scholarly journals Experimental Study on the Effect of Hydrogen Sulfide on High-Temperature Proton Exchange Membrane Fuel Cells by Using Electrochemical Impedance Spectroscopy

Catalysts ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 441 ◽  
Author(s):  
Ren-Jun Kang ◽  
Yong-Song Chen
Keyword(s):  
Hydrogen Sulfide ◽  
High Temperature ◽  
Proton Exchange Membrane ◽  
Electrochemical Impedance ◽  
Proton Exchange ◽  
Operating Conditions ◽  
Cell Performance ◽  
Membrane Electrode ◽  
Pure Hydrogen ◽  
Exchange Membrane

When the fuel supplied to a high-temperature proton exchange membrane fuel cell (HT-PEMFC) is produced by hydrocarbon formation, hydrogen sulfide (H2S) may appear, resulting in decreased cell performance and durability. To study the effects of H2S on the performance and durability of the HT-PEMFC, a series of experiments was conducted. In the first step, the effects of polyvinylidene fluoride (PVDF) and platinum loading on cell performance were investigated and discussed under pure hydrogen operation conditions. Optimal PVDF and platinum compositions in the catalyst layer are suggested. Then, the effect of H2S on membrane electrode assembly (MEA) performance with various platinum loadings was investigated by supplying hydrogen containing 5.2 ppm of H2S to the anode of the MEA. An electrochemical impedance spectroscope was employed to measure the impedance of the MEAs under various operating conditions. Finally, degradation of the MEA when supplied with hydrogen containing 5.2 ppm of H2S was analyzed and discussed. The results suggest that the performance of an MEA with 0.7 mg Pt cm−2 and 10% PVDF can be recovered by supplying pure hydrogen. The rate of voltage decrease is around 300 μV h−1 in the presence of H2S.

scholarly journals Effect of Stratification of Cathode Catalyst Layers on Durability of Proton Exchange Membrane Fuel Cells

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2975
Author(s):  
Zikhona Nondudule ◽  
Jessica Chamier ◽  
Mahabubur Chowdhury
Keyword(s):  
Fuel Cells ◽  
Proton Exchange Membrane ◽  
Electrochemical Impedance ◽  
Catalyst Layer ◽  
Cost Effective ◽  
Proton Exchange ◽  
Membrane Electrode ◽  
Potential Cycling ◽  
Catalyst Layers ◽  
Exchange Membrane

To decrease the cost of fuel cell manufacturing, the amount of platinum (Pt) in the catalyst layer needs to be reduced. In this study, ionomer gradient membrane electrode assemblies (MEAs) were designed to reduce Pt loading without sacrificing performance and lifetime. A two-layer stratification of the cathode was achieved with varying ratios of 28 wt. % ionomer in the inner layer, on the membrane, and 24 wt. % on the outer layer, coated onto the inner layer. To study the MEA performance, the electrochemical surface area (ECSA), polarization curves, and electrochemical impedance spectroscopy (EIS) responses were evaluated under 20, 60, and 100% relative humidity (RH). The stratified MEA Pt loading was reduced by 12% while maintaining commercial equivalent performance. The optimal two-layer design was achieved when the Pt loading ratio between the layers was 1:6 (inner:outer layer). This MEA showed the highest ECSA and performance at 0.65 V with reduced mass transport losses. The integrity of stratified MEAs with lower Pt loading was evaluated with potential cycling and proved more durable than the monolayer MEA equivalent. The higher ionomer loading adjacent to the membrane and the bi-layer interface of the stratified catalyst layer (CL) increased moisture in the cathode CL, decreasing the degradation rate. Using ionomer stratification to decrease the Pt loading in an MEA yielded a better performance compared to the monolayer MEA design. This study, therefore, contributes to the development of more durable, cost-effective MEAs for low-temperature proton exchange membrane fuel cells.

scholarly journals Insight on Single Cell Proton Exchange Membrane Fuel Cell Performance of Pt-Cu/C Cathode

Catalysts ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 544 ◽  
Author(s):  
Marjan Bele ◽  
Matija Gatalo ◽  
Primož Jovanovič ◽  
Francisco Ruiz-Zepeda ◽  
Martin Šala ◽  
...  
Keyword(s):  
Single Cell ◽  
Proton Exchange Membrane ◽  
Electrochemical Impedance ◽  
High Current Density ◽  
Reduction Reaction ◽  
Proton Exchange ◽  
Membrane Electrode ◽  
Rotating Disc ◽  
Fuel Cell Performance ◽  
Exchange Membrane

