Stacking apparatus for alternately stacking a strip-shaped separator and electrode precursors

Abstract

A stacking apparatus (10) for alternately stacking a strip-shaped separator and electrode precursors comprises a stacking station (20) configured to receive electrode precursors (100, 101); a first transfer device (12) for transferring first electrode precursors (100) and a second transfer device (13) for transferring second electrode precursors (101) movable between a respective pick-up position and a release position; a feeder device (21) of a strip-shaped separator (102) configured to continuously feed a strip-shaped separator (102) towards the stacking device (20); a displacement device (23) configured to operate on the strip-shaped separator (102) and comprising an accompanying device (24) movable with alternating motion between a first end position (P1) and a second end position (P2) on the stacking station (20) to position the strip-shaped separator (102) between the first electrode precursors (100) and the second electrode precursors (101); a compensating device (31) configured to operate on the strip-shaped separator (102) and movable away from the accompanying device (24) at least when the accompanying device (24) is in the first end position (P1) and at least when the accompanying device (24) is in the second end position (P2).

Description

[0001] "Stacking apparatus for alternately stacking a strip-shaped separator and electrode precursors"

[0002] DESCRIPTION

[0003] The present invention refers to stacking apparatus for alternately stacking a stripshaped separator and electrode precursors, wherein electrode precursors are stacked together with the interposition of a strip-shaped separator.

[0004] The present invention finds a preferred, although not exclusive, application in the sector of the production of electric accumulators, for the realization of which a semi-finished product with an overlapping layer structure, for example stacked, is used.

[0005] In the industrial sector of the production of electric accumulators, electrochemical cells are produced made from stacks of positive and negative electrode precursors, arranged alternately one above the other, with a separation layer in dielectric material interposed, generally indicated in the technical jargon of the sector with the term "separator".

[0006] These electrochemical cells can be made by folding a strip-shaped separator according to a "Z" arrangement and interposing electrode precursors in the form of sheets that form an anode and cathode of an electrochemical cell, respectively, between one loop and another loop of the "Z".

[0007] The electrode precursors are substantially made by depositing a layer of electrode active material on one surface or both surfaces of a current collector metal foil. By choosing a suitable combination of active material for electrodes and of material of the current-collecting metal sheet, it is possible to obtain electrode precursors intended for making positive electrodes and electrode precursors intended for making negative electrodes.

[0008] The Applicant, in the context of the constant need to increase the performance and efficiency of the production processes for the realization of electrochemical cells, has felt the need to be able to have stacking apparatuses for a strip-shaped separator and electrode precursors that allow high production rates, that is, that allow high cell production speeds.

[0009] The Applicant has noted that in order to fold a strip-shaped separator according to a "Z" arrangement, in such a way as to be able to insert the electrode precursors inside the strip-shaped separator loops, it is appropriate to move the strip-shaped separator with an alternating motion between two points or end zones above a stacking station. In this way, successive portions of the stripshaped separator are laid on the stacking station and electrode precursors can be deposited on such portions of the strip-shaped separator. At each reversal of the direction of motion of the strip-shaped separator, it is possible to create a respective loop in the strip-shaped separator and to deposit an electrode precursor on the portion of the strip-shaped separator just laid on the stacking station.

[0010] The Applicant has also noted that such movement of the strip-shaped separator on the stacking station requires that the strip-shaped separator follow a law of motion that comprises the succession of dead points at the end zones (i.e. at the zones where the reversal of the direction of motion of the strip-shaped separator takes place) at which the speed of the strip-shaped separator with respect to the stacking station is substantially zero.

[0011] The Applicant has therefore observed that the speed with which the strip-shaped separator is unwound from a respective reel to be fed at the stacking station should follow the same law of motion with which the strip-shaped separator is placed on the stacking station. This law of motion should therefore provide for the succession of stops and restarts in the unwinding of the strip-shaped separator from the respective reel.

[0012] The Applicant has noted that as the deposition rate of electrode precursors on the stacking station increases, the accelerations and decelerations to which the reel of strip-shaped separator is subjected increase.

[0013] The Applicant has however observed that such accelerations and decelerations of the reel of strip-shaped separator introduce stresses into the strip-shaped separator which may compromise the structural integrity of the strip-shaped separator or which may trigger oscillatory phenomena in the strip-shaped separator compromising its correct deposition on the stacking station.

[0014] In order to increase the deposition rate of electrode precursors on the stacking station and therefore to increase the performance and efficiency of the production processes for the realization of electrochemical cells, the Applicant has perceived that it should be possible to continue to unwind the strip-shaped separator from the respective reel even when the strip-shaped separator is at zero speed with respect to the stacking station, i.e. when the direction of motion of the strip- shaped separator on the stacking station is reversed.

[0015] The Applicant has therefore found that by arranging a compensating device placed between the reel and the stacking station and configured to operate on the strip-shaped separator in such a way as to manage an excess of strip-shaped separator unwound from the reel, it is possible to continue to continuously unwind the strip-shaped separator from the respective reel even when the direction of motion of the strip-shaped separator on the stacking station is reversed.

[0016] In this way it is possible to increase the deposition rate of electrode precursors on the stacking station and thereby increase the performance and efficiency of the alternated implementation process of the strip-shaped separator and electrode precursors.

