2014 Hydrogen and Fuel Cells Program Annual Merit Review and Peer Evaluation Meeting Washington, DC – June 16-20, 2014
Advanced Materials and Concepts for Portable Power Fuel Cells
Piotr Zelenay Los Alamos National Laboratory Los Alamos, New Mexico 87545
Project ID: FC091
This presentation does not contain any proprietary, confidential, or otherwise restricted information
2014 Hydrogen and Fuel Cells Program Annual Merit Review – Slide 1 Overview
Timeline Partner Organization – Principal Investigator • Project start date: September 1, 2010
• Project end date: August 31, 2014 – Radoslav Adzic Budget
• FY13 DOE funding: $1,048K – Yushan Yan • $810K Planned FY14 funding: • Total DOE project value: $3,825K – James McGrath • Cost share: 8.2%
Barriers – Alex Martinez Bonastre • A. Durability (catalyst; electrode) • B. Cost (catalyst; membrane; MEA) – Christian Böhm • C. Electrode Performance (fuel oxidation kinetics) – Karren More
2014 Hydrogen and Fuel Cells Program Annual Merit Review – Slide 2 Relevance: Objective & Targets
Objective: Develop advanced materials (catalysts, membranes, electrode structures, membrane- electrode assemblies) and fuel cell operating concepts capable of fulfilling cost, performance, and durability requirements established by DOE for portable fuel cell systems; assure path to large-scale fabrication of successful materials
Technical Targets: Portable Power Fuel Cell Systems (< 2 W; 10-50 W; 100-250 W) Characteristics Units 2011 Status 2013 Targets 2015 Targets Specific power W/kg 5; 15; 25 8; 30; 40 10; 45; 50
Power Density W/L 7; 20; 30 10; 35; 50 13; 55; 70
Specific energy Wh/kg 110; 150; 250 200; 430; 440 230; 650; 640
Energy density Wh/L 150; 200; 300 250; 500; 550 300; 800; 900
Cost $/W 150; 15; 15 130; 10; 10 70; 7; 5 Durability Hours 1,500; 1,500; 2,000 3,000; 3,000; 3,000 5,000; 5,000; 5,000 Mean time between failures Hours 500; 500; 500 1,500; 1,500; 1,500 5,000; 5,000; 5,000
Original project technical targets (to be relaxed given modified targets above): • System cost target: $3/W
• Performance target: Overall fuel conversion efficiency (ηΣ) of 2.0-2.5 kWh/L For methanol fuel:
(1) 2.0-2.5 kWh/L → ηΣ = 0.42-0.52 (1.6-2.0× improvement over the state of the art, ~ 1.250 kWh/L)
(2) If ηfuel = 0.96, ηBOP= 0.90, Vth=1.21 (at 25°C) -1 Vcell = Vth [ηΣ (ηfuel ηBOP ) ] = 0.6 V
2014 Hydrogen and Fuel Cells Program Annual Merit Review – Slide 3 Approach: Focus Areas & FY15 Milestones
• DMFC anode research (JMFC, LANL, BNL): (i) new catalysts with improved activity and reduced cost; (ii) durability improvements • Innovative electrode structures for better activity and durability (UD) • Hydrocarbon membranes for lower MEA cost and enhanced fuel cell performance (VT, LANL): (i) block copolymers; (ii) copolymers with cross-linkable end-groups • Alternative fuels for portable fuel cells: (i) dimethyl ether research (LANL); (ii) ethanol oxidation electrocatalysis (BNL) • Advanced materials characterization (ORNL, BNL, LANL); MEA performance testing, including durability (LANL, JMFC, SFC); ten-cell stack (SFC)
Date Milestones Status Comment
Synthesize multiblock copolymer based on tetramethyl > 200 mA cm-2 at 0.50 V achieved in a DMFC Dec 13 bisphenol A capable of delivering > 200 mA cm-2 at 0.50 Complete operating with TM-based multiblock copolymer at a V (DMFC, 75°C). cell temperature of 25°C Improve mass activity of the precious metal catalyst of Mass activity of 55 A g-1 (0.230 A cm-2) achieved with -1 -1 Mar 14 DME oxidation from the present-day 37 A g to 50 A g Complete LANL-developed ternary Pt55Ru35Pd10/C catalyst at at 0.50 V (DDMEFC, 80°C). low Pt cathode loading (2.0 mg cm-2). Achieve the DMFC performance goal of 150 mA cm-2 at Presently 40 mV away from target (150 mA cm-2 at Jun 14 Pending 0.6 V with low Pt loadings (< 1.0 mg cm-2 at anode). 0.56 V, 90°C). 10-cell DMFC stack utilizing JMFC’s “advanced Complete testing of a short stack utilizing fully optimized anode catalyst” (AAC) tested by SFC Energy for Sep 14 Complete new components developed in the project. over 2,500 h; performance loss below that of a commercial stack with 2× higher PtRu loading.
