Electrode materials: a challenge for the exploitation of protonic solid oxide fuel cells

Fabbri, Emiliana; Pergolesi, Daniele; Traversa, Enrico

doi:10.1088/1468-6996/11/4/044301

Cited by 131 publications

(79 citation statements)

References 89 publications

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“…Moreover, water formation on the oxygen side instead of the fuel side prevents diluting the fuel, and hence, PCFCs can operate with higher fuel efficiency, simpler balance-ofplant, and reduced risk of anode oxidation. One of the main obstacles so far for utilizing the full potential of PCFCs is the poor performance of the cathode, and state-of-the-art SOFC cathode materials based on oxide mixed ion electron conducting electrode materials (O-MIECs) has not yet shown acceptable performance for PCFCs at intermediate temperatures [1]. In a fuel cell with protons as the only charge carriers, all faradaic current is in principle restricted to pass through the triple phase boundary (tpb) when supplied with O-MIEC or pure electron conducting electrodes.…”

Section: Introductionmentioning

confidence: 99%

Reaction Kinetics of Protons and Oxide Ions in LSM/Lanthanum Tungstate Cathodes with Pt Nanoparticle Activation

Strandbakke

Dyrlie

Hage

et al. 2016

J. Electrochem. Soc.

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Composite electrodes of La 0.8 Sr 0.2 MnO 3 (LSM) / La 28-x W 4+x O 54+3x/2 (x=0.85, "LWO56") on LWO56 electrolytes have been characterized by use of electrochemical impedance spectroscopy vs pO 2 and temperature from 900 ⁰C, where LWO56 is mainly oxide ion conducting, to 450 ⁰C, where it is proton conducting in wet atmospheres. The impedance data are analyzed in a model which takes into account the simultaneous flow of oxide ions and protons across electrolyte and electrodes, allowing extraction of activation energies and pre-exponential factors for the partial electrode reactions of protons and oxide ions. One composite electrode was infiltrated with Pt nanoparticles with average diameter of 5 nm, lowering the overall electrode polarization resistance (R p ) at 650 ⁰C from 260 to 40 Ω cm 2 . The Pt-infiltrated electrode appears to be rate limited by surface reactions with activation energy of ~90 kJ mol -1 in the low temperature proton 2 transport regime and ~150 kJ mol -1 in the high temperature oxide ion transport regime. The charge transfer reaction, which makes a minor contribution to R p , exhibits activation energies of ~85 kJ mol -1 for both oxide ion and proton charge transfer.

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Section: Introductionmentioning

confidence: 99%

Reaction Kinetics of Protons and Oxide Ions in LSM/Lanthanum Tungstate Cathodes with Pt Nanoparticle Activation

Strandbakke

Dyrlie

Hage

et al. 2016

J. Electrochem. Soc.

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“…In order to obtain larger triple phase boundary regions and reduced electrode polarizations, composite electrodes were used. 34 The anode support and the anode functional layers consisted of BZY and NiO powders in 4:6 weight ratio and the anode support was made more porous for easy gas diffusion by adding starch prior to the co-pressing and co-firing. Single cells containing PrBaCo 2 O 5+δ (PBCO) based composite electrode deployed with doped BZY electrolytes have shown impressive power output performances 35,36 and consequently, a composite mixture of PBCO and BZY in 7:3 weight ratio was chosen as the cathode in this study.…”

Section: Resultsmentioning

confidence: 99%

Y and Ni Co-Doped BaZrO₃as a Proton-Conducting Solid Oxide Fuel Cell Electrolyte Exhibiting Superior Power Performance

