Design Principles and Routes for Calcium Alkoxyaluminate Electrolytes.

Multivalent-ion battery technologies are increasingly attractive options for meeting diverse energy storage needs. Calcium ion batteries (CIB) are particularly appealing candidates for their earthly abundance, high theoretical volumetric energy density, and relative safety advantages. At present, only a few Ca-ion electrolyte systems are reported to reversibly plate at room temperature: for example, aluminates and borates, including Ca[TPFA]2, where [TPFA]- = [Al(OC(CF3)3)4]- and Ca[B(hfip)4]2, [B(hfip)4]2- = [B(OCH(CF3)2)4]-. Analyzing the structure of these salts reveals a common theme: the prevalent use of a weakly coordinating anion (WCA) consisting of a tetracoordinate aluminum/boron (Al/B) center with fluorinated alkoxides. Leveraging the concept of theory-aided design, we report an innovative, one-pot synthesis of two new calcium-ion electrolyte salts (Ca[Al(tftb)4]2, Ca[Al(hftb)4]2) and two reported salts (Ca[Al(hfip)4]2 and Ca[TPFA]2) where hfip = (-OCH(CF3)2), tftb = (-OC(CF3)(Me)2), hftb = (-OC(CF3)2(Me)), [TPFA]- = [Al(OC(CF3)3)4]-. We also reveal the dependence of Coulombic efficiency on their inherent propensity for cation-anion coordination.

Self-terminating, heterogeneous solid-electrolyte interphase enables reversible Li-ether cointercalation in graphite anodes.

Ether solvents are suitable for formulating solid-electrolyte interphase (SEI)-less ion-solvent cointercalation electrolytes in graphite for Na-ion and K-ion batteries. However, ether-based electrolytes have been historically perceived to cause exfoliation of graphite and cell failure in Li-ion batteries. In this study, we develop strategies to achieve reversible Li-solvent cointercalation in graphite through combining appropriate Li salts and ether solvents. Specifically, we design 1M LiBF4 1,2-dimethoxyethane (G1), which enables natural graphite to deliver ~91% initial Coulombic efficiency and >88% capacity retention after 400 cycles. We captured the spatial distribution of LiF at various length scales and quantified its heterogeneity. The electrolyte shows self-terminated reactivity on graphite edge planes and results in a grainy, fluorinated pseudo-SEI. The molecular origin of the pseudo-SEI is elucidated by ab initio molecular dynamics (AIMD) simulations. The operando synchrotron analyses further demonstrate the reversible and monotonous phase transformation of cointercalated graphite. Our findings demonstrate the feasibility of Li cointercalation chemistry in graphite for extreme-condition batteries. The work also paves the foundation for understanding and modulating the interphase generated by ether electrolytes in a broad range of electrodes and batteries.

Regulating Li Nucleation and Growth Heterogeneities via Near-Surface Lithium-Ion Irrigation for Stable Anode-Less Lithium Metal Batteries.

The inhomogeneous nucleation and growth of Li dendrite combined with the spontaneous side reactions with the electrolytes dramatically challenge the stability and safety of Li metal anode (LMA). Despite tremendous endeavors, current success relies on the use of significant excess of Li to compensate the loss of active Li during cycling. Herein, a near-surface Li+ irrigation strategy is developed to regulate the inhomogeneous Li deposition behavior and suppress the consequent side reactions under limited Li excess condition. The conformal polypyrrole (PPy) coating layer on Cu surface via oxidative chemical vapor deposition technique can induce the migration of Li+ to the interregional space between PPy and Cu, creating a near-surface Li+-rich region to smooth diffusion of ion flux and uniform the deposition. Moreover, as evidenced by multiscale characterizations including synchrotron high-energy X-ray diffraction scanning, a robust N-rich solid-electrolyte interface (SEI) is formed on the PPy skeleton to effectively suppress the undesired SEI formation/dissolution process. Strikingly, stable Li metal cycling performance under a high areal capacity of 10 mAh cm-2 at 2.0 mA cm-2 with merely 0.5 × Li excess is achieved. The findings not only resolve the long-standing poor LMA stability/safety issues, but also deepen the mechanism understanding of Li deposition process.

Electrolyte Reactivity on the MgV2O4 Cathode Surface.

