Method and Apparatus for Assembling Electrodes

Abstract

A method for forming electrodes assemblies, used for producing secondary lithium batteries, comprises the steps of feeding two separator strips with continuous feed motions, inserting between the two strips a succession of anodes at reciprocal distances that progressively increase, arranging a succession of cathodes, either all on an outer side of a strip, or alternating a cathode on an outer side of a strip and a cathode on an outer side of the other strip, such that on each single anode a single cathode is superimposed with the interposition of one of the two strips; strips, cathodes and anodes are then laminated together, the laminated product is wound in a single winding direction and the wound product is separated from the rest of the laminated product to enable a subsequent electrodes assembly to be formed.

Claims

1. A method for forming electrodes assemblies, in particular for producing electric energy storage devices, comprising the steps of: feeding a first separator strip (S1) and a second separator strip (S2), each strip being fed with a continuous feed motion, along paths converging in an operative section where said first strip (S1) and said second strip (S2) are superimposed on each other; during said feeding step, inserting a number (N) of electrodes with first polarity (A1, A2, A3, . . . , AN) between said two strips (S1, S2), one after the other at reciprocal distances (D1, D2, . . . ) that progressively increase from the first electrode with first polarity (A1) to the last electrode with first polarity (AN), whereby the distance (D1) between the first and second electrodes with first polarity (A1 and A2) is less than the distance (D2) between the second and third electrodes with first polarity (A2 and A3) which in turn is less than the distance (D3) between the third and fourth electrodes with first polarity (A3 and A4), and so on for all electrodes with first polarity; during said feeding step, arranging a succession of electrodes with second polarity (C1, C2, C3, . . . ), said second polarity being opposed to said first polarity, to form an arrangement of electrodes with second polarity (C1, C2, C3, . . . ), in which the electrodes with second polarity (C1, C2, C3, . . . ) are arranged alternately on an outer side of the first strip (S1) and on an outer side of the second strip (S2) so that an electrode with first polarity in an odd ordinal position (A1, A3, . . . ) is superimposed on an electrode with second polarity (C1, C3, . . . ) with the interposition of the first strip (S1), and an electrode with first polarity in an even ordinal position (A2, A4, . . . ) is superimposed on an electrode with second polarity (C2, C4, . . . ) with the interposition of the second strip (S2).

2. The method according to claim 1, comprising, after said steps of inserting electrodes with first polarity (A1, A2, A3, . . . , AN) and arranging electrodes with second polarity (C1, C2, C3, . . . ), the step of laminating together said first strip, said second strip and said electrodes with first polarity and second polarity to produce a laminated product.

3. The method according to claim 2, comprising the step of winding said laminated product in a single winding direction (F) so as to produce a wound product that comprises a stack of said electrodes with first polarity (A1, A2, A3, . . . , AN) superimposed alternately with said electrodes with second polarity (C1, C2, C3, . . . ) with the alternated interposition of the first strip (S1) and the second strip (S2).

4. The method according to claim 3, comprising the step of separating the wound product from the rest of the laminated product to allow the formation of a subsequent electrodes assembly.

5. The method according to claim 4, wherein said laminating step is performed by means of a laminating device (5), said winding step is performed by means of winding means (6) and said separating step is realized by means of a separating device (7), said separating device (7) being arranged along a continuous working line between said laminating device (5) and said winding means (6).

6. The method according to any one of claims claim 3, wherein each of said electrodes with first polarity (A1, A2, A3, . . . , AN) and second polarity (C1, C2, C3, . . . ) is provided with a tab (T) and wherein said reciprocal distances (D1, D2, D3, . . . ) progressively increase from the first electrode with first polarity (Al) to the last electrode with first polarity (AN) so that in the wound product the tabs (T) of electrodes of the same polarity are superimposed on each other, taking into account the increasing volume of the product during winding.

7. The method according to claim 1, wherein said electrodes with first polarity (A1, A2, A3, . . . , AN) comprise anodes and said electrodes with second polarity (C1, C2, C3, . . . ) comprise cathodes.

8. The method according to claim 1, wherein said number (N) of electrodes with first polarity (A1, A2, A3, . . . , AN) is greater than 2, or greater than 3, or greater than 4, or greater than 5, or greater than 6, or greater than 7, or greater than 8.

9. An apparatus for assembling electrodes, in particular for implementing a method according to claim 1, said apparatus comprising: a first feed path with continuous motion of a first continuous separator strip (S1) and a second feed path with continuous motion of a second continuous separator strip (S2), said paths converging to an operative section where the first strip (S1) and second strip (S2) are superimposed on each other; inserting means (2) for inserting a succession of electrodes with first polarity between the first strip (S1) and the second strip (S2); feeding means (4) for arranging a succession of electrodes with second polarity, one part on an outer side of the first strip (S1) and another part on an outer side of the second strip (S2).

