Effects of Bi doping on the microstructure, electrical and electrochemical properties of La2-xBixCu0.5Mn1.5O6 (x = 0, 0.1 and 0.2) perovskites as novel cathodes for solid oxide fuel cells.

Bi-doped La 2- x Bi x Cu 0.5 Mn 1.5 O 6 (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 LBCMs were investigated. The results reveal that Bi 3+ 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 Mn 3+ /Mn 4+ pairs for the hopping of electrons and accelerate the oxygen transportation. Second, Bi doping can affect the microstructure of LBCMs 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 polarization resistance (0.101 Ωcm 2 ) of LBCM-0.1 at 850 °C and make it a superior cathode candidate for solid oxide fuel cells. [ABSTRACT FROM AUTHOR]