GB2498055A - Tubular fuel cell - Google Patents

Abstract

A tubular fuel cell 10 comprises a support tube 11, 12, 13 which serves as a support for a functional layer system 21. In order to simplify the electrical contact, at least one of the functional layers 21 is subdivided by at least one region 23 extending in the longitudinal direction L of the support tube 11, 12, 13, so that at least two spaced functional layer sections A, B result. A method for producing the fuel cell is also described and claimed. Preferably, the region 23 is provided with an electrically insulating layer 24, which may be made of a magnesium silicate such as forsterite. The functional layer system 21 preferably comprises an anode layer, a solid electrolyte and a cathode layer.

Description

Fuel cefl system The present invention relates to a method for producing a fu& cell, a fuel-cell-based energy system and the use such a fuel cell.

Prior art

High-temperature fuel bells, which are also referred to as solid oxide fuel cells (SOFCs), serve to generate power and optionally also heat. They are used mostly in auxiliary power units or combined heat and power plants (CHP), High-temperature fuel cells may have a tubular or planar support body. The fuel cells of the type of interest here have a tubular support body and are therefore to be distinguished owing to their geometric design from fuel cells of planar form. Fuel cells with a tubular support body are also referred to as tubular fuel cells. Tubular fuel cells may be designed with both ends open, so that fuel gas or air can be passed through the tubular fuel cell, and also may be designed with one end side closed, fuel gas or air being able to be led into the inside of the fuel cell via a lance

Disclosure of the Invention

the subject-mailer of the invention is a tubular fuel cell (10) having a support tube (tube) which serves as a support for a fuhctional layer system. The functional layer system or its functional layers may be deposited on the inside or on the outside of the support tube (tube). The support tube may therefore serve as a support both for internal functional layers and for external functional layers, in particular however for *": internal functional layers. In this regard, in principle both ends of the support tube may be open. In particular, however, one end of the support tube (tube) may be closed. *. 30

In particular, at least one of the functional layers, for example the internSlfunctional layers, is subdivided in the longitudinal direction of the support tube (tube), for example by at least one region extending in the longitudinal direction of the support tube, so that two functional layer sections, for example half-layers, in particular spaced from one another, result.

A subdivision of one or more functional layers in the longitudinal direction of the support tube, in particular by a region extending in the longitudinal direction and spacing functional layer sections, has an advantageous effect on the electrical connection of the functional layers and enables the current flow to be directed through one functional layer section from one end of the support tube to the other end of the support tube in a.first direction in the longitudinal direction of the support tube and the current flow to be directed through the other functional layer section again, in a direction opposite to the first direction! from one end of the support tube to the other end of the support tube. By multiple subdivision, in this case a multiple to-and-fro directing of the current flow is also possible in principle.

Directing current through functional layers subdivided in this way is advantageous * in particular in tubular fuel cells having a support tube which is closed at one end! the closed end impedes electrical contacting In particular, the reversal of the direction of the current flow can therefore take place in the region of the closed end.

In the context of one embodiment! a functional layer at least partly adjoining the support tube and/or an at least partly exposed functional layer is subdivided by at least one region extending in the longitudinal direction of the support tube, so that at least two functional layer sections spaced from one another! in particular circumferentiafly with respect to the circumference of the support tube, result.

In the context of a further embodiment, a gas-tight, electrically insulating, in particular electrically insulating, in particular electrically and ionically insulating, inner insulation layer is formed between the support tube and the region which extends in the longitudinal direction of the support tube and which spaces the * fUnctional layer sections of the functional layer at least partly adjoining the support tube.

In connection with the insulation layers, the term inner" refers to the arrangement of the insulation layer between the support tube and the functional layers, in particular the term "inner" insulation layer leaving open whether the insulation layer is formed inside the support tube (functional layersystem on inside of the support tube) or outside the support tube (functional layer system on outside of the support tube).

In particular, the inner insulation layer may overlap edge sectioná, of the functional in layer sections of the functional layer at least partly adjoining the support tube, which adjoin the spacing region extending in the longitudinal direction of the support tube. In this case, the inner insulation layer may be arranged between the support tube and the edge sections, of the functional layer sections of the functional layer at least partly adjoining the support tube, which adjoin the spacing region extending in the longitudinal direction of the support tube. In this case, the remaining regions of the functional layer sections of the functional* lyer at least partly adjoining the support tube adjoin the support tube.

In the context of an alternative or additional embodiment, the region which extends in the longitudinal direction of the support tube and which spaces the functional layer sections of the at least partly exposed functional layer is covered by a gas-tight, electrically insulating, in particular electrically and ionically insulating, exposed insulation layer. In particular, the exposed insulation layer may overlap edge sections, of the functional layer sections of the at least partly exposed functional *r'" 25 layer, whThh adjoin the spacing region extending in the longitudinal direction of the support tube.

The inner insulation layer andlor the exposed insulation layer advantageously enable the region subdividing the functional, layer(s) and thus the functional layer *; 30 system (tubular functional layer pack) to be gas-tightly sealed. It is thus advantageously possible to prevent'gas, for example oxygen-containing gas andlor a fuel gas, from being able to penetrate through the functional layer system, in particular from one side of the functional layei system to the other side of the functional layer system, and cause a "chemical short circuit". Moreover,, the inner insulation layer and/or the exposed insulation layer enable the subdivided functional layer sections to be electricaUy and ionically insulated from one another and also a gas exchange therebetween to be prevented.

In the context of a further embodiment, the inner insulation layer and/or the exposed insulation layer extends in the form of a strip in the longitudinal direction of the support tube. In particular, in this case the inner insulation layer and/or the exposed insulation layer may -as explained in more detail later -adjoin cathode-electrolyte units belonging to a string or extend parallel to strings of'cathode-' electrolyte units.

In the context of a special configuration of these embodiments, the region which extends in the longitudinal direction of the support tube and which spaces the functional layer sections of the functional layer at least partly adjoining the support tube is partly or completely filled with the material of the insulation layer, and/or the region which extends in the longitudinal direction of the support tube and which spaces the functional layer sections of the at least partly exposed functional layer is partly or completely filled with the material of the insulation layer.

