Modeling of oxygen reduction mechanism for 3PB and 2PB pathways at solid oxide fuel cell cathode from multi-step charge transfer

Gong, Mingyang; Gemmen, Randall; Liu, Xingbo

doi:10.1016/j.jpowsour.2011.11.002

Cited by 57 publications

(72 citation statements)

References 46 publications

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“…In addition, both the phase fraction and grain shape can be used to tune the relative amount of TPB and SSA of LSM, which could be helpful in adjusting the relative amount of electrode surface pathway and bulk pathway in SOFC electrode. 12,13 The simulations in this work show that it is possible to tune the performance degradation rate by delicately designing the initial microstructure in SOFC cathode. However, to what extend these results are applicable to real SOFC electrodes is still pending more refined study and experimental verification.…”

Section: Discussionmentioning

confidence: 85%

“…the electrode surface pathway and the bulk pathway. 7,12,13 Due to the small ionic conductivity of LSM, the electrode surface pathway is considered to be dominating in the conventional composite cathode of LSM and YSZ. In this pathway, the oxygen molecule is converted to oxygen intermediates on the LSM surface, diffuses to the triple phase boundary (TPB) through surface diffusion and incorporates into YSZ at TPB.…”

mentioning

confidence: 99%

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Linking Initial Microstructure to ORR Related Property Degradation in SOFC Cathode: A Phase Field Simulation

Lei

Cheng

Wen

2017

J. Electrochem. Soc.

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Microstructure evolution driven by thermal coarsening is an important factor for the loss of oxygen reduction reaction rates in SOFC cathode. In this work, the effect of an initial microstructure on the microstructure evolution in SOFC cathode is investigated using a recently developed phase field model. Specifically, we tune the phase fraction, the average grain size, the standard deviation of the grain size and the grain shape in the initial microstructure, and explore their effect on the evolution of the grain size, the density of triple phase boundary, the specific surface area and the effective conductivity in LSM-YSZ cathodes. It is found that the degradation rate of triple phase boundary density and specific surface area of LSM is lower with less LSM phase fraction (with constant porosity assumed) and greater average grain size, while the degradation rate of effective conductivity can also be tuned by adjusting the standard deviation of grain size distribution and grain aspect ratio. Solid oxide fuel cell (SOFC) is a promising candidate to achieve clean electricity generation with high efficiency.1-5 Using ionic conductor, e.g. yttria stabilized zirconia (YSZ), as electrolyte, and perovskite oxides, e.g. La 1-x Sr x MnO 3 (LSM) or (La, Sr)(Co, Fe)O 3 (LSCF), as cathode material, SOFC usually operates at relatively high temperature, i.e. between 600• C to 1000• C, 1 due to the large activation energy for oxygen ion diffusion 6 and oxygen reduction reaction (ORR).7 This high operating temperature makes SOFC free from noble metal catalyst and highly flexible to a wide range of fuels.8 However, it also makes SOFC vulnerable to degradations caused by, for example, coarsening, secondary phase formation and Cr poisoning, [9][10][11] which limit the long-term stability of SOFC.Coarsening has been found to be one of the degradation mode in LSM-based SOFC cathode above 850• C. 11 The increased polarization resistance after coarsening suggests its impact on the ORR in the cathode. There are two possible pathways for ORR on LSM, i.e. the electrode surface pathway and the bulk pathway. 7,12,13 Due to the small ionic conductivity of LSM, the electrode surface pathway is considered to be dominating in the conventional composite cathode of LSM and YSZ. In this pathway, the oxygen molecule is converted to oxygen intermediates on the LSM surface, diffuses to the triple phase boundary (TPB) through surface diffusion and incorporates into YSZ at TPB. The rate determining step is still under debate, and it might depend on the operational condition and the microstructure. But it is known that both the TPB density and specific surface area (SSA) of LSM can influence the rate of the electrode surface pathway in the SOFC cathode.7,13 Previous experiments and simulations have shown that the coarsening in SOFC electrode leads to the loss of both the TPB density and the SSA of electrode phase, 14-17 which increases the polarization resistance in cathode. In addition, coarsening is known to increase the ohmic resistance in SOFC elect...

