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Elucidating the impact of the ionomer equivalent weight on a platinum group metal-free PEMFC cathode via oxygen limiting current

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SusMat 2023年第1期3卷 72-90页

作者： HaoWang Luigi Osmieri Haoran Yu Michael J.Zachman Jae Hyung Park Nancy N.Kariuki Firat C.Cetinbas Sunilkumar Khandavalli Scott Mauger Deborah J.Myers David A.Cullen Kenneth C.Neyerlin Chemistry and Nanoscience Center National Renewable Energy LaboratoryGoldenColoradoUSA Center for Nanophase Materials Sciences Oak Ridge National LaboratoryOak RidgeTennesseeUSA Chemical Sciences and Engineering Division Argonne National LaboratoryLemontIllinoisUSA Nuclear Science and Engineering Division Argonne National LaboratoryLemontIllinoisUSA

Leveraging the interactions between ionomer and catalyst can increase the performance of proton exchangemembrane fuel *** impacts of the equivalent weight(EW)of perfluorosulfonic acid-based ionomers on the platinum group metal-free electrode structure and fuel cell performance have not been fully *** membrane electrode assemblies(MEAs)were prepared by using a commercial Fe-N-C catalyst,two perfluorosulfonic acid ionomers with different EWs,that is,Aquivion 720(A720)and Nafion 1100(N1100),and two ionomer-tocatalyst(I/C)*** four MEAswere characterized to understand the impact of the ionomer EW and content on the capacitance,proton conductivity,and mass transport on the *** mass transport resistance was measured for the first time using a new oxygen reduction reaction limiting current method enabling to couple the effects of oxygen diffusion with liquid water *** EW ionomer combined with a moderate I/C results in improved performance due to its enhanced proton ***,when used at high I/C,it can cause severewater flooding at high current density due to the enhanced liquid water uptake,especially at high relative humidity,resulting in lower catalyst utilization and higher mass transport resistance.

关键词： ionomer equivalent weight limiting current mass transport oxygen reduction reaction PGMfree catalyst proton exchange membrane fuel cell

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Identifying Diffusion limiting current to Unravel the Intrinsic Kinetics of Electrode Reactions Affected by Mass Transfer at Rotating Disk Electrode

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Chinese Journal of Chemical Physics 2022年第5期35卷 797-804,I0012页

作者： Mian-le Xu Wei Chen Ling-wen Liao Zhen Wei Jun Cai Yan-xia Chen Hefei National Laboratory for Physical Sciences at the Microscale Department of Chemical PhysicsUniversity of Science and Technology of ChinaHefei 230026China

Rotating disk electrode systems are widely used to study the kinetics of electrocatalytic reactions that may suffer from insufficient mass transfer of the *** current density at certain overpotential calculated by the Koutecky-Levich equation is commonly used as the metrics to evaluate the activity of ***,it is frequently found that the diffusion limiting current density is not correctly identified in the *** of kinetic current density,the measured current density normalized by diffusion limiting current density(j/jL)has also been frequently under circumstance where its validity is not *** taking oxygen reduction reaction/hydrogen oxidation reaction/hydrogen evolution reaction as examples,we demonstrate that identifying the actual diffusion limiting current density for the same reaction under otherwise identical conditions from the experimental data is essential to accurately deduce kinetic current *** analysis reveals that j/jLis a rough activity metric which can only be used to qualitatively compare the activity trend under conditions that the mass transfer conditions and the roughness factor of the electrode are exactly the *** addition,if one wants to use j/jLto compare the intrinsic activity,the concentration overpotential should be eliminated.

关键词： limiting current Kinetic current Mass transfer Activity metrics

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Measurement and separation of cathodic mass transport resistance in high temperature proton exchange membrane fuel cell

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Progress in Natural Science:Materials International 2020年第6期30卷 868-875页

作者： Ziqian Wang Linlin Yang Suli Wang Hai Sun Gongquan Sun Key Laboratory of Fuel Cells and Hybrid Power Sources Dalian Institute of Chemical Physics Chinese Academy of Sciences University of Chinese Academy of Sciences Dalian National Laboratory for Clean Energy Dalian Institute of Chemical Physics Chinese Academy of Sciences

High oxygen transport resistance in the cathode is a main cause of the low performance of high temperature proton exchange membrane fuel cell(HT-PEMFC), and therefore to determine the contribution of different mass transport processes to the oxygen transport resistance is beneficial to the subsequent research work. In this paper,the molecular diffusion resistance(R) in the cathode was successfully calculated by measuring the limiting currents with using different diluent gases. And the oxygen transport resistance in phosphoric acid(R) was analyzed by changing the humidity and temperature. It was found that the total oxygen transport resistance(R) increased obviously with the increase of the humidify, and the variation of Runder different conditions was mainly related to the change of R. Combined with the phenomenon that the experimental value of Rwas less than the calculated value at high humidity, but higher than that at high operation temperature, we speculate that the cause of that Rincreased obviously at high humidity is the occupancy or blockage of gas phase transport channel in catalyst layer(CL) by phosphoric acid due to the water absorption of phosphoric acid in CL and the swelling of membrane. This consequence indicates that it is the change of phosphoric acid distribution that dominate Cthe Rhigh humidity.

关键词： Electrochemistry Fuel cells High temperature proton exchange membrane Oxygen transport resistance limiting current

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Preparation and characterization of Ce_(0.8)Sm_(0.2)O_(1.9)-La_(0.8)Sr_(0.2)Cr_(0.5)Fe_(0.5)O_(3-δ) dual-phase membranes for oxygen permeation

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Journal of Materiomics 2020年第1期6卷 224-231页

作者： Guangjun Zhang Xiaonan Bao Fanrong Zeng Nguyen Q.Minh Shaorong Wang School of Chemical Engineering and Technology China University of Mining and Technology1st Da-xue RoadXuzhouJiangsu221116China Jiangsu Province Engineering Laboratory of High Efficient Energy Storage Technology and Equipments 1st Da-xue RoadXuzhouJiangsu221116China University of California San Diego9500 Gilman Drive La JollaCA92093-0147USA

In this study,with La_(0.8)Sr_(0.2)Cr_(0.5)Fe_(0.5)O_(3-δ)(LSCrF)and Ce_(0.8)Sm_(0.2)O_(1.9)(SDC)taken as the electronic conducting phase and the oxide ion conductor,respectively,dual-phase composite ceramic membranes with or without 3%(in mole)Y_(2)O_(3) stable ZrO_(2)(3YSZ)support were prepared and tested as oxygen separation ***,the oxygen transmission performance was tested by the electrochemical method based on the limiting *** results obtained with this method coincide with those acquired by means of gas ***,the dependences of oxygen permeation rate on oxygen partial pressure,temperature and ceramic membrane thickness were *** air was used as the sweeping gas on the porous 3YSZ supported SDC-LSCrF dual-phase membrane,the oxygen permeation rate can reach 0.73,0.82,0.90 and 0.97 mL cm^(-2) min^(-1) at 650,700,750 and 800℃,respectively.

关键词： Dual-phase Ceramic membranes Oxygen permeation limiting current

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