Influence of the Discretization Methods on the Distribution of Relaxation Times Deconvolution: Implementing Radial Basis Functions with DRTtools

Bimetallic FeCu-MOF derivatives as heterogeneous catalysts with enhanced stability for electro-Fenton degradation of lisinopril

A bimetallic FeCu/NC core-shell catalyst, consisting in nanoparticles where zero-valent Fe and Cu atoms, slightly oxidized on their surface, are encapsulated by carbon has been successfully prepared by modifying the synthesis route of MIL(Fe)-88B. FeCu/NC possessed well-balanced textural and electrochemical properties. According to voltammetric responses, in-situ Fe(III) reduction to Fe(II) by low-valent Cu was feasible, whereas the high double-layer capacitance confirmed the presence of a great number of electroactive sites that was essential for continuous H2O2 activation to •OH via Fenton's reaction. Electrochemical impedance and distribution of relaxation times (DRT) analysis informed about the strong leaching resistance of FeCu/NC. To validate the promising features of this catalyst, the advanced oxidation of the antihypertensive lisinopril (LSN) was investigated for the first time. The heterogeneous electro-Fenton (HEF) treatment of 16.1 mg L-1 LSN solutions was carried out in a DSA/air-diffusion cell. At pH 3, complete degradation was achieved within 6 min using only 0.05 g L-1 FeCu/NC; at near-neutral pH, 100 % removal was also feasible even in actual urban wastewater, requiring 60-75 min. The FeCu/NC catalyst demonstrated high stability, still maintaining 86.5 % of degradation efficiency after 5 cycles and undergoing low iron leaching. It outperformed the monometallic (Fe/NC and Cu/NC) catalysts, which is explained by the Cu(0)/Cu(I)-catalyzed Fe(II) regeneration mechanism that maintains the Fenton's cycle. LC-MS/MS analysis allowed the identification of two main primary LSN by-products. It can then be concluded that the FeCu/NC-based HEF process merits to be further scaled up for wastewater treatment.

Lanthanum doping and surface Li3BO3 passivating layer enabling 4.8 V nickel-rich layered oxide cathodes toward high energy lithium-ion batteries

Single crystalline Ni-rich layered oxide cathodes show high energy density and low cost, have been regarded as one of the most promising candidates for next generation lithium-ion batteries (LIBs). Extending the cycling voltage window will significantly improve the energy density, however, suffers from bulk structural and interfacial chemistry degradation, leading to rapidly cycle performance deterioration. Here, we propose a dual-modification strategy to synthesize La doping and Li3BO3 (LBO) coating layers modified LiNi0.8Co0.1Mn0.1O2 (NCM811) by a facile one-step heating treatment processing. In-situ EIS and XRD, ex-situ XPS techniques are applied to demonstrate that the La diffused amorphous domains and Li3BO3 passivating layers dampen the lattice distortion, enhance the interfacial chemistry behavior as well as lithium ion transportation kinetics. Specifically, surface La doping amorphous domains successfully suppress the intense lattice stress and volume changes induced by the phase transitions during lithiation/delithiation, thus avoiding the intergranular crack and enhancing the mechanical stability of the material. Moreover, the LBO layer formed by the consumption of residual lithium prevents successive parasitic reactions at the interface as well as provides rapid Li-ion diffusion channels. Furthermore, the coating layer also diminishes the residual lithium compounds, increasing the atmosphere stability and safety of LIBs. Consequently, the La doping and LBO coating NCM811 exhibits an exceptional initial specific capacity (230.6 mAh/g) at 0.5C under a high cutoff voltage of 4.8 V, and a 73.8 % capacity retention following 100 cycles. In addition, a superior specific capacity of 133.8 mAh/g is provided even at a high current density (4C). Our work paves a promising road to tackle the integral structure deterioration and interfacial instability of Ni-rich cathodes.

Densification of Cathode/Electrolyte Interphase to Enhance Reversibility of LiCoO2 at 4.65 V

For LiCoO2 (LCO) operated beyond 4.55 V (vs Li/Li+), it usually suffers from severe surface degradation. Constructing a robust cathode/electrolyte interphase (CEI) is effective to alleviate the above issues, however, the correlated mechanisms still remain vague. Herein, a progressively reinforced CEI is realized via constructing Zr─O deposits (ZrO2 and Li2ZrO3) on LCO surface (i.e., Z-LCO). Upon cycle, these Zr─O deposits can promote the decomposition of LiPF6, and progressively convert to the highly dispersed Zr─O─F species. In particular, the chemical reaction between LiF and Zr─O─F species further leads to the densification of CEI, which greatly reinforces its toughness and conductivity. Combining the robust CEI and thin surface rock-salt layer of Z-LCO, several benefits are achieved, including stabilizing the surface lattice oxygen, facilitating the interface Li+ transport kinetics, and enhancing the reversibility of O3/H1-3 phase transition, etc. As a result, the Z-LCO||Li cells exhibit a high capacity retention of 84.2% after 1000 cycles in 3-4.65 V, 80.9% after 1500 cycles in 3-4.6 V, and a high rate capacity of 160 mAh g-1 at 16 C (1 C = 200 mA g-1). This work provides a new insight for developing advanced LCO cathodes.

A family of dual-anion-based sodium superionic conductors for all-solid-state sodium-ion batteries

The sodium (Na) superionic conductor is a key component that could revolutionize the energy density and safety of conventional Na-ion batteries. However, existing Na superionic conductors are primarily based on a single-anion framework, each presenting inherent advantages and disadvantages. Here we introduce a family of amorphous Na-ion conductors (Na2O2-MCly, M = Hf, Zr and Ta) based on the dual-anion framework of oxychloride. Benefiting from a dual-anion chemistry and with the resulting distinctive structures, Na2O2-MCly electrolytes exhibit room-temperature ionic conductivities up to 2.0 mS cm-1, wide electrochemical stability windows and desirable mechanical properties. All-solid-state Na-ion batteries incorporating amorphous Na2O2-HfCl4 electrolyte and a Na0.85Mn0.5Ni0.4Fe0.1O2 cathode exhibit a superior rate capability and long-term cycle stability, with 78% capacity retention after 700 cycles under 0.2 C (1C = 120 mA g-1) at room temperature. The discoveries in this work could trigger a new wave of enthusiasm for exploring new superionic conductors beyond those based on a single-anion framework.

Locally Enhanced Flow and Electric Fields Through a Tip Effect for Efficient Flow-Electrode Capacitive Deionization

Low-electrode capacitive deionization (FCDI) is an emerging desalination technology with great potential for removal and/or recycling ions from a range of waters. However, it still suffers from inefficient charge transfer and ion transport kinetics due to weak turbulence and low electric intensity in flow electrodes, both restricted by the current collectors. Herein, a new tip-array current collector (designated as T-CC) was developed to replace the conventional planar current collectors, which intensifies both the charge transfer and ion transport significantly. The effects of tip arrays on flow and electric fields were studied by both computational simulations and electrochemical impedance spectroscopy, which revealed the reduction of ion transport barrier, charge transport barrier and internal resistance. With the voltage increased from 1.0 to 1.5 and 2.0 V, the T-CC-based FCDI system (T-FCDI) exhibited average salt removal rates (ASRR) of 0.18, 0.50, and 0.89 μmol cm-2 min-1, respectively, which are 1.82, 2.65, and 2.48 folds higher than that of the conventional serpentine current collectors, and 1.48, 1.67, and 1.49 folds higher than that of the planar current collectors. Meanwhile, with the solid content in flow electrodes increased from 1 to 5 wt%, the ASRR for T-FCDI increased from 0.29 to 0.50 μmol cm-2 min-1, which are 1.70 and 1.67 folds higher than that of the planar current collectors. Additionally, a salt removal efficiency of 99.89% was achieved with T-FCDI and the charge efficiency remained above 95% after 24 h of operation, thus showing its superior long-term stability.

