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

Project Information

DOLPHIN

Grant agreement ID: 826204

DOI

10.3030/826204

Project closed

EC signature date 13 December 2018

Start date 1 January 2019

End date 31 December 2023

Funded under

• SOCIETAL CHALLENGES - Climate action, Environment, Resource Efficiency and Raw Materials

Total cost

€ 2 962 681,25

EU contribution

€ 2 962 681,25

Coordinated by

COMMISSARIAT A L ENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES
France

Periodic Reporting for period 4 - DOLPHIN (Disruptive PEMFC stack with nOvel materials, Processes, arcHitecture and optimized Interfaces)

Reporting period: 2022-10-01 to 2023-12-31

Summary of the context and overall objectives of the project

The DOLPHIN project is exploring an innovative route to produce light & compact PEMFC stacks, combining different approaches: reduction of rib-channel dimensions; different processes to manufacture the corresponding bipolar plates (very thin metallic and carbon sheets, GDL machining, stamping, printing, additive manufacturing, laser milling); improved ionomer and membrane; improved ink formulation and process of the catalyst layers; composite light terminal plate; Single Layer Graphene to reduce H2 cross-over… Based on the two most promising technologies selected by a step-by-step approach (1.8 cm² single cell, then 100 cm² single cell, then 100 cm² 6-cells), 5 kW demonstrator tests are planned to check the progress compared to the KPIs targeted below (Table 1).
Numerous of the objectives above have been reached, for instance a) reduction of rib-channel dimensions (CEA), b) manufacturing of bipolar plates with thin designs by GDL machining (CEA), printing (CEA), additive manufacturing (DMG-MORI), stamping (SYMBIO), and laser milling (ZSW), c) supply and use of improved ionomer and membrane (CHEMOURS), d) development of improved ink formulation and process of the catalyst layers (CEA), e) development of a composite light terminal plate (Hexcel), and f) coating of Single Layer Graphene onto membranes (UoM).

The performance reached (@3A/cm², GAIA conditions) with the TP4-2 short stack combining machined GDL and printing, is high (1.8 W/cm²) with very high compactness (6.6 kW/l @3A/cm²) and (8.4 kW/kg @3A/cm²) and a manufacturing cost realistic to target 20 €/kW and manufacturing time cycle realistic for mass production for automotive application.

The project has reached most of the objectives and numerous KPIs, and opened the route towards more efficient stacks for automotive application.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Different hardware have been manufactured and tested for step by step selection
o TP1, TP2 and TP3 hardware have been designed, manufactured and used for performance tests and step by step material/process selection, from 1.8 to 175 cm²
o TP4 stacks have been manufactured, assembled and tested, using the same electrochemical core (developed in the project) and the two most promising fluidic cores: additive manufacturing (TP4-1), and GDL machining combined with printing (TP4-2)
o TP1 tests on machined metallic plates have demonstrated that reducing the rib/channel dimensions (from 600 µm down to 200 µm) allows increasing the performance (~20-30 % in power density)
o samples were successfully prepared for the fluidic cores by a) printing conductive ribs (down to 200 µm rib-channel pitch) onto flat thin (20 µm) metallic and carbon-based sheets, b) additive manufacturing (700 µm pitch, metallic sheets), c) 3D moulded carbon composite (600 µm pitch), and d) GDL machining (down to 800 µm pitch)
o samples leading to the same performance as the ‘best’ commercial ones were successfully prepared for the electrochemical core thanks to a) 10 µm thick prototype re-inforced membrane, b) use of alternative Pt/C commercial materials, and c) improvement of ink formulation and manufacturing process
o a 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
o Gas Diffusion Medium (GDM) has been produced with a thickness ~100 µm; performance tests were promising but additional work will be necessary to better control its final thickness after treatments (hydrophobic and microporous layer coatings)

The two most promising technological solutions identified are:
• GDL machining to produce the gas flow fields on the active surface, combined with ink printing for the manifolds; this leads to high performance (1.8 W/cm² @3A/cm²) and very high compactness (6.6 kW/l @3A/cm²) and (8.4 kW/kg @3A/cm²) with a manufacturing cost realistic to target 20 €/kW and manufacturing time cycle realistic for mass production for automotive application
• Additive manufacturing to produce the full bipolar plate in one step; this leads to the highest performance (~ 1.97 W/cm²) due to the very thin rib-channel dimensions achievable; nevertheless the compactness will be lower and the manufacturing cost and time cycle are too important; unfortunately TP4-1 stack could not be properly assembled as the bipolar plates manufactured by additive manufacturing were not flat enough, leading to leakage and local over-compression
Each of these technologies have been combined with the improved ink formulation and process for the catalyst layers with the materials of the project; this allows the same performance as ‘most advanced’ commercial MEA.

In addition, different operating conditions have been discussed and tested (see §1.1.4). The best performance is achieved with the GAIA operating conditions.

Cost Assessment:
DOLPHIN project allowed to cost assess a wide range of innovative solutions covering novel materials, processes and architectures. Throughout the project, around 10 concepts and innovations were evaluated, as well as 5 manufacturing routes, to assess the potential €/kW for a 100 kW stack.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Progress beyond SoA
• Performance (W/cm²) can be improved by reducing the rib-channel pitch
• Flow-fields with downsized rib-channel pitch have been manufactured by a) printing conductive ribs (~ 200 µm rib-channel pitch) onto flat thin (down to 20 µm) metallic and carbon-based sheets, b) additive manufacturing (~ 700 µm pitch, metallic sheets), c) 3D molded carbon composite (~ 600 µm pitch), and d) Gas Diffusion Layer machining (~ 800 µm pitch); this allows the cooling circuit to be independent of the air and H2 flow fields and thus allows to better manage fluidic and thermal transfers
• Comparison of different technological solutions in terms of manufacturability, scale-up and cost
• The performance can be kept (W/cm²) when removing a carbon fiber substrate on one side (GDM-only route), allowing reducing the weight and volume of the stack
• Very high performance has been reached (1.8 W/cm²@3A/cm²) on TP4-2, and based on this technology, (6.6 kW/l @3A/cm²) and (8.4 kW/kg @3A/cm²), 25€/kW can be expected for a full 100kW stack suitable for automotive application

Potential impacts
• SYMBIO (now a joint venture between FAURECIA, MICHELIN, and STELLANTIS) has 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 has allowed another step forward towards the industrialization of high-performance fuel cell stacks. Important investments (manufacturing capabilities, research and industrial tests, hardware, technicians, engineers, Ph. D…) have been done during the project
• CHEMOURS had access to relevant results on its last developments and has confirmed their commercialization interest for PEMFC
• For the research institutes (ZSW, CEA, UoM), DOLPHIN has allowed 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. The project has also allowed 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)

Estimation of the KPIs for a 100kW stack, based on TP4-2