Ni‐rich LiNixCoyMn1−x−yO2 (x ≥ 0.8) layered oxides are the most promising cathode materials for lithium‐ion batteries due to their high reversible capacity of over 200 mAh g−1. Unfortunately, the ...anisotropic properties associated with the α‐NaFeO2 structured crystal grains result in poor rate capability and insufficient cycle life. To address these issues, a micrometer‐sized Ni‐rich LiNi0.8Co0.1Mn0.1O2 secondary cathode material consisting of radially aligned single‐crystal primary particles is proposed and synthesized. Concomitant with this unique crystallographic texture, all the exposed surfaces are active {010} facets, and 3D Li+ ion diffusion channels penetrate straightforwardly from surface to center, remarkably improving the Li+ diffusion coefficient. Moreover, coordinated charge–discharge volume change upon cycling is achieved by the consistent crystal orientation, significantly alleviating the volume‐change‐induced intergrain stress. Accordingly, this material delivers superior reversible capacity (203.4 mAh g−1 at 3.0–4.3 V) and rate capability (152.7 mAh g−1 at a current density of 1000 mA g−1). Further, this structure demonstrates excellent cycling stability without any degradation after 300 cycles. The anisotropic morphology modulation provides a simple, efficient, and scalable way to boost the performance and applicability of Ni‐rich layered oxide cathode materials.
A Ni‐rich LiNi0.8Co0.1Mn0.1O2 cathode material with radially aligned single‐crystal primary particles is synthesized. This unique crystallographic texture enables three‐dimensional (3D) Li+ diffusion channels penetrated straightforwardly from surface to center of the secondary particles and significantly alleviates volume‐change‐induced intergrain stress upon cycling. Accordingly, this material delivers superior capacity, rate capability and excellent cycling stability.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
In view of the sluggish kinetics suppressing the oxygen evolution reaction (OER), developing efficient and robust OER catalysts is urgent and essential for developing efficient energy conversion ...technologies. Herein, hybrid amorphous/crystalline FeCoNi layered double hydroxide (LDH)‐supported single Ru atoms (Ru SAs/AC‐FeCoNi) are developed for enabling a highly efficient electrocatalytic OER. The amorphous outer layer in Ru SAs/AC‐FeCoNi is composed of abundant defect sites and unsaturated coordination sites, which can serve as anchoring sites to stabilize single Ru atoms. The crystalline inner has a highly symmetric rigid structure, thereby strengthening the stability of support for a long‐lasting OER. The synergistic effects endow this hybrid catalyst with extremely low overpotential (205 mV at 10 mA cm−2). Density functional theory calculation indicates that single Ru atoms stabilized by hybrid amorphous/crystalline FeCoNi LDH facilitate the formation of Ru–O* (rate‐determining step), thus accelerating the OER process.
Herein, hybrid amorphous/ crystalline FeCoNi layered double hydroxide (LDH)‐supported single Ru atoms (Ru SAs/AC‐FeCoNi) are developed to enable a highly efficient electrocatalytic oxygen evolution reaction. The amorphous outer layer in Ru SAs/AC‐FeCoNi is composed of abundant defect sites and unsaturated coordination sites, which can serve as anchoring sites to stabilize single Ru atoms.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Developing a facile route to access active and well-defined single atom sites catalysts has been a major area of focus for single atoms catalysts (SACs). Herein, we demonstrate a simple approach to ...generate atomically dispersed platinum via a thermal emitting method using bulk Pt metal as a precursor, significantly simplifying synthesis routes and minimizing synthesis costs. The ammonia produced by pyrolysis of Dicyandiamide can coordinate with platinum atoms by strong coordination effect. Then, the volatile Pt(NH3) x can be anchored onto the surface of defective graphene. The as-prepared Pt SAs/DG exhibits high activity for the electrochemical hydrogen evolution reaction and selective oxidation of various organosilanes. This viable thermal emitting strategy can also be applied to other single metal atoms, for example, gold and palladium. Our findings provide an enabling and versatile platform for facile accessing SACs toward many industrial important reactions.
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IJS, KILJ, NUK, PNG, UL, UM
Lithium–air batteries (LABs) have attracted tremendous attention since the proposal of the LAB concept in 1996 because LABs have a super high theoretical/practical specific energy and an infinite ...supply of redox-active materials, and are environment-friendly. However, due to the lack of critical electrode materials and a thorough understanding of the chemistry of LABs, the development of LABs entered a germination period before 2010, when LABs research mainly focused on the development of air cathodes and carbonate-based electrolytes. In the growing period, i.e. , from 2010 to the present, the investigation focused more on systematic electrode design, fabrication, and modification, as well as the comprehensive selection of electrolyte components. Nevertheless, over the past 25 years, the development of LABs has been full of retrospective steps and breakthroughs. In this review, the evolution of LABs is illustrated along with the constantly emerging design, fabrication, modification, and optimization strategies. At the end, perspectives and strategies are put forward for the development of future LABs and even other metal–air batteries.
•A combined mechanical and chemical method was used to promote hydrate formation.•This method comprises surfactant addition and gas-inducing agitation.•This method led to increased hydrate formation ...rate.
