Manufacturing method of electrode assembly

A manufacturing method of an electrode assembly, the method comprising:

• a first step of forming an active material formed body including a communication hole;
• a second step of providing a solid material including Li2+XC1−XBXO3 (X represents a real number exceeding 0 and equal to or smaller than 1) on the active material formed body without using a solvent;
• a third step of melting the solid material;
• and
• a fourth step of rapidly cooling and solidifying a molten material of the solid material,
• wherein the communication hole is filled with the molten material in the third step, and
• a cooling speed for rapidly cooling the molten material of the solid material is 102 degree/sec to 105 degree/sec in the fourth step.