Boosting Electrochemical Performance via Extra-Role of La-Doped CeO2-δ Interlayer for "Oxygen Provider" at High-Current SOFC Operation

Utilizing rare earth doped ceria in solid oxide cells (SOCs) engineering is indeed a strategy aimed at enhancing the electrochemical devices' durability and activity. Particularly, Gd-doped ceria (GDC) is actively used for barrier layer and catalytic additives in solid oxide fuel cells (SOFCs). In this study, experiments are conducted with La-doped CeO2 (LDC), in which the Ce sites are predominantly occupied by La, to prevent the formation of the Ce-Zr solid solution. This LDC is comparably used as a functional interlayer between the electrolyte and cathode if sintered at lower temperatures to avoid La2Zr2O7 impurity. In addition, the high substitution of La3+ into the ceria lattice improves the oxygen non-stoichiometry of LDC, leading to accelerated electrochemical high performance by the additional role of LDC for oxygen supplier capacitance at high current operation. Thus, it is confirmed that the improved SOFC high performance is achieved at the maximum power density (MPD) of ≈2.15 W cm-2 at 800 °C when the optimized LDC buffer layer is hired at the anode-supported typed-Samsung's SOFC by lowering the sintering temperature to prevent LDC's impurity reaction.

Evaluation of Oxide|Sulfide Heteroionic Interface Stability for Developing Solid-State Batteries with a Lithium-Metal Electrode: The Case of LLZO|Li6PS5Cl and LLZO|Li7P3S11

Developing solid-state batteries (SSB) with a lithium metal electrode (LME) using only one type of solid electrolyte (SE) is a significant challenge since no SE fits all the requirements imposed by both electrodes. A possible solution is using multilayer SSBs with an LME where the drawbacks of each SE are overcome by using layers of different SEs. However, research on inorganic SE1|SE2 heteroionic interfaces is still quite preliminary, especially regarding oxide|sulfide heteroionic interfaces. This work reports the electrochemical investigation of the heteroionic interface between Li6.25Al0.25La3Zr2O12 (Al-LLZO) and two representative materials for sulfide-based SEs: argyrodite-based Li6PS5Cl (LPSCl) and glass-like Li7P3S11 (LPS711). Through in-depth temperature- and pressure-dependent impedance analyses of multilayer symmetric cells at equilibrium (i.e., no current load), the electrical properties of the heteroionic interfaces are assessed. The pressure-dependent kinetic of the Al-LLZO|LPSCl pair is interpreted with the concept of geometric constriction resistance and show that its resistance is lower than for the Al-LLZO|LPS711 pair. Furthermore, the effect of Al-LLZO surface treatment on the electrical properties of the Al-LLZO|LPSCl heteroionic interface is evaluated. Such investigation shows that the value of the interface activation energy decreases when the Al-LLZO surface is heat treated, revealing a significant influence of the carbonate/hydroxide passivation layer on the heteroionic interface. Additionally, by cycling the symmetric cell for 900 h at 1.0 mAh·cm-2, it is revealed that the Al-LLZO|LPSCl interface has a lower impedance increase than the Al-LLZO|LPS711 interface, especially if the Al-LLZO is heat treated. With this work, we highlight that the oxide|argyrodite combination can be a promising candidate for multilayer SSBs with an LME. However, we show that an optimized LLZO surface treatment and chemical analysis of the interface are recommended for future research.

In Situ Analysis of Interfacial Morphological and Chemical Evolution in All-Solid-State Lithium-Metal Batteries

In situ analysis of Li plating/stripping processes and evolution of solid electrolyte interphase (SEI) are critical for optimizing all-solid-state Li metal batteries (ASSLMB). However, the buried solid-solid interfaces present a challenge for detection which preclude the employment of multiple analysis techniques. Herein, by employing complementary in situ characterizations, morphological/chemical evolution, Li plating/stripping dynamics and SEI dynamics were directly detected. As a mixed ionic-electronic conducting interface, Li|Li10GeP2S12 (LGPS) performed distinct interfacial morphological/chemical evolution and dynamics from ionic-conducting/electronic-isolating interface like Li|Li3PS4 (LPS), which were revealed by combination of in situ atomic force microscopy and in situ X-ray photoelectron spectroscopy. Though Li plating speed in LGPS was higher than LPS, speed of SSE decomposition was similar and ~85 % interfacial SSE turned into SEI during plating and remained unchanged in stripping. To leverage strengths of different SSEs, an LPS-LGPS-LPS sandwich electrolyte was developed, demonstrating enhanced ionic conductivity and improved interfacial stability with less SSE decomposition (25 %). Using in situ Kelvin probe force microscopy, Li-ion behavior at interface between different SSEs was effectively visualized, uncovering distribution of Li ions at LGPS|LPS interface under different potentials.

Oxygen- and proton-transporting open framework ionomer for medium-temperature fuel cells

Medium-temperature proton exchange membrane fuel cells (MT PEMFCs) operating at 100° to 120°C have improved kinetics, simplified thermal and water management, and broadened fuel tolerance compared with low-temperature PEMFCs. However, high temperatures lead to Nafion ionomer dehydration and exacerbate gas transportation limitations. Inspired by osmolytes found in hyperthermophiles, we developed α-aminoketone-linked covalent organic framework (COF) ionomers, interwoven with Nafion, to act as "breathable" proton conductors. This approach leverages synergistic hydrogen bonding to retain water, enhancing hydration and proton transport while reducing oxygen transport resistance. For commercial Pt/C, the MT PEMFCs achieved peak and rated power densities of 18.1 and 9.5 Watts per milligram of Pt at the cathode at 105°C fueled with H2 and air, marking increases of 101 and 187%, respectively, compared with cells lacking the COF.

Field-Driven Solid-State Defect Control of Bilayer Switching Devices

We develop a framework for controlling and investigating reversible ionic transfer between two solid metal oxides layers by examining field-driven changes in electrical properties of the thin film bilayer oxide system Pr0.1Ce0.9O2/La1.85Ce0.15CuO4 (PCO/LCCO). We show that we can reversibly redistribute oxygen ions by applied voltage in a highly controlled and reversible fashion near ambient temperatures over large oxygen ion activity limits, which, for the first time, is directly interpretable by defect chemical models. This allowed us to determine how defect concentrations in each layer systematically varied with voltage and the subsequent impact on each film's conductance. These results showcase the relevance and applicability of defect chemical models, traditionally considered only at elevated temperatures, to the development of bilayer devices of importance to neuromorphic memory applications. This allows for a more systematic approach for studying and understanding the solid-solid exchange process in electrochemically controlled microelectronic devices. Moreover, our work sets the foundation for the development of large-area field-driven defect-controlled bilayer switching devices with potential application to a broad array of functionally modulated devices.

Investigation of Water Impacts on Surface Properties and Performance of Air-Electrode in Reversible Protonic Ceramic Cells

Water, being abundant and readily accessible, gains widespread usage as proton source in many catalysis and energy conversion technologies, including applications like reversible protonic ceramic cells (R-PCCs). Revealing the influence of water on the electrode surface and reaction kinetics is critical for further improving their electrochemical performance. Herein, a hydrophilic air-electrode PrBa0.875Cs0.125Co2O5+δ is developed for R-PCC, which demonstrates a remarkable peak power density of 1058 mW cm-2 in fuel cell mode and a current density of 1354 mA cm-2 under 1.3 V in electrolyzing steam at 650 °C. For the first time on R-PCC, surface protons' behavior in response to external voltages is captured using in situ FTIR characterizations. Further, it is shown that contrary to the bulk proton uptake process that is thought to follow hydrogenation reactions and lead to cation reductions. The air-electrode presents enriched surface protons occurring through oxidizing surface cations, as confirmed by depth-profiling XPS results. H/D isotope exchange experiments and subsequent electrochemical characterization analyses reveal that the presence of protons enhances surface reactions. This study fills the knowledge gap between water-containing atmospheres and electrochemical performance by providing insights into the surface properties of the material. These new findings provide guidance for future electrode design and optimization.

