Long-Term Performance of Solid Oxide Stacks With Electrode-Supported Cells Operating in the Steam Electrolysis Mode

Performance characterization and durability testing have been completed on two five-cell high-temperature electrolysis stacks constructed with advanced cell and stack technologies. The solid oxide cells incorporate a negative-electrode-supported multi-layer design with nickel-zirconia cermet negative electrodes, thin-film yttria-stabilized zirconia electrolytes, and multi-layer lanthanum ferrite-based positive electrodes. The per-cell active area is 100 cm2. The stack is internally manifolded with compliant seals. Treated metallic interconnects with integral flow channels separate the cells and electrode gases. Stack compression is accomplished by means of a custom spring-loaded test fixture. Initial stack performance characterization was determined through a series of DC potential sweeps in both fuel cell and electrolysis modes of operation. Results of these sweeps indicated very good initial performance, with area-specific resistance values less than 0.5 Ω.cm2. Long-term durability testing was performed with a test duration of 1000 hours. Overall performance degradation was less than 10% over the 1000-hour period. Final stack performance characterization was again determined by a series of DC potential sweeps at the same flow conditions as the initial sweeps in both electrolysis and fuel cell modes of operation. A final sweep in the fuel cell mode indicated a power density of 0.356 W/cm2, with average per-cell voltage of 0.71 V at a current of 50 A.

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High Temperature Water Electrolysis Using Metal Supported Solid Oxide Electrolyser Cells (SOEC)

Advances in Science and Technology ◽

10.4028/www.scientific.net/ast.72.135 ◽

2010 ◽

Vol 72 ◽

pp. 135-143 ◽

Cited By ~ 5

Author(s):

Günter Schiller ◽

Asif Ansar ◽

Olaf Patz

Keyword(s):

High Temperature ◽

Fuel Cell ◽

Current Density ◽

Degradation Rate ◽

Cell Voltage ◽

Operating Conditions ◽

Solid Oxide ◽

Metallic Interconnect ◽

A Current

Metal supported cells as developed at DLR for use as solid oxide fuel cells by applying plasma deposition technologies were investigated in operation of high temperature steam electrolysis. The cells consisted of a porous ferritic steel support, a diffusion barrier layer, a Ni/YSZ fuel electrode, a YSZ electrolyte and a LSCF oxygen electrode. During fuel cell and electrolysis operation the cells were electrochemically characterised by means of i-V characteristics and electrochemical impedance spectroscopy measurements including a long-term test over 2000 hours. The results of electrochemical performance and long-term durability tests of both single cells and single repeating units (cell including metallic interconnect) are reported. During electrolysis operation at an operating temperature of 850 °C a cell voltage of 1.28 V was achieved at a current density of -1.0 A cm-2; at 800 °C the cell voltage was 1.40 V at the same operating conditions. The impedance spectra revealed a significantly enhanced polarisation resistance during electrolysis operation compared to fuel cell operation which was mainly attributed to the hydrogen electrode. During a long-term test run of a single cell over 2000 hours a degradation rate of 3.2% per 1000 hours was observed for operation with steam content of 43% at 800 °C and a current density of -0.3 Acm-2. Testing of a single repeating unit proved that a good contacting of cell and metallic interconnect is of major importance to achieve good performance. A test run over nearly 1000 hours showed a remarkably low degradation rate.

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Microstructure Evolution in a Solid Oxide Fuel Cell Stack Quantified with Interfacial Free Energy

Energies ◽

10.3390/en14123476 ◽

2021 ◽

Vol 14 (12) ◽

pp. 3476

Author(s):

Tomasz A. Prokop ◽

Grzegorz Brus ◽

Janusz S. Szmyd

Keyword(s):

Free Energy ◽

Fuel Cell ◽

Solid Oxide Fuel Cell ◽

Microstructure Evolution ◽

Ion Beam ◽

Solid Oxide ◽

Oxide Fuel ◽

Long Term Performance ◽

Term Performance

Degradation of electrode microstructure is one of the key factors affecting long term performance of Solid Oxide Fuel Cell systems. Evolution of a multiphase system can be described quantitatively by the change in its interfacial energy. In this paper, we discuss free energy of a microstructure to showcase the anisotropy of its evolution during a long-term performance experiment involving an SOFC stack. Ginzburg Landau type functional is used to compute the free energy, using diffuse phase distributions based on Focused Ion Beam Scanning Electron Microscopy images of samples taken from nine different sites within the stack. It is shown that the rate of microstructure evolution differs depending on the position within the stack, similar to phase anisotropy. However, the computed spatial relation does not correlate with the observed distribution of temperature.

