Prismatic type secondary battery including insulation tube

A prismatic secondary battery, comprising:

• an electrode assembly, the electrode assembly including a first electrode, a second electrode, and a separator between the first and second electrodes;
• a case accommodating the electrode assembly, the case having an open upper end and at least two pairs of surfaces facing each other;
• a cap assembly sealing the open upper end of the case;
• and
• an insulation tube surrounding a lateral periphery of the case and the cap assembly within a region up to a certain height or greater, the insulation tube including at least one elastically deformable part at a side thereof,
• wherein the at least one elastically deformable part includes:
• at least one first bellows ridge extending along a first direction of the insulation tube and to an outside of the insulation tube;
• and
• at least one first bellows trough at a side portion of the at least one first bellows ridge, the at least one first bellows trough extending along the first direction of the insulation tube and to an inside of the insulation tube.