Additionally, the functional layer at least partly adjoining the support tube be subdivided by at least one region extending in the direction of the circumference of the support tube, so that two or more functional layer sections spaced from one *:... 25 another, in particular axially with respect to the longitudinal direction of the support tube; result. -* Also the at least partly exposed functional layer may additionally be subdivided by at least one region extending in the direction of the circumference of the support *5S tube, so that two or more functional layer sections spaced from one another, in * particular axially-with respect to the longitudinal direction of the support tube, result.

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lii particular, the cathode-electrolyte units (explained in more detail later) belonging to a string may be spatially separated from one another by this additional subdivision bf the functional layers.

The regions the region which extend in the direction of the circumference of the support tube and which space the functional layer sections of the functional layer at least partly adjoining the support tube andior of the at least partly exposed' functional layer may be partly or completely filled with a gas-tight, electrically insulating material. The material may in this case, but does not necessarily have to be, additionally ionically insulating.

To distinguish them from the inner and/or exposed insulation layer which extends in particular in the longitudinal direction of the support tube, the regions which extend in the circumferential direction of the support tube and are filled with electrically insulating material ae called insulation sections.

In the context of a further embodiment, the functional layer at least panty adjoining the tube body is a cathode layer and the at least partly exposed layer is an anode layer.

Conversely, it is however equally possible for the functional layer at least partly adjoining the tube body to be an anode layer and the at least partly exposed layer to be a cathode layer. *. .* * * . * *

**:s* 25 Preferably, the functional layer at least partly adjoining the tube body is a cathode layer and the at least partly exposed layer is an anode layer. * -

In parbcular, an intermediate functional layer may be formed between the functional * layer at least partly adjoining the support tube and the at least partly exposed *** functional layer. The intermediate functional layer may, in particular, be an electrolyte layer.

The intermediate functional layer, in particular the electrolyte layer, may be formed substantially analogously to the adjoining functional layer: the exposed functional layer, i.e. the cathode layer and the anode layer.

In particular, the intermediate functional layer may be subdivided by at least one region extending in the longitudinal direction of the support tube, so that at least two functional layer sections of the intermediate functional layer which are spaced from one another, in particular circumferentially with respect to the circumference of the support tube, result. The region which extends in the longitudinal direction of the support tube and which spaces the functional layer sections of the intermediate functional layer may be partly or completely filled with an ionically and electrically insulating material. In particular, the region which extends in the longitudinal direction of the support tube and which spaces the functional layer sections of the intermediate functional layer may likewise be partly or completely filled with the gas-tight, electrically and ionically insulating material of the, for example inner and/or exposed, insulation Layer(s).

Additionally, the intermediate functional layer may be subdivided by at least one region extending in the direction of the circumference of the support tube, so that two or more functional layer sections which are spaced from one another, in particular axiafly with respect to longitudinal direction of the support tube, result.

The regions which extend in the direction of the circumference of the support tube and space the functional layer sections of the intermediate layer may be partly or completely filled with an electrically conductive, ionically insulating material. In *.... 25 particular, the regions for subdividing the intermediate layer which extend in the direction of the circumference of the support tube may serve as interconnectors and, for example, connect two adjacent cathode-electrolyte-anode units in series.

In this case, the interco.nnectors may adjoin on the one hand a cathode of a cathode-electrolyte-anode unit and on the other hand an anode of another cathode-n..

electrolyte-anode unit. In this case, cathode of one cathode-electrolyte-anode unit may be formed, for example, in an overlapping manner with respect to the anode of the other cathode-electrolyte-anode unit, the interconnector being formed at east in the overlapping region.

The regions which extend in the longitudinal direction of the support tube and which subdivide the functional layer at least partly adjoining the support body, the intermediate functional layer and the at least partly exposed functional layer may be formed in particular at least substantially at the same place, in particular above one another. This has the advantage that an insulation layer, in particular the inner and/or exposed insulation layer, which may be deposited for example in a process step, can insulate the subdivided functional layer sections of the functional layer at least partly adjoining the support body, of the intermediate functional layer and of the at least partly exposed functional layer, equaHy electrically and lonically from one another and also prevent a gas exchange therebetween. In particular, the regions which exteid in the longitudinal direction of the support tube, and which subdivide the functional layer at least partly adjoining the support body, the intermediate functional layer and the at least partly exposed functional layer, can therefore be fifled partly or completelywith the gas-tight, electrically and ionically insulating material of the inner and/or exposed insulation layer.

The functional layer system may, for example, be of sandwich-like form and comprise in particular a cathode layer, an anode layer and an electrolyte layer arranged between the cathode layer arid the anode layer. In this case, the cathode layer may have cathode layer sections spaced from one another, the electrolyte layer electrolyte layer sections spaced from one another and the anode layer anode *.... 25 layer sections spaced from one another, where in each case a cathode layer section with an electrolyte layer section and an anode layer section forms a 0..

cathode, an electrolyte and an anode of a cathode-electrolyte-anode unit. In this way, the cathode layer, the electrolyte layer and the anode iayer, in particular the cathode layer sections, the electrolyte layer sections and the anode layer sections, form a multiplicity of cathode-electrolyte-anode units. .

In this case, at east two mutually parallel strings of series-connected cathode-electrolyte-anode units may be formed in the functional layer system in the longitudinal direction of the suppbrt tube.

The cathodes, electrolytes and anodes of cathode-electrolyte-anode units belonging to different strings may in this case be electrically and ionically insulated from one another in particular by the regions which extend in the longitudinal direction of the support tube and which respectively space the cathode layer section of the cathode layer and the electrolyte layer sections of the electrolyte layer and the anode layer sections of the anode layer, in particular circumferentially with respect to the circumference of the support tube.

In this case, the cathodes and anodes of cathode-electrolyte-anode units belonging* to a string may be electrically insulated from one another by the regions which extend in the direction of the circumference of the support tube and which respectively space the cathode layer section of the cathode layer and the anode layer sections of the anode layer, in. particular axially with respect to the longitudinal direction of the support tube.

The electrolytes of cathode-electrolyte-anode units belonging to a string may in this case be ionically insulated from one another by the regions which extend in the direction of the circumference of the support tube and which space the electrolyte layer sections of the electrolyte layer, in particular axially with respect to the longitudinal direction of the support tube. In this case, the cathode-electrolyte-anode units belonging to a string may additionally be connected in series by the regions which extend in the direction of the circumference of the support tube and which space the electrolyte layer sections of the electrolyte layer, in particular axially with respect to the longitudinal direction of the support tube. In other words, the regions which extend in the direction of the circumference of the support tube and which space the electrolyte layer sections of the electrolyte layer, in particular axially with respect to the longitudinal direction of the support tube, may also serve as interconnectors.