2014 Hydrogen and Fuel Cells Program Annual Merit Review – Slide 4 MeOH Oxidation: Advanced Anode Catalyst (AAC) Development
Main activities: (i) further development of AAC (advanced anode catalyst) to meet the project milestone (0.15 A cm-2 at 0.60 V) and (ii) stack demonstration (in collaboration with SFC Energy)
-2 Strategy: (i) increase AAC loading from 1.0 to 2.0 mgPt cm (backup slide); (ii) lower carbon content to thin electrode layer; (iii) optimize Pt-to-Ru ratio to lower onset potential of MeOH oxidation; (iv) modify cell operating conditions (temperature, concentration)
2 -1 Catalyst Pt:Ru atomic ratio Surface area by COads (m g ) HiSPEC® 12100 1:1 37 PtRu/C advanced anode catalyst (AAC) 1:4 20 PtRuC (new catalyst) 1:6 29
-2 • No significant gain in AAC Note: Anode loading limited to 0.8 mgPt cm due to catalyst flaking at higher loadings performance brought about by catalyst loading increase (backup slide) • A 33% increase in wt% of metal
(Pt+Ru) in AAC having no effect on catalytic activity Voltage / V
• Pt-to-Ru 1:4 atomic ratio: Optimum or combination of fast dehydrogenation,
efficient CO removal and low Ru Potential crossover to cathode 2 • Highlight: Ten 50 cm MEAs with • Cell: 80ºC optimized AAC prepared and supplied
-2 to SFC Energy for final stack testing Current Density / mA cm
2014 Hydrogen and Fuel Cells Program Annual Merit Review – Slide 5 MeOH Oxidation: Testing Under Different Conditions
-2 -2 Anode: AAC, 1.0 mgPt cm , 0.5 - 0.6 M MeOH; Cathode: Pt/C, 1.5 mgPt cm , air (fuel cell ), H2 (anode polarization); Membrane: Nafion 115; Cell: 80 - 88°C
Cathode
Project performance target Voltage / V / Voltage or
Anode Potential Potential
-2 Current Density / mA cm
• An increase in cell temperature to 88°C bringing a gain of 20 mV at 150 mA cm-2 • Highlight: Improvement in high current density observed without any additional methanol crossover loss with 0.6 M
• A decrease in cMeOH from 0.6 M at 80°C (0.5 M at 88°C) to 0.4 M resulting in mass transport limitations at a current density of 150 mA cm-2
Cell performance achieved: 0.56 V at 0.150 A cm-2 (88°C) (at present, only 0.04 V away from target)
2014 Hydrogen and Fuel Cells Program Annual Merit Review – Slide 6 Ten-Cell Direct Methanol Fuel Cell Stack
SFC EFOY Fuel Cell System 10-Cell DMFC Stack with JMFC AAC-Anode CCMs
Basic Values Over Net Runtime • Maximum stack voltage reached 70 h of operation • Pump failure after ca. 2,500 h apparently affecting
performance at longer times • Highlight: Decay rate of 19 µV/(h per cell), slightly lower
Voltage / mV / Voltage than in commercial MEAs with much higher Pt loadings
Stack milestone completed AAC – promises to enable DMFCs for higher power Net Runtime / h applications
2014 Hydrogen and Fuel Cells Program Annual Merit Review – Slide 7 MeOH Oxidation: PtRu Nanostructures (SEM,TEM, HADDF-STEM)
PtRuNTs PtRuCuNWs
SEM TEM SEM TEM HRTEM
HAADF-STEM Pt Ru HAADF-STEM Pt Ru Cu Cu
Pt Ru Pt Ru
PtRuCuNWs: Cu-rich core, PtRu-rich shell
2014 Hydrogen and Fuel Cells Program Annual Merit Review – Slide 8 MeOH Oxidation: Innovative PtRu Nanostructure Catalysts
Activity XRD of CuNW, PtRuNTs, PtRuCuNWs
Solution: 1.0 M MeOH in 0.1 M HClO4 PtRu/C: HiSPEC® 12100, Scan rate: 5 mV/s
XPS of CuNW, PtRuNTs, PtRuCuNWs
• XPS Pt 4f and Ru 3p shifts attesting to facile removal of CO from PtRuCuNWs surface • Highlight: Successful scale-up of PtRuCuNWs from 5 mg to 19 mg per batch