Predictive understanding of the molecular interaction of electrolyte ions and solvent molecules and their chemical reactivity on electrodes has been a major challenge but is essential for addressing instabilities and surface passivation that occur at the electrode-electrolyte interface of multivalent magnesium batteries. In this work, the isolated intrinsic reactivities of prominent chemical species present in magnesium bis(trifluoromethanesulfonimide) (Mg(TFSI)2) in diglyme (G2) electrolytes, including ionic (TFSI-, [Mg(TFSI)]+, [Mg(TFSI):G2]+, and [Mg(TFSI):2G2]+) as well as neutral molecules (G2) on a well-defined magnesium vanadate cathode (MgV2O4) surface, have been studied using a combination of first-principles calculations and multimodal spectroscopy analysis. Our calculations show that nonsolvated [Mg(TFSI)]+ is the strongest adsorbing species on the MgV2O4 surface compared with all other ions while partially solvated [Mg(TFSI):G2]+ is the most reactive species. The cleavage of C-S bonds in TFSI- to form CF3- is predicted to be the most desired pathway for all ionic species, which is followed by the cleavage of C-O bonds of G2 to yield CH3+ or OCH3- species. The strong stabilization and electron transfer between ionic electrolyte species and MgV2O4 is found to significantly favor these decomposition reactions on the surface compared with intrinsic gas-phase dissociation. Experimentally, we used state-of-the-art ion soft landing to selectively deposit mass-selected TFSI-, [Mg(TFSI):G2]+, and [Mg(TFSI):2G2]+ on a MgV2O4 thin film to form a well-defined electrolyte-MgV2O4 interface. Analysis of the soft-landed interface using X-ray photoelectron, X-ray absorption near-edge structure, electron energy-loss spectroscopies, as well as transmission electron microscopy confirmed the presence of decomposition species (e.g., MgFx, carbonates) and the higher amount of MgFx with [Mg(TFSI):G2]+ formed in the interfacial region, which corroborates the theoretical observation. Overall, these results indicate that Mg2+ desolvation results in electrolyte decomposition facilitated by surface adsorption, charge transfer, and the formation of passivating fluorides on the MgV2O4 cathode surface. This work provides the first evidence of the primary mechanisms leading to electrolyte decomposition at high-voltage oxide surfaces in multivalent batteries and suggests that the design of new, anodically stable electrolytes must target systems that facilitate cation desolvation.

Are We Truly Safe? Unfolding the Final Chapters of COVID-19 Walk-Through Booths.

This research proposes a safety strategy for coronavirus disease 2019 (COVID-19) walk-through booths to optimize pandemic preparedness. These booths, designed for respiratory sample collection during the COVID-19 pandemic, effectively reduce infection risk and personal protective equipment-related fatigue among healthcare workers. However, inadequate disinfection and glove management could escalate infection transmission. Using computational fluid dynamics simulations, we analyzed droplet dispersion on booth surfaces and gloves under various wind conditions. Our findings suggest that when setting up COVID-19 walk-through booths, their location should be strategically chosen to minimize the effects of wind. All surfaces of booth gloves must be thoroughly disinfected with a certified disinfectant after nasopharyngeal swab collection. It is also recommended to wear disposable gloves over booth gloves when changing between patient examinations. In wind-affected areas, individuals nearby should not solely rely on the 2-meter distancing rule due to potential droplet spread from walk-through booths. We strongly recommend consistent and proper mask use for effective droplet blocking. Adherence to these guidelines can significantly enhance the safety and efficiency of walk-through booths, particularly in potential future pandemics.

Multifunctional Effect of Fe Substitution in Na Layered Cathode Materials for Enhanced Storage Stability.