The subdivision of the, for example internal, functional layers may in particular be effected in such a way that with respect to the functional layers two functional layer half-tubes (half-tubes) result.

In the context of a further embodiment, the subdivision of the functional layer adjoining the support tube and/or of the exposed functional layer and/or of the intermediate functional layer is therefore effected in such a way that with respect to the functional layers two functional layer half-tubes result, in particular wherein the functional layer halt-tubes are spaced from one another, in particular circumferentially with respect to the circumference of the support tube, by two regions extending in the longitudinal direction of the support tube.

The functional layer half-tubes may, for example, each have or form a string is composed of cathode-electrolyte-anode units connected in series.

In the context of a further embodiment, in this case the regions which extend in the longitudinal direction of the support tube and which space the functional layer half-tubes is partly or completely filled with a gas-tight, electrically and ionically insulating insulation layer material.

In particular, in this case there may be formed, between the support tube and the regions which extend in the longitudinal direction of the support tube and which space the functional layer half-tubes, in each case a gas-tight, electrically and ionically insulating, inner insulation layer which optionally overlaps edge regions of the functional layer half-tubes adjoining the respective region. * *

Alternatively or additionally thereto, the regions which extend in the longitudinal direction of the support tube and which space the functional layer half-tubes may in' *...: 30 each case be covered by a gas-tight, electrically and.ionicalty insulating, exposed * insulation layer which optionally overlaps edge regions of the functional layer half-tubes adjoining the respective region.

The inner insulation layers and/or the exposed insulation layers may in this case extend in particular in the form of a strip in the longitudinal direction of the support tube.

The support tube may have at least one open end which is configured as a foot section for fastening the fuel cell (mounting flange). In the case of a support tube open at both ends, the support tube may have such a foot section at both open ends. In the case of a support tube which has a closed end, the support tube may be closed by a cap section at one end, the other open end of the support tube serving as a foot section.

The cap section may. for example, have recesses and/or struts for centring and/or stabilising a gas supply lance introducible into the interior of the support tube.

The functional layer system may in particular be deposited on a substantially ho}low-cylindrical, middle section of the support tube which extends between the foot sections or the cap section and the foot section.

The middle section of the support tube may in this case in particular be gas-permeably porous.

The cap section and/or the foot section(s) may in this case in particular be gas-tight.

In the connecting zones between a gas-permeably porous section and a gas-tight *:***! sectiàn, the gas-permeably porous section and the gas-tight section may be formed in an interlocking manner.

* 30 The support tube may, for example, comprise or be formed from at least one material which is selected from the group consisting of magnesium silicates, in particular forsterite, zirconium dioxide, in particular doped zirconium dioxide, for example zirconium dioxide doped with 6.5% .by weight of yttrium oxide (1203), aluminium oxide, aluminium oxide-zirconium oxide mixtures, spinels, for example magnesium spinels, Such as magnesium aluminate, zirconium oxide-glass mixtures, zinc oxide and mixtures thereof. In this case, the gas-tight sections and the gas-permeably porous section may be formed from the same material and differ essentially only with regard to the porosity and gas-tightness.

In particular, the support tube may comprise or be formed from at least one material which is selected from the group consisting of magnesium silicates, in particular forsterite, aluminium oxide (Al203), spinels, for example magnesium spinels (Mg-spinel), such as magnesium aluminate, and mixtures thereof.

Preferably, the support tube is comprise or be formed from a magnesium silicate, in particular forsterite. Magnesium silicates, in particular forsterite (Mg2SiO4), is particularly suitable as a support material for forming the support tube, on account of its electrochemical strength, the high electrical resistance and the coefficients of thermal expansion, appropriate for the functional layers, of 1O-111O K1, and can thus additionally also be used as a material for the inner and/or exposed insulation layer or as insulation paste. 2.0

The current flow within the tube may in this case be directed, for example, within a first half-tube from the foot section of the support tube (foot of the tube) to the cap section of the support tube (head of the tube) and via the second half-tube from the cap section (head) back to the foot section (foot) of the support tube (tube).

In the context of a further embodiment, the current flow within the functional layer system or tube is directed within a first functional layer half-tube (half-tube) from the * open end (foot) ot the support tube (tube) to the closed end (head) of the support * tube (tube), and is directed via the second functional layer half-tube (half-tube) from the closed end (head) of the support tube (tube) back to the closed end (foot) of thefl support tube (tube). 0*

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In the context of a further embodiment an electrical ring conductor, which electrically connects to one another two functional layer sections of a functional layer subdivided by a region extending in the longitudinal direction of the support tube, is formed in the functional layer systeffi. In this way, in particular two cathode-electrolyte-anode unit strings may be connected to one another is series.

In particular, in this case an electrical ring conductor may be arranged in the head region of the tube or in the region otthe cap section or closed end of the support tube.

For example, the first functional layer half-tube may be electrically connected by the ring conductor to the second functional layer half-tube in the region of the clbsed end of the support tube, The ring conductor thus enables in particular the strings of the functional Payer half-tubes to be connected in series among one another.

The ring conductor may be formed, for example, from the materiaj of the at least partly exposed functional layer or from the material of the functional layer at least partly adjoining the support tube, in particular from the material of the anode layer or the cathode layer.

In the context of a further embodiment, the functional layer system is deposited on the inside or on the outside, in particular the inside, of the support tube.

Preferably, the functional layer system is deposited on that side of the support tube which can be subjected to fuel gas. This may, for example, be the interior of the support tube, in which case the fuel cell can be called a tubular cell with internal electrode pack.

An arrangement of the functional layer system on the side of the support body 4*t * 30 which can be subjected to fuel gas has the advantage that the flow may be reduced in an inert fuel gas atmosphere and thus less expensive materials, such as, for example, nickel, may be used.

