Pressureless all-solid-state Na/S batteries with self-supporting Na_(5)YSi_(4)O_(12) scaffolds

The development of reliable and affordable all-solid-state sodium metal batteries(ASS-SMBs)requires suitable solid-state electrolytes with cost-efficient processing and stabilized electrode/electrolyte interfaces.Here,an integrated porous/dense/porous Na_(5)YSi_(4)O_(12)(NYS)trilayered scaffold is designed and fabricated by tape casting using aqueous slurries.In this template-based NYS scaffold,the dense layer in the middle serves as a separator and the porous layers on both sides accommodate the active materials with their volume changes during the charge/discharge processes,increasing the contact area and thus enhancing the utilization rate and homogenizing the current distribution.The Na/NYS/Na symmetric cells with the Pb-coated NYS scaffold exhibit significantly reduced interfacial impedance and superior critical current density of up to 3.0 mA cm^(-2)against Na metal owing to enhanced wettability.Furthermore,the assembled Na/NYS/S full cells operated without external pressure at room temperature showed a high initial discharge capacity of 970 mAh g^(-1)and good cycling stability with a capacity of 600 mAh g^(-1)after 150 cycles(based on the mass of sulfur).This approach paves the way for the realization of economical and practical ASS-SMBs from the perspective of ceramic manufacturing.

Discharge and jet characteristics of gliding arc plasma igniter driven by pressure difference

Stable combustion in an afterburner can help increase the thrust of the engine in a short time,thereby improving the maneuverability of a fighter.To improve the ignition performance of an afterburner,a twin-duct ignition platform was designed to study the performance of a gliding arc plasma igniter in close-to-real afterburner conditions.The research was carried out by a combination of experiments and simulations.The working environment of the igniter was explored through a numerical simulation.The results showed that the airflow ejected from the radiating holes formed a swirling sheath,which increased the anti-interference ability of the airflow jet.The influence of the pressure difference between the inlet and outlet of the igniter(Δp),the flow rate outside the igniter outlet(W_(2)),and the installation angle(α)on the singlecycle discharge energy(E)as well as the maximum arc length(L)were studied through experiments.Three stages were identified:the airflow breakdown stage,the arc evolution stage,and the arc fracture stage.E and L increased by 107.3%and 366.2%,respectively,withΔp increasing from 10 to 70 Torr.The relationship between L andΔp obtained by data fitting is L=3-2.47/(1+(Δp/25)^(4)).The relationship of L at differentαis L_(α=0°)>(L_(α=45°)and L_(α=135°))>L_(α=180°)>L_(α=90°).E and L decrease by 18.2%and 37.3%,respectively,whenΔp=45 Torr and W_(2) is increased from 0 to 250 l min^(-1).

Enhanced room-temperature Na^(+) ionic conductivity in Na_(4.92)Y_(0.92)Zr_(0.08)Si_(4)O_(12)

Developing cost-effective and reliable solid-state sodium batteries with superior performance is crucial for stationary energy storage.A key component in facilitating their application is a solid-state electrolyte with high conductivity and stability.Herein,we employed aliovalent cation substitution to enhance ionic conductivity while preserving the crystal structure.Optimized substitution of Y^(3+)with Zr^(4+)in Na_(5)YSi_(4)O_(12) introduced Naþion vacancies,resulting in high bulk and total conductivities of up to 6.5 and 3.3 mS cm^(-1),respectively,at room temperature with the composition Na_(4.92)Y_(0.92)Zr_(0.08)Si_(4)O_(12)(NYZS).NYZS shows exceptional electrochemical stability(up to 10 V vs.Naþ/Na),favorable interfacial compatibility with Na,and an excellent critical current density of 2.4 mA cm^(-2).The enhanced conductivity of Naþions in NYZS was elucidated using solid-state nuclear magnetic resonance techniques and theoretical simulations,revealing two migration routes facilitated by the synergistic effect of increased Naþion vacancies and improved chemical environment due to Zr^(4+)substitution.NYZS extends the list of suitable solid-state electrolytes and enables the facile synthesis of stable,low-cost Naþion silicate electrolytes.

