WO2013045230A1

WO2013045230A1 - Method for the production of a solid electrolyte fuel cell

Info

Publication number: WO2013045230A1
Application number: PCT/EP2012/067207
Authority: WO
Inventors: Carsten Schuh
Original assignee: Siemens Aktiengesellschaft
Priority date: 2011-09-27
Filing date: 2012-09-04
Publication date: 2013-04-04

Abstract

The invention relates to a method for producing a solid electrolyte fuel cell, wherein at least one component for forming the solid electrolyte fuel cell is produced by forming layers on a substrate. An aerosol deposition process is used to form the layers, suitable aerosol particles being used for each layer. Furthermore, an aerosol deposition step without subsequent tempering is carried out on an interconnector plate on the cathode side in order to form a Cr evaporation barrier layer, wherein ceramics in an spinel structure are used as aerosol particles.

Description

description

Process for producing a solid electrolyte fuel cell

The invention relates to a method for producing a solid electrolyte fuel cell according to the preamble of An ^¬ claim 1. Generic solid electrolyte fuel cells are from the

Known in the art. ^¬ ground laying principles of solid oxide fuel cells, in art as SOFC (Solid Oxide Fuel Cell) go for example known from International Publication No. WO 2011/019455 Al, out. These fuel cells consist essentially of a cathode and an anode, between which a solid electrolyte is arranged.

In operation of the fuel cell with a flow of current through an external load, a gaseous fuel supplied to an anode oxidizes, resulting in a release of electrons that flow through the external load and reduce oxygen at a cathode. The charge flow in the external circuit is compensated by an ion transport in the electrolyte. Thus, oxygen is dissociated from the air at the cathode and converted into oxygen ions which migrate through the electrolyte and react with the fuel at the interface between the anode and the electrolyte. A oxidke ^¬ ramische fuel cell operates with an operating temperature above 500 ° C, at which a coming therein for use solid electrolyte has a sufficient ionic conductivity for oxygen ions.

In said publication WO 2011/019455 AI will continue to go on the concept of a solid electrolyte battery ^¬. This is based on the principle of action of solid electrolyte fuel cells under additional Providence at least one memory element. Instead of a feeder one Fuel is provided at the anode a reservoir, which includes on the one hand a porous, that is, gas-permeable, oxidizable material and a redox couple. For a reconstruction loadable operation of the solid electrolyte battery exiting oxygen ions of an oxidizable SpeI ^¬ cherschicht a storage element are supplied to the anode. In the SpeI ^¬ cherschicht a redox reaction takes place in such a way that be in egg ^¬ nem charging operation of the solid electrolyte battery is reduced, the active redox components of the storage layer and oxidized in accordance with a discharge operation. Accordingly, oxygen molecules or oxygen ions are transported from the storage element to the anode in a charging process.

With regard to the properties and production of the electrolyte layer and of other layers, solid electrolyte batteries and solid electrolyte fuel cells have some similarities. Therefore, in addition, the term solid electrolyte fuel cell both a solid electrolyte fuel cell ^¬ material itself and the rechargeable concept is understood egg ner solid electrolyte battery.

For some predominantly ceramic layer structures of a solid electrolyte fuel cell such as a Zr0 ₂ ^~

Electrolyte layer, oxide ceramics used for cathode and anode as well as high chromium-containing metallic interconnectors incl. Contact and protective layers is currently a layered structure

By screen printing, wet spraying, sol-gel and nano-suspension process, also referred to as dip and spin coating, further applied a layer structuring by means of electrophoretic deposition and by plasma spraying and physical vapor deposition (PVD). Almost all the methods have in common that during the process high per ^¬ process temperatures are required.

Deposition by means of aerosol deposition can avoid these disadvantages of a high process temperature. The deposition by means of aerosol deposition for producing a Fuel cell, for example from Scripture "Anode Supported SOFC with GDC Barrier Layer Deposited by Aerosol Deposition Method, Proceedings of the ASME 2010, 8th Interna ^¬ tional Fuel Cell Science, Engineering and Technology Confer- ence, S.351-357", as well as from However, the layers described in this prior art are due to their composition and tightness unge ^¬ is, the migration of atomic chromium from the alloy of the interconnector plate countries ^¬ to verhin in the fuel cell. However, this is largely responsible for the Langzeitdegradation of Festleketrolyt fuel cells, and in besodere by the deposition of chromium in or at the cathode In addition to this influence based on an electrochemical competing reaction in the cathode, chromate ome also responsible for a detrimental change of fuel cell power collectors, which are based on a purely chemical interaction of the chromium species with Mn304 precipitates in the current collector. Consequently, it turns out to be technically necessary to prevent chromium diffusion, in particular by means of a suitable chromium vapor barrier layer to prevent or significantly reduce ver ^¬ .