[0017] The present invention therefore concerns a stacking apparatus for alternately stacking a strip-shaped separator and electrode precursors.

[0018] Preferably, the apparatus comprises a stacking station configured to receive electrode precursors is provided.

[0019] Preferably, the apparatus comprises a first transfer device for transferring first electrode precursors and a second transfer device for transferring second electrode precursors respectively movable between a pick-up position and a release position, wherein the release position of the first transfer device and the release position of the second transfer device are placed at said stacking station and wherein the first transfer device and the second transfer device are configured in such a way that when the first transfer device is in the release position, the second transfer device is moved away from the release position and when the second transfer device is in the release position, the first transfer device is moved away from the release position.

[0020] Preferably, the apparatus comprises a feeder device of a strip-shaped separator configured to continuously feed a strip-shaped separator towards the stacking station.

[0021] Preferably, the apparatus comprises a displacement device configured to operate on the strip-shaped separator and comprising an accompanying device movable with alternating motion between a first end position and a second end position on the stacking station to position the separator between the first electrode precursors and the second electrode precursors. Preferably, the apparatus comprises a compensating device placed between the accompanying device and the feeder device configured to operate on the stripshaped separator.

[0022] Preferably, the compensating device is configured to move away from the accompanying device at least when the accompanying device is in the first end position and at least when the accompanying device is in the second end position.

[0023] The Applicant has verified that in this way, when the accompanying device is in the first end position or in the second end position and therefore when the stripshaped separator is reversing the deposition direction on the stacking station being at a substantially zero speed with respect to the stacking station, the compensating device moving away from the accompanying device can continue to receive strip-shaped separator from the feeder device. The feeder device can then continue to continuously feed the strip-shaped separator without having to decelerate or stop.

[0024] With the expression "continuous" referred to an expression of motion or movement or unwinding of a reel or feeding of the strip-shaped separator, is meant a movement, an unwinding or a feeding that takes place without continuity, that is, without there being a stop or interruption in the movement, unwinding or feeding. In particular, with reference to the unwinding of a strip-shaped separator from a reel, it is understood that the strip-shaped separator is never stopped during its unwinding from the reel.

[0025] By the expression "static condition" referred to a device, is meant that said device does not perform translations with respect to an absolute reference system, i.e. with respect to a reference system integral with the building in which the apparatus subject-matter of the present invention is mounted, being able to rotate with respect to an absolute reference system, for example to rotate about a rotation axis. For example, when a device of the apparatus which is the subjectmatter of the present invention is in a static condition, said device is fixed, being able to rotate only with respect to a rotation axis, with respect to a base frame of the apparatus.

[0026] By the expression "electrode precursor" is meant a current-collecting metal foil preferably having a layer of electrode-active material on one surface or on both surfaces of the metal foil.

[0027] By the expression "strip-shaped separator" is meant a strip having a dimension much greater than two additional dimensions, wherein a first dimension of such two additional dimensions is much greater than a second dimension of such two additional dimensions. The strip can be monolithic or formed by a plurality of layers joined together of identical material or different materials. A strip-shaped separator also has characteristics such as to allow some bending during its advancement along a relative feed line.

[0028] The present invention may have at least one of the preferred features described below. These characteristics can therefore be present individually or in combination with each other, except when expressly stated otherwise, in the apparatus of the present invention.

[0029] Preferably, said feeder device comprises an unwinding element configured to unwind the strip-shaped separator with continuous motion from a reel of stripshaped separator.

[0030] Preferably, the strip-shaped separator is a continuous strip-shaped separator, i.e. a strip-shaped separator having a single initial portion and a single final portion when deposited on the stacking station to form an electrochemical cell.

[0031] Preferably, said unwinding element is stationary.

[0032] Preferably, said unwinding element comprises one or more unwinding rollers.

[0033] Preferably, said compensating device comprises a translating device movable with alternating motion between a third end position and a fourth end position.

[0034] Preferably, the translating device acts on the separator before the separator reaches the displacement device.

[0035] Preferably, the translating device and the accompanying device are configured such that when the translating device is in the third end position, the translating device is closer to the first end position of the accompanying device than to the second end position of the accompanying device.

[0036] Preferably, the translating device and the accompanying device are configured such that when the translating device is in the fourth end position, the translating device is closer to the second end position of the accompanying device than to the first end position of the accompanying device.

[0037] By arranging the translating device movable with alternating motion between a third end position and a fourth end position, it is possible to oscillate the translating device above the accompanying device in such a way that, by appropriately phasing together the oscillation of the accompanying device between the first and second end positions and the oscillation of the translating device between the third and fourth end positions, the translating device compensates for the stops of the accompanying device in dead spots.

[0038] Preferably, the translating device and the accompanying device are configured such that when the accompanying device is in the first end position, the translating device moves away from the accompanying device.

[0039] In this way, when the accompanying device is in the first dead centre (given by the first end position) and therefore when the accompanying device has a zero speed with respect to the stacking station, the translating device of the compensating device compensates (keeping the strip-shaped separator at the correct tension) the excess strip-shaped separator fed towards the accompanying device.

[0040] Preferably, the translating device and the accompanying device are configured such that when the accompanying device is in the first end position, the translating device moves from the third end position towards the fourth end position.

