisfy a concentration of 0.1 to 6 M, and preferably 4 to 6 M.

[0109] When the concentration of the hydroxide salt is less than 0.1M, the concentration of hydroxide ions inside the electrolyte is low, and an overpotential due to polarization may occur at the anode.

[0110] Conversely, if the concentration of hydroxide exceeds 6M, the high pH of the electrolyte causes zinc ions to acquire various oxidation states, forming various types of complexes. Consequently, reversible charging and discharging of metal-air batteries may become difficult.

[0111]

[0112] As such, the polymer gel electrolyte of the present invention is gelled from an organic acid ligand, which is a chelating agent, a redox mediator formed from metal ions, a hydrophilic polymer, and a hydroxide salt, thereby maintaining physical properties without change in performance even while the shape is deformed.

[0114] Typically, zinc-air batteries use atmospheric oxygen as an active material, so they can have a high energy density.

[0115] However, as mentioned above, a high overpotential is required to induce an oxygen reduction reaction at the anode during discharge or an oxygen evolution reaction during charging.

[0116] Therefore, conventional zinc-air batteries have low charge / discharge efficiency and are at a significant disadvantage, especially in high-power applications.

[0117] In contrast, the polymer gel electrolyte constituting the metal-air battery of the present invention has the characteristic of having a low overpotential from the reversible reduction reaction of the redox medium contained in the electrolyte, and thus high charge-discharge efficiency.

[0118] Also, as long as oxygen is continuously supplied from the outside, self-charging is possible.

[0119] Accordingly, metal-air batteries using polymer gel electrolytes can be charged autonomously and exhibit excellent stability during long-term charge-discharge cycles.

[0121] Method for manufacturing a polymer gel electrolyte for a metal-air battery

[0122] The method for preparing a polymer gel electrolyte for a metal-air battery according to the present invention is characterized by comprising the steps of: preparing an aqueous polymer electrolyte solution by adding a polymer having hydrophilic groups, an oxidation-reduction medium, and a hydroxide salt to a solvent, and then mixing and stirring; and gelling the aqueous polymer electrolyte solution by crosslinking.

[0124] In the step of preparing an aqueous polymer gel electrolyte solution, 1 to 100 parts by weight of a redox medium can be mixed with 100 parts by weight of a polymer having hydrophilic groups, preferably 10 to 50 parts by weight of a redox medium can be mixed, and more preferably 20 to 40 parts by weight can be mixed.

[0125] In an aqueous solution of a polymer gel electrolyte, satisfying the standard of 100 parts by weight of a polymer having hydrophilic groups has the effect of facilitating the gelation reaction of the electrolyte and the formation of a solid electrolyte.

[0126] By satisfying 1 to 100 parts by weight of the redox medium, the oxygen reduction reaction and oxygen evolution reaction occur efficiently at the anode, thereby having the effect of reducing the overpotential.

[0128] As described above, polymers having hydrophilic groups may include one or more of polyvinyl alcohol (PVA), polyacrylamide (PAM), polyacrylic acid (PAA), sodium polyacrylate (PANa), polyethylene oxide (PEO), polyethylene glycol, polyvinylpyrrolidone, alginate, chitosan, starch, dextran, glucan, and gelatin.

[0130] The redox mediator can be formed from a chelating agent ligand and preferably may include NaFeEDTA (Ethyelendiaminetetraacetic acid iron(III) sodium salt).

[0132] Hydroxide salts may include one or more of sodium hydroxide (NaOH), potassium hydroxide (KOH), lithium hydroxide (LiOH), and ammonium hydroxide (NH4OH).

[0133] The concentration of the hydroxide salt in the solvent can be 0.1 to 6 M.

[0135] Subsequently, a polymer gel electrolyte can be prepared by inducing a gelation reaction through a polymer crosslinking reaction of an aqueous polymer electrolyte solution containing a polymer having hydrophilic groups, a redox mediator, and a hydroxide salt.

[0136] That is, an aqueous solution of a polymer electrolyte can be gelled to produce a polymer gel electrolyte.

[0138] A gelation reaction can be induced through the physical cross-linking reaction of the polymer contained in the polymer electrolyte aqueous solution.

