A device for electrochemically and reversibly storing dihydrogen.

Abstract

The present invention is an apparatus (1) for electrochemically and reversibly storing dihydrogen, said apparatus comprising a sealed chamber (2) intended to receive an electrolyte medium (3) and gaseous dihydrogen (4), connection means (5) suitable for connecting said sealed chamber to a gas circuit (6), at least one first electrode (7) arranged inside said sealed chamber, and at least one second electrode (8). Said at least one second electrode is suitable for oxidizing gaseous dihydrogen dissolved in the electrolyte medium to form protons, and reducing the protons to form gaseous dihydrogen, according to Formula 1. JPEG2026536524000016.jpg9170 Said at least one first electrode comprises at least one redox pair M that is insoluble in said electrolyte medium y / M x , said at least one redox pair is configured to assume at least two oxidation states according to Formula 2, and is suitable for being reduced from the oxidation state M y to the reduced state M x , or vice versa, JPEG2026536524000017.jpg9170 wherein x and y are oxidation numbers in the formula. The absolute potential difference |ΔE| between the redox potential of the pair H + / H2 in the case of a given electrolyte medium and gaseous dihydrogen within a given pressure range, and the redox potential of at least one pair M y / M x is 0.6 V or less

Description

[Technical Field]

[0001] This invention relates to the field of dihydrogen storage.

[0002] In particular, the present invention relates to an apparatus and method for reversibly storing dihydrogen over a long period of time. [Background technology]

[0003] Replacing fossil fuels with renewable energy sources (such as solar, wind, or hydropower) requires the large-scale development of means to store intermittently generated electrical energy. This storage is essential because electricity production fluctuates significantly, with peak production and consumption changing daily. Furthermore, particularly with solar power, there is a seasonal gap between the peak summer electricity production and the peak winter heating demand. Therefore, energy storage methods capable of storing energy for several hours to several months are needed.

[0004] One of the main options is to significantly increase electrochemical energy storage. Currently, lithium-ion battery technology is dominant in the market. Other technologies, such as redox flow batteries and older technologies like nickel-iron batteries, iron-oxygen batteries, or nickel-metal hydride batteries, are also considered options. However, current electrochemical energy storage technologies are only suitable for relatively short storage periods and can only temporarily stabilize the frequency of the power grid or stabilize the daily fluctuations between maximum power generation and maximum consumption. Technical limitations such as self-discharge and the cost per kWh of storage are also barriers, making them unsuitable for seasonal energy storage.

[0005] 100m that meets insulation standards 2For a small, newly built house, storing renewable energy seasonally using lithium-ion technology would cost an exorbitant amount of thousands of euros. Furthermore, lithium-ion batteries occupy at least several cubic meters of volume. Moreover, such a concentration of batteries poses a significant fire risk. A safer alternative is redox flow batteries. However, they have a lower energy density, and the volume required for the batteries can reach tens of cubic meters. In addition, the rapid development of electrochemical energy storage technologies for mobile or stationary applications could soon impact the availability of mineral resources used in their manufacture, potentially leading to increased costs and raw material shortages for these technologies.

[0006] In addition to daily or weekly storage, seasonally storing renewable energy over several months remains a major challenge. In principle, this long-term storage is possible with dihydrogen, but one of the main challenges is that dihydrogen molecules are relatively difficult and expensive to store, and above all, there are safety concerns regarding the storage of dihydrogen under ultra-high pressure.

[0007] Regarding dihydrogen storage, it is possible to store dihydrogen in its pure form or in the form of a liquid organic hydrogen carrier by compressing or liquefying the gas, adsorption onto porous materials, or formation of metal hydrides. Each of these technologies has its advantages and disadvantages, but none of them have been deployed on a large scale for renewable energy storage at present.

[0008] A particularly promising alternative method in recent years is based on the interconversion of solid metal oxides to solid metals. For example, exposing a metal oxide to dihydrogen produces metal, and exposing a metal to an aqueous solution produces dihydrogen gas, which may be supercritical in some cases or at a temperature above 200°C and at least at the saturated vapor pressure of water. Energy can also be released by utilizing the combustion of iron in air, but this has the limitation of potentially producing nitrogen oxides. Another typical method for storing renewable energy combines the electrochemical reduction of zinc ions to metal zinc at one electrode with the oxidation of water at a second electrode. In a separate process, metallic zinc is chemically converted into zinc ions and hydrogen as needed. However, all of these alternative methods have limitations; they are not suitable for direct application in individual homes or small communities, and even less so for application in large-scale industrial facilities. [Overview of the project] [Problems that the invention aims to solve]

[0009] Therefore, there is a very high need to store hydrogen, especially hydrogen produced by electrolysis. [Means for solving the problem]

[0010] The object of the present invention is to provide an apparatus and method for electrochemically and reversibly storing hydrogen, having the following features. - The ability to stably store dihydrogen, - No risk, - For example, it must be possible to store it for a long period of time, such as several tens of days or several months. - Low cost, - Suitable for community storage or private storage (e.g., a single-family home or a small community), but not limited to these. - Utilizing abundant elements, - Capable of storing and releasing dihydrogen as needed. - Can be carried out at room temperature or a temperature close to room temperature, and / or - Can be carried out at atmospheric pressure or a pressure close to atmospheric pressure.

[0011] For this purpose, an electrochemical and reversible dihydrogen storage device is provided. This device comprises the following components. - An electrolytic medium and a sealed chamber intended to receive gaseous dihydrogen, - Connection means suitable for connecting the sealed chamber to a gas circuit, - At least one first electrode and at least one second electrode. The at least one first electrode and the at least one second electrode are arranged inside the sealed chamber.

[0012] The at least one second electrode is suitable for oxidizing the gaseous dihydrogen dissolved in the electrolytic medium to form protons or hydrogen ions or hydronium ions, and reducing the protons or hydrogen ions or hydronium ions to form gaseous dihydrogen, according to Equation 1. JPEG2026536524000002.jpg12170

[0013] The at least one first electrode comprises at least one redox couple M that is insoluble in the electrolytic medium y / M x wherein the at least one redox couple is configured to assume at least two oxidation states according to Equation 2, and is suitable for being reduced from the oxidation state M y to the reduced state M x , or conversely, that is, suitable for being oxidized from the reduced state M x to the oxidation state M y , JPEG2026536524000003.jpg10170 wherein x and y are oxidation numbers.

[0014] The redox potential of the pair H for a given electrolytic medium and gaseous dihydrogen within a given pressure range + / H2, and at least one pair M y / M x The absolute potential difference |ΔE| with the oxidation-reduction potential is 0.6V or less.

[0015] Preferably, the electrolyte medium is not included in the apparatus and is not part of the apparatus. Preferably, the at least one first electrode and the at least one second electrode of the apparatus are intended to be in contact with the electrolyte medium.

[0016] The electrolyte medium may be part of the apparatus.

[0017] Preferably, |ΔE|=E(H + / H2)-E(M y / M x ) and in the formula, E(M y / M x ) is at least one for M y / M x This is the oxidation-reduction potential (in volts), and E(H + / H2) is the case of gaseous dihydrogen with a predetermined electrolyte medium and a predetermined pressure range relative to H + This is the oxidation-reduction potential of H2 (unit: volts).

[0018] In this specification, the terms “dihydrogen” or “gaseous dihydrogen” mean or refer to gaseous dihydrogen (H2).

[0019] Preferably, the gaseous dihydrogen oxidized at at least one second electrode is dissolved in the electrolyte medium. Preferably, as used herein, “oxidation” or “reduction” of a compound is understood to mean electrochemical oxidation or electrochemical reduction of the compound in the electrolyte medium.

[0020] Preferably, the pressure of the electrolyte medium and / or the gaseous dihydrogen (in the sealed chamber) is equal to the pressure in the sealed chamber.

[0021] Preferably, unless otherwise specified, the potential or oxidation-reduction potential is expressed in volts (V).

[0022] Preferably, at least one first electrode and at least one second electrode are intended to be in contact with and / or immersed in the electrolyte medium. In other words, when the device is operating, at least one first electrode and at least one second electrode are in contact with and / or immersed in the electrolyte medium.

