Fuel Cells Durability & Performance


June 20, 2008
400 Pages - SKU: CHDQ1793304
License type:
Table of Contents Related Reports
CHAPTER 1
MEA Development for Automotive
Applications
Kev Adjemian, PhD, Manager, Fuel Cell Laboratory,
and Akihiro Iiyama, PhD, Expert Leader, Nissan
Motor Co., Ltd.
Since the inception of the fuel cell program at Nissan Motor Company, great developmental strides have been made in both component and system optimization. This work has resulted in Nissan Motor Company providing the first fuel cell vehicle for commercial taxi service in Japan. Nevertheless, further improvements to the durability and performance of the MEA are required for mass-commercialization. This is being carried out by first understanding the underlying mechanisms followed by formulating effective counter-measures and new materials. Using this approach, major advancements towards fuel cell commercialization are being realized.
CHAPTER 2
On-Road Experiences with FC
Degradation from FCV Learning
Demonstration
Jennifer Kurtz, Senior Engineer, National Renewable
Energy Laboratory
After the first two years of DOE’s fuel cell vehicle Learning Demonstration project, NREL has amassed a significant amount of on-road fuel cell vehicle performance information. This data has been analyzed to determine fuel cell voltage degradation, and whether there are any detectable dominant factors affecting the degradation rates. NREL will present the latest public results on this topic from their analysis.
CHAPTER 3
Fast Conditioning - Impacts on System
Performance & Life Cycle Cost
Kevin Beverage, Lead Process Engineer,
Electrochemical Technology Group, Nuvera Fuel
Cells, Inc.
Conditioning of PEM fuel cells is a necessary, yet not well understood process that is required before a fresh PEM can reach 100% of its expected performance. When manufacturing commercial stacks, the time requirement becomes a critical consideration for the overall cost of the product since traditional conditioning procedures demand anywhere from 8-24 hours of operation, adding a significant premium due to overhead. An investigation into the current hypotheses regarding conditioning mechanisms is presented as well as results showing 1 hour conditioning of subscale stacks and 1.5 hour conditioning of full scale commercial stacks. Ongoing work toward reducing the necessary conditioning time to a target of 10 minutes will be discussed as well as the potential durability impacts of certain procedures used to accelerate conditioning.
CHAPTER 4
Low-Cost, Durable Kynar® Based Fuel
Cell Membranes
James T. Goldbach, PhD, Research Scientist,
Corporate and External Research Dept, Arkema Inc.
Arkema has developed a new approach to PEM design whereby the mechanical property requirements are decoupled from the other desired properties. This decoupling is accomplished by blending two very dissimilar polymers, a fluoropolymer such as Kynar® poly(vinylidene fluoride) with any one of a range of nonfluorinated polyelectrolytes. Using this blending process along with inexpensive starting materials, many different membrane compositions can be produced at significantly reduced cost over traditional methodologies. The newest membrane generation utilizing Arkema’s polymer blending approach has shown a dramatic increase in durability. Continued testing of this membrane in standard fuel cell durability tests shows excellent performance compared to industry material benchmarks. The latest results of these tests will be reviewed along with future testing plans.
CHAPTER 5
Strategies and Technologies to Improve
the Durability of Membranes and MEAs
for PEM Fuel Cells
Gonzalo Escobedo, PhD, Senior Engineer, DuPont
Fuel Cells, E.I. du Pont de Nemours and Company,
Inc.
DuPont has been involved in the fuel cell industry from its infancy, starting with PEM membrane supply used to make the first fuel cells for NASA space program in the 1960’s. Nafion® PFSA was the first membrane used and is still the leading membrane in PEM fuel cell systems today. DuPont continues to develop new and improved membranes that enable stack and system developers to design more effective and efficient fuel cell systems. This presentation will present an overview of the industry’s past and what DuPont has done to meet the requirements for FC systems today and the durability and performance challenges for PEMs in the future.
