Method for preparation of the solid oxide fuel cell single cell
There are disclosed a method for preparation of the solid oxide fuel cell single cell and a single cell with nano (micro) meso porous cathode electrode that are operational from 723 to 1073 K. The cathode electrode of the single cell possesses very large surface area (10-500 m2 g −1 ) with the hierarchical nano (micro) mesoporous structure, very high catalytic activity and very low oxygen electroreduction activation energy varying from 0.3-0.8 eV at −0.2 . . . 0 V cathode electrode potential versus porous Pt/O 2 reference electrode in air.
1. A method for preparation of a solid oxide fuel cell single cell operational from 723 to 1073 K, said fuel cell including a microporous and mesoporous cathode electrode, comprising the following steps:
(A) thermal decomposing a mixture of rare earth nitrate, strontium nitrate and cobalt nitrate with conducting corresponding rare earth cobaltite activated with strontium ions in the presence of the reducing agent and oxygen;
(B) preparing a raw cathode electrode paste by mixing rare earth cobaltite activated with strontium ions, mechanically uncompressible pore forming agent, organic binder and solvent or mixture of solvents as microporous and mesoporous forming agents for obtaining highly microporous and mesoporous cathode electrode;
(C) preparing gadolinia or samaria doped ceria electrolyte by sintering at a temperature from about 800 to about 1800 K with the molar ratio of gadolinia or samaria in gadolinia or samaria activated ceria varied with CeO 2 , prior to said sintering, pressing said gadolinia and samaria doped ceria electrolyte at a pressure from about 5 to about 20 kN cm −2 from about 0.5 to about 15 min;
(D) forming said microporous and mesoporous cathode electrode and microporous and mesoporous cathode electrolyte halfcell by burning out the pore forming agent, solvent and binder from the raw cathode electrode paste and sintering said raw cathode electrode paste onto the gadolinia or samaria doped ceria oxide oxygen ion conducting electrolyte at a temperature from about 700 to about 1773 K for about 60 to about 600 min; and
(E) screenprinting Pt-paste onto a free side of cathode electrolyte halfcell and sintering the fuel cell at temperatures from about 800 to about 1500 K for about 6 to about 600 min.
2. The method of claim 1 , wherein said molar ratio of gadolinia or samaria in gadolinia or samaria activated ceria is varied up to about 0.20.
3. The method of claim 1 , wherein said rare earth cobaltite cathode electrode for solid oxide fuel cell is substituted and activated with strontium ions, varying the molar ratio of Sr2+ up to about 0.6.
4. The method of claim 1 , wherein a carbon acetylene black powder is used as an uncompressible pore forming agent in the raw cathode electrode paste.
5. The method of claim 4 , wherein the amount of uncompressible pore forming agent in the raw cathode electrode paste is in a range up to about 30 weight percent of the total raw cathode electrode paste.
6. The method of claim 1 , wherein said binder is ethylcellulose and the binder is present in a range up to about 10 weight percent of the total raw cathode electrode paste.
7. The method of claim 1 , wherein said microporous and mesoporous cathode electrode possesses the hierarchical nano(micro)mesoporous structure with surface area from about 10 to about 500 m2 g −1 .
8. The method of claim 1 wherein said reducing agent is glycine, further wherein said reducing agent is used to initiate the thermal decomposing step.
9. The method of claim 1 , wherein said solvent is turpentine oil.
10. The method of claim 1 , wherein said rare earth cobaltite is present in a perovskite structure, further wherein the molar ratio of rare earth element in strontium activated rare earth cobaltite is varied from about 1.0 to about 0.4 in an A-site position of a perovskite structure of rare earth cobaltite.