BATTERY PACK, ENERGY STORAGE SYSTEM, AND VEHICLE

A battery pack has improved safety against external impacts, and an energy storage system and a vehicle including the same. The battery pack includes a battery module having at least one battery cell; a tray having a plate shape so that the battery module is mounted thereon; a reinforcing member having a plate shape and mounted on the tray, the reinforcing member having at least a portion coupled to the tray and the other portion supporting the battery module upward, the reinforcing member being configured to form a space separated from the tray below the other portion supporting the battery module; and an elastic member constrained in the separated space in an elastically deformed state and configured to press a lower surface of the reinforcing member upward.