JP6139344B2 - Electrochemical cell - Google Patents

Description

  Embodiments of the invention relate to electrochemical cells.

  Solid Oxide Fuel Cell (SOFC) usually uses a reducing fuel gas (hydrogen or hydrogen) through an electrolyte membrane having ionic conductivity (oxygen ions or hydrogen ions) under operating conditions of about 600 to 1000 ° C. This is a device that reacts a hydrocarbon (such as hydrocarbon) with an oxidizing gas (such as oxygen) (fuel cell reaction) and extracts the energy as electricity.

  On the other hand, Solid Oxide Electrolysis Cell (SOEC) uses the reverse reaction of SOFC as the principle of operation, and electrolyzes high-temperature water vapor through an electrolyte membrane having ionic conductivity, thereby converting hydrogen and oxygen. It is a device to obtain.

  Regarding the shape of the solid oxide type electrochemical cell, since it is based on solid oxide (ceramics), it can be formed into various shapes. In general, a flat plate type, a cylindrical type, a wave type, a honeycomb type, a cylindrical flat plate type, and the like can be given. Among these shapes, there is a cylindrical flat plate type that is installed in mass-produced household fuel cell systems that are currently on the market and has a proven record (Patent Document 1).

  Cylindrical plate type electrochemical cell is, for example, a fuel electrode, an electrolyte, and an air electrode are laminated on a porous support having a flow path for gas flow, one end side is opened, and the other side is a gas manifold. The structure is arranged.

  When such a cylindrical plate type electrochemical cell is used for SOFC, fuel gas is supplied from the gas manifold to the flow path of the porous support, and electricity is generated by an electrochemical reaction. At this time, since the end on the side opposite to the side on which the gas manifold is disposed is open, unreacted fuel in the electrochemical reaction is discharged from the open end. Therefore, there is a problem that the use efficiency of the fuel gas when used as SOFC is low and the power generation efficiency is lowered.

  In addition, when a cylindrical plate type electrochemical cell is used for SOEC, water vapor as a raw material is supplied to the air electrode and water vapor is decomposed into hydrogen and oxygen by an electrolysis reaction. It is held in the flow path of the porous support. However, since one end of the electrochemical cell is open, particularly the generated hydrogen gas is reoxidized when it comes into contact with external air or the like. For this reason, there existed a problem that the production | generation efficiency of hydrogen gas fell and the electrolysis efficiency by the said electrochemical cell fell.

JP 2003-272668 A

  The present invention can improve the use efficiency of reducing fuel gas when used as a fuel cell, improve the power generation efficiency of the fuel cell, and can generate hydrogen generated when used as an electrolysis cell. An object of the present invention is to provide an electrochemical cell having a cell structure capable of improving the production efficiency and the electrolysis efficiency of the electrolytic cell.

  The electrochemical cell of the embodiment is an electrically insulating electrolyte membrane exhibiting oxygen ion conductivity, a fuel electrode formed on a first main surface of the electrolyte membrane, and the electrolyte membrane, An air electrode formed on a second main surface opposite to the first main surface and a main surface of the fuel electrode on the side facing the electrolyte membrane, and along the length direction inside And a porous support formed with a plurality of channels. Further, a sealing member disposed so as to seal the plurality of flow paths at one end side, and a reducing fuel gas is supplied or generated into the plurality of flow paths at the other end side. And a gas supply / recovery member arranged to recover the generated hydrogen gas. In the porous support, a dense member is inserted into one of the plurality of flow paths so as to divide the plurality of flow paths into two regions in a width direction substantially perpendicular to the length direction. The reducing fuel gas or the hydrogen gas sequentially flows in the first region and the second region defined by the dense member of the plurality of flow paths.

It is sectional drawing which shows schematic structure of the electrochemical cell in embodiment. It is a top view which shows schematic structure of the porous support body of the electrochemical cell shown in FIG. It is an upper top view which shows schematic structure of the electrochemical cell in this embodiment. It is an upper top view which shows schematic structure of the electrochemical cell in this embodiment.

