Publications by Arata Nakajo | EPFL Graph Search

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The locally-resolved degradation behavior was studied during 1900 hours in an SOFC repeat-element. In-situ measurements of local electrochemical performance were made on 18 locations over a segmented anode-supported cell. The evolution of local current densities, overpotentials and area-specific resistances was studied, showing a reorganization of the electrochemical reaction with time. The extent and the spatial distribution of degradation were established for different electrochemical reactions steps usin

The relevance of the phase-field approach to simulate the fracture in porous ceramics has been investigated. For this purpose, the conditions for the crack initiation using the phase-field model have been compared to the theoretical predictions of the coup ...

Solid oxide fuel cell (SOFC) stacks are extremely vulnerable to mechanical failures in any of their constituents, which ultimately lead to cell cracking. Like all devices, distinct failure sequences arise from different events or design particularities. Th ...

Structural stability issues in planar solid oxide fuel cells arise from the mismatch between the coefficients of thermal expansion of the components. The stress state at operating temperature is the superposition of several contributions, which differ depe ...

Understanding mechanisms that affect degradation and durability of solid oxide fuel cell (SOFC) stacks and systems is becoming increasingly important as systems are being deployed around the world. A novel simulation approach accounting for state-of-the-art understanding of degradation mechanisms in the context of an operating SOFC system has been developed. Investigative tools simulating lifetime degradation have been applied to a physical SOFC system model designed and controlled to allow dynamic dispatch

Solid Oxide Fuel Cells (SOFC) is an interdisciplinary technology by excellence, necessitating combined knowledge and R&D from mechanical, chemical, electrical and materials science engineering. At LENI Laboratory at EPFL, SOFC cells and stacks are designed, tested and analysed in collaboration with industry, from small area single cells to now kW-range stacks integrated in a system. The hardware R&D effort is strongly assisted by, and dependent on, modeling activities, for both design (e.g. new geometries)

Thermo-mechanical issues in solid oxide fuel cells (SOFC) must be understood and overcome to meet the reliability standards for market implementation. This study presents a thermo-mechanical model of an SOFC-stack SRU. The analysis starts with the simulati ...

The experimental validation of a real-time optimization (RTO) strategy for the optimal operation of a solid oxide fuel cell (SOFC) stack is reported in this paper. Unlike many existing studies, the RTO approach presented here utilizes the constraint-adapta ...

Microstructural changes in Ni–yttria stabilized zirconia (YSZ) near the YSZ electrolyte were examined by three-dimensional (3D) electron microscopy after electrolysis and fuel cell operation up to 10,700 h and 15,000 h, respectively. The depletion of Ni an ...

Intricate 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 ...

This study examines the effect of Ni migration near the interface with the electrolyte after fuel cell (SOFC) and electrolysis mode (SOEC) operation on nickel-yttria stabilized zirconia (Ni-YSZ) electrodes. The experimental dataset consists in a series of ...

Planar SOFC stack technology based on a unique concept (SOFConnex™) uses structured gas distribution layers between unprofiled metal sheet interconnects and thin Ni-YSZ anode supported electrolyte cells. The layers are flexible both in material and designa ...

The degradation of the Ni-YSZ electrode was investigated after SOFC or SOEC operation for up to 4,700 h and 10,700 h, respectively. 3-D FIB-SEM serial sectioning combined with 3-D EDS elemental mapping allowed the measurement of structural, material and el ...

Strontium migration from the oxygen electrode to the interface between the electrolyte and interlayer was investigated in solid oxide cells in fuel cell (SOFC) and electrolysis (SOEC) modes. Four samples were imaged by focused ion beam scanning electron mi ...

Arata Nakajo

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Locally-Resolved Study of Degradation in a SOFC Repeat- Element

Prediction of crack nucleation and propagation in porous ceramics using the phase-field approach

Compilation of mechanical properties for the structural analysis of solid oxide fuel cell stacks. Part II: Metallic interconnect, sealants and gas diffusion layers

Simulation of thermal stresses in anode-supported solid oxide fuel cell stacks. Part II: Loss of gas-tightness, electrical contact and thermal buckling

The Effects of Dynamic Dispatch on the Degradation and Lifetime of Solid Oxide Fuel Cell Systems

Solid Oxide Fuel Cell

Thermo-mechanical Reliability of SOFC Stacks During Combined Long-term Operation and Thermal Cycling

Experimental Real-Time Optimization of a Solid Oxide Fuel Cell Stack via Constraint Adaptation

Evolution of the Morphology Near Triple-Phase Boundaries in Ni–Yttria Stabilized Zirconia Electrodes Upon Cathodic Polarization

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

Effects of Polarization on the Microstructural Changes at the YSZ/Ni-YSZ Interface

Impact of Materials and Design on Solid Oxide Fuel Cell Stack Operation

Evolution of 3-D Transport Pathways and Triple-Phase Boundaries in the Ni-YSZ Hydrogen Electrode upon Fuel Cell or Electrolysis Cell Operation

Strontium Migration at the GDC-YSZ Interface of Solid Oxide Cells in SOFC and SOEC Modes

Experimental Real-Time Optimization of a Solid Oxide Fuel Cell Stack via Constraint Adaptation

Emerging Investigators in Electrochemical Energy Conversion and Storage 2020

Determination of an electrochemical model from experiments on a segmented solid oxide fuel cell