Advanced Materials and Clean Energy Laboratory (AMCEL)

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Abstract

Achieving both chemical robustness and practical manufacturability of proton-conducting electrolytes remains a central barrier to high-performance reversible protonic ceramic cells (R-PCCs). Zirconium-based proton conductors offer exceptional thermochemical stability, yet their limited sintering kinetics often result in poor densification, elevated ohmic resistance, and mechanically fragile interfaces. Here, we introduce a gradient electrode strategy that resolves this long-standing processing-performance conflict by jointly regulating sintering kinetics, shrinkage behavior, and interfacial compatibility within the cell architecture. In this design, a sintering-active electrolyte is coupled with a highly sinterable support through a compositionally graded electrode interlayer, enabling cooperative shrinkage-stress-assisted densification while suppressing chemical and mechanical mismatch across interfaces. This synergistic configuration produces dense, large-grained electrolyte membranes with chemically clean and mechanically coherent junctions, leading to enhanced proton transport and efficient electrode coupling. As a result, this graded design dramatically enhances proton transport and electrode integration, enabling reversible cell operation with a peak power density of 671 mW cm−2and electrolysis current densities up to −1.33 A cm−2 at 1.3 V and 600 °C. Beyond performance metrics, the graded architecture exhibits exceptional resilience under aggressive operating conditions, including rapid thermal cycling, dynamic voltage perturbations, and prolonged high-steam electrolysis, without measurable degradation. By coupling kinetically activated electrolytes with gradient electrode integration, this work establishes a broadly applicable graded co-sintering framework for structural integration of multilayer R-PCCs, overcoming a key limitation that has constrained Zr-based proton conductors for over a decade and advancing their viability for durable, high-efficiency hydrogen energy conversion.

Our article, “Interfacial Nanostructuring Enables Integrated, Low-Polarization Reversible Protonic Ceramic Cells,” was accepted for publication in Advanced Advanced Energy Materials. 

oxygen‑electrode–electrolyte junction simultaneously controls polarization losses, steam tolerance, and mechanical stability during reversible operation. Conventional porous electrodes depend on discontinuous point contacts and chemically reactive interfaces, which raise interfacial resistance and increase the likelihood of delamination. Addressing these coupled limitations requires an interlayer that is thin, conductive, continuous, chemically compatible, and structurally integrated.

This work introduces a pulsed‑laser‑deposition interfacial nanostructuring approach that forms a dense, nanocrystalline Pr₀.₅La₀.₅BaCo₂O₅₊δ interlayer directly on a chemically robust BaZr₀.₈Y₀.₂O₃ electrolyte. The resulting interlayer creates a conformal two‑dimensional contact and a defect‑rich reaction zone beneath a porous PLBC oxygen electrode, strengthening the electrode–electrolyte junction while maintaining gas accessibility. The engineered interface increases interfacial bonding strength threefold and substantially lowers interfacial polarization. As a result, the cells reach peak power densities of 1.16 W cm⁻² at 600 °C and sustain stable steam‑electrolysis operation for roughly 1000 h under 0.3–0.7 atm steam, maintaining steady operando impedance at 1.30 V with faradaic efficiency above 92%. These findings demonstrate that interfacial nanostructuring enables structurally integrated, low‑polarization electrode–electrolyte interfaces suitable for versatile electrochemical devices.  

Link will be provided soon...

Our article, “Heterojunction Architecture Resolves the Stability-Performance Paradox in Reversible Protonic Ceramic Cells,” was accepted for publication in Advanced Functional Materials. 