The oxygen reduction reaction (ORR) properties of a proprietary PtCu3/C alloy electrocatalyst produced on a multi-gram scale are characterized by the conventional rotating disc electrode (RDE) method and by constructing a membrane electrode assembly (MEA) proton exchange membrane (PEM) single cell. The PtCu3 nanoparticles become porous, enriched in Pt on the surface, and exhibit a high RDE activity. The single cell electrochemical study reveals that, contrary to most advanced catalysts, the high ORR activity can be transferred from the RDE to the MEA. In the latter case, at 0.9VIRfree, a mass activity of 0.53 A/mgPt, at a Pt electrode loading of 0.2 mg/cm2, is achieved. However, at high current density, oxygen transport becomes limited. This is proven by the analysis of polarization curves and electrochemical impedance spectroscopy (EIS) data with a Kulikovsky (physical) model. These indicate that this limitation is caused by the non-optimal microporosity of our catalyst, which hinders the mass transport of oxygen during ORR. Based on our prospective results, one can realistically plan for further efforts to bridge the gap between the RDE and MEA measurements completely and achieve high power densities for Pt-alloy electrocatalysts.

Design and Experimental Characterization of a High-Temperature Proton Exchange Membrane Fuel Cell Stack

2011 ◽  
Vol 8 (5) ◽  
Author(s):  
Robert Radu ◽  
Nicola Zuliani ◽  
Rodolfo Taccani
Keyword(s):  
Fuel Cells ◽  
High Temperature ◽  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
Single Cells ◽  
Pem Fuel Cells ◽  
Proton Exchange ◽  
Pure Hydrogen ◽  
Exchange Membrane

Proton exchange membrane (PEM) fuel cells based on polybenzimidazole (PBI) polymers and phosphoric acid can be operated at temperature between 120 °C and 180 °C. Reactant humidification is not required and CO content up to 1% in the fuel can be tolerated, only marginally affecting performance. This is what makes high-temperature PEM (HTPEM) fuel cells very attractive, as low quality reformed hydrogen can be used and water management problems are avoided. From an experimental point of view, the major research effort up to now was dedicated to the development and study of high-temperature membranes, especially to development of acid-doped PBI type membranes. Some studies were dedicated to the experimental analysis of single cells and only very few to the development and characterization of high-temperature stacks. This work aims to provide more experimental data regarding high-temperature fuel cell stacks, operated with hydrogen but also with different types of reformates. The main design features and the performance curves obtained with a three-cell air-cooled stack are presented. The stack was tested on a broad temperature range, between 120 and 180 °C, with pure hydrogen and gas mixtures containing up to 2% of CO, simulating the output of a typical methanol reformer. With pure hydrogen, at 180 °C, the considered stack is able to deliver electrical power of 31 W at 1.8 V. With a mixture containing 2% of carbon monoxide, in the same conditions, the performance drops to 24 W. The tests demonstrated that the performance loss caused by operation with reformates, can be partially compensated by a higher stack temperature.

Dynamic Model of the High Temperature Proton Exchange Membrane Fuel Cell Stack Temperature

2009 ◽  
Vol 6 (4) ◽  
Author(s):  
Søren Juhl Andreasen ◽  
Søren Knudsen Kær
Keyword(s):  
High Temperature ◽  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
Cell Model ◽  
Thermal Control ◽  
Test System ◽  
Proton Exchange ◽  
Pure Hydrogen ◽  
Fuel Cell Stack ◽  
Exchange Membrane

The present work involves the development of a model for predicting the dynamic temperature of a high temperature proton exchange membrane (HTPEM) fuel cell stack. The model is developed to test different thermal control strategies before implementing them in the actual system. The test system consists of a prototype cathode air cooled 30 cell HTPEM fuel cell stack developed at the Institute of Energy Technology at Aalborg University. This fuel cell stack uses PEMEAS Celtec P-1000 membranes and runs on pure hydrogen in a dead-end anode configuration with a purge valve. The cooling of the stack is managed by running the stack at a high stoichiometric air flow. This is possible because of the polybenzimidazole (PBI) fuel cell membranes used and the very low pressure drop in the stack. The model consists of a discrete thermal model dividing the stack into three parts: inlet, middle, and end. The temperature is predicted in these three parts, where they also are measured. The heat balance of the system involves a fuel cell model to describe the heat added by the fuel cells when a current is drawn. Furthermore the model also predicts the temperatures when heating the stack with external heating elements for start-up, heat conduction through stack insulation, cathode air convection, and heating of the inlet gases in the manifold. Various measurements are presented to validate the model predictions of the stack temperatures.

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