CHAPTER 6
Experimental Validation of a Method of
Oxygen Removal During a Shutdown of
an Automotive PEM Fuel Cell
George S. Saloka, Research Engineer, Fuel Cell
Research, Ford Motor Company
Lifetime of a PEM fuel cell can be significantly shortened by an exposure to air from an idle to a start-up transition. Hydrogen fuel introduced into anode compartment, that contains air during a vehicle start-up simultaneously mixes with oxygen within the same catalyst layer (anode) that can lead to local potential gradients within the same electrode that can attack the catalyst, its catalyst support, and the membrane. Experiments utilizing the oxygen depleted gas from the cathode of the fuel cell to purge the anode during shut down were undertaken. Anode gas cycling experiments have demonstrated that cycling between air and hydrogen severely degrades cell performance due to reduction of the catalyst active area. However, nitrogen and 5% oxygen gas cycling have a minimal effect on cell performance. Hydrogen crossover tests indicate that the membrane remains unaffected as a result of the anode gas cycling. Polarization curves indicate that using an oxygen depleted gas (5% oxygen) to purge a fuel cell during shut-down is nearly as beneficial as using neat nitrogen to purge a fuel cell during fuel cell shut-down.
CHAPTER 7
The Titanium Separator with Stable
Durability and Low Electrical Resistance
Toshiki Sato, Senior Researcher, Materials Research
Laboratory, Kobe Steel, Ltd.
The high corrosion resistant separator with low electrical resistance has been developed. It consisted of titanium substrate coated with gold alloy thin film by magnetron sputtering. The low and stable electrical resistance in corrosive atmosphere such as inside fuel cell has been achieved by the controlled heat treatment after the coating on passive TiO2 layer.
CHAPTER 8
Non-Fluorinated Proton-Conducting
Materials for Fuel Cell Membrane and
Electromagnetic Method of Conductivity
Testing
Elena Shembel, DSc, President and CEO, Enerize
Corporation
The goal of this work is developing non-fluorinated low cost fuel cell polymer membrane with high conductivity, minimal dependence on humidity, and stability under high temperatures. The polymers for the membrane have been produced by a joint condensation method of aliphatic polyamides, aromatic sulfoacids and aldehydes in organic solvent media with adding a catalytic quantity of sulfuric acid. They are spaced cross-linked polymers comprising graft aromatic sulfo-acid radicals. Synthesized materials are thermally stable up to 230°C and have high conductivity. The membrane conductivity was evaluated by nondestructive, non-contact electromagnetic method, which could also be used for automatic testing of polymer membranes during production.
CHAPTER 9
FlowCath™ Technology - A Route to
Precious Metal-Free Cathodes for PEMType
Fuel Cells
Andrew Creeth, PhD, Chief Technology Officer,
ACAL Energy Ltd.
ACAL Energy Ltd is developing FlowCath™ technology for PEM fuel cell cathodes for standard proton ion exchange membranes which removes the need for precious metal catalysts. An indirect redox system is used with catalysts that offer significantly reduced cost and substantial performance improvement potential. It is a platform technology that can be used for multiple fuels and applications that span automotive, stationary and portable. A description of the technology with performance to date and prospects will be given.
CHAPTER 10
PEM Fuel Cell Durability Testing
John R. Davey, PhD, and Rod L. Borup, PhD,
Institute for Hydrogen and Fuel Cell Research, Los
Alamos National Laboratory
The durability of polymer electrolyte membrane (PEM) fuel cells is a major barrier to the commercialization of these systems for stationary and transportation power applications. Durability is difficult to quantify and improve, in part because of the quantity and duration (i.e., up to several thousand hours or more) of testing required. Ideally, a component developer would like to evaluate new materials and cell designs with a minimum of longterm PEMFC testing. This has led to the development of accelerated testing methods. These testing methods rely upon understanding the degradation mechanism for a specific fuel cell component. Many of the testing methods used for accelerated testing of individual components will be presented, including efforts to understand the degradation mechanism.
CHAPTER 11
Ballard’s Approach to Concept Level
Testing: The Mk1020 ACS Fuel Cell
Stack
George Skinner, Senior Engineer, Test & Reliability
Group, Ballard Power Systems, Inc.
