Battery pack

A battery pack comprising:

• an electrode assembly having an outer side surface, a top and a bottom opposing each other;
• an electrode plate outwardly extending from the top of the electrode assembly;
• a case accommodating the electrode assembly, wherein the case includes first and second walls opposing each other, wherein each of the first and second walls has an inner surface and an outer surface opposing each other, wherein the inner surface faces the outer side surface of the electrode assembly,
• wherein at least a portion of the outer surface of the second wall is uneven, wherein the uneven portion defines a gap between the outer surface of the electrode assembly and the inner surface of the second wall, wherein the uneven portion extends in the width direction of the second wall of the case,
• wherein the uneven portion comprises a plurality of protrusions and a plurality of recesses alternately formed with respect to each other, wherein each of the protrusions extends in the same direction in which the electrode plate extends,
• wherein the outer surface of the second wall is configured to be deformed based on pressure applied to the case, wherein the thickness of each of the protrusions and recesses is configured to decrease by stretching in response to the outer surface of the second wall being deformed,
• wherein each of the first and second walls has a predetermined radius of curvature, and
• wherein the predetermined radius of curvature of the second wall is greater than the predetermined radius of curvature of the first wall.