WO2016063647A1

WO2016063647A1 - Electrochemical cell stack and electrical power system

Info

Publication number: WO2016063647A1
Application number: PCT/JP2015/075358
Authority: WO
Inventors: 亀田　常治; 吉野　正人; 理子犬塚
Original assignee: 株式会社東芝
Priority date: 2014-10-20
Filing date: 2015-09-07
Publication date: 2016-04-28
Also published as: JP6385788B2; JP2016081813A

Abstract

An electrochemical cell stack 10 according to the present invention comprises small unit cell stacks 11 and a heat exchanger 12 disposed between the small unit cell stacks 11 to exchange heat with the small unit cell stacks 11, wherein each of the small unit cell stacks 11 includes at least one unit cell 13 formed by stacking current collectors 15 and 16 and a separator 17 on each surface of an electrochemical cell 14 including an electrolyte film 21, an oxygen electrode 22 disposed on one principal surface of the electrolyte film 21, and a hydrogen electrode 23 disposed on another principal surface of the electrolyte film 21.

Description

Electrochemical cell stack and power system

Embodiments of the present invention relate to an electrochemical cell stack and a power system.

An electrochemical cell including a solid electrolyte membrane, for example, contains a reducing agent such as hydrogen or hydrocarbon and an oxidizing agent such as oxygen through a solid electrolyte membrane having ion conductivity under a high temperature condition of 700 to 1000 ° C. Used to react and extract electrical energy. In addition, the electrochemical cell can generate oxygen and hydrogen by electrolyzing water vapor with electric energy supplied from the outside.

Electrochemical cell functions as a solid oxide fuel cell (SOFC) that extracts reaction energy between a reducing agent and an oxidizing agent as electricity when a reaction for extracting electric energy is performed. On the other hand, in the case of electrolyzing water vapor or the like, the electrochemical cell uses the reverse reaction of the reaction in the SOFC as described above as an operating principle, and electrolyzes high-temperature water vapor through an electrolyte membrane to generate hydrogen and oxygen. It functions as a solid oxide electrolysis cell (SOEC).

Using an electrochemical device equipped with an electrochemical cell having both functions of SOFC and SOEC, power can be afforded by performing either power generation mode or electrolysis mode operation, so-called reversible operation, as necessary. Sometimes, it is possible to realize a power storage system (hydrogen power storage system) that generates and stores hydrogen and generates power using the stored hydrogen when power is insufficient.

In such a power storage system, the entire heat storage system is further enhanced by efficiently accumulating or supplying heat accompanying the exothermic reaction that occurs during power generation in SOFC and the endothermic reaction that occurs during electrolysis of water vapor in SOEC. It can be operated efficiently.

JP 2012-109251 A JP 2011-228171 A

In order to operate the entire power storage system with high efficiency, the heat transfer between the electrochemical cell and the outside is efficiently performed during exothermic and endothermic reactions in the electrochemical cell. It is desired that the electrochemical cell stack can be stably used for a long period of time at a temperature (for example, 700 to 1000 ° C.) at which oxygen ions can effectively pass through the solid electrolyte membrane.

An object of the embodiment of the present invention is to provide an electrochemical cell stack that can be used stably for a long period of time within a temperature range in which the solid electrolyte membrane functions effectively.

An electrochemical cell stack according to one embodiment comprises an electrolyte membrane, an oxygen electrode provided on one main surface of the electrolyte membrane, and a hydrogen electrode provided on the other main surface of the electrolyte membrane. A small unit cell stack including one or more single cells each having a current collector and a separator provided on both sides of the chemical cell; and between the small unit cell stacks and one end of the small unit cell stack. It is provided in any one or both, It comprises the said small unit cell stack and the heat exchange part in which heat exchange is possible, It is characterized by the above-mentioned.

It is a perspective view which shows simply the structure of the electrochemical cell stack by 1st Embodiment. FIG. 2 is a cross-sectional view taken along the line AA in FIG. FIG. 3 is a cross-sectional view taken along the line BB in FIG. It is a disassembled perspective view of an electrochemical cell. It is a schematic diagram which shows an example of a 1st electrical power collector or a 2nd electrical power collector. It is the elements on larger scale of FIG. It is a figure which shows typically another example of a 1st electrical power collector or a 2nd electrical power collector. It is a figure which shows typically another example of a 1st electrical power collector or a 2nd electrical power collector. It is a figure which shows typically another example of a 1st electrical power collector or a 2nd electrical power collector. It is a figure which shows typically another example of a 1st electrical power collector or a 2nd electrical power collector. It is sectional drawing which shows another example of a structure of an electrochemical cell stack. It is sectional drawing which shows another example of a structure of an electrochemical cell. It is explanatory drawing which shows an example of a heat exchanger. It is explanatory drawing which shows the relationship between the height of an electrochemical cell stack, and the temperature of a single cell. It is explanatory drawing which shows the relationship between the height of an electrochemical cell stack, and the temperature of a single cell. It is the figure which provided the cell edge part cover in the edge part of a hydrogen electrode and a hydrogen electrode porous base material. It is the figure which provided the sealing layer in the cell edge part cover. It is sectional drawing which shows another example of a structure of an electrochemical cell stack. It is a figure which shows simply the structure of the electric power system by 2nd Embodiment.

Hereinafter, embodiments of the present invention will be described in detail.

[First Embodiment]
<Electrochemical cell stack>
FIG. 1 is a perspective view schematically showing a configuration of an electrochemical cell stack according to the present embodiment, FIG. 2 is a cross-sectional view taken along line AA in FIG. 1, and FIG. 3 is a cross-sectional view taken along line BB in FIG. It is. As shown in FIGS. 1 to 3, the electrochemical cell stack 10 includes a small unit cell stack 11 and a heat exchanger (heat exchange unit) 12, and the small unit cell stack 11 and the heat exchanger 12 are stacked. Configured.

In the present embodiment, the reaction gas supplied into the small unit cell stack 11 refers to an oxidizing agent, a reducing agent, or water vapor. The oxidant refers to a gas containing oxygen such as air, the reducing agent refers to a fuel gas such as hydrogen or hydrocarbon, and the water vapor may be a medium in which most of the water is in a gas phase state. This includes cases where some of the state water is included.

(Small unit cell stack)
The small unit cell stack 11 includes one or more flat plate-type single cells 13 (in the embodiment shown in FIGS. 1 to 3, five layers are stacked). Note that the small unit cell stack 11 includes one or more single cells. In the present embodiment, the small unit cell stack 11 is preferably configured by stacking 3 to 30 single cells. If the number of single cells in the small unit cell stack 11 is within the above range, as will be described later, heat exchange between each single cell 13 and the heat exchanger 12 can be performed reliably. It becomes easy to control the temperature distribution of the temperature in 11, and the temperature of each single cell 13 can be made constant.

An exploded perspective view of the single cell 13 is shown in FIG. As shown in FIG. 4, the single cell 13 includes an electrochemical cell 14 and current collectors 15 and 16 (first current collector 15 and second current collector 16) provided on both surfaces of the electrochemical cell 14. A pair of separators 17 that sandwich the electrochemical cell 14 from the outside of the first current collector 15 and the second current collector 16, and a cell holder 19.

The electrochemical cell 14 includes an ion conductive solid electrolyte membrane (electrolyte membrane) 21, an oxygen electrode 22 provided on one main surface 21 a of the solid electrolyte membrane 21, and the other main surface 21 b of the solid electrolyte membrane 21. A hydrogen electrode 23 is provided, and a hydrogen electrode porous substrate 24 provided on the surface of the hydrogen electrode 23 opposite to the solid electrolyte membrane 21 side, and these are laminated.

