Hydrogen peroxide fuel cell

Abstract

To provide a fuel cell having an avalanche amplification function.SOLUTION: A fuel cell in which a water-soluble electrolytic solution contains hydrogen peroxide with high dipole efficiency, has a micro capacitor that forms a configuration where a dipole electric double-layer is provided between a cathode electrode formed of metal copper or its alloy and an anode electrode formed of a metal or its alloy and having such an electrode potential difference that the electrode potential of the anode electrode is lower than that of the cathode electrode, and electrons flow from the cathode electrode to the anode electrode by a tunnel phenomenon. The fuel cell causes a current amplification phenomenon similar to avalanche amplification.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] This invention In a hydrogen peroxide fuel cell that uses hydrogen peroxide as fuel (oxidizer), Electron avalanche flow from the cathode electrode to the anode electrode surface pseudo Regarding batteries with amplification capabilities. [Background technology]

[0002] Avalanche amplification is a phenomenon in which, when light enters the light-receiving part of a semiconductor with a strong electric field, electrons generated by photon collisions with semiconductor atoms are accelerated, collide with other semiconductor atoms, and evoke multiple more electrons. This avalanche-like chain reaction causes an explosive increase in the number of moving electrons. This effect causes a large change in current. This phenomenon is unique to semiconductors and insulators, but it is also an avalanche amplification phenomenon that occurs when a p-type semiconductor and an n-type semiconductor are facing each other with a depletion layer in between, and electrons flow into that depletion layer. Therefore, in an electrolyte containing a compound that forms a dipole, such as hydrogen peroxide, if a pair of battery electrodes are brought close together to form a dipole electric double layer between the electrodes, a separatorless battery with power generation function is formed without short circuits (Patent Document 1). However, if the configuration is such that the cathode electrode side contacts the anode electrode side locally via a dipole, a microcapacitor (Note: In this specification, a certain amount of charge is accumulated in the capacitor formed by the dipole layer interposed between the cathode and anode electrodes facing each other at a nanoscale interval of at least one dipole) is formed. discharge A capacitor is formed in which electrons flow out due to the phenomenon, resulting in a phenomenon similar to avalanche amplification in a photodiode. (Avalanche pseudo-amplification phenomenon) It is thought that the following occurs. That is, when one or more microcapacitors are formed between a pair of battery electrodes via a dipole, electrons flow into this microcapacitor from the surrounding cathode electrode and store energy. If the cathode electrode approaches the anode electrode via a triangular projection electrode from this cathode region, discharge As a result of this phenomenon, electrons begin to flow to a localized area of ​​the anode electrode, and when they collide with other atoms on the electrode and are evoked, the avalanche pseudoIt is thought that amplification occurs. In recent years, hydrogen peroxide fuel cells, unlike hydrogen fuel cells, have been expected to be a promising energy conversion platform because their one-compartment structure using an aqueous solution makes fuel supply easy and allows operation without a membrane separating the cathode and anode chambers. Therefore, the present invention relates to a fuel cell using hydrogen peroxide, and avalanche pseudo We conducted extensive research to provide a structure that can increase electromotive force by employing an amplification effect.

[0003] However, since hydrogen peroxide is a high-energy-density liquid that functions as both a fuel and an oxidizer, most metal electrodes catalyze the disproportionation reaction of H2O2 to H2O and O2. As a result, it exhibits a significant loss mechanism in peroxide fuel cells, and it was previously thought that hydrogen peroxide fuel cells using metal as the cathode electrode could not exist. Therefore, a hydrogen peroxide fuel cell has been published that uses poly(3,4-ethylenedioxythiophene (PEDOT)), a conductive polymer, as the cathode electrode, while using nickel mesh as the anode electrode, in order to avoid losses due to the disproportionation reaction, and exhibits an open-circuit potential in the range of 0.5 to 0.6 V with a power density of 0.20 to 0.30 mW cm (Non-Patent Literature 1). On the other hand, a hydrogen peroxide fuel cell using copper hexacyanoferrate (CuHCF) as the cathode material and Ni grid as the anode material has also been published (Non-Patent Literature 2). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent application No. 2021-073490 [Non-patent literature]

