WO2015135775A1

WO2015135775A1 - Serially connected combination of cells, in particular for a redox flow storage system, and method for production thereof

Info

Publication number: WO2015135775A1
Application number: PCT/EP2015/054239
Authority: WO
Inventors: Michael Geisler
Original assignee: Schmid Energy Systems Gmbh
Priority date: 2014-03-12
Filing date: 2015-03-02
Publication date: 2015-09-17
Also published as: DE102014103286B4; DE102014103286A1

Abstract

The invention relates to a method for producing a serially connected combination (10) of cells (13, 15), comprising a membrane (14) and electrodes (16, 17) arranged on both sides of the membrane (14) which combination is closed on both sides by a plastic wall (11, 12) and is sealed on the longitudinal edges. The entire combination (10) is produced from five individual webs in a reel-to-reel process.

Description

A series-connected composite of cells, especially for one

Redox flow storage system, and method for its production

The invention relates to a series-connected composite of cells with a membrane and disposed on both sides of the membrane electrodes, which is completed on both sides in each case by a plastic wall and is sealed at the longitudinal edges. Such a composite is particularly suitable for the production of redox flow storage systems. The invention further relates to a method for producing such a composite.

Redox flow batteries or redox flow storage systems are based on the principle that two electrolytes flow through the half-cells of an electrochemical cell and thereby change their oxidation state on the surface of the electrodes. The emitted or absorbed in the half-cell reactions electrons over an external circuit work. The circuit is closed by an ion-conductive separating layer or membrane, which ensures the charge balance between the two half-cells. To make larger units, a whole series of cells must be connected in series.

In the prior art (see, for example, WO 201 1/075135 A1), in this case the individual cells are interconnected via bipolar plates which are arranged between adjacent cells.

The use of bipolar plates for interconnecting the cells is complex and increases the total resistance of the cell network. In addition, it is difficult to produce a larger composite in a simple and inexpensive manner, since the individual cells and the bipolar plates each have to be connected to each other so as to produce a cell stack.

Although it is generally known to use a roll-to-roll process for the production of a membrane electrode assembly for a fuel cell (cf. WO 2007/1 10397 A1), it is not apparent how such a process for the production a series-connected composite of cells with a membrane and arranged on both sides of the membrane electrodes, which is completed on both sides in each case by a plastic wall, can be transmitted.

Against this background, the present invention seeks to provide a serially interconnected composite according to the type mentioned, which can be produced in a simple and cost-effective manner, and to provide a manufacturing method for producing such a composite, which is applicable on a large scale.

This object is achieved by a method for producing a series-connected composite of cells with a membrane and arranged on both sides of the membrane electrodes, which is completed on both sides in each case by a plastic wall and sealed at the longitudinal edges wherein the process is carried out in a roll-to-roll process comprising the steps of: a) providing tape-shaped electrode material for a first and a second belt-shaped electrode; b) providing band-shaped plastic material for a first and a second cell wall web and punching out marginal service holes at both edges of each cell wall panel; c) providing band-shaped material for an ion-conducting membrane web and pretreating the membrane web on selected lines in the transverse direction and at both edges in the longitudinal direction; d) merging a first cell wall track followed by a first cell wall track

Electrode trajectory, the membrane web, a second electrode web and a second cell wall web in a roll-to-roll process and edge-side bonding of the webs by local melting at the two edges; e) local melting of the composite produced in step (d) along the previously pretreated lines in the transverse direction; f) separating the composite by a subtractive process on selected lines in the transverse direction alternately on one side and the other side between adjacent melting zones from the step (e) for creating trenches that electrically interrupt the respective electrode on a membrane side.

The object of the invention is completely solved in this way. According to the invention, the entire composite can be produced in a roll-to-roll process, which ensures a simple and cost-effective production and also high safety, that the composite produced in this way is also sufficiently sealed when it is in the operation of electrolytes, that is, by an anolyte and a catholyte, flows through.

In a composite produced in this way, the serial interconnection of the adjacent cells is ensured by the band-shaped electrodes which pass through adjacent cells and are densified in a fluid-tight manner between adjacent cells by the production method. By separating the electrodes by a subtractive method according to step (f) alternately on one side and on the other side, the desired serial connection is ensured.

