Battery injection and formation control device

The invention discloses a battery injection and formation control device which comprises an internal piston, an external piston, an injection hole arranged in a battery shell cover plate, a plastic bracket in a battery shell and a piston packaging device capable of controlling gas emission pressure, wherein the internal piston is detachably fixed in the plastic bracket and internally provided with a threaded hole matched with the external piston, the threaded hole is mutually aligned with the injection hole, and the external piston is connected with a thread in the threaded hole of the internal piston for closing the injection hole after penetrating through the injection hole. Positive pressure in a battery acts on the internal piston to press a sealing surface of the internal piston, thus airtightness of the injection hole is ensured. Through controlling the gas emission pressure during battery formation, gas pressure in the battery can be reduced, and battery expansion is lightened;and electrochemical prope