WO2008129182A2

WO2008129182A2 - Hydrogen storing method and unit

Info

Publication number: WO2008129182A2
Application number: PCT/FR2008/050379
Authority: WO
Inventors: Arash Mofakhami
Original assignee: Ceram Hyd
Priority date: 2007-03-06
Filing date: 2008-03-06
Publication date: 2008-10-30
Also published as: FR2913417B1; EP2129621A2; WO2008129182A3; CN101679023A; US20100089767A1; FR2913417A1; AU2008240532A1; JP2010520145A; ZA200906056B; CA2679788A1; AU2008240532B2

Abstract

The invention relates to a method for storing hydrogen and for producing hydrogen in which, for storing hydrogen, a unit (2) having: a cation donor, particularly of H+ ions, an anode (20), a cathode capable of storing atomic and/or molecular (22) hydrogen, a wall (21) permeable to ions, having an electrical non conducting but ionic conducting material, between the cathode and the cation donor, is subjected to an electric field allowing the formation, at least at the cathode and electrical non conducting material interface, of atomic and/or molecular hydrogen and storing said hydrogen at least in the cathode, and in which, to restitute hydrogen gas, the cathode is heated and/or depressed.

Description

Hydrogen storage process and unit

The present invention relates to the storage of hydrogen and more particularly the storage of hydrogen produced electrochemically, and the return of the stored hydrogen. International application WO 2006/003328 discloses a process for producing and storing hydrogen.

There is a need to benefit from a storage unit for storing a relatively large quantity of hydrogen capable of returning it outside the unit in the form of molecular hydrogen. According to one of its aspects, the subject of the invention is therefore a process for producing and storing hydrogen, in which, for storing hydrogen, a unit comprising: a cation donor, in particular H ions; ⁺ , - an anode, - a cathode capable of storing atomic and / or molecular hydrogen, an ion-permeable wall, comprising an electrically non-conductive but ionically conductive material between the cathode and the cation donor, is subjected to a an electric field enabling the formation, at least at the interface of the cathode and of the electrically non-conductive material, of atomic and / or molecular hydrogen and its storage within the at least one cathode, and in which, in order to restore the hydrogen gas, the cathode is heated and / or depressed.

By "storing" it is necessary to understand a chemical or physical absorption or adsorption, at the atomic level and / or in the porosities of the material.

The cathode may comprise a hydrurable material. By "interface" between the cathode and the electrically non-conductive material, it should be understood that there is a phenomenon of molecular contact between the cathode and the electrically nonconductive material. Between the electrically non-conductive material and the cathode, the interface is made to ensure the transformation of a hydrogen ion into a hydrogen atom on the surface of the cathode, the cathode being configured to absorb it immediately. . By "non-conductive electrical material" is meant a material whose electrical conductivity is low enough not to be detrimental to cationic conduction. The process according to the invention makes it possible to store the hydrogen during its production and to return it at will, according to the needs.

Storage can be performed without causing degradation at the cathode.

The present invention can find application in many fields where hydrogen gas is needed to produce energy, for example vehicles, electronic devices or electricity generators. The invention also applies to the intermittent storage of any form of renewable energy, for example of wind, driving tide or solar.

The ion-permeable wall may have a water permeability of less than 5% of the mass of hydrogen produced.

The cathode may contain less than 5% by weight of water.

The ion-permeable wall may have zero water permeability, measured under normal conditions of temperature and pressure, with liquid water, or even in the form of steam, at a temperature of less than 900 ^° C. and a difference pressure on both sides of the membrane not exceeding 4 bar.

