Microstructural studies on degradation of interface between LSM–YSZ cathode and YSZ electrolyte in SOFCs

Liu, Yilin; Hagen, Anke; Barfod, Rasmus; Chen, Ming; Wang, Hsiang-Jen; Poulsen, F.W.; Hendriksen, Peter Vang

doi:10.1016/j.ssi.2009.07.011

Cited by 121 publications

(105 citation statements)

References 8 publications

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“…Indicators are used for the risk of reoxidation of the anode [21] and formation of undesirable zirconate phases (LZO, SZO) in the LSMeYSZ cathode. For the latter, the thermodynamic data on the critical oxygen partial pressure from Liu et al [12] is interpolated and compared with the local one, computed from the local overpotential and oxygen gas phase concentration.…”

Section: Modelling Approachmentioning

confidence: 99%

Progressive activation of degradation processes in solid oxide fuel cells stacks: Part I: Lifetime extension by optimisation of the operating conditions

Nakajo

Mueller

Brouwer

et al. 2012

Journal of Power Sources

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h i g h l i g h t s< Analysis of the combined effect of multiple degradation processes in SOFC stacks. < Acceleration of the degradation and sequential activation of processes is predicted. < Optimisation of the operating conditions can extend lifetime by a factor up to 10. < Operating conditions for the highest performance and the best durability differ. < Overpotential rather than current density influences the degradation behaviour. a r t i c l e i n f o t r a c tThe degradation of solid oxide fuel cells (SOFC) depends on stack and system design and operation. A methodology to evaluate synergistically these aspects to achieve the lowest production cost of electricity has not yet been developed.A repeating unit model, with as degradation processes the decrease in ionic conductivity of the electrolyte, metallic interconnect corrosion, anode nickel particles coarsening and cathode chromium contamination, is used to investigate the impact of the operating conditions on the lifetime of an SOFC system. It predicts acceleration of the degradation due to the sequential activation of multiple processes. The requirements for the highest system efficiency at start and at long-term differ. Among the selected degradation processes, those on the cathode side here dominate. Simulations suggest that operation at lower system specific power and higher stack temperature can extend the lifetime by a factor up to 10, because the beneficial decrease in cathode overpotential prevails over the higher release of volatile chromium species, faster metallic interconnect corrosion and higher thermodynamic risks of zirconate formation, for maximum SRU temperature below 1150 K. The counter-flow configuration, combined with the beneficial effect of internal reforming on lowering the parasitic air blower consumption, similarly yields longer lifetime than co-flow.

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Section: Modelling Approachmentioning

confidence: 99%

Progressive activation of degradation processes in solid oxide fuel cells stacks: Part I: Lifetime extension by optimisation of the operating conditions

Nakajo

Mueller

Brouwer

et al. 2012

Journal of Power Sources

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“…As for any multilayered system made of brittle materials, the MEA is prone to failures related to residual stresses generated during the manufacturing process, and to further thermal cycling and prolonged exposure to aggressive environments. During operation, physico-chemical alterations in the bulk and at the interfaces between the materials, ensuing sole or combined effects of material incompatibilities [7,8], particle growth [9e13] and contamination [14] have a consequence on the long-term reliability and resistance towards transient operation and thermal and reoxidation cycling [15e18]. Mori et al [19] and Sun et al [20] report a shrinkage of the Ni-yttria stabilised zirconia (YSZ) anode during thermal cycling.…”

Section: Introductionmentioning

confidence: 99%

Mechanical reliability and durability of SOFC stacks. Part II: Modelling of mechanical failures during ageing and cycling

