BATTERY PACK AND ENERGY STORAGE SYSTEM INCLUDING SAME

Discussed is a battery back that may include at least one cell assembly and a pack case configured to accommodate the at least one cell assembly. The at least one cell assembly may include: two or more cell stacks including battery cells that are stacked; a cell pressurization unit disposed at outermost positions on opposite sides of each cell stack in a stacking direction of the battery cells and configured to provide pressing force to each cell stack; and a bus-bar frame assembly disposed at a front and a rear of the two or more cell stacks in a direction intersecting the stacking direction of the battery cells and configured to electrically connect the battery cells and integrally support the two or more cell stacks and the cell pressurization unit.