KR20230114674A - Hydrogen-hydrogen peroxide fuel cell and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a fuel cell for producing electrical energy using hydrogen and hydrogen peroxide and a method for manufacturing the same. It has higher energy density and can store energy for a long time. In addition, if hydrogen and hydrogen peroxide are continuously supplied, electrical energy can be continuously produced, so it can be applied to emergency power sources (UPS, etc.), aerospace and military fields.

Description

Hydrogen-hydrogen peroxide fuel cell and manufacturing method thereof

The present invention relates to a fuel cell for producing electric energy using hydrogen and hydrogen peroxide and a manufacturing method thereof.

Recently, fuel cells are attracting attention as a clean energy conversion device with high efficiency and low emission of pollutants, and are widely used. However, high cost and limitations in technical reliability make commercialization difficult. In particular, since the oxygen reduction reaction of the oxygen electrode in a fuel cell occurs about 10 ⁶ times slower than the hydrogen oxidation reaction of the hydrogen electrode, the oxygen reduction activity of the oxygen electrode Reaction is not only a major factor determining the overall reaction rate, but also pointed out as a cause of deterioration of fuel cell performance.

On the other hand, hydrogen-hydrogen peroxide fuel cells can obtain higher energy thermodynamically than existing hydrogen-oxygen fuel cells. However, hydrogen peroxide is chemically unstable in most catalysts and decomposes into oxygen and water, making it difficult to efficiently obtain electrical energy.

In addition, conventional fuel cells use a large amount of noble metal catalysts in the cathode and anode, and in particular, have a disadvantage in that a large amount of noble metal catalyst is used in the anode. In order to reduce costs, research on reducing the platinum content is being conducted in the short term, but from a long-term perspective, it is essential to develop a non-noble metal catalyst. Over the past several decades, many efforts have been made to develop non-noble metal catalysts for fuel cells. Although there were no groundbreaking results, this has been a strong driving force for research on non-precious metal catalysts for commercialization of fuel cells. Recently, promising non-noble metal catalysts such as transition metal alloys and chalcogenides have been developed, but their reactivity is still low compared to platinum, so efforts are needed to improve them.

Republic of Korea Patent No. 10-0864024 (2008.10.16. Publication)

An object of the present invention is to provide a hydrogen-hydrogen peroxide fuel cell with excellent energy density and energy efficiency using hydrogen with high energy density and hydrogen peroxide, which is a strong oxidizing agent, and a manufacturing method thereof.

The present invention includes an oxidation electrode, an electrolyte membrane and a reduction electrode, the electrolyte membrane is provided between the oxidation electrode and the reduction electrode, the reduction electrode includes a vanadium liquid catalyst, and vanadium tetravalent cations included in the vanadium liquid catalyst A hydrogen-hydrogen peroxide fuel cell characterized in that vanadium 5 is oxidized to a cation by being oxidized by hydrogen peroxide is provided.

In addition, the present invention comprises the steps of manufacturing an anode (first step); manufacturing a cathode (second step); placing an electrolyte membrane on the prepared anode and pressurizing it to compress the anode (third step); and stacking the prepared reduction electrode so as to face the electrolyte membrane (fourth step), wherein the reduction electrode includes a vanadium liquid catalyst, and vanadium tetravalent cations included in the vanadium liquid catalyst are formed by hydrogen peroxide. It provides a method for manufacturing a hydrogen-hydrogen peroxide fuel cell, characterized in that vanadium 5 is oxidized to a cation.

The hydrogen-hydrogen peroxide fuel cell according to the present invention uses hydrogen with high energy density and hydrogen peroxide, which is a strong oxidizing agent, to have higher energy density than conventional fuel cells and can store energy for a long time. In addition, if hydrogen and hydrogen peroxide are continuously supplied, electrical energy can be continuously produced, so it can be applied to emergency power sources (UPS, etc.), aerospace and military fields.

