High-performance Solid Oxide Research Articles

Investigation of plasma sprayed Sr0·7La0·3TiO3 / La0·2Sr0·8MnO3 Bi-layer interconnector performance and its application in high power tubular solid oxide fuel cells

Atmospheric plasma spraying (APS) has been demonstrated as an efficient and rapid method for manufacturing high-performance solid oxide fuel cells (SOFCs), with interconnects serving as the “wires” for large-scale integration of SOFCs. However, the challenge of producing highly conductive and stable interconnects through plasma spraying remains unresolved. This study developed a Bi-layer perovskite interconnect for segmented-in-series solid oxide fuel cell (SIS–SOFCs). It involved APS-prepared dense N-type interconnects of Sr0·7La0·3TiO3 (LST), achieving low porosity, low leakage rate, and high conductivity LST coatings. The element of Ti valence state changes and conductivity of LST powders, hydrogen-treated powders, LST coatings, and hydrogen-treated coatings were quantitatively analyzed through phase detection and elemental valence state analysis under different oxygen partial pressure conditions to explore the variation of LST coating conductivity. Simultaneously, bi-layer interconnector model using La0·2Sr0·8MnO3(LSM)as the P-type interconnect was established to elucidate the electron transport mechanism within the Bi-layer interconnect under operating conditions and propose optimization schemes for the structural design of tubular serial-connected cell interconnects. The tubular dual-cell combination using LST/LSM Bi-layer interconnectors exhibited a maximum power density of 360 mW/cm2 at 800 °C, with only 33% interconnector loss compared to the maximum power density of 540 mW/cm2 achieved by a single cell at 800 °C. Additionally, it attained the highest open circuit voltage (1.9 V) at 650 °C. This Bi-layer interconnectors has been successfully applied in serial-connected tubular cells with more than 5 cells. Furthermore, the dual-cell combination showed almost no performance loss under 100 h of constant current discharge (0.3 A/cm2) testing. These research findings indicate that the LST/LSM Bi-layer interconnectors prepared using atmospheric plasma spraying is an ideal material system for the functional layer of interconnects in high-power tubular segmented-in-series solid oxide fuel cell structures.

Praseodymium-Cerium Oxide-Infiltrated Perovskite Cathode with Superior Electrochemical Performance for Solid Oxide Fuel Cells.

This study presents a high-performance solid oxide fuel cell employing a perovskite cathode, strontium iron molybdenum oxide [Sr2Fe1.5Mo0.5O6-δ (SFM)], infiltrated with praseodymium-cerium oxide [Pr0.2Ce0.8O2-δ (PCO)], a fluorite. This infiltration notably enhances the oxygen reduction reaction kinetics and long-term stability. Evidence of enhanced stability is seen through minimized impedance degradation over 50 h. Furthermore, PCO infiltration improves the cathode's resistance to chromium poisoning by suppressing strontium degradation. Compared to the bare SFM cathode, the PCO-infiltrated SFM composite cathode doubles the cell's power density at 800 °C.

Construction of more oxygen vacancies of BaCo0.4Fe0.4Zr0.2O3-δ for high-performance proton-conducting solid oxide fuel cell cathodes

The cathodic catalytic activity for the oxygen reduction reaction (ORR) plays a critical role in determining the performance of proton-conducting solid oxide fuel cells (P-SOFCs). BaCo0.4Fe0.4Zr0.2O3-δ (BCFZ) has emerged as a promising cathode for P-SOFCs due to its triple-phase conductivity. Nevertheless, its suboptimal proton conductivity and hydration ability at intermediate temperatures prevent it from achieving the anticipated ORR catalytic activity. To address these limitations, this study explores the enhancement of electrocatalytic activity in BCFZ through alkali metal doping and A-site defect construction. The effects of such modifications on oxygen surface exchange kinetics and ORR catalytic activity are systematically investigated. The findings reveal that BCFZ exhibits relatively low parameters in terms of electronic conductivity, oxygen ion conductivity, oxygen vacancy concentration, kchem, and Dchem. Conversely, these parameters are markedly improved in A-site deficient BCFZ (D-BCFZ) and Na/K-doped BCFZ. Consequently, the enhancement of these properties yields a significant increase in ORR catalytic activity, with D-BCFZ demonstrating the best electrochemical performance. Specifically, P-SOFC with D-BCFZ cathode achieves an Rp value of just 0.073 Ω cm2 and a Pmax value of 0.928 W cm−2 at 650 °C. This study provides theoretical insight into the mechanisms by how alkali metal doping and defect construction enhance the ORR catalytic activity of BCFZ. These findings offer valuable guidance for the development and optimization of high-performance P-SOFC cathodes.

