Influence of Cathode Materials on Opening Performance of Plasma Opening Switch

Experiments have been conducted on a plasma opening switch (POS) test-bed to investigate the influence of cathode materials made of aluminum, stainless steel, molybdenum and tungsten on opening performance for conduction time up to 3 microseconds, conduction current up to 100 kA. Remarkaly different opening characteristics have been shown for these materials,with tungsten being of the best opening performance.

A universal performance-enhancing method for Li-S batteries:the cathode material of Li_(2)S@Li_(2)S_(2)@Li_(2)S_(6) double-shell structure

Lithium sulfide(Li_(2)S)as a cathode material for lithium-sulfur(Li-S)batteries,one of the most promising advanced batteries in the future,has received tremendous attention in the past decades.However,developing the practical Li_(2)S cathode confronts challenges of low conductivity for Li-ions and electrons,high sensitivity to environmental moisture,big overpotential barrier to electrochemical activation,and poor cyclability due to the shuttle effect of intermediate species.This article herein reports a simple and effective strategy for making Li_(2)S@Li_(2)S_(2)@Li_(2)S_(6) double-shelled microparticles,which can significantly mitigate these problems.They are synthesized by dissolving Li2S together with S in dimethoxyethane,then drying off the solvent,and finally calcining the collected solid.Compared with pure Li_(2)S,such a double-shell material presents a 26.7% improvement in cycling capacity,0.5 V lower in activation overpotential,and prolonged tolerance in the ambient environment.The density functional theory calculation shows that the performance enhancement lies in the higher stability of Li2S6in contact with moisture and some autocatalytic effect of Li_(2)S_(2)@Li_(2)S_(6).Such a double-shell structure becomes a universal performanceenhancing approach when being combined with other means,such as cathodes composited with catalytic MoS_(2),separators modified with selenium-doped sulfurized-polyacrylonitrile/montmorillonite,electrolytes containing fluorenone additive,and Li anodes coated with a layer of Li_(3)N.The corresponding capacity retention shows up to 80%improvement compared with pure Li_(2)S.

Improved High-rate Performance and Cycling Stability of 1D LiFePO_4 Nanorods by a Facile Annealing Process

To alleviate the main limitations of lithium ion diffusion rate and poor electronic conductivity for LiFePO4 cathode material, it is desirable to synthesize nano-size LiFePO4 material due to its enhanced electronic and lithium ion transport rates and thus an improved high-rate performance. However, our previous synthesized LiFePO4 nanorods only exhibited low high-rate and slightly unstable cycle performance. Possible reasons are the poor crystallization and Fe2＋ oxidation of LiFePO4 nanorods prepared by hydrothermal method. In this paper, LiFePO4 nanorods were simply dealt with at 700 ℃ for 4 h under the protection of Ar and H2 mixture gas. The electrochemical properties of LiFePO4/Li cells were investigated by galvanostatic test and cyclic voltammetry（CV）. The experimental results indicated that the annealed LiFePO4 nanorods delivered an excellent cycling stability and obviously improved capacity of 150 mA·h·g-1 at 1C, and even 122 mA·h·g-1 at 5C.

Recent advances in cathode materials for Li-S battery:structure and performance

Li–S battery is one of the most promising candidates for next-generation energy storage technology.However, the rapid capacity fading and low-energy-density limit its large-scale applications. Scholars invest a lot of effort to introduce new materials. A neglected problem is that reasonable structure is as important as new material. In this review, four kinds of cathode structures were analyzed through morphology and electrochemical properties. The relationship between structures and properties was elaborated through reaction mechanism. The advantages and disadvantages of each structure were discussed. We hope the summary and discussion provide inspiration for structure design in Li–S battery cathode materials.

Manganese Dioxide with High Specific Surface Area for Alkaline Battery

The authors reported a facile method for the synthesis of manganese dioxide without any template and catalyst at a low-temperature. The prepared sample was characterized with X-ray diffraction（XRD）, scanning electron microscopy（SEM）, Brunauer-Emmett-Teller（BET） surface analysis, Fourier transform infrared（FTIR） spectrometry, cyclic voltammetry, alternative current（AC） impedance test and battery discharge test. It is found that the prepared sample belongs to α-MnO2 and has a microsphere morphology and a large BET surface area. The electrochemical characterization indicates that the prepared sample displays a larger electrochemical capacitance than the commercial electrolytic manganese dioxides（EMD） in Na2SO4 solution, and exhibits larger discharge capacity than EMD, especially at a high rate discharge condition when it is used as cathode of alkaline Zn/MnO2 battery.

A nanoporous nitrogen-doped graphene for high performance lithium sulfur batteries

A nanoporous N-doped reduced graphene oxide（p-N-rGO） was prepared through carbothermal reaction between graphene oxide and ammonium-containing oxometalates as sulfur host for Li-S batteries.The p-N-rGO sheets have abundant nanopores with diameters of 10-40 nm and the nitrogen content is 2.65 at%.When used as sulfur cathode,the obtained p-N-rGO/S composite has a high reversible capacity of 1110mAhg^-1 at 1C rate and stable cycling performance with 781.8 mAhg-1 retained after 110 cycles,much better than those of the rGO/S composite.The enhanced electrochemical performance is ascribed to the rational combination of nanopores and N-doping,which provide efficient contact and wetting with the electrolyte,accommodate volume expansion and immobilize polysulfides during cycling.