1 is a diagram showing the operating principle of a hydrogen-hydrogen peroxide fuel cell according to an embodiment of the present invention.
2 is a photograph of an oxidation reaction of a vanadium liquid catalyst according to an embodiment of the present invention.
3 is a unit cell evaluation result of a hydrogen-hydrogen peroxide fuel cell according to an embodiment of the present invention.

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

The present invention includes an oxidation electrode, an electrolyte membrane and a reduction electrode, the electrolyte membrane is provided between the oxidation electrode and the reduction electrode, the reduction electrode includes a vanadium liquid catalyst, and vanadium tetravalent cations included in the vanadium liquid catalyst It is oxidized by the hydrogen peroxide to provide a hydrogen-hydrogen peroxide fuel cell characterized in that vanadium 5 is oxidized to a cation.

Specifically, the hydrogen-hydrogen peroxide fuel cell may include an oxidation electrode using an oxidation reaction of fuel, a reduction electrode using a reduction reaction of an oxidizing agent, and an electrolyte membrane positioned between the oxidation electrode and the reduction electrode. It is not.

The oxidation electrode may include a substrate and a catalyst layer.

The substrate may serve to support the electrode and diffuse the fuel into the catalyst layer to facilitate easy access of the fuel to the catalyst layer, and a conductive substrate may be used as the substrate. Specifically, the conductive substrate may be carbon paper, carbon cloth, carbon felt, or metal cloth, and the metal cloth is a porous film or polymer fiber composed of a fibrous metal cloth. A metal film may be formed on the surface of the fabric.

It is preferable to use a water-repellent material treated with a fluorine-based resin to prevent a reduction in the diffusion efficiency of reactants due to water generated during operation of the fuel cell. The fluorine-based resin includes polytetrafluoroethylene, Polyvinylidene fluoride, 　polyhexafluoropropylene, polyperfluoroalkylvinyl ether, polyperfluorosulfonylfluoride alkoxyvinyl ether, fluorinated ethylenepropylene, polychlorotrifluoroethylene and these It may be any one selected from the group consisting of copolymers of, but is not limited thereto.

The catalyst layer serves to help the oxidation reaction of fuel to proceed efficiently and may include a catalyst.

As long as the catalyst is generally used in the art, it is applicable without limitation, and specifically, a platinum-based catalyst may be used as the catalyst. The platinum-based catalyst includes platinum, ruthenium, osmium, platinum-ruthenium alloy, platinum-osmium alloy, platinum-palladium alloy, platinum-M alloy (M is gallium (Ga), titanium (Ti), vanadium (V), chromium (Cr), Manganese (Mn), Iron (Fe), Cobalt (Co), Nickel (Ni), Copper (Cu), Zinc (Zn), Tin (Sn), Molybdenum (Mo), Tungsten (W), Ruthenium A catalyst selected from the group consisting of (Ru), rhodium (Rh), and a transition metal selected from the group consisting of combinations thereof) and mixtures thereof may be used, but is not limited thereto.

An anode including the substrate and a catalyst layer may be prepared by, for example, applying a slurry containing a catalyst to a substrate, but is not limited thereto.

The cathode may include at least one selected from the group consisting of carbon paper, carbon cloth, and carbon felt, and unlike the anode, there is no need to use a noble metal catalyst. .

The vanadium liquid catalyst may be composed of a 0.3 to 1 M vanadyl sulfate (VOSO ₄ ) solution and a 1 to 3 M sulfuric acid (H ₂ SO ₄ ) solution, but is not limited thereto.

In the vanadium liquid catalyst, vanadium tetravalent cations may be oxidized with hydrogen peroxide to vanadium pentavalent cations, and the vanadium liquid catalyst may be vanadyl sulfate.

When the vanadyl sulfate is dissolved in a sulfuric acid solution and then reacted with hydrogen peroxide, a reaction shown in Scheme 3 below may occur.

The electrolyte membrane may be a cation exchange membrane or an anion exchange membrane, but is not limited thereto.

The cation exchange membrane is a fluorine-based polymer, a benzimidazole-based polymer, a polyimide-based polymer, a polyetherimide-based polymer, a polyphenylene sulfide-based polymer, a polysulfone-based polymer, a polyethersulfone-based polymer, a polyether ketone-based polymer, It may be any one selected from the group consisting of ether-ether ketone-based polymers and polyphenylquinoxaline-based polymers, but is not limited thereto.