[0005] [Non-Patent Document 1] Chemical Communications,2018, Vol.54, Pages 11873-11876 [Non-Patent Document 2] Journal of Hydrogen Energy, ELSEVIER, Vol.45, Issue 47, 25 September 2020, Pages 25708-25718 [Non-Patent Document 3] Eiji Mizuto: Progress in Physical Chemistry (1936), 10(3): pp. 154-165 [Overview of the project] [Problems that the invention aims to solve]

[0006] In the case of fuel cells, there is also the problem that the electromotive force is low, around 1V, compared to metal-air batteries, and avalanche pseudo While the introduction of amplification functions is desirable, conventional hydrogen peroxide fuel cell cathode electrodes such as poly(3,4-ethylenedioxythiophene (PEDOT) and copper hexacyanoferrate (CuHCF) have avalanches. pseudo It is difficult to incorporate amplification functionality.

[0007] The inventors have found that copper or its alloys are effective as cathode electrodes for hydrogen peroxide fuel cells. Therefore, utilizing the fact that the cathode electrode is made of copper or its alloy, they have conducted intensive research and found that in a hydrogen peroxide fuel cell, when an electrode portion protruding from the cathode electrode surface is formed and brought into close proximity to the anode electrode via a dipole, electricity is stored in the dipole electric double layer from the surrounding cathode electrode. However, when the cathode electrode is extremely close to the anode electrode, discharge We discovered that when electrons begin to flow locally to the anode electrode due to this phenomenon, and collide with other atoms on the anode electrode, causing excitation, the generation of electrons increases exponentially, and the amount of electricity generated increases. This invention utilizes this to create an avalanche pseudo The objective is to provide a fuel cell with amplification capabilities. [Means for solving the problem]

[0008] The inventor has a method for increasing the power generation of fuel cells using an avalanche. pseudoIt provides a battery that is increased by an amplification function, and includes a water-soluble electrolyte containing a compound with a high dipole efficiency that forms a dipole electric double layer on the electrode surface, a cathode electrode made of a transition metal composed of copper, titanium, and iron, and an anode electrode made of magnesium, aluminum, zinc, or an alloy thereof, which is a metal inferior to the cathode electrode. The cathode electrode has a plurality of spacers protruding from its electrode surface toward the counter electrode surface of the anode electrode, and the tip of the spacer and the anode electrode surface face each other at an interval in which at least one dipole is interposed therebetween, sandwiching the dipole electric double layer to form a microcapacitor. It stores electrons from the cathode until a predetermined charge accumulates. discharge It is characterized in that it flows concentratedly to the anode local area by the effect, avalanche pseudo It is in a battery having an amplification function.

Advantages of the Invention

[0009] According to the present invention, a microcapacitor (FIG. 2) composed of a dipole electric double layer is provided between the cathode electrode and the anode electrode constituting the battery (FIG. 1). Therefore, once a charge of a predetermined amount or more is stored, electrons flow from the microcapacitor to the anode electrode discharge due to the effect, and these electrons collide with the atoms around the anode electrode, further arousing a plurality of electrons. Through this chain reaction like an avalanche, the number of mobile electrons increases explosively. (In aqueous battery systems, oxidation-reduction reactions are primarily driven by ion conduction, and electron conduction does not usually occur.) . The plurality of electrode protrusions form a plurality of microcapacitors between the anode electrode, collect electricity, and when a certain charge accumulates, discharge They are scattered to form microcapacitors that repeat discharging due to the phenomenon, and a conceptual diagram of an equivalent circuit configuration is shown as in FIG. 4, causing the electromotive force change shown in FIG. 5. A microcapacitor is preferably a dipole electric double layer formed of at least one dipole, for example, a molecule having a dipole efficiency such as a hydrogen peroxide molecule, sandwiched between the tip of the acute triangular protrusion electrode protruding from the cathode electrode surface and the anode electrode surface. Referring to the dipole efficiency of hydrogen peroxide, a compound having a dipole efficiency of 2.0 e.s.u.×10 -15 or more is preferred (Non-Patent Document 3).

