Diapositiva 1

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18th November 2005
-INCONTRO PERIODICO GIOVANI RICERCATORI REGIONE
PIEMONTE-
Management and characterization of Polymer
Electrolyte Membrane Fuel Cell
M. Lucariello, P. Spinelli
Dipartimento di Scienza dei Materiali ed
Ingegneria Chimica, Politecnico di Torino, Corso
Duca degli Abruzzi 24, 10129 Torino, tel
0115644638, e-mail. marialaura.lucariello_at_polito.
it
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EXPERIMENTAL DETAILS
Structural and Electrochemical characterization
Commercial electrocatalyst Pt/C
Laboratory prepared electrocatalysts
MEA ASSEMBLING
PEMFC MANAGEMENT HARDWARE
PEMFC ELECTROCHEMICAL TESTING
MATHEMATICAL MODEL
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PEMFC MANAGEMENT
FUEL CELL TESTING HARDWARE by HySyTech for
PEMFC feeding with H2 or CH3OH
1,4W single cell (by ElectroChem)
Water dosing pump
CH3OH section
H2 section

• cell temperature and pressure
• evaporator temperature
• heating hoses temperature
• fuels mass flow and humidity

OPERATIONAL PARAMETERS CONTROLLED
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CATALYST LAYER PREPARATION AND CELL ASSEMBLING

Nafion solution 5 wt
Commercial Pt/C catalyst (20 wt. Pt on Vulcan
XC-72)
Deionized water and isopropyl alcohol or glycerol
STIRRING AND ULTRASONIC BLENDING
CATALYST INK
HOT PRESSING
MEA
TEFLONIZED CARBON CLOTH
PAINTING
NAFION MEMBRANE
PEMFC
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LAB-PREPARED MEAs POLARIZATION CURVES
(commercial Pt/C catalyst with different load)
ART6 MEA has a lower catalyst load than ART4
MEA, but comparable performances. The
preparation technique is more effective with low
catalyst load.
ART4 1.0 mg cm-2 Pt, Nafion 117
ART6 0.5 mg cm-2 Pt, Nafion117
ART12 MEA has a lower catalyst load, same
catalytic activity but lower performance than
ART11 MEA
ART11 0.5 mg cm-2 Pt, Nafion115
ART12 0.25 mg cm-2 Pt, Nafion115
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COMPARISON BETWEEN COMMERCIAL MEA AND
LAB-PREPARED MEA
Commercial MEA 1.0 mg cm-2 Pt, Nafion 115
LAB-PREPARED ART11 0.5 mg cm-2 Pt, Nafion115
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EXPERIMENTAL DATA ANALYSIS
COMMERCIAL MEA
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CYCLIC VOLTAMMETRY

• TECHNIQUE TO DETERMINE THE ELECTROCHEMICALLY
  ACTIVE SURFACE AREA OF PEMFC ELECTRODES
• PROCEDURE TO RECOVER DRIED MEAs
• TECHNIQUE TO ACTIVATE MEAs