(First embodiment)
FIG. 1 is a cross-sectional view showing a schematic configuration of an electrochemical cell in the present embodiment, and FIG. 2 is a plan view showing a schematic configuration of a porous support of the electrochemical cell shown in FIG.

  An electrochemical cell 10 shown in FIG. 1 is formed on the first main surface 11A side of the electrolyte membrane 11 that is electrically insulating and exhibits electronic insulation and oxygen ion conductivity. The fuel electrode 12 and the air electrode 13 formed on the second main surface 11B side of the electrolyte membrane 11 on the side facing the first main surface 11A are included. A porous support 14 is disposed on the main surface 12A of the fuel electrode 12 on the side facing the electrolyte membrane 11. A plurality of flow paths 14 </ b> A are formed along the length direction inside the porous support 14.

  Furthermore, the electrochemical cell 10 includes a sealing member 16 disposed so as to seal a plurality of flow paths 14A formed inside the porous support 14 on one end side, and porous on the other end side. A gas manifold 17 serving as a gas supply / recovery member is provided so as to supply reducing fuel gas to a plurality of flow paths 14A formed inside the carbon support 14 or to recover generated hydrogen gas. Contains.

The electrolyte membrane 11 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. 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 11 is not limited to these materials, and may be composed of other materials.

  In addition, although the thickness of the electrolyte membrane 11 can be arbitrarily set according to the objective, it can be set as the range of 0.001 mm-1 mm, for example. Further, the electrolyte membrane 11 generally has a dense structure because it mainly conducts only oxygen ions and does not allow gas to pass therethrough.

  The fuel electrode 12 can be made of nickel or cermet of nickel oxide and at least one of ceria-based and zirconia-based ceramics. When the fuel electrode 12 is composed of cermet, the mass mixing ratio of nickel oxide and ceramic is set to, for example, 70:30 to 30:70 before the reduction treatment. Note that the nickel oxide is converted to nickel after the reduction treatment.

Examples of the ceria-based ceramics include 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 . Further, examples of the zirconia ceramic particles include stabilized ceramics 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.

  When the electrochemical cell 10 is used as an SOFC, the fuel electrode 12 supplies a reducing fuel gas (a gas containing hydrogen or hydrocarbon as a main component) over the entire fuel electrode 12 to reduce the fuel cell 12. In order to improve the use efficiency of the fuel gas, and when the electrochemical cell 10 is used as an SOEC, water vapor (air) is supplied over the entire fuel electrode 12 to improve the production efficiency of hydrogen gas and the like. In general, it is formed as a porous body.

The thickness of the fuel electrode 12 can be 5 μm to 100 μm.
The air electrode 13 includes a LaSrMn oxide (hereinafter, LSM), a LaSrCo oxide (hereinafter, LSC), a LaSrCoFe oxide (hereinafter, LSCF), a LaSrFe oxide (hereinafter, LSF), a LaSrMnCo oxide (hereinafter, LSMC), LaSrMnCr oxide (hereinafter LSMC), LaCoMn oxide (hereinafter LCM), LaSrCu oxide (hereinafter LSC), LaSrFeNi oxide (hereinafter LSFN), LaNiFe oxide (hereinafter LNF), LaBaCo oxide (hereinafter hereafter) LBC), LaNiCo oxide (hereinafter LNC), LaSrAlFe oxide (hereinafter LSAF), LaSrCoNiCu oxide (hereinafter LSCNC), LaSr-FeNiCu oxide (hereinafter LSFNC), LaNi oxide (hereinafter LN) GdSrCo oxide (hereinafter referred to as G SC), GdSrMn oxide (hereinafter GSM), PrCaMn oxide (hereinafter PCaM), PrSrMn oxide (hereinafter PSM), PrBaCo oxide (hereinafter PBC), SmSrCo oxide (hereinafter SSC), NdSmCo oxidation (Hereinafter referred to as NSC), BiSrCaCu oxide (hereinafter referred to as BSCC), BaLaFeCo oxide (hereinafter referred to as BLFC), BaSrFeCo oxide (hereinafter referred to as BSFC), YSrFeCo oxide (hereinafter referred to as YLFC), YCuCoFe oxide (hereinafter referred to as YCCF) ), YBaCu oxide (hereinafter referred to as YBC), or other materials having electron-ion mixed conductivity.

