Machine and method for making electrical energy storage devices

Abstract

The invention concerns a machine (10) for making electrical energy storage devices and a corresponding method. The machine (10) comprises feeding means (21, 22, 23, 24) for feeding a cathode film (25), an anode film (27) and at least one separator film (26, 28), a plurality of transit rollers (31, 32, 33, 34) each able to receive a respective one of the films (25, 26, 27, 28), a plurality of cutting devices(35, 36, 37, 38) each able to carry out the cutting of a respective one of the films (25, 26, 27, 28), and a rotating member (50) provided with at least two winding cores (53) and a plurality of transfer rollers (511, 512, 513, 514) configured to temporarily wind a respective segment of the films (25, 26, 27, 28) and transfer them to the winding core (53).

Description

[0001] “MACHINE AND METHOD FOR MAKING ELECTRICAL ENERGY

[0002] STORAGE DEVICES”

[0003] FIELD OF THE INVENTION

[0004] The present invention concerns a machine and a method for making electrical energy storage devices.

[0005] The electrical energy storage devices makeable using the method and the winding machine according to the present invention can be batteries with a cylindrical or substantially cylindrical shape, commonly known as jelly rolls, or with an oval shape, obtained by winding about a flat pin.

[0006] BACKGROUND OF THE INVENTION

[0007] Batteries with a cylindrical shape and containing, as a single electrochemical cell, a strip wound about a winding core are known. The strip consists of a cathode film and an anode film, between which a separator film is inserted to prevent any contact between the cathode and anode. Usually, the strip also comprises another separator film to cover the cathode.

[0008] To make these batteries, there are so-called winding machines in which the strip is made starting from four reels, each formed by a respective anode film, cathode film and films of each of the two separators. A multilayer is usually created, formed by two separator films with the cathode film interposed. This multilayer is fed to the winding core about which it is wound. The anode film is inserted during the winding.

[0009] In general, in known machines, the winding core and the reels from which the films are unwound are all motorized. A critical aspect to manage is the synchronization between the feed of the films, which occurs at a constant speed, and the speed at which the strip is wound about the winding core, which occurs at variable speed. In particular, it is necessary to manage the sudden movement of the head, the cutting of the separators and their insertion in the winding core. The cutting of the separator films and the insertion of the electrode films take place in different steps and in motion with pliers that operate the insertion of the material.

[0010] One problem found in different machine models is poor productivity. To resolve this problem, a machine is known from WO2023275909 comprising a unit for unwinding the films from their respective reels, and a rotating member carrying a plurality of winding cores to wind individual segments of film about each one of them, and thus create a respective jelly roll. On the rotating member, which is driven with continuous motion, there are also mounted four accumulation rollers for each winding core, each accumulation roller being configured to receive and provisionally wind segments of film of a predetermined size.

[0011] The films pass on respective transit rollers, placed externally and peripherally to the rotating member, before arriving at the accumulation rollers. The machine described in WO2023275909 further comprises blades as cutting means, each attached on a respective horizontally pivoting lever and able to cooperate with the transit rollers to cut to size the films that have been wound about the accumulation rollers, so that the segments wound about the accumulation rollers have predefined lengths. The cutting is carried out on the transit rollers upstream of the accumulation rollers.

[0012] The cutting is carried out in a dwell step, therefore it is necessary to interrupt the unwinding of the film about the transit roller during the cutting. For this purpose, the machine comprises a buffer device arranged between the unwinding unit and the transit rollers, and containing a buffer member, or buffer, for each of the films.

[0013] This buffer device allows to accommodate the portions of film that are unwound from the reels during the cutting step.

[0014] Furthermore, once the winding of a segment of film about an accumulation roller has ended, at the end of the cutting step, the accumulation roller about which the segment of film has been wound is moved away from the transit roller, on which the film was cut, and another accumulation roller comes into contact with the transit roller to resume the winding of another segment of film, partly recovering the film that has been accommodated by the buffer device, and so on.

[0015] A disadvantage of this known machine is that it is necessary to have a buffer device sized so as to accommodate the portions of film that are unwound between the cutting step and the restart of the winding about a new accumulation roller. These continuous restarts in winding the films about the accumulation rollers can also cause film misalignments, mainly due to loss of optimal tension.

