Energy storage expansion tank

The invention belongs to the technical field of expansion tanks, and particularly relates to an energy storage expansion tank which comprises a tank body, the tank body is composed of a small shell and a large shell which are distributed up and down, and a leather film is installed between the small shell and the large shell; a PP lining is installed on the upper side of the large shell. An interlayer is fixedly mounted in the small shell; a pneumatic assembly capable of adjusting the air pressure between the interlayer and the leather film is mounted in the cavity on the upper side of the interlayer; when cooling liquid with external pressure enters the expansion tank, the pressure of the cooling liquid in the expansion tank is increased, the leather film is extruded and deformed, gas in a cavity between the leather film and the interlayer is compressed, after the gas is compressed, the size is decreased, the pressure is increased, at the moment, the pneumatic assembly works, the gas in the cavity between th