This paper reports experimental measurements of the isothermal and isochoric formation kinetics of methane hydrate in sodium dodecyl sulphate (SDS) solutions of various concentrations with gas-inducing agitation, and the results are compared with those obtained with normal agitation and no agitation. The experiments were conducted at 274 K with initial gas pressure of 10 MPa. At a given SDS concentration, the gas-inducing agitation gave higher hydrate formation rate than normal agitation and no agitation. Gas inducing agitation of deionized water gave a relatively low methane hydrate formation rate, which could be greatly enhanced by adding SDS. The enhanced kinetics can be attributed to increased gas-liquid contact area, with the coalescence of induced gas bubbles being effectively inhibited by SDS at low concentrations.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPUK, ZRSKP
Highlights
The composite cathode composition, preparation method, and chemical compatibility play critical roles in constructing triple-phase interfaces.
Understanding the electrolyte degradation is ...critical for boosting the high-performance composite sulfur cathode.
The volume change of sulfur challenges the mechanical stability of composite sulfur cathode.
Lithium–sulfur batteries with liquid electrolytes have been obstructed by severe shuttle effects and intrinsic safety concerns. Introducing inorganic solid-state electrolytes into lithium–sulfur systems is believed as an effective approach to eliminate these issues without sacrificing the high-energy density, which determines sulfide-based all-solid-state lithium–sulfur batteries. However, the lack of design principles for high-performance composite sulfur cathodes limits their further application. The sulfur cathode regulation should take several factors including the intrinsic insulation of sulfur, well-designed conductive networks, integrated sulfur-electrolyte interfaces, and porous structure for volume expansion, and the correlation between these factors into account. Here, we summarize the challenges of regulating composite sulfur cathodes with respect to ionic/electronic diffusions and put forward the corresponding solutions for obtaining stable positive electrodes. In the last section, we also outlook the future research pathways of architecture sulfur cathode to guide the develop high-performance all-solid-state lithium–sulfur batteries.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Abstract
High-energy density lithium-rich layered oxides are among the most promising candidates for next-generation energy storage. Unfortunately, these materials suffer from severe electrochemical ...degradation that includes capacity loss and voltage decay during long-term cycling. Present research efforts are primarily focused on understanding voltage decay phenomena while origins for capacity degradation have been largely ignored. Here, we thoroughly investigate causes for electrochemical performance decline with an emphasis on capacity loss in the lithium-rich layered oxides, as well as reaction pathways and kinetics. Advanced synchrotron-based X-ray two-dimensional and three-dimensional imaging techniques are combined with spectroscopic and scattering techniques to spatially visualize the reactivity at multiple length-scales on lithium- and manganese-rich layered oxides. These methods provide direct evidence for inhomogeneous manganese reactivity and ionic nickel rearrangement. Coupling deactivated manganese with nickel migration provides sluggish reaction kinetics and induces serious structural instability in the material. Our findings provide new insights and further understanding of electrochemical degradation, which serve to facilitate cathode material design improvements.
•Algal hydrophobicity and bubble size are key factors for microalgae flotation.•Algal hydrophobicity can be improved using cationic surfactants at appropriate pHs.•A step-wise optimization of algae ...flotation is demonstrated.
Microalgae harvesting by air flotation is a promising technology for large-scale production of biofuel, feed and nutraceuticals from algae. With an adherence-to-hydrocarbon method and two different types of flotation cells (mechanically agitated cell and Jameson cell), microalgal surface hydrophobicity and bubble size were identified to be critical for effective froth flotation of microalgae. Freshwater alga Chlorella sp. BR2 showed naturally a high hydrophobicity and an ideal response to flotation. However, many marine microalgae possess a low surface hydrophobicity and are thus difficult to harvest. This paper shows that a step-wise optimization approach can substantially improve the flotation of a low surface hydrophobicity marine microalga, Tetraselmis sp. M8, to near full recovery with an enrichment ratio of 11.4.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPUK
Abstract We synthesised the evidence of microRNAs as prognostic biomarkers in lung cancer. Studies were identified by searching PubMed, Embase and Web of Science until March 2012. Descriptive ...characteristics for studies were described and an additional meta-analysis for two specific microRNAs (miR-21 and miR-155) which were studied extensively was performed. Pooled hazard ratios (HRs) and their corresponding 95% confidence intervals (CIs) were calculated. The median study size was 88 patients (interquartile range IQR = 53–193) and the median HR in the studies that reported statistically significant results was 2.855 (IQR = 2.01–5.035). For the studies evaluating miR-21’s association with clinical outcomes, the pooled HR suggested that high expression of miR-21 has a negative impact on overall survival (OS) in non-small cell lung cancer (NSCLC) (HR = 2.321.17–4.62, P < 0.05) and recurrence-free survival (RFS)/cancer-specific survival (CSS) in lung adenocarcinoma (HR = 2.431.67–3.54, P < 0.001). As for miR-155, the pooled HR for OS was 2.09 (95% CI: 0.68–6.41, P > 0.05) which was not statistically significant, but for RFS/CSS was 1.42 (95% CI: 1.10–1.83, P = 0.007). These results indicate that microRNAs show promising associations with prognosis in lung cancer; moreover, specific microRNAs such as miR-21 and miR-155 can predict recurrence and poor survival in NSCLC.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPUK
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