The total impermeability of the wall during production and storage can make it possible to ensure the storage within the cathode of the atomic and / or molecular hydrogen formed. The hydrogen adsorption required for this purpose may depend on the nature of the cathode. Indeed, the presence of water in the cathode may risk preventing the establishment of molecular contact within the cathode, thus preventing the establishment of a satisfactory electrical conduction, and thus preventing the formation of hydrogen in the cathode. cathode or at the interface. On the other hand, the presence of water at the interface of the cathode and the proton exchange membrane may be of no consequence on the system. Indeed, the water behaves as the continuity of the wall permeable to ions because of its ionic conduction power. Moreover, since near the cathode the medium is reducing due to the presence of hydrogen, the presence of water is not a problem for storage.

The anode may be made of any electrically conductive material compatible with the H ⁺ ion donor, for example platinum, graphite, a thin layer of a mixture of RuO ₂ , IrO ₂ or RuO ₂ , IrO ₂ and TiO ₂ or RuO ₂ , IrO ₂ and SnO ₂ lined with a porous titanium plate (30 to 50% for example) or a conductive polymer, among others. The thin layer may have a thickness of between 5 microns and 20 microns, for example about 10 microns. The anode may be in contact with the electrically nonconductive material.

The cathode may have a solid, liquid or powder form; a powdery form can facilitate the manufacture of the unit with very different shapes.

The cathode may comprise an intermetallic compound, in particular chosen from complex interstitial or metal hydrides, for example chosen from the following list: of type AB5 (A and B being metals), for example LaNi ₅ , the lava phases

(Zr, Ti) (Mn, V, Cr, Ni) ₂ , for example ZrMn ₂ or TiMn ₂ , Mg, TiFe, Mg ₂ Ni, vanadium-based solid cube solutions, BaReHg (the formula corresponding to hydridized state), Mg ₂ FeH ₆ (the formula corresponding to the hydride state), NaAlH ₄ (the formula corresponding to the hydrided state), LiBH ₄ (the formula corresponding to the hydrided state), and all their compounds, derivatives or their alloys.

The cathode may be embedded in a mass of boron nitride, the periphery of this mass of boron nitride constituting the electrically nonconductive material. The electrode may comprise for example a metal foam or any conductive and hydrurable material, embedded in a mass of boron nitride.

The electrically non-conductive material may comprise a ceramic, for example comprising hexagonal boron nitride, preferably activated by an acidic solution in an electric field, lithium nitride, boric acid, an ionic conductive polymer, and more generally any ion exchange material. The electrically non-conductive material may be chosen from ion exchange ceramics developed for PEMFC or PCFC cells.

The non-conductive electrical material may for example comprise turbostratic boron nitride, that is to say whose crystallization planes may be slightly offset with respect to the theoretical crystallization position, for example hexagonal crystallization of boron nitride, which leads to a poorer maintenance of the plans between them, the latter being further apart.

The electrically nonconductive material may comprise hexagonal boron nitride grains contiguous to each other, for example grains having a size of the order of 100 μm, or even of a nanometric size. The boron nitride grains may be oriented preferably not all parallel to the wall, but for example perpendicularly, so as to ensure better mechanical strength, or heterogeneously, to ensure better proton conduction. The boron nitride may be in the form of grains, for example of average size of the order of 7 to 11 microns. The mass proportion of boron nitride in the material may be between 5% and 100%, for example up to 70%. The wall may be entirely made of high pressure sintered boron nitride powder. Alternatively, it may comprise boron nitride and a binder, being manufactured by a HIP (hot isostatic pressure) process.

The electrically non-conductive material may comprise percolated boron nitride grains, for example held together by a compound, for example a compound of the following list: nickel, boron oxide, calcium borate, ethyl cellulose, acid boric, Polyvinyl alcohol, vinylcaprolactam, PTFE (Teflon ^®), Poly ethyl sulfone sulfone.

The electrically nonconductive material may be formed by boron nitride inserted into a binder, for example boric acid or a polymer membrane, which can provide very good proton conductivity to the electrically non-conductive material. The polymer may for example be PVA (polyvinyl alcohol),

Vinylcaprolactam, PTFE (Tefion ^® ), Polyether sulfone sulfone.