In a preferred embodiment of the invention, the resulting in step (f) trenches are sealed immediately after their production with plastic.

In this way results in a high integrity and mechanical resistance of the composite.

According to a further embodiment of the invention, the electrodes in step (a) made of porous graphite material, in particular one or more layers of graphite paper, produced on the several longitudinally over the entire length extending metal strip, preferably copper strip, at certain intervals be applied to a surface, preferably non-adherently attached or soldered at certain points.

In an additional embodiment of this embodiment are applied over the metal strip plastic strip of greater width than the metal strip, preferably applied by Kunststoffklebepunkte, also on the opposite side of plastic strip aligned with the plastic strip on the first page, preferably by Kunststoffklebepunkte, and then the plastic strip both Sides of the graphite material melted by hot rolling into the surface of the graphite material.

In this way, the graphite electrodes are electrically connected to well-conducting current collector strips and they are reliably protected from chemical attack by the electrolyte solution.

According to a further embodiment of the invention is applied to the membrane at the predetermined locations at which later in step (f) the separation of the electrodes in the transverse direction, in each case a protective strip of plastic on the release side facing surface.

In this way it is prevented that the running on the opposite side of the electrode or the current collector strip extending thereon is only injured by the subsequent separation step.

The separation of the electrodes at the predetermined locations can be done by a mechanical cutting or sawing method, such as by means of a cutting roller, or about by a laser cutting process.

In a preferred embodiment of the invention is used as a plastic material for all plastic parts polypropylene or optionally polyethylene, wherein the plastic material is preferably free from plasticizer.

Also in the plastic material for closing the trenches is preferably polyethylene, which is pressed or injected into the trenches, expediently at elevated temperature, so that a sufficient flowability is given.

According to a further embodiment of the invention, electrolytic supply lines are connected to the supply holes punched out in step (b), preferably by matching the electrolyte connection pieces accurately via the assigned Supply holes are placed at predetermined locations and welded to the surrounding surface of the cell wall web, preferably by mirror welding.

In this way, a clean and even at high hydraulic pressure sufficiently tight connection of the electrolyte supply lines is ensured. For mirror welding, the parts to be joined are first brought to a certain distance from each other and then heated locally by an introduced heated metal plate, so that after removal of the metal plate, the relevant parts can be welded together under pressure.

[0023] In accordance with another embodiment of the invention, a group of supply holes is connected to an electrolyte fitting connected to an electrolyte main lead using at least four main electrolyte leads, one main electrolyte lead for the anolyte supply and the catholyte supply, and one main electrolyte lead for each the Anolytabfuhr and the catholyte discharge, which are connected to the associated cells of the composite each via a voltage reduction path.

In this way, the hydraulic supply of the composite with catholyte and anolyte can be ensured in a suitable manner to produce a composite with high efficiency, which is particularly suitable for a redox flow battery, in particular for a vanadium redox flow battery (VRFB).

According to a further embodiment of the invention, the voltage reduction sections are each made by wrapping the respective electrolyte main line with a hose, with which the relevant electrolyte main line is connected to the associated electrolyte connection piece.

In this way, results in a particularly simple production of the voltage reduction sections, which in the prior art usually as meandering were trained in closed rooms. With the method according to the invention results in a significant simplification.

The electrolyte fittings are preferably made by injection molding, preferably polypropylene or polyethylene.

In this way, results in a simple and inexpensive production.

According to a further embodiment of the invention, a membrane web is used, which is narrower than the cell wall webs, preferably narrower by about 5 to 15 mm, and which is preferably made of a modified PTFE film, in particular of a modified with perfluorosulfonic PTFE Foil.

In this way, the membrane web can be enclosed and integrated directly when connecting the various webs between the plastic webs, without the need for further steps are necessary. The modified PTFE material used has proven to be particularly advantageous for a highly effective membrane.

In order to ensure a good adhesion of the membrane in the integration into the two plastic sheets at the edges and a good adhesion in the production of transversely extending Einschmelzzonen, the pretreatment of the membrane web is preferably carried out in step (c) by oxidation in an oxidation bath at the predetermined locations.

For this purpose, the membrane web for the oxidation of the longitudinal edges in step (c) suspended in the longitudinal direction and are immersed with two longitudinal edges in the oxidation bath with a predetermined depth.

