Sulfur Poisoning of Ni Anode as a Function of Operating Conditions in Solid Oxide Fuel Cells

Abstract

In the present study, we investigated the sulfur poisoning of the Ni anode in solid oxide fuel cells (SOFCs) as a function of operating conditions. Anode supported cells were fabricated, and sulfur poising tests were conducted as a function of current density, H 2 S concentration and humidity in the anode gas. The voltage drop was significant under the higher current density (~ 714 mA/cm 2) condition, while it was much reduced under the lower current density (~ 389 mA/cm 2) condition, at 100 ppm of H 2 S. A secondary voltage drop, which occurred only at the high current density, was attributed to Ni oxidation in the anode. Thus, operation at high current density with high H 2 S concentration may lead to permanent deterioration in the anode. The effect of water content (10%) on the sulfur poisoning was also investigated through a constant current test (~ 500 mA/cm 2) at 10 ppm of H 2 S. The cell operating with 10% wet anode gas showed a much smaller initial voltage drop, in comparison with a dry anode gas. The present study indicates that operating conditions, such as gas humidity and current density, should be carefully taken into account, especially when fuel cells are operated with H 2 S containing fuel.

Spatial sulfur poisoning behavior associated with in‐plane electrochemical performance variation of solid oxide fuel cells

“…In contrast, the current density was relatively stable in the 2nd drop section at 0.9 V (corresponding to a lower current density), in both 5 and 100 ppm; the lower the current density, the lower the drop % value in the 2nd drop section, which is the opposite to that in the 1st drop section. A higher degradation rate with higher current density was also observed in our previous studies and in other studies [20, 23, 25, 47]. The slow and continuous performance degradation in the 2nd drop section is related to irreversible anode microstructure changes (Ni oxidation and/or agglomeration), accelerated by increasing the current density.…”

High‐Performance Thermoelectric SnSe: Aqueous Synthesis, Innovations, and Challenges

“…Among the state‐of‐the‐art thermoelectric materials, tin selenide (SnSe) is one of the most promising candidates to apply to thermoelectric devices due to its environmentally friendly feature, high cost‐effectiveness, and outstanding thermoelectric performance derived from its appropriate bandgap of ≈0.9 eV and intrinsic low κ l 9,10 . Figure a shows the development timeline for all SnSe‐based bulk thermoelectric materials,11–124 from which a record high ZT of ≈2.8 at 773 K was found in the n‐type SnSe single crystal,11 derived from its ultralow κ l of ≈0.18 W m −1 K −1 and high S 2 σ of ≈9.0 µW cm −1 K −2 at this temperature 125. Such a high ZT is also very competitive to other state‐of‐the‐art thermoelectric systems which possess ZTs > 2, such as PbTe,126–134 GeTe,135–147 Cu 2 Se/Cu 2 S,148–157 and AgSbTe 2 158.…”

“…A summary of ZTs for SnSe‐based thermoelectric materials. a) The timeline for state‐of‐the‐art SnSe bulks thermoelectric materials,11–124,169–182 the performance achieved by solution route are circled by yellow. b) Temperature‐dependent ZT and c) corresponding peak and average ZT values for polycrystalline SnSe through different fabrication techniques 13,16,22,46,58,62,95,99,101.…”

Enhanced Thermoelectric Transport Properties of <i>n</i>-type InSe by Sn doping

“…Meanwhile, other efforts have been focused on discovering new thermoelectric materials. Among the various new thermoelectric materials, post-transition metal chalcogenides such as SnSe [9], In 4 Se 3 [10] and In 2 Se 3 [11], which consist of a two-dimensional layered structure, have attracted significant attention due to their intrinsically low lattice thermal conductivity (κ latt ), which is caused by the weak atomic bonding between layers (van der Waals bonds).…”

“…Additionally, SnSe and In 4 Se 3 materials exhibit a special phenomenon in which lattice softening [9] of the charge density wave (CDW) [10] occurs as the temperature increases.…”