The practical deployment of protonic ceramic cells (PCCs) is currently impeded by an intrinsic trade-off between chemical stability and electrochemical performance. Here, we resolve this paradox through a heterojunction architecture that synergistically integrates a high-conductivity, Zn-modified chemically stable electrolyte with a self-assembled, multiphasic oxygen electrode, PrNi0.5Co0.3Zr0.1Y0.1O3-δ (PNCZY). This design establishes a functionally graded interface with engineered band alignment, creating a Schottky-type barrier that selectively suppresses electronic leakage while facilitating rapid proton transport. The resulting device exhibits exceptional bidirectional performance, achieving a peak power density of 956 mW cm-2 at 600 °C in fuel cell mode and an electrolysis current density of -2300 mA cm-2 at 1.3 V. Crucially, the cell maintains > 96% Faradaic efficiency under high steam loads, confirming the efficacy of the carrier-selective interface. This work provides a generalizable blueprint for decoupling material properties through interfacial engineering, paving the way for durable, high-efficiency energy conversion technologies.  

https://advanced.onlinelibrary.wiley.com/doi/10.1002/adfm.202600006

Our article “Nano-Engineered Interfaces in Dual-Layer Electrodes for Protonic Ceramic Cells with Enhanced Stability and Kinetics” was accepted by ACS Nano. 

Enhancing interfacial stability and charge transfer in protonic ceramic cells (PCCs) remains a critical challenge, as structural degradation and interfacial resistance often compromise durability and efficiency. Here, we report a nanoengineered dual-layer oxygen electrode architecture designed to address these limitations by introducing a fine-grained nanoparticle interfacial contact layer beneath a porous catalytic backbone. The nanoscale powders, through enhanced sintering activity, densify into a robust interfacial layer that promotes strong chemical bonding, uniform adhesion, and continuous ionic/electronic pathways with the BCZYYb electrolyte. This hierarchical architecture mitigates delamination, redistributes mechanical stress, and establishes efficient charge and mass transport channels without relying on corrosive surface treatments. Electrochemical evaluation demonstrates that the dual-layer design markedly reduces interfacial polarization resistance and accelerates electrode kinetics. Compared to the single-layer counterpart, the architecture achieves a peel strength of 44.53 N/cm2, a 40% improvement in peak power density (0.96 W cm–2 at 600 °C), and a 130% enhancement in electrolysis current density (4.78 A cm–2 at 1.57 V). Faradaic efficiency remains as high as 88% under high steam concentrations, underscoring minimal charge loss during practical operation. Notably, the electrode retains stability across 450–600 °C and under transient voltage cycling, with impedance spectra confirming suppressed interfacial resistance growth over prolonged use. These results highlight nanoscale interface engineering as a powerful route to enhance both mechanical robustness and electrochemical kinetics in PCCs. The demonstrated scalability and durability of this architecture provide a versatile platform for advancing solid-state electrochemical systems, including reversible fuel cells and high-efficiency hydrogen production technologies. 

https://pubs.acs.org/doi/10.1021/acsnano.5c15759

Our article “Scalable Solution-Processed Electrolyte Membranes with Optimized Microstructure for High-Performance Protonic Ceramic Electrochemical Cells” was accepted by ACS Applied Materials & Interfaces. 

Proton-conducting electrochemical cells (PCECs) are promising for efficient hydrogen production, but achieving dense, uniform, thin electrolyte layers remains a key challenge, particularly for scalable fabrication. Here, we present a solution-processed deposition approach with a mechanistically optimized slurry for uniform electrolyte formation. By tailoring particle size distribution, solid loading, and solvent/additive balance, we regulated wetting behavior and evaporation kinetics of the electrolyte slurry to promote homogeneous electrolyte particle packing. These features facilitate tight grain boundary contact and early stage neck growth during sintering, eliminating residual porosity, and improving mechanical integrity. The resulting ∼15 μm thick electrolyte shows high density, strong electrode adhesion, and stable interfaces outperforming the previously reported spray-based fabricated electrolyte by about 31% at 600 °C in FC mode. Single cells deliver 0.962 W cm–2 at 600 °C in fuel cell mode and 1.31 A cm–2 at 1.3 V in electrolysis mode, maintaining robust performance over 100 h with negligible degradation (≤0.02% h–1) in each mode. Scale-up to 2.5 cm diameter substrates confirmed reproducible densification and geometric stability. This work demonstrates a cost-effective, scalable route where control over particle-fluid interactions and drying dynamics enables a superior electrolyte microstructure and high PCEC performance. 

https://pubs.acs.org/doi/10.1021/acsami.5c16287

Our review work entitled “Multiscale engineering of BaZr1-xYxO3-δ -based protonic ceramics: A critical review of defect chemistry, interface design, and computational insights” was accepted by Energy Reviews. 

