POWER SUPPLY DEVICE, AND VEHICLE AND ELECTRICAL STORAGE DEVICE EACH EQUIPPED WITH SAME

Power supply device includes: battery stack in which a plurality of battery cells each including, on a top surface thereof, gas discharge valve that opens when an internal pressure of outer covering can increases are stacked; first cover provided on a top surface of battery stack and defining first gas duct communicating with gas discharge valve; and second cover provided on a top surface of first cover and defining second gas duct on a top surface of first gas duct. A plurality of communication holes through which first gas duct and second gas duct communicate with each other are formed on the top surface of first cover.