Mixing element and accumulator with at least one mixing element

The element (1) has a hollow body provided with apertures (10, 11) such that a channel is formed in the hollow body. The channel opens the opening in opposite end portions. A periphery of a reservoir space (13) is greater than circumference of underlying portions of the mixing element such that the underlying portions form a thin flow channel (17) with respect to a cross-sectional area of the reservoir space. A periphery of the hollow body in an area of the flow channel below a transition is reduced from the reservoir space into the flow channel toward a lower end portion. An independent claim is also included for a rechargeable battery.