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

Abstract

A stacking apparatus (10) for alternately stacking a continuous 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); a feeder device (21) of a continuous strip-shaped separator (102) configured to feed a continuous strip-shaped separator (102) towards the stacking station (20); a displacement device (23) comprising an accompanying device (24) configured to operate on the continuous strip-shaped separator (102) and movable between a first end 0 position (P1) and a second end position (P2) above the stacking station (20); wherein the accompanying device (24) comprises a first accompanying roller (24a) and a second accompanying roller (24b) configured to contact the strip-shaped separator (102) and to displace it between the first end position (P1) and the second end position (P2) and rotatable about their own rotation axes (R1, R2) parallel to each other, wherein the first accompanying roller (24a) and the second accompanying roller (24b) are movable parallel to their own rotation axes (R1, R2) between a plurality of stable axial positions.

Description

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

[0002] DESCRIPTION

[0003] The present invention refers to stacking apparatus for alternately stacking a continuous strip-shaped separator and electrode precursors.

[0004] The present invention is preferably directed to a stacking apparatus wherein the continuous strip-shaped separator is a dielectric separator the electrode precursors are sheet foils of cathode precursors and anode precursors of an electrochemical cell.

[0005] The present invention can be used to make electrochemical cells, for example secondary electrochemical cells, comprising flat electrodes separated from each other by a continuous dielectric separator.

[0006] In the industrial sector of the production of electric accumulators, electrochemical cells are produced made from stacks of positive and negative electrodes, arranged alternately one above the other, with interposed a separation layer of dielectric material, generally indicated in the technical jargon of the sector with the term "separator", formed by a single continuous strip folded between the electrodes.

[0007] In Applicant's experience, such electrochemical cells may be produced with a stacking apparatus for stacking one or more continuous strip-shaped separators and electrode precursors to automate the production process.

[0008] In accordance with the Applicant's experience, such a stacking apparatus may comprise a fixed base frame on which a first electrode precursor receiving station, a second electrode precursor receiving station and a stacking station located between the two receiving stations are mounted. Above the fixed frame there is positioned a movable frame that moves with alternated straight motion parallel to the fixed frame. Electrode precursor gripping equipments are mounted on the movable frame which picks up the electrode precursors from the receiving stations and releases them into the stacking station. A strip-shaped separator unwinder is also mounted on the movable frame which is fed by a continuous strip-shaped separator reel. The strip-shaped separator unwinder comprises two idle accompanying rollers, having mutually parallel rotation axes which deflect the path of the separator above the stacking station as the electrode precursors are deposited. When the movable frame translates to move a gripping equipment that has just deposited an electrode precursor in the stacking station away, the accompanying rollers translate integrally with the movable frame above the electrode precursor just deposited in the stacking station and position the stripshaped separator above the sheet foil just deposited. The process is cyclically implemented to form a cell composed of a stack of electrode precursors wherein each electrode precursor is separated from another electrode precursor by the strip-shaped separator which thus assumes an "accordion" shape within the cell (this accordion shape being known in the art as "z folding"). When the electrochemical cell is completed, the strip-shaped separator is cut and the cell thus obtained is removed from the stacking station to free the stacking station and allow the entire process to be repeated to make a further electrochemical cell.

[0009] There is an increasing need, particularly in the industrial sector for the production of electric accumulators, to have stacking devices to alternately stack a stripshaped separator and electrode precursors that allow high production rates, that is, that allow high production speeds of electrochemical cells.

[0010] The Applicant has noted that in an apparatus of the type summarily described above, the production speed could be limited by periodic machine stops necessary to restore the precision with which the accompanying rollers are actually able to position the strip-shaped separator exactly above the electrode precursor just deposited in the stacking station.

[0011] The Applicant has in fact observed that the strip-shaped separator dragged by the accompanying rollers tends to perform micro translations on the surfaces of the accompanying rollers in a direction parallel to the rotation axes of the accompanying rollers. The Applicant considers that these micro translations could be the effect of a lack of absolute parallelism between the unwinding axis of the reel of the strip-shaped separator and the rotation axis of the accompanying rollers, or, in combination, could be the effect of free oscillations of the section of strip-shaped separator extending between the reel and the accompanying rollers.

