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Cost-effective and flexible 3D printed SOFC stacks for commercial applications

Periodic Reporting for period 3 - Cell3Ditor (Cost-effective and flexible 3D printed SOFC stacks for commercial applications)

Période du rapport: 2019-01-01 au 2020-04-30

The implantation of efficient and clean technologies for energy production is currently a major issue. Solid Oxide Fuel Cell (SOFC) are highly efficient systems converting chemical energy stored in a fuel into electricity and usable heat. Being a ceramic-based multi-layer device, its fabrication involves expensive and time-consuming multi-step manufacturing processes (more than 100 steps) and several high-temperature thermal treatments. The Cell3Ditor project addresses the main challenge of improving production processes of SOFC systems by introducing novel manufacturing technologies such as 3D printing of ceramics. The project develops 3D printing technology for mass manufacturing of SOFC cells and stacks with the final aim of reducing costs and time to market and simplifying the design for manufacturing while giving flexibility to the final product.

Pursuing the aforementioned goals, the Cell3Ditor project reached many important achievements in different fronts.

The project drove the field of 3D printing of ceramics by supplying a multi-material hybrid ceramic printer, all the necessary slurries and inks for the production of SOFCs, and printing and post-printing procedures for the generation of single-repeating units. Two concepts were devised for the fabrication of SOFC cells that provide interesting outcomes and set the basis for future generation of devices and manufacturing processes. The first pursued the enhancement of the cell performance by enhancing the active area, which was successfully demonstrated (60% increase was demonstrated in a proof of concept using corrugated membranes). The second aimed impacting the fabrication process itself and consisted in the generation of Single Repeating Units (SRUs) in a single printing process.

The Cell3Ditor project has delivered tools for the development of business, has provided evidences of the energy and environmental efficiency and has given visibility to the 3D printing of ceramics in SOFCs production. Two business plans, patent landscape, and an LCA were conducted. Also intensive dissemination and communication of the project’s goals and results were carried out. An acknowledgement of the project’s success is the achievement of the award to the most innovative project by the Fuel Cells and Hydrogen Joint Undertaking and the grant with the very prestigious Solar Impulse Label.
The Cell3Ditor project has worked in the main objectives devised for achieving the final goal of defining new manufacturing paragons for the fabrication of SOFCs based on 3D printing technologies. Advances have been achieved in parallel in the development of printable feedstock, a dual multimaterial 3D printer, and optimized processes, including printing and co-sintering.

The first part of the project provided an accurate definition of final specification of the system to be 3D printed, based on Finite Elements Simulations (FEM), laying the funds of the requirements of this 3D printing technology.

An outcome of the project has been the development of printable feedstocks of YSZ for SLA, pastes for Robocasting and inks of nano-composites for inkjet. The addition of cathode, anode, electrolyte and interconnections materials to the palette of available material increase will help the development of the flourishing field of 3D printing of ceramics.

An important achievement was the development of a unique device for 3D printing multi-materials. Currently, the hybrid multi-material 3D printing machine is fully operative and successfully commercialized by one of the partners (3DCeram-Sinto), supposing a table-top factory for the development of high added value pieces and devices based on functional ceramics.

The joint efforts carried out by the multi-disciplinary consortium in the different aspects of the production process allowed an enhancement of the maturity of the ceramic 3D printing technology applied to SOFCs. Fully printed (SLA+Robocasting) Single Repeating Units (SRUs) and cells with complex structures have been fabricated and tested, demonstrating the potential of this approach. These pioneering results set the basis for future development of high temperature devices in the field of energy.

The Cell3Ditor project included efforts for identifying the most promising exploitable results and finding the best routes for a successful exploitation of the developed technologies. Two market analyses have been performed looking for the best possible approach to the market. The patent landscape and freedom-to-operate scenario has been updated along the project. In this context, four patents have already arisen fruit of the project developments. Also, a Life Cycle Analysis was conducted with real process data, showing a noticeable reduction of greenhouse gases emission among other.

Dissemination has received a major attention from specialized audience and general public. Intensive participation in congresses, fairs and other outreach activities was key in reaching different target public. Also, successful dissemination around the world was achieved thanks to different channels, including the website, with more than 12.000 visits, and several social media: Twitter, Youtube, and Researchgate.
The Cell3Ditor project has supplied several outcomes that represent clear advances beyond the state of the art. Among the most important achievements are:

- A dual multi-material ceramic 3D printer has been developed for the first time, capable to provide complex pieces and devices with a 30x30x12 cm3 platform. The readiness level of this device has progressed from at a lab scale (TRL4) to a final commercialized device (TRL9).

- Ceramic slurries and inks adapted to the 3D printing processes. The materials added to the palette include electrolyte (8YSZ) cathode (LSM), anode composites (Ni-YSZ) and interconnect (LCTM), and voids. Importantly, the rheological properties and interaction with different required curing agents (i.e. UV light, IR light or heat) has been matched to the requirements of the specific 3D printing technique. The maturity level of the inks has moved from first concepts and laboratory tests (TRL2) to a commercial product (TRL 9)

- Printing procedures for the fast and accurate printing of complex multi-material pieces. Best parameters were pursued for slurry and ink curability by the implementation light and heat sources.

- Sintering and co-sintering procedures were defined for the achieving of compact crack-free pieces. Complex geometries of ionic conductor gas tight electrolytes have been achieved. The main challenge still unsolved is the simultaneous sintering (co-sintering) of dense electrolytes together with porous cathode layers. In this case, the maturity of the technology progressed from the initial formulated concept to the first proof of concept demonstrated in the laboratory (TRL 3-4)

- Assessment the energy and raw materials demands of the complete fabrication processes defined and its comparison with state of the art procedures.

- Detection and study of the most promising exploitable outcomes of the project (PEDR, two business plans and freedom to operate studies). Four patents have been achieved and a fifth one is under preparation, which will help future exploitation.

- Vast dissemination and communication of the project results and goals to specialized actors and to the general public, with special emphasis on young citizens.
Scheme of the system devised in the Cell3Ditor project (up). CERAMAKER 3D printing machine and examp