Relationship Between Designed Three-Dimensional YSZ Electrolyte Surface Area and Performance of Solution-Precursor Plasma-Sprayed La_0.8Sr_0.2MnO_3−δ Cathodes

Active three-phase boundaries (TPBs) significantly influence cathode performance in solid oxide fuel cells, but obtaining long TPBs and understanding the mechanism underlying the improved cathode performance when the electrolyte is prepared with a smooth surface by a high-temperature sintering process remain essential challenges. In this work, we used flame spraying to deposit single-layer semimolten particles on a smooth electrolyte to build a three-dimensional surface with enlarged active surface area and thus increased TPBs. Meanwhile, La_0.8Sr_0.2MnO_3−δ (LSM) cathodes with fine microstructure were deposited by solution-precursor plasma spraying (SPPS) on the designed electrolyte to establish a three-dimensional cathode–electrolyte interface. The deposition behavior of the semimolten particles on the smooth electrolyte and LSM cathodes on the three-dimensional electrolyte surface was studied. The effects of the area enlargement factor (α_area) on the polarization resistance of the SPPS LSM cathodes were investigated, using three-dimensional electrolytes with α_area from 1.29 to 2.48. The results indicated that convex particles with different molten states bonded well with the electrolytes. SPPS LSM cathodes also showed good interfacial bonding with convex particles. Finally, the cathode polarization (R_p) decreased linearly with increase of α_area. At 800 °C, R_p decreased from 0.98 to 0.32 Ω cm² when α_area was increased from 1.29 to 2.48.