[0012] The Applicant has verified that these micro translations result in an alignment error, albeit minimal, between the just deposited electrode precursor and the separator strip deposited on it. This alignment error can be amplified at each stripshaped separator deposition step, requiring the stacking apparatus to stop when the alienation error exceeds tolerance limits in the stacking accuracy of the various strip-shaped separator layers. The Applicant has therefore felt the need to prevent or correct such alignment errors, so as to be able to reduce or cancel the required downtime to zero out the alignment errors and thus increase the production speed.

[0013] The Applicant has thought of arranging return rollers between the separator strip reel and the accompanying rollers, so as to decrease the free oscillation length of the strip-shaped separator.

[0014] The Applicant observed that this measure, although it seemingly decreases the alignment error, is not sufficient to achieve the desired result.

[0015] The Applicant has therefore perceived that it could be made an attempt to compensate for a possible alignment error by moving the strip-shaped separator parallel to the rotation axes of the accompanying rollers during the operation of the stacking apparatus.

[0016] The Applicant has found that by making the accompanying rollers movable parallel to their rotation axis, a possible alignment error could be compensated for by moving the accompanying rollers and with them the strip-shaped separator, so as not to have to stop the stacking apparatus to correct the alignment error and thus increase the production speed of electrochemical cells.

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

[0018] The apparatus preferably comprises a stacking station configured to receive electrode precursors.

[0019] The apparatus preferably 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.

[0020] The apparatus preferably comprises a feeder device for a strip-shaped separator configured to feed a strip-shaped separator towards the stacking station.

[0021] The apparatus preferably comprises a displacement device comprising an accompanying device configured to operate on the strip-shaped separator and movable between a first end position and a second end position above the stacking station. Preferably, the accompanying device comprises a first accompanying roller and a second accompanying roller configured to contact the strip-shaped separator and to displace it between the first end position and the second end position.

[0022] Preferably, the first accompanying roller and the second accompanying roller are rotatable about their own parallel rotation axes.

[0023] Preferably, the first accompanying roller and the second accompanying roller are movable along directions parallel to their rotation axes between a plurality of stable axial positions.

[0024] The Applicant has verified that by moving axially and holding the first accompanying roller and the second accompanying roller stably in an axial position, the strip-shaped separator also moves axially. By setting the axial displacement of the first and second accompanying rollers so as to compensate for the ongoing axial misalignment on the strip-shaped separator, it is possible to compensate for this axial misalignment and correctly position the strip-shaped separator between the first electrode precursors and the second electrode precursors.

[0025] "Electrode precursor" means a plate having two dimensions much larger than a third dimension. The electrode precursor may be a monolithic plate or a plate formed of a plurality of layers joined together of identical material or different materials.

[0026] "Strip-shaped separator" means 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.

[0027] "Axial or axially" means a direction parallel to the rotation axis of the first accompanying roller.

[0028] The present invention may have, in one or both of its aspects, at least one of the preferred features described below. Such features may be present individually or in combination with each other, unless expressly stated otherwise, both in the apparatus and in the method of the present invention.

[0029] Preferably, 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.

[0030] Preferably, the apparatus comprises a movement device configured to move the first accompanying roller and the second accompanying roller between said plurality of stable axial positions.

[0031] The movement device enables the first accompanying roller and the second accompanying roller to move axially according to the specific need, that is, according to the ongoing or expected axial misalignment of the strip-shaped separator.

[0032] Preferably, said movement device is configured to simultaneously move the first accompanying roller and the second accompanying roller between said plurality of stable axial positions.

[0033] The Applicant has verified that the strip-shaped separator can be displaced axially by the first accompanying roller and the second accompanying roller when the strip-shaped separator exerts a contact pressure on said first accompanying roller and second accompanying roller. This contact pressure generates a friction between the strip-shaped separator and the first accompanying roller and the second accompanying roller which enables the axial displacement of the stripshaped separator when the first accompanying roller and the second accompanying roller are displaced axially. Since the contact pressure that the strip-shaped separator exerts on the first accompanying roller and on the second accompanying roller varies during the movement of the displacement device above the stacking station, making both the first accompanying roller and the second accompanying roller axially movable along their rotation axes, it is possible to axially move the accompanying roller on which the greatest contact pressure is exerted at a given instant.

[0034] Preferably, the movement of the first accompanying roller and of the second accompanying roller above the stacking station between the first end position and the second end position results in a contact between said strip-shaped separator and the first accompanying roller, while the movement of the first accompanying roller and of the second accompanying roller above the stacking station between the second end position and the first end position results in a contact between said strip-shaped separator and said second accompanying roller.