Nanostructured thin film SrCo0.8Nb0.1Ta0.1O3-δ cathode for low-temperature solid oxide fuel cells

Nanostructured perovskite-type cathodes are considered essential for the realization of high-performance solid oxide fuel cell (SOFC). However, perovskite-type cathode materials demonstrating high electrochemical performance in the low-temperature operating region below 600° are limited. SrCo0.8Nb0.1Ta0.1O3-δ (SCNT) has been identified as a material that exhibits exceptional performance even in the low-temperature region of 500 °C. This paper investigates the growth behavior and electrochemical properties of SCNT thin films for SOFC cathode applications. Pulsed laser deposition (PLD) was employed to fabricate SCNT films under varying chamber pressures: 5 mTorr, 75 mTorr, and 150 mTorr. Systematic analysis through X-ray diffraction and X-ray photoelectron spectroscopy indicates that the structural factors of PLD perovskite oxide nanostructures, such as grain size, porosity, and in-plane connectivity, are intricately influenced by deposition pressure without affecting crystallinity and chemical composition. The findings demonstrate that achieving desired electrochemical properties of the nanostructured PLD perovskite oxide necessitates specific optimal deposition conditions for these structural parameters. Electrochemical assessments revealed an optimal nanostructure achieved with 1200 nm at 75mTorr, demonstrating enhanced power density due to increased active reaction surface area, which significantly reduced resistances in ohmic and polarization. Excessive thickness, however, led to performance decline due to film delamination. Integration of optimized SCNT films into an anodic aluminum oxide supported thin film SOFC exhibited 907 mW/cm2 of peak power density at 550 °C.

Sr and Mn co-doping PrBaFe2O5+δ optimizes the electrochemical performance and stability of solid oxide fuel cell cathode

Developing cobalt-free cathode with high stability and high electrochemical activity is very important for constructing low-cost, high-performance solid oxide fuel cells. Layered perovskite PrBaFe2O5+δ (PBF) is known to ave important magnetic, oxygen exchange kinetic and electrochemical properties. In this study, Sr and Mn co-doping A-site and B-site of PrBa0.5Sr0.5Fe1.6Mn0.4O5+δ (PBSFM) electrode was synthesized and characterized its properties. The first-principles calculation shows that Sr and Mn co-doped PBSFM decreases the oxygen vacancy energy, improves the overlap of oxygen-metal bond hybridization and structural stability. The polarization resistance (Rp) of PBSFM decreases from 0.22 to 0.077 Ω cm2 at 700 °C. At 800 °C, the power density of fuel cell reaches 674 mW cm−2 using hydrogen as fuel. In addition, Sr and Mn co-doped PBSFM significantly improves impedance and single cell stability under operating conditions.

Mechanism of chromium poisoning on La0.5Sr0.5Co0.25Fe0.75O3 cathode and enhancing chromium tolerance using a novel anion doping strategy

Chromium poisoning the La1-xSrxCoyFe1-yO3(LSCF) cathode for solid oxide fuel cells is a severe issue that can lead to its electrochemical performance degradation. To clarify poisoning mechanism of chromium species and develop a novel anion doping strategy with enhancing chromium tolerance, the adsorption behavior of Cr species on LSCF and F-doping LSCF surface are explored by density functional theory (DFT) calculations. Our results indicate that CrO3 molecule prefers to be adsorbed on the La(Sr)O-terminated surface rather that the Co(Fe)O2-terminated LSCF(001) surface. The adsorption energies of CrO3 molecule are much larger than that of O2 molecules, implies that the CrO3 is more favorable to absorb on the LSCF surface. Bader charge analysis shows the CrO3 molecule behaves as an electron acceptor through an adsorption process. The adsorption of Cr atom is a weak physical adsorption for Sr site and La site and the Cr atom chemisorption is found to occur on hollow site and O site. In addition, F-doping efficiently improves chromium tolerance by weakening the adsorption strength of chromium species that poisons LSCF surface and this may be a feasible strategy to develop cathode for high performance solid oxide fuel cells.

