This work presents a discretization strategy based on the Continuous Galerkin (CG) formulation with a new Adaptative Mesh Refinement (AMR) strategy to simulate Direct Steam Internal Reforming Solid Oxide Fuel Cells (DIR-SOFC). The governing equations used in the proposed methodology are based on Ohm's law for the electrochemical potentials at each conductive phase and the Dusty Gas Model (DGM) for species diffusion, assuming uniform and constant temperature and pressure. The reactions induced in the different regions of the domain (electrolyte, anode, and cathode) result in sharp variations of the solution on the different interfaces that need to be properly captured. Thus, to enhance the simulation accuracy and efficiency, a new AMR strategy is proposed, refining the mesh according to the error estimators of the potentials. Additionally, a novel iterative approach to accurately approximate the concentration polarization in the anode by employing the Bulter-Volmer equations is also presented for the Direct Internal Reforming (DIR). Finally, we present several examples to validate and assess the capabilities of this formulation and validate the numerical results with reference examples. Furthermore, a parametric analysis is conducted to investigate the impact of temperature and cell current on potentials, chemical composition, and fuel cell efficiency.

Cobalt-free oxide electrode materials have received increasing attention due to the interest in replacing critical raw materials in clean energy technologies. Among other compositions, La0.6Sr0.4Fe0.8Cu0.2O3-delta (LSFCu)-based perovskites were proposed in the past for Solid Oxide Fuel Cell (SOFCs) applications due to their mixed ionic-electronic conductivity and low polarisation resistance. In this work, novel LSFCu-based compositions have been explored for their use as oxygen electrodes in SOFC and Solid Oxide Electrolysis Cells (SOECs). Single-phase LSFCu and fluorite-perovskite nanocomposites with (La,Ce)O2-delta-(La,Ce)0.6Sr0.4Fe0.8Cu0.2O3-delta composition were studied, the latter resulting from a one-pot co-synthesis of LSFCu and ceria with intermediate compositions reached by substantial cerium-lanthanum cation intermixing after self-organised phase separation. The best performances were achieved for compositionally complex nanocomposites based on 20% and 50% ceria with full-cell power densities of 1.15 and 1.26 W cm-2 in SOFC mode (0.7 V), and current densities of 1.41 and 1.75 A cm-2 in SOEC mode (1.3 V), at 800 degrees C. Durability tests performed in SOFC mode at 800 degrees C under high current densities (1 A cm-2) during nearly 900 h confirmed the benefits of optimal ceria incorporation, showing a remarkable reduction (7 & times; lower) in the degradation rate compared to single-phase LSFCu. This work presents a straightforward approach to fabricating cobalt-free oxygen electrodes for SOC technology, opening a new avenue for developing highly complex composition (high entropy) self-organised nanocomposites.

Solid Oxide Fuel and Electrolysis Cells (SOFC/SOEC) are a promising solution for clean power generation and highly efficient hydrogen production, but their deployment is still hindered by high manufacturing costs, slow start-up times, limited thermo-mechanical robustness, and relatively low volumetric and gravimetric power densities, particularly for mobility applications. Advanced manufacturing routes such as 3D printing have demonstrated the potential to address some of these issues by enabling unexplored geometries that improve thermo-mechanical properties while increasing specific power. However, the upscaling of such techniques is still in its infancy, and the associated costs remain uncertain. This study evaluates the manufacturing cost of complex-shape SOFC stacks based on corrugated electrolyte-supported cells produced via ceramic stereolithography (SLA). The costs are compared with reference stacks fabricated using conventional manufacturing routes. A bottom-up cost model assesses material usage, capital, labor, utilities, indirect cost contributions, and volumetric and gravimetric power density for a 5 kW module across different production volumes. The results show that the SLA-based stack concept achieves a cost per unit of power of 2047-777-627 €·kW⁻¹ for 1-10-25 MW·y⁻¹ of production capacity, compared with 2420-928-725 €·kW⁻¹ for the state-of-the-art stack concept at the same installed capacities. This trend changes above 60 MW·y⁻¹. The reduction is mainly related to lower capital expenditure and material consumption. Sensitivity analyses identify current density, electrolyte cost, and manufacturing learning effects as the dominant cost drivers. These findings indicate that additive manufacturing enables a viable pathway toward compact, lightweight, and cost-effective solid oxide stacks suitable for mobility and aviation applications.

Compact Mn–Cu spinel protective coatings were fabricated on AISI 441 ferritic stainless steel by electrophoretic deposition (EPD) followed by rapid thermal processing (RTP). The proposed approach enabled the formation of compact, adherent and partially densified coatings within significantly reduced processing times (below 1 h). A processing window was identified by varying RTP temperature and dwell time, highlighting the strong influence of thermal parameters on coating densification and adhesion. In situ high-temperature X-ray diffraction (HT-XRD) analysis of the Mn–Cu spinel powder revealed phase evolution during heating, including the growth of CuO-related peaks and spinel instability at 950 °C. Microstructural characterization showed that RTP conditions strongly affect coating morphology, densification behaviour, and thickness uniformity. Crack-free coatings were obtained under optimized conditions, while EDS analysis showed no detectable chromia scale formation at the coating/substrate interface after RTP treatment. The results demonstrate that RTP-assisted EPD is a promising and potentially scalable route for the fabrication of Mn–Cu spinel protective coatings for SOC interconnects, enabling rapid densification while limiting thermal exposure and interfacial degradation phenomena.

