JP2014222077A - Hydrogen occlusion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem that high pressure occlusion of hydrogen is difficult.SOLUTION: A thin film anode 150 separates a hydrogen molecule into hydrogen atoms. Protons of the separated hydrogen atoms are incorporated into a proton conductor membrane 160. As a hydrogen occlusion cathode 120 has a low potential relative to the thin film anode 150 by the operation of a power supply 40, the incorporated protons move toward the hydrogen occlusion cathode 120 and are incorporated and stored by the hydrogen occlusion cathode 120. This occlusion is maintained at the intensity according to potential difference.

Description

  The present invention relates to hydrogen storage.

  A method is known in which a hydrogen molecule is changed to a proton once, and then the proton is returned to a hydrogen atom and occluded (for example, Patent Document 1).

JP 2003-336798 A

  The problem of the prior art is that it is difficult to store hydrogen under high pressure. There are many academically unknown areas of reaction between hydrogen and metals, and there are many possibilities for industrial use. However, not limited to Patent Document 1, when hydrogen is introduced into a container, it is difficult to occlude at a hydrogen partial pressure exceeding the mechanical pressure resistance of the container (for example, 1000 atmospheres (≈0.1 GPa)).

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms.

(1) According to one aspect of the present invention, a hydrogen storage device is provided. The hydrogen storage device includes a thin film that takes in hydrogen molecules; a proton conductor that is laminated with the thin film and that allows the hydrogen molecules taken into the thin film to pass as protons; and a proton conductor that is laminated with the proton conductor; An occlusion body that occludes the protons that have passed through; a conductive cathode disposed so as to sandwich the occlusion body together with the thin film; and an electric field generator that generates an electric field such that the electric potential of the thin film is higher than that of the conductive cathode. Is provided. According to this embodiment, protons can be occluded with a strength corresponding to the electric field.

(2) In the above aspect, the electric field generation unit includes a power source that generates a potential difference between the thin film and the conductive cathode. According to this embodiment, since an electric field is generated so as to surround the storage cathode, protons can be stored in the storage cathode better.

(3) In the above embodiment, the occlusion body is laminated on the surface of the conductive cathode; the proton conductor is laminated so as to sandwich the occlusion body with the conductive cathode, and is laminated on the back surface of the conductive cathode. A proton conductor laminated on the back surface of the conductive cathode is disposed so as to be sandwiched with the conductive cathode, and an anode to which a voltage is applied by the power source so as to have a higher potential than the conductive cathode is provided. According to this embodiment, since the electric field also acts on the back surface of the conductive cathode, it is possible to suppress protons from coming out from the back surface.

(4) The said form WHEREIN: The site | part which the said conductive cathode and the said thin film oppose without interposing the said occlusion body is provided with the hydrogen block layer laminated | stacked on the said thin film. According to this embodiment, since the proton is suppressed from moving between the conductive cathode and the proton, peeling between the conductive cathode and the proton conductor can be suppressed.

  The present invention can be realized in various forms other than the above. For example, it can be realized in the form of a hydrogen storage method or the like.

The block diagram of a hydrogen storage apparatus. Sectional drawing of a hydrogen storage structure. The top view of a hydrogen storage structure. The top view of a conductive cathode. The top view of a hydrogen storage cathode. The top view of a proton conductor membrane. The top view of a thin film anode. The top view of a hydrogen block layer. The top view of a hydrogen barrier cathode. The top view of an anode. The graph which shows the relationship between an electromotive force and elapsed time. The block diagram of a hydrogen storage apparatus (embodiment 2). Sectional drawing of hydrogen storage structure (Embodiment 3). Sectional drawing of hydrogen storage structure (Embodiment 4). The top view of a hydrogen storage structure (fifth embodiment). Sectional drawing of hydrogen storage structure (Embodiment 6).

  Embodiment 1 will be described. FIG. 1 shows the configuration of the hydrogen storage device 20. The hydrogen storage device 20 includes a gas container 30, a power source 40, an anode lead wire 51, a cathode lead wire 52, a substrate 60, a heater 70, a heater control unit 75, and a hydrogen storage structure 100.

  The hydrogen storage structure 100 is for storing hydrogen and will be described in detail with reference to FIG. The gas container 30 is for enclosing hydrogen. The power supply 40, the anode lead wire 51, and the cathode lead wire 52 are for applying a voltage to the hydrogen storage structure 100. The substrate 60 is made of quartz glass, diamond, or the like, and supports the hydrogen storage structure 100. Quartz glass is heat resistant, dense, and electrically insulating. The heater 70 heats the hydrogen storage structure 100 through the substrate 60. This heating is performed to control hydrogen storage by the hydrogen storage structure 100, as will be described later. The heater control unit 75 controls the heater 70.

