Publications de Arata Nakajo | EPFL Graph Search

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

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 ...

ELSEVIER2022

Fracture properties of porous yttria-stabilized zirconia under micro-compression testing

Arata Nakajo

Micro-compression tests were carried out on pillars of 60 mu m in diameter, milled by plasma focused ion beam in porous Yttria-Stabilized Zirconia (YSZ) pellets. The fracture properties were determined over a wide range of porosities (33 %-63 %) for 8YSZ a ...

ELSEVIER SCI LTD2022

Techno-Economic Optimization of an Integrated Biomass Waste Gasifier–Solid Oxide Fuel Cell Plant

Jürg Alexander Schiffmann, Jan Van Herle, Arata Nakajo, François Maréchal, Maria del Mar Perez Fortes, Victoria Xu Hong He

With a growing energy demand in a carbon-constrained society, fuels cells powered by renewable fuels, and specifically solid waste, are seen as interesting contributors to the energy portfolio. The alternative energy industry needs to reduce costs, enhance ...

2021

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

Jan Van Herle, Marco Cantoni, Arata Nakajo, Guillaume Jeanmonod, Priscilla Caliandro, Giorgio Rinaldi, Lucie Navratilova

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 ...

2020

Emerging Investigators in Electrochemical Energy Conversion and Storage 2020

Arata Nakajo

ASME2020

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

Jan Van Herle, Arata Nakajo, Priscilla Caliandro, Giorgio Rinaldi, Lucie Navratilova

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 ...

2019

Model-assisted identification of solid oxide cell elementary processes by electrochemical impedance spectroscopy measurements

Stefan Diethelm, Jan Van Herle, Arata Nakajo, Priscilla Caliandro

Electrochemical Impedance Spectroscopy (EIS) is extensively used to characterize Solid Oxide Cells (SOCs) to extract information on the elementary loss mechanisms. However, these individual mechanisms usually overlap in the frequency domain, requiring dedi ...

2019

Characterization of local morphology and availability of triple-phase boundaries in solid oxide cell electrodes

Jan Van Herle, Marco Cantoni, Arata Nakajo, Pierre Burdet, Giorgio Rinaldi

The performance of solid oxide cells is known to be dependent upon the density of three phase boundaries (TPB), but the potential for improving their effective electrocatalytic activity by morphological adjustments is imprecisely known. A spilling algorith ...

2019

Analytical transport network theory to guide the design of 3-D microstructural networks in energy materials: Part 1. Flow without reactions

Arata Nakajo

We present a fully analytical, heuristic model the "Analytical Transport Network Model" for steady-state, diffusive, potential flow through a 3-D network. Employing a combination of graph theory, linear algebra, and geometry, the model explicitly relates a ...

Elsevier Science Bv2017

Production and Reliability Oriented SOFC Cell and Stack Design

Jan Van Herle, Zacharie Wuillemin, Arata Nakajo, Fabio Greco, Xin Wang

This paper presents an innovative development methodology for a production and reliability oriented SOFC cell and stack design aiming at improving the stacks robustness, manufacturability, efficiency and cost. Multi-physics models allowed a probabilistic a ...

2017

The Effects of Component Tolerances on the Thermo-Mechanical Reliability of SOFC Stacks

Jan Van Herle, Zacharie Wuillemin, Arata Nakajo, Fabio Greco

The reliability of solid oxide fuel cell (SOFC) systems is closing the gap to meet the requirements for market implementation. Finite-element (FE) stack models, typically used for stack reliability analyses, commonly consider idealized components. In reali ...

2017

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

Jan Van Herle, Marco Cantoni, Arata Nakajo, Pierre Burdet, Emad Oveisi, Giorgio Rinaldi

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 ...

2017

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

Jan Van Herle, Marco Cantoni, Arata Nakajo, Pierre Burdet

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 ...

2017

Accessible triple-phase boundary length: A performance metric to account for transport pathways in heterogeneous electrochemical materials

Jan Van Herle, Marco Cantoni, Arata Nakajo

The performance of materials for electrochemical energy conversion and storage depends upon the number of electrocatalytic sites available for reaction and their accessibility by the transport of reactants and products. For solid oxide fuel/electrolysis ce ...

Elsevier Science Bv2016

Role of microstructure on electrode operating mechanisms for mixed ionic electronic conductors: From synchrotron-based 3D reconstruction to electrochemical modeling

Arata Nakajo

A typical La0.6Sr0.4Co0.2Fe0.8O3-delta (LSCF) electrode was reconstructed by X-ray nanotomography. The new Nano Imaging beamline ID16A-NI of the European Synchrotron Radiation Facility (ESRF) was used to conduct the investigation. Particular attention was ...

Elsevier Science Bv2016

Electrochemical Model of a Triode Solid Oxide Fuel Cell

Stefan Diethelm, Jan Van Herle, Arata Nakajo, Priscilla Caliandro

A Triode Solid Oxide Fuel Cell is a novel cell architecture that consists of two circuits: an auxiliary circuit, operated in electrolysis mode, and a conventional main fuel cell circuit. During triode operation, performance enhancement can be expected espe ...

2015

Characterization of Cracks and their Effects on the Effective Transport Pathways in Ni-YSZ Anodes after Reoxidation Using X-Ray Nanotomography

Jan Van Herle, Arata Nakajo, Fabio Greco, Siyuan Wang, Jian Wang

Reduction-oxidation cycling of Ni-based electrodes for solid oxide fuel/electrolysis cells irreversibly alters their microstructure and can cause the fracture of the electrolyte. Non-destructive 3-D imaging enables tracking of microstructural changes that ...

2015

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

Jan Van Herle, Zacharie Wuillemin, Arata Nakajo, Fabio Greco

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 ...

2015

Modelling the impact of creep on the probability of failure of a solid oxide fuel cell stack

Jan Van Herle, Arata Nakajo, Fabio Greco

In solid oxide fuel cell (SOFC) technology a major challenge lies in balancing thermal stresses from an inevitable thermal field. The cells are known to creep, changing over time the stress field. The main objective of this study was to assess the influenc ...

2014

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

Daniel Favrat, Jan Van Herle, Arata Nakajo

The 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 mod ...

Elsevier2012