The insulation layer(s), in particular the inner and/or outer insulation layer, may comprise or be formed from for example at least one, in particular gas-tight, material which is selected from the group consisting of magnesium silicates, in particular forsterite, zirconium dioxide, in jart4cular doped zirconium dioxide, for example zirconium dioxide doped with 65% by weight of yttrium oxide (Y203), aluminium oxide, aluminium oxide-zirconium oxide mixtures, spinels, for example magnesium spinels, such as magnesium aluminate, zirconium oxide-glass mixtures, zinc oxide and mixtures thereof. In this case, the material of the insulation layer(s) may be in particular the same material from which the support tube is formed and differ optionally only with regard to its gas-tightness.

Possible material candidates for the insulation layer(s), in particular the inner and/or outer insulation layer, which come into consideration are in particular either the dense forsterite, Mg-spinel or A1203.

In particular the insulation layer material may therefore be selected from the group consisting of, in particular gas-tight, magnesium silicates, in particular forsterite, aluminium oxide (Al203), spinels, for example magnesium spinels (Mg-spinel), such as magnesium alumiriate, arid mixtures thereof.

In the context of a further embodiment, the insulation layer material comprises or is a, in particular gas-tight, magnesium silicate, in particular forsterite. Magnesium siricate, in particular forsterite (Mg2SiO4), is particularly suitable as a support material for forming the support tube, on account of its electrochemical strength, the high electrical resistance and the coefficients of thermal expansion, appropriate for the functional layers, of 1O.11106 K1, and can thus also be used as a material for the inner and/or exposed insulation layer or as insulation paste. Magnesium S.....

* silicates, in particular forsterite, have provided particularly suitable in order, on the one hand, to hinder undesired gas diffusion through the. functional layer system and in the functional layers, in particular between the subdivided functional layer * * sections of the functional layers, and, on the other hand, to act as an electrical insulator.

With regard to further technical features and advantages of the fuel cell according to the invention, reference is hereby made explicitly to the explanations in connection with the method according to the invention, the energy system according to the invention, the use according to the inventiofl and also with the figures.

A further subject-matter of the present invention is a method for producing a tubular fuel cell, in particular a fuel cell according to the invention.

In this method, in a method step a) a sleeve or a sheet is printed with a functional layer system comprising a cathode layer, an anode layer and an electrolyte layer lying therebetween, wherein at least the functional layer printed last, for example the cathode layer or the anode layer, in particular the cathode layer, is subdivided by at least one unprinted region, so that at least two spaced functional layer sections result.

In a method step b)the unprinted region of the functional layer, printed last in method step b), is printed with a gas-tight or gas-tightly sintering., electrically insulating, in particular electridally and ionically insulating, insulation layer.

In a method step c) a support tube, provided with the functional layer system is formed by means of ceramic injection moulding (CIM), wherein the sleeve or sheet carrying the functional layer system is overrnoulded or back-moulded, which is also called inmould labelling (IML).

* During the printing, it is not readily possible in a process step to print around a sleeve completely or print a sheet directly up to the edge. Moreover, in the case of the fuel cell according to the invention, it is provided that at least one of the **** * functional layers is subdivided into two functional layer sections by a itself in the * * longitudinal direction of the support tube. In both cases, in the case of printing step, therefore an unprintable andior unprinted region. may remain which has to be sealed off in particular from the porous support tube. -In this case, the method according to the inventior advantageously enables such gas-untight regions to be sealed in a simple and effective manner by the insulation layer(s). The insulation layers may in this case be printed, for example lastly, for example longitudinally over the unprinted region. It is thus possible to connect the functional layer system (functional layer pack) in series and thereby avoid excessive currents, which could not otherwise be discharged only with difficulty.

The printing of the sleeve or the sheet, in particular with the functional layer system (electrode pack) may be effected method step a) and b) by means of round screen printing technology.

Alternatively to this, in method step a) a flat sheet1 so-called flat stock, may be printed, in particular with the functional layer system, and is subsequently bent to form a hollow cylinder, during which two mutually opposite sides of the sheet adjoin one another to form a joint and the joint is printed with a further gas-tight or gas-tightly sintering, electrically and ionically insulating insulation layer.

In the context of one embodiment, the method therefore further comprises the method steps bi) and b2), which take place after method step a). In this case, in method step bi) the sheet is bent to form a hollow cylinder, wherein two mutually opposite sides of the sheet adjoin one another to form a joint. In method step b2) the joint is then printed with a further gas-tight or gas-tightly sintering, electrically insulating, in particular electrically and ionically insulating, insulation layer Q. In this case, method step b) may take place before methcd step bi), for example by means of flat screen printing, or before, during or after method step b2), for example by means of round screen printing. *0-

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In method step b) and method step b2), use may be made in particular of a screen printing paste which is designed to form a gas-tight and electrically insulating, in particular electrically and ionically insulating, material.

S The screen printing paste may comprise, for example, at least one material for formin at least one material from the group consisting of magnesium silicates, in.

particular forsterite, zirconium dioxide, in particular doped zirconium dioxide, for example zirconium dioxide doped with 6.5% by weight of yttrium oxide (Y203), aluminium oxide, aluminium oxidezirconium oxide mixtures, spinels, for example magnesium spinels, such as magnesium alurninate, zirconium oxide-glass mixtures, zinc oxide and mixtures thereof. In this case, the material, for the formation of which the screen printing paste is designed, may be in particular the same material from which the support tube is formed and differ optionally only with regard to its gas-tightness.

In particular, the screen printing paste may comprise at least one material for forming at least one material from the group consisting of, in particular gas-tight, magnesium silicates, in particular forsterite, aluminium oxide (Al203), spinels, for example magnesium spinels (Mg-spinel), such as magnesium aluminate, and 23 mixtures thereof, Preferèbly, the screen printing paste comprises at least one material for forming a magnesium silicate, in particular forsterite.

The above materials may be present in particular in powder form in the screen printing paste.

* The screen printing paste containing one or more of the above materials in powder form is preferably adjusted such, that the insulation layer(s) to be formed therefrom r 30 corresponds, in sintering shrinkage and coefficient of temperature expansion (GTE), to that of the functional layer system (functional layer pack) and the support * tube (forsterite tube).

In the context of a further embodiment, in method step a) the funcUonal layer systeffl is printed in such a way that the cathode layer, the electrolyte layer and the anode layer are subdivided by at least one common unprinted region.

