Apparatus for z-folding separators and method for making electrode-separator arrangements

Abstract

The invention relates to a device (10) for folding strip-shaped separators (1) extending in a longitudinal direction (x) into a z-shape for the electrode-separator arrangement of individual battery cells. The device according to the invention is characterized by two pressers (3) for clamping the separator (1) at its both ends in the longitudinal direction (x), and a mounting tool (5) arranged between the two pressers (3), the mounting tools (5) having the same distance from each other in the longitudinal direction (x), having bars (6) in a transverse direction (y) extending transversely to the longitudinal direction (x), and being attached to be movable in the longitudinal direction of a rail (4) extending along the longitudinal direction (1), the rail (4) being formed movable in a height direction (z) transverse to the longitudinal direction (x) and transverse to the transverse direction (y), the bars (6) being arranged alternately above and below the clamping position of the separator (1) in the height direction (z) when viewed in the longitudinal direction (x). According to a first method, the separator (1) is folded, followed by the provision of electrodes, whereby an electrode-separator arrangement is produced. Alternatively, a blank can be made from the separator (1) and the electrodes (2) laminated thereto, which is then folded correspondingly into a z-shape using the device (10).

Description

[Technical field]

[0001] The invention relates to an apparatus for z-folding longitudinally extending separator strips for electrode-separator arrangements of individual battery cells, and furthermore to two different methods for producing stacked electrode-separator arrangements using an apparatus of this kind. [Background technology]

[0002] The production of electrode-separator arrangements is widely known from the general prior art. In fact, three manufacturing methods have been established, which are described, for example, in Non-Patent Document 1. This document essentially describes the stacking of individual separator sheets and electrodes, as well as the rolling of electrodes and separators. Another method is the so-called z-folding, which is generally called "z-folding". For this, seamless separators are used, on which one electrode is placed, and then the separator is folded back or folded back on the electrode, followed by the next sheet-like electrode, which in turn has the other polarity. The separator is then folded back again, the next electrode is placed, and the process is repeated. In this case, the separator must be continuously supplied as roll material and moved back and forth accordingly. The advantage of stacking or z-folding is that, unlike rolling, no curvature of the electrodes takes place, which can be a decisive advantage, especially in solid-state batteries. The advantage of winding is that it allows for very high production speeds that cannot be achieved by the continuous process of stacking and Z-folding.

[0003] US Patent No. 5,399,633 describes a method substantially as mentioned at the outset, in which separators for individual battery cells, in which the electrodes are stacked, are folded via a movable bar to form a stack of z-folded electrodes for the battery cell.

[0004] Furthermore, US Pat. No. 5,399,633 describes a similar process for forming electrodes and separators into a z-folded electrode stack configuration. Another method of this kind is basically known from US Pat. No. 5,399,633. Finally, reference is made to US Pat. No. 5,399,633, which also addresses this subject and essentially discloses a device for folding an electrode stack into an f-shape. Both methods have in common that the bar used for the z-folding must be removed again from the stacked or folded material, which is relatively complicated. For this reason, in the prior art, lateral pulling is shown and described, for example in the above-mentioned US Pat. No. 5,399,633, and also in the above-mentioned US Pat. No. 5,399,633. This is problematic whenever the electrodes and separators are brought together but not yet fixed, since in that case the electrodes can slip in the stack, which leads to defective production. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2003-243270 [Patent Document 2] Patent Publication No. 2009-140776 [Patent Document 3] DE 102018200958 [Patent Document 4] Patent Publication No. 2012-033275 [Non-patent literature]

[0006] [Non-Patent Document 1] Literature “Process and Performance Optimization by Selective Assembly of Battery Electrodes”, Jan Schmitt et al., CIRP Annals-Manufacturing Technology 63 (2014)9-12 Summary of the Invention [Problem to be solved by the invention]

[0007] It is therefore an object of the present invention to provide an apparatus for z-folding a separator that allows for high production speeds, as well as a suitable method for producing an electrode-separator arrangement. [Means for solving the problem]

[0008] According to the invention, this problem is solved by an apparatus with the features of claim 1, here in particular the characterizing part of claim 1. Advantageous configurations and developments of the apparatus according to the invention emerge from the claims dependent on claim 1. The solution with regard to the method is shown in the method of claim 5 as well as in the alternative method of claim 6.