2014 Hydrogen and Fuel Cells Program Annual Merit Review – Slide 9 Methanol Oxidation: Alternative Approach
Decoration of Expanded Pt Monolayer with Ru for Improved MeOH Oxidation Activity CO 2 160 Ru /Pt /Au/C 2ML ML Ru2ML/PtML/Au/C PtRu/C (Commercial) - 0.2% ClO4 120
Pt+Ru+Au E/V vs. RHE 0.30.50 V vs.V vs. Ag/AgCl RHE 80 0.72V 0.63V 0.54V 0.45V 0.36V 40 0.27V j / mA/mg 0.5 M MeOH + 0.1 M HClO 0.18V 4 0.09V Room Temperature 0 2400 2000 1600 1200 0 20 40 60 80 100 120 Wavenumber / cm-1 Time / min
Onset Potential Ru Nanoclusters i /i • CO the only observed product of at 0.05 mA (V)* f b 2 methanol oxidation PtML/Au 0.288 1.2 • Ru deposition causing a shift in the Ru /Pt /Au 0.185 3.1 ML ML onset potential of CO oxidation to ca. Ru2ML/PtML/Au 0.133 2.9 0.30 V vs. RHE (25°C) (Pt Ru ) /Au 0.207 1.3 3 1 ML • Different Ru quantities allowing fine- * Ag/AgCl potential scale tuning MeOH oxidation activity
2014 Hydrogen and Fuel Cells Program Annual Merit Review – Slide 10 DMFC Hydrocarbon Membranes
High cell resistance Proton conductivity Multi-block copolymer Low fuel efficiency Methanol permeability Nitrile group Durability Water uptake Tetra methyl (TM) bisphenol A
Importance of Low Water Uptake on Durability*
Polysulfone MB TM-BisA MB 0.5 M MeOH
* Kim et al., J. Electrochem. Soc. 2010, 157, B1616-B1623
2014 Hydrogen and Fuel Cells Program Annual Merit Review – Slide 11 DMFC Membranes: FY14 Multi-block Copolymers
-2 Chemical Structure of FY14 Multi-block Copolymers Anode: 2.7 mg cm Pt50Ru25/C, 1.0 M MeOH, 1.8 mL/min; Cathode: 2.0 mg cm-2 Pt/C; Cell: 75ºC O 0.8 O O S DM (t = 28 m) O 0.7 TM (t = 31 m) HO3S SO3H 0.6 BisA (t = 25 m) C N C N CF3 0.5 X O . O O . 0 5 0 5 0.4 CF3 0.3 )
0.10 2
H C Cell voltage (V) CH CH 3 CH3 3 3 CH3 0.2 = cm
X C C C , , , 0.05 0.1 CH3 CH3 CH3 H3C CH3 H3C CH3
0.0 0.00 ( HFR BP Bis A DM TM 0.0 0.1 0.2 0.3 0.4 0.5 0.6 Current density (A cm-2)
Morphology & Mechanical Properties • Successfully synthesized high molecular
SAXS profile Stress-strain curve weight BisA, DM and TM multi-block 60 qmax copolymers 50 1 • TM-based copolymer shows more ordered 40 domain structure (SAXS), higher 2qmax 30 elongation (stress-strain curve), and lower 0.1 20 BisA
Stress (MPa) DM methanol permeability (back-up slide) Intensity (a.u.) BisA 10 TM DM Random TM • Highlight: Reached DMFC performance 0 -2 0.01 of > 200 mA cm at 0.50 V (75°C) 0.1 1 0 5 10 15 20 25 30 -1 q (nm ) Strain (%) December 2013 milestone achieved
2014 Hydrogen and Fuel Cells Program Annual Merit Review – Slide 12 DMFC Membranes: Progress in Multi-block Copolymer Research
0.14 80 0.12 70
) 60 2 0.10 50
cm 0.08
40 0.06 30 HFR( 0.04 20 0.02 Wateruptake (vol.%) 10 0.00 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 ) -2 140 0.5 M MeOH 120 100 HFR Change During Life Test 80 0.14 60 FY 2012 No 9 40 FY 2014 No 17
MeOH crossover crossover MeOH 0.12
) Nafion 212
20 2 limitingcurrent (mA cm 0 0.10 cm
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
1. Nafion 115 (150 µm thick) 10. 6FPAEB-BPSH (15K-15K) 0.08
2. 6FBPSH0-BPSH (7K-7K) 11. 6F100BPPAEB-BPSH (10K-10K) HFR ( 3. 6FBPSH0-BPSH (11K-11K) 12. 6F75BPPAEB-BPSH (10K-10K) 4. 6FBPSH0-BPSH (15K-15K) 13. 6F50BPPAEB-BPSH (10K-10K) 0.06 5. 6FK-BPSH (7K-7K) 14. 6F25BPPAEB-BPSH (10K-10K) 6. 6FK-BPSH (11K-11K) 15. 6F50BisA50PAEB-BPS (10K-10K) 1.0 M MeOH 7. 6FK-BPSH (15K-15K) 16. 6F50DM50PAEB-BPS (10K-10K) 0.04 8. 6FPAEB-BPSH (7K-7K) 17. 6F50TM50PAEB-BPS (10K-10K) 0 20 40 60 80 100 120 9. 6FPAEB-BPSH (11K-11K) Thickness of all membranes - 60 µm; best performing PEM - Time (h)
