Revealing the Multifunctional Electrocatalysis of Indium-Modulated Phthalocyanine for High-Performance Lithium-Sulfur Batteries

The sluggish kinetics of complicated multiphase conversions and the severe shuttling effect of lithium polysulfides(LiPSs)significantly hinder the applications of Li-S battery,which is one of the most promising candidates for the next-generation energy storage system.Herein,a bifunctional electrocatalyst,indium phthalocyanine self-assembled with carbon nanotubes(InPc@CNT)composite material,is proposed to promote the conversion kinetics of both reduction and oxidation processes,demonstrating a bidirectional catalytic effect on both nucleation and dissolution of Li_(2)S species.The theoretical calculation shows that the unique electronic configuration of InPc@CNT is conducive to trapping soluble polysulfides in the reduction process,as well as the modulation of electron transfer dynamics also endows the dissolution of Li_(2)S in the oxidation reaction,which will accelerate the effectiveness of catalytic conversion and facilitate sulfur utilization.Moreover,the InPc@CNT modified separator displays lower overpotential for polysulfide transformation,alleviating polarization of electrode during cycling.The integrated spectroscopy analysis,HRTEM,and electrochemical study reveal that the InPc@CNT acts as an efficient multifunctional catalytic center to satisfy the requirements of accelerating charging and discharging processes.Therefore,the Li-S battery with InPc@CNT-modified separator obtains a discharge-specific capacity of 1415 mAh g^(-1)at a high rate of 0.5 C.Additionally,the 2 Ah Li-S pouch cells deliver 315 Wh kg^(-1)and achieved 80%capacity retention after 50 cycles at 0.1 C with a high sulfur loading of 10 mg cm^(-2).Our study provides a practical method to introduce bifunctional electrocatalysts for boosting the electrochemical properties of Li-S batteries.

Viscoelastic Analysis of a Surface Acoustic Wave Gas Sensor Coated by a New Deposition Technique

An analysis of the response of surface acoustic wave sensors coated with polymer film based on new coating deposition （self-assemble and molecularly imprinted technology） is described and the response formulas are hence deduced. Using the real part of shear modulus, the polymer can be classified into three types： glassy film, glassy-rubbery film and rubbery film, Experimental results show that the attenuation response is in better consistence with the simulation than in Martin＇s theory, but the velocity response does not accord with the calculation exactly. Maybe it is influenced by the experimental methods and environment. In addition, simulations of gas sorption for polymer films are performed. As for glassy film, the SAW sensor response increases with increasing fihn thickness, and the relationship between the sensor response and the concentration of gas is pretty linear, while as for glassy-rubbery flint and rubbery film, the relationship between the sensor sensitivity anti concentration of gas is very complicated. The ultimately calculated results indicate that the relationship between the sensor response and frequency is not always linear due to the viscoelastic prooerties of the polymer.

P4S10 modified lithium anode for enhanced performance of lithium–sulfur batteries

To address the corrosion and dendrite issues of lithium metal anodes, a protective layer was ex-situ constructed by P4S10 modification. It was determined by X-ray photoelectron spectroscopy and Raman spectra that the main constituents of the protective layer were P4S10, Li3PS4 and other LixPySztype derivatives. The protective layer was proved to be effective to stabilize the interphase of lithium metal. With the modified Li anodes, symmetric cells could deliver stable Li plating/stripping for 16000 h;Li–S batteries exhibited a specific capacity of 520 m A h g-1 after 200 cycles at 1000 m A g-1 with average Coulombic efficiency of 97.9%. Therefore, introducing LixPySzbased layer to protect Li anode provides a new strategy for the improvement of Li metal batteries.