The first current collector 15 is stacked on the outer surface of the oxygen electrode 22, and the second current collector 16 is stacked on the outer surface of the hydrogen electrode 23. The solid electrolyte membrane 21, the oxygen electrode 22, the hydrogen electrode 23, and the hydrogen electrode porous substrate 24 all have a rectangular shape. Further, the size of the oxygen electrode 22 is smaller than that of the solid electrolyte membrane 21, and there is a portion that is not covered with the oxygen electrode 22 on the outer periphery of the solid electrolyte membrane 21. In addition, the shape of the solid electrolyte membrane 21, the oxygen electrode 22, the hydrogen electrode 23, and the hydrogen electrode porous base material 24 is not limited to a square shape, and can be an arbitrary shape.

The solid electrolyte membrane 21 is formed by densely forming a solid oxide having electronic insulation and oxygen ion conductivity into a film shape. Here, the dense state may be a dense density that allows gas leakage in the solid electrolyte membrane 21 to be substantially ignored. The solid electrolyte membrane 21 is formed using, for example, stabilized zirconia, perovskite oxide, or ceria (CeO ₂ ) electrolyte solid solution. Stabilized zirconia is zirconia in which a stabilizer is dissolved in zirconia. As the stabilizer, for _{_{_{_{example, Y 2 O 3, Sc 2}}}} O 3, Yb 2 O 3, Gd 2 O 3, Nd 2 O 3, CaO, MgO or the like can be mentioned. Examples of the perovskite oxide include LaSrGaMg oxide, LaSrGaMgCo oxide, and LaSrGaMgCoFe oxide. As the ceria-based electrolyte solid solution, a solid solution in which Sm ₂ O ₃ , Gd ₂ O ₃ , Y ₂ O ₃ , La ₂ O ₃ , or the like is dissolved in a material containing CeO ₂ can be given. Moreover, the solid electrolyte membrane 21 is not limited to these materials, and may be composed of other materials.

The solid electrolyte membrane 21 has electronic insulation and oxygen ion conductivity within a temperature range of 700 to 1000 ° C., for example. Within this temperature range, oxygen ions can pass through the solid electrolyte membrane.

In addition, the thickness of the solid electrolyte membrane 21 can be arbitrarily adjusted as appropriate according to the intended use. For example, the thickness of the solid electrolyte membrane 21 is preferably in the range of 5 μm to 500 μm, for example. .

The oxygen electrode 22 is made of a material that can efficiently dissociate oxygen and has electronic conductivity. The oxygen electrode 22 is configured using a known material that is used as an oxygen electrode of an electrochemical cell. Examples of the oxygen electrode 22 include lanthanum / strontium / manganese (LaSrMn) -based perovskite oxide (LSM), LaSrCo oxide (LSC), LaSrCoFe oxide (LSCF), LaSrFe oxide (LSF), LaSrMnCo oxide ( LSMC), LaSrMnCr oxide (LSMC), LaCoMn oxide (LCM), LaSrCu oxide (LSC), LaSrFeNi oxide (LSFN), LaNiFe oxide (LNF), LaBaCo oxide (LBC), LaNiCo oxide (LNC) ), LaSrAlFe oxide (LSAF), LaSrCoNiCu oxide (LSCNC), LaSrFeNiCu oxide (LSFNC), LaNi oxide (LN), GdSrCo oxide (GSC), GdSrMn oxide (GS) ), PrCaMn oxide (PCaM), PrSrMn oxide (PSM), PrBaCo oxide (PBC), SmSrCo oxide (SSC), NdSmCo oxide (NSC), BiSrCaCu oxide (BSCC), BaLaFeCo oxide (BLFC) BaSrFeCo oxide (BSFC), YSrFeCo oxide (YLFC), YCuCoFe oxide (YCCF), or YBaCu oxide (YBC). The oxygen electrode 22 may be a mixture of these oxides, for example, LSM-YSZ, LSCF-SDC, LSCF-GDC, LSCF-YDC, LSCF-LDC, LSCF-CDC, LSM-ScSZ, LSM-SDC, LSM -It may be formed of GDC or the like. Furthermore, for example, components such as Pt, Ru, Au, Ag, and Pd may be added to the oxygen electrode 22.

The thickness of the oxygen electrode 22 can be arbitrarily set according to the intended use. For example, the thickness of the oxygen electrode 22 can be set in the range of 30 μm to 100 μm.

The hydrogen electrode 23 is an oxide having an average particle diameter of 1 nm to 100 nm made of metal particles having an average particle diameter of 0.1 μm to 5 μm made of a hydrogen electrode catalytic metal and an oxide having the same oxygen ion conductivity as the solid electrolyte membrane 21. It is comprised including physical particles. As a hydrogen electrode catalyst metal, metal oxides, such as metals, such as nickel, silver, or platinum, nickel oxide, or cobalt oxide, are mentioned, for example. The oxide constituting the oxide particles is made of ceramics having oxygen ion conductivity, for example, ceria-based oxides such as samaria stabilized ceria (SDC) or gadolinia stabilized ceria (GDC), or yttria stabilized. Examples thereof include zirconia-based oxides such as zirconia (YSZ). Moreover, you may use the oxide which comprises the solid electrolyte membrane 21 as an oxide which comprises an oxide particle.

If the average particle diameter of the metal particles is in the range of 0.1 μm to 5 μm, the surface area of the catalyst particles can be increased, so that the activity as an electrode can be increased. Further, the average particle size of the metal particles is more preferably 1 μm or less. If the particle size is too small, characteristic deterioration due to aggregation of the metal particles occurs at the time of operation of the single cell 13, particularly at a high current density. Therefore, the lower limit of the average particle size of the metal particles is preferably 0.1 μm. .

Further, it is preferable that the average particle diameter of the oxide particles is in the range of 1 nm to 100 nm because the denseness of the structure sintering by firing can be improved. The average particle size of the oxide particles is more preferably 1 nm to 50 nm. In addition, it is preferable that the lower limit of the average particle diameter of oxide particle | grains shall be 1 nm from a viewpoint of a dispersibility at the time of manufacturing technology and mixing.

In addition, the average particle diameter means a volume average diameter by an effective diameter, and the average particle diameter is measured by, for example, a laser diffraction / scattering method or a dynamic light scattering method.

Regarding the mixing ratio of the metal particles and the oxide particles, when the mass of the metal particles is 1, the mass of the oxide particles is preferably set in the range of 0.6 to 1.6. Within this range, the metal particles and the oxide particles are uniformly dispersed, and the activity of the hydrogen electrode 23 and the oxygen ion conduction path and electron conduction path in the hydrogen electrode 23 can be arranged in the most balanced manner.

Further, the thickness of the hydrogen electrode 23 can be arbitrarily set according to the application to be used. For example, the thickness of the hydrogen electrode 23 can be set within a range of 50 μm to 200 μm.

The hydrogen electrode porous substrate 24 is a layer serving as a support substrate of the electrochemical cell 14 and is provided in a state of being integrally bonded to the hydrogen electrode 23. Since the hydrogen porous substrate 24 functions as a support for the electrochemical cell 14, the mechanical strength of the electrochemical cell 14 can be maintained or improved.

The porosity of the hydrogen electrode porous substrate 24 is preferably 30 to 80%, for example. A porosity of 30% or more is preferable because the gas permeability is not impaired and the characteristics of the electrochemical cell 14 can be maintained. On the other hand, when the porosity is 80% or less, it is preferable because the mechanical strength can be sufficiently maintained and the occurrence of breakage during assembly can be suppressed. The porosity is measured by a gas permeation method, a water absorption method, a porosimeter, or the like.