Introduction Solid Oxide Cells (SOCs) are emerging as a robust technology in the frame of energy conversion, primarily due to their exceptional efficiency and remarkable fuel flexibility. These devices operate at elevated temperatures, which facilitates high ionic conduction. Such versatility makes SOCs highly attractive for a wide range of applications, from stationary power generation to the integration of renewable energy sources for grid balance. Over the past decades, extensive research has focused on optimizing the electrochemical processes within these cells, leading to significant improvements in both performance and durability. Recent advancements have underscored the advantages of operating SOCs under high-pressure conditions. [1] Increasing the partial pressures of the reactants has been shown, through both simulation and experimental studies, to enhance the electrochemical reaction rates, thereby boosting the overall efficiency [2,3]. In the context of electrolysis, where solid oxide electrolysis cells (SOECs) are employed, the benefits extend further. Operating under pressure not only accelerates the reaction kinetics but also enables the direct production of pressurized hydrogen. This integrated approach offers an alternative to conventional mechanical hydrogen compressors. Although these compressors are well-established, their initial stages compressing hydrogen from atmospheric levels to several bars are high energy demands. By combining the electrochemical generation and compression of hydrogen within a single process, overall energy consumption can be significantly reduced [4]. Despite these promising advantages, the implementation of high-pressure SOCs is not without its challenges. To date, all SOC systems that have been tested under elevated pressures have required the use of a pressure vessel. This necessity imposes a twofold penalty: the system becomes bulkier, and the energy losses increase due to the low performance of thermal insulation materials at high pressures. The current generation of cells and sealants is generally optimized for lower-pressure differentials, 10-20 mbar, and their inherent limitations restrict in the low-pressure gradients the components can sustain. Consequently, the design of these components becomes a critical factor in ensuring both the mechanical integrity and the overall efficiency of the system. Recently, C. Grosselindemann et.al presented a work in which they developed a vessel-free set-up and demonstrated the possibility of operating a 1 by 1 cm cell up to 11 bars of pressure [5]. Recently, ceramic additive manufacturing has emerged as a revolutionary technique in the fabrication of Solid Oxide Cells (SOCs), particularly for producing complex shape electrolytes that are impossible to produce using traditional ceramic manufacturing methods like tape casting or extrusion. This additive manufacturing approach enables precise control over component geometry, thereby facilitating the creation of intricate architectures that not only optimize gas distribution but also enhance mechanical stability by producing a corrugated membrane [6]. In contrast to conventional ceramic fabrication, which often involves multiple processing steps and results in significant material waste, 3D printing offers a direct and efficient pathway for component production with minimal material loss. The inherent layer-by-layer construction process further allows for the integration of tailored porosity and finely tuned microstructures, critical factors that improve both ionic conductivity and mechanical robustness. Beyond these immediate advantages, the adoption of 3D printing techniques represents a significant step forward in the design and performance optimization of SOCs. For example, as demonstrated by A. Martos et al. [7], the implementation of complex shape geometries effectively simplifies the single repeating unit (SRU) by enabling gas transport directly through the corrugated membrane rather than relying on interconnects. This innovative design permits a transition from the traditional thick interconnects with embedded gas channels to a more streamlined, thin, and flat architecture that maintains efficient gas distribution while reducing overall system bulk. The reported performance of 35 W at the SRU level and 330 W at the stack level in SOEC mode underscore the scalability and effectiveness of this novel approach, suggesting that such designs could start the way for more compact and energy-efficient SOC systems. Scope This work, based on corrugated geometry cells presented by A. Martos et. al. [7], introduces a novel 3D-printed cell design that incorporates an innovative sealing strategy able to operate the cell up to 5 bars in a vessel-free station, by combining the precision of additive manufacturing able to create complex shapes with a compressive sealing approach. This synergy not only enables the creation of complex cell architectures but also enhances the overall integrity of the sealing material, ensuring a robust and leak-tight assembly under operational conditions, 5 bar. This results in improved mechanical stability and enhanced electrochemical cell performance. This approach aims to be the first vessel-free SOC configuration able to be scaled up from cell design up to stack level. In parallel, a significant development in the experimental setup is the introduction of a pressure-vessel-free test station capable of characterizing from SRU up stacks. This custom-designed station has been engineered to evaluate 3D-printed SOCs at pressures of up to 5 bars without the use of a pressure vessel. By doing so, the system not only reduces experimental complexity but also minimizes thermal and mechanical losses typically associated with traditional high-pressure testing environments. Experimental methods 3YSZ samples were manufactured using stereolithography (SLA) with an industrial ceramic 3D printing system (CERAMAKER C900, 3DCERAM, FR). The parts were built by sequentially depositing and curing 25 μm-thick layers, defining the resolution in the z-direction, while the x-y resolution was determined by the laser spot size (~40 μm). A UV semiconductor laser with a characteristic wavelength of 355 nm was used for curing the slurries. The printed 3YSZ samples had a circular shape with an external diameter of 5.00 cm and a sealing frame with notches of varying spacing and width, from 1 cm to 300 µm, along with a thick support. Thermiculite 870 (Flexitallic) was used as a compressive sealant for the tests. To achieve these final dimensions after sintering, a rescaling process was applied to compensate for shrinkage during the sintering stage. Results To evaluate gas tightness at high pressure, the sealing performance of the printed 3YSZ samples was tested up to 5 bar. The design that demonstrated the best performance features a sealing frame of 15 mm with notches 300 µm wide and spaced 300 µm apart as shown in Figure 1. Leak rate measurements at room temperature using nitrogen and helium, to safely emulate hydrogen, revealed values of 0.1 sccm·cm⁻¹, equivalent to a 4 sccm leak rate at the cell level, and 0.15 sccm·cm⁻¹ , comparable to a 6 sccm leak rate at the cell level at 5 bars, as shown in Figure 2. The leak rate at the cell level represents less than 1% of the flow used under working conditions, aligning with data reported by SOC stack manufacturers. Similar measurements performed at the operating temperature of 850ºC enhanced sealing performance, particularly at high pressures between 3 and 5 bar. These results demonstrated the possibility of operating 3D-printed corrugated cells up to 5 bar in a vessel-free configuration. As our approach is based on a cell with enhanced mechanical properties and the use of compressive sealants, with no chemical bonds between the cell and the ceramic, the maximum pressure gradient a corrugated cell can sustain was evaluated. A breaking test was performed in order to know the differential pressure a corrugated 3D printed cell can withstand, as explained before the enhanced mechanical properties due to the geometry can increase the differential pressure the call can withstand. The test corresponds to slowly increasing the pressure till the membrane breaks and the pressure is released. As shown in Figure 3, our corrugated 3DPrinted cell, can hold a differential pressure of up to 1.6 bar before breaking, demonstrating the viability of our approach for high-pressure testing and the enhanced mechanical properties. Having proven the proposed 3Dprinted complex shape sealing design is suitable for SOC operation at 5 bar, an electrolyte-supported cell with a corrugated membrane and a high-pressure sealing frame was designed and successfully manufactured via 3D printing. Future work aims to test the manufactured cell in a vessel-free station at pressures up to 5 bar to further validate the viability of this approach under operating conditions and to evaluate the SOC performance in these conditions. Aswell wants to prove the potential of 3D printing as a breakthrough manufacturing technique to produce SOC electrolytes with complex shapes capable of operating at mid to high pressures without the use of pressure vessel. This study highlights the potential of 3D printing for fabricating high-pressure sealing frames, achieving leak rates of 4–6 sccm at 5 bar, corresponding to less than 1% of the working flow. Furthermore, testing at 850°C demonstrated enhanced sealing performance, validating the feasibility of operating 3D-printed corrugated cells at pressures up to 5 bar in a vessel-free configuration. 4o References [1] L. Bernadet, G. Gousseau, A. Chatroux, J. Laurencin, F. Mauvy, M. Reytier, Influence of pressure on solid oxide electrolysis cells investigated by experimental and modeling approach, Int. J. Hydrogen Energy 40 (2015) 12918–12928, https:// doi.org/10.1016/j.ijhydene.2015.07.099. [2] S.H. Jensen, X. Sun, S.D. Ebbesen, M. Chen, Pressurized operation of a planar solid oxide cell stack, Fuel Cell. 16 (2016) 205–218, https://doi.org/10.1002/ fuce.201500180. [3] Y. Wang, R. Zhan, Y. Qin, G. Zhang, Q. Du, K. Jiao, Three-dimensional modeling of pressure effect on operating characteristics and performance of solid oxide fuel cell, Int. J. Hydrogen Energy 43 (2018) 20059–20076, https://doi.org/10.1016/j. ijhydene.2018.09.025. [4] G. Sdanghi, G. Maranzana, A. Celzard, V. Fierro, Review of the current technologies and performances of hydrogen compression for stationary and automotive applications, Renew. Sustain. Energy Rev. 102 (2019) 150–170, https://doi.org/10.1016/j.rser.2018.11.028. [5] C. Grosselindemann, M. Dorn, F.M. Bauer, M. Seim, D. Ewald, D. Esau, M. Geörg, R. Rössler, A. Pundt, A. Weber, Pressurized single cell testing of solid oxide cells, Journal of Power Sources, Volume 614, 2024, 234963, https://doi.org/10.1016/j.jpowsour.2024.234963. [6] A. Pesce, A. Hornés, M. Núñez, A. Morata, M. Torrell, and A. Tarancón, “3D printing the next generation of enhanced solid oxide fuel and electrolysis cells,” J Mater Chem A Mater , vol. 8, no. 33, pp. 16926–16932, Sep. 2020, doi: 10.1039/d0ta02803g. [7] A.M. Martos, S. Márquez, R.S. Pavlov, W. Zambelli, S. Anelli, M. Nuñez, L. Bernadet, J.J. Brey, M. Torrell, A. Tarancón, “3D printing of reversible solid oxide cell stacks for efficient hydrogen production and power generation”, Journal of Power Sources, Vol 609, 2024, 234704 ,https://doi.org/10.1016/j.jpowsour.2024.234704. Figure 1

