Electrochemical investigation of Pr6O11 infiltration into La0.8Sr0.2MnO3-δ-Ce0.9Gd0.1O1.95 cathodes for IT-SOFC

Infiltration through spray-pyrolysis deposition is a one-step and effective method for enhancing the electrode performance of solid oxide fuel cell (SOFC) at intermediate temperatures. Among various infiltrated electrodes, Pr6O11 has shown promising electrocatalytic properties for oxygen reduction reaction (ORR), despite its relatively low electrical conductivity. This study focuses on obtaining Pr6O11-infiltrated cathodes using spray-pyrolysis deposition, with different porous backbone layers that exhibit electronic and/or ionic conductivity: La0.8Sr0.2MnO3-δ (LSM), Ce0.9Gd0.1O1.95 (CGO), and LSM-CGO composite. The electrochemical properties and the subprocesses involved in the ORR are investigated in symmetrical cells. It is observed that the polarization resistance (Rp) decreases when the backbone layer exhibits high ionic conductivity. At 650 ºC, the Rp values are 0.03, 0.06 and 0.1 Ω cm2 for CGO, LSM-CGO and LSM backbones, respectively. The dependence of Rp contributions with pO2 reveals that the same electrochemical processes are involved regardless of the backbone composition, confirming a less resistive oxide-ion transport from the TPB into the electrolyte with the CGO backbone. In contrast, the CGO backbone exhibits higher series resistance (Rs) (44.5 Ω cm), attributed to an increased contribution of ohmic losses compared to the LSM backbone (39.8 Ω cm). This study provides valuable insights into the performance and optimization of Pr6O11-infiltrated cathodes with different backbone compositions for their implementation in SOFCs.