[0035] Preferably, said movement device is configured to move the first accompanying roller and the second accompanying roller in an identical manner between said plurality of stable axial positions.

[0036] Preferably, said movement device is configured to axially lock the first accompanying roller and the second accompanying roller in any axial position of said plurality of stable axial positions.

[0037] Preferably, said first plurality of stable axial positions is comprised between a first axial end position and a second axial end position.

[0038] Preferably, each stable axial position of the first accompanying roller corresponds to a respective stable axial position of the second accompanying roller.

[0039] Preferably, said displacement device comprises an oscillating arm driven by an actuation shaft.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] Preferably, the first accompanying roller and the second accompanying roller are rotatably supported at a first end of said oscillating arm.

[0044] Preferably, the actuation shaft is connected to the oscillating arm in a distal position with respect to the first accompanying roller and the second accompanying roller.

[0045] Preferably, the actuation shaft is connected to a second end, opposite to the first, of the oscillating arm.

[0046] Preferably, said actuation shaft of the accompanying device is parallel to the rotation axis of the first accompanying roller and the second accompanying roller.

[0047] Preferably, the stacking station comprises a substantially flat stacking surface. Preferably said stacking surface lies in a plane parallel to the actuation shaft.

[0048] 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.

[0049] 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.

[0050] Preferably, the first accompanying roller has an outer surface configured to contact the strip-shaped separator.

[0051] Preferably, the second accompanying roller has an outer surface configured to contact the strip-shaped separator.

[0052] 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.

[0053] 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.

[0054] Preferably, said oscillating arm and said actuation shaft are rotatably mounted, with respect to a rotation axis of the actuation shaft, on a support structure.

[0055] Preferably, the oscillating arm, and with it the accompanying device, rotate with respect to the support structure oscillating around the rotation axis of the actuation shaft, so that the accompanying device moves with an alternating motion between the first end position and the second end position.

[0056] Preferably, said stacking station is fixed with respect to said support structure while said accompanying device moves between the first end position and the second end position.

[0057] In a first embodiment, preferably said movement device is configured to translate said oscillating arm along a direction parallel to the rotation axis of the first accompanying roller and parallel to the rotation axis of the second accompanying roller.

[0058] In this way, the axial translation of the oscillating arm causes a corresponding axial translation of the first accompanying roller and the second accompanying roller between said plurality of stable axial positions.

[0059] In this embodiment, preferably said movement device comprises a slide slidingly associated with a rail along an axial direction.

[0060] Preferably, said movement device further comprises an actuator connected to said slide to move said slide in an axial direction along said rail.

[0061] Preferably, said oscillating arm is axially slidable with respect to said rail and is axially integral with said slide.

[0062] In this way, when the actuator moves the slide, the slide slides along the rail translating the oscillating arm in an axial direction.

[0063] Preferably, said slide is integral with said support structure.

[0064] Preferably said support structure is slidably mounted on said rail.

[0065] Preferably, said oscillating arm is constrained to said support structure in an axial direction.

[0066] In this way, when the actuator moves the slide, the slide slides along the rail translating both the oscillating arm and the support structure in an axial direction.

[0067] Preferably, said actuator comprises an internally threaded bushing integral with said slide.

[0068] Preferably, said actuator comprises an electric motor having a threaded shaft inserted in said bushing.

[0069] Preferably said electric motor is integral with said rail.

[0070] When the electric motor rotates its threaded shaft, the threaded shaft engaged in the threaded bushing translates the threaded bushing which translates the slide.

[0071] In a second embodiment, preferably said movement device is configured to translate said first accompanying roller and said second accompanying roller with respect to said oscillating arm along a direction parallel to the rotation axis of the first accompanying roller and parallel to the rotation axis of the second accompanying roller.

[0072] In this embodiment, the oscillating arm is not axially translatable.

[0073] In this embodiment, preferably said movement device comprises a first slide equipment integral for translations in an axial direction with respect to the first accompanying roller and slidingly associated in an axial direction with respect to said oscillating arm.

[0074] Preferably, said movement device comprises a first actuator installed on said first slide equipment to translate said first slide equipment axially with respect to said oscillating arm.

[0075] In this way, by operating the first actuator, the first slide equipment translates axially. Since the first accompanying roller is integral with the first slide equipment, the first accompanying roller is also translated axially.

