WO2013190164A1 - Membrane électrolytique à oxyde solide placée sur un support comportant des nervures de silicium dopé pour des applications dans des micropiles à combustible à oxyde solide - Google Patents

Membrane électrolytique à oxyde solide placée sur un support comportant des nervures de silicium dopé pour des applications dans des micropiles à combustible à oxyde solide Download PDF

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Publication number
WO2013190164A1
WO2013190164A1 PCT/ES2013/070406 ES2013070406W WO2013190164A1 WO 2013190164 A1 WO2013190164 A1 WO 2013190164A1 ES 2013070406 W ES2013070406 W ES 2013070406W WO 2013190164 A1 WO2013190164 A1 WO 2013190164A1
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WO
WIPO (PCT)
Prior art keywords
electrolytic
silicon
membrane
doped silicon
ribs
Prior art date
Application number
PCT/ES2013/070406
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English (en)
Spanish (es)
Inventor
Iñigo GARBAYO SENOSIAIN
María de les Neus SABATÉ VIZCARRA
Marc SALLERAS FREIXES
Albert TARANCÓN RUBIO
Alex MORATA GARCÍA
Original Assignee
Consejo Superior De Investigaciones Científicas (Csic)
Fundació Institut De Recerca En Energia De Catalunya (Irec)
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Application filed by Consejo Superior De Investigaciones Científicas (Csic), Fundació Institut De Recerca En Energia De Catalunya (Irec) filed Critical Consejo Superior De Investigaciones Científicas (Csic)
Publication of WO2013190164A1 publication Critical patent/WO2013190164A1/fr

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1097—Fuel cells applied on a support, e.g. miniature fuel cells deposited on silica supports
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04007—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids related to heat exchange
    • H01M8/04037—Electrical heating
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/12—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte
    • H01M2008/1293—Fuel cells with solid oxide electrolytes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Definitions

