JP5858862B2 - Electrochemical equipment - Google Patents

Description

  Embodiments of the present invention relate to electrochemical devices.

  A solid oxide fuel cell (SOFC) is a reductive substance supplied to a hydrogen electrode through an electrolyte membrane having ionic conductivity (oxygen ions or hydrogen ions) under an operating condition of about 600 to 900 ° C. This is a device for reacting a gas (fuel gas: hydrogen or hydrocarbon) and an oxidizing gas (oxygen or air) supplied to the oxygen electrode (fuel cell reaction) and taking out the energy as electricity.

  On the other hand, an electrochemical cell (Solid Oxide Electrolysis Cell: SOEC) is based on the reverse reaction of SOFC, and obtains hydrogen and oxygen by electrolyzing high-temperature water vapor through an ionic conductive electrolyte membrane. Device.

  Therefore, if the so-called reversible operation, in which the fuel cell reaction and the electrolytic reaction are performed alternately in the same cell, is performed, hydrogen is accumulated by the electrolytic reaction when there is a margin in power, and power is generated using the accumulated hydrogen when power is insufficient. It is possible to provide a power storage system using hydrogen as an energy medium. However, when putting such an operation into practical use, it is necessary to establish a cell structure that efficiently performs both the fuel cell reaction and the electrolytic reaction and maintains high efficiency over a long period of time.

  In general, a plurality of the above-described electrochemical cells are connected in series via a separator, and are configured as an electrochemical device having a laminated structure in which an end plate is arranged at the end. In such an electrochemical device, when the electrochemical cell is used as an SOFC, the electricity generated in each electrochemical cell is taken out to the outside via the end plates arranged above and below and stored appropriately. On the other hand, when the electrochemical cell is used as a SOEC, hydrogen generated by electrolysis in each electrochemical cell is appropriately stored.

  However, as described above, in order to establish a cell structure that maintains high efficiency over a long period of time, when an electrochemical cell is used as a SOFC, a reducing gas and an oxidizing gas supplied to each electrode In a single electrochemical device including an electrochemical cell and a separator, it is important that each gas leaks from the flow path and does not mix and react with each other. In addition, when an electrochemical cell is used as a SOEC, hydrogen gas generated in each electrochemical cell does not leak outside from a single electrochemical device including the electrochemical cell and separator, and is mixed and reacted with each other. It is important not to.

  Therefore, in order to establish the cell structure as described above, it is important to ensure the sealing property (sealing property) between the electrochemical cell and the separator.

  In order to solve such problems, conventionally, a glassy or metal sealing material has been installed in contact with, for example, the cell end face and compressed from above and below to ensure gas sealing performance. However, in the sealing method for flat plate cells, the maintenance of the sealing structure largely depends only on the viscosity of the glass, which is the quality of the sealing member, and the viscosity of the glass changes greatly in the vicinity of the operating temperature. However, it is difficult to maintain all the sealing properties, and there is a problem that the sealing performance may become unstable due to the limited sealing area. Furthermore, there is a problem that sufficient sealing performance cannot be obtained over the entire surface when the cell thickness varies in a plane.

JP 2005-1000086 JP 2007-287585 A

  The problem to be solved by the present invention is to ensure the sealing performance of the electrochemical cell and the sealing performance of the oxygen electrode and the hydrogen electrode in a single electrochemical device having an electrochemical cell and a separator. It is an object of the present invention to provide an electrochemical device that improves the efficiency of a battery reaction and an electrolytic reaction and maintains a highly efficient fuel cell reaction and electrolytic reaction over a long period of time.