Brief Description of the Drawings

[0010] [Figure 1] It is a conceptual diagram of a microcapacitor section that exhibits the avalanche-like amplification function of the present invention. [Figure 2] It is a conceptual diagram of a fuel cell to which the avalanche-like amplification function of the present invention is applied. [Figure 3] (A) of the configuration of the copper electrode constituting the fuel cell having the avalanche-like amplification function of the present invention is a perspective view, and (B) is an end view of the combined state of the magnesium electrode and the copper electrode. [Figure 4] It is a conceptual diagram of a battery in which a large number of microcapacitors are formed. [Figure 5] It is a graph showing the power generation state when the microcapacitor of the present invention is applied to a magnesium-air battery. [Figure 6] (A) of the configuration of the copper electrode of the battery forming a normal electric double layer capacitor is a perspective view, and (B) is a cross-sectional view of the combined state of the magnesium electrode and the copper electrode.

Embodiments for Carrying Out the Invention

[0011] The present invention increases the power generation amount of a fuel cell by an avalanche pseudo amplification function. Since the present invention achieves an avalanche pseudo amplification effect with a dipole electric double layer, it includes an aqueous electrolyte containing a compound with a high dipole efficiency that forms a dipole electric double layer on the electrode surface. Typical compounds for forming a dipole double layer are various electrolytes and aqueous hydrogen peroxide solutions. However, in terms of their dipole efficiency, 2.0 e.s.u.×10 -15Compounds having the above dipole moment, hydrogen peroxide is preferred (Non-Patent Literature 3). As the cathode electrode, not only copper or its alloys, but also transition metals and their alloys consisting of titanium and iron are effective. As the anode electrode, an anode electrode made of magnesium, aluminum, zinc, or an alloy thereof, which is a metal less noble than the cathode electrode, is preferred. The cathode electrode has a plurality of spacers that protrude from its electrode surface toward the counter electrode surface of the anode electrode, and the tips of these spacers and the anode electrode surface face each other at a distance between which at least one dipole is interposed, sandwiching a dipole electric double layer to form a microcapacitor. As a result, electrons from the cathode are stored and stored until a predetermined charge is accumulated. discharge The avalanche is characterized by its effect of concentrating flow to the anode. pseudo It has an amplification function. In this invention, as shown in Figure 2, a Mg anode electrode plate and a Cu cathode electrode plate are immersed in an alkaline electrolyte containing hydrogen peroxide and arranged facing each other. Then, as shown in Figure 3(A), a part of the copper electrode 10 is cut out in a triangular shape and raised perpendicular to the electrode surface to form an acute-angled triangular projection electrode 11 with a height of 5 to 15 mm, and its tip is positioned opposite the magnesium electrode surface so as to softly contact it. A spacing that allows at least one dipole molecule to be interposed is preferable. The projection electrodes are formed at intervals of 150 mm to 200 mm, and it is preferable that electrons flow in from the surrounding cathode electrode region.

[0012] The electromotive force in this invention is the electromotive force in a configuration of anode electrode / alkaline electrolyte containing hydrogen peroxide / cathode electrode, and the reaction of the metal-air cell is as follows. Oxidation reaction on the anode side: 2Mg → 2Mg 2+ + 4e - and, On the other hand, the reduction reaction on the cathode side is O2 + H2O + 4e - →4OH - This is the result. In this invention, hydrogen peroxide is added to the electrolyte to promote the reduction reaction on the cathode side of a metal-air battery, thereby improving the reason why the ionization rate of the cathode side positive electrode is inferior to that of the anode side negative electrode. In other words, metallic copper is converted to copper by Cu + H2O2 → Cu2+ +OH + OH - And Cu + OH → Cu 2+ + OH - dissolves partially in hydrogen peroxide, but Cu 2+ + 2HO2 - → Cu + 2HO2, and it is considered that the HO2 group promotes the decomposition of hydrogen peroxide by the Haber u. Willstatter chain (Non-Patent Document 3).