The anion exchange membrane may be selected from electrolytes selected from fluorine-based polymers and hydrocarbon-based polymers having a functional group that exhibits a cation capable of easily transporting hydroxide ions, but is not limited thereto.

The electrolyte membrane serves as an insulator that electrically separates the anode and the cathode, and at the same time serves as a medium for transferring electrons and/or hydrogen ions from the anode to the cathode during operation of the hydrogen-hydrogen peroxide fuel cell. Since it can simultaneously perform the role of separating the electrolyte membrane, it is preferable that the electrolyte membrane is manufactured using a polymer having excellent hydrogen ion conductivity.

The electrolyte membrane may further include an electrical conductive layer to ensure sufficient electrical conductivity, but is not limited thereto.

The hydrogen-peroxide fuel cell of the present invention may further include an oxidation reactor for supplying a vanadium liquid catalyst to the reduction electrode, but is not limited thereto.

The oxidation reactor contains hydrogen peroxide, and hydrogen peroxide is a very strong oxidizing agent with a standard reduction potential of 1.76 V. When vanadium tetravalent cations reduced at the reduction electrode are supplied to the oxidation reactor, they are oxidized again by hydrogen peroxide and then supplied to the reduction electrode. . Through this reaction pathway, a high energy density fuel cell using hydrogen and hydrogen peroxide can be provided.

An oxidation reaction of fuel occurs at the oxidation electrode. The fuel may include gaseous or liquid hydrogen or hydrocarbon fuel commonly used in the art, and the hydrocarbon fuel may be methanol, ethanol, propanol, butanol, or natural gas.

The hydrogen-peroxide fuel cell may further include a fuel supply port to supply fuel to the anode.

At the reduction electrode, a reduction reaction of the vanadium liquid catalyst occurs. Specifically, electrical energy is generated as vanadium pentavalent cations are reduced to vanadium tetravalent cations.

The hydrogen-peroxide fuel cell of the present invention is a hydrogen-peroxide fuel cell with high energy density and energy efficiency by using inexpensive carbon materials without using a precious metal catalyst by using vanadium, which has low activation energy of oxidation/reduction reaction, as a redox pair. can provide.

The hydrogen-hydrogen peroxide fuel cell may further include a circulation catalyst supply port to supply a liquid circulation catalyst including a vanadium liquid catalyst to the reduction electrode, but is not limited thereto.

1 is a view showing the operating principle of a hydrogen-hydrogen peroxide fuel cell of the present invention, wherein the oxidizing electrode is formed in the same structure as a general fuel cell, uses a Pt/C catalyst, and has the same structure as a conventional fuel cell such as A hydrogen oxidation reaction occurs, and electrons and hydrogen ions generated at this time move to the reduction electrode through the conductive wire and the electrolyte membrane. In addition, at the cathode, water is generated along with the reduction reaction of vanadium pentavalent cations (VO ₂ ⁺ ) as shown in Reaction Formula 2 below, and electrical energy and thermal energy are generated. Vanadium tetravalent cations (VO ²⁺ ) generated in this reaction move to the oxidation reactor. In the oxidation reactor, vanadium 5 is oxidized to a cation (VO ₂ ⁺ ) again as shown in Scheme 3 below. Putting these reaction equations together, they can be summarized as oxidation and reduction reactions of hydrogen and hydrogen peroxide as shown in Reaction Formula 4 below. In this case, vanadium undergoes repeated oxidation and reduction reactions, and does not change before/after the reaction. Liquid that helps the reduction reaction of hydrogen peroxide will act as a catalyst.