One embodiment of the present invention is an electrically insulating electrolyte membrane exhibiting oxygen ion conductivity, an oxygen electrode formed on one main surface side of the electrolyte membrane, and the other main surface of the electrolyte membrane An electrochemical cell having a hydrogen electrode formed on the side, a pair of separators made of an electrically conductive material electrically connected to each of the oxygen electrode and the hydrogen electrode of the electrochemical cell, and the pair comprising a first sealing member and Netsu膨tonicity of the second seal member of the easily deformable which is disposed between the separators, at least one of a portion of the first seal member and said second sealing member, wherein Located on the end of the electrolyte membrane of the electrochemical cell, isolates the oxygen electrode and the hydrogen electrode of the electrochemical cell, and the first seal member is easily deformable at the use temperature of the electrochemical cell. The second seal Characterized in that it is a foam material that is thermally expanded by the wood foams at the use temperature of the electrochemical cell.

  According to the present invention, in a single electrochemical device having an electrochemical cell and a separator, the sealing property of the electrochemical cell is ensured, the sealing property of the oxygen electrode and the hydrogen electrode is ensured, and the fuel cell reaction and electrolysis are ensured. The efficiency of the reaction can be improved, and a highly efficient fuel cell reaction and electrolytic reaction can be maintained over a long period of time.

It is sectional drawing which shows schematic structure of the electrochemical apparatus in 1st Embodiment. It is a schematic block diagram which shows the state which laminated | stacked the electrochemical apparatus shown in FIG. 1, and connected two or more in series. It is sectional drawing which shows schematic structure of the electrochemical apparatus in 2nd Embodiment. It is sectional drawing which shows schematic structure of the electrochemical apparatus in 3rd Embodiment.

  Hereinafter, it demonstrates based on embodiment, referring drawings.

(First embodiment)
FIG. 1 is a cross-sectional view illustrating a schematic configuration of an electrochemical device according to the present embodiment, and FIG. 2 is a schematic configuration diagram illustrating a state in which the electrochemical devices illustrated in FIG. 1 are stacked and a plurality are connected in series. . In addition, the electrochemical apparatus demonstrated below is related with the single electrochemical apparatus which comprises a laminated structure as shown in FIG.

  An electrochemical device 10 shown in FIG. 1 includes an electrochemical cell 11 and a pair of separators 12 and 12 disposed above and below the electrochemical cell 11.

  The electrochemical cell 11 includes a hydrogen electrode porous substrate 111 that is a support substrate, and a hydrogen electrode 114 that is sequentially formed on the upper surface of the support substrate 111, and is electrically insulating and oxygen ion conductive. And an oxygen electrode 113. A first current collecting layer 115 is formed on the upper surface of the oxygen electrode 113, and a second current collecting layer 116 is formed on the lower surface of the hydrogen electrode porous substrate 111.

  The hydrogen porous substrate 111 is not an essential component in the electrochemical device 10 of this embodiment, and can be omitted. However, the provision of the hydrogen electrode porous substrate 111 reduces the supply resistance of the reducing gas (fuel gas: hydrogen, hydrocarbon, etc.) to the hydrogen electrode 114 due to the porosity, and the electrolyte. The thickness of the film 112 can be reduced. If the thickness of the electrolyte membrane 112 is large, it takes a long time for oxygen ions to be conducted through the electrolyte membrane 112, so that the resistance of the electrochemical cell 11, that is, the electrochemical device 10 increases, but the thickness of the electrolyte membrane 112 is increased. Is small, the time required for oxygen ions to be conducted through the electrolyte membrane 112 can be shortened, and the resistance of the electrochemical cell 11, that is, the electrochemical device 10 can be reduced.

The hydrogen electrode porous substrate 111 can be composed of an ordinary ceramic sintered body, and the porosity is attributed to the molding pressure when forming the molded body, the sintering temperature during sintering, and the like. In particular, the amount of the three-phase interface on the side of the hydrogen electrode 114 is increased by using an electron-ion mixed conductive ceramic material. Therefore, the electrochemical reaction at the hydrogen electrode 114 is promoted, and the output characteristics of the electrochemical cell 11 can be improved. Specifically, it can be composed of at least one selected from the group consisting of _Sm 2 _{O 3} doped _CeO 2, _Gd 2 _{O 3} doped CeO _2, and _Y 2 _{O 3} doped CeO _2.

