Methods for manufacturing a stack, stack, electrolysis plant and fuel cell system

Abstract

The invention relates to a method for manufacturing a stack (1) with a plurality of electrochemical cells (2), in which the electrochemical cells (2) are stacked, placed between two end plates (3), and clamped to the end plates (3). According to the invention, tapes (4) and / or cables (5) made of electrically non-conductive fibers are used for clamping (2). The invention further relates to a stack (1), an electrolysis plant, and a fuel cell system with a stack (1) according to the invention.

Description

The invention relates to a method for producing a stack according to the preamble of claim 1. The stack can be, in particular, an electrolysis stack or a fuel cell stack. The invention therefore also relates to an electrolysis system and to a fuel cell system having a stack according to the invention.Prior ArtA stack includes a plurality of electrochemical cells in a stacked arrangement. These are clamped together with the aid of metallic clamping bands. In order to be able to adjust the length of the tension straps, these are fastened to the stack by means of adjustable fastening devices.The metallic tension straps are usually surrounded by shrink tubes to provide electrical insulation from the electrochemical cells. This is because the potential of the cells can be up to 500 V, so that there is the risk of arcing from the cells to the clamping bands. When adjusting the length of the tension straps, the length of the shrink tubes must accordingly also be adapted. This requires time and personnel.The present invention is concerned with the object of eliminating the disadvantages of the prior art. In particular, the production of a stack is to be simplified and made more cost-effective.Disclosure of the InventionTo achieve the object, the method having the features of claim 1 and the stack having the features of claim 6 are proposed. Advantageous further developments of the invention can be found in the respective dependent claims. Furthermore, an electrolysis system and a fuel cell system with a stack according to the invention are specified.A method for producing a stack having a multiplicity of electrochemical cells is proposed. In the method, the electrochemical cells are stacked, placed between two end plates and clamped to the end plates. According to the invention, straps and / or cables made of electrically non-conductive fibers are used for bracing.Because in the method according to the invention, straps and / or cables which are made of electrically non-conductive fibers are used for bracing, electrical insulation by means of shrink tubes can be dispensed with. The production of the stack is thus significantly less time-consuming and cost-intensive. The special straps and / or ropes can be used otherwise like the metal tension straps known from the prior art. In particular, the same fastening means can be used for fastening the straps and / or cables to the stack.According to a preferred embodiment of the invention, the straps and / or cables used for bracing are made of electrically non-conductive polymer fibers. Polymer fibers are electrically non-conductive plastic fibers and are therefore particularly well suited. Preferably, the polymer fibers are fibers made of LCP, i.e. of a liquid crystal polymer ("liquid crystal polymer"). Liquid crystal polymers are plastics which combine the properties of polymers and liquid crystals. Liquid crystalline polymers have very high tensile strength and high modulus of elasticity. That is, they can absorb high tensile loads and are also extremely stable. LCP fibers are, for example, about 5 times stronger than steel. Furthermore, liquid-crystalline polymers have very low dielectric constants. This means that they are hardly transmissive to electric fields and are thus electrically insulating.To produce LCP fibers, liquid-crystalline polymers are generally spun. The LCP fibers can then be used as conventional fibers. For example, the fibers may be woven or braided.In a further development of the invention, it is therefore proposed that the straps and / or cables used for bracing the electrochemical cells are woven or braided from the electrically non-conductive fibers.Further plate-shaped elements can be arranged between the end plates and the stacked electrochemical cells. The further elements can be, in particular, a current collector plate. According to a preferred embodiment of the invention, a current collector plate is therefore respectively inserted between the end plates and the stacked electrochemical cells. This allows the stack to be connected later to a power supply or power electronics.Furthermore, a stack for an electrolysis system or a fuel cell system is proposed. The stack includes a stack of a plurality of electrochemical cells disposed between two end plates and clamped to the end plates. According to the invention, the stack and the end plates are braced by means of straps and / or ropes made of electrically non-conductive fibers.Because in the stack according to the invention straps and / or ropes made of electrically non-conductive fibers are used for bracing the stack and the end plates, an additional electrical insulation of the straps and / or ropes can be dispensed with. In particular, the use of the otherwise customary shrink tubes can be dispensed with. The stack can thus be produced much more simply and economically. The proposed bag can be produced in particular by the method according to the invention described above.According to a preferred embodiment of the invention, the straps and / or ropes are made of electrically non-conductive polymer fibers, preferably LCP fibers. The advantages of polymer fibers, in particular of LCP fibers, have already been described in detail further above, so that reference is made to these. Again to be emphasized are the high tensile strength and stability of the LCP fibers, which prove to be particularly advantageous for the proposed use.It is also proposed that the straps and / or ropes be woven or braided from the electrically non-conductive fibers. The strength of the straps and / or ropes can thereby be further increased.Advantageously, a current collector plate is inserted between the end plates and the stack. The stack can later be connected to a power supply or power electronics via the current collector plate.Since the preferred fields of application are electrolysis systems and fuel cell systems, an electrolysis system and / or a fuel cell system each with a stack according to the invention are furthermore proposed.A preferred embodiment of the invention is explained below with reference to the attached drawings. This shows a schematic side view of a stack according to the invention.DETAILED DESCRIPTION OF THE DRAWINGThe stack 1 shown comprises a plurality of electrochemical cells 2 which are arranged to form a stack 7. Above and below the stack 7, a current collector plate 6 and an end plate 3 are arranged, respectively. The stack 7 and the plates 6, 3 are clamped together by means of belts 4. Instead of straps 4, cables 5 (see reference numerals in brackets) could also be used.The straps 4 or cables 5 do not require a shrink tube for electrical insulation with respect to the stack 1, in particular with respect to the electrochemical cells 2 and the current collector plates 6, since these are produced from electrically non-conductive fibers, for example from LCP fibers. As a result, the production of the stack 2 can be significantly simplified and made more cost-effective. When using LCP fibers, a very high tension force can also be applied, since these have a very high tensile strength. Bands 4 or ropes 5 made of LCP fibers are also many times stronger than metallic tension bands.

