Facile Deficiency Engineering in a Cobalt-Free Perovskite Air Electrode to Achieve Enhanced Performance for Protonic Ceramic Fuel Cells.

As a crucial component responsible for the oxygen reduction reaction (ORR), cobalt-rich perovskite-type cathode materials have been extensively investigated in protonic ceramic fuel cell (PCFC). However, their widespread application at a commercial scale is considerably hindered by the high cost and inadequate stability. In response to these weaknesses, the study presents a novel cobalt-free perovskite oxide, Ba0.95La0.05(Fe0.8Zn0.2)0.95O3-δ (BLFZ0.95), with the triple-conducting (H+|O2-|e-) property as an active and robust air electrode for PCFC. The B-site deficiency state contributes significantly to the optimization of crystal and electronic structure, as well as the increase in oxygen vacancy concentration, thus in turn favoring the catalytic capacity. As a result, the as-obtained BLFZ0.95 electrode demonstrates exceptional electrochemical performance at 700 °C, representing extremely low area-specific resistance of 0.04 Ω cm2 in humid air (3 vol.% H2O), extraordinarily high peak power density of 1114 mW cm-2, and improved resistance against CO2 poisoning. Furthermore, the outstanding long-term durability is achieved without visible deterioration in both symmetrical and single cell modes. This study presents a simple but crucial case for rational design of cobalt-free perovskite cathode materials with appreciable performance via B-site deficiency regulation.

Perovskite nanoparticles@N-doped carbon nanofibers as robust and efficient oxygen electrocatalysts for Zn-air batteries.

We applied a novel solid-liquid co-electrospinning approach to synthesize hybrid LaCoO3 perovskite nanoparticles@nitrogen-doped carbon nanofibers (LCNP@NCNF) as an effective and robust electrocatalyst for Zn-air batteries. LCNP@NCNF featured an integrated structure with well-crystallized perovskite nanoparticles uniformly distributed in micro/mesoporous NCNF. In addition, LCNP@NCNF exhibited a high specific surface area of ~183.3 m2 g-1 and a large pore volume of ~0.164 m3 g-1. The rotating-electrode measurement revealed the better intrinsic activity and more favorable stability of LCNP@NCNF in comparison with their counterparts. Moreover, Zn-air batteries employing LCNP@NCNF showed a relatively smaller discharge-charge voltage gap of ~0.95 V and longer cycling stability than the battery adopting the physically blended LCNP and NCNF. We ascribed the improved electrochemical activity to the enhanced synergistic interaction originating from the successful coupling of LCNP and NCNF.