POWER SUPPLY DEVICE, ELECTRIC VEHICLE PROVIDED WITH SAID POWER SUPPLY DEVICE, AND ELECTRICITY-STORAGE DEVICE

A plurality of battery cells each having a prismatic shape, a fixing member that fixes the plurality of battery cells in a stacked state, and a thermal insulation sheet that is sandwiched between stacking surfaces of battery cells and thermally insulates the adjacent battery cells, wherein thermal insulation sheet is an inorganic fiber sheet in which inorganic fibers are aggregated in a three-dimensionally non-directional manner and fine voids are provided between the inorganic fibers.