Progress on High Voltage PEO-based Polymer Solid Electrolytes in Lithium Batteries

Polymer electrolytes have attracted great interest for next-generation lithium-based batteries on account of safety and high energy density. In this review, we assess recent progress on the design of poly(ethylene oxide)(PEO)-based solid polymer electrolytes in high voltage lithium batteries and identify possible side reactions between PEO-based electrolytes and existing cathodes. We provide an overview of the ways to enhance high voltage resistance of PEO-based electrolytes. Those include components blend, molecular design and interface modification. With these efforts, we want to present new insights into rational design of PEO-based electrolytes to develop solid-state lithium batteries for advanced performance.     

Electric field induced metal–insulator transition in VO2 thin film based on FTO/VO2/FTO structure

A VO₂ thin film has been prepared using a DC magnetron sputtering method and annealing on an F-doped SnO₂ (FTO) conductive glass substrate. The FTO/VO₂/FTO structure was fabricated using photolithography and a chemical etching process. The temperature dependence of the I–V hysteresis loop for the FTO/VO₂/FTO structure has been analyzed. The threshold voltage decreases with increasing temperature, with a value of 9.2 V at 20 °C. The maximum transmission modulation value of the FTO/VO₂/FTO structure is 31.4% under various temperatures and voltages. Optical modulation can be realized in the structure by applying an electric field.     

The effect of applied negative bias voltage on the structure of Ti-doped a-C:H films deposited by FCVA

Ti-doped hydrogenated diamond-like carbon (DLC) films were deposited on Si(1 0 0) substrates by a filtered cathodic vacuum arc (FCVA) method using Ar and CH₄ as the feedstock. The composition and microstructure of the films were investigated by Raman spectroscopy, X-ray photoelectron spectroscopy and IR spectroscopy. The internal stress was determined by the radius of curvature technique. The influence of the bias voltage on the microstructure of the as-deposited films was investigated. It was found that the graphite-like bonds was dominated in the Ti-doped DLC film deposited at 0 V bias voltage. When bias voltage was increased to −150 V, more diamond-like bond were produced and the sp³ content in film reached the maximum value, after which it decreased and more graphite-like bonds feature produced with further increase of the negative bias voltage. The compressive internal in the Ti-doped DLC films also exhibited a maximum value at −150 V bias voltage. IR results indicated that CH bonded intensity reduced, and H atoms bonded with C atoms were substituted for the Ti atoms as the negative bias voltage increasing. All the composition and microstructure change can be explained by considering the plasma conditions and the effect of negative bias voltage applied to the substrate.     

Remarkably improved cycling stability of 3D porous Cu–Sn anode for lithium-ion full cells by adjusting working voltage range

Numerous studies confirm that three dimensional porous Cu–Sn (3DP Cu–Sn) anode possesses good application prospect in light of its desirable electrochemical performance on lithium ion half cells, but there are a few related systematic researches on lithium ion full cells until now, which is indispensable before its commercialization. Herein, the effects of galvanostatic charge-discharge voltage range on the cycling stability of 3DP Cu–Sn anode for lithium ion full cells are investigated systematically. The results show that the suitable charge-discharge voltage range plays a key role in improving the reversible capacity and cycling stability of the 3DP Cu–Sn||LiCoO₂ full cell, which is closely related to maintaining the electrode structure stable by controlling the amount of Li⁺ extracted and inserted. Especially, in the voltage range of 1.2–3.9 ​V, the full cell exhibits remarkably improved electrochemical properties with the high initial reversible capacity of 2.71 ​mAh cm⁻² and 71.95% capacity retention upon 80 cycles. We believe that this work can provide a significant reference for the practical application of porous Sn-based anodes.     