Experimental investigation of a gliding discharge plasma jet igniter

Relight of jet engines at high altitude is difficult due to the relatively low pressure and temperature of inlet air.The penetration of initial flame kernel affects the ignition probability in the turbine engine combustor greatly.In order to achieve successful ignition at high altitude,a deeper penetration of initial flame kernel should be generated.In this study,a Gliding Arc Plasma Jet Igniter(GAPJI)is designed to induce initial flame kernel with deeper penetration to achieve successful ignition at high altitude.The ignition performance of the GAPJI was demonstrated in a model combustor.It was found that GAPJI can generate plasma with deeper penetration up to 30.5 mm than spark igniter with 22.1 mm.The discharge power of GAPJI was positively correlated with flow rate of the carrier gas,approaching 200 W in average.Ignition experiments show that GAPJI has the advantage of extending the lean ignition limit.With GAPJI,the lean ignition limit of the combustor is 0.02 at 0 km,which is 55.6%less than that with spark igniter(0.045).The evolution of flame morphology was observed to explore the development of the flame kernel.It is shown that the advantage of a high penetration and continuous releasing energy can accelerate the ignition process and enhance combustion.

Acidification and bubble template derived porous g-C_(3)N_(4) for efficient photodegradation and hydrogen evolution

Graphitic carbon nitride(g-C_(3)N_(4))as a metal-free candidate of photocatalyst has received worldwide attention because of its great potentials in solar light-induced degradation and hydrogen evolution,yet the industrial application is seriously hindered by the small specific surface area and rapid recombination rate of carriers.Herein,we demonstrate that porous g-C_(3)N_(4)(HCl-CNU-X)can be prepared via the copolymerization of acidified melamine and a green bubble template(urea).Transmission electron microscopy and nitrogen sorption characterization results show that the prepared HCl-CNU-X possesses an in-plane porous structure and large specific surface area,enabling the exposure of more accessible active sites.As a result,HCl-CNU-X exhibits both enhanced photocatalytic tetracycline hydrochloride degradation and higher hydrogen evolution than bulk g-C_(3)N_(4).The boosted photocatalytic performance was ascribed to the formation of the porous structure,which dramatically promotes the separation of charge-carriers and facilitates the electron transfer.This work demonstrates that the acidification of nitrogen-rich precursors combined with a bubble-template can develop a new paradigm of highly porous photocatalysts for environmental remediation and water splitting.

A novel fluorescent sensor for Al^(3+)and Zn^(2+)based on a new europium complex with a 1,10-phenanthroline ligand

A new europium complex Eu(tta)_(3)Li(la)based on 1,10-phenanthroline derivative(Li=(2-(3,5-dimethoxyphenyl)-1 H-imidazo[4,5-f][1,10]phenanthroline),tta=2-thenoyItrifluoroacetone)was designed and synthesized.Its structure was characterized by^(1)H and^(13)C NMR,elemental analysis,UV-vis,fluorescence spectra and single crystal X-ray diffraction.The crystal of the complex la belongs to monoclinic system with the space group P2_(1/n).The europium complex la in the solid and in the solution displays the typical emission of Eu(III)ion centered at 612 nm as a result of the electric dipole transition(^(5)D_(0)-►^(7)F_(2)).It exhibits high quantum yield(20.42%),long lifetime(0.29 ms)and good CIE color coordinate(0.67,0.33)in solid.In addition,the complex shows high sensitivity and selectivity towards Al^(3+)and Zn^(2+)in methanol solution which can be attributed to the Al^(3+)/Zn^(2+)cation instead of Eu^(3+)in the complex la.The LODs for Al^(3+)and Zn^(2+)were calculated to be 5.880×10^(-7)and 7.678×10^(-8)mol/L,respectively.Besides,the additions of Al^(3+)and Zn^(2+)express remarkable color changes from red to bright blue and ivory that can be clearly observed by the naked eye respectively.

Intrinsic Zero-Linear and Zero-Area Compressibilities over an Ultrawide Pressure Range within a Gear-Spring Structure

Materials with zero-linear compressibility(ZLC)and zero-area compressibility(ZAC)have great promise for specific applications retaining constancy in specific directions or planes under external impaction.To date,no more than 10 ZLC/ZAC materials have been reported,most of which have very limited working pressure ranges(<10 GPa).Herein,we report the observation of ZLC and ZAC in Li2Ti(IO3)6 with a gear-spring type structure over an ultrawide pressure range(0–40 GPa).