[0016] Another disadvantage of the known machine is that it has a very complicated structure and is quite bulky. There is therefore the need to perfect the known machine and method for making electrical energy storage devices so as to overcome at least one of the disadvantages of the state of the art.

[0017] To do this, it is necessary to resolve the technical problem of maintaining film alignment and reducing overall dimensions.

[0018] In particular, one purpose of the present invention is to provide a machine and perfect a method for making electrical energy storage devices capable of cutting the films without any interruption whatsoever in their feed.

[0019] Another purpose of the present invention is to provide a machine and perfect a method in which the film unwound from the respective reels is managed with minimal accumulations upstream of the winding rollers.

[0020] Another purpose of the present invention is to provide a machine for making electrical energy storage devices that has a simple structure.

[0021] The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

[0022] SUMMARY OF THE INVENTION

[0023] The present invention is set forth and characterized in the independent claims. The dependent claims describe other characteristics of the present invention or variants to the main inventive idea.

[0024] In accordance with the above purposes and to resolve the technical problem described above in a new and original way, also achieving considerable advantages compared to the state of the prior art, a machine according to the present invention for making electrical energy storage devices comprises feeding means for feeding with continuous motion anode film, a cathode film and at least one separator film to be fed between the anode film and the cathode film; a plurality of transit rollers, the latter being able to each receive a respective one of the above mentioned films coming from the feeding means; a plurality of cutting devices each able to cut a respective one of the films on a respective transit roller; a rotating member placed downstream of the plurality of transit rollers and provided with at least two winding cores and a plurality of transfer rollers configured to temporarily wind a respective segment of the above mentioned films and to each transfer a respective film towards a respective winding core. In accordance with one aspect of the present invention, the machine comprises a buffer unit between the plurality of transit rollers and the plurality of transfer rollers. The buffer unit comprises a respective pair of buffer rollers for each transit roller, each roller of the pair of buffer rollers being configured to alternately cooperate with a respective transit roller in order to wind a segment of a respective one of the films, and to feed the segment to a respective roller of the plurality of transfer rollers.

[0025] Advantageously, each cutting device comprises a cutting roller provided with a longitudinal blade. More advantageously, the blade is retractable between a position internal to the cutting roller and a position extended from the cutting roller. The cutting device is rotated in a manner synchronized with the corresponding transit roller.

[0026] Doing so achieves at least the advantage of being able to cut the films without stopping their feed. Moreover, the presence of two buffer rollers for each film allows to transfer a portion of film towards the rotating member and to receive a subsequent portion of film from the transit roller in shadow time.

[0027] This maintains a continuous feed of the film until the rotating member, which is rotated with a stepwise motion.

[0028] Always in accordance with the above purposes and to resolve the technical problem described above in a new and original way, also achieving considerable advantages compared to the state of the prior art, a method according to the present invention for making electrical energy storage devices comprises the steps of continuously feeding an anode film, a cathode film, and at least one separator film between the anode film and the cathode film; receiving each of the films on a respective transit roller; cutting, by means of cutting devices, each of the films of a predefined length on the respective transit roller; temporarily winding a respective segment of the films about a plurality of transfer rollers and transferring them to a respective winding core mounted on a rotating member located downstream of the plurality of transit rollers, rotatably driving the winding core so as to wind the segments of film taken from the transfer rollers to form a respective wound element.

[0029] According to one aspect of the invention, the method further comprises, before temporarily winding a respective segment of the films about a plurality of transfer rollers, a step of feeding the films to a buffer unit located between the plurality of transit rollers and the plurality of transfer rollers, the buffer unit comprising a respective pair of buffer rollers for each transit roller, wherein each roller of the pair of buffer rollers cooperates alternately with a respective transit roller to wind a segment of a respective one of the cathode film, anode film and of the at least one separator film, and subsequently feed the segment to a respective roller of the plurality of transfer rollers.