The electrolyte membrane 112 can be composed of, for example, stabilized zirconia. In this case, examples of the stabilizer include Y ₂ O ₃ , Sc ₂ O ₃ , Yb ₂ O ₃ , Gd ₂ O ₃ , Nd ₂ O ₃ , CaO, and MgO. These stabilizers are used as a solid solution in zirconia. Moreover, it can replace with stabilized zirconia and can also comprise perovskite type oxides, such as LaSrGaMg oxide, LaSrGaMgCo oxide, LaSrGaMgCoFe oxide, LaSrGaMgCoFe oxide. Furthermore, a ceria-based electrolyte solid solution in which Sm ₂ O ₃ , Gd ₂ O ₃ , Y ₂ O ₃ , La ₂ O _{3 and the} like are dissolved in CeO ₂ can also be used. However, the electrolyte membrane 112 is not limited to these materials, and may be made of other materials.

  The electrolyte membrane 112 generally has a dense structure because it conducts only oxygen ions and does not allow gas to pass therethrough. Therefore, as described below, even when contacting the seal member, high sealing performance is exhibited between the seal member and the electrolyte membrane 112.

  The thickness of the electrolyte membrane 112 can be arbitrarily set according to the purpose, but can be set in the range of, for example, 0.001 mm to 0.5 mm.

The oxygen electrode 113 can be made of any material that has been used as an oxygen electrode of an electrochemical cell, such as LaSrMnO ₃ perovskite oxide, but is preferably made of a lanthanum / strontium / cobalt composite oxide. To do. Thereby, the reaction efficiency between the oxygen electrode 113 and the hydrogen electrode 114 can be improved, the generation voltage when used as a solid electrolyte fuel cell (SOFC) can be further improved, and the electrochemical cell (SOEC). As a result, the generation current, that is, the generation amount of oxygen and hydrogen can be further improved.

  Examples of the lanthanum / strontium / cobalt composite oxide include lanthanum / strontium / cobalt / iron composite oxide in addition to lanthanum / strontium / cobalt composite oxide.

  When the electrochemical cell 11 is used as SOFC, the oxygen electrode 113 supplies an oxidizing gas (oxygen, air, etc.) over the entire oxygen electrode 113 (thickness direction), and the use efficiency of the oxidizing gas When the electrochemical cell 11 is used as SOEC in order to improve the efficiency, it is generally formed as a porous body in order to efficiently extract the generated oxygen gas.

  Although the thickness of the oxygen electrode 113 can be arbitrarily set according to the purpose, it can be, for example, in a range of 0.01 mm to 1 mm.

  The hydrogen electrode 114 can be composed of nickel particles or cermet of nickel oxide particles and at least one of ceria-based and zirconia-based ceramic particles. When the hydrogen electrode 114 is composed of cermet, before the reduction treatment, the mass mixing ratio of nickel oxide particles and ceramic particles is, for example, 70:30 to 30:70, and the average particle diameter of nickel oxide particles and the average of ceramic particles The ratio with the particle diameter is set to, for example, 100: 30 to 100: 1. Note that the nickel oxide particles are converted into nickel particles after the reduction treatment.

  When the electrochemical cell 11 is used as SOFC, the hydrogen electrode 114 supplies a reducing gas (such as hydrogen gas or hydrocarbon gas) over the entire hydrogen electrode 114 (in the thickness direction), thereby reducing the reducing gas. When the electrochemical cell 11 is used as SOEC in order to improve the efficiency of use, it is generally formed as a porous body in order to efficiently extract the generated hydrogen gas.

  The thickness of the hydrogen electrode 114 can be 5 μm to 100 μm.