Recent progress of fiber-shaped batteries towards wearable application

Rapid development of portable or wearable devices, which is inspired by requirements of instant messaging,health monitoring and handling official business, urgently demands more tiny, flexible and light power sources. Fibershaped batteries explored in recent years become a prospective candidate to satisfy these demands. With 1D architecture,the fiber-shaped batteries could be adapted to various deformations and integrated into soft textile and other devices.Numerous researches have been reported and achieved huge promotion. To give an overview of fiber-shaped batteries,we summarized the development of fiber-shaped batteries in this review, and discussed the structure and materials in fiber-shaped batteries. The flexibility of batteries with the potential application of the batteries was also exhibited and showed the future perspective. Finally, challenges in this field were discussed, hoping to reveal research direction towards further development of fiber-shaped batteries.

Study on dynamic response of multi-degree-of-freedom explosion vessel system under impact load

In order to study the dynamic response and calculate the axial dynamic coefficient of the monolayer cylindrical explosion vessel,the wall of vessel is simplified as a multi-degree-of-freedom(MDoF) undamped elastic foundation beam.Decoupling the coupled motion equation and using Duhamel's integrals,the solutions in generalized coordinates of the equations under exponentially decaying loads,square wave loads and triangular wave loads are calculated.These solutions are consistent in form with the solutions of single-degree-of-freedom(SDoF) undamped forced vibration simplified model.Based on the model,equivalent MDoF design method(also called MDoF dynamic coefficient method) of cylindrical explosion vessel is proposed.The traditional method can only predict the dynamic coefficient of torus portion around the explosion center,but this method can predict that of the vessel wall at any axial n dividing point position.It is verified that the prediction accuracy of this model is greatly improved compared with the SDoF model by comparing the results of this model with SDoF model and numerical simulation in different working conditions.However,the prediction accuracy decreases as the scaled distance decreases and approaches the end of the vessel,which is related to the accuracy of the empirical formula of the implosion load,the simplification of the explosion load direction,the boundary conditions,and the loading time difference.

A CLASS OF COMPACT UPWIND TVD DIFFERENCE SCHEMES

A new method was proposed for constructing total variation diminishing （TVD） upwind schemes in conservation forms. Two limiters were used to prevent nonphysical oscillations across discontinuity. Both limiters can ensure the nonlinear compact schemes TVD property. Two compact TVD （CTVD） schemes were tested, one is thirdorder accuracy, and the other is fifth-order. The performance of the numerical algorithms was assessed by one-dimensional complex waves and Riemann problems, as well as a twodimensional shock-vortex interaction and a shock-boundary flow interaction. Numerical results show their high-order accuracy and high resolution, and low oscillations across discontinuities.

Comparative Analysis of Experiment Treating Benzene and CEES by Pulse Corona Plasma

Based on an experiment treating benzene and 2-chloroethyl ethyl sulfide （CEES） by pulse corona induced-plasma, the simiarities and differences found in the experimental data and analytical results are analyzed in a comparative manner in this paper. The theory applied is also discussed.

Extended XG Equation for the Prediction of Adsorption Equilibrium of Vapor Mixture on Activated Carbon

The XG equation, which is developed by us previously for describing the adsorption equilibrium of pure vapor on activated carbon, is extended to multi-component system. Verified by experimental data, the extended XG equation was found to be more successful in predicting the adsorption equilibrium of vapor mixture on activated carbon than the extended Langmuir equation, the extended BET equation and the ideal adsorbed solution theory (IAST).

In situ self-nucleophilic synthesis of nano-Li_(4)Ti_(5)O_(12)/reduced graphite oxide composite with mesopore-oriented porous structure for high-rate lithium ion batteries

It is the core to improve the electron/ion transfer features of Li_(4)Ti_(5)O_(12) for achieving high-rate anode in lithium ion batteries.By directly using graphite oxide powder,nano-Li_(4)Ti_(5)O_(12)/reduced graphite oxide composite with mesopore-oriented porosity is prepared through one-pot facile ball-milling method in this work.Synthesis mechanism underlying the self-nucleophilic effect of oxygen-containing functional groups in graphite oxide is substantiated.Reactants can intercalate into graphite oxide bulk and in-situ generate nanoparticles.Subsequently,graphite oxide with nanoparticles generated inside can obtain a mesopore-oriented porous structure under ball-milling.Furthermore,the synergistic effects of Li_(4)Ti_(5)O_(12) nanoparticles and mesopore-oriented porosity strengthen composites with rapid Li^(+)diffusion and electron conductive frameworks.The obtained optimal LTO/GO-1.75 composite displays excellent high-rate capability(136 mA·h/g at 7000 mA/g)and good cycling stability(a capacity retention of 72%after 1000 cycles at 7000 mA/g).Additionally,the reactants concentration in this demonstrated strategy is as high as 30 wt%−40 wt%,which is over 6 times that of traditional methods with GO suspensions.It means that the strategy can significantly increase the yield,showing big potential for large-scale production.

