ELECTROCHEMICAL CELL STACK

An electrochemical cell stack according to a second aspect of the present invention includes an electrochemical cell and a manifold supporting a base end of the electrochemical cell. The electrochemical cell includes an electric conductive support substrate and a power generation unit disposed on the support substrate. Additionally, a gas flow path is provided in the support substrate. The power generation unit includes an anode disposed on a first main surface of the support substrate, a cathode, and a solid electrolyte layer disposed between the anode and the cathode. Additionally, the solid electrolyte layer contains a zirconia-based material as a main component thereof. The solid electrolyte layer includes a base end portion positioned on a side of the base end and a separated portion positioned separated from the base end. The base end portion includes a first area covering within 3 μm from an anode side surface, and a second area provided on the first area. An intensity ratio of tetragonal zirconia to cubic zirconia in a Raman spectrum in the first area is greater than an intensity ratio of tetragonal zirconia to cubic zirconia in the Raman spectrum in the second area.