[0023] Preferably, the gas circuit is not part of the apparatus. Preferably, the gas circuit is an external gas circuit, and the connection means is intended to be connected to this gas circuit.

[0024] Preferably, at least one redox pair M y / M x It is insoluble in a given electrolyte medium.

[0025] Preferably, at least one redox pair M y / M x At least two of the redox forms, preferably each redox form, are electroactive.

[0026] Preferably, at least one redox pair M y / M x It is in solid form.

[0027] Preferably, at least one redox pair M y / M x It is in contact with and / or attached to and / or fixed to and / or grafted to at least one first electrode. Preferably, at least one redox pair M y / M x It does not dissolve in the electrolyte medium.

[0028] Preferably, a portion of the total volume inside the sealed chamber is intended to be filled with an electrolyte medium, and the remaining portion of the total volume inside the sealed chamber is intended to be filled with gaseous dihydrogen.

[0029] Preferably, the apparatus according to the present invention is not a battery and / or fuel cell and / or electrolytic cell for water splitting, and is not intended, and / or suitable, and / or configured to operate as a battery and / or fuel cell and / or electrolytic cell for water splitting.

[0030] Preferably, according to this specification, the gaseous dihydrogen that reacts with at least one second electrode is dissolved in the electrolyte medium.

[0031] Preferably, E(M y / M x The voltage range is -0.6V to +0.6V relative to the reversible hydrogen electrode. 0 (H + (H2) is an electrolyte solution with a pH of 0 and an absolute pressure of 1 × 10⁻⁶. 5 If the voltage is Pascal, it will be 0V relative to a standard hydrogen electrode.

[0032] Preferably, |ΔE| is 0.55V or less, more preferably 0.50V or less, even more preferably 0.45V or less, most preferably 0.40V or less, even more preferably 0.35V or less, particularly advantageously 0.30V or less, even more advantageously 0.25V or less, even more particularly advantageously 0.20V or less, in a more preferable way 0.15V or less, in a more preferable way 0.10V or less, in an even more particular way 0.05V or less, and in the most preferable way equal to 0V.

[0033] When the electrolyte medium is an aqueous solution, the oxidation-reduction reaction occurring at the second electrode, namely the oxidation of gaseous dihydrogen and the reduction of water, can also be expressed as follows, depending on the pH and the pressure of gaseous dihydrogen. JPEG2026536524000004.jpg11170

[0034] Therefore, preferably, at least one second electrode is suitable for oxidizing gaseous dihydrogen in an aqueous medium according to formula 3 to form water, and then reducing the water to form gaseous dihydrogen and hydroxide.

[0035] At least one first electrode contains multiple water-insoluble redox pairs (M y / M x M z / M y M a / M z It is acceptable for the range to include a>z>y>x).

[0036] These multiple redox pairs may be composed of or made from a single chemical element or material, or they may be composed of or made from different chemical elements or materials.

[0037] At least one first electrode contains multiple materials or chemical elements, This may be used for fabrication. At least one first electrode is coated on a conductive material with at least one redox pair M y / M x Does it include, This can be used for production.

[0038] The device may include a plurality of at least one first electrode and / or a plurality of at least one second electrode connected in parallel.

[0039] The electrolyte medium may be a gel or a solid. Preferably, the electrolyte medium is a liquid.

[0040] Preferably, the electrolyte medium is a proton acceptor. Preferably, the electrolyte medium is capable of solvating protons and / or accepting protons.

[0041] Therefore, preferably, at least one second electrode is suitable for oxidizing gaseous dihydrogen dissolved in the electrolyte medium to form protons that are solvated / accepted by the electrolyte medium, and for reducing the electrolyte medium to form gaseous dihydrogen according to Equation 1.

[0042] Preferably, the sealed chamber does not contain gaseous dioxygen.

[0043] Preferably, gaseous dioxygen or dissolved gaseous dioxygen is not required and / or involved in the storage and / or release of dihydrogen according to the present invention. Preferably, gaseous dioxygen or dissolved gaseous dioxygen is not required and / or involved in the electrochemical reactions and / or oxidation-reduction reactions of the apparatus according to the present invention.

[0044] Preferably, the electrolyte medium includes or is composed of a protic medium.

[0045] The protic media include or consist of alcohols, carboxylic acids, amino compounds, ammonia, sulfonated compounds, phosphonic acid compounds, boron compounds, or mixtures thereof.

[0046] The protic medium may contain or consist of a protic ionic liquid.

[0047] The protic medium can be composed of a deep eutectic solvent.

[0048] Preferably, the electrolyte medium contains water or is composed of water.

[0049] The electrolyte medium does not have to contain water, or may be different from water, and may contain at least one redox pair M y / M x The oxidation-reduction potential of is higher than that of the electrolyte medium.

[0050] The electrolyte medium does not have to contain water, or may be different from water, and may contain at least one redox pair M y / M x The oxidation-reduction potential of is lower than that of the electrolyte medium.

[0051] Preferably, the electrolyte medium contains or is composed of water, and also contains at least one redox pair M y / M x Its oxidation-reduction potential is lower than that of water.

[0052] Preferably, the electrolyte medium contains or is composed of water, and also contains at least one redox pair M y / M x The oxidation-reduction potential of is greater than or less than the reduction potential of water.

[0053] Preferably, the electrolyte medium is — At least one redox pair M Y / M x The spontaneous reaction between the electrolyte medium and / or — Gaseous dihydrogen and at least one redox pair M y / M x A natural reaction It contains one or more additives to limit or suppress [something].

[0054] Preferably, one or more additives provide at least one redox pair M in the electrolyte medium. y / M x It is configured, or suitable, to prevent dissolution. Therefore, preferably, one or more additives are at least one redox pair M y / M x This enables or facilitates the maintenance of the material in a state of being fixed or attached to at least one first electrode.

[0055] The electrolyte medium intended to be received in the sealed chamber is a liquid. - The apparatus includes means configured to remove the electrolyte medium and reintroduce it into the sealed chamber, and / or - The at least one first electrode, preferably in a reduced state M x At least one pair M located y / M x The first electrode, which includes the first electrode, is configured to be removed from the electrolyte in the sealed chamber and then reintroduced.

[0056] Preferably, means are provided for removing the electrolyte medium from the sealed chamber, pumping it out, or discharging the electrolyte medium from the sealed chamber, and preferably means are provided for filling the sealed chamber with the electrolyte medium or bringing the electrolyte medium back into contact with the electrodes.

[0057] Preferably, at least one first electrode is configured to be removed or withdrawn from the electrolyte, and more preferably, at least one redox pair M y / M x Reduction form M x It is configured to limit or avoid spontaneous oxidation.

[0058] Preferably, after gaseous dihydrogen is stored at or within the first electrode, that is, at least one pair M y / M x Reduced state M x When this is the case, the electrolyte medium is removed from the sealed chamber, and / or at least one first electrode is removed from the electrolyte medium.

[0059] Preferably, when it is necessary to release gaseous dihydrogen from the apparatus, the electrolyte medium is brought back into contact with the electrodes in the sealed chamber, that is, the sealed chamber is filled with the electrolyte medium again.

[0060] Preferably, at least one first electrode is brought back into contact with the electrolyte medium in the sealed chamber, i.e., at least one first electrode is returned to the electrolyte in the sealed chamber, and more preferably, when it is necessary to release gaseous dihydrogen from the apparatus, at least one first electrode is moved from the gaseous medium to the electrolyte medium in the sealed chamber.

[0061] Removing the electrolyte medium from the sealed chamber and / or removing at least one first electrode from the electrolyte medium is equivalent to removing at least one redox pair M y / M x This is a method to prevent or avoid spontaneous reaction between the electrolyte medium and the electrolyte medium.

[0062] Preferably, the at least one redox pair M y / Mx teeth, — Metals such as iron, zinc, tungsten, cadmium, copper, bismuth, antimony, and lead, and metal hydrides such as LaNi5, — Contains insoluble organic molecules such as anthraquinones, and / or insoluble redox polymers such as polyaniline.

