POWER SUPPLY DEVICE, AND ELECTRIC VEHICLE AND POWER STORAGE DEVICE THAT COMPRISE SAID POWER SUPPLY DEVICE

A power supply device includes a battery block in which a plurality of battery cells () is stacked in a thickness with separator () clamped therebetween, a pair of end plates disposed on opposing end faces of the battery block, and a binding bar coupled to the pair of end plates and fixing the battery block in a compressed state via the end plates, in order to absorb expansion of the battery cells with the separator and suppress degradation of the separator in a state of being heated by the battery cells. Separator () has a three-layer structure including viscoelastic elastic sheet () that absorbs expansion of battery cell () and heat-insulating sheets () laminated on opposing surfaces of elastic sheet (), and heat-insulating sheet () is hybrid material (A) of an inorganic powder and a fibrous reinforcing material.