10. The apparatus according to claim 9, wherein said inserting means comprises at least two distinct inserting devices (2) configured to insert electrodes with first polarity (A1, A2, A3, . . . ) with arrangements alternating one with respect to the other.

11. The apparatus according to claim 9, wherein said feeding means comprises at least two distinct feeding devices (4) configured to arrange the electrodes with second polarity (C1, C2, C3, . . . ) with arrangements alternating one with respect to the other.

12. The apparatus according to claim 11, wherein, among said two distinct feeding devices (4), there is a first feeding device (4) arranged to feed electrodes with second polarity (C1, C3, C5, . . . ) on an outer side of the first strip (S1) and there is a second feeding device (4) arranged to feed electrodes with second polarity (C2, C4, C6, . . . ) on an outer side of the second strip (S2).

13. The apparatus according to claim 9, comprising laminating means (5) arranged on said operating section for laminating together the first strip (S1), the second strip (S2), the electrodes with first polarity and the electrodes with second polarity.

14. The apparatus according to claim 13, comprising winding means (6) arranged on said operating section for winding in a single winding direction (F) the laminated product exited by said laminating means (5) and making a wound product.

15. The apparatus according to claim 14, comprising separating means (7) arranged on said operating section between said laminating means (5) and said winding means (6) for separating the wound product from the rest of the laminated product.

16. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The invention can be better understood and implemented with reference to the enclosed drawings that illustrate embodiments thereof by way of non-limiting examples, in which:

[0024] FIG. 1 is a diagram of a first embodiment of an assembly apparatus that is suitable for assembling electrodes for producing electric energy storage devices, according to the present invention;

[0025] FIGS. 2 to 5 show four steps in sequence of a method for forming electrodes assemblies for electric energy storage devices, made according to the present invention using, in particular, the apparatus of FIG. 1;

[0026] FIG. 6 shows a wound product obtained by the assembly method shown in FIGS. 2 to 5;

[0027] FIG. 7 is a diagram of a second embodiment of an assembly apparatus that is suitable for assembling electrodes for producing electric energy storage devices, according to the present invention;

[0028] FIGS. 8 to 11 show four steps in sequence of a method for forming electrodes assemblies for electric energy storage devices, made according to the present invention using, in particular, the apparatus of FIG. 7;

[0029] FIG. 12 is a diagram of a third embodiment of an assembly apparatus that is suitable for assembling electrodes for producing electric energy storage devices, according to the present invention;

[0030] FIGS. 13 and 14 show two embodiments of continuous electrode strips E which are usable in the apparatuses of FIGS. 1 and 7;

[0031] FIG. 15 shows one embodiment of a continuous electrode strip E that is usable in the apparatus of FIG. 12.

DETAILED DESCRIPTION

[0032] For the sake of greater clarity and simplicity, analogous elements of different embodiments have been indicated by the same numbering.

[0033] With 1, overall, an apparatus has been indicated for assembling electrodes for producing electric energy storage devices, in particular for producing cells of secondary lithium batteries.

[0034] The assembly apparatus 1 may comprise, in particular, a first feed path with continuous motion of a first continuous separator strip S1. The assembly apparatus 1 may comprise, in particular, a second feed path with continuous motion of a second continuous separator strip S2. The two paths may converge, as in these embodiments, in an operating portion in which the first strip S1 and the second strip S2 are at least partially superimposed on one another.

[0035] Each of the two paths may comprise, for example, a reel (not shown) for unwinding the respective strip S1 or S2 and/or guiding and sliding means for guiding and sliding the strip (for example support rollers, transmission rollers, etc, which are not illustrated) and/or tensioning means for tensioning the strip (for example tensioning rollers, tightening pulleys, anti-deflection rollers, etc, which are not illustrated), etc. The various elements that make up the two paths of the strips S1 and S2 could also be elements of known type, for which reason they have not been shown and will not be disclosed in greater detail.

[0036] The assembly apparatus 1 may comprise, in particular, inserting means for inserting a succession of at least N electrodes A1, A2, A3, . . . , AN with first polarity between the first strip S1 and the second strip S2. The first polarity may be, as in these embodiments, negative, for the construction of galvanic cells (the electrodes A1, A2, A3, etc, will be anodes).

