Interconnector-electrochemical reaction single cell composite body, and electrochemical reaction cell stack

An electrochemical reaction cell stack comprising:

• a plurality of interconnector-electrochemical reaction unit cell composite bodies, at least one of the interconnector-electrochemical reaction unit cell composite bodies is an interconnector-electrochemical reaction unit cell composite body comprising:
• an electrochemical reaction unit cell including an electrolyte layer, and a cathode and an anode which face each other in a first direction with the electrolyte layer intervening therebetween;
• and
• an interconnector which has a first through hole defining a fuel gas flow channel and which interconnector is disposed on the anode side of the electrochemical reaction unit cell;
• and
• a sealing member which forms a fuel gas flow channel and which sealing member is disposed between the interconnector of one of two adjacent interconnector-electrochemical reaction unit cell composite bodies among the plurality of interconnector-electrochemical reaction unit cell composite bodies and the other interconnector-electrochemical reaction unit cell composite body, the electrochemical reaction cell stack being characterized in that:
• the interconnector of the one interconnector-electrochemical reaction unit cell composite body includes a coating forming a first surface of the interconnector, the first surface being located on a side of the interconnector opposite the anode;
• and
• the coating includes a first coating and a second coating having reduction resistance higher than that of the first coating, the first coating forming a first surface region which is a portion of the first surface of the interconnector and is located away from the first through hole, the second coating forming a second surface region which is a portion of the first surface of the interconnector, which second surface region surrounds the first through hole, and which second surface region is located between the first coating and the first through hole;
• and
• the inner peripheral contour of the first coating is located outward of the inner peripheral contour of the sealing member as viewed in the first direction;
• and
• the second coating contains chromia.