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FRM 5101460 AFCC Research Needs Analysis for Generation 4 Vehicles
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FRM 5101460 2 Future Generations Generation 1 Technology Demonstration F-Cell Generation 2 Customer Acceptance B-Class F-Cell Generation 3 Cost Reduction I Generation 4 Market Introduction Cost Reduction II Passenger Cars Lead application Generation 1 Technology Demonstration Generation 2 Customer Acceptance Bus Generation 1 Technology Demonstration Generation 2 Customer Acceptance Sprinter Generation 5 High Volume Series Production 2004 2010 2013 201x 202y Fuel Cell Roadmap - The Path to Commercialization Fuel cell passenger cars will drive the volume
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FRM 5101460 3 Status of Fuel Cell Technology Performance Safety Comfort Freeze start Range Reliability Longevity Package/weight Cost Generation 3 Cars will demonstrate competitive capabilities. Cost remains the challenge!
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FRM 5101460 4 5 Basic Strategies For Cost Reduction Detailed examination of all 5 areas will indicate the best paths for further improvement. Investment of development dollars
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FRM 5101460 5 Mining For Cost Reduction Given multiple options a good miner: Drills new test holes. Explores a few high risk/high gain paths. Exploits the known paths fully in order of their value. Saves some lower value ore bodies for later exploration. Knows when a ore body is exhausted.
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FRM 5101460 6 Distillation Stack CostDurabilityFuel Economy Strategic Filter Critical Research Needs
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FRM 5101460 7 Strategic Filter 1.Criticality The criticality is the sum of the magnitudes of all the effects (good or bad) of using a technology path. 2.Understanding A measure of how much we know about a technology option Advantages, failure modes and trade-offs 3.Remaining Opportunity Improvement Effort How much improvement remains to be made along each technology path. If a path is fully mature we reach the “Technology Limit” and further improvement will require a “breakthrough” or the exploitation of a different path. Technology Limit Opportunity Status
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FRM 5101460 8 Map of the Technology Mine (Cost) Technology At Limit Exploit in present design: diminishing returns High Priority Research Focus of academic and corporate research Research Lower urgency research Development Engineering Focus of in house and supplier engineering
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FRM 5101460 9 The Biggest Driver for Materials Technology At Limit Exploit in present design: diminishing returns High Priority Research Focus of academic and corporate research Research Lower urgency research Development Engineering Focus of in house and supplier engineering
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FRM 5101460 10 Some Statistics 1.We should focus on the 23% that are most critical. 2.Overall understanding of the opportunities is good. 3.There are many good opportunities for cost reduction
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FRM 5101460 11 The Most Critical Research These areas of research and development need to be the focus. New durable high activity catalysts. Enable low cost system Enable high current density via plate and GDL Lower cost cell materials 1 2 3 4 1 1 1 1 2 2 2 2 3 3 3 2 4 4
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FRM 5101460 12 The Mature Technologies These technologies have reached their maximum capability. Gen 4 stack will utilize them at their maximum. It’s time to look for alternative paths or breakthroughs.
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FRM 5101460 Examples and Targets
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FRM 5101460 14 Catalyst Carbon Supports - High surface area carbon supported Platinum catalysts have been the main technology in automotive PEM for the generation 1,2 and likely 3 stacks however they have essentially reached the limits of performance and durability and new path need to be explored for generation 4. Activity vs Durability - For Pt based structures mass activity can be enhanced by increasing the surface area or by altering the electronic structure of the surface. Both options need to be pursued but the impact on durability is critical. Processing - During the development of new catalyst systems we need to simultaneously develop the processes to synthesize them at low cost and possibly to deposit them directly onto MEA with as few intermediate steps as possible to ensure high material yields.
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FRM 5101460 15 Cathode Catalyst Pathways Stabilized Platinum Alloys Catalyst- Support Interaction (Non-Carbon) Pseudo Bulk Catalyst Non Precious Metal Catalyst Proprietary Process Support Structures Thin film Pt-alloy Structures Various Materials High Surface Area Metal oxides Core Shell Catalysts Work Streams Create stable alloys that retain high performance Improve activity w/ more robust support materials Replace platinum with w/ cheap catalytic materials High activity & stability
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FRM 5101460 16 Mass Activity/ Specific Activity C=Carbon; HSC=High Surface Area Carbon 4x Mass Activity Target
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FRM 5101460 17 Membrane Driver PFSA membranes are quite mature and it is becoming apparent that further improvements will be limited. They are however quite capable and are expected to be viable in future generations when the cost of producing them is reduced significantly. Cross-over - In order to enable cost reduction in the fuel cell support systems a large reduction in the Nitrogen cross over is needed. Unless a change in the basic polymer is used to achieve this thinner membranes may not be practical. Hydration - A great deal of effort has been put into reducing the resistance of membranes at low RH however this has increased the basic cost of the materials. Fundamental studies have shown that zero RH conduction cannot occur for sulphonic acid based membranes.