A new method for inversion of hydroxyl group of carbocyclic nucleosides

The hydroxyl group of carbocyclic nucleosides was inversed when the compounds were treated with Me3SiCl, KCN and a catalytic mount of NaI in DMF/CH3CN.

3D Numerical Simulation of Aerodynamic Characteristics of a Gas Filter

The filter paper and activated carbon which filled inside the gas filter have porous media characteristics. In order to study the flow field structure in the filter layer and the activated carbon layer, Computational Fluid Dynamics method is used to simulate the aerodynamic characteristics of a simplified gas filter. The inertial and viscosity parameters of porous media are solved by Forchheimer equation. The three-dimensional N-S equation and the modified low Reynolds number k-ε turbulence model are adopted to analyze the influence of the explosion-proof plate on the gas filter’s aerodynamic characteristics. The results showed that the air age in the upstream of the activated carbon plates was small, which easily caused the rapid penetration of the Poisonous gas. And in the downstream and around of the activated carbon plates, the air age is larger, formed dead zone, the utilization rate of activated carbon is lower. The explosion-proof plate increases the pressure drop of the gas filter, the air age distribution in the filter layer is more uniform and the utilization rate of filter paper is improved. However, the explosion-proof plate has little influence on the flow field structure of the activated carbon layer.

Hard-carbon hybrid Li-ion/metal anode enabled by preferred mesoporous uniform lithium growth mechanism

To achieve high energy density in lithium batteries,the construction of lithium-ion/metal hybrid anodes is a promising strategy.In particular,because of the anisotropy of graphite,hybrid anode formed by graphite/Li metal has low transport kinetics and is easy to causes the growth of lithium dendrites and accumulation of dead Li,which seriously affects the cycle life of batteries and even causes safety problems.Here,by comparing graphite with two types of hard carbon,it was found that hybrid anode formed by hard carbon and lithium metal,possessing more disordered mesoporous structure and lithophilic groups,presents better performance.Results indicate that the mesoporous structure provides abundant active site and storage space for dead lithium.With the synergistic effect of this structure and lithophilic functional groups(–COOH),the reversibility of hard carbon/lithium metal hybrid anode is maintained,promoting uniform deposition of lithium metal and alleviating formation of lithium dendrites.The hybrid anode maintains a 99.5%Coulombic efficiency(CE)after 260 cycles at a specific capacity of 500 m Ah/g.This work provides new insights into the hybrid anodes formed by carbon-based materials and lithium metal with high specific energy and fast charging ability.

基于AR模型与神经网络的核爆与闪电电磁脉冲信号识别

对平稳随机信号功率谱估计的AR模型,分别利用自相关函数法和Burg算法求该模型系数,作为核爆炸和闪电电磁脉冲信号的特征值;采用BP神经网络作为分类器以及不同的隐含层数和隐含层节点数,对核爆和闪电电磁脉冲实测数据进行识别研究。结果表明:AR参数模型法对两类信号特征值提取是非常有效的,采用Burg算法来求AR模型参数,其特征值提取效果优于自相关函数法。

A gelatin-based artificial SEI for lithium deposition regulation and polysulfide shuttle suppression in lithium-sulfur batteries

