CELL, CELL STACK DEVICE, MODULE, AND MODULE STORAGE DEVICE

A cell 1 according to the present disclosure includes: a first electrode layer (3); a solid electrolyte layer (4) on the first electrode layer (3), the solid electrolyte layer (4) containing Zr; a middle layer (7) on the solid electrolyte layer (4), the middle layer (7) containing CeO which also contains a rare earth element other than Ce; and a second electrode layer (5) on the middle layer (7), wherein a boundary region between the solid electrolyte layer (4) and the middle layer (7) includes a basing point at which a molarity of Ce and a molarity of Zr are equal. An average molarity of the Ce within a range from the basing point up to 3 µm toward the solid electrolyte layer 4 is equal to or less than 10 mol% with respect to a total of Ce, Zr, and other rare earth elements, an average molarity of Zr within the range is equal to or more than 70 mol% with respect to a total of Ce, Zr, and other rare earth elements, or a molarity ratio of Ce with respect to Zr within the range is equal to or less than 0.143.