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B 1.3 S/T methodology and associated work plan

B 1.3.1 Describe the overall strategy of the work plan

The increase of the durability of polymer electrolyte membrane fuel cells is the main objectives of this project. The overall work is organised in three phases:
  • Specification/Definition Phase
  • Analysis Phase
  • Improvement Phase
The research and development work will be supported by the co-ordination and management activity and the results will be disseminated to the European public.
In the first phase – specification and definition phase – materials, components as well as testing and operating conditions will be specified. The crucial aspect of the phase is to choose operating conditions which are relevant for automotive applications and to define materials and samples which are industrial state of the art and can be completely analyzed without restrictions. This specification and definition phase is also used as start-up phase for the experimental work and is necessary to supply the experimental working groups with the samples for the second project phase. In addition, the first project phase is also used as start-up phase of the modelling work in the work package 4 and allows the researchers to adapt the models to the requirements of the gas diffusion layer description.
The second phase of the project – the analysis phase – includes the main work of the project. In this phase the scientific foundation for the third project phase will be generated. In the second phase the individual degradation processes of the components and their interactions will be investigated. This work is organised in three work packages related to the main fuel cell components; the membrane electrode assembly, the gas diffusion layer and the bipolar plates, because the analytic methodology depends on the components which will be investigated. In addition, the industrial partners will be able to utilise the results and generated knowledge to improve the durability of fuel cells. Therefore, for each work package in the analysis phase an industrial partner participates in the work package which is related to a main fuel cell component. In the analysis phase an intense communication and interaction between the work packages is planned. One element combining the work packages are the planned long-term tests and therefore the participants of all three work packages in the analysis phase will agree on the definition of the joint fuel cell tests. As discussed in detail above, the research work will concentrate on the influence of the water balance in the fuel cell on the degradation processes. The water balance in the fuel cell depends strongly on the transport properties of the gas diffusion layers and especially their micro porous layers; therefore, an analysis in the form of modelling of the transport properties will be performed in order to understand local water balance and consequently to advance the understanding of the degradation mechanisms of all components which are related to water and humidity. This includes also the complexity of the interactions of the different degradation processes.

The third phase is the improvement phase. In this phase the knowledge of the degradation processes and mechanisms will be use to generate technological progress. These technological advances are based on an understanding of the degradation of fuel cells and based on the knowledge of the individual degradation mechanisms and their interactions. Further this phase will develop a new methodology for life-time prediction of fuel cells and provide an increased durability of fuel cells due to improved materials (no new development) and operating strategies.

The work in the project is organized in seven work packages; the resulting structure of the project is shown in the diagram below. Short descriptions of each work package and their interactions also given below.


Figure 6: Project structure of DECODE

Work package 1: Project management and coordination

This work package is focused on taking advantage of the project resources in a structured and efficient manner so as to achieve the objectives of the project. This requires reliable communication channels between the partners. The progress in the project will be monitored, tracked and reported continuously during the project. This work package includes also the cost monitoring by the administrative team. In addition the co-ordinator together with the steering committee will make the financial planning for the project. In this work package possible problems of administrative nature or in the exchange of know-how and samples will be solved.An agreement of the consortium will enter into force at the start phase of the project. Any new technical approach will be discussed in detail in order to ensure a full commercial utilisation by industrial partners. At each project milestone, industrial partners will decide on work programme orientation.
This task will extend over the entire length of the project and include:

  • Industrial utilisation of the results and presentation of the final work,
  • Project management guideline dedicated to the project,
  • Planning costs,
  • Reporting procedure,
  • Communication and confidentiality aspects.
The consortium agreement will be prepared using the guideline from the EC and will include: technical, commercial, organisational, financial and legal provisions.
The responsible administrative team will communicate all instructions to the partners by e-mail. Then the partners can ask the technical-scientific co-ordinator for instructions, in order to fulfil any administrative requirements. Progress of the project will be reported every three weeks by each work package leader to the technical-scientific manager, who will communicate with them as necessary. Semi-annual meetings of all partners will be held in order to give them a general knowledge of the progress and critical problems, and to generate solutions for them, as well as decide on the next quarter programme.