[0037] The inserting means may comprise, as in the embodiments in FIGS. 1 and 7, two distinct inserting devices 2 that are suitable for inserting the electrodes with a first polarity (anodes) in an alternating manner with respect to one another, so that one of the two inserting devices 2 may be configured for inserting the electrodes in an uneven ordinal position A1, A3, A5, etc, whereas the other of the two inserting devices 2 may be configured for inserting the electrodes in an even ordinal position A2, A4, A6, etc.

[0038] Each inserting device 2 of the electrodes with first polarity may comprise, for example, a feed path of a continuous electrode strip E (for example unwound from a reel, not shown) to feed (with continuous feed motion) the electrode strip E to a cutting device 3 that is suitable for separating single electrodes from the continuous electrode strip E. Each inserting device 2 may be provided with means, for example of known type, for applying the single electrodes, in succession one after the other, between the two separators S1 and S2.

[0039] The assembly apparatus 1 may comprise, in particular, feeding means for arranging a succession of electrodes C1, C2, C3, . . . , C(N−1) with a second polarity, according selectively to two different arrangement modes: either according to a first mode (FIGS. 1 and 12), with all the electrodes C1, C2, etc., arranged on an outer side of the first strip S1, or, according to a second mode (FIG. 7), with a part of electrodes with a second polarity arranged on an outer side of the first strip S1 and another part arranged on an outer side of the second strip S2. The second polarity may be, as in these embodiments, positive, for the construction of galvanic cells (the electrodes C1, C2, C3, etc., cathodes).

[0040] The feeding means may comprise, as in the embodiments in FIGS. 1 and 7, two distinct feeding devices 4 suitable for arranging the electrodes with a second polarity C1, C2, C3, etc., (cathodes) alternatively in relation to one another, so that one of the two feeding devices 4 may be configured for inserting the electrodes in an uneven ordinal position C1, C3, C5, etc, whereas the other of the two feeding devices 4 may be configured for inserting the electrodes in an even ordinal position C2, C4, C6, etc.

[0041] The two distinct feeding devices 4 may be configured, in particular, as in the embodiment in FIG. 7, in which a first feeding device 4 is arranged to feed the electrodes with a second polarity (cathodes) on an outer side of the first strip S1 and a second feeding device 4 is arranged to feed the electrodes with a second polarity on an outer side of the second strip S2.

[0042] Each feeding device 4 of the electrodes with a second polarity may comprise, for example, a feed path of a continuous electrode strip E (for example unwound from a reel, not shown) that feeds (with continuous feed motion) the electrode strip E to a cutting device 3 that is suitable for separating single electrodes from the continuous electrode strip E. Each feeding device 4 may be provided with means, for example of known type, for applying the single electrodes, in succession one after the other, on the two separators 51 and S2, in the aforesaid first or second mode.

[0043] As said, the electrodes with first polarity A1, A2, A3, . . . , AN, may comprise, as in these embodiments, anodes and the electrodes with a second polarity C1, C2, C3, . . . , may comprise cathodes, even if it is possible to provide the opposite.

[0044] The assembly apparatus 1 may comprise, in particular, laminating means arranged on the aforesaid operating portion to couple together, by a laminating process, the first strip S1, the second strip S2, the electrodes A1, A2, A3, . . . , with first polarity (anodes) and the electrodes C1, C2, C3, . . . , with a second polarity (cathodes). This laminating means may comprise, in particular, laminating means of known type, for example one or more pairs of laminating rollers 5.

[0045] The assembly apparatus 1 may comprise, in particular, winding means 6 arranged on the aforesaid operating portion to wind in a single winding direction F the laminated product exiting the laminating means and make a wound product. The winding means 6 may comprise, in particular, winding means 6 of known type, for example means comprising a rotating spindle that rotates a gripping member of the laminated product.

[0046] The assembly apparatus 1 may comprise, in particular, separating means arranged, in particular, on the aforesaid operating portion, for example between the laminating means (rollers 5) and winding means 6, to separate the wound product from the rest of the laminated product and thus form a single electrodes assembly. Such separating means may comprise, in particular, separating means of known type, such as for example at least one cutting device 7 that is suitable for cutting the laminated product during continuous advancement of the laminated product, for example a cutting device 7 provided with a reciprocal forward and backward motion and with tools that adopt a closed cutting position for cutting the laminated product in the outward motion and an open rest position in the return motion to resume the initial position and permit the subsequent cut.

[0047] The assembly apparatus 1 may comprise, in particular, programmable electronic control means for controlling the various actuating means of the apparatus. The assembly apparatus 1 may further comprise sensor means (that is not shown) connected to the control means to control and/or ensure the correct operation of the apparatus 1. Such sensor means may comprise, for example, sensor means of optical type (for example image acquisition means) for checking the quality of the product and/or detecting possible irregularities during the process actuated by the apparatus 1, for example sensor means arranged at the outlet of the laminating means.