Lithium fluorosulfonate-induced low-resistance interphase boosting low-temperature performance of commercial graphite/LiFePO4 pouch batteries

The performance of Li-ion batteries (LIBs) at sub-ambient temperatures is limited by the resistive interphases due to electrolyte decomposition, particularly on the anode surface. In this study, lithium fluorosulfonate (LFS) was added to commercial electrolytes to enhance the low-temperature electrochemical performance of LiFePO4 (LFP)/graphite (Gr) pouch cells. The addition of LFS significantly reduced the charge transfer resistance of the anode, substantially extending the cycle life and discharge capacity of commercial LFP/Gr pouch cells at -10 and -30 °C. Compared with the capacity retention rate of the baseline electrolyte at -10 °C (80 % after 25cycles), the capacity retention rate of the LFS electrolyte after 100 cycles under 0.5 C/0.5 C was retained at 94 %. Further mechanistic studies showed that the LFS additive induced the formation of a solid electrolyte interphase (SEI) film comprising inorganic-rich LiF, Li2SO4, and additional organic fluorides and sulfides to maintain good stability at the Gr/electrolyte interface during low-temperature operation. LFS suppressed electrolyte decomposition by forming a robust and low-resistance SEI film on the anode. These results demonstrate that LFS is a promising electrolyte additive for low-temperature LFP/Gr pouch cells.

Pressure Tuning and Sn Particle Size Optimization for Enhanced Performance in PbSnF4-Based All-Solid-State Fluoride Ion Batteries

All-solid-state fluoride ion batteries (ASSFIBs) show remarkable potential as energy storage devices due to their low cost, superior safety, and high energy density. However, the poor ionic conductivity of F- conductor, large volume expansion, and the lack of a suitable anode inhibit their development. In this work, PbSnF4 solid electrolytes in different phases (β- and γ-PbSnF4) are successfully synthesized and characterized. The ASSFIBs composed of β-PbSnF4 electrolytes, a BiF3 cathode, and micrometer/nanometer size (µ-/n-) Sn anodes, exhibit substantial capacities. Compared to the μ-Sn anode, the n-Sn anode with nanostructure exhibits superior battery performance in the BiF3/β-PbSnF4/Sn battery. The optimized battery delivers a high initial discharge capacity of 181.3 mAh g-1 at 8 mA g-1 and can be reversibly cycled at 40 mA g-1 with a high discharge capacity of over 100.0 mAh g-1 after 120 cycles at room temperature. Additionally, it displays high discharge capacities over 90.0 mAh g-1 with excellent cyclability over 100 cycles under -20 °C. Detailed characterization has confirmed that reducing Sn particle size and boosting external pressure are crucial for achieving good defluorination/fluorination behaviors in the Sn anode. These findings pave the way to designing ASSFIBs with high capacities and superior cyclability under different operating temperatures.

Scalable, Flexible, Magnetic-Field-Guided rULGO Sponge-BN-Cobalt Oxide-Based Supercapacitors: Mechanistic Insights into Multiple Charge Transfer Pathways by the Distribution of Relaxation Times

Scalable and flexible supercapacitors are in high demand from an application point of view. Through our exploration, we have attained promising performance of electrochemical energy storage under the influence of an external magnetic field for future energy-based applications. In this work, a commercial sponge is used as a template for ultra-large graphene oxide (rULGO) functionalization, followed by the incorporation of Co3O4:BN without the inclusion of binders or conductive additives. The fabricated electrodes, namely, SPG-rULGO and SPG-rULGO-Co3O4:BN, demonstrate superior performance with a potential window of 2.2 V at a magnetic field strength of 13.5 and 28 mT, respectively. A specific capacitance of 218 ± 5% F·g-1 and 312 ± 5% F·g-1, respectively, with retention rates of 80 and 88% over 5000 charge-discharge cycles are achieved. In contrast to the conventional fabrication of the asymmetric device, both electrodes are made using flexible substrates with SPG-rULGO-Co3O4:BN as the positive electrode and SPG-rULGO as the negative electrode eliminating the need to use activated carbon. This configuration yields a specific capacitance of 153 ± 5% F·g-1 at 1 Ag-1, leading to a high energy density of 103 ± 5% W·h·kg-1 at a power density of 1.10 ± 5% kW kg-1 with an 85% retention rate. The charge-discharge mechanism of bare and modified electrodes is probed by the distribution of relaxation time analysis of the coupled electrochemical impedance spectra. The integration of magnetic field with advanced electrode materials opens up other possibilities for optimizing energy storage systems and advancing the field of flexible and mechanically robust supercapacitors.

Designing a Schottky Barrier-Free Interface for a Highly Conductive Anode in Proton Exchange Membrane Water Electrolysis

Iridium, the most widely used anode catalyst in proton exchange membrane water electrolysis (PEMWE), must be used minimally due to its high price and limited supply. However, reducing iridium loading poses challenges due to abnormally large anode polarization. Herein, we present an anode catalyst layer (CL) based on a one-dimensional iridium nanofiber that enables a high current density operation of 3 A cm-2 at 1.86 V, even at an ultralow loading (0.07 mgIr cm-2). The performance is maintained even with a Pt coating-free porous transport layer (PTL) because our nanofiber CL circumvents the interfacial electron transport problem caused by the native oxide on the Ti PTL. We attribute this to the low work function and the low-ionomer-exposed surface of the nanofiber CL, which prevent the formation of Schottky contact at the native oxide interface. These results highlight the significance of optimizing the electronic properties of the CL/PTL interface for low-iridium-loading PEMWE.

Recycling Spent Ternary Cathodes to Oxygen Evolution Catalysts for Pure Water Anion-Exchange Membrane Electrolysis

Recycling spent lithium-ion batteries (LIBs) to efficient water-splitting electrocatalysts is a promising and sustainable technology route for green hydrogen production by renewables. In this work, a fluorinated ternary metal oxide (F-TMO) derived from spent LIBs was successfully converted to a robust water oxidation catalyst for pure water electrolysis by utilizing an anion-exchange membrane. The optimized catalyst delivered a high current density of 3.0 A cm-2 at only 2.56 V and a durability of >300 h at 0.5 A cm-2, surpassing the noble-metal IrO2 catalyst. Such excellent performance benefits from an artificially endowed interface layer on the F-TMO, which renders the exposure of active metal (oxy)hydroxide sites with a stabilized configuration during pure water operation. Compared to other metal oxides (i.e., NiO, Co3O4, MnO2), F-TMO possesses a higher stability number of 2.4 × 106, indicating its strong potential for industrial applications. This work provides a feasible way of recycling waste LIBs to valuable electrocatalysts.

A-site-deficiency range identified for in situ exsolution from (La0.4Sr0.6)1-αTi0.95Ni0.05O3±δ electrodes for SOFC and SOEC

Modulating the A-site deficiency is a useful method to achieve the exsolution of nanoparticles on the surface of perovskite, improving the catalytic activity. However, rules for designing the deficiency value and its roles on the structure and performance remain unclear. In this study, a wide range of A-site deficiencies of (La0.4Sr0.6)1-αTi0.95Ni0.05O3±δ (LSTN, α = 0.00, 0.13, 0.15, and 0.18) titanate perovskite materials was designed to systematically investigate their crystal structure, binding energy, oxygen vacancy concentration, exsolution process, and electrochemical performance. An extremely high conductivity (e.g., 331.75 S cm-1@800 °C, 5% H2/Ar) was obtained in parallel with enhanced catalytical activity in SOFC and SOEC modes. The A-site-deficient samples displayed a higher conductivity, oxygen vacancy concentration, and power output than the stoichiometric samples (α = 0.00). The best maximum power density of 78.74 mW cm-2 and the highest population density of 25 particles per μm2 were obtained on the deficient LSTN with α = 0.13. These findings suggest that LSTN is an exceptionally promising material for solid oxide cell (SOC) electrodes.

Interfacial Dynamics Study of NCM523-Based Semi-Solid-State Lithium-Ion Batteries by Electrochemical Impedance Spectroscopy

The use of solid electrolytes (SE) in solid-state batteries holds the promise of achieving higher energy densities and enhancing safety. However, current solid-state batteries face significant interface impedance issues, mainly dealing with the effect of the evolution of the solid-solid interface on ion transport. Semi-solid-state batteries (SSB), containing a small amount of liquid electrolyte, serve as appropriate transitional products in the development process of solid-state batteries. More importantly, the clarity of the relevant interface dynamics can provide theoretical guidance for the subsequent all-solid-state batteries. Therefore, this paper investigates SSB through Electrochemical Impedance Spectroscopy (EIS), primarily employing a combination of theoretical modeling, simulation predictions, and experimental analyses to elucidate the complex electrochemical processes within these batteries. Based on detailed exploration of the complex electrochemical processes within SSB, we have discovered additional electrochemical processes beyond Li+ penetration through the solid-electrolyte interphase (SEI) film and charge transfer. We attribute the additional electrochemical reaction processes to the resistance present at the SE/SEI interface of SSB on account of numerical analysis and interface characterization. Furthermore, this interface resistance exhibits a trend of initial decrease followed by continuous increase, elucidating the attribution and numerical variations of various impedance components within the EIS. The application of EIS techniques to analyze ion transport processes in SSB serves as a suitable transition toward achieving all-solid-state batteries as well as provides guidance for subsequent interface optimization of solid-state batteries and propels their transition from laboratory experimentation to commercialization.

