Catalyst Degradation in Fuel Cell Electrodes: Accelerated Stress Tests and Model-based Analysis

Urchaga, Patrick; Kadyk, Thomas; Rinaldo, Steven G.; Pistono, Antonio O.; Hu, Jingwei; Lee, Wendy; Richards, Chris; Eikerling, Michael; Rice, Cynthia A.

doi:10.1016/j.electacta.2015.03.152

Cited by 52 publications

(35 citation statements)

References 42 publications

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“…Electrochemical measurements.-A classical glass threeelectrode electrochemical cell was used for the electrochemical studies with a graphite rod as the counter electrode 28 and the reference electrode was a Reversible Hydrogen Electrode (RHE) separated from the working electrode compartment by a luggin capillary with a glass frit (all potentials in this article are referenced to the RHE). A stationary glassy carbon electrode (5 mm diameter) covered with a thin layer of catalyst was used as working electrode, as described in the section below.…”

Section: Methodsmentioning

confidence: 99%

“…It has been observed that the potential profile applied during ADT between 0.6 and 0.95 V has an influence on the degradation rate and is usually greater for the square wave perturbation profile as compared with triangular wave perturbation profile or potential holding. 13,23 However, studies on Pt dissolution (from extended surfaces to supported nanoparticles) indicated that triangular waves lead to a higher dissolution of Pt at UPLs at or above 0.95 V. 23,27,28 More precisely, the dissolution seems to occur during the oxide layer reduction (cathodic sweep) and the amount of dissolved Pt is inversely proportional to the scan rate (1-100 mV sec −1 ) applied. 11,25,26,29 The ECSA loss due to increased number of ADT cycles shows initially a fast decay during the first 1000 perturbation cycles, followed by a gradual loss over an extended number of cycles.…”

Section: F1176mentioning

confidence: 99%

See 1 more Smart Citation

Platinum Dissolution in Fuel Cell Electrodes: Enhanced Degradation from Surface Area Assessment in Automotive Accelerated Stress Tests

Rice

Urchaga

Pistono

et al. 2015

J. Electrochem. Soc.

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Automotive fuel cells are plagued by high platinum-based cathode catalyst costs exacerbated by high catalyst loadings to circumvent performance losses induced by typical urban drive cycles. Accelerated durability tests are commonly used to evaluate the impact of nano-structure and/or operating conditions on cathode catalyst loss rates. To map out loss rates the electrochemical surface area (ECSA) of the catalyst is periodically monitored. Herein the accelerated stress testing was performed 25,000 times by imposing perturbations from 0.9 V to 0.6 V in a triangular wave profile while the ECSA was measured by assessing the hydrogen adsorption/desorption region with a lower potential limit of 0.025 V at intermittent points during the triangular wave perturbations. The ECSA loss observed during the 25,000 triangle wave cycles is 7% when measured only 2 times, but 26.3% when measured 250 times. The exacerbated losses during frequent low potential ECSA measurements suggest a restructuring of the catalyst surface due to the formation of a protective β-oxide, as seen by alterations in the cyclic voltammtric profile and particle size distribution. The increasing price of fossil fuel stimulated by an impending near future accessible supply depletion combined with the increased awareness of the adverse contributions of the Internal Combustion Engines (ICEs) on global warming has driven an international research thrust toward alternative energy production for personal automotive transportation from alternative energy technologies. Proton Exchange Membrane Fuel Cells (PEMFCs) currently appear as one of the potential alternatives to ICEs for automotive applications due to their higher efficiency and the fact that they use hydrogen and air (21% oxygen) as fuel and oxidant, respectively, with water as the only by-product. Furthermore, depending on the production method, hydrogen can be considered as a renewable source of energy if generated in ways such as electrolysis from either wind turbines or solar energy.The commercialization and massive production of automotive PEMFC technologies is still a challenge due to durability and cost limitations.1 The PEMFC type is the most suitable fuel cell technology to replace ICEs for vehicle propulsion because of the solid electrolyte permitting comparable travel distances, available power for frequent fast idle-to-peak transients to support typically sized personal vehicles and fast startup/shutdown. However, the relatively low working temperature of PEMFCs (typically below 100• C, due to membrane limitations) requires the use of Pt based catalysts for both the anode and the cathode catalyst layers thereby significantly increasing their price. Utilization of finely dispersed catalyst nanoparticles onto a high surface electrically conducting substrates (typically high surface carbon supports) and optimization of catalytic layers have yet allowed a drastic decrease of the catalytic layer cost by lowering the Pt loading by a factor of 10 (reaching 0.4 mg. cm −2 total loading) in the past 30 ...