[0076] Preferably, said first slide equipment comprises a first slide integral for translations in the axial direction to a first end of the first accompanying roller and a second slide integral for translations in the axial direction to a second end of the first accompanying roller.

[0077] Preferably, said first accompanying roller is rotatable around its own rotation axis with respect to said first slide and said second slide.

[0078] In this way, the first accompanying roller is supported slidingly in the axial direction at both ends.

[0079] Preferably, said movement device further comprises a first rail integral with the oscillating arm and slidingly engaged by said first slide and a second rail integral with the oscillating arm and slidingly engaged by said second slide.

[0080] In this way, the oscillating arm functions as a support for the axial sliding of the first accompanying roller.

[0081] Preferably, said first slide comprises a threaded bushing and said first actuator comprises a threaded bushing which engages said threaded bushing.

[0082] When the first actuator rotates the threaded bushing, the threaded bushing is screwed or unscrewed from the threaded bushing.

[0083] Preferably, said threaded bushing is rotatable with respect to said oscillating arm and constrained to the oscillating arm so as not to translate axially with respect to the oscillating arm.

[0084] In this way, when the threaded bushing rotates, the threaded bushing can only rotate with respect to the oscillating arm and therefore the threaded bushing translates the threaded bushing as it is screwed or unscrewed in the threaded bushing. The translation of the threaded bushing causes a corresponding translation of the first accompanying roller.

[0085] Preferably, said threaded bushing is rotated by an electric motor of said movement device.

[0086] In the second embodiment, said movement device preferably comprises a second slide equipment integral for translations in an axial direction with respect to the second accompanying roller and slidingly associated in an axial direction with respect to said oscillating arm.

[0087] Preferably, said movement device comprises a second actuator able to translate said second slide equipment axially with respect to said oscillating arm.

[0088] In this way, by operating the second actuator, the second slide equipment translates axially. Since the second accompanying roller is integral with the second slide equipment, the second accompanying roller is also translated axially.

[0089] Preferably, said second slide equipment comprises a third slide integral for translations in an axial direction with a first end of the second accompanying roller and a fourth slide integral for axial translations with a second end of the second accompanying roller.

[0090] Preferably, said second accompanying roller is rotatable around its own rotation axis with respect to said third slide and said fourth slide.

[0091] In this way, the second accompanying roller is supported slidingly in the axial direction at both ends.

[0092] Preferably, said movement device further comprises a third rail integral with the oscillating arm and slidingly engaged by said third slide and a fourth rail integral with the oscillating arm and slidingly engaged by said fourth slide.

[0093] In this way, the oscillating arm functions as a support for the axial sliding of the second accompanying roller. Preferably, said third slide comprises a threaded bushing and said second actuator comprises a threaded bushing which engages said threaded bushing.

[0094] When the second actuator rotates the threaded bushing, the threaded bushing is screwed or unscrewed from the threaded bushing.

[0095] Preferably, said threaded bushing is rotatable with respect to said oscillating arm and constrained to the oscillating arm so as not to translate axially with respect to the oscillating arm.

[0096] In this way, when the threaded bushing rotates, the threaded bushing can only rotate with respect to the oscillating arm and therefore the threaded bushing translates the threaded bushing as it is screwed or unscrewed in the threaded bushing. The translation of the threaded bushing causes a corresponding translation of the second accompanying roller.

[0097] Preferably, said threaded bushing is rotated by an electric motor of said movement device.

[0098] Preferably, the electric motor that rotates the threaded bushing of the first actuator is the same electric motor that rotates the threaded bushing of the second actuator.

[0099] In this way, with a single electric motor it is possible to translate both the first accompanying roller and the second accompanying roller axially.

[0100] In addition, in this way it is possible to ensure that the first accompanying roller and the second accompanying roller translate axially simultaneously and by the same amount.

[0101] Preferably, said single electric motor comprises a rotation shaft parallel to the rotation axis of the first and second accompanying roller.

[0102] Preferably, a transmission kinematic mechanism is provided between the rotation shaft of the electric motor, the threaded bushing of the first actuator and the threaded bushing of the second actuator.

[0103] Preferably, said transmission kinematic mechanism is a transmission belt.

[0104] 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 schematic perspective view of some components of the stacking apparatus of figure 1 ; figures 3 and 4 are schematic front views of a first embodiment and a second embodiment of the apparatus of figure 1 ; figure 5 is a schematic side view, partially in section, of the apparatus of figure 1 in the first embodiment; and figures 6 and 7 are schematic side views, partially in section, of the apparatus of figure 1 in the second embodiment.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] The first transfer device 12 for transferring first electrode precursors 100 and the second transfer device 13 for transferring second electrode precursors 101 are mounted on a support frame 11 .