INTRODUCTION Our society’s heavy reliance on fossil fuels has led to severe environmental consequences, particularly the accumulation of greenhouse gases in the atmosphere, accelerating climate change. Transitioning to a low-carbon energy matrix is not only desirable but essential to mitigate the detrimental effects of global warming. Renewable energy sources such as wind and solar power have the potential to meet the global energy demand, but their intermittent nature requires the development of efficient energy storage and conversion technologies. In addition, the implementation of processes of carbon capture and storage (CCS) and carbon capture and utilisation (CCU) has proven to be an effective approach to reducing the existing atmospheric CO 2 levels, complimenting the transition to a sustainable energy system. [1–4] While CCS processes are oftentimes costly and complicated, and present the disadvantage of possible CO 2 leakages, CCU processes offer an interesting alternative by converting captured CO 2 into value-added chemicals using renewable external energy. Different strategies for CO 2 conversion have been investigated, including artificial photosynthesis, thermocatalytic reduction, electrochemical reduction and photochemical conversion. Among these, electrochemical reduction of CO 2 is especially attractive due to two main reasons: the possibility of controlling the process by adjusting the applied voltage and operation temperature, and the option of coupling it with renewable energy sources, hence contributing to a circular carbon energy cycle. [2,5] The existing electrolysis technologies play a crucial role in facilitating this energy transition and have been tested for CO 2 electroreduction [6]. Amongst them, Solid Oxide Electrolysis Cells (SOECs) are particularly promising due to their high efficiency, elevated temperature operation and potential industrial integration. Another important advantage over low-temperature electrolysers is their capacity to operate in co-electrolysis mode (co-SOEC), simultaneously reducing H 2 O and CO 2 mixtures to directly produce syngas (H 2 + CO, fuel side) and oxygen gas (oxygen side). [1,6,7] A key factor influencing the performance of SOECs (and co-SOECs) is the selection of electrode materials, particularly the oxygen electrode (anode), which plays a critical role in determining efficiency, stability, and durability. The anodic reaction, the Oxygen Evolution Reaction (OER), involves a complex four-electron transfer process, making anodic polarisation the dominant factor affecting cell performance. State-of-the-art (SoA) oxygen electrodes for SOECs are based on perovskite-structured oxides, particularly cobalt-containing materials, previously used in Solid Oxide Cell (SOC) technology due to their excellent electrocatalytic activity and mixed ionic-electronic conduction. Notable compositions include La 1−x Sr x Co 1−y Fe y O 3−δ (LSCF), Ba 1−x Sr x Co 1−y Fe y O 3−δ (BSCF) and La 1−x Sr x CoO 3−δ (LSC), often combined with good ionic conductors such as Y 2 O 3 -doped ZrO 2 (YSZ) or Ce 1-x Gd x O 2−δ (GDC) to enhance stability and oxygen ion transport. These composite electrodes help mitigate the formation of insulating phases, maintain structural integrity, and improve electrochemical performance. [4,8] However, the reliance on cobalt in these materials introduces significant challenges, including cost fluctuations, supply limitations, and environmental concerns related to cobalt extraction. Additionally, cobalt-based electrodes often suffer from phase instability and mechanical incompatibility, leading to performance degradation over time. These issues have driven ongoing research into alternative electrode materials with reduced or no cobalt content, aiming to balance high performance with improved long-term stability while minimising the use of critical raw materials. Recent advancements in Co-free oxygen electrode materials have demonstrated promising activity and durability, making them strong candidates for replacing conventional cobalt-based electrodes. [9] In this work, we present the Cu-doped lanthanum strontium ferrite La 0.6 Sr 0.4 Fe 0.8 Cu 0.2 O 3-δ ( LSFCu ) and the LSFCu-CeO 2 20 % (wt. %, LSFCu-20C ) perovskite-fluorite composite as novel cobalt-free oxygen electrodes. The preparation of these materials through a ‘one-pot’ synthesis method is presented, along with their structural characterisation and posterior evaluation as oxygen electrodes of SOC devices in co-SOEC conditions. EXPERIMENTAL The LSFCu and LSFCu-20C electrode materials were synthesised using a ‘one-pot’ auto-combustion method. In this case, ethylenediaminetetraacetic acid (EDTA) served as both the organic fuel and chelating agent, while ammonium nitrate (NH 4 NO 3 ) acted as a combustion promoter. Aqueous solutions of metal nitrates were prepared in stoichiometric ratios according to the target composition. This solution was then combined with a pH=10 solution containing EDTA (>99.4%, Sigma-Aldrich) and NH 4 NO 3 (>99.0%, Sigma-Aldrich) in a 1:3 ratio. The mixture was heated on a hot plate until the formation of a gel, which self-ignites yielding a dark brown, sponge-like powder. The powder was ground using an agate mortar and calcined in air at 850 °C for 6 hours to obtain the final electrode materials. Details of the synthesis can be found elsewhere. [10] X-ray powder diffraction (XRD) was used to characterise the crystalline structure of the powders. XRD patterns were acquired in the 2θ=20-80° range in 0.04° steps with 1 s/step (at room temperature) with a Bruker D8 Advance diffractometer (280 mm goniometer radius) in Bragg-Brentano geometry and with CuKα sealed-tube radiation (λ=1.5418 Å) operating at 40 kV and 40 mA. A Lynxeye 1D detector was used for data collection. Scanning Electron Microscopy (SEM) micrographs were obtained using a Zeiss Auriga microscope (Germany) in the 1.5-20 kV energy range and SE2, InLens (SE detector), and BSE detectors. Full-cell devices were prepared by depositing a ~500 nm GDC barrier layer (by Pulsed Layer Deposition) on top of the electrolyte of a fuel-electrode-supported half-cell NiO-YSZ|YSZ. Terpineol-based inks of LSFCu and LSFCu-20C electrodes were prepared and brush-painted on top of the electrolyte and sintered at 950 °C for 4 h (determined in previous steps of the study [11]). The active area of the deposited oxygen electrodes was ~2.0 cm². The electrochemical characterisation of the cells was performed in a commercial ProboStat™ (NorECs AS) test station placed inside a vertical tubular furnace. Gold mesh/paste and nickel mesh/paste were used to collect the current on the oxygen and fuel sides, respectively. Ceramabond™ 552 (Aremco) was applied to the edges of the cells to ensure gas tightness between the oxygen and fuel chambers. Current density-voltage (V-I) curves of the full cells