[0030] Advantageously, the method is performed using the machine disclosed above. DESCRIPTION OF THE DRAWINGS

[0031] These and other aspects, characteristics and advantages of the present invention will become apparent from the following description of some embodiments, given as a non-restrictive example with reference to the attached drawings wherein:

[0032] - fig. 1 is a schematic lateral view of a machine for making electrical energy storage devices, according to a first embodiment of the present invention;

[0033] - fig. 2 is an enlarged view of a first zone of the machine of fig. 1;

[0034] - figs. 3a-3f are enlarged views of a detail of the first zone of fig. 2, in various successive operating steps.

[0035] We must clarify that the phraseology and terminology used in the present description, as well as the figures in the attached drawings also in relation as to how described, have the sole function of better illustrating and explaining the present invention, their purpose being to provide a non-limiting example of the invention itself, since the scope of protection is defined by the claims.

[0036] To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It is understood that elements and characteristics of one embodiment can be conveniently combined or incorporated into other embodiments without further clarifications.

[0037] DESCRIPTION OF AN EMBODIMENT OF THE PRESENT INVENTION

[0038] With reference to fig. 1, a machine 10 for making electrical energy storage devices according to the present invention comprises a feeding station 20 for feeding a plurality of films and a winding station 30 for winding the same films in order to form a wound element 100, intended to be an electrochemical cell of an electrical energy storage device.

[0039] The feeding station 20 is provided with feeding means 21, 22, 23, 24 for feeding respective films intended to constitute the wound element. In particular, the films comprise a cathode film 25, an anode film 27 and two separator films 26, 28, unwound from respective reels 25A, 25B, 26A, 26B, 27A, 27B, 28A, 28B. At each feeding mean 21, 22, 23, 24 from which a corresponding film 25, 26, 27, 28 is unwound, there are preferably provided two reels 25 A, 25B, 26A, 26B, 27A, 27B, 28A, 28B, so as not to have to interrupt the feed of a film when the corresponding reel runs out. It is however possible to have only one reel for each film.

[0040] The films 25, 26, 27, 28 are fed through respective tensioning systems 25C, 26C, 27C, 28C and, subsequently, through an unwinding device 29 until the winding station 30 (fig. 1), which comprises a plurality of transit rollers 31, 32, 33,

[0041] 34, in this case four transit rollers 31, 32, 33, 34, each able to receive a corresponding film 25, 26, 27, 28 (figs. 1 and 2).

[0042] Upstream of each transit roller 31, 32, 33, 34 there is an aligner 25D, 26D, 27D, 28D configured to align the films.

[0043] In the winding station 30 there are also provided four cutting devices 35, 36, 37, 38 each configured to cut to size a corresponding film 25, 26, 27, 28 on a corresponding transit roller 31, 32, 33, 34. For this purpose, each cutting device

[0044] 35, 36, 37, 38 is placed proximal to the corresponding transit roller 31, 32, 33, 34.

[0045] In the embodiment shown, each cutting device 35, 36, 37, 38 consists of a cutting roller 350, 360, 370, 380 provided with a longitudinal blade 351, 361, 371, 381, that is, which develops longitudinally relative to the cutting roller 350, 360, 370, 380. Each blade 351, 361, 371, 381 is preferably retractable, that is, it is movable between a rest position, in which the blade 351, 361, 371, 381 is contained inside the corresponding cutting roller 350, 360, 370, 380, and a cutting position, in which the blade 351, 361, 371, 381 is extended radially, or substantially radially, outside the cutting roller 350, 360, 370, 380.

[0046] Each transit roller 31, 32, 33, 34 comprises a respective cavity 310, 320, 330, 340 in which a counter-blade 311 , 321, 331 , 341 is housed, configured to interact with the blade 351, 361, 371, 381 of the corresponding cutting device 35, 36, 37, 38 when it is in the cutting position. More precisely, when the blades 351, 361, 371, 381 are in the cutting position, they enter the respective cavity 310, 320, 330, 340 substantially flush with the counter-blade 311, 321, 331, 341 . We must clarify that these counter-blades 311 , 321, 331, 341 are contained within the volume of their transit roller 31, 32, 33, 34, so as not to interact with the film 25, 26, 27, 28 passing thereon.