[Scheme 1]

Oxidation electrode reaction: H ₂ → 2H ⁺ + 2e ^-

[Scheme 2]

Cathode Reaction: 2VO ₂ ⁺ + 4H ⁺ + 2e ^- → 2VO ²⁺ + 2H ₂ O

[Scheme 3]

Oxidation reactor: 2VO ²⁺ + H ₂ O ₂ → 2VO ₂ ⁺ + 2H ⁺

[Scheme 4]

Overall reaction: H ₂ +H ₂ O ₂ → 2H ₂ O + Electric energy

In addition, the present invention comprises the steps of manufacturing an anode (first step); manufacturing a cathode (second step); placing an electrolyte membrane on the prepared anode and pressurizing it to compress the anode (third step); and stacking the prepared reduction electrode so as to face the electrolyte membrane (fourth step), wherein the reduction electrode includes a vanadium liquid catalyst, and vanadium tetravalent cations included in the vanadium liquid catalyst are formed by hydrogen peroxide. It provides a method for manufacturing a hydrogen-hydrogen peroxide fuel cell, characterized in that vanadium 5 is oxidized to a cation.

The first step is a step of manufacturing an oxidation electrode by forming a catalyst layer on a substrate. Specifically, it may be prepared by applying a slurry containing a catalyst to a substrate, but is not limited thereto.

The substrate may serve to support the electrode and diffuse the fuel into the catalyst layer to facilitate easy access of the fuel to the catalyst layer, and a conductive substrate may be used as the substrate. Specifically, the conductive substrate may be carbon paper, carbon cloth, carbon felt, or metal cloth, and the metal cloth is a porous film or polymer fiber composed of a fibrous metal cloth. A metal film may be formed on the surface of the fabric.

It is preferable to use a water-repellent material treated with a fluorine-based resin to prevent a reduction in the diffusion efficiency of reactants due to water generated during operation of the fuel cell. The fluorine-based resin includes polytetrafluoroethylene, Polyvinylidene fluoride, 　polyhexafluoropropylene, polyperfluoroalkylvinyl ether, polyperfluorosulfonylfluoride alkoxyvinyl ether, fluorinated ethylenepropylene, polychlorotrifluoroethylene and these It may be any one selected from the group consisting of copolymers of, but is not limited thereto.

The catalyst layer serves to help the oxidation reaction of fuel to proceed efficiently and may include a catalyst.

As long as the catalyst is generally used in the art, it is applicable without limitation, and specifically, a platinum-based catalyst may be used as the catalyst. The platinum-based catalyst includes platinum, ruthenium, osmium, platinum-ruthenium alloy, platinum-osmium alloy, platinum-palladium alloy, platinum-M alloy (M is gallium (Ga), titanium (Ti), vanadium (V), chromium (Cr), Manganese (Mn), Iron (Fe), Cobalt (Co), Nickel (Ni), Copper (Cu), Zinc (Zn), Tin (Sn), Molybdenum (Mo), Tungsten (W), Ruthenium A catalyst selected from the group consisting of (Ru), rhodium (Rh), and a transition metal selected from the group consisting of combinations thereof) and mixtures thereof may be used, but is not limited thereto.

In the second step, the cathode may include at least one selected from the group consisting of carbon paper, carbon cloth, and carbon felt, and unlike the anode, a noble metal catalyst may be used. no need to use

The vanadium liquid catalyst may be composed of a 0.3 to 1 M vanadyl sulfate (VOSO ₄ ) solution and a 1 to 3 M sulfuric acid (H ₂ SO ₄ ) solution, but is not limited thereto.

The cathode may include a vanadium liquid catalyst, and vanadium tetravalent cations included in the vanadium liquid catalyst may be oxidized to vanadium pentavalent cations by being oxidized by hydrogen peroxide.

In the third step, the electrolyte membrane may be placed on one surface of the oxidation electrode and compressed by applying a pressure of 1.5 to 3 bar at a temperature of 100 to 150 ° C for 2 to 10 minutes.

The electrolyte membrane may be a cation exchange membrane or an anion exchange membrane, but is not limited thereto.

The cation exchange membrane is a fluorine-based polymer, a benzimidazole-based polymer, a polyimide-based polymer, a polyetherimide-based polymer, a polyphenylene sulfide-based polymer, a polysulfone-based polymer, a polyethersulfone-based polymer, a polyether ketone-based polymer, It may be any one selected from the group consisting of ether-ether ketone-based polymers and polyphenylquinoxaline-based polymers, but is not limited thereto.