Developing stable cathode materials that are resistant to storage degradation is essential for practical development and industrial processing of Na-ion batteries as many sodium layered oxide materials are susceptible to hygroscopicity and instability upon exposure to ambient air. Among the various layered compounds, Fe-substituted O3-type Na(Ni1/2Mn1/2)1-xFexO2 materials have emerged as a promising option for high-performance and low-cost cathodes. While previous reports have noted the decent air-storage stability of these materials, the role and origin of Fe substitution in improving storage stability remain unclear. In this study, we investigate the air-resistant effect of Fe substitution in O3-Na(Ni1/2Mn1/2)1-xFexO2 cathode materials by performing systematic surface and structural characterizations. We find that the improved storage stability can be attributed to the multifunctional effect of Fe substitution, which forms a surface protective layer containing an Fe-incorporated spinel phase and decreases the thermodynamical driving force for bulk chemical sodium extraction. With these mechanisms, Fe-containing cathodes can suppress the cascades of cathode degradation processes and better retain the electrochemical performance after air storage.

Suppressing Universal Cathode Crossover in High-Energy Lithium Metal Batteries via a Versatile Interlayer Design.

The universal cathode crossover such as chemical and oxygen has been significantly overlooked in lithium metal batteries using high-energy cathodes which leads to severe capacity degradation and raises serious safety concerns. Herein, a versatile and thin (≈25 µm) interlayer composed of multifunctional active sites was developed to simultaneously regulate the Li deposition process and suppress the cathode crossover. The as-induced dual-gradient solid-electrolyte interphase combined with abundant lithiophilic sites enable stable Li stripping/plating process even under high current density of 10 mA cm-2 . Moreover, X-ray photoelectron spectroscopy and synchrotron X-ray experiments revealed that N-rich framework and CoZn dual active sites can effectively mitigate the undesired cathode crossover, hence significantly minimizing Li corrosion. Therefore, assembled lithium metal cells using various high-energy cathode materials including LiNi0.7 Mn0.2 Co0.1 O2 , Li1.2 Co0.1 Mn0.55 Ni0.15 O2 , and sulfur demonstrate significantly improved cycling stability with high cathode loading.

Computational Predictions of the Stability of Fluorinated Calcium Aluminate and Borate Salts.

Energy storage concepts based on multivalent ions, such as calcium, have great potential to become next-generation batteries due to their low cost and comparable cell voltage and energy density to Li-ion batteries. However, the development of Ca batteries is still hindered by the lack of suitable materials that grant a long cycle life. Specific to electrolyte materials, developing a calcium salt that is chemically stable under ambient conditions and enables reversible electrodeposition of Ca is critical. In this work, we use first-principles calculations to study the intrinsic and reductive stability of twelve Ca salts with fluorinated aluminate and borate anions and analyze the decomposition products formed on the metal anode surface that are critical to early-stage solid electrolyte interphase formation. We found anions with significant steric hindrance and a high degree of fluorination are intrinsically less stable and deemed unviable designs for Ca salt. Aluminate salts are generally less reactive with the Ca anode than their borate counterparts, and a high degree of fluorination leads to weaker reductive stability. Calcium fluoride is the most prominent decomposition product on the anode surface, and carbide-like motifs were also found from the decomposition of the designed salts.

Formation and impact of nanoscopic oriented phase domains in electrochemical crystalline electrodes.

Electrochemical phase transformation in ion-insertion crystalline electrodes is accompanied by compositional and structural changes, including the microstructural development of oriented phase domains. Previous studies have identified prevailingly transformation heterogeneities associated with diffusion- or reaction-limited mechanisms. In comparison, transformation-induced domains and their microstructure resulting from the loss of symmetry elements remain unexplored, despite their general importance in alloys and ceramics. Here, we map the formation of oriented phase domains and the development of strain gradient quantitatively during the electrochemical ion-insertion process. A collocated four-dimensional scanning transmission electron microscopy and electron energy loss spectroscopy approach, coupled with data mining, enables the study. Results show that in our model system of cubic spinel MnO2 nanoparticles their phase transformation upon Mg2+ insertion leads to the formation of domains of similar chemical identity but different orientations at nanometre length scale, following the nucleation, growth and coalescence process. Electrolytes have a substantial impact on the transformation microstructure ('island' versus 'archipelago'). Further, large strain gradients build up from the development of phase domains across their boundaries with high impact on the chemical diffusion coefficient by a factor of ten or more. Our findings thus provide critical insights into the microstructure formation mechanism and its impact on the ion-insertion process, suggesting new rules of transformation structure control for energy storage materials.

Strong Isotopic Fractionation of Oxygen in TiO2 Obtained by Surface-Enhanced Solid-State Diffusion.