[0009] The device according to the invention is thus used for folding longitudinally extending strip-shaped separators into a Z-shape for the electrode-separator arrangement of individual battery cells. The device comprises two pressers designed to clamp a separator, adjusted to a length suitable for the method, at both ends in the longitudinal direction. Between the two pressers, fixtures are arranged, which comprise bars that are at the same distance from each other in the longitudinal direction and extend in a transverse direction to the longitudinal direction. The fixtures are accommodated in rails in the longitudinal direction and are movable from them in the longitudinal direction. The rails themselves are movable in a height direction transverse to both the longitudinal and transverse directions, i.e. the rails can be moved away from each other or towards each other. The individual bars are located in the height direction, alternating above and below the clamping position of the separator, as viewed in the longitudinal direction. That is, when the separator is clamped between the pushers, one bar is located above the separator and the other bar is located below the separator, alternating with the other bar. Now, when the rails move away from each other, the fixture connected to the rails exerts a corresponding force on the bars, so that the separator is pulled downward by half of the bars and pulled upward by the other half of the bars. In this case, the positions of the two pushers also change to approach each other, because the separator now forms a strip folded in a z-shape, and therefore the separator is correspondingly shorter when considered only in the longitudinal direction. At the end position of the pushers and the rails, the rails have moved as far away from each other as possible, and the pushers have moved as close to each other as possible, so that a bundle of separators folded in a z-shape is located between the pushers.

[0010] Here, according to the invention, the bar is adapted to be heatable and / or a cutting device is provided for cutting the separator in the region of the bar where the pushers are moved to the closest position to one another.

[0011] In one variant, the bars are also constructed to be heatable as well. This is particularly important for stackable separators, which can be stacked into a unit by means of a heated press. For other separators this is also possible in principle.

[0012] In the finished final product, the bars are undesirable. They can be heated so that they can be removed from the separator, for example by heating the bar and then moving the rail beyond its end position, which melts the separator in the area of ​​the fold and pulls the bar out of the separator in a direction transverse to the direction of movement through the molten material. At the same time, the melted parts are then melted together by the corresponding application of pressure from the presser, helping to fasten the unit instead of or as a complement to the heated presser.

[0013] Alternatively or complementary to this, a cutting device can also be provided for cutting the separator in the region of the bar at the position where the pressers have been moved in the direction of maximum approach to each other. Such a cutting device serves to remove the bar accordingly, complementary or alternative to the use of a heated bar. Here, the cutting can be performed mechanically, for example via a knife, rolling cutter, etc., or a laser can be used for the cutting. These techniques are particularly suitable when non-laminable separators are used, in which the material cannot be melted and / or cut via heat without damage.

[0014] According to a very advantageous development of the device according to the invention, the length of the bar in the transverse direction is now designed to be greater than the width of the separator, such a wide bar improving the folding quality and allowing, for example, a configuration of the fixtures in which the fixtures hold the bar at both ends in the transverse direction, so that a uniform tensile force can be applied to the separator via the bar when the rails are moved away from each other.

[0015] According to another very advantageous configuration of the device according to the invention, the presser can be designed to be heatable, so that the separators can be laminated by heating, in particular after the pressers have been butted together in their end position, so that the separators are melted accordingly, so that individual regions of the separator are joined together and so that a fixed unit is formed of the separator and, typically, the previously installed electrodes.

[0016] In order to adjust the procedure of the device accordingly and to be able to fold the separator in a Z-shape in this device, according to a very advantageous configuration of the device according to the invention, the device can have a control for adjusting the movement of the pushers and the rails, which control is in particular set up to move the rails away from each other as described above and to move the pushers towards each other in order to fold the separator, said movements being carried out by corresponding adjustment of the rails and the pushers.

[0017] In the method according to the invention for producing an electrode-separator arrangement in the form of a stack for individual battery cells with continuous separators, in one method step the electrodes are stacked on the separators, where on each longitudinal side of the separator the electrodes are each followed by a free section having at least the length of the electrode. This allows for an alternating arrangement of electrodes and free sections in the longitudinal direction of the separator, so that after folding, a layer of the separator on which the electrodes are stacked is located on one side of the electrode and another layer with a free section is folded over the electrode. In this case, moreover, on each side of the separator, electrodes of the same polarity are arranged, for example anodes on the top and cathodes on the bottom. Electrodes of different polarity are located at least partially opposite each other on each side. In this context, "at least partially" means, for example, that the number of anodes differs from the number of cathodes, so that only one of the electrodes is present in one of the end regions of the separator in order to complete the folding. After such a semi-finished product has been produced from the separator and the stacked electrodes, in a second method step this semi-finished product is folded in a Z-shape in one of the above-mentioned configurations by moving the rails and the presses to their end positions as already suggested, resulting in an electrode-separator arrangement which is formed with a Z-folded separator.

