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  1. Abstract

    Solid-oxide fuel cells (SOFCs) offer great promise for producing electricity using a wide variety of fuels such as natural gas, coal gas and gasified carbonaceous solids; however, conventional nickel-based anodes face great challenges due to contaminants in readily available fuels, especially sulphur-containing compounds. Thus, the development of new anode materials that can suppress sulphur poisoning is crucial to the realization of fuel-flexible and cost-effective SOFCs. In this work, La0.1Sr1.9Fe1.4Ni0.1Mo0.5O6–δ (LSFNM) and Pr0.1Sr1.9Fe1.4Ni0.1Mo0.5O6–δ (PSFNM) materials have been synthesized using a sol-gel method in air and investigated as anode materials for SOFCs. Metallic nanoparticle-decorated ceramic anodes were obtained by the reduction of LSFNM and PSFNM in H2 at 850°C, forming a Ruddlesden–Popper oxide with exsolved FeNi3 bimetallic nanoparticles. The electrochemical performance of the Sr2Fe1.4Ni0.1Mo0.5O6–δ ceramic anode was greatly enhanced by La doping of A-sites, resulting in a 44% decrease in the polarization resistance in reducing atmosphere. The maximum power densities of Sr- and Mg-doped LaGaO3 (LSGM) (300 μm) electrolyte-supported single cells with LSFNM as the anode reached 1.371 W cm −2 in H2 and 1.306 W cm–2 in 50 ppm H2S–H2 at 850°C. Meanwhile, PSFNM showed improved sulphur tolerance, which could be fully recovered after six cycles from H2 to 50 ppm H2S–H2 operation. This study indicates that LSFNM and PSFNM are promising high-performance anodes for SOFCs.

     
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  2. Abstract

    A traditional composite cathode for proton‐conducting solid oxide fuel cells (H‐SOFCs) is typically obtained by mixing cathode materials and proton conducting electrolyte of BaCe0.7Y0.2Zr0.1O3–δ(BZCY), providing chemical and thermal compatibility with the electrolyte. Here, a series of triple‐conducing and cobalt‐free iron‐based perovskites as cathodes for H‐SOFCs is reported. Specifically, BaCexFe1–xO3–δ(x = 0.36, 0.43, and 0.50) shows various contents of two single phase perovskites with an in situ heterojunction structure as well as triple conductivity by tailoring the Ce/Fe ratios. The cell performance with the optimized BaCe0.36Fe0.64O3–δ(BCF36) cathode composition reaches 1056 mW cm−2at 700 °C. Moreover, a record cell performance of 1525 mW cm−2at 700 °C is obtained by modifying the BCF36 cathode microstructure through a spraying method, demonstrating high promise with Co‐free cathodes for H‐SOFCs.

     
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  3. Abstract

    The proton‐conducting solid oxide electrolysis cell (H‐SOEC) is a promising device that converts electrical energy to chemical energy. H‐SOECs have been actively studied in the past few years, due to their advantages over oxygen‐ion‐conducting solid oxide electrolysis cells (O‐SOECs), such as lower operation temperature, relatively lower activation energy, and easier gas separation. A critical overview of recent progress in H‐SOECs is presented, focusing particularly on the period from 2014 to 2018. This review focuses on three aspects of H‐SOECs, namely, the materials, modeling, and current leakage in proton conducting oxide electrolytes. Specifically, the current leakage in proton conducting oxides, which is often neglected, leads to two problems in the studies of H‐SOECs. One is the distortion of the electrochemical impedance spectra and the other is low faradaic efficiency of electrolysis. Based on the comprehensive and critical discussion in these three sections, challenges in the development of H‐SOECs are highlighted and prospective research in H‐SOECs is outlined.

     
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  4. Free, publicly-accessible full text available October 1, 2024