Evaluation for sintering of electrocatalysts and its effect on voltage drops in high-temperature proton exchange membrane fuel cells (HT-PEMFC)

Suzuki, Ai; Oono, Yuka; Williams, Mark C.; Miura, Ryuji; Inaba, Kenji; Hatakeyama, Nozomu; Takaba, Hiromitsu; Hori, Michio; Miyamoto, Akira

doi:10.1016/j.ijhydene.2012.09.016

Cited by 29 publications

(22 citation statements)

References 80 publications

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“…However, the thermodynamic open circuit voltage (OCV) decreases with an increase in the temperature, especially above 100 °C, due to the increase of the partial pressure of water [23,24,[26][27][28]. In addition, the durability of the carbon support and the supported catalyst at a high temperature are among the main challenges when seeking to maintain the performance and durability of a MEA for a high-temperature PEMFC [29].…”

Section: Catalystmentioning

confidence: 99%

Design and Synthesis of Cross-Linked Copolymer Membranes Based on Poly(benzoxazine) and Polybenzimidazole and Their Application to an Electrolyte Membrane for a High-Temperature PEM Fuel Cell

et al. 2013

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Elevated-temperature (100~200 °C) polymer electrolyte membrane (PEM) fuel cells have many features, such as their high efficiency and simple system design, that make them ideal for residential micro-combined heat and power systems and as a power source for fuel cell electric vehicles. A proton-conducting solid-electrolyte membrane having high conductivity and durability at elevated temperatures is essential, and phosphoric-acid-containing polymeric material synthesized from cross-linked polybenzoxazine has demonstrated feasible characteristics. This paper reviews the design rules, synthesis schemes, and characteristics of this unique polymeric material. Additionally, a membrane electrode assembly (MEA) utilizing this polymer membrane is evaluated in terms of its power density and lifecycle by an in situ accelerated lifetime test. This paper also covers an in-depth discussion ranging from the polymer material design to the cell performance in consideration of commercialization requirements. OPEN ACCESSPolymers 2013, 5 78

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Section: Catalystmentioning

confidence: 99%

Design and Synthesis of Cross-Linked Copolymer Membranes Based on Poly(benzoxazine) and Polybenzimidazole and Their Application to an Electrolyte Membrane for a High-Temperature PEM Fuel Cell

et al. 2013

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“…Such an approach for catalyst degradation, carbon corrosion and membrane degradation was presented for PEFC 94 and HT-PEFC. 95 It gives detailed information but requires many parameters of the respective fuel cell system. The opposite approach is to drastically reduce the level of detail or to focus on one specific degradation mode.…”

Section: Degradation Modelsmentioning

confidence: 99%

Accelerated Degradation of High-Temperature Polymer Electrolyte Fuel Cells: Discussion and Empirical Modeling

Reimer

Schumacher

Lehnert

2014

J. Electrochem. Soc.

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Accelerated stress tests are commonly applied in order to obtain a prediction of fuel cell life time within a short testing period. The stress test in this work considers a fuel cell which is constantly under load with frequent periods of very high current. Four different cells were operated each with a specific load profile. As a result severe performance degradation was observed in the region of high current densities. A short overview over the phenomena which may contribute to this specific fuel cell degradation is compiled from literature. Based on this overview major degradation modes are identified and combined with a simple polarization curve model. The modeling results allow for two different interpretations. Carbon corrosion reactions can explain the observed effects if cell voltage is assumed as the driving force for degradation. A better fit was obtained by using the overall heat flux as degradation criterion. In this case an increase in local temperature could lead to redistribution and loss of phosphoric acid from the MEA. The expected lifetime of a polymer electrolyte fuel cell (PEFC) ranges from 5 000 h for mobile application to 40 000 h for stationary application.1,2 In order to gain information about time dependent degradation in advance accelerated test protocols are used.3,4 Depending on the design of these tests valuable information about the nature of the main degradation mode under the applied operation conditions can be obtained. Despite the difference in operation conditions for PEFC, HT-PEFC and PAFC the structure and material of the electrodes are almost the same. Consequently, observed degradation phenomena show strong similarities.5 A good description of these phenomena can be found in several review papers 6-13 as well as in at least four books 1,2,14,15 where recent experimental facts and interpretations are summarized. A compact description can also be found in a recent review paper on modeling transport phenomena in PEFCs. 16 The purpose of this paper is to present the results of a specific accelerated degradation test for high temperature polymer electrolyte fuel cells (HT-PEFC) with phosphoric acid doped polybenzimidazole (PBI/H 3 PO 4 ) membranes. The fuel cell is constantly under load with frequent periods of very high current. In order to accelerate degradation effects the fuel cell is operated beyond it's point of maximum power. A simple polarization curve model is used as starting point for the analysis of data. Based on this first analysis a degradation model is proposed which allows for a straightforward physical interpretation. The complexity of degradation effects which occur simultaneousy usually leads to models which either resolve a specific mechanism in depth or describe more general effects. This paper aims at general effects which requires a broader understanding of degradation. In the following it is attempted to provide an overview over the phenomena which may contribute to fuel cell degradation. Based on this overview major degradation modes are identified and ...

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“…The 3D kinetic Monte Carlo (3D-KMC) sintering simulator [24], was applied to follow-up the sintering of electrocatalysts over time. The results of the catalytic morphological changes obtained by 3D-KMC could be reflected in the voltage calculation scheme, the developed code of the polarization loss [25,26], and the morphologically affected cell performance could be theoretically evaluated. Simulated results were compared with the measured results of experimental durability tests of the HT-PEMFC using PBI-H 3 PO 4 membranes for cell temperatures of 150 °C, 170 °C, and 190 °C [27,28].…”

Section: 1mentioning

confidence: 99%

Influence of the Sintering of Electrocatalysts and Decrease of Proton Conductivity on the Current-Voltage Performance in the High-Temperature Proton Exchange Membrane Fuel Cells (HT-PEMFC)

et al. 2014

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The influence of the sintering of electrocatalysts and decrease of the proton conductivity on the current-voltage performance in the HT-PEMFC was theoretically evaluated under the non-humid conditions at 150 °C, 170 °C and 190 °C. Decreasing rate of the proton conductivity was evaluated based on the tortuosity of the proton pass. The more the phosphoric acid was evaporated with a rise in temperature, the proton path found to become more tortuous and the proton conductivity was accordingly estimated to be decreased. A theoretical breakdown of the voltage drops indicated that the sintering of the electrocatalyst influenced on the voltage drop in earlier several hundreds of hours. The following voltage drop in the latter stage was caused mainly due to the decrease in the proton conductivity.

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Evaluation for sintering of electrocatalysts and its effect on voltage drops in high-temperature proton exchange membrane fuel cells (HT-PEMFC)

Cited by 29 publications

References 80 publications

Design and Synthesis of Cross-Linked Copolymer Membranes Based on Poly(benzoxazine) and Polybenzimidazole and Their Application to an Electrolyte Membrane for a High-Temperature PEM Fuel Cell

Design and Synthesis of Cross-Linked Copolymer Membranes Based on Poly(benzoxazine) and Polybenzimidazole and Their Application to an Electrolyte Membrane for a High-Temperature PEM Fuel Cell

Accelerated Degradation of High-Temperature Polymer Electrolyte Fuel Cells: Discussion and Empirical Modeling

Influence of the Sintering of Electrocatalysts and Decrease of Proton Conductivity on the Current-Voltage Performance in the High-Temperature Proton Exchange Membrane Fuel Cells (HT-PEMFC)

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