• Extensive research performed towards reducing methanol crossover and water uptake • Highlight: Much better performance with 60 µm TM-based copolymer MEA than with Nafion 115 MEA (the industry standard); lower HFR, methanol crossover, and water uptake demonstrated at the same time
2014 Hydrogen and Fuel Cells Program Annual Merit Review – Slide 13 Ethanol Oxidation: Improved Synthesis of Ternary Catalysts
Reactive Spray Deposition for Ternary Catalysts Ethanol Oxidation at 25°C and 60°C -1 and Oxide Supports (0.5 M EtOH + 0.1 M HClO4; 10 mV s ) (with Radenka Maric, University of Connecticut) 0.8 PtRhSnO2/C O2 Pt Sn/C Precursors 0.6 3 Fuels Pt/C
0.4
TEM SEM
0.2 Current / mA Room 25°C 0.0 Temperature 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 E / V vs. RHE PtRhSnO /C 4 2
• Combustion synthesis capable of forming multi-component 3 catalysts in one-step, directly on gas diffusion layer (GDL) 2 • Possible issues: Cleaning remaining organics and preventing particles agglomeration
Current / mA 1 • Highlight: Resulting ternary catalysts show excellent ο 6060 °CC activity and stability at 25°C and 60°C 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 E / V vs. RHE
2014 Hydrogen and Fuel Cells Program Annual Merit Review – Slide 14 Ethanol Oxidation: Alternative Oxide Catalysts & Intermetallic PtML Support
Different Oxide Co-Catalysts Intermetallic vs. Core-Shell (PdAuCo Support)
(for solving SnO 2 instability)
2.0 1.0 PtCeO2/C -2 PtML/Pd4Au1Co5/C Pt3Rh/Ti4O7 (Core-shell) 0.8 1.5 Pt /Pd Au Co /C Pt3Rh/ITO ML 4 1 5 PtIrO /C (Intermetallic) 0.6 x Pt/C 1.0 Pt/C PtML/Pd/C 0.4 0.5 M EtOH + 0.5 Current / mA 0.2 0.1 M HClO4 10 mV/s 0.0 0.0
0.0 0.2 0.4 0.6 0.8 1.0 CurrentDensity / mA*cm E / V vs. RHE 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 E / V vs. Ag/AgCl
CeO2-Promoted PtML
-2 0.4 CeO2-PtML/Pd/C • Highlight: Several oxides, IrOx in particular, identified PtML/Pd/C 0.3 as promising replacement for insufficiently stable SnO2 0.5M EtOH + in ternary catalysts of EtOH oxidation 0.2 0.1M HClO4 • CeO2 considerately enhances activity of PtML/Pd/C in 10mV/s ethanol oxidation (also methanol oxidation, not shown) 0.1
• PtML/PdAuCo shows high ethanol oxidation activity 0.0 CurrentDensity / mA*cm relative to Pt; intermetallic PdAuCo exhibiting better 0.0 0.2 0.4 0.6 0.8 1.0 performance as a Pt support than core-shell PdAuCo E / V vs. RHE ML
2014 Hydrogen and Fuel Cells Program Annual Merit Review – Slide 15 DME Oxidation: MEA and Fuel Delivery System Optimization
-2 ® Anode: 4.0 or 3.0 mgPGM cm , PtRu/C (HiSPEC 12100), 40 sccm DME gas, 26 psig; Cathode: 4.0 mg cm-2 Pt black, 500 sccm air, 20 psig; Membrane: Nafion® 212; Cell: 80ºC
0.9 0.8 0.7 0.6 February 2014 (3.0 mg cm-2) 0.5 PGM 0.4 Voltage (V) Voltage
0.3 December 2012 (4.0 mg cm-2) 0.2 PGM December 2013 0.1 -2 (4.0 mgPGM cm ) 0.0 0.0 0.2 0.4 0.6 Current density (A cm-2)
• MEA and fuel delivery system optimization carried out with commercial PtRu/C HiSPEC 12100 catalyst • Highlight: FY13 to FY14 DDMEFC performance increase from 0.095 A cm-2 to 0.215 A cm-2 at 0.5 V, in spite of lowering the PGM anode loading by 25% in FY14