The thickness of the hydrogen electrode porous substrate 24 is preferably set in the range of 500 μm to 5 mm, for example. If the thickness of the hydrogen electrode porous substrate 24 is within this range, the mechanical strength can be maintained and the gas permeability can be secured.

The hydrogen electrode porous substrate 24 is provided on the main surface 23b of the hydrogen electrode 23, but may be provided on one surface of the solid electrolyte membrane 21 on the oxygen electrode 22 side.

In such an electrochemical cell 14, during power generation, as shown by the following formula (1), oxygen is dissociated at the oxygen electrode 22 to generate oxygen ions (O ²⁻ ). The oxygen ions move to the hydrogen electrode 23 through the solid electrolyte membrane 21, and the oxygen ions and hydrogen react with each other as shown by the following formula (2) to generate water. The electrons generated at this time are taken out and consumed by an external load. The reaction during power generation in the electrochemical cell 14 at this time is an exothermic reaction.
1 / 2O ₂ + 2e ⁻ → O ²⁻ (1)
H ₂ + O ²⁻ → H ₂ O + 2e ⁻ (2)

On the other hand, in the electrochemical cell 14, during electrolysis, an external power supply is connected instead of an external load, and a reverse reaction during power generation proceeds. That is, as shown by the following formula (3), the supplied water vapor (water) is decomposed into hydrogen and oxygen ions (O ²⁻ ) at the hydrogen electrode 23 by the power supplied from the external power source to the single cell 13. , Hydrogen is released. Also, oxygen ions move to the oxygen electrode 22 through the solid electrolyte membrane 21. Then, at the oxygen electrode 22, as shown in the following formula (4), electrons are separated from oxygen ions to become oxygen, and the oxygen is released. At this time, the separated electrons are taken out and recycled and used. The reaction during electrolysis in the electrochemical cell 14 at this time is an endothermic reaction.
_{^{_{H 2 O + 2e - → H}}} 2 + O 2- ··· (3) O 2- → 1 / 2O 2 + 2e - ··· (4)

The first current collector 15 and the second current collector 16 are both made of a conductive material and configured to allow gas to pass therethrough. The first current collector 15 and the second current collector 16 are electrically connected to the oxygen electrode 22 and the hydrogen electrode 23, respectively. The first current collector 15 and the second current collector 16 are generally formed in a plate shape in order to collect current evenly from the entire surface of the electrode. The first current collector 15 and the second current collector 16 are generally formed in a rectangular shape smaller than the solid electrolyte membrane 21, and the first current collector 15 is approximately the same size as the oxygen electrode 22. Is formed.

The first current collector 15 and the second current collector 16 are made of a mesh shape, a cloth shape, a porous body, or the like. It is preferable that the first current collector 15 and the second current collector 16 are used so as to have an appropriate thickness. Thereby, the thickness of the 1st electrical power collector 15 and the 2nd electrical power collector 16 can be adjusted arbitrarily.

The first current collector 15 is formed of, for example, a metal such as nickel or stainless steel subjected to an oxidation resistant surface treatment, or a metal having oxidation resistance such as gold, silver or platinum.

The second current collector 16 is formed of a metal such as nickel, silver or platinum, for example.

In addition to the above materials, the first current collector 15 and the second current collector 16 are made by mixing a material used for each electrode such as gold and silver, a metal paste having strong oxidation resistance, and a foam material. It can be formed using a thing.

A foam material is a material that foams during normal temperature to use temperature. For example, calcium carbonate (CaCO ₃ ) can be used as the foaming substance. Calcium carbonate is decomposed into calcium oxide (CaO) and carbon dioxide (CO ₂ ) by heating. When CO ₂ is generated, bubbles are generated in the first current collector 15 and the second current collector 16. Further, as the foamed substance, ceramics containing a component that vitrifies and a component that gasifies into water vapor, CO ₂ , or the like by performing heat treatment at a temperature between normal temperature and use temperature can be used. Such foam materials include pearlite, fly ash, or obsidian. A substance foamed by applying heat treatment to obsidian is used as a shirasu balloon.

If the content of the foaming substance in the first current collector 15 and the second current collector 16 is too small, the volume expansion associated with foaming may be small, and the thermal expansion of the electrochemical cell 14 may not be followed. Moreover, when there is too much quantity of a foaming substance, a bubble may connect and airtightness may not be ensured. Therefore, the content of the foaming substance is, for example, 1 to 20 wt%, more preferably 5 to 10 wt%.

By using a material in which a foam material is mixed as the first current collector 15 and the second current collector 16, the first current collector 15 and the second current collector 16 are expanded or expanded at the use temperature of the electrochemical cell 14. By extending, it is possible to suppress a reduction in contact resistance between the first current collector 15 or the second current collector 16 and the oxygen electrode 22 or the hydrogen electrode 23.

The laminated unit configuration of the electrochemical cell 14 and the first current collector 15 and the second current collector 16 is flatness from the viewpoint of ensuring electrical connection and gas sealing property to suppress gas leakage. Is preferably high. The flatness is defined by JIS. The thickness range of the separator 17 and the cell holder 19 is between the first current collector 15, the second current collector 16, and the cell holder 19 between the first current collector 15 or the second current collector 16. It depends on the respective materials used for the gas seal portion 35 provided.

In the present embodiment, the difference in thickness between the first current collector 15 or the second current collector 16 and the gas seal portion 35 is preferably ± 50 μm or less, and more preferably ± 20 μm or less. If the difference in thickness between the first current collector 15 and the second current collector 16 and the gas seal portion 35 is within the above range, the electrical connection with the separator 17 of the electrochemical cell 14 and the single cell 13 Gas sealing properties can be ensured.

As a method of forming the first current collector 15 and the second current collector 16 that ensure such an electrical connection and gas sealability, for example, a conductive material containing a conductive particulate material and / or a fibrous material is used. There is a method in which a porous porous material is laminated to a predetermined thickness. By laminating the conductive porous material to a predetermined thickness to form the first current collector 15 and the second current collector 16, the first current collector 15 and the second current collector 16 are robust. Due to the excellent properties, even when the thickness of the electrochemical cell 14 varies greatly, the single cell 13 with high flatness can be formed, and the first current collector 15 or the second current collector 16 and the oxygen electrode 22 can be formed. Alternatively, the electrical connection with the hydrogen electrode 23 and the gas sealing property of the single cell 13 can be ensured, and the favorable electrochemical cell stack 10 can be manufactured. Thus, an example of the configuration of the first current collector 15 and the second current collector 16 is shown below.

FIG. 5 is a diagram schematically showing an example of the first current collector 15 or the second current collector 16, and FIG. 6 is a partially enlarged view of FIG. As shown in FIG. 5 and FIG. 6, the first current collector 15 or the second current collector 16 is composed of aggregate particles 41 and aggregate particles 41 that combine the aggregate particles 41 or between the aggregate particles 41 and the electrodes. A layered body (particulate current collecting layer) 43 including particles 42 is formed, and a conductive layer 44 is formed on the surface of the aggregate particles 41.

