Abstract:To design durable and reliable solid oxide fuel cells (SOFCs) for commercialization, we investigate the degradation behavior of yttria-stabilized zirconia-based anode-supported cells under two electrical load conditions -load trip (0.2-0 A • cm −2 ) and load cycle (0.20-0.12 A • cm −2 ) modes for 60 times (about 1,450 h). During the load trip condition, the operating voltage of the cell decreases by 86 mV through the 1,443 h operation (60 load trips) with the degradation ratio of 9.1% (59.5 μV • h −1 at 0.2 A … Show more
“…During normal SOFC operations, water is produced by the electrochemical reactions of transported oxygen ions through the electrolyte with hydrogen in the NiO-YSZ fuel electrode. Kim et al reported that atmospheres with a high water content (high a H 2 O ) that are formed in the anode during hydrogen oxidation reactions result in the growth and oxidation of Ni particles that become NiO in the fuel electrodes. This is because the increased a H 2 O in the gas phase leads to increased Ni(OH) 2 in the anode .…”
A critical
issue to tackle before successful commercialization
of solid oxide fuel cells (SOFCs) can be achieved is the long-term
thermal stability required for SOFCs to operate reliably without significant
performance degradation despite enduring thermal cycling. In this
work, the impact of thermal cycling on the durability of NiO-yttria-stabilized
zirconia-based anode-supported cells is studied using three different
heating/cooling rates (1, 2, and 5 °C min–1) as the temperature fluctuated between 400 and 700 °C. Our
experiments simulate time periods when power from SOFCs is not required
(e.g., as might occur at night or during an emergency shutdown). The
decay ratios of the cell voltages are 8.8% (82 μV h–1) and 19.1% (187 μV h–1) after thermal cycling
testing at heating/cooling rates of 1 and 5 °C min–1, respectively, over a period of 1000 h. The results indicate SOFCs
that undergo rapid thermal cycling experience much greater performance
degradation than cells that experience slow heating/cooling rates.
The changes in total resistance for thermally cycled cells are determined
by measuring the R
pol of the electrodes
(whereas the ohmic resistances of the cells remain unchanged from
their initial value), signifying that electrode deterioration is the
main degradation mechanism for SOFCs under thermal cycling. In particular,
fast thermal cycling leads to severe degradation in the anode part
of SOFCs with substantial agglomeration and depletion of Ni particles
seen in our characterizations with field emission–scanning
electron microscopy and electron probe microanalysis. In addition,
the mean particle size in the cathode after thermal cycling testing
increases from 0.104 to 0.201 μm for the 5 °C min–1 cell. Further, the presence of Sr-enriched regions is more significant
in the La0.6Sr0.4Co0.2Fe0.8O3−δ cathode after fast thermally cycled
SOFCs.
“…During normal SOFC operations, water is produced by the electrochemical reactions of transported oxygen ions through the electrolyte with hydrogen in the NiO-YSZ fuel electrode. Kim et al reported that atmospheres with a high water content (high a H 2 O ) that are formed in the anode during hydrogen oxidation reactions result in the growth and oxidation of Ni particles that become NiO in the fuel electrodes. This is because the increased a H 2 O in the gas phase leads to increased Ni(OH) 2 in the anode .…”
A critical
issue to tackle before successful commercialization
of solid oxide fuel cells (SOFCs) can be achieved is the long-term
thermal stability required for SOFCs to operate reliably without significant
performance degradation despite enduring thermal cycling. In this
work, the impact of thermal cycling on the durability of NiO-yttria-stabilized
zirconia-based anode-supported cells is studied using three different
heating/cooling rates (1, 2, and 5 °C min–1) as the temperature fluctuated between 400 and 700 °C. Our
experiments simulate time periods when power from SOFCs is not required
(e.g., as might occur at night or during an emergency shutdown). The
decay ratios of the cell voltages are 8.8% (82 μV h–1) and 19.1% (187 μV h–1) after thermal cycling
testing at heating/cooling rates of 1 and 5 °C min–1, respectively, over a period of 1000 h. The results indicate SOFCs
that undergo rapid thermal cycling experience much greater performance
degradation than cells that experience slow heating/cooling rates.
The changes in total resistance for thermally cycled cells are determined
by measuring the R
pol of the electrodes
(whereas the ohmic resistances of the cells remain unchanged from
their initial value), signifying that electrode deterioration is the
main degradation mechanism for SOFCs under thermal cycling. In particular,
fast thermal cycling leads to severe degradation in the anode part
of SOFCs with substantial agglomeration and depletion of Ni particles
seen in our characterizations with field emission–scanning
electron microscopy and electron probe microanalysis. In addition,
the mean particle size in the cathode after thermal cycling testing
increases from 0.104 to 0.201 μm for the 5 °C min–1 cell. Further, the presence of Sr-enriched regions is more significant
in the La0.6Sr0.4Co0.2Fe0.8O3−δ cathode after fast thermally cycled
SOFCs.
“…These BFCs consist of bioelectrodes where glucose, the substrate, undergoes the process of oxidation at the anode by the catalytic activity of an enzyme and subsequently produces electrons, which are responsible for creating electricity. Several factors affect the cell output efficiency, namely-the concentration of fuel, the mode or mechanism of transfer of electrons, the action of the enzyme, the potential of the cell, and others [ 21 , 79 , 80 ]. Fig.…”
Section: Types and Preparation Of Biofuel Cellsmentioning
“…To match the fluctuating electricity demand and generation in a future electricity grid, dominated by renewable energy sources like wind and photovoltaic, dynamic operation of fuel cells is required. Previous research has shown that the degradation und therefore the lifespan of Solid Oxide Cell (SOC) stacks shows a significant dependency on the operating conditions and dynamic load changes [3]. However, some research suggests that the degradation is not caused by the load changes itself but spatial temperature gradients during load changes [4][5][6].…”
In this work the authors designed and experimentally evaluated different controller topologies for fuel cell operation (SOFC) of a reversible solid oxide cell (rSOC) system. Aim of the controller is to operate the SOFC system autonomously at a constant maximum temperature for maximum efficiency. The controller design incorporates an artificial neuronal network (ANN) for real time state predictions. The training data for the ANN was generated by a Digital Twin of this system. The generated training data consists of about 16,000 different steady state operating conditions.
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