A fuel cell comprises an anode, a cathode, and a solid electrolyte layer disposed between the anode and the cathode. The solid electrolyte layer contains a zirconia-based material as a main component. A first intensity ratio of tetragonal crystal zirconia to cubic crystal zirconia in a Raman spectrum in a central portion of the solid electrolyte layer is greater than a second intensity ratio of tetragonal crystal zirconia to cubic crystal zirconia in a Raman spectrum of an outer edge.

A bipolar plate for a fuel cell is provided. The bipolar plate for the fuel cell has a plurality of flow channels, and a rib is defined between neighboring two flow channels. A side surface of the rib is non-porous. A top surface of the rib may be a roughened surface in order to improve performance of the fuel cell.

A bipolar plate for a fuel cell is provided. The bipolar plate for the fuel cell has a plurality of flow channels, and a rib is defined between neighboring two flow channels. A side surface of the rib is non-porous. A top surface of the rib may be a roughened surface in order to improve performance of the fuel cell.

A fuel cell that includes an air fuel cell bipolar plate and a hydrogen fuel cell bipolar plate respectively having a Turing-pattern microstructure configuration. The spatial arrangement of the air fuel cell bipolar plate and the hydrogen fuel cell bipolar plate is such that the air layer of the air fuel cell bipolar plate and the hydrogen layer of the hydrogen fuel cell bipolar plate are opposed to each other to define a microstructure configuration for a coolant layer.