Method and apparatus for winding electrode foils and one or more separator tapes together for the production of electrochemical cells

Abstract

Method and apparatus for making electrode foil assemblies and separators wound together for the production of electrochemical cells, which comprises a plurality of first accumulation devices that are configured to house pre-cut portions of a first electrode foil and a plurality of second accumulation devices that are configured to house pre-cut portions of a second electrode foil and a first and a second strip-shaped separator, wherein a first winding mandrel and a second winding mandrel are arranged downstream of the plurality of first accumulation devices and of the plurality of second accumulation devices. The first winding mandrel is configured to wind a first length of the first electrode foil unwound from a first accumulation device of the plurality of first accumulation devices, a first length of the second electrode foil from a first accumulation device of the plurality of second accumulation devices, and the first strip-shaped separator forming a first winding. The second winding mandrel is configured to wind a second length of the first electrode foil from a second accumulation device of the plurality of first accumulation devices, a second length of the second electrode foil from a second accumulation device of the plurality of second accumulation devices, and the second strip-shaped separator forming a second winding.

Description

[0001] Method and apparatus for winding electrode foils and one or more separator tapes together for the production of electrochemical cells

[0002] DESCRIPTION

[0003] The present invention refers to a winding apparatus and to a method for winding electrode foils and one or more separator strips together.

[0004] The present invention is particularly usable in a process for making electrochemical cells, for example secondary electrochemical cells, comprising electrodes separated from each other by a dielectric separator, typically a stripshaped separator.

[0005] One type of electrochemical cells, called jelly roll or Sw / ss roll, provides that a strip-shaped separator is interposed between two electrode foils, in particular an anode and a cathode, and that the multilayer composed of separator and electrode foils is wound to form an electrochemical cell of cylindrical or almost cylindrical shape. Typically, two separators are used: an internal separator between anode and cathode and an external separator in contact with one of the two electrodes.

[0006] Typically, in order to make this type of electrochemical cells, winding apparatuses are used which provide a winding mandrel rotatable around its own longitudinal axis. Free ends of the first electrode foil, of the separator and of the second electrode foil are associated with the winding mandrel which is placed in rotation around its own longitudinal axis causing the winding of the electrode foils and of the separator between them.

[0007] In the Applicant's experience, in order to feed the materials to the winding mandrel, the electrode foils and the one or more separators are unwound from respective feeding reels so as to be wound in the winding mandrel, at which each material is cut by separating from the respective feeding reel. The winding mandrel is driven in rotation making the jelly roll type winding of the electrode foils and separators. Often, the winding mandrel is mounted on a rotatable forming station for finishing the product and unloading it.

[0008] In some types of automatic winding machines, the aforementioned operations are carried out by stopping the winding at the step of introducing and of cutting each material from the respective feeding roller.

[0009] In the Applicant's experience, in other types of machines the separator and the electrode foils are unwound continuously from the respective feeding reels and the winding is carried out without stopping the product, reducing instead the winding speed of the mandrel in preparation for the step of cutting the materials from the respective feeding reels.

[0010] In particular, the Applicant has noted that, once the materials of the jelly roll assembly have been constrained to the winding mandrel, they are rotated at a predetermined and relatively fast winding speed. In preparation for the cutting of a material, the rotation speed is reduced in order to carry out the cutting operations with the required accuracy and precision.

[0011] The Applicant has also observed that the increasingly stringent quality specifications of the assembly both in relation to the length of the materials that make up the layers of the assembly and to the dimensional tolerances for the alignments between the layers actually require relatively significant speed reductions with a consequent increase in the production cycle time of the assembly. In order to avoid tugging in the material, it is also often preferable that the reduction in rotation speed is gradual, which condition can lead to a further increase in cycle time.

[0012] In the Applicant's experience, in some production processes, in order to ensure a better electrical insulation between anode and cathode, it is preferable that the cutting of each electrode is carried out before having finished the winding that makes the jelly roll so that the last wound layers consist only of separator material. Cutting the electrode foils from the respective feeding roller before cutting the separator strip or strips and thus before finishing the winding of the materials requires variations in winding speed (deceleration before cutting and acceleration after cutting) for each material. This, in addition to affecting the cycle time, makes the production process and its control and supervision complex.

[0013] The Applicant has perceived that the possibility of pre-cutting the electrode foils at a length suitable for the formation of the assembly was interposed between the winding mandrel and the material feeding rollers and in such a way that the “precut” foils are supplied to the winding mandrel, the number of jelly roll assemblies per unit of time would increase compared to a production process with the characteristics described above.

[0014] The Applicant has understood that the provision of accumulation devices that house pre-cut portions of electrode foil allows to decouple the continuous supply of the electrode foils from the feeding rollers to the winding mandrel. In particular, the provision of at least one respective temporary accumulation device for the first and second foil on which a length of electrode foil cut from the respective feeding roller is wound allows to eliminate the need to stop or slow down the winding speed of the electrode foil in the winding mandrel and therefore to improve the efficiency of the production cycle, simplifying also the step of making the multilayer and its control.

[0015] The Applicant has also observed that decoupling the preparation of the lengths of the electrode foils from the winding of the jelly roll assembly may allow the preparation of separate products in temporal overlap with each other. In particular, it is possible, with a single reel of electrode foil, to prepare the material for an anode or for a cathode for two distinct windings in a respective mandrel, further reducing production cycles.

[0016] The present invention therefore concerns a method for making assemblies of electrode foils and one or more separators wound together for the production of electrochemical cells.

[0017] Preferably, the method comprises unwinding from a first electrode reel a first electrode foil and winding at least a first and a second length of the first electrode foil on a respective first accumulation device and a second accumulation device of a plurality of first accumulation devices arranged in sequence and at a distance from each other along a first advancement path.

[0018] Preferably, each accumulation device of the plurality of first accumulation devices is rotatable around its own rotation axis and is movable along the first advancement path.

[0019] Preferably, the method comprises unwinding from a second electrode reel a second electrode foil and winding at least a first and a second length of the second electrode foil on a respective first accumulation device and a second accumulation device of a plurality of second accumulation devices arranged in sequence and at a distance from each other along a second advancement path. Preferably, each accumulation device of the plurality of second accumulation devices is rotatable around its own rotation axis and is movable along a second advancement path.

[0020] Preferably, subsequently to winding at least a first and a second length of the first electrode foil and to winding at least a first and a second length of the second electrode foil, the method comprises unwinding the first length of the first electrode foil from the first accumulation device of the plurality of first accumulation devices, the first length of the second electrode foil from the first accumulation device of the plurality of second accumulation devices, and unwinding a first strip-shaped separator from a first separator reel of a first stripshaped separator, and winding the first length of the first electrode foil, the first strip-shaped separator and the first length of the second electrode foil on a first winding mandrel arranged downstream with respect to the plurality of first accumulation devices and to the second plurality of accumulation devices. Preferably, subsequently to winding at least a first and a second length of the first electrode foil and to winding at least a first and a second length of the second electrode foil, the method comprises unwinding the second length of the first electrode foil from the second accumulation device of the first plurality of accumulation devices, the second length of the second electrode foil from the second accumulation device of the second plurality of accumulation devices and a second strip-shaped separator from a second separator reel and winding the second length of the first electrode foil, the second strip-shaped separator and the second length of the second electrode foil on a second winding mandrel arranged downstream with respect to the plurality of first accumulation devices and to the plurality of second accumulation devices.

[0021] The present invention further concerns a winding apparatus for making assemblies of electrode foils and one or more separators wound together for the production of electrochemical cells.

[0022] Preferably, the apparatus comprises a first unwinding roller configured to house a first electrode reel of a first electrode foil and a plurality of first accumulation devices arranged in sequence, at a distance from each other along a first advancement path and movable along the first advancement path, wherein each first accumulation device is rotatable around its own rotation axis and is configured to receive and to wind a length of the first electrode foil from the first electrode reel.

[0023] Preferably the apparatus comprises a second unwinding roller configured to house a second electrode reel of a second electrode foil and a plurality of second accumulation devices arranged in sequence, at a distance from each other along a second advancement path and movable along the second advancement path, wherein each accumulation device of the plurality of second accumulation devices is rotatable around its own rotation axis and is configured to receive and to wind a length of the second electrode foil from the second electrode reel.

[0024] Preferably, the apparatus comprises a third unwinding roller configured to house a first separator reel of a first strip-shaped separator.

[0025] Preferably, the apparatus comprises a fourth unwinding roller configured to house a second separator reel of a second strip-shaped separator.

[0026] Preferably, the apparatus comprises a first winding mandrel rotatable around its own winding axis and arranged downstream of the plurality of first accumulation devices and of the plurality of second accumulation devices, wherein the first winding mandrel is configured to receive a first length of the first electrode foil from a first accumulation device of the plurality of first accumulation devices, the first strip-shaped separator from the third unwinding roller, and a first length of the second electrode foil from a first accumulation device of the second plurality of accumulation devices.

[0027] Preferably, the apparatus comprises a second winding mandrel rotatable around its own winding axis and arranged downstream of the plurality of first accumulation devices and of the plurality of second accumulation devices, wherein the second winding mandrel is configured to receive a second length of the first electrode foil from a second accumulation device of the plurality of first accumulation devices, the second strip-shaped separator from the fourth unwinding roller and a second length of the second electrode foil from a second accumulation device of the plurality of second accumulation devices.

[0028] By “electrode foil” is meant a strip or foil having a dimension (i.e. length) much larger than two additional dimensions, wherein a first dimension of such two additional dimensions is much larger than a second dimension of such two additional dimensions. The electrode foil can be a monolithic strip (or foil) or a strip formed by a plurality of layers joined together made of identical material or different materials, possibly coated at least in part with an active material for electrodes. The electrode foil also has characteristics that allow some bending during its use.

[0029] By “strip-shaped separator” is meant a strip having a dimension that is much larger than two further dimensions, wherein a first dimension of such two further dimensions is much larger than a second dimension of such two further dimensions. The strip can be monolithic or formed by a plurality of layers joined together made of identical material or different materials. The separator strip is made of or coated with dielectric material. The strip-shaped separator also has characteristics such as to allow some bending during its use.

