Recent advances on battery separators based on poly(vinylidene fluoride) and its copolymers for lithium-ion battery applications

Lithium-ion batteries represent one of the most suitable systems for effective energy storage for a wide range of applications, such as smartphones, laptops, electric vehicles, or even home storage systems. Among the different battery components, the separator plays an essential role in the performance of the batteries; its most relevant characteristics are (micro)structure, wettability, thermal and mechanical properties, and ionic conductivity value. This work provides a comprehensive review of the current state of the art in lithium-ion battery separator membranes based on poly(vinylidene fluoride) (PVDF) and its copolymers. The most recent developments in the last two years are presented, focusing on the different separator types that have been developed with the aim of improving wettability, thermal characteristics, and cycling behavior. The most used types of PVDF separators are composites, polymer blends, and the combination of both. Among the most common fillers, metal–organic frameworks, ionic liquids, and ceramic particles have been used for the development of PVDF-based composites and polymers such as poly(m-phenylene isophthalamide), poly(acrylonitrile), poly(tetrafluoroethylene), or poly(methyl methacrylate), for the development of polymer blends. Electrospinning is one of the most used processing techniques to improve wettability, thermal stability, and mechanical properties. The wettability of separators has been also improved by using PVDF as a coating on commercial separators.It is shown that PVDF-based battery separators can play an important role in the next generation of high-performance batteries.     

Effect of Ionic Liquid Anion Type in the Performance of Solid Polymer Electrolytes Based on Poly(Vinylidene fluoride‐trifluoroethylene)

The effect of different anions within the ionic liquid in the characteristics of solid polymer electrolytes (SPEs) based on P(VDF‐TrFE) has been investigated. 1‐ethyl‐3‐methylimidazolium acetate, [C₂mim][OAc], 1‐ethyl‐3‐methylimidazolium triflate, [C₂mim][(CF₃SO₃)], 1‐ethyl‐3‐methylimidazolium lactate, [C₂mim][Lactate], 1‐ethyl‐3‐methylimidazolium thiocyanate, [C₂mim][SNC] and 1‐ethyl‐3‐methylimidazolium hydrogen sulfate [C₂mim][HSO₄] have been used in SPE prepared by solvent casting. The polymer phase, thermal and electrochemical properties of the SPE have been determined. The thermal and electrical properties of the SPEs strongly depend on the selected IL, as determined by their different interactions with the polymer matrix. The room temperature ionic conductivity increases in the following way for the different anions: [SNC]>[CF₃SO₃)]>[HSO₄]>[Lactate]>[OAc], which is mainly dependent on the viscosity of the ionic liquid.     

旋风分离器减阻杆结构及减阻前后流场的测定与分析

报告了在旋风分离器内安装不同断面形状及尺寸的细杆（简称减阻杆）后对流动阻力降低及安装减阻杆前后旋风分离器内流场变化的测定结果，得出了减阻幅度与减阻杆插入长度和迎风面积及背风面曲率半径成正比、减阻杆使切向速度及轴向速度梯度减小、径向上静压梯度减小和轴向上逆压梯度减小等结论．本文同时对减阻杆的减阻机理及减阻时保证分离效率或提高分离效率的原因进行了分析．     

Total Integration of the Sample Injection,Microdroplet Reaction,Phase Separation,Real-Time Optical Detection,and Recovery of Diverse Silver–Gold Bimetallic Nanoalloys in a Continuous Process

Microfluidic droplet generators have garnered great attention due to the uniformity, high-throughput capability, and facile experimental setup. To maximize the potentials of droplet technology as a chemical/biological nanoliter-scale reactor, the downstream processes such as separation of the aqueous and oil phase, real-time monitoring of the products formed in droplets, and the final product recovery from the droplets is necessary. In this study, the droplet is utilized as a chemical reactor to synthesize a variety of Ag and Au bimetallic nanoalloys in a fully integrated microsystem including sample injection, a T-junction droplet generator, droplet reaction, water–oil phase separation, real-time UV–vis absorbance detection, and product recovery. The flow rate of the Ag nanoparticle (NP) solution and the HAuCl₄ solution was tuned to generate different molar ratios of Ag and Au components. The in-line UV–vis absorbance spectrometer displays a peak shift of the Ag/Au bimetallic alloys depending on the molar ratio of Ag/Au in the continuous process, enabling to judge the kind of the Ag/Au alloys in situ and collect a variety of Ag/Au nanoalloys. Thus, the desired nanomaterials can be obtained with minimal trial and error, saving time and cost.     

