Cell, cell stack unit, electrochemical module, and electrochemical apparatus

A cell comprising:

• a solid oxide electrolyte layer;
• a first electrode layer on a surface of the solid oxide electrolyte layer;
• and
• a second electrode layer on another surface of the solid oxide electrolyte layer,
• wherein
• the second electrode layer comprises a plurality of pores accounting for a total number of pores in the second electrode layer,
• in any cross-section of the second electrode layer, the plurality of pores comprise:
• first pores of a first pore size range from 0.02 μm to 1 μm, the first pores accounting for 80 percent to 90 percent of the plurality of pores;
• second pores of a second pore size range that partially overlaps and increases beyond the maximum pore size of the first pore size range, the second pores accounting for 9 percent to 19 percent of the plurality of pores;
• and
• third pores of a third pore size range that starts beyond the maximum pore size of the first pore size range and partially overlaps with the second pore size range and increases beyond a maximum pore size of the second pore size range, the third pores accounting for 0.3 percent to 2 percent of the plurality of pores.