  In this case, since the air electrode 13 has electronic conductivity and oxide ion conductivity, the electrochemical reaction of oxygen ions in the air electrode 13 is promoted, and oxygen can be generated efficiently. That is, the generation current when used as an SOEC, that is, the generation amount of oxygen and hydrogen can be further improved.

  In addition, when using the material which has the electron-ion mixed conductivity mentioned above, a composition ratio etc. do not ask | require. Further, a mixture of stabilized zirconia or ceria-based electrolyte solid solution may be used. Further, for example, by adding a metal component such as Pt, Ru, Au, Ag, Pd to the above-described electron-ion mixed conductive material, the above-described electron conductivity and oxide ion conductivity are improved. Oxygen and hydrogen production can be increased more efficiently.

  When the electrochemical cell 10 is used as an SOEC, the air electrode 13 is generally formed as a porous body in order to efficiently extract the generated oxygen. Although the thickness of the air electrode 13 can be arbitrarily set according to the purpose, it can be set in a range of 0.001 mm to 1 mm, for example.

  As shown in FIG. 2, the porous support 14 includes a plurality of flow paths 14A and first regions 14A-1 in the width direction substantially perpendicular to the length direction in which the plurality of flow paths 14A are formed. A dense part is formed by inserting a long cylindrical dense member 141 having the same diameter as that of the flow path into the substantially central flow path so as to be divided into two areas of the second area 14A-2. Therefore, when the electrochemical cell 10 is used as an SOFC, when the reducing fuel gas is introduced from the inlet 17A of the gas manifold 17, the reducing fuel gas is short-cut and immediately discharged from the outlet 17B to the outside. Instead, after flowing through the first region 14A-1 to the sealing member 16, it flows through the second region 14A-2 and is discharged from the discharge port 17B (arrow in the figure). reference).

  In the present embodiment, the dense member 141 is inserted in the substantially central flow path of the plurality of flow paths 14A, but in the two areas of the first area 14A-1 and the second area 14A-2. Any one of the plurality of channels 14A may be used as long as it can be divided.

  The reducing fuel gas flowing through the flow path 14A of the porous support 14 reaches the fuel electrode 12 through the pores of the porous support 14, and the air passes through the air electrode 13 and the electrolyte membrane 11 to reach the fuel electrode 12. As a result of the fuel cell reaction occurring at the fuel electrode 12, water (water vapor) is generated. As described above, water (water vapor) is generated when the fuel cell reaction occurs in the fuel electrode 12, but in the present embodiment, the plurality of flow paths 14A of the porous support 14 are formed as described above. The dense member member 141 is inserted into any one of the first region 14A-1 and the second region 14A-2 defined in the porous support 14 by the reducing fuel gas. Will flow sequentially.

  Accordingly, since the retention time and the retention amount of the reducing fuel gas supplied to the porous support 14 in the porous support 14 are increased, the arrival rate of the reducing fuel gas to the fuel electrode 12, that is, the porosity The supply efficiency of the reducing fuel gas to the fuel electrode 12 via the quality support 14 is improved, and the power generation efficiency of the electrochemical cell 10 is improved.

  In addition, when using the electrochemical cell 10 as SOEC, the water vapor | steam used as a raw material comes to be supplied to the air electrode 13, and the dense member 141 of the porous support body 14 is specially used for use as SOEC. Has no effect. However, since the sealing member 16 disposed on one end side of the electrochemical cell 10 is sealed on one end side of the plurality of flow paths 14A of the porous support 14, the generated hydrogen gas is porously supported. When introduced into the body 14, it does not leak to the outside from the open end of the porous support 14. Therefore, the production efficiency of hydrogen gas is improved, and further, the electrolysis efficiency of the electrochemical cell 10 is improved.

