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28 results on '"Goswami, Navneet"'

15. Mechanistic interactions in polymer electrolyte fuel cell catalyst layer degradation.

Author

Goswami, Navneet, Grunewald, Jonathan B., Fuller, Thomas F., and Mukherjee, Partha P.

Abstract

Polymer Electrolyte Fuel Cells (PEFCs) exhibit considerable performance decay with cycling owing to the degradation of platinum (Pt) catalysts, resulting in the loss of the valuable electrochemically active surface area. Catalyst inventory retention is thus a necessity for a sustained cathodic oxygen reduction reaction (ORR) and to ameliorate the life expectancy of PEFCs. We demonstrate a thermo-kinetic model cognizant of processes like platinum particle dissolution–reprecipitation and oxide formation coupled with an electrochemical reactive transport model to derive mechanistic insights into the deleterious phenomena at the interfacial scale. The heterogeneous nature of particle aging in a catalyst layer environment is delineated through coarsening–shrinking zones and further comprehension of instability signatures is developed from the dissolution affinity of diameter bins through a metric, onset time. The severe degradation at high temperature and under fully humidified conditions is intertwined with the local transport resistance and the critical transient, where the catalyst nanoparticles reach a limiting diameter stage. We further reveal the degradation-performance characteristics through variation in the ionomer volume fraction and the mean size of the particle distribution in the electrode. It has been found that the kinetic and transport characteristics are crucially dependent on the interplay of two modes – one leading to the depletion of the catalyst nanoparticles and the other that emanates from catalyst coarsening. [ABSTRACT FROM AUTHOR]

Published
2022
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27. Mesoscale Physics in the Catalyst Layer of Proton Exchange Membrane Fuel Cells.

Author

Grunewald, Jonathan B., Fuller, Thomas F., Mistry, Aashutosh N., Verma, Ankit, Goswami, Navneet, and Mukherjee, Partha P.

Subjects
MESOCLIMATOLOGY, CATALYSTS, PROTON exchange membrane fuel cells
Abstract

Proton-exchange membranes fuel-cells (PEMFC) electrochemical performance insights are predicated on a detailed understanding of species transport in the cathode catalyst layer (CCL). Traditionally, CCL microstructure considerations were approached through approximations with unresolved pore-scale features. Such simplifications cause the loss of predictability for improving the economic feasibility via lower Pt-loading or non-noble metal catalysts. With advances in visualization, microstructure resolved mesoscale models become possible. A judicious combination of lattice Boltzmann (LBM) and finite volume (FVM) is an appropriate strategy for direct numerical simulation (DNS) of the physicochemical fields that remain unresolved due to spatiotemporal limitations. [ABSTRACT FROM AUTHOR]

Published
2019
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28. Modeling Proton Exchange Membrane Fuel Cell Cathode Catalyst Layers with the Lattice-Boltzmann-Method Framework

Author

Grunewald, Jonathan B, Goswami, Navneet, Mukherjee, Partha P., and Fuller, Thomas F.

Abstract

A Lattice-Boltzmann-Method model for a proton exchange membrane fuel cell (PEMFC) electrode has been presented. One of the main challenges in the development of the cathode catalyst layer (CCL) in PEMFCs is the lack of detailed understanding of species transport and how it affects electrochemical performance. Researchers have typically used high level approximations that oversimplify the microstructure of the CCL--these are known as macrohomogenous models. However, as the field has progressed, these idealizations have begun to show their flaws, especially in areas of improving catalytic performance with lower Pt-loadings and non-noble metal catalysts. Previously, the microstructure details needed to build an accurate mesoscale model have eluded researchers; however, with advances in tomography and focused-ion-beam scanning-electron-microscopy (FIB-SEM), creating these representations has become possible. Mesoscale modeling in the CCL has been traditionally approached through either the Lattice-Boltzmann-Method (LBM) or electrochemistry coupled Direct-Numerical-Simulation (DNS). These models have been underutilized in the fuel-cell community due to their complexity and resource intensiveness; however, with advances in parallel computing, this has become not only a possibility, but a necessity for modeling phenomena such as low platinum loadings and interfacial effects. The idea behind this model is to study a particular phenomenon - the effect of current density on saturation. While not the focus of this work, LBM can eventually be coupled with DNS in a synergistic modeling approach. This can shed light on the transport and degradation phenomena in PEMFCs, particularly catalyst layer considerations and carbon support corrosion.

Published
2019

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