Rechargeable battery module

1. A rechargeable battery module, comprising:

unit cells arranged in a first direction;

a bus bar that electrically connects the unit cells;

a pair of end plates spaced apart from each other along the first direction at opposite ends of the unit cells to support the unit cells; and

at least one side plate between the pair of end plates and connected to the pair of end plates, the at least one side plate extending along the unit cells and spaced apart from the unit cells a predetermined distance,

wherein the at least one side plate includes:

stepped portions facing the unit cells, the stepped portions including a flat base at an outermost side of the at least one side plate, and at least one protruding portion that protrudes toward the unit cells from the flat base along a second direction crossing the first direction, and

a through-hole adjacent to the unit cells, and

wherein an insulating sheet is adhered to the at least one protruding portion and adjacent to the unit cells.

2. The rechargeable battery module as claimed in claim 1 , wherein the stepped portions have depths in a second direction crossing the first direction.

3. The rechargeable battery module as claimed in claim 1 , wherein the flat base and the protruding portion are connected at a right angle.

4. The rechargeable battery module as claimed in claim 1 , wherein the at least one side plate includes a plurality of through holes along a third direction crossing the first and the second directions.

5. The rechargeable battery module as claimed in claim 4 , wherein one stepped portion corresponds to each of the plurality of through holes.

6. The rechargeable battery module as claimed in claim 1 , wherein a height of the at least one protruding portion along the second direction is about 30% to about 40% of a thickness of the at least one side plate along the second direction.

7. The rechargeable battery module as claimed in claim 1 , wherein the at least one protruding portion gradually decreases and protrudes from the flat base to the unit cells.

8. The rechargeable battery module as claimed in claim 1 , wherein the at least one protruding portion is repeatedly directed from the flat base to the unit cells and directed from the unit cells to an opposite side thereof.

9. The rechargeable battery module as claimed in claim 1 , wherein:

the at least one side plate is a metal sheet with a predetermined thickness, and

the stepped portions extend along an entire thickness of the at least one side plate in a second direction crossing the first direction.

10. The rechargeable battery module as claimed in claim 1 , further including a flange along bottoms of the unit cells to support the bottoms of the unit cells, the flange being connected to a lower end portion of the at least one side plate to extend in a second direction crossing the first direction.

11. The rechargeable battery module as claimed in claim 10 , wherein the flange includes a rib that protrudes in a third direction crossing the first and second direction, the rib extending in the first direction.

12. The rechargeable battery module as claimed in claim 1 , further comprising an end support between the end plate and an outermost unit cell, the end support being an insulator.

13. The rechargeable battery module as claimed in claim 1 , further comprising an insulating sheet between the at least one side plate and the unit cells.

14. A rechargeable battery module, comprising:

unit cells arranged in a first direction;

a bus bar that electrically connects the unit cells;

a pair of end plates spaced apart from each other along the first direction at opposite ends of the unit cells to support the unit cells; and

at least one side plate between the pair of end plates and connected to the pair of end plates, the at least one side plate extending along the unit cells and spaced apart from the unit cells a predetermined distance,

wherein the at least one side plate includes stepped portions facing the unit cells, and

wherein the stepped portions include:

a flat base at an outermost side of the at least one side plate, the flat base being parallel with the at least one side plate, and

at least one protruding portion that protrudes toward the unit cells from the flat base along a second direction crossing the first direction, a first edge of the at least one protruding portion being connected to the flat base, and a second edge of the at least one protruding portion being opposite the first edge and spaced apart from the unit cells along the second direction to have an empty space therebetween.