A sagger alignment structure includes: a first clip configured to connect at least one pair of saggers in a state in which sides of the at least one pair of saggers face each other, where the first clip includes: a first clip body; first clip sides bent from opposite sides of the first clip body; and a first insertion space between the first clip sides and configured to accommodate the sides of the at least one pair of saggers, and where the first clip body comprises a first opening that defines a through hole through the first clip body.

Disclosed is a calcination vessel for manufacturing electrode active materials, the calcination vessel including 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 one stack support portion extending upward from a part of an upper end of each side wall portion that is not a corner region where adjacent side wall portions abut each other.