Electrolyte forming process
A process for forming an electrolyte for a metal-supported solid-oxide fuel cell, the process comprising: a. combining a doped-ceria powder with a sintering aid and solvent to form a slurry; b. applying the slurry to an anode layer; c. drying to form a green electrolyte; and d. firing the green electrolyte to form a sintered electrolyte; wherein the slurry in step b. comprises doped-ceria powder with a physical property selected from bimodal particle size distribution, a BET surface area in the range 15-40 m 2 /g, a spherical morphology, or combinations thereof together with an electrolyte obtained by the process, a fuel cell and fuel cell stack, comprising the electrolyte, and the use of the fuel in the generation of electrical energy.
1. A process of forming a structure including an electrolyte and an anode layer for a metal-supported solid-oxide fuel cell, the process comprising:
a. providing a metal-supported anode layer comprising a metal substrate having an anode layer deposited thereon;
b. combining a doped-ceria powder with a sintering aid and solvent to form a slurry;
c. applying the slurry to the anode layer, wherein the slurry comprises doped-ceria powder with a bimodal particle size distribution;
d. drying to form a green electrolyte;
e. placing a mass on at least a part of the metal substrate to hold at least the part of the metal substrate flat during a step of firing the green electrolyte; and
f. firing the green electrolyte in air at a sintering temperature that is less than 1100° C. to form a sintered electrolyte overlying the metal substrate and the anode layer thereon,
wherein the metal substrate comprises a stainless steel foil substrate comprising a perforated region surrounded by a non-perforated region.
2. The process according to claim 1 , further comprising: attrition milling the slurry prior to application to the anode layer.
3. The process according to claim 1 , wherein the bimodal particle size distribution comprises particles forming a peak in a range 0.1-0.4 μm and a peak in a range 0.5-1.5 μm.
4. The process according to claim 1 , wherein the sintering aid is present in a range 0.5-5 mol % total cations.
5. The process according to claim 1 , further comprising: forming the green electrolyte from a screen-printable ink.
6. The process according to claim 1 , wherein the green electrolyte comprises multiple layers of electrolyte formed by applying the slurry in layers over the anode layer, with drying between the application of each layer.
7. The process according to claim 1 , wherein the anode layer is a sintered anode layer.
8. The process according to claim 1 , wherein the anode layer is a green anode layer and the green anode layer and green electrolyte are sintered in a single firing step.
9. The process according to claim 1 , wherein the green electrolyte covers the anode layer and the metal substrate.
10. The process according to claim 1 , further comprising: pressing after application of the slurry to the anode layer, but prior to firing of the green electrolyte.
11. A process for forming a fuel cell, comprising:
forming an electrolyte on a metal-supported anode layer using the process of claim 1 , and
applying a cathode material to the electrolyte.
12. A fuel cell comprising an electrolyte obtained by the process according to claim 1 .
13. A fuel cell stack comprising at least two fuel cells according to claim 12 .
14. The process according to claim 1 , wherein the doped-ceria powder has a BET surface area in a range 15-40 m 2 /g.
15. The process according to claim 1 , wherein the doped-ceria powder has a spherical morphology.
16. The process according to claim 1 , wherein the slurry in step c. comprises doped-ceria powder with a bimodal particle size distribution, a BET surface area in a range 15-40 m 2 /g and a spherical morphology.