Abstract: To improve upon an accumulator (1) in a bipolar stack configuration comprising a number of sub-cells (9) arranged in layers within a housing (2) and separated by conductive partitions (8), wherein each sub-cell (9) has a positive (10) and a negative (11) electrode and a separator (12) between the electrodes (10, 11), as well as electrolytes in contact with the electrodes, such that the stack comprised of the sub-cells (9) can be fastened easily and safely via mechanical means, it is suggested that the stack, comprised of several sub-cells layered on top of one another be held in place via a force that will keep the individual elements (8, 10, 11, 12) of the stack in contact with one another with only a mechanical tie rod (14).