Examples of the ceria-based ceramic particles include particles made of ceramics in which Sm ₂ O ₃ , Gd ₂ O ₃ , Y ₂ O ₃ , La ₂ O _{3 and the} like are dissolved in CeO ₂ . Moreover, as zirconia-based ceramic particles, stabilizers such as Y ₂ O ₃ , Sc ₂ O ₃ , Yb ₂ O ₃ , Gd ₂ O ₃ , Nd ₂ O ₃ , CaO, and MgO are dissolved in ZrO ₂ . There may be mentioned particles made of ceramics.

  The first current collector 115 and the second current collector 116 mainly reduce the contact resistance between the electrochemical cell 11 and the pair of separators 12, 12. For example, when the electrochemical cell 11 is used as a SOFC, the separator 12 , 12 to extract the generated power to the outside with high efficiency without loss. In the present embodiment, the first current collector 115 and the second current collector 116 are not indispensable components, but the above-described effects can be obtained by disposing these current collectors.

  The first current collector 115 and the second current collector 116 need to be made of a material that does not oxidize under normal operating conditions. For example, the first current collector 115 and the second current collector 116 are other base materials in addition to noble metals such as gold, silver, and platinum. A metal or the like coated with silver or the like can be used. A ceramic material having conductivity can also be used. Further, a chromium-based alloy whose oxide film has conductivity can also be used. Moreover, the form can also be made into a film | membrane form as needed, and can also be made into a mesh form or a felt form.

  In the electrochemical cell 11 of the present embodiment, the oxygen electrode 113 is disposed on the upper side and the hydrogen electrode 114 is disposed on the lower side. However, the oxygen electrode 113 is disposed on the lower side, and the hydrogen electrode 114 is disposed on the lower side. It can also be arranged on the upper side.

In the present embodiment, it is disposed between the pair of separators 12 and 12, the first seal member 15 and Netsu膨tonicity of the second seal member 16 of the easily deformable sealing an electrochemical cell is provided . A part of the first seal member 15 is located on the end of the electrolyte membrane 112 of the electrochemical cell 11 and isolates the oxygen electrode 113 and the hydrogen electrode 114 of the electrochemical cell 11.

  The first seal member 15 is an easily deformable seal member, and is a use temperature of a metal foil such as copper, silver, aluminum, or the electrochemical cell 11, that is, the electrochemical device 10, for example, at a temperature of 600 ° C. to 900 ° C. It can be made of glass that softens. Specifically, it can be composed of sodium silicate glass and borosilicate glass.

  In the present embodiment shown in FIG. 1, since the first seal member 15 is made of a metal foil, the lower seal 12 and the electrolyte membrane are formed on the first seal member 15 with an adhesive 17 such as silver paste. While being fixed on the edge part of 112, the insulating material 18 is provided and it electrically connects with the upper separator 12. FIG. In the case where the first seal member 15 is made of glass as described above, the glass 17 itself has adhesiveness and electrical insulation, and thus the adhesive 17 and the insulating material 18 described above can be omitted.

  Even when the first seal member 15 is made of a metal foil, the adhesive 17 can be omitted if the upper surface of the lower separator 12 is processed to provide an anchoring effect such as an uneven structure. it can.

  In addition, in the lower separator 12 in contact with the first seal member 15, the first seal member 15 and the lower seal 12 are fixed by preliminarily fixing the adhesive or the fine powder made of the same material as the first seal member 15. The adhesion of the separator 12 is improved. The fine powder is fixed by, for example, a sputtering method or a cold spray method.

  The second seal member 16 is a heat-expandable seal member. Specifically, the second seal member 16 foams at a temperature of, for example, 600 ° C. to 900 ° C., which is the use temperature of the electrochemical cell 11, that is, the electrochemical device 10. It is made of a material that expands. Specifically, it is made of a material containing a foaming agent such as shirasu balloon, pearlite, fly ash or the like. As an example, the foaming agent is 1 to 20% by mass, preferably 5 to 10% by mass, glass such as sodium silicate glass and borosilicate glass is 30 to 40% by mass, and ceramics such as yttria-stabilized zirconia and alumina are 20 to 20%. 30% by mass, a general organic binder such as methylcellulose, and a material containing 10 to 30% by mass of a component such as Cr or S that does not contain a poisoning component for the cell can be formed.