[0030] The term “adhesive”, in particular referred to an adhesive tape, refers to the ability of a body to attach to a surface on which it is applied, for example by means of an adhesive provided on the body.

[0031] The expression “upstream” means, unless otherwise specified, a position which, along a direction of forming of the jelly-roll winding or with respect to a direction of unwinding of a strip-shaped element, is placed towards the respective feeding reel and / or away from the forming station. The expression “downstream” means, unless otherwise specified, a position which, along a direction of forming of the jelly-roll winding and / or with respect to a direction of unwinding of a strip-shaped element, is placed away from the respective strip-shaped element feeding reel and / or towards the forming station.

[0032] By “strip-shaped element”, unless otherwise specified, is meant an electrode foil or a strip-shaped separator.

[0033] Typically, the electrode foils are composed of different materials. The foils comprise a thin metal layer, for example of copper or aluminium, which is coated on one side or both sides with an electrochemically active material. In other examples, the electrode foils may comprise a polymeric binder, a conductive additive, and an electrochemically active material. The main function of the polymeric binder is to retain the active material together with the conductive additive.

[0034] The anode and the cathode of a winding are formed starting from a respective electrode foil.

[0035] The separators are typically strip-shaped elements consisting of an electrically insulating material, for example an electrically insulating polymeric membrane and are referred to in the present description and claims as strip-shaped separators.

[0036] Preferably, each strip-shaped element is fed by a respective reel continuously, in the form of strip-shaped separators or continuous foils.

[0037] Preferably, each accumulation device of the first accumulation devices comprises a first accumulation roller rotatable around a first winding pin coinciding with its own rotation axis. In one embodiment, a length of first electrode foil is wound on and unwound from the first accumulation roller of the accumulation device of the plurality of first accumulation devices.

[0038] Preferably, each accumulation device of the second accumulation devices comprises a second accumulation roller rotatable around a second winding pin coinciding with its own rotation axis. In one embodiment, a length of second electrode foil is wound on and unwound from the second accumulation roller of the accumulation device of the second accumulation devices.

[0039] Preferably, the first winding mandrel is arranged downstream with respect to the plurality of first accumulation devices, to the second plurality of accumulation devices and to the first separator reel.

[0040] Preferably, the second winding mandrel arranged downstream with respect to the plurality of first accumulation devices, to the plurality of second accumulation devices and to the second separator reel.

[0041] Preferably, unwinding the first length of the first electrode foil, the first stripshaped separator and the first length of the second electrode foil comprises simultaneously unwinding the first length of the first electrode foil, the first stripshaped separator and the first length of the second electrode foil.

[0042] Preferably, the winding on the first winding mandrel is simultaneous with the unwinding of the first length of the first electrode foil, the first strip-shaped separator and the first length of the second electrode foil.

[0043] Preferably, unwinding the second length of the first electrode foil, the second strip-shaped separator and the second length of the second electrode foil comprises simultaneously unwinding the second length of the first electrode foil, the second strip-shaped separator and the second length of the second electrode foil.

[0044] Preferably, the winding on the second winding mandrel is simultaneous with the unwinding of the second length of the first electrode foil, the second strip-shaped separator and the second length of the second electrode foil.

[0045] Preferably, there is defined a forming direction that extends in the unwinding direction of the first and second electrode foil from the respective feeding reels to the production of jelly roll type windings.

[0046] Preferably, the first strip-shaped separator is unwound from the first separator reel to be directly wound on the first winding mandrel.

[0047] Preferably, the second strip-shaped separator is unwound from the second separator reel to be directly wound on the second winding mandrel.

[0048] Preferably, the method comprises, subsequently to winding the first and second length of the first electrode foil on a respective first and second accumulation device of the plurality of first accumulation devices and prior to unwinding the first and second length from said first and second accumulation device, cutting the first electrode foil from the first electrode reel, upstream of the respective first and second accumulation device of the plurality of first accumulation devices.

[0049] Preferably, subsequently to winding the first and second length of the second electrode foil on a respective first and second accumulation device of the plurality of second accumulation devices and prior to unwinding the first and second length from said first and second accumulation device of the plurality of second accumulation devices, cutting the second electrode foil from the second electrode reel, upstream of the respective first and second accumulation device of the plurality of second accumulation devices.

[0050] Preferably, simultaneously with unwinding the first length of the first electrode foil, of the first length of the second electrode foil and of the first strip-shaped separator, the method comprises unwinding a third strip-shaped separator from a third separator reel.

[0051] Preferably, the third strip-shaped separator is unwound from the third separator reel to be directly wound to the first winding mandrel simultaneously with the winding of the first length of the first electrode foil, the first length of the second electrode foil and of the first strip-shaped separator.

[0052] Preferably, simultaneously with the unwinding of the second length of the first electrode foil, of the second length of the second electrode foil and of the second strip-shaped separator, the method comprises unwinding a fourth strip-shaped separator from a fourth separator reel.

[0053] Preferably, the fourth strip-shaped separator is unwound from the fourth separator reel to be directly wound to the second winding mandrel simultaneously with the winding of the second length of the first electrode foil, the second length of the second electrode foil and the second strip-shaped separator.

[0054] Preferably, the first winding mandrel is arranged at a first winding position downstream of the first and second plurality of accumulation devices.

[0055] Preferably, the second winding mandrel is arranged at a second winding position arranged downstream of the first and second plurality of accumulation devices. The first winding position and the second winding position are arranged with respect to each other in a direction transverse with respect to the forming direction.

[0056] Preferably, the accumulation devices of the plurality of first accumulation devices advance and stop intermittently along the first advancement path.

[0057] Preferably, the accumulation devices of the plurality of first accumulation devices are arranged in sequence and at a distance from each other along the first advancement path.

[0058] In one embodiment, the first accumulation devices are arranged equidistant from each other along the first advancement path.

[0059] Preferably, the accumulation devices of the plurality of second accumulation devices advance and stop intermittently along the second advancement path.

[0060] Preferably, the accumulation devices of the plurality of second accumulation devices are arranged in sequence and at a distance from each other along the second advancement path.

[0061] In one embodiment, the second accumulation devices are arranged equidistant from each other along the second advancement path.

[0062] Preferably, the first and second advancement path are circular.

[0063] Preferably, advancing the accumulation devices of the plurality of first accumulation devices comprises moving the accumulation devices by one step between successive positions of a first plurality of positions defined along the first advancement path for a first movement time interval, tMi, and stopping the advancement of the accumulation devices of the first plurality of accumulation devices subsequently to each advancement by one step for a first stop time interval, tsi.

[0064] Preferably, the accumulation devices of the plurality of first accumulation devices are mounted rotatably around the respective rotation axis on a first support structure rotatable around a first transfer axis.

[0065] Preferably, the method comprises advancing the first support structure around the first transfer axis so as to define the first advancement path along which the accumulation devices are arranged at a distance from each other.

[0066] Preferably, the first support structure is configured to rotate around its own first transfer axis, the rotation defining the first advancement path along which the plurality of first accumulation devices move.

[0067] Preferably, the first support structure is a horizontal conveyor, in particular it is a transfer wheel.

[0068] Preferably, advancing the accumulation devices of the plurality of second accumulation devices comprises moving each accumulation device by one step between successive positions of a second plurality of positions defined in the second advancement path for a second movement time interval, tM2, and stopping the advancement of the accumulation devices of the second plurality of accumulation devices subsequently to each advancement by one step for a second stop time interval, ts2.

[0069] Preferably, the accumulation devices of the plurality of second accumulation devices are mounted rotatably around the respective own rotation axis on a second support structure rotatable around a second transfer axis.

[0070] Preferably, the method comprises advancing the second support structure around the second transfer axis so as to define the second advancement path along which the second accumulation devices are arranged at a distance from each other.

[0071] Preferably, the second support structure is configured to rotate around its own second transfer axis, the rotation defining the second advancement path along which the plurality of second accumulation devices move.

[0072] Preferably, the second support structure is a horizontal conveyor, in particular it is a transfer wheel.

[0073] Preferably, the first and second support structure are arranged in alignment with respect to each other in a direction transverse, preferably substantially perpendicular, to the forming direction.

[0074] Preferably, the first and second support structure are substantially aligned with each other along a direction perpendicular with respect to the forming direction. Preferably, the first plurality of positions comprises a first loading position and a plurality of first unloading positions, the plurality of first unloading positions being arranged downstream of the first loading position with respect to the first advancement path.

[0075] Preferably, at the first loading position each accumulation device of the plurality of first accumulation devices is positioned to receive the first electrode foil from the first electrode reel and to wind a length of the first electrode foil thereon.

[0076] Preferably, unwinding the first length of the first electrode foil from the first accumulation device and the second length from the second accumulation device of the plurality of first accumulation devices is at the plurality of first unloading positions.

[0077] Preferably, the first plurality of positions corresponds in number to the plurality of first accumulation devices.

[0078] Preferably the unloading positions of the first plurality of unloading positions are adjacent to each other.

[0079] Preferably, the second plurality of positions along the second advancement path comprises a second loading position and a plurality of second unloading positions, the plurality of second unloading positions being arranged downstream of the second loading position with respect to the first advancement path.

[0080] Preferably, at the second loading position each accumulation device of the plurality of second accumulation devices is positioned to receive the second electrode foil from the second electrode reel and to wind a length of the second electrode foil thereon.

[0081] Preferably, unwinding the first length of the second electrode foil from the first accumulation device and the second length from the second accumulation device of the plurality of second accumulation devices is at the plurality of second unloading positions of the second plurality of positions.

[0082] Preferably, the second plurality of positions corresponds in number to the plurality of second accumulation devices.

[0083] Preferably the unloading positions of the second plurality of unloading positions are adjacent to each other.

[0084] Preferably, the intermittent movement of the first accumulation devices is synchronous with the intermittent movement of the second accumulation devices. In particular, the first stop time interval, tsi, is equal to or substantially equal to the second stop time interval, ts2, and the first movement time interval, tMi, is equal to the second movement time interval tM2.

