Patent Publication Number: US-2023135982-A1

Title: Electrochemical cell device

Description:
TECHNICAL FIELD 
     The present disclosure relates to an electrochemical cell device. The present application claims a priority based on Japanese Patent Application No. 2020-072919 filed on Apr. 15, 2020, the entire content of which is incorporated herein by reference. 
     BACKGROUND ART 
     PTL 1 (WO 2019/244480) describes a fuel cell. The fuel cell described in PTL 1 includes a solid electrolyte layer, an anode, a cathode, an anode side current collector, and a cathode side current collector. 
     The anode and the cathode sandwich the solid electrolyte layer (hereinafter, the solid electrolyte layer sandwiched between the anode and the cathode will be referred to as “cell”). The anode side current collector and the cathode side current collector sandwich the cell. Each of the anode side current collector and the cathode side current collector is constituted of a metal porous body sheet composed of a metal porous body having a framework with a three-dimensional network structure. 
     CITATION LIST 
     Patent Literature 
     
         
         PTL 1: WO 2019/244480 
       
    
     SUMMARY OF INVENTION 
     An electrochemical cell device according to the present disclosure includes: a cell having a first main surface and a second main surface opposite to the first main surface; a first current collector having a third main surface facing the first main surface; and a second current collector having a fourth main surface facing the second main surface. The cell is warped to protrude from the second main surface toward the first main surface. The third main surface is provided with a recess at a position facing a central portion of the first main surface. The fourth main surface includes a protrusion at a position facing a central portion of the second main surface. Each of the first current collector and the second current collector is constituted of one or more metal porous body sheets each composed of a metal porous body having a framework with a three-dimensional network structure. The central portion of the first main surface includes a portion of the first main surface with a longest distance from a flat reference surface when the cell is placed on the reference surface such that the second main surface faces the reference surface. The central portion of the second main surface includes a portion of the second main surface with a longest distance from the reference surface when the cell is disposed on the reference surface such that the second main surface faces the reference surface. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1 A  is a cross sectional view of an electrochemical cell device  100 . 
         FIG.  1 B  is an enlarged cross sectional view of a cell  10 . 
         FIG.  2    is a plan view of cell  10 . 
         FIG.  3    is a schematic cross sectional view showing a shape of warpage of cell  10 . 
         FIG.  4    is a plan view of a current collector  20 . 
         FIG.  5    is a cross sectional view at V-V of  FIG.  4   . 
         FIG.  6    is a plan view of a current collector  30 . 
         FIG.  7    is a cross sectional view at VII-VII of  FIG.  6   . 
         FIG.  8    is a plan view of a current collector  20  of an electrochemical cell device  200 . 
         FIG.  9    is a cross sectional view at IX-IX of  FIG.  8   . 
         FIG.  10    is a plan view of a current collector  30  of electrochemical cell device  200 . 
         FIG.  11    is a cross sectional view at XI-XI of  FIG.  10   . 
         FIG.  12    is a cross sectional view of a current collector  20  of an electrochemical cell device  300 . 
         FIG.  13    is a cross sectional view of a current collector  30  of electrochemical cell device  300 . 
     
    
    
