Durable Tape-Cast Trilayer La_0.8Sr_0.2Ga_0.8Mg_0.2O_3-δ Electrolyte with Infiltrated Electrodes for Intermediate Temperature Solid Oxide Fuel Cells

As global energy demands shift toward a sustainable alternative, hydrogen-powdered solid oxide fuel cells (SOFCs) offer a high-efficiency, low-emission solution for electrical energy conversion. However, performance limitations at intermediate temperatures (600-800 °C) necessitate advancements in electrolyte and electrode design. The present work presents the fabrication of a trilayer (porous/dense/porous) La_0.8Sr_0.2Ga_0.8Mg_0.2O_3‑δ electrolyte using a tape casting method, yielding a sintered structure with ∼55 μm thick, porous layers (∼55% porosity) and a ∼20 μm dense electrolyte supported by La_0.8Sr_0.2Ga_0.8Mg_0.2O_3‑δ rings. The porous La_0.8Sr_0.2Ga_0.8Mg_0.2O_3‑δ backbone is infiltrated with nominal chemical composition NdBaCoFeO_5+δ (NBCF) and a Ni-Gd-doped-Ce (Ni-GDC) anode. Electrochemical impedance spectroscopy, distribution functions of relaxation times, and equivalent circuit modeling identified an optimal NBCF loading of 1.58 mg/cm², which minimizes charge transfer and diffusion resistance, reducing the area-specific resistance to 0.025 Ω cm² at 800 °C. Full cell testing under SOFC conditions achieves a peak powder density of 400 mW/cm² at 750 °C with low ohmic (0.11 Ω cm²) and polarization (0.33 Ω cm²) resistances.