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

Abstract

A stacking apparatus (1) comprises a stacking station (20); a first transfer device (10) for transferring first electrode precursors (100) and a second transfer device (13) for transferring second electrode precursors (101) movable between a pick-up position and a release position placed at the 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); 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). The feeder device (21) comprises a first separator guide (29) and a second separator guide (30) placed above the accompanying device (24) and respectively comprising a first contact surface (31) and a second contact surface (32), configured to contact the continuous strip-shaped separator (102) during its unwinding, rotatable around their own rotation axes (R3, R4) parallel to each other, wherein at least one of the first contact surface (31) and the second contact surface (32) is movable along its own rotation axis (R3, R4) between a first 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 separator unwinder which is fed by a continuous separator reel is also mounted on the movable frame. The 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 away a gripping equipment that has just deposited an electrode precursor in the stacking station, the accompanying rollers translate integrally with the movable frame above the electrode precursor just deposited in the stacking station and position the separator above the electrode precursor 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 continuous 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 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] The need is increasingly felt, particularly in the industrial sector of the production of electric accumulators, to be able to have stacking apparatuses for alternately stacking a continuous strip-shaped 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 separator exactly above the electrode precursor just deposited in the stacking station.

[0011] The Applicant has in fact observed that the separator strip 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 separator strip and the rotation axis of the accompanying rollers, or, in combination, could be the effect of free oscillations of the section of separator strip 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 separator deposition step, requiring the stacking apparatus to stop when the alienation error exceeds tolerance limits in the stacking accuracy of the various separator layers.

[0013] 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.

[0014] The Applicant has thought of providing contact surfaces, which roll around axes parallel to the axes of the accompanying rollers, placed between the reel of separator strip and the accompanying rollers and which contact the separator strip, in such a way as to decrease the free oscillation length of the separator strip.

[0015] The Applicant observed that this measure, although it seemingly decreases the alignment error, is not sufficient to achieve the desired result.

[0016] The Applicant has therefore perceived that it could be made an attempt to compensate for a possible alignment error by moving the separator strip parallel to the rotation axes of the accompanying rollers during the operation of the stacking apparatus.

[0017] The Applicant has found that by making one of such contact surfaces movable between a plurality of stable positions and parallel to the rotation axis of the contact surface, a possible alignment error could be compensated for by moving the contact surface and with it the separator, so as not to have to stop the stacking apparatus to correct the alignment error and therefore increase the production speed of electrochemical cells.

[0018] The present invention therefore concerns a stacking apparatus for alternately stacking a continuous strip-shaped separator and electrode precursors.

[0019] Preferably, there is provided a stacking station configured to receive electrode precursors.

[0020] Preferably, there are provided a first transfer device for transferring first electrode precursors and a second transfer device for transferring second electrode precursors.

[0021] Preferably, the first transfer device and the second transfer device are 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. Preferably, there is provided a feeder device of a continuous strip-shaped separator configured to feed a continuous strip-shaped separator towards the stacking station.

[0022] Preferably, there is provided an accompanying device configured to operate on the continuous and strip-shaped separator and movable between a first end position and a second end position above the stacking station.

[0023] Preferably, the feeder device comprises a first separator guide and a second separator guide positioned above the accompanying device.

[0024] Preferably, the first separator guide and the second separator guide respectively comprise a first contact surface and a second contact surface configured to contact the continuous strip-shaped separator during its unwinding.

[0025] Preferably, the first contact surface and the second contact surface guide are rotatable about their own mutually parallel rotation axes.

[0026] Preferably, said first contact surface is movable along its rotation axis between a first plurality of stable axial positions and said second contact surface is movable along its rotation axis between a second plurality of stable axial positions.

[0027] The Applicant has verified that the continuous strip-shaped separator, engaged by the accompanying device moving between the first end position and the second end position to position the continuous strip-shaped separator on the stacking station, may tend to be axially misaligned with respect to the optimal axial position of interposition between the first electrode precursors and the second electrode precursors.

