3D-Printing of Proton Conducting Ceramics
Authors: Nadolska Małgorzata , Pośpiech Joanna , Sobczyk Tomasz , Chmielewski Marek , Szpunar Iga , Wachowski Sebastian 
Published: July 2021

3D-printing technology is being extensively utilized in energy sector, as it allows for manufacturing complex structures (compacted stacks, desired microarchitectures and porosity) and customizable shapes for specific devices. Moreover, fast prototyping time and reduction of production cost make this technology promising for industrial applications. Up to now, plenty of 3D-printed energy conversion and storage devices and hence precursor materials have been proposed. Reported examples concern solar cells, biofuel cells, rechargeable ion batteries, carbon-based supercapacitors and others [1-2]. On the other hand, 3D-printing of proton-conducting materials is rarely reported. The pioneering research was presented by Mu et al., who have developed novel laser 3D-printing method which allows to obtain protonic ceramics with the desired crystal structures, microstructures, and geometries [3]. The method consists of the preparation of printable paste from component raw materials (carbonate and single metal oxides) mixed with sintering aid, the deposition of a thin green film of the targeted protonic ceramics, and the reactive sintering by rapid CO2 laser scanning. Such method was successfully applied for the synthesis of dense electrolytes (e.g. BCZYYb, BZY20), porous electrodes (e.g. BCZYYb+NiO, BaCo0.4Fe0.4Zr0.1Y0.1O3-δ), dense interconnect (La0.7Sr0.3CrO3-δ/LSC), and dense mixed protonic and electronic-conduction composite (BaCe0.85Fe0.15O3-δ– BaCe0.15Fe0.85O3-δ/BCF) [4]. The second available example is devoted to the 3D-printed proton exchange membrane and has been recently reported by K. Iwase and co-workers [5]. Scientists developed UV-cured ink (mixture of proton-conducting ionic liquids, inorganic silica nanoparticles, and UV-sensitive photocurable resins) which can be successfully applied to the printing of proton exchange membranes.
In the present study, we developed 3D-printing of protonic ceramics- Ba0.5La0.5Co1-xFexO3-δ (0 ≤x≤ 1), which are promising materials for positrodes in protonic ceramic fuel cells [6]. The Project is devoted both to the construction of 3D-printer and ink preparation. Two printing technology- fused deposition modeling and extrusion-based 3D-printing were selected and embedded into one 3D-printer. In addition, the system was equipped with IR laser for post-processing. Ink (solid filament or gel) was prepared from ceramic powder and polymer (i.e. polylactic acid or polyvinyl alcohol), which act as a matrix and is removed at the end. Various compositions (e.g.ceramic to polymer ratio, polymer concentration, solvent) and synthesis conditions (e.g. time, temperature) were tested. A lot of attention was paid to the proper ceramic dispersion, which ensures printouts homogeneity. Therefore, various approaches such as ball-milling of ceramic and ultrasonication of gel were optimized and implemented. The last important step was devoted to the laser post-processing, during which polymer is removed and ceramic is sintered. Various laser powers, scan speeds and number of scans were tested. Printed layers before and after post-processing were characterized by X-Ray diffraction, Fourier Transform Infra-Red spectroscopy and Scanning Electron Microscopy. In the future it is planned to adopt developed technology and use it for the printing of multi-layered positrodes with graded functionality.

References

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Acknowledgements

Project FunKeyCat is supported by the National Science Centre, Poland under the M-ERA.NET 2, which has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement no 685451.