The aggregate particles 41 can be made of metal, ceramics, organic polymer, or the like. As the metal, stainless steel, ferrite alloy, aluminum, Ni metal, Cr metal, or the like can be used. As the ceramic, any one oxide selected from Al, Si, Ti, Fe, Co, Ni, Cu, Ag, Au, Pd, Pt, Zr, La, Sr, Gd, and Mn, nitride, Alternatively, either carbide can be used. As the organic polymer, epoxy resin, polyester resin, urea resin, polyimide resin, polyethylene resin, polypropylene resin, polyamide resin, vinyl chloride resin, or the like can be used. The aggregate particles 41 may have a powder that is usually commercially available, or may be produced by adjusting the particle size after being manufactured by an atomizing method or the like.

As the bonding fine particles 42, those containing any of Al, Si, Ti, Fe, Co, Ni, Cu, Mn, Ag, Au, Pd, Pt, Rh, Zr, La, Sr, Gd, and the like should be used. Can do. The bonded fine particles 42 are composed of fine crystal and / or amorphous phase particles.

The conductive layer 44 is, for example, a metal layer or a conductive oxide layer. More specifically, it can be a layer made of an oxide compound called various metal materials or a highly conductive oxide. Such a conductive layer 44 can be formed by, for example, a plating method, an ion plating method, a chemical vapor deposition method, a physical vapor deposition method, an electrophoresis method, a sol-gel method, a solution deposition method, or the like. The conductive oxide layer can be easily formed by mixing and drying (oxidizing) several kinds of solutions having components of the oxide compound with the aggregate particles 41.

An oxide compound called a highly conductive oxide includes, for example, TiO, VO, or EuO _1-X called NaCl type, LiTi ₂ O ₄ called spinel type, or Fe ₃ O ₄ , ReO ₂ called perovskite type, M _x WO ₃ (M is a metal _{_{_{generally), LaTiO 3, SrVO 3,}}} CaCrO 3, SrCrO 3, La 1-X SrMnO 3, SrFeO 3, SrCoO 3, La 1-x Sr x CoO 3, LaNiO 3, CaRuO 3, SrRuO ₃ , SrIrO ₃ , BaPbO ₃ , BaPb _1-x Bi _x O ₃ , or (Ba, Ca, Sr) TiO _3-x , V ₂ O ₃ called corundum type, or Ti ₂ O ₃ , called rutile type _{_{_{VO 2, CrO 2, MoO 2}}} , WO 2, β-ReO 2, RuO 2, V O _2n-1 or _{_{_{Ti n O 2n-1, SnO}}} 2-x, Pb 2 Ru 2 O 7-x , called pyrochlore type, or _{_{_{Bi 2 Ru 2 O 7-x}}} , Other _Tl _{2 O 2-x,,} Tl _1-x F, or M _x V ₂ O _2-x (M is a general metal).

In the first current collector 15 or the second current collector 16, the conductive layers 44 of the adjacent aggregate particles 41 are bonded to each other through the bonded fine particles 42, thereby having conductivity as a whole.

Such a current collector can be manufactured, for example, by the following method. The aggregate particles 41 having the conductive layer 44 formed on the surface in advance, the alkoxide solution, and the solvent are adjusted in necessary amounts and mixed sufficiently to prepare a slurry. Thereafter, the slurry is applied to one surface of the electrochemical cell 14, shaped into a predetermined shape, and dried to a predetermined thickness. Thereafter, the electrochemical cell 14 to which the slurry is applied is sandwiched between flat metal plates, and while the slurry is compressed and deformed and restrained, the electrochemical cell 14 to which the slurry is applied is heat-treated to hydrolyze the alkoxide in the slurry. I do. Thereby, the coupling | bonding fine particle 42 produces | generates from an alkoxide solution, the aggregate particle | grains 41 or the electrode of the electrochemical cell 14 and the aggregate particle | grain 41 are each couple | bonded through the produced | generated coupling | bonding fine particle 42, and electrochemical. The first current collector 15 or the second current collector 16 is formed on one surface of the cell 14, and the other current collector is formed on the other surface of the electrochemical cell 14. At this time, the conductive layers 44 of the adjacent aggregate particles 41 are brought into contact with each other, thereby having conductivity as a whole.

Further, after forming the first current collector 15 and the second current collector 16 on both surfaces of the electrochemical cell 14, one or both surfaces of the first current collector 15 and the second current collector 16 are processed to be flat. May be used.

In the above method, the alkoxide solution contains a metal alkoxide containing the component atoms of the aggregate particles 41. Specifically, as the metal alkoxide, an alkoxide compound of any one of Al, Si, Ti, Fe, Co, Ni, Cu, Ag, Au, Pd, Pt, Zr, La, Sr, Gd, or Mn is used. It is done.

As the solvent, an alcohol solution such as butanol can be used.

At this time, as the alkoxide solution, it is preferable to use a mixture of a metal alkoxide containing main component atoms of the aggregate particles 41 and a dispersion medium, and heat treatment is preferably performed at 50 ° C. or higher. By setting the heat treatment temperature to 50 ° C. or higher, the hydrolysis treatment can be effectively advanced. The higher the heat treatment temperature is, the more stable the bonded fine particles 42 are. However, if the temperature is too high, the mechanical properties of the aggregate particles 41 may be deteriorated.

FIG. 7 shows another example of the first current collector 15 or the second current collector 16. As shown in FIG. 7, the first current collector 15 or the second current collector 16 is composed of aggregate particles 41 and bonded fine particles 42, and the respective surfaces of the aggregate particles 41 and the bonded fine particles 42. A conductive layer 44 is formed. In the first current collector 15 or the second current collector 16, the conductive layer 44 is formed on the surface of each of the adjacent aggregate particles 41 and the combined fine particles 42, so that the first current collector 15 or the second current collector 16 is formed. An electrical passage is secured in the two current collectors 16 and has electrical conductivity as a whole. By connecting such a structure in a three-dimensional network, an electric path is formed from the electrochemical cell 14 side to the surface of the first current collector 15 or the second current collector 16.

As described in the method of manufacturing the first current collector 15 or the second current collector 16 shown in FIGS. 5 and 6, the first current collector 15 or the second current collector 16 is previously formed in the conductive layer 44. After the first current collector 15 or the second current collector 16 is manufactured in the same manner except that the aggregate particles 41 in which the conductive layer 44 is not formed are used instead of using the aggregate particles 41 in which the layers are formed. It can be obtained by forming a conductive layer 44 on the surfaces of the aggregate particles 41 and the bonding fine particles 42 by performing a plating process such as electroless plating on the whole. By connecting such a structure in a three-dimensional network, an electric path is formed from the electrochemical cell 14 side to the surface of the first current collector 15 or the second current collector 16.

FIG. 8 shows another example of the first current collector 15 or the second current collector 16. As shown in FIG. 8, the first current collector 15 or the second current collector 16 has aggregate particles 41 covered with a conductive layer 44 and metal particles 45 that join the aggregate particles 41. The first current collector 15 or the second current collector 16 is different from the first current collector 15 or the second current collector 16 shown in FIGS. 5 and 6 in that the aggregate particles 41 on which the conductive layer 44 is formed are formed. The difference is that the particles to be bonded are metal particles 45 made of a metal material. In the first current collector 15 or the second current collector 16, the conductive layers 44 of the adjacent aggregate particles 41 are in direct contact with each other and indirectly in contact through the metal particles 45. As conductive. By connecting such a structure in a three-dimensional network, an electric path is formed from the electrochemical cell 14 side to the surface of the conductive porous material.

The first current collector 15 or the second current collector 16 is obtained by mixing aggregate particles 41 on which a conductive layer 44 has been formed in advance, metal particles 45, and a solvent, forming into a predetermined shape, and drying. The aggregate particles 41 on which the conductive layer 44 is formed and the metal particles 45 are bonded by fusing by heat treatment at a high temperature. At this time, the conductive layers 44 of the aggregate particles 41 are brought into direct contact with each other and indirectly brought into contact with each other through the metal particles 45, thereby having conductivity as a whole.