     DETAILED DESCRIPTION 
     Problem to be Solved by the Present Disclosure 
     In the fuel cell according to PTL 1, a cell may be warped. When the cell is warped, spaces are formed between the cell and the anode side current collector and between the cell and the cathode side current collector (contact between the cell and each current collector is deteriorated). 
     The present disclosure provides an electrochemical cell device to reduce a space between a cell and a current collector. 
     Advantageous Effect of the Present Disclosure 
     According to the electrochemical cell device of the present disclosure, the space between the cell and the current collector can be reduced. 
     DESCRIPTION OF EMBODIMENTS 
     First, embodiments of the present disclosure are listed and described. 
     (1) An electrochemical cell device according to one embodiment includes: a cell having a first main surface and a second main surface opposite to the first main surface; a first current collector having a third main surface facing the first main surface; and a second current collector having a fourth main surface facing the second main surface. The cell is warped to protrude from the second main surface toward the first main surface. The third main surface is provided with a recess at a position facing a central portion of the first main surface. The fourth main surface includes a protrusion at a position facing a central portion of the second main surface. Each of the first current collector and the second current collector is constituted of one or more metal porous body sheets each composed of a metal porous body having a framework with a three-dimensional network structure. The central portion of the first main surface includes a portion of the first main surface with a longest distance from a flat reference surface when the cell is placed on the reference surface such that the second main surface faces the reference surface. The central portion of the second main surface includes a portion of the second main surface with a longest distance from the reference surface when the cell is disposed on the reference surface such that the second main surface faces the reference surface. 
     According to the electrochemical cell device of (1), a space between the cell and each current collector can be reduced. 
     (2) In the electrochemical cell device of (1), the one or more metal porous body sheets of the first current collector may be a first metal porous body sheet and a second metal porous body sheet. The first metal porous body sheet and the second metal porous body sheet may be disposed side by side in a plane orthogonal to a thickness direction of the first current collector. A first through hole may be formed in the second metal porous body sheet at a position corresponding to the recess so as to extend through the second metal porous body sheet in a thickness direction of the second metal porous body sheet. The first metal porous body sheet may be disposed in the first through hole. A thickness of the second metal porous body sheet may be more than a thickness of the first metal porous body sheet. The recess may be defined by an inner peripheral surface of the first through hole and a main surface of the first metal porous body sheet. 
     According to the electrochemical cell device of (2), the space between the cell and the current collector can be reduced. 
     (3) In the electrochemical cell device of (2), a value obtained by subtracting the thickness of the first metal porous body sheet from the thickness of the second metal porous body sheet may be equal to a warpage amount of the cell. 
     According to the electrochemical cell device of (3), the space between the cell and the current collector can be further reduced. 
     (4) In the electrochemical cell device of (1), the one or more metal porous body sheets of the first current collector may be a first metal porous body sheet and a second metal porous body sheet. The first metal porous body sheet and the second metal porous body sheet may be disposed to be stacked on each other such that the second metal porous body sheet is located on the third main surface side in a thickness direction of the first current collector. A first through hole may be formed in the second metal porous body sheet at a position corresponding to the recess so as to extend through the second metal porous body sheet in a thickness direction of the second metal porous body sheet. 
     (5) In the electrochemical cell device of any one of (1) to (4), the one or more metal porous body sheets of the second current collector may be a third metal porous body sheet and a fourth metal porous body sheet. The third metal porous body sheet and the fourth metal porous body sheet may be disposed side by side in a plane orthogonal to a thickness direction of the second current collector. A second through hole may be formed in the fourth metal porous body sheet at a position corresponding to the protrusion so as to extend through the fourth metal porous body sheet in a thickness direction of the fourth metal porous body sheet. The third metal porous body sheet may be disposed in the second through hole. A thickness of the third metal porous body sheet may be more than a thickness of the fourth metal porous body sheet. 
     According to the electrochemical cell device of (5), the space between the cell and the current collector can be reduced. 
     (6) In the electrochemical cell device of (1) to (4), a value obtained by subtracting the thickness of the fourth metal porous body sheet from the thickness of the third metal porous body sheet may be equal to a warpage amount of the cell. 
     According to the electrochemical cell device of (6), the space between the cell and the current collector can be further reduced. 