[0109] 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.

[0110] 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.

[0111] 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.

[0112] The second transfer device 13 further comprises a kinematic mechanism 17 connected to the transfer plate 16 for moving the transfer plate 16.

[0113] 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 ).

[0114] 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 .

[0115] 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.

[0116] 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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] The feeder device 21 is placed between the first transfer device 12 and the second transfer device 13 and above the stacking station 20.

[0121] 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.

[0122] 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 11 . 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.

[0123] 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.

[0124] 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.

[0125] 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 ).

[0126] 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.

[0127] As best illustrated in figure 2, the accompanying device 24 comprises 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.

[0128] In some embodiments, the first accompanying roller 24a and the second accompanying roller 24b can be motorized by one or more electric motors 25 in order to rotate independently.

[0129] In any case, the first accompanying roller 24a and the second accompanying roller 24b are rotatable around 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.

[0130] 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 P1 and the second end position P2 and between the second end position P2 and the first end position P1 .

[0131] 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.

[0132] In embodiments in which the first accompanying roller 24a and the second accompanying roller 24b are motorized, the first accompanying roller 24a and the second accompanying roller 24b counter-rotate 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.

[0133] As illustrated in figure 2, 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 P1 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.

[0134] As illustrated in figures 3 and 4, the apparatus 10 comprises a support structure 31 on which the oscillating arm 27 is rotatably mounted. The oscillating arm 27 is rotatably mounted on the support structure 31 at the actuation shaft 28. The actuation shaft 28 is in fact rotatably supported, for example by bearings (not illustrated) by the support structure 31 in order to rotate with respect thereto. The stacking station 20 is also mounted on the support structure 31. The stacking station 20 can be integral with the support structure 31 or can be rotatably mounted on the support structure 31 . In the latter case, a plurality of stacking stations 20 can be provided mounted on the periphery of a drum 32 rotatably mounted on the support structure 31 , as schematically illustrated in figures 3 and 4. When the accompanying device 24 deposits the strip-shaped separator 102, the stacking station is always fixed with respect to the support structure 31 , that is, it does not translate and does not rotate with respect to the support structure 31.

[0135] The apparatus 10 comprises a movement device 33 configured to move the first accompanying roller 24a and the second accompanying roller 24b between a plurality of distinct axial positions, so as to compensate for any axial misalignments of the strip-shaped separator 102 by displacing the latter axially as a result of the axial displacement of the first accompanying roller 24a and the second accompanying roller 24b.

[0136] In accordance with the embodiment illustrated in figures 3 and 5, the movement device 33 acts on the oscillating arm 27 by displacing the latter axially with respect to the stacking station 20. The movement device 33 translates the support structure 31 axially and with it the oscillating arm 27. The movement device 33 acts on the oscillating arm 27 only by translating the latter parallel to the rotation axis R1 of the first accompanying roller 24a and parallel to the rotation axis R2 of the second accompanying roller 24b and with respect to the stacking station 20.

[0137] As shown in figures 3 and 5, the movement device 33 comprises a rail 34 which extends in an axial direction, that is, parallel to the rotation axis R1 of the first accompanying roller 24a and parallel to the rotation axis R2 of the second accompanying roller 24b. The rail 34 is fixed and is preferably mounted on a structure resting on or constrained to the floor of the plant in which the apparatus 10 is mounted. The support structure 31 and with it the oscillating arm 27 is mounted slidingly on the rail 34. In this regard, the movement device 33 comprises a slide 35 integral with the support structure 31 , which slide 35 is slidingly coupled to the rail 34.

[0138] As schematically illustrated in figure 5 (where the drum 32 carrying the stacking station 20 has not been depicted, an actuator 36 is configured to displace the slide 35 along the rail 34. In this regard, the actuator 36 comprises an internally threaded bushing 37 mounted integrally with the slide 35. In other words, the bushing 37 is constrained to slide 35 in such a way that a translation of the bushing 37 corresponds to an equal translation of the slide 35 along the rail 34. The actuator 36 further comprises an electric motor 38 which is mounted integral with the rail 34. The electric motor 38 can for example be mounted with a suitable bracket on the rail 34. The electric motor 38 comprises a motor shaft 39 which develops parallel to the rotation axis R1 of the first accompanying roller 24a and parallel to the rotation axis R2 of the second accompanying roller 24b. The motor shaft 39 is threaded in such a way as to create a worm screw and is inserted into the bushing 37 to couple with the internal thread of the bushing 37.

