Battery case for secondary battery

1. A battery case comprising a receiving part having an electrode assembly mounted therein, wherein the receiving part, which is formed by deforming a sheet type base material, is configured to have a stair structure in which at least one corner or surface forming a shape of the receiving part is deformed,

wherein the receiving part has a side wall configured to have the stair structure, the stair structure comprising two or more steps, the steps forming right angles in cross-section, and the steps have heights gradually decreased in a depth direction of the receiving part.

2. The battery case according to claim 1 , wherein the base material is formed of a laminate sheet comprising a resin layer and a metal layer.

3. The battery case according to claim 2 , wherein the base material comprises an upper layer of a first polymer resin, an intermediate layer of a blocking metal, and a lower layer of a second polymer resin.

4. The battery case according to claim 1 , wherein the base material has a thickness of 0.3 mm to 6 mm.

5. The battery case according to claim 1 , wherein, when the stair structure comprises n steps, an n-th step is located at a lowermost end of the stair structure in the depth direction of the receiving part, an (n−1)-th step is located at a top of the n-th step, and the n-th step has a smaller height than the (n−1)-th step.

6. The battery case according to claim 5 , wherein the height of the n-th step is equivalent to 50 to 90% of that of the (n−1)-th step.

7. The battery case according to claim 5 , wherein a thickness of the side wall of the receiving part at the n-th step is equivalent to 90 to 99% of that of the side wall of the receiving part at the (n−1)-th step.