Performance and Durability of Reversible Solid Oxide Cells with Nano-electrocatalysts Infiltrated Electrodes

Abstract

This work focuses on improving the durability of Ni/yttria-stabilized zirconia (YSZ) fuel electrode-supported solid oxide cells under the reversible operation mode by infiltrating nano-sized electrocatalysts into both electrodes. The resulting cell consists of a CGO (Gd-doped CeO2) scaffold-based oxygen electrode that is infiltrated with LSC (La0.6Sr0.4CoO3-δ) and CGPO (Gd, Pr-co-doped CeO2) nanocomposite infiltrates and a Ni/YSZ fuel electrode modified with nano-CGO infiltrates. Constant-current tests at + 0.5 A/cm2 and − 0.5 A/cm2 are carried out, followed by cycling between fuel-cell and electrolysis modes at ± 0.5 A/cm2 and ± 1.25 A/cm2. Under the reversible operation at ± 0.5 A/cm2, the cell showed lower degradation rates than under the single mode operation, with cell voltage degradation of 1.23%/kh in fuel cell mode and 0.53%/kh in electrolysis mode. During the cycling operation at ± 1.25 A/cm2, the overall degradation rate under the electrolysis mode was only 0.46%/kh. Compared to the previously tested cells with only LSC infiltrated oxygen electrodes, the cell tested in this work shows better durability with degradation rates of less than half of the previous tests. The results in this work demonstrate that infiltrating nano-electrocatalysts into both electrodes is an effective solution to boost cell performance and durability under reversible operation.

Performance and Degradation of Electrolyte Supported SOECs with Advanced Thin-Film Gadolinium Doped Ceria Barrier Layers in Long-Term Stack Test

“…These characteristic frequencies have been identified in previous work at DLR 9,10 and by other research groups. 12,14,19,[25][26][27][28][29] During the galvanostatic SOEC operation from 5180 h to 7935 h, the overall resistance R total at low frequencies in the impedance spectra increased from 991 mΩ•cm 2 to 1081 mΩ•cm 2 , i.e. +32.7 mΩ•cm 2 •kh -1 .…”

Electrochemical Performance and Durability of a Solid Oxide Cell with Nanoparticles-Modified Electrodes for CO2 Electrolysis

“…The cell voltage of Cell_S increased from 1167 to 1189 mV during the entire testing period, with a degradation rate of 24 mV/kh (25). As for Cell_R, a lower degradation rate of 0.53%/kh and 0.46%/kh were observed during the ±0.5 and ±1.25 A/cm 2 reversible testing under SOEC electrolysis mode (18). Despite operating at a higher temperature of 800 °C, the cell in this work has a much higher degradation compared to the cells tested under steam electrolysis.…”

“…Post-mortem Raman spectroscopy is needed to prove this. Comparison with steam electrolysis and SOEC/SOFC reversible operation A comparison was made between this test and two previously reported tests under steam electrolysis (denote as Cell_S) and reversible operation (denote as Cell_R) (18,25). All three cells have the same composition of CGO@Ni/YSZ|YSZ|CGO|LSC/CGPO@CGO and were infiltrated with the same electrocatalysts into both electrodes.…”

“…Specifically, Ce1-xPrxO2-δ (CPO) showed high electronic conductivity due to 4+/3+ oxidation states of PrO2 (16)(17). Previous research has demonstrated that the infiltrated cell maintains excellent stability with low degradation rates of 0.53-2% during constant steam electrolysis and reversible (electrolysis and fuel cell modes) operations (18)(19)(20). The investigation in this study is performed by electrochemical impedance spectroscopy (EIS) measurements.…”

Syngas Production from CO2 and H2O via Solid-Oxide Electrolyzer Cells: Fundamentals, Materials, Degradation, Operating Conditions, and Applications

“…Additionally, considerably higher degradation rates have been reported at higher current densities and lower operating temperatures . Interestingly, operation in the SOFC mode suppresses the electrode degradation induced during operation in the SOEC mode. ,− To explain this surprising result, Hughes et al hypothesized that shortened cycling may interrupt some unfavorable incubations (e.g., oxygen-bubble formation, cation migration, and zirconate-phase nucleation), which subsequently interrupt degradation. Therefore, the reversal of a current operation is also a promising approach for solving problems associated with oxygen-electrode delamination.…”