under different operating conditions were carried out using a Maynuo M9812 electronic load and a Velleman LABPS3005D power source (to compensate for voltage losses). Electrochemical Impedance Spectroscopy (EIS) measurements of full cells were registered with a potentiostat PARSTAT® 2273 (PAR Instruments) in galvanostatic mode with a 50 mA amplitude in the 10 5 -10 -1 Hz frequency range, at OCV and 1200 mV. The measurements were performed in SOEC and co-SOEC mode in the 720-820 ºC temperature range. The fuel side was supplied with a 65:25:10 mixture of H 2 O:CO 2 :H 2 (45 mL min -1 cm -2 H 2 O, 17.3 mL min -1 cm -2 CO 2 and 7 mL min -1 cm -2 H 2 ). An air flow of 100 mL min -1 cm -2 was delivered to the oxygen electrode side. RESULTS AND DISCUSSION The composition of the powders obtained from the auto-combustion route was assessed by XRD. The collected XRD patterns are shown in Figure 1 . This confirmed the presence of a single perovskite phase in the pure sample that corresponds to the LSFCu material; and two phases, the LSFCu perovskite and CeO 2 fluorite, for the LSFCu-20C composite material. Fit of the data through the Rietveld method was used to quantify the weight percentages of the phases in the LSFCu-20C. The results, 80.7 % of LSFCu and 19.3 % of CeO 2 , agree with the expected values considering the method’s accuracy. No impurities or secondary phases were observed, confirming that the chosen method allowed us to obtain the desired materials, a perovskite and a composite, in two steps: a simple combustion synthesis plus an additional calcination step. The powder morphology and distribution of the phases along the LSFCu-20C composite sample were analysed employing electronic microscopy. Figure 2 displays the micrographs obtained for the LSFCu-20C sample. Figure 2a shows the porous microstructure of the material in its powder form. Figure 2b presents a micrograph of the LSFCu-20C oxygen electrode deposited in a half-cell, captured with a BSE detector. The image reveals larger particles corresponding to LSFCu (dark phase) and smaller CeO 2 particles (bright phase). Their distribution appears uniform across the sample, with intimate contact between the two phases. However, ongoing investigations are assessing potential cationic interdiffusion between the phases, which could result in a complex doped material with stoichiometries differing from the nominal composition stated here. After the structural and morphological characterisation, the electrochemical characterisation of the oxygen electrode materials for Solid Oxide Cells is here presented. The performance of the materials as oxygen electrodes for SOC devices working under co-SOEC conditions was evaluated through polarisation curves and EIS measurements. Figure 3 exhibits the voltage-current density (V-I) curves for the LSFCu and LSFCu-20C compounds at 820 °C. First, the displayed Open Circuit Voltage (OCV) values of ~0.85 V agree with the theoretical value expected for the utilised partial pressures and temperature. Moving on to their performance, high current densities of 0.93 A cm -2 and 1.53 A cm -2 were achieved at 1.3 V for the LSFCu and LSFCu-20C electrodes, respectively. This shows a huge increase (60%) in performance given by the CeO 2 addition. EIS measurements under bias (1.2 V), shown as insets of Figure 3 , further confirm these results. In them, a clear reduction in the polarisation resistance can be appreciated. Moreover, the difference in serial resistance observed could be owed to the fact that the LSFCu-20C composite has a better attachment to the GDC barrier layer. In summary, both materials achieved high current densities, demonstrating their potential as oxygen electrodes for co-electrolysis applications. Furthermore, the LSFCu-20C material outperformed pure LSFCu under co-SOEC conditions, suggesting that CeO 2 addition enhances the MIEC behaviour of the electrode leading to improved performance. REFERENCES [1] A. Hauch, R. Küngas, P. Blennow, A.B. Hansen, J.B. Hansen, B. V. Mathiesen, M.B. Mogensen, Recent advances in solid oxide cell technology for electrolysis, Science (1979) 370 (2020). https://doi.org/10.1126/science.aba6118. [2] Y. Song, X. Zhang, K. Xie, G. Wang, X. Bao, High-Temperature CO2 Electrolysis in Solid Oxide Electrolysis Cells: Developments, Challenges, and Prospects, Advanced Materials 31 (2019) 1–18. https://doi.org/10.1002/adma.201902033. [3] Y. Zheng, J. Wang, B. Yu, W. Zhang, J. Chen, J. Qiao, J. Zhang, A review of high temperature co-electrolysis of H2O and CO2 to produce sustainable fuels using solid oxide electrolysis cells (SOECs): Advanced materials and technology, Chem Soc Rev 46 (2017) 1427–1463. https://doi.org/10.1039/c6cs00403b. [4] S. Anelli, F. Baiutti, A. Hornés, L. Bernadet, M. Torrell, A. Tarancón, Improved mesostructured oxygen electrodes for highly performing solid oxide cells for co-electrolysis of steam and carbon dioxide, J Mater Chem A Mater 7 (2019) 27458–27468. https://doi.org/10.1039/c9ta07373f. [5] R.J. Lim, M. Xie, M.A. Sk, J.M. Lee, A. Fisher, X. Wang, K.H. Lim, A review on the electrochemical reduction of CO2 in fuel cells, metal electrodes and molecular catalysts, Catal Today 233 (2014) 169–180. https://doi.org/10.1016/j.cattod.2013.11.037. [6] R. Küngas, Review—Electrochemical CO 2 Reduction for CO Production: Comparison of Low- and High-Temperature Electrolysis Technologies , J Electrochem Soc 167 (2020) 044508. https://doi.org/10.1149/1945-7111/ab7099. [7] S. Anelli, E. Hernández, L. Bernadet, X. Sun, A. Hagen, F. Baiutti, M. Torrell, A. Tarancón, Co-electrolysis of steam and carbon dioxide in large area solid oxide cells based on infiltrated mesoporous oxygen electrodes, J Power Sources 478 (2020). https://doi.org/10.1016/j.jpowsour.2020.228774. [8] L. Bernadet, C. Moncasi, M. Torrell, A. Tarancón, High-performing electrolyte-supported symmetrical solid oxide electrolysis cells operating under steam electrolysis and co-electrolysis modes, Int J Hydrogen Energy 45 (2020) 14208–14217. https://doi.org/10.1016/j.ijhydene.2020.03.144. [9] U. Draz, E. Di Bartolomeo, A.P. Panunzi, U. Pasqual Laverdura, N. Lisi, R. Chierchia, L. Duranti, Copper-Enhanced CO2 Electroreduction in SOECs, ACS Appl Mater Interfaces (2024) 8842–8852. https://doi.org/10.1021/acsami.3c17766. [10] N. Di Benedetto, C. De los Santos, M. Del Pilar Yeste, J. Morais, M. Do Carmo Martins Alves, A. Amaya, L. Suescun, J.M. Gatica, H. Vidal, J. Castiglioni, Influence of the Thermal Processing and Doping on LaMnO3 and La0.8A0.2MnO3 (A = Ca, Sr, Ba) Perovskites Prepared by Auto-Combustion for Removal of VOCs, Catalysts 12 (2022) 865. https://doi.org/10.3390/catal12080865. [11] N. Di Benedetto Sviridenko, Development of ion-conducting ceramics for reversible Solid Oxide Cells, Master, Facultad de Química, Universidad de la República/ PEDECIBA Química, 2022. Figure 1