[0063] Preferably, the at least one second electrode includes a catalyst or combination of catalysts suitable for oxidizing gaseous dihydrogen dissolved in the electrolyte medium to form protons, and then reducing the protons to form gaseous dihydrogen, according to Formula 1.

[0064] Preferably, the catalyst or combination of catalysts is active for both the hydrogen evolution reaction and the hydrogen oxidation reaction.

[0065] At least one second electrode may be made of, or contain, several catalysts that are active for both hydrogen evolution and hydrogen oxidation reactions.

[0066] The catalyst may be, for example, a precious metal, such as platinum (Pt), palladium (Pd), gold (Au), rhodium (Rh), iridium (Ir), or ruthenium (Ru), or a catalyst containing these. Preferably, the catalyst may be, for example, a dimetallic alloy or a polymetallic alloy, such as PtCo, PtNi, PtIr, or PtRu, or a catalyst containing these. Preferably, the catalyst may be, for example, a transition metal, such as nickel, nickel-molybdenum (NiMo) alloy, or nickel-boron (NiB), or a catalyst containing these. Preferably, the catalyst may be, for example, a metal / nonmetallic doped carbon-based catalyst, such as Pt or Pd nanoparticles supported on carbon black or carbon nanotubes, or a nitrogen-doped carbon material, or a catalyst containing these. Preferably, the catalyst may be, for example, a polymer-derived catalyst, such as a pyrolysis metal polymer complex containing a metal like Pt or Ni, or a catalyst containing these. Preferably, the catalyst is, for example, a metal phosphide, metal nitride, metal carbide, or metal sulfide, such as nickel phosphide (Ni2P), cobalt phosphide (CoP), ruthenium phosphide, ruthenium sulfide, ruthenium carbide, tungsten carbide (WC), ruthenium nitride, or ruthenium phosphide-ruthenium sulfide, or may contain these.

[0067] Preferably, the apparatus further comprises supply means configured to inject gaseous dihydrogen into the sealed chamber or remove gaseous dihydrogen from the sealed chamber via the gas circuit. Preferably, the apparatus and / or the supply means are configured to maintain the pressure of gaseous dihydrogen in the sealed chamber within a predetermined pressure range.

[0068] The apparatus may further include two current collectors connected to the at least one first electrode and the at least one second electrode, respectively.

[0069] The apparatus may further include a current generator configured to pass an electric current between the at least one first electrode and the at least one second electrode.

[0070] Preferably, the current generator is configured to control and / or stop the injection of current into at least one first electrode and at least one second electrode in accordance with a potential difference measured using dedicated means for measuring the potential difference between at least one first electrode and at least one second electrode. The current generator may also be configured to stop injecting current into at least one first electrode and at least one second electrode when a predetermined potential difference or potential difference threshold is reached between at least one first electrode and at least one second electrode.

[0071] The apparatus may further include means for monitoring and / or controlling the pressure of gaseous dihydrogen in the sealed chamber.

[0072] Means for monitoring and / or controlling pressure include, or may be constructed from, a control unit and / or a command unit and / or a processing unit. The control unit and / or command unit and / or processing unit may be arranged and / or configured and / or programmed to issue commands to supply means and / or current generators.

[0073] The present invention also provides a method for electrochemically and reversibly storing dihydrogen in an apparatus according to the present invention. The method includes the step of storing gaseous dihydrogen in the apparatus. The storage step is - A step of supplying gaseous dihydrogen to a sealed chamber of the apparatus by a supply means until a predetermined pressure range is reached, wherein the apparatus includes at least one first electrode and at least one second electrode and includes an electrolyte medium, and the gaseous dihydrogen is injected through a connecting means of the sealed chamber that connects the sealed chamber to a gas circuit, preferably an external gas circuit. - By injecting current into at least one first electrode using a current generator, at least one redox pair M that is insoluble in the electrolyte medium of at least one first electrode is generated. y / M x oxidized state M y From reduced state M xThe process comprises reducing the gas to a certain value and oxidizing the dissolved gaseous dihydrogen at at least one second electrode to form a proton, a hydrogen ion, or a hydronium ion.

[0074] The case where the electrolyte medium is a gaseous dihydrogen within a predetermined pressure range is the H + The oxidation-reduction potential of / H2 and the at least one pair M y / M x The absolute potential difference |ΔE| with the oxidation-reduction potential is 0.6V or less.

[0075] Preferably, the current density injected into at least one first electrode and at least one second electrode is lower than the current density used in fuel cells or electrolytic cells for water splitting. For example, the current density injected into at least one first electrode and at least one second electrode is preferably such that the electrode area is 1 cm². 2 Less than 100mA per unit, more preferably 10mA / cm² 2 Further, and more preferably, 1 mA / cm 2 The following applies:

[0076] Preferably, the charge / discharge rate C is lower than the charge / discharge rate of the battery, where C is the capacity of the device. For example, the charge / discharge rate is preferably 0.05C or less, more preferably 0.01C or less, and even more preferably 0.005C or less.

[0077] Preferably, the method further includes a step of releasing gaseous dihydrogen from the apparatus. The release step is - At least one first electrode, the at least one redox pair M y / M x Reduced state M x From oxidation state M y By oxidizing it and injecting a current into the at least one second electrode, the proton is reduced at the at least one second electrode to form gaseous dihydrogen, - Discharging or removing the gaseous dihydrogen from the sealed chamber via the connecting means.

[0078] Preferably, the method includes means for monitoring and / or controlling the pressure of gaseous dihydrogen in the sealed chamber, such that the pressure of gaseous dihydrogen is equal to a gauge pressure of 1 × 10⁻⁶ at ambient temperature. 6 The process further includes monitoring and / or controlling the temperature to be less than or equal to a Pascal.

[0079] Preferably, the pressure of the gaseous dihydrogen is such that the gauge pressure at ambient temperature is 2 × 10⁻⁶. 3 ~8×10 5 It is monitored and controlled to become Pascal.

[0080] Preferably, the apparatus according to the present invention is configured to carry out the method according to the present invention, more preferably specifically to carry out the method according to the present invention. Thus, any feature of the apparatus according to the present invention can be adapted and / or integrated into the method according to the present invention, and vice versa.

[0081] Other objects, features, and advantages of the present invention will become apparent from the following detailed description of some embodiments of the invention with reference to the accompanying drawings. [Brief explanation of the drawing]

