Prismatic secondary battery

A prismatic secondary battery comprising:

• a prismatic hollow outer body having a mouth portion;
• a sealing plate for sealing up the mouth portion of the prismatic hollow outer body;
• and
• a flat electrode assembly including one end having stacked positive electrode substrate exposed portions, including another end having stacked negative electrode substrate exposed portions, and stored in the prismatic hollow outer body;
• a positive electrode collector including a first rib being connected to an outermost surface on one side of the stacked positive electrode substrate exposed portions and a positive electrode collector including a second rib being connected to an outermost surface on another side of the stacked positive electrode substrate exposed portions,
• a negative electrode collector including a third rib being connected to an outermost surface on one side of the stacked negative electrode substrate exposed portions and a negative electrode collector including a fourth rib being connected to an outermost surface on another side of the stacked negative electrode substrate exposed portions,
• the positive electrode collector including the first rib and the negative electrode collector including the third rib being located on the same side of the flat electrode assembly, and the positive electrode collector including the second rib and the negative electrode collector including the fourth rib being located on the same side of the flat electrode assembly,
• the difference between the leading end in the height direction of the first rib and the leading end in the height direction of the third rib being within 0.1 mm, and the leading end in the height direction of the first rib and the leading end in the height direction of the third rib protruding from the outermost surface of the flat electrode assembly toward the prismatic hollow outer body, and
• a leading end in the height direction of the second rib and a leading end in the height direction of the fourth rib not protruding from the outermost surface of the flat electrode assembly toward the prismatic hollow outer body.