  • the invention is located within the area of microelectronics, more specifically in the manufacture of microsystems and the energy production sector.
  • the invention relates to solid oxide micro fuel cells, in particular to increasing the effective area of self-supporting electrolytic membranes.
  • micro-batteries and the micro fuel cells appear to be the most viable to manufacture, due to their high lifetime, high energy density and integration capacity.
  • micro fuel cells In the face of micro-batteries, nowadays developed and marketed as an energy source for portable devices, micro fuel cells have recently received great interest from the community scientific Although the concept has been known for decades (for large-scale energy production), now the goal has been to develop them on a small scale, for applications in the low power regime. Advantages such as its high energy density, the emission of non-polluting waste (water) and the possibility of avoiding possible moving parts (micro motors, micro turbines ...) make micro fuel cells really attractive.
  • electrolyte acts as a barrier for electrons that are exchanged in redox reactions, forcing them to travel an external circuit and thus generating the electric current.
  • electrolyte must allow the passage of certain ions through it, in order to complete the ion exchange between the two reactions.
  • the different types of fuel cell differ basically in the material that the electrolyte is made of and, as a consequence, in the ionic species that are exchanged through it during the process.
  • PEMFC polymeric electrolytic membrane fuel cells
  • SOFC solid oxide fuel cells
  • the electrolyte is made of a protonic conductive polymer (H + )
  • H + protonic conductive polymer
  • SOFC solid oxide fuel cells
  • the reactions that occur on each side of the electrolyte are the reduction of oxygen to oxide ions in the cathode (O2 + 2e ⁇ 20 2 ⁇ ) and the oxidation of fuel (3 ⁇ 4, for example) to protons in the anode (3 ⁇ 4 2H + + 2e ⁇ ).
  • the electrons generated in this reaction travel through an external circuit until they reach the cathode, thus closing the electronic exchange in the reaction and generating the electric current.
  • Protons (H + ) and ions (0 2 ⁇ ) combine well in the cathode (in PEMFCs), or in the anode (SOFC) forming 3 ⁇ 40 as a residue.
  • SOFCs solid oxide micro fuel cells
  • the invention presented here proposes a new approach to the objective of obtaining self-supported membranes of large area, with the aim of improving the maximum power achievable in a single SOFC thus improving its energy density.
  • the invention consists in the development and manufacturing of large surface solid oxide micro fuel cells.
  • the micro fuel cells are based on self-supported membranes on silicon-based micro platforms.
  • the process includes the manufacture of electrolytic membranes based on thin ceramic layers and the inclusion of electrodes on both sides of the membrane.
  • a unique aspect of the invention is the manufacture of the electrolytic membrane.
  • This membrane is manufactured supported on the silicon platform, in whose center a silicon-free area is defined, where the membrane is located.
  • the electrolytic membrane can be made of any electrolytic material typically used in SOFC, for example YSZ or CGO.
  • the material is deposited by means of any thin layer deposition technique, including pulsed laser deposition (PLD), chemical vapor vapor deposition (CVD), sputtering, evaporation ... and can comprise a thickness range between 5 nm and the 5 ⁇ .
  • PLD pulsed laser deposition
  • CVD chemical vapor vapor deposition
  • sputtering evaporation ...
  • Another unique aspect of the invention is the use of silicon ribs as a support for electrolytic membranes, since they have larger areas than usual. During the manufacturing process of the silicon platform that supports the membranes, a series of silicon ribs is defined by crossing the silicon-free zone for the membrane. These nerves act as a support for the ceramic membrane, thus allowing the silicon-free zone to be larger than normal.
  • the membrane may have some dimensions of between 500x500 ⁇ and 50x50 mm, taking into account that part of this area will be occupied by the nerves.
  • Doped silicon nerves have a thickness between 1 and 50 ⁇ and a width between 1 and 200 ⁇ . Being crosslinked, they define a series of singular membranes that, together, form the membrane of large area. These singular membranes can have different geometries, depending on the design of the network of nerves, including the circular, square, hexagonal, triangular geometry ... The dimensions of these singular membranes must always be greater than the width intended for the silicon ribs that define them.
  • the geometry of the large area membrane can also vary depending on the design of the nerve network, in order to optimize the distribution of the singular membranes. In this sense, large area membranes can comprise series of singular membranes between 2x2 and 50x50 membranes.
  • the electrodes are deposited (anode and cathode). These electrodes can be made of any metal, for example Pt, Ag, Ni ... but also of ceramic materials or cermets. The electrodes can be deposited using the same thin layer deposition technique as for the electrolyte, or a different one depending on the material chosen as the electrode.