Protonic ceramic energy devices represent a promising frontier for sustainable energy conversion and storage, operating efficiently at intermediate temperatures (350–650 ​°C) and facilitating integration with renewable energy sources. Among protonic ceramic materials, yttrium-doped barium zirconate (BaZr1-xYxO3-δ, BZY) stands out for its competitive proton conductivity, chemical resilience, and compatibility with diverse fuels and environments. This review critically examines the fundamentals and multiscale design strategies for BZY-based ceramic cells. We discuss atomic-level composition-structure relationships, innovative synthesis routes, and advanced processing methods to overcome manufacturing and scalability challenges. We then highlight microstructure engineering and interface design approaches that minimize resistance and elevate device performance, supported by state-of-the-art characterization and predictive modeling techniques, including density functional theory and machine learning. Recent advances, such as hybrid architectures and AI-driven defect optimization, demonstrate significant improvements in conductivity, stability, and Faradaic efficiency, confirming BZY's pivotal role in green hydrogen production and power-to-chemicals applications. By integrating insights across materials chemistry, electrochemistry, and engineering, this review provides a comprehensive roadmap for researchers aiming to translate laboratory breakthroughs into robust, scalable protonic ceramic technologies for decarbonized energy systems. 

https://www.sciencedirect.com/science/article/pii/S2772970225000367?via%3Dihub

We recently have a work “Structural Transformation of Oxygen Electrode from Perovskite to Ruddlesden-Popper for Enhanced Reversible Hydrogen Production and Power Generation in Protonic Ceramic Cells” accepted by Materials Today (IF=22). In this work, we a novel Ruddlesden-Popper (R-P) structured electrode, (Pr0.6Sr0.4)2Ni0.7Co0.3O4+δ (PSNC), produced by systematic strontium doping in PrNi0.7Co0.3O3-δ (PNC) for intermediate-temperature reversible protonic ceramic electrochemical cells. 

The strategic Sr2+ substitution for Pr3+ causes a structural transition from an orthorhombic perovskite to a layered R-P phase, generating well-defined routes for improved ionic transport. Electrochemical characterizations reveal outstanding bifunctional performance, with the PSNC electrode obtaining a peak power density of 1.03 W cm-2 in fuel cell mode and a current density of 1.30 A cm-2 at 1.30 V in electrolysis mode at 600 °C.  The cell demonstrates exceptional operational resilience and mechanical-electrochemical robustness, maintaining long-term stability despite vigorous dynamic voltage cycling.  Faradaic efficiency experiments at 1.16 V under 50% steam show up to 85% efficiency and highly steady extended galvanostatic operation up to 2.0 A cm-2, indicating the electrode’s durability and stability in harsh environments.  Structural and interfacial investigations confirm the electrode’s pristine integrity and high compatibility with the electrolyte. These synergistic properties position PSNC as a promising choice for next-generation energy conversion devices, allowing for seamless transitions between power generation and hydrogen production under realistic conditions.

https://www.sciencedirect.com/science/article/pii/S136970212500433X?dgcid=coauthor

We have a two-years project funded to work on developing a biochar integrated membrane reactor for achieving reactive carbon capture from biomass and carbon wastes into olefins. 

Collaborated with Prof. Pei Dong and her student, Boshen Xu, from George Mason University, we recently have one review paper titled with “Surface Reconstruction of Versatile Perovskites via In Situ Nanoparticle Engineering for Solid Oxide Cells” to be published by Chem Catalysis.

Dr. Jiufeng Ruan, our postdoc researcher, is the equal first author together with Boshen.

This review discusses the atomic-scale surface reconstruction of perovskite oxides via in situ exsolution. It emphasizes the fundamental mechanisms, strategies for precise process control, and the recent progresses of advanced techniques for in situ explorative characterizations. These insights provide guidance for designing durable and efficient perovskite catalysts in solid oxide cells.

Congratulations, everyone! The paper link will be provided soon.