Nanostructured GDC-impregnated La_(0.7)Ca_(o.3)CrO_(3-δ) symmetrical electrodes for solid oxide fuel cells operating on hydrogen and city gas

摘要

Nanostructured Gd_(0.1)Ce_(0.9)O_(1.95) (GDC)-impregnated La_(0.7)Ca_(0.3)CrO_(3-δ) (LCC) composites were investigated as symmetrical electrodes for La_(0.9)Sr_(0.1)Ga_(0.8)Mg_(0.2)O_(3-δ) (LSGM)-supported solid oxide fuel cells (SOFCs) without using interlayer at anode/electrolyte interface. The impregnation of aqueous Gd_(0.1)Ce_(0.9)(NO_3)_x solution into the porous LCC electrode backbones was found to form nanosized GDC particles on LCC surfaces after calcining at 850 ℃ for 30 min. The optimized performance of electrodes for SOFCs had been achieved through the impregnation cycles of 3-7 times. The introduction of the ion conducting phase GDC in nanometer significantly enhanced the symmetrical electrode performance. The symmetrical cell with the impregnation of five times displayed the best performance and the maximum power densities were 521 mW cm"2 and 638 mW cm"2 at 850 ℃ and 900 ℃ with dry H_2 as fuel, respectively. Using commercial city gas containing H2S as fuel, the maximum power densities of the cell reached 362 mW cm~(-2) and 491 mW cm~(-2) at 850 ℃ and 900 ℃, respectively. The microstructure, valence state of Ce element and electrochemical stability of the nanostructured GDC-impregnated LCC composites were also discussed.