     (7) In the electrochemical cell device of any one of (1) to (4), the one or more metal porous body sheets of the second current collector may be a third metal porous body sheet and a fourth metal porous body sheet. The third metal porous body sheet and the fourth metal porous body sheet may be disposed to be stacked on each other such that the fourth metal porous body sheet is located on the fourth main surface side in a thickness direction of the second current collector. The fourth metal porous body sheet may constitute the protrusion. 
     According to the electrochemical cell device of (7), the space between the cell and the current collector can be reduced. 
     (8) In the electrochemical cell device of (1) to (7), the first current collector may be a cathode side current collector, and the second current collector may be an anode side current collector. 
     According to the electrochemical cell device of (8), the space between the cell and the current collector can be reduced. 
     (9) In the electrochemical cell device of (8), the framework of each of the one or more metal porous body sheets of the first current collector may contain nickel and cobalt. A coating weight of each of the one or more metal porous body sheets of the first current collector may be 900 g/m 2  or less. 
     According to the electrochemical cell device of (9), the space between the cell and the current collector can be reduced. 
     (10) In the electrochemical cell device of (8), the framework of each of the one or more metal porous body sheets of the second current collector may contain nickel. A coating weight of each of the one or more metal porous body sheets of the second current collector may be 1000 g/m 2  or less. 
     (11) In the electrochemical cell device according to (1) to (10), a value obtained by dividing a warpage amount of the cell by a maximum width of the cell when viewed in a plan view may be 1/1000 or more. 
     According to the electrochemical cell device of (11), even when the warpage of the cell is large, the space between the cell and the current collector can be reduced. 
     (12) The electrochemical cell device of (1) to (11) may be a solid oxide fuel cell. 
     According to the electrochemical cell device of (12), contact between the cell and the current collector can be improved, thus resulting in increased output voltage in the solid oxide fuel cell. 
     (13) The electrochemical cell device of (1) to (11) may be a solid oxide electrolysis cell. 
     According to the electrochemical cell device of (13), contact between the cell and the current collector can be improved, thus resulting in lowered electrolytic voltage in the solid oxide electrolysis cell. 
     Details of Embodiments of the Present Disclosure 
     Next, embodiments of the present disclosure will be described with reference to figures. Here, the same or corresponding portions are denoted by the same reference characters, and the same explanation will not be described repeatedly. 
     First Embodiment 
     Hereinafter, a configuration of an electrochemical cell device (hereinafter, referred to as “electrochemical cell device  100 ”) according to a first embodiment will be described. 
     Electrochemical cell device  100  is a solid oxide fuel cell (SOFC). Although electrochemical cell device  100  may be a solid oxide electrolysis cell (SOEC), the SOFC will be described below as an exemplary electrochemical cell device  100 . 
       FIG.  1 A  is a cross sectional view of electrochemical cell device  100 .  FIG.  1 A  shows a structure of a single-cell included in electrochemical cell device  100 . Electrochemical cell device  100  is formed by stacking a plurality of single-cell structures. Further,  FIG.  1 A  does not illustrate warpage of a cell  10 , a recess  20   c , and a protrusion  30   c , which will be described later.  FIG.  1 B  is an enlarged cross sectional view of cell  10 . As shown in  FIGS.  1 A and  1 B , electrochemical cell device  100  includes cell  10 , a current collector  20 , a current collector  30 , an interconnector  40 , and an interconnector  50 . 
     Cell  10  has a main surface  10   a  and a main surface  10   b . Main surface  10   b  is a surface opposite to main surface  10   a . Cell  10  includes a solid electrolyte layer  11 , a cathode  12 , an anode  13 , and an intermediate layer  14 . 
     Solid electrolyte layer  11  is a layer composed of a solid electrolyte. For example, solid electrolyte layer  11  is composed of an oxide (YSZ) of zirconium (Zr) doped with yttrium (Y). Cathode  12  is composed of, for example, LSC (oxide of lanthanum (La) strontium (Sr) cobalt (Co)). Anode  13  is composed of, for example, a mixture of YSZ and an oxide of nickel (Ni 2 O). Intermediate layer  14  is composed of, for example, an oxide (GDC) of cerium (Ce) doped with gadolinium (Gd). 
     Cathode  12  constitutes a main surface  10   a  of cell  10 . Anode  13  constitutes a main surface  10   b  of cell  10 . Solid electrolyte layer  11  is disposed between cathode  12  and anode  13 . Intermediate layer  14  is disposed between solid electrolyte layer  11  and cathode  12 . Solid electrolyte layer  11  and anode  13  are in contact with each other. 
       FIG.  2    is a plan view of cell  10 . As shown in  FIG.  2   , cell  10  has a circular shape when viewed in a plan view. However, the planar shape of cell  10  is not limited thereto. Cell  10  may have a quadrangular shape when viewed in a plan view. 
       FIG.  3    is a schematic cross sectional view showing a shape of warpage of cell  10 . As shown in  FIG.  3   , cell  10  is warped. For example, cell  10  is warped to protrude from the main surface  10   b  side toward the main surface  10   a  side. A warpage amount of cell  10  (hereinafter, referred to as “warpage amount WA”) is, for example, 100 μm or more. Warpage amount WA may be 1000 μm or more. 