[0041] In this way, the translating device of the compensating device moves away from the accompanying device placed in the first end position.

[0042] Preferably, the translating device and the accompanying device are configured such that when the accompanying device is in the second end position, the translating device moves away from the accompanying device.

[0043] In this way, when the accompanying device is in the second dead centre (given by the second end position) and therefore when the accompanying device has a zero speed with respect to the stacking station, the translating device of the compensating device compensates (keeping the strip-shaped separator at the correct tension) the excess strip-shaped separator fed towards the accompanying device.

[0044] Preferably, the translating device and the accompanying device are configured such that when the accompanying device is in the second end position, the translating device moves from the fourth end position towards the third end position.

[0045] In this way, the translating device of the compensating device moves away from the accompanying device placed in the second end position.

[0046] The accompanying device is preferably configured to move from the first end position (or the second end position) to the second end position (or the first end position) by first accelerating from the stop position at a constant speed, then moving along at least one stretch at a constant speed and finally decelerating to stop at the second (or first) end position.

[0047] Similarly, the translating device is preferably configured to move from the third end position (or the fourth end position) to the fourth end position (or the third end position) by first accelerating from the stop position at a constant speed, then moving along at least one stretch at a constant speed and finally decelerating to stop at the fourth (or third) end position.

[0048] Preferably, the translating device reaches the third end position when the accompanying device moves from the second end position to the first end position.

[0049] Preferably, the translating device reaches the fourth end position when the accompanying device moves from the first end position to the second end position.

[0050] Preferably, said stretch is a stretch in which the accompanying device moves at a constant speed.

[0051] Preferably, said compensating device comprises an oscillating pendulum driven by a drive shaft and supporting said translating device.

[0052] Preferably, said drive shaft is interposed between the feeder device and the stacking station.

[0053] Preferably, said drive shaft moves the oscillating pendulum with an alternating motion having a first point of reversal of motion at the first end position of the translating device and a second point of reversal of motion at the second end position of the translating device.

[0054] Preferably, said drive shaft reverses the direction of displacement of the oscillating pendulum at the first point of reversal of motion and at the second point of reversal of motion.

[0055] Preferably, said drive shaft is placed at a first end of the oscillating pendulum and said translating device is placed at a second end of the oscillating pendulum.

[0056] Preferably, the drive shaft is connected to the oscillating pendulum in a distal position with respect to the translating device.

[0057] Preferably, said second end of the oscillating pendulum is interposed between the first end of the oscillating pendulum and the stacking station.

[0058] Preferably, said translating device comprises a first translating roller and a second translating roller comprising a respective rotation axis.

[0059] Preferably, the rotation axis of the first translating roller is parallel to the rotation axis of the second translating roller.

[0060] Preferably, the first translating roller comprises an outer surface configured to contact the strip-shaped separator.

[0061] Preferably, the second translating roller comprises an outer surface configured to contact the strip-shaped separator.

[0062] Preferably, a distance separating the rotation axis of the first translating roller from the rotation axis of the second translating roller is greater than the sum of the radii of the first translating roller and the second translating roller.

[0063] Preferably, the distance separating the rotation axis of the first translating roller from the rotation axis of the second translating roller is equal to or greater than the sum of the radius of the first translating roller, the radius of the second translating roller and the thickness of the strip-shaped separator.

[0064] Preferably, said first translating roller and second translating roller are configured to receive and contact said strip-shaped separator.

[0065] Preferably, said first translating roller and second translating roller are configured to pass said strip-shaped separator between respective outer surfaces and between respective rotation axes.

[0066] Preferably, said compensating device comprises a deflecting roller having a rotation axis coaxial with said drive shaft. Preferably, the rotation axis of the deflecting roller is parallel to the rotation axis of the first translating roller and the second translating roller.

[0067] Preferably, the rotation axes of the first translating roller and the second translating roller are always interposed between the rotation axis of the deflecting roller and the stacking station.

[0068] Preferably, said deflecting roller is configured to deflect said strip-shaped separator towards said first translating roller and second translating roller.

[0069] Preferably, the accompanying device is configured to lay the strip-shaped separator on the stacking station.

[0070] Preferably, said displacement device comprises an oscillating arm driven by an actuation shaft and supporting said accompanying device.

[0071] Preferably, said actuation shaft is placed, with respect to said stacking station, on the opposite side with respect to said feeder device of the strip-shaped separator.

[0072] Preferably, said actuation shaft moves the oscillating arm with an alternating motion having a first point of reversal of motion at the first end position of the accompanying device and a second point of reversal of motion at the second end position of the accompanying device.

[0073] Preferably, said actuation shaft reverses the displacement direction of the oscillating arm at the first point of reversal of motion and at the second point of reversal of motion.

[0074] Preferably, the accompanying device is supported at a first end of said oscillating arm.

[0075] Preferably, the actuation shaft is connected to the oscillating arm in a distal position with respect to the accompanying device.

[0076] Preferably, the actuation shaft is connected to a second end, opposite to the first, of the oscillating arm.

[0077] Preferably, the stacking station comprises a substantially flat stacking surface.

[0078] Preferably said stacking surface lies in a plane parallel to the actuation shaft.