The polymer, for example PVA, can be used to plug the porosities present in the boron nitride. The addition of polymer may for example be carried out under vacuum, so that the latter is sucked into the pores of the boron nitride. The electrically nonconductive material can be obtained by the following method.

Boron nitride grains are mixed with a polymer binder in liquid form, this mixture being poured onto a substrate, then heated to a temperature sufficient to cause calcination of the binder, for example at a temperature of the order of

600 or 700 ⁰ C, so that the grains of boron nitride are percolated between them on the substrate.

In a further step, the result obtained is heated at a temperature of between 800 and 1700 ^° C., or even between 1000 and 1500 ^° C. under a neutral atmosphere, for example nitrogen or argon, causing the grains to sinter together. .

Finally, in a further step, the substrate is removed and a rigid boron nitride membrane composed of sintered grains is obtained.

The substrate may for example comprise a thin woven, made for example of Nylon ^® , PolyEthylEtherKetone, Ethylene Tetrafluoroethylene, Polyethylene terephthalate or Polyester. In the foregoing, the edge nitride may have been previously activated or activated during or at the end of the process of manufacturing the electrically non-conductive material.

By activation of boron nitride is meant a process for promoting proton conduction in boron nitride.

Boron nitride may for example be activated in an acid solution while being subjected to an electric field.

Boron nitride can still be activated in a sodium hydroxide solution, with or without the application of an electric field. In yet another process, the boron nitride can be activated by being dipped in a solution, for example water, in the presence of iron, for example an iron gate, and under application of an electric field.

The use of boron nitride in powder form can facilitate the activation of the latter. The boron nitride may be activated in its powder form before insertion into a binder, for example into a polymer, or after insertion into this binder, for example depending on the binder used.

In the process described above, the boron nitride grains can be activated before they are inserted into the polymeric binder or after the sintering of the grains. In case of sintering, the activation can be done at the end of the process, to avoid the risk that it is destroyed by sintering.

The ion-permeable wall may comprise one or more layers of different materials, at least one of which may exert a cationic conductor function. Between the layer having this function and the electrolyte, the wall may comprise, for example, a porous layer having a support function.

The ion-permeable wall may at least partially, more completely, cover the cathode, especially at least on its face facing the anode.

The electrically non-conductive material of the ion-permeable wall can be used to prevent, in an exemplary embodiment, any contact between the cathode and the cation donor.

Moreover, the electrically non-conductive material is preferably impervious to gaseous hydrogen, so as to make it easier, during the restitution of hydrogen gas, the evacuation of it to an outlet of hydrogen gas and not to the donor of cations.

The cation donor can be an electrolyte, for example an aqueous acidic solution comprising for example at least one of the compounds of the following list: sulfuric acid, hydrochloric acid, weak acid, or weak acid salts.

The cation donor can be liquid, as mentioned above, or alternatively be solid, gaseous or in the form of plasma.

The cation donor can be circulated in the unit, for example by means of a pump or mobile set in motion. This circulation may remain internal to the unit or may take place partially outside the unit, for example in a charging device of the unit. Such a circulation may allow for example to avoid the formation of a H ⁺ ion gradient in the unit, given that the unit can consume water to ensure the formation of hydrogen. In addition, the circulation of the cation donor may make it possible to maintain the characteristics of the exchange surface around the anode and the cathode substantially constant.

The voltage applied between the anode and the cathode during the production of hydrogen may be for example between 1 and 3000 volts, better between 1.24 and 200 volts, preferably between 1.24 and 4 volts.

The cathode may be heated to restore the hydrogen gas, for example at a temperature above 30 ^° C., more preferably 50 ^° C., for example between 70 ° and 350 ^° C., the temperature being able to be chosen according to the materials.

The heating can take place after evacuation of the electrolyte, this evacuation being able to take place towards the recharging device. Alternatively, the cation donor is not removed for heating to release hydrogen. The unit can also be heated to a temperature lower than that producing destocking, during the hydrogen production and storage phase, in order to improve the latter.