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Section: Methodsmentioning

confidence: 99%

Section: F1176mentioning

confidence: 99%

Platinum Dissolution in Fuel Cell Electrodes: Enhanced Degradation from Surface Area Assessment in Automotive Accelerated Stress Tests

Rice

Urchaga

Pistono

et al. 2015

J. Electrochem. Soc.

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“…The related issues of high materials cost and poor effectiveness factor are aggravated by another challenge, namely the degradation of the catalytic performance caused by dissolution, coagulation and detachment of Pt nanoparticles. [14][15][16][17] Forays in electrocatalysis research therefore strive to rationalize the factors that control the ORR activity of Pt-based catalysts [18][19][20] and they increasingly place a focus on unraveling the critical correlation between ORR activity and Pt dissolution kinetics. [21][22][23] In this context, the mechanisms and rates of the ORR and Pt dissolution are intimately linked as they both proceed through the formation or reduction of chemisorbed oxygen species at the Pt surface.…”

Section: Introductionmentioning

confidence: 99%

Chemisorbed Oxygen at Pt(111): a DFT Study of Structural and Electronic Surface Properties

Malek

Eikerling

2017

Electrocatalysis

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Simulations based on density functional theory are used to study the electronic and electrostatic properties of a Pt (111) surface covered by a layer of chemisorbed atomic oxygen. The impact of the oxygen surface coverage and orientationally ordered interfacial water layers is explored. The oxygen adsorption energy decreases as a function of oxygen coverage due to lateral adsorbate repulsion. The surficial dipole moment density induced by the layer of chemisorbed oxygen causes a positive shift of the work function. In simulations with interfacial water layers, ordering and orientation of water molecules strongly affect the work function. It is found that the surficial dipole moment density and charge density are roughly linearly dependent on the oxygen surface coverage. Moreover, we found that water layers exert only a small impact on the surface charging behavior of the surface.

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“…[29][30][31][32] In the area of LIB research, Dreyer et al employed a population balance approach to study the phase-change behavior of randomly dispersed interconnected particles during lithium storage. 33 Röder et al used a similar approach to study the influence of the particle size distribution on LIB performance. 34 The present work aims to investigate the evolution of the SEI thickness distribution during cycling of the battery under different aging conditions.…”

mentioning

confidence: 99%

Statistical Physics-Based Model of Solid Electrolyte Interphase Growth in Lithium Ion Batteries

Tahmasbi

Kadyk

Eikerling

2017

J. Electrochem. Soc.

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The article presents a statistical physics-based model for the growth of the solid electrolyte interphase (SEI) in the negative electrode of lithium ion batteries. During battery operation, the SEI thickness grows by the reaction between lithium ions, electrons and solvent species on the surface of active particles at the negative electrode. The growth of the SEI layer causes a loss of lithium ions that induces capacity fade. In addition, it increases the ion transport resistance and decreases the total porosity. Our model employs a population balance formalism based on the Fokker-Planck Equation to describe the propagation of the particle density distribution function in the electrode. Structure-transforming processes at the level of individual particles are accounted for by using a set of kinetic and transport equations. These processes alter the particle density distribution function, and cause changes in battery performance. A parametric study of the model singles out the first moment of the initial SEI thickness distribution as the determining factor in predicting the capacity fade. The model-based treatment of experimental data allows analyzing processes that control SEI growth and extracting their controlling parameters. Lithium ion batteries (LIBs) are highly touted energy storage devices for portable electronics and electric vehicles.1 The LIB system consists of a negative electrode, a positive electrode, a separator, an electrolyte, and two current collectors. The most commonly used electrolytes are comprised of lithium salts, such as LiPF 6 in a solution of ethylene carbonate (EC) and dimethyl carbonate (DMC).1 The electrodes consist of randomly distributed and interconnected particles of active material, which store and release the lithium ions.Aging and degradation of LIBs have become major concerns for the operation of electric vehicles (EVs), which must fulfill exacting requirements in terms of durability, cyclability and overall lifetime. Battery aging is linked to the (electro-)chemical and mechanical degradation of the electrodes and the electrolyte.2 Three main degradation mechanisms prevail at the particle level during the cycling of LIBs:(1) growth of the solid electrolyte interphase (SEI) at the negative electrode, 2,3 (2) formation of cracks in the SEI layer at the negative electrode, 4 and (3) dissolution and isolation of nanocrystalline particles at the positive electrode.5 These processes lead to capacity fade and power loss.At the beginning of the battery life, particularly during the first cycle, the electrolyte undergoes reduction at the electrode/electrolyte interface, because the negative electrode operates at potentials that are outside of the electrochemical stability window of electrolyte components. This reduction is accompanied by the irreversible consumption of lithium ions.6 This process forms a passivating surface layer known as the solid electrolyte interphase. The SEI layer grows further during charging, thereby reducing the amount of active lithium ions. Moreover, this l...

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Catalyst Degradation in Fuel Cell Electrodes: Accelerated Stress Tests and Model-based Analysis

Cited by 52 publications

References 42 publications

Platinum Dissolution in Fuel Cell Electrodes: Enhanced Degradation from Surface Area Assessment in Automotive Accelerated Stress Tests

Platinum Dissolution in Fuel Cell Electrodes: Enhanced Degradation from Surface Area Assessment in Automotive Accelerated Stress Tests

Chemisorbed Oxygen at Pt(111): a DFT Study of Structural and Electronic Surface Properties

Statistical Physics-Based Model of Solid Electrolyte Interphase Growth in Lithium Ion Batteries

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