Shafi

Boulfrad

et al. 2015

J. Electrochem. Soc.

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The fabrication of anode supported single cells based on BaZr 0.8 Y 0.2 O 3-δ (BZY20) electrolyte is challenging due to its poor sinteractive nature. The acceleration of shrinkage behavior, improved sinterability and larger grain size were achieved by the partial substitution of Zr with Ni in the BZY perovskite. Phase pure Ni-doped BZY powders of nominal compositions BaZr 0.8-x Y 0.2 Ni x O 3-δ were synthesized up to x = 0.04 using a wet chemical combustion synthesis route. BaZr 0.76 Y 0.2 Ni 0.04 O 3-δ (BZYNi04) exhibited adequate total conductivity and the open circuit voltage (OCV) values measured on the BZYNi04 pellet suggested lack of significant electronic contribution. The improved sinterability of BZYNi04 assisted the ease in film fabrication and this coupled with the application of an anode functional layer and a suitable cathode, PrBaCo 2 O 5+δ (PBCO), resulted in a superior fuel cell power performance. With humidified hydrogen and static air as the fuel and oxidant, respectively, a peak power density value of 428 and 240 mW cm −2 was obtained at 700 and 600 • C, respectively. The increasing worldwide energy demand and the threatening environmental pollution from conventional fossil fuel combustion call for the thrive of sustainable alternative energy supply. In the past decade, there has been a growing interest toward proton conducting ceramics owing to their high proton conductivity with low activation energies at intermediate temperatures.1 These ceramic materials, termed as high temperature proton conductors (HTPCs), exhibit proton conductivity under hydrogen and/or steam atmospheres 2-6 and find applications as electrolyte membranes for proton conducting solid oxide fuel cells 7,8 and steam electrolyzers, 9,10 as well as hydrogen separation membranes. 11-14One of the major challenges for practical deployment has been the selection of an appropriate electrolyte material with adequate ionic conductivity at low temperatures, good processability, and chemical stability for long-term operation in working conditions. To date, although a wide range of proton conductor materials has been reported, 15,16 the majority of the researches on HTPC electrolytes still focus on BaCeO 3 and BaZrO 3 related materials.17,18 Y-doped BaCeO 3 (BCY) exhibits good sinterability with appropriate protonic conductivity, but practical application is hindered by its reactivity with acidic gases such as CO 2 that leads to decomposition into BaCO 3 and CeO 2 . In contrast, Y-doped BaZrO 3 (BZY) is chemically stable at fuel cell working conditions, but BZY poor sinterability results in large volumes of poorly conducting grain boundaries in ceramic bodies that end up in significantly reducing the total proton conductivity. Nonetheless, it has been reported that grain boundary free BZY thin films exhibit superior bulk proton conductivity. 19The fabrication of BZY-based cells with high ionic conductivity and dense microstructure is a major challenge. The refractory nature of BaZrO 3 hinders its application in fuel cells or other rel...

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“…Tremendous advantages result from its employment including cheaper interconnect materials, shorter start-up and shut-down time, easier and more reliable sealing, less chances of materials and performance degradation. Also as water in formed at the cathode side, hence fuel dilution is avoided which results in higher fuel utilization efficiency and in higher OCV values [2,3].…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2017

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Email Addresses of the corresponding authors: mohammad.naeem1@buitms.edu.pk and jtsi@st-andrews.ac.uk ABSTRACT Ba0.5Sr0.5Ce0.6Zr0.2Gd0.1Y0.1O3 -δ (BSCZGY) proton conducting electrolyte material for intermediate temperature solid oxide fuel cells (IT-SOFCs) has been synthesized by a sol-gel modified Pechini process and its sinterability, thermal expansion, microstructure, ionic conductivity and chemical stability have been investigated. Ionic conductivity at 700 ºC was measured to be ~ 8 x 10 -3 S cm -1 in wet 5 vol% H2/Ar atmospheres. Chemical stability test in pure CO2 up to 1200 ºC shows that the material is highly stable; better than the stability of BaZr0.3Ce0.5Y0.1Yb0.1O3 -δ.

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Electrode materials: a challenge for the exploitation of protonic solid oxide fuel cells

Cited by 131 publications

References 89 publications

Reaction Kinetics of Protons and Oxide Ions in LSM/Lanthanum Tungstate Cathodes with Pt Nanoparticle Activation

Reaction Kinetics of Protons and Oxide Ions in LSM/Lanthanum Tungstate Cathodes with Pt Nanoparticle Activation

Y and Ni Co-Doped BaZrO₃as a Proton-Conducting Solid Oxide Fuel Cell Electrolyte Exhibiting Superior Power Performance

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

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Electrode materials: a challenge for the exploitation of protonic solid oxide fuel cells

Cited by 131 publications

References 89 publications

Reaction Kinetics of Protons and Oxide Ions in LSM/Lanthanum Tungstate Cathodes with Pt Nanoparticle Activation

Reaction Kinetics of Protons and Oxide Ions in LSM/Lanthanum Tungstate Cathodes with Pt Nanoparticle Activation

Y and Ni Co-Doped BaZrO3as a Proton-Conducting Solid Oxide Fuel Cell Electrolyte Exhibiting Superior Power Performance

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

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Y and Ni Co-Doped BaZrO₃as a Proton-Conducting Solid Oxide Fuel Cell Electrolyte Exhibiting Superior Power Performance