In this work, a La0.6Sr0.4Co0.2Fe0.8O3-delta (LSCF113) perovskite core coated by Ruddlesden-Popper phase La0.6Sr1.4Co0.2Fe0.8O4-delta (LSCF214) thin film to form a LSCF113-214 core-shell structure cathode is synthesized by Sr2+ solution coating method. Its phase composition, lattice structure, electrochemical catalytic activity and full cell performance are investigated. The electrocatalytic activity and stability of the LSCF113 cathode are enhanced by in situ formation of LSCF214 on the LSCF113 surface. The electrochemical performance enhancement is due to the higher catalytic activity of the LSCF214 Ruddlesden-Popper phase and the mismatch of the lattice parameters between the LSCF214 and LSCF113 regions leading to more favorable oxygen vacancy formation and oxygen molecule adsorption. The electrochemical impedance spectrum indicates that LSCF113-214 electrode has a lower polarization resistance (0.17 Omega cm(2)) than the LSCF113 electrode (0.32 Omega cm(2)) at 650 degrees C. And the long term stability of LSCF113-214 is evaluated with no structure evolution in 400 h test at 600 degrees C. An anode-supported single cell with doped ceria as the electrolyte is used to evaluate the electrochemical performance of LSCF113-214, which shows an open circuit voltage of 0.81 V and a maximum power density of 0.57 W cm(-2) at 650 degrees C. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.