[0013] Moreover, according to the present invention, the electric double layer formed on the surface of the cathode electrode contains hydrogen peroxide and is formed by its dipole function. Therefore, the anode electrode of the counter electrode does not short-circuit even when it comes into contact with the cathode electrode. If the contact between the opposing anode electrode and the cathode electrode is formed by protrusions or the like arranged pointwise at a certain interval, an electric double layer capacitor structure will be formed at the tip of the point-like protrusion (Fig. 1), and it will exist at multiple points on the electrode surface as a microcapacitor (Fig. 3). The battery electromotive force is collected and then discharge flows due to the effect, and avalanche pseudo amplification is repeated (Fig. 5). Therefore, compared with the case of the same electrode configuration without a macro capacitor function, it will exhibit a power generation ability more than twice as high.

[0014] In the present invention, it is preferable to supply a part or all of hydrogen peroxide to the water-soluble electrolyte with sodium percarbonate. Specifically, it is preferable to add several percent to a dozen percent of hydrogen peroxide solution (volume%) or sodium percarbonate (weight%) to a neutral or alkaline aqueous solution containing 0.5 to 2.0 mol of an alkali metal or alkaline earth metal halide, particularly sodium chloride.

[0015] The anode electrode is made of magnesium or an alloy thereof, By taking a battery configuration of (-)Mg / NaCl + H2O2 / Cu(+), a decomposition voltage necessary to decompose hydrogen peroxide or the hydroxyl radical obtained by its decomposition is applied between the copper cathode electrode. As the magnesium alloy electrode, a magnesium / aluminum / zinc alloy electrode of MAZ61 or MAZ31 can be used.

[0016] The anode electrode and cathode electrode are alternately arranged opposite each other with a spacer in between at a constant distance, and an electric double-layer capacitor is formed at the contact area between the anode electrode and the cathode electrode using a water-soluble electrolyte containing hydrogen peroxide. Preferably, the spacer is made of the same metallic copper or copper alloy as the cathode electrode and has point-like protrusions spaced at a constant distance on the counter electrode surface (Figure 2). The microcapacitor is 2.0esu × 10⁻¹⁴ -15 A dipole having the above dipole moment can be constructed by facing a cathode electrode and an anode electrode with a distance of the order of nanometers, such as the distance between a single molecule of hydrogen peroxide. A triangular electrode is projected from the cathode electrode surface so that a tunnel current concentrates from the cathode electrode to the anode electrode. When multiple cathode electrodes are facing each other, it is best to change the number and position of the protruding electrodes of each cathode electrode to change the location where they approach the anode electrode. The anode electrode dissolves due to collisions with electrons from the cathode electrode, and these electrons collide with surrounding atoms in a chain reaction, stimulating electron generation. As a result, large through-holes (2.0 mm to 5.00 mm) are formed in the areas where the protrusions of the cathode electrode are close, and numerous small through-holes (0.5 mm to 1.0 mm) are formed throughout the electrode, creating a spongy structure. (This phenomenon is not observed in typical ion conduction-mediated redox reactions.) . [Examples]

[0017] A battery with multiple microcapacitors, as shown in Figure 4, was constructed using the copper electrodes shown in Figure 3. A top-opening rectangular plastic container with a capacity of 3000 ml was used. In Figure 3, a copper cathode electrode plate 10 with a thickness of 1 mm and dimensions of 100 x 100 mm has numerous triangular protrusions 11 with a height of 50 mm cut out at intervals of 150 mm to 200 mm on all sides (Figure 3A). As shown in Figure 3B, the copper electrodes 10 are joined together at both ends with the protrusions 11 facing inward, and the middle is back-to-back with the copper electrodes 10 sandwiching a magnesium anode electrode plate 20 with a thickness of 2 mm and dimensions of 100 x 100 mm. Using this combined electrode, a microcapacitor can be formed on the surface of the copper cathode electrode, as shown in Figure 1. On the other hand, as shown in Figure 6A, a spacer S is attached to a copper cathode electrode plate 10 that is 1 mm thick and measures 100 x 100 mm in length and width. The spacer S is formed by cutting a copper electrode plate into a T shape and bending the ends. The cathode electrode plate sandwiches both sides of a 2 mm thick, 100 x 100 mm Mg anode electrode plate 20 via the spacer S. When the two Mg anode electrode plates 20 are alternately sandwiched between the three copper cathode electrode plates 10 via the spacer S, the state shown in the upper end view in Figure 6B is obtained. Using this combination of electrodes does not form the microcapacitor shown in Figure 1.