  By adopting the sealing structure as described above, the electrochemical cell 11 is sealed with the first seal member 15 and the second seal member 16, and the oxygen electrode 113 and the hydrogen electrode 114 of the electrochemical cell 11 are also sealed with the first seal member 15. And is sealed and isolated by the second seal member 16.

  Therefore, when the electrochemical cell 11 is used as SOFC, an oxidizing gas (such as oxygen or air) supplied to the oxygen electrode 113 and a reducing gas (fuel gas: hydrogen or hydrogen) supplied to the hydrogen electrode 114 are used. Hydrocarbons etc.) leak from the respective flow paths and do not mix and react with each other. In addition, when the electrochemical cell 11 is used as a SOEC, hydrogen gas and oxygen gas generated in the electrochemical cell do not leak outside from the electrochemical device 10 including the electrochemical cell 11 and the separator 12 and are mixed with each other. And does not react.

  As a result, it is possible to provide the electrochemical device 10 that maintains a highly efficient fuel cell reaction and electrolytic reaction over a long period of time.

  In the present embodiment, since the first current collector 115 is formed relatively thick on the oxygen electrode 113, the first seal member 15 (including the adhesive 17 and the insulating material 18 in the case of a metal foil) is used. ) And the second seal member 16 are arranged so as to have substantially the same thickness as that of the first current collector 115, so that the above-described sealing property and isolation property must be ensured.

  Moreover, in this embodiment, although the 1st seal member 15 is arrange | positioned inside and the 2nd seal member 16 is arrange | positioned on the outer side, both arrangement order can also be reversed. That is, the first seal member 15 can be disposed on the outside and the second seal member 16 can be disposed on the inside.

  The electrochemical device 10 shown in FIG. 1 is generally used by being connected in series by being stacked via a separator 12 as shown in FIG. A pair of end plates 21 and 21 are disposed at both ends of the laminated structure. For example, when the electrochemical cell 11 is used as a SOFC, the total power generated in each electrochemical cell 11 is the pair of end plates 21 and 21. It is taken out through. For example, when the electrochemical cell 11 is used as a SOEC, an electrolytic voltage to be applied to each electrochemical cell 11 is supplied from a pair of end plates 21, 21, and each electrochemical cell 11 is passed through a pair of separators 12. To be supplied.

  Although not particularly illustrated, in the laminated structure shown in FIG. 2, each electrochemical cell 11 and the end plate 21 are fastened from above and below by a plurality of bolts.

(Second Embodiment)
FIG. 3 is a cross-sectional view illustrating a schematic configuration of the electrochemical device according to the present embodiment. In addition, the same code | symbol is used about the component similar to or the same as the component shown in FIG.1 and FIG.2.

  As shown in FIG. 3, the electrochemical device 30 of the present embodiment has a convex portion 121 formed downward at the end of the separator 12 located on the upper side of the electrochemical cell 11, and the convex portion 121 is thermally expandable. Except that the second seal member 16 is pressed, it has the same configuration as the electrochemical device 10 of the first embodiment shown in FIG.

  In this embodiment, since the convex part 121 of the separator 12 presses the second seal member 16, the sealing property of the electrochemical cell 11 is particularly improved, and it is generated when the electrochemical cell 11 is used as a SOEC. Leakage of hydrogen gas and oxygen gas from the electrochemical device 10 including the electrochemical cell 11 and the separator 12 can be prevented.