[0139] When the electric motor 38 rotates the motor shaft 39, the latter is screwed or unscrewed (depending on the direction of rotation of the electric motor 38) in the bushing 37, forcing the latter to translate as a result of the engagement of the thread of the motor shaft 39 with the internal thread of the bushing 37. The translation of the bushing 37 causes a translation of the slide 35 along the rail 34 and therefore a translation of the support structure 31 and of the oscillating arm 27 with respect to the stacking station 20. The translation of the oscillating arm 27 causes an equal translation of the first accompanying roller 24a and the second accompanying roller 24b with respect to the stacking station 20. Note that by stopping the rotation of the motor shaft 39, the first accompanying roller 24a and the second accompanying roller 24b remain stably in the axial position reached, compensating for any axial misalignments of the strip-shaped separator 102 with respect to the stacking station 20.

[0140] In a second embodiment illustrated in figures 4, 6 and 7, the movement device 33 is configured to translate the first accompanying roller 24a and the second accompanying roller 24b with respect to the oscillating arm 27 along a direction parallel to the rotation axis R1 of the first accompanying roller 24a and parallel to the rotation axis R2 of the second accompanying roller 24b.

[0141] As schematically illustrated in figure 6, the movement device 33 comprises a first slide equipment 40 mounted on the first accompanying roller 24a and integral for axial translations with the first accompanying roller 24a. The first accompanying roller 24a translates in an axial direction integral with the first slide equipment 40. The first slide equipment 40 is slidingly mounted on the oscillating arm 27 to translate in an axial direction with respect to the oscillating arm 27. In this embodiment, the oscillating arm 27 is not translatable in the axial direction with respect to the stacking station 20. The first slide equipment 40 comprises a first slide 41 and a second slide 42. The first slide 41 and the second slide 42 are placed at opposite axial ends of the first accompanying roller 24a. The first accompanying roller 24a is rotatable about its rotation axis R1 with respect to the first slide 41 and with respect to the second slide 42.

[0142] The first slide 41 is mounted on a first rail 43 mounted integral with the oscillating arm 27 at an axial end of the first accompanying roller 24a. The second slide 42 is mounted on a second rail 44 mounted integral with the oscillating arm 27 at an axial end of the first accompanying roller 24a opposite the axial end on which the first slide 41 is mounted.

[0143] In order to be able to translate the first slide 41 and the second slide 42 along the first rail 43 and along the second rail 44, the movement device 33 comprises a first actuator 45 active on the first slide 41 . The first actuator 45 comprises a threaded bushing 46 (or threaded pin) which is rotated about an axis parallel to the rotation axis R1 of the first accompanying roller 24a. The first slide 41 comprises a threaded bushing 47 internally in which the threaded bushing 46 is engaged in a screwing and unscrewing relationship. The threaded bushing 46 is rotatable about an axis parallel to the rotation axis R1 of the first accompanying roller 24a with respect to the oscillating arm 27 and is integral for translations in the axial direction with the oscillating arm 27. When the threaded bushing 46 is rotated, the threaded bushing 46 is screwed or unscrewed (depending on the direction of rotation) in the threaded bushing 47, forcing the latter to translate as a result of the engagement of the thread of the threaded bushing 46 with the thread of the threaded bushing 47. The translation of the threaded bushing 47 causes a translation of the first slide 41 along the first rail 43 and therefore, by means of the first accompanying roller 24a, a translation of the second slide 42 along the second rail 44. The first accompanying roller 24a therefore translates with respect to the oscillating arm 27 along an axial direction.

[0144] Note that by stopping the rotation of the threaded bushing 46, the first accompanying roller 24a remains stably in the axial position reached.

[0145] In the second embodiment, as schematically illustrated in figure 7, the movement device 33 comprises a second slide equipment 48 mounted on the second accompanying roller 24b and integral with it for axial translations to the second accompanying roller 24b. The second accompanying roller 24b translates in the axial direction in an integral manner with the second slide equipment 48. The second slide equipment 48 is slidably mounted on the oscillating arm 27 to translate in an axial direction with respect to the oscillating arm 27. The second slide equipment 48 comprises a third slide 49 and a fourth slide 50. The third slide

[0146] 49 and the fourth slide 50 are placed at opposite axial ends of the second accompanying roller 24b. The second accompanying roller 24b is rotatable about its rotation axis R2 with respect to the third slide 49 and with respect to the fourth slide 50.

