Abstract: The invention relates to an electrolysis cell for preparing liquid alkali metal from a liquid alkali metal-heavy metal alloy, which comprises a tube (1) which is arranged essentially horizontally and has a closure device (4) at each of the two ends of the tube (1), at least one solid electrolyte tube (12) arranged in the tube (1), which conducts alkali metal ions and is closed at one end and has an opening (11) at the other end, with the solid electrolyte tube (12) being arranged concentrically in the tube (1) and having the opening (11) facing one end of the tube (1) so that a first annular gap (13) for conducting the liquid alkali metal-heavy metal alloy which forms one anode is present between the inside of the tube (1) and the outside of the solid electrolyte tube (12), an interior space (14) in the solid electrolyte tube (12) for accommodating the liquid alkali metal which can be utilized as cathode, where the closure device (4) comprises an alkali metal-heavy metal alloy inlet (8) or outlet (9) op