[0028] The Applicant has verified that by moving axially and holding stably in an axial position reached the first contact surface or in combination the second contact surface of the first separator guide and of the second separator guide, the continuous strip-shaped separator also moves axially and reaches the accompanying device in a different axial position. By setting the axial displacement of the first contact surface and / or the second contact surface in such a way as to compensate for the ongoing axial misalignment on the accompanying device, it is possible to compensate for this axial misalignment and correctly position the continuous strip-shaped separator between the first electrode precursors and the second electrode precursors. The Applicant has further verified that the continuous strip-shaped separator can be axially displaced from the first contact surface and from the second contact surface when the continuous strip-shaped separator exerts a contact pressure on these contact surfaces. Such contact pressure generates friction between the continuous strip-shaped separator and the contact surface that allows axial displacement of the continuous strip-shaped separator when the contact surface is axially displaced. Since the contact pressure that the continuous strip-shaped separator exerted on the first contact surface and on the second contact surface varies during the movement of the accompanying device, making both the first contact surface and the second contact surface axially movable along their rotation axes, it is possible to axially move the contact surface on which the greater contact pressure is exerted at a given instant.

[0029] "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.

[0030] "Continuous 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.

[0031] By "axial or axially" is meant a direction parallel to the rotation axis of the first contact surface of the first separator guide and parallel to the second contact surface of the second separator guide.

[0032] The present invention may have, in one or both of its aspects, 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.

[0033] Preferably, the accompanying device is configured to lay the continuous stripshaped separator on the stacking station.

[0034] 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. Preferably, the continuous strip-shaped separator is fed by a continuous reel of strip-shaped separator towards the feeder device.

[0035] Preferably, the continuous strip-shaped separator passes through the feeder device passing between the first separator guide and the second separator guide such that the rotation axes of the first contact surface and the second contact surface face opposite surfaces of the continuous strip-shaped separator.

[0036] Preferably, the rotation axis of the first contact surface is spaced from the rotation axis of the second contact surface such that the continuous strip-shaped separator is always in contact with at least one of the first contact surface and the second contact surface.

[0037] Preferably, said rotation axes of the first contact surface and of the second contact surface lie in a plane substantially parallel to a plane parallel to the stacking surface of said stacking station.

[0038] In this way, the first separator guide and the second separator guide direct the continuous strip-shaped separator towards the accompanying device in such a way that the stresses internal to the continuous strip-shaped separator (caused by the accompanying action of the accompanying device) are evenly distributed in axial direction.

[0039] The Applicant considers that this makes it possible to prevent or in any case reduce the axial misalignment of the continuous strip-shaped separator.

[0040] Preferably, there is provided a first movement device configured to move said first contact surface between said first plurality of stable axial positions.

[0041] Preferably, said first movement device is configured to axially lock said first contact surface in any axial position of said first plurality of stable axial positions.

[0042] Preferably, said first plurality of stable axial positions is comprised between a first axial end position and a second axial end position.

[0043] Preferably, the movement of the accompanying device between the first end position and the second end position results in a contact between said continuous strip-shaped separator and said second contact surface of the second separator guide and wherein the movement of the accompanying device between the second end position and the first end position results in a contact between said continuous strip-shaped separator and said first contact surface of the first separator guide.

[0044] Preferably, there is provided a second movement device configured to move said second contact surface between said second plurality of stable axial positions.

[0045] Preferably, said second movement device is configured to axially lock said second contact surface in any axial position of said second plurality of stable axial positions.

[0046] Preferably, said second plurality of stable axial positions is comprised between a first axial end position and a second axial end position.

[0047] Preferably, each stable axial position of the first plurality of stable axial positions corresponds to a stable axial position of the second plurality of stable axial positions.

[0048] Preferably, said first movement device is operable independently of said second movement device.

[0049] In this way, it is possible both to axially move both the first contact surface and the second contact surface by the same amount or by different amounts, and to axially move only the first contact surface, and to axially move only the second contact surface.

[0050] Preferably, said first separator guide is a first roller wherein a radially outer cylindrical surface of said first roller defines said first contact surface.

[0051] Preferably, said first roller is an idle roller.

[0052] Preferably, the first movement device axially moves only said first roller along said rotation axis of the first contact surface.

[0053] Preferably, said second separator guide is a second roller wherein a radially outer cylindrical surface of said second roller defines said second contact surface.

[0054] Preferably, said second roller is an idle roller.

[0055] Preferably, the second movement device axially moves only said second roller along said rotation axis of the second contact surface.

[0056] Preferably, said first movement device comprises a rail slidingly associated with a slide along an axial direction. Preferably, said slide is fixed and said rail slides in said slide.