[0047] The rotation of the transit rollers 31, 32, 33, 34 and of the cutting rollers 350,

[0048] 360, 370, 380 is synchronized so that the blade 351, 361, 371, 381 penetrates into the cavity 310, 320, 330, 340 of the transit roller 350, 360, 370, 380 going flush with the corresponding counter-blade 311, 321, 331, 341. Preferably, the blade 351, 361, 371, 381 can be retractable, if the cutting roller 350, 360, 370, 380 rotates continuously, to avoid cutting the film 25, 26, 27, 28 with each rotation.

[0049] It can also be provided that the rotation of the cutting roller 350, 360, 370, 380 takes place only in the cutting step but still synchronized, so that the blade 351,

[0050] 361, 371 , 381 is in the cutting position at the transit roller 31 , 32, 33, 34 when the cutting has to be carried out.

[0051] Alternatively, any cutting system that allows to cut the film on the transit roller in continuous can be used.

[0052] Each transit roller 31, 32, 33, 34 also comprises its own retaining means 312, 322, 332, 342 configured to retain, downstream of the cutting, the end of the corresponding film 25, 26, 27, 28 in contact with its external surface. In the example shown, the retaining means 312, 322, 332, 342 are of the suction type, suitably connected to a suction source.

[0053] The winding station 30 also comprises, immediately downstream of the transit rollers 31, 32, 33, 34, a buffer unit 40 provided with a plurality of buffer devices 41, 42, 43, 44, in this example four, namely one buffer device 41, 42, 43, 44 for each of the transit rollers 31, 32, 33, 34.

[0054] Each buffer device 41, 42, 43, 44 is provided with a first buffer roller 411, 421, 431 , 441 and with a second buffer roller 412, 422, 432, 442. Both buffer rollers are movable between a pick-up position in which they are substantially in contact with the respective transit roller 31 , 32, 33, 34 so as to wind the film passing on the transit roller 31, 32, 33, 34, and a transfer position which will be described below.

[0055] Each buffer roller 411, 412, 421, 422, 431, 432, 441, 442 is mounted on a respective arm 413, 414, 423, 424, 433, 434, 443, 444. The arms are pivoted two by two about four axes of rotation Rl, R2, R3, R4, each one being relative to a corresponding buffer device 41, 42, 43, 44. It is thus apparent that each buffer device 41 , 42, 43, 44 comprises two arms 413, 414, 423, 424, 433, 434, 443, 444 pivoted about a same axis of rotation Rl, R2, R3, R4, each arm 413, 414, 423, 424, 433, 434, 443, 444 carrying a buffer roller 411, 412, 421, 422, 431, 432, 441, 442. Obviously, the buffer rollers 411, 412, 421, 422, 431, 432, 441, 442 are mounted rotatable about their central axis on the end of the respective arm 413, 414, 423, 424, 433, 434, 443, 444.

[0056] The above-described configuration causes the buffer rollers 411, 412, 421, 422, 431, 432, 441, 442 to be movable along a trajectory shaped substantially as a circular arc centered on a respective axis of rotation Rl, R2, R3, R4 on which the arms are pivoted.

[0057] Advantageously, each buffer roller 411, 412, 421, 422, 431, 432, 441, 442 is provided with its own retaining member 415, 416, 425, 426, 435, 436, 445, 446 to retain the film on the respective buffer roller 415, 416, 425, 426, 435, 436, 445, 446. In the example shown, the retaining members 415, 416, 425, 426, 435, 436, 445, 446 comprise rollers each associated with a respective buffer roller 411, 412, 421, 422, 431, 432, 441, 442.

[0058] Downstream of the buffer unit 40 there is provided a rotating member 50 provided with transfer units 51 each comprising four transfer rollers 511, 512, 513, 514, so that for each transfer roller 511, 512, 513, 514 there is a respective buffer device 41, 42, 43, 44, and therefore a respective film 25, 26, 27, 28 (figs. 1 and 2). The rotating member 50 is rotated with a stepwise motion.

[0059] In each transfer unit 51, the transfer rollers 511, 512, 513, 514 are substantially arranged along the external edge of the rotating member 50 when they are oriented towards the buffer unit 40.

[0060] The rotating member 50 also comprises a plurality of winding cores 53, configured to wind the films 25, 26, 27, 28 and thus make the wound elements 100 in a known manner.

