The present invention relates to a bipolar battery having at least two battery cells comprising: a negative end terminal, a positive end terminal and at least one biplate assembly arranged in a sandwich structure between the negative and positive end terminals. The battery also comprises a separator, with electrolyte, arranged between each negative and positive electrode forming a cell. An inner barrier of a hydrophobic material is arranged at least around one electrode on a first side of the biplate. An outer sealing, e.g. a frame, is provided around the edge of each biplate assembly and each end terminal and a hole is arranged through each biplate interconnecting each cell with adjacent cell(s) to create a common gas space for all cells in the battery. The invention also relates to a biplate assembly.