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MATISSE = MAnufacTuring Improved Stack with textured Surface Electrodes for Stationary and CHP applications

Grant agreement no: 621195

Duration: 36 Months

Starting Time: 01.10.2014

Project Summary

Objectives & Consortium

MATISSE is a 36-month project targeting to the development of LT-PEMFC advanced cells and stacks for stationary applications. The consortium of the project consists of 3 industrials and 2 research organizations with CEA in the role of the project-coordinator.

Methodology

The project methodology includes assessment of stacks incremented with new materials produced and processes developed during the project. Three stack designs are addressed for the stationary fuel cell operating conditions in H2/O2, H2/air and reformate H2/air–mode.

MATISSE intends to achieve objectives in terms of stack robustness, lifetime, performance and cost. For this purpose, advanced material solutions are validated as proof of concept for the manufacturability of cells and stacks. The materials are validated based on defined test protocols for functional and durability testing. Applied devices for measuring the current density distribution give valuable information during electrode development and advanced ex-situ post-mortem analyzing methods are applied along the evaluation steps.

Textured (non-homogeneous) electrodes are aimed on avoiding electrode flooding or drying to reduce degradation phenomena, previously investigated by ex-situ analysis conducted on reference components. The manufacturability of advanced electrodes is demonstrated by using a continuous screen printing process to make the catalyst layers and by the automation of the membrane electrodes assembly step. This is aimed on reducing costs to meet the market target allowing a large deployment of stationary PEMFC systems. In this context cost assessments are carried out to assess the progression of MATISSE stack technology toward the objectives of the market.

Development and Manufacturing of Textured Electrodes

The overall scientific approach of the project is to develop and manufacture textured electrodes for tree different stack designs comprising also tree different applications. Besides technical aspects like robustness and lifetime and performance, cost-issues and proved manufacturability are also considered in the development. Applied local diagnostic-tools like segmented cells during stack-testing are giving advanced information about the individual status of the Membrane-Electrode-Assembly (MEA) during validation tests.  

Advanced cell development is conducted by the development of specific inks according to cell design and operating conditions (figure 1), considering segmented cell information. The first evaluation of each ink is performed on 25cm² single cell level, going subsequent ahead to the original stack-design if results are promising.

Figure 1: Principle of ink-development within the MATISSE-project
Figure 1: Principle of ink-development within the MATISSE-project

Baselines for textured non-homogenous electrodes are the results of the initially produced homogeneous electrodes (reference).

After selection of best electrode-compositions, the manual processes are transferred to automated processes of MEA-fabrication (pilot line), as schematically shown in figure 2, and automated stack assembly at AREVA. 

Figure 2: Example - Automated production line for electrodes at CEA
Figure 2: Example - Automated production line for electrodes at CEA

Accompanying to the described processes, specific system recommendations (BoP) and cost studies are evaluated based on the new electrodes and MEAs for the individual stack designs and applications. The feasibility and reproducibility of the automated process is proved on one selected design by a production volume of 200 MEAs at CEA.

Applied current density distribution plates on short stack level in the original stack hardware design give valuable information about the homogeneity of the current density like exemplary presented in figure 3. Changes in hydrophobicity in electrodes compared to reference material can easily be traced by ono-by-one comparison in defined load levels in reference operating conditions.

Figure 3: Three-and two-dimensional evaluation of current density measurement data
Figure 3: Three-and two-dimensional evaluation of current density measurement data

Durability of the MEAs is evaluated by application- and partner specific test programs. For example, the test program for reformate hydrogen/air application is a long-term test of at least 3000 operation hours including defined start-stops (see figure 4), whereat the durability of MEAs for regular hydrogen/air application of another industrial partner has to be proved in an Accelerated Stress Test AST (see figure 5).

Figure 4: partner-specific test program of MEAs for reformate hydrogen/air application
Figure 4: partner-specific test program of MEAs for reformate hydrogen/air application
Figure 5: partner-specific test program of MEAs for hydrogen/air application

Durability is evaluated by polarization-curves in defined conditions. Therefore, aging is followed during the durability-test by initial (begin of test), intermediate and final (end of test) polarization curves.

Figure 6 presents exemplary the followed irreversible degradation-rate over a 2-week AST- test of reference electrode based on the load profile shown in figure 4, depicting one cell of a four-cell stack. The test operating parameters relative humidity anode (hydrogen gas flow rH 75%), relative humidity cathode (air flow rH 75%) and stack temperature (coolant inlet 65°C) are shortened in column by 75-75-65.

Figure 7 presents the average voltage evolution during the test. Valuable information about degradation is additionally gained by applied electrochemical methods, also performed at begin, middle and end of test.  

Figure 6: Evaluation of irreversible degradation by polarization curves in defined conditions
Figure 6: Evaluation of irreversible degradation by polarization curves in defined conditions
Figure 7: AST- test reference-MEA (hydrogen/air) - Evolution average cell voltage
Figure 7: AST- test reference-MEA (hydrogen/air) - Evolution average cell voltage

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