Enhancing oxygen surface exchange coefficients of strontium-doped lanthanum manganates with electrolytes

Electrolyte effects on the oxygen surface exchange coefficients of strontium-doped lanthanum manganates (LSM) are investigated using electrical conductivity relaxation technique. Introducing electrolytes can significantly reduce the re-equilibration time, demonstrating the substantial promotion in the surface exchange kinetics. The coefficient at 1000 °C increases from 9.00 × 10−5 cm s−1 for pure LSM to 2.45 × 10−4 cm s−1 for LSM coated with yttria-stabilized zirconia, and further increases to 7.92 × 10−4 cm s−1 for LSM with samaria-doped ceria. The nearly one order of magnitude increase in the coefficient demonstrates that introducing electrolytes can effectively increase the electrochemical performance of solid-oxide-fuel-cell cathodes by enhancing the surface exchange reaction in addition to extending the reaction sites.

► Introducing electrolyte can increase the oxygen surface exchange coefficient of LSM. ► The coefficient increases from 9.00 × 10−5 to 7.92 × 10−4 cm s−1 when doped ceria is coated. ► The coefficient increment depends on electrolyte conductivity rather than catalytic activity.