Lithium-sulfur(Li-S) battery is one of the best candidates for the next-generation energy storage system due to its high theoretical capacity(1675 mA h-1),low cost and environment friendliness.However,lithium(Li) dendrites formation and polysulfide shuttle effect are two major challenges that limit the commercialization of Li-S batteries.Here we design a facile bifunctional interlayer of gelatin-based fibers(GFs),aiming to protect the Li anode surface from the dendrites growth and also hinder the polysulfide shuttle effect.We reveal that the 3D structural network of GFs layer with abundant polar sites helps to homogenize Li-ion flux,leading to uniform Li-ion deposition.Meanwhile,the polar moieties also immobilize the lithium polysulfides and protect the Li metal from the side-reaction.As a result,the anodeprotected batteries have shown significantly enhanced performance.A high coulombic efficiency of 96% after 160 cycles has been achieved in the Li-Cu half cells.The Li-Li symmetric cells exhibit a prolonged lifespan for 800 h with voltage hysteresis(10 mV).With the as-prepared GFs layer,the Li-S battery shows approximately 14% higher capacity retention than the pristine battery at 0.5 C after 100 cycles.Our work presents that this gelatin-based bi-functional interlayer provides a viable strategy for the manufacturing of advanced Li-S batteries.

A novel permselective organo-polysulfides/PVDF gel polymer electrolyte enables stable lithium anode for lithium–sulfur batteries

Lithium-sulfur(Li-S)battery can satisfy the need of the future power battery market because of its high energy density,but the hidden dangers caused by lithium anode have seriously hindered their commercialization.Herein,an innovative gel polymer electrolyte(GPE)composed of polyvinylidene fluoride(PVDF)and organo-polysulfide polymer(PSPEG)is proposed,which could be used in semisolid-state Li-S batteries for protection of Li anodes.Particularly,organo-polysulfide polymer could chemically/electrochemically generate both inorganic and organic components simultaneously in-situ once contacting fresh Li metal surface and/or during discharging processes.And these inorganic/organic components could participate in the formation of the SEI layer and finally constitute a stable and flexible hybrid SEI layer on the surface of Li metal anode.Moreover,the organic components were permselective to lithium ions against anions.Therefore,PVDF/PSPEG GPE ensures the ideal chemical and electrochemical properties for Li-S batteries.Our work demonstrates an effective solution to solve the problems about Li anodes and contributes to the development of the safe Li metal batteries.

P(VDF-HFP)-poly(sulfur-1,3-diisopropenylbenzene) functional polymer electrolyte for lithium–sulfur batteries

Lithium–sulfur(Li–S)battery as a high-energy density electrochemical energy storage system has attracted many researchers’attention.However,the shuttle effect of Li–S batteries and the challenges associated with lithium metal anode caused poor cycle performance.In this work,the organosulfide poly(sulfur-1,3-diisopropenylbenzene)(PSD)was prepared as cathode material and additive of P(VDFHFP)polymer electrolyte(P(VDF-HFP)).It was verified that P(VDF-HFP)polymer electrolyte with 10%PSD(P(VDF-HFP)-10%PSD)showed a higher ionic conductivities than that of liquid electrolyte up to2.27×10-3 S cm-1 at room temperature.The quasi-solid-state Li-S batteries fabricated with organosulfide cathode material PSD and P(VDF-HFP)based functional polymer electrolyte delivered good cycling stability(780 m Ah g-1 after 200 th cycle at 0.1 C)and rate performance(613 m Ah g-1 at 1 C).The good cycling performance could be attributed to the synergistic effect of components,including the interaction between polysulfides and polymer main chain in the organosulfide cathode,the sustained organic/inorganic hybrid stable SEI layer formed by polymer electrolyte additive PSD,the improved cathode/electrolyte interface and the good affinity between P(VDF-HFP)based functional polymer electrolyte and Li metal surface.This strategy herein may provide a new route to fabricate high-performance Li–S batteries through the organosulfide cathode and functional polymer electrolyte.

