Experimental deconvolution of electrode resistances of a Ni-CGO-based electrolyte-supported cell via symmetrical cell testing

Electrolyte-supported solid oxide cells (SOCs) using Ni-CGO and LSCF-CGO electrodes show promising and stable performance in steam electrolysis. However, deconvoluting the impedance response is complicated by overlapping processes from both electrodes. This work presents a combined approach using symmetrical cell testing, electrochemical impedance spectroscopy (EIS), equivalent circuit modeling (ECM), and multi-physics impedance modeling to isolate individual resistances. At 800 °C, under open-circuit voltage with 50/50 H 2 O/H 2 on the fuel side and air on the oxygen side, the total polarization resistance ( R p ) of a full cell with thick 3YSZ electrolyte was 0.16 Ω cm 2 , 0.04 Ω cm 2 from the Ni-CGO fuel electrode and 0.02 Ω cm 2 from the LSCF-CGO oxygen electrode. The remaining resistance is mainly attributed to gas conversion. Low-frequency deviations between symmetric and full cells are captured by the impedance model. This method enables robust deconvolution of overlapping processes in SOCs and supports further development of durable electrodes for electrolysis applications. • LSCF-CGO and Ni-CGO electrodes tested across temperatures and compositions. • Electrode-specific contributions deconvoluted via EIS and circuit modeling. • Comparison of symmetrical and full cells must consider gas conversion resistance. • Ni-CGO exhibits higher resistance than LSCF-CGO from 650 to 850 °C. • Multi-physics modeling captures gas conversion in low-frequency impedance.