     Warpage amount WA is measured by the following method. First, cell  10  is placed on a flat reference surface. Second, LK-G35 provided by Keyence is used to measure a distance (hereinafter, referred to as “distance L”) between the reference surface and a position (hereinafter, referred to as “apex P”) on main surface  10   a  with the longest distance from the reference surface. Apex P is located at the central portion of cell  10  (the central portion of main surface  10   a ) when viewed in a plan view. Third, the thickness of cell  10  (hereinafter, referred to as “thickness T”) is subtracted from distance L. In this way, warpage amount WA is measured. 
     The maximum width of cell  10  when viewed in a plan view is defined as a width W max  (see  FIG.  2   ). A value obtained by dividing warpage amount WA by width W max  is, for example, 1/1000 or more. The value obtained by dividing warpage amount WA by width W max  may be 1/100 or more. When the planar shape of cell  10  is a circular shape, width W max  is equal to the diameter of the circular shape. When the planar shape of the cell is a quadrangular shape, width W max  is equal to the length of the diagonal of the quadrangular shape. 
     As shown in  FIG.  1 A , current collector  20  is disposed on main surface  10   a , and current collector  30  is disposed on main surface  10   b . From another viewpoint, it can be said that cell  10  is sandwiched between current collector  20  and current collector  30 . Current collector  20  is a cathode side current collector, and current collector  30  is an anode side current collector. 
     Current collector  20  has a main surface  20   a  and a main surface  20   b . Main surface  20   a  faces main surface  10   a . Main surface  20   b  is a surface opposite to main surface  20   a .  FIG.  4    is a plan view of current collector  20 .  FIG.  5    is a cross sectional view at V-V of  FIG.  4   . As shown in  FIGS.  4  and  5   , main surface  20   a  is provided with recess  20   c . Main surface  20   a  is depressed toward the main surface  20   b  side in recess  20   c . Recess  20   c  is disposed at a position facing the central portion of main surface  10   a.    
     Current collector  20  is constituted of a metal porous body sheet  21  and a metal porous body sheet  22 . Each of metal porous body sheet  21  and metal porous body sheet  22  is composed of a metal porous body having a framework with a three-dimensional network structure. 
     The framework of the metal porous body of each of metal porous body sheet  21  and metal porous body sheet  22  contains, for example, nickel (Ni) and cobalt. The coating weight of each of metal porous body sheet  21  and metal porous body sheet  22  is preferably 900 g/m 2  or less. The coating weight of metal porous body sheet  21  (metal porous body sheet  22 ) is a value obtained by dividing the weight of metal porous body sheet  21  (metal porous body sheet  22 ) by the area of the main surface of metal porous body sheet  21  (metal porous body sheet  22 ). 
     Current collector  20  has a circular shape when viewed in a plan view. Metal porous body sheet  21  has a circular shape when viewed in a plan view. Metal porous body sheet  22  has an annular shape when viewed in a plan view. That is, a through hole  22   a  is formed in metal porous body sheet  22  so as to extend through metal porous body sheet  22  in the thickness direction of metal porous body sheet  22 . Through hole  22   a  is formed at a position corresponding to recess  20   c.    
     The thickness (hereinafter, referred to as “thickness T 2 ”) of metal porous body sheet  22  is larger than the thickness (hereinafter, referred to as “thickness T 1 ”) of metal porous body sheet  21 . Metal porous body sheet  21  and metal porous body sheet  22  are disposed side by side (disposed not to be stacked on each other) in a plane orthogonal to the thickness direction of current collector  20 . Metal porous body sheet  21  is disposed in through hole  22   a . Therefore, metal porous body sheet  21  and through hole  22   a  constitute recess  20   c.    
     Current collector  30  has a main surface  30   a  and a main surface  30   b . Main surface  30   a  faces main surface  10   b . Main surface  30   b  is a surface opposite to main surface  30   a .  FIG.  6    is a plan view of current collector  30 .  FIG.  7    is a cross sectional view at VII-VII of  FIG.  6   . As shown in  FIGS.  6  and  7   , main surface  30   a  has a protrusion  30   c . At protrusion  30   c , main surface  30   a  protrudes opposite to main surface  30   b . Protrusion  30   c  is disposed at a position facing the central portion of main surface  10   b.    
     Current collector  30  is constituted of a metal porous body sheet  31  and a metal porous body sheet  32 . Each of metal porous body sheet  31  and metal porous body sheet  32  is constituted of a metal porous body having a framework with a three-dimensional network structure. 
     The framework of the metal porous body of each of metal porous body sheet  31  and metal porous body sheet  32  contains, for example, nickel. The coating weight of each of metal porous body sheet  31  and metal porous body sheet  32  is preferably 1000 g/m 2  or less. The coating weight of metal porous body sheet  31  (metal porous body sheet  32 ) is a value obtained by dividing the weight of metal porous body sheet  31  (metal porous body sheet  32 ) by the area of the main surface of metal porous body sheet  31  (metal porous body sheet  32 ). 
     Current collector  30  has a circular shape when viewed in a plan view. Metal porous body sheet  31  has a circular shape when viewed in a plan view. Metal porous body sheet  32  has an annular shape when viewed in a plan view. That is, a through hole  32   a  is formed in metal porous body sheet  32  so as to extend through metal porous body sheet  32  in the thickness direction of metal porous body sheet  32 . Through hole  32   a  is formed at a position corresponding to protrusion  30   c.    