  FIG. 2 shows a cross section of the hydrogen storage structure 100. FIG. 3 shows a top view of the hydrogen storage structure 100. The hydrogen storage structure 100 includes a conductive cathode 110, a hydrogen storage cathode 120, a hydrogen barrier cathode 130, an anode 140, a thin film anode 150, a proton conductor film 160, and a hydrogen block layer 170.

  The conductive cathode 110 is formed on the substrate 60 by a conductor (for example, gold or nickel) that does not allow much hydrogen to pass through. The hydrogen storage cathode 120 is formed on the conductive cathode 110 by a metal (such as lead or a hydrogen storage alloy) that stores hydrogen. The proton conductor film 160 is formed on the hydrogen storage cathode 120 by a composition having a property of conducting protons.

  The hydrogen barrier cathode 130, the anode 140, and the thin film anode 150 are formed on the substrate 60 and the proton conductor film 160 by film formation. The thin film anode 150 is formed of a conductive material (metal such as lead) having a property of occluding hydrogen. The hydrogen barrier cathode 130 and the anode 140 are made of a conductive material (metal such as gold or nickel). If the hydrogen barrier cathode 130 and the anode 140 are the same material, the hydrogen barrier cathode 130 and the anode 140 may be formed simultaneously.

  As a method for forming the hydrogen barrier cathode 130, the anode 140, and the thin film anode 150, vapor deposition or sputtering is preferable. The planar shape of each layer is shown in FIGS. In the film formation, the one-dot broken lines are matched and laminated. 4 shows the conductive cathode 110, FIG. 5 shows the hydrogen storage cathode 120, FIG. 6 shows the proton conductor membrane 160, FIG. 8 shows the hydrogen blocking layer 170, FIG. 9 shows the hydrogen barrier cathode 130, and FIG. An anode 140 is shown.

  The hydrogen block layer 170 is formed of a material (metal or insulator) that hardly transmits hydrogen. The hydrogen blocking layer 170 blocks permeation of hydrogen in a region where hydrogen does not preferably pass (hereinafter referred to as “unsuitable region”), while in a region where hydrogen preferably passes (hereinafter referred to as “preferred region”). Forms a hydrogen passage window. These areas will be described later.

  A method of using the hydrogen storage device 20 will be described with reference to FIGS. A gas containing hydrogen isotope molecules is sealed in the gas container 30. Hydrogen isotope molecules (A in FIG. 2) in the gas are absorbed by the thin film anode 150 in the hydrogen passage window and decomposed to become hydrogen isotope atoms (B in FIG. 2). Hydrogen isotope atoms (B in FIG. 2) in the proton conductor film 160 are brought into contact with the proton conductor film 160 by diffusion and become positively charged hydrogen isotope ions.

  After filling the gas, a voltage of several volts is applied by the power source 40. When a voltage is applied, the thin film anode 150 becomes higher in potential than the conductive cathode 110. Since an electric field acts on the proton conductor film 160, positively charged hydrogen isotope ions move toward the hydrogen storage cathode 120 having a negative potential and are absorbed by the hydrogen storage cathode 120 (FIG. 2 C).

Thus, the hydrogen isotope in the gas is pushed into the hydrogen storage cathode 120 and stored according to the applied voltage value. This indentation strength is indicated as pressure by the Nernst equation.
P _H = P ₀ exp (zFV / RT) (1)
P _H : pressure acting on hydrogen isotope ions, P ₀ : partial pressure of hydrogen isotope gas, V: applied voltage, z: valence of hydrogen isotope ions, F: Faraday constant, R: gas constant, T: Temperature (Kelvin)

  The hydrogen isotope ions occluded in the hydrogen occlusion cathode 120 pass through the proton conductor membrane 160, exit the hydrogen occlusion structure 100, and return to the gas. However, the hydrogen isotope atoms released and diffused into the proton conductor film 160 are ionized again, and are drawn back to the hydrogen storage cathode 120 by the electric field.

  Furthermore, since the hydrogen storage cathode 120 is sandwiched between the conductive cathode 110 and the proton conductor film 160, an electric field is generated so as to surround the hydrogen storage cathode 120. As a result, hydrogen cannot come out at the boundary between the hydrogen storage cathode 120 and the conductive cathode 110, and storage by high pressure is realized.

FIG. 11 is a graph showing the relationship between electromotive force and elapsed time. This relationship was acquired by an experiment using the hydrogen storage device 20. The experimental conditions were as follows: the thickness of the hydrogen storage cathode 120 was 0.2 μm, the area of the hydrogen storage cathode 120 (area of the hydrogen passage window) was 58 mm ² , the thickness of the proton conductor film 160 was 1 μm, and the proton conductor film 160. The composition was set to BaZr _0.8 Y _0.2 O ₃ , the target temperature of the hydrogen storage structure 100 was 260 ° C. (533 K), the applied voltage was 1 to 10 V, and the current was 0.1 to 1 mA. The electromotive force was measured after the electric circuit was disconnected at each measurement target time.

