Bi-doped La2-xBixCu0.5Mn1.5O6 (LBCM-x, x=0, 0.1 and 0.2) were synthesized as potential cathode materials for intermediate -temperature solid oxide fuel cells. The effects of 6s(2) lone pair electrons on the electrical and electrochemical properties of LBCM5 were investigated. The results reveal that Bi3+ affects the properties of LBCMs in two ways. First, Bi doping can promotes the formation of oxygen vacancies, which is consistent with the results of first-principles calculations. The formation of oxygen vacancies can increase the amount of Mn3+/Mn4+ pairs for the hopping of electrons and accelerate the oxygen transportation. Second, Bi doping can affect the microstructure of LBCM5 and make LBCM-0.1 has the smallest grain size. The dual effects of Bi doping result in the highest electrical conductivity (143.91 Scm(-1)) as well as the lowest polarizationresistance(0.101(Omega cm(2))of LBCM-0.1 at 850 degrees C and make it a superior cathode candidate for solid oxide fuel cells.(C) 2017 Elsevier Ltd. All rights reserved.