In method step c) use may be made; for example, of at least one injection moulding component, in particular two injection moulding components, which comprises, for example, at least one matehal for forming at least one material from the group consisting of magnesium silicates, in particular forsterite, zirconium dioxide, in particular doped zirconium dioxide, for example zirconium dioxide doped with 6.5% by weight of yttrium oxide (Y203),, aluminium oxide, aluminium oxide-zirconium oxide mixtures, spinels, for eample magnesium spinels, such as magnesium aluminate, zirconium oxide-glass mixtures, zinc oxide and mixtures thereof. In this case, the material, for the formation of which the injection moulding component or the injection mould components are designed, may be in particular the same material from which the insulation layer(s) are formed and differ optionally only with regard to its gas-tightness.

In particular, the at least one injection moulding component may comprise at least one material for forming at least one material from the group consisting of, in particular gas-tight, magnesium silicates, in particular forsterite, aluminium oxide (A1203), spinels, for example magnesium spinels (Mg-spinel), such as magnesium aluminate, and mixtures thereof.

Preferably, the at least one injection moulding component comprises at least one material for forming a magnesium silicate, in particular forsterite.

4**s*t In method step c) use may be made, in particular, of an injection mould, in particular having a cavity and a mould core which can be introduced into the cavity, r o the sleeve or sheet being placed on the mould core or a wall of the cavity spaced from the mould core. ns. * S

0.*.* . * S. The support tube (tube) may be produced in method step C) in particular by means of multi-component ceramic injection moulding, for example a 2-component ceramic injection moulding technique (CIM).

S The sleeve or sheet may be removed after method step c), for example burnt off during sintering of the support tube or mechanically removed.

With regard to further technical features and advantages of the method according to the invention, reference is hereby made explicitly to the explanations in connection with the fuel cell according to the invention, the energy system according to the invention, the use according to the invention and also with the figures.

Furthermore, the present invention relates to an energy system, for example a combined heat and power plant, for example for a residential or bifice building, an industrial plant, a power station or a vehicle, for example a micro-combined heat and power plant and/or a vehicle, which comprises and/cr uses (use in SOFC-CHP plants) a fuel cell according to the invention and/or a fuel cell system according to the invention and/or a fuel cells produced according to the invention and/ora fuel cell system produced according to the invention. A (micro-)combined heat and power plant may be understood to be in particular a plant for simultaneously generating power and heat from an energy carrier.

With regard to further technical features and advantages of the energy system according to the invention, reference is hereby made explicitly to the explanations in connection with the fuel cell according to the invention, the method according to * * the invention, the use according to the invention and also with the figures * * Furthermore, the present invention relates to the use of a tubular fuel cell according to the invention or a tubular fuel cell produced according to the invention in high-temperature fuel cells or combined heat and power plants. * *

With regard to further technical features and advantages of the use according to the invention, reference is hereby made explicitly to the explanations in connection with the fuel cell according to the invention, the method according to the invention, the energy system according to the invention and also with the figures.

Drawings Further advantages and advantageous configurations of the subject-matters according to the invention are illustrated by the drawings and explained in the following description. It should be noted that the drawings have merely a descriptive character and are, not intended to limit the invention in any form. In the drawings Fig. I shows a schematic, perspective view of one embodiment of a fuel cell according to the invention; Fig. 2 shows a schematic sectional view of one embodiment of a fuel cell according to the invention; and Figs. 3a-3g show schematic views for illustrating one embodiment of a functional layer system of a fuel cell according, to the invention.

The embodiment, shown in Figure 1, of a tubular fuelcell (high-temperature fuel cell, SOFC tube) 10 according to the invention has a partially porous, substantially cylindrically shaped support tube 11,12,13 serving as support for functional layers (hidden in Figure 1) Located internally, i.e. deposited on the inside of the support tube. Figure 1 shows that one end of the support tube 11,12,13 is closed by a cap section 12 made of a gas-tight material. On the opposite side there is formed a foot * section II (mounting flange, gas connection flange) which is likewise made of a gas-tight material and enabres a gas-tight connection of the support tube 11,12,13 to a support plate (not illustrated) -optionally without additional sealing by glass-like materials. ****

Figure 1 further shows that a gas-permeably porous, substantially hollow-cylindrical; middle section 13 extends between the gasrtight foot section 11 and the gas-tight cap section 12. On the inside of the tube wall, porous in this section 13, is deposited the functional layer system (hidden in Figure 1) which can be subjected to a gas, for example an oxygen-containing gas, such as air, from outside the support tube 11,12,13 through the pores of the middle section 13 and can be subjected to another gas, for example a fuel gas, such as hydrogen, methane, etc.) from the interior of the support tube 11,12,13.

The dashed lines indicate that, in the connecting zones, adjoining tight and porous sections may be formed in an interlocking manner.

Figure 1 further shows that a gas supply lance 14 projects into the interior of the support tube 11,12,13, which lance is designed to subject the interior to the gas, in particular fuel gas. Figure 1 illustrates that the cap section 12 may have concave recesses and/or struts I 2a for centring and/or stabilising the gas supply lance.

In principle, in particular on a reversal of the layer sequence of the functional layer system -a reverse gas supply is possible, namely of the interior of the support tube 11,12,13 with an oxygencontaining gas and the external surroundings of the support tube 11,12,13 with fuel gas. It is likewise possible to deposit the functional layer system in the same or reverse layer sequence on the outside of the porous section 13.

Figure 2 illustrates that the functional layer pack 21-28 situated in the tube interior 11,12,13 divided up such that the functional layers 26,25,21 are subdivided along the support tube 11,12,13, so that two "half-tubes" A,B result. The flow S is guided from the foot 11 of the tube 1112,13 to the head 12 via one functional layer half-tube (half-tube) A. and from the head 12 back to the foot 13 via the other functional 30. layer half-tube (half-tube) B. The two half-shells A,B are electrically connected to one another at the head 12 of the tube 11,12,13 via a ring conductor 21 a. Between the two half-tubes A,B are formed two regions 23 which space the half-tubes A,B and may also be called joints, of which however only one is marked in Figure 2, since the other lies on the side facing away from the observer. The regions 23 spacing the half-tubes A,B extend in the longitudinal direction L of the support tube 11,12,13 and initially remain unprinted during the production of the functional layer pack 2 1-28. In order to seal these unprinted regions 23 gas-tightly, in particular without producing an electronic, ionic or gas-related short circuit, a gas-tight, electrically or ionically insulating insulation layer 24 is deposited, in particular subsequently, on each of the unprinted regions 23, in particular which layer fills the respective unprinted region 23. The insulation layer 24 may in this case be printed onto the respective region 23 in particular from outside and in doing so overlap adjoining edge regions of the half-tubes A,B, so that the insulation layer 24 is formed partly between the support tube 11,12,13 and the edge sections of the half-tubes AB.