Isotopically pure semiconductors have important applications for cooling electronic devices and quantum computing and sensing. Raw materials of sufficiently high isotopic purity are expensive and difficult to obtain; therefore, a post-synthesis method for removing isotopic impurities would be valuable. Through isotopic self-diffusion measurements of oxygen in rutile TiO2 single crystals immersed in water, we demonstrate fractionation of 18O by a factor of 3 below natural abundance in a near-surface region up to 10 nm wide. The submerged surface injects O interstitials that displace lattice 18O deeper into the solid as a result of the statistics of interstitialcy-mediated diffusion combined with steep chemical gradients of O interstitials. Slightly acidic and slightly basic liquid solutions both enhance the fractionation and affect the details of isotopic profile shapes through several chemical and physical mechanisms.

Surface-Based Post-synthesis Manipulation of Point Defects in Metal Oxides Using Liquid Water.

Initial synthesis of semiconducting oxides leaves behind poorly controlled concentrations of unwanted atomic-scale defects that influence numerous electrical, optical, and reactivity properties. We have discovered through self-diffusion measurements and first-principles computations that poison-free oxide surfaces inject interstitial oxygen atoms into the crystalline solid when simply contacted with liquid water near room temperature. These interstitials diffuse quickly to depths of 20 nm-2 µm and are likely to eliminate prominent classes of unwanted defects or neutralize their action. The mild conditions of operation access a regime for oxide fabrication that relaxes important thermodynamic constraints that hamper defect regulation by conventional methods at higher temperatures. The surface-based approach appears well-suited for use with nanoparticles, porous oxides, and thin films for applications in advanced electronics, renewable energy storage, photocatalysis, and photoelectrochemistry.

Mechanism of creation and destruction of oxygen interstitial atoms by nonpolar zinc oxide(101[combining macron]0) surfaces.

Oxygen vacancies (VO) influence many properties of ZnO in semiconductor devices, yet synthesis methods leave behind variable and unpredictable VO concentrations. Oxygen interstitials (Oi) move far more rapidly, so post-synthesis introduction of Oi to control the VO concentration would be desirable. Free surfaces offer such an introduction mechanism if they are free of poisoning foreign adsorbates. Here, isotopic exchange experiments between nonpolar ZnO(101[combining macron]0) and O2 gas, together with mesoscale modeling and first-principles calculations, point to an activation barrier for injection only 0.1-0.2 eV higher than for bulk site hopping. The modest barrier for hopping in turn enables diffusion lengths of tens to hundreds of nanometers only slightly above room temperature, which should facilitate defect engineering under very modest conditions. In addition, low hopping barriers coupled with statistical considerations lead to important qualitative manifestations in diffusion via an interstitialcy mechanism that does not occur for vacancies.

Kinetic Control of Oxygen Interstitial Interaction with TiO2(110) via the Surface Fermi Energy.

Atomically clean surfaces of semiconducting oxides efficiently mediate the interconversion of gas-phase O2 and solid-phase oxygen interstitial atoms (Oi). First-principles calculations together with mesoscale microkinetic modeling are employed for TiO2(110) to determine reaction pathways, assess appropriate rate expressions, and obtain corresponding activation energies and pre-exponential factors. The Fermi energy (EF) at the surface influences the rate-determining step for both injection and annihilation of Oi. The barriers range between 0.72-0.82 eV for injection and 0.60-2.34 eV for annihilation and may be manipulated through intentional control of EF. At equilibrium, the microkinetic model and first-principles calculations indicate that interconversion of Oi species in the first and second sublayers limits the rate. The effective pre-exponential factors for injection and annihilation are surprisingly low, probably resulting from the use of simple Langmuir-like rate expressions to describe a complicated kinetic sequence.

Fermi level dependence of gas-solid oxygen defect exchange mechanism on TiO2 (110) by first-principles calculations.

