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Membranes for portable direct alcohol fuel cells
Desalination 200 (2006) 653–655
Membranes for portable direct alcohol fuel cells Vincenzo Antonuccia, Antonino S. Aricòa, Vincenzo Baglioa, John Bruneab, Irmgard Buderc*, Noelia Cabellod, Martin Hogarthd, Roland Martinb, Suzana Nunesc a
Istituto di Tecnologie Avanzate per l’Energia “Nicola Giordano", Salita Santa Lucia Sopra Contesse, 5 – 98126 – Messina, Italy b Solvay S.A. – Rue de Ransbeek 310 – B-1120 Brussels, Belgium c GKSS Research Centre Geesthacht GmbH, Institute of Polymer Research, Max-Planck-Str. 1, 21502 Geesthacht, Germany email: [email protected] d Johnson Matthey Technology Centre, Blount’s Court Road, Sonning Common, Reading, Berkshire, RG4 9NH, United Kingdom Received 18 October 2005; accepted 2 March 2006
1. Introduction Fuel cells are expected to play a major role in the future sustainable energy supply in stationary and automotive sectors, contributing to replace conventional power systems, which work on fossil fuels. Portable fuel cells are expected to come first and open the market for other applications. The potential market for portable fuel cell devices includes weather stations, medical devices, signal units, auxiliary power units (APU), gas sensors, etc. The objective of the European project MOREPOWER is to develop a low cost, lowtemperature portable direct methanol fuel cell (DMFC) device of compact construction and modular design. The aimed electrical characteristics are 40 A, 12.5 V (total power 500 W). The aimed values of DMFC single-cell performance are 0.5 V/cell at 0.1 A cm–2 for the midterm target *Corresponding author.
and 0.2 A cm–2 at 30–60°C (in atmospheric pressure air) as final target. The state-of-the-art DMFC devices developed mainly for automotive applications operate at temperatures up to 140°C using advantage of enhanced electrochemical and transport kinetic at higher temperatures. The targeted DMFC (and DEFC) device for portable application has to work at relatively low temperatures and atmospheric pressure. The effective operation at this low temperature is particularly challenging and requires innovation in different aspects of materials and system development. 2. Experimental 2.1. Development of new membranes with reduced fuel crossover New low-cost proton exchange membranes based on SOLVAY radiochemical grafting technology (Morgane® CRA type membrane
Presented at EUROMEMBRANE 2006, 24–28 September 2006, Giardini Naxos, Italy. 0011-9164/06/$– See front matter © 2006 Published by Elsevier B.V. doi:10.1016/j.desal.2006.03.489
654
V. Antonucci et al. / Desalination 200 (2006) 653–655
Table 1 Proton conductivity, methanol crossover, water and methanol permeabilities Membrane
Proton conductivity Methanol crossover at 60°C and at 60°C/mS cm–1 1 atm. pressure/mol min–2 cm–2
Nafion®117 CRA-08 SPEEK SPEEK-mod1
95 45 13 15
3.2 ´ 10–6
30°C ®117
Nafion
40°C
50°C
60°C
membrane
Atmospheric pressure
0.4 0.2 0
0
0.1
0.2 0.3 Current density (A cm–2)
Water permeability at 55°C/mol cm–1 min–1 15 ´ 6.2 ´ 3´ 1.6 ´
10–6 10–6 10–6 10–6
40°C
50°C
60°C
CRA-08 assembled at 80°C
0.6
Atmospheric pressure
0.4 0.2 0
0.4
10–7 10–7 10–7 10–7
30°C
0.8 Cell voltage (V)
Cell voltage (V)
4.5 ´ 1.5 ´ 0.5 ´ 0.2 ´
2.8 ´ 10–6
0.8 0.6
Methanol permeability at 55°C/mol cm–1 min–1
0
0.1
0.2 0.3 Current density (A cm–2)
0.4
Fig. 1. The polarization curves of Nafion®117 at different temperatures.
Fig. 3. The polarization curves of Nafion®117 of CRA-08.
variants) are under investigation, as well as membranes based on sulfonated poly (ether ether ketone) membranes (SPEEK). Further inorganic modification of SPEEK membranes (SPEEK-mod1) was developed to reduce the permeability to alcohols while keeping high proton conductivity.