Figure 1 shows that the functional layer system 2 1-28 further that the at least partly exposed functional layer 21, in addition to the subdivision by the region 23 extending in the longitudinal direction L of the support tube and subsequently printed with the insulation layer 24, is subdivided by regions 22 extending in the direction of the circumference U of the support tube 11,1213, so that in each case four functional layer sections 21 spaced from one another, in particular axially with respect to the longitudinal direction L of the support tube 11,12,13, result. The functional layer 21 may be in particular an anode layer 21, the subdivided anode layer sections 21 serving as anodes which form, with functional layer sections, serving as electrolytes and cathodes, of a similarly segmented, underlying electrolyte layer (hidden in Figure 2) and an, in turn, underlying, similarly segmented cathode layer (hidden in Figure 2). eight cathode-electrolyte-anode S units, which may also be called segments. Figure 2 shows that the sealing of the two unprinted regions 23 is effected by in each case one gas-tight insulation layer 24 which is printed transversely to the cathode-electrolyte-anode units (segments) and extends in particular parallel to the two strings. 5*

S *5*S

S

*5***e

S

Figures 3a to 3g show schematic views for illustrating one embodiment of a functional layer system 21-28 of a fuel cell 10 according to the invention.

Figures 3a and 3c show cross-sections through the functional layer system shown in plan view in Figure 3b. In Figure 3b, the left-hand, thick, dash-dot, verticaHine provided with viewing direction arrows pointing to the left, marks the section plane of the cross-section shown in Figure 3a, and the right-hand, thick, dash-dot, vertical line provided with viewing direction arrows pointing to the right, marks the section plane of the cross-section shown in Figure 3c.

Figures 3d and 3e are greatly enlarged details from the topmost region of Figure 3a and a region at the top left in Figure 3b. Correspondingly, Figure 3d shows a greatly enlarged crpss-section and Figure 3e shows a greatly enlarged plan view.

Figures 31 and 3g are greatly enlarged details from the topmost region of Figure 3c and a region at the top right in Figure 3b. Correspondingly, Figure 3f shows a greatly enlarged cross-section and Figure 3g shows a greatly enlarged plan view.

In the plan views of Fig. 3b, Fig. 3e and Fig. 3f, uniform line marking (dash-dot-dash lines, dash-dash-dash lines, thin continuous lines, thick continuous lines) has been carried out. Here, the same line marking has been used for the reference lines, of the associated reference symbols.

Thus, the dash-dot-dash lines mark a lowermost functional layer system level, in particular the anode layer 21, in which are formed anodes (anode layer sections) 21 which are partly separated from one another by anode insulation sections 22 te..'.

* formed in the same plane and likewise marked by dash-dot-dash lines. Also formed in this lowermost functional layer system level is an electrical ring conductor 21a, which is therefore likewise marked by dash-dot-dash lines.

The dash-dash-dash lines mark a functional layer system level lying above the level of the anode layer 2122, in particular the intermediate layer or electrolyte layer 25, in which are formed electrolytes (electrolyte layer sections) 25 which are parfly separated from one another by interconnectors 28 formed in the same plane and likewise marked by dash-dash-dash lines.

The thin continuous lines adjacent thereto mark a functional layer system level)ying above the level of the intermediate layer or electrolyte layer 25, in particular the cathode layer 26, ri which are formed cathodes (cathode layer sections) 26 which are partly separated from one another by cathode insulation sections 27 formed in the same plane and likewise marked by thin continuous lines.

The thick continuous lines, which border the vertical strips denoted by the reference symbol 24, mark insulation layers 24 lying above the levels explained above.

The uppermost strip, which can be seen in Figures 3b, 3f and 3g, illustrates that the functional layer system 2128 is firstly printed on a carrier sheet.

For reasons of clarity, riot all reference symbols have been marked in the general illustrations of Figs. 3a to 3c. FQr a better understanding, in the context of the description of Figures 3a to 3d, reference symbols are also mentioned which are marked only in the enlarged illustrations of Figs. 3d to 3g. but the meaning of which is clear on account of the uniform reference symbol assignment, the uniform line marking and the comparability of the general illustrations in Figures 3a to Sc with the greatly enlarged illustrations in Figures 3d to 3g.

The cross-sections of Figs. 3a, 3c, 3d and 3d show that the functional layer system 21 is of sandwich-like form and comprises a cathode layer 26,27, an underlying 0*e** * electrolyte layer 25,28 and an, in turn, underlying anode layer 21,22. *

**.*** e Figures Sb, 3e and 3g show plan views of the cathode layer 26 of the functional layer system 21-28. In these figures, in particular Figure 3b illustrates that the cathode layer 26; the electrolyte layer 25 and the anode layer 21 are subdivided by an initially unprinted region 23 which later, on deposition of the functional layer system 21-28 on a support tube 11,12,13 extends in the longitudinal direction L of the support tube 1112,13 (see Figure 2) and which 23 subdivides the cathode rayer 26, the electrolyte layer 25 and the anode layer 21 such that two functional layer sections A,B (half-layers), spaced in particular circumferentially with respect to the circumference U of the support tube 11,12,13 (see Figure 2), result. On the deposition of the functional layer system 21-28 art the support tube 111213, the functionaC layer system 21-28 is also shaped into a tube, so that the two functional layer sections A,B (half-layers) may also be called functional layer half-tubes A,B.

In addition to the region 23 extending later in the longitudinal direction L of the support tube 11,12,13, the cathode layer 26, the electrolyte layer 25 and the anode layer 21 are subdivided by regions 22,27,28 which later extend in the direction of the circumference U of the support tube 11,12,13, there result in the cathode layer 26, the electrolyte layer 25 and the anode layer 21 in each case a total of two times eight functional layer sections 26,2521 which are spaced from one another axially with respect to longitudinal direction L of the support tube 11,12,13.