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Section: Discussionmentioning

confidence: 85%

mentioning

confidence: 99%

Linking Initial Microstructure to ORR Related Property Degradation in SOFC Cathode: A Phase Field Simulation

Lei

Cheng

Wen

2017

J. Electrochem. Soc.

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“…Finally, the third pathway is one where O 2 is absorbed by the surface of the cathode material and through a twostep charge transfer becomes 2O X in the bulk of the cathode material where it diffuses through the bulk to Brought to you by | MIT Libraries Authenticated Download Date | 5/10/18 7:13 AM arrive at the electrolyte. The design of our system and its pathways is inspired by the work of Gong et al [2]. For the system results given in Sections 3.1, 3.2, and 3.3, adsorption sites are located at multiple positions from the interconnect to the electrolyte.…”

Section: Sofc Cathode Modelmentioning

confidence: 99%

“…There are many models based on one or the other of these two views. Gong et al [2] have built a one-dimensional (1D) continuum model in order to study the interaction between O -formation and transport at the surface of the cathode material and O X (V .. O ) diffusion in the bulk. Experimental observation is still needed to confirm the existence of the intermediate product O - [1].…”

Section: Introductionmentioning

confidence: 99%

“…In other words, the model directly uses quantum mechanical energy eigenlevels (e.g., such as those which could be determined from the density of states of density functional theory (DFT) or from the potential energy surfaces of quantum chemistry) as input to the system description, a description which as a result contains the complete information of the particles (included in this case) and material (not included here) from an ab initio standpoint. The conventional approach for achieving a similar result requires several very different models to cooperate with each other, with each applicable to a given set of nonequilibrium phenomena at a particular time and length scale [2,[13][14][15][16][17][18][19][20][21] and each resulting in a large computational burden and requiring a range of expertise from the atomistic to the macroscopic. Clearly, the need for such cooperation is that very often microscopic and mesoscopic level properties not only influence performance at these levels but strongly do so at the macroscopic level as well.…”

Section: Introductionmentioning

confidence: 99%

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Multiscale Transient and Steady-State Study of the Influence of Microstructure Degradation and Chromium Oxide Poisoning on Solid Oxide Fuel Cell Cathode Performance

Spakovsky

Shen

et al. 2018

Journal of Non-Equilibrium Thermodynamics

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Oxygen reduction in a solid oxide fuel cell cathode involves a nonequilibrium process of coupled mass and heat diffusion and electrochemical and chemical reactions. These phenomena occur at multiple temporal and spatial scales, making the modeling, especially in the transient regime, very difficult. Nonetheless, multiscale models are needed to improve the understanding of oxygen reduction and guide cathode design. Of particular importance for long-term operation are microstructure degradation and chromium oxide poisoning both of which degrade cathode performance. Existing methods are phenomenological or empirical in nature and their application limited to the continuum realm with quantum effects not captured. In contrast, steepest-entropy-ascent quantum thermodynamics can be used to model nonequilibrium processes (even those far-from equilibrium) at all scales. The nonequilibrium relaxation is characterized by entropy generation, which can unify coupled phenomena into one framework to model transient and steady behavior. The results reveal the effects on performance of the different timescales of the varied phenomena involved and their coupling. Results are included here for the effects of chromium oxide concentrations on cathode output as is a parametric study of the effects of interconnect-three-phase-boundary length, oxygen mean free path, and adsorption site effectiveness. A qualitative comparison with experimental results is made.

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Root Cause Analysis of Degradation in Protonic Ceramic Electrochemical Cell with Interfacial Electrical Sensors Using Data‐Driven Machine Learning

Wu,

Wang,

Bian

et al. 2023

Advanced Science

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Protonic ceramic electrochemical cells (PCECs) offer promising paths for energy storage and conversion. Despite considerable achievements made, PCECs still face challenges such as physiochemical compatibility between componenets and suboptimal solid–solid contact at the interfaces between the electrolytes and electrodes. In this study, a novel approach is proposed that combines in situ electrochemical characterization of interfacial electrical sensor embedded PCECs and machine learning to quantify the contributions of different cell components to total degradation, as well as to predict the remaining useful life. The experimental results suggest that the overpotential induced by the oxygen electrode is 48% less than that of oxygen electrode/electrolyte interfacial contact for up to 1171 h. The data‐driven machine learning simulation predicts the RUL of up to 2132 h. The root cause of degradation is overpotential increase induced by oxygen electrode, which accounts for 82.9% of total cell degradation. The success of the failure diagnostic model is demonstrated by its consistency with degradation modes that do not manifest in electrolysis fade during early real operations. This synergistic approach provides valuable insights into practical failure diagnosis of PCECs and has the potential to revolutionize their development by enabling improved performance prediction and material selection for enhanced durability and efficiency.

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Modeling of oxygen reduction mechanism for 3PB and 2PB pathways at solid oxide fuel cell cathode from multi-step charge transfer

Cited by 57 publications

References 46 publications

Linking Initial Microstructure to ORR Related Property Degradation in SOFC Cathode: A Phase Field Simulation

Linking Initial Microstructure to ORR Related Property Degradation in SOFC Cathode: A Phase Field Simulation

Multiscale Transient and Steady-State Study of the Influence of Microstructure Degradation and Chromium Oxide Poisoning on Solid Oxide Fuel Cell Cathode Performance

Root Cause Analysis of Degradation in Protonic Ceramic Electrochemical Cell with Interfacial Electrical Sensors Using Data‐Driven Machine Learning

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