[0048] The assembly apparatus 1 according to the invention may be used, in particular, to implement a method for forming electrodes assemblies, in particular for producing electric energy storage devices (for example lithium batteries), which may comprise the operating steps disclosed below.

[0049] The assembly method may comprise, in particular, a step of feeding the first strip S1 of separator and the second strip S2 of separator, each with a continuous feed motion, along paths that converge on the operating portion in which the first strip S1 and the second strip S2 are (at least partially) superimposed on one another to permit coupling thereof.

[0050] The assembly method may comprise, in particular, a step of inserting between the two strips S1 and S2, for example during the aforesaid step of feeding the strips S1 and S2 continuously (i.e. whilst the strips S1 and S2 advance continuously, without interrupting the motion), a number N of electrodes with first polarity A1, A2, A3, . . . , AN, (anodes) one after the other, in order to form at least one first electrodes assembly, in which the reciprocal distances D1, D2, . . . , D(N−1) between the various electrodes A1, A2, A3, . . . , increase progressively from the first electrode with first polarity A1 (first anode of the electrodes assembly) to the last electrode with first polarity AN (last anode of the electrodes assembly).

[0051] In particular, the assembly apparatus 1 may be so programmed that the distance D1 between the first and the second electrode with first polarity A1 and A2 is less than the distance D2 between the second and the third electrode with first polarity A2 and A3 which will in turn be less than the distance D3 between the third and fourth electrode with first polarity A3 and A4, and so on until the last pairs of electrodes, so that the distance D(N−2) between the antepenultimate and penultimate electrode with first polarity A(N−2) and A(N−1) will be less than the distance D(N−1) between the penultimate and the last electrode with first polarity A(N−1) and A(N), before restarting with another arrangement of electrodes A1, A2, A3, etc., to form the next electrodes assembly (in symbols we will have D1<D2<D3<<D(N−2)<D(N−1), with N>2, or N>3, or N>4, or N>5, or N>6, or N>7, or N>8).

[0052] The assembly method may comprise, in particular, a step of arranging a succession of electrodes with a second polarity C1, C2, C3, . . . , (cathodes) in particular during the aforesaid step of feeding the strips S1 and S2 continuously, in which the second polarity is opposite the first polarity, to form, selectively, a first or a second arrangement of electrodes with a second polarity C1, C2, C3, etc.

[0053] In the case of the first arrangement (FIGS. 1 and 12 and FIGS. 2 to 5), the electrodes with a second polarity C1, C2, C3, . . . , are so arranged on an outer side of the first strip S1 that on each electrode with first polarity A1, A2, A3, . . . , AN a single electrode with a second polarity C1, C2, C3, is superimposed . . . , with the interposing of the first strip S1, except for the first or second electrode with first polarity A1 or A2 (in the specific embodiment the second electrode A2 with first polarity), at which no electrode with a second polarity is superimposed, but an empty space is left.

[0054] In the case of the second arrangement (FIG. 7 and FIGS. 8 to 11), the electrodes with a second polarity C1, C2, C3, . . . , are arranged alternatingly on an outer side of the first strip S1 and on an outer side of the second strip S2, such that on each electrode with first polarity in an uneven ordinal position A1, A3, . . . , a single electrode with a second polarity C1, C3, . . . is interposed, with the interposing of the first strip S1, and such that on electrodes with first polarity in an even ordinal position A2, A4, . . . , a single electrode with a second polarity C2, C4, . . . is interposed, with the interposing of the second strip S2. It is in particular possible to ensure that at the last or penultimate electrode with first polarity AN or A(N−1) an empty space is left, so that at the end of the winding an electrode assembly is obtained that comprises two electrodes of the same polarity (A1 and AN) at the two opposite ends, at the first and last place. In the specific embodiment (in which the number N is even) an empty space has been left, without superimposing any electrode at the last electrode A8; in the case of an uneven number N, an empty space could be left, without superimposing any electrode, at the penultimate electrode A(N−1).

[0055] The assembly method may comprise, in particular, after the aforesaid steps of inserting electrodes with first polarity A1, A2, A3, . . . , AN and arranging electrodes with a second polarity C1, C2, C3, . . . , a step of laminating together the first strip S1, the second strip S2 and the electrodes with first polarity A1, A2, etc., and with a second polarity C1, C2, etc., for making a laminated product.

[0056] The assembly method may comprise, in particular, a step of winding the laminated product in a single winding direction F so as to make a wound product that comprises a stack of electrodes with first polarity A1, A2, A3, . . . , AN that are alternatingly superimposed with electrodes with a second polarity C1, C2, C3, . . . , with alternating interposing of the first strip S1 and of the second strip S2.