     The thickness (hereinafter, referred to as “thickness T 3 ”) of metal porous body sheet  31  is larger than the thickness (hereinafter, referred to as “thickness T 4 ”) of metal porous body sheet  32 . Metal porous body sheet  31  and metal porous body sheet  32  are disposed side by side (disposed not to be stacked on each other) in a plane orthogonal to the thickness direction of current collector  30 . Metal porous body sheet  31  is disposed in through hole  32   a . Therefore, metal porous body sheet  31  constitutes protrusion  30   c.    
     A value obtained by subtracting thickness T 1  from thickness T 2  is preferably equal to warpage amount WA. A value obtained by subtracting thickness T 4  from thickness T 3  is preferably equal to warpage amount WA. It should be noted that a case where the value obtained by subtracting thickness T 1  from thickness T 2  falls within a range of 0.95 time or more and 1.05 times or less as large as warpage amount WA is included in the case where “the value obtained by subtracting thickness T 1  from thickness T 2  is equal to warpage amount WA”, and a case where the value obtained by subtracting thickness T 4  from thickness T 3  falls within a range of 0.95 time or more and 1.05 times or less as large as warpage amount WA is included in the case where “the value obtained by subtracting thickness T 4  from thickness T 3  is equal to warpage amount WA”. 
     Metal porous body sheet  22  may be concentrically divided into a plurality of metal porous body sheets. In this case, a metal porous body sheet disposed on an outer side is thicker. Metal porous body sheet  32  may be concentrically divided into a plurality of metal porous body sheets. In this case, a metal porous body sheet disposed on an outer side is thinner. 
     As shown in  FIG.  1 A , interconnector  40  is disposed on main surface  20   b  and interconnector  50  is disposed on main surface  30   b . From another viewpoint, it can be said that cell  10 , current collector  20 , and current collector  30  are sandwiched between interconnector  40  and interconnector  50 . A groove  41  is formed in the main surface of interconnector  40  on the current collector  20  side, and a groove  51  is formed in the main surface of interconnector  50  on the current collector  30  side. Each of interconnector  40  and interconnector  50  is composed of an electrically conductive material. 
     Hereinafter, effects of electrochemical cell device  100  will be described. 
     In electrochemical cell device  100 , since cell  10  is warped to protrude from main surface  10   b  toward main surface  10   a , spaces are formed between main surface  10   a  and main surface  20   a  and between main surface  10   b  and main surface  30   a  when main surface  20   a  and main surface  30   a  are flat. This results in an increased contact electrical resistance value between cell  10  and current collector  20 , an increased contact electrical resistance value between cell  10  and current collector  30 , and a decreased output voltage from electrochemical cell device  100 . 
     However, in electrochemical cell device  100 , since main surface  20   a  is provided with recess  20   c  and main surface  30   a  has protrusion  30   c , main surface  20   a  is facilitated to conform to the shape of main surface  10   a  and main surface  30   a  is facilitated to conform to the shape of main surface  10   b , thereby reducing the spaces between main surface  10   a  and main surface  20   a  and between main surface  10   b  and main surface  30   a.    
     Therefore, according to electrochemical cell device  100 , the contact electrical resistance value between cell  10  and current collector  20  and the contact electrical resistance value between cell  10  and current collector  30  can be decreased, and the output voltage from electrochemical cell device  100  can be improved. 
     It should be noted that when electrochemical cell device  100  is an SOEC, the contact electrical resistance value between cell  10  and current collector  20  and the contact electrical resistance value between cell  10  and current collector  30  are decreased, with the result that the electrolytic voltage in electrochemical cell device  100  can be lowered. 
     When the framework of the metal porous body of each of metal porous body sheet  21  and metal porous body sheet  22  contains nickel and cobalt and the coating weight of the metal porous body of each of metal porous body sheet  21  and metal porous body sheet  22  is 900 g/m 2  or less, deformability of each of metal porous body sheet  21  and metal porous body sheet  22  can be ensured, so that main surface  20   a  is more facilitated to conform to the shape of main surface  10   a.    
     When the framework of the metal porous body of each of metal porous body sheet  31  and metal porous body sheet  32  contains nickel and the coating weight of the metal porous body of each of metal porous body sheet  31  and metal porous body sheet  32  is 900 g/m 2  or less, deformability of each of metal porous body sheet  31  and metal porous body sheet  32  can be ensured, so that main surface  30   a  is more facilitated to conform to the shape of main surface  10   b.    
     (Power Generation Test) 
     Hereinafter, a power generation test performed to confirm the effects of electrochemical cell device  100  will be described. 
     &lt;Samples&gt; 
     Electrochemical cells of samples 1 to 6 were provided for a power generation test. In each of samples 1 to 6, the shapes of cell  10 , current collector  20 , and current collector  30  were as shown in Table 1. It should be noted that although not shown in Table 1, in each of samples 1 to 6, the thickness and diameter of cell  10  were 0.4 mm and 100 mm, respectively. 
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Warpage 
                   