Deciphering the enhanced oxygen reduction reaction activity of PrBa0.5Sr0.5Co1.5Fe0.5O5+δ via constructing negative thermal expansion offset for high-performance solid oxide fuel cell

Solid oxide fuel cells (SOFCs) are one of the most efficient energy conversion devices. However, the sluggish oxygen reduction reaction (ORR) kinetics at low temperatures significantly challenge the performance and commercialization of SOFCs. Introducing negative expansion coefficient materials has been recognized as an effective approach to enhancing the ORR catalytic properties, but a clear understanding of this enhanced electrochemical performance is still lacking. In this work, the composite cathode of PrBa0.5Sr0.5Co1.5Fe0.5O5+δ (PBSCF) with different amounts of negative-thermal-expansion material Sm0.85Zn0.15MnO3 (SZM) is prepared, and in-depth analysis the effect of SZM on the catalytic activity of cathodic ORR is systematically investigated. Simultaneously, the mechanistic studies verify that the enhanced ORR activity might be attributed to the constructed compression strain during sintering, which significantly improves the adsorption, dissociation, and oxygen ion exchange process of the PBSCF cathode.

Quantifying Microstructure Features for High-Performance Solid Oxide Cells.

The drive for sustainable energy solutions has spurred interest in solid oxide fuel cells (SOFCs). This study investigates the impact of sintering temperature on SOFC anode microstructures using advanced 3D focused ion beam-scanning electron microscopy (FIB-SEM). The anode's ceramic-metal composition significantly influences electrochemical performance, making optimization crucial. Comparing cells sintered at different temperatures reveals that a lower sintering temperature enhances yttria-stabilized zirconia (YSZ) and nickel distribution, volume, and particle size, along with the triple-phase boundary (TPB) interface. Three-dimensional reconstructions illustrate that the cell sintered at a lower temperature exhibits a well-defined pore network, leading to increased TPB density. Hydrogen flow simulations demonstrate comparable permeability for both cells. Electrochemical characterization confirms the superior performance of the cell sintered at the lower temperature, displaying higher power density and lower total cell resistance. This FIB-SEM methodology provides precise insights into the microstructure-performance relationship, eliminating the need for hypothetical structures and enhancing our understanding of SOFC behavior under different fabrication conditions.

Developing abundant rare-earth iron perovskite electrodes for high-performance and low-cost solid oxide fuel cells

The swift advancement of the solid oxide fuel cell (SOFC) sector necessitates a harmony between electrode performance and commercialization cost. The economic value of elements is frequently linked to their abundance in the Earth's crust. Here, we develop abundant rare-earth iron perovskite electrodes of Ln0.6Sr0.4FeO3-δ (Ln= La, Pr, and Nd) with high abundant rare-earth metals and preferred iron metal for SOFCs. All three symmetric electrode materials display a cubic perovskite phase and excellent chemical compatibility with Gd0.2Ce0.8O2-δ electrolyte. All three electrodes possess exceptional surface oxygen exchange ability. At 800°C, single cells with La0.6Sr0.4FeO3-δ, Pr0.6Sr0.4FeO3-δ, and Nd0.6Sr0.4FeO3-δ symmetric electrodes attained excellent open circuit voltages of 1.108, 1.101, and 1.097 V, respectively, as well as peak powers of 213.52, 281.12, and 254.58 mW cm-2. The results suggest that overall performance of abundant rare-earth iron perovskite electrodes has a favorable impact on the extensive expansion of SOFCs, presenting significant potential for practical applications.

A High-Performance and Durable Direct-Ammonia Symmetrical Solid Oxide Fuel Cell with Nano La0.6Sr0.4Fe0.7Ni0.2Mo0.1O3-δ-Decorated Doped Ceria Electrode.

