Secondary battery and electrochemical device

A secondary battery, comprising:

• an electrode assembly;
• and
• a shell, accommodating the electrode assembly, wherein the shell comprises a first wall and a second wall opposite to each other along a thickness direction of the electrode assembly,
• wherein the first wall is provided with a first protruding portion, the first protruding portion protrudes from the first wall towards an inside of the shell, and the shell further comprises a third wall, the third wall connects the first wall and the second wall, the third wall is spaced apart from the electrode assembly along a first direction, and the first direction is perpendicular to the thickness direction of the electrode assembly;
• and
• along the thickness direction of the electrode assembly, a dimension of an inner surface of the third wall is L1, a thickness of the electrode assembly is L2, and a height by which the first protruding portion protrudes beyond an inner surface of the first wall is L3, wherein L3≥L1−L2.