  In the present embodiment, “dense” in the dense member 141 means the above-described effect, that is, when reducing fuel gas is introduced from the introduction port 17A of the gas manifold 17, the reducing fuel gas. Are short-cut and immediately discharged from the discharge port 17B to the sealing member 16 after flowing through the first region 14A-1 and then flowing through the second region 14A-2 to the discharge port 17B. For example, the porosity is preferably 10% or less, and more preferably 5% or less. In other words, by having such a porosity, the above-described effects can be achieved, and the “dense” requirement in this embodiment can be satisfied. The porosity is measured by a mercury intrusion method or the like.

  The dense member 141 can be obtained by densifying the same material of the porous support 14. In this case, even if the temperature rises when the electrochemical cell 10 is used as SOFC or SOEC, there is no difference in thermal expansion between the two, and the damage to the porous support 14 due to the difference in thermal expansion is suppressed. be able to.

  The porous support 14 needs to be made of a material having at least electronic conductivity so that a predetermined voltage can be applied between the fuel electrode 12 and the air electrode 13, for example, a metal sintered body or a metal foam. , A metal fiber body, and a ceramic sintered body having conductivity, the porosity of which is, for example, the molding pressure when forming the molded body, the sintering temperature during sintering, and the type of pore forming material Due to etc. In particular, the amount of the three-phase interface on the side of the fuel electrode 12 is increased by using an electron-ion mixed conductive ceramic material. Therefore, the electrochemical reaction in the fuel electrode 12 is promoted, and the output characteristics of the electrochemical cell 10 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. Moreover, electroconductivity can also be provided by plating etc. with respect to the porous support body 14 mentioned above.

  The thickness of the porous support 14 can be, for example, 100 μm or more and 1000 μm or less. The strength that the thickness of the porous support 14 is smaller than 100 μm is not sufficient, and the strength of the electrochemical cell 10 is deteriorated. On the other hand, when the thickness of the porous support 14 is larger than 1000 μm, the ion conductive resistance increases.

(Second Embodiment)
FIG. 3 is an upper plan view showing a schematic configuration of the electrochemical cell in the present embodiment. In FIG. 3, the description of the electrolyte membrane 11 and the fuel electrode 13 is omitted to clarify the features of the present embodiment.

  In the electrochemical cell 20 of the present embodiment, the air electrode 13 is composed of two parts, a first air electrode 13-1 and a first air electrode 13-2, and is disposed on both sides of the dense member 141. This is different from the electrochemical cell 10 of the first embodiment shown in FIG.

  In the electrochemical cell 10 according to the first embodiment, when the electrochemical cell 10 is used as an SOFC, the reducing fuel gas flowing through the flow path 14A of the porous support 14 is porous support as described above. The air reaches the fuel electrode 12 through the pores of the body 14, the air passes through the air electrode 13 and the electrolyte membrane 11, reaches the fuel electrode 12, and a fuel cell reaction occurs in the fuel electrode 12, thereby generating water (water vapor). It becomes like this. However, since the dense member 141 is irrelevant to gas permeation, even if an air electrode is formed in the portion, the air electrode in the portion does not contribute to the fuel cell reaction.

  Therefore, in the electrochemical cell 20 of the present embodiment, as described above, the air electrode 13 is composed of the first air electrode 13-1 and the first air electrode 13-2, and the dense member 141. It is arranged on both sides. Therefore, since the air electrode 13 does not exist at the position where the dense member 141 is located, the power generation efficiency per unit electrode area can be improved. By dividing into two planes, the resistance distribution in each plane in the case of two planes becomes a direction smaller than the distribution in the plane in the case of one plane, and by collecting current separately for each plane, It is possible to increase power generation efficiency.

  Since other features and operational effects are the same as those of the first embodiment, description thereof is omitted in this embodiment.

