Lithium secondary battery and method of fabricating the same

A method of fabricating a lithium secondary battery, comprising:

• preparing a plurality of pouch cells in which an electrode assembly including a cathode and an anode is accommodated;
• forming stack structures by stacking the plurality of pouch cells;
• and
• forming an elastic foam layer on an outer surface of at least two of the plurality of pouch cells
• wherein a tensile modulus of the elastic foam layer is from 200 MPa to 800 MPa,
• wherein a porosity of the elastic foam layer is from 60% to 90%,
• wherein the elastic foam layer includes a cured product of a composition including a foaming agent, a polyol and an isocyanate, and the foaming agent is included in an amount from 0.1 wt % to 5 wt % based on a total weight of the composition,
• wherein the elastic foam layer is disposed on each of two outermost surfaces of the stack structure,
• a thickness of the elastic foam layer is from 0.1 mm to 10 mm, and
• the elastic foam layer is a film layer having a single layer structure,
• wherein the elastic foam layer is not disposed on facing surfaces of two different pouch cells within each of the stack structures, and
• the elastic foam layer is disposed on facing surfaces of two different stack structures of pouch cells.