[0018] Prepare an electrolyte solution in a plastic container by adding 0.5 mol / l or more, preferably 1.5 mol / l to 2 mol / l, of sodium chloride to approximately 1500 ml of pure water. Add 50-100 g of sodium percarbonate and 50 ml of 30% hydrogen peroxide solution to this solution. As the battery reaction progresses, the hydrogen peroxide will be consumed and the light bulb will dim after a certain period of time, so add 10 ml of 30% hydrogen peroxide solution every 2-3 hours.

[0019] In this embodiment, the performance of the electrode configurations shown in Figures 3A and 3B and Figures 6A and 6B was compared to compare the performance when a microcapacitor is formed on the copper cathode electrode surface versus when it is not. Since all conditions except the electrode configuration were the same, the hydrogen peroxide fuel cell reaction in alkaline electrolyzed water is the same in that it is accompanied by a magnesium-air cell reaction. Therefore, based on the following reaction equation, hydrogen peroxide reacts with H2O2 + 2H2O + 2e - →2H2O+2OH - While it decomposes into H2O2 + 2OH on the cathode electrode side, - →O2+2H2O+2e - In addition to causing oxidation reactions, metal oxidation reactions in alkaline electrolytes occur, such as Mg → Mg 2+ +2e - As a result, the reaction that reduces and ionizes oxygen on the cathode side is O2 + 2H2O + 4e - →4OH -A typical metal-air cell reaction occurs. However, while it is understood that oxygen gas is generated in hydrogen peroxide fuel cells and metal-air cell reactions, in the above configuration, not only oxygen gas but also hydrogen gas is generated. This suggests that, as indicated in Non-Patent Literature 3 (by Eiji Mizuto, Progress in Physical Chemistry (1936), 10(3): pp. 154-165), a catalytic function is at work on the surface of the copper cathode electrode, causing the decomposition of hydrogen peroxide or hydroxyl ions, which leads to the power generation reaction. 2H₂O₂→4·OH→H₂+O₂+4e⁻ 4OH - →H2+O2+4e -

[0020] Considering the experimental results above, it was found that, depending on the configuration for creating the microcapacitor, the fuel cell with the microcapacitor shown in Figure 3 shows more than twice the current increase compared to the one without the microcapacitor shown in Figure 6. This indicates that the current collection and discharge effect associated with the microcapacitor has a significant impact on the power generation of the battery. Therefore, the configuration of the present invention is groundbreaking because it can provide a novel and useful configuration for a single-compartment hydrogen peroxide fuel cell.

Claims

1. A hydrogen peroxide fuel cell comprising a water-soluble electrolyte containing hydrogen peroxide as a dipole compound and forming a dipole electric double layer at the interface with the electrode, a cathode electrode made of metallic copper or an alloy thereof, and an anode electrode made of metal or an alloy thereof that forms an electrode potential difference with an electrode potential lower than that of the cathode electrode, wherein the cathode electrode has electrode protrusions, and a plurality of microcapacitors are provided in close proximity to the anode electrode via the electrode protrusions, formed by the electrode protrusions of the cathode electrode, the surface of the anode electrode, and the water-soluble electrolyte containing hydrogen peroxide between them, and the microcapacitors have the function of providing electron flow from the cathode electrode to the anode electrode via the microcapacitors.

2. The hydrogen peroxide fuel cell according to claim 1, wherein the microcapacitor is a dipole electric double layer formed of an acute-angled triangular projection electrode protruding from the cathode electrode surface and a water-soluble electrolyte containing hydrogen peroxide sandwiched between the tip of the projection electrode and the anode electrode surface.

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