[0085] Preferably, the plurality of first unloading positions comprises or consists of a first unloading position, a second unloading position and a third unloading position. Preferably, the method comprises partially unwinding the first length of the first electrode foil from the first accumulation device of the plurality of first accumulation devices at the first unloading position of the first plurality of unloading positions and simultaneously partially unwinding the second length of the first electrode foil from the second accumulation device of the first plurality of accumulation devices at the second unloading position, wherein partially unwinding the first and second length of the first electrode foil is carried out simultaneously with the winding of a length of the first electrode foil at the first loading position.

[0086] Preferably, while continuing to partially unwind the first and second length of the first electrode foil, the method comprises advancing the plurality of first accumulation devices by one step so as to move the first accumulation device from the first unloading position to the second unloading position and the second accumulation device from the second unloading position to the third unloading position.

[0087] Preferably, simultaneously with the winding of a successive length of first electrode foil positioned at the first loading position, the method comprises continuing to unwind the first length of first electrode foil from the first accumulation device of the first plurality of accumulation devices at the second unloading position of the first plurality of unloading positions and continuing to unwind the second length of first electrode foil from the second accumulation device of the first plurality of accumulation devices at the third unloading position of the first plurality of unloading positions completing the unwinding of the first length and of the second length of first electrode foil.

[0088] Preferably, the partial unwinding of the first length and second length of the first electrode foil from the respective accumulation device is in a first stop time interval tsi . The continuation of the partial unwinding of the first and second length of the first electrode foil continues during the advancement by one step is in a first movement time interval, tMi. The completion of the unwinding of the first and second length of the first electrode foil and simultaneous winding of a further length of the first electrode foil is in a first stop time interval tsi .

[0089] Preferably, the unwinding time of a length from an accumulation device of the first accumulation devices, tui , is approximately equal to (2tsi + tMi).

[0090] Preferably, the plurality of second unloading positions of the second plurality of positions comprises or consists of a fourth unloading position, a fifth unloading position and a sixth unloading position.

[0091] Preferably, the method comprises partially unwinding the first length of the second electrode foil from the first accumulation device of the plurality of second accumulation devices at the fourth unloading position of the plurality of second unloading positions and simultaneously partially unwinding the second length of the second electrode foil from the second accumulation device of the second plurality of accumulation devices at the fifth unloading position of the second plurality of unloading positions, wherein partially unwinding the first and second length of the second electrode foil is carried out simultaneously with the winding of a length of the second electrode foil at the second loading position.

[0092] Preferably, by continuing to partially unwind the first and second length of the second electrode foil, the method comprises advancing the plurality of second accumulation devices by one step so as to move the first accumulation device of the plurality of second accumulation devices from the fourth unloading position to the fifth unloading position and the second accumulation device of the plurality of second accumulation devices from the fifth unloading position to a sixth unloading position.

[0093] Preferably, simultaneously with the winding of a successive length of second electrode foil positioned at the second loading position, the method comprises continuing to unwind the first length of second electrode foil from the first accumulation device of the plurality of second accumulation devices at the fourth unloading position of the second plurality of the unloading positions and continuing to unwind the second length of the second electrode foil from the second accumulation device of the second plurality of accumulation devices at the sixth unloading position of the second plurality of unloading positions completing the unwinding of the first length and of the second length of second electrode foil.

[0094] Preferably, the partial unwinding of the first length and second length of the second electrode foil from the respective first and second accumulation device is in a second stop time interval ts2. The continuation of the partial unwinding of the first and second length of the second electrode foil continues during the advancement by one step is in a second movement time interval, tM2. The completion of the unwinding of the first and second length of the second electrode foil and the simultaneous winding of a further length of the second electrode foil is in a second stop time interval ts2.

[0095] Preferably, the unwinding time of a length from an accumulation device of the second accumulation devices, tu2, is approximately equal to (2ts2 + tM2).

[0096] Further characteristics and advantages of the present invention will become clearer from the following detailed description of a preferred embodiment thereof, with reference to the appended drawings and provided by way of indicative and non-limiting example, in which: figure 1 is a schematic top view of an apparatus for winding electrode foils and one or more separators together for making a plurality of assemblies for the production of electrochemical cells, in accordance with an embodiment; figure 2A schematically illustrates an example of arrangement of the plurality of first accumulation devices on a first support structure at a first time instant; figure 2B schematically illustrates an example of arrangement of the plurality of first accumulation devices of figure 2A at a second time instant subsequent to the first time instant; figure 3A schematically illustrates an example of arrangement of the plurality of second accumulation devices on a second support structure at a first time instant; figure 3B schematically illustrates an example of arrangement of the plurality of second accumulation devices of figure 3A at a second time instant subsequent to the first time instant; figure 4 is a top view of an accumulation device of the plurality of first accumulation devices in which some parts of it are indicated; figure 5 is a top view of an accumulation device of the plurality of second accumulation devices in which some parts of it are indicated; figure 6A is a schematic top view of a first winding mandrel according to an embodiment; figure 6B is a schematic top view of a second winding mandrel according to an embodiment; figure 7 is a top view of a first forming station of the apparatus of figure 1 for making a first jelly-roll assembly, in which further details are shown; figure 8 shows the first forming station of figure 7 which is rotated in a successive position along a first forming advancement path; figure 9 is a top view of a second forming station of the apparatus of figure 1 for making a second jelly-roll assembly, in which further details are shown, and figure 10 shows the second forming station of figure 9 which is rotated in a successive position along a second forming advancement path.

[0097] The representations in the accompanying figures do not necessarily have to be understood in scale and do not necessarily respect the proportions between the various parts. In the figures, the same or similar elements of different embodiments will be indicated by the same reference numerals.

[0098] Figure 1 schematically illustrates a winding apparatus 10 for winding electrode foils and one or more separators together for making assemblies for the production of electrochemical cells. In the embodiment illustrated in the figures, the winding apparatus 10 is configured for the production of two assemblies in temporal overlap with each other.

[0099] The apparatus 10 comprises a plurality of unwinding rollers 1 -6 for feeding stripshaped elements, wherein each unwinding roller is configured to house a respective strip-shaped element reel.

[0100] The apparatus 10 comprises a first unwinding roller 1 configured to house and unwind a first electrode reel 11 of a first electrode foil 22 and a second unwinding roller 2 configured to house and unwind a second reel 12 of a second electrode foil 24.

[0101] A third unwinding roller 3 is configured to house and unwind a first reel 13 of a first strip-shaped separator 21 , hereinafter indicated with first separator reel 13.

[0102] A fourth unwinding roller 4 is configured to house and unwind a second reel 14 of a second strip-shaped separator 23, hereinafter indicated with second separator reel 14.

[0103] In the embodiments of the figures, the apparatus 10 further comprises a fifth unwinding roller 5 configured to house and unwind a third reel 15 of a third stripshaped separator 25, hereinafter indicated with third separator reel 15. A sixth unwinding roller 6 is configured to house and unwind a fourth reel 16 of a fourth strip-shaped separator 26, hereinafter indicated with a fourth separator reel 16. The winding apparatus 10 comprises a first winding mandrel or winder mandrel 43 rotatable around its own winding axis V3 (figure 6A). The first winding mandrel 43 is arranged at a first forming station 41 (figures 1 ,7-8).

[0104] In the embodiment of figure 6A, the winding mandrel 43 comprises two half-parts 43a and 43b which can be moved towards and away from each other to allow the free end of a strip-shaped element, in particular an electrode foil or a strip-shaped separator, to be inserted between the two half-parts by moving the two half-parts apart and to retain a strip-shaped element between them by bringing the two halfparts closer together.

[0105] Once the free ends of each strip-shaped element have been inserted, the first winding mandrel 43 is configured to rotate around its own winding axis, making the winding of the electrode foils and of the separators.

[0106] The apparatus 10 comprises a second winding mandrel 45 rotatable around its own winding axis V4 (figure 6B). The second unwinding mandrel 45 is arranged at a second forming station 42 (figures 1 , 9-10).

[0107] In the embodiment of figure 6B, the winding mandrel 45 comprises two half-parts 45a and 45b which can be moved towards and away from each other to allow the free end of a strip-shaped element, in particular an electrode foil or a strip-shaped separator, to be inserted between the two half-parts by moving the two half-parts apart and to retain a strip-shaped element between them by bringing the two halfparts closer together.

[0108] Once the free ends of each strip-shaped element have been inserted, the second winding mandrel 45 is configured to rotate on its own winding axis, making the winding of the electrode foils and of the separators.

[0109] The winding will be indicated hereinafter also as an assembly. Each winding mandrel 43, 45 has the function of winding together the strip-shaped elements that make a jelly roll type winding.

[0110] The apparatus 10 comprises a plurality of first accumulation devices 35.

[0111] The plurality of the first accumulation devices 35 is arranged downstream of the first electrode reel 11 of the first electrode foil 22.

[0112] Each accumulation device 35 is rotatable around its own rotation axis V1 and is configured to receive and to wind a length 27 (figure 4) of the first electrode foil 22 from the first electrode reel 11 . In particular, each accumulation device 35 of the plurality of first accumulation devices comprises a respective first accumulation roller 39 rotatable around a first winding pin 37 coinciding with the rotation axis V1 . The first accumulation roller 39 comprises an outer surface (not indicated) configured to receive thereon a length of electrode foil 27.

[0113] Each accumulation device 35 of the plurality of first accumulation devices is rotatable around the rotation axis V1 in two opposite directions, a first direction for winding the first electrode foil and a second direction for unwinding a portion of the first electrode foil.

[0114] The accumulation devices of the plurality of first accumulation devices 35 are arranged in sequence and at a distance from each other along a first advancement path 32 and are movable along said first advancement path.

[0115] The plurality of first accumulation devices 35 is arranged on a first support structure 31 which is configured to rotate around its own first transfer axis T1 , the rotation defining the first advancement path 32.

[0116] The accumulation devices 35 of the plurality of first accumulation devices are mounted rotatably around their own rotation axis V1 on the first support structure 31. Each first accumulation device 35 rotates simultaneously about its own rotation axis V1 and about the first transfer axis T1 of the first support structure 31 along the first advancement path 32.

[0117] The first transfer axis T1 is parallel to the rotation axes V1 of the accumulation devices of the plurality of accumulation devices 35.