Ceramic materials are key in energy technologies such as solid oxide cells or all-solid-state batteries. Recent advances in 3D-printing have pushed their potential, enabling unprecedented complex and customizable geometries. However, 3D-printing of ceramics involves remarkably long heat treatments, which limit their implementation. In this work, ultrafast high-temperature sintering was successfully employed to develop 3D-printed solid oxide electrolytes treated in less than 15 min, for the first time. The optimal sintering conditions resulted in > 96 % densification preserving structural integrity. Despite the presence of intragranular porosity, ascribed to the non-equilibrium conditions of the process, the final ionic conductivity remained within the expected range for 8YSZ. Additionally, the complete UHS 3D-printed electrolyte-supported cell demonstrated a peak power density exceeding 0.5 Wcm(-2) at 900 degrees C, surpassing previously reported performances of similar systems. This highlights the potential of UHS as a final ceramic processing method to obtain highly densified and conductive materials with full functionality.

This work presents the implementation of ceramic stereolithography 3D printing to generate catalytic supports to investigate the influence of the structured reactor design on its conversion efficiency for CO2 methanation. Alumina monolithic supports were fabricated by stereolithography using a non-linear channel geometry formed by an array of twisted elements, which was compared to the conventional monolith design. The catalytic performance of the 3D printed monoliths, functionalized with Ni as a catalyst material, was evaluated and complemented by CFD simulation, showing the strong correlation between the support design selection and CO2 conversion rates. A maximum CO2 conversion of 84 % at 400 degrees C was achieved owing to the three-dimensional monolith design, which increased the catalytic activity of the system under high gas flow rates by creating a nonuniform reactant flow distribution with higher turbulence kinetic energy. Therefore, this work demonstrates the potential of ceramic 3D printing technologies to boost the catalytic device efficiency by implementing novel designs, not reproducible by conventional ceramic manufacturing approaches.