[0139] For example, a polymer gel electrolyte can be prepared by cooling an aqueous polymer electrolyte solution to a temperature of -5 to 5°C and maintaining it for 10 minutes to 2 hours.

[0140] Meanwhile, an aqueous polymer electrolyte solution can induce a gelation reaction through a chemical cross-linking reaction.

[0141] In this case, one or more crosslinking agents selected from glutaraldehyde, 4-carboxybenzaldehyde, and 2,3-dialdehyde cellulose can be added to induce a crosslinking reaction, thereby producing a polymer gel electrolyte.

[0143] metal-air battery

[0144] The polymer gel electrolyte produced according to the manufacturing method of the present invention can be applied to a flexible metal-air battery.

[0145] FIG. 1 is a process diagram showing a method for manufacturing a metal-air battery according to the present invention.

[0146] First, a rod-shaped zinc metal (10) is manufactured into a spiral shape as a cathode, and then the spiral zinc metal rod (10) is placed in a hollow cylinder-shaped template (20).

[0147] Afterwards, a polymer electrolyte solution (22) containing a polymer having hydrophilic groups, an oxidation-reduction medium, and a hydroxide salt, as in step A, is introduced into a mold (20) in which a spiral zinc metal rod (10) is located.

[0148] Afterwards, a polymer gel electrolyte (25) can be prepared by inducing a gelation reaction through a cross-linking reaction as in step B.

[0149] Afterwards, the mold (20) is removed, and a flexible metal-air battery can be manufactured by wrapping a carbon fiber cloth (Carbon cloth, 30) having pores on the surface of the polymer gel electrolyte as in step C.

[0150] Wrapping a carbon cloth involves covering part or all of the outer surface of a polymer gel electrolyte. The carbon cloth can act as a cathode, providing a pathway for electrons to move while allowing oxygen to flow between the carbon fibers and react with the electrolyte.

[0151] In addition, carbon fiber fabric is formed from carbon fibers, and pores are formed between the fibers, which can increase the surface area.

[0152] Carbon fiber fabric is also called carbon fabric or carbon cloth.

[0154] As illustrated in FIG. 2, the metal-air battery comprises a negative electrode (anode, 10) containing a metal, a positive electrode (cathode, 30) having oxygen as an active material, and a polymer gel electrolyte (25) interposed between the negative electrode and the positive electrode.

[0155] One side of the negative electrode (10) and one side of the positive electrode (30) are in contact with a polymer gel electrolyte (25).

[0156] The polymer gel electrolyte simultaneously serves as an ion conductor and a separator that separates the cathode and the anode.

[0157] In FIG. 2, the polymer gel electrolyte (25) is shown separated into two layers to illustrate the reaction mechanism, but it is not limited to this.

[0159] The cathode (10) can be used as a metal plate or alloy plate itself, or as a spiral cathode inserted into a polymer gel electrolyte.

[0160] The cathode may include one or more of zinc, lithium, magnesium, and aluminum.

[0162] The anode (30) is a plate-shaped electrode that is relatively thin compared to the cathode, and can be manufactured by adding an anode material to a binder solution and stirring to prepare a slurry, and then applying or attaching it to a polymer gel electrolyte.

[0163] A conductive material can be used as an anode with oxygen as the active material.

[0164] Conductive materials can be used without limitation as long as they have porosity and conductivity.

[0165] For example, for conductive materials, porous carbon-based materials can be used.

[0166] Such carbon-based materials may include carbon black, graphite, graphene, activated carbon, carbon fiber, etc., used alone or in combination.

[0168] Figure 2 shows the mechanism of a metal-air battery according to the present invention.

[0169] Metal-air batteries enable the generation of electricity through the following reactions.

[0171] [Chemical Formula 1]

[0172] (1) Fe(II)(EDTA) + O2→ Fe(III)(EDTA)O2

[0173] (2) Fe(III)(EDTA)O2 + H2O + e - → Fe(II)(EDTA)OOH + OH -

[0174] (3) Fe(II)(EDTA)OOH + H2O + 2e - → Fe(II)(EDTA)OH + 2OH -

[0175] (4) Fe(II)(EDTA)OH + e - → Fe(II)(EDTA) + OH -

[0177] Referring to Figure 2 and Chemical Formula 1, during discharge, oxygen from the air at the anode dissolves into the electrolyte through the anode and reacts with [Fe(II)(EDTA)], a redox medium contained in the polymer gel electrolyte, and oxidizes it to [Fe(III)(EDTA)].