                   
               
               
                   
                 Amount WA 
                 Current Collector 20 
                 Current Collector 30 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 Sample 1 
                 100 
                 μm 
                 Metal Porous Body Sheet 21 
                 Metal Porous Body Sheet 31 
               
               
                   
                   
                   
                 (Thickness T1 = 400 μm) + 
                 (Thickness T3 = 500 μm) + 
               
               
                   
                   
                   
                 Metal Porous Body Sheet 22 
                 Metal Porous Body Sheet 32 
               
               
                   
                   
                   
                 (Thickness T2 = 500 μm) 
                 (Thickness T4 = 400 μm) 
               
               
                 Sample 2 
                 300 
                 μm 
                 Metal Porous Body Sheet 21 
                 Metal Porous Body Sheet 31 
               
               
                   
                   
                   
                 (Thickness T1 = 200 μm) + 
                 (Thickness T3 = 500 μm) + 
               
               
                   
                   
                   
                 Metal Porous Body Sheet 22 
                 Metal Porous Body Sheet 32 
               
               
                   
                   
                   
                 (Thickness T2 = 500 μm) 
                 (Thickness T4 = 200 μm) 
               
               
                 Sample 3 
                 1000 
                 μm 
                 Metal Porous Body Sheet 21 
                 Metal Porous Body Sheet 31 
               
               
                   
                   
                   
                 (Thickness T1 = 100 μm) + 
                 (Thickness T3 = 1100 μm) + 
               
               
                   
                   
                   
                 Metal Porous Body Sheet 22 
                 Metal Porous Body Sheet 32 
               
               
                   
                   
                   
                 (Thickness T2 = 1100 μm) 
                 (Thickness T4 = 100 μm) 
               
               
                 Sample 4 
                 2000 
                 μm 
                 Metal Porous Body Sheet 21 
                 Metal Porous Body Sheet 31 
               
               
                   
                   
                   
                 (Thickness T1 = 100 μm) + 
                 (Thickness T3 = 2100 μm) + 
               
               
                   
                   
                   
                 Metal Porous Body Sheet 22 
                 Metal Porous Body Sheet 32 
               
               
                   
                   
                   
                 (Thickness T2 = 2100 μm) 
                 (Thickness T4 = 100 μm) 
               
               
                 Sample 5 
                 100 
                 μm 
                 One Metal Porous Body 
                 One Metal Porous Body 
               
               
                   
                   
                   
                 Sheet Having Thickness of 
                 Sheet Having Thickness of 
               
               
                   
                   
                   
                 500 μm 
                 500 μm 
               
               
                 Sample 6 
                 1000 
                 μm 
                 One Metal Porous Body 
                 One Metal Porous Body 
               
               
                   
                   
                   
                 Sheet Having Thickness of 
                 Sheet Having Thickness of 
               
               
                   
                   
                   
                 1100 μm 
                 1100 μm 
               
               
                   
               
            
           
         
       
     
     As shown in Table 1, in each of samples 1 and 5, warpage amount WA was 100 μm. In sample 2, warpage amount WA was 300 μm. In each of samples 3 and 6, warpage amount WA was 1000 μm. In sample 4, warpage amount WA was 2000 μm. 
     In sample 1, a metal porous body sheet  21  having a thickness of 400 μm and a metal porous body sheet  22  having a thickness of 500 μm were used as current collector  20 , and a metal porous body sheet  31  having a thickness of 500 μm and a metal porous body sheet  32  having a thickness of 400 μm were used as current collector  30 . 
     In sample 2, a metal porous body sheet  21  having a thickness of 200 μm and a metal porous body sheet  22  having a thickness of 500 μm were used as current collector  20 , and a metal porous body sheet  31  having a thickness of 500 μm and a metal porous body sheet  32  having a thickness of 200 μm were used as current collector  30 . 
     In sample 3, a metal porous body sheet  21  having a thickness of 100 μm and a metal porous body sheet  22  having a thickness of 1100 μm were used as current collector  20 , and a metal porous body sheet  31  having a thickness of 1100 μm and a metal porous body sheet  32  having a thickness of 100 μm were used as current collector  30 . 
     In sample 4, a metal porous body sheet  21  having a thickness of 100 μm and a metal porous body sheet  22  having a thickness of 2100 μm were used as current collector  20 , and a metal porous body sheet  31  having a thickness of 2100 μm and a metal porous body sheet  32  having a thickness of 100 μm were used as current collector  30 . 
     In sample 5, one metal porous body sheet having a thickness of 500 μm was used as current collector  20 , and one metal porous body sheet having a thickness of 500 μm was used as current collector  30 . 
     In sample 6, one metal porous body sheet having a thickness of 1100 μm was used as current collector  20 , and one metal porous body sheet having a thickness of 1100 μm was used as current collector  30 . 
     &lt;Test Results&gt; 
     Table 2 shows an initial value of an output voltage between the anode and the cathode when a current of 0.5 A/cm 2  flows between the anode and the cathode at 750° C. 
     
