Power storage device including power storage cells having a positive electrode, a negative electrode, a separator, and an accommodation chamber for a liquid electrolyte

A power storage device, comprising a cell stack in which power storage cells are stacked in series, wherein

• each power storage cell includes:
• a positive electrode, in which a positive electrode active material layer is bonded to a first surface of a positive electrode current collector;
• a negative electrode, in which a negative electrode active material layer is bonded to a first surface of a negative electrode current collector, the negative electrode active material layer being disposed to face the positive electrode active material layer of the positive electrode;
• a separator disposed between the positive electrode active material layer and the negative electrode active material layer;
• a seal portion disposed between a first surface of the positive electrode current collector of the positive electrode and a first surface of the negative electrode current collector of the negative electrode, and on an outer side of the positive electrode active material layer and the negative electrode active material layer, and bonded to both the positive electrode current collector and the negative electrode current collector;
• and
• an accommodation chamber defined by the seal portion, the positive electrode and the negative electrode and accommodates a liquid electrolyte in a liquid-tight manner,
• wherein
• the liquid electrolyte is a liquid electrolyte containing an ester compound and a nonaqueous solvent,
• the ester compound is at least one of methyl acetate, ethyl acetate, or methyl propionate,
• the positive electrode current collector and the negative electrode current collector located as outermost layers of the cell stack are terminal current collectors,
• at least one of the terminal current collectors is made of a high thermal conductivity material having a thermal conductivity greater than or equal to 100 W/(m·K), and
• the power storage device comprises a cooling unit that cools the at least one terminal current collector made of the high thermal conductivity material.