[0079] Preferably, when said accompanying device is placed in the first end position, or when said accompanying device is placed in the second end position, said stacking surface is interposed, with respect to a direction perpendicular to the stacking surface, between the feeder device and said accompanying device.

[0080] Preferably, when said accompanying device is placed in the first end position and when said accompanying device is placed in the second end position, said stacking surface is interposed, with respect to a direction perpendicular to the stacking surface, between the feeder device and said accompanying device.

[0081] Preferably, said accompanying device comprises a first accompanying roller having an outer surface configured to contact the strip-shaped separator.

[0082] Preferably, said accompanying device comprises a second accompanying roller having an outer surface configured to contact the strip-shaped separator.

[0083] Preferably, the first accompanying roller and the second accompanying roller are counter-rotating to each other.

[0084] Preferably, the first accompanying roller and the second accompanying roller comprise, respectively, a rotation axis.

[0085] Preferably, the rotation axis of the first accompanying roller is parallel to the rotation axis of the second accompanying roller.

[0086] Preferably, the rotation axis of the first accompanying roller and the second accompanying roller is parallel to the rotation axis of the first translating roller and the second translating roller.

[0087] Preferably, a distance separating the rotation axis of the first accompanying roller from the rotation axis of the second accompanying roller is greater than the sum of the radii of the first accompanying roller and the second accompanying roller.

[0088] Preferably, the distance separating the rotation axis of the first accompanying roller from the rotation axis of the second accompanying roller is equal to or greater than the sum of the radius of the first accompanying roller, the radius of the second accompanying roller and the thickness of the strip-shaped separator.

[0089] Preferably, at least one electric motor is connected to the first accompanying roller and the second accompanying roller for driving the first accompanying roller and the second accompanying roller. Preferably, said at least one electric motor is configured to rotate the first accompanying roller and the second accompanying roller while the accompanying device moves between the first end position and the second end position.

[0090] Preferably, said at least one electric motor is configured to stop the rotation of the first accompanying roller when the first accompanying roller is in the first end position.

[0091] Preferably, said at least one electric motor is configured to stop the rotation of the second accompanying roller when the second accompanying roller is in the second end position.

[0092] Preferably, said actuation shaft of the accompanying device is parallel to the rotation axis of the first accompanying roller and the second accompanying roller.

[0093] Preferably, said outer surface of the first accompanying roller rolls without creeping with respect to the strip-shaped separator.

[0094] Preferably, said outer surface of the second accompanying roller rolls without creeping with respect to the strip-shaped separator.

[0095] 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 view of a stacking apparatus for alternately stacking a strip-shaped separator and electrode precursors in accordance with the present invention; figure 2 is a further schematic view of the apparatus of figure 1 with some parts omitted to better highlight others; figures 3 and 4 are schematic perspective views of some components of the apparatus of figure 1 ; figures 5 to 10 are schematic representations of some operating conditions of the apparatus of figure 1 ; and figure 1 1 is a schematic perspective view of some components of the stacking apparatus of figure 1 .

[0096] The representations in the attached figures do not necessarily have to be understood in scale and do not necessarily respect the proportions between the various parts.

[0097] The apparatus 10 is preferably used to make electrochemical cells, for example secondary electrochemical cells, comprising flat electrodes separated from each other by a continuous dielectric separator.

[0098] The apparatus 10 comprises a support frame 11 on which the various components of the apparatus 10 are mounted.

[0099] The apparatus 10 comprises a first transfer device 12 for transferring first electrode precursors 100 and a second transfer device 13 for transferring second electrode precursors 101.

[0100] The first transfer device 12 comprises, in the preferred embodiment of the invention, a transfer plate 14 configured to contact and retain a first electrode precursor 100. The transfer plate 14 may for example comprise a suction device or suction cups (not illustrated) to allow a first electrode precursor 100 to be retained.

[0101] As schematically shown in figure 1 , the first transfer device 12 further comprises a kinematic mechanism 15 connected to the transfer plate 14 for moving the transfer plate 14.

[0102] Similarly, the second transfer device 13 comprises, in the preferred embodiment of the invention, a transfer plate 16 configured to contact and retain a second electrode precursor 101. The transfer plate 16 may for example comprise a suction device or suction cups (not illustrated) to allow a second electrode precursor 101 to be retained.

[0103] The second transfer device 13 further comprises a kinematic mechanism 17 connected to the transfer plate 16 for moving the transfer plate 16.

[0104] The first electrode precursors 100 are fed to the first transfer device 12 by a first plate feeder 18 (figure 1 ). The second electrode precursors 101 are fed to the second transfer device 13 by a second plate feeder 19 (figure 1 ).

[0105] The first transfer device 12 is movable between a pick-up position (illustrated in figure 1 ) and a release position. In the pick-up position, the transfer plate 14 is substantially positioned at the first plate feeder 18 and in contact with a first electrode precursor 100. The second transfer device 13 is movable between a pick-up position and a release position (illustrated in figure 1 ). In the pick-up position, the transfer plate 16 is substantially placed at the second plate feeder 19 and in contact with a second electrode precursor 101 .

[0106] The apparatus 10 comprises a stacking station 20 placed between the first transfer device 12 and the second transfer device 13. The stacking station 20 is provided with a stacking surface 20a configured to receive the electrode precursors 100, 101 . The stacking surface 20a is a flat surface.

