Method for rolling up definite lengths of a mats in a unidirectional rolled roll, where mats are advanced one after another into a rolling mechanism in flattened out condition and released from the mechanism in rolled up condition. A rolled up mat is ejected from the rolling mechanism and caused to roll out therefrom on top of a succeeding flattened out mat which advances towards the rolling mechanism. A mat rolling station for performing the method is provided, where a ramp conveyer is provided which advances a flattened mat towards the rolling mechanism. At the rolling mechanism, bending conveyers are provided for advancing the forwardly moving mat sections into a circular bend on the ramp conveyer. A difference of surface speeds of the bending conveyers and the ramp conveyer is controllable by a signal provoked by the advance of a succeeding mat on the ramp conveyer before the rolling mechanism.

Manufacturing machine (9) and method for manufacturing a cylindrical electrochemical cell (2) consisting of a spiral winding of a composite material (8) comprising at least two conductor bands (4, 6) and at least two separator bands (5, 7) overlapping one another. They are provided: a plurality of winding heads (13), each of which supports a holding device (14) which is configured to grab an end of the composite material (8) and to rotate on itself around a first rotation axis (15) so as to obtain a spiral winding of the composite material (8); a drum (11) which supports the winding heads (13) and which is mounted in a rotary manner so as to rotate with a continuous law of motion around a second rotation axis (12) in order to move the winding heads (13) along a processing path (P2); and a feeding unit (10) configured to feed the composite material (8) to the winding heads (13).

A mandrel member of a winder for a secondary battery, which is mounted in a winder configured to manufacture a jelly roll-type electrode assembly by winding a stack of a first electrode plate, a separator, and a second electrode plate, the mandrel member comprising a cylindrical body having a hollow portion, wherein the cylindrical body includes a plurality of slits having a planar shape to cross the cylindrical body in a hollow axis direction so that the hollow portion inside the cylindrical body is in fluid communication with the outside of the cylindrical body.