[0061] Each transfer roller 511, 512, 513, 514 is provided with its own transfer member

[0062] 531, 532, 533, 534 configured to retain a corresponding end of a film 25, 26, 27, 28 and to bring it to the corresponding winding core 53. Each transfer member 531,

[0063] 532, 533, 534 is configured as an arm pivoted on a support 535, 536, 537, 538 which extends radially from its transfer roller 511, 512, 513, 514. Each support 535, 536, 537, 538 is rotatable with respect to the corresponding transfer roller 511, 512, 513, 514 about its longitudinal axis. In the example shown, the rotating member 50 comprises four transfer units 51, and therefore four winding cores 53 angularly distributed around the axis of rotation R5 of the rotating member 50. The buffer unit 40 is placed on one side of the rotating member 50, which rotates clockwise in the example shown. The wound elements 100 are extracted in an extraction position E positioned at the bottom.

[0064] In the extraction position E, an exit station 60 is provided in which a star wheel 61 and a conveying device 62 are arranged, for example of the type indicated in patent application WO2023275909.

[0065] The machine 10 also comprises taping means of the wound element 100 of a known type, for example as disclosed in document WO2023275909.

[0066] The operation of the machine 10 described heretofore, which corresponds to the method according to the present invention, comprises the following steps.

[0067] After arranging the reels 25A, 25B, 26A, 26B, 27A, 27B, 28A, 28B of the films in the respective feeding means 21, 22, 23, 24, their feed to the transit rollers 31, 32, 33, 34 is started, here segments of film are cut which are then fed to the winding cores 53 so as to form the wound elements 100. Before being fed to the winding cores 53, the segments of film are first wound about the buffer rollers 41, 42, 43, 44 of the buffer unit 40 and then transferred onto the transfer rollers of the transfer unit 51.

[0068] Hereafter, for simplicity, the feed of only the cathode film 25 through the corresponding path is described, but the progress is identical for the other three films 26, 27, 28 through the respective paths.

[0069] The cathode film 25 arrives at the transit roller 31 and immediately at the first buffer roller 411 placed in contact with the transit roller 31, so as to be wound about the buffer roller 411.

[0070] Once a predefined size of the film has been wound about the buffer roller 411, its cutting to size by means of the cutting device 35 is commanded. More precisely, the blade 351 (so far in the retracted position inside the roller 350) is driven so as to move it into its position extended from the roller 350. The cutting is thus carried out in cooperation with the counter-blade 311 of the transit roller 31 , as explained above. The retaining means 312 of the transit roller 31 are also driven, so that the next portion of film is not detached therefrom.

[0071] Since the cutting always takes place in the same spot, at the end of the cutting the transit roller can be accelerated to return in step, so that the cutting of the film takes place at the exact length desired.

[0072] Once the cutting has been carried out, the blade 351 is immediately returned into its retracted position inside the roller 350.

[0073] The end tab of the portion of cathode film 25 wound about the first buffer roller 411 is kept in position be means of the retaining member 415 (fig. 3b).

[0074] At this point, the buffer device 41 is driven so that the first buffer roller 411 is approached to the corresponding transfer roller 511 of the rotating member 50, this approach is carried out by rotating the arm 413 that carries the first buffer roller 411 . At the same time, the second buffer roller 412 of the buffer device 41 , which had previously been in contact with another transfer roller and then approached to the transit roller 31 (fig. 3a), is brought into contact with the transit roller 31 (fig. 3b), this displacement, made in two steps (approach (fig. 3a) and then contact (fig. 3b)), is performed by rotating the arm 414 that carries the second buffer roller 412.

[0075] In practice, the transit roller 31 is always contacted alternately by the first 411 and by the second 412 buffer roller, allowing the cathode film 25 to be unwound without any interruptions.

[0076] When the second buffer roller 412 contacts the transit roller 31, the end of the cathode film 25, retained by suction on the transit roller 31 immediately after the cutting, is taken by the second buffer roller 412 by suction (fig. 3c).

[0077] In particular, in the passage of the cathode film 25 from the transit roller 31 to the second buffer roller 412, the suction is interrupted on the transit roller 31 and activated on the second buffer roller 412 to allow the transfer of the free end of the cathode film 25 that has just been cut.

