Electrochemical performance and stability of SrTi_(0.3)Fe_(0.6)Co_(0.1)O_(3-δ) infiltrated La_(0.8)Sr_(0.2)MnO_3-Zr_(0.92)Y_(0.16)O_(2-δ) oxygen electrodes for intermediate-temperature solid oxide electrochemical cells

摘要

The La0.8Sr0.2MnO3-Zr0.92Y0.16O2-delta (LSM-YSZ) composite is the most widely used oxygen electrode for solid oxide electrochemical cells (SOCs). However, operating temperatures 700 degrees 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-delta(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.