Battery module, battery rack comprising same, and power storage device

1. A battery module comprising:

at least two cell assemblies, each of the at least two cell assemblies including a plurality of secondary batteries electrically connected to each other and stacked in a front-rear direction;

a module housing having a first side wall, a second side wall and an internal space in which the at least two cell assemblies is received;

a first gas passage formed between the first side wall and a first side of the at least two cell assemblies for circulation of gas generated from the at least two cell assemblies; and

a flame retardant plate extending in a left-right direction including:

a body formed in a plate shape and interposed between the at least two cell assemblies, and

a first flame barrier extending in the left-right direction from a first end of the body and disposed in part of the first gas passage.

2. The battery module according to claim 1 , further comprising:

a busbar assembly including at least one busbar that comes into contact with an electrode terminal provided in the plurality of secondary batteries to electrically connect the plurality of secondary batteries; and

at least two busbar frames in which the at least one busbar is mounted, and provided on each of left and right sides of the at least two cell assemblies,

wherein the first gas passage is a space formed between an outer surface of the busbar frame and an inner surface of the module housing, and

wherein the first flame barrier has a plurality of gas vent holes that is open in the front-rear direction to allow gas generated from the at least two cell assemblies to flow.

3. The battery module according to claim 2 , wherein the module housing has a gas outlet in communication with an end of the first gas passage, and

wherein each of the plurality of gas vent holes continuously reduces in opening size toward the gas outlet.

4. The battery module according to claim 2 , wherein the module housing has a gas outlet in communication with an end of the first gas passage, and

wherein the first flame barrier includes a guide structure to guide gas generated from the cell assembly toward the plurality of gas vent holes.

5. The battery module according to claim 1 , wherein an inner surface of the module housing has an insertion protrusion having a slit into which a portion of the first flame barrier is inserted.

6. The battery module according to claim 1 , wherein the flame retardant plate has a multilayer structure including at least one of a flame retardant layer, a heat insulating layer configured to prevent heat transfer, an expandable layer that expands in volume at a predetermined temperature, and a heat absorbing layer configured to absorb heat at a predetermined temperature.

7. The battery module according to claim 6 , wherein the multilayer structure is a structure in which the expandable layer is interposed between two flame retardant layers, or a structure in which the heat insulating layer is interposed between the two flame retardant layers.

8. The battery module according to claim 1 , wherein the cell assembly includes at least one of a heat absorbing pad between the plurality of secondary batteries configured to absorb heat through an endothermic reaction at a predetermined temperature or a heat insulating pad configured to prevent heat transfer.

9. A battery rack comprising a plurality of battery modules according to claim 1 , and a rack case in which the plurality of battery modules is received in such a manner that the battery modules are stacked in a vertical direction.

10. The battery rack according to claim 9 , wherein the battery rack comprises a flame retardant cover interposed between the plurality of battery modules to cover a top or a bottom of a battery module of the plurality of battery modules.

11. The battery rack according to claim 10 , wherein at least a portion of an outer periphery of the flame retardant cover extends such that it is exposed to outside from between the plurality of battery modules, and

wherein the extended outer periphery of the flame retardant cover is bent upward.

12. The battery rack according to claim 10 , wherein the flame retardant cover has a concave-convex structure bent at a predetermined interval.

13. An energy storage system comprising the battery rack according to claim 9 .

14. The battery module according to claim 1 , further comprising:

a second gas passage formed between the second side wall and a second side of the at least two cell assemblies; and

a second flame barrier extending in the left-right direction from a second end of the body and disposed in part of the second gas passage.

15. The battery module according to claim 1 , wherein the flame retardant plate is planar.

16. The battery module according to claim 1 , wherein the first flame barrier has a plurality of gas vent holes that is open in the front-rear direction to allow gas generated from the at least two cell assemblies to flow.

17. The battery module according to claim 1 , wherein the flame retardant plate is formed of an expandable material that expands in volume at a predetermined temperature.

18. The battery module according to claim 1 , wherein the flame retardant plate has a multilayer structure including a central layer and a pair of outer layers, and

wherein a width of the outer layers in the left-right direction is equal to a width of the body of the flame retardant plate.