The heating of the cathode can advantageously be done in a controlled manner, for example to act precisely on the amount of hydrogen gas released. Alternatively or additionally, the unit, and in particular the cathode, can be depressed to facilitate the extraction of hydrogen gas.

The heating can be caused by Joule effect during the circulation of an electric current, for example in a conductor integrated in the unit, for example extending within the cathode. Heating can still be done by circulation of a hot fluid.

Atomic and / or molecular hydrogen can also be stored, if desired, in the electrically non-conductive material of the ion-permeable wall. The atomic or molecular hydrogen produced within the unit can be stored in the cathode only or, alternatively, both in the cathode and in the electrically nonconductive material.

Furthermore, the hydrogen can be stored in the cathode in atomic and / or molecular form, depending on the choice in particular of the material forming the cathode. Hydrogen gas leaving the cathode can be collected for use in a fuel cell and / or fuel or reagent.

The invention further relates, independently or in combination with the foregoing, to a unit for storing and recovering hydrogen, comprising:

an anode, a cathode capable of storing atomic and / or molecular hydrogen, a cation donor, in particular of ions H ⁺ , an ion-permeable wall comprising an electrically nonconductive but ionically conductive material between the cathode and the cation donor, optionally a cathode heating element, - an electrical connector for electrically feeding the anode and the cathode to create between them an electric field allowing the formation of atomic and / or molecular hydrogen at least within the cathode and its storage at least in the cathode, the unit being arranged to collect the hydrogen gas released by the cathode at least during the heating thereof, the unit further comprising: a fluidic connector allowing to channel the hydrogen gas thus released towards the outside of the unit.

The hydrogen storage and return unit may comprise an outer casing intended to house at least the anode, the cathode, the cation donor, the non-conductive but electrically conductive material, the possible heating element and, if appropriate, also the electrical connector. This outer casing can be made at least partially in a synthetic or metallic material. The anode of the hydrogen storage and recovery unit may be porous and / or pierced with orifices, for example being in the form of a screen or a metallic or metallized foam.

The heating member may comprise an electrical resistance, and be inside or outside the outer casing.

The heating member may, for example, make it possible to heat the unit to a temperature greater than or equal to 30 ^° C., more preferably 50 ^° C., for example between 70 and 350 ^° C.

The heating member may comprise an electrical resistance at least partially disposed in the cathode or in an element in contact with it, for example in an elastically deformable member for applying the cathode against the non-conductive but electrically conductive material and for compensating variations in volume of the cathode.

When the heating member is disposed at least partially in the cathode, it may for example comprise a resistive wire traveling through the cathode and electrically isolated therefrom.

The unit may further comprise a temperature sensor, better a device for regulating the temperature of the cathode, for example to control the heating of the cathode to adjust the temperature to the desired hydrogen flow rate. The unit can be configured to allow expansion of the cathode during its operation, and in particular to ensure permanent contact between the cathode and the non-conductive but electrically conductive material.

The unit may comprise an elastically deformable member on the side of the cathode opposite to the electrically non-conductive material of the ion-permeable wall, arranged to urge the cathode to bear against this electrically nonconductive material. Such an elastically deformable member may deform elastically to compensate for a change in volume of the cathode, for example during swelling due to accumulated hydrogen.

The elastically deformable member is for example made at least partially with an elastically deformable metal material, for example a spring steel, or with an elastomer having a sufficient thermal resistance, for example based on silicone that can withstand a temperature of at least 250 ⁰ C. In an exemplary embodiment, the cathode is tubular, surrounding for example an interior space for its expansion. Such a configuration is desirable when the cathode comprises one or more intermetallic compounds capable of expanding upon hydrogen accumulation, for example from about 25% to 30% by volume. The internal space can accommodate the elastically deformable member, which is for example in the form of an elastomeric sleeve.

