Supercapacitor electrode based on few-layer h-BNNSs/rGO composite for wide-temperature-range operation with robust stable cycling performance

Currently,developing supercapacitors with robust cycle stability and suitability for wide-temperature-range operations is still a huge challenge.In the present work,few-layer hexagonal boron nitride nanosheets(h-BNNSs)with a thickness of 2−4 atomic layers were fabricated via vacuum freeze-drying and nitridation.Then,the h-BNNSs/reduced graphene oxide(rGO)composite were further prepared using a hydrothermal method.Due to the combination of two two-dimensional(2D)van der Waals-bonded materials,the as-prepared h-BNNSs/rGO electrode exhibited robustness to wide-temperature-range operations from−10 to 50℃.When the electrodes worked in a neutral aqueous electrolyte(1 M Na2SO4),they showed a great stable cycling performance with almost 107%reservation of the initial capacitance at 0℃ and 111% at 50℃ for 5000 charge−discharge cycles.

Entanglement quantification via weak measurements assisted by deep learning

Entanglement has been recognized as being crucial when implementing various quantum information tasks.Nevertheless, quantifying entanglement for an unknown quantum state requires nonphysical operations or post-processing measurement data. For example, evaluation methods via quantum state tomography require vast amounts of measurement data and likely estimation.

Large-Scale Synthesis of the Stable Co-Free Layered Oxide Cathode by the Synergetic Contribution of Multielement Chemical Substitution for Practical Sodium-Ion Battery

The O3-type layered oxide cathodes for sodium-ion batteries(SIBs)are considered as one of the most promising systems to fully meet the requirement for future practical application.However,fatal issues in several respects such as poor air stability,irreversible complex multiphase evolution,inferior cycling lifespan,and poor industrial feasibility are restricting their commercialization development.Here,a stable Co-free O3-type NaNi_(0.4)Cu_(0.05)Mg_(0.05)Mn_(0.4)Ti_(0.1O2) cathode material with large-scale production could solve these problems for practical SIBs.Owing to the synergetic contribution of the multielement chemical substitution strategy,this novel cathode not only shows excellent air stability and thermal stability as well as a simple phase-transition process but also delivers outstanding battery performance in half-cell and full-cell systems.Meanwhile,various advanced characterization techniques are utilized to accurately decipher the crystalline formation process,atomic arrangement,structural evolution,and inherent effect mechanisms.Surprisingly,apart from restraining the unfavorable multiphase transformation and enhancing air stability,the accurate multielement chemical substitution engineering also shows a pinning effect to alleviate the lattice strains for the high structural reversibility and enlarges the interlayer spacing reasonably to enhance Na^(+)diffusion,resulting in excellent comprehensive performance.Overall,this study explores the fundamental scientific understandings of multielement chemical substitution strategy and opens up a new field for increasing the practicality to commercialization.

High-performance chromite by structure stabilization treatment

Chromite is an important raw material applied in refractories.Efforts have been made to obtain high-performance chromite by adding MgO and Al203 from the viewpoint of structure optimization.In order to explore the effect of Al203 and MgO on the structure,two formulas,i.e.,Mg-rich and Al-rich ones,were selected.The phase and microstructure development of samples heated in the temperature range of 1200-1600℃ were studied by X-ray diffraction and scanning electron microscopy with energy-dispersive spectrometry.MgO and Al203 added have diffused into chromite successfully by heat treatment.MgO diffuses into chromite,occupying the tetrahedral vacancies caused by the diffusion and oxidation of Fe2+ions to stabilize the structure.Al203 diffuses into the surface layer of chromite,forming spinel-sesquioxide structure.Al-rich sample which has spinel-sesquioxide structure shows better corrosion resistance toward fayalite slag than Mg-rich sample which has single spinel structure by blocking the interdiffusion between Fe^2+ions in fayalite slag and Mg^2+ions in chromite.

Effect and mechanism of nano-Ca_(10)(PO_(4))_(6)(OH)_(2)additive on compressive strength of calcium aluminate cement at high temperature

Calcium aluminate cement(CAC)is widely used as a binder for refractory materials,and thus the improvement in compressive strength is of vital importance for CAC applied at high temperature.For this purpose,nano-Ca_(10)(PO_(4))_(6)(OH)_(2)additive with a ratio of 0.5–1.5 mass%was added with the water-cement ratio to be 0.4.X-ray diffraction and isothermal calorimetry analysis demonstrate that nano-Ca_(10)(PO_(4))_(6)(OH)_(2)additive can shorten the hydration process and promote the formation of main hydrates of CaAl2O4·10H2O(CAH10)and Ca2Al2O5·8H2O(C2AH8).In addition,scanning electron microscopy results suggest that nano-Ca_(10)(PO_(4))_(6)(OH)_(2)can protect CAH10 and C2AH8 from being destroyed during the calcination,guaranteeing that these thin lamellar crystals are intertwined to form the denser microstructure.Benefited from above effects,nano-Ca_(10)(PO_(4))_(6)(OH)_(2)can obviously improve the compressive strength of the CAC mortar samples cured for 7 d after calcination at 1100°C,while the improving effect is dependent upon its contents.Especially,compared with the one without the additive,the compressive strength of the sample with 1.0%nano-Ca_(10)(PO_(4))_(6)(OH)_(2)is increased by 14%.

High resolution imaging with anomalous saturated excitation

The nonlinear fluorescence emission has been widely applied for high spatial resolution optical imaging.Here,we studied the fluorescence anomalous saturating effect of the nitrogen vacancy defect in diamond.The fluorescence reduction was observed with high power laser excitation.It increased the nonlinearity of the fluorescence emission,and changed the spatial frequency distribution of the fluorescence image.We used a differential excitation protocol to extract the high spatial frequency information.By modulating the excitation laser’s power,the spatial resolution of imaging was improved approximately 1.6 times in comparison with the confocal microscopy.Due to the simplicity of the experimental setup and data processing,we expect this method can be used for improving the spatial resolution of sensing and biological labeling with the defects in solids.