Abstract: To prevent a reduction in the performance of a unit cell due to a gas shortage in a cathode chamber. An electrochemical reaction unit includes a unit cell, a cathode-side member, and an anode-side member. The electrochemical reaction unit satisfies the following condition on at least one of supply and discharge sides of the cathode chamber. Condition: the distance between the midpoint between opposite end points of a cathode-side opening group including an opening of a cathode-side communication channel and the midpoint (specific point) between opposite end points of an anode-side supply opening group including an opening of an anode-side supply communication channel in a direction parallel to an inner circumferential surface of a cathode chamber hole is shorter than the distance between the centroid of a cathode-side gas channel hole and the specific point in the direction parallel to the inner circumferential surface of the cathode chamber hole.

Abstract: An electrochemical reaction cell stack including a plurality of unit cells and flat plate-shaped electrically conductive members arranged in a first direction. The electrically conductive members include: a first member having a first surface including a first flat portion and a protruding portion and a second member both located on the first side of the first member in the first direction, the second member having a second surface facing the first surface and including a second flat portion and a recessed portion facing the protruding portion. The thickness of the second member is larger than the thickness of the first member in the first direction. The depth of the recessed portion of the second member from the second flat portion is larger than the protruding length of the protruding portion of the first member from the first flat portion in the first direction.

Abstract: An electrochemical reaction cell stack includes an electrochemical reaction block including three or more electrochemical reaction units arranged in a first direction; a first heat-absorbing member which is disposed on one side of the electrochemical reaction block in the first direction and absorbs heat generated from the electrochemical reaction block; and a second heat-absorbing member which is disposed on the other side of the electrochemical reaction block in the first direction and absorbs heat generated from the electrochemical reaction block. An upstream electrochemical reaction unit is disposed between the first heat-absorbing member and the downstream electrochemical reaction unit disposed closest to the first heat-absorbing member, and an upstream electrochemical reaction unit is disposed between the second heat-absorbing member and the downstream electrochemical reaction unit disposed closest to the second heat-absorbing member.

Abstract: To prevent a reduction in the performance of a unit cell due to a gas shortage in a cathode chamber. An electrochemical reaction unit includes a unit cell, a cathode-side member, and an anode-side member. The electrochemical reaction unit satisfies the following condition on at least one of supply and discharge sides of the cathode chamber. Condition: the distance between the midpoint between opposite end points of a cathode-side opening group including an opening of a cathode-side communication channel and the midpoint (specific point) between opposite end points of an anode-side supply opening group including an opening of an anode-side supply communication channel in a direction parallel to an inner circumferential surface of a cathode chamber hole is shorter than the distance between the centroid of a cathode-side gas channel hole and the specific point in the direction parallel to the inner circumferential surface of the cathode chamber hole.

Abstract: An interconnector-electrochemical reaction unit cell composite body includes an electrochemical reaction unit cell and an interconnector. The interconnector has a plurality of combinations of protrusions protruding in the first direction and recesses provided on a side opposite the protrusions in the first direction and being concave toward the protrusions. At least one of the combinations is configured such that, as viewed in the first direction, the bottom of the recess is located on the side toward the open end of the recess. In a section parallel to the first direction, the recess is located within a width t2 of the protrusion in the second direction orthogonal to the first direction, and the width t1 of the recess in the second direction is smaller than the width t2.

Abstract: An electrochemical reaction cell stack including a plurality of unit cells and flat plate-shaped electrically conductive members arranged in a first direction. The electrically conductive members include: a first member having a first surface including a first flat portion and a protruding portion and a second member both located on the first side of the first member in the first direction, the second member having a second surface facing the first surface and including a second flat portion and a recessed portion facing the protruding portion. The thickness of the second member is larger than the thickness of the first member in the first direction. The depth of the recessed portion of the second member from the second flat portion is larger than the protruding length of the protruding portion of the first member from the first flat portion in the first direction.

Abstract: An electrochemical reaction cell stack includes an electrochemical reaction block including three or more electrochemical reaction units arranged in a first direction. The electrochemical reaction block includes a gas introduction flow passage, a gas discharge flow passage, and a gas transfer flow passage. An upstream electrochemical reaction unit includes an upstream introduction communication passage for connecting an upstream anode chamber to the gas introduction flow passage, and an upstream discharge communication passage for connecting the upstream anode chamber to the gas transfer flow passage. Similarly, a downstream electrochemical reaction unit includes a downstream introduction communication passage and a downstream discharge communication passage.

Abstract: An electrochemical reaction cell stack includes an electrochemical reaction block including three or more electrochemical reaction units arranged in a first direction; a first heat-absorbing member which is disposed on one side of the electrochemical reaction block in the first direction and absorbs heat generated from the electrochemical reaction block; and a second heat-absorbing member which is disposed on the other side of the electrochemical reaction block in the first direction and absorbs heat generated from the electrochemical reaction block. An upstream electrochemical reaction unit is disposed between the first heat-absorbing member and the downstream electrochemical reaction unit disposed closest to the first heat-absorbing member, and an upstream electrochemical reaction unit is disposed between the second heat-absorbing member and the downstream electrochemical reaction unit disposed closest to the second heat-absorbing member.

Abstract: An interconnector-electrochemical reaction unit cell composite body includes an electrochemical reaction unit cell and an interconnector. The interconnector has a plurality of combinations of protrusions protruding in the first direction and recesses provided on a side opposite the protrusions in the first direction and being concave toward the protrusions. At least one of the combinations is configured such that, as viewed in the first direction, the bottom of the recess is located on the side toward the open end of the recess. In a section parallel to the first direction, the recess is located within a width t2 of the protrusion in the second direction orthogonal to the first direction, and the width t1 of the recess in the second direction is smaller than the width t2.