二硫化锡纳米片阻变存储器的制备与性能

采用水热法合成了尺寸为50~100 nm的二硫化锡纳米片,并首次以二硫化锡作为阻变层材料的阻变存储器（Cu/PMMA/SnS₂/Ag,PMMA=聚甲基丙烯酸甲酯）,对其阻变性能进行了研究。结果表明： Cu/PMMA/SnS₂/Ag阻变存储器的开关比约10⁵,耐受性2.7×10³。在上述2项性能指标达到较优水平的同时,开态与关态电压分别仅约为0.28与-0.19 V。     

Sulfone-based high-voltage electrolytes for high energy density rechargeable lithium batteries:Progress and perspective

Further enhancement in the energy density of rechargeable lithium batteries calls for high-voltage cathode materials and stable anodes,as well as matched high-voltage electrolytes without compromising the overall property of batteries.Sulfone-based electrolytes have aroused great interest in recent years owing to their wide electrochemical window and high safety.However,significant challenges such as the complexity of synthesis,high melting point(typically above room temperature),high viscosity,and their poor compatibility with graphite-based anodes have drastically impeded their practical applications.In this review,recent progress of sulfone solvents in high energy density rechargeable lithium batteries is summarized theoretically and experimentally.More importantly,general improvement methods of sulfone-based electrolytes,such as adding additives and cosolvents,structural modifications of sulfo ne,superconcentrated salt strategy are briefly discussed.We expect that this review provides inspiration for the future developments of sulfone-based high-voltage electrolytes(SHVEs) and their widespread applications in high specific energy lithium batteries.     

Modelling photovoltaic modules with neural networks using angle of incidence and clearness index

A neural network for modelling photovoltaic modules using angle of incidence and clearness index is proposed. Engineers require methods to estimate the output of a photovoltaic plant depending on meteorological conditions. Therefore, models for the grid inverter and the generator must be provided, and their outputs must be combined. The connection between both models is related to the maximum power point of the generator and how it is tracked by the inverter. That maximum power point under specific conditions of irradiance and module temperature is determined by the I–V curve of the module, which must be simulated under those conditions. Algebraic procedures were used to simulate the I–V curve. Recently, neural networks have been used for the same purpose. Previous methods only take into account the irradiance and the module temperature. The model proposed is based on neural networks, and it uses not only the irradiance and the module temperature but also the angle of incidence and the instantaneous clearness index as additional inputs. The normalised clearness replaces the standard clearness index because it allows the removal of the hourly trend found in this last index. This new model improves the results obtained with previous ones as it can distinguish amongst samples with the same solar irradiance and temperature values but with different angle of incidence and instantaneous clearness index. Results show that this model could be used to improve the accuracy of the tools used to forecast the output of photovoltaic plants. Copyright © 2014 John Wiley & Sons, Ltd.     

Effect of lithium intercalation on the photovoltaic performances of photovoltachromic cells

In the last few years, a new class of smart multifunctional photoelectrochemical devices has been attracting the interest of several academic institutions and industrial companies: photovoltachromic cells, combining the features of photoelectrochromic cells with those of dye‐sensitized solar cells. Here, we report the results of a detailed electrochemical analysis aiming at investigating the electrochemical behavior of these complex photoelectrochemical devices. In particular, we have been focused on the effect of Li⁺ ions displacement during the coloration of the electrochromic tungsten oxide on the performances of the photovoltaic unit. As we had previously observed striking differences between the performances of the barely photovoltaic mode (with the tungsten oxide in the bleached state) and the photovoltachromic mode (with the tungsten oxide in the colored state), we thus attempted to provide a reasonable physical interpretation to the observed phenomena. Copyright © 2013 John Wiley & Sons, Ltd.     

Effect of relative humidity on current–voltage characteristics of monopolar DC wire-to-plane system

This paper deals with the DC monopolar corona discharge in wire-to-plane geometry under variable humid air conditions. The classical formulas of Townsend commonly used for the current–voltage characteristics were used to determine the various corona parameters for the both polarities of the corona discharge. A circular biased probe has been adapted to the plane and is used to measure the ground plane current density and electric field during the monopolar corona discharge. A new approach to the problem of corona discharge in transmission system has been described in this paper. The effect of varying the humidity and wires diameter is also investigated. The values of the electric field and the current density are maximum beneath the corona wire and decrease when moving away from them and the current–voltage characteristics follow the quadratic Townsend's law. The experimental results show that the monopolar corona discharge is strongly affected by the air humidity. The current density and the electric field are measured and compared with the computed values. The agreement between the calculated values and those obtained experimentally is satisfactory. The per unit electric field and current density are also represented by a unique function.     

关于开设内光电效应实验的探索与思考

介绍了开设以内光电效应为理论基础的半导体光电器件的重要性和迫切性,并详细介绍了内光电效应的理论与半导体光电器件的分类和应用前景。