FIG. 9 shows another example of the first current collector 15 or the second current collector 16. As shown in FIG. 9, the first current collector 15 or the second current collector 16 is composed of two layers of a fibrous current collecting layer 47 made of a conductive fibrous material 46 and a particulate current collecting layer 43. It consists of

In this case, a slurry containing the conductive fibrous material 46 is applied on the electrochemical cell 14 and heat treated to form the fibrous current collecting layer 47, and then the first shown in FIGS. 5 and 6 above. The particulate current collecting layer 43 is formed on the fibrous current collecting layer 47 in the same manner as the method for producing the current collector 15 or the second current collector 16. As a result, the first current collector 15 is formed on one surface of the electrochemical cell 14, and the second current collector 16 is formed on the other surface of the electrochemical cell 14.

FIG. 10 shows another example of the first current collector 15 or the second current collector 16. As shown in FIG. 10, the first current collector 15 or the second current collector 16 includes a metal fiber 48 and a ceramic fiber 49 and is formed in a layer shape.

The metal fiber 48 can be used as long as it has conductivity.

The ceramic fiber 49 is composed of alumina fiber or zirconia fiber.
Moreover, the ceramic fiber 49 can contain a silica etc. as needed. This silica may be inevitably contained as an impurity, or may be contained as a second component.

The ceramic fiber 49 preferably has a diameter of 0.5 μm to 50 μm and a length of 10 μm to 1000 μm. If the diameter of the ceramic fiber 49 is 50 μm or less, the ceramic fiber 49 can be easily bent, and thus can be compressed and deformed, and deterioration of the sealing characteristics can be suppressed. On the other hand, if the diameter of the ceramic fiber 49 is 0.5 μm or more, the ceramic fiber 49 is kept dispersed, and voids can be formed by the ceramic fibers 49. Therefore, it is possible to fill the voids with foamed glass or ceramic particles.

Furthermore, the length of the ceramic fiber 49 is preferably 10 μm to 1000 μm. If the length of the ceramic fiber 49 is 10 μm or more, the intersecting portion of the fibers can also be bent. Therefore, the ceramic fiber 49 can be compressed and deformed, and the deterioration of the sealing characteristics can be suppressed. On the other hand, when the length of the ceramic fiber 49 is 1000 μm or less, the ceramic fiber 49 can be uniformly dispersed, and the voids of the ceramic fiber 49 can be filled with foamed glass or ceramic particles.

A first current collector 15 is formed on one surface of the electrochemical cell 14 by laminating metal fibers 48 and ceramic fibers 49 on the electrochemical cell 14 to form a fiber layer having a predetermined thickness. The second current collector 16 is formed on the other surface of the electrochemical cell 14.

Further, as shown in FIG. 2 or FIG. 3, in the present embodiment, the first current collector 15 and the second current collector 16 are sandwiched between a pair of separators 17 provided outside in the stacking direction. ing. A plurality of holes 28 are provided at the ends of the pair of separators 17, bolts are inserted into these holes 28, and the pair of separators 17 are tightened in a direction approaching each other by a bolt and a nut attached to the bolt.

The separator 17 has a function of supplying a reactive gas (oxidant, reducing agent, or water vapor) to each electrode and collecting current evenly from the entire surface of the electrode. Therefore, the separator 17 has a through oxygen channel 31 and a through fuel channel 32 at predetermined intervals on the contact surface with each electrode in order to supply the reaction gas to each electrode. The penetrating oxygen channel 31 and the penetrating fuel channel 32 are spaces through which regions extending along opposing sides penetrate in the thickness direction of the separator 17.

The separator 17 has a groove-like oxygen channel 33 between a pair of through oxygen channels 31 in order to supply an oxidant (for example, air) to the oxygen electrode 22 on one surface. The separator 17 supplies a reducing agent (for example, hydrogen) or water vapor to the hydrogen electrode 23 on the surface of the separator 17 opposite to the surface on which the grooved oxygen flow path 33 is formed. A grooved fuel flow path 34 is provided between the flow paths 32. The grooved oxygen channel 33 is formed in the separator 17 in a direction orthogonal to the grooved fuel channel 34. The groove-like oxygen flow path 33 and the groove-like fuel flow path 34 form gas spaces that communicate with the oxygen electrode 22 or the hydrogen electrode 23, respectively. Oxygen is supplied to the groove-like oxygen channel 33, and oxygen is supplied to the oxygen electrode 22 through the groove-like oxygen channel 33. Further, hydrogen or water vapor is supplied to the groove-like fuel flow path 34, and hydrogen or water vapor is supplied to the hydrogen electrode 23 through the groove-like fuel flow path 34. When electrolysis is performed in the electrochemical cell 14, only water vapor is supplied and oxygen is not supplied.

The separator 17 is generally formed in a plate shape from a conductive material in order to collect current evenly from the entire surface of the electrode. The electrochemical cell 14 includes a first current collector 15 and a second current collector. 16 and the separator 17 are electrically connected. The separator 17 is in close contact with the oxygen electrode 22 or the hydrogen electrode 23 through a portion in contact with the oxygen electrode 22 or the hydrogen electrode 23 other than the groove-like oxygen channel 33 or the groove-like fuel channel 34. Then, electric power is supplied from the outside to the electrochemical cell 14 through the separator 17, or electric power is supplied from the electrochemical cell 14 to the outside.

Further, it is preferable that a cover layer (not shown) is provided on the electrode-side surface of the separator 17 at a portion in contact with a gas seal portion 35 to be described later so that the contact surface with the gas seal portion 35 is flat.

The adhesion between the first current collector 15 or the second current collector 16 and the electrode surface of the oxygen electrode 22 or the hydrogen electrode 23 depends on the electrochemical cell 14 and the separator 17 and the first current collector 15 or the second current collector. It is ensured by tightening the body 16 from above and below with a plurality of bolts.

In addition, the cell holder 19 has a function of fixing the hydrogen electrode 23 and the ends of the second current collector 16. The cell holder 19 is provided so as to surround the periphery of the hydrogen electrode 23 and the second current collector 16, and the hydrogen electrode 23 and the second current collector 16 are fitted and fixed to the recess 19 a of the cell holder 19. The cell holder 19 is made of metal or ceramics. The cell holder 19 has substantially the same thickness as the electrochemical cell 14, for example.

The electrochemical cell stack 10 includes a gas seal portion 35 between the separator 17 and the cell holder 19 for ensuring the gas seal performance of the single cell 13. The gas seal portion 35 can be formed using an insulating material. Even when the cell holder 19 is made of metal, it is possible to ensure insulation between the first current collector 15 and the second current collector 16. In general, when a wide area of the small unit cell stack 11 is integrally sealed with glass, it is caused by a difference in thermal expansion and misalignment with members constituting the electrochemical cell stack 10 such as the small unit cell stack 11 and the heat exchanger 12. There is a high possibility that the seal will be damaged due to accumulation of distortion and defects. By using glass as a material for forming the gas seal portion 35, the small unit cell stacks 11 are integrated with the glass so that the small unit cell stacks 11 can be appropriately slid and deformed. As a whole, the chemical cell stack 10 can improve robustness against seal breakage.

As the glass, glass having a glass transition temperature of 800 ° C. or higher can be used. Since glass has a stack operating temperature range of about 800 ° C., it is preferable to use crystallized glass that is solid at least 800 ° C. from the viewpoint of durability for a long period of time.
As such glass, for example, sodium silicate or borosilicate glass can be used.