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Analysis of Long-Term and Thermal Cycling Tests for a Commercial Solid Oxide Fuel Cell

Journal of Electrochemical Energy Conversion and Storage ◽

10.1115/1.4037232 ◽

2017 ◽

Vol 14 (4) ◽

Cited By ~ 3

Author(s):

Dustin Lee ◽

Jing-Kai Lin ◽

Chun-Huang Tsai ◽

Szu-Han Wu ◽

Yung-Neng Cheng ◽

...

Keyword(s):

Fuel Cell ◽

Thermal Cycling ◽

Solid Oxide Fuel Cell ◽

Coefficient Of Thermal Expansion ◽

Solid Oxide ◽

Oxide Fuel ◽

Flow Rates ◽

Degradation Rates ◽

Two Stages

The effects of isothermally long-term and thermal cycling tests on the performance of an ASC type commercial solid oxide fuel cell (SOFC) have been investigated. For the long-term test, the cells were tested over 5000 h in two stages, the first 3000 h and the followed 2000 h, under the different flow rates of hydrogen and air. Regarding the thermal cycling test, 60 cycles in total were also divided into two sections, the temperature ranges of 700 °C to 250 °C and 700 °C to 50 °C were applied for the every single cycle of first 30 cycles and the later 30 cycles, respectively. The results of long-term test show that the average degradation rates for the cell in the first 3000 h and the followed 2000 h under different flow rates of fuel and air are 1.16 and 2.64%/kh, respectively. However, there is only a degradation of 6.6% in voltage for the cell after 60 thermal cycling tests. In addition, it is found that many pores formed in the anode of the cell which caused by the agglomeration of Ni after long-term test. In contrast, the vertical cracks penetrating through the cathode of the cell and the in-plane cracks between the cathode and barrier layer of the cell formed due to the coefficient of thermal expansion (CTE) mismatch after 60 thermal cycling tests.

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Long-term tests of a Jülich planar short stack with reversible solid oxide cells in both fuel cell and electrolysis modes

International Journal of Hydrogen Energy ◽

10.1016/j.ijhydene.2013.01.192 ◽

2013 ◽

Vol 38 (11) ◽

pp. 4281-4290 ◽

Cited By ~ 108

Author(s):

Van Nhu Nguyen ◽

Qingping Fang ◽

Ute Packbier ◽

Ludger Blum

Keyword(s):

Fuel Cell ◽

Solid Oxide

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Coke-free operation of an all porous solid oxide fuel cell (AP-SOFC) used as an O2 supply device

Journal of Materials Chemistry A ◽

10.1039/c4ta05009f ◽

2015 ◽

Vol 3 (6) ◽

pp. 2684-2689 ◽

Cited By ~ 7

Author(s):

Y. M. Guo ◽

G. Largiller ◽

C. Guizard ◽

C. Tardivat ◽

D. Farrusseng

Keyword(s):

Fuel Cell ◽

Solid Oxide Fuel Cell ◽

Coke Formation ◽

Solid Oxide ◽

Operational Stability ◽

Porous Solid ◽

Cell Performance ◽

Oxide Fuel ◽

O2 Supply

An anode-supported AP-SOFC with long-term operational stability was developed to improve cell performance over 14 times without any coke formation.

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Application of an Anode Model to Investigate Physical Parameters in an Internal Reforming Solid-Oxide Fuel Cell

Journal of Fuel Cell Science and Technology ◽

10.1115/1.1895925 ◽

2005 ◽

Vol 2 (2) ◽

pp. 136-140 ◽

Cited By ~ 8

Author(s):

Eric S. Greene ◽

Maria G. Medeiros ◽

Wilson K. S. Chiu

Keyword(s):

Fuel Cell ◽

Solid Oxide Fuel Cell ◽

Structural Parameters ◽

Porous Electrode ◽

Cell Voltage ◽

Solid Oxide ◽

Physical Parameters ◽

Oxide Fuel ◽

Internal Reforming ◽

Porous Anode

A one-dimensional model of chemical and mass transport phenomena in the porous anode of a solid-oxide fuel cell, in which there is internal reforming of methane, is presented. Macroscopically averaged porous electrode theory is used to model the mass transfer that occurs in the anode. Linear kinetics at a constant temperature are used to model the reforming and shift reactions. Correlations based on the Damkohler number are created to relate anode structural parameters and thickness to a nondimensional electrochemical conversion rate and cell voltage. It is shown how these can be applied in order to assist the design of an anode.

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