Secondary battery

1. A secondary battery, comprising:

an electrode assembly, the electrode assembly including electrode plates and

a separator interposed between the electrode plates,

at least one of the electrode plates including:

a coated part, the coated part including a metallic plate having an active material coated thereon, and

an uncoated part, the uncoated part including a metallic plate without active material coated thereon,

the uncoated part including

a folding part at an end portion of the uncoated part, the folding part being folded with respect to other portions of the uncoated part along a folding line such that a plane of the metallic plate in the folding part is inclined with respect to a plane of the metallic plate in other portions of the uncoated part;

a current collector physically and electrically contacting the folding part; and

a supporting element, the supporting element penetrating the uncoated part along the folding line, and supporting the folding part along the folding line,

wherein the electrode assembly has a plate shape formed by winding the electrode plates and the separator in a jelly roll configuration and then pressing the wound electrode assembly,

wherein the electrode assembly includes:

a flat part where an outer circumference of the electrode assembly is flat; and

curved parts where the outer circumference of the electrode assembly is curved, the curved parts being disposed at both ends of the flat part, and

wherein the folding line is disposed in the flat part,

wherein a penetration slit penetrates the uncoated part along the folding line.

2. The secondary battery as claimed in claim 1 , wherein the supporting element includes a supporting plate, the supporting plate: being disposed in the penetration slit, and supporting the folding part along the folding line.

3. The secondary battery as claimed in claim 1 , further comprising:

a case, the case:

having an open end, and

being configured to accommodate the electrode assembly; and

a cap plate, the cap plate:

being coupled to the open end of the case, and

being configured to seal the electrode assembly in the case.

4. The secondary battery as claimed in claim 1 , wherein:

the electrode plates include first and second electrode plates separated by the separator, and

the current collector includes first and second current collectors electrically connected to the first and second electrode plates, respectively.

5. The secondary battery as claimed in claim 4 , further comprising a first electrode terminal, the first electrode terminal:

being electrically connected to the first current collector, and

partially protruding out of the case through the cap plate.

6. The secondary battery as claimed in claim 5 , further comprising a second electrode terminal, the second electrode terminal:

being electrically connected to the second current collector, and

partially protruding out of the case through the cap plate.

7. The secondary battery as claimed in claim 1 , wherein the supporting element that penetrates the uncoated part along the folding line extends in one direction in the form of a straight continuous line, a discontinuous dotted line, or a discontinuous dashed line.