Solid oxide fuel cells (SOFCs) offer a significant advantage over other fuel cells in terms of flexibility in the choice of fuel. Ammonia stands out as an excellent fuel choice for SOFCs due to its easy transportation and storage, carbon-free nature and mature synthesis technology. For direct-ammonia SOFCs (DA-SOFCs), the development of anode catalysts that have efficient catalytic activity for both NH3 decomposition and H2 oxidation reactions is of great significance. Herein, we develop a Mo-doped La0.6Sr0.4Fe0.8Ni0.2O3-δ (La0.6Sr0.4Fe0.7Ni0.2Mo0.1O3-δ, LSFNM) material, and explore its potential as a symmetrical electrode for DA-SOFCs. After reduction, the main cubic perovskite phase of LSFNM remained unchanged, but some FeNi3 alloy nanoparticles and a small amount of SrLaFeO4 oxide phase were generated. Such reduced LSFNM exhibits excellent catalytic activity for ammonia decomposition due to the presence of FeNi3 alloy nanoparticles, ensuring that it can be used as an anode for DA-SOFCs. In addition, LSFNM shows high oxygen reduction reactivity, indicating that it can also be a cathode for DA-SOFCs. Consequently, a direct-ammonia symmetrical SOFC (DA-SSOFC) with the LSFNM-infiltrated doped ceria (LSFNM-SDCi) electrode delivers a superior peak power density (PPD) of 487 mW cm-2 at 800 °C when NH3 fuel is utilised. More importantly, because Mo doping greatly enhances the reduction stability of the material, the DA-SSOFC with the LSFN-MSDCi electrode exhibits strong operational stability without significant degradation for over 400 h at 700 °C.

High-Performance Reversible Solid Oxide Cells for Powering Electric Vehicles, Long-Term Energy Storage, and CO2 Conversion.

The rapid population growth coupled with rising global energy demand underscores the crucial importance of advancing intermittent renewable energy technologies and low-emission vehicles, which will be pivotal toward carbon neutralization. Reversible solid oxide cells (RSOCs) hold significant promise as a technology for high-efficiency power generation, long-term chemical energy storage, and CO2 conversion. Herein, RSOCs were, for the first time, studied to power electric vehicles. Based on our experimental results, an ideal RSOC stack was established with reasonable assumptions. Subsequently, through analysis and comparison of important merits, such as power densities, energy densities, charging/refueling time, and fuel economy of RSOC-based electric vehicles (RSOCEVs), conventional internal combustor vehicles (ICEVs), and battery-based electric vehicles (BEVs), the advantages and prospects of RSOCEVs were highlighted. Our H2-H2O RSOCs exhibit high electrochemical performances in both fuel cell (peak power density = 1.6 W cm-2 at 750 °C) and electrolysis modes (current density = 2.0 A cm-2 at 1.3 V and 750 °C), along with durable reversible operation under a wide range of conditions. In CO-CO2, our RSOCs achieved excellent performance in fuel cell mode (peak power density = 0.68 cm-2 at 700 °C). Furthermore, a world record current density of 3.4 A cm-2 at 1.5 V and 750 °C was achieved in the CO2 electrolysis mode. Moreover, an assessment of the CO2 electrolysis efficiency was conducted, offering insights for establishing energy storage strategies and mitigating CO2 emissions. Therefore, the RSOC technology has the potential to assume a central role in a future energy system with abundant renewable power generation while mitigating the CO2 released from fossil fuels.

Optimizing Bilayer Electrolyte Thickness Ratios for High-Performing Low-Temperature Solid Oxide Fuel Cells

Abstract Bilayer electrolytes for low-temperature solid oxide fuel cells (LT-SOFCs) offer the potential for higher power density by lowering the ohmic area specific resistance (ASR) and increasing the open circuit voltage (OCV) of mixed ionic/electronic conducting (MIEC) type electrolyte (e.g., GDC). However, optimizing the bilayer electrolyte thickness ratio is essential to achieve high power densities at low-temperatures (650-500℃). Herein we provide a systematic study of GDC/YCSB bilayer thickness ratios on anode-supported LT-SOFCs. In all cases the bilayer maximum power density (MPD) is higher than single-layer GDC based cells with reduced ohmic ASR values. Specifically, a high MPD of ~1 W/cm2 at 650℃ was achieved on a GDC(20 μm)/YCSB(12 μm) bilayer electrolyte based SOFC, which is 62% higher than single-layer GDC based SOFC (0.64 W/cm2) operating on humidified H2 as fuel. Such enhancement is due to the 9.3% improvement in OCV and 36% reduction in ohmic ASR values with the addition of the YCSB layer. The reduction in ohmic ASR of the bilayer electrolyte SOFCs is due to an increase of GDC electrical conductivity caused by the lower pO2 at the YCSB/GDC interface which must be considered in optimizing the thickness ratio of the bilayer electrolyte for achieving higher power density LT-SOFCs.