[0082] [Figure 1] This is a schematic side view of one embodiment of the apparatus according to the present invention. [Figure 2] Figures 2A, 2C, and 2D show cyclic voltammetry curves obtained with the first electrode containing carbonyl iron as the redox pair My / Mx. Figure 2B shows cyclic voltammetry obtained with the first electrode containing Fe3O4 as the redox pair My / Mx. Figures 2A and 2B show experiments conducted with an aqueous electrolyte medium containing 1M KOH, Figure 2C shows an aqueous electrolyte medium containing 25% KOH by volume, and Figure 2D shows experiments conducted with an aqueous electrolyte medium containing 25% KOH by volume and 0.01M Na2S. The potential scanning speed was 1mV / s, and the experiments were conducted under an H2 atmosphere. [Figure 3]The upper graph shows 100 charge-discharge cycles of the apparatus according to the first embodiment, where the first electrode contains carbonyl iron as the redox pair My / Mx, and charge-discharge was performed at 0.1 μA in an aqueous electrolyte medium containing 1 M KOH under an H2 atmosphere. The lower graph shows the Coulomb efficiency of the apparatus calculated from the charge-discharge data in the upper graph. [Figure 4] Figure 4A shows the cyclic voltammetry curve obtained with the first electrode containing bismuth as the redox pair My / Mx. The experiment was conducted in an aqueous electrolyte medium containing 1M KOH, with a potential scanning rate of 1mV / s, and under an H2 atmosphere. Figure 4B shows the cyclic voltammetry curve obtained with the first electrode containing LaNi5 as the redox pair My / Mx. The experiment was conducted in an aqueous electrolyte medium containing 1M KOH, with a potential scanning rate of 1mV / s, and under an H2 atmosphere. [Figure 5] Figure 5A shows the cyclic voltammetry curve obtained with the first electrode containing antimony as the redox pair My / Mx. The experiment was conducted in an aqueous electrolyte medium containing 1M KOH, with a potential scanning speed of 1mV / s, and under an H2 atmosphere. Figure 5B shows the cyclic voltammetry curve obtained with the first electrode containing zinc as the redox pair My / Mx. The experiment was conducted in an aqueous electrolyte medium containing 1M KOH, with a potential scanning speed of 1mV / s, and under an H2 atmosphere. Figure 5C shows the cyclic voltammetry curve obtained with the first electrode containing anthraquinone as the redox pair My / Mx. The experiment was conducted in an aqueous electrolyte medium containing 1M KOH, with a potential scanning speed of 1mV / s, and under an H2 atmosphere. [Figure 6] The upper graph shows 100 charge-discharge cycles of the apparatus according to the first embodiment. The first electrode contains bismuth as the redox pair My / Mx, and charge-discharge was performed at 0.1 μA in an aqueous electrolyte medium containing 1 M KOH under an H2 atmosphere. The lower graph shows the Coulomb efficiency of the apparatus calculated from the charge-discharge data in the upper graph. [Figure 7]Figure 7A shows the charge-discharge cycle of the apparatus according to the first embodiment, where the first electrode contains anthraquinone as the redox pair My / Mx, and the charge-discharge cycle was performed at 0.5 μA in an aqueous electrolyte medium containing 1M KOH under an H2 atmosphere. Figure 7B shows the charge-discharge cycle of the apparatus according to the first embodiment, where the first electrode contains LaNi5 as the redox pair My / Mx, and the charge-discharge cycle was performed at 5 μA in an aqueous electrolyte medium containing 1M KOH under an H2 atmosphere. Figure 7C shows the charge-discharge cycle of the apparatus according to the first embodiment, where the first electrode contains antimony as the redox pair My / Mx, and the charge-discharge cycle was performed at 0.5 μA in an aqueous electrolyte medium containing 1M KOH under an H2 atmosphere. [Figure 8] Figure 8A shows the cyclic voltammetry curve obtained at the first electrode containing carbonyl iron as the redox pair My / Mx. Cyclic voltammetry was performed using an aqueous electrolyte medium containing 1M KOH, with a potential scanning rate of 0.1 mV / s, and the experiment was conducted by continuously injecting N2 into a sealed chamber. Figure 8B is a graph obtained from the cyclic voltammetry curve shown in Figure 8A, showing the current measured over time. Figure 8C shows the reaction of the online H2 sensor during the cyclic voltammetry cycle shown in Figure 8A. [Figure 9] The upper graph shows the constant current cycle obtained with the first electrode containing carbonyl iron as the redox pair My / Mx, performed in a sealed chamber with continuous injection of N2 and an aqueous electrolyte medium containing KOH 1M. The lower graph shows the reaction of the online H2 sensor during the constant current cycle shown in the upper graph. [Modes for carrying out the invention] [Examples]

[0083] The following embodiments are not restrictive, and other embodiments including selections of the features described below may also be contemplated. Where a selection is sufficient to provide a technical advantage or to distinguish the present invention from the prior art, the selection may consist of a feature isolated from a series of features (even if this selection is isolated in a sentence that includes other features). This selection comprises at least one feature, preferably described by technical function without including structural features, or includes some of the structural details if that part is sufficient to provide a technical advantage or to distinguish the present invention from the prior art.

[0084] Referring to Figure 1, an embodiment of the apparatus 1 (referred to as apparatus 1) for electrochemically and reversibly storing dihydrogen according to the present invention is described. The apparatus 1 has a sealed chamber 2 intended to contain an electrolyte medium 3 and gaseous dihydrogen 4. The sealed chamber 2 is sealed against gases and liquids. The sealed chamber 2 is 1×10 7 Pascals, preferably 5×10 6 Pascals or less. The method for electrochemically and reversibly storing dihydrogen according to the present invention (referred to as the present method) does not require high-pressure gaseous dihydrogen 4 in the sealed chamber 2. Therefore, the apparatus 1 may be installed near a residence. The pressure of the gaseous dihydrogen 4 in the sealed chamber 2 must be higher than atmospheric pressure to prevent atmospheric gases, in particular dioxygen, from diffusing within the sealed chamber 2, in particular inside the electrolyte medium 3. In practice, the presence of gaseous dioxygen in the apparatus 1, in particular in the sealed chamber 2, must be avoided. Usually, to avoid diffusion of atmospheric gases in the sealed chamber 2, it is sufficient that the gauge pressure in the sealed chamber 2 is 2×10 3 Pascals or higher.

[0085] The device 1 further comprises at least one first electrode 7 and at least one second electrode 8 arranged inside the sealed chamber 2. The device 1 further comprises one first electrode 7 and one second electrode 8 according to a non-limiting embodiment. The electrode 8 is suitable for oxidizing gaseous dihydrogen dissolved in the electrolyte medium 3 to form protons, and reducing protons to form gaseous dihydrogen, in accordance with the following Formula 1. JPEG2026536524000005.jpg9170

[0086] The electrode 7 comprises at least one redox pair M that is insoluble in the electrolyte medium 3 y / M x . The at least one redox pair M y / M x is configured to exhibit at least two oxidation states M y and M x . The at least one redox pair M y / M x is suitable for being reduced from the at least one oxidation state M y to the at least one reduced state M x and being oxidized from the at least one reduced state M x to the at least one oxidation state M y , in accordance with the following Formula 2. JPEG2026536524000006.jpg9170

[0087] When the electrolyte medium 3 contains or is composed of water, that is, when the solvent of the electrolyte medium 3 contains or is composed of water, the oxidation of dissolved gaseous dihydrogen 4 and the reduction of protons occurring at the electrode 8 may be accompanied by the generation and / or consumption of water, hydronium ions and / or hydroxide ions, depending on the pH of the aqueous electrolyte medium 3.

[0088] Therefore, according to the present invention, the storage of gaseous dihydrogen converts gaseous dihydrogen 4 into protons and electrons at the second electrode 8, and at the same time, these electrons are used to convert the oxidized form M of the at least one redox pair M y / M x y (or one of them) into the reduced form M x ​By reducing to (or one of them), at least one pair M y / M x Reduction state M x This is done by storing it in the first electrode 7 via [a certain method]. Thus, according to the present invention, gaseous dihydrogen is not stored in gaseous form, but in another form, namely, dissociated as protons and electrons, in a single tank (sealed chamber 2), but the protons and electrons are dissolved in the electrolyte medium 3 and stored in the first electrode 7 in the form of insoluble reduced redox pairs. In the more advantageous embodiments described below, electrons are stored in at least one redox pair M y / M x After storage, the electrons and protons can be further separated by removing the electrolyte medium 3 from the sealed chamber 2 and / or removing at least one first electrode 7 from the electrolyte medium. This results in the safest dihydrogen storage compared to high-pressure and / or liquid dihydrogen storage, which should be avoided in residential areas and / or near urban or densely populated areas. Furthermore, small-scale pressurization (typically 250-700 bar) of gaseous dihydrogen and liquefaction of gaseous dihydrogen are costly. According to the present invention, such costs are avoided. In addition, in the present invention, the reaction rate between the redox pair and the electrolyte medium 3 is relatively slow in the optimized electrolyte medium 3, and the electrode 7 and the electrolyte medium 3 can be reversibly separated, thus enabling long-term storage.

[0089] Furthermore, the first electrode 7 and / or at least one redox pair M y / M x and / or electrolyte medium 3 contains at least one redox pair M y / M x Reduction form M x Selected to suppress the natural oxidation of. In this storage process, at least one pair of M y / M x The oxidation-reduction potential E(M) y / M x Depending on the situation, energy is supplied to the device 1 or recovered from the device 1 by injecting a current at a predetermined potential between electrode 7 and electrode 8.

