An electrochemical battery is disclosed. The electrochemical battery has an electrode plate comprising a frame and a generally flat grid connected to the frame, the frame comprising at least a top frame member having a contact lug, wherein the grid comprises a plurality of grid wires and a plurality of window-like open areas between the grid wires, further comprising an active mass within the open areas and/or on the grid wires, wherein the electrode plate comprises on one outer surface or on both opposing outer surfaces of the active mass a pattern of grooves, wherein the grooves extend diagonally from a position closer to the top frame member to a position further away from the top frame member. A method for producing an electrode plate is also disclosed.