Project Objectives

The main objective of Second Act is to improve understanding of stack degradation and propose durability improvements for μCHP systems using PEMFC or DMFC. The project aims at: • Analysing long term lifetime tests data from existing systems to identify main causes for failure related to system operation and quantify performance degradation of the stacks, over the long term (at least 10,000 hrs and more than 20,000 hrs for some systems considered) • Conducting lifetime tests to investigate degradation at cell and stack levels and to better understand mechanisms involved. Common degradation mechanisms in stack components (electrodes mainly) will be particularly considered to help identifying similar type of improvements on materials and processes to be implemented for lifetime extension. • Developing, applying and validating accelerated stress tests (AST) and specific tests representative of failures in harsh conditions for the different Fuel Cell technologies • Developing and applying in-situ and ex-situ investigation techniques for better identification and local resolution of the degradation mechanisms. Heterogeneities in degradation over the cells surface and across the stacks will be particularly tackled, with regards to local operation and local conditions (including fuel composition) • Developing new statistical approach and models for better understanding and description of systems stochastic/deterministic degradation, reversible/permanent degradation and heterogeneities of degradation in single cells and stacks. • Demonstrating stack lifetime improvements increased tolerance to applications’ relevant cycling or operating modes (e.g. start/stop or idle), mainly through stack components modifications (in materials, components design, manufacturing processes…) for Pure H2, Reformate PEMFC and DMFC. For the improvements of Membrane Electrodes Assemblies that will be particularly considered as core components, two routes will be followed, one on raw materials and manufacturing processes to face mainly defects and one on structured (nonhomogeneous) electrodes and GDL to face mainly degradation heterogeneities. o Improvements will address particular causes of performance degradation or sources of stack failure thanks to better understanding gained with experimental and modelling investigations o Improvements will be verified at cell and stack level in existing designs, following validated AST or specific harsh tests in conditions representative of the systems considered.