[0057] Preferably, said first roller is rotatably coupled to said rail to slide axially with respect to the slide.

[0058] Preferably, the rotation axis of said first roller is parallel to said rail.

[0059] Preferably, said first movement device further comprises an actuator connected to said rail for moving said rail in an axial direction along said slide.

[0060] Preferably, said actuator comprises an electric motor having an outlet shaft connected to a worm screw.

[0061] Preferably, said worm screw is rotatably coupled to a slider integral with said rail, such that a rotation of the worm screw causes a translation of said slider.

[0062] Preferably, said second movement device comprises a rail slidingly associated with a slide along an axial direction.

[0063] Preferably, said slide is fixed and said rail slides in said slide.

[0064] Preferably, said second roller is rotatably coupled to said rail to slide axially with respect to the slide.

[0065] Preferably, the rotation axis of said second roller is parallel to said rail.

[0066] Preferably, said second movement device further comprises an actuator connected to said rail for moving said rail in an axial direction along said slide.

[0067] Preferably, said actuator comprises an electric motor having an outlet shaft connected to a worm screw.

[0068] Preferably, said worm screw is rotatably coupled to a slider integral with said rail, such that a rotation of the worm screw causes a translation of said slider.

[0069] Preferably, when said accompanying device is placed in an intermediate position between the first and the second end position, the accompanying device is placed below the vertical of the first separator guide and the second separator guide.

[0070] Preferably, the accompanying device moves between the second end position and the first end position and above the stacking station when the first transfer device moves from the release position to the pick-up position. Preferably, the accompanying device moves between the first end position and the second end position and above the stacking station when the second transfer device moves from the release position to the pick-up position.

[0071] Preferably, for displacing the accompanying device above the stacking station, the stacking apparatus comprises a displacement device.

[0072] Preferably, said displacement device comprises an oscillating arm driven by an actuation shaft and supporting said accompanying device.

[0073] Preferably, said actuation shaft is placed, with respect to said stacking station, on the opposite side with respect to said feeder device of a continuous strip-shaped separator.

[0074] 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.

[0075] 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.

[0076] Preferably, the accompanying device is supported at a first end of said oscillating arm.

[0077] Preferably, the actuation shaft is connected to the oscillating arm in a distal position with respect to the accompanying device.

[0078] Preferably, the actuation shaft is connected to a second end, opposite to the first, of the oscillating arm.

[0079] Preferably, the stacking station comprises a substantially flat stacking surface.

[0080] Preferably said stacking surface lies in a plane parallel to the actuation shaft.

[0081] Preferably, when said accompanying device is placed in an intermediate position between the first and second end position, the accompanying device is, along a direction perpendicular to the stacking surface, interposed between the stacking surface and the (first and second) separator guides.

[0082] Preferably, when said accompanying device is placed in an intermediate position between the first and second end positions, the accompanying device is placed at a greater level with respect to the stacking surface.

[0083] Preferably, when said accompanying device is placed in the first end position, the accompanying device is at a lower level than the stacking surface.

[0084] Preferably, when said accompanying device is placed in the second end position, the accompanying device is placed at a lower level than the stacking surface.

[0085] Preferably, said intermediate position between the first and the second end position is substantially equally spaced from the first end position and from the second end position.

[0086] Preferably, when displacing the accompanying device above the stacking station, the continuous strip-shaped separator is stretched above an electrode precursor that has just been transferred to the stacking station.

[0087] Preferably, in the first end position the accompanying device is placed at a first distance from the stacking surface.

[0088] Preferably, in the second end position the accompanying device is placed at a second distance from the stacking surface.

[0089] Preferably, in an intermediate position between the first and the second end position the accompanying device is placed at a third distance from the stacking surface.

[0090] Preferably, said intermediate position is placed at an apex point of the curved path travelled by the accompanying device.

[0091] Preferably, said third distance is greater than the first distance and greater than the second distance.

[0092] Preferably, the first distance is substantially equal to the second distance.

[0093] The Applicant considers that by providing the first distance and the second distance less than the third distance, the continuous strip-shaped separator can easily adhere to the cell being formed, and in particular to the just deposited electrode precursor, without the need to subject the continuous strip-shaped separator to actions that may cause excessive stretching of the continuous stripshaped separator. Preferably, said accompanying device comprises a first accompanying roller having an outer surface configured to contact the continuous strip-shaped separator.

