Harnessing High-Throughput Computational Methods to Accelerate the Discovery of Optimal Proton Conductors for High-Performance and Durable Protonic Ceramic Electrochemical Cells.

The pursuit of high-performance and long-lasting protonic ceramic electrochemical cells (PCECs) is impeded by the lack of efficient and enduring proton conductors. Conventional research approaches, predominantly based on a trial-and-error methodology, have proven to be demanding of resources and time-consuming. Here, this work reports the findings in harnessing high-throughput computational methods to expedite the discovery of optimal electrolytes for PCECs. This work methodically computes the oxygen vacancy formation energy (EV), hydration energy (EH), and the adsorption energies of H2O and CO2 for a set of 932 oxide candidates. Notably, these findings highlight BaSnxCe0.8-xYb0.2O3-δ (BSCYb) as a prospective game-changing contender, displaying superior proton conductivity and chemical resilience when compared to the well-regarded BaZrxCe0.8-xY0.1Yb0.1O3-δ (BZCYYb) series. Experimental validations substantiate the computational predictions; PCECs incorporating BSCYb as the electrolyte achieved extraordinary peak power densities in the fuel cell mode (0.52 and 1.57 W cm-2 at 450 and 600 °C, respectively), a current density of 2.62 A cm-2 at 1.3 V and 600 °C in the electrolysis mode while demonstrating exceptional durability for over 1000-h when exposed to 50% H2O. This research underscores the transformative potential of high-throughput computational techniques in advancing the field of proton-conducting oxides for sustainable power generation and hydrogen production.

Tuning Proton Insertion Chemistry for Sustainable Aqueous Zinc-Ion Batteries.

Rechargeable aqueous zinc-ion batteries (ZIBs) have emerged as an alternative to lithium-ion batteries due to their affordability and high level of safety. However, their commercialization is hindered by the low mass loading and irreversible structural changes of the cathode materials during cycling. Here, a disordered phase of a manganese nickel cobalt dioxide cathode material derived from wastewater via a coprecipitation process is reported. When used as the cathode for aqueous ZIBs , the developed electrode delivers 98% capacity retention at a current density of 0.1 A g-1 and 72% capacity retention at 1 A g-1 while maintaining high mass loading (15 mg cm-2 ). The high performance is attributed to the structural stability of the Co and Ni codoped phase; the dopants effectively suppress Jahn-Teller distortion of the manganese dioxide during cycling, as revealed by operando X-ray absorption spectroscopy. Also, it is found that the Co and Ni co-doped phase effectively inhibits the dissolution of Mn2+ , resulting in enhanced durability without capacity decay at first 20 cycles. Further, it is found that the performance of the electrode is sensitive to the ratio of Ni to Co, providing important insight into rational design of more efficient cathode materials for low-cost, sustainable, rechargeable aqueous ZIBs.

A Synergistic Three-Phase, Triple-Conducting Air Electrode for Reversible Proton-Conducting Solid Oxide Cells.

Reversible proton-conducting solid oxide cells (R-PSOCs) have the potential to be the most efficient and cost-effective electrochemical device for energy storage and conversion. A breakthrough in air electrode material development is vital to minimizing the energy loss and degradation of R-PSOCs. Here we report a class of triple-conducting air electrode materials by judiciously doping transition- and rare-earth metal ions into a proton-conducting electrolyte material, which demonstrate outstanding activity and durability for R-PSOC applications. The optimized composition Ba0.9Pr0.1Hf0.1Y0.1Co0.8O3-δ (BPHYC) consists of three phases, which have a synergistic effect on enhancing the performance, as revealed from electrochemical analysis and theoretical calculations. When applied to R-PSOCs operated at 600 °C, a peak power density of 1.37 W cm-2 is demonstrated in the fuel cell mode, and a current density of 2.40 A cm-2 is achieved at a cell voltage of 1.3 V in the water electrolysis mode under stable operation for hundreds of hours.

Durable and High-Performance Thin-Film BHYb-Coated BZCYYb Bilayer Electrolytes for Proton-Conducting Reversible Solid Oxide Cells.

Proton-conducting reversible solid oxide cells are a promising technology for efficient conversion between electricity and chemical fuels, making them well-suited for the deployment of renewable energies and load leveling. However, state-of-the-art proton conductors are limited by an inherent trade-off between conductivity and stability. The bilayer electrolyte design bypasses this limitation by combining a highly conductive electrolyte backbone (e.g., BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (BZCYYb1711)) with a highly stable protection layer (e.g., BaHf0.8Yb0.2O3-δ (BHYb82)). Here, a BHYb82-BZCYYb1711 bilayer electrolyte is developed, which dramatically enhances the chemical stability while maintaining high electrochemical performance. The dense and epitaxial BHYb82 protection layer effectively protects the BZCYYb1711 from degradation in contaminating atmospheres such as high concentrations of steam and CO2. When exposed to CO2 (3% H2O), the bilayer cell degrades at a rate of 0.4 to 1.1%/1000 h, which is much lower than the unmodified cells at 5.1 to 7.0%. The optimized BHYb82 thin-film coating adds negligible resistance to the BZCYYb1711 electrolyte while providing a greatly enhanced chemical stability. Bilayer-based single cells demonstrated state-of-the-art electrochemical performance, with a high peak power density of 1.22 W cm-2 in the fuel cell mode and -1.86 A cm-2 at 1.3 V in the electrolysis mode at 600 °C, while demonstrating excellent long-term stability.

