Understanding the Degradation Mechanisms of Understanding the Degradation Mechanisms of Membrane Membrane - - Electrode Electrode - - Assembly for High Temperature PEMFCs Assembly for High Temperature PEMFCs and and Optimization of the Individual Components Optimization of the Individual Components DEMMEA DEMMEA DEMMEA DEMMEA DEMMEA DEMMEA DEMMEA DEMMEA Brussels, November 2010 Joint Technology Initiatives-CP Coordinator: Dr. Stylianos Neophytides Advent Technologies SA
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Understanding the Degradation Mechanisms of Understanding the Degradation Mechanisms of MembraneMembrane--ElectrodeElectrode--Assembly for High Temperature PEMFCs Assembly for High Temperature PEMFCs
and and Optimization of the Individual ComponentsOptimization of the Individual Components
DEMMEADEMMEADEMMEADEMMEADEMMEADEMMEADEMMEADEMMEA
Brussels, November 2010
Joint Technology Initiatives-CP
Coordinator: Dr. Stylianos Neophytides Advent Technologies SA
� Understand the functional operation as well as the degradation
phenomena of high temperature H3PO4 imbibed PEM and its
electrochemical interface.
� Modeling in correlation with experimental observations.
� Combined use of advanced experimental techniques. Design and
development of accelerated tests and prediction tools for the
MEA’s performance.
� Make targeted modifications on the MEA system.
DEMMEADEMMEADEMMEADEMMEADEMMEADEMMEADEMMEADEMMEA Concerns of the DEMMEA project
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� Study of oxidative stability: Fenton test combined with NMR, SEC, Raman, XPS, DMA.
� Retention of acid and/or water: TGA, SEM, TEM
� Study of the proton conductivity by means of 4-probe current interruption method. Effect of polymer matrix and water vapor.
ABABABAB----PBI and variantsPBI and variantsPBI and variantsPBI and variants
Advent PEMs Advent PEMs Advent PEMs Advent PEMs
1. High Temperature Polymer Electrolyte Membranes
DEMMEADEMMEADEMMEADEMMEADEMMEADEMMEADEMMEADEMMEA
Catalyst degradation:
(i) platinum dissolution and redeposition known as Ostwald ripening
(ii) coalescence of platinum nanoparticles via platinum nanocrystallite migration on the carbon support
(iii) platinum particle agglomeration triggered by corrosion of carbon support and leaching of Pt and alloyed metals
Concerns of the DEMMEA project
2. Catalyst and Catalytic Layers
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New catalysts based on Pt supported on finely dispersed or structurally organized modified carbon supports (nanotubes, pyrolytic carbon).
� Study of catalyst stability and utilization by means of XRD, TEM, SEM-EDX, TGA, H2 chemisorption, Raman, XPS, RRDE and CV experiments & X-Ray tomography.
� Mathematical modeling of catalyst degradation.
� Proposal of a stable electrocatalytic layer with improved metal electrocatalyst utilization.
Concerns of the DEMMEA project
2. Catalyst and Catalytic Layers
DEMMEADEMMEADEMMEADEMMEADEMMEADEMMEADEMMEADEMMEA Concerns of the DEMMEA project
3. Membrane Electrode Assembly
ABPBI membrane; gas utilisation: air/H2= 2,0/1,2
Cathode: Pt= 1,3 mg.cm-2
, Anode: Pt= 0,7 mg.cm
-2
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Advent MEA
Feed: H2/O
2 1.2/2, Ambient pressure
Electrode area 25cm2
@ 180oC
@ 200oC
Study be means of combined electrochemical &
spectroscopic investigation techniques.
� Determination and optimization of Pt electrocatalytic utilization.
� Define a protocol correlating the accelerated MEA’s degradation rates with normal operation.
DEMMEADEMMEADEMMEADEMMEADEMMEADEMMEADEMMEADEMMEA Concerns of the DEMMEA project
3. Membrane Electrode Assembly
In-situ measurements
o Catalyst structure: In-situ X-ray absorption
o Adsorbed species on the catalyst: Delta µ XANES technique
o Electrochemical metal-electrolyte interface: Ambient Pressure
Photoelectron Spectroscopy (APES)
o Long term testing of the FC: I-V plots, AC Impedance, CV
o Parameters that affect the performance: I-V plots, AC Impedance
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Post mortem analysisPost mortem analysis
o MEA: Pt corrosion: TEM-EDX
o PEM degradation: NMR, SEC, Raman, XPS,
o Electrode: EDX and EFTEM
Quantitative determination of EASA of porous electrodes
o Catalyst: XRD, H2 chemisorption, Raman, XPS
Concerns of the DEMMEA project
3. Membrane Electrode Assembly
DEMMEADEMMEADEMMEADEMMEADEMMEADEMMEADEMMEADEMMEA The goal
Tailormade optimization of the MEA into a commercially reliable product for