[0094] Preferably, said accompanying device comprises a second accompanying roller having an outer surface configured to contact the continuous strip-shaped separator.

[0095] Preferably, the first accompanying roller and the second accompanying roller are counter-rotating to each other.

[0096] Preferably, the first accompanying roller and the second accompanying roller comprise, respectively, a rotation axis.

[0097] Preferably, the rotation axis of the first accompanying roller is parallel to the rotation axis of the second accompanying roller.

[0098] 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.

[0099] 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 continuous strip-shaped separator.

[0100] 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.

[0101] 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.

[0102] The Applicant considers that in this way the first accompanying roller and the second accompanying roller are able to accompany the continuous strip-shaped separator between the first end position and the second end position without inducing unwanted tensions, or in any case generating few tensions, in the continuous strip-shaped separator, allowing high deposition speeds of the continuous strip-shaped separator on the cell being formed.

[0103] Preferably, said outer surface of the first accompanying roller rolls without creeping with respect to the continuous strip-shaped separator.

[0104] Preferably, said outer surface of the second accompanying roller rolls without creeping with respect to the continuous strip-shaped separator.

[0105] 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: figures 1 to 3 are schematic views of a stacking apparatus for alternately stacking a continuous strip-shaped separator and electrode precursors in accordance with the present invention under different operating conditions; figure 4 is a perspective schematic view of a feeding device of the stacking apparatus in figure 1 ; figure 5 is a schematic sectional view along the plane V-V of the feeding device of figure 4; figure 6 is a schematic sectional view along the plane VI-VI of the feeding device of figure 4; figures 7A and 7B are schematic perspective views of some components of the feeding device of figure 4; and figure 8 is a schematic perspective view of some components of the stacking apparatus of figure 1 .

[0106] 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.

[0107] 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.

[0108] The apparatus 10 comprises a support frame 11 on which the various components of the apparatus 10 are mounted. 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.

[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 (figure 2) 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 3).

[0114] The first transfer device 12 is movable between a pick-up position (illustrated in figures 1 and 2) and a release position (illustrated in figure 3). 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 (illustrated in figure 3) and a release position (illustrated in figures 1 and 2). 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 to 3, 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 sheet plate 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 to 3, the apparatus 10 further comprises 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.

[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] A rotating support 22 receives a reel 103 of continuous strip-shaped separator 102. From the reel 103 mounted on the rotating support 22, the continuous stripshaped separator 102 is continuously unwound and fed towards the stacking station 20. The apparatus 10 comprises a displacement device 23 configured to operate on the continuous strip-shaped separator 102 fed by the feeder device 21. 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 continuous stripshaped 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.

[0122] The continuous 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.

[0123] The resulting electrochemical cell is of the "bag" or "prismatic" type. Unlike cylindrical winding batteries, the 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 continuous strip-shaped separator 102 is evenly zigzag-like stacked around the anode (e.g. the first electrode precursors 100) and the cathode (e.g. the second electrode precursors 101 ).

[0124] The displacement device 23 comprises a mobile accompanying device 24 with alternating motion between a first end position P1 (figure 1 ) and a second end position P2 (figure 3). 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.

[0125] As better illustrated in figure 8, the accompanying device 24 comprises, in the preferred embodiment of the invention, a first accompanying roller 24a configured to contact the continuous 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 continuous 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.

[0126] 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 continuous stripshaped separator 102. In other words, the continuous 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 continuous 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 .

[0127] 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 continuous strip-shaped separator 102 capable of unwinding the latter from its reel mounted on the rotating support 22. 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 continuous stripshaped 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.

[0128] 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 continuous 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 continuous strip-shaped separator 102.

[0129] As illustrated in figure 8, 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.

[0130] Between the rotating support 22 for the reel 103 of continuous strip-shaped separator 102 and the accompanying device 24 there is placed the feeder device 21 , as schematically illustrated in figures 2 and 3.

[0131] The feeder device 21 receives the continuous strip-shaped separator 102 from the reel 103 and directs it towards the accompanying device 24. The feeder device 21 is fixed with respect to the rotating support 22 and with respect to the support frame 1 1 . The feeder device 21 is traversed by a plane perpendicular to the stacking surface 20a and passing through the space separating the first accompanying roller 24a and the second accompanying roller 24b when the accompanying device 24 is placed in an intermediate position between the first end position R1 and the second end position P2.