[0147] The third slide 49 is mounted on a third rail 51 mounted integral with the oscillating arm 27 at an axial end of the second accompanying roller 24b. The fourth slide

[0148] 50 is mounted on a fourth rail 52 mounted integral with the oscillating arm 27 at an axial end of the second accompanying roller 24b opposite the axial end on which the third slide 49 is mounted.

[0149] In order to be able to translate the third slide 49 and the fourth slide 50 along the third rail 51 and along the fourth rail 52, the movement device 33 comprises a second actuator 53 active on the third slide 49. The second actuator 53 comprises a threaded bushing 54 (or threaded pin) which is rotated about an axis parallel to the rotation axis R2 of the second accompanying roller 24b. The third slide 49 comprises a threaded bushing 55 internally in which the threaded bushing 54 is engaged in a screwing and unscrewing relationship. The threaded bushing 54 is rotatable about an axis parallel to the rotation axis R2 of the second accompanying roller 24b with respect to the oscillating arm 27 and is integral for translations in the axial direction with the oscillating arm 27. When the threaded bushing 54 is rotated, the threaded bushing 54 is screwed or unscrewed (depending on the direction of rotation) in the threaded bushing 55, forcing the latter to translate as a result of the engagement of the thread of the threaded bushing 54 with the thread of the threaded bushing 55. The translation of the threaded bushing 55 causes a translation of the third slide 49 along the third rail 49 and therefore, by means of the second accompanying roller 24b, a translation of the fourth slide 50 along the fourth rail 52. The second accompanying roller 24b therefore translates with respect to the oscillating arm 27 along an axial direction.

[0150] Note that by stopping the rotation of the threaded bushing 54, the second accompanying roller 24b remains stably in the axial position reached.

[0151] The threaded bushing 46 of the first actuator 45 and the threaded bushing 54 of the second actuator 53 are rotated simultaneously, at the same rotation speed and in the same direction, so that the first accompanying roller 24a and the second accompanying roller 24b are translated in the axial direction by the same amount and simultaneously.

[0152] For this purpose, the movement device 33 comprises an electric motor 56 which rotates the threaded bushing 46 of the first actuator 45 and the threaded bushing 54 of the second actuator 53. The electric motor 56 comprises a rotation shaft 57 parallel to the rotation axis R1 , R2 of the first accompanying roller 24a and the second accompanying roller 24b. Preferably, the rotation shaft 57 is coaxial with the actuation shaft 28 of the oscillating arm 27, as shown in figures 6 and 7. As schematically illustrated in figure 4, a transmission kinematic mechanism 58 is provided between the rotation shaft 57 of the electric motor 56, the threaded bushing 46 of the first actuator 45 and the threaded bushing 54 of the second actuator 53. The transmission kinematic mechanism 58 can be a transmission belt 59 (as schematically illustrated in figure 4) or a transmission chain or even a gear train. The transmission belt 59 transmits the rotary motion of the rotation shaft 57 of the electric motor 56 to the threaded bushing 46 of the first actuator 45 and to the threaded bushing 54 of the second actuator 53.

Claims

CLAIMS1. Stacking apparatus (10) for alternately stacking a continuous 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); a feeder device (21 ) of a continuous strip-shaped separator (102) configured to feed a continuous strip-shaped separator (102) towards the stacking station (20); a displacement device (23) comprising an accompanying device (24) configured to operate on the continuous strip-shaped separator (102) and movable between a first end position (P1 ) and a second end position (P2) above the stacking station (20); wherein the accompanying device (24) comprises a first accompanying roller (24a) and a second accompanying roller (24b) configured to contact the stripshaped separator (102) and to displace it between the first end position (P1 ) and the second end position (P2) and rotatable about their own rotation axes (R1 , R2) parallel to each other, wherein the first accompanying roller (24a) and the second accompanying roller (24b) are movable along directions parallel to their own rotation axes (R1 , R2) between a plurality of stable axial positions.

2. Apparatus (10) according to claim 1 , comprising a movement device (33) configured to move the first accompanying roller (24a) and the second accompanying roller (24b) between said plurality of stable axial positions.

