Power storage device

1 . A power storage device comprising: a plurality of storage battery units stacked in a predetermined direction; and a plurality of heat dissipating materials for dissipating heat generated in the storage battery units, wherein: the plurality of storage battery units include: a first storage battery unit, a second storage battery unit disposed at a position adjacent to the first storage battery unit along a predetermined direction, a third storage battery unit disposed at a position adjacent to the second storage battery unit along the predetermined direction, a fourth storage battery unit disposed at a position adjacent to the third storage battery unit along the predetermined direction, and a fifth storage battery unit disposed at a position adjacent to the fourth storage battery unit along the predetermined direction; the heat dissipating material includes: a first heat dissipating material having a first portion disposed between and abutting both the first storage battery unit and the second storage battery unit, a second portion disposed between and abutting both the third storage battery unit and the fourth storage battery unit, and a first connecting portion extending form the first portion to the second portion, and a second heat dissipating material separate from the first heat dissipating material and having a third portion between and abutting both the second storage battery unit and the third storage battery unit, a fourth portion disposed between and abutting both the fourth storage battery unit and the fifth storage battery unit, and a second connecting portion extending from the third portion to the fourth portion; the first storage battery unit, the second storage battery unit, the third storage battery unit, the fourth storage battery unit, and the fifth storage battery unit are stacked so as to be aligned along the predetermined direction in a state in which a widest surface of the first storage battery unit, the second storage battery unit, the third storage battery unit, the fourth storage battery unit, and the fifth storage battery unit face each other and, wherein the first storage battery unit, the second storage battery unit, the third storage battery unit, the fourth storage battery unit, and the fifth storage battery unit each include only one positive electrode and only one negative electrode.

2 . The power storage device of claim 1 , wherein each of the first portion, the second portion, the third portion, and the fourth portion is a flat plate.