[0090] Gaseous dihydrogen 4 contains at least one pair of M y / M x Reduction state M x at least one against M y / M x Oxidation state M y And it is recovered by converting it into electrons. At the same time, gaseous dihydrogen 4 is produced at at least one second electrode 8 by reducing the protons. In this recovery step, at least one pair M y / M x The oxidation-reduction potential E(M) y / M x Depending on the situation, energy is supplied to or recovered from the device 1 by injecting a current between electrodes 7 and 8 at a predetermined potential. In this way, according to the present invention, gaseous dihydrogen 4 can be released instantaneously as needed.

[0091] The redox reaction of a redox pair shows, reflects, or expresses the relationship between the oxidation number of the oxidation state and the oxidation number of the reduction state of the redox pair. Therefore, as is known to those skilled in the art, such an expression / relationship is not necessarily electrically equilibrium. This is the case in Equation 2.

[0092] Furthermore, as mentioned above, at least one pair of M y / M x It is fixed to the electrode and never solvates in the electrolyte medium 3.

[0093] Furthermore, Equation 2 is not electrically balanced, indicating that dihydrogen storage / recovery does not occur spontaneously, but requires the input / supply of electrical energy (i.e., a flow of electrons).

[0094] For these reasons, Equation 2 is not spontaneously electrically neutral and is a process that stores dihydrogen (i.e., at least one redox pair M) y / M x Oxidation form M y (or one of them) reduced form M xThe process involves reducing the hydrogen to (simultaneously oxidizing gaseous dihydrogen 4 to protons and electrons), and recovering dihydrogen (i.e., at least one redox pair M). y / M x Reduction form M x (or one of them) in oxidative form M y It is emphasized that electrical energy is required for oxidation to (or one of) these substances (simultaneously reducing protons and electrons to form gaseous dihydrogen 4). JPEG2026536524000007.jpg9170

[0095] As described herein, energy storage requires at least one redox pair M y / M x Oxidation form M y Reduce to reduced form M x (or one of them), and conversely, at least one redox pair M y / M x Reduction form M x Oxidized to form M y In the process of making (or one of) these, external electrical energy, i.e., electrons, is required.

[0096] Therefore, those skilled in the art will directly and clearly infer that formula 2 can preferably be expressed in an obscure way, for example, as follows. JPEG2026536524000008.jpg18170 This is, for example, an oxidation-reduction pair M y / M x This applies when the compound is organic and / or not a hydrate or coordination complex. JPEG2026536524000009.jpg8170 This is, for example, when the compound or atom M is inorganic and / or a coordination complex, but is not limited to this, M in the formula y M y It can also be written as C (M y C may be a hydrate / coordination complex), or JPEG2026536524000010.jpg9170 This is, for example, when the compound or atom M is inorganic and / or a coordination complex, but is not limited to this, M in the formula y is M y C p It may also be written as (M y C p (This may be a hydrate / coordination complex), or JPEG2026536524000011.jpg9170 This is, for example, when the compound or atom M is inorganic and / or a coordination complex, but is not limited to this, M in the formula x M x C p It may also be written as (M x C p (This may be a hydrate / coordination complex).

[0097] C can be written as follows, may include the following, or may consist of the following: - One or more identical or different atoms or molecules of the solvent, particularly in the neutral form of the solvent. - One or more identical or different ligands and / or one or more identical or different atoms or molecules of an ionic solvent, or one or more identical or different atoms or molecules of the ionic form of the solvent (a non-neutral solvent or a partially charged solvent, which may be protic or aprotic, e.g., hydronium ions or hydroxide ions), - One or more identical or different atoms or molecules of the electrolyte medium 3, - One or more identical or different atoms or molecules of the salt (preferably contained in electrolyte medium 3), and / or - One or more identical or different atoms or molecules of the electrolyte (of electrolyte medium 3).

[0098] For example, if the solvent is protic, then the solvent S (and its conjugated form) can be expressed as follows: JPEG2026536524000012.jpg10170

[0099] For example, the electrolyte medium 3 may preferably contain a salt or an electrolyte, but this is not essential. - Na + , K + Li + Ca 2+ Mg 2+ Cl - F - , SO3 - NO3 - 5CN - and / or CO3 2-

[0100] For example, C may be the following, or may include the following: - Preferably, when the pH is 10 or higher, OH - (When the solvent is water or a protic solvent) and / or counterion (Na + , K + Li + Ca 2+ , and / or Mg 2+ etc.), - Preferably, if the pH is 4 or less, H3O + (or H + ) (when the solvent is water or a protic solvent) and / or counterion (CO3 2- F - , HCOO - , SO3 - NO3 - 5CN - and / or Cl - etc.), and / or - Salt or electrolyte, preferably with a pH of about 7, Na + , K + Li + Ca 2+ Mg 2+ Cl - F - , HCOO - , SO3 - NO3 - 5CN - CO3 2- .

[0101] Apparatus 1, when it is a predetermined electrolyte medium 3 and gaseous dihydrogen 4 within a predetermined pressure range, has at least one pair M y / M x The oxidation-reduction potential E(M) y / M x ) and against H + / H2 oxidation-reduction potential E(H + The device is configured such that the absolute potential difference |ΔE| with (H2) is 0.6V or less. In a battery, the potential difference between the redox potential of the anode's redox pair and the redox potential of the cathode's redox pair must be as high as possible. A high potential difference is required for a battery to function, and is usually higher than 1 volt. Therefore, unlike a battery, according to this invention, |ΔE| is as small as possible. Reducing |ΔE| reduces the energy required to store or release gaseous dihydrogen, thus increasing the efficiency of the device 1. Furthermore, the charge-discharge rate (C rate) of the device 1 is lower compared to the typical charge-discharge rate of energy storage batteries. Typically, the charge-discharge rate of the device 1 is 0.05~0.001C, while the charge-discharge rate of a battery is 0.1~5C. The current density of this device is lower compared to fuel cells or electrolytic cells for water splitting. Typically, the current density of the device 1 is 0.5~100mA / cm². 2 While current densities of 100-2000 mA / cm² are used, fuel cells or electrolytic cells for water splitting use 100-2000 mA / cm². 2 This is the current density. Furthermore, this device neither injects nor generates oxygen.

[0102] The apparatus 1 further includes connecting means 5 suitable for connecting the sealed chamber 2 to an external gas circuit 6.

[0103] The apparatus 1 further includes two current collectors 10, each connected to at least one anode 7 and at least one cathode 8. The two current collectors 10 form and / or connect to two respective connectors 13, which are located outside the sealed chamber 4 and are intended to be connected to the current generator 11.

[0104] In a favorable embodiment, hydrogen has at least one redox pair M y / Mx Reduction state M x If the electrolyte medium 3 is stored through or in this reduced state and is liquid, the apparatus 1 further includes means 14 configured to remove the electrolyte medium 3 from the sealed chamber 2, and / or at least one first electrode 7 is configured to be removed from the electrolyte medium in the sealed chamber 2. In this way, there is no contact between the electrolyte medium 3 and at least one first electrode 7, and at least one redox pair M y / M x Reduction state M x This further prevents the dihydrogen from spontaneously reacting with the electrolyte medium 3. At least one first electrode 7 is also configured to be reintroduced into the electrolyte medium in the sealed chamber 2, and means 14 is also configured to reintroduce the electrolyte medium 3 into the sealed chamber 3 when it is necessary to release dihydrogen from the apparatus 1. In a non-limiting description, means 14 includes supply means such as a pump and connecting means suitable for connecting the sealed chamber to a liquid circuit and to a liquid tank for temporarily storing the electrolyte medium 3. In the absence of electrolyte, the sealed chamber 2 is within a predetermined pressure range, preferably 2 × 10⁻⁶ 3 ~5×10 6 Pascals, preferably 1 × 10⁻⁶ 6 It is maintained in a state where it is filled with dihydrogen at Pascal's gauge pressure.