  • Another particular aspect of the invention is the use of doped silicon ribs also as current collectors for one of the electrodes, as well as as support ribs.
  • doped silicon ribs also as current collectors for one of the electrodes, as well as as support ribs.
  • both electrodes it allows the electrical contacts of both electrodes to be made from the same side of the silicon platform, through the use of buried doped silicon tracks that contact the network of nerves in the membrane and the contact point.
  • the invention contemplates the possibility of adding an extra metallic current collector on the opposite electrode, which is not in contact with the doped silicon.
  • This current collector would be formed by a network of metal tracks in the form of a mesh. The metal tracks would be deposited on the electrode, in the same areas as the doped silicon nerves. In this way, it would be possible to have current collectors for both electrodes while maintaining the total active area of the battery.
  • the dimensions of the metal tracks are therefore limited by the dimensions of the ribs, always being as wide as possible and following the architecture of the rib network.
  • the thickness of the metal collector could vary between 50 nm and 5 ⁇ .
  • Another particular aspect of the invention consists in the inclusion of a micro heater to locally heat the electrolytic membrane.
  • the invention includes the possibility of implementing a resistive type micro heater based on metal tracks forming a coil.
  • the heater is located on the silicon ribs, so it does not imply any loss of effective membrane area.
  • the heater is passivated with layers dielectrics that prevent electrical leakage.
  • the dimensions of the metal tracks are always determined by the dimensions of the ribs, so that the metal tracks of the heater are always narrower than the ribs.
  • the thickness of the heater tracks can vary between 10 nm and 2 ⁇ and can be made of various materials, including metals typically used to manufacture micro heaters in micro electronics (Pt, Au, W ).
  • This element is particularly useful considering that the operating temperatures of SOFCs are between 400 and 600 ° C.
  • the implementation of a micro heater allows the active part of the micro stack (the electrolytic membrane, plus the two electrodes) to reach the corresponding working temperature while the support platform is practically maintained at room temperature. This fact greatly simplifies the maneuverability of the device, also making it easier to seal the platform with the interconnects. When sealing at room temperature, the risks of rupture are drastically reduced due to the different thermal expansion of the materials involved.
  • Figure 1 (a) Scheme of a solid oxide micro fuel cell according to the invention, (b) Scheme of a solid oxide micro fuel cell according to the invention, including a micro heater.
  • FIG. 3 Diagram of a large surface electrolytic membrane supported on nerves of doped silicon with different geometries of the singular membranes (top view): (a) hexagonal, (b) square, (c) circular. In (a) a scheme of a membrane is also represented Large surface electrolytic including a micro heater (top view).
  • the present invention consists in the use of doped silicon ribs for the manufacture of large surface solid oxide micro fuel cells.
  • Figure 1 (a) shows a diagram of a complete SOFC supported on a silicon platform ⁇ substrate), where the different components of the device can be distinguished.
  • the silicon ribs located below the fine electrolyte allow the manufacture of membranes with larger areas.
  • the porous anode and the porous cathode are deposited on both sides of the electrolyte completing the battery.
  • the porous anode also covers the silicon nerves, establishing contact with them and thus allowing the collection of the current generated at the anode through them ⁇ contact of the anode).
  • the electrical connections of both electrodes are, therefore, on the cathode side.
  • Figure 1 (b) also shows a scheme of a SOFC according to the invention, but in this case including a micro heater to locally heat the membrane, while the rest of the device ⁇ substrate) is kept at room temperature.
  • the metal tracks of the heater are deposited on the silicon ribs coated on both sides with insulating dielectric layers.
  • the heater contacts are also placed on the cathode side, as are the anode and cathode contacts.
  • Figure 2 shows the manufacturing process for obtaining the device described in Figure 1 (b).
  • the manufacture of the device as described in Figure 1 (a) is similar, only that steps 2 (d) and 2 (e) They must skip.
  • the different components of the device are marked with numbers so that they can be easily identified.
  • Table (table 1) shows what each number corresponds to.
  • the areas (2) where you wish to dop the silicon substrate (1) are defined by photolithography. These areas correspond to the future nerves of doped silicon.
  • the silicon ribs have a width wl and are separated from each other by a distance w2.
  • the ribs have a circular section due to semi ⁇ isotropic doping process.
  • the tracks where the metal is deposited are defined by photolithography (5). Through a lift-off process, the metal remains only in the defined areas, giving rise to the coil-shaped heater. In the same process, a metallic layer is also deposited on the area destined to contact the silicon ribs (anode current collection). Thus, a good electrical contact with the doped silicon is ensured.
