A real proton-conductive, robust, and cobalt-free cathode for proton-conducting solid oxide fuel cells with exceptional performance

The development of proton, oxygen-ion, and electron mixed conducting materials, known as triple-conduction materials, as cathodes for proton-conducting solid oxide fuel cells (H-SOFCs) is highly desired because they can increase fuel cell performance by extending the reaction active area. Although oxygen-ion and electron conductions can be measured directly, proton conduction in these oxides is usually estimated indirectly. Because of the instability of cathode materials in a reducing environment, direct measurement of proton conduction in cathode oxide is difficult. The La0.8Sr0.2Sc0.5Fe0.5O3-delta (LSSF) cathode material is proposed for H-SOFCs in this study, which can survive in an H-2-containing atmosphere, allowing measurement of proton conduction in LSSF by hydrogen permeation technology. Furthermore, LSSF is discovered to be a unique proton and electron mixed-conductive material with limited oxygen diffusion capability that is specifically designed for H-SOFCs. The LSSF is an appealing cathode choice for H-SOFCs due to its outstanding CO2 tolerance and matched thermal expansion coefficient, producing a record-high performance of 2032 mW cm(-2) at 700 degrees C and good long-term stability under operational conditions. The current study reveals that a new type of proton-electron mixed conducting cathode can provide promising performance for H-SOFCs, opening the way for developing high-performance cathodes.