The Mk1020 ACS Fuel Cell Stack is a scalable, self-humidifying, air-cooled design intended for reliable & robust operation over a wide range of operating conditions. This presentation describes how Ballard’s Test & Reliability group contributed to the development of the design, from exploring the operating envelope of the concept prototypes to developing a set of standardized characterization tests & defeatured load cycles used to verify the design for customer field tests.
CHAPTER 12
Complex Approach to Design and
Evaluation of Fuel Cell Systems and
Components
Vesna Stanic, PhD, Chief Scientist, EnerFuel
EnerFuel has been developing a PEM fuel cell powered remote surveillance system (RSS) that will be commercially available in 2007. To be competitive with the currently available surveillance technologies, the system has low cost, portability and one year run time before it needs hydrogen storage to be recharged. Furthermore, the system provides reliable operation at various environmental conditions. Addressing specific durability and performance issues related to low power portable fuel cells through the use of a complex approach to design and evaluation of fuel cell system and components, EnerFuel overcame fuel cell commercialization barriers.
CHAPTER 13
Investigation of Durability Issues in
Polymer Electrolyte Membrane (PEM)
Electrolytic Cells
Sarb Giddey, PhD, Senior Research Scientist, Fuel
Cell and Ionic Technologies Group, CSIRO Energy
Technology
Distributed hydrogen generation would remove the need for the costly up-front transportation / distribution infrastructure requirements and can assist with the early trials of the fuel cell technology and introduction of the hydrogen economy. Polymer electrolyte membrane based electrolytic cells offer high efficiencies, can operate at higher current densities leading to compact design, and produce high purity hydrogen at high pressures with electrochemical compression. However, the efficiency degrades with time and in some cases a catastrophic failure occurs that leads to a loss in the current efficiency. In this paper, the sources of performance degradation and efficiency loss with time have been discussed.
CHAPTER 14
Transient Multi-Scale Modeling Of
Coupled Aging Mechanisms in PEFC - A
Theoretical Tool for Experimental
Interpretation and Advanced MEA
Design
Alejandro A. Franco, PhD, Physicist, Laboratory of
PEFC Components (LCPEM),
DRT/LITEN/Department of Hydrogen Technologies
(DTH), CEA-Grenoble
In this talk we discuss a new dynamic mechanistic model of coupled electrochemical ageing processes in a PEFC MEA, on the basis of a recent modular multi-scale non-equilibrium thermodynamics approach developed by us. It couples cathodic Pt oxidation/dissolution/ripening, Ptz+ diffusion/migration/recrystallization in ionomer and cathode carbon corrosion, with a novel description of the nano-scale ionomer/Pt interface dynamics and MEA micro-scale charge transfers. The model analyses MEA response sensitivity to operating conditions, initial Pt/C/Nafion® loadings and temporal evolution of the electrocatalytic activity. Impact of initial electrodes morphology on durability is studied and the time influence on EIS pattern is simulated. Predictions are validated in dedicated benches and by ex-situ experiments and characterization techniques.
CHAPTER 15
Development of Advanced MEAs for PEM
Water Electrolysis
Everett B. Anderson, PhD, Director of
Electrochemical Technology, Distributed Energy
Systems
On-site hydrogen generation using proton exchange membrane (PEM) technology is an attractive option today for many industrial applications and being looked at as a promising nearterm solution for the role-out of the hydrogen economy. In order to compete in these emerging energy applications the cost of generation must be reduced. The membrane-electrode assembly (MEA) is at the center of these cost reduction efforts. Recent efforts to identify new membrane materials and catalysts that can reduce the cost of the MEA will be presented.
CHAPTER 16
An In-Situ, Real-time, Gas Humidity
Sensor for Fuel Cells
Nathan Hurvitz, Director of Engineering &
Operations, VIASPACE
Accurate measurement of fuel cell operating conditions is critical to the proper design and performance characterization of PEMFCs. In the past, inlet gas humidity measurements have been a particular problem because of the lack of a suitable sensor. Now, tunable diode laser spectroscopy (TDLAS) has been used to solve this problem. The VIASPACE HS-1000 VIASENSOR incorporates a patent pending miniature laser sensor technology to provide rapid, accurate, and reliable measurements of fuel cell gas humidity. This paper describes the technology and its application to the precise measurement of fuel cell gases.
 
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