Battery module with improved safety, battery pack including the battery module and vehicle including the battery pack
A battery module improves safety by blocking current when the temperature rises, a battery pack includes the battery module, and a vehicle includes the battery pack. The battery module includes two or more battery cells, an electrode assembly having both ends respectively connected to one ends of electrode leads of opposite polarities in a pouch case together with an electrolyte and other ends of the electrode leads are exposed to an outside of the pouch case, wherein the electrode leads and a bus bar connecting a first battery cell and a second battery cell, wherein the bus bar comprises a metal layer and a material layer that is normally conductive but may act as a resistor when a temperature rises, and wherein the material layer comprises a gas generating material that is decomposed at a certain temperature or higher to generate a gas and increase resistance.
1. A battery module comprising:
two or more battery cells, wherein the two or more battery cells are pouch type secondary batteries, each battery cell having an electrode assembly having ends respectively connected to a first end of an electrode lead of opposite polarities sealed in a pouch case together with an electrolyte and a second end of each electrode lead exposed to an outside of the pouch case,
wherein the electrode leads and a bus bar are connected to a first battery cell and a second battery cell of the two or more battery cells,
wherein the bus bar comprises a metal layer and a material layer that is conductive, but capable of acting as a resistor above a predetermined temperature,
wherein the material layer comprises a gas generating material that is decomposed at the predetermined temperature or higher to generate a gas and increase resistance, and
wherein the bus bar includes a block and a body, the block being connected to the electrode leads, the block embedded in a first surface of the body, a surface of the block being exposed to an outside coplanar with the first surface of the body, the material layer being interposed between the body and the block to separate the block from the body.
2. The battery module of claim 1 , wherein the material layer further comprises a conductive material, and an adhesive.
3. The battery module of claim 1 , wherein the gas generating material is melamine cyanurate.
4. The battery module of claim 2 , wherein the conductive materials are connected and fixed to each other by the adhesive, and when the gas is generated, the conductive materials are disconnected to increase resistance.
5. The battery module of claim 1 , wherein the block comprises:
a first block connected to an electrode lead of the first battery cell; and
a second block connected to an electrode lead of the second battery cell,
wherein a current flow path from the first battery cell to the second battery cell is provided along the electrode lead of the first battery cell, the first block, a first material layer interposed between the body and the first block, a second material layer interposed between the body and the second block, the second block, and the electrode lead of the second battery cell, in order.
6. The battery module of claim 1 , wherein the first battery cell and the second battery cell are connected in series through the bus bar.
7. The battery module of claim 6 , wherein the first battery cell and the second battery cell are stacked such that respective electrode leads are stacked to have opposite polarities, and the second end of the electrode lead of the first battery cell and the second end of the electrode lead of the second battery cell are bent toward each other in a stack direction and the bus bar is disposed in parallel to the stack direction between bent portions of the respective electrode leads such that the respective electrode leads are connected.
8. The battery module of claim 1 , wherein the bus bar is in a plate shape with a thickness less than a length and a width and is provided with grooves through which the electrode leads penetrate.
9. A battery pack comprising:
at least one battery module according to claim 1 ; and
a pack case configured to package the at least one battery module.
10. A vehicle comprising at least one battery pack according to claim 9 .
11. The battery module of claim 1 , wherein the material layer extends below an outer surface of the bus bar.
12. The battery module of claim 1 , wherein the material layer prevents direct contact of the body with the block.
13. The battery module of claim 1 , wherein the body and the block are formed of the metal layer.