Battery pack having reinforcement member

1. A battery pack comprising:

a battery module array having battery modules which are arranged in a lateral direction in two or more rows, each of the battery modules being configured to have a structure in which battery cells or unit modules, each of which has two or more battery cells mounted therein, are stacked in which the battery cells or the unit modules are vertically erected;

a base plate on which the battery modules are stacked in a vertically erected state;

a pair of main members provided at a front and rear of the battery module array to support load of the battery modules, opposite ends of each of the main members being fastened to an external device;

a pair of end plates disposed in tight contact with the front and rear of the battery module array in a state in which a lower end of each of the end plates is fixed to the base plate; and

supporting bars connected between upper parts or side parts of the end plates so as to interconnect and support the end plates,

wherein a reinforcement member is coupled to side walls of the end plates or sides of the main members at an outer side of an outermost battery module of the battery module array to minimize deformation of the battery pack when the battery pack is vibrated in a front and rear direction, and

wherein the reinforcement member is disposed at the outer side of the outermost battery module in a diagonal structure or in an X-shaped structure in a plane.

2. The battery pack according to claim 1 , wherein each of the battery cells is a plate-shaped battery cell.

3. The battery pack according to claim 2 , wherein each of the battery cells is configured to have a structure in which an electrode assembly is mounted in a battery case formed of a laminate sheet.

4. The battery pack according to claim 1 , wherein each of the main members is configured to have a U-shaped frame structure surrounding opposite sides and a bottom of the battery module array.

5. The battery pack according to claim 4 , wherein upper ends of each of the main members are bent outward so that the battery pack can be easily mounted to an external device, and the bent portions of each of the main members are provided with fastening holes.

6. The battery pack according to claim 1 , wherein the reinforcement member is coupled to the side walls of the end plates or the sides of the main members by welding or bolting.

7. The battery pack according to claim 1 , wherein the reinforcement member is further coupled to tops of the end plates by welding or bolting so that the reinforcement member is disposed in the diagonal structure or in the X-shaped structure in a plane.

8. The battery pack according to claim 1 , wherein each of the end plates is formed in the shape of a single body having a size corresponding to the front or rear of the battery module array to minimize deformation of the battery pack when the battery pack is vibrated in an up and down direction.

9. The battery pack according to claim 1 , wherein each of the end plates comprises a body part disposed in contact with the battery module array, an upper end wall, a lower end wall, and a pair of side walls, the upper end wall, the lower end wall, and the side walls protruding outward from a perimeter of the body part.

10. The battery pack according to claim 9 , wherein the lower end wall of each of the end plates is coupled to a lower end of the base plate and a lower end of each of the main members by welding or bolting.

11. The battery pack according to claim 10 , wherein the welding or the bolting is carried out at four or more spots.

12. The battery pack according to claim 9 , wherein each of the side walls of each of the end plates is coupled to each side of each of the main members by welding or bolting.

13. The battery pack according to claim 12 , wherein the welding or the bolting is carried out at one or more spots.

14. The battery pack according to claim 9 , wherein the upper end wall of each of the end plates protrudes upward from a top of the battery module array so that the supporting bars can be easily mounted to the end plates.

15. The battery pack according to claim 14 , wherein the upwardly protruding height is equivalent to 2 to 20% of a height of the battery module array.

16. The battery pack according to claim 1 , wherein each of the end plates is formed in the planar shape of a rectangle.

17. The battery pack according to claim 1 , wherein each of the end plates is provided at an upper part thereof with through holes, in which the supporting bars are mounted.

18. A device such as an electric vehicle, hybrid electric vehicle or plug-in hybrid electric vehicle using the battery pack according to claim 1 as a power source.

19. The device according to claim 18 , wherein the battery pack is installed in a lower end of a trunk of the vehicle or between a rear seat and the trunk of the vehicle.