Synthesis,characterization and electrochemical evaluation of high-performance Sr(Ce 0.6 Zr 0.4 ) 0.85 Y 0.15 O 3−δ /Sm 0.2 Ce 0.8 O 1.9 co-ionic conducting composite electrolytes for solid oxide fuel cells

Abstract

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The Sr(Ce_0.6Zr_0.4)_0.85Y_0.15O_3−δ/Sm_0.2Ce_0.8O_1.9 (Strontium Cerium Zirconium Yttrium oxide [SCZY] and Samarium-doped Ceria [SDC]) co-ionic conducting composite electrolyte was successfully prepared by separately synthesising SCZY and SDC via the citrate-EDTA complexing method, followed by mechanical mixing through ball milling. After sintering at 1450 °C for 5 h, the composite exhibited a dense structure with retained integrity. Electrochemical and structural analyses were conducted under varied atmospheres and temperatures. The Pt/SCZY-SDC/Pt cell's total electrical conductivity and activation energy were determined using electrochemical impedance spectroscopy, yielding values of 0.039 S cm⁻¹ and 61.56 kJ mol⁻¹, respectively, in H₂/Air at 600–800 °C. Conductivity measurements indicated H⁺ and O²⁻ ion conductivities of 0.228 and 0.00349 S cm⁻¹, respectively, at 800 °C. Notably, the electrolyte-supported Pt/SCZY-SDC/Pt cell demonstrated a power output of 21.7 mW cm⁻² and an open-circuit voltage of 0.74 V at 800 °C, featuring a 1.19-mm electrolyte thickness and 2.54 cm² cathode area.