Work package 2: Requirements and Specifications

In order to ascertain relevance for the automotive application, operating conditions and testing procedures will be specified in accordance with the inputs of car manufacturers, whereas the results from the FCTESQA project will be taken into account. Also the material and components, which will be used in the project, will be defined to ensure that all participants work on the same materials and samples. This will ensure that the results are comparable and complementary. Therefore, the deliverables of this work package are the basis for starting the experimental work in the work packages 3, 4 and 5.

Work package 3: Investigation of Membrane and Electrodes degradation

The work package 3 aims to understand the physico-chemical phenomena responsible for the PEFC membrane electrodes assembly degradation under steady-state and transient operating conditions representative of automotive applications. Particular attention will be paid to the effect of water management or to the occurrence of liquid water on the degradation of the membranes, of the reactive layers and/or on the reduction of their performance. Experimental and theoretical efforts will be combined in order to establish MEA microstructure-properties-performance relationships, to elucidate MEA degradation and failure mechanisms, and to help improving PEFC durability.

This objective will be reached thanks to the following organization of the work package: experimental tasks, including ageing tests with in-situ analyses and ex-situ characterizations, are conducted in parallel of modelling tasks aiming to integrate the results of the experiments. This coupled approach is applied to study the degradation of the membrane and of the reactive layers. The specific degradation processes of these two components will be addressed thanks to relevant specific ageing protocols leading particularly to membrane or to reactive layer degradation and thanks to relevant specific models based on the physical phenomena occurring during their degradation. The ageing protocols will be moreover defined considering the possibility to qualify the particular effect of the water on the supposed mechanisms.

For the membranes, the main point will be to clarify the effect of the spatial distribution of water within the membrane taking also into account the mechanical stress. Also conductivity changes will be investigated on microscopic level. A specificity of these studies will be the possibility to conduct a comparative study of different types of PFSA materials, namely branched long-side-chain materials (commercial, e.g. Nafion®) and linear short-side-chain materials (developmental Hyflon® Ion) that present particularly a different behaviour with regard to water. For the reactive layers, the main point will be to outline the effect of water management and/or of liquid water occurrence on the main known mechanisms leading to losses in the active surface area whether by the oxidation of the platinum or of the carbon or by the dissolution of the electrolyte.

The results obtained on the different components characterized will be exploited to develop improved materials or components to be validated in the work package 6. The link between the work packages is ensured by the common long-term measurements in all WP 3, 4, 5 with the relevant components (membranes, electrodes, gas diffusion layers, bipolar plates). In this way, test can be performed efficiently and results and samples are shared by all work packages. Since it is experimentally easier to extract an aged GDL compared to an aged MEA from long-term measurements, the first approach will be used to provide artificially and naturally pre-aged GDLs from WP 4 for the analysis in this work package. The results of the investigations of mechanical parameters of GDL (work package 4) and bipolar plates as well as seals (work package 5) is thereby linked with the study on membrane mechanical ageing. The data on water contents for the reactive layer interacts with the studies on GDL in work package 4. Also the investigations of the interfacial degradation, mainly the delamination of the GDL from the MEA, accelerated by liquid water are used in both work packages 3 and 4. The study of electrochemical pollution of the reaction layer has to consider degradation of bipolar plates & seals which is investigated in work package 5. Also here the long-term testing represents an important communication and information exchange tie between these work packages. The generated knowledge about the degradation processes and analytic methodology will be used in work package 6.


Work package 4: GDL Degradation Characterization and Assessment

The objective of WP4 is to understand the effects and fundamental degradation mechanisms relevant to the porous media. The changes found in porous media during long term operation will be studied in detail and correlated with degradation effects observed in PEFC-operation, particularly concerning the management of liquid water. Experimental methods to quantify changes will be developed. Furthermore, selectively pre-aged materials by application of chemical, mechanical and electrochemical stress to the porous materials will be prepared.