[0105] At least one redox pair M y / M x Reduction state M x For long-term storage of hydrogen via [a specific method], we propose an alternative to the above embodiment: at least one redox pair M y / M x Reduction state M x To further prevent spontaneous reaction with gaseous dioxygen, an inert gas may be injected into the sealed chamber 3 through the gas circuit 6, or a supply means 9 may be provided to remove the inert gas from the sealed chamber 3. After removing the electrolyte medium 3 from the sealed chamber 3 using means 14, the gauge pressure of the inert gas in the sealed chamber 3 is 2 × 10⁻⁶. 3 ~5×10 6 Pascals, preferably 1 × 10⁻⁶ 6An inert gas is injected into the sealed chamber until it reaches a Pascal. This function prevents the diffusion of gaseous dihydrogen within the sealed chamber 3. When it is necessary to release dihydrogen, the inert gas is removed by the supply means 9, and then the electrolyte medium 3 is reintroduced into the sealed chamber 3, thereby allowing the electrolyte medium 3 to come into contact with electrodes 7 and 8 again and release dihydrogen from the apparatus 1. The inert gas may be supplied by an external means or stored in another tank 15 connected to the supply means 9.

[0106] As a non-limiting example, the gaseous dihydrogen 4 sent to the sealed chamber 2 may be produced in a nearby water splitting electrolysis unit supplied with renewable energy (solar panels or wind turbines). Advantageously, the gaseous dihydrogen 4 produced by electrolysis may be temporarily stored in a gas tank 12 before being injected into the sealed chamber 2.

[0107] Redox vs. M y / M x Based on calculations using several metal elements and organic molecules, the approximate total energy required to store and release 37.3 grams (gr) of gaseous dihydrogen according to the present invention is the redox ratio M y / M x It was found that the amount varies from 50 to 250 Wh, which is 10 to 45% of the available energy stored in device 1. To store 1000 kWh, the volume of sealed chamber 2 is approximately 2 m³. 3 In contrast, the volume required to store the same amount of energy in a bottle rack equipped with 300 bar compressed hydrogen or lithium batteries is approximately 8 m³. 3 That is the case.

[0108] As is known to those skilled in the art, the redox potential of a redox pair can change depending on the pH, temperature, and pressure of the gas in equilibrium with the electrolyte medium in which the redox pair is in contact and / or immersed.

[0109] For example, redox pair H + / H2 oxidation-reduction potential E(H +The voltage (H2) changes from 0 volts relative to the standard hydrogen electrode (SHE) at pH=0 to -0.83 volts relative to the SHE at pH=14.

[0110] Preferably, at least one pair M y / M x The oxidation-reduction potential E(M) y / M x ) so that the voltage is as close as possible to 0 volts at the reversible hydrogen electrode (RHE), at least one pair M y / M x Select the appropriate option. In other words, this potential must be close to 0 volts on the SHE reference at pH=0, or close to -0.83V on the SHE reference at pH=14.

[0111] As a non-limiting example, in a preferred embodiment, the electrolyte medium 3 is an aqueous electrolyte solution 3. In this case, the redox reaction occurring at the second electrode 8 can be described according to Formula 1 when the pH of the aqueous electrolyte solution 3 is neutral or acidic, or according to the following Formula 3 when the pH of the aqueous electrolyte solution 3 is neutral or basic. JPEG2026536524000013.jpg9170

[0112] Therefore, aqueous electrolyte solution 3 is preferably one of the following: - High pH, ​​typically 10 or higher, more preferably 11 or higher, even more preferably 12 or higher, most preferably 13 or higher, and most preferably 14 or higher, or - Low pH, typically 4 or less, more preferably 3 or less, even more preferably 2 or less, most preferably 1 or less, and even more preferably 0 or less, and / or - Buffered, that is: • High concentration, typically 1 mol / L or more, more preferably 1.25 or more, even more preferably 1.5 or more, most preferably 1.75 or more, even more preferably 2 or more, particularly advantageously 2.25 or more, even more particularly advantageously 2.5 or more, even more particularly advantageously 2.75 or more, and particularly preferably 3 mol / L of acid, such as hydrohalic acid, sulfuric acid or nitric acid, or buffered with a base, such as potassium hydroxide or sodium hydroxide, or A buffer solution containing a weak acid and its conjugate base, or a weak base and its conjugate acid.

[0113] The present invention also describes a method for electrochemically and reversibly storing dihydrogen in an apparatus 1 according to the present invention. This method includes the step of storing gaseous dihydrogen 4 in the apparatus 1. This storage step consists of supplying gaseous dihydrogen 4 using a supply means 9, for example including a pump 9, until the pressure of gaseous dihydrogen in a sealed chamber 2 reaches a predetermined pressure range or value. The gaseous dihydrogen 4 is injected into the sealed chamber 2 via a connecting means 5. The gaseous dihydrogen 4 may come from a water splitting electrolytic cell or a gas tank 12. The storage step further involves passing an electric current through at least one first electrode 7 using a current generator 11 to generate at least one oxidation-reduction pair M y / M x oxidized state M y From reduced state M x This includes reducing the gas to a certain state and oxidizing the dissolved gaseous dihydrogen 4 at at least one second electrode 8 to form a proton.

[0114] This method further includes a step of releasing gaseous dihydrogen 4 from apparatus 1. This release step involves at least one redox pair M at the first electrode 7. y / M x Reduced state M x From oxidation state M y The process involves oxidizing the material, reducing the protons by passing an electric current through at least one of the second electrodes 8, and forming gaseous dihydrogen 4 at at least one of the second electrodes 8. The discharge step further includes discharging the gaseous dihydrogen 4 from the sealed chamber 2 through the connecting means 5.

[0115] The method further includes a step of monitoring and / or controlling the pressure of gaseous dihydrogen 4 in a sealed chamber 2 by means of monitoring and / or controlling the pressure of gaseous dihydrogen 4. Typically, the gauge pressure of gaseous dihydrogen 4 is 2 × 10⁻⁶ at ambient temperature. 3 ~5×10 6 Pascals, preferably 1 × 10⁻⁶ 6 It's Pascal.

[0116] In the first embodiment, referring to Figures 2 to 7, results obtained from an apparatus 1 including one first electrode 7 and one second electrode 8 are shown. Apparatus 1 is a redox pair M consisting of iron as a chemical element. y / M x It contains one of these. Iron was chosen because it is inexpensive and abundant. The oxidation-reduction pair M used for storing gaseous dihydrogen according to this embodiment y / M x Fe (固体) / Fe(OH) 2(固体) The first electrode 7 is made from a graphite rod sold by Sigma-Aldrich®, coated with carbonyl iron particles with an iron content of over 97%. The graphite rod coated with carbonyl iron particles is impregnated with paraffin. The paraffin is used here to eliminate any trace of gaseous oxygen. In fact, this method of reversibly storing dihydrogen is carried out in the absence of gaseous oxygen, and no oxygen is generated during the dihydrogen storage process. The graphite rod is rubbed against paper to which particles of the material under test are attached. This effectively fixes the particles to the graphite surface. According to the first embodiment, the apparatus is configured for electrochemical research. The first electrode 7 is placed at the interface between the electrolyte medium 3 and the dihydrogen atmosphere 4, and the small surface area (several mm²) of the first electrode 7 is used. 2Only the first electrode 8 is immersed in the electrolyte medium 3. Therefore, the apparatus 1 according to the first embodiment is not configured to maximize the dihydrogen storage capacity. The second electrode 8 is made from a 2 cm × 2 cm graphite felt piece coated with platinum (Pt) nanoparticles. The Pt nanoparticles are deposited by repeating the potential of the graphite felt from 0 to -1 V relative to Ag / AgCl at 20 mV / s for 30 cycles in a solution containing 0.1 M KCl and 1 mM K2PtCl6. After washing with distilled water and drying, the obtained second electrode 8 is extremely efficient at converting H2 to protons and protons to H2 in the range of low experimental currents. The second electrode 8 was used as a reversible hydrogen electrode (RHE) in the presence of H2. All potentials measured with the first electrode 7 were obtained relative to the RHE.