In the same way that gases interact with oxide semiconductor surfaces from above, point defects interact from below. Previous experiments have described defect-surface reactions for TiO2(110), but an atomistic picture of the mechanism remains unknown. The present work employs computations by density functional theory of the thermodynamic stabilities of metastable states to elucidate possible reaction pathways for oxygen interstitial atoms at TiO2(110). The simulations uncover unexpected metastable states including dumbbell and split configurations in the surface plane that resemble analogous interstitial species in the deep bulk. Comparison of the energy landscapes involving neutral (unionized) and charged intermediates shows that the Fermi energy EF exerts a strong influence on the identity of the most likely pathway. The largest elementary-step thermodynamic barrier for interstitial injection trends mostly downward by 2.1 eV as EF increases between the valence and conduction band edges, while that for annihilation trends upward by 2.1 eV. Several charged intermediates become stabilized for most values of EF upon receiving conduction band electrons from TiO2, and the behavior of these species governs much of the overall energy landscape.

An Application of Item Response Theory to Scoring Patient Safety Culture Survey Data.

Patient safety culture is important in preventing medical errors. Thus, many instruments have been developed to measure it. Yet, few studies focus on the data processing step. This study, by analyzing the Chinese version of the Safety Attitudes Questionnaire dataset that contained 37,163 questionnaires collected in Taiwan, found critical issues related to the currently used mean scoring method: The instrument, like other popular ones, uses a 5-point Likert scale, and because it is an ordinal scale, the mean scores cannot be calculated. Instead, Item Response Theory (IRT) was applied. The construct validity was satisfactory and the item properties of the instrument were estimated from confirmatory factor analysis. The IRT-based domain scores and mean domain scores of each respondent were estimated and compared. As for resolution, the mean approach yielded only around 20 unique values on a 0 to 100 scale for each domain; the IRT method yielded at least 440 unique values. Meanwhile, IRT scores ranged widely at each unique mean score, meaning that the precision of the mean approach was less reliable. The theoretical soundness and empirical strength of IRT suggest that healthcare institutions should adopt IRT as a new scoring method, which is the core step of processing collected data.

Ensuring Taiwan patient safety culture survey is free from differential item functioning.

BACKGROUND: Differential item functioning (DIF) means the interference of some demographic characteristic or grouping of the tight relationship between trait levels. DIF threatens precise interpretations of survey results and makes them unreliable. The aim of this study was to examine whether the succinct version of Taiwan Patient Safety Culture (TPSC-S) survey is free from DIF and to mitigate its impact if needed. METHODS: The TPSC-S survey results of 2964 respondents in a public hospital in Taiwan were analyzed. The existence, type, and effect size of DIF were examined for each TPSC-S item using a proportional-odds logistic regression method between characteristic groups, including gender, work experience, job types, management roles, employment status, and safety reporting experiences. RESULTS: The study results revealed that several items of TPSC-S showed statistically significant DIF between characteristic groups. Nevertheless, the magnitude of these DIF was small, and their influence to TPSC-S survey was not significant. The domain-level DIF impact was completely insignificant for all characteristic groups. CONCLUSION: This study revealed that the 24-item TPSC-S survey was free from DIF in six characteristic groups. The difference in survey scores between groups stems from the real difference that hospital safety managers want to measure.

The Hospital Patient Safety Culture Survey: Reform of Analysis and Visualization Methods.

Understanding the topography of hospital safety culture is vital for developing, implementing, and monitoring the effectiveness of tailored safety programs. Since 2009, the Chinese version of the Safety Attitudes Questionnaire (SAQ-C) has been introduced and administered to providers in many Taiwanese hospitals. The mean percentage of SAQ survey respondents who demonstrate attitudinal agreement within each of the SAQ domains, the percent agreement (PA) score, is used worldwide as the main parameter of safety culture surveys. However, several limitations within PA scoring have been identified. Our study sought to improve scoring methodology and develop a new graph layout for cultural topography presentation. A total of 37,163 responses to a national SAQ-C administration involving 200 Taiwan hospitals were retrospectively analyzed. To understand the central tendency and spread of safety culture scores across all participating hospitals, the median and interquartile range (IQR) of PA scores to the SAQ's teamwork domain were calculated, plotted, and named "safety culture grid." Study results denote limitations in the current PA scoring scheme, suggest SAQ analysis modification, and introduce a visualization graph layout that can provide richer information about safety culture dissemination than that available from currently utilized tools.

National quality evaluation of peri-surgical hearing care for pediatric otitis media with effusion.