Claims

Method for producing a stack (1) having a multiplicity of electrochemical cells (2), in which the electrochemical cells (2) are stacked, placed between two end plates (3) and braced with the end plates (3), characterized in that straps (4) and / or ropes (5) which are produced from electrically non-conductive fibres are used for bracing (2).Method according to claim 1, characterised in that the straps (4) and / or ropes (5) used for bracing are made of electrically non-conductive polymer fibres.Method according to claim 2, characterised in that the polymer fibres are liquid crystal polymer (LCP) fibres.Method according to claim 1, 2 or 3, characterised in that the straps (4) and / or cables (5) used for bracing the electrochemical cells (2) are woven or braided from the electrically non-conductive fibres.Method according to one of the preceding claims, characterized in that a current collector plate (6) is in each case inserted between the end plates (3) and the stacked electrochemical cells (2).Stack (1) for an electrolysis plant or a fuel cell system, comprising a stack (7) of a plurality of electrochemical cells (2) which is arranged between two end plates (3) and is braced with the end plates (3), characterized in that the stack (7) and the end plates (3) are braced by means of straps (4) and / or ropes (5) which are made of electrically non-conductive fibres.Stack (1) according to claim 6, characterised in that the belts (4) and / or ropes (5) are made of electrically non-conductive polymer fibres, preferably LCP fibres.Stack (1) according to claim 6 or 7, characterised in that the straps (4) and / or ropes (5) are woven or braided from the electrically non-conductive fibres.Stack (1) according to one of Claims 6 to 8, characterized in that a current collector plate (6) is in each case inserted between the end plates (3) and the stack (7).Electrolysis plant having a stack (1) according to one of Claims 6 to 9.Fuel cell system having a stack (1) according to one of Claims 6 to 9.

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