Moreover, the gas seal part 35 can use what combined the said glass and inorganic material. As the inorganic material, ceramics such as yttria-stabilized zirconia and alumina may be further included in the gas seal portion 35. The content of such an inorganic material in the gas seal portion 35 is, for example, 5 to 20 wt%.

The gas seal portion 35 has an adhesive surface having a width obtained by combining the width of the oxygen electrode 22 that is not in contact with the oxygen electrode 22 and the width of the cell holder 19 in the entire width of the solid electrolyte membrane 21.

The gas seal portion 35 preferably has a thickness of 0.2 to 1.0 mm in order to ensure gas sealability.

The gas seal portion 35 is preferably formed with a glass pool groove at an appropriate location of the separator 17 and the cell holder 19 so that the gas seal portion 35 is securely bonded to the separator 17 and the cell holder 19.

Further, in the present embodiment, as shown in FIG. 11, the gas seal portion is provided within a range that does not block the penetrating oxygen channel 31 and the penetrating fuel channel 32 at the end 17 a of the separator 17 for each small unit cell stack 11. 35 is provided. By providing the gas seal portion 35 at the end portion 17a within a range that does not block the through-oxygen flow channel 31 and the through-fuel flow channel 32, the strength of the seal portion of the gas seal portion 35 is improved and the gas seal performance is improved. Can do.

In this embodiment, the single cell 13 is in electrical contact with the oxygen electrode 22 and the separator 17 on the oxygen electrode side, and between the hydrogen electrode 23 and the separator 17 on the hydrogen electrode side while ensuring gas sealing performance at the end. Therefore, the sum of the thicknesses of the oxygen electrode 22, the solid electrolyte membrane 21, the hydrogen electrode 23, the first current collector 15, and the second current collector 16 of the electrochemical cell 14 is equal to the thickness of the cell holder 19. The sum of the thicknesses of the two gas seal portions 35 is preferably substantially the same, and more preferably the difference between the two is 0.1 mm or less. Note that when the bolts are tightened when the electrochemical cell stack 10 is assembled, the gas seal portion 35, the first current collector 15 and the second current collector 16 contract according to the pressure, and the gas seal property and the electrical contact are reduced. In order to ensure, it is preferable to provide a certain degree of robustness.

Furthermore, it is preferable to provide a filler 50 between the electrochemical cell 14 and the cell holder 19 as shown in FIG. By providing the filler 50 between the electrochemical cell 14 and the cell holder 19, even when the unevenness of the end of the electrochemical cell 14 is large, the leakage of the reaction gas from the end of the electrochemical cell 14 is suppressed. can do.

As the material of the filler 50, it is possible to use glass that melts near the operating temperature, ceramic powder that does not cause reaction or melting with glass or peripheral members at the operating temperature, or a mixture of glass powder. it can. The average particle size of the ceramic powder or glass powder is preferably 1 μm or less.

(Heat exchanger)
The heat exchanger 12 is formed in a plate shape and is provided between the small unit cell stacks 11. The heat exchanger 12 exchanges heat with the small unit cell stack 11 and supplies heat to the small unit cell stack 11 during recovery of heat generated by power generation in the single cell 13 or electrolysis in the single cell 13. Is to do. The heat exchanger 12 includes a heat transport pipe 52 through which the heat transport medium gas 51 passes. As the heat transport medium gas 51, for example, nitrogen (N ₂ ), carbon dioxide (CO ₂ ), helium (He), or the like is used.

The heat transport pipe 52 is provided meandering in the heat exchanger 12 as shown in FIG. With this structure, the heat transfer area of the heat transport pipe 52 can be increased by circulating the heat transport medium gas 51 through the heat transport pipe 52.

Since the material of the heat exchanger 12 is required to have high thermal conductivity, electrolyte resistance, heat resistance, etc., for example, stainless steel or the like is used.

Since the heat exchanger 12 is provided between the small unit cell stacks 11, heat exchange is performed for each small unit cell stack 11. Thereby, the electrochemical cell stack 10 can easily control the temperature distribution in the small unit cell stack 11, and can adjust and control the heat exchange efficiency of the entire stack to be high.

Further, since the heat exchanger 12 is provided in a meandering manner with the heat transport pipe 52 inside the heat exchanger 12 to increase the heat transfer area with the heat transport medium gas 51, heat is generated from a limited contact surface with the single cell 13. As a result, the electrochemical cell stack 10 can be made compact.

In addition to the heat exchanger 12 having the heat transport pipe 52 therein, other methods may be used as long as the gas flow path can be formed inside the heat exchanger 12.

The heat exchanger 12 may be provided not only between the small unit cell stacks 11 but also at one end such as the upper end or the lower end of the small unit cell stack 11.

In addition, the electrochemical cell stack 10 includes a metal foil (buffer part) 55 between the small unit cell stack 11 and the heat exchanger 12. As the material of the metal foil 55, SUS or the like is used. Since the metal foil 55 can relieve the stress generated by plastic deformation, by providing the metal foil 55 between the small unit cell stack 11 and the heat exchanger 12, the small unit cell stack 11 and the heat exchanger 12 are provided. And the tolerance for deformation of the small unit cell stack 11 is increased, the robustness of the entire stack is improved, and the gas seal portion 35 can be prevented from being damaged.

In this embodiment, the metal foil 55 is provided between the small unit cell stack 11 and the heat exchanger 12, but the small unit cell stack 11 and the heat exchanger 12 may be directly laminated.

In such an electrochemical cell stack 10, during power generation, an oxidizing agent (for example, air) is supplied to the electrochemical cell stack 10 from an external gas supply means. This oxidant is sent to the grooved oxygen channel 33 through the through oxygen channel 31. The oxidant that has reached the groove-like oxygen flow path 33 passes through the first current collector 15 and comes into contact with the oxygen electrode 22.

On the other hand, a reducing agent (for example, hydrogen) is supplied to the electrochemical cell stack 10 from an external gas supply means. This reducing agent is sent to the grooved fuel flow path 34 through the through fuel flow path 32. The reducing agent that has reached the groove-like fuel flow path 34 is supplied to the hydrogen electrode 23 through the second current collector 16.

Thus, when an oxidizing agent is supplied to the oxygen electrode 22 and a reducing agent is supplied to the hydrogen electrode 23, an electric current is generated in the electrochemical cell 14 to generate electric power. The current generated in the electrochemical cell 14 flows through the second current collector 16 to an external load connected to the electrochemical cell stack 10 and is consumed.

Also, at the time of electrolysis, the oxidizing agent is not supplied, and water vapor is supplied to the penetrating fuel flow path 32 instead of the reducing agent. The water vapor is sent from the through fuel flow path 32 to the grooved fuel flow path 34, passes through the second current collector 16, and is supplied to the hydrogen electrode 23. When water vapor is supplied to the hydrogen electrode 23, the water vapor is electrolyzed in the electrochemical cell 14 to generate hydrogen and oxygen.

Thus, since the electrochemical cell stack 10 is provided with the heat exchanger 12 between the small unit cell stacks 11, the small unit cell stack 11 can perform heat exchange. With this configuration, the electrochemical cell stack 10 can easily control the temperature distribution of the plurality of single cells 13 in the stack, and the solid electrolyte membrane 21 functions effectively in the electrochemical cell stack 10. It can be used stably for a long time within the temperature range.