A New Class of Proton Conductors with Dramatically Enhanced Stability and High Conductivity for Reversible Solid Oxide Cells.

Reversible solid oxide cells based on proton conductors (P-ReSOCs) have potential to be the most efficient and low-cost option for large-scale energy storage and power generation, holding promise as an enabler for the implementation of intermittent renewable energy technologies and the widespread utilization of hydrogen. Here, the rational design of a new class of hexavalent Mo/W-doped proton-conducting electrolytes with excellent durability while maintaining high conductivity is reported. Specifically, BaMo(W)0.03 Ce0.71 Yb0.26 O3-δ exhibits dramatically enhanced chemical stability against high concentrations of steam and carbon dioxide than the state-of-the-art electrolyte materials while retaining similar ionic conductivity. In addition, P-ReSOCs based on BaW0.03 Ce0.71 Yb0.26 O3-δ demonstrate high peak power densities of 1.54, 1.03, 0.72, and 0.48 W cm-2 at 650, 600, 550, and 500 °C, respectively, in the fuel cell mode. During steam electrolysis, a high current density of 2.28 A cm-2 is achieved at a cell voltage of 1.3 V at 600 °C, and the electrolysis cell can operate stably with no noticeable degradation when exposed to high humidity of 30% H2 O at -0.5 A cm-2 and 600 °C for over 300 h. Overall, this work demonstrates the promise of donor doping for obtaining proton conductors with both high conductivity and chemical stability for P-ReSOCs.

A Nonstoichiometric Niobium Oxide/Graphite Composite for Fast-Charge Lithium-Ion Batteries.

Electrification of transportation has spurred the development of fast-charge energy storage devices. High-power lithium-ion batteries require electrode materials that can store lithium quickly and reversibly. Herein, the design and construction of a Nb2 O5-δ /graphite composite electrode that demonstrates remarkable rate capability and durability are reported. The presence of graphite enables the formation of a dominant Nb12 O29 phase and a minor T-Nb2 O5 phase. The high rate capability is attributed to the enhanced electronic conductivity and lower energy barriers for fast lithium diffusion in both Nb12 O29 and T-Nb2 O5 , as unraveled by density functional theory calculations. The excellent durability or long cycling life is originated from the coherent redox behavior of Nb ions and high reversibility of lithium intercalation/deintercalation, as revealed by operando X-ray absorption spectroscopy analysis. When tested in a half-cell at high cycling rates, the composite electrode delivers a specific capability of 120 mAh g-1 at 80 C and retains over 150 mAh g-1 after 2000 cycles at 30 C, implying that it is a highly promising anode material for fast-charging lithium-ion batteries.

High-Performance, Thermal Cycling Stable, Coking-Tolerant Solid Oxide Fuel Cells with Nanostructured Electrodes.

Solid oxide fuel cells (SOFCs) are a promising solution to a sustainable energy future. However, cell performance and stability remain a challenge. Durable, nanostructured electrodes fabricated via a simple, cost-effective method are an effective way to address these problems. In this work, both the nanostructured PrBa0.5Sr0.5Co1.5Fe0.5O5+δ (PBSCF) cathode and Ni-Ce0.8Sm0.2O1.9 (SDC) anode are fabricated on a porous yttria-stabilized zirconia (YSZ) backbone via solution infiltration. Symmetrical cells with a configuration of PBSCF|YSZ|PBSCF show a low interfacial polarization resistance of 0.03 Ω cm2 with minimal degradation at 700 °C for 600 h. Ni-SDC|YSZ|PBSCF single cells exhibit a peak power density of 0.62 W cm-2 at 650 °C operated on H2 with good thermal cycling stability for 110 h. Single cells also show excellent coking tolerance with stable operation on CH4 for over 120 h. This work offers a promising pathway toward the development of high-performance and durable SOFCs to be powered by natural gas.

Fabrication of Ag-Pd concave nanocrystals through facet-selective oxidation of Ag atoms.

We report the fabrication of Ag-Pd concave nanocrystals by introducing the Pd(ii) precursor into an aqueous suspension of Ag nanocubes in the presence of cetyltrimethylammonium chloride (CTAC) under ambient conditions. Different from the previously reported work that involved the oxidation of Ag and deposition of Pd at random sites on the surface for the generation of Ag-Pd hollow nanocrystals, we demonstrate that the Cl- ions from CTAC can confine the oxidation of Ag atoms to the side faces of a nanocube while the resultant Pd atoms are deposited on the edges in an orthogonal manner. By controlling the amount of the Pd(ii) precursor involved in a synthesis, we can transform Ag nanocubes into Ag-Pd nanocrystals with different degrees of concaveness for the side faces and controllable Pd contents. We characterize the outermost layer of concave surfaces for the as-obtained Ag-Pd nanocrystals by surface-enhanced Raman scattering (SERS) through the use of an isocyanide probe. This facile approach would enable the fabrication of Ag-based concave nanocrystals for applications in plasmonics and catalysis.