The present invention is therefore based on the object of specifying a method for producing a solid electrolyte fuel cell, with which the layer structures can be produced at lower process temperatures, at the same time the formation of a suitable chromium vapor barrier layer is to be made possible. This object is achieved by a manufacturing method having the features of patent claim 1. In a method for producing a solid electrolyte fuel cell is provided to generate at least a component for Bil ^¬ dung of the solid electrolyte fuel cell by layering on a respective substrate. In this case, according to the invention, an aerosol deposition method is used for layer formation, wherein aerosol particles adapted to the respective layer are used and wherein an optional tempering takes place for setting a respective microstructure of the layer.

Furthermore, according to the method according to the invention for forming a chromium evaporation barrier layer on a cathode-side interconnector plate, an aerosol deposition takes place without subsequent heat treatment, ceramics in a spinel structure being used as aerosol particles.

The spinel structures deposited by an aerosol deposition process prove to be sufficiently dense to inhibit migration of chromium atoms through the layer.

According to the invention, an additional use of an aerosol deposition method for layer formation is provided for different layers of a preferably planar solid electrolyte fuel cell. The method provides for a very low process and substrate temperature, for example at room temperature or to only about 300 ° C before.

The aerosol deposition process has been significantly developed by the Japanese Research Institute AIST (National Institute of Advanced Industrial Science and Technology) and is also known by the acronym ADM (Aerosol Deposition Method).

The aerosol deposition method used sub-ym-powder particles, of which first dispersed in a carrier gas such as 0 _2, N _2, Ar, He, air, etc. to form an aerosol ^¬ the. The aerosol is finally transported via a nozzle into a Un ^¬ terdruckkammer and thereby via a Druckdiffe- highly accelerated to eventually strike a substrate. As a result, so much kinetic energy is released that an in-situ sintering process is used which forms an almost completely dense nanocrystalline ceramic layer at very low process and substrate temperatures, for example at room temperature up to about 300 ° C.

By means of this method, both high-density and porous ceramic layers or metallic layers with thicknesses between approximately 1 and 500 μm can be deposited on different substrates.

An optional tempering by short-term heating to 400 - 800 ° C, for example via a furnace process or by laser treatment, leads to a rapid microstructure coarsening. This optional process step of annealing thus offers a spectrum for the layer formation of high-density, fine to coarse-grained layers up to highly porous, multi-phase composite structures.

The method according to the invention makes it possible to produce both porous and high-density layer structures at low process temperatures with the desired microstructure in a cost-efficient manner on the respective substrates.

Another advantage of using the aerosol deposition method for film formation at a Festelekt ^¬ rolyt fuel cell is given by the possibility of a non-sinterable processability and wetting in itself by decomposition, chemical reactions to high sintering temperatures, etc., incompatible starting materials. By contrast, only comparable material compositions would be difficult to prepare in comparable alternative processes. Another advantage is the ability to coat arbitrarily shaped layers, not just planar contours and surfaces. A particular advantage of using the aerosol deposition method for film formation in the solid oxide fuel cell electric ^¬ lyt is given by the possibility of circuit provide an optional annealing step in the presence, with the grain coarsening of the nanocrystalline structure in the initial state is enabled. Depending on whether this anneal is a ^¬ set or not, thus the possibility of nanoscale high-density layer or microcrystalline to decor with dark ^¬ th yields.

Besides, by the use of a mixture of ceramic and polymer, ie, burn-out particles in the aerosol an either high density, in particular gas-tight layer or a porous, in particular gas-permeable layer can be obtained after combustion of the burnable particles at sufficiently ho ^¬ hen temperatures.

Another advantage of using the aerosol deposition process for layer formation in the case of the solid electrolyte fuel cell results from the low necessary

Layer thickness to obtain a gas-tight layer, resulting in more advantageous before ^¬ manner, for example, to an additional reduction of the lowering ^¬ passage resistance for oxygen ions in the case of the electrolyte. The high-density configuration of the layers also advantageously leads to an additional reduction of a respective surface resistance of the layers.

By a slight influence on the substrate materials, the aerosol deposition method has particular advantages for the

Layer formation in a solid electrolyte fuel cell. In ^¬ way of example here are a reduced tendency to Interdiffu- sion, a reduction of thermally induced degradation and decomposition as well as mechanical stresses, emphasized a reduction in a formation of undesirable boundary layer phases and oxide layers. Further embodiments and embodiments of the invention are the subject of the dependent claims.

In the following the invention and its embodiments will be explained in more detail with reference to the drawing. The only FIG. shows a schematic cross-sectional view of a

Layer structure of a solid electrolyte fuel cell according to an embodiment of the invention. The in FIG. The illustrated solid electrolyte fuel cell includes a plurality of layers which are subsequently laminated in the direction from the cathode shown in the drawing above to the anode shown in the drawing below.