[0118] The rotation axes V1 of the first accumulation devices are motorized to impart the rotation of the respective accumulation devices 35 in the two directions for winding and unwinding. The rotation of the first support structure 31 along the first advancement path 32 is driven by an electric motor (not shown).

[0119] In the embodiments illustrated in the figures, the first support structure 31 is a horizontal conveyor, in particular a transfer wheel.

[0120] The first electrode reel 11 feeds a portion of the first electrode foil 22 to each accumulation device of the first accumulation devices 35 along a feeding direction F1.

[0121] The accumulation devices of the plurality of first accumulation devices 35 move forward and stop intermittently along the first advancement path 32.

[0122] The first support structure 31 rotates around the first transfer axis T 1 to bring, one after the other, each accumulation device 35 of the plurality of first accumulation devices into a position adapted to receive the first electrode foil 22, said position being indicated hereinafter with first loading position A1 (figures 2A and 2B). In particular, at the first loading position A1 , the accumulation device 35 is configured to receive the first electrode foil 22 from the first electrode reel 11 .

[0123] More in general, each accumulation device 35 of the first accumulation devices moves by one step between two next adjacent positions of a first plurality of positions defined along the first advancement path 32.

[0124] The first plurality of positions comprises the first loading position A1 and a first plurality of unloading positions A2, A3 and A4 indicated in figures 2A and 2B and described more in detail hereinafter.

[0125] Subsequently to each step between next adjacent positions of the first advancement path 32, the first accumulation devices 35 stop for a time interval indicated hereinafter with first stop time interval, tsi .

[0126] The time interval in which the first accumulation devices 35 move by one step, i.e. between two next adjacent positions, is indicated with first movement time interval, tMi.

[0127] The first stop time interval, tsi , is selected in such a way as to allow the winding of a length 27 on an accumulation device 35 of the plurality of first accumulation devices.

[0128] Preferably, the first movement time interval tivn is less than the first stop time interval tsi .

[0129] In one embodiment, the stop time tsi also takes into account the time necessary for the introduction of the first electrode foil into the accumulation device arranged at the first loading position A1 and, as described hereinafter, of the time necessary for the introduction of the material for unwinding a length from the accumulation device.

[0130] In embodiments, tsi is at least twice greater than tMi.

[0131] More in general, the values of tsi and tMi can be defined with reference to the distance between two successive positions of the accumulation devices on the support structure or to the advancement speed of the transfer wheel 31 and / or by means of a suitable relationship between the values tsi and tMi.

[0132] Figure 2A schematically illustrates an example of arrangement of the plurality of first accumulation devices 35 on the first support structure 31 at a first time instant.

[0133] The number of first accumulation devices and, as specified below, the number of second accumulation devices, illustrated in the figures equal to six, is to be understood as non-limiting.

[0134] A first electrode foil 22, which extends along a first feeding direction F1 , is unwound from the first electrode reel to be wound on respective first accumulation devices 35a-35f when placed at the first loading position A1. In the illustrated example, the plurality of first accumulation devices 35 is formed by a first accumulation device 35a, a second accumulation device 35b, a third device 35c, a fourth accumulation device 35d, a fifth device 35c, and a first accumulation device 35a. The fifth accumulation device 35e is placed at the first loading position A1 and rotates around its own rotation axis V1 to wind the first electrode foil 22 on the outer surface of the first accumulation roller 39.

[0135] Prior to the winding of the first electrode foil 22 and in ways known per se and not depicted in detail, a free end of the first electrode foil (not shown) was inserted into the accumulation device 35e placed in the first loading position A1 by means of a first material introduction group 51 a. Once the winding is finished, the wound portion is cut off from the first electrode reel 11 by means of a first cutting device 52a so as to form a length 27 of the first electrode foil 22.

[0136] As described above, during the winding of a length of first electrode foil on an accumulation device of the plurality of first accumulation devices 35, the accumulation device positioned in A1 is stationary for a first stop time interval tsi . The winding apparatus 10 is configured to unwind a first and a second length 27 of first electrode foil 22 from two distinct accumulation devices of the first accumulation devices 35 when arranged at respective unloading positions of the first plurality of unloading positions, the unloading positions being positioned downstream of the loading position A1 with respect to the first advancement path 32.

[0137] The first plurality of unloading positions comprise and in the illustrated embodiment consist of, a first unloading position A2, a second unloading position A3 and a third unloading position A4. The first, second and third unloading position are arranged in sequence in the direction of the first advancement path 32.

[0138] In figure 2A, the first accumulation device 35a is arranged at the first unloading position A2 and the second accumulation device 35b is arranged at the second unloading position A3 which is next adjacent to the first unloading position A2. The second accumulation device 35b is arranged, along the first advancement path 32, downstream of the first accumulation device 35a. The first and second accumulation device 35a, 35b have previously received a respective first and second length 27, 27' of the first electrode foil 21 at the position A1 .

[0139] At the first unloading position A2, the first length 27 of the first electrode foil 22 is unwound from the first accumulation device 35a to be wound on the first winding mandrel 43 for the production of a first jelly-roll type assembly. At the second unloading position A3, the second length 27 of the first electrode foil 22 is unwound from the second accumulation device 35b to be wound on the second winding mandrel 45 for the production of a second jelly-roll type assembly.

[0140] At the first unloading position A2, the first length 27 of the first electrode foil 22 is partially unwound from the first accumulation device 35a. At the second unloading position A3, the second length 27' of the first electrode foil 22 is partially unwound from the second accumulation device 35b. The partial unwinding of the first length from the first accumulation device 35a and the partial unwinding of the second length from the second accumulation device 35b takes place in a first time interval tsi .

[0141] The partial unwinding from the first and second accumulation device 35a, 35b takes place simultaneously with the winding on the fifth accumulation device 35e arranged at the position A1 .

[0142] Still with reference to figure 2A, the sixth accumulation device 35f of the plurality of first accumulation devices represents a step in which the winding of a length has been completed and the accumulation device 35f has moved by one step with respect to the first loading position A1. The third and fourth accumulation device 35c and 35d are arranged downstream of the second accumulation device 35b. The accumulation devices 35c and 35d are devoid of the length 27 as it has already been unwound during the steps prior to the configuration illustrated in the figure.

[0143] Subsequently to the time interval tsi , the first support structure 31 rotates by one step in a first movement time interval tMi moving the first accumulation devices 35. In particular, the first accumulation device 35a moves from the first unloading position A2 to the second unloading position A3 and the second accumulation device 35b moves from the second unloading position A3 to the third unloading position A4.

[0144] The second unloading position A3 is next adjacent to the first unloading position A2 and the third unloading position A4 is next adjacent to the second unloading position A3.

[0145] During the first movement time interval tMi in which the first support structure 31 rotates by one step, the partial unwinding of the first length 27 from the first accumulation device 35a and the partial unwinding of the second length 27' from the second accumulation device 35b proceeds.

[0146] Figure 2B shows the arrangement of the plurality of first devices at a successive time in which the first accumulation devices have advanced by one step with respect to the arrangement of figure 2A. The first accumulation device 35a is arranged at the second unloading position A3 and the second accumulation device 35b is arranged at the third unloading position A4.

[0147] At the second unloading position A3, the first length of the first electrode foil 22 continues to be unwound continuously from the first accumulation device 35a until completion of the unwinding of the length. Similarly, at the third unloading position A4, the unwinding of the second length of the first electrode foil from the second accumulation device 35b is completed.

[0148] The completion of the unwinding of the first and second length 27, 27' of the first electrode foil 22 respectively from the first and second accumulation device 35a, 35b takes place in a time interval equal to or comprised in the first time interval tsi .

[0149] The winding time of a length at the first loading position A1 is approximately equal to the first time interval tsi .

[0150] The total unwinding time of a length from an accumulation device of the first accumulation devices 35, tui , is given approximately by the sum (tsi + tivn + tsi), i.e. tm = 2tsi + tMi. In case tMi << tsi , tin = 2tsi.

[0151] Approximately, in the unwinding time of a length of the first electrode foil from an accumulation device of the plurality of first accumulation devices 35, the winding of a length is carried out on two accumulation devices that are arranged in succession at the first loading position A1 .

[0152] In the configuration of figure 2B, the sixth accumulation device 35d is in the first loading position A1 and is configured to receive the first electrode foil 22 and to make the winding of a length 27. The winding of a length of first electrode foil 22 from the fourth accumulation device 35d is simultaneous with the completion of the unwinding of the lengths of the first electrode foil 22 from the first and second winding mandrel 43 and 45.

[0153] With reference to figure 2B, the fifth accumulation device 35e provided with the winding 27 is in a position subsequent to the first loading position A1 and the sixth accumulation device 35f is arranged at the first unloading position A2. However, in this unloading position, the unwinding of the length does not take place since the feeding of a respective length to the two winding mandrels 43, 45 is in progress.

[0154] In a step subsequent to the configuration of figure 2B and not shown in the figures, the fifth accumulation device 35e is positioned in A2 and the sixth accumulation device 35f is positioned in A3 for the introduction of a first and second length 27, 27' of the first electrode foil 22 respectively to the first winding mandrel 43 and to the second winding mandrel 45.

[0155] The apparatus 10 comprises a plurality of second accumulation devices 36.

[0156] The plurality of second accumulation devices 36 is arranged downstream of the second electrode reel 12 of the second electrode foil 24.

[0157] Each accumulation device 36 of the second plurality of accumulation devices is rotatable around its own rotation axis V2 (figure 5) in two opposite directions, a first direction for winding the second electrode foil and a second direction for unwinding a portion of the second electrode foil.

[0158] Each accumulation device 36 is configured to receive and to wind a length 28 (figure 5) of the second electrode foil 24 from the second electrode reel 12.

[0159] In particular, each accumulation device 36 of the plurality of second accumulation devices comprises a second accumulation roller 39' rotatable around a second winding pin 38 coinciding with the rotation axis V2. The second accumulation roller 39' comprises an outer surface (not indicated in figure 5) configured to receive thereon a length of the electrode foil 28.

[0160] The accumulation devices of the plurality of second accumulation devices 36 are arranged in sequence and at a distance from each other along a second advancement path 34 and are movable along said second advancement path.