As shown in FIG. 11, the electromotive force increased with time, reaching a maximum of about 0.5V. Substituting this voltage value, valence z = 1 of hydrogen isotope ions, and P ₀ = 0.2 atm into equation (1) results in P _H ≈1 GPa. Ordinary pressure vessels cannot withstand such ultra high pressures. In contrast, the hydrogen storage device 20 does not have a pressure-resistant structure, and realizes storage by such an ultrahigh pressure. Such occlusion is realized due to the overall laminated structure without gaps and the dimensional effect of the hydrogen storage cathode 120.

  Since the hydrogen storage cathode 120 is formed as a thin film, internal defects are unlikely to occur during the manufacturing process. For this reason, strength is increased by the size effect based on fracture mechanics. Since the size effect is generally remarkable when the size is smaller than the micron order, the size effect is greatly improved in the strength of the hydrogen storage cathode 120.

  As described above, the hydrogen blocking layer 170 blocks the transmission of hydrogen isotope molecules in the inappropriate region, while forming a hydrogen passage window in the suitable region to allow the hydrogen isotope molecules to pass through. The preferred region is a region where the hydrogen storage cathode 120, the thin film anode 150, and the proton conductor film 160 overlap. In contrast, the unsuitable region is a region where the conductive cathode 110 and the thin film anode 150 overlap while the hydrogen storage cathode 120 does not overlap.

  If hydrogen isotope molecules are taken into the thin film anode 150 in the inappropriate region, the hydrogen isotope ions move toward the conductive cathode 110. The conductive cathode 110 cannot occlude a large amount of hydrogen isotope ions due to the nature of the material. The hydrogen isotope ions that are not occluded generate a high pressure at the boundary between the conductive cathode 110 and the proton conductor film 160. The high voltage may cause the conductive cathode 110 and the proton conductor film 160 to peel off. The hydrogen blocking layer 170 is provided to suppress such peeling by preventing the hydrogen isotope molecules from being taken into the thin film anode 150.

  As described above, according to the hydrogen storage device 20, storage of hydrogen by ultra high pressure is realized. Furthermore, the hydrogen storage device 20 can be used for various experiments relating to storage of hydrogen.

  A second embodiment will be described. FIG. 12 shows the configuration of the hydrogen storage device 220. However, illustration of the gas device, the heater, and the heater control unit is omitted. The hydrogen storage device 220 includes a plurality of hydrogen storage units 102, a power source 240, a plurality of anode wirings 251, and a plurality of cathode wirings 252.

  Each of the plurality of hydrogen storage units 200 corresponds to a stacked body of the hydrogen storage structure 100 and the substrate 60 of the first embodiment. The power supply 240, the anode wiring 251 and the cathode wiring 252 are for applying a voltage to each of the hydrogen storage units 200.

  By integrating the hydrogen storage structure as in the second embodiment, even if the hydrogen storage cathode is thin (for example, less than a micron order), a sufficient calorific value can be obtained in an application using an exothermic reaction, or a physical property measurement experiment. In this application, a sufficient signal amount can be obtained.

  For example, when used as an experimental device to observe changes and reactions associated with hydrogen storage of metals, the necessary functions are realized by attaching a thermocouple for temperature measurement, an X-ray window for X-ray analysis, and various measuring instruments. Can be made. When utilizing an exothermic reaction of a metal storing hydrogen, a desired function can be realized by incorporating a heat exchange device.

  The substrate in Embodiment 2 is preferably composed of film-like glass or the like. Thereby, the hydrogen storage structure can be accumulated at a sufficiently high density. A structure that absorbs heat or a product may be sandwiched between the hydrogen storage structures, or the hydrogen storage structures may be in close contact with each other via an appropriate insulator.

  Another embodiment 3 will be described. FIG. 13 shows a hydrogen storage structure 300 according to the third embodiment. Unlike the hydrogen storage structure 100, the hydrogen storage structure 300 includes a hydrogen storage cathode 320 instead of including the conductive cathode 110 and the hydrogen storage cathode 120.

  The hydrogen storage cathode 320 has both functions of the conductive cathode 110 and the hydrogen storage cathode 120 in the first embodiment. That is, the hydrogen storage cathode 320 realizes generation of an electric field for the proton conductor film 160 and storage of protons. Further, in the third embodiment, the hydrogen block layer is unnecessary and omitted. According to the third embodiment, the cost can be reduced.

  The hydrogen isotope ions stored in the hydrogen storage cathode 320 tend to pass through the substrate 60 and the hydrogen barrier cathode 130. However, since these materials are made of materials that do not easily allow hydrogen to pass through, these materials hardly pass. In this way, the hydrogen storage cathode 320 can store the hydrogen isotope at a high pressure.