[0078] Once the second buffer roller 412 has started the winding, the transit roller 31 returns in step, as described above.

[0079] Each buffer roller 411, 412 follows its own circular arc trajectory about the axis R1 due to the rotation of the corresponding arm 413, 414.

[0080] When the first buffer roller 411 comes into contact with the corresponding transfer roller 511 (fig. 3c), the segment of cathode film 25 wound about the first buffer roller 41 1 is transferred to the transfer roller 511.

[0081] In particular, the free end of the segment of cathode film 25 wound about the first buffer roller 411 is released from the retaining member 415 and retained by suction by the transfer roller 511 which, by rotating, winds the entire segment of cathode film 25 about itself, which had previously been wound about the first buffer roller 411.

[0082] After having wound the cathode film 25 about the transfer roller 511, the free end of the cathode film 25 is retained by the transfer member 531 (fig. 3d), which will bring it to the winding core 53 when the transfer roller 511 is brought proximal to the winding core 53.

[0083] When the winding of the segment of cathode film 25 about the transfer roller 51 1, as well as the simultaneous winding of the other three films 26, 27, 28 about the respective transfer rollers 512, 513, 514, are completed, the rotating member 50, which has so far been kept stationary, is driven to rotate by an angle such as to bring the next group of transfer rollers 511, 512, 513, 514 (figs. 3e, 3f) at the buffer devices 41, 42, 43, 44. In the example shown here, the rotation is done by a 90° angle.

[0084] In practice, when the four films formed by anode, cathode and two separators have been wound about the respective transfer rollers, these are brought about the winding core 53, so that the respective transfer members supply the end of the respective segment of film to the winding core 53, as disclosed in WO2023275909, incorporated entirely here as reference.

[0085] At the level of the transit rollers 31, 32, 33, 34 and the buffer devices 41, 42, 43, 44, the previously described steps are resumed exchanging the first and second buffer roller 411, 412.

[0086] The drives are made following a pre-established sequence. In particular, it starts with winding the separator films 26, 28 in a first instance and the cathode 25 and anode 27 films in a second instance.

[0087] Once the wound element 100 has been made, it remains on the winding core 53 until the latter reaches the extraction position E (fig. 1).

[0088] Subsequently, an adhesive strip is applied on the wound element 100, which is then extracted from the rotating member 50. Both steps are performed in a known manner, for example as disclosed in document WO2023275909.

Claims

CLAIMS1. Machine (10) for making electrical energy storage devices, said machine comprising feeding means (21, 22, 23, 24) configured to feed in continuous a cathode film (25), an anode film (27) and at least one separator film (26, 28) disposed between said cathode film (25) and said anode film (27), a plurality of transit rollers (31, 32, 33, 34) each configured to receive respectively said cathode film (25), anode film (27) and the at least one separator film (26, 28), a plurality of cutting devices (35, 36, 37, 38) each configured to cut respectively said cathode film (25), anode film (27) and the at least one separator film (26, 28) on a respective transit roller (31, 32, 33, 34), and a rotating member (50) placed downstream of said plurality of transit rollers (31, 32, 33, 34) and provided with at least two winding cores (53), and a plurality of transfer rollers (511, 512, 513, 514) configured to temporarily wind a respective segment of said films (25, 26, 27, 28) and transfer them to said winding core (53), characterized by further comprising a buffer unit (40) placed between said plurality of transit rollers (31, 32, 33, 34) and said plurality of transfer rollers (511, 512, 513, 514), and comprising a respective pair of buffer rollers (41 1 , 412, 421, 422, 431, 432, 441, 442) for each transit roller (31, 32, 33, 34), wherein each roller of the pair of buffer rollers (411, 412, 421, 422, 431, 432, 441, 442) is configured to alternately cooperate with a respective transit roller (31, 32, 33, 34) to wind the respective segment of said cathode film (25), anode film (27) and the at least one separator film (26, 28), and to feed said segment to a respective roller of said plurality of transfer rollers (511, 512, 513, 514).

2. Machine (10) as in claim 1, characterized in that each cutting device (35, 36, 37, 38) comprises a cutting roller (350, 360, 370, 380) provided with a longitudinal blade (351, 361, 371 , 381).