[0161] The plurality of second accumulation devices 36 is arranged on a second support structure 33 which is configured to rotate around its own second transfer axis T2, the rotation defining the second advancement path 34.

[0162] The accumulation devices 36 of the plurality of second accumulation devices are mounted rotatably around their own rotation axis V2 on the second support structure 33. Each second accumulation device 36 rotates simultaneously around its own rotation axis V2 and around the second transfer axis T2 of the second support structure 33 along the second advancement path 34.

[0163] The second transfer axis T2 is parallel to the rotation axes V2 of the second accumulation devices 36.

[0164] Each accumulation device 36 of the second plurality of accumulation devices is rotatable around the rotation axis V2 in two opposite directions, a first direction for winding the first electrode foil and a second direction for unwinding a portion of the first electrode foil.

[0165] The rotation axes V2 are motorized to impart the rotation of the respective second accumulation devices 36 in the two opposite directions (winding and unwinding). The rotation of the second support structure 33 along the second advancement path 34 is driven by an electric motor (not shown).

[0166] In the embodiments illustrated in the figures, the second support structure 33 is a horizontal conveyor, in particular a transfer wheel.

[0167] The second electrode reel 12 feeds a portion of the second electrode foil 24 to each accumulation device of the second accumulation devices 36 along a feeding direction F2.

[0168] The second accumulation devices 36 move forward and stop intermittently along the second advancement path 34.

[0169] The second support structure 33 rotates around the second transfer axis T2 to bring, one after the other, each accumulation device 36 of the plurality of second accumulation devices into a position adapted to receive the second electrode foil 24, such position being indicated below with second loading position B1 (figures 3A and 3B). In particular, at the second loading position B1 , the accumulation device 36 is configured to receive the second electrode foil 24 from the second electrode reel 12.

[0170] More in general, each accumulation device of the second accumulation devices 36 moves by one step between two next adjacent positions of a second plurality of positions defined along the second advancement path 34.

[0171] The second plurality of positions comprises the second loading position B1 and a second plurality of unloading positions B2, B3 and B4 indicated in figures 3A and 3B and described more in detail hereinafter.

[0172] Subsequently to each step between next adjacent positions of the second advancement path 34, the second accumulation devices 36 stop for a time interval indicated hereinafter with second stop time interval, ts2.

[0173] The time interval in which the second accumulation devices 36 move by one step, i.e. between two next adjacent positions, is indicated with the second movement time interval, tM2.

[0174] The second stop time interval, ts2, is selected so as to allow the winding of a length 28 on an accumulation device 36 of the plurality of second accumulation devices.

[0175] Preferably, the second movement time interval tM2 is lower than the second stop time interval ts2.

[0176] In one embodiment, the stop time ts2 of the accumulation device also takes into account the time necessary for the introduction of the second electrode foil into the accumulation device arranged at the second loading position B1 and the time necessary for the introduction of the material for the unwinding of the length from an accumulation device.

[0177] In embodiments, ts2 is at least twice greater tM2.

[0178] More in general, the values of ts2 and tM2 may be defined with reference to the distance between two successive positions of the accumulation devices on the support structure or to the advancement speed of the transfer wheel 33 and / or by means of a suitable relationship between the values ts2 and tM2.

[0179] Figure 3A schematically illustrates an example of arrangement of the plurality of second accumulation devices 36 on the second support structure 33 at a first time instant.

[0180] A second electrode foil 24, which extends along a second feeding direction F3, is unwound from the second electrode reel 12 to be wound on respective second accumulation devices 36a-36f when placed at the second loading position B1. In the illustrated example, the plurality of second accumulation devices 36 is formed by a first accumulation device 36a, a second accumulation device 36b, a third device 36c, a fourth accumulation device 36d, a fifth device 36e, and a sixth accumulation device 36f. The fifth accumulation device 36e is placed at the second loading position B1 and rotates around its own winding axis V2 to wind the second electrode foil 24 on the outer surface of the second accumulation roller 39'.

[0181] Prior to the winding of the second electrode foil 24 and in ways known per se and not depicted in detail, a free end of the second electrode foil (not shown) was inserted into the accumulation device 36e placed in the second loading position B1 by means of a second material introduction group 51 b. Once the winding is finished, the wound portion is cut off from the second electrode reel 12 by means of a second cutting device 52b so as to form a length 28 of the second electrode foil 24. During the winding of a length of second electrode foil on an accumulation device of the plurality of second accumulation devices 36, the accumulation device positioned in B1 is stationary at a second stop time interval ts2.

[0182] The winding apparatus 10 is configured to unwind a first and a second length 28, 28' of second electrode foil 24 from two distinct accumulation devices of the second accumulation devices 36 when arranged at respective unloading positions of the second plurality of unloading positions, the unloading positions being positioned downstream of the second loading position B1 with respect to the second advancement path 34.

[0183] The second plurality of unloading positions consist of a fourth unloading position B2, a fifth unloading position B3 and a sixth unloading position B4. The fourth, fifth and sixth unloading position are arranged in sequence in the direction of the second advancement path 34.

[0184] In figure 3A, the first accumulation device 36a is arranged at the fourth unloading position B2 and the second accumulation device 36b is arranged at the fifth unloading position B3 which is next adjacent to the fourth unloading position B2. The second accumulation device 36b is arranged, along the second advancement path 34, downstream of the first accumulation device 35a. The first and second accumulation device 36a, 36b have previously received a respective first and second length 28, 28' of the second electrode foil 24 at the second loading position B1.

[0185] At the fourth unloading position B2, the first length 28 of the second electrode foil 24 is unwound from the first accumulation device 36a to be wound on the first winding mandrel 43 for the production of the first jelly-roll type assembly. At the fifth unloading position B3, the second length 28 of the second electrode foil 24 is unwound from the second accumulation device 36b to be wound on the second winding mandrel 45 for the production of the second jelly-roll type assembly.

[0186] At the fourth unloading position B2, the first length 28 of the second electrode foil 24 is partially unwound from the first accumulation device 36a. At the fifth unloading position B3, the second length 28' of the second electrode foil 24 is partially unwound from the second accumulation device 36b. The partial unwinding of the first length from the first accumulation device 36a and the partial unwinding of the second length from the second accumulation device 36b takes place in the second time interval ts2.

[0187] The partial unwinding from the first and second accumulation device 36a, 36b of the plurality of second accumulation devices takes place simultaneously with the winding on the fifth accumulation device 36e at the second loading position B1 .

[0188] Still with reference to figure 3A, the sixth accumulation device 36f of the plurality of second accumulation devices represents a step in which the winding of a length has been completed and the accumulation device 36f has moved by one step with respect to the second loading position B1. The third and fourth accumulation device 36c and 36d are arranged downstream of the second accumulation device 36b. The accumulation devices 36c and 36d are devoid of the length 28 as it has already been unwound during the steps prior to the configuration illustrated in the figure.

[0189] Subsequently to the second time interval ts2, the second support structure 33 rotates by one step in a second movement time interval tM2 moving the second accumulation devices 36. In particular, the first accumulation device 36a moves from the fourth unloading position B2 to the fifth unloading position B3 and the second accumulation device 36b moves from the fifth unloading position B3 to the sixth unloading position B4.

[0190] The fifth unloading position B3 is next adjacent to the fourth unloading position B2 and the sixth unloading position B4 is next adjacent to the fifth unloading position B3.

[0191] During the second movement time interval tM2 for the rotation of the second support structure 33 by one step, the partial unwinding of the first length 28 of the second electrode foil 24 from the first accumulation device 36a and the partial unwinding of the second length 28' from the second accumulation device 36b proceeds.

[0192] Figure 3B shows the arrangement of the plurality of first devices at a successive instant in which the second accumulation devices have advanced by one step with respect to the arrangement of figure 3A. The first accumulation device 36a is arranged at the fifth unloading position B3 and the second accumulation device 36b is arranged at the sixth unloading position B4.

[0193] At the fifth unloading position B3, the first length 28 of the second electrode foil 24 continues to be unwound continuously from the first accumulation device 36a until completion of the unwinding of the length. Similarly, at the sixth unloading position B4, the unwinding of the second length 28' of the second electrode foil from the second accumulation device 36b is completed.

[0194] The completion of the unwinding of the first and second length 28, 28' of the second electrode foil 28 respectively from the first and second accumulation device 36a, 36b takes place in a time interval equal to or comprised in the second time interval ts2.

[0195] The winding time of a length at the second loading position B1 is approximately equal to the second time interval ts2.

[0196] The total unwinding time of a length from an accumulation device of the second accumulation devices 36, tu2, is given approximately by the sum (ts2 + tM2 + ts2), i.e. tu2 = 2ts2 + tM2. In the case of tM2 << ts2, tu2 = 2ts2.

[0197] Approximately, in the unwinding time of a length of the second electrode foil 24 from an accumulation device of the plurality of second accumulation devices 36, the winding of a length is carried out on two accumulation devices that are arranged at the second loading position B1 .

[0198] In preferred embodiments, the first stop time interval is equal to the second stop time interval, tsi = ts2. The first movement time interval is equal to the second movement time interval, tMi = tM2. In this way, the intermittent movement of the first accumulation devices 35 is synchronous with the intermittent movement of the second accumulation devices 36.

[0199] In the configuration of figure 3B, the sixth accumulation device 35d is in the second loading position B1 and is configured to receive the second electrode foil 24 and to carry out a winding of a length 28.

[0200] The winding of a length of second electrode foil 24 from the fourth accumulation device 36d is simultaneous with the completion of the unwinding of the lengths of the second electrode foil 24 at the first and second winding mandrel 43 and 45. Still with reference to figure 3B, the fifth accumulation device 36e provided with the winding 28 is in a position subsequent to the second loading position B1 and the sixth accumulation device 36f is arranged at the fourth unloading position B2. However, in this unloading position, the unwinding of the length does not take place since the feeding of a respective length to the two winding mandrels 43, 45 is in progress.

[0201] In a step subsequent to the configuration of figure 3B and not shown in the figures, the accumulation device 36f is positioned in B2 and the accumulation device 36e is positioned in B3 for the introduction of a first and second length of the second electrode foil 24 respectively to the first winding mandrel 43 and to the second winding mandrel 45.

