Electrophoretic deposition of dense Sr- And Mg-doped LaGaO₃ electrolyte films on porous La-doped ceria for intermediate temperature solid oxide fuel cells

The application of the electrophoretic deposition (EPD) technique to the preparation of dense La_0.8Sr_0.2Ga_0.8Mg _0.2O_2.8 (LSGM) electrolyte films for intermediate temperature solid oxide fuel cells (IT-SOFCs) was investigated. Suspensions of LSGM were prepared in acetone + I₂+ H₂O dispersion media. The effects of water and iodine content, of the applied voltage, and of powder loading on the EPD rate were systematically studied using metallic substrates (Pt and stainless steel). This allowed to identify the suitable set of EPD process parameters that were used to deposit LSGM films on tape-cast composite electrodes, composed of lanthanum-doped ceria (La_0.4Ce _0.6O_2-x, LDC), polyvinylidene difluoride (PVDF) and carbon powders. After EPD, dense and crack-free 15 μm thick LSGM films were obtained on porous LDC by co-firing in air at 1,490 °C. Line profile analyses performed by energy dispersive X-ray spectroscopy (EDS) did not reveal any interdiffusion of ions across the LSGM/LDC interface. The chemical and structural compatibility of LSGM with LDC was also checked by heat treating a mixture of the two powders (1:1 weight ratio) using the same thermal cycle as that of the LDC/LSGM bi-layer co-firing at 1,490 °C. EPD has thus proven to be a viable way for manufacturing anode-supported LSGM electrolyte films.