Abstract:

Single layer LSM＋ YSZ and double layers LSM/LSM＋ YSZ composite electrodes with varying YSZ content in the LSM＋ YSZ layer have been prepared. The electrochemical properties and microstructures of the electrodes were investigated and compared. The electrochemical performance of the single layer LSM＋YSZ electrodes was improved when a certain amount of YSZ was added due to the increase of the three phase boundaries (TPB) by the addition of YSZ, while excessive YSZ addition (60％ ) caused a decrease in performance, because the in-phase resistance of the electrode increased so high, leading to a reduced effective electrode area. The problem was eliminated by a double-layer LSM/LSM＋ YSZ composite electrode, in which a pure LSM layer functioned as a current collector and reduced the in-phase resistance.As a result, both large TPB area and low ohmic resistance were assured in this kind structure. At 1223 K, the double-layer composite electrode with 50 wt.％ YSZ has the lowest polarization resistance of 0.3Ω•cm2.

Key words: SOFC, Composite LSM electrodes, Double-layer electrodes, AC impedance