Empowering Low-Temperature Lithium-Sulfur Batteries: Unlocking the Potential of Transition Metal Alloy-Based Cathode Materials

At low temperatures, lithium-sulfur (Li-S) batteries have poor kinetics, resulting in extreme polarization and decreased capacity. In this study, we investigated the electrochemical performance of Li-S batteries utilizing transition metal alloy-based cathode materials. Specifically, binary transition metal alloys (FeNi, FeCo, and NiCo) are integrated into a porous carbon nanofiber (CNF) matrix as composite cathode material. Our findings reveal that alloying metallic Ni with Fe in the FeNi@CNFs composite enhances the catalytic conversion of sulfur species, mitigating the shuttle effect and improving battery performance even under low temperatures. Li-S batteries employing a Li2S6/FeNi@CNFs cathode exhibited a significantly high initial discharge capacity of 1655 mAh g-1 at 0.1 C. Even at the higher current density of 10 C, the Li2S6/FeNi@CNFs composite can still reach an ultrahigh specific capacity of 828 mAh g-1. In addition, Li2S6/FeNi@CNFs demonstrated exceptional initial discharge capacities of 890.5 and 382.7 mAh g-1 at 0.1 C under -20 and -40 °C, respectively. With an initial capacity of 392.02 mAh g-1 and a capacity retention rate of 88.86% (after 60 cycles) at 0.2 C, the conversion of LiPSs in Li2S6/FeNi@CNFs is significantly enhanced even at ultralow temperatures of -40 °C. The findings of this study hold significant implications for the advancement of extremely low-temperature Li-S batteries.

Pyoverdine binding aptamers and label-free electrochemical detection of pseudomonads

Pyoverdines are iron-chelating siderophores employed by various pseudomonads to promote their growth in iron-limited environments, facilitating both beneficial and detrimental interactions with co-inhabiting microbes or hosts, including plants and animals. The fluorescent pseudomonads produce fluorescent pyoverdines comprised of a conserved central chromophore and a unique strain-specific peptidic side chain produced by non-ribosomal peptide synthetases. Pyoverdine Pf5 (PVD-Pf5) is produced by Pseudomonas protegens Pf-5, a species known for supporting plant growth and its involvement in plant pathogen control. To develop a means of exploring the dynamics of P. protegens activity in soil and in the rhizosphere, we selected DNA aptamers that specifically recognize PVD-Pf5 with high affinities. Two selected aptamers with only 16% identity in sequence were examined for structure and function. We found evidence that both aptamers form structures in their apo-forms and one aptamer has structural features suggesting the presence of a G-quadruplex. Although their tertiary structures are predicted to be different, both aptamers bind the target PVD-Pf5 with similar affinities and do not bind other siderophores, including the related pyoverdine, pseudobactin, produced by Pseudomonas sp. B10. One aptamer binds the pyoverdine peptide component and may also interact with the chromophore. This aptamer was integrated into a nanoporous aluminum oxide biosensor and demonstrated to successfully detect PVD-Pf5 and not to detect other siderophores that do not bind to the aptamer when evaluated in solution. This sensor provides a future opportunity to track the locations of P. protegens around plant roots and to monitor PVD-Pf5 production and movement through the soil.

Synergistic Bulk and Surface Engineering for Expeditious and Durable Reversible Protonic Ceramic Electrochemical Cells Air Electrode

Reversible protonic ceramic electrochemical cells (R-PCECs) offer the potential for high-efficiency power generation and green hydrogen production at intermediate temperatures. However, the commercial viability of R-PCECs is hampered by the sluggish kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) within conventional air electrodes operating at reduced temperatures. To address this challenge, this work introduces a novel approach based on the simultaneous optimization of bulk-phase metal-oxygen bonds and in-situ formation of a metal oxide nano-catalyst surface modification. This strategy is designed to expedite the ORR/OER electrocatalytic activity of air electrodes exhibiting triple (O2-, H+, e-) conductivity. Specifically, this engineered air electrode nanocomposite-Ba(Co0.4Fe0.4Zr0.1Y0.1)0.95Ni0.05F0.1O2.9-δ demonstrates remarkable ORR/OER catalytic activity and exceptional durability in R-PCECs. This is evidenced by significantly improved peak power density from 626 to 996 mW cm-2 and highly stable reversibility over a 100-h cycling period. This research offers a rational design strategy to achieve high-performance R-PCEC air electrodes with superior operational activity and stability for efficient and sustainable energy conversion and storage.

Stabilizing Zn2SiO4 Anode by a Lithium Polyacrylate Binder for Highly Reversible Lithium-Ion Storage

Binders are crucial for maintaining the mechanical stability of the electrodes. However, traditional binders fail to adequately buffer the volume expansion of Zn2SiO4 anode, causing electrode contact failure and considerable capacity loss during cycling. In this study, we propose a simple and effective solution to address these challenges through a combined strategy of hollow structure design and the introduction of an aqueous lithium poly(acrylic acid) (LiPAA) binder. Hollow structures can shorten ion-transfer distance and accommodate volume change outside. The excellent adhesion of the LiPAA binder created a secure connection between the active Zn2SiO4 particles, conductive additives, and the current collector, which enhanced the mechanical stability and integrity of the electrode. As a result of these positive factors, a Zn2SiO4 electrode using LiPAA as a binder can deliver an excellent capacity of 499 mAh g-1 at a high current density of 5 A g-1 and a long life span of 1000 cycles at 1 A g-1 with a capacity retention of 98%, which significantly outperforms other binders. As demonstrated by ex situ X-ray diffraction and ex situ X-ray absorption spectroscopy, the storage of lithium ions in Zn2SiO4 follows a dual conversion-alloying mechanism, using Zn as the redox center. In this process, Zn is first reduced to metallic Zn and then forms a LiZn alloy upon lithium-ion insertion. This work shows that LiPAA offers a promising approach to improve the cycling longevity of conversion and alloying anodes in Li-ion batteries.

Scaffold Infiltrated Cathodes for Low-Temperature Solid Oxide Fuel Cells

Lowering the operating temperature of solid oxide fuel cells (SOFCs) and electrolysis cells (SOECs) to reduce system cost and increase lifetime is the key to widely deploy this highly efficient energy technology, but the high cathode polarization losses at low temperatures limit overall cell performance. Here we demonstrate that by engineering a universal ceria-based scaffold with infiltrated nanoscale electrocatalysts, a low cathode polarization <0.25 Ω·cm2 with remarkably high performance 1 W/cm2 at 550 °C is achieved. The combination of low processing and operating temperature restrains the nanosized electrocatalysts, not only allowing fast oxygen transport but also providing an essential electronically connective network to facilitate electrochemical reactions without requiring the high-temperature processing of a separate cathode layer. Moreover, excellent SOFC durability was demonstrated for over 500 h. This work shows a promising pathway to reduce processing/system costs with all scalable ceramic processing techniques for the future development of low-temperature SOFCs and SOECs.

