Manipulating cation nonstoichiometry towards developing better electrolyte for self-humidified dual-ion solid oxide fuel cells

Dual-ion (oxygen ion and proton) conducting electrolyte BaZr0.1Ce0.7Y0.1Yb0.1O3-delta (BZCYYb) is one of the most commonly used electrolyte materials for proton conducting fuel cells (PCFCs). Here, we improve conducting property and performance of BZCYYb electrolyte through simply introducing B-site cation deficiency. Dual-ion conductivities for Ba(Zr0.1Ce0.7Y0.1Yb0.1)(0.95)O3-delta (BZCYYb-0.95) electrolyte are improved to a large extent as 2.5 times protonic conductivity (4.6 x 10(-2) S cm(-1) at 700 degrees C) and 6.3 times oxygen ionic conductivity (1.2 x 10(-)(2) S cm(-1) at 900 degrees C) compared to BZCYYb electrolyte. Low-temperature (1350 degrees C) sinterability of BZCYYb-0.95 is achieved for the higher concentration of defect compared to the original material (BZCYYb, 1500 degrees C). Meanwhile, a cell with the BZCYYb-0.95 electrolyte illustrates prominent power density of 794 mW cm(-2) at 650 degrees C, superior to the cell with BZCYYb (643 mW cm(-2)) at the same condition. The collaborative diffusions of dualion via two different conducting mechanisms enhance the cell performance with BZCYYb-0.95 electrolyte. The cell voltage and power density actually have no observable performance degradation during the course of the 300-h test. Therefore, it indicates the dual-ion diffusions of BZCYYb-0.95 electrolyte as the promising future for practical application.