[0132] The feeder device 21 comprises a first separator guide 29 and a second separator guide 30 through which the continuous strip-shaped separator 102 passes, as schematically illustrated in figure 4. The first separator guide 29 comprises a first contact surface 31 configured to contact the continuous stripshaped separator 102 and the second separator guide 30 comprises a second contact surface 32 configured to contact the continuous strip-shaped separator 102. The first contact surface 31 rotates about its own rotation axis R3 driven in rotation by the continuous strip-shaped separator 102. The second contact surface 32 rotates about its own rotation axis R4 driven in rotation by the continuous strip-shaped separator 102. The rotation axes R3, R4 of the first contact surface 31 and the second contact surface 32 are parallel to each other. The rotation axes R3, R4 of the first contact surface 31 and the second contact surface 32 are parallel to the rotation axes R1 , R2 of the first accompanying roller 24a and the second accompanying roller 24b.

[0133] In the preferred embodiment of the invention, the first separator guide 29 is made by a first roller 33 whose radially outer cylindrical surface 34 defines the first contact surface 31 . Similarly, the second separator guide 30 is made by a second roller 35 whose radially outer cylindrical surface 36 defines the second contact surface 32.

[0134] The rotation axis R3 of the first roller 33 is spaced from the rotation axis R4 of the second roller 35 by a distance that is substantially equal to the sum of the radii of the first roller 33 and the second roller 35 and the thickness of the continuous strip-shaped separator 102. In other words, the continuous strip-shaped separator passes between the first roller 33 and the second roller 35 without being crushed between those two rollers. The continuous strip-shaped separator 102 is inserted between the first roller 33 and the second roller 35 and is preferably in contact with both the radially outer cylindrical surface 34 of the first roller 33 and the radially outer cylindrical surface 36 of the second roller 35. The rotation axis R3 of the first roller 33 and the rotation axis R4 of the second roller 35 always remain at the same mutual distance.

[0135] The first roller 33 is idle. The first roller 33 is mounted on a support structure 37 comprising a pair of forks 38 on which the first roller 33 is rotatably mounted, as illustrated in figure 7A. The second roller 35 is idle. The second roller 35 is mounted on a support structure 39 comprising a pair of forks 40 on which the second roller 35 is rotatably mounted, as illustrated in figure 7B. The support structure 37 for the first roller 33 is symmetrical with respect to the support structure 39 for the second roller 35, such that the first roller 33 is directly facing the second roller 35.

[0136] A first movement device 41 acts on the first roller 33 to displace it axially along a direction parallel to the rotation axis R3 of the first roller 33. The first movement device 41 axially moves the first roller 33 between a plurality of stable axial positions, i.e. axial positions that are maintained by the first roller 33.

[0137] As illustrated in figure 5, the first movement device 41 comprises an actuator 42 made by an electric motor 43 fixed to a plate 44 fixed with respect to the support frame 11 . The electric motor 43 comprises a rotating outlet shaft 43a to which a worm screw 45 is connected. The worm screw 45 is parallel to the rotation axis R3 of the first roller 33 and is inserted into an internally threaded slider 46 stably connected to the support structure 37, as schematically illustrated in figure 5. The first movement device 41 further comprises a rail 47 mounted on the support structure 37. The rail 47 is straight and parallel to the rotation axis R3 of the first roller 33. The first movement device 41 further comprises a slide 48 made fixed to the plate 44 on which the electric motor 43 is mounted. The rail 47 is slidably coupled to the slide 48 in such a way that the support structure 37 and with it the first roller 33 can translate axially along the slide 48. The rotation of the outlet shaft 43a of the electric motor 43 causes a rotation of the worm screw 45 which, by screwing or unscrewing in the slider 46, causes an axial displacement of the slider 46. The slider 46, being integral with the support structure 37, results in an axial translation of the support structure 37 and therefore of the first roller 33. The rail 47 and the slide 48 accompany the axial translation of the support structure 37.

[0138] A second movement device 49 acts on the second roller 35 to displace it axially along a direction parallel to the rotation axis R4 of the second roller 35. The second movement device 49 axially moves the second roller 35 between a plurality of stable axial positions, i.e. axial positions that are maintained by the second roller 35.

[0139] The second movement device 49 is independent of the first movement device 41 such that the first roller 33 and the second roller 35 can be axially translated independently of each other.

