Concepts for Ultra-High Power Density Solid Oxide Fuel Cells (SOFC)

A parametric equation for describing polarization in solid oxide fuel cells (SOFC) is presented in terms of experimentally measurable parameters. The equation explicitly describes activation and concentration polarizations at the two electrodes, and the ohmic loss as a function of current density. Using the equation and known values of experimentally measured parameters, determined by in-cell and out-of-cell tests, various polarizations are estimated as functions of current density, and the maximum possible performance characteristics are assessed. Using the model, prospects for ultra-high power density SOFC at intermediate temperatures (<800 degrees C) are examined. The results show that even in thin electrolyte film, anode-supported cells, ohmic contribution can be substantial, not all of it being attributable to the electrolyte. The results also show that the electrode particle size has a substantial effect on activation polarization.