Secondary battery pack comprising movable wall and elastic member

1. A secondary battery pack comprising:

at least one unit cell including a secondary battery or a secondary battery module;

at least one end plate which is disposed on at least one side of both opposite end sides of the unit cell;

a movable wall which is disposed between the at least one end plate and one side face of the unit cell; and

an elastic member which is disposed between the at least one end plate and the movable wall to apply a compression force to the one side face of the unit cell through the movable wall,

wherein the at least one end plate includes:

a convex part which is formed thereon so as to protrude in an opposite direction of the one side face of the unit cell, so that, when the movable wall moves to the end plate due to the unit cell being expanded while pressing the elastic members, the movable wall is housed therein,

wherein when the movable wall moves to the end plate due to the unit cell being expanded while pressing the elastic members, the movable wall moves into the convex part.

2. The secondary battery pack according to claim 1 , wherein the movable wall includes:

a flat plate-shaped body; and

one or more hollow column-shaped elastic member insertion protrusions which are formed on a surface facing the at least one end plate of the body,

wherein the at least one end plate further includes:

an additional protruded parts which is formed thereon so as to protrude in the opposite direction of the one side face of the unit cell corresponding to the elastic member insertion protrusions, so that, when the movable wall moves to the at least one end plate due to the unit cell being expanded while pressing the elastic members, the elastic member insertion protrusions are inserted therein, and

one end portion of the elastic member is inserted inside of the elastic member insertion protrusion, and the other end portion of the elastic member is positioned in the additional protruded part.

3. The secondary battery pack according to claim 1 , wherein the at least one end plate further includes:

a guide member which protrudes from the convex part to the movable wall,

wherein the movable wall includes:

a flat plate-shaped body; and

one or more hollow column-shaped guide member insertion protrusions which are formed on a surface facing the at least one end plate of the body,

wherein the guide member is slidably inserted into the guide member insertion protrusions.

4. The secondary battery pack according to claim 2 , wherein the secondary battery pack further includes:

a switch which is attached on an outer surface of the at least one end plate,

the movable wall includes:

a pressing member which is formed on the surface facing the at least one end plate of the body,

the at least one end plate includes:

a through hole which is formed therein so that, when the movable wall moves to the at least one end plate due to the unit cell being expanded while pressing the elastic members, the pressing member protrudes to an outside of the at least one end plate,

wherein the switch is positioned in the at least one end plate so that the pressing member protrudes via the through hole to operate the switch.

5. The secondary battery pack according to claim 4 , wherein the switch is a non-return type switch.

6. The secondary battery pack according to claim 4 , wherein the pressing member is disposed at a center of the movable wall, and

a plurality of elastic member insertion protrusions or a plurality of guide member insertion protrusions are disposed so as to be point-symmetric about the pressing member.

7. The secondary battery pack according to claim 4 , wherein the pressing member has a connecting part formed at a free end portion thereof.

8. The secondary battery pack according to claim 4 , wherein the pressing member is separately connected to the body.

9. The secondary battery pack according to claim 1 , wherein the movable wall is formed by aluminum die-casting.

10. The secondary battery pack according to claim 2 , wherein the movable wall has a frame part which is formed on the body thereof in a lattice form and has a larger thickness than the other portions thereof, and

the elastic member insertion protrusions are disposed on the frame part.

11. The secondary battery pack according to claim 3 , wherein the movable wall has a frame part which is formed on the body thereof in a lattice form and has a larger thickness than the other portions thereof, and

the guide member insertion protrusions are disposed on the frame part.