Models and thinking tools for the description of the effects of liquid water in porous media will be developed in order to describe microscopic and nanoscopic effects. From this description changes during operation can be analysed and identified leading to a thorough understanding of degradation of porous media which at present is insufficiently studied.
The work package will start in month 1 with preparatory work to set up the models and thinking tools. Experimental work will start after the completion of WP2 in month 4. It is expected to complete the work in month 31.

Work package 4 is linked with the work packages 2, 3, 5 and 6. As described above all work packages are interlinked by the long-term measurements which are jointly analysed. Work package 4 in this context will provide artificially and naturally pre-aged components for analysis in other work packages. By linking work package 4 (GDL) with 3 (MEA) and 5 (bipolar plate) the roles and impact of interfacial processes in the degradation context will be better understood. Furthermore, by consolidating the findings of work packages 2, 3 and 5 with those from within work package 4 the sensitivity of fuel cell operation with regard to specific degradation-induced changes can be determined and thus provide prioritisation within the work package 6 effort. The generated knowledge about the degradation processes and analytic methodology will be used in work package 6. Work package 4 will integrate the results from WP3 and WP5 in the development and fine tuning of the models on thinking tools.


Work package 5: Investigation of Degradation of Bipolar Plates and Seals

The work package 5 aims to understand the fundamental degradation mechanisms of metallic bipolar plates with/without appropriate coatings as well as of bipolar plates manufactured of composite materials. In the work package not only the changes of the properties and composition of the bipolar plate materials and surfaces will be investigated. The investigation of the degradation mechanisms will be performed by in-situ and ex-situ methods and will be related to the operating conditions. Also the interactions of the degradation processes of the bipolar plates and sealings with the gas diffusion layer and the membrane electrode assembly will be investigated. The results from the ex-situ and in-situ experiments will be combined to determine fuel cell behaviour with respect to changes of properties of bipolar plates.

Work package 5 is linked with the work packages 2, 3, 4 and 6 as described above. Like for work packages 3 and 4, the results of the work package 5 will be used as input for the work package 6.


Work package 6: Improved durability

In the work package 6 the results and ideas from the work packages 3, 4 and 5 will be used to improve durability of fuel cells. In the work package the models of the individual degradation processes will be integrated into a model for description of the overall degradation of a fuel cell. This tool will be used to estimate the importance of different degradation processes and mechanisms in fuel cells and to develop a preliminary tool for the prediction of life-time for fuel cells. In addition, the components and materials which have the highest sensitivity towards life-time limitation will be determined. Based on the knowledge about the degradation mechanisms created in the work packages 3, 4 and 5 the concepts to improve the materials will be developed and tested in work package 6. As a second approach to improve the durability improved operating strategies will be developed. This approach may include the definition of operating parameters compromising the requirements from the mobile application and the requirement to avoid accelerated degradation. Both tactics to improve the durability will be experimentally proved in a long term test, as well as in accelerated fuel cell tests.

Work package 6 is dependent on the results from work packages 3, 4 and 5.


Work package 7: Recommendation and Dissemination

The objective of the work package 7 is to disseminate the results for the scientific work in order to allow non participating companies to develop own solutions to increase the life time of fuel cells basing on the knowledge generated in the project. For this purpose different forms of publications are planned:
  • Organisation of scientific work shops
  • Publication of the results in scientific journals
  • Publications in press releases
  • Internet presence
However, all information from the project will be initially treated as strictly confidential before they are not patented, so as to avoid endangering the interests of the partners. This work package is strongly linked to the scientific work packages, because the results which will be disseminated in the work package 7 are created in the work packages 2, 3, 4, 5 and 6.


B 1.3.3 Work packages list








No.

Title
Leader






 1
 Project management and coordination  DLR






 2
 Requirements and Specifications  DLR






 3
 Investigation of Membrane and Electrodes degradation  CEA






 4
 GDL Degradation Characterization and Assessment  ZSW






 5
 Investigation of Degradation of Bipolar Plates and Seals  DANA






 6
 Improved durability  DLR






 7
 Recommendation and Dissemination  JRC