CATHODIC FEEDING Ar 100 ml/min, 1 atm ANODIC
FEEDING H2 100 ml/min, 1 atm
VOLTAGE RANGE 0 -1,1 V
SCAN RATE 100 mV s-1
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COMPARISON BETWEEN COMMERCIAL MEA AND
LAB-PREPARED MEAs
Commercial MEA 1.0 mg cm-2 Pt, Nafion 115
ART6 0.5 mg cm-2 Pt, Nafion117
ART4 1.0 mg cm-2 Pt, Nafion 117
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COMPARISON BETWEEN DIFFERENT Pt LOAD OF
LAB-PREPARED MEAs
ART11 0.5 mg cm-2 Pt, Nafion115
ART12 0.25 mg cm-2 Pt, Nafion115
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MEA ACTIVATION
New laboratory prepared MEAs have been activated
by continuous voltammetric cycles.
AFTER ACTIVATION
BEFORE ACTIVATION
AFTER ACTIVATION (400 cycles)
?
?
?
BEFORE ACTIVATION
?
MEA ART 10 Cyclic voltammetries 0.5 mg cm-2
Pt, Nafion 117 and glycerol
MEA ART 10 Polarization curves V(I) 0.5 mg
cm-2 Pt, Nafion 117 and glycerol
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MEA RECOVERING
Keeping the MEA in a dry climate, causes a
decrease in membrane conductivity. Proton
conductivity of a MEA is strongly dependent on
the hydration level of the ionomer.
Recovering of a degraded MEA has been obtained
by continuous voltammetric cycles
BEFORE DEGRADATION
BEFORE DEGRADATION
AFTER ACTIVATION (400 cycles)
AFTER ACTIVATION
AFTER DEGRADATION
The treatment has been re-established the correct
hydration of the membrane .
Pt activation and membrane resistance decrease
took place during the voltammetric cycles.
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LABORATORY PREPARED CATALYST
Pt-transition metal alloy electrocatalysts have
better activity toward oxygen reduction reaction
(ORR) than Pt catalyst.
Catalyst
Pt-Co Alloy
Catalyst Fabrication Method
MECHANICAL ALLOIYNG (MA)
Pt (99.99, 45 103nm)
Co (99.99, 45 103nm)
MA
ELECTROCATALYST SAMPLES
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PHASE IDENTIFICATION
Three different solid solutions of Pt-Co have
been prepared by high energy ball milling
technique
XRD analysis
Pt as received
Pt0.75Co0.25
Pt0.50Co0.50
Pt0.25Co0.75
Co as received
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CRYSTALITE SIZES
Crystallite sizes and cell parameters of the
Pt-Co alloys have been determined fitting the
XRD patterns by the Rietveld method
Disordered solid solutions having nano-sized
structures have been obtained
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CELL PARAMETERS
The cell parameters (molar volumes) variation
toward the atomic percent of Pt is almost linear
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CONCLUSIONS

• A simple methodology for the laboratory
  preparation of the MEAs has been put up in view
  of catalytic layers testing having different
  composition.

• The obtained MEAs were characterized from the
  electrochemical view point, providing
  reproducible results.

• The management of the fuel cell was carried out a
  purposely designed hardware

• A simplified mathematical model has been proposed
  to obtain kinetic parameters from the
  experimental data.

• Mechanically alloyed Pt-Co electrocatalysts with
  nanometric grain size (30 nm) have been
  synthesized.

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AKNOWLEDGEMENTS
E. Ambrosio C. Francia N. Penazzi P. Spinelli
POLITECNICO DI TORINO
G. Mulas S. Enzo G. Cocco
UNIVERSITA DI SASSARI
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ELECTROCHEMICAL CHARACTERIZATION OF COMMERCIAL
MEAs
SINGLE CELL WITH GEOMETRICAL AREA OF 5 cm2 AND
REFERENCE ELECTRODE ELECTRODE 1 mg/cm2
Pt, 20 wt. Pt/Vulcan XC-72 ELECTROLITE
Nafion -115 GAS DIFFUSION LAYER Carbon Paper
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COMPARISON BETWEEN DIFFERENT NAFION THICKNESS OF
LAB-PREPARED MEAs
ART6 0.5 mg cm-2 Pt, Nafion117
ART11 0.5 mg cm-2 Pt, Nafion115
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• MESSA A PUNTO DI UNA STAZIONE DI PROVA PER LO
  STUDIO DI PEMFC
• CARATTERIZZAZIONE ELETTROCHIMICA DI MEA
  COMMERCIALI
• CARATTERIZZAZIONE ELETTROCHIMICA E STRUTTURALE DI
  MEA LAB-PREPARED CON CATALIZZATORI COMMERCIALI
• CARATTERIZZAZIONE ELETTROCHIMICA E STRUTTURALE DI
  LAB-PREPARED MEA CON CATALIZZATORI PREPARATI
  VIA AM

• NELLA CARATTERIZZAZIONE ELETTROCHIMICA
• CV E IV SU MEA COMMERCIALI
• CV E IV PER LA CAR DI MEA LAB PREP
• RECUPERO DI MEA DEGRADATE
• CV E IV CONFRONTO TRA MEA AVENTI DIFFERENTI
  CARICHI CATALITICI
• CV E IV CONFRONTO TRA MEA AVENTI DIFFERENTI
  SPESSORI DI NAFION