Kinetics and transport at AMTEC electrodes. I - The interfacial impedance model

Mixed mass-transport and kinetic control of sodium ion reduction at porous inert electrodes on sodium beta-double-prime alumina solid electrolyte (BASE) ceramic in a high-temperature electrochemical cell has been observed and modeled. The high ionic conductivity of BASE and the reversibility of the liquid sodium/BASE anodic half-cell led to assignment of potential-dependent (nonohmic) resistances to kinetic and mass-transport processes associated with the porous electrode. The morphology of these electrodes and typical sodium gas pressures are consistent with Knudsen, or free-molecular, flow through the electrode.