[0057] The assembly method may comprise, in particular, a step of separating the wound product from the rest of the laminated product to enable a subsequent electrodes assembly to be formed.

[0058] For every single electrodes assembly, the number N of electrodes with first polarity A1, A2, A3, . . . , AN may be a number greater than 2, or greater than 3, or greater than 4, or greater than 5, or greater than 6, or greater than 7, or greater than 8. In the specific embodiments illustrated here, the number N is equal to 8.

[0059] For each single electrodes assembly, the total number of electrodes with a second polarity C1, C2, etc., may be the same as N−1, in such a manner that in the wound end product the most external electrodes (the first and last of the stack) are electrodes A1 and A8 of the same polarity (first polarity, in particular negative).

[0060] Each electrode with first polarity A1, A2, A3, . . . , AN and with a second polarity C1, C2, C3 is provided with a tab T.

[0061] The aforesaid reciprocal distances D1, D2, D3, , increase progressively from the first electrode with first polarity A1 to the last electrode with first polarity AN (and/or, likewise, between the electrodes with a second polarity) so that in the wound product the tabs T of electrodes of the same polarity are superimposed on one another precisely, taking account of the increase in volume of the product during winding. The aforesaid reciprocal distances have been taken with reference to the electrodes con first polarity (anodes), but could also be taken with reference to the electrodes with a second polarity (cathodes), without this substantially changing anything, as the absolute distances could be different, as the electrodes with first polarity (anodes) are normally slightly wider than the electrodes with a second polarity (cathodes), but the increases of the distances between the various pairs of electrodes would substantially remain the same.

[0062] In the specific embodiments illustrated, in which the tabs T are situated on one side of the electrodes with a non-central but eccentric arrangement (to the right or the left of the centre line or centre of the electrode), the electrodes of the same polarity with an odd ordinal position (for example A1, A3, A5, etc.) will have the tabs with the same eccentric arrangement (to the right or the left), whereas the electrodes of the same polarity with an even ordinal position (for example A2, A4, A6, etc.) will have tabs with the opposite eccentric arrangement (to the left or right).

[0063] In FIGS. 13 and 14, two embodiments of electrode strips E are illustrated which are usable in the apparatuses of FIGS. 1 and 7 for each of the two inserting devices 2, in which the tabs T of each electrode strip E are arranged with a constant pitch, in such a manner that each continuous electrode strip E can be cut to obtain electrodes with the tabs T having the same eccentric arrangement (to the right or the left). With dashed lines, the future cutting lines are indicated at which the various cutting devices 3 will separate the single electrodes from the strips A.

[0064] In FIG. 15, one embodiment of electrode strip E is illustrated that is usable in the apparatus of FIG. 12 for the single inserting device 2, in which the tabs T of the electrode strip E are arranged with a non-constant pitch, but in an alternating manner, such that the continuous electrode strip E can be cut to obtain electrodes with the tabs T having the eccentric arrangements in an alternating manner (an electrode with eccentric arrangement of the tab T to the right and the subsequent electrode with eccentric arrangement of the tab T to the left, then the right, and so on).

[0065] The programmable electronic control means of the assembly apparatus may be programmed so as to cause the aforesaid distances D1, D2, etc., in function of at least one datum relating to at least one dimension (in particular the thickness) of the first strip S1 and/or the second strip S2 and/or the electrodes with first polarity A1, A2, etc., and/or the electrodes with a second polarity C1, C2, etc. This datum/these data is/are entered into the memory of the control means and are then used by a processor to determine the aforesaid distances D1, D2, etc.

[0066] The aforesaid laminating step may be performed by the laminating device (rollers 5); the aforesaid winding step may be performed by the winding means 6; the aforesaid separating step may be performed by the separating device (cutting device 7); the separating device may be arranged, as in the specific embodiments disclosed here, along a continuous processing line between the laminating device and the winding means.

[0067] FIG. 6 shows one embodiment of an electrodes assembly that is makeable according to the method and/or the assembly apparatus of the invention. This assembly comprises a stack of electrodes (cathodes and anodes), at least five, or at least seven, or at least nine, or at least eleven, or at least thirteen electrodes in number (in the specific embodiment fifteen electrodes), which are superimposed on one another, with opposite alternating polarities to one another, and further comprising two continuous strips S1 and S2 of separator that are wound in a single winding direction and separate the electrodes from one another. Each strip S1 and S2 has a first winding start end in the innermost part of the stack and a second winding finish end outside the stack.