The interior space can still accommodate, for example, the heater and / or the temperature sensor.

The unit may comprise a filling connector and / or purge cation donor, optionally provided with a valve opening on connection with a filling system or purging outside the unit.

The unit may include a hydrogen outlet fitting for conveying the liberated hydrogen gas outside the unit.

These connectors fill and / or purge and hydrogen outlet may be provided with suitable sealing systems, such as O-rings, for example.

The invention also relates to a charging device of a unit as defined above, comprising at least one housing for receiving the storage unit and at least one electrical connector to be connected to the electrical connector of the unit so to generate an electric field between the cathode and the anode and, if necessary, heat the cathode.

The recharging device can comprise several housings allowing to recharge several units simultaneously or successively.

On the other hand, the recharging device may comprise a housing for receiving a supply of water or electrolyte for supplying the unit or units with an internal circuit, and optionally recovering the electrolyte during the emptying of these cells. units.

The charging device can be arranged to monitor the charge and interrupt it when certain conditions are reached.

The recharging device may comprise one or more end-of-charge indicators, for example one or more light-emitting diodes and / or a pressure detection device. Detection of the increase in pressure can translate a saturation of the cathode into hydrogen and the end of the possibility of storage. The charging device can be arranged to cut the power supply from a certain value of the pressure.

The recharging device may comprise, for example at the bottom of each of the housings intended to receive a unit, at least one connector to be connected to the hydrogen outlet and / or with the filling and / or purge connector (s) mentioned above. - above. One or more valves may be actuated during the introduction of a refill in the charging device.

The invention further relates to a method comprising the step of supplying a fuel cell with the hydrogen extracted from a storage unit as defined above.

In the case where the unit is intended to be introduced into an electrical appliance, the storage unit may, before its introduction, be emptied of the cation donor, in particular in the case where the latter is a liquid. This emptying can be performed to the aforementioned charging device, for example. The invention also relates to an electrical appliance, in particular a telephone or laptop, comprising at least one housing for receiving at least one storage unit as defined above.

The unit may be configured to operate at ambient temperature or even at a temperature greater than 60 ^° C., for example more than 100 ^° C., and for example at an internal pressure of between 0.1 bar and 100 bar. The storage in the cathode can be improved under pressure.

The unit may, where appropriate, be coupled to a fuel cell, for example within a one-piece assembly.

The fuel cell can share an envelope with the hydrogen production and storage unit, if any.

In such a case, the destocking of hydrogen takes place to the fuel cell without leaving the envelope containing the storage unit and the fuel cell.

The invention will be better understood on reading the following detailed description, non-limiting examples of implementation thereof, and on examining the appended drawing, in which: FIG. schematic and simplified hydrogen storage and production units, as well as the associated charging device, FIG. 2 is a view similar to FIG. 1, the hydrogen production and storage units being removed from the charging device, FIG. 3 is an exploded view showing an assembly comprising a storage and production unit and a fuel cell, - Figure 4 shows the assembly of Figure 3, in the assembled state, Figure 5 shows an alternative embodiment of the unit,

FIG. 6 is a diagrammatic and partial longitudinal section of the unit of FIG. 5, FIG. 7 is a schematic and partial section of an alternative embodiment of the unit, and FIG. 8 represents examples of FIG. rate of hydrogen loading as a function of time, according to several voltages applied between the anode and the cathode.

FIG. 1 shows a system 1 comprising two removable units 2 for producing and storing hydrogen and a recharging device 3 for recharging these units 2 in hydrogen between two successive uses.

The charging device 3 may comprise, as can be seen in FIG. 2 in particular, housings 4 for each receiving a unit 2 and may comprise a reservoir 5 which can be filled with a liquid intended for the units 2, for example the electrolyte.

