0.5Sr 0.5Co 2O 5+δ cathode for SOFCs]]>

摘要

In this study, the crystal structure, thermal, oxygen transport, electrical conductivity and electrochemical properties of the perovskite NdBa0.5Sr0.5Co2O5+δ(NBSC55) are investigated. In the temperature range of 250?°C–350?°C, the weight loss upon heating was due to a partial loss of lattice oxygen and along with a reduction of Co4+to Co3+. The tend of weight-loss slows down as temperature increased above 350?°C indicating a reduction of Co3+to Co2+during this stage. The oxygen migration is dominated by surface exchange process at high temperature range (650-800?°C); however, the bulk diffusion process prevails at low temperature range (500–600?°C). For long-term testing, the polarization resistance of NBSC55 increases gradually form 3.13?Ω?cm2for 2?h to 3.34?Ω?cm2for 96?h at 600?°C and an increasing-rate for polarization resistance is around 0.22%?h?1. The power density of the single cell with NBSC55 cathode reached 341?mW?cm?2at 800?°C.