A lithiated gel polymer electrolyte with superior interfacial performance for safe and long-life lithium metal battery

Rechargeable lithium metal batteries(LMBs)have gained much attention recently.However,the short lifespan and safety issues restrict their commercial applications.Here we report a novel gel polymer electrolyte(GPE)based on lithiated poly(vinyl chloride-r-acrylic acid)(PVCAALi)to realize dendritesuppressing and long-term stable lithium metal cycling.PVC chains ensure the quick gelation process and high electrolyte uptake,and lithiated PAA segments enable the increase of mechanical strength,acceleration of lithium-ion transmission and improvement of interfacial compatibility.PVCAALi GPE showed much higher mechanical strength compared with other free-standing GPEs in previous works.It displays a superior ionic conductivity of 1.50 m S cm^(-1) and a high lithium-ion transference number of 0.59 at room temperature.Besides,the lithiated GPE exhibits excellent interfacial compatibility with lithium metal anodes.Lithium symmetrical cells with PVCAALi GPE yield low hysteresis of 50 m V over1000 h at 1.0 m A cm^(-2).And the possible mechanism of the lithiated GPE with improved lithium-ion transfer and interfacial property was discussed.Accordingly,both the Li4Ti5O12/Li and lithium-sulfur(Li-S)cells assembled with PVCAALi GPE show outstanding electrochemical performance,retaining high discharge capacities of 133.8 m Ah g^(-1) and 603.8 m Ah g^(-1) over 200 cycles,respectively.This work proves excellent application potential of the highly effective and low-cost PVCAALi GPE in safe and long-life LMBs.

Copolymer-assisted Polypropylene Separator for Fast and Uniform Lithium Ion Transport in Lithium-ion Batteries

In lithium-ion batteries(LIBs),separators play a vital role in lithium-ion(Li+)transport,and thus affect rate performance,battery life,and safety.Here,a new kind of multifunctional copolymer poly(acrylonitrile-co-lithium acrylate-co-butyl acrylate)(PAAB-Li)is synthesized through soap-free emulsion polymerization,and is used to form homogeneous-covered separator based on PP matrix by a simple dip-annealing process.Compared to the bare PP separator,the modified separators with PAAB-Li enable higher ionic conductivity,higher lithium ion transference number(increased from 0.360 to 0.525),and lower interface impedance(reduced from 155Ω to 34Ω).It has been indicated that PAAB-Li functional layer significantly promotes the fast transport of Li+and improves the compatibility of the separator/electrolyte-electrode interface.The LiCo02/graphite cells with the PAAB-Li-assisted separator demonstrate excellent cycle stability and rate performance.In addition,the Li symmetric cells with the modified separator stably cycle over 800 h,indicating the functional layer effectively suppresses the lithium dendrite growth.This facile strategy can be easily applied to LIBs requiring high safety and even be scalable to Li metal batteries