In a variant, the charging device 3 comprises a single housing 4. Each unit 2 may, as illustrated in FIGS. 3 and 4, be arranged to be coupled during use to a fuel cell 6, for example within an assembly 10 comprising at least one fluidic connector making it possible to recover the hydrogen produced by the unit 2 for injection into the fuel cell 6 and an electrical connector for electrically powering the unit 2, for example to cause by heating the release of the stored hydrogen.

The assembly 10 may comprise, as illustrated in Figure 4, an electrical connector 11 for the fuel cell to electrically power the electrical apparatus in which the assembly 10 is introduced.

FIG. 3 shows another example of unit 2, having a generally cylindrical shape.

This unit 2 comprises an outer casing 15 which has a cover 16 at one end. Of course, the invention is not limited to a particular envelope shape, and this may be in one piece, if appropriate. The casing 15 accommodates in the example considered an anode 20, which is advantageously perforated in order to increase the exchange surface, an ion-permeable wall 21 comprising an electrically nonconductive but ionically conductive material, a cathode 22 made in a material for storing hydrogen and an elastic return member 24.

The material of the wall 21 permeable to ions, which is disposed in contact with the cathode 22, is electrically non-conductive but ionic conductor, in order to be traversed by the H ⁺ ions. Storage of hydrogen is favored when the contact area between the cathode 22 and this electrically nonconductive material 21 is large. The wall 21 has for example a tubular shape closed by a bottom, on the opposite side to the cover 16.

The non-conductive material of the wall 21 may comprise hexagonal boron nitride, activated by the electrolyte being left several hours in contact, under an electric field. The return member 24 is for example a sleeve of an elastomeric material such as silicone, capable of withstanding the temperature at which the cathode 22 is heated to release the hydrogen.

The wall 21 and the return member 24 may confine with each other the cathode 22 when the latter is liquid or powdery. The return member 24 makes it possible to press the cathode 22 against the wall 21, in order to ensure contact between the two despite the expansions of the cathode 22.

Unit 2 can accommodate a heater 25 for heating cathode 22 to cause release of accumulated hydrogen.

The unit 2 can also be provided with a temperature sensor 26, shown very schematically in FIG. 6, in order to avoid overheating and / or to control the flow rate of hydrogen released by regulating the heating of the cathode 22 .

The exit of the hydrogen out of the unit can take place by an orifice 27 which forms or is equipped with a male or female connector, possibly equipped with a valve.

An electrolyte circulation can take place through the unit, by means of orifices 14. The circulating electrolyte comes into contact with the anode 20 and the wall 21.

According to one aspect of the invention, the cathode 22 is made of a material capable of storing hydrogen, for example a hydrurable material. Under the effect of an electric field created between the anode 20 and the cathode 22, the anode being connected to the pole positive of an electric generator which is for example integrated to the charging device 3, and the cathode to the negative pole of this electric generator, the H ⁺ cations contained in the electrolyte migrate through the wall 21 to the cathode 22 and reduce atomic hydrogen at the interface of the cathode 22 and the wall 21. The atomic and / or molecular hydrogen thus generated is directly stored in the cathode 22, and possibly in the wall 21 if this is carried out in accordance with the WO 2006/003328.

Hydrogen is preferably stored in the cathode as atomic hydrogen, being directly adsorbed in the cathode. In the case where the cathode comprises an intermetallic compound, the hydriding of the cathode can be done by a chemissorption reaction, the molecular hydrogen splitting into atomic hydrogen in contact with the intermetallic compound. In order to promote this chemissorption reaction, the hydrophilic cathode may optionally be heated and / or pressurized.

If the pore diameter of the wall 21 is smaller than the dimensions of the H ₃ O ⁺ ions contained in the H ⁺ ion donor, the intensity of the electric field applied between the anode and the cathode must be sufficient to cause the rupture H ₃ O ⁺ ions according to the reaction:

H ₃ O ⁺ - »H ₂ O + H ⁺

The reaction consumes water, which is preferably present in the electrolyte.