[0140] Structurally, the second movement device 49 is identical to the first movement device 41 .

[0141] In particular (as illustrated in figure 6), the second movement device 49 comprises an actuator 50 made by an electric motor 51 fixed to the plate 44. The electric motor 51 comprises a rotating outlet shaft 51 a to which a worm screw 52 is connected. The worm screw 52 is parallel to the rotation axis R4 of the second roller 35 and is inserted into an internally threaded slider 53 stably connected to the support structure 39, as schematically illustrated in figure 6. The second movement device 49 further comprises a rail 54 mounted on the support structure 39. The rail 54 is straight and parallel to the rotation axis R4 of the second roller 35. The second movement device 49 further comprises a slide 55 made fixed to the plate 44 on which the electric motor 51 is mounted. The rail 54 is slidably coupled to the slide 55 in such a way that the support structure 39 and with it the second roller 35 can translate axially along the slide 55. The rotation of the outlet shaft 51 a of the electric motor 51 causes a rotation of the worm screw 52 which, by screwing or unscrewing in the slider 53, causes an axial displacement of the slider 53. The slider 53, being integral with the support structure 39, results in an axial translation of the support structure 39 and therefore of the second roller 35. The rail 54 and the slide 55 accompany the axial translation of the support structure 39.

[0142] In the preferred embodiment of the invention, the slide 48 of the first movement device 41 and the slide 55 of the second movement device 49 are mounted on a common support element 56. The support element 56 is mounted on the plate 44. The support element 56 comprises a through opening 57 to allow the passage of the continuous strip-shaped separator 102, as schematically illustrated in figure 4.

[0143] In use, in order to alternately stack the continuous strip-shaped separator 102 and the electrode precursors 100, 101 , the first electrode precursors 100 and the second electrode precursors 101 are transferred to the stacking station 20 in an alternating manner, i.e. one at a time and with a succession providing for an alternation between the first electrode precursors 100 and the second electrode precursors 101 .

[0144] The continuous strip-shaped separator 102 is fed to the stacking station 20 by passing through the feeder device 21. The continuous strip-shaped separator 102 passes between the first separator guide 29 and the second separator guide 30. The first contact surface 31 and the second contact surface 32 are in contact with the two opposite surfaces of the continuous strip-shaped separator 102 and are rotated by the latter. The first contact surface 31 and the second contact surface 32 rotate in opposite directions to each other. The continuous stripshaped separator 102 then reaches the accompanying device 24 being engaged by the same.

[0145] Starting from a situation in which a second electrode precursor 101 has just been deposited, the continuous strip-shaped separator 102 is engaged by the first accompanying roller 24a to displace the continuous strip-shaped separator 102 above the stacking station 20 between the first end position P1 and the second end position P2. The continuous strip-shaped separator 102 is then placed on the second electrode precursor 101 . The second electrode precursor 101 is then partially wound by the continuous strip-shaped separator 102.

[0146] Subsequently, a first electrode precursor 100 is deposited in the stacking station 20 above a portion of continuous strip-shaped separator 102 just lied on the second electrode precursor 101. Subsequently, the accompanying device 24 reverses its motion to pass between the second end position P2 and the first end position P1 .

[0147] The continuous strip-shaped separator 102 is engaged by the second accompanying roller 24b to displace the continuous strip-shaped separator 102 above the stacking station 20 between the second end position P2 and the first end position P1. The continuous strip-shaped separator 102 is then placed on the first electrode precursor 100. The first electrode precursor 100 is then partially wound by the continuous strip-shaped separator 102.

[0148] The described process is repeated until the electrochemical cell is formed.

[0149] If during deposition of the continuous strip-shaped separator 102 above the first electrode precursor 100 or the second electrode precursor 101 the continuous strip-shaped separator 102 is axially misaligned, the first separator guide 29, or in combination the second separator guide 30, is axially translated to a new stable axial position. To axially translate the first separator guide 29, the electric motor 43 is driven. The rotation of the outlet shaft 43a of the electric motor 43 causes a rotation of the worm screw 45 which, by screwing or unscrewing in the slider 46, causes an axial displacement of the slider 46. The slider 46 causes an axial translation of the support structure 37 and therefore of the first separator guide 29. To axially translate the second separator guide 30, the electric motor 51 is driven. The rotation of the outlet shaft 51 a of the electric motor 51 causes a rotation of the worm screw 52 which, by screwing or unscrewing in the slider 53, causes an axial displacement of the slider 53. The slider 53 causes an axial translation of the support structure 39 and then of the second separator guide 30.