OBJECTIVE: Otitis media with effusion (OME) is a common disease among children that can lead to grave sequelae with respect to hearing. Thus, when treating OME, appropriate hearing care should be provided; ventilation tube insertion (VTI), a standard approach for treating OME, is no exception. This study examined hearing care for VTI and its associated factors, especially at the national level. DESIGN: Retrospective database analysis. SETTING: Taiwan's National Health Insurance Research Database. PARTICIPANTS: One thousand one hundred and fifty-nine patients who received VTI (age ≤12 years; 2011-12). INTERVENTION: No intervention. MAIN OUTCOME MEASURES: Compliance to guidelines: sufficient observation time (OBS), tympanogram before VTI (TYM-B) and hearing tests before and after VTI (HEAR-B and HEAR-A, respectively). RESULTS: The national proportions of completion for each procedure were 30.1% for OBS, 84.4% for TYM-B, 74.3% for HEAR-B and 36.0% for HEAR-A; those of OBS and HEAR-A were extremely low. Age, nasal allergy and even geographic area were associated with differences across completion patterns. Regression revealed some notable patterns. Compared with non-teaching hospitals, teaching hospitals administered HEAR-B most successfully (odds ratio [OR: 3.20, 95% CI: 1.06-9.63) and the smallest hospital group performed HEAR-B most successfully (OR: 2.92, 95% CI: 1.14-7.46). CONCLUSION: Several findings surfaced concerning VTI-related hearing care and its association with many clinical and socioeconomic factors in this national study. These findings could serve as a map for improving hearing care quality among children with OME.

First-principles description of oxygen self-diffusion in rutile TiO2: assessment of uncertainties due to enthalpy and entropy contributions.

Properties related to transport such as self-diffusion coefficients are relevant to fuel cells, electrolysis cells, and chemical/gas sensors. Prediction of self-diffusion coefficients from first-principles involves precise determination of both enthalpy and entropy contributions for point defect formation and migration. We use first-principles density functional theory to estimate the self-diffusion coefficient for neutral O0i and doubly ionized Oi2- interstitial oxygen in rutile TiO2 and compare the results to prior isotope diffusion experiments. In addition to formation and migration energy, detailed estimates of formation and migration entropy incorporating both vibrational and ionization components are included. Distinct migration pathways, both based on an interstitialcy mechanism, are identified for O0i and Oi2-. These result in self-diffusion coefficients that differ by several orders of magnitude, sufficient to resolve the charge state of the diffusing species to be Oi2- in experiment. The main sources of error when comparing computed parameters to those obtained from experiment are considered, demonstrating that uncertainties due to computed defect formation and migration entropies are comparable in magnitude to those due to computed defect formation and migration energies. Even so, the composite uncertainty seems to limit the accuracy of first-principles calculations to within a factor of ±103, demonstrating that direct connections between computation and experiment are now increasingly possible.

Bimetallic Nickel/Ruthenium Catalysts Synthesized by Atomic Layer Deposition for Low-Temperature Direct Methanol Solid Oxide Fuel Cells.

Nickel and ruthenium bimetallic catalysts were heterogeneously synthesized via atomic layer deposition (ALD) for use as the anode of direct methanol solid oxide fuel cells (DMSOFCs) operating in a low-temperature range. The presence of highly dispersed ALD Ru islands over a porous Ni mesh was confirmed, and the Ni/ALD Ru anode microstructure was observed. Fuel cell tests were conducted using Ni-only and Ni/ALD Ru anodes with approximately 350 µm thick gadolinium-doped ceria electrolytes and platinum cathodes. The performance of fuel cells was assessed using pure methanol at operating temperatures of 300-400 °C. Micromorphological changes of the anode after cell operation were investigated, and the content of adsorbed carbon on the anode side of the operated samples was measured. The difference in the maximum power density between samples utilizing Ni/ALD Ru and Pt/ALD Ru, the latter being the best catalyst for direct methanol fuel cells, was observed to be less than 7% at 300 °C and 30% at 350 °C. The improved electrochemical activity of the Ni/ALD Ru anode compared to that of the Ni-only anode, along with the reduction of the number of catalytically active sites due to agglomeration of Ni and carbon formation on the Ni surface as compared to Pt, explains this decent performance.