The regions (cathode insulation layer sections) 27 which axially space the functional layer sections of the cathode layer 26 (cathode layer sections), and also the regions (anode insulation layer sections) 22 which axially space the functional layer sections of the anode layer 21 (anode. layer sections) may be filled in particular with a gas-tight, electrically insulating material.

The regions (interconnectors) 28 which axially space the functional layer sections 25 of the electrolyte layer 25 (electrolyte layer sections) may be filled in particular with : a gas-light, ionicallyinsulating and electrically conductive material and thereby both * ionically insulate the electrolyte layer sections 25 from one another and serve as interconnectors 28 for series connecti6n of adjacent cathode sections 26 and anode sections 21 of different cathode-electrolyte-anode units 26,25,21.

* *..* The cross-sections in Figs. 3a 3c, 3d and 3f illustrate that the cathode layer sections 26, the electrolyte layer sections 25 and the anode layer sections 21 are arranged slightly offset from one another, so that in each case a cathode layer section 26 overlaps an adjacent anode layer section 21, an interconnector 28 being formed in electrolyte layer 25 in the overlapped region. This makes it possible to connect adjacent cathode-electrolyte-anode units 26,25,21 in series to one another b to form strings which extend in each case through the left A functional layer section and through the right functional layer section 8 in the longitudinal direction L of the support tube 11,12,13 and are connected in series among one another via an electrical ring conductor 21a which is formed in the anode layer 21 from the anode material.

The cathodes 26, electrolytes 25 and anodes 21 of cathode-electrolyte-anode units 26,25,21 belonging to different strings are in this case electrically and ionically insulated from one another the regions 23 which extend in the longitudinal direction L of the support tube 11,12,13, and which respectively spaces the cathode layer section of the cathode layer 26 and the electrolyte layer sections of the electrolyte layer 25 and the anode layer sections of the anode layer 21, in particular circumferentially with respect to the circumference U of the support tube 11,12,13.

Furthermore, Figures 3b, 3e and 3g illustrate that, on the region 23 subdividing the cathode layer 26, the electrolyte layer 25 and the anode layer 21 and extending En the longitudinal direction L of the support tube 11,12,13, and also on regions 23 laterally adjoining the cathode layer 26, the electrolyte layer 25 and the anode layer 21 and initially unprinted, there are deposited two gas-tight or gas-tightly sintering, electrically and ionically insulating, insulation layer 24 which fill the initially unprinted regions 23.

The cathodes 26 for series connection of the strings in each case the anodes 21 of *,....: the adjacent cathode-electrolyte-anode units 26,25,21 may overlap by a certain distance (dl), in particular in the longitudinal direction L of the tube 11,12,13 of about 8 cm, for example of about 2mm, for example of 1.94 mm The electrochemically active area (d2) of an individual cathode-electrolyte-anode unit 26,25,21 may have, for example, a height, in particular in the longitudinal direction L of the tube 1112,13, of about 6cm, of about 6mm, for example 5.88 mm. The area (d3) required for the series connection of adjacent cathode-electrolyte-anode units may have, for example, a height, in particular in the longitudinal direction L of the tube 1112,13, of about 8 cm, S about 4 mm, for example 3.94 mm. And the S electrochemically active area of the functional layer system overall may have, for example, a height (d4), in particular in the longitudinal direction L of the tube 11,12,13, of about 8cm, for example 74.62mm.

In the context of one embodiment of the method according to the invention, in this case the functional layer system 21-28 shown in Figures 3a to 3g is printed on a sleeve by means of round screen printing, the regions 23 initially remaining unprinted. In a further method step, two insulation layers 24 are then printed on, the unprinted region 23 in the middle in Figure 3b being covered by an insulation layer 24 and the two outer unprinted regions 23, which are formed on the sleeve in the form of a common unprinted region 23, being covered by the other insulation layer 24.

In the context of another embodiment of the method according to the invention, in this case the functional layer system 2 1-28 shown in Figures 3a to 3g is printed by means of screen printing on a flat sheet which is bent into a hollow cylinder, the two outer unprinted regions 23 adjoining one another to form a joint 23, the joint 23 then being printed with an insulation layer 24, for example by means of round screen printing. The' middle, initially unprinted, region 23 may in this case' be printed with the insulation layer 24 both in the flat shape and in the bent shape of the sheet. 25. 0* *

In the context of the embodiment shown in Figures 3a to 3g, the cathode layer 26 and the insulation layers 24 are the outermost layers with respect to the sleeve or the bent sheet. a.

30. If such an arrangement is placed on a mould core which can be introduced into a cavity of an injection mould in such a way that the functional layer system 21-28 is spaced from the inner wall of the cavity, a support tube 11,12,13 whose inside is provided with the functional layer system 21-28 can be formed by injecting a ceramic injection moulding component into the cavity, the cathode layer 26 and the insulation layers 24 adjoining the support tube 11,1213 and the anode layer 21 being exposed and freeiy ccessible from the interior of the support tube 11,12,13.

If, however, such an arrangement is placed on an inner wall of a cavity of an injectiOn thould and a mould core is introduced into the cavity in a manner spaced from the functional layer system 21-28, a support tube 11,12,13 whose outside is provided with the functional layer system 2 1-28 can be formed by injecting a ceramic injection moulding component into the cavity, the anode layer 21 adjoining the support tube 11,12,13 and the cathode layer 26 and the insulation layers 24 being exposed and freely accessible from the external surroundings of the support tube 11,12,13.

In the case of a reverse layer sequence, in which the anode layer 21 is deposited on the electrolyte layer 25 and the electrolyte layer 25 is deposited on the cathode layer 26, the anode layer 21 and the insulation layers 24 would be the outermost layers with respect to the sleeve or the bent sheet.

In the case where such an arrangement is placed on the mould core of en injection mould, a support tube 11,12,13 whose inside is provided with the functional layer system 21-28 can be formed, the anode layer 21 and the insulation layers 24.

adjoining the support tube 11,12,13 and the cathode layer 26 being exposed and freely accessible from the interior of the support tube 11,12,13. *. a

In the case where such an arrangement is placed on the cavity inner wall of an fle*S * injection mould, a support tube 11,12,13 whose outside is provided with the functional layer system 21-28 can be formed, the cathode layer 26 adjoining the support tube 11,12,13 and the anode layer 21 and the insulation layers 24 being exposed and freely accessible from the external surroundings of the support tube ** 11,12,13.