High-performance Ti-doped strontium cobaltite perovskites as oxygen electrodes in solid oxide cells

Oxygen electrodes play a vital role in realizing high-performance solid oxide cells (SOCs) with high roundtrip efficiency, large-scale capacity, and long-term stability energy storage. This paper constructs Ti-doped strontium cobaltite perovskites (SrCo1-xTixO3-δ, SCTx, x = 0.2, 0.3, 0.4, 0.5) as newly stable oxygen electrodes for SOCs. The changes of oxygen vacancy in SCTx with Ti-doped concentration are investigated by X-ray photoelectron spectroscopy (XPS). The results show that the content of oxygen vacancy decreases with the enrichment of Ti doping. The area-specific resistance (ASR) of the symmetrical cell with SrCo0.8Ti0.2O3-δ (SCT2) electrode is only 0.013 Ω cm2 at 850 °C in air. The single cell with SCT2 oxygen electrode achieves the peak power density of 1.313 W cm−2 at 850 °C under humidified H2 conditions in fuel cells mode, and the current density reaches 2.95 A cm−2 under an electrolytic voltage of 1.9 V at 850 °C for CO2 electrolysis. The Density functional theory (DFT) calculations confirm that the oxygen vacancy formation energy is the lowest when the ratio of Ti to Co is 2:8, verifying the superior property of SCT2. This study comes up with a creation for developing high-stability and high-activity oxygen electrode materials that can be used for energy storage systems.

Revitalizing Oxygen Reduction Reactivity of Composite Oxide Electrodes via Electrochemically Deposited PrOx Nanocatalysts.

Solid oxide fuel cells that operate at intermediate temperatures require efficient catalysts to enhance the inherently poor electrochemical activity of the composite electrodes. Here, a simple and practical electrochemical deposition method is presented for fabricating a PrOx overlayer on lanthanum strontium manganite-yttria-stabilized zirconia (LSM-YSZ) composite electrodes. The method requires less than four minutes for completion and can be carried out under at ambient temperature and pressure. Crucially, the treatment significantly improves the electrode's performance without requiring heat treatment or other supplementary processes. The PrOx-coated LSM-YSZ electrode exhibits an 89% decrease in polarization resistance at 650°C (compared to an untreated electrode), maintaining a tenfold reduction after ≈400h. Transmission line model analysis using impedance spectra confirms how PrOx coating improved the oxygen reduction reaction activity. Further, tests with anode-supported single cells reveal an outstanding peak power density compared to those of other LSM-YSZ-based cathodes (e.g., 418mWcm-2 at 650°C). Furthermore, it is demonstrated that multicomponent coating, such as (Pr,Ce)Ox, can also be obtained with this method. Overall, the observations offer a promising route for the development of high-performance solid oxide fuel cells.

Flat-tube solid oxide stack with high performance for power generation and hydrogen production

This study presents the design, fabrication, and evaluation of a high-performance flat-tube solid oxide cell (FT-SOC) stack, which demonstrates exceptional power generation and hydrogen production capabilities. Comprising three large-sized FT-SOCs, each with an active area of 60 cm2, the stack was tested at 750 °C. It achieved a peak power density of 1.222 W/cm2 in fuel cell (FC) mode and an electrolysis current density of 1.283 A/cm2 at an average voltage of 1.3 V in electrolysis cell (EC) mode, marking the highest reported values for FT-SOC stacks to date. These results surpass the performance of most large-sized planar SOC stacks. Post-operation analysis revealed excellent interfacial contact between components, contributing to the stack's high performance. This study underscores the potential of FT-SOCs in efficient power generation and electrolytic energy storage applications, providing insights that could facilitate their industrial application.

Synergistic Effects of In-Situ Exsolved Ni-Ru Bimetallic Catalyst on High-Performance and Durable Direct-Methane Solid Oxide Fuel Cells.