3. Apparatus (10) according to claim 2, wherein said movement device (33) is configured to axially lock the first accompanying roller (24a) and the second accompanying roller (24b) in any axial position of said plurality of stable axial positions.

4. 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 rotatably 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 accompanying device (24).

5. Apparatus (10) according to claim 4 wherein said oscillating arm (27) and said actuation shaft (28) are rotatably mounted, with respect to a rotation axis of said actuation shaft (28), on a support structure (31 ), said stacking station (20) being fixed with respect to said support structure (31 ) while said accompanying device (24) moves between the first end position (P1 ) and the second end position (P2).

6. Apparatus (10) according to claim 4 or 5, wherein said movement device (33) is configured to translate said oscillating arm (27) along a direction parallel to the rotation axis (R1 ) of the first accompanying roller (24a) and parallel to the rotation axis (R2) of the second accompanying roller (24b).

7. Apparatus (10) according to claim 6, wherein said movement device (33) comprises a slide (35) slidingly associated with a rail (34) along an axial direction and an actuator (36) connected to said slide (35) for moving said slide (35) in an axial direction along said rail (34); said oscillating arm (27) being axially sliding with respect to said rail (34) and being axially integral with said slide (35).

8. Apparatus (10) according to claims 5 and 7, wherein said slide (35) is integral with said support structure (31 ) and wherein said actuator (36) comprises an internally threaded bushing (37) integral with said slide (35); said actuator (36) comprising an electric motor (38) having a threaded motor shaft (39) inserted in said bushing (37).

9. Apparatus (10) according to claim 4 or 5, wherein said movement device (33) is configured to translate said first accompanying roller (24a) and said second accompanying roller (24b) with respect to said oscillating arm (27) along a direction parallel to the rotation axis (R1 ) of the first accompanying roller (24a) and parallel to the rotation axis (R2) of the second accompanying roller (24b).

10. Apparatus (10) according to claim 9, wherein said movement device (33) comprises a first slide equipment (40) integral for translations in the axial direction to the first accompanying roller (24a) and slidingly associated in the axial direction with said oscillating arm (27) and a first actuator (45) active on said first slide equipment (40) for axially translating said first slide equipment (40) with respect to said oscillating arm (27).

11. Apparatus (10) according to claim 10, wherein said first slide equipment (40) comprises a first slide (41 ) integral for translations in the axial direction to a firstend of the first accompanying roller (24a) and a second slide (42) integral for translations in the axial direction to a second end of the first accompanying roller (24a); said movement device (33) further comprising a first rail (43) integral with the oscillating arm (27) and slidingly engaged by said first slide (41 ) and a second rail (44) integral with the oscillating arm (27) and slidingly engaged by said second slide (42).

12. Apparatus (10) according to claim 11 , wherein said first slide (41 ) comprises a threaded bushing (47) and wherein said first actuator (45) comprises a threaded bushing (46) engaging said threaded bushing (47), said threaded bushing (46) being rotatable with respect to said oscillating arm (27) and constrained to the oscillating arm (27) for not translating axially with respect to the oscillating arm (27), said threaded bushing (46) being rotated by an electric motor (56) of said movement device (33).

13. Apparatus (10) according to any one of claims 9 to 12, wherein said movement device (33) comprises a second slide equipment (48) integral for translations in the axial direction to the second accompanying roller (24b) and slidingly associated in the axial direction to said oscillating arm (27) and a second actuator (53) active on said second slide equipment (48) for axially translating said second slide equipment (48) with respect to said oscillating arm (27).

14. Apparatus (10) according to claim 13, wherein said second slide equipment (48) comprises a third slide (49) integral for translations in the axial direction to a first end of the second accompanying roller (24b) and a fourth slide (50) integral for translations in the axial direction to a second end of the second accompanying roller (24b); said movement device (33) further comprising a third rail (51 ) integral with the oscillating arm (27) and slidingly engaged by said third slide (49) and a fourth rail (52) integral with the oscillating arm (27) and slidingly engaged by said fourth slide (50).

15. Apparatus (10) according to claim 14, wherein said third slide (49) comprises a threaded bushing (55) and wherein said second actuator (53) comprises a threaded bushing (54) engaging said threaded bushing (55), said threaded bushing (54) being rotatable with respect to said oscillating arm (27) and constrained to the oscillating arm (27) for not translating axially with respect to the oscillating arm (27), said threaded bushing (54) being rotated by an electric motor (56) of said movement device (33).

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