For example, when the electrochemical cell stack has a structure in which the heat exchanger 12 is not disposed between the small unit cell stacks 11, as shown in FIG. 14, the single cells stacked in the electrochemical cell stack The temperature distribution of the single cell increases in the vertical direction, and the efficiency of the entire stack tends to decrease. On the other hand, the electrochemical cell stack 10 can easily control the temperature distribution of the plurality of single cells 13 stacked in the stack by providing the heat exchanger 12 between the small unit cell stacks 11. . For this reason, as shown in FIG. 15, the electrochemical cell stack 10 has all the temperatures of the plurality of single cells 13 stacked in the stack within a temperature range in which oxygen ions can effectively pass through the solid electrolyte membrane 21. Therefore, the operation efficiency of the entire electrochemical cell stack 10 can be improved.

Moreover, the electrochemical cell stack 10 can improve the gas sealing property of the single cell 13 by providing the gas sealing portion 35 between the separator 17 and the cell holder 19.

Further, in the electrochemical cell stack 10, by providing the metal foil 55 between the small unit cell stack 11 and the heat exchanger 12, the tolerance for deformation of the small unit cell stack 11 increases, and the entire stack is robust. Can be improved, and damage to the gas seal portion 35 can be suppressed.

In the present embodiment, the solid electrolyte membrane 21, the hydrogen electrode 23, and the hydrogen electrode porous substrate 24 are fitted in the recess 19a of the cell holder 19, but as shown in FIG. The end of the extremely porous substrate 24 may be covered with the cell end cover 56 and fitted into the recess 19a. The cell end cover 56 can be formed using a stable metal, glass, ceramics, or the like that does not react with the reaction gas supplied to the electrochemical cell 14 or peripheral members under operating conditions. Since the hydrogen electrode 23 and the hydrogen electrode porous substrate 24 are fixed to the recess 19a via the cell end cover 56, the flatness and thickness uniformity of the end face can be adjusted more strictly. Higher robustness can be imparted by suppressing the influence of the flatness and thickness of the end portion of the electrochemical cell 14 on the property.

Further, as shown in FIG. 17, a seal layer 57 may be provided between the end portions of the solid electrolyte membrane 21, the hydrogen electrode 23, and the hydrogen electrode porous substrate 24 and the cell holder 19. By providing the sealing layer 57 between the solid electrolyte membrane 21, the hydrogen electrode 23 and the hydrogen electrode porous substrate 24 and the cell end cover 56, the solid electrolyte membrane 21, the hydrogen electrode 23 and the hydrogen electrode porous substrate 24 are provided. And the gas seal between the cell holder 19 can be further enhanced.

Further, in the present embodiment, as shown in FIG. 18, an insulating strength auxiliary portion 58 may be provided outside the gas seal portion 35. Thereby, while maintaining the insulation with the inside of the electrochemical cell 14, gas sealing performance can be maintained for a longer period of time, and the strength of the electrochemical cell stack 10 can be further improved.

In the present embodiment, the electrochemical cell stack 10 is an internal manifold system in which the separator 17 is provided with the through oxygen passage 31 and the penetration fuel passage 32 and the gas introduction passage for the reaction gas is arranged inside the separator 17. Although a case has been described, the present invention is not limited to this. For example, the grooved oxygen flow path 33 and the grooved fuel flow path 34 are extended to the end of the separator 17, and the penetrating oxygen flow path 31 and the penetrating fuel flow path 32 are provided outside the separator 17. The same applies to an external manifold system in which the flow path 31 and the grooved oxygen flow path 33 are connected, the through fuel flow path 32 and the grooved fuel flow path 34 are connected, and the reaction gas is circulated. Can do.

As described above, the electrochemical cell stack 10 is a solid oxide electrolytic cell (SOEC) that electrolyzes water to produce hydrogen, or a solid oxide fuel cell (SOFC) that generates power using hydrogen as a fuel. Since it can be used effectively, the electrochemical cell stack 10 is used as a solid oxide electrolytic cell and a solid oxide fuel cell, so that the combined electric power of the solid oxide electrolytic cell and the solid oxide fuel cell can be obtained. It can be used effectively as a system.

[Second Embodiment]
<Power system>
The power system according to this embodiment includes a solid oxide electrolytic cell that electrolyzes water vapor, a solid oxide fuel cell that generates power using a reducing agent and an oxidizing agent, and heat generated by the solid oxide fuel cell. The solid oxide electrolysis cell and the solid oxide fuel cell include the electrochemical cell stack according to the first embodiment. In this embodiment, a case where the power system is used as a hydrogen power storage system will be described. Therefore, in this embodiment, hydrogen is used as the reducing agent and oxygen is used as the oxidizing agent.

FIG. 19 is a diagram simply showing the configuration of the power system according to the present embodiment. As shown in FIG. 19, a power system (hydrogen power storage system) 60 includes a solid oxide electrolytic cell (SOEC) 61, a solid oxide fuel cell (SOFC) 62, and a hydrogen storage unit (reducing agent storage). Part) 63, an oxygen storage part (oxidant storage part) 64, a heat storage part 65, and a thermal circulation line L11. In the present embodiment, the electrochemical cell stack 10 according to the first embodiment is used as the solid oxide electrolytic cell 61 and the solid oxide fuel cell 62.

Steam is supplied to the small unit cell stack 11 of the solid oxide electrolytic cell 61 from the outside through the water supply line L12. In the solid oxide electrolytic cell 61, the water vapor supplied through the water supply line L12 is electrolyzed into oxygen and hydrogen using electric power supplied from the outside.

The water vapor supplied to the solid oxide electrolytic cell 61 is supplied to the solid oxide electrolytic cell 61 after being heated up to about 800 ° C., for example, and is electrolyzed in the solid oxide electrolytic cell 61. Therefore, most of them are in the gas phase.

Also, as the electric power supplied from the outside to the solid oxide electrolytic cell 61, for example, electric power obtained by using natural energy such as solar power generation, wind power generation, or hydroelectric power generation can be used.

The hydrogen generated in the solid oxide electrolytic cell 61 is supplied to and stored in the hydrogen storage unit 63, and the oxygen generated in the solid oxide electrolytic cell 61 is supplied to and stored in the oxygen storage unit 64.

Further, the heat supplied to the heat exchanger 12 of the solid oxide electrolytic cell 61 is released after being used for heat exchange with the small unit cell stack 11.

Hydrogen stored in the hydrogen storage unit 63 and oxygen stored in the oxygen storage unit 64 are supplied to the small unit cell stack 11 of the solid oxide fuel cell 62.

In the small unit cell stack 11 of the solid oxide fuel cell 62, electric power is generated using hydrogen supplied from the hydrogen storage unit 63 and oxygen supplied from the oxygen storage unit 64.

Further, heat is supplied to the heat exchanger 12 of the solid oxide electrolytic cell 61 from an external heat source to the heat exchanger 12, and heat is exchanged with the small unit cell stack 11 to be heated. The heat after heat exchange in the heat exchanger 12 is discharged to a thermal circulation line L11 that connects the solid oxide electrolytic cell 61 and the solid oxide fuel cell 62. The heat discharged from the heat exchanger 12 is supplied to the heat storage unit 65 through the heat circulation line L11 and stored in the heat storage unit 65.

As the heat storage unit 65, for example, a heat storage container (not shown) in which a plurality of capsules (not shown) of a ceramic material such as a silicon carbide sintered body in which a heat storage material is enclosed can be used. . As the heat storage material, for example, a latent heat storage material such as sodium chloride, potassium chloride, magnesium chloride, calcium chloride, lithium fluoride, lithium carbonate, sodium carbonate, or potassium carbonate is used. The heat storage container forms a flow path for the medium flowing around the capsule.