2.2. Membrane characterisation
0.6
Atmospheric pressure
0.4
120 100 80 60 40 20 0
0.2 0
140
0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0
0
0.1
0.2 0.3 Current density (A cm–2)
0.4
Fig. 2. The polarization curves of Nafion®117 of SPEEK-mod1.
50
100 150 200 250 300 Current density (mA cm–2)
350
Power density (mW cm–2)
GKSS SPEEK-mod1 membrane
Cell voltage (V)
Cell voltage (V)
0.8
30°C 40°C 50°C 60°C
The membranes were washed in water and the proton conductivity was evaluated by
0 400
SOLVAY CRA-08, Air (l = 2) SOLVAY CRA-08, Air (l = 3) SOLVAY CRA-08, Air (l = 4) SOLVAY CRA-08, Power density air (l = 2) SOLVAY CRA-08, Power density air (l = 3) SOLVAY CRA-08, Power density air (l = 4)
Fig. 4. The polarization curves of CRA-08 at 60°C and different cathodic pressures (2, 3 and 4 bar).
V. Antonucci et al. / Desalination 200 (2006) 653–655
655
impedance spectroscopy in measurements at 106–10 Hz at 100% relative humidity. The water and methanol permeabilities across the membranes were measured by pervaporation at 55° C, using a 1.5 M methanol solution. The performance of CRA-08, SPEEK-mod1 and Nafion® was testes by JM and CNR-ITAE in different MEAs concerning performance, stability and methanol crossover.
The polarization curves of Nafion®117 at different temperatures are shown in Fig. 1, of SPEEK-mod1 in Fig. 2 and of CRA-08 in Fig. 3. The membrane electrode assembly was further optimized using different manufacture parameters including improved catalyst dispersion. In Fig. 4 the polarization curves of CRA-08 at 60°C and different cathodic pressures (2, 3 and 4 bar) are shown.
3. Results
4. Conclusions
The results of the proton conductivity measurements, the methanol crossover in a fuel cell and water and methanol permeabilities are listed in Table 1.
The new developed membranes have a performance at least as good as Nafion®117. The performance of 100 mA cm–2 at 0.5 is reached with an improved catalyst.
Membranes for portable direct alcohol fuel cells Vincenzo Antonuccia, Antonino S. Aricòa, Vincenzo Baglioa, John Bruneab, Irmgard Buderc*, Noelia Cabellod, Martin Hogarthd, Roland Martinb, Suzana Nunesc a
Istituto di Tecnologie Avanzate per l’Energia “Nicola Giordano", Salita Santa Lucia Sopra Contesse, 5 – 98126 – Messina, Italy b Solvay S.A. – Rue de Ransbeek 310 – B-1120 Brussels, Belgium c GKSS Research Centre Geesthacht GmbH, Institute of Polymer Research, Max-Planck-Str. 1, 21502 Geesthacht, Germany email: [email protected] d Johnson Matthey Technology Centre, Blount’s Court Road, Sonning Common, Reading, Berkshire, RG4 9NH, United Kingdom Received 18 October 2005; accepted 2 March 2006
1. Introduction Fuel cells are expected to play a major role in the future sustainable energy supply in stationary and automotive sectors, contributing to replace conventional power systems, which work on fossil fuels. Portable fuel cells are expected to come first and open the market for other applications. The potential market for portable fuel cell devices includes weather stations, medical devices, signal units, auxiliary power units (APU), gas sensors, etc. The objective of the European project MOREPOWER is to develop a low cost, lowtemperature portable direct methanol fuel cell (DMFC) device of compact construction and modular design. The aimed electrical characteristics are 40 A, 12.5 V (total power 500 W). The aimed values of DMFC single-cell performance are 0.5 V/cell at 0.1 A cm–2 for the midterm target *Corresponding author.