[0150] Since the continuous strip-shaped separator 102 is in direct contact with the first contact surface 31 of the first separator guide 29, or in combination, with the second contact surface 32 of the second separator guide 30, the axial translation of the first separator guide 29, or in combination, of the second separator guide 30 moves the continuous strip-shaped separator 102 axially, translating it axially.

[0151] The driving time of the electric motor 43 or the electric motor 51 is a function of the axial displacement of the continuous strip-shaped separator 102 to be obtained. Once the continuous strip-shaped separator 102 is axially realigned in the stacking station 20 above the first electrode precursor 100 or the second electrode precursor 101 , the electric motor 43 and the electric motor 51 are stopped.

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); an accompanying device (24) configured to operate on the continuous stripshaped separator (102) and movable between a first end position (P1 ) and a second end position (P2) above the stacking station (20); wherein the feeder device (21 ) comprises a first separator guide (29) and a second separator guide (30) placed above the accompanying device (24) and respectively comprising a first contact surface (31 ) and a second contact surface (32), configured to contact the continuous strip-shaped separator (102) during its unwinding, rotatable around their own rotation axes (R3, R4) parallel to each other, wherein said first contact surface (31 ) is movable along its own rotation axis (R3) between a first plurality of stable axial positions and said second contact surface (32) is movable along its own rotation axis (R4) between a second plurality of stable axial positions.

2. Apparatus (10) according to claim 1 , wherein said rotation axes (R3, R4) of the first contact surface (31 ) and of the second contact surface (32) lie in a plane substantially parallel to a plane parallel to the stacking surface (20a) of said stacking station (20).

3. Apparatus (10) according to claim 1 or 2, comprising a first movement device (41 ) configured to move said first contact surface (31 ) between said first plurality of stable axial positions.

4. Apparatus (10) according to claim 3, wherein said first movement device (41 ) is configured to axially lock said first contact surface (31 ) in any axial position of said first plurality of stable axial positions.

5. Apparatus (10) according to claim 4, comprising a second movement device (49) configured to move said second contact surface (32) between said second plurality of stable axial positions.

6. Apparatus (10) according to claim 5, wherein said second movement device (49) is configured to axially lock said second contact surface (32) in any axial position of said second plurality of stable axial positions.

7. Apparatus (10) according to claims 4 and 5, wherein said first movement device (41 ) is operable independently of said second movement device (49).

8. Apparatus (10) according to any one of the preceding claims, wherein the movement of the accompanying device (24) between the first end position (P1 ) and the second end position (P2) results in a contact between said continuous strip-shaped separator (102) and said second contact surface (32) of the second separator guide (30), and wherein the movement of the accompanying device (24) between the second end position (P2) and said first end position (P1 ) results in a contact between said continuous strip-shaped separator (102) and said first contact surface (31 ) of the first separator guide (29).

9. Apparatus (10) according to any one of the preceding claims, wherein said first separator guide (29) is a first roller (33) wherein a radially outer cylindrical surface (34) of said first roller (33) defines said first contact surface (31 ) and wherein said second separator guide (30) is a second roller (35) wherein a radially outer cylindrical surface (36) of said second roller (35) defines said second contact surface (32).

10. Apparatus (10) according to claims 3 and 9, wherein said first movement device (41 ) comprises a rail (47) slidingly associated with a slide (48) along an axial direction and an actuator (42) connected to said rail (47) for moving said rail (47) in an axial direction along said slide (48); said first roller (33) being rotatably coupled to said rail (47).11 . Apparatus (10) according to claims 5 and 9, wherein said second movement device (49) comprises a rail (54) slidingly associated with a slide (55) along an axial direction and an actuator (50) connected to said rail (54) for moving said rail (54) in an axial direction along said slide (55); said second roller (35) being rotatably coupled to said rail (54).

12. Apparatus (10) according to any one of the preceding claims, wherein when said accompanying device (24) is placed in an intermediate position between the first and second end positions (P1 , P2), the accompanying device (24) is below the vertical of the first separator guide (29) and the second separator guide (30).

Images