Nakajo

Mueller

Brouwer

et al. 2012

International Journal of Hydrogen Energy

103

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Creep Contact analysis a b s t r a c tIntricate relationships between mechanical and electrochemical degradation aspects likely affect the durability of solid oxide fuel cell stacks. This study presents a modelling framework that combines thermo-electrochemical models including degradation and a contact thermo-mechanical model that considers rate-independent plasticity and creep of the components materials and the shrinkage of the nickel-based anode during thermal IntroductionThe end of operation of a solid oxide fuel cell (SOFC) stack ultimately occurs due to the loss of structural integrity of one or several of the cells, as highlighted by several short-stack experiments, e.g [1e4]. We believe this is the result of the accumulation during operation, of physico-chemical alterations inducing a weakening of the materials and interfaces, of plastic and creep deformations, and of the modification of the temperature profile, due to the degradation of the electrochemical performance of the cells. Mechanical issues do not, however, exclusively occur after prolonged use. Inappropriate control during start-up and shut-down and/or following of the electrical power demand, harsh characterisation procedures and thermal cycling can induce discrete failures [5,6]. Despite the evidence of mechanical issues in SOFCs, which are experienced even during laboratory button cell tests, this topic is still receiving limited attention. Efforts are seen as standalone tasks, owing to the different experimental and modelling techniques that are required to gather the essential information, whereas mechanical failures in SOFCs are likely intricately related to chemical and electrochemical aspects.The central component in a stack is the membrane electrode assembly (MEA). As for any multilayered system made of brittle materials, the MEA is prone to failures related to residual * Corresponding author. Tel.: þ41 21 693 35 05.E-mail address: arata.nakajo@epfl.ch (A. Nakajo).Available online at www.sciencedirect.com journal h om epa ge: www.elsev ier.com/locate/he i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 7 ( 2 0 1 2 ) 9 2 6 9 e9 2 8 6

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“…It is well known that LSM can react with YSZ at high temperatures to form insulating phases of La 2 Zr 2 O 7 (LZ) and SrZrO 3 (SZ) [3,16,17]. Both phases weaken the electrical contact of cathode/electrolyte because the conductivity of these zirconates is at least 2-3 orders of magnitude lower than that of YSZ electrolyte [18]. However, LZ and SZ phases formed at the interface will probably disappear from the three-phase boundaries on cathodic polarization because of the shift of the oxygen potential to the more reducing side [3].…”

Section: Phases Of the Ysz Filmsmentioning

confidence: 99%

Characterization of yttria-stabilized zirconia films deposited by dip-coating on La0.7Sr0.3MnO3 substrate: Influence of synthesis parameters

Marrero¹,

Ribeiro²,

Malfatti³

et al. 2013

J Adv Ceram

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Yttria-stabilized zirconia (YSZ, ZrO 2 -8%Y 2 O 3 ) films were deposited onto lanthanum strontium manganite (LSM, La 0.7 Sr 0.3 MnO 3 ) substrates using dip-coating process aiming for the application in solid oxide fuel cells (SOFCs). YSZ precursor was prepared by sol-gel method; three values of the organic/inorganic concentration ratio (1, 3 and 5) were utilized and the sol viscosity was adjusted (60 mPa·s and 100 mPa·s) before deposition on the substrate. The influence of these synthesis parameters on the structure and morphology of the deposited films was examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The films showed characteristic peaks of LSM, YSZ (with cubic structure) and secondary phases of SrZrO 3 and La 2 O 3 . Depending on the synthesis conditions, crack-free, homogeneous and well adhered films were obtained, with thickness of 11-24 m.

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Microstructural studies on degradation of interface between LSM–YSZ cathode and YSZ electrolyte in SOFCs

Cited by 121 publications

References 8 publications

Progressive activation of degradation processes in solid oxide fuel cells stacks: Part I: Lifetime extension by optimisation of the operating conditions

Progressive activation of degradation processes in solid oxide fuel cells stacks: Part I: Lifetime extension by optimisation of the operating conditions

Mechanical reliability and durability of SOFC stacks. Part II: Modelling of mechanical failures during ageing and cycling

Characterization of yttria-stabilized zirconia films deposited by dip-coating on La0.7Sr0.3MnO3 substrate: Influence of synthesis parameters

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