Battery module having bus bar, and battery pack

1. A battery module, comprising:

a plurality of cylindrical battery cells including electrode terminals each at one of a top and a bottom of a respective one of the plurality of cylindrical cells, the plurality of cylindrical battery cells being arranged in columns and rows in a horizontal direction;

a module housing including an accommodation portion having a plurality of hollow structures to accommodate the plurality of cylindrical battery cells inserted into the module housing; and

a bus bar configured to contact the electrode terminals of the plurality of cylindrical battery cells to electrically connect between the plurality of cylindrical battery cells,

wherein the bus bar comprises:

a main body portion at a top or a bottom of the plurality of cylindrical battery cells and defining a plate shape having upper and lower surfaces that are broader than a lateral surface of the main body portion in the horizontal direction; and

a contact portion configured to electrically contact and be connected to one electrode terminal of the electrode terminals of one of the plurality of cylindrical battery cells, that extends and protrudes from the main body portion in a horizontal direction, that is stepped from the main body portion in a direction toward the one electrode terminal, and that includes a branched structure bifurcated in two directions with respect to a direction in which the contact portion extends and protrudes from the main body portion,

wherein the branched structure includes an embossed protrusion such that a first surface of the branched structure is recessed, and a second surface of the branch structure has a protruding surface to protrude toward the one electrode terminal with the first and second surface being on opposite surfaces of the branched structure.

2. The battery module of claim 1 , wherein the main body portion includes at least one connection opening, and

wherein the contact portion is within a circumference of the connection opening.

3. The battery module of claim 2 , wherein a notch is defined in a connection area between the circumference of the connection opening and the contact portion.

4. The battery module of claim 1 , wherein the connection opening is defined at an end of the main body portion.

5. The battery module of claim 1 , wherein the bus bar comprises a copper alloy.

6. The battery module of claim 1 , wherein the embossed protrusion has an annular shape in a plan view and has a greater protruding depth toward a center of the annular shape of the embossed protrusion in a direction toward the one electrode terminal.

7. The battery module of claim 6 , wherein the welding rod has a cylindrical shape, and

a diameter of the annular shape of the embossed protrusion is less than a diameter of the cylindrical shape of the welding rod.

8. The battery module of claim 7 , wherein a top surface of the contact portion at a peripheral circumference corresponding to the embossed protrusion includes an insertion groove that is internally engraved, wherein an end of the cylindrical welding rod in a vertical direction is inserted into the insertion groove.

9. The battery module of claim 1 , wherein the electrode terminals of the cylindrical battery cells comprise first electrode terminals at an upper end of the cylindrical battery cells and second electrode terminals at a lower end of the cylindrical battery cells,

wherein the bus bar comprises:

a first bus bar mounted to a top of the module housing to be electrically connected to the first electrode terminals; and

a second bus bar mounted to a bottom of the module housing to be electrically connected to the second electrode terminals.

10. A battery module, comprising:

a plurality of cylindrical battery cells including electrode terminals each at one of a top and a bottom of a respective one of the plurality of cylindrical cells and a plurality of externally protruding protrusions formed on the electrode terminals, the plurality of cylindrical battery cells being arranged in columns and rows in a horizontal direction;

a module housing including an accommodation portion having a plurality of hollow structures to accommodate the plurality of cylindrical battery cells inserted into the module housing; and

a bus bar welded to the protrusions of the electrode terminals of the plurality of cylindrical battery cells by welding and configured to electrically connect between the plurality of cylindrical battery cells,

wherein the bus bar comprises:

a main body portion at a top or a bottom of the plurality of cylindrical battery cells and defining a plate shape having upper and lower surfaces that are broader than a lateral surface of the main body portion in the horizontal direction; and

a contact portion configured to electrically contact and be connected to one electrode terminal of one of the plurality of battery cells, that extends and protrudes from the main body portion in a horizontal direction, that is stepped from the main body portion in a direction toward the one electrode terminal, and that includes a branched structure bifurcated in two directions with respect to a direction in which the contact portion extends and protrudes from the main body portion,

wherein the branched structure includes an embossed protrusion such that a first surface of the branched structure is recessed, and a second surface of the branch structure has a protruding surface to protrude toward the one electrode terminal with the first and second surface being on opposite surfaces of the branched structure, and

wherein a contact area is configured to allow a welding rod to establish electrical connection around the embossed protrusion in the branched structure.

11. A battery pack comprising at least two battery modules according to claim 1 , which are arranged in a direction.

12. The battery module of claim 10 , wherein the main body portion includes at least one connection opening, and

wherein the contact portion is within a circumference of the connection opening.

13. The battery module of claim 12 , wherein a notch is defined in a connection area between the circumference of the connection opening and the contact portion.

14. The battery module of claim 10 , wherein the embossed protrusion has an annular shape in a plan view and has a greater protruding depth toward a center of the annular shape of the embossed protrusion in a direction toward the one electrode terminal.

15. The battery module of claim 10 , wherein the electrode terminals of the cylindrical battery cells comprise first electrode terminals at upper ends of the cylindrical battery cells and second electrode terminals at lower ends of the cylindrical battery cells,

wherein the bus bar comprises:

a first bus bar mounted to a top of the module housing to be electrically connected to the first electrode terminals; and

a second bus bar mounted to a bottom of the module housing to be electrically connected to the second electrode terminals,

wherein the first bus bar comprises a mounting portion at a front end portion of the main body portion to be in contact with a portion of the second bus bar, and

wherein the second bus bar comprises:

a bent portion that is vertically and upwardly bent and extended from a rear end portion of the main body portion; and

a connection portion that is bent and extended backward from an upper end of the bent portion and is configured to be mounted on the mounting portion of the first bus bar to be electrically connected to the first bus bar.

16. The battery module of claim 1 , wherein a contact area is configured to allow a welding rod to establish electrical connection around the embossed protrusion in the branched structure.

17. The battery module of claim 9 , wherein the branched structure includes an embossed protrusion protruding toward the one electrode terminal, and a contact area is set to allow a welding rod to establish electrical connection around the embossed protrusion in the branched structure.

18. The battery module of claim 9 , wherein the first bus bar comprises a mounting portion at a front end portion of the main body portion to be in contact with a portion of the second bus bar.

19. The battery module of claim 12 , wherein the second bus bar comprises:

a bent portion that is vertically and upwardly bent and extended from a rear end portion of the main body portion; and

a connection portion that is bent and extended backward from an upper end of the bent portion and is configured to be mounted on the mounting portion of the first bus bar to be electrically connected to the first bus bar.

20. The battery module of claim 10 , a diameter of the embossed protrusion is less than a diameter of the welding rod in contact with the contact region.