Device for storing electrical energy, method for assembling and starting up said device, and method for operating said device

An apparatus for storing electric energy, which comprises an electrochemical cell having a cathode space for accommodating a liquid cathode material and an anode space for accommodating a liquid anode material, where the cathode space and the anode space are separated by a solid electrolyte, wherein the solid electrolyte is enclosed by a sheet-like structure having openings through which the cathode material can flow, the sheet-like structure is made of an electrically conductive material and the cathode space comprises at least one segment, where each segment has an outer wall composed of an electrically conductive material and the outer wall is fastened in a fluid-tight and electrically conductive manner to the sheet-like structure having openings, wherein each segment is filled with a porous felt or a porous material being different from porous felt and the cathode space is divided by the sheet-like structure having openings into an inner region and an outer region and a porous electrode and a chemical barrier layer composed of a material which does not conduct electrons are accommodated in the inner region between the sheet-like structure having openings and the solid electrolyte and the outer region comprises the at least one segment.