In the upper part of the drawing, a cathode-side interconnector plate 5 is shown. While in the Vergangen ^¬ uniform due to high operating temperatures of 800 - 1000 ° C exclusively ceramic interconnector plates 5 on the basis of doped lanthanum chromites (lacros) were used, may be prepared by the usual today operating temperatures of an SOFC in regions between 600-800 ° C meanwhile me ^¬ tallische materials are used. Chromia forming Le ^¬ alloys, for example, ferritic steels are preferred since gradually materials for metallic Interkonnektorplat ^¬ th. Chromia-forming alloys are characterized in that, in contrast to other metal oxides they have a sufficiently high electrical conductivity. The disadvantage is the formation of volatile chromium compounds, also referred to as chromium evaporation. These arise under the operating conditions of the fuel cell and are deposited disadvantageously on or in the cathode. In order to suppress the chromium evaporation, according to the invention, a chromium vapor barrier layer 10, which is applied over the entire area on the cathode-side interconnector plate 5 in the ^{direction of} an electrolyte 50 of the fuel cell, is provided. According to one ^{embodiment of} the invention, this chromium ^vapor barrier layer 10 is applied in a highly dense manner by means of the aerosol deposition process while setting a layer thickness of preferably less than 10 μm. As an aerosol ^¬ particulate ceramics according to an embodiment of the invention employed in a spinel structure, used in particular CoMn- spinel. As shown in FIG. shown, covers the chromium evaporation barrier layer 10 preferably all in the direction of the electric ^¬ lyts 50 of the fuel cell facing structure of the interconnector plate 5. The structure of the interconnector plate 5 is determined through the air channels in which the oxygen of the cathode is supplied.

Individual solid electrolyte fuel cells are terkonnektorplatten beyond the In 5, which act designed as a planar elekt ^¬ generic connection devices together to form units of multiple cells. The interconnector plates 5 have gas channels formed therein.

The planar-shaped solid electrolyte fuel cells are manufactured individually and then stacked on top of each other and optionally sealed with a high-temperature sealing material.

Layer to improve the electrical contact between the ka- Thode side interconnector plate 5 having a cathode 25, a contact layer 20 on the side coated with the chromium ^¬ evaporation barrier layer 10 cathode-side ^¬ In terkonnektorplatte 5 is applied. The according to an exporting ^¬ approximately of the invention by means of the aerosol

Deposition method applied contact layer 20 is preferably made of a LaCuCo oxide. To ensure a deformable contact with the cathode layer 25 of the cell, a porous structure is set. The preferred

Layer thickness is 10 ym and more. The cathode-side interconnector plate 5 coated according to the preceding description with the chromium ^evaporation barrier layer 10 and the contact layer 20 is pressed against a presintered cathode layer 25 in a subsequent manufacturing process.

The cathode layer 25 forms a substrate and an electrical ^¬ specific contact layer for the cathode functional layer 30th

As the cathode functional layer 30 LSM compounds based on (La, Sr) MnÜ ₃ and / or LSCF compounds based on (La, Sr) (Co, Fe) 03 are used. Said compounds are referred to according to an embodiment in conjunction with ceramic mikbasierten electrolyte materials such as yttrium-stabilized zirconia (YSZ), even YSZ used, before ^¬ preferably in a direction indicated as 8YSZ composition having a concentration of 8 mol% Y ₂ O ₃ in ZrÜ ₂ . In an off ^¬ product variant, an admixture of another elec- rolytwerkstoffs, such as cerium-based Composition ^¬ gen, especially cerium gadolinium oxide, also called CGO be seen ^¬. The applied according to an embodiment of the invention by the aerosol deposition method Katho ^¬ the function layer 30 is gebil- det as a highly porous structure. The preferred layer thickness is 20 ym and Darun ^¬ ter.

A diffusion proves to 30 spilled strontium between the cathode functional layer 30 and electric ^¬ lyt 50th of from LSCF- compounds of the cathode functional layer as a problem to avoid these Sr-diffusion according to one embodiment of the invention, a diffusion barrier layer 40 to prevent Sr diffusion to the YSZ electrolyte when using LSCF on the cathode side. The applied according to an embodiment of the invention by the aerosol deposition method, diffusion barrier layer 40 is formed as a highly dense layer having a very small layer ^¬ thickness of preferably less than 1 ym. A thin one Diffusion barrier layer 40 proves to be favorable for the electrical resistance of the fuel cell.

