Transport Properties and Electrochemical Reaction

Temperature dependence of electrical conductivity of (La, Sr)Mn03 is shown in Fig. 7.6 [26]. The conductivity in air is high enough for a planar SOFC. For a tubular or segment-in-series type stack, however, the current path is longer 

Typical current-potential curves for (La,Sr)Mn03 reported by Tsuneyoshi et al. [29] are shown in Fig. 7.7. The data are taken for both the cathodic and anodic polarization. The empirical equation is derived from the reaction order analysis as follows  

In a practical application, LSM is often used as a composite with YSZ particles [33] to increase the electrochemical reaction site. As YSZ can make a separate ionic path, the reaction site is made three dimensionally inside the electrode layer. The width of the active reaction area is determined by the resistance ratio of the diffusion and the interface reaction. Because electronic conductivity is decreased by mixing YSZ, a current collection layer of LSM or other material is necessary. 

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