[0107] When the first transfer device 12 is in the release position, the transfer plate 14 is positioned at the stacking station 20 to deposit the first electrode precursor 100 carried in the stacking station 20. When the second transfer device 13 is in the release position, the transfer plate 16 is placed at the stacking station 20 to deposit the second electrode precursor 101 carried in the stacking station 20.

[0108] As schematized in figures 1 , the first transfer device 12 and the second transfer device 13 move substantially counterphase. The first transfer device 12 and the second transfer device 13 are never both in their respective release positions. When the first transfer device 12 is in the release position, the second transfer device 13 is in the pick-up position, or is moving between the pick-up position and the release position. When the second transfer device 13 is in the release position, the first transfer device 12 is in the pick-up position, or is moving between the pick-up position and the release position. Note that since the first transfer device 12 and the second transfer device 13 remain in the release position for a time necessary to release the respective electrode precursor in the stacking station 20, when one transfer device is in the respective release position, the other transfer device moves toward and reaches the respective pick-up position.

[0109] The continuous movement of the first transfer device 12 and of the second transfer device 13 from the respective pick-up positions to the respective release positions (and from the respective release positions to the respective pick-up positions) results in the formation of a stack of alternately superimposed first electrode precursors 100 and second electrode precursors 101 in the stacking station 20. As schematized in figures 1 , the apparatus 10 further comprises a feeder device 21 of a strip-shaped separator 102 configured to continuously feed a strip-shaped separator 102 towards the stacking station 20.

[0110] The feeder device 21 is placed between the first transfer device 12 and the second transfer device 13 and above the stacking station 20.

[0111] The feeder device 21 comprises a rotating support 22 on which a reel 103 of stripshaped separator 102 is placed. From the reel 103 mounted on the rotating support 22, the strip-shaped separator 102 is continuously unwound and fed towards the stacking station 20.

[0112] The feeder device 21 further comprises an unwinding element 29 configured to unwind the strip-shaped separator 102 with continuous motion from the reel 103. The unwinding element 29 is stationary, i.e. it is mounted in a fixed position on the support frame 1 1 . As schematized in figure 1 , the unwinding element 29 can comprise a pair of motorized unwinding rollers 30 that act on the strip-shaped separator 102 to unwind it from the reel 103. Any other device suitable for unwinding the strip-shaped separator 102 from the reel 103 may be used in place of or in combination with the unwinding rollers 30.

[0113] The apparatus 10 comprises a displacement device 23 configured to operate on the strip-shaped separator 102 fed by the feeder device 20. The displacement device 23 operates at the stacking station 20 and is arranged between the first transfer device 12 and the second transfer device 13. The displacement device 23 has the function of positioning the strip-shaped separator 102 between the first and second electrode precursors that are deposited in the stacking station 20. The displacement device 23 is physically and functionally distinct from the first transfer device 12 and the second transfer device 13.

[0114] The strip-shaped separator 102 has the function of physically keeping the first electrode precursors 100 and the second electrode precursors 101 separate to avoid short circuits therebetween.

[0115] The resulting electrochemical cell is of the "bag" or "prismatic" type. Unlike cylindrical winding batteries, batteries using a bagged or prismatic cell do not use the "jelly roll" type winding method but use the "Z-folding" technique in which the strip-shaped separator 102 is inserted with zig-zag continuity around the anode (e.g. the first electrode precursors 100) and the cathode (e.g. the second electrode precursors 101 ). The displacement device 23 comprises a mobile accompanying device 24 with alternating motion between a first end position P1 (as shown in figure 1 ) and a second end position P2. The first end position P1 is placed between the stacking station 20 and the first transfer device 12 and the second end position P2 is placed between the stacking station 20 and the second transfer device 13. The stacking station 20 then develops between the first end position P1 and the second end position P2 of the accompanying device 24.

[0116] As better illustrated in figure 1 1 , the accompanying device 24 comprises, in the preferred embodiment of the invention, a first accompanying roller 24a configured to contact the strip-shaped separator 102 and to accompany it in the movement between the first end position P1 and the second end position P2. The accompanying device 24 further comprises a second accompanying roller 24b configured to contact the strip-shaped separator 102 and to accompany it in the movement between the second end position P2 and the first end position P1 . The first accompanying roller 24a and the second accompanying roller 24b are motorized by one or more electric motors 25 to be able to rotate independently. The first accompanying roller 24a and the second accompanying roller 24b are rotatable about respective rotation axes R1 , R2. The rotation axis R1 of the first accompanying roller 24a is parallel to the rotation axis R2 of the second accompanying roller 24b.