As carriers for the above-mentioned ceramic layers either the anode is used, here, an anode layer shown in the drawings 70. Such a cell is then ^¬ be characterized as anodenge ^¬ assisted cell or as ASC (Anode Supported Cell). In an alternative variant serves as a carrier, the YSZ electrolyte layer itself, which is why this structure is referred to as ESC (Electrolyte Supported Cell). In a wide ^¬ ren alternative embodiment, constructed ^¬ the acts as a carrier a highly porous metal layer on the first anode layer 70 and then the other functional layers, ie anode functional layer 60, electrolyte 50, diffusion barrier layer 40, cathode the functional layer 30 and cathode layer 25th Due to the metallic nature of this anode-side support layer, this type of construction of the cell is then referred to as metal-supported cell or as MSC (Metal Supported Cell).

The actual electrolyte layer 50 is located in the middle of the cell. This electrolyte layer 50 is also formed according to an embodiment of the invention by means of the aerosol deposition process. The electrolyte material used is yttrium-stabilized zirconium dioxide, YSZ, preferably in a composition also designated 8YSZ with a concentration of 8 mol% Y ₂ O ₃ in ZrO ₂ . In an embodiment variant, an admixture of a further electrolyte material, in particular cerium-gadolinium oxide, CGO, may be provided. Alternatively, the entire electrolyte layer 50 may be formed of ceria and / or doped ceria. The applied according to an embodiment of the invention by the aerosol deposition method ^¬ electrolyte layer 50 is formed as a highly dense structure. The preferred layer thickness is 50 ym and below, ideally 10 ym and below. The demands on the underneath of the electrolyte 50 is ^¬ arranged anode functional layer 60 is a high open poro ^¬ intensity to ensure a gas transport to an electrochemical three-phase boundary area, and high electrical see conductivity to the released during oxidation of fuel gas electron unimpeded in the direction of the anode-side Interkonnektorplatte 90 derive. This anode radio ^¬ tion layer 60 is formed according to an embodiment of the invention also overall by the aerosol deposition method. The anode material used is a composite of 8YSZ or 3YSZ and / or CGO with nickel particles. The required high open porosity is in addition to a Gefügevergrö- berung also supported so that Adiabatic bare particles, for example of plastic or organic material incorporated ^¬ introduced in the course of aerosol deposition in the structure by means of a process executed by the aerosol deposition anneal which burn out at said annealing step or at subsequent operating temperatures. The preferred layer thickness is 20 ym and below.

A arranged beneath the anode layer 70 forms a sub ^¬ strat and an electrical contact layer for the anode functional layer 60. A contact network 80 based on nickel is used a IMPROVE ^¬ tion of the contact between the anode layer 70 and the anode-side interconnector plate 90th

Claims

claims

1. A method for producing a solid electrolyte fuel cell, wherein at least one component for forming the solid electrolyte fuel cell is generated by layer formation on a respective substrate, wherein the

Layering an aerosol deposition method is used, and wherein for the respective layer adapted aerosol particles are used,

characterized in that

to form a Cr evaporation barrier layer (10) on a cathode-side interconnector plate (5), an aerosol deposition takes place without subsequent heat treatment, ceramic materials in a spinel structure being used as aerosol particles.

2. The method according to claim 1,

characterized,

that aerosol deposition takes place to form a layer thickness of less than ten micrometers.

3. The method according to any one of claims 1 or 2,

characterized,

in that a CoMn spinel is used as the aerosol particle material.

4. The method according to claim 1,

characterized,

that aerosol deposition takes place without subsequent heat treatment to form a high-density barrier layer (40) to prevent Sr diffusion.

5. The method according to claim 4,

characterized,

that an aerosol deposition takes place to form a layer thickness of less than a micrometer.

6. The method according to any one of claims 4 and 5, characterized,

in that CGO is used as the aerosol particle material.

7. The method according to any one of the preceding claims,

characterized,

in that, to form a contact layer (20) on a cathode-side interconnector plate (5), an aerosol deposition with subsequent tempering takes place for setting a porous layer structure.

8. The method according to claim 7,

characterized,

that an aerosol deposition takes place to form a layer thickness of more than ten micrometers.

9. The method according to any one of claims 7 and 8,

characterized,

in that an LaCuCo oxide is used as the aerosol particle material.

10. The method according to any one of the preceding claims,

characterized,

that an aerosol deposition with subsequent tempering takes place in order to form a highly porous cathode functional layer (30).

11. The method according to claim 10,

characterized,

that aerosol deposition takes place to form a layer thickness of less than twenty micrometers.

12. The method according to any one of claims 10 and 11,

characterized,

in that LSM compounds and / or LSCF compounds are used as the aerosol particle material.

13. The method according to claim 12,

characterized, in that the LSM compounds and / or LSCF compounds used as aerosol particle material are mixed with 8YSZ and / or 3YSZ and / or zirconium oxide and / or CGO.

14. Solid electrolyte fuel cell, which is at least teilwei ^¬ se made according to a method according to one of claims 1 to 13.

15. Solid electrolyte battery, which is at least partially manufactured according to a method according to one of claims 1 to 13.