Triple conducting perovskite Ba0.95La0.05Fe0.8Zn0.2O3−δ as oxygen electrode for reversible protonic ceramic cells

• Published in: International journal of hydrogen energy 2023-03, Vol.48 (24), p.9037-9045
• Main Authors: Jing, Junmeng, Lei, Ze, Zheng, Ziwei, Wang, Haoran, Zhang, Panpan, Wang, Zhaowen, Xu, Hui, Yang, Zhibin
• Format: Article
• Language: English
• Subjects: Electrochemical performance; Oxygen electrode; Protonic ceramic electrolysis cell; Protonic ceramic fuel cell; Steam electrolysis
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2022.12.019

Reversible protonic ceramic cells (R-PCCs) have drawn much attention as energy conversion devices. However, the performance of R-PCCs is limited by the lack of highly active oxygen electrodes under operating conditions. Herein, crystal structure, oxygen non-stoichiometry, and conductivity of a triple-conducting perovskite Ba0.95La0.05Fe0.8Zn0.2O3−δ (BLFZ) are investigated. High oxygen vacancy concentration of BLFZ (δ = 0.575–0.705) is observed at a temperature range of 400–700 °C, as confirmed by combining thermo-gravimetric and iodometric titration results. The electrochemical reaction process of BLFZ-BaZr0.1Ce0.7Y0.1Yb0.1O3−δ (BZCYYb) electrode for symmetrical cells is elucidated by the distribution relaxation time (DRT) analysis. Oxygen dissociation is the rate-limiting step for protonic ceramic fuel cell (PCFC). At 650 °C, a single cell with BLFZ-BZCYYb oxygen electrode demonstrates the current density of 1070 mA cm−2 at 1.5 V in protonic ceramic electrolysis cell (PCEC) mode under wet H2 and 10% H2O-air atmospheres, achieving no apparent degradation of a cycling test for 200 h in dual modes of PCFC and PCEC. This research suggests that the triple-conducting perovskite BLFZ is a promising candidate for R-PCCs electrodes. [Display omitted] •High oxygen vacancy of BLFZ is comprehensively studied as oxygen electrode for R-PCC.•The rapid reaction rates and superior performance of BLFZ-BCZYYb were found.•No obvious degradation of a cycling test for 200 h in PCFC and PCEC mode are achieved.