Calcination vessel for manufacturing electrode active material

A calcination vessel assembly comprising:

• a plurality of calcination vessels disposed in a 2×2 or more horizontal array on a plane, wherein
• each of the calcination vessels comprises:
• a base portion forming a bottom surface of the calcination vessel;
• side wall portions extending upward from outer peripheries of the base portion to form a raw material receiving space;
• and
• at least two stack support portions extending upward from an upper end of each side wall portion that is not a corner region where adjacent side wall portions abut each other.