Cobalt-Free Perovskite Cathodes for Solid Oxide Fuel Cells

The past decade has observed rapid growth in the development of cobalt-free perovskite cathodes, which provide enhanced structure and operational stability at the operating temperature of intermediate temperature solid oxide fuel cells (IT-SOFC, 600–800 °C) compared to its cobalt-containing counterpart. This Review aims to present a comprehensive overview on the status and advances of the existing cobalt-free perovskite cathodes for IT-SOFCs by discussing electrochemical behaviors, thermal expansion properties, stabilities as well as the oxygen ionic and the electronic transport properties of these cobalt-free perovskite cathode compositions, with primary emphasis on the relationship between the electrochemical performances and the materials science-related factors. Among various cobalt-free perovskite cathodes presented in this Review, niobium-doped compositions generally show lower polarization resistances relative to other cathode compositions.