Coordination engineering for iron-based hexacyanoferrate as a high-stability cathode for sodium-ion batteries

Iron-based hexacyanoferrate (Fe-HCF) are promising cathode materials for sodium-ion batteries (SIBs) due to their unique open-channel structure that facilitates fast ion transport and framework stability. However, practical implementation of SIBs has been hindered by low initial Coulombic efficiency (ICE), poor rate performance, and short lifespan. Herein, we report a coordination engineering to synthesize sodium-rich Fe-HCF as cathodes for SIBs through a uniquely designed 10-kg-scale chemical reactor. Our study systematically investigated the relationship between coordination surroundings and the electrochemical behavior. Building on this understanding, the cathode delivered a reversible capacity of 99.3 mAh g-1 at 5 C (1 C = 100 mA g-1), exceptional rate capability (51 mAh g-1 even at 100 C), long lifespan (over 15,000 times at 50 C), and a high ICE of 92.7%. A full cell comprising the Fe-HCF cathode and hard carbon (HC) anode exhibited an impressive cyclic stability with a high-capacity retention rate of 98.3% over 1,000 cycles. Meanwhile, this material can be readily scaled to the practical levels of yield. The findings underscore the potential of Fe-HCF as cathodes for SIBs and highlight the significance of controlling nucleation and morphology through coordination engineering for a sustainable energy storage system.

Reconstruction of zinc-metal battery solvation structures operating from -50 ~ +100 °C

Serious solvation effect of zinc ions has been considered as the cause of the severe side reactions (hydrogen evolution, passivation, dendrites, and etc.) of aqueous zinc metal batteries. Even though the regulation of cationic solvation structure has been widely studied, effects of the anionic solvation structures on the zinc metal were rarely examined. Herein, co-reconstruction of anionic and cationic solvation structures was realized through constructing a new multi-component electrolyte (Zn(BF4)2-glycerol-boric acid-chitosan-polyacrylamide, simplified as ZGBCP), which incorporates double crosslinking network via the esterification, protonation and polymerization reactions, thereby combining multiple advantages of 'liquid-like' high conductivity, 'gel-like' robust interface, and 'solid-like' high Zn2+ transfer number. Based on the ZGBCP electrolyte, the Zn anodes achieve record-low polarization and stable cycling. Furthermore, the ZGBCP electrolyte renders the AZMBs ultrawide working temperature (-50 °C ~ +100 °C) and ultralong cycle life (30000 cycles), which further validates the feasibility of the dual solvation structure strategy and provides a innovative perspective for the development of high-performance AZMBs.

In Situ Self-Assembled Active and Stable Ir@MnOx/La0.7Sr0.3Cr0.9Ir0.1O3-δ Interfaces for CO2 Electrolysis

Solid oxide electrolysis cells are prospective approaches for CO2 utilization but face significant challenges due to the sluggish reaction kinetics and poor stability of the fuel electrodes. Herein, we strategically addressed the long-standing trade-off phenomenon between enhanced exsolution and improved structural stability via topotactic ion exchange. The surface dynamic reconstruction of the MnOx/La0.7Sr0.3Cr0.9Ir0.1O3-δ (LSCIr) catalyst was visualized at the atomic scale. Compared with the Ir@LSCIr interface, the in situ self-assembled Ir@MnOx/LSCIr interface exhibited greater CO2 activation and easily removable carbonate intermediates, thus reached a 42 % improvement in CO2 electrolysis performance at 1.6 V. Furthermore, an improved CO2 electrolysis stability was achieved due to the uniformly wrapped MnOx shell of the Ir@MnOx/LSCIr cathode. Our approach enables a detailed understanding of the dynamic microstructure evolution at active interfaces and provides a roadmap for the rational design and evaluation of efficient metal/oxide catalysts for CO2 electrolysis.

Reviving Cost-Effective Organic Cathodes in Halide-Based All-Solid-State Lithium Batteries

The evolution of inorganic solid electrolytes has revolutionized the field of sustainable organic cathode materials, particularly by addressing the dissolution problems in traditional liquid electrolytes. However, current sulfide-based all-solid-state lithium-organic batteries still face challenges such as high working temperatures, high costs, and low voltages. Here, we design an all-solid-state lithium battery based on a cost-effective organic cathode material phenanthrenequinone (PQ) and a halide solid electrolyte Li2ZrCl6. Thanks to the good compatibility between PQ and Li2ZrCl6, the PQ cathode achieved a high specific capacity of 248 mAh g-1 (96 % of the theoretical capacity), a high average discharge voltage of 2.74 V (vs. Li+/Li), and a good capacity retention of 95 % after 100 cycles at room temperature (25 °C). Furthermore, the interactions between the high-voltage carbonyl PQ cathode and both sulfide and halide solid electrolytes, as well as the redox mechanism of the PQ cathode in all-solid-state batteries, were carefully studied by a variety of advanced characterizations. We believe such a design and the corresponding investigations into the underlying chemistry give insights for the further development of practical all-solid-state lithium-organic batteries.

Advancing Solid Oxide Fuel Cell Performance: Enhanced Electrochemical Properties of Pr1-xCaxBaFe2O5+δ Nanofiber Cathodes via Ca Doping

The double perovskite oxide PrBaFe2O5+δ has great potential as a cathode material for solid oxide fuel cells (SOFCs). However, the electrochemical characteristics of Fe-based double perovskites are relatively inferior. To improve its electrochemical performance, Ca is investigated to partially replace Pr, forming Pr1-xCaxBaFe2O5+δ (PCBFx, x = 0.0-0.3) by an electrospinning technique. The PCBFx nanofibers exhibited a crystalline structure characterized by orthorhombic symmetry and space group P4/mmm. Furthermore, these PCBFx nanofibers displayed exceptional chemical compatibility with the Sm0.2Ce0.8O1.95 (SDC) electrolyte when sintered at a temperature of 900 °C for 5 h. The X-ray photoelectron spectroscopy (XPS) analysis reveals a progressive increase in the Fe4+ concentration as the Ca doping level rises. The polarization resistances (Rp) of the PCBF00, PCBF01, PCBF02, and PCBF03 nanofiber cathodes were 0.103, 0.079, 0.056, and 0.048 Ω cm2 at 750 °C. In the meantime, doping Ca increases the peak power density of the single cell by 46%, from 762.80 (PCBF00) to 1114.85 (PCBF03) mW cm-2 at 750 °C. The results demonstrate that PCBF03 double perovskite nanofibers exhibit great potential as cathode materials for SOFCs.

Synergistically engineered in-situ self-assembled heterostructure composite nanofiber cathode with superior oxygen reduction reaction catalysis for solid oxide fuel cells

The engineering and exploration of cathode materials to achieve superior oxygen reduction catalytic activity and resistance to CO2 are crucial for enhancing the performance of solid oxide fuel cells (SOFCs). Herein, a novel heterostructure composite nanofiber cathode comprised of PrBa0.5Sr0.5Co2O5+δ and Ce0.8Pr0.2O1.9 (PBSC-CPO-ES) was prepared for the first time through a synergistic approach involving in-situ self-assembly and electrostatic spinning techniques. PBSC-CPO-ES exhibits exceptionally high oxygen reduction catalytic activity and CO2 resistance, which is attributed to its unique nanofiber microstructure and abundant presence of heterointerfaces, significantly accelerating the charge transfer process, surface exchange and bulk diffusion of oxygen. The introduction of CPO not only effectively reduces the thermal expansion of PBSC but also changes the characteristics of oxygen ion transport anisotropy in layered perovskite materials, forming three-dimensional oxygen ion transport pathways. At 750 °C, the single cell employing the PBSC-CPO-ES heterostructure nanofiber attains an impressive peak power density of 1363 mW cm-2. This represents a notable 60.7 % improvement in comparison to the single-phase PBSC powder. Moreover, PBSC-CPO-ES exhibits excellent CO2 tolerance and performance recovery after CO2 exposure. This work provides new perspectives to the design and advancement of future high-performance and high-stability SOFC cathode materials.

Detection of invasive ductal carcinoma in quadrant breast areas by electrical impedance tomography implemented with gaussian relaxation-time distribution (EIT-GRTD)

Invasive ductal carcinoma (IDC) in breast specimens has been detected in the quadrant breast area: (I) upper outer, (II) upper inner, (III) lower inner, and (IV) lower outer areas by electrical impedance tomography implemented with Gaussian relaxation-time distribution (EIT-GRTD). The EIT-GRTD consists of two steps which are (1) the optimum frequencyfoptselection and (2) the time constant enhancement of breast imaging reconstruction.foptis characterized by a peak in the majority measurement pair of the relaxation-time distribution functionγ,which indicates the presence of IDC.γrepresents the inverse of conductivity and indicates the response of breast tissues to electrical currents across varying frequencies based on the Voigt circuit model. The EIT-GRTD is quantitatively evaluated by multi-physics simulations using a hemisphere container of mimic breast, consisting of IDC and adipose tissues as normal breast tissue under one condition with known IDC in quadrant breast area II. The simulation results show that EIT-GRTD is able to detect the IDC in four layers atfopt= 30, 170 Hz. EIT-GRTD is applied in the real breast by employed six mastectomy specimens from IDC patients. The placement of the mastectomy specimens in a hemisphere container is an important factor in the success of quadrant breast area reconstruction. In order to perform the evaluation, EIT-GRTD reconstruction images are compared to the CT scan images. The experimental results demonstrate that EIS-GRTD exhibits proficiency in the detection of the IDC in quadrant breast areas while compared qualitatively to CT scan images.