       
         
           
               
               
             
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                 Output Voltage 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 Sample 1 
                 0.85 V 
               
               
                   
                 Sample 2 
                 0.86 V 
               
               
                   
                 Sample 3 
                 0.89 V 
               
               
                   
                 Sample 4 
                 0.90 V 
               
               
                   
                 Sample 5 
                 0.78 V 
               
               
                   
                 Sample 6 
                 0.70 V 
               
               
                   
                   
               
            
           
         
       
     
     As shown in Table 2, the output voltage of sample 1 was more than the output voltage of sample 5. The output voltage of sample 3 was more than the output voltage of sample 6. 
     In view of these comparisons, it was also experimentally revealed that since main surface  20   a  of current collector  20  is provided with recess  20   c  and main surface  30   a  of current collector  30  has protrusion  30   c , the space between cell  10  and current collector  20  and the space between cell  10  and current collector  30  can be decreased and the output voltage from electrochemical cell device  100  can be increased. 
     As warpage amount WA is larger, the spaces are more likely to be formed between cell  10  and current collector  20  and between cell  10  and current collector  30 , but a surface area of cell  10  contributing to an electrochemical reaction is increased. 
     The output voltage of sample 6 was less than the output voltage of sample 5. This is presumably due to the following reason: since warpage amount WA of sample 6 was more than warpage amount WA of sample 5, the space between cell  10  and current collector  20  and the space between cell  10  and current collector  30  were increased, thereby increasing the contact electrical resistance between cell  10  and current collector  20  and the contact electrical resistance between cell  10  and current collector  30 . 
     On the other hand, in each of samples 1 to 4, as warpage amount WA was larger, the output voltage was increased. In each of samples 1 to 4, each of the value obtained by subtracting thickness T 1  from thickness T 2  and the value obtained by subtracting thickness T 4  from thickness T 3  coincided with warpage amount WA. 
     In view of this, it was experimentally revealed that by increasing warpage amount WA while each of the value obtained by subtracting thickness T 1  from thickness T 2  and the value obtained by subtracting thickness T 4  from thickness T 3  coincides with warpage amount WA, the surface area of cell  10  contributing to the electrochemical reaction can be increased, in other words, the output voltage from electrochemical cell device  100  can be further increased, while reducing the space between cell  10  and current collector  20  and the space between cell  10  and current collector  30 . 
     Second Embodiment 
     Hereinafter, a configuration of an electrochemical cell device (hereinafter, referred to as “electrochemical cell device  200 ”) according to a second embodiment will be described. Here, the following mainly describes differences from the configuration of electrochemical cell device  100 , and the same explanation will not be described repeatedly. 
     Electrochemical cell device  200  includes a cell  10 , a current collector  20 , a current collector  30 , an interconnector  40 , and an interconnector  50 . Cell  10  is warped to protrude from main surface  10   b  toward main surface  10   a . Main surface  20   a  is provided with a recess  20   c , and main surface  30   a  has a protrusion  30   c . Regarding these points, the configuration of electrochemical cell device  200  is the same as the configuration of electrochemical cell device  100 . 
       FIG.  8    is a plan view of current collector  20  of electrochemical cell device  200 .  FIG.  9    is a cross sectional view at IX-IX of  FIG.  8   . As shown in  FIGS.  8  and  9   , in electrochemical cell device  200 , current collector  20  has a metal porous body sheet  23  and a metal porous body sheet  24 . Metal porous body sheet  23  has a circular shape when viewed in a plan view, for example. Metal porous body sheet  24  has an annular shape when viewed in a plan view, for example. 
     A through hole  24   a  is formed in metal porous body sheet  24  so as to extend through metal porous body sheet  24  in the thickness direction of metal porous body sheet  24 . Through hole  24   a  is disposed at a position corresponding to recess  20   c . Metal porous body sheet  23  and metal porous body sheet  24  are disposed to be stacked on each other in the thickness direction of current collector  20 . Metal porous body sheet  24  is disposed on the main surface  20   a  side. As a result, through hole  24   a  and metal porous body sheet  23  constitute recess  20   c.    