[0178] Electrons generated by the oxidation of the cathode move to the anode and reduce the [Fe(III)(EDTA)] formed on the anode surface, thereby forming [Fe(II)(EDTA)].

[0179] As such, the oxygen reduction medium contained in the electrolyte acts as a catalyst to facilitate the oxygen reduction reaction during discharge, and plays a role in increasing charge-discharge efficiency by reducing overvoltage.

[0180] In addition, if the external circuit of the metal-air battery is cut off and a continuous oxygen supply is provided from the positive electrode, self-charging becomes possible, enabling repeated charging and discharging operations without a separate external power supply and achieving a stable discharge voltage even during long-term charge-discharge cycles.

[0182] As such, specific examples of the polymer gel electrolyte for metal-air batteries, the method for manufacturing the same, and the metal-air battery using the same are as follows.

[0184] The metal-air battery used in Figures 3 to 6 was manufactured in the following manner.

[0185] First, a rod-shaped zinc electrode was manufactured into a spiral shape as the cathode.

[0186] After placing a spiral-shaped zinc electrode in the center of a hollow circular cylinder template, an aqueous polymer electrolyte solution was placed in the template and maintained at 0°C for 1 hour to form a polymer gel electrolyte.

[0187] A polymer electrolyte aqueous solution was prepared by adding 6M KOH hydroxide salt to 1g of PVA as a polymer having hydrophilic groups, 0.3g of Na[Fe(EDTA)] as an oxidation-reduction medium, and 30g of a mixed solvent of deionized water and glycerol, and then mixing and stirring.

[0188] Subsequently, a flexible metal-air battery was constructed by wrapping a carbon fiber cloth as an anode on the outer surface of a polymer gel electrolyte.

[0190] Figure 3 shows the flexibility of a metal-air battery according to the present invention.

[0191] Figures 3(A) to (D) show the appearance when a rod-shaped zinc is used as a spiral cathode electrode and the outside of the zinc electrode is filled with a polymer gel electrolyte.

[0192] The manufactured metal-air battery is flexible, so it can be deformed into any shape.

[0193] Figures 3(E) to (J) show a metal-air battery manufactured by wrapping a positive electrode around the outside of a polymer gel electrolyte in which a negative electrode is placed, and it shows that it can be flexibly deformed under various deformation conditions.

[0195] Figures 4 and 5 show the characteristics of a metal-air battery according to the present invention.

[0196] Figure 4 compares the charge / discharge cycle results (A) to (C) of a metal-air battery according to the present invention when oxygen is supplied from the outside and when oxygen is cut off from the outside.

[0197] Figure 4(A) shows that repeated self-charging is possible under conditions where oxygen is supplied from the outside.

[0198] Figure 4(B) shows that under conditions where oxygen is cut off from the outside, self-charging does not occur and the voltage drops rapidly.

[0199] Figure 4(C) shows the difference in charging voltage depending on whether oxygen is supplied.

[0200] The voltage rose rapidly from the moment oxygen was supplied from the outside, and then remained above 1V after 200 seconds. On the other hand, under conditions where oxygen was cut off from the outside, the voltage was below 0.2V.

[0202] FIG. 5 shows the voltage and capacity, charge / discharge cycle characteristics, and charge / discharge cycle characteristics (A) to (D) under deformation conditions of a metal-air battery according to the present invention.

[0203] Fig. 5(A) is 1 mA / cm 2 It shows the discharge voltage curve and discharge capacity during discharge at a current density.

[0204] Due to the movement of electrons to the anode, a decrease in the anode's potential and an increase in the cathode's potential occur, resulting in a lower potential difference; at this time, it can be confirmed that the discharge capacity decreases.

[0205] Figure 5(B) shows the maximum output characteristics that can be implemented depending on the discharge current.

[0206] It showed a maximum output value in the 30 ~ 40mA range.

[0207] Referring to Fig. 5(C), 1 mA / cm 2 When discharged and charged at a current density, the charge / discharge efficiency and stability can be verified during 500 charge / discharge cycles.

[0208] Referring to Fig. 5(D), the stability of the charge-discharge cycle under various deformation conditions can be confirmed.