Furthermore, the membrane web for oxidation in the transverse direction in step (c) between the upper and lower pulleys are hung zig-zag-shaped and are immersed in the oxidation bath at a predetermined immersion depth of preferably 5 to 10 mm, are advanced after treatment and are immersed in the next section until all the selected lines have been oxidized in the transverse direction.

As the oxidation bath, for example, sodium can be used dissolved in ammonia.

By such an oxidation treatment can be a good adhesion in the subsequent application of plastic, in particular of polypropylene, to ensure the membrane web.

A series-connected composite of cells produced by the method described above has a membrane web and electrode webs arranged on both sides of the membrane web, the composite being closed on both sides in each case by a continuous plastic cell wall web over its entire length, and which is sealed at the longitudinal edges by a connection of the two cell wall webs, wherein the serial interconnection is formed by continuous electrode tracks which are electrically alternately in the transverse direction on one side and the other at each (n) -th and each (n + 1) - th cell are interrupted.

Such a series-connected composite of cells preferably each has a group of supply holes on the cells, which are connected to an electrolyte fitting, which is connected to an electrolyte main line, wherein at least four electrolyte main lines are provided, one main electrolyte line for anolyte supply and the Katholytzufuhr and in each case an electrolyte main line for the Anolytabfuhr and Katholytabfuhr, which are connected to the associated cells of the composite each via a voltage reduction path.

Preferably, the voltage reduction sections are each formed by at least one winding of a hose around at least one main electrolyte line. In this way, a highly effective composite of serially interconnected cells, wherein the hydraulic connections are ensured in a simple and cost-effective manner.

It is understood that the features of the invention mentioned above and those yet to be explained can be used not only in the respectively specified combination but also in other combinations or alone, without departing from the scope of the present invention.

Further features and advantages of the invention will become apparent from the following description of preferred embodiments with reference to the drawings. Show it:

1 shows a cross section through an inventive composite of cells connected in series with one another;

FIG. 2 shows a plan view of the composite according to FIG. 1 from above; FIG.

3 is a plan view of the membrane web after treatment in the oxidation bath.

4 is a plan view of an electrode web in an enlarged view;

5 shows a cross section through the electrode web according to FIG. 4;

Fig. 6 is a schematic view showing the treatment of the membrane sheet in an oxidation bath in the transverse direction;

Fig. 7 is a schematic view showing the longitudinal treatment of the membrane sheet in an oxidation bath; Fig. 8 is a perspective view of the composite of FIG. 1, which is additionally provided with the hydraulic supply and

9 is an enlarged partial section through an electrolyte fitting according to

Fig. 8.

In Fig. 1, an inventive composite is shown in cross-section and generally designated by the numeral 10.

The composite 10 comprises a plurality of anodic half cells 13 and cathodic half cells 15, which are connected in series via integrated electrode tracks 16, 17 with each other. The anodic half cells 13 and the cathodic half cells 15 are separated by a membrane web 14, which runs in the middle of the composite 10. On one side of the membrane web 14 runs parallel to a first electrode web 16 and again parallel to a first cell wall web 1 1, through which the composite is closed to the outside. On the other side of the membrane web 14 extends a second electrode web 17 and in turn parallel to a second cell wall web 12, through which the composite 10 is completed on this side to the outside.

The first electrode track 16 and the second electrode track 17 run through in the longitudinal direction of the composite 10 and are alternately electrically separated from one another on the one side and on the other side by a trench 24 which is filled with an electrically insulating filler strip 26 , In this way, a composite interconnected in series 10, wherein the current flow, which is indicated by the arrows 28, once between the cathodic half-cell 15 and the anodic half-cell 13 through the membrane 14 therethrough, then over the first electrode web 16 into the next, reversely poled half-cell, then again through the membrane 14 passes through etc.

The anodic half cells 13 and the cathodic half cells 15 are in each case alternately on one side and on the other side of the composite 10. The electrodes 16, 17, which consist of porous graphite material, run continuously through the cell walls between adjacent cells, which are each produced by insulating Einschmelzzonen 18. The Einschmelzzonen 18 are each disposed on both sides of a trench 24 and separate the adjacent cells fluid-tight from each other. The porous electrode material is in this case sealed fluid-tight by the melting process.