Self-Assembled Nanocomposite Based on SrCo0.7Fe0.2Sc0.1O3-δ as an Efficient Intermediate-to-Low-Temperature SOFC Cathode

The high performance of intermediate-to-low temperature solid oxide fuel cells (ILT-SOFCs) closely depends on the catalytic activity of the cathode material. However, most high-activity perovskite cathodes are rich in Sr and will arise from Sr segregation during the long-term working, resulting in the decay of activity and stability. Herein, by regulating the calcined way and temperature, a type of self-assembled nanocomposite perovskite cathode is developed, the stoichiometric SrCo0.7Fe0.2Sc0.1O3-δ (SCFSc) powder self-separates into a cubic phase (Pm3̅m, Sc-rich) and a tetragonal phase (P4/mmm, Sc-fewer). Meanwhile, a single cubic phase is prepared with the same formula via calcining the SCFSc pellet. It is found that the nanocomposite cathode shows better oxygen reduction reaction catalytic activity than single cubic SCFSc, caused by lower impedance of oxygen surface exchange and bulk diffusion. Particularly, the nanocomposite SCFSc cathode with the self-assembled heterointerfaces mitigates the Sr segregation and shows a peak power density of 1.17 W cm-2 at 700 °C and excellent stability for ∼101 h at 600 °C. This work provides a strategy for the development of nanocomposite cathodes to mitigate cation segregation and improve catalytic activity and stability.

Highly Crystalline Multivariate Prussian Blue Analogs via Equilibrium Chelation Strategy for Stable and Fast Charging Sodium-Ion Batteries

Prussian blue analogs (PBAs) have been widely recognized as superior cathode materials for sodium-ion batteries (SIBs) owing to numerous merits. However, originating from the rapid crystal growth, PBAs still suffer from considerable vacancy defects and interstitial water, making the preparation of long-cycle-life PBAs the greatest challenge for its practical application. Herein, a novel equilibrium chelation strategy is first proposed to synthesize a high crystallinity (94.7%) PBAs, which is realized by modulating the chelating potency of strong chelating agents via "acid effect" to achieve a moderate chelating effect, forcefully breaking through the bottleneck of poor cyclic stability for PBAs cathodes. Impressively, the as-prepared highly crystalline PBAs represent an unprecedented level of electrochemical performance including ultra-long lifespan (10000 cycles with 86.32% capacity maintenance at 6 A g-1), excellent rate capability (82.0 mAh g-1 at 6 A g-1). Meanwhile, by pairing with commercial hard carbon, the as-prepared PBAs-based SIBs exhibit high energy density (350 Wh kg-1) and excellent capacity retention (82.4% after 1500 cycles), highlighting its promising potential for large-scale energy storage applications.

Stable Photo-Rechargeable Al Battery for Enhancing Energy Utilization

Photovoltaic cells (PVs) are able to convert solar energy to electric energy, while energy storage devices are required to be equipped due to the fluctuations of sunlight. However, the electrical connection of PVs and energy storage devices leads to increased energy consumption, and thus energy storage ability and utilization efficiency are decreased. One of the solutions is to explore an integrated photoelectrochemical energy conversion-storage device. Up to date, the integrated photo-rechargeable Li-ion batteries often suffer from unstable photo-active materials and flammable electrolytes under illumination, with concerns in safety risks and limited lifetime. To address the critical issues, here a novel photo-rechargeable aluminum battery (PRAB) is designed with safe ionic liquid electrolytes and stable polyaniline photo-electrodes. The integrated PRAB presents stable operation with an enhanced reversible specific capacity ≈191% under illumination. Meanwhile, a simplified continuum model is established to provide rational guidance for designing electrode structures along with a charging/discharging strategy to meet the practical operation conditions. The as-designed PRAB presents an energy-saving efficiency ≈61.92% upon charging and an energy output increment ≈31.25% during discharging under illumination. The strategy of designing and fabricating stable and safe photo-rechargeable non-aqueous Al batteries highlights the pathway for substantially promoting the utilization efficiency of solar energy.

Enabling Uniform and Stable Lithium-Ion Diffusion at the Ultrathin Artificial Solid-Electrolyte Interface in Siloxene Anodes

Constructing a stable and robust solid electrolyte interphase (SEI) has a decisive influence on the charge/discharge kinetics of lithium-ion batteries (LIBs), especially for silicon-based anodes which generate repeated destruction and regeneration of unstable SEI films. Herein, a facile way is proposed to fabricate an artificial SEI layer composed of lithiophilic chitosan on the surface of two-dimensional siloxene, which has aroused wide attention as an advanced anode for LIBs due to its special characteristics. The optimized chitosan-modified siloxene anode exhibits an excellent reversible cyclic stability of about 672.6 mAh g-1 at a current density of 1000 mA g-1 after 200 cycles and 139.9 mAh g-1 at 6000 mA g-1 for 1200 cycles. Further investigation shows that a stable and LiF-rich SEI film is formed and can effectively adhere to the surface during cycling, redistribute lithium-ion flux, and enable a relatively homogenous lithium-ion diffusion. This work provides constructive guidance for interface engineering strategy of nano-structured silicon anodes.

In-situ electrochemical impedance analysis of a commercial SOFC stack fueled by real wood gas

The combination of solid oxide fuel cells (SOFCs) and wood gasification has the potential to significantly increase renewable electricity production and decrease emissions. Depending on the quality of the wood gas, degradation processes have a significant impact on the reliability and lifetime of the SOFC. Using electrochemical impedance spectroscopy (EIS) and subsequent distribution of relaxation times (DRT) analysis, the impact on the degradation of coupling wood gasification with a commercial SOFC stack is determined in this study. The thermal behavior of the SOFC stack under various operating conditions, as well as various synthetic wood gas mixtures classified by their hydrogen-to-carbon (H/C) ratio, was assessed. The decrease in the H/C ratio from 8 to 1, observed during syngas and real wood gas operation, leads to a rightward shift in the Nyquist plots, suggesting an increase in the SOFC stack's impedance. Correlations between variations in the H/C ratio and their effects on anodic electrooxidation, ionic conduction, gas transport, and diffusion were identified using DRT analysis to interpret the EIS results. By incorporating an upstream desulfurization system and ensuring an H/C ratio greater than 2, the coupling of biomass gasification with the SOFC stack was stable to degradation issues.

Regulating Pseudo-Graphitic Domain and Closed Pores to Facilitate Plateau Sodium Storage Capacity and Kinetics for Hard Carbon

Hard carbon anode demonstrates exceptional potential in sodium-ion batteries due to their cost-effectivenss and superior plateau capacity. However, the proximity of the plateau capacity to the cut-off voltage of battery operation and the premature cut-off voltage response caused by polarization at high rates greatly limit the exploitation of plateau capacities, raising big concerns about inferior rate performance of high-plateau-capacity hard carbon. In this work, a facile pre-oxidation strategy is proposed for fabricating lignin-derived hard carbon. Both high-plateau capacity and sodiation kinetics are significantly enhanced due to the introduction of expanded pseudo-graphitic domains and high-speed closed pores. Impressively, the optimized hard carbon exhibits an increased reversible capacity from 252.1 to 302.0 mAh g-1, alongside superior rate performance (174.7 mAh g-1 at 5 C) and stable cyclability over 500 cycles. This study paves a low-cost and effective pathway to modulate the microstructure of biomass-derived hard carbon materials for facilitating plateau sodium storage kinetics.

