Battery pack

1. A battery module comprising:

a first end plate and a second end plate, each of the end plates comprising at least one flange;

a plurality of battery units arranged along a first direction between the end plates;

a first guide plate on a first side of the plurality of battery units, extending in the first direction and coupled to respective first flanges of the at least one flange of the first and second end plates;

a second guide plate on a second side of the plurality of battery units opposite the first side, extending in the first direction and coupled to respective second flanges of the at least one flange of the first and second end plates;

a first reinforcement plate on a third side of the plurality of battery units, extending in the first direction and coupled to the first and second end plates; and

a second reinforcement plate on a fourth side of the plurality of battery units opposite the third side, extending in the first direction and coupled to the first and second end plates,

wherein each of the end plates further comprises a base plate adjacent to and contacting a respective outermost side of the plurality of battery units, and the at least one flange of each of the end plates extends away from the base plate in the first direction or a direction opposite the first direction,

wherein the at least one flange comprises:

the first and second flanges extending respectively from first and second sides of the base plate away from the plurality of battery units;

a third flange extending from a third side of the base plate away from the plurality of battery units; and

a fourth flange extending from a fourth side of the base plate away from the plurality of battery units, the fourth side being opposite to the third side,

wherein each of the flanges has at least one opening passing through the flange in a direction substantially perpendicular to the first direction, and

wherein the first reinforcement plate attaches to the third flange at one or more openings of the at least one opening of the third flange, and the second reinforcement plate attaches to the fourth flange at one or more openings of the at least one opening of the fourth flange.

2. The battery module of claim 1 , wherein a distance between the first and second guide plates in a second direction perpendicular to the first direction is greater than or equal to a width in the second direction of the end plates.

3. The battery module of claim 1 , wherein the first reinforcement plate comprises a first base plate on the third side of the plurality of battery units and first bent portions on each side of the first base plate extending away from the plurality of battery units, and

wherein the second reinforcement plate comprises a second base plate on the fourth side of the plurality of battery units and second bent portions on each side of the second base plate extending away from the plurality of battery units.

4. The battery module of claim 1 , further comprising a first insulation plate between the first reinforcement plate and the third side of the plurality of battery units; and a second insulation plate between the second reinforcement plate and the fourth side of the plurality of battery units.

5. The battery module of claim 1 , wherein the third flange comprises a low portion having a lower height than other portions of the third side of the base plate, and wherein the low portion receives the first reinforcement plate.

6. The battery module of claim 1 , wherein the first and second guide plates have openings.