2014 Hydrogen and Fuel Cells Program Annual Merit Review – Slide 16 DME Oxidation: Development of Ternary PtRuPd/C Catalyst
PtRuPd catalyst: Pt − primary DME adsorption and dehydrogenation XRD Ru − source of surface oxidant for CO removal Pd − C-O and C-H bond scission catalyst
® 2 -2 Electrode: Pt80X20/C (X = Pd, Ru) or HiSPEC 9100 on GCE (0.196 cm ); 60 µgPGM cm ; -1 Solution: DME-saturated (0.74 M), 0.1 M HClO4; Cell: 5 mV s ; 60°C 0.14 PtPd PtRu
0.12
) Pt (111) (200) ECSA
-2 0.10
0.08
0.06
0.04 Current density cm(mA 0.02
COads, CHads 20 nm 20 nm Pt80Ru20/C Pt80Pd20/C 0.00 0.3 0.4 0.5 0.6 0.7 0.8 Potential (V vs. RHE) Crystallite size Lattice parameter Catalyst (nm) (Å) Highlight: In agreement with proposed mechanism, (i) Pd addition results in higher current density with Pt80Pd20/C 1.9 3.93
the same onset potential as observed with Pt; (ii) Ru Pt80Ru20/C 2.7 3.87
leads to lower onset potential of DME oxidation Pt/C (HiSPEC® 9100) 3.7 3.92
2014 Hydrogen and Fuel Cells Program Annual Merit Review – Slide 17 DME Oxidation: Development of Ternary PtRuPd/C Catalyst
1.0
Pt Ru Pd /C XRD 55 35 10
-2 Pt Ru /C (HiSPEC 12100) 0.8 50 50
5 0.6 (111) nm Fuel Cell Test Conditions 0.4
-2 ® Anode: 4.0 mgPGM cm PtRuPd/C, HiSPEC 12100, 40 sccm
Current density/mA cm 0.2 (200) DME gas, 26 psig; Cathode: 2.0 mg cm-2 Pt/C HiSPEC® 9100, ® 100 sccm air, 20 psig; Membrane: Nafion 212; Cell: 80ºC 0.0 0.0 0.2 0.4 0.6 0.8 1.0 Potential/V vs. RHE
Pt Ru Pd /C Pt55Ru35Pd10/C 55 35 10 0.9 0.8 -1 Pt Ru (HiSPEC 12100) Pt50Ru50/C (HiSPEC 12100) 50 A g at 0.50 V 50 50 0.8 Project Target 0.7 0.6 0.6 0.5 0.4 0.4 Voltage (V) Voltage Voltage (V) Voltage 0.3 0.2 0.2 0.1 0.0 0.0 0.0 0.2 0.4 0.6 0.8 0 50 100 150 200 250 -1 Current density (A cm-2) Mass specific current (A g )
-2 -1 Highlight: 220 mA cm or 55 A g at 0.50 V reached with ternary Pt55Ru35Pd10/C and cathode -2 loading of 2.0 mgPt cm (100 sccm air flow)* DME Project Target and March 2014 milestone of 50 A g-1 achieved and exceeded
-1 -2 * 67 A g reached with Pt50Ru50/C anode, 4.0 mgPt cm cathode and 500 sccm air flow (backup slide)
2014 Hydrogen and Fuel Cells Program Annual Merit Review – Slide 18 DME Oxidation: Progress at LANL FY11 - FY14
FY How Progress Has Been Made
2011 Pt-to-Ru ratios screened and Pt50Ru50 selected
2012 DME-to-water stoichiometry ratio and membrane optimized
2013 New ternary Pt45Ru45Pd10/C catalyst developed replacing the Pt50Ru50 black anode catalyst
2014 Ternary catalyst further optimized to Pt55Ru35Pd10/C; MEA and fuel cell operating conditions improved
Performance at 0.50 V
Highlight: DDMEFC performance improved by a factor of at least 2.5× over the project duration with concurrent significant reduction in precious metal loading
2014 Hydrogen and Fuel Cells Program Annual Merit Review – Slide 19 DME Oxidation: DDMEFC and DMFC Performance Comparison
-2 ® Anode: 4.0 mgmetal cm PtRuPd/C, HiSPEC 12100, 40 sccm DME gas, 26 psig, 1.8 mL/min 0.5 M or 1.0 M MeOH, 0 psig Cathode: 2.0 mg cm-2 Pt/C HiSPEC® 9100, 100 sccm air, 20 psig; Membrane: Nafion® 212 (DME), Nafion® 115 (MeOH); Cell: 80ºC
0.9 Pt55Ru35Pd10/C - DME 0.8 Pt50Ru50/C (HiSPEC 12100) - 0.5 M MeOH Pt50Ru50/C (HiSPEC 12100) - 1.0 M MeOH 0.7
0.6
0.5
Voltage (V) Voltage 0.4
0.3
0.2
0.1 0.0 0.2 0.4 0.6 0.8 Current density (A cm-2)