On the side of the membrane 14 associated with the respective trench, a protective strip 22 made of polyethylene is attached in each case, by means of which the opposite electrode web 16 or 17 is protected from injury during the subsequent separation process.

Each cell 13, 15 has at the edge side according to FIG. 2, a plurality of supply holes 20, through which a flow with an anolyte or a catholyte in operation is made possible.

In the following, the preparation of the composite 10 will be explained in more detail.

4 shows a plan view of the first electrode track 16 in an enlarged view from above.

As the electrode material, one or more layers of graphite paper 34 having a total thickness of about 0.5 to 1.2 mm as shown in FIG. 5 are used.

Then, as a current collector 16, two or more metal strips 36 of copper are first applied to individual points by means of polypropylene over the entire length of the electrode web 16 or fastened by means of a soldering process. In each case, a plastic strip 37 made of polypropylene is applied, which covers the metal strip 36 laterally. On the opposite side of the graphite paper 34, a complementary plastic strip 38 is applied. Longitudinal edges on the graphite paper web 34 of a certain width remain free. By hot rolling the plastic strips 37, 38 are melted at their edges in the graphite paper 34. The temperature is hereby initiated especially on the line where the plastic strip over the associated metal strip 36 protrude. As a result, the copper strips 36 are fixed in a fluid-tight manner on the graphite paper 34. During reflow, it is ensured by a suitable adjustment of the roll temperature and the duration that the graphite paper 34 is not soaked with plastic where it is to come into electrical contact with the metal strip 36.

For the production of the cell wall webs 1 1, 12 band-shaped polypropylene is used, in which according to FIG. 2 at the two longitudinal edges supply holes 20 are punched in groups of, for example, four adjacent supply holes. The supply holes 20 thereby form groups whose first and last holes are separated from one another by distances which are greater than the distances between holes 20 of the same group. The centerlines between two adjacent pit holes groups define the so-called cell period.

For the preparation of the membrane web 14, a modified PTFE film is used, for example, a PTFE film modified with perfluorosulfonic acid. For example, for this purpose, the membrane film from the company Fumatech (BWT Group) can be used, which is sold under the name Fumatec 450. This is an anion conductor that blocks cations. Of course, cation-conducting and anion-blocking films may also be used.

The membrane strip material is about 8 mm narrower than the strip material from which the cell wall webs 1 1, 12 are produced. On the surfaces which are later to be connected to the respective other cell wall web and at which the Einschmelzzonen be generated in the transverse direction 18, the membrane material is superficially oxidized, such as by treatment in a solution of sodium and ammonia.

For this purpose, the membrane web 14 is bent egg-shaped in FIG. 7 in the longitudinal direction and suspended over a roller 50, so that the two longitudinal edges of the membrane web 14 dip into the oxidation bath 42. The immersion depth r ₂ defines the width of the treatment zone. Subsequently, the membrane web according to FIG. 6 is suspended on a frame, with a lower frame 44 with lower deflection rollers 48 and with an upper frame 46 with upper deflection rollers 47. The membrane web 14 thus becomes zig-zag-shaped between the upper deflection rollers 47 and the lower pulleys 48 held. The membrane web 14 is now immersed in the oxidation bath 42 with the immersion depth r-ι so as to generate the oxidation regions in the transverse direction. After sufficient treatment time, the membrane web 14 is moved out first by moving the two frames 44, 46 from the oxidation bath 42 and then moved in the direction of arrows 49 until the next treatment zones abut the lower deflection rollers 48. Then again a treatment by lowering into the oxidation bath 42 to the depth r-ι. The entire process is repeated until the entire membrane web 14 is treated at the selected locations.

On one side of the membrane sheet 14 is then along transverse to the film direction lines corresponding to the center line between each (2n) -th and (2n + 1) -th group of holes, an approximately 1 mm thicker, approx 1 mm wide, over the entire membrane web width reaching protective strips 22 made of polypropylene tacked. The thickness (perpendicular to the electrode plane) of these protective strips 22 depends on the precision with which the subsequent separation process for separating the electrodes is carried out.