[0018] According to another method according to the invention, the stacking of the electrodes can also be omitted, for example, when non-stackable separators are used. In this case, in a first method step, the separator is pre-folded in the device according to the above-mentioned configuration, by moving the rail and the pusher in the direction of the respective end position, but stopping before reaching the respective end position. In this case, the separator is folded in a z-shape, but is present with relatively large open pockets, which are respectively oriented upwards and downwards or respectively oriented to the side, depending on the arrangement of the device. Then, for example, all electrodes are inserted simultaneously into the corresponding pockets, or in two consecutive steps, first all anodes and then all cathodes are inserted into the corresponding pockets, for example the cathodes from below and the anodes from above, or in a rotated arrangement the cathodes are inserted from the left and the anodes from the right accordingly. Then, in a third method step, the rail and the pusher are moved to the respective end positions. Here too, a corresponding z-folded electrode-separator arrangement results without prior preparation of semi-finished products from the electrodes and separators.

[0019] In both methods according to the invention, it is basically possible to use a separator that can be stacked. In this case, in a further method step, the device can be fixed to a unit at the end of the press, and for this purpose, in a corresponding configuration, the press can be heated in the above-mentioned sense, so that the separator is stacked to produce a unit. Alternatively, other methods for fixing to a unit can also be applied, for example, adhesive can be injected from the side of a laterally open z-fold. In particular, adhesive tape can be used for fixing, if the separator is not to be stacked or fused.

[0020] According to the invention, if such a fixed unit is present, the separator is separated in the region of the bar of said fixed unit, whereby the bar is removed from the unit, which can be done in the sense described above, for example by cutting with mechanical means or a laser, or by the bar being heated and the rails of the device being moved away from each other beyond the end position, so that the bar is drawn through the molten material of the separator.

[0021] Further highly advantageous configurations of the device according to the invention as well as of the method according to the invention emerge from the exemplary embodiments which are described in more detail below with reference to the drawings. [Brief description of the drawings]

[0022] [Figure 1] 1 shows a side view of a device according to the invention in a starting position; [Diagram 2] FIG. 2 shows a front view taken along line II-II in FIG. [Diagram 3] 2 shows the pusher and rail in an intermediate position, as in FIG. 1 . [Figure 4] FIG. 4 shows a front view taken along line IV-IV in FIG. [Diagram 5] 2 shows the end position of the pusher and rail, shown similarly to FIG. 1; [Figure 6] 6 shows a front view taken along line VI-VI in FIG. 5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Based on the following figures, the procedure for producing a z-folded electrode-separator arrangement will be described using as an example a separator 1 on which electrodes 2 are stacked, as can be seen in FIG. 1. Here, the separator 1 is clamped between two presses 3 in the longitudinal direction x. Here, a first electrode 2, for example an anode 2.1, is arranged on one surface of the separator 1 located on the upper side in the height direction z, and a cathode 2.2 is arranged on the lower side. Between the electrodes, there are always empty sections of the separator 1, which have at least the length of the electrode 2 arranged next to them in the longitudinal direction x. Here, only the anode 2.1 is arranged in the section shown on the far right, and the cathode 2.2 is omitted.

[0024] In addition to the side view in FIG. 2, this structure can also be seen correspondingly in the front view shown in FIG. 2 along the line II-II in FIG. 1. Here too, a separator 1 can be seen, which has an anode 2.1 on the upper side in the height direction z and a cathode 2.2 on the lower side in the height direction z. Here, in the longitudinal direction x, two rails extend above and below the separator 1, on which, as also shown in FIG. 1, a number of fixtures 5 are arranged, only two of which are numbered. As can be seen from FIG. 2, the fixtures 5 can be attached laterally to the rails in the transverse direction y. The fixtures 5 can be moved in the longitudinal direction x relative to the rails 4. Here, the fixtures 5 themselves have bars 6, which extend in the transverse direction y and are particularly visible in FIG. 2. As can be seen in particular from FIG. 1, these bars 6 are always arranged alternately above and below the separator 1 in the height direction z and are always arranged in the boundary region between the area with electrodes 2 and the section without electrodes.

[0025] The z-folding of the separator 1 to obtain the desired electrode-separator arrangement is initiated on the one hand by the movement of the pressers 3 towards each other, for which the presser 3 shown on the left in each of the figures shown here moves towards the right. At the same time, the two rails 4 move away from each other, whereby a tensile force is applied to the separator at the corresponding points via the fixtures 5 and the bars 6. After this movement of the device, generally designated 10, has been initiated, it is in the position shown in figures 3 and 4, which are shown similarly to figures 1 and 2. Here again, from the view of the left presser 3 shown in figure 4, one of the electrodes is shown on the separator 1, here the anode 2.1. To perform an accordion-like z-folding of the separator 1, the rails 4 and thus the bars connected to them via the fixtures 5 move up and down away from each other. Each individual fixture 5 moves in the longitudinal direction x towards the right presser 3, whereby the desired arrangement of the separator 1 is obtained.