[0202] The first winding mandrel 43 is arranged at a first winding position C1 , in which the first mandrel is configured to receive a first length of the first electrode foil 22, the first strip-shaped separator 21 , a first length of the second electrode foil 24 and the second strip-shaped separator 26 (figures 1 , 7-8).

[0203] The second winding mandrel 45 is arranged at a second winding position D1 , in which the second mandrel is configured to receive a second length of the first electrode foil 21 , the second strip-shaped separator 23, a second length of the second electrode foil 24 and the fourth strip-shaped separator 26 (figures 1 , 9- 10).

[0204] The first and second winding position C1 , D1 are arranged downstream of the plurality of first accumulation devices 35 and of the plurality of second accumulation devices 36.

[0205] In one embodiment, the first and second winding position C1 , D1 are arranged in substantial alignment with respect to each other in a direction transverse, preferably substantially perpendicular, to the forming direction PD.

[0206] With reference to figures 1 and 7, the first winding mandrel 43 is mounted on the first conveyor 41 which comprises a third support structure 47 configured to rotate around its own transfer axis T3, indicated with third transfer axis, along a first forming path 44. In particular, the first winding mandrel 43 is mounted on the third support structure 47. The rotation of the third support structure 47 along the first forming path 44 is driven by an electric motor (not shown). The third support structure 47 is in particular a horizontal conveyor, for example a transfer wheel.

[0207] The winding axis V3 of the first winding mandrel 43 (figure 6a) is motorized to impart the rotation and make a winding.

[0208] During winding on the first winding mandrel 43, the first length 27 of the first electrode foil 22 is unwound along a first unwinding path U1 which extends from the first accumulation device 35a to the first unwinding mandrel 43. Since the unwinding of the first length 27 of the first electrode foil 21 is carried out at two different positions of the first advancement path 32, the direction of the first unwinding path U1 changes when the support structure 31 moves by one step.

[0209] Still during winding on the first winding mandrel 43, the first length 28 of the second electrode foil 24 is unwound along a third unwinding path U3 which extends from the first accumulation device 36a of the second accumulation devices 36 to the first unwinding mandrel 43. Since the unwinding of the first length 28 of the second electrode foil is carried out at two different positions of the second advancement path 34, the direction of the third unwinding path U3 changes when the support structure 33 moves by one step.

[0210] Along the unwinding direction U1 of the first length 27 and the unwinding direction U3 of the first length 28 there is provided a respective material introduction group 53, 54 (indicated in figure 1 ) which is configured to insert a respective free end of the length 27, 28 of the first and second electrode foil 22, 24 in the first winding mandrel 43. The material introduction group 53 and the material introduction group 54 are configured to hold in position and / or translate the free end of the length for the purpose of inserting it into the first winding mandrel 43.

[0211] The first strip-shaped separator 21 extends along a first separator unwinding path S1 . The first separator unwinding path S1 extends from the third unwinding roller 3 to the first winding mandrel 43 arranged at the winding position C1. The first strip-shaped separator 21 is transferred from the third unwinding roller 3 directly to the first winding mandrel 43.

[0212] The third strip-shaped separator 25 extends along a third separator unwinding path S3. The third separator unwinding path S3 extends from the third unwinding roller 3 to the first winding mandrel 43, at the winding position C1 . The third stripshaped separator 25 is transferred from the third unwinding roller 3 directly to the first winding mandrel 43. The third strip-shaped separator 25 is placed on the outer surface of the assembly.

[0213] The winding of the first strip-shaped separator 21 , the first length 27 of the first electrode foil 22, the first length 28 of the second electrode foil 24 and of the third strip-shaped separator 25 on the first winding mandrel 43 takes place simultaneously. The simultaneous winding of the strip-shaped elements on the first winding mandrel 43 is to be understood as without the surpluses in the length of a strip-shaped element with respect to the other strip-shaped elements of the winding required by the production specifications.

[0214] Figure 7 illustrates in more detail the first forming station 41. The first winding mandrel 43 is movable along a first forming path 44 which comprises the first winding position C1 at which the first winding mandrel 43 is configured to receive the strip-shaped elements and make a jelly-roll type winding, as described above. Once the winding of the strip-shaped elements on the first winding mandrel 43 has been completed at the position C1 , the first winding mandrel proceeds along the first forming path 44 to a first cutting position C2, illustrated in figure 8.

[0215] At the first cutting position C2, the first and third strip-shaped separator 21 and 25 are cut by a respective third cutting device 60. For example, the third cutting device 60 comprises a knife 65 which cuts off along its cutting stroke 66 simultaneously the first and the third strip-shaped separator 21 , 25.

[0216] During the movement of the first winding mandrel 41 from the first winding position C1 to the first cutting position C2, the first and third strip-shaped separator 21 , 25 modify the direction of the unwinding paths S1 , S3 and in general the extension of the respective advancement paths. In the cutting position C2 the first winding mandrel 43 comprises a winding 73.

[0217] In order to accompany the relative unwinding of the strip-shaped separators 21 , 25 from the respective separator reel to the first winding mandrel 43, the apparatus 10 comprises a first buffer device 61 for controlling the unwinding of the first strip-shaped separator 21 arranged along the first separator path S1 and a second buffer device 62 for controlling the unwinding of the third strip-shaped separator 25 along the third advancement path S3. The first and second buffer device 61 and 62, known per se, partially or entirely retain and release an excess length of the respective strip-shaped separator so as to adapt the length of the advancement path between the respective unwinding roller and the first winding mandrel 43.

[0218] Subsequently to the cutting of the first and third strip-shaped separator 21 and 25, the first winding mandrel 43 moves from the cutting position C2 to a finishing position C3 along the first forming path 44 (step not illustrated in the figures).

[0219] At the finishing position C3 an assembly or winding 73 of the jelly-roll type is completed. In particular, at the finishing position C3, a patch of adhesive tape (not indicated) is applied on an end portion of the second strip-shaped separator 25 wound externally on the first mandrel 43. For this purpose and in manners known per se, there is provided an adhesive tape feeder 66a which comprises a reel of adhesive tape 68a and a blade 67a configured to cut off a patch of adhesive tape. In particular, the patch of adhesive tape is partially superimposed on the free end of the second strip-shaped separator 25 so as to close the winding and make the assembly more stable during its transfer to the successive processing stations.

[0220] The assembly 73 thus formed proceeds along the third advancement path 45 from the completion position C2 to an unloading position C3 and transferred to successive processing stations, schematically indicated with an arrow 71 (figure 8).

[0221] In the example illustrated in figures 1 , 7-8, the first forming station 41 comprises three winding mandrels, the first winding mandrel 43 described above, a winding mandrel 43a and a winding mandrel 43b.

[0222] In figure 7, the first winding mandrel 43 winds the strip-shaped elements to form a winding 73 and is arranged in the winding position C1. The winding mandrel 43a, provided with the winding, is arranged at the finishing position C3 for closing the winding by means of a patch of adhesive tape (not indicated) by means of the adhesive tape feeder 66a. The winding mandrel 43b arranged at the unloading position C4 is empty. In the successive step illustrated in figure 8, the first winding mandrel 43 has moved into the cutting position, the winding mandrel 43a is in the unloading position C4 and the winding mandrel 43b is in the position C1. In the position C1 , the winding mandrel 43b is ready to receive the lengths of the first and second electrode and the strip-shaped separators to form a new winding. With reference to figures 1 , 9 and 10, the second winding mandrel 45 is mounted on the second conveyor 42 which comprises a fourth support structure 48 configured to rotate around its own transfer axis T4 along the second forming path 46. In particular, the second winding mandrel 44 is mounted on the fourth support structure 48. The rotation of the fourth support structure 48 along the second forming path 46 is driven by an electric motor (not shown). The fourth support structure 48 is in particular a horizontal conveyor, for example a transfer wheel.

[0223] The winding axis V4 (figure 6b) of the second winding mandrel 45 is motorized to impart the rotation and make a winding.

[0224] Figure 9 illustrates in more detail the second forming station 42. The second winding mandrel 45 is movable along a second forming path 46 which comprises the second winding position D1 at which the second winding mandrel 45 is configured to receive the strip-shaped elements and make a winding of the jellyroll type, as described above.

[0225] During winding on the second winding mandrel 45, the second length 27' of the first electrode foil 22 is unwound along a second unwinding path U2 which extends from the second accumulation device 35b to the second winding mandrel 45. Since the unwinding of the second length 27' of the first electrode foil 21 is carried out at two different positions of the first advancement path 32, the direction of the first unwinding path U2 changes when the fourth support structure 48 moves by one step.

[0226] Still during winding on the second winding mandrel 45, the second length 28' of the second electrode foil 24 is unwound along a fourth unwinding path U4 which extends from the second accumulation device 36b of the second accumulation devices 36 to the second unwinding mandrel 45. Since the unwinding of the second length 28' of the second electrode foil is carried out at two different positions of the second advancement path 34, the direction of the fourth unwinding path U4 changes when the support structure 33 moves by one step. Along the unwinding direction U2 of the second length 27' and the unwinding direction U4 of the first length 28' there is provided a respective material introduction group 55, 56 (indicated in figure 1 ) which is configured to insert a respective free end of the length 27', 28' of the first and second electrode foil 22, 24 in the second winding mandrel 45. The material introduction group 55 and the material introduction group 56 are configured to hold in position and / or translate the free end of the length for the purpose of inserting it into the second winding mandrel 45.

[0227] The second strip-shaped separator 23 extends along a second separator unwinding path S2. The second separator unwinding path S2 extends from the fourth unwinding roller 4 to the second winding mandrel 45 arranged at the winding position D1 . The second strip-shaped separator 23 is transferred from the fourth unwinding roller 4 directly to the second winding mandrel 45. The fourth strip-shaped separator 26 extends along a fourth separator unwinding path S4. The fourth separator unwinding path S4 extends from the sixth unwinding roller 6 to the second winding mandrel 45 arranged at the second winding position D1 . The fourth strip-shaped separator 26 is transferred from the sixth unwinding roller 6 directly to the second winding mandrel 45. The fourth strip-shaped separator 26 is placed on the outer surface of the assembly.