[0117] The rotation axis R1 of the first accompanying roller 24a is spaced from the rotation axis R2 of the second accompanying roller 24b by a distance that is substantially equal to the sum of the radii of the first accompanying roller 24a and the second accompanying roller 24b and the thickness of the strip-shaped separator 102. In other words, the strip-shaped separator passes between the first accompanying roller 24a and the second accompanying roller 24b without being crushed between those two accompanying rollers. The strip-shaped separator 102 is inserted between the first accompanying roller 24a and the second accompanying roller 24b and is preferably in contact with both an outer surface of the first accompanying roller 24a and an outer surface of the second accompanying roller 24b. The rotation axis R1 of the first accompanying roller 24a and the rotation axis R2 of the second accompanying roller 24b always remain at the same mutual distance during the passage of the first accompanying roller 24a and the second accompanying roller 24b between the first end position R1 and the second end position P2 and between the second end position P2 and the first end position P1 . When the first accompanying roller 24a and the second accompanying roller 24b move between the first end position P1 and the second end position P2, the first accompanying roller 24a and the second accompanying roller 24b exert a pulling action on the strip-shaped separator 102 capable of accompanying the latter from its own reel mounted on the rotating support 20. When the first accompanying roller 24a and the second accompanying roller 24b move between the first end position P1 and the second end position P2, the first accompanying roller 24a and the second accompanying roller 24b unwind the strip-shaped separator 102 on the stacking station 20 and in particular on the electrode precursor just deposited by the first transfer device 12 or by the second transfer device 13 on the stacking station 20.

[0118] The first accompanying roller 24a and the second accompanying roller 24b are placed in rotation about the respective rotation axes R1 , R2 in such a way as to make the first accompanying roller 24a and the second accompanying roller 24b counter-rotating to each other. The first accompanying roller 24a and the second accompanying roller 24b are placed in rotation about the respective rotation axes R1 , R2 in such a way as to cancel or in any case minimize relative slips between the strip-shaped separator 102 and the outer surface of the first accompanying roller 24a and of the second accompanying roller 24b. The first accompanying roller 24a and the second accompanying roller 24b roll without creeping on the strip-shaped separator 102.

[0119] As illustrated in figure 1 1 , the displacement device 23 comprises an actuator 26 connected to the first accompanying roller 24a and the second accompanying roller 24b for moving the latter between the first end position R1 and the second end position P2 and between the second end position P2 and the first end position P1 . The actuator 26 comprises an oscillating arm 27 hinged at a first end thereof to a motorised actuation shaft 28. The first accompanying roller 24a and the second accompanying roller 24b are hinged to the oscillating arm 27 at a second end thereof. The actuation shaft 28 is placed parallel to the rotation axes R1 , R2 of the first accompanying roller 24a and the second accompanying roller 24b. The actuation shaft 28 is placed, with respect to said stacking station 20, on the opposite side with respect to said feeder device 21. The actuation shaft 28 moves the oscillating arm 27 with an alternating motion having a first dead centre at the first end position P1 and a second dead centre at the second end position P2.

[0120] Between the stacking station 20 and the unwinding element 29, the apparatus 10 comprises a compensating device 31 (schematized with a rectangle in figure 1 and better illustrated in figures 2, 3 and 4). The compensating device 31 has a function of direct feed interface of the strip-shaped separator 102 between the feeder device 21 and the accompanying device 24, as illustrated in figure 2. Between the accompanying device 24 and the compensating device 31 there are no further members or devices, such as return members or the like, configured to act on the strip-shaped separator 102. The compensating device 31 is only rotatably mounted on the support frame 1 1 . The compensating device 31 cannot translate with respect to the support frame 11 .

[0121] The compensating device 31 comprises a translating device 32 movable with alternating motion between a third end position P3 and a fourth end position P4. The third end position P3 is placed on the side facing the first transfer device 12 and the fourth end position P4 is placed on the side facing the second transfer device 13. The distance separating the third end position P3 from the first end position P1 reached by the accompanying device 24 is smaller than the distance separating the third end position P3 from the second end position P2 reached by the accompanying device 24. The distance separating the fourth end position P4 from the first end position P1 reached by the accompanying device 24 is greater than the distance separating the fourth end position P4 from the second end position P2 reached by the accompanying device 24. The third end position P3 and the fourth end position P4 reached by the translating device 32 are spaced from the stacking station 20.

[0122] As best illustrated in figure 4, the translating device 32 comprises, in the preferred embodiment of the invention, a first translating roller 33 configured to contact the strip-shaped separator 102 and to accompany it in the movement between the fourth end position P4 and the third end position P3. The translating device 32 further comprises a second translating roller 34 configured to contact the stripshaped separator 102 and to accompany it in the movement between the third end position P3 and the fourth end position P4. The first translating roller 33 and the second translating roller 34 are preferably idle rollers, i.e. not motorized. The first translating roller 33 and the second translating roller 34 are rotatable about respective rotation axes R3, R4. The rotation axis R3 of the first translating roller 33 is parallel to the rotation axis R4 of the second translating roller 34.

[0123] The rotation axis R3 of the first translating roller 33 is spaced from the rotation axis R4 of the second translating roller 34 by a distance which is substantially equal to the sum of the radii of the first translating roller 33 and of the second translating roller 34 and of the thickness of the strip-shaped separator 102. In other words, the strip-shaped separator passes between the first translating roller 33 and the second translating roller 34 (as illustrated in figure 3) without being crushed between these two translating rollers. The strip-shaped separator 102 is inserted between the first translating roller 33 and the second translating roller 34 and is preferably in contact with both an outer surface 33a of the first translating roller 33 and an outer surface 33b of the second translating roller 34. The rotation axis R3 of the first translating roller 33 and the rotation axis R4 of the second translating roller 33 always remain at the same mutual distance during the passage of the first translating roller 33 and the second translating roller 34 between the third end position P3 and the fourth end position P4 and between the fourth end position P4 and the third end position P3.