3. Machine (10) as in claim 2, characterized in that said blade (351, 361, 371, 381) is movable between a position internal to said cutting roller (350, 360, 370, 380) and an external position therefrom.

4. Machine (10) as in any one of the preceding claims, characterized in that each transit roller (31, 32, 33, 34) is provided with a respective counter-blade (311, 321, 331, 341) configured to cooperate with a respective cutting device (35, 36, 37, 38) to carry out the cutting of a respective one of said films (25, 26, 27, 28).

5. Machine (10) as in any one of the preceding claims, characterized in that said buffer rollers (411 , 412, 421 , 422, 431 , 432, 441 , 442) of the same pair are movable along respective circular trajectories preferably centered on the same axis of rotation (Rl, R2, R3, R4).

6. Machine (10) as in any one of the preceding claims, characterized in that said plurality of cutting devices (35, 36, 37, 38) is configured to cut without stopping the respective transit rollers (31, 32, 33, 34).

7. Machine (10) as in any one of the preceding claims, characterized in that the rollers of each pair of buffer rollers (411, 412, 421, 422, 431, 432, 441, 442) are pivoted on a respective arm (413, 414, 423, 424, 433, 434, 443, 444) rotating about a common axis of rotation (Rl, R2, R3, R4).

8. Method for making electrical energy storage devices, said method comprising the steps of continuously feeding a cathode film (25), an anode film (27) and at least one separator film (26, 28) between said cathode film (25) and said anode film (27), receiving each of said films (25, 26, 27, 28) on a respective transit roller (31, 32, 33, 34), cutting, by means of cutting devices (35, 36, 37, 38), each of said films (25, 26, 27, 28) of a predefined length on a respective transit roller (31, 32, 33, 34), temporarily winding a respective segment of said films (25, 26, 27, 28) about a respective plurality of transfer rollers (511, 512, 513, 514) and transferring them to a respective winding core (53) mounted on a rotating member (50) located downstream of said plurality of transit rollers (31, 32, 33, 34), rotatably driving said winding core (53) so as to wind said segments of film (25, 26, 27, 28) taken from the transfer rollers (511, 512, 513, 514) to form a respective wound element (100), characterized by further comprising, before temporarily winding a respective segment of said films (25, 26, 27, 28) about a plurality of transfer rollers (511, 512, 513, 514), a step of feeding said films (25, 26, 27 28) to a buffer unit (40) located between said plurality of transit rollers (31, 32, 33, 34) and said plurality of transfer rollers (511, 512, 513, 514), said buffer unit (40) comprising a respective pair of buffer rollers (411, 412, 421, 422, 431, 432, 441, 442) for each transit roller (31, 32, 33, 34), wherein each roller of the pair of buffer rollers (411, 412, 421, 422, 431, 432, 441, 442) cooperates alternately with a respective transit roller (31, 32, 33, 34) to wind a respective segment of said cathode film (25), anode film (27) and of the at least one separator film (26, 28), and subsequently feed saidsegments to a respective roller of said plurality of transfer rollers (511, 512, 513, 514).

9. Method as in claim 8, characterized in that said rotating member (50) is rotated with a stepwise motion so as to bring proximal to the transit rollers (31, 32, 33, 34) a respective plurality of transfer rollers (511, 512, 513, 514) at a time.

10. Method as in claim 8 or 9, characterized in that said cutting step is carried out while the respective transit roller (31, 32, 33, 34) is rotating.

11. Method as in claim 8, 9 or 10, characterized in that the rollers of said pair of buffer rollers (411, 412, 421, 422, 431, 432, 441, 442) are arranged in contact with the respective transit roller (31, 32, 33, 34) when cooperating with the latter.

12. Method as in any one of the claims from 8 to 11 , characterized in that when one roller of a respective pair of buffer rollers (411 , 421 , 431 , 441 ) is moved away from the respective transit roller (31, 32, 33, 34) towards one of the transfer rollers (511, 512, 513, 514), the other buffer roller of said pair of buffer rollers (412, 422, 432, 442) is immediately brought into contact with said respective transit roller(31, 32, 33, 34).

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