Attapulgite nanorods assisted surface engineering for separator to achieve high-performance lithium–sulfur batteries

Lithium-sulfur(Li-S)batteries have been recognized as one of the most promising candidates for nextgeneration portable electronic devices,owing to their extremely high energy density and low cost.However,the dissolution of lithium polysulfides(LiPSs)and consequent"shuttle effect"seriously hinder the practical deployment of Li-S batteries.Herein,multi-metal oxide nanorods named attapulgite are proposed as multifunctional ionic sieve to immobilize LiPSs and further promote the regulation of LiPSs.Attapulgite,consisting of Al,Mg,Fe,Si and O ions,possesses more polar sites to immobilize LiPSs in comparison with single metal oxides.In addition,the catalytic nature(Fe ions)of attapulgite avails the LiPSs conversion reaction,which is further confirmed by the linear sweep voltammetry and electrochemical impedance spectroscopy.Benefited from the synergistic effect of multi-metal oxide and conductive carbon,the Li-S battery with the modified separator delivers remarkable discharge capacities of 1059.4 mAh g-1 and 792.5 mAh g-1 for the first and 200th cycle at 0.5 C,respectively.The work presents an effective way to improve the electrochemical performance of Li-S batteries by employing attapulgite nanorods assisted separator surface engineering.

Enhancing interfacial stability in solid-state lithium batteries with polymer/garnet solid electrolyte and composite cathode framework

The solid-state lithium battery is considered as an ideal next-generation energy storage device owing to its high safety,high energy density and low cost.However,the poor ionic conductivity of solid electrolyte and low interfacial stability has hindered the application of solid-state lithium battery.Here,a flexible polymer/garnet solid electrolyte is prepared with poly(ethylene oxide),poly(vinylidene fluoride),Li6.75La3 Zr1.75Ta0.25O12,lithium bis(trifluoromethanesulfonyl)imide and oxalate,which exhibits an ionic conductivity of 2.0 ×10^(-4) S cm^(-1) at 55℃,improved mechanical property,wide electrochemical window(4.8 V vs.Li/Li+),enhanced thermal stabilities.Tiny acidic OX was introduced to inhibit the alkalinity reactions between Li6.75La3 Zr1.75Ta0.25O12 and poly(vinylidene fluoride).In order to improve the interfacial stability between cathode and electrolyte,an Al2 O3@LiNi0.5Co0.2Mn0.3O2 based composite cathode framework is also fabricated with poly(ethylene oxide) polymer and lithium salt as additives.The solid-state lithium battery assembled with polymer/garnet solid electrolyte and composite cathode framework demonstrates a high initial discharge capacity of 150.6 mAh g^(-1) and good capacity retention of 86.7% after 80 cycles at 0.2 C and 55℃,which provides a promising choice for achieving the stable electrode/electrolyte interfacial contact in solid-state lithium batteries.

Study on the green upconversion saturation in Er^(3+) doped oxyfluoride tellurite glass

The upconversion emission spectra of Er^3＋ doped oxyfluoride tellurite glasses excited by 808 nm laser diode （LD） were measured. The dependence of 550 nm upconversion emission on the excitation intensity was analyzed. Quadratic intensity dependence was only observed at weak excitation intensity. With increasing the excitation intensity, saturation was turned out. The experimental results were fitted to a model based on the rate equations.

Te0.045S0.955PAN composite with high average discharge voltage for Li–S battery

As a sulfur-containing cathode material,sulfide polyacrylonitrile(SPAN)is expected to be used for longlife lithium-sulfur battery because there is no shuttle effect occurred in its charge process.However,its specific capacity and discharge potential need to be further improved to satisfy the urgent demands for high-performance batteries.In this paper,Te0.045S0.955PAN composite was synthesized by co-heating TexS1-x and PAN,and the superior electrochemical performance to that of SPAN was obtained because of doping Te with high conductivity.The as-prepared Te0.045S0.955PAN composite possessed the specific capacity of 675 mAh g^-1 after 100 cycles at the current density of 0.1 A g^-1 with high capacity retention of96.6%compared to the second cycle.Especially,during cycling,Te0.045S0.955PAN showed average discharge voltages of 1.88-1.91 V,which were higher than 1.85-1.88 V for SPAN at the same current density.Thus doping Te provides a new strategy for increasing the energy density of SPAN.