[0124] When the translating device 31 moves between the third end position P3 and the fourth end position P4, and when the translating device 31 moves between the fourth end position P4 and the third end position P3, the translating device 31 exerts a pulling action on the strip-shaped separator 102 capable of accompanying the latter in the path followed by the translating device 31 .

[0125] As illustrated in figure 3, the compensating device 31 comprises an oscillating pendulum 35 that supports the translating device 32. The oscillating pendulum 35 is driven by a drive shaft 36 which is connected to an electric motor 37. The drive shaft 36 is positioned at a first end of the oscillating pendulum 35 and the translating device 32 is positioned at a second end of the oscillating pendulum 35. Said second end of the oscillating pendulum 35 is a free end which, during the oscillation of the oscillating pendulum 35 reaches the third end position P3 and the fourth end position P4. As illustrated in figure 4, the oscillating pendulum

[0126] 35 is an elongated body rotatable about the drive shaft 36. The oscillating pendulum 35 is connected to the first translating roller 33 and the second translating roller 34 to move the latter between the third end position P3 and the fourth end position P4 and between the fourth end position P4 and the third end position P3. The first translating roller 33 and the second translating roller 34 are hinged to the oscillating pendulum 35 at the second end thereof. The drive shaft

[0127] 36 is placed parallel to the rotation axes R3, R4 of the first translating roller 33 and the second translating roller 34. The drive shaft 36 moves the oscillating pendulum 35 with an alternating motion having a first dead centre at the third end position P3 and a second dead centre at the fourth end position P4. The drive shaft 36 is only rotatably mounted on the support frame 1 1 . As illustrated in figure 3, the compensating device 31 further comprises a deflecting roller 38 configured to contact the strip-shaped separator 102 and deflect it towards the translating device 32. As best depicted in figure 4, deflecting roller 38 has a rotation axis R5 coaxial with drive shaft 36. The rotation axis R5 of the deflecting roller 38 is parallel to the rotation axis R3 of the first translating roller 33 and the rotation axis R4 of the second translating roller 34. A return roller 39 (or a plurality of return rollers) may be provided in proximity to the deflecting roller 38 to deflect the strip-shaped separator 102 from the feeder device 21 and to the compensating device 31 , as schematically illustrated in figure 3.

[0128] As schematically illustrated in figures 5 and 6, the translating device 32 is configured to move away from the accompanying device 24 when the accompanying device 24 is in the first end position R1 . When the accompanying device 24 is in the first end position R1 , the accompanying device 24 reverses its direction of motion and therefore reaches a condition of substantial immobility in exact correspondence with the reversal of the direction of motion. In this condition, the translating device 32 moves away from the accompanying device 24 in such a way as to progressively lengthen the path that the strip-shaped separator 102 must travel to reach the accompanying device 24. In this way, the strip-shaped separator 102 is maintained at a suitable tension while the accompanying device 24 is substantially stationary and while the feeder device 21 continuously feeds the strip-shaped separator 102 towards the stacking station 20. As illustrated in figures 5 and 6, the translating device 32 moves while the accompanying device 24 is substantially stationary. In particular, when the accompanying device 24 is in the first end position P1 , the translating device 32 moves from the third end position P3 towards the fourth end position P4.

[0129] When the accompanying device 24 moves from the first end position P1 towards the second end position P2, the translating device 32 continues its movement towards the fourth end position P4 until it reaches it, as schematized in figure 7.

[0130] When the translating device 32 reaches the fourth end position P4 (as illustrated in figure 7), the accompanying device 24 has not yet reached the second end position P2. When the translating device 32 reaches the fourth end position P4, the translating device 32 reverses its direction of motion and therefore reaches a condition of substantial immobility in exact correspondence with the reversal of the direction of motion. In this condition, i.e. when the translating device 32 reverses its direction of motion, the accompanying device 24 is moving between the first end position P1 and the second end position P2. As schematically illustrated in figure 8, when the accompanying device 24 reaches the second end position P2, the translating device 32 is movable away from the accompanying device 24. When the accompanying device 24 is in the second end position P2, the accompanying device 24 reverses its direction of motion and therefore reaches a condition of substantial immobility in exact correspondence with the reversal of the direction of motion. In this condition, the translating device 32 moves away from the accompanying device 24 in such a way as to progressively lengthen the path that the strip-shaped separator 102 must travel to reach the accompanying device 24. In this way, the strip-shaped separator 102 is maintained at a suitable tension while the accompanying device 24 is substantially stationary and while the feeder device 21 continuously feeds the strip-shaped separator 102 towards the stacking station 20. As illustrated in figure 8, the translating device 32 moves while the accompanying device 24 is substantially stationary. In particular, when the accompanying device 24 is in the second end position P2, the translating device 32 moves from the fourth end position P4 towards the third end position P3.

[0131] When the accompanying device 24 moves from the second end position P2 towards the first end position P1 , the translating device 32 continues its movement towards the third end position P3, as schematized in figure 9.