[0228] The winding of the second strip-shaped separator 23, the second length 27' of the first electrode foil 22, the second length 28' of the second electrode foil 24 and the fourth strip-shaped separator 26 on the second winding mandrel 45 takes place simultaneously. The simultaneous winding of the strip-shaped elements on the second winding mandrel 45 is to be understood as excluding any surpluses in the length of a strip-shaped element with respect to the other strip-shaped elements of the winding are required by the production specifications.

[0229] Once the winding of the strip-shaped elements on the second winding mandrel 45 has been completed at the position D1 , the second winding mandrel 45 proceeds along the second forming path 46 to a second cutting position D2 illustrated in figure 10.

[0230] At the second cutting position D2, the second and fourth strip-shaped separator 23 and 26 are cut by a respective fourth cutting device 69. For example, the fourth cutting device 69 comprises a knife 67 which cuts off along its cutting stroke 68 simultaneously the second and the fourth strip-shaped separator 23, 26.

[0231] During the movement of the second winding mandrel 41 from the second winding position D1 to the second cutting position D2, the second and fourth strip-shaped separator 23, 26 modify the direction of the unwinding paths S2, S4 and in general the extension of the respective advancement paths. In the second cutting position D2 the first winding mandrel 43 comprises a winding 74.

[0232] In order to accompany the relative unwinding of the strip-shaped separators 23, 26 from the respective separator reel to the second winding mandrel 45, the apparatus 10 comprises a third buffer device 63 for controlling the unwinding of the second strip-shaped separator 23 arranged along the second separator path S2 and a fourth buffer device 64 for controlling the unwinding of the fourth stripshaped separator 26 along the fourth advancement path S4. The third and fourth buffer device 63 and 64, known per se, partially or entirely retain and release an excess length of the respective strip-shaped separator so as to adapt the length of the advancement path between the respective unwinding roller and the second winding mandrel 45.

[0233] Subsequently to the cutting of the second and fourth strip-shaped separator 23 and 26, the second winding mandrel 45 moves from the cutting position D2 to a second finishing position D3 along the second forming path 46 (step not illustrated in the figures).

[0234] At the finishing position D3 an assembly or winding 74 of the jelly-roll type is completed. In particular, at the second finishing position D3, a patch of adhesive tape (not indicated) is applied on an end portion of the fourth strip-shaped separator 26 wound externally on the second mandrel 45. For this purpose and in manners known per se, there is provided a second adhesive tape feeder 66b which comprises a reel of adhesive tape 68b and a blade 67b configured to cut off the patch of adhesive tape. In particular, the patch of adhesive tape is partially superimposed on the free end of the fourth strip-shaped separator 26 so as to close the winding and make the assembly more stable during its transfer to successive processing stations.

[0235] The assembly 74 thus formed proceeds along the second forming path 46 from the second completion position D2 to a second unloading position D3 and transferred to successive processing stations, schematically indicated with an arrow 72 (step not illustrated in the figures).

[0236] In the example illustrated in figures 1 , 9-10, the second forming station 42 comprises three winding mandrels, the second winding mandrel 45 described above and further winding mandrels 45a and 45b.

[0237] In figure 9, the second winding mandrel 45 winds the strip-shaped elements to form a winding 74 and is arranged in the second winding position D1 . The winding mandrel 45a, provided with the winding 74, is arranged at the finishing position D2 for closing the winding by means of a patch of adhesive tape (not indicated) by means of the adhesive tape feeder 66b. The winding mandrel 45b arranged at the second unloading position D4 is empty. In the successive step illustrated in figure 10, the second winding mandrel 45 has moved into the cutting position, the winding mandrel 45a is in the second unloading position D4 and the winding mandrel 45b is in the second winding position D1 .

[0238] In the position D1 , the second winding mandrel 45b is ready to receive the lengths of the first and second electrode and the strip-shaped separators to form a new winding.

[0239] The person skilled in the art will recognize that it is possible to combine the various characteristics of the embodiments described above to obtain further embodiments, all falling within the scope of the present invention as defined by the subsequent claims.

Claims

CLAIMS1 . Method for making assemblies of electrode foils and one or more separators wound together for the production of electrochemical cells, the method comprising:- unwinding from a first electrode reel (11 ) a first electrode foil (22) and winding at least a first and a second length (27) of the first electrode foil (22) on a respective first accumulation device (35a) and a second accumulation device (35b) of a plurality of first accumulation devices (35) arranged in sequence and at a distance from each other along a first advancement path (32), wherein each accumulation device of the plurality of first accumulation devices (35) is rotatable around its own rotation axis (V1 ) and is movable along the first advancement path (32);- unwinding from a second electrode reel (12) a second electrode foil (24) and winding at least a first and a second length (28) of the second electrode foil (24) on a respective first accumulation device (36a) and a second accumulation device (36b) of a plurality of second accumulation devices (36) arranged in sequence and at a distance from each other along a second advancement path (34), wherein each accumulation device (36) of the plurality of second accumulation devices is rotatable around its own rotation axis (V2) and is movable along a second advancement path (34);- subsequently to winding at least a first and a second length (27) of the first electrode foil (22) and to winding at least a first and a second length (28) of the second electrode foil (24), unwinding the first length (27) of the first electrode foil (22) from the first accumulation device (35a) of the plurality of first accumulation devices (35), the first length (28) of the second electrode foil (24) from the first accumulation device (36a) of the plurality of second accumulation devices (36), and unwinding a first strip-shaped separator (21 ) from a first separator reel (13) of a first strip-shaped separator (21 ), and winding the first length (27) of the first electrode foil (22), the first strip-shaped separator (21 ) and the first length (28) of the second electrode foil (24) on a first winding mandrel (43) arranged downstream with respect to the plurality of first accumulation devices (35) and to the plurality of second accumulation devices (36), and unwinding the second length (27) of the first electrode foil (22) from the second accumulation device (35b) of the first plurality of accumulation devices (35), the second length (28) of the second electrode foil (24) from the second accumulation device (36b) of the second plurality of accumulationdevices (36) and a second strip-shaped separator (23) from a second separator reel (14) and winding the second length (27) of the first electrode foil (22), the second strip-shaped separator (23) and the second length (28) of the second electrode foil (24) on a second winding mandrel (45) arranged downstream with respect to the plurality of first accumulation devices (35) and to the plurality of second accumulation devices (36).

2. Method according to claim 1 , wherein unwinding the first length (27) of the first electrode foil (22), the first strip-shaped separator (21 ) and the first length (28) of the second electrode foil (24) comprises simultaneously unwinding the first length (27) of the first electrode foil (22), the first strip-shaped separator (21 ) and the first length of the second electrode foil and winding on the first winding mandrel (43) is simultaneous with the unwinding of the first length of the first electrode foil (22), the first strip-shaped separator (21 ) and the first length (28) of the second electrode foil (24), and unwinding the second length (27) of the first electrode foil (22), the second stripshaped separator (23) and the second length (28) of the second electrode foil (24) comprises simultaneously unwinding said second length (27) of the first electrode foil, second strip-shaped separator (23) and second length (28) of the second electrode foil (24) and winding on the second winding mandrel (45) is simultaneous with the unwinding of the second length (27) of the first electrode foil (22), the second strip-shaped separator (23) and the second length (28) of the second electrode foil (24).

3. Method according to claim 1 or 2, wherein the first strip-shaped separator(21 ) is wound from the first separator reel (13) to be directly wound to the first winding mandrel (43) and the second strip-shaped separator (23) is wound from the second separator reel (14) to be directly wound to the second winding mandrel (45).

4. Method according to one of the preceding claims, which comprises, subsequently to winding the first and second lengths (27) of the first electrode foil(22) on a respective first and second accumulation device (35a, 35b) of the plurality of first accumulation devices (35) and prior to unwinding the first and second length from said first and second accumulation devices (35a, 35b), cutting the first electrode foil (27) from the first electrode reel (11 ), upstream of the respective first and second accumulation devices of the plurality of first accumulation devices (35), andsubsequently to winding the first and second length (28) of the second electrode foil (24) on a respective first and second accumulation device (36a, 36b) of the plurality of second accumulation devices (36) and prior to unwinding the first and second length from said first and second accumulation devices (36a, 36b) of the plurality of second accumulation devices (36), cutting the second electrode foil (28) from the second electrode reel (12), upstream of the respective first and second accumulation device of the plurality of second accumulation devices (36).

5. Method according to one of the preceding claims, which comprises advancing and stopping the first accumulation devices (35) of the plurality of first accumulation devices intermittently along the first advancement path (32), and advancing and stopping the second accumulation devices (36) of the plurality of second accumulation devices intermittently along the second advancement path (34).

6. Method according to claim 5, wherein- advancing the first accumulation devices (35) of the plurality of first accumulation devices comprises moving the first accumulation devices by one step between adjacent proximal positions of a first plurality of positions along the first advancement path (32) for a first movement time interval (tMi) and stopping the advancement of the first accumulation devices (35) subsequently to each advancement by one step for a first stop time interval (tsi), and advancing the second accumulation devices (36) of the plurality of second accumulation devices comprises moving each second accumulation device of the second plurality of accumulation devices by one step between adjacent proximal positions of a second plurality of positions of the second advancement path (34) for a second movement time interval (tM2) and stopping the advancement of the second accumulation devices (36) subsequently to each advancement by one step for a second stop time interval (ts2).

7. Method according to any of the preceding claims, wherein the first accumulation devices (35) of the plurality of first accumulation devices are rotatably mounted around the respective rotation axis (V1 ) on a first support structure (31 ) rotatable around a first transfer axis (T1 ), the method comprising advancing the first support structure (31 ) around the first transfer axis (T1 ) so as to define the first advancement path (32) along which the first accumulationdevices (35) are arranged, and the second accumulation devices (36) of the plurality of second accumulation devices are rotatably mounted around the respective own rotation axis (V2) on a second support structure (33) rotatable around a second transfer axis (T2), the method comprising advancing the second support structure (33) around the second transfer axis (T2) so as to define the second advancement path (34) along which the second accumulation devices (36) are arranged.