Performance of the latest-generation DDMEFC slightly exceeding that of the state-of-the-art DMFC (Both systems operating under their respective optimum conditions)
2014 Hydrogen and Fuel Cells Program Annual Merit Review – Slide 20 Collaborations
• Seven organizations with complementary skills and capabilities in catalyst development, electrode-structure design, materials characterization, MEA fabrication, and portable fuel cell development and commercialization: Los Alamos National Laboratory (LANL) – direct DOE EERE contract Brookhaven National Laboratory (BNL) – direct DOE EERE contract University of Delaware – subcontract to LANL Virginia Tech – subcontract to LANL Johnson Matthey Fuel Cells – subcontract to BNL SFC Energy – subcontract to BNL Oak Ridge National Laboratory – no cost partner • Collaborations outside Fuel Cell Technologies Program: Oorja Fuel Cells, Fremont, California, USA – reduction in DMFC cost for applications in excess of 1.0 kW in power; two LANL DMFC patents licensed by Oorja in April 2014 University of Warsaw, Warsaw, Poland – development of components for direct dimethyl ether fuel cell (common program development phase) Danish Technical University (DTU) – direct dimethyl fuel cell electrocatalysis (joint research proposal to be submitted in summer 2014)
2014 Hydrogen and Fuel Cells Program Annual Merit Review – Slide 21 Responses to Previous Year Reviewers’ Comments
“Very good progress was made in anode catalyst research. On the membrane research, it would be very useful to check how the TM membrane/electrode interface changes in durability test, to validate the hypothesis that matching water uptake to Nafion® can improve interface durability. Also, it is perhaps more useful to have the membrane swelling ratio data.” The data showed in our 2013 presentation was preliminary. Since then we have completed a thorough interfacial durability study of TM membrane/electrode, the results of which have been presented this year. While we plan to measure the swelling ratio of the multi-block copolymers, the relevance of the swelling ratio to interfacial durability may be questionable. “Lack of long-term testing; 1000 hours is only a 2 month test; this is the fourth year of the program; this should have been done for all of their promising catalysts.” Most durability testing in the project has been performed using potential/voltage cycling (accelerated stress testing) to avoid tying either electrochemical or fuel cell test equipment to one cell for prolonged times. However, the most promising DMFC anode catalyst, Johnson Matthey’s Fuel Cell’s advanced anode catalyst (ACC), underwent this year testing in a 10-cell SFC Energy stack for ca. 3,500 hours. In spite of a much lower catalyst loading (approximately half of that used in SFC’s commercial products), the catalyst showed lower rate of performance degradation than methanol oxidation catalysts used in commercial systems. “Given team's strength in direct fuel cell systems, the team should drill down to the fundamentals of DME fuel system and determine the viability of the success of DME technology as a competitive technology to DMFC.” As highlighted in this year’s presentation, advancements in DME research (both electrocatalysis and fuel delivery system) have been central to the project effort at Los Alamos. Test data shows that DME fuel cells can match, and in some cases outperform, the state-of-the-art DMFCs.