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FRM 5101460 18 Additive Technology Low cost PFSA membranes Hydrocarbon membranes Block Co-polymer Low cost SSC PFSA Free Radical Scavengers Water Retention Additives Work Streams Improve membranes by adding special function materials. Lower membrane cost, improve performance & durability. Cost and better gas cross over. Homo polymer Reinforcement Low cost LSC PFSA Membrane Pathways
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FRM 5101460 19 Dry Conduction Progress
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FRM 5101460 20 Dry Conduction Progress II Log Scale Improved materials all have the same sensitivity to RH. Overall resistance at all RHs improved Without a change in conduction physics target at <30% RH unlikely to be met
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FRM 5101460 21 Proton dissociation –Needs Water Vassiliki-Alexandra Glezakou, et.al. Phys. Chem. Chem. Phys., 2007, 9, 5752–5760 RSO 3 H : (H 2 O) n RSO 3 - + H + (H 2 O) n Based on these models for the equilibrium: RSO 3 H : (H 2 O) n RSO 3 - + H + (H 2 O) n When n>3, the ion pair structure, RSO 3 - + H + (H 2 O) n is more stable than the neutral complex (H 2 O) n. Ionization could happen. High proton transport rate in PFSA membranes requires a high degree ionization At RH <30%, the number of water molecules in a typical PFSA n 3. Insufficient water in the membrane can cause a low proton conductivity and poor durability n=2 n=3 - +
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FRM 5101460 22 N2 Cross Over Effect on Parasitic Load The amount of gas that needs to be pumped back into the stack inlet is proportional to the nitrogen cross over rate. The power required to pump this nitrogen is waste and requires extra cells to produce it. The recycle circuit is typically purged to get rid of the accumulated nitrogen which inevitably wastes hydrogen. Incremental improvements in nitrogen crossover directly benefit the cost and fuel economy of Fuel Cell Vehicles.
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FRM 5101460 23 Cost-Performance Gaps
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FRM 5101460 24 Bipolar Plates Driver Plate technology is quite mature due to significant investment by researchers and a competitive environment with the suppliers. Plate assemblies can be made with good quality and strength at thicknesses well below 2mm and it is now the flow field and not plate material that limits further reductions. Cost - While several suppliers are predicting cost which approach the targets, a significant gap remains with respect to joining/sealing methods, as well as corrosion protection coating technology and production cycle times. Water Management - At high current densities much higher gas and liquid water fluxes must move through the channels. Water remains a big driver for flow resistance and poor flow distribution.
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FRM 5101460 25 Carbon or Metal: No Clear Winner Coated Metal Carbon Composite Inherently corrosion resistant. Conductive surface. 200 um web thickness. Better FF, seal, and backside geometry possible. Inherent Advantages Needed Improvements Strength/toughness Process cycle time Raw material costs Low cost joining method High Strength/Toughness 100 um web thickness Inexpensive forming process Inexpensive substrate Coating Cost/Process Welding/joining cost Surface contact resistance plate to plate Available formed shapes.
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FRM 5101460 26 Pressure Drop Vs Water For a smooth wall circular pipe Gen 4 flow field advancements reduce pressure drop of advanced cells by ~30 %
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FRM 5101460 27 Power Density Progress Mk5 Mk7 Mk8 Mk901 Generation 1Generation 2 Current density Generation 3Generation 4 Current density and cell pitch
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FRM 5101460 28 Conclusions There are many open paths to make further progress on Fuel Cell System costs. There has been a great deal of progress in many key areas: oOur understanding of the options is good. oThere are quite a few mature technologies that can be exploited in the generation 4 cars. And thus: oResources will be focussed onto paths with the most remaining opportunity and highest impact on cost. This focussed research and engineering effort will enable us to meet commercial fuel cell targets
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