  • the metal tracks of the heater have a thickness ti and a width w4.
  • a dielectric layer is deposited on the entire substrate, except in the areas destined for the electrical contacts for the anode and the heater ⁇ 5a and 5b, respectively).
  • the dielectric layer is deposited on the entire substrate, and subsequently, by a photolithography process, it is selectively removed from the desired areas (contacts).
  • the layers of silicon nitride and silicon oxide are removed in certain areas of the back side of the substrate. Thus, the areas where the silicon will be subsequently engraved to create the membranes are defined. The defined area will have a width w5.
  • the silicon substrate (1) and the silicon oxide layer (3) of the upper face are removed by wet etching with KOH and HF respectively, made from the face back of the substrate.
  • the silicon nitride layer on the back side acts as a mask allowing the etching of silicon only in the desired areas.
  • These zones define large surface silicon nitride membranes supported on the silicon ribs, which will act as a substrate during the electrolyte deposition in the next step. Doped silicon is selective when taxed with KOH, so the nerves are not recorded during this step. Due to the anisotropic etching of silicon, the width of the w6 membrane will always be smaller than the width defined during the etching of the silicon nitride on the back side in the previous step (w5).
  • the ceramic electrolyte (7), with a thickness t2, is deposited by a thin layer deposition technique on the insulating layer (6).
  • the cathode (8) and anode (5) electrodes, with thicknesses t3 and t4 respectively, are deposited on both sides of the substrate and the membrane.
  • the possible materials are multiple, including metals and ceramics or cermets. Also, these electrodes can be deposited by different thin layer deposition techniques.
  • Figure 3 shows top views of different large surface electrolytic membranes.
  • the support silicon ribs (2) define self-supporting singular membranes (1), with different geometries: hexagonal (a), square (b) or circular (c). In all three cases, a large surface membrane consisting of a set of 5x5 singular membranes is illustrated, although the number of singular membranes per large surface membrane may vary, forming larger or smaller membranes.
  • the coil shape of the micro heater (3) can be seen in Figure 3 (a).
  • the metal tracks of the heater follow the geometry of the ribs (2) on which they are supported.
  • Figure 4 shows optical microscope images of some of the large surface membranes manufactured in accordance with the manufacturing process detailed in Figure 2.
  • the membranes correspond to the geometry detailed in Figure 3 (a), although in In this case a series of "secondary" (much finer) silicon nerves were added forming triangles within the hexagons, to ensure a good distribution of heat throughout the entire membrane.
  • Example 1 Manufacture of a large surface YSZ membrane supported on nerves of doped silicon.
  • a 200 nm thick YSZ membrane was manufactured according to the manufacturing process detailed in Figure 2 (skipping steps d and d).
  • a 300 nm silicon nitride pre-membrane supported on the network of doped silicon ribs was manufactured.
  • the dimensions of the doped silicon nerves were defined as 85 ⁇ in width and 10 ⁇ in maximum thickness, and distributed so as to define singular hexagonal membranes with a side of 150 ⁇ .
  • the YSZ was deposited on said nitride pre-membrane by PLD. Subsequently, silicon nitride was removed by RIE from the back side of the membrane, thus releasing the self-supported YSZ membrane in the silicon nerves.
  • Example 2 Manufacture of a SOFC based on a large surface YSZ membrane supported on doped silicon ribs.
  • a large surface SOFC can be manufactured following the same steps as in example 1 but adding the electrode reservoir and current collectors.
  • platinum electrodes were deposited by sputtering, thus completing the fuel cell.
  • the thickness of the electrode was defined as 80 nm, to form a porous layer by heat treatment of the platinum layers at 600 ° C.
  • doped silicon nerves were also used as current collectors.
  • the Pt layer it was not only deposited on the YSZ membrane but also on the silicon ribs (see figure 2j, element 9).
  • a good electrical contact between the electrode and the current collector was ensured.
  • a contact was opened through the dielectric layers on the cathode side to be able to contact the doped silicon ribs (see Figure 2c). Therefore, the current collection of both electrodes was made from the same side of the cathode.
  • Example 3 Manufacture of a SOFC based on a large surface YSZ membrane supported on doped silicon ribs, including a buried micro heater.
  • a large surface SOFC with a micro heater integrated in the membrane can be manufactured following the same steps as in examples 1 and 2, but including the corresponding manufacturing steps with the tank and micro heater insulation (dye steps in figure 2).
  • a coil-shaped tungsten heater was deposited on the silicon nitride on the cathode side, defining W tracks on the silicon ribs (see figure 3a).
  • the thickness of the heater tracks was set at 500 nm, while its width at 50 ⁇ .
  • a 500 nm insulating layer of silicon oxide was subsequently deposited covering the heater to avoid short circuits with the electrodes or the current collector.