Claims (1)

1. <claim-text>Claims: 1. Tubular fuel cell (10) having a support tube (111213) which serves as a support for a functional layer system (21-28), claracterised in that at least one S of the functional ayers (21,25,26) is subdivided by at least one region (23) extending in the longitudinal direction (L) of the support tube (11,12,13)3 so that at least two functional layer sections (A,B) spaced from one another result.</claim-text> <claim-text>2. Tubular fuel cell (10) according to Claim 1, wherein a functional layer (26) at least partly adjoining the support tube (11,12,13) and/or an at least partly exposed functional layer (21) is subdivided by at least one region (23) extending in the longitudinal direction (L) of the support tube (11312,13), so that at least two functional layer sections (A,S) spaced from one another result.</claim-text> <claim-text>3. Tubular fuel cell (10) according to Cairn 1 or 2, wherein a gas-tight, electrically insulating, in particular electricallyand ionically insulating, inner insulation layer (24) is formed between the support tube (1112,13) and the region (23) which extends in the longitudinal direction (L) of the support tube (11,12,13) and which spaces the functional layer sections (A,B) of the functional layer (26) at least partly adjoining the support tube (1112,13), and/or wherein the region (23) which extends in the longitudinal direction (L) of the support tube (11,12,13) and which spaces the functional layer sections (A,B) of the at least partly exposed functional layer (21) is covered by a gas-tight, electrically insulating, in particular electrically and ionically insulating, exposed insulation layer (24).* 4. Tubular fuel cell (10) according to Claim 3, wherein the inner insulation layer (24) and/or the exposed insulation layer (24) extends in the form of a strip in the longitudinal direction (14 of the support tube (1112,13).* 5. Tubular fuel cell (10) according to Claim 3 or 4, * . . wherein the inner insulation layer (24) overlaps edge sections, of the functional layer sections (AB) of the functional layer (26) at least partly adjoining the support tube (11,12,13), which adjoin the spacing region (23) extending in the longitudinal direction (L) of the support tube (11,12,13), andfor S wherein the exposed insulation layer (24) overlaps edge sections, of the functional layer sections (A,B) of the at least partly exposed functional layer (21), which adjoin the spacing region (23) extending in the longitudinal direction (L) of the support tube (11,12,13) 6. Tubular fuel cell (10) according to one of Claims 3 to 5, wherein the insulation !ayer material (24) comprises a magnesium silicate, in particular forsterite.7. Tubular fuel cell (10) according to one of Claims ito 6, wherein the functional layer (26) *at (east partly adjoining the tube body (11,12,13) is a cathode layer and the at least partly exposed layer (21) is an anqde layer, or wherein the functional layer at (east parUy adjoining the tube body is an anode layer and the at least partly exposed layer is a cathode layer.8. Tubularfuelcell(10) according to one of Claims ito 7, wherein the subdivision of the functionaL layer (26) adjoining the support tube (11,12,13) and/or of the exposed functional layer (21) and/or of an intermediate functional layer (25) formed between the functional layer (26) at least partly adjoining the tube body (11,12,13) and the at least partly exposed functional layer (21) is effected in such a way that with respect to the functional layers (21-28) two functional layer half-tubes (A,B) result, in particular wherein the functional layer half-tubes (A,B) are spaced from one another by two regions (23) extending in the longitudinal direction (L) of the support tube (11,12,13). 4.9. Tubular fuel cell (10) according to Claim a, wherein the regions (23) which *44* : extend in the longitudinal direction (L) of the support tube (11,12,13) and which S.....S Sspace the functional layer half-tubes (A B) is partly or completely titled with an insulation layer material (24).10. Tubular fuel cell (10) according to one of Claims I to 9, wherein the current flow within the functional layer system (21-28) is directed within *a first functional layer half-tube (A) from an open end (11) of the support tube (1112,13) to a closed end (12) of the support tube (11,12,13), and is directed via the second functional layer half-tube (B) from the closed end (12) of the support tube (11,12,13) back to the closed end (11) of the support tube (11,12,13).11. Tubular fuel cell (10) according to one of Claims 8 to 10, wherein an electrical ring conductor (21a), which electrically connects to one another two functional layer sections of a functional layer (21) subdivided by a region extending in the longitudinal direction (L) of the support tube (11,12,13), is formed in the functional layer system (21-28), in particular wherein the electrical ring conductor (21a) is formed in the region of a closed end (12) of the support tube (11,12,13).12. Tubular fuel cell (10) according to one of Claims I to 11, wherein the functional layer system (2 1-28) is deposited on the inside or on the outside, in particular the inside, ofthesupporttube(11,12,13).13. Method for producing a tubular fuel celr (10), in particular according to one of CLaims ito 12, comprising the method steps: a) printing a sleeve or a sheet with a functional layer system (21-28) * comprising a cathode layer (26), an anode layer (21) and an electrolyte layer (25) lying therebetween, wherein at least the functional layer (21) printed last, in particular the cathode layer, is subdivided by at least one * 30 unprinted region (23), so that at least two spaced functional layer sections **. (A,B) (half-layers) result, b) printing the uriprinted region (23) of the functional layer (26), printed last in method step b), with a gas-tight or gas-tightly sintering, electrically insulating, in partccular electrically and ionica)ly insulating, insulation layer (24), c) forming a support tube (11,12,13), provided with the functional layer system (21-28), by means of ceramic injection moulding, wherein the sleeve or sheet carrying the functional layer system (21-28) is overmouldeci or back-rnoulded.14. Method according to Claim 13, wherein in method step a) the functional layer system (21-28) is printed in such a way that the cathode layer (26), the electrolyte layer (25) and the anode layer (21) are subdivided by at least one common unpririted region (23).15. Method according to Claim 13 or 14, wherein the method further comprises the method steps bi) and b2): bi) bending the sheet to form a hoflow cylinder, wherein two mutually opposite sides of the sheet adjoin one another to form a joint (23), b2) printing the joint (23) with a further gas-tight or gas-tightly sintering, electrically insulating, in particular electrically and ionically insulating, insulation layer (24), wherein the method step bi) and b2) take place after method step a), wherein method step b) takes place before method step bi) or before, during or after method step b2). * * * . * * * * .S..... * S</claim-text>