Solid Oxide Cells excel as energy conversion devices have demonstrated high efficiency in power generation as fuel cells and energy storage through electrolysis. One of the most concerning topics on SOC field on electrolyte supported cell (ESC) is reducing the thickness of the electrolyte to minimize and the associated serial resistance. Conventionally, the fabrication of this multi-layer ceramic device involves advanced manufacturing processes like tape casting and screen-printing. Recently, electrolyte-supported Solid Oxide Cells have been recently started to be manufactured using ceramic 3D printing techniques, enabling the creation of distinctive geometries with previously unexplored possibilities on functional ceramics. In this work, stereolithography 3D printing of yttria-stabilized zirconia (YSZ) was used to fabricate thin planar SOC electrolytes for electrolyte supported cells achieving thickness up to 30um on button cells. For their scaling up, nerve structured architectures were added to electrolyte membranes by the vast possibilities of SLA 3D printing. The Nerve interface engineering is used to thin some parts of the cell, reducing the average thickness, improving the electrochemical properties while improving the mechanical robustness of the cell (Fig1.). Full cell electrochemical characterization of the here developed electrolyte-supported solid oxide cells was carried out through I–V polarization curves, obtaining a maximum current density of 198mA/cm 2 in and 152mA/cm 2 in SOFC and SOEC mode respectively at 750ºC and electrochemical impedance spectroscopy (EIS), obtaining a minimum serial resistance (ASRs) of 1 Ωcm 2 at 750ºC Introduction Solid oxide fuel cells (SOFCs) are highly efficient, zero-emission power generators that convert hydrogen into electricity, making them one of the most effective energy generation technologies available today. When operated in reverse mode, these devices function as energy storage systems, producing storable hydrogen from electricity and water. Known as solid oxide electrolysis cells (SOECs), they offer a highly efficient method for energy conversion. Solid oxide cells (SOCs) are multilayer electrochemical devices with a ceramic-based structure. They feature a dense oxide-ion-conducting electrolyte sandwiched between two electrodes. The state-of-the-art materials for SOCs include yttria-stabilized zirconia (YSZ) as the electrolyte, with electrode compositions based on YSZ composites—lanthanum strontium manganite (LSM-YSZ) for the oxygen electrode and nickel–YSZ (Ni–YSZ) for the fuel electrode. Electrolyte-supported cells (ESC) and fuel electrode-supported cells (FESC) are classified based on their supporting layer. Regardless of the cell configuration, their fabrication follows a multi-step shaping process using conventional functional manufacturing techniques such as tape casting and screen printing. However, innovative methods incorporating alternative techniques such as spin coating, pulsed laser deposition, inkjet printing, infiltration, binder jetting among others have also been explored 4 . Notably, additive manufacturing and 3D printing of ceramics have recently demonstrated their potential for producing highly complex functional ceramic components with excellent mechanical and electrochemical properties 2 . It has been shown that intricate geometries and surface modifications of the electrolyte can enhance thermomechanical stability, enabling a reduction in membrane thickness. In addition to offering greater design flexibility, 3D printing significantly reduces material waste—an important factor when working with functional ceramic materials. It also provides a time- and cost-efficient alternative to traditional ceramic manufacturing, particularly for applications such as SOFCs and SOECs. Recent studies have further demonstrated the benefits of leveraging geometric patterns, made possible by the design freedom of additive manufacturing, to enhance volumetric current density, especially in critical areas. Among the various 3D printing techniques, stereolithography (SLA) has emerged as a promising approach for producing functional ceramic-based materials for energy applications. 5,6 Through additive manufacturing, the resulting electrolytes were thicker than those produced using conventional techniques. This has been one of the primary drawbacks of the technology, as a thinner electrolyte corresponds to lower serial resistance and higher peak power density. First, Masciandaro et al. printed 300μm-thick self-supported 3YSZ flat and complex shaped electrolytes of 1.54cm 2 area to demonstrate the suitability of SLA to generate electrolytes for SOC applications. The cells showed electrochemical serial resistance of 4Ωcm 2 and peak power density of 60mW at 800◦C. 1 In another study, Celika et al. achieved 75um 3YSZ electrolytes with a 40x40mm conventional tape casting technique and additionally 25um in a 24.15% of the active area by cutting patterns in the electrolyte active region. Resulting as serial resistance of 1.95Ωcm 2 and 2.25Ωcm 2 for patterned and planar electrolyte respectively. Nevertheless, SLA showed the potential to improve SOC performance by overcoming the geometrical constraints of conventional ceramic production processes. 3 In this work, stereolithography 3D printing of yttria-stabilized zirconia (3YSZ) was used to fabricate thin planar SOC electrolytes for electrolyte supported SOC cells with thickness of up to 30um with a serial resistance 0.45Ωcm 2 for 750ºC. For the scaling up of this technique, nerve structure architectures were added to the previous electrolyte thanks to the vast possibilities of 3D printing. The Nerve interface engineering is used to thin some parts of the cell keeping the electrochemical properties while keeping mechanical robustness of the cell. The resulting 3YSZ nerve patterned have less than 45um mean thickness. This 3D printed novel electrolyte design was scaled up for fuel cell measurements to 50x50mm active area, obtaining a less than 80um mean thickness electrolyte with a performance of 120mW at 750◦C. Demonstrating that by 3D Printing techniques electrolyte thickness similar to the State of the art can be achieved, and consequently comparable efficiencies to conventional techniques, while presenting the already commented advantages of 3D Printing. Methodology 3YSZ electrolytes were manufactured using stereolithography (SLA) with an industrial ceramic 3D printing system (CERAMAKER C900, 3DCERAM, FR). The parts were built by sequentially depositing and curing 25 μm-thick layers, defining the resolution in the z-direction, while the x-y resolution was determined by the laser spot size (~50 μm). A UV semiconductor laser with a characteristic wavelength of 355 nm was used for curing the slurries. The printed button-cell membranes had a circular shape with a diameter of 2.00 cm, an active area of 1.75 cm². To achieve these final dimensions after sintering, a rescaling process was applied to compensate for shrinkage during the sintering stage. For the fabrication of nerve-patterned solid oxide cells, a rib structure with a height of 30 μm and a width of 180 μm was incorporated into the electrolyte CAD design. Large-area samples featured a nerve-patterned structure, were square-shaped (8 × 8 cm), and had an active area of 25 cm². Sintered 3YSZ electrolytes have been functionalized for fuel cell application by painting commercial electrode materials (FuelCell Materials) of LSM-YSZ, for the oxygen electrode. And by a self-made thermo-curable ink with ceramic loading of NiO-YSZ for the fuel electrode. The NiO-YSZ painted electrode layer was sintered in air at 1450◦C for 2 h, while the YSZ-LSM (FuelCell Materials) layers were attached at 1200◦C for 2 h, at a heating and cooling rate of 2◦C/min. Symmetrical characterization of the electrolytes was carried out by the application of LSM-YSZ in both sides of the electrolyte and gold ink to ensure electrical contact. Button cells were electrochemically tested in both fuel cell and electrolysis modes using a ProboStat™ system (NOR-ECS, Norway) within a temperature range of 700–900 °C. Their electrochemical performance was assessed through I–V polarization curves and electrochemical impedance spectroscopy (EIS). Measurements were conducted using a potentiostat/galvanostat and a frequency response analyzer (Parstat 2273, PAR, USA) over a frequency range of 500 mHz to 1 MHz, with an amplitude of 100 mV under open-circuit voltage (OCV) and a bias of 0.7 V as operating conditions. Large-area solid oxide cell was characterized using a custom-built electrochemical test bench with controlled temperature and atmosphere. The setup included a DC power supply (EA-PSI 9080–60T) and electronic loads (TrueData Load – FuelCon), enabling cell testing under different operating modes (SOFC and SOEC). The performance was evaluated through I–V polarization curves. Morphological and microstructural characterization was carried out using a Scanning Electron Microscope (SEM) (AURIGA, ZEISS, Germany) and optical microscopy with a PLu Neox 3D Optical Profiler (SENSOFAR, Spain) confocal microscope. Results and discussion Flat and nerve-patterned 3YSZ freestanding membranes were successfully fabricated using SLA 3D printing, followed by high-temperature sintering. Although the nerve pattern is barely visible to the naked eye (Fig.2a), surface topography analysis using confocal imaging (Fig. 2b) provides a detailed view of the printed structure, revealing a nerve height of 20 μm, a width of 185 μm, and a pitch of 130 μm. SEM cross-sectional images (Fig. 2c) show that the thickness of 34 μm in the planar area, while the nerve area of the electrolyte has a thickness of 52 μm. The pitch between nerves is 135 μm, and the width is 190 μm, consistent with the confocal imaging results. The patterned electrolyte layer itself has a thickness of 34 μm, with the nerves reaching a height of 23 μm. For fuel cell measurements this design was thickened to a flat and nerved button cells of 60um electrolyte layer. Nerves were thickened to 30um approximately for the patterned design, resulting the mean thickness of the patterned electrolyte 80um. This electrolyte, was scaled up to a squared cell of 50x50mm of active area (Fig. 3) SOFC and SOEC mode results at 750ºC are shown in Fig4. IV polarization curves for flat cell design and nerve patterned design are shown in Fig. 4a and 4b. EIS results for the two button cell designs are shown in Fig. 4c and Fig.4d. SOFC IV (Fig4.a) show a similar current density for both designs achieving almost 200mA/cm 2 at 0.6V with a peak power of 120mW/cm 2 . In SOFC EIS (Fig4.c) it can be seen that serial resistance is lower for the flat design (1Ωcm 2 ) than the nerved (1,27Ωcm 2 ) as expected due to lower mean electrolyte thickness. This is consistent with SOEC EIS (Fig4. d) in which serial resistances present the same values. For the SOEC IV (Fig.4 b), flat cell has a higher current density being 152mA/cm 2 for the flat cell and 108mA/cm 2 for the nerve patterned. Regarding IV polarization curves and EIS of the large, area results will be shown in the near future. Conclusions Our findings confirm that SOC electrolyte membranes can be fabricated by SLA 3D printing achieving thicknesses comparable to those achieved using state-of-the-art techniques (75 μm), and importantly, this can be accomplished on large scale stackable cells. This progress highlights the potential of ceramic 3D printing to become an increasingly viable and competitive alternative to conventional manufacturing methods due to these advantages on complex shape and waste material among others. As this technology continues to evolve, improvements in precision, scalability, and material properties will further enhance its adoption in industrial and high-performance applications. References [1] Three-dimensional printed yttria-stabilized zirconia self-supported electrolytes for solid oxide fuel cell applications. S. Masciandaro, et al. Journal of the European Ceramic Society, 2019. [2] Large-area 3D printed electrolyte-supported reversible solid oxide cells. M. Lira, et.al. Electrochimica Acta 467 (2023) [3] Mechanical and electrochemical behavior of novel electrolytes based on partially stabilized zirconia for solid oxide fuel cells. Selahattin Celik, et al. Ceramics International41(2015)8785–8790 [4] 3D printing the next generation of enhanced sòlid oxide fuel and electrolysis cells. Arianna Pesce, et. al. J. Mater. Chem. A, 2020, 8,16926 [5] 3D printed electrolyte-supported solid oxide cells based on Ytterbium-doped scandia-stabilized zirconia. S. Márquez et. al. J. Phys. Energy 6 (2024) 015016 [6] 2022 roadmap on 3D printing for energy. A.Tarancón et. al. J. Phys. Energy 4 (2022) 011501 Figure 1

