A supercapacitor cell is provided having unit cells arranged in series and encapsulated in a flexible and leak-tight packaging, and a supercapacitor module having at least one stack of several of these cells. The cell includes n unit cells (n≧2) arranged side by side in series and encapsulated in the packaging, each unit cell having two upper and lower electrodes, a membrane separating them and an ionic electrolyte, the cell having inside of the packaging a plurality of current collectors, two upper and lower collector parts of which respectively cover the upper and lower electrodes. A pair of adjacent unit cells is covered with an upper or lower collector common to this pair, two truncated upper and/or lower collectors formed at two ends of the cell, two adjacent collectors respectively terminated by facing edge sections electrically insulated from one another by an insulating adhesive material covering them.