       FIG.  10    is a plan view of current collector  30  of electrochemical cell device  200 .  FIG.  11    is a cross sectional view at XI-XI of  FIG.  10   . As shown in  FIGS.  10  and  11   , current collector  30  has a metal porous body sheet  33  and a metal porous body sheet  34 . Each of metal porous body sheet  33  and metal porous body sheet  34  has a circular shape when viewed in a plan view, for example. The diameter of metal porous body sheet  33  is larger than the diameter of metal porous body sheet  34 . 
     Metal porous body sheet  33  and metal porous body sheet  34  are stacked on each other in the thickness direction of current collector  30 . Metal porous body sheet  34  is disposed on the main surface  30   a  side so as to correspond to the position of protrusion  30   c . As a result, metal porous body sheet  34  constitutes protrusion  30   c.    
     Hereinafter, effects of electrochemical cell device  200  will be described. 
     As with electrochemical cell device  100 , since main surface  20   a  is provided with recess  20   c  and main surface  30   a  has protrusion  30   c  in electrochemical cell device  200 , main surface  20   a  is facilitated to conform to the shape of main surface  10   a  and main surface  30   a  is facilitated to conform to the shape of main surface  10   b , thereby reducing the spaces between main surface  10   a  and main surface  20   a  and between main surface  10   b  and main surface  30   a . As a result, according to electrochemical cell device  200 , the contact electrical resistance value between cell  10  and current collector  20  and the contact electrical resistance value between cell  10  and current collector  30  can be decreased, and the output voltage from electrochemical cell device  100  can be improved. 
     Third Embodiment 
     Hereinafter, a configuration of an electrochemical cell device (hereinafter, referred to as “electrochemical cell device  300 ”) according to a third embodiment will be described. Here, the following mainly describes differences from the configuration of electrochemical cell device  100 , and the same explanation will not be described repeatedly. 
     Electrochemical cell device  300  includes a cell  10 , a current collector  20 , a current collector  30 , an interconnector  40 , and an interconnector  50 . Cell  10  is warped to protrude from main surface  10   b  toward main surface  10   a . Main surface  20   a  is provided with a recess  20   c , and main surface  30   a  has a protrusion  30   c . Regarding these points, the configuration of electrochemical cell device  300  is the same as the configuration of electrochemical cell device  100 . 
       FIG.  12    is a cross sectional view of current collector  20  of electrochemical cell device  300 .  FIG.  13    is a cross sectional view of current collector  30  of electrochemical cell device  300 . As shown in  FIGS.  12  and  13   , each of current collector  20  and current collector  30  is constituted of one metal porous body sheet (metal porous body sheet  25  and metal porous body sheet  35 ). 
     It should be noted that each of recess  20   c  of current collector  20  (metal porous body sheet  25 ) and protrusion  30   c  of current collector  30  (metal porous body sheet  35 ) can be formed by, for example, press working. 
     Hereinafter, effects of electrochemical cell device  300  will be described. 
     As with electrochemical cell device  100 , since main surface  20   a  is provided with recess  20   c  and main surface  30   a  has protrusion  30   c  in electrochemical cell device  300 , main surface  20   a  is facilitated to conform to the shape of main surface  10   a  and main surface  30   a  is facilitated to conform to the shape of main surface  10   b , thereby reducing the spaces between main surface  10   a  and main surface  20   a  and between main surface  10   b  and main surface  30   a . As a result, according to electrochemical cell device  300 , the contact electrical resistance value between cell  10  and current collector  20  and the contact electrical resistance value between cell  10  and current collector  30  are decreased, and the output voltage from electrochemical cell device  100  can be improved. 
     The embodiments disclosed herein are illustrative and non-restrictive in any respect. The scope of the present invention is defined by the terms of the claims, rather than the embodiments described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims. 
     REFERENCE SIGNS LIST 
     
         
           10 : cell;  10   a ,  10   b : main surface;  11 : solid electrolyte layer;  12 : cathode;  13 : anode;  14 : intermediate layer;  20 : current collector;  20   a ,  20   b : main surface;  20   c : recess;  21 : metal porous body sheet;  22 : metal porous body sheet;  22   a : through hole;  23 : metal porous body sheet;  24 : metal porous body sheet;  24   a : through hole;  25 : metal porous body sheet;  30 : current collector;  30   a : main surface;  30   b : main surface;  30   c : protrusion;  31 : metal porous body sheet;  32 : metal porous body sheet;  32   a : through hole;  33 ,  34 ,  35 : metal porous body sheet;  40 : interconnector;  41 : groove;  50 : interconnector;  51 : groove;  100 ,  200 ,  300 : electrochemical cell device; L: distance; P: apex; T, T 1 , T 2 , T 3 , T 4 : thickness; WA: warpage amount; W max : width.