Excellent electrochemical performance is achieved by PrBa0.5Sr0.5Co1.5Fe0.5O5+delta@La2NiO4+delta (PBSCF@LN) core-shell structure cathode, LN coating's existence enhances the cathode catalytic activity by promoting the oxygen reduction reaction (ORR) surface process. Besides the LN's excellent oxygen adsorption-desorption property, roughness surface of LN coating provides more ORR active sites compared to pristine PBSCF cathode. Thorough investigation is carried out based on the PBSCF and LN oxide's oxygen diffusion mechanism and corresponding ORR process elementary steps are constructed. Combine the theoretical derivations with experimental results, rate-determining step of PBSCF and PBSCF@LN cathode can be ascertained. With LN coating's introduction, PBSCF cathode's rate-determining step transfers from surface oxygen exchange to oxygen species' crossing LN coating, reducing thickness of LN coating can further improve PBSCF LN cathode' performance. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.