The use of reversible solid oxide cells (rSOC) as bi-directional Power-to-Gas (P2G) and Gas-to-Power (G2P) devices in microgrids with renewable energy sources has attracted considerable attention in the last years. The present study analyzes the energy management of a rSOC connected in a microgrid, considering hydrogen prices from the European HYDRIX market and electricity prices and demands from the Spanish electrical grid. The energy management strategy, based on model predictive control, determines the optimal path for transitions between SOE and SOFC according to the market. The strategy relies on a model including experimental rSOC transition times, thermal effects, and safety constraints to avoid undesired mode switching. The study was conducted in a scaled grid-connected system including 10 kW solar and wind renewable generation and a rSOC of 4.2-6 kW (SOFC-SOE). The aim is to assess the impact of different renewable energy sources on the performance of rSOC and on the resulting economic balance. The results show that an energy management strategy considering hydrogen markets can reach higher revenue, with increases of approximate to 4.6% for solar and approximate to 14.1% for wind, compared to existing algorithms based solely on electricity prices.

Solid oxide cells (SOCs) utilizing mixed ionic-electronic conductors often face performance limitations due to undesired reactions with conventional stabilized-zirconia electrolytes. Ceria-based diffusion barrier layers mitigate these reactions, enhancing electrode activity and durability. Recently, physical thin-film methods have enabled sub-micrometer barrier layers with significantly improved performance compared to traditional methods. However, scalability and cost-effectiveness remain key constraints for commercial SOCs. In this work, we developed a gadolinium-doped ceria (GDC) diffusion barrier layer by magnetron sputtering at room temperature, followed by a novel rapid thermal processing (RTP) sintering approach. This method produced a dense submicrometer GDC layer on anode-supported half-cells. Time and energy consumption were significantly reduced compared to conventional processes. Structural, morphological, compositional, and electrochemical characterizations were performed to evaluate quality and performance. Tests on button cells showed >30 % performance improvement over reference cells with state-of-the-art porous barrier layers, with power outputs of 1.26 W cm(-2) at 0.7 V in fuel cell mode and 1.54 A cm(-2) at 1.3 V in electrolysis mode at 750 degrees C. When scaled to large-area cells (12 x 8 cm(2)) in short stacks, RTP-treated cells achieved up to 60 % improvement in fuel cell and 30 % in electrolysis at 650 degrees C. This approach provides a viable route for large-scale production of high-performance SOCs.

3D printing is revolutionizing manufacturing, particularly in fields where complex shapes offer significant advantages, such as catalysis. This study demonstrates the potential of the ceramic-based additive manufacturing for producing catalytic beds for CO2 methanation. In particular, it demonstrates the effectiveness of alumina catalytic beds with flat channels, fabricated via stereolithography, within the temperature range of 260 - 340 degrees C. 3D-printed beds show a 20 % performance increase compared to stainless-steel catalytic supports made through conventional milling and selective laser sintering. This research introduces a novel approach to produce catalytic materials, combining the advantages of additive manufacturing with the selection of materials that have optimal catalytic properties. Additionally, the 3D structuring of channels with a herringbone pattern further improves CO2 conversion by 15 % at 300 degrees C, due to an increase of the functional area and enhanced flow distribution along the channel. Overall, this study paves the way for further advancements by incorporating advanced features into catalytic beds employing ceramic 3D printing technologies.

Renewable hydrogen offers a promising pathway to address the challenge of large-scale chemical energy storage in the transition to a decarbonized future. The most efficient devices to convert renewable electricity into hydrogen, and vice versa, are reversible solid oxide cells (SOC-s). Despite recent advances in materials performance and durability, conventional ceramic manufacturing technologies strongly limit the huge potential of SOC-s, imposing severe geometrical restrictions that penalize the overall system efficiency. Here we capture the benefits of using previously unexplored complex-shapes by scaling 3D-printed reversible solid oxide cells with improved mechanical properties, higher performance, and embedded functionality. Stacks made of 45 cm2-3D-printed electrolyte-supported solid oxide cells combined with ultrathin flat metallic interconnects were successfully fabricated and operated in fuel cell (SOFC) and electrolysis (SOEC) modes delivering up to 85 L/h of hydrogen production while presenting less than 5 % degradation after more than 500 h of operation. The advances presented here demonstrate the viability of upscaling the process of solid-oxide-cell 3D printing and brings advantageous stack designs aimed for a cost-competitive and customizable hydrogen technologies deployment. In particular, the enhancement by design achieved here provides innovative SOC stacks with volumetric and gravimetric power densities that are three and four times higher, respectively, than their planar counterparts using the same set of materials.