On the other side of the membrane sheet 14, along lines perpendicular to the web direction, which correspond to the center line between each (2 + 1) th and (2n) -th hole group, an approx. 1 mm thicker, approx. 1 mm wide, over the entire width of the web extending protective strip 22 made of polypropylene stapled. The thickness in turn depends on the precision of the subsequent separation process.

Subsequently, the so-called cell wedding takes place. In this case, two outer cell wall webs 11, 12, a central membrane web 14 and the two electrode webs 16, 17 are brought together to form a so-called cell web. For this purpose, material is combined by five roles, counting from top to bottom, the first cell wall web 1 1, a first equipped with current collectors electrode track 16, wherein the metal strips 36 are oriented upwards, the pretreated membrane web 14, the second electrode web 17, with the metal strips 36 oriented downwards, and finally a second cell wall track 12. In this case, the cell wall webs 1 1, 12 are displaced relative to one another in such a way that the aforementioned protective strips 22 are offset in the transverse direction by one cell period, cf. FIG. 1. The groups of the supply holes 20 of the first and second cell wall webs 1 1, 12 are aligned with each other.

[0060] The five webs are melted together by hot rolling. The melting process takes place only at the longitudinal edges of the cell wall webs 1 1, 12, and over a width, which detects the membrane 14 and the electrode edges 16, 17 with. Here, the Einschmelzzonen 39, 40 used in FIG. 5.

In addition, the fusing operation is carried out everywhere between two adjacent cell periods to 1 to 3 mm apart, transverse in the film transverse direction lines centered around the center line between the supply holes groups, so that the aforementioned Einschmelzzonen 18 arise.

Subsequently, by a linear acting ablative method (for example a laser-assisted method or a method with a cutting roller) on the top and bottom of the composite 10 thus formed along the lines 24 as shown in FIG. 1 trenched 24 trenches 24, which shown in FIG 1 just enough so deep that the there extending electrode tracks 16, 17 (in particular the metal strips 36) are separated. By the previously applied protective strip 22 is prevented in this case that is cut through the membrane 14 through (thickness only a few tenths of a millimeter) in the opposite electrode web. The respective trenches 24 occupy a significantly smaller proportion of the width of the melter zones 18 running there. Immediately after these trenches 24 have been produced, they are filled, for example by a printing process, with electrically non-conductive material, preferably polypropylene, so that the filler strips 26 according to FIG. 1 result. In this way, on the top of the cell wall panel 11, between each (2n) th and (2n + 1) th filled trenches 24 are drawn, remaining between each (2n + 1) th and (2n) th the cell web material continuously. Complementarily, in this way, trenches 24 are filled on the underside of the cell wall track between each (2n + 1) th and (2n) th. Between each (2n) -th and (2n + 1) -th cell, the cell web material remains uninterrupted.

The resulting scheme of the current flow is indicated in Fig. 1 by the arrows 28.

Subsequently, the electrolyte supply lines are connected, compare to FIGS. 8 and 9.

The supply holes, each juxtaposed in groups of, for example, four supply holes 20, are each provided with an electrolyte fitting 60 that is coupled to an electrolyte main via an associated tubing 62. There are four tubular electrolyte main lines are provided, which are arranged on the two sides of the cell assembly 10. According to FIG. 8, an electrolyte main line 55 for supplying an anolyte and in parallel an electrolyte main line for supplying a catholyte run. On the opposite side of the composite 10 extend an electrolyte main line 57 for discharging the anolyte and parallel thereto an electrolyte main line 58 for discharging the catholyte.

Fig. 9 shows a perspective view of an electrolyte fitting 60 which is just cut in a plane passing through the transverse channel 68 cutting plane. Externally, a connection opening 66 is provided, which runs over the transverse channel 68 inwardly and then opens into a longitudinal channel 70 which is open at the bottom. Via the longitudinal channel 70, the connection with the underlying supply holes 20 is made possible. The longitudinal channel 70, which is closed off by the part of the cell wall provided with the supply holes 20, together with the supply holes 20, causes the electrolyte to be fed uniformly across the cell width, and also to be uniformly discharged again from the half cell. The respective electrolyte connection pieces 60 are suitably positioned on the respective surface of the cell wall web 1 1 or 12 and then welded by mirror welding. The connection with the associated electrolyte main lines 55, 56, 57, 58 then takes place via hose lines 62, which are connected between the connection openings 66 and the respective main electrolyte line 55, 56, 57, 58. In this case, a voltage reduction path 64 is generated by a winding 64 around the respective main electrolyte line 55-58 with several turns, that is to say the greatest possible ohmic resistance between two half-cells which are at different potentials.

