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

Periodic Reporting for period 2 - DOLPHIN (Disruptive PEMFC stack with nOvel materials, Processes, arcHitecture and optimized Interfaces)

Reporting period: 2020-07-01 to 2021-07-31

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 public market but the stack cost still needs to be reduced and durability to be improved. Filling the gap between present State Of the Art and expected targets will not be possible by an incremental approach.
The DOLPHIN project is thus exploring an innovative route to produce light & compact PEMFC stacks, combining different approaches: thin (metallic or composite) bipolar plate, rib-channel dimensions, GDL, and membrane; composite terminal plate; Single Layer Graphene to reduce H2 permeation; graded catalyst layers. A 5 kW stack will be manufactured and tested to check the progress compared to the KPIs below (SoA in 2017):
• 4.0 kW/kg (3.4)
• 5.0 kW/l (4.1)
• 2 W/cm² @0.66 V (1.13)
• < 20 €/kW (36.8)
• Durability: 6000 hours (3500)
• Stack max operating temperature: 105 °C (95)
Specification and design:
• 100 kW stack, 5 kW stack (on-going), including performance specifications and operating conditions, and their components (dimensions, thickness, main physical properties)
• test protocols for performance, durability, and model fitting
• modular single cell test platforms to analyse 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
• terminal plates to reduce mass and volume by using composite materials rather than the classical Aluminium
• based on 2D and 3D modelling, an improved innovative flow-field design (anode and cathode) has been proposed to improve performance; it will be tested in TP2

Manufacturing and test of components:
• TP1 hardware has been manufactured and tests are on-going
• TP2 hardware has been manufactured and tests have started
• 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 a) printing conductive ribs (down to 200 µm pitch) onto flat thin (metallic and carbon-based) sheets for TP1 and TP2, b) additive manufacturing (700 µm pitch, metallic sheets) for TP1 and TP2, and c) 3D moulded carbon composite (600 µm pitch)
• 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 leading to increased performance
• 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

An online public workshop has been done, and production of three NewsLetters, one press release, and three LinkedIn posts; participation to a workshop organized by Toyota.
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.
Manufacturing of Flow-Fields with ultra thin rib/channel pitch, using innovative processes
Power density is increased with thin flow fields (CEA)
Design of composite light Terminal Plate (Hexcel)
Samples for TP2 tests (CEA, DMG-MORI)
High permeability ionomer (CHEM)
Example of polarisation curve with thinner rib/channel pitch (CEA)
Performance of the 'MPL-only' solution (ZSW, CEA)