A Plastic-Crystal Electrolyte Layer Promotes Interfacial Stability of Ni-Rich Oxide Cathode in Li6PS5Cl-Based All-Solid-State Rechargeable Li Batteries

Unfavorable parasitic reactions between the Ni-rich layered oxide cathode and the sulfide solid electrolyte have plagued the realization of all-solid-state rechargeable Li batteries. The accumulation of inactive by-products (P2Sx, S, POx n- and SOx n-) at the cathode-sulfide interface impedes fast Li-ion transfer, which accounts for sluggish reaction kinetics and significant loss of cathode capacity. Herein, we proposed an easily scalable approach to stabilize the cathode electrochemistry via coating the cathode particles by a uniform, Li+-conductive plastic-crystal electrolyte nanolayer on their surface. The electrolyte, which simply consists of succinonitrile and Li bis(trifluoromethanesulphonyl)imide, serves as an interfacial buffer to effectively suppress the adverse phase transition in highly delithiated cathode materials, and the loss of lattice oxygen and generation of inactive oxygenated by-products at the cathode-sulfide interface. Consequently, an all-solid-state rechargeable Li battery with the modified cathode delivers high specific capacities of 168 mAh g-1 at 0.1 C and a high capacity retention >80 % after 100 cycles. Our work sheds new light on rational design of electrode-electrolyte interface for the next-generation high-energy batteries.

Difluoroester solvent toward fast-rate anion-intercalation lithium metal batteries under extreme conditions

Anion-intercalation lithium metal batteries (AILMBs) are appealing due to their low cost and fast intercalation/de-intercalation kinetics of graphite cathodes. However, the safety and cycliability of existing AILMBs are constrained by the scarcity of compatible electrolytes. Herein, we showcase that a difluoroester can be applied as electrolyte solvent to realize high-performance AILMBs, which not only endows high oxidation resistance, but also efficiently tunes the solvation shell to enable highly reversible and kinetically fast cathode reaction beyond the trifluoro counterpart. The difluoroester-based electrolyte demonstrates nonflammability, high ionic conductivity, and electrochemical stability, along with excellent electrode compatibility. The Li| |graphite AILMBs reach a high durability of 10000 cycles with only a 0.00128% capacity loss per cycle under fast-cycling of 1 A g-1, and retain ~63% of room-temperature capacity when discharging at -65 °C, meanwhile supply stable power output under deformation and overcharge conditions. The electrolyte design paves a promising path toward fast-rate, low-temperature, durable, and safe AILMBs.

In Situ Polymerization Bi-Functional Gel Polymer Electrolyte for High Performance Quasi-Solid-State Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries are expected to be the next-generation energy storage system due to the ultrahigh theoretical energy density and low cost. However, the notorious shuttle effect of higher-order polysulfides and the uncontrollable lithium dendrite growth are the two biggest challenges for commercially viable Li-S batteries. Herein, these two main challenges are solved by in situ polymerization of bi-functional gel polymer electrolyte (GPE). The initiator (SiCl4) not only drives the polymerization of 1,3-dioxolane (DOL) but also induces the construction of a hybrid solid electrolyte interphase (SEI) with inorganic-rich compositions on the Li anode. In addition, diatomaceous earth (DE) is added and anchored in the GPE to obtain PDOL-SiCl4-DE electrolyte through in situ polymerization. Combined with density functional theory (DFT) calculations, the hybrid SEI provides abundant adsorption sites for the deposition of Li+, inhibiting the growth of lithium dendrites. Meanwhile, the shuttle effect is greatly alleviated due to the strong adsorption capacity of DE toward lithium polysulfides. Therefore, the Li/Li symmetric cell and Li-S full cell assembled with PDOL-SiCl4-DE exhibit excellent cycling stability. This study offers a valuable reference for the development of high performance and safe Li-S batteries.

Multidimensional Electrochemistry Decodes the Operando Mechanism of Hydrogen Oxidation

Being an efficient approach to the utilization of hydrogen energy, the hydrogen oxidation reaction (HOR) is of particular significance in the current carbon-neutrality time. Yet the mechanistic picture of the HOR is still blurred, mostly because the elemental steps of this reaction are rapid and highly entangled, especially when deviating from the thermodynamic equilibrium state. Here we report a strategy for decoding the HOR mechanism under operando conditions. In addition to the wide-potential-range I-V curves obtained using gas diffusion electrodes, we have applied the AC impedance spectroscopy to provide independent and complementary kinetic information. Combining multidimensional data sources has enabled us to fit, in mathematical rigor, the core kinetic parameter set in a 5-D data space. The reaction rate of the three elemental steps (Tafel, Heyrovsky, and Volmer reactions), as a function of the overpotential, can thus be distilled individually. Such an undocumented kinetic picture unravels, in detail, how the HOR is controlled by the elemental steps on polarization. For instance, at low polarization region, the Heyrovsky reaction is relatively slow and can be ignored; but at high polarization region, the Heyrovsky reaction will surpass the Tafel reaction. Additionally, the Volmer reaction has been the fastest within overpotentials of interest. Our findings not only offer a better understanding of the HOR mechanism, but also lay the foundation for the development of improved hydrogen energy utilization systems.

The Potential Regulation of Working Anode for Long-Term Zero-Volt Storage at 37 °C in Li-Ion Batteries

The advanced lithium-ion batteries that can tolerate zero-volt storage (ZVS) are in high demand for implantable medical devices and spacecraft. However, ZVS can raise the anode potential, leading to Cu current collector dissolution and solid-electrolyte interphase (SEI) degradation, especially at 37 °C. In this contribution, by quantitatively regulating the dosage of Li6CoO4 cathode additives, controllable potential of the working anode under abusive-discharge conditions is demonstrated. The addition of Li6CoO4 keeps zero-crossing potential (ZCP) and the potential of ZVS below 2.0 V (vs Li/Li+) for LiCoO2|mesocarbon microbead cells at 37 °C. The capacity retention ratio (CRR) increases from 69.1% and 35.9% to 98.6% and 90.8% after 10 and 20 days of ZVS, respectively. The Cu dissolution and SEI degradation are effectively suppressed, while the over-lithiated cathode exhibits high reversible capacity after ZVS. The limiting conditions of long-term ZVS are further explored and a corresponding guide map is designed. When quantitatively regulating ZCP and the potential in ZVS, Cu dissolution, SEI degradation, and irreversible conversion of the cathode constitute the limiting conditions. This contribution designs the most reasonable potential range for ZVS protection at 37 °C, and realizes the best CRR record through precise potential regulation for the first time.

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 ≈400 h. 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., 418 mW cm-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.

Cation-Loaded Porous Mg2+-Zeolite Layer Direct Dendrite-Free Deposition toward Long-Life Lithium Metal Anodes

Lithium metal, with ultrahigh theoretical specific capacity, is considered as an ideal anode material for the lithium-ion batteries. However, its practical application is severely plagued by the uncontrolled formation of dendritic Li. Here, a cation-loaded porous Mg2+-Zeolite layer is proposed to enable the dendrite-free deposition on the surface of Li metal anode. The skeleton channels of zeolite provide the low coordinated Li+-solvation groups, leading to the faster desolvation process at the interface. Meanwhile, anions-involved solvation sheath induces a stable, inorganic-rich SEI, contributing to the uniform Li+ flux through the interface. Furthermore, the co-deposition of sustained release Mg2+ realizes a new faster migration pathway, which proactively facilitates the uniform diffusion of Li on the lithium substrate. The synergistic modulation of these kinetic processes facilitates the homogeneous Li plating/stripping behavior. Based on this synergistic mechanism, the high-efficiency deposition with cyclic longevity exceeding 2100 h is observed in the symmetric Li/Li cell with Mg2+-Zeolite modified anode at 1 mA cm-2. The pouch cell matched with LiFePO4 cathode fulfills a capacity retention of 88.4% after 100 cycles at a severe current density of 1 C charge/discharge. This synergistic protective mechanism can give new guidance for realizing the safe and high-performance Li metal batteries.

