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Disruptive PEMFC stack with nOvel materials, Processes, arcHitecture and optimized Interfaces

Periodic Reporting for period 1 - DOLPHIN (Disruptive PEMFC stack with nOvel materials, Processes, arcHitecture and optimized Interfaces)

Reporting period: 2019-01-01 to 2020-06-30

Hydrogen is a very promising solution to produce and use sustainable energy. Thanks to different developments over the last 20 years, Proton Exchange Membrane Fuel Cell (PEMFC) cars are now on the threshold of market introduction, but the stack cost still needs to be reduced and durability to be proven. Filling the gap between present State Of the Art and expected targets will not be possible by an incremental approach.
In this perspective, the DOLPHIN project is exploring a highly innovative route to produce light-weight & compact PEMFC stacks, combining different objectives: thin (metallic or composite) bipolar plate, rib-channel dimensions, GDL, and membrane; composite terminal plate integrating some stack/system functions; Single Layer Graphene to avoid H2 permeation; catalyst layers with gradients. A 5 kW stack will be manufactured and tested to check the progress compared to the KPIs below.
Main KPIs of DOLPHIN:
• 4.0 kW/kg (SoA 2017 = 3.4)
• 5.0 kW/l (SoA 2017 = 4.1)
• 2 W/cm² @0.66 V (SoA 2017 = 1.13)
• < 20 €/kW (SoA 2017 = 36.8)
• Durability: 6000 hours (SoA 2017 = 3500)
• Stack max operating temperature: 105 °C (SoA 2017 = 95)
The first period was focused on defining the different material and test specifications, and manufacturing and testing some first developments.

Specification and design of the:
• 100kW stack including performance specifications (KPIs, power and current densities for different scenarii of operation), and operating conditions
• different components of the stack (dimensions, thickness, main physical properties)
• test protocols to check performance and durability, and to allow model fitting
• rib-channel sizes with the analysis of the link between dimensions and stack performance
• terminal plates for which first results show a potential reduction of mass and volume by using composite materials rather than the classical Aluminium
• modular single cell test platforms to analyze the performance of the solutions developed in the project : TP1 (1.8 cm²) to mimic local stack operating conditions ; TP2 (100 cm²) as a first step towards the short stacks and the final 5 kW stack demonstrator

Manufacturing and test of first components:
• TP1 tests on machined metallic plates have demonstrated that reducing the pitch (from 600 µm down to 200 µm) allows to increase the performance (~20-30 % in power density)
• samples were successfully prepared by printing conductive ribs (down to 200 µm pitch) onto flat thin (metallic and carbon-based) sheets ; first performance tests are promising
• first samples were successfully obtained by additive manufacturing (700 µm pitch, metallic sheets) and 3D moulded carbon composite (600 µm pitch).
• modeling shows that 75 µm thick stainless steel sheets could be stamped ; confirmation tests are planned
• Gas Diffusion Medium (GDM) has been produced with a thickness lower than 100 µm ; performance tests are promising ; work is on-going to reduce its thickness after treatments
• A 10 µm thick prototype re-inforced membrane has been supplied and first tests are promising
• An improved ionomer with high oxygen permeability (HOPI) is under development, first characterization tests are promising
• Single Layer Graphene (SLG) was successfully transferred onto the membrane ; H2 crossover is reduced, work is on-going to increase its proton conductivity
• stand-alone protective diffusion layer has been successfully prepared as a first step towards the no-GDM route ; performance is comparable to the standard coated MicroPorous Layers
Progress beyond SoA and expected results
• one-atom Single Layer Graphene (SLG) coating onto thin (10 µm re-inforced) membrane to reduce H2 cross-over with good proton conductivity, compatible with operating temperatures up to 120°C
• improved ionomer with higher oxygen permeability
• active layers with Pt/ionomer gradients coated onto the membrane and/or the SLG
• thin (< 100 µm) GDL with more controlled and stable hydrophobic treatment
• even more disruptive will be to remove the GDM, using only a protective coating onto the active layers
• rib-channels with ultra-thin pitch as produced by ink printing (~200 µm), laser milling (~200 µm), or additive manufacturing (~500 µm); this could lead to a cooling circuit independant of the air and H2 flow fields and thus allow to better manage fluidic and thermal transfers
• flow-fields produced with thin (75 µm) sheets: stamped metallic and moulded carbon
• lightweight composite terminal plate integrating some Balance of Stack functions
• comparison of the different technological solutions in terms of manufacturability, scale-up and cost
• assembly of the most relevant developments to produce and test (preformance and durability) a 5 kW stack demonstrator capable to fulfill the KPIs

Potential impacts (including the socio-economic impact and the wider societal implications of the project so far)
The DOLPHIN project constitutes another step forward towards the development in Europe of the whole value chain for hydrogen fuel cells. The project is focused on automotive applications but most of the developments are also relevant for other applications (railway, buses...).

The project will have positive impacts for the partners:
• HEXCEL will gain knowledge and know-how on the use of composite materials in the fuel cell market and creates networking opportunities with leading companies and research institutes on the field of renewable energies. All this will allow to facilitate the access to a potential new market for HEXCEL and hence secure (and create) jobs along the whole production chain of composite materials (fiber manufacture, reinforcement manufacture, prepreg manufacture)
• SYMBIO (now a 50/50 joint venture between FAURECIA and MICHELIN) has already set up an ambitious strategy to become a leading actor in the Fuel Cell vehicles shift by 2030 (with a target of an annual production of 200 000 stacks). DOLPHIN will consist in another step forward towards the industrialization of high-performance fuel cells as one objective is to have at the end of the project fuel cell components that are as close as possible of the industrialization process
• CHEMOURS will have access to relevant results on its last developments and thus confirm their commercialization interest for automotive application
• In the research institutes (ZSW, CEA, UoM), DOLPHIN allows increasing the knowledge in terms of material developments, test protocols and performance, in relationship with top-leading industrial actors. Direct technology transfers to industrial partners will be discussed as relevant. The project also allows to secure permanent jobs and to hire some additional researchers (students, fix-term contracts) contributing to train them for the future of H2 European industry.