Battery system, vehicle including battery system, and power storage device

A battery system comprising:

• a battery stack including a plurality of rectangular battery cells that are stacked;
• a pair of end plates placed at both ends of the battery stack;
• and
• a binding bar that connects the pair of end plates together to fix the battery stack in a compressed state in a stacking direction, each of the end plates including
• plates placed on both surfaces of the end plate, and
• a plate-shaped block laminated between the plates, wherein
• the plates each include an outer plate placed on an outer surface among the both surfaces and an inner plate placed on an inner surface among the both surfaces,
• the plate-shaped block includes
• dual-side blocks placed on both sides and separated from each other, and
• an intermediate block provided in a tapered groove between the dual-side blocks,
• the tapered groove has a taper shape that gradually increases in width from an outside to an inside of the end plate,
• the intermediate block is placed in close contact with facing surfaces of the tapered groove in a slidable manner,
• the dual-side blocks are fixed on inner surfaces of the plates, and
• the intermediate block pressed by the battery stack is press-fitted into the tapered groove and applies tensile stress to the outer plate and the inner plate via the dual-side blocks.