The hydrogen production reaction also causes a gaseous release of oxygen. This gas evolution can result in the formation of bubbles at the anode 20 in the electrolyte.

The gaseous oxygen produced during the production of hydrogen can be recovered at a corresponding outlet in the unit, and stored or used directly, or released into the atmosphere.

It is possible to extract the hydrogen thus stored by heating the cathode and / or by putting the latter in depression, for example to supply a fuel cell and / or to use hydrogen as fuel or reagent. Preferably, the unit is emptied of the electrolyte before heating the cathode. This emptying can be done to the charging device, for example.

The flow of hydrogen extracted can be controlled by acting for example on the heating temperature of the cathode. In a variant that is not illustrated, the heating member is outside the casing 15.

In the variant illustrated in FIG. 7, the heating member 25 is disposed within the cathode 22. This figure also illustrates the possibility for the anode 20 to be supported by the ion-permeable wall 21.

The anode 20 is crossed by the electrolyte 40, which may optionally communicate with a reserve located on the side of the anode 20 which is opposite the cathode 22.

The ion-permeable wall 21 may have a multilayer structure, with for example, as illustrated in FIG. 7, a support layer 21a and a layer 21b of non-conductive but electrically conductive material.

The support layer 21a may be constituted by a porous ceramic, for example.

The presence of the support layer 21a can reduce the thickness of the layer 21b by providing the maintenance function of this layer 21b.

The layer 21a can also make it possible to use an anode 20 having a lower mechanical strength, by supporting it.

FIG. 8 represents an example of results obtained with a unit similar to that of the example of FIG. 6, with the exception of the heating element, placed outside the envelope.

The anode used is graphite. The wall 21 is hexagonal boron nitride activated by being left three hours in contact with the electrolyte under tension of 50 volts. The wall 21 is for example made by machining a bar, with a thickness of 1 mm.

The electrolyte is 5M sulfuric acid. The cathode 22 is based on LaNi ₅ powder used in NiMH batteries.

Of course, the invention is not limited to the examples which have just been described.

The unit can be made with different shapes and sizes and with other materials. If necessary, the anode and the cathode can be interdigitated. The unit may include a plurality of storage generating cells each having a cathode and an anode. The electrolyte may be located internally, being surrounded by the anode, the ion-permeable wall and the cathode, which is thus external to the anode and may itself be surrounded by an elastically deformable member. The expression "comprising" should be understood as being synonymous with "having at least one", unless the opposite is specified.

Claims

1. A method for storing and producing hydrogen, wherein for storing hydrogen, a unit (2) comprising: a cation donor, in particular an H + ion, an anode (20), a cathode capable of storing the atomic and / or molecular hydrogen (22), an ion-permeable wall (21) having an electrically nonconductive but ionically conductive material between the cathode and the cation donor is subjected to an electric field for forming at least at the interface of the cathode and of the electrically nonconductive material, of atomic and / or molecular hydrogen and its storage within the at least one cathode, and wherein, to restore gaseous hydrogen, the cathode is heated and / or depressed.

2. Method according to the preceding claim, wherein the wall (21) permeable to ions has a permeability to water less than 5% of the mass of hydrogen produced.

3. Method according to the preceding claim, wherein the cathode contains less than 5% by weight of water.

The method of any preceding claim, wherein the ion-permeable wall (21) has zero water permeability.

5. Process according to any one of the preceding claims, the cathode comprising an intermetallic compound, in particular chosen from the following list: of type AB5 (A and B being metals), for example LaNi ₅ , the lava phases (Zr, Ti ) (Mn, V, Cr, Ni) ₂ , for example ZrMn ₂ or TiMn ₂ , Mg, TiFe, Mg ₂ Ni, vanadium-centered solid cubic solutions, BaReHg (the formula corresponding to the hydrided state), Mg ₂ FeH ₆ (the formula corresponding to the hydrided state), NaAH ₄ (the formula corresponding to the hydrided state), LiBH ₄ (the formula corresponding to the hydride state), and all their compounds, derivatives or their alloys .

