Electrochemical performance and stability of SrTi0.3Fe0.6Co0.1O3-δ infiltrated La0.8Sr0.2MnO3[sbnd]Zr0.92Y0.16O2-δ oxygen electrodes for intermediate-temperature solid oxide electrochemical cells

Abstract

The La0.8Sr0.2MnO3Zr0.92Y0.16O2-δ (LSM-YSZ) composite is the most widely used oxygen electrode for solid oxide electrochemical cells (SOCs). However, operating temperatures >700 °C are required for good performance since oxygen reactions are limitied to three-phase boundaries (TPBs) because of poor ionic conductivity of LSM. Furthermore, LSM-YSZ electrodes typically delaminate during electrolysis operation leading to cell degradation. One strategy to improve SOCs with LSM-YSZ electrodes is to infiltrate a mixed ionically and electronically conducting (MIEC) material that promotes oxygen exchange. However, infiltrated materials have a nano-scale structure that may not be stable under SOC operating temperatures. Here, we report results on the infiltration of SrTi0.3Fe0.6Co0.1O3-δ (STFC), a recently reported high performance MIEC, into LSM-YSZ to improve its electrochemical performance and stability at intermediate temperatures. The infiltrated STFC enhances LSM-YSZ and cell performance, typically yielding a decrease in electrode polarization resistance by a factor >3 times, resulting in an increase in fuel cell maximum power density and electrolysis current density (at 1.3 V) by a factor > 2 times. Perhaps more significantly, the infiltrated electrodes show good performance stability, with suppression of electrode delamination during electrolysis and no evidence of coarsening or segregation induced degradation.