8. Method according to claim 7, wherein the first plurality of positions of the first advancement path (32) comprises a first loading position (A1 ), at which each accumulation device (35) of the plurality of first accumulation devices is positioned to receive the first electrode foil (22) from the first electrode reel (11 ) and to wind a length (27) of the first electrode foil thereon, and wherein unwinding the first length (27) of the first electrode foil (22) from the first accumulation device (35a) and the second length from the second accumulation device (35b) of the plurality of first accumulation devices is at a plurality of first unloading positions (A2-A4) of the first plurality of positions, the plurality of first unloading positions (A2-A4) being arranged downstream of the first loading position (A1 ) with respect to the first advancement path (32), and wherein the second plurality of positions of the second advancement path (34) comprises a second loading position (B1 ), at which each second accumulation device (36) of the plurality of second accumulation devices is positioned to receive the second electrode foil (24) from the second electrode reel (12) and to wind a length (28) of the second electrode foil (24) thereon, and to unwind the first length (28) of the second electrode foil (24) from the first accumulation device (36a) and the second length of the second electrode foil from the second accumulation device (36b) of the plurality of second accumulation devices (36) is at a plurality of second unloading positions (B2-B4) of the second plurality of positions, the plurality of second unloading positions (B2-B4) being arranged downstream of the second loading position (B1 ) with respect to the second advancement path (34).

9. Method according to claim 8, which comprises partially unwinding the first length (27) of the first electrode foil (22) from the first accumulation device (35a) of the plurality of first accumulation devices at a first unloading position (A2) of the first plurality of unloading positions (A2-A4) and simultaneously partially unwinding the second length (27) of the first electrode foil(22) from the second accumulation device (35b) of the first plurality of accumulation devices at a second unloading position (A2) of the first plurality of unloading positions, wherein partially unwinding the first and second length of the first electrode foil (22) is carried out simultaneously with the winding of a length of the first electrode foil at the first loading position (A1 ), advancing the plurality of first accumulation devices by one step so as to move the first accumulation device from the first unloading position (A2) to the second unloading position (A3) and the second accumulation device from the second unloading position (A3) to a third unloading position (A4) while continuing to partially unwind the first and second length of the first electrode foil, and simultaneously with the winding of a successive length of first electrode foil (22) positioned at the first loading position (A1 ), continuing to unwind the first length of first electrode foil (22) from the first accumulation device (35a) of the first plurality of accumulation devices at the second unloading position (A3) of the first plurality of unloading positions (A2-A4) and continuing to unwind the second length of first electrode foil (22) from the second accumulation device (35b) of the first plurality of accumulation devices (35) at the third unloading position (A4) of the first plurality of unloading positions so as to complete the unwinding of the first length and second length of first electrode foil (22).

10. Method according to claim 8 or 9, which comprises partially unwinding the first length (28) of the second electrode foil (24) from the first accumulation device (36a) of the plurality of second accumulation devices (36) at a fourth unloading position (B2) of the second plurality of unloading positions (B2-B4) and simultaneously partially unwinding the second length (28) of the second electrode foil (24) from the second accumulation device (36b) of the second plurality of accumulation devices (36) at a fifth unloading position (B3) of the second plurality of unloading positions (B2-B4), wherein partially unwinding the first and second length of the second electrode foil (24) is carried out simultaneously with the winding of a length of the second electrode foil (24) at the second loading position (B1 ), advancing the plurality of second accumulation devices (36) by one step so as to move the first accumulation device (36a) of the plurality of second accumulation devices from the fourth unloading position (B2) to the fifth unloading position (B3) and the second accumulation device (36b) of the plurality of second accumulation devices from the fifth unloading position (B3) to a sixth unloading position (B4) while continuing to partially unwind the first and second length (28) of the second electrode foil (24), andsimultaneously with the winding of a successive length of second electrode foil (24) positioned at the second loading position (B1 ), continuing to unwind the first length of the second electrode foil (24) from the first accumulation device (36a) of the plurality of second accumulation devices at the fourth unloading position (B3) of the first plurality of unloading positions (B2-B4) and continuing to unwind the second length of the second electrode foil (24) from the second accumulation device (36b) of the second plurality of accumulation devices (36) at the sixth unloading position (B4) of the second plurality of unloading positions so as to complete the unwinding of the first length and of the second length of second electrode foil (24).

11. Method according to one of the preceding claims, which comprises unwinding a third strip-shaped separator (25) from a third separator reel (5) simultaneously with the unwinding of the first length of the first electrode foil (22), of the first length of the second electrode foil (24) and of the first strip-shaped separator (21 ), and unwinding a fourth strip-shaped separator (26) from a fourth separator reel (6) simultaneously with the winding of the second length of the first electrode foil (22), of the second length of the second electrode foil (24) and of the second stripshaped separator (23).

12. Method according to claim 11 , wherein the third strip-shaped separator (25) is unwound from the third separator reel (15) to be directly wound to the first winding mandrel (43) simultaneously with the winding of the first length of the first electrode foil (22), the first length of the second electrode foil (24) and the first strip-shaped separator (21 ), and the fourth strip-shaped separator (26) is wound from the fourth separator reel (16) to be directly wound to the second winding mandrel (45) simultaneously with the winding of the second length of the first electrode foil (22), the second length of the second electrode foil (24) and the second strip-shaped separator (23).

13. Winding apparatus (10) for making assemblies of electrode foils and one or more separators wound together for the production of electrochemical cells, the apparatus comprising:- a first unwinding roller (1 ) configured to house a first electrode reel (11 ) of a first electrode foil (22);- a plurality of first accumulation devices (35) arranged in sequence, at a distance from each other along a first advancement path (32) and movable along the firstadvancement path, wherein each first accumulation device is rotatable around its own rotation axis (V1 ) and is configured to receive and to wind a length (27) of the first electrode foil from the first electrode reel (11 );- a second unwinding roller (2) configured to house a second electrode reel (12) of a second electrode foil (24);- a plurality of second accumulation devices (36) arranged in sequence, at a distance from each other along a second advancement path (34) and movable along the second advancement path, wherein each accumulation device of the plurality of second accumulation devices is rotatable around its own rotation axis (V2) and is configured to receive and to wind a length (28) of the second electrode foil (24) from the second electrode reel (12);- a third unwinding roller (3) configured to house a first separator reel (13) of a first strip-shaped separator (21 );- a fourth unwinding roller (4) configured to house a second separator reel (14) of a second strip-shaped separator (23);- a first winding mandrel (43) rotatable around its own winding axis (V3) and arranged downstream of the plurality of first accumulation devices (35) and of the plurality of second accumulation devices (36), wherein the first winding mandrel (43) is configured to receive a first length (27) of the first electrode foil (22) from a first accumulation device (35a) of the plurality of first accumulation devices (35), the first strip-shaped separator (21 ) from the third unwinding roller (3) and a first length of the second electrode foil (24) from a first accumulation device (36a) of the second plurality of accumulation devices (36), and- a second winding mandrel (45) rotatable around its own winding axis (V4) and arranged downstream of the plurality of first accumulation devices (35) and of the plurality of second accumulation devices (36), wherein the second winding mandrel (45) is configured to receive a second length (27) of the first electrode foil (22) from a second accumulation device (35b) of the plurality of first accumulation devices, the second strip-shaped separator (23) from the fourth unwinding roller (14) and a second length of the second electrode foil (24) from a second accumulation device (36b) of the plurality of second accumulation devices (36).

14. Apparatus according to claim 13, which comprises a first support structure (31 ) on which the accumulation devices of the plurality of first accumulation devices (35) are mounted rotatably about the respective rotation axis (V1 ), the first support structure (31 ) being configured to rotate around its own transfer axis (T1 ), the rotation of the first support structure (31 ) definingthe first advancement path (32), and a second support structure (33) on which the accumulation devices of the plurality of second accumulation devices (36) are mounted rotatably about the respective rotation axis, the second support structure (33) being configured to rotate around its own transfer axis (T2), the rotation of the second support structure (33) defining the second advancement path (34).

15. Apparatus according to claim 14, wherein the plurality of first accumulation devices (35) are configured to move between successive positions of a first plurality of positions which comprises a first loading position (A1 ) at which a respective accumulation device of the plurality of first accumulation devices (35) is configured to receive a length of the first electrode foil (22) from the first electrode reel (11 ) and a plurality of first unloading positions (A2-A4) at which a respective accumulation device of the plurality of first accumulation devices (35) is configured to unwind the first and second length of the first electrode foil, and the plurality of second accumulation devices (36) are configured to move between successive positions of a first plurality of positions which comprises a second loading position (B1 ) at which a respective accumulation device of the plurality of second accumulation devices (36) is configured to receive a length of the second electrode foil (24) from the second electrode reel (12) and a plurality of second unloading positions (B2-B4) at which a respective accumulation device of the plurality of second accumulation devices (36) is configured to unwind the first and second length of the second electrode foil (24).

16. Apparatus according to one of claims from 13 to 15, wherein between the third unwinding roller (3) and the first winding mandrel (43) there is defined a first separator unwinding path (S1 ) which transfers the first strip-shaped separator (21 ) directly to the first winding mandrel (43), and between the fourth unwinding roller (4) and the second winding mandrel (45) there is defined a second separator unwinding path (S2) which transfers the second strip-shaped separator (23) directly to the second winding mandrel (45).

17. Apparatus according to one of claims from 13 to 16, wherein the first unwinding roller (1 ) and the second unwinding roller (2) are arranged upstream of the first plurality of accumulation devices (35) and of the second plurality of accumulation devices (36) with respect to a respective unwinding direction of the first and second electrode reel (1 , 2), the apparatus comprising a first cutting device (52a) arranged upstream of the accumulation devices of thefirst plurality of accumulation devices (35) and configured to cut the first electrode foil (22) from the first electrode reel (11 ) and make a length (27) of the first electrode foil (22) wound on a respective accumulation device of the plurality of first accumulation devices (35), and a second cutting device (52b) arranged upstream of the accumulation devices of the second plurality of accumulation devices (36) and configured to cut the second electrode foil (24) from the second electrode reel (12) and make a length (28) of the second electrode foil (24) wound on a respective accumulation device of the plurality of second accumulation devices (36).

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