Enhanced Sulfur and Coking Tolerance of a Mixed Ion Conductor for SOFCs: BaZr _0.1 Ce _0.7 Y _{0.2– x} Yb _x O _3–δ

Abstract

The anode materials that have been developed for solid oxide fuel cells (SOFCs) are vulnerable to deactivation by carbon buildup (coking) from hydrocarbon fuels or by sulfur contamination (poisoning). We report on a mixed ion conductor, BaZr(0.1)Ce(0.7)Y(0.2-)(x)Yb(x)O(3-delta), that allows rapid transport of both protons and oxide ion vacancies. It exhibits high ionic conductivity at relatively low temperatures (500 degrees to 700 degrees C). Its ability to resist deactivation by sulfur and coking appears linked to the mixed conductor's enhanced catalytic activity for sulfur oxidation and hydrocarbon cracking and reforming, as well as enhanced water adsorption capability.

Effects of H2O and CO2on Electrochemical Behaviors of BSCF Cathode for Proton Conducting IT-SOFC

“…[7][8][9] In comparison, proton conducting oxides, many of which are perovskite-structured, offer higher ionic conductivity with low electronic transport number as well as lower activation energy at intermediate temperature. [10][11][12][13][14][15][16] As a result, they are regarded as the preferred electrolyte for IT-SOFC. 17 For IT-SOFC, the cathode process is generally regarded as the rate-limiting step due to its high activation energy compared to the electrolyte.…”

“…7 In addition, how would the co-presence of H 2 O and CO 2 , which is a more realistic situation for practical SOFC operation, influence the electrochemical behavior for proton conducting SOFC with BSCF cathode has never been studied to the best of the authors' knowledge. 31,32 In this work, the chemical stability and compatibility of the BSCF cathode with one of the leading proton conducting electrolytes BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ (BZCYYb) [10][11][12]14,15 under various conditions were studied. More importantly, BSCF/BZCYYb/BSCF cathode symmetrical cells were used to investigate the influence of water vapor and CO 2 on the electrochemical behaviors for the proton conducting IT-SOFC at various temperatures ranging from 650…”

Retraction: High‐Performance Molybdenum Dioxide‐Based Anode for Dodecane‐Fueled Solid‐Oxide Fuel Cells (SOFCs)

“…To address this issue, two major approaches have been considered: using alternative anode materials with a high coking tolerance or co-feeding the fuel with a high concentration of oxidizing agents such as air, CO 2 , or water. [14][15][16][17][18][19] In our previous work we successfully produced a novel MoO 2 -based anode with an exceptionally high coking resistance for liquid hydrocarbons such as n-dodecane and biodiesel at an operating temperature of 850 8C. [20] The procedure developed in our group, which is based on the electrostatic spray deposition (ESD) method, has opened up the possibility of developing liquid hydrocarbon-fueled SOFCs.…”

Wet chemical synthesis and characterisation of Ba 0.5 Sr 0.5 Ce 0.6 Zr 0.2 Gd 0.1 Y 0.1 O 3−δ proton conductor

“…There was no evidence of carbonation when kept in flowing pure CO2 at 800 ºC for 24 hours and conductivity of 4 x 10 -3 S cm -1 at 600 ºC was measured, which is good enough for practical applications [31]. It showed a better densification as well and a relative density of ~ 95% after firing 1450 ºC, when processed via solid state reaction method; while for BZCY and BZCYYb, a sintering temperature 1550 ºC in required for getting a densification > 90% when processed by solid state reaction method [25,27].…”

“…However, later it has been reported that BZCY was unstable when it was kept in 3% (balanced with air) CO2 at 600 ºC for 24 hours and diffraction peaks corresponding to BaCO3 and CeO2 were observed in XRD [26]. Aliovalent Y + Yb co-doped BCZY showed better performance than BZCY and higher ionic conductivity of 14 x 10 -3 S cm -1 at 500 ºC [27,28]. However, though initially BaZr0.1Ce0.7Y0.2Yb0.1O3 -δ (BZCYYb) was reported to be stable in CO2 atmospheres, later it was found to be unstable when heated up to 800 ºC in CO2/N2 (1:2 ratio) atmosphere [29].…”