2014 Hydrogen and Fuel Cells Program Annual Merit Review – Slide 22 Remaining Needs, Barriers, and Challenges
Direct methanol and dimethyl ether fuel cells:
• Further improvements to mass activity of both anode and cathode catalysts by modifications to existing catalyst formulations or development of new catalysts
• Reduction in cost to allow application to high-power systems (for example, by lowering catalyst cost and improving performance durability)
• Increase in fuel conversion efficiency via progress in anode catalysis (new formulations), reduction in fuel and anode-component crossover and enhancements in cathode tolerance to fuel/anode-component crossover
• Development of alternative membranes with improved stability and reduced permeability of fuels and anode catalyst component(s)
Ethanol as alternative fuel for direct fuel cells:
• Development of active and chemically stable catalyst with high selectivity for 12-electron
oxidation of ethanol to CO2 (in fuel cell type electrodes) • Forsaking anode catalyst formulations that rely on intrinsically unstable components (including some core-shell formulations)
• Leveraging of DMFC/DDMEFC experience in the development of membranes with reduced crossover and in addressing effects of crossover on cathode performance
2014 Hydrogen and Fuel Cells Program Annual Merit Review – Slide 23 Future Work: Remainder of FY14 and FY15 (Optional)
Direct methanol fuel cells: • Complete current catalyst development efforts to meet last remaining project milestone (0.15 A cm-2 at 0.60 V) • Develop methanol oxidation catalysts free of intrinsically unstable components; possible formulations include two-dimensional platelets containing low-coordination atoms of precious metals and Au-core nanoparticles as supports • Develop inks, GDL treatments, optimize and assure manufacturability by a scalable production process for advanced anode catalyst (AAC), targeting 50% Pt reduction in two years without performance/durability penalty (30% Pt reduction in FY15) and 500 W system
Direct DME fuel cells: • Complete development and optimization of the ternary PtRuPd catalyst for DME oxidation • Implement multiblock copolymer membranes in DDMEFC-type MEAs • Complete detailed study of DME crossover and its impact on DDMEFC performance
Ethanol oxidation catalysis: • Develop new-generation catalysts of ethanol oxidation, for example, catalysts on composites of stable oxides and lattice-expanded nanoparticles of precious metals; use in-fuel-cell stability and 12-electron selectivity and primary performance and selection criteria • Perform assessment of DEFC viability at the present state of ethanol oxidation catalysis
2014 Hydrogen and Fuel Cells Program Annual Merit Review – Slide 24 Summary
• JMFC’s advanced anode catalyst (AAC) reached 0.150 A cm-2 at -2 -2 0.56 V with low anode loading of 1.0 mgPt cm (total 2.5 mgPt cm ). • AAC was used in CCMs prepared JMFC for a 10-cell SFC Energy stack; in spite of much lower loading, ACC showed better stability over 2500 hours of stack operation than commercial catalysts.
• Progress in methanol catalysis is viewed by SFC Energy as Basic Values Over Net Runtime enabling for higher power DMFC applications, power generators in particular (presently off-limits due to the prohibitive catalyst cost).
• High current density of 0.200 A cm-2 at 0.50 (75°C) was achieved with TM-based multi-block copolymer; a 60-µm TM-based MEA showed lower resistance, methanol crossover and water uptake than a Nafion 115-based MEA – a DMFC industry standard.
• Significant progress in DME electrocatalysis with the ternary 0.9 PtRuPd/C was demonstrated resulting in a DDMEFC current Pt55Ru35Pd10/C - DME -2 -1 0.8 Pt50Ru50/C (HiSPEC 12100) - 0.5 M MeOH density of 220 A cm (55 A g mass-specific activity of the anode Pt50Ru50/C (HiSPEC 12100) - 1.0 M MeOH 0.7 catalyst) – a 2.5-fold improvement in activity since project inception. 0.6 • LANL DDMEFC was demonstrated to match state-of-the-art DMFC 0.5 across the entire range of current densities. (V) Voltage 0.4 0.3 • Recent advancements in ethanol oxidation electrocatalysis at BNL 0.2 0.1 (PtML/Au/C catalyst) led to ca. 200 mV reduction in overpotential of 0.0 0.2 0.4 0.6 0.8 EtOH oxidation relative to Pt/C; LANL fuel cell testing is upcoming. Current density (A cm-2)