(Third embodiment)
FIG. 4 is an upper plan view showing a schematic configuration of the electrochemical cell in the present embodiment. In FIG. 4, only the schematic configuration of the porous support of the electrochemical cell is described in order to clarify the features of the present embodiment.

  In the electrochemical cell 30 of the present embodiment, the gas pipe 34 is disposed in the gas flow channel located in the center of the porous support 14, and the dense structure is constituted by the gas pipe 34. It differs from the electrochemical cell 10 of 1st Embodiment shown to 1 grade | etc.,.

  In the electrochemical cell 30 of the present embodiment, since the dense member is constituted by the gas pipe 34, the arrow is not drawn from the introduction port 17 </ b> A provided in the gas manifold 17 but by the arrow in the figure from the gas pipe 34. Since the fuel gas can be introduced into the porous support 14 in the direction shown, the fuel gas can be reliably taken up. After reaching the sealing member 16, it flows through the first region 14A-1 and the second region 14A-2 and is discharged from the gas manifold 17 to the outside as indicated by arrows in the figure. In this case, the introduction port 17A functions as a discharge port.

  Accordingly, since the retention time and the retention amount of the reducing fuel gas supplied to the porous support 14 in the porous support 14 are increased, the arrival rate of the reducing fuel gas to the fuel electrode 12, that is, the porosity The supply efficiency of the reducing fuel gas to the fuel electrode 12 via the quality support 14 is improved, and the power generation efficiency of the electrochemical cell 10 is improved.

  Since other features and operational effects are the same as those of the first embodiment, description thereof is omitted in this embodiment.

  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.

DESCRIPTION OF SYMBOLS 10, 20, 30 Electrochemical cell 11 Electrolyte membrane 12 Fuel electrode 13 Air electrode 13-1 1st air electrode 13-2 2nd air electrode 14 Porous support body 141 Dense member 14-1 1st area | region 14 -2 Second area 34 Gas pipe

Claims (4)

An electrolyte membrane that is electrically insulating and exhibits oxygen ion conductivity;
A fuel electrode formed on the first main surface of the electrolyte membrane;
An air electrode formed on a second main surface of the electrolyte membrane opposite to the first main surface;
A porous material formed on the main surface of the fuel electrode on the side facing the electrolyte membrane, having a plurality of flow paths formed along the length direction therein , and having a plurality of pores. A porous support comprising:
One end side, a sealing member that abolish sealing the plurality of channels to the outside,
A gas supply / recovery member arranged to supply reducing fuel gas into the plurality of flow paths or to recover the generated hydrogen gas on the other end side;
In the porous support, a dense member is inserted into one of the plurality of flow paths so as to divide the plurality of flow paths into two regions in a width direction substantially perpendicular to the length direction. And
The electrochemical cell, wherein the reducing fuel gas or the hydrogen gas sequentially flows through a first region and a second region defined by the dense member of the plurality of flow paths. An electrolyte membrane that is electrically insulating and exhibits oxygen ion conductivity;
A fuel electrode formed on the first main surface of the electrolyte membrane;
An air electrode formed on a second main surface of the electrolyte membrane opposite to the first main surface;
A porous material formed on the main surface of the fuel electrode on the side facing the electrolyte membrane, having a plurality of flow paths formed along the length direction therein , and having a plurality of pores. A porous support comprising:
One end side, a sealing member that abolish sealing the plurality of channels to the outside,
A gas supply / recovery member arranged to supply reducing fuel gas into the plurality of flow paths or to recover the generated hydrogen gas on the other end side;
A gas pipe made of a dense member is inserted into any of the plurality of flow paths in the porous support,
The electrochemical cell according to claim 1, wherein the reducing fuel gas or the hydrogen gas flows along a path from the gas pipe to another flow path in which the gas pipe is not inserted.   The electrochemical cell according to claim 1 or 2, wherein the air electrode is divided into two in a non-formation region of the dense member.   The electrochemical cell according to any one of claims 1 to 3, which constitutes a cell for high-temperature steam electrolysis.

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