[0117] Referring to Figure 2A, the cyclic voltammetry curve measured using carbonyl iron in 1M KOH under a dihydrogen atmosphere is shown. Several peaks are observed. Each peak corresponds to a different electrochemical reaction, such as the following reactions. - Fe+2OH - →[Fe(OH)2]ads+2e - - Fe+2OH - →Fe(OH)2+2e - - Fe(OH)2+OH - →FeOOH+H2O+e - - 3Fe(OH)2+OH - →Fe3O 4. 4H2O+2e - - FeOOH + H2O + e - →Fe(OH)2+OH - - Fe3O4.4H2O+2e - →3Fe(OH)2+2OH - - Fe(OH)2+2e - →Fe+2OH - - [Fe(OH)2]ads+2e- →Fe+2OH - - 2H2O + 2e - →H2+2OH - or 2H + +2e - →H2

[0118] Although there are slight differences in peak position and relative peak intensity, as shown in Figure 2B, very similar electrochemical signals can be observed even when using other types of iron, such as Fe3O4 (metallic purity 99.997%, Puratronic, Alfa), in 1M KOH under a dihydrogen atmosphere.

[0119] Figure 2C shows the results when using carbonyl iron with 25% KOH as the electrolyte under a dihydrogen atmosphere. As the conditions change, the relative intensity or exact position of different redox signals changes slightly.

[0120] Figure 2D shows the results for carbonyl iron obtained under a dihydrogen atmosphere, using 25% KOH as the electrolyte medium and adding Na2S as an additive to the electrolyte medium. Assuming that sulfur species are adsorbed on the metal surface, the hydrogen evolution reaction is inhibited within a predetermined potential range.

[0121] Figure 3 shows the Coulomb efficiency of device 1 after 100 charge-discharge cycles. A Coulomb efficiency of 90-100% was obtained. The charge-discharge cycle according to the present invention should not be interpreted as a charge-discharge cycle of a battery. According to the present invention, the efficiency of the charge-discharge cycle, which can be evaluated by Coulomb efficiency, indicates or characterizes the reversibility and / or efficiency of dihydrogen storage / release. Charging is performed in an oxidation-reduction ratio of M y / M x Oxidation state M y This corresponds to the dihydrogen storage process in the reduction process, while the discharge is the oxidation-reduction versus M y / M x Reduction state M x This corresponds to the dihydrogen release step in the oxidation process.

[0122] Other elements / compounds are redox-matched M y / M x To demonstrate its suitability for this purpose, Figure 4A shows the cyclic voltammetry curve obtained when bismuth particles (100 mesh, 99% trace metal basis, manufactured by Sigma-Aldrich) were used in 1M KOH under a dihydrogen atmosphere. Two distinct peaks can be observed: one for oxidation around 0.55 V and the other for reduction around 0.2 V.

[0123] Referring to Figure 4B, gaseous dihydrogen storage by metal hydride formation using lanthanum pentanickel (LaNi5, hydrogen storage grade from Sigma-Aldrich) is shown, and indeed, under experimental conditions (KOH 1M, H2 atmosphere), a reversible redox signal centered around 0 volts relative to RHE was observed.

[0124] Antimony (Fluka powder) and zinc (bioMerieuxSA powder) are subjected to a redox reaction. y / M x Examples of its use are shown in Figures 5A and 5B, respectively. Reactivity suitable for dihydrogen storage was observed. With electrolyte medium 3, i.e., 1M KOH under an H2 atmosphere, the stability of the redox reaction was limited compared to other compounds such as carbonyl iron or bismuth. The composition of electrolyte medium 3 can be modified to better control reactions at metal interfaces.

[0125] Insoluble organic molecules or insoluble organic polymers are subjected to oxidation-reduction reactions. y / M x An example of its use is shown in Figure 5C. The first electrode 7 is composed of anthraquinone (Fluka, 99% purity) adsorbed onto Ketjenbrak particles (FuelCellStore's EC-300J). As can be seen, a clear reversible electrochemical reaction was observed at 0.23V relative to the RHE standard.

[0126] Figure 6 shows bismuth in redox pairs. y / M xThis shows the Coulomb efficiency of device 1 after 100 charge-discharge cycles using it as a charger. Bismuth exhibits a clear charge-discharge process. The cycles were mainly between 0.25 and 0.5 volts, and the Coulomb efficiency was approximately 80-100%.

[0127] Figures 7A, 7B, and 7C show charge-discharge cycle experiments with antimony, LaNi5, and anthraquinone, respectively. Each system has its own unique redox potential range: anthraquinone is approximately 0.25 volts, LaNi5 is approximately 0 volts, and antimony is approximately 0.1–0.2 volts.

[0128] The results shown in the first embodiment indicate that the potential difference between the charging potential and the discharging potential can be reduced to approximately 0.100V. Assuming that 37.3 grams (gr) of dihydrogen can be stored at 1000 ampere-hours (Ah), the available energy is approximately 560 watt-hours (Wh) (here, we consider the widely accepted value of 15 kWh per 1 kg of H2). The energy required for the entire H2 storage and release cycle is 100 Wh, which is less than 20% of the total available energy. This needs to be compared to the energy required for pressurizing hydrogen (7% at 200 bar, 15% at 700 bar) or liquefaction (35% at industrial scale, and more at smaller scales). Conversion to ammonia requires 15-30% of the initial energy, and liquid organic hydrogen carriers require 35-40%. Furthermore, these energy cost estimates are typically for large-scale industrial facilities.

[0129] In the second embodiment, referring to Figures 8 and 9, results obtained from an apparatus 1 including one first electrode 7 and one second electrode 8 are presented. Apparatus 1 is a single redox pair M consisting of iron as a chemical element. y / M x It includes the oxidation-reduction pair M used for storing gaseous dihydrogen according to this embodiment. y / M x Fe (固体) / Fe(OH) 2(固体)The first electrode 7 is made of stainless steel mesh coated with carbonyl iron particles. This electrode is obtained by mixing 1 gram of carbonyl iron particles with an iron content of over 97%, sold by Sigma-Aldrich®, with 70 milligrams of polyethylene with an average molecular weight of approximately 4000, also sold by Sigma®. This mixture is applied to a 316L stainless steel mesh by pressing at 140°C. The working area (or immersion area) of the first electrode 7 is approximately 1 cm². 2 The second electrode 8 is a platinum mesh (6cm x 4cm) connected to a platinum wire with a diameter of 1mm. The potential of the first electrode 7 was controlled using a reference electrode, which is a third electrode of Hg / HgO (KOH 1M). Unlike the first embodiment, gaseous dihydrogen was not injected into the sealed chamber 2. The sealed chamber 2 was under an inert atmosphere with a continuous flow of N2. The gas leaving the sealed chamber 2 was continuously analyzed using an online H2 sensor positioned to measure the gaseous dihydrogen released from the first electrode 7 within the sealed chamber 2. The aqueous electrolyte solution 3 consisted of KOH 1M or 25% KOH (by volume), with or without the addition of 0.01M Na2S to the water.

[0130] According to the second embodiment, in order to demonstrate hydrogen release upon request, redox pair M y / M x The amount used was increased. Unlike the first embodiment, in which only a small surface of the first electrode 7 was immersed in the electrolyte medium 3, in the second embodiment, the majority of the effective surface of the first electrode 7 is immersed in the electrolyte medium 3. Therefore, the apparatus 1 according to the second embodiment is configured to show an improvement in dihydrogen storage capacity.

[0131] Figure 8A shows the cyclic voltammetry curve of apparatus 1 at 0.1 mV / s. The redox pair M observed in Figure 2A y / M xA typical redox signal with a small amount of hydrogen is similarly observed in Figure 8A. Figure 8B shows the current values ​​monitored over time from the values ​​measured by voltammetry. The current increases and decreases periodically over time, and at the same time the potential fluctuates from -1.15V to -0.7V (vs. Hg / HgO). When the current is greater than 0A, dihydrogen needs to be released, and when the current is less than 0A, dihydrogen needs to be stored. In fact, when the current is greater than 0A, hydrogen is detected periodically. Figure 8C shows the reaction of the gaseous dihydrogen sensor, which is proportional to the amount of gaseous dihydrogen released from apparatus 1 over time.