  A fourth embodiment will be described. FIG. 14 is a cross-sectional view of the hydrogen storage structure 400. As shown in FIG. 14, the hydrogen storage structure 400 includes a second proton conductor film 460 and a field anode 480 in addition to the hydrogen storage structure 100 of the first embodiment. Instead, a hydrogen barrier cathode 430 and an anode 440 instead of the anode 140 are provided.

  The electric field anode 480 is provided on the substrate 60. The second proton conductor film 460 is provided between the electric field anode 480 and the conductive cathode 110. The anode 440 is electrically connected to the thin film anode 150 and the electric field anode 480. With this configuration, the electric field also acts on the back surface of the conductive cathode 110, so that protons are prevented from coming out of the back surface, and the problem that the substrate 60 and the conductive cathode 110 are separated by high-pressure hydrogen is suppressed.

  A fifth embodiment will be described. FIG. 15 is a top view of the hydrogen storage structure 500. The hydrogen storage structure 500 includes hydrogen barrier cathodes 531 and 532 and anodes 541 and 542. The hydrogen barrier cathode 532 and the anode 542 function as an electrical resistance measurement for a hydrogen storage cathode or a thin film anode or as a spare for disconnection. According to the hydrogen storage structure 500, convenience in measurement is improved.

  A sixth embodiment will be described. FIG. 16 is a cross-sectional view of the hydrogen storage structure 600. As shown in FIG. 16, the hydrogen storage structure 600 will be described based on the hydrogen storage structure 400 of the fourth embodiment. Instead of the conductive cathode 110 and the hydrogen storage cathode 120, the hydrogen storage structure of the third embodiment is used. It has a structure including a cathode 320.

  The present invention is not limited to the embodiments, examples, and modifications of the present specification, and can be implemented with various configurations without departing from the spirit of the present invention. For example, the technical features in the embodiments, examples, and modifications corresponding to the technical features in the embodiments described in the summary section of the invention are to solve some or all of the above-described problems, or In order to achieve part or all of the effects described above, replacement or combination can be performed as appropriate. If the technical feature is not described as essential in this specification, it can be deleted as appropriate. For example, you may exclude a hydrogen block layer from what was demonstrated as a form provided with a hydrogen block layer.

DESCRIPTION OF SYMBOLS 20 ... Hydrogen storage apparatus 30 ... Gas container 40 ... Power supply 51 ... Anode lead wire 52 ... Cathode lead wire 60 ... Substrate 70 ... Heater 75 ... Heater control unit 100 ... Hydrogen storage structure 102 ... Hydrogen storage unit 110 ... Conductive cathode 120 ... Hydrogen storage cathode 130 ... Hydrogen barrier cathode 140 ... Anode 150 ... Thin film anode 160 ... Proton conductor film 170 ... Hydrogen block layer 200 ... Hydrogen storage unit 220 ... Hydrogen storage device 240 ... Power supply 251 ... Anode wiring 252 ... Cathode wiring 300 ... Hydrogen Storage structure 320 ... Hydrogen storage cathode 400 ... Hydrogen storage structure 430 ... Hydrogen barrier cathode 440 ... Anode 460 ... Second proton conductor film 480 ... Electric field anode 500 ... Hydrogen storage structure 531 ... Hydrogen barrier cathode 532 ... Hydrogen barrier cathode 541 ... Anode 542 ... Anode

Claims (4)

A thin film that takes in hydrogen molecules;
A proton conductor laminated with the thin film and passing hydrogen molecules taken into the thin film as protons;
An occlusion body that is laminated with the proton conductor and occludes protons that have passed through the proton conductor;
A conductive cathode disposed so as to sandwich the occlusion body together with the thin film;
A hydrogen storage device comprising: an electric field generating unit that generates an electric field such that the thin film has an electric potential higher than that of the conductive cathode. The hydrogen storage device according to claim 1, wherein the electric field generation unit includes a power source that generates a potential difference between the thin film and the conductive cathode. The occlusion body is laminated on the surface of the conductive cathode,
The proton conductor is laminated so as to sandwich the occlusion body together with the conductive cathode, and is laminated on the back surface of the conductive cathode,
The proton conductor laminated | stacked on the back surface of the said conductive cathode is arrange | positioned so that it may pinch | interpose with the said conductive cathode, The anode to which a voltage is applied by the said power supply so that it may become a higher electric potential than the said conductive cathode is provided. 2. The hydrogen storage device according to 2. The hydrogen storage device according to any one of claims 1 to 3, further comprising a hydrogen block layer that is stacked on the thin film at a portion where the conductive cathode and the thin film face each other without the storage member interposed therebetween.

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