The connections between the outputs of the voltage reduction section 64 and the electrolyte fittings 60 change in their course along the composite from above to below and behind, according to the alternating alternating polarity of the individual cells.

The end electrodes at the axial ends of the composite 10 are slightly longer than the other tracks that make up the composite. At these two ends copper terminals are attached over the entire width of the electrode tracks and then soldered. Cell wall webs can also be cut to length by being cut through approximately in the middle of the period and the electrode webs are cut loose at the longitudinal edges in order to make them accessible to contact with copper conductors.

The following criteria are used for certain dimensions of the composite:

The distance between adjacent metal bands 36, their cross-sectional area and their width (in the direction of the membrane plane) is determined from the maximum of the ratio of the active, the electrolyte exposed electrode area proportional useful power and the ohmic (electronic) losses in the electrode material. For example, the format and the area of the individual cells may be approximately DIN A4, with the cell measuring 20 cm in the flow direction and 30 cm in the flow direction, for example. It falls about such a cell from about 1 bar of pressure. Larger surfaces are preferred as long as the electrolyte pressure in the system does not become too large for the necessary electrolyte flow, preferably not significantly greater than 1 bar.

The number of cells connected in series is preferably determined from the minimum of the system cost / system performance ratio. The higher the input voltage (DC), the better the cost of inverters and their efficiency. Since this is the output voltage of the composite, but also increase the shunt losses with it via the electrolyte paths between hydraulically connected and electrically connected in series half cells of the same polarity. These losses can be reduced by hydraulic separation of the cell series into shorter cell series. But this in turn increases the cost of the necessary pumping system.

Claims

Method for producing a series-connected composite (10) from cells (13, 15) having a membrane (14) and electrodes (16, 17) arranged on both sides of the membrane (14), which are outwardly on both sides by a plastic wall ( 1 1, 12) and sealed at the longitudinal edges, in a roll-to-roll process, comprising the following steps:

(A) providing band-shaped electrode material (16, 17) for a first and a second band-shaped electrode;

(b) providing band-shaped plastic material for first and second cell wall webs (11, 12) and punching out marginal service holes (20) at both edges of each cell wall panel (11, 12);

(c) providing band-shaped material for an ion-conducting membrane web (14) and pretreating the membrane web (14) on selected lines (18) in the transverse direction and at both edges in the longitudinal direction;

(d) merging a first cell wall web (11) followed by a first electrode web (16), the membrane web (14), a second electrode web (17), and a second cell wall web (12) in a roll-to-roll process; edge-side joining of the webs (1 1, 12, 14, 16, 17) by local melting at the two edges;

(e) local melting of the composite (10) produced in step (d) along the previously pretreated lines (18) in the transverse direction;

(F) separating the composite (10) by a subtractive method on selected lines in the transverse direction alternately on one side and the other side between adjacent Einschmelzzonen (18) from the step (E) for the production of trenches (24), which interrupt the respective electrode (16, 17) on a membrane side electrically.

2. Method according to claim 1, in which the trenches (24) formed by the separation in step (f) are closed with plastic (26) immediately after their production.

3. The method of claim 1 or 2, wherein the electrodes (16, 17) in step (a) of porous graphite material, in particular from one or more layers of graphite paper (34) are produced on the several in the longitudinal direction over the entire length extending metal strips (36), preferably copper strips are applied at certain intervals on a surface, preferably non-adherently attached or soldered at certain points.

4. The method of claim 3, wherein over the metal strip (36) plastic strips (37) of greater width than the metal strips (36) are applied, preferably by Kunststoffklebepunkte, on the opposite side plastic strips (38) are applied, preferably by Kunststoffklebepunkte, and then the plastic strips (37, 38) are melted on both sides of the graphite material (34) by hot rolling into the surface of the graphite material (34).

