The invention concerns an electrochemical generator element (102) comprising successively a first electrode layer having a polarity (114), a first electrolyte layer (110), a second electrode layer with reverse polarity (108), a second electrolyte layer (112), a second electrode layer with said polarity (116). The electrode layers of said polarity (114, 116) are connected by a parallel connection. It further comprises current collectors (118, 120) connected to the electrode layers with said polarity (114, 116). The thickness of the first electrode layer with said polarity (114) is different from the thickness of said second electrode layer with said polarity (116). The invention is applicable to lithium-polymer storage batteries.