  When the second seal member 16 is disposed inside the first seal member 15, in addition to the sealing performance as described above, the sealing performance (isolation properties) of the oxygen electrode 113 and the hydrogen electrode 114 of the electrochemical cell 11. ) Will also improve. Therefore, when the electrochemical cell 11 is used as SOFC, an oxidizing gas (such as oxygen or air) supplied to the oxygen electrode 113 and a reducing gas (fuel gas: hydrogen or hydrogen) supplied to the hydrogen electrode 114 are used. Hydrocarbons and the like) can be more effectively prevented from leaking out from the respective flow paths and mixing and reacting with each other. Moreover, when using the electrochemical cell 11 as SOEC, it can prevent more effectively that the hydrogen gas and oxygen gas which were produced | generated by the electrochemical cell mutually mix and react.

  As a result, it is possible to provide the electrochemical device 10 that maintains a highly efficient fuel cell reaction and electrolytic reaction over a long period of time.

(Third embodiment)
FIG. 4 is a cross-sectional view illustrating a schematic configuration of the electrochemical device according to the present embodiment. In addition, the same code | symbol is used about the component similar to or the same as the component shown in FIG.1 and FIG.2.

  As shown in FIG. 4, the electrochemical device 40 according to the present embodiment includes the electrochemical cell 11 from the upper separator 12 between the first seal member 15 located on the inner side and the hydrogen electrode 113 of the electrochemical cell 11. A partition wall 122 extending toward the electrolyte membrane 112 is provided. Therefore, even when the first seal member 15 is composed of sodium silicate glass, borosilicate glass, or the like, and the glass is melted at the use temperature of the electrochemical cell 11, the melted glass flows into the oxygen electrode 113, There is no case where it adheres to the oxygen electrode 113 and impairs its function.

  When the oxygen electrode 113 is disposed on the lower side and the hydrogen electrode 114 is disposed on the upper side, the first seal member 15 and the hydrogen electrode 114 are separated from each other by the partition wall 122, and the first seal member 15 is In the case where the glass is composed of the soda silicate glass and the borosilicate glass, it is possible to prevent the melted glass from adhering to the hydrogen electrode 114 and not to impair the function.

  Since other features, advantages, and operational effects are the same as those of the electrochemical device 10 of the first embodiment, description thereof is omitted.

  As mentioned above, although several embodiment of this invention was described, these embodiment was posted as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

10, 30, 40 Electrochemical apparatus 11 Electrochemical cell 111 Hydrogen electrode porous substrate 112 Electrolyte membrane 113 Oxygen electrode 114 Hydrogen electrode 115 First current collector 116 Second current collector 12 Separator 121 Separator convex part 122 Partition 15 First Seal member 16 Second seal member 17 Adhesive 18 Insulating material 21 End plate

Claims (4)

An electrolyte membrane that is electrically insulating and exhibits oxygen ion conductivity, an oxygen electrode formed on one main surface side of the electrolyte membrane, and a hydrogen electrode formed on the other main surface side of the electrolyte membrane An electrochemical cell having:
A pair of separators electrically connected to each of the oxygen electrode and the hydrogen electrode of the electrochemical cell and made of an electrically conductive material;
Comprising a second seal member of the first seal member and Netsu膨tonicity of the easily deformable which is disposed between the pair of separators,
A part of at least one of the first seal member and the second seal member is located on an end portion of the electrolyte membrane of the electrochemical cell, and isolates the oxygen electrode and the hydrogen electrode of the electrochemical cell. And
The first seal member is a metal foil that exhibits easy deformation at the use temperature of the electrochemical cell,
The electrochemical device, wherein the second seal member is a foam material that thermally expands by foaming at a use temperature of the electrochemical cell . Disposed an insulating material at least one of the upper and lower surfaces of those said metal foil, characterized in that to ensure electrical insulation between the pair of separators, the electrochemical device according to claim 1. At least one of the pair of separators, characterized in that it has a convex portion that presses the second sealing member, the electrochemical device according to claim 1 or 2. Said first sealing member and said second sealing member, characterized in that it comprises the formed partition wall between at least one of the hydrogen electrode and the oxygen electrode of the electrochemical cell, claim 1-3 The electrochemical device according to 1.

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