5. The method according to any one of the preceding claims, wherein on the membrane (14) at the predetermined locations at which later in step (f) the separation of the electrodes (16, 17) takes place in the transverse direction, in each case a protective strip (22) Plastic is applied to the separation side facing surface.

6. The method according to any one of the preceding claims, wherein the separation of the electrodes (16, 17) takes place at the predetermined locations by a mechanical cutting or sawing process or by a laser cutting process.

7. The method according to any one of the preceding claims, is used in the polypropylene or polyethylene as a plastic material.

8. The method according to any one of claims 2 to 7, wherein the plastic material for closing the trenches (24) is pressed or injected into the trenches (24), preferably at elevated temperature.

9. The method according to any one of the preceding claims, wherein to the punched in step (b) supply holes (20) electrolyte supply lines are connected, preferably by electrolyte fittings (60) fit over the associated supply holes (20) are placed at predetermined locations and with the surrounding Surface of the cell wall web (1 1, 12) are welded, preferably by mirror welding.

A method according to claim 9, wherein a respective group of supply holes (20) is connected to an electrolyte fitting (60) connected to an electrolyte main lead (55, 56, 57, 58), at least four main electrolyte leads (55-58 ), in each case an electrolyte main line for the Anolytzufuhr (55) and the Katholytzufuhr (56) and in each case an electrolyte main line for the Anolytabfuhr (57) and the Katholytabfuhr (58) with the associated cells of the composite (13, 15) respectively via a voltage reduction path (64) are connected.

1 1. A method according to claim 10, wherein the stress relief sections (64) are each made by wrapping at least one main electrolyte line (55-58) with at least one tube (62).

12. The method according to any one of claims 9 to 1 1, wherein the electrolyte fittings (60) are preferably made by injection molding of polypropylene or polyethylene, which is preferably free of plasticizer.

13. The method according to any one of the preceding claims, wherein a membrane web (14) is used, which is narrower than the cell wall webs (1 1, 12), preferably about 5 to 15 millimeters narrower, and preferably made of a modified PTFE film is produced, in particular from a modified with perfluorosulfonic acid PTFE film.

14. The method according to any one of the preceding claims, wherein the pretreatment of the membrane web (14) in step (c) by oxidation in an oxidation bath (42) takes place at the predetermined locations.

15. The method of claim 14, wherein the membrane web (14) for the oxidation of the longitudinal edges in step (c) suspended in the longitudinal direction and with both longitudinal edges in an oxidation bath (42) having a predetermined depth (12) is immersed.

16. The method according to claim 14 or 15, wherein the membrane web (14) for oxidation in the transverse direction in step (c) between the upper and lower pulleys (47, 48) is hung zig-zag-shaped and with a predetermined immersion depth (ri) of preferably 5 to 10 millimeters is immersed in the oxidation bath, after the treatment further moved and immersed in the next section until all selected lines are oxidized in the transverse direction.

17. The method of claim 14, 15 or 16, wherein the oxidation bath sodium is used dissolved in ammonia.

18. A series-connected composite (10) comprising cells (13, 15) with a continuous membrane web (14) and electrode webs (16, 17) arranged on both sides of the membrane web (14), which are projected outwardly on both sides by a continuous cell wall web (1 1, 12) is made of plastic over its entire length and is sealed at the longitudinal edges by a connection of the two cell wall webs (1 1, 12), wherein the serial interconnection via continuous electrode tracks (16, 17) is formed, the electrically in Querrich- are interrupted alternately on the one and the other side at each (n) -th and every (n + 1) -th cell, preferably produced in a roll-to-roll method according to one of the preceding claims.

19. The composite of claim 18, wherein each of a group of supply holes (20) on the cells (13, 15) with an electrolyte fitting (60) is connected to an electrolyte main line (55-58), wherein at least four main electrolyte lines (55-58), in each case an electrolyte main line for the anolyte supply (55) and the catholyte supply (56) and in each case an electrolyte main line for the Anolytabfuhr (57) and the Katholytabfuhr (58) with the associated cells (13, 15) of the composite (10) are each connected via a voltage reduction path (64).

20. The composite of claim 19, wherein the voltage reduction sections (64) are each formed by a winding (64) of a hose (62) around the respective main electrolyte line (55-58), by means of which at least one main electrolyte line (55-58) with the associated electrolyte connector (60) is connected.