The heat stored in the heat storage unit 65 is supplied to the heat exchanger 12 of the solid oxide electrolytic cell 61 through the thermal circulation line L11 and used for heat exchange with the small unit cell stack 11, and then released. Is done.

Thus, the power system 60 includes the solid oxide electrolytic cell 61, the solid oxide fuel cell 62, and the thermal circulation line L11. In this system, the solid oxide fuel cell 62 generates electric power, and the heat generated in the solid oxide fuel cell 62 is supplied to the heat exchanger 12 during electrolysis in the solid oxide electrolytic cell 61 as a heat storage unit. The heat can be stored in 65. The power generation that occurs in the solid oxide fuel cell 62 is an exothermic reaction, and the electrolysis that occurs in the solid oxide electrolytic cell 61 is an endothermic reaction. Therefore, according to the electric power system 60, the heat generated in each small unit cell stack 11 in the solid oxide fuel cell 62 is discharged to the outside through the heat exchanger 12, and is stored in the heat storage unit 65, and the heat storage unit By supplying the heat stored in 65 to each heat exchanger 12 of the solid oxide electrolytic cell 61, the reaction heat generated during power generation in the small unit cell stack 11 of the solid oxide fuel cell 62 is reused. Therefore, the overall energy efficiency of the power system 60 can be improved.

In the present embodiment, a hydrogen storage unit 63 and an oxygen storage unit 64 are provided, and hydrogen and oxygen supplied to the solid oxide fuel cell 62 are hydrogen stored in the hydrogen storage unit 63 and the oxygen storage unit 64. In addition, hydrogen and oxygen supplied from the outside may be used.

In this embodiment, the heat storage unit 65 is provided to store the heat discharged from the solid oxide fuel cell 62. However, the heat storage unit 65 is directly supplied to the solid oxide electrolytic cell 61 without storing heat. May be.

In the present embodiment, the case where the power system is a hydrogen power storage system has been described. However, the present invention is not limited to this, and the power system is applied to a power system that uses other fuel as a fuel source. You can also. Further, the reducing agent is not limited to hydrogen and the oxidizing agent is not limited to oxygen. Any gas can be used as long as the reducing agent is a gas containing hydrogen and the oxidizing agent is a gas containing oxygen.

According to the embodiment described above, the solid electrolyte membrane can be used stably for a long time within a temperature range where the solid electrolyte membrane functions effectively.

As described above, the embodiment according to the present invention has been described. However, the above-described embodiment is presented as an example, and is not intended to limit the scope of the invention. The novel embodiment can be implemented in various other forms, and various combinations, omissions, replacements, changes, and the like can be made without departing from the spirit 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 Electrochemical cell stack 11 Small unit cell stack 12 Heat exchanger (heat exchanger)
13 Single cell 14 Electrochemical cell 15 Current collector (first current collector)
16 Current collector (second current collector)
17 Separator 19 Cell holder 21 Solid electrolyte membrane (electrolyte membrane)
22 Oxygen electrode 23 Hydrogen electrode 24 Hydrogen electrode porous substrate 28 Hole 31 Through oxygen flow path 32 Through fuel flow path 33 Grooved oxygen flow path 34 Grooved fuel flow path 35 Gas seal part 41 Aggregate particle 42 Bonded fine particle 43 Laminate (particulate current collecting layer)
44 Conductive layer 45 Metal particle 46 Fibrous material 47 Fibrous current collecting layer 48 Metal fiber 49 Ceramic fiber 50 Filler 51 Heat transport medium gas 52 Heat transport pipe 55 Metal foil (buffer part)
56 Cell end cover 57 Seal layer 58 Reinforcement material 60 Power system 61 Solid oxide electrolytic cell (SOEC)
62 Solid oxide fuel cell (SOFC)
63 Hydrogen storage part (reducing agent storage part)
64 Oxygen storage (oxidizer storage)
65 Heat storage section L11 Thermal circulation line L12 Water supply line

Claims

A current collector and a separator on both surfaces of an electrochemical cell comprising an electrolyte membrane, an oxygen electrode provided on one main surface of the electrolyte membrane, and a hydrogen electrode provided on the other main surface of the electrolyte membrane. A small unit cell stack including one or more single cells provided with:
A heat exchanging unit that is provided between one of or both of the small unit cell stacks and one end of the small unit cell stack, and is capable of exchanging heat with the small unit cell stack;
An electrochemical cell stack comprising:
The electrochemical cell stack according to claim 1, wherein the heat exchanging unit recovers heat generated by power generation in the single cell or supplies heat necessary for electrolysis in the single cell.
The electrochemical cell stack according to claim 1 or 2, wherein the small unit cell stack includes 3 to 30 single cells.
A cell holder provided so as to surround the hydrogen electrode and the current collector on the hydrogen electrode side, and fixing an end of the hydrogen electrode and the current collector on the hydrogen electrode side;
A gas seal part including glass provided between the cell holder and the separator;
The electrochemical cell stack according to any one of claims 1 to 3, further comprising:
The electrochemical cell stack according to any one of claims 1 to 4, further comprising a buffer unit between the small unit cell stack and the heat exchange unit.
The electrochemical cell stack according to claim 4 or 5, wherein the glass transition temperature of the glass is 800 ° C or higher.
The electrochemical cell stack according to any one of claims 1 to 6, wherein the gas seal portion further includes a strength auxiliary portion having insulating properties on an outer periphery of the small unit cell stack.
The electrochemical cell stack according to any one of claims 1 to 7, wherein the current collector is formed of a mesh shape, a cloth shape, or a porous body.
The porous body has a particulate current collecting layer including aggregate particles and the aggregate particles, or a combined fine particle that combines the aggregate particles with the oxygen electrode and the hydrogen electrode, and a conductive fibrous shape. A conductive layer is provided on the surface of any one or both of a layer comprising a fibrous current collecting layer made of a substance and the particulate current collecting layer, and the aggregate particles and the binding fine particles of the particulate current collecting layer. 9. The electrochemical cell stack according to claim 8, wherein the electrochemical cell stack is any one of a layer including a metal layer, a layer including metal particles and aggregate particles coated with the conductive layer, and a layer including metal fibers and ceramic fibers.
The electrochemical cell stack according to any one of claims 1 to 9, wherein the current collector includes a metal paste and a foam material.
A solid oxide electrolytic cell for electrolyzing water vapor;
A solid oxide fuel cell that generates electricity using a reducing agent and an oxidizing agent;
A heat circulation line for supplying heat generated in the solid oxide fuel cell to the solid oxide electrolytic cell;
Comprising
A power system, wherein the solid oxide electrolytic cell and the solid oxide fuel cell comprise the electrochemical cell stack according to any one of claims 1 to 10.
A heat storage section that is provided in the heat circulation line and stores heat generated in the solid oxide fuel cell;
The power system according to claim 11, wherein the heat stored in the heat storage unit is supplied to the solid oxide electrolytic cell.
Further comprising a reducing agent storage unit for storing a reducing agent generated by the operation of the solid oxide electrolytic cell;
The electric power system according to claim 11 or 12, wherein the reducing agent stored in the reducing agent storage unit is supplied to the solid oxide fuel cell.
Further comprising an oxidant storage unit for storing an oxidant generated by the operation of the solid oxide electrolytic cell;
The power system according to any one of claims 11 to 13, wherein the oxidant stored in the oxidant storage unit is supplied to the solid oxide fuel cell.