[0210] Figure 6 shows actual photos of a metal-air battery according to the present invention operating under various deformation conditions and the operating voltages at each condition (A) to (E).

[0211] In Fig. 6, it can be seen that the metal-air battery according to the present invention exhibits a stable driving voltage under various deformation conditions.

[0213] As such, the metal-air battery with the polymer gel electrolyte of the present invention has the effect of maintaining performance even when twisted or deformed, and has high portability and flexibility.

[0214] In addition, it is capable of self-charging, can automatically generate its own power from the reversible reduction reaction of a redox medium, directly generates electricity, and has renewable characteristics.

[0215] In addition, the required current and voltage can be obtained through parallel or series connections.

[0216] In addition, it has higher stability than conventional metal-air batteries and can maintain a lifespan of more than 500 cycles by replacing the negative electrode.

[0218] Although the present invention has been described above with reference to the illustrated drawings, the present invention is not limited by the embodiments and drawings disclosed in this specification, and it is obvious that various modifications can be made by a person skilled in the art within the scope of the technical concept of the present invention. Furthermore, even if the effects of the configuration of the present invention were not explicitly described while explaining the embodiments of the present invention above, it is natural to acknowledge that the effects predictable by said configuration should also be recognized. Explanation of the symbols

[0220] 10: Cathode, spiral zinc metal rod 20 : Mold 22: Polymer electrolyte aqueous solution 30: Anode, carbon fiber fabric 25: Polymer gel electrolyte

Claims

Claim 1 A polymer gel electrolyte for a metal-air battery having a gel form, comprising: a polymer having hydrophilic groups; a redox medium; and a hydroxide salt. Claim 2 A polymer gel electrolyte for a metal-air battery according to claim 1, wherein the polymer having a hydrophilic group comprises one or more of polyvinyl alcohol (PVA), polyacrylamide (PAAM), polyacrylic acid (PAA), sodium polyacrylate (PANa), polyethylene oxide (PEO), polyethylene glycol, polyvinylpyrrolidone and copolymer thereof, alginate, chitosan, starch, dextran and glucan, and gelatin. Claim 3 In claim 1, the redox medium is a polymer gel electrolyte for a metal-air battery comprising a complex ion having a ring-shaped linkage structure in which one ligand forms a coordinate bond with a metal ion at two or more sites. Claim 4 A polymer gel electrolyte for a metal-air battery according to claim 1, wherein the ligand of the redox mediator comprises one or more organic acids selected from ethylene diamine, ethylene diamine tetraacetic acid (EDTA), iminodiacetic acid, and phthalocyanine. Claim 5 A polymer gel electrolyte for a metal-air battery according to claim 1, wherein the hydroxide salt comprises one or more of sodium hydroxide (NaOH), potassium hydroxide (KOH), lithium hydroxide (LiOH), and ammonium hydroxide (NH4OH). Claim 6 (a) a step of preparing an aqueous polymer electrolyte solution by adding a polymer having hydrophilic groups, a redox mediator, and a hydroxide salt to a solvent; and (b) a step of gelling the aqueous polymer electrolyte solution by crosslinking; a method for preparing a polymer gel electrolyte for a metal-air battery. Claim 7 A method for preparing a polymer gel electrolyte for a metal-air battery according to claim 6, wherein in step (a) above, 1 to 100 parts by weight of a redox medium is mixed with 100 parts by weight of a polymer having hydrophilic groups. Claim 8 A method for preparing a polymer gel electrolyte for a metal-air battery according to claim 6, wherein in step (a) above, the concentration of the hydroxide salt in the solvent is 0.1 to 6 M. Claim 9 A metal-air battery comprising: an anode containing a metal; a cathode having oxygen as an active material; and a polymer gel electrolyte interposed between the anode and the cathode, wherein the polymer gel electrolyte comprises a polymer having hydrophilic groups, a redox medium, and a hydroxide salt, and the polymer gel electrolyte has a gel form. Claim 10 In claim 9, the redox medium is a metal-air battery comprising a complex ion having a ring-shaped linkage structure in which one ligand forms a coordinate bond with a metal ion at two or more sites. Claim 11 In claim 9, the negative electrode is a metal-air battery comprising one or more of zinc, lithium, magnesium, and aluminum.

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