[0026] This manner of the rails 4 being pulled away from each other and the presses 3 moving towards each other continues accordingly until the end position of the presses 3 and rails 4 shown in FIG. 5 is reached. The presses 3 clamp the electrode-separator arrangement between them and can, for example, be heated to result in a unit consisting of the separator 1 and the electrode 2 in the stackable separator 1. Finally, the bar 6 is removed from the unit, for example in the region of the bar 6, which can be separated, in particular mechanically by a knife or preferably by heating the bar 6. The heated bar is pulled out of the unit by moving the rail 4 beyond its end position. The molten separators can then be brought together again and the unit can be closed accordingly tightly.

[0027] The alternative embodiment mentioned at the beginning, in which the electrodes 2 are not laminated to the separator 1, would require that the movement of the pusher 3 and the rail 4 would be stopped accordingly in an intermediate position of the device 10 between the two positions shown in Figs. 3 and 5 in order to insert the electrodes into the pockets, for example all the electrodes 2 at the same time or in each figure first the anode 2.1 from above and then the cathode 2.2 from below. It would then move to the end position shown in Fig. 5. Instead of melting or heating the separator 1 to form a unit, here a lateral gluing of the separator ends could take place, for example by glue, adhesive tape, etc. It would then also be possible here to remove the bar 6, for example by cutting the separator 1, and then to reapply the same, for example by means of an adhesive tape.

Claims

1. A device (10) for folding a strip-shaped separator (1) extending in a longitudinal direction (x) into a z-shape for an electrode-separator arrangement of an individual battery cell, comprising: two pressing tools (3) for holding the separator (1) at both ends in the longitudinal direction (x); In the device (10), a mounting tool (5) is provided between the two pressing tools (3), the mounting tool (5) has bars (6) in a transverse direction (y) that are at the same distance from each other in the longitudinal direction (x) and extend in a direction transverse to the longitudinal direction (x), a rail (4) is formed that is movable in a height direction (z) that transverses the longitudinal direction (x) and the transverse direction (y), and the bars (6) are alternately arranged above and below the clamping position of the separator (1) in the height direction (z) when viewed in the longitudinal direction (x), The device (10), characterized in that the mounting fixture (5) is mounted on a rail (4) extending in the longitudinal direction (x) so as to be movable along the longitudinal direction (1), and the bar (6) is configured to be heatable and / or a cutting device is provided for cutting the separator (1) in the area of ​​the bar (6) at a position where the pushers (3) are moved to a position where they are maximally close to each other.

2. 2. The device (10) according to claim 1, characterized in that the length of the bar (6) in the transverse direction (y) is made greater than the width of the separator (1) in the transverse direction (y).

3. 3. The device (10) according to claim 1 or 2, characterized in that the pressing tool (3) is heatable.

4. 4. The device (10) according to claim 1, 2 or 3, characterized by a control for adjusting the movement of the pushers (3) and the rails (4), the control being set in particular to move the rails (4) away from each other and to move the pushers (3) towards each other in order to fold the separator (1).

5. A method for producing an electrode-separator arrangement in stack form for individual battery cells with a continuous separator (1), comprising: in a first method step, electrodes (2) are laminated onto the separator (1), such that on each side of the separator (1) in the longitudinal direction (x), the electrodes (2) are each followed by a vacant section having at least the length of the electrodes (2), and on each side of the separator (1) electrodes of the same polarity are arranged, the electrodes of different polarities being at least partially opposite each other on each side, In a subsequent second method step, the semi-finished product consisting of the separator (1) and the electrodes (2) laminated thereon is folded in a Z-shape in the device (10) according to any one of claims 1 to 6 by the rails (4) and the presses (3) being moved to their respective end positions, In a further subsequent method step, the stacked electrode-separator arrangement is fixed in the end position of the press (3) to form a unit, The method, characterized in that, in the fixed unit, the separator (1) is separated in the region of the bar (6) in order to remove the bar (6) from the unit.

6. A method for producing an electrode-separator arrangement in stack form for individual battery cells with a continuous separator (1), comprising: In a first method step, the separator (1) is pre-folded in a z-shape in the device (10) according to any one of claims 1 to 6 by the rail (4) and the pusher (3) which are moved in the direction of the respective end position and stopped before reaching the respective end position, In a subsequent second method step, electrodes (2) of one polarity are simultaneously inserted into the pockets of the Z-folded separator (1) from one side and the electrodes (2) of the other polarity are simultaneously inserted into the pockets of the Z-folded separator (1) from the other side, or multiple electrodes (2) of different polarities are simultaneously inserted into the pockets of the Z-folded separator (1) from both sides, In a subsequent third method step, the rail (4) and the pusher (3) are moved to their respective end positions, In a further subsequent method step, the stacked electrode-separator arrangement is fixed in the end position of the press (3) to form a unit, The method, characterized in that, in the fixed unit, the separator (1) is separated in the region of the bar (6) in order to remove the bar (6) from the unit.

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