Direct-methane solid oxide fuel cells (CH4-SOFCs) have gained significant attention as methane, the primary component of natural gas (NG), is cheap and widely available and the natural gas infrastructures are relatively mature. However, at intermediate temperatures (e.g., 600-650 °C), current CH4-SOFCs suffer from low performance and poor durability under a low steam-to-carbon ratio (S/C ratio), which is ascribed to the Ni-based anode that is of low catalytic activity and prone to coking. Herein, with the guidance of density functional theory (DFT) studies, a highly active and coking tolerant steam methane reforming (SMR) catalyst, Sm-doped CeO2-supported Ni-Ru (SCNR), was developed. The synergy between Ni and Ru lowers the activation energy of the first C-H bond activation and promotes CHx decomposition. Additionally, Sm doping increases the oxygen vacancy concentration in CeO2, facilitating H2O adsorption and dissociation. The SCNR can therefore simultaneously activate both CH4 and H2O molecules while oxidizing the CH* and improving coking tolerance. We then applied SCNR as the CH4-SOFC anode catalytic reforming layer. A peak power density of 733 mW cm-2 was achieved at 650 °C, representing a 55% improvement compared to that of pristine CH4-SOFCs (473 mW cm-2). Moreover, long-term durability testing, with >2000 h continuous operation, was performed under almost dry methane (5% H2O). These results highlight that CH4-SOFCs with a SCNR catalytic layer can convert NG to electricity with high efficiency and resilience.

3D printed electrolyte-supported solid oxide cells based on Ytterbium-doped scandia-stabilized zirconia

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 μm- 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.

(Invited) Materials Stability in Anode-Supported Solid Oxide Cells

Professor Anil Virkar has been a pioneer in the development and characterization of high-performance anode-supported solid oxide fuel cells, and in understanding degradation processes in such cells operated in electrolysis mode. This talk reviews methods for improving anode-supported cells, particularly for yielding high performance at reduced operating temperature. The understanding of degradation mechanisms occurring during solid oxide electrolysis cell operation will be discussed.

Low-pressure plasma sprayed dense scandia-stabilized zirconia electrolyte and its effect on SOFC performance

The plasma spraying process has been proven capable of fabricating high-performance metal-supported solid oxide fuel cells (MS-SOFCs), and the critical technology is to prepare dense MS-SOFC electrolytes. Usually, very low-pressure plasma spraying (<1000 Pa) is adopted as it can significantly improve the electrolyte density and air tightness. However, at the same time, it also has the disadvantages of low deposition efficiency and high cost. This paper explores whether it is possible to prepare dense MS-SOFC electrolytes under low-pressure conditions (1000–10000 Pa) with ideal deposition efficiency and cost. Specifically, 4000 Pa and 7000 Pa were chosen to prepare scandia-stabilized zirconia (ScSZ) electrolytes. The effects of spraying pressure and distance on the electrolyte microstructure and cell electrochemical performance were investigated. It was found that the electrolyte prepared at a pressure of 4000 Pa and a spraying distance of 325 mm had the lowest porosity of 3.28%. Meanwhile, the cell exhibited the best electrochemical performance with an open circuit voltage of 1.008 V and a maximum power density of 970 mW/cm2 at 800 °C.

High-performance solid oxide electrolysis cell with the ordered straight pores in the support

The large diffusion resistance of steam in the thick support layer is the main factor limiting the performance of solid oxide electrolysis cell (SOEC). This work demonstrates the importance of the straight pore diffusion channel in enhancing the performance of electrolysis cell. The Cell-A with the straight pore diffusion channel in the support and the Cell-B with randomly distributed pores in the support have been compared and the corresponding reaction mechanisms are elucidated. Under 50% absolute humidity (A.H), Cell-A achieves a very high current density of −4.30 A cm−2@1.5V and −2.37 A cm−2@1.3V at 800 °C. Even if under A.H = 10%, Cell-A also displays a high current density of −2.74A cm−2@1.5V, which is 6 times than that of Cell-B. Electrochemical impedance spectroscopy (EIS) measurements and analysis of distribution of relaxation times (DRT) reveal a significant reduction of the gas diffusion resistance on Cell-A. The rate-determining Cell-A is the diffusion of oxygen ion through the air electrode/electrolyte interface, and the gas diffusion is no longer the main factor limiting steam electrolysis.