Role of Intragap States in Sensitized Sb-Doped Tin Oxide Photoanodes for Solar Fuels Production

In view of developing photoelectrosynthetic cells which are able to store solar energy in chemical bonds, water splitting is usually the reaction of choice when targeting hydrogen production. However, alternative approaches can be considered, aimed at substituting the anodic reaction of water oxidation with more commercially capitalizable oxidations. Among them, the production of bromine from bromide ions was investigated long back in the 1980s by Texas Instruments. Herein we present optimized perylene-diimide (PDI)-sensitized antimony-doped tin oxide (ATO) photoanodes enabling the photoinduced HBr splitting with >4 mA/cm2 photocurrent densities under 0.1 W/cm2 AM1.5G illumination and 91 ± 3% faradaic efficiencies for bromine production. These remarkable results, among the best currently reported for the photoelectrochemical Br- oxidation by dye sensitized photoanodes, are strongly related to the occupancy extent of ATO's intragap (IG) states, generated upon Sb-doping, as demonstrated by comparing their performances with PDI-sensitized analogues on both undoped SnO2- and TiO2-passivated ATO scaffolds by means of (spectro)electrochemistry and electrochemical impedance spectroscopy. The architecture of the ATO-PDI photoanodic assembly was further modified via the introduction of a molecular iridium-based water oxidation catalyst, thus proving the versatility of the proposed hybrid interfaces as photoanodic platforms for photoinduced oxidations in PEC devices.

Unlocking iron metal as a cathode for sustainable Li-ion batteries by an anion solid solution

Traditional cathode chemistry of Li-ion batteries relies on the transport of Li-ions within the solid structures, with the transition metal ions and anions acting as the static components. Here, we demonstrate that a solid solution of F- and PO43- facilitates the reversible conversion of a fine mixture of iron powder, LiF, and Li3PO4 into iron salts. Notably, in its fully lithiated state, we use commercial iron metal powder in this cathode, departing from electrodes that begin with iron salts, such as FeF3. Our results show that Fe-cations and anions of F- and PO43- act as charge carriers in addition to Li-ions during the conversion from iron metal to a solid solution of iron salts. This composite electrode delivers a reversible capacity of up to 368 mAh/g and a specific energy of 940 Wh/kg. Our study underscores the potential of amorphous composites comprising lithium salts as high-energy battery electrodes.

Rational Design of Ruddlesden-Popper Perovskite Ferrites as Air Electrode for Highly Active and Durable Reversible Protonic Ceramic Cells

Reversible protonic ceramic cells (RePCCs) hold promise for efficient energy storage, but their practicality is hindered by a lack of high-performance air electrode materials. Ruddlesden-Popper perovskite Sr3Fe2O7-δ (SF) exhibits superior proton uptake and rapid ionic conduction, boosting activity. However, excessive proton uptake during RePCC operation degrades SF's crystal structure, impacting durability. This study introduces a novel A/B-sites co-substitution strategy for modifying air electrodes, incorporating Sr-deficiency and Nb-substitution to create Sr2.8Fe1.8Nb0.2O7-δ (D-SFN). Nb stabilizes SF's crystal, curbing excessive phase formation, and Sr-deficiency boosts oxygen vacancy concentration, optimizing oxygen transport. The D-SFN electrode demonstrates outstanding activity and durability, achieving a peak power density of 596 mW cm-2 in fuel cell mode and a current density of - 1.19 A cm-2 in electrolysis mode at 1.3 V, 650 °C, with excellent cycling durability. This approach holds the potential for advancing robust and efficient air electrodes in RePCCs for renewable energy storage.

Corrosion Mechanism and Electrochemical Reactions on Alloy 690 in Simulated Primary Coolant of Water-Water Energy Reactors

During the power operation of the primary loop of a water cooled-water moderated energy reactor (WWER), the water chemistry evolves from a high-boron high-potassium composition to significantly lower concentrations of both constituents at the end of a campaign, and the Li concentration reaches ca. 0.7-0.9 ppm. In the present paper, the effect of primary water chemistry evolution during operation on the corrosion rate and conduction mechanism of oxides on Alloy 690 is studied by in situ impedance spectroscopy at 300 °C/9 MPa during 1-week exposures in an autoclave connected to a re-circulation loop. At the end of exposure, the samples were anodically polarized at potentials -0.8 to -0.1 V vs. SHE to evaluate the stability of the passive oxide. Simultaneously exposed samples of Alloy 690 were subsequently analyzed by XPS to estimate the thickness and in-depth composition of oxides. Impedance data were quantitatively interpreted using the mixed-conduction model (MCM) for oxide films. The effect of water chemistry evolution on the corrosion rate and conduction mechanism in the oxide on Alloy 690 in a primary coolant is discussed based on the obtained parameters.

Heteroionic Interfaces in Hybrid Solid-State Batteries─Current Constriction at the Interface between Different Solid Electrolytes

The requirements for suitable electrolyte materials in solid-state batteries are diverse and vary greatly depending on their role as separator or as part of the composite cathode. Hybrid cell concepts that incorporate different types of solid electrolytes are considered a promising solution to overcome the limitations of single material classes. However, the kinetics at the heteroionic interface (i.e., charge transfer) substantially affects the cell performance. Moreover, non-ideal physical contacts hinder detailed electrochemical characterization of the interface properties. Thus, we use microstructure-resolved electric network computations to explore how the impedance response of a homogeneous bilayer system is influenced by the interface morphology and the material parameters of the single solid electrolyte layers. Porous interfaces and the resulting current constriction effects give rise to signatures in the impedance spectrum that resemble that of actual migration processes. This hinders unequivocal identification of the origin of the impedance contributions. The resistance and capacitance of this geometric interface signal depend strongly on the contact area and its spatial distribution, the pore capacitance, and the local conductivities around the interface. An experimental case study of an oxide-sulfide multilayer is considered to highlight the challenges in impedance analysis and the assessment of reliable material parameters. These findings are universal and apply to any heterojunction.

An excellent bismuth-doped perovskite cathode with high activity and CO2 resistance for solid-oxide fuel cells operating below 700 °C

Lowering the operating temperatures of solid-oxide fuel cells (SOFCs) is critical, although achieving success in this endeavor has proven challenging. Herein, Bi0.15Sr0.85Co0.8Fe0.2O3-δ (BiSCF) is systematically evaluated as a carbon dioxide (CO2)-tolerant and highly active cathode for SOFCs. BiSCF, which features Bi3+ with an ionic radius similar to Ba2+, exhibits activity (e.g., 0.062 Ω cm2 at 700 °C) comparable to that of Ba0.5Sr0.5Co0.8Fe0.2O3-δ and PrBaCo2O5+δ, while demonstrating a considerable advantage over Bi-doped cathodes. Moreover, BiSCF exhibits long-term stability over a period of 500 h, and an anode-supported cell with BiSCF achieves a power density of 912 mW cm-2 at 650 °C. The CO2-poisoned BiSCF exhibits quick reversibility or slight activation after returning to normal conditions. The exceptional CO2 tolerance of BiSCF can be attributed to its reduced basicity and high electronegativity, which effectively restrict surface Sr diffusion and hinder subsequent carbonate formation. These findings highlight the substantial potential of BiSCF for SOFCs operating below 700 °C.

Stabilizing BiVO4 Photoanode in Bicarbonate Electrolyte for Efficient Photoelectrocatalytic Alcohol Oxidation

In order to expand the application of bismuth vanadate (BiVO4) to the field of photoelectrochemistry, researchers have explored the potential of BiVO4 in catalyzing or degrading organic substances, potentially presenting a green and eco-friendly solution. A study was conducted to investigate the impact of electrolytes on the photocatalysis of benzyl alcohol by BiVO4. The research discovered that, in an acetonitrile electrolyte (pH 9) with sodium bicarbonate, BiVO4 catalyzed benzyl alcohol by introducing saturated V5+. This innovation addressed the issue of benzyl alcohol being susceptible to catalysis in an alkaline setting, as V5+ was prone to dissolution in pH 9 on BiVO4. The concern of the photocorrosion of BiVO4 was mitigated through two approaches. Firstly, the incorporation of a non-aqueous medium inhibited the formation of active material intermediates, reducing the susceptibility of the electrode surface to photocorrosion. Secondly, the presence of saturated V5+ further deterred the leaching of V5+. Concurrently, the production of carbonate radicals by bicarbonate played a vital role in catalyzing benzyl alcohol. The results show that, in this system, BiVO4 has the potential to oxidize benzyl alcohol by photocatalysis.