6. Method according to one of the preceding claims, the electrically non-conductive material comprising a ceramic, in particular comprising a nitride of hexagonal boron, better boron nitride activated by an acid solution under electric field, lithium nitride, an ionic conductive polymer, boric acid.

7. Method according to one of the preceding claims, the wall (21) permeable to ions comprising one or more layers of different materials, at least one of these layers exerting a cationic conductor function.

8. Method according to the preceding claim, the wall (21) comprising a porous layer having a support function between the layer having the cationic conductor function and the electrolyte.

9. Process according to any one of the preceding claims, wherein the cation donor is an acidic aqueous solution.

The process according to any of the preceding claims, wherein the cation donor is circulated in the unit.

11. A method according to any one of the preceding claims, wherein the voltage applied between the anode and the cathode during the production of hydrogen is between 1 and 300 volts better between 1.24 and 200 volts, preferably between 1.24 and 4 volts.

12. Method according to any one of the preceding claims, wherein the cathode is heated to a temperature above 30 ⁰ C, especially between 70 and 350 C, to produce hydrogen gas.

13. The method of claim 12, the heating being caused by effect

Joule during the circulation of an electric current.

14. The method of claim 12, the heating taking place after evacuation of the electrolyte.

15. The method of claim 12, the unit being heated to a temperature below that producing the destocking of hydrogen, during the phase of production and storage of hydrogen, in order to improve the latter.

The method of any of the preceding claims, wherein atomic and / or molecular hydrogen is also stored in the electrically nonconductive but ionically conductive material.

17. Unit (2) for storing and recovering hydrogen comprising: an anode (20), a cathode (22) capable of storing atomic and / or molecular hydrogen, a cation donor, in particular of H + ions, an ion-permeable wall (21) comprising an electrically nonconductive but ionically conductive material between the cathode and the cation donor, optionally a member (25) for heating the cathode, an electrical connector for electrically feeding the anode and cathode in order to create between them an electric field allowing the formation of atomic and / or molecular hydrogen at least within the cathode and its storage at least in the cathode , the unit being arranged to collect the hydrogen gas released by the cathode at least during heating thereof, the unit further comprising: a fluidic connector for channeling hydrogen to the outside of the unit gas thus released.

18. Unit according to the preceding claim, the heating means comprising an electrical resistance.

19. Unit according to one of the two preceding claims, further comprising a device (26) for regulating the temperature of the cathode.

20. Unit according to any one of the three preceding claims, wherein the cathode (22) comprises an intermetallic compound

21. Unit according to any one of claims 17 to 20, wherein the non-electrically conductive material comprises a ceramic, in particular an amorphous ceramic.

22. Unit according to any one of claims 17 to 21, the cation donor being an aqueous acid solution.

23. Unit according to any one of claims 17 to 22, comprising an elastic return member (24) for biasing the cathode against the non-conductive electrical material but ionic conductor.

24. Unit according to any one of claims 17 to 23, comprising a filling connector and / or purge cation donor.

25. Unit according to any one of claims 17 to 24, comprising a connector for extracting the stored hydrogen gas.

26. Unit according to any one of claims 17 to 25, the anode (20) being supported by the wall (21) permeable to ions.

27. A method of producing electricity, comprising the step of supplying a fuel cell with hydrogen extracted from a storage unit as defined in any one of claims 17 to 26.

28. Device for recharging a unit as defined in any one of claims 17 to 26, comprising at least one housing (4) for receiving the unit (2) and at least one electrical connector to be connected to the electrical connector. of the unit to generate an electric field between the cathode and the anode.

29. Electrical apparatus, in particular a telephone or laptop, comprising at least one housing for receiving at least one storage unit according to any one of claims 17 to 26.