and 0.2 A cm–2 at 30–60°C (in atmospheric pressure air) as final target. The state-of-the-art DMFC devices developed mainly for automotive applications operate at temperatures up to 140°C using advantage of enhanced electrochemical and transport kinetic at higher temperatures. The targeted DMFC (and DEFC) device for portable application has to work at relatively low temperatures and atmospheric pressure. The effective operation at this low temperature is particularly challenging and requires innovation in different aspects of materials and system development. 2. Experimental 2.1. Development of new membranes with reduced fuel crossover New low-cost proton exchange membranes based on SOLVAY radiochemical grafting technology (Morgane® CRA type membrane
Presented at EUROMEMBRANE 2006, 24–28 September 2006, Giardini Naxos, Italy. 0011-9164/06/$– See front matter © 2006 Published by Elsevier B.V. doi:10.1016/j.desal.2006.03.489
654
V. Antonucci et al. / Desalination 200 (2006) 653–655
Table 1 Proton conductivity, methanol crossover, water and methanol permeabilities Membrane
Proton conductivity Methanol crossover at 60°C and at 60°C/mS cm–1 1 atm. pressure/mol min–2 cm–2
Nafion®117 CRA-08 SPEEK SPEEK-mod1
95 45 13 15
3.2 ´ 10–6
30°C ®117
Nafion
40°C
50°C
60°C
membrane
Atmospheric pressure
0.4 0.2 0
0
0.1
0.2 0.3 Current density (A cm–2)
Water permeability at 55°C/mol cm–1 min–1 15 ´ 6.2 ´ 3´ 1.6 ´
10–6 10–6 10–6 10–6
40°C
50°C
60°C
CRA-08 assembled at 80°C
0.6
Atmospheric pressure
0.4 0.2 0
0.4
10–7 10–7 10–7 10–7
30°C
0.8 Cell voltage (V)
Cell voltage (V)
4.5 ´ 1.5 ´ 0.5 ´ 0.2 ´
2.8 ´ 10–6
0.8 0.6
Methanol permeability at 55°C/mol cm–1 min–1
0
0.1
0.2 0.3 Current density (A cm–2)
0.4
Fig. 1. The polarization curves of Nafion®117 at different temperatures.
Fig. 3. The polarization curves of Nafion®117 of CRA-08.
variants) are under investigation, as well as membranes based on sulfonated poly (ether ether ketone) membranes (SPEEK). Further inorganic modification of SPEEK membranes (SPEEK-mod1) was developed to reduce the permeability to alcohols while keeping high proton conductivity.
2.2. Membrane characterisation
0.6
Atmospheric pressure
0.4
120 100 80 60 40 20 0
0.2 0
140
0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0
0
0.1
0.2 0.3 Current density (A cm–2)
0.4
Fig. 2. The polarization curves of Nafion®117 of SPEEK-mod1.
50
100 150 200 250 300 Current density (mA cm–2)
350
Power density (mW cm–2)
GKSS SPEEK-mod1 membrane
Cell voltage (V)
Cell voltage (V)
0.8
30°C 40°C 50°C 60°C
The membranes were washed in water and the proton conductivity was evaluated by
0 400
SOLVAY CRA-08, Air (l = 2) SOLVAY CRA-08, Air (l = 3) SOLVAY CRA-08, Air (l = 4) SOLVAY CRA-08, Power density air (l = 2) SOLVAY CRA-08, Power density air (l = 3) SOLVAY CRA-08, Power density air (l = 4)
Fig. 4. The polarization curves of CRA-08 at 60°C and different cathodic pressures (2, 3 and 4 bar).
V. Antonucci et al. / Desalination 200 (2006) 653–655
655
impedance spectroscopy in measurements at 106–10 Hz at 100% relative humidity. The water and methanol permeabilities across the membranes were measured by pervaporation at 55° C, using a 1.5 M methanol solution. The performance of CRA-08, SPEEK-mod1 and Nafion® was testes by JM and CNR-ITAE in different MEAs concerning performance, stability and methanol crossover.
The polarization curves of Nafion®117 at different temperatures are shown in Fig. 1, of SPEEK-mod1 in Fig. 2 and of CRA-08 in Fig. 3. The membrane electrode assembly was further optimized using different manufacture parameters including improved catalyst dispersion. In Fig. 4 the polarization curves of CRA-08 at 60°C and different cathodic pressures (2, 3 and 4 bar) are shown.
3. Results
4. Conclusions
The results of the proton conductivity measurements, the methanol crossover in a fuel cell and water and methanol permeabilities are listed in Table 1.
The new developed membranes have a performance at least as good as Nafion®117. The performance of 100 mA cm–2 at 0.5 is reached with an improved catalyst.