[0132] When the translating device 32 reaches the third end position P3 (as illustrated in figure 10), the accompanying device 24 has not yet reached the first end position P1 . When the translating device 32 reaches the third end position P3, the translating device 32 reverses its direction of motion and therefore reaches a condition of substantial immobility in exact correspondence with the reversal of the direction of motion. In this condition, i.e. when the translating device 32 reverses its direction of motion, the accompanying device 24 is moving between the second end position P2 and the first end position P1 . When the accompanying device 24 returns to the first end position P1 , the description in relation to figure 5 is repeated.

Claims

CLAIMS1. Stacking apparatus (10) for alternately stacking a strip-shaped separator and electrode precursors comprising: a stacking station (20) configured to receive electrode precursors (100, 101 ); a first transfer device (12) for transferring first electrode precursors (100) and a second transfer device (13) for transferring second electrode precursors (101 ) respectively movable between a pick-up position and a release position, wherein the release position of the first transfer device (12) and the release position of the second transfer device (13) are placed at said stacking station (20) and wherein the first transfer device (12) and the second transfer device (13) are configured in such a way that when the first transfer device (12) is in the release position, the second transfer device (13) is moved away from the release position and when the second transfer device (13) is in the release position, the first transfer device (12) is moved away from the release position; a feeder device (21 ) of a strip-shaped separator (102) configured to continuously feed a strip-shaped separator (102) towards the stacking station (20); a displacement device (23) configured to operate on the strip-shaped separator (102) and comprising an accompanying device (24) movable with alternating motion between a first end position (P1 ) and a second end position (P2) on the stacking station (20) to position the strip-shaped separator (102) between the first electrode precursors (100) and the second electrode precursors (101 ); a compensating device (31 ) placed between the accompanying device (24) and the feeder device (21 ) configured to operate on the strip-shaped separator (102); the compensating device (31 ) being configured to move away from the accompanying device (24) at least when the accompanying device (24) is in the first end position (P1 ) and at least when the accompanying device (24) is in the second end position (P2).

2. Apparatus (10) according to claim 1 , wherein said feeder device (21 ) comprises an unwinding element (29) configured to unwind the strip-shaped separator (102) with continuous motion from a reel (103) of strip-shaped separator; said unwinding element (29) being stationary.

3. Apparatus (10) according to claim 1 or 2, wherein said compensating device (31 ) comprises a translating device (32) movable with alternating motion between a third end position (P3) and a fourth end position (P4).

4. Apparatus (10) according to claim 3, wherein the translating device (32) and the accompanying device (24) are configured such that when the accompanying device (24) is in the first end position (P1 ), the translating device (32) moves away from the accompanying device (24).

5. Apparatus (10) according to claim 3 or 4, wherein the translating device (32) and the accompanying device (24) are configured such that when the accompanying device (24) is in the first end position (P1 ), the translating device (32) moves from the third end position (P3) towards the fourth end position (P4).

6. Apparatus (10) according to any one of claims 3 to 5, wherein the translating device (32) and the accompanying device (24) are configured such that when the accompanying device (24) is in the second end position (P2), the translating device (32) moves away from the accompanying device (24).

7. Apparatus (10) according to any one of claims 3 to 6, wherein the translating device (32) and the accompanying device (24) are configured such that when the accompanying device (24) is in the second end position (P2), the translating device (32) moves from the fourth end position (P4) towards the third end position (P3).

8. Apparatus (10) according to any one of claims 3 to 7, wherein the translating device (32) and the accompanying device (24) are configured such that the translating device (32) reaches the third end position (P3) when the accompanying device (24) moves from the second end position (P2) to the first end position (P1 ).

9. Apparatus (10) according to any one of claims 3 to 8, wherein the translating device (32) and the accompanying device (24) are configured such that the translating device (32) reaches the fourth end position (P4) when the accompanying device (24) moves from the first end position (P1 ) to the second end position (P2).

10. Apparatus (10) according to any one of claims 3 to 9, wherein said compensating device (31 ) comprises an oscillating pendulum (35) driven by a drive shaft (36) and supporting said translating device (32); said drive shaft (36) being interposed between the feeder device (21 ) and the stacking station (20).11 . Apparatus (10) according to claim 10, wherein said drive shaft (36) is placed at a first end of the oscillating pendulum (35) and said translating device (32) is placed at a second end of the oscillating pendulum (35), said second end of the oscillating pendulum (35) being interposed between the first end of the oscillating pendulum (35) and the stacking station (20).

12. Apparatus (10) according to claim 10 or 1 1 , wherein said compensating device (31 ) comprises a deflecting roller (38) having a rotation axis (R5) coaxial with said drive shaft (36) and wherein said translating device (32) comprises a first translating roller (33) and a second translating roller (34) rotatable about respective rotation axes (R3, R4) parallel to the rotation axis (R5) of the deflecting roller (38); said deflecting roller (38) being configured to deflect said strip-shaped separator (102) towards said first translating roller (33) and said second translating roller (34) and said first translating roller (33) and said second translating roller (34) being configured to receive and contact said strip-shaped separator (102).

13. Apparatus (10) according to any one of the preceding claims, wherein said displacement device (23) comprises an oscillating arm (27) driven by an actuation shaft (28) and supporting said accompanying device (24); said actuation shaft (28) being placed, with respect to said stacking station (20), on the opposite side with respect to said compensating device (31 ).

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