Magnetic nanoparticles separation based on nanostructures

This study describes a magnetic array, which consists of depositing Fe nanowires on a porous alumina membrane. Such a device can be used as a planar magnetic separator. Its performance for the collection of Fe₃O₄ nanoparticles is experimentally shown. For magnetization of such iron nanowires in the vertical direction, we propose equations to calculate the theoretical absorption ratio.     

A linear time algorithm to list the minimal separators of chordal graphs

Kumar and Madhavan [Minimal vertex separators of chordal graphs, Discrete Appl. Math. 89 (1998) 155-168] gave a linear time algorithm to list all the minimal separators of a chordal graph. In this paper we give another linear time algorithm for the same purpose. While the algorithm of Kumar and Madhavan requires that a specific type of PEO, namely the MCS PEO is computed first, our algorithm works with any PEO. This is interesting when we consider the fact that there are other popular methods such as Lex BFS to compute a PEO for a given chordal graph.     

Application of Guar Gum and its Derivatives as Green Binder/Separator for Advanced Lithium-Ion Batteries

Since their first commercialization in the 1990s,lithium-ion batteries (LIBs) have become an indispensible part of our everyday life in particular for portable electronic devices. LIBs have been considered as the most promising sustainable high energy density storage device. In recent years, there is a strong demand of LIBs for hybrid electric and electric vehicles to lower carbon footprint and mitigate climate change. However, LIBs have several issues, for example, high cost and safety issues such as over discharge, intolerance to overcharge, high temperature operation etc. To address these issues several new types of electrodes are being studied. Traditional binder PVDF is costly, difficult to recyle, undergoes side reactions at high temperature and cannot stabilize high energy density electrodes. To overcome these challenges, diiferent binders have been introduced with these electrodes. This minireview is focused on the application of guar gum as a binder for different electrodes and separator. The electrochemical performance of electrodes with guar gum has been compared with other binders.     

锂离子电池凝胶聚合物隔膜的研究进展

作为锂离子电池重要组分,隔膜由多孔聚烯烃高分子材料组成;电解质体系由有机碳酸酯和六氟磷酸锂混合组成,虽具有高离子电导率,但因液态碳酸酯的易燃特性给锂离子电池带来了安全隐患。利用能够将液态电解质体系凝胶化的聚合物制备得到的凝胶聚合物隔膜,结合了液态电解质体系高电导率和固态电解质高安全性的优点。凝胶聚合物隔膜的研究从简单微孔凝胶聚合物隔膜开始,经历了引入少量纳米无机颗粒的掺杂凝胶聚合物隔膜,到引入大量纳米颗粒的凝胶陶瓷隔膜的发展历程。本文详细介绍这三种类型凝胶聚合物隔膜的物理化学特性,最后展望凝胶聚合物隔膜的发展趋势。     

高安全性阻燃动力锂离子电池隔膜

逐年加剧的能源短缺以及日益严重的环境污染问题使得发展电动汽车日益迫切.电动汽车安全问题对动力锂离子电池在大功率输出和高安全性能等方面提出了更高的要求.隔膜电解质体系是制约动力锂离子电池快速发展的重要瓶颈之一,因此,开发高性能的隔膜对提高动力锂离子电池的综合性能至关重要.本文综述了近年来隔膜材料的种类、制备工艺、性能以及本课题组在高安全性阻燃动力锂离子电池隔膜方面的研究进展,并对未来电池隔膜的发展方向进行了预期和展望.     

紫外光辐照接枝MMA改性锂离子电池PE隔膜

采用紫外光辐照接枝的方法,通过本体聚合,将甲基丙烯酸甲酯（MMA）接枝至聚乙烯（PE）隔膜表面,以改善其对电解液的润湿性能。结果表明：通过紫外光辐照可实现有效的表面接枝,当引发剂质量浓度为0.10 g/mL,光照时间为150 s时,表面接枝率达到49.15%,通过扫描电镜、原子力显微镜等对膜表面形貌变化进行了观察,静态...