Power-to-Liquid processes have the potential to decarbonize maritime transport by producing carbon–neutral electro-fuels. One example of a potential implementation of this process is the combined technology of co-electrolysis of carbon dioxide and water, along with Fischer–Tropsch Synthesis. Given the promising prospects of producing electro-fuels to achieve net-zero objectives by 2050, a critical question that arises is whether sufficient resources are available to replace the current demand for fossil marine gas oil (MGO). This study evaluates the requirements and availability of resources necessary for producing marine electro-fuel using the MGO demand at the Port of Barcelona as a case study. The results indicate that current supplies of renewable energy and biogenic CO2 are insufficient to fully replace the total fossil MGO demand. However, by 2050, it is expected that these resource limitations will be overcome, considering the current official projections for the growth of renewable electricity and the biogas industry. The deployment of renewable electricity generation and the rollout of biomethane industrial network as biogenic carbon source is found to be essential for the viability of the future substitution of fossil MGO with its electro-fuel equivalent

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The application of additive manufacturing technologies for the fabrication of functional ceramics has exhibited extraordinary potential for revolutionizing conventional manufacturing routes of electrochemical energy generators. The incorporation of 3D printing into the production strategy of Solid Oxide Cells (SOCs) allows their geometrical complexity to be increased through the hierarchical design of the systems, while simultaneously optimizing the ceramic manufacturing process, minimizing the upfront investment, and augmenting the manufacturing efficiency owing to the reduction in production steps. In this regard, the elaboration of multi-material 3D printing for the fabrication of entire SOC devices is required to achieve a fully automated production process. The current work presents and discusses the main technological and material challenges for the development of self-supported Solid Oxide Fuel Cells (SOFCs) fabricated in a single step by using hybrid multi-material 3D printing. The results on the fabrication of complete self-supported SOFCs are here presented with special attention to the most critical steps: the hybridization of stereolithography and robocasting 3D printing technologies and the co-sintering of a multilayered ceramic device. The electrochemical characterization of the printed and co-sintered cells validates the innovative approach, reaching a remarkable maximum power density above 250 mW cm-2 at 950 degrees C. This result, together with the developed hybrid technology, represents a step forward for further digitalization of the functional ceramic device manufacturing, more specifically, the SOC manufacturing process, leading to the fabrication of fully 3D printed monolithic SOFC stacks. The capabilities of hybrid multi-material additive manufacturing to produce entire self-standing SOFC devices have been proved in just two stages, 3D printing and co-sintering.

Solid oxide cells (SOC) are an efficient and cost-effective energy conversion technology able to operate reversibly in fuel cell and electrolysis mode. Electrolyte-supported SOC have been recently fabricated employing 3D printing to generate unique geometries with never-explored capabilities. However, the use of the state-of-the-art electrolyte based on yttria-stabilized zirconia limits the current performance of such printed devices due to a limited oxide-ion conductivity. In the last years, alternative electrolytes such as scandia-stabilized zirconia (ScSZ) became more popular to increase the performance of electrolyte-supported cells. In this work, stereolithography 3D printing of Ytterbium-doped ScSZ was developed to fabricate SOC with planar and corrugated architectures. Symmetrical and full cells with about 250 μ m- thick electrolytes were fabricated and electrochemically characterized using impedance spectroscopy and galvanostatic studies. Maximum power density of 500 mW cm ^−2 in fuel cell mode and an injected current of 1 A cm ^−2 at 1.3 V in electrolysis mode, both measured at 900 °C, were obtained demonstrating the feasibility of 3D printing for the fabrication of high-performance electrolyte-supported SOC. This, together with excellent stability proved for more than 350 h of operation, opens a new scenario for using complex-shaped SOC in real applications.

Developing cost-effective and durable interconnects for solid oxide cells is crucial to overcome currently existing barriers for the commercialization of this promising energy technology. A systematic microstructural and electrical characterization of MnCo2O4 spinel coatings processed by electrophoretic deposition on SUS 445 ferritic stainless steel, manufactured through powder metallurgy, is here reviewed and discussed for application in high temperature solid oxide cells stacks. The work presents a successful combination of the powder metallurgy processing of metallic interconnects with the electrophoretic deposition as a fast and versatile approach to coat complex interconnect shapes. Therefore, this study assesses the effect of the sintering route of coated steel on the final microstructure. Remarkable results in terms of electrical properties are here presented for EPD coated sample reduced at 1000 °C and re-oxidised at 800 °C in static air, obtaining an area specific resistance degradation rate of 1.2 mΩ cm2/kh together with an effective limitation of Cr outward diffusion despite the prolonged exposure in relevant conditions. This novel approach opens the door for a new class of complex-shaped interconnects with enhanced performance and durability and excellent scalability at a low cost.

Solid oxide electrolysis cells are ceramic multilayer devices based on crystalline oxides with ionic and mixed ionic-electronic properties. Due to their ceramic nature, strong shape limitations have to be considered since conventional manufacturing methods for multilayer ceramics are based on tape casting, screen printing, extrusion, or dip coating, which ultimately result in planar or tubular geometries.

Solid Oxide Cells are highly efficient energy conversion devices for power generation, in fuel cell mode, and energy storage, in electrolysis mode. This multi-layer ceramic device is currently fabricated with state-of-the-art manufacturing processes such as tape casting and screen-printing. Alternatively, ceramic 3D printing technologies such as stereolithography or robocasting have demonstrated their potential to fabricate enhanced electrochemical cells by employing an additive manufacturing approach able to create complex shapes, hierarchical structures or improved interfaces by design while reducing the amount of waste material. In this work, large-area solid oxide cells of 25 cm2 (16 cm2 of active area) were fabricated by 3D-printing electrolyte supports made of yttria-stabilized zirconia combined with composite electrodes based on nickel and lanthanum strontium manganite for the fuel and oxygen electrodes, respectively. Electrochemical characterization of such electrolyte-supported solid oxide cells was carried out in fuel cell and electrolysis modes. In fuel cell operation mode, a maximum power of 3.5 W (corresponding to a peak power density of 220 mW/cm2) was measured at 950°C while in electrolysis mode, the cell was able to operate at 7.3W with a maximum injected current of -5.6 A at 1.3V (corresponding to 340 mA/cm2). A galvanostatic degradation test carried out at 900°C over 1150h in SOFC mode proved a remarkable low degradation rate of 11 mV kh−1 confirming the robustness of the cell produced by 3D printing and the interest of further exploiting the advantages of improvements generated by design.