2014 Hydrogen and Fuel Cells Program Annual Merit Review – Slide 25 Co-Authors
– ethanol and methanol anode catalyst research Radoslav Adzic (PI), Meng Li, Miomir Vukmirovic, Kotaro Sasaki – anode catalyst and membrane research; characterization Piotr Zelenay (Project Lead), Hoon Chung, Joseph Dumont, Qing Li, Yu Seung Kim, Ulises Martinez, Yun Xu, Gang Wu – nanostructure catalyst structures Yushan Yan (PI), Jie Zheng – hydrocarbon membrane research James McGrath (PI), Jarrett Rowlett, Andy Shaver – methanol anode catalyst research; MEA integration Alex Martinez Bonastre (PI), Willie Hall, Graham Hards, Emily Price, Jonathan Sharman, Geoff Spikes – MEA integration and testing; final deliverable Christian Böhm (PI) – microscopic characterization (no-cost partner) Karren More (PI), David Cullen
2014 Hydrogen and Fuel Cells Program Annual Merit Review – Slide 26 Title
Technical Backup Slides
2014 Hydrogen and Fuel Cells Program Annual Merit Review – Slide 27 MeOH Oxidation: AAC Anode; Effect of Annealing Temperature and Loading
2 -1 Catalyst CO metal area / m gcat AAC 20 High metal content AAC @ T1 20 High metal content AAC @ T2 21 High metal content AAC @ T3 27 High metal content AAC @ T4 30
Anode: AAC@T2, 2.0 mg cm-2, 0.5 - 0.6 M MeOH; Cathode: -2 Pt Anode: AAC, 1.0 mgPt cm , 0.5 - 0.6 M MeOH; Cathode: Pt/C, 1.5 -2 Pt/C, 1.5 mgPt cm air (fuel cell), H2 (anode polarization); mg cm-2 air; Nafion 115; 80°C Pt Membrane: Cell: Membrane: Nafion 115; Cell: 80°C
T1 > T2 > T3 > T4
0.6 V; 150 mA cm-2
Voltage / V / Voltage
-2 -2 i (mA cm ) i (mA cm )
• Increase in annealing temperature helps performance of high metal-content (low carbon- content) catalysts (via increase in surface area), but not beyond that of low metal-content AAC
2 • Only small performance gain achieved with 2.0 mgPt/cm (noticeably lower Pt mass activity)
2014 Hydrogen and Fuel Cells Program Annual Merit Review – Slide 28 DMFC Membranes: FY14 Multi-block Copolymers
Synthetic Procedure of FY14 Multi-block Copolymers Methanol Crossover Limiting Current
KO3S
O [ -2 KO O [ S O O n K Anode: 2.7 mg cm Pt50Ru25/C, 1.0 M MeOH, 1.8 mL/min; O -2 BPS100 SO3K Cathode: 2.0 mg cm Pt/C; Cell: 75ºC
CN CN CN
CF3 0.35
[ F O O [ O X O F )
[ [ - -2 y 1 y CF3 0.30 6F50X50PAEB o 135 C 2 days 0.25
KO3S CN CN
O CF3 ( [ [ [ 0.20 O O O O X O [ S O n [ [ - y 1 y ( F m O C 3 SO3K - 0.15 6F50X50PAEB BPS100 CH H3C 3 DM (t = 28 m) CH CH3 CH3 3 0.10 X = TM (t = 31 m) CH3 CH3 CH3 H H BisA (t = 25 m) H3C CH3 3C C 3 0.05
s crossoeverMeOH current density (A/cm (Bi A) (DM) (TM) 0.00 Structural Characterization with 1H NMR 0.2 0.3 0.4 0.5 0.6 0.7 0.8 Cell volt (V)
Note: Methanol crossover data above are for novel MEAs highlighted earlier (Slide 12).
2014 Hydrogen and Fuel Cells Program Annual Merit Review – Slide 29 DME Oxidation: MEA and Fuel Delivery System Optimization
-2 ® Anode: 4.0 or 3.0 mgPGM cm , PtRu/C (HiSPEC 12100), 40 sccm DME gas, 26 psig; Cathode: 4.0 mg cm-2 Pt black, 500 sccm air, 20 psig; Membrane: Nafion® 212; Cell: 80ºC
0.9 50 A g-1 at 0.50 V 0.8 (Project Target) 0.7 0.6 67 A g-1 at 0.50 V 0.5 February 2014 0.4 -2
Voltage (V) Voltage (3.0 mgmetal cm ) 0.3 0.2 December 2012 (4.0 mg cm-2) December 2013 metal -2 0.1 (4.0 mgmetal cm ) 0.0 0 50 100 150 200 250 Mass specific current (A g-1)
• MEA and fuel delivery system optimization carried out with commercial PtRu/C HiSPEC 12100 catalyst • Highlight: Mass-specific activity of 67 A g-1 reached with PtRu/C – the highest ever recorded, but -2 obtained with a relatively high cathode loading of 4.0 mgPt cm and very high air flow (500 sccm)
2014 Hydrogen and Fuel Cells Program Annual Merit Review – Slide 30