Ameliorating La0.5Sr1.5MnO4 with Ni-doping to Enhance Cathode Electrocatalysis for Proton-Conducting Solid Oxide Fuel Cells

Cathodes with high electrocatalytic activity are critical for commercializing proton-conducting solid oxide fuel cells (H-SOFCs). Herein, B site acceptor Ni-doping is first attempted to ameliorate manganite-based Ruddlesden-Popper phase oxide La0.5Sr1.5MnO4+delta (LSMO), introducing more oxygen vacancies and new effective Ni2+-O-Ni3+ electron-hopping transition paths with an irregular structural deformation, ultimately enhancing the electrocatalysis with a 2.23 to 2.60 times improvement of electrical conductivity at 500-700 degrees C. The significantly enhanced oxygen/proton diffusion in the La0.5Sr1.5Mn0.7Ni0.3O4+delta (LSMN) sample, verified via electrical conductivity relaxation results, can enhance electrocatalytic activity, enabling more efficient oxygen reduction reaction kinetics. Hence, the Ni-ameliorated LSMN cathode exhibits a prominent power output of 1342 and 668 mW cm(-2) at 700 and 600 degrees C on a H-SOFC, surpassing the cells with the Ni-free LSMO cathode and other LSMO-based and Ln(2)NiO(4)-based cathodes in the literature. On balance, the excellent power density and polarization performance, together with the superior operation stability demonstrates that the LSMN candidate is a preferable alternative to H-SOFC cathodes. This work is an attempt to design highly active electrodes by regulating the crystal structure derived from B-site acceptor-doping, which is also beneficial for new material designs in H-SOFC and related electrocatalytic fields.