[0132] As shown in Figure 9, applying a step current over a set period of time makes the controlled release of dihydrogen even clearer. When carbonyl iron is oxidized with a current of 10 mA, dihydrogen is detected. When oxidation is stopped, the sensor's response rapidly decreases.

[0133] When the electrolyte medium 3 was separated from the electrode in a sealed chamber and a dihydrogen atmosphere was introduced, the electrode 7 was found to be stable for at least 6 months with no visible signs of corrosion. This result indicates that, if the device is operated properly under optimal conditions, it can achieve the necessary stability for seasonal storage, i.e., over several months.

[0134] The present invention is not limited to the embodiments described above, and many modifications may be made within the scope of the present invention.

[0135] Therefore, possible alternative configurations that combine the above embodiments include the following: - At least one redox pair M Y / M x It is composed of metals such as antimony, copper, lead, zinc, tungsten or cadmium, and / or metal hydrides such as LaNi5, and / or insoluble organic molecules such as anthraquinone or insoluble redox polymers such as polyaniline, and / or - Electrolyte medium 3 includes a protic medium and / or - Electrolyte medium 3 contains water and / or is a mixture of water and an organic medium and / or - Electrolyte medium 3 does not contain water and contains at least one redox pair M y / M x The redox potential of is higher than the reduction potential of the electrolyte medium, lower than the oxidation potential of the electrolyte medium, and / or - The electrolyte medium contains water and at least one redox pair M y / M x The oxidation-reduction potential of is lower than the oxidation potential of water, and is greater than or less than the reduction potential of water, and / or - Electrolyte solution 3 is • At least one redox pair M Y / M x The spontaneous reaction between and the electrolytic aqueous solution 3, and / or • Gaseous dihydrogen 4 and at least one redox pair M y / M x a natural reaction It contains one or more additives to limit or suppress [something].

Claims

1. An apparatus (1) for electrochemically and reversibly storing dihydrogen, wherein the apparatus is - A sealed chamber (2) intended to receive an electrolyte medium (3) and gaseous dihydrogen (4), - Connection means (5) suitable for connecting the sealed chamber to the gas circuit (6), - At least one first electrode (7) and at least one second electrode (8) arranged within the sealed chamber. Includes, The at least one second electrode is suitable for oxidizing gaseous dihydrogen dissolved in an electrolyte medium to form protons, and for reducing the protons to form gaseous dihydrogen, according to formula 1. The at least one first electrode is insoluble in the electrolyte medium and contains at least one redox pair M ｙ / M ｘ The at least one redox pair is configured to have at least two oxidation states according to formula 2, and oxidation state M ｙ From reduced state M ｘ Suitable for reduction to, or vice versa, In the formula, x and y are oxidation numbers. When the electrolyte medium is a predetermined type and the gaseous dihydrogen is within a predetermined pressure range, the ratio to H ＋ / H ２ The redox potential of and at least one pair M ｙ / M ｘ The absolute potential difference |ΔE| with the oxidation-reduction potential is 0.6V or less. Device (1).

2. The apparatus (1) according to claim 1, wherein the electrolyte medium (3) includes a protic medium.

3. The apparatus (1) according to claim 1 or 2, wherein the electrolyte medium (3) contains water.

4. The electrolyte medium (3) is - Unlike water, said at least one redox couple M ｙ / M ｘ has said redox potential higher than the reduction potential of the electrolyte medium and lower than the oxidation potential of the electrolyte medium, or - Contains water and the at least one oxidation-reduction pair M ｙ / M ｘ The aforementioned oxidation-reduction potential is lower than the oxidation potential of water, and is equal to or less than the reduction potential of water. The apparatus (1) according to claim 1 or 2.

5. The electrolyte medium (3) is - The at least one redox pair M ｙ / M ｘ and the spontaneous reaction between the electrolyte medium and / or - The gaseous dihydrogen and the at least one oxidation-reduction pair M ｙ / M ｘ a natural reaction The apparatus according to any one of claims 1 to 4, comprising one or more additives for limiting or suppressing.

6. The electrolyte medium (3) intended to be received in the sealed chamber (2) is a liquid, - The apparatus includes means (14) configured to remove the electrolyte medium and reintroduce it into the sealed chamber, and / or - The at least one first electrode (7) is configured to be removed from the electrolyte in the sealed chamber and reintroduced into the electrolyte in the sealed chamber. The apparatus according to any one of claims 1 to 5.

7. The at least one redox pair M ｙ / M ｘ This includes metals such as iron, zinc, tungsten, cadmium, copper, bismuth, antimony, and lead, as well as LaNi. ５ The apparatus (1) according to any one of claims 1 to 6, comprising metal hydrides such as, organic molecules such as anthraquinones and / or redox polymers such as polyaniline.

8. The apparatus (1) according to any one of claims 1 to 7, wherein the at least one second electrode (8) includes a catalyst or combination of catalysts suitable for oxidizing gaseous dihydrogen dissolved in the electrolyte medium (3) to form a proton, and reducing the proton to form gaseous dihydrogen, according to formula 1.

9. The apparatus (1) according to any one of claims 1 to 8, further comprising a supply means (9) configured to inject gaseous dihydrogen (4) into the sealed chamber (2) or remove gaseous dihydrogen from the sealed chamber (2) via the gas circuit (6) so as to maintain the pressure of gaseous dihydrogen in the sealed chamber within a predetermined pressure range.

10. The apparatus (1) according to any one of claims 1 to 9, further comprising two current collectors (10) connected to the at least one first electrode (7) and the at least one second electrode (8), respectively.

11. The apparatus (1) according to any one of claims 1 to 10, further comprising a current generator (11) configured to conduct current between the at least one first electrode (7) and the at least one second electrode (8).

12. The apparatus (1) according to any one of claims 1 to 11, further comprising means for monitoring and / or controlling the pressure of gaseous dihydrogen (4) in the sealed chamber (2).

13. A method for electrochemically and reversibly storing dihydrogen in an apparatus (1) according to any one of claims 1 to 12, the method comprising the step of storing gaseous dihydrogen (4) in the apparatus, the storage step being - A step of supplying gaseous dihydrogen to the sealed chamber (2) of the apparatus by supply means (9) until a predetermined pressure range is reached, wherein the apparatus includes at least one second electrode (8) and at least one first electrode (7), and includes an electrolyte medium (3), and the gaseous dihydrogen is injected through the sealing chamber connecting means (5) which connects the sealed chamber to the gas circuit (6), - By injecting current into at least one first electrode (7) using the current generator (11), at least one redox pair M that is insoluble in the electrolyte medium of at least one first electrode (7) is generated. ｙ / M ｘ Oxidation state M ｙ From reduced state M ｘ The process involves reducing the gas to a proton by oxidizing the dissolved gaseous dihydrogen at at least one second electrode (8). It consists of, The case where the H2H ＋ / H ２ The oxidation-reduction potential and the at least one pair M ｙ / M ｘ The absolute potential difference |ΔE| with the oxidation-reduction potential is 0.6V or less. method.

14. The apparatus (1) further includes a step of releasing gaseous dihydrogen (4), the release step being: - At least one first electrode (7) the at least one redox pair M ｙ / M ｘ Reduced state M ｘ From oxidation state M ｙ By oxidizing it and injecting a current into the at least one second electrode (8), the proton is reduced at the at least one second electrode to form gaseous dihydrogen, - To discharge the gaseous dihydrogen from the sealed chamber (2) via the connecting means (5) The method according to claim 13, comprising:

15. Means for monitoring and / or controlling the pressure of gaseous dihydrogen (4) in the sealed chamber (2) are used to ensure that the pressure of gaseous dihydrogen is equal to a gauge pressure of 1 × 10⁻⁶ at ambient temperature. ６ The method according to claim 13 or 14, further comprising the step of monitoring and / or controlling so that the result is less than or equal to a Pascal.

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