Battery module having improved safety, battery pack including battery module, and vehicle including battery pack

1. A battery module comprising:

two or more battery cells, including a first battery cell and a second battery cell; and

a current shut-off battery cell providing an electrical connection between the first battery cell and the second battery cell, the current shut-off battery cell having a case,

wherein, when overcharge occurs, the case of the current shut-off battery cell ruptures to disconnect the electrical connection,

wherein each of the first battery cell and a second battery cell have a first electrode lead with a bent part, and

wherein the current shut-off battery cell is smaller or thinner than either of the first battery cell and the second battery cell so that the current shut-off battery cell is disposed between the bent parts of each first electrode lead while not affecting a distance between the first battery cell and the second battery cell.

2. The battery module according to claim 1 , wherein each of the first battery cell and the second battery cell is a pouch-type secondary battery having a second electrode and an electrode assembly having two ends, the two ends respectively connected to a first end of the first electrode lead and a first end of the second electrode lead,

wherein each electrode assembly is received in a case together with an electrolyte solution and the case is hermetically sealed, and

wherein a second end of each electrode lead is exposed outside of the case.

3. The battery module according to claim 1 , wherein the first battery cell and the current shut-off battery cell are connected in series, and the current shut-off battery cell and the second battery cell are connected in series.

4. The battery module according to claim 2 , wherein the first electrode lead of the first battery cell and the first electrode lead of the second battery cell are connected to each other by electrode leads of the current shut-off battery cell.

5. The battery module according to claim 4 , wherein the first battery cell and the second battery cell are stacked in an alternating manner in a stack direction such that each alternating electrode lead has opposite polarities, and the second end of the first electrode lead of the first battery cell and the second end of the first electrode lead of the second battery cell are bent facing each other along the stack direction, and the current shut-off battery cell is placed in parallel to the stack direction.

6. The battery module according to claim 1 , wherein an electrode assembly of the current shut-off battery cell has a stack of a negative electrode plate, a separator and a positive electrode plate, wherein the positive electrode plate includes:

a positive electrode current collector; and

a positive electrode active material layer formed on the positive electrode current collector,

wherein the positive electrode active material layer includes a positive electrode active material, a gas generating material, a conductive material and a binder.

7. The battery module according to claim 6 , wherein the gas generating material is one selected from the group consisting of lithium carbonate (Li 2 CO 3 ), calcium carbonate (CaCO 3 ), Lithium Nickel Oxide (LNO) and lithium oxalate, or mixtures thereof.

8. The battery module according to claim 6 , wherein the gas generating material is included in the positive electrode plate in an amount of 0.1 to 20 weight % based on the total weight of the positive electrode active material and the gas generating material.

9. The battery module according to claim 6 , wherein the gas generating material is bonded and immobilized by the binder, and pores are formed by voids in the gas generating material.

10. The battery module according to claim 6 , wherein the positive electrode active material and the gas generating material are blended together.

11. The battery module according to claim 6 , wherein the positive electrode active material layer includes a primer layer and an active material coating layer,

wherein the primer layer includes the gas generating material, the conductive material and the binder, and

wherein the active material coating layer includes the positive electrode active material, the conductive material and the binder.

12. The battery module according to claim 11 , wherein the gas generating material is present in an amount of 90 to 99.9 weight % of solids in the primer layer.

13. The battery module according to claim 2 , wherein the first electrode lead of the first battery cell or the first electrode lead of the second battery cell is made of a bimetal,

wherein the bimetal has a stack of a first metal having a high coefficient of thermal expansion and a second metal having a low coefficient of thermal expansion,

the first metal having a high coefficient of thermal expansion is coupled with the electrode lead of the current shut-off battery cell, and

an end of the first metal having a high coefficient of thermal expansion is adhered to the case of the current shut-off battery cell by an adhesive element.

14. A battery pack comprising:

at least one battery module according to claim 1 ; and

a pack case which houses the at least one battery module.

15. A vehicle comprising:

at least one battery pack according to claim 14 .

16. A battery module comprising:

two or more battery cells, including a first battery cell and a second battery cell; and

a current shut-off battery cell providing an electrical connection between the first battery cell and the second battery cell, the current shut-off battery cell having a case,

wherein, when overcharge occurs, the case of the current shut-off battery cell ruptures to disconnect the electrical connection,

wherein the first battery cell and the second battery cell are stacked in a lateral direction, and

wherein the current shut-off battery cell is located above the first battery cell and the second battery cell.

17. The battery module according to claim 1 , wherein the first battery cell and the second battery cell each have a positive terminal and a negative terminal extending from a case and spaced apart in a first direction, and

wherein the current shut-off battery cell has a positive terminal and a negative terminal extending from the case of the current shut-off battery cell spaced apart in a second direction perpendicular to the first direction.

18. The battery module according to claim 1 , wherein the first electrode is drawn from the first battery cell at a point a first distance from where the first electrode lead is drawn from the second battery cell, and

wherein a largest dimension of the current shut-off battery cell is less than the first distance.