Abstract

La présente invention concerne une pile à combustible à oxyde solide qui comprend: (a) un substrat comportant au moins une cavité pour former une membrane; (b) une membrane électrolytique formée d'une couche mince d'un oxyde solide de plus de 5 nm mais de moins de 5 μm d'épaisseur, qui recouvre la cavité formée dans le substrat; (c) un réseau de nervures en silicium dopé traversant la cavité, immédiatement sous la membrane électrolytique, de sorte qu'elles servent de support à l'électrolyte; les nervures en silicium déterminant des membranes électrolytiques singulières d'une taille toujours supérieure à la taille des nervures, lesquelles forment ensemble la membrane électrolytique de grande surface; et (d) deux couches fines qui font office d'électrodes, déposées individuellement de chaque côté de ladite membrane électrolytique. Par conséquent l'objet de la présente invention porte sur le procédé de fabrication de ladite pile à combustible.
PCT/ES2013/070406 2012-06-21 2013-06-21 Membrane électrolytique à oxyde solide placée sur un support comportant des nervures de silicium dopé pour des applications dans des micropiles à combustible à oxyde solide WO2013190164A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ESP201230973 2012-06-21
ES201230973A ES2446465B1 (es) 2012-06-21 2012-06-21 Membrana electrolitica de oxido solido soportada sobre nervios de silicio dopado para aplicaciones en micro pilas de combustible de oxido solido

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WO2013190164A1 true WO2013190164A1 (fr) 2013-12-27

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017042034A1 (fr) * 2015-09-10 2017-03-16 Robert Bosch Gmbh Élément micromécanique de détection d'électrolyte solide et procédé de fabrication de celui-ci
WO2017042179A1 (fr) * 2015-09-10 2017-03-16 Robert Bosch Gmbh Composant à semi-conducteur

Citations (3)

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Publication number Priority date Publication date Assignee Title
US4448865A (en) * 1981-10-30 1984-05-15 International Business Machines Corporation Shadow projection mask for ion implantation and ion beam lithography
JP2003346842A (ja) * 2002-05-23 2003-12-05 Nissan Motor Co Ltd 固体酸化物型燃料電池用セル板及びその製造方法
US7189471B2 (en) * 1999-02-01 2007-03-13 The Regents Of The University Of California Solid oxide MEMS-based fuel cells

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4448865A (en) * 1981-10-30 1984-05-15 International Business Machines Corporation Shadow projection mask for ion implantation and ion beam lithography
US7189471B2 (en) * 1999-02-01 2007-03-13 The Regents Of The University Of California Solid oxide MEMS-based fuel cells
JP2003346842A (ja) * 2002-05-23 2003-12-05 Nissan Motor Co Ltd 固体酸化物型燃料電池用セル板及びその製造方法

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Title
GARBAYO: "Electrical characterization of thermomechanically stable YSZ membranes for micro solid oxide fuels applications", SOLID STATE IONICS 2010, vol. 181, 7 January 2010 (2010-01-07), pages 322 - 331 *
JUAN PABLO ESQUIVEL ET AL.: "fuel cell-powered microfluid platform for lab-on-a-chip applications", LAB ON A CHIP., vol. 12, no. 1, 7 January 2012 (2012-01-07), pages 73 - 79 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017042034A1 (fr) * 2015-09-10 2017-03-16 Robert Bosch Gmbh Élément micromécanique de détection d'électrolyte solide et procédé de fabrication de celui-ci
WO2017042179A1 (fr) * 2015-09-10 2017-03-16 Robert Bosch Gmbh Composant à semi-conducteur

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ES2446465A1 (es) 2014-03-07

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