The anion exchange membrane may be selected from electrolytes selected from fluorine-based polymers and hydrocarbon-based polymers having a functional group that exhibits a cation capable of easily transporting hydroxide ions, but is not limited thereto.

The electrolyte membrane serves as an insulator that electrically separates the anode and the cathode, and at the same time serves as a medium for transferring electrons and/or hydrogen ions from the anode to the cathode during operation of the hydrogen-hydrogen peroxide fuel cell. Since it can simultaneously perform the role of separating the electrolyte membrane, it is preferable that the electrolyte membrane is manufactured using a polymer having excellent hydrogen ion conductivity.

The electrolyte membrane may further include an electrical conductive layer to ensure sufficient electrical conductivity, but is not limited thereto.

The electrolyte membrane may have a thickness of 10 to 100 μm or 30 to 70 μm.

Hereinafter, the present invention will be described through the following examples, but the following examples are only illustrated to help understanding of the present invention, but the scope of the present invention is not limited.

Example 1

The membrane-electrode assembly of the hydrogen-peroxide unit cell of the present invention is largely composed of an anode (oxidation electrode), a cathode (reduction electrode), and an electrolyte membrane. First, Pt/C (40%) GDE (Gas Diffusion Electrode, SGL-39BB) with 40% platinum supported on the anode is used as an electrode that oxidizes hydrogen, which is a fuel. The size was used by cutting into a square with a size of 5 cm x 5 cm. As the electrolyte membrane, Nafion 212 having a thickness of 50 μm was used. At this time, the size of the electrolyte membrane was cut into a size of 8 cm x 8 cm for easy fixation by attaching to the unit cell. The prepared anode electrode and the Nafion 212 electrolyte membrane were attached through a hot-pressing method, and were bonded by applying a pressure of 2 bar at a temperature of 110 ° C. for about 5 minutes.

Carbon felt was used as a cathode electrode material for reducing vanadium 5 cations, and at this time, the size was cut into a square of 5 cm x 5 cm in the same size as the anode GDE. A unit cell was assembled by placing a carbon felt electrode on the completed half anode electrode-electrolyte membrane assembly. In order to use the carbon felt electrode, a cell guide used for liquid solution injection was used, and at this time, a 140 μm gasket was used for the anode and cathode, respectively, to complete the unit cell.

Experimental Example 1

In order to confirm the energy density of the hydrogen-peroxide fuel cell of the present invention, the theoretical energy density that can be obtained when using hydrogen and various oxidants was calculated, and the results are shown in Table 1.

Referring to Table 1, the energy density is determined by the difference between the oxidation number, formula weight (or equivalent), concentration, and standard reduction potential of hydrogen and an oxidizing agent. Among various oxidizing agents, hydrogen peroxide can exist in a state with a purity as high as 35%, and an energy density of up to 731 mWh/g can be obtained because the equivalent weight is as low as 17 g/mol _e ^- . The energy density of existing lithium-ion batteries is 200 mWh/g, which is higher than conventional batteries and can store energy for a long time. In addition, if hydrogen and hydrogen peroxide are continuously supplied, electrical energy can be continuously produced. These hydrogen-hydrogen peroxide fuel cells can be applied to emergency power sources, aerospace and military fields.

Experimental Example 2

The activity of the vanadium catalyst used in the present invention and the performance of the unit cell using hydrogen and hydrogen peroxide according to the present invention were evaluated, and the results are shown in FIGS. 2 and 3 .

2 is a photograph of a solution obtained by dissolving vanadium +4-valent VOSO ₄ at a concentration of 0.5 M in a 2M sulfuric acid solution (left blue solution) and then oxidizing the ions using hydrogen peroxide to +5-valent VO ₂ (SO ₄ ) ₂ . am. It was confirmed that when hydrogen peroxide was added to a +4-valent vanadium solution, vanadium +4-valent ions were oxidized to +5-valent ions in a matter of seconds due to the strong oxidizing power of hydrogen peroxide.

The performance of the unit cell was evaluated using the oxidized vanadium +5 valent solution and hydrogen.

3 is a result of evaluating the performance of a unit cell using a vanadium +5 valent ion solution oxidized using hydrogen and hydrogen peroxide. As an anode, a gas diffusion electrode (GDE) with an area of 25 cm ² was used. For GDE, a Pt/C catalyst with a loading of 0.4 mg/cm ² based on platinum and coated on carbon paper (SGL-39BB) was used. The GDE described above was hot-pressed on a Nafion 212 electrolyte membrane at 110 ° C. for 5 minutes, and commercially available carbon fibers were assembled and used as a cathode without hot pressing.

High-purity hydrogen gas was supplied to the anode at a flow rate of 500 ml/min, and an aqueous vanadium solution oxidized with hydrogen peroxide was supplied to the cathode at a flow rate of 200 ml/min. After heating the temperature of the electrolyte and the unit cell to 50 ℃, the performance was evaluated using a fuel cell evaluation device.

As a result of evaluating the hydrogen-hydrogen peroxide fuel cell, the OCV (Open Circuit Volatage) was measured to be about 1.05 V, which is about 0.1 V higher than that of the existing hydrogen-oxygen fuel cell, and the activation loss was observed to be very low. This resulted in 0.54A/cm ² and 432 mW/cm ² at a unit cell voltage of 0.8V. This power density is higher than that of conventional hydrogen-oxygen fuel cells, and it is a system with very high commercialization potential.

As described above, although the present invention has been described by limited examples, the present invention is not limited thereto, and the technical spirit of the present invention and the claims to be described below are made by those skilled in the art to which the present invention belongs. Of course, various modifications and variations are possible within the equivalent range of the scope.

Claims (8)

Including an anode, an electrolyte membrane and a cathode,
The electrolyte membrane is provided between the anode and the cathode,
The reduction electrode includes a vanadium liquid catalyst,
A hydrogen-peroxide fuel cell, characterized in that vanadium tetravalent cations included in the vanadium liquid catalyst are oxidized by hydrogen peroxide to oxidized vanadium 5valent cations. According to claim 1,
The hydrogen-peroxide fuel cell, characterized in that the vanadium liquid catalyst consists of a 0.3 to 1 M vanadyl sulfate (VOSO ₄ ) solution and a 1 to 3 M sulfuric acid (H ₂ SO ₄ ) solution. According to claim 1,
The electrolyte membrane is a hydrogen-hydrogen peroxide fuel cell comprising a cation exchange membrane or an anion exchange membrane. According to claim 1,
The hydrogen-hydrogen peroxide fuel cell further comprises an oxidation reactor for supplying a vanadium liquid catalyst to a reduction electrode. According to claim 1,
The hydrogen-hydrogen peroxide fuel cell, characterized in that the energy density of the hydrogen-peroxide fuel cell is 600 to 800 Wh / kg. manufacturing an anode (first step);
manufacturing a cathode (second step);
placing an electrolyte membrane on the prepared anode and pressurizing it to compress the anode (third step); and
A step (fourth step) of stacking the prepared reduction electrode so as to face the electrolyte membrane,
The reduction electrode includes a vanadium liquid catalyst,
A method of manufacturing a hydrogen-peroxide fuel cell, characterized in that vanadium tetravalent cations included in the vanadium liquid catalyst are oxidized by hydrogen peroxide to oxidize to vanadium 5 valent cations. According to claim 6,
The vanadium liquid catalyst is a method for producing a hydrogen-peroxide fuel cell, characterized in that consisting of a 0.3 to 1 M vanadyl sulfate (VOSO ₄ ) solution and a 1 to 3 M sulfuric acid (H ₂ SO ₄ ) solution. According to claim 6,
The electrolyte membrane is a method of manufacturing a hydrogen-hydrogen peroxide fuel cell comprising a cation exchange membrane or an anion exchange membrane.