The invention relates to an electrochemical cell comprising at least one strip diaphragm forming a core area, said strip diaphragm consisting of at least two, maximum 10,000, flat individual cells, each formed from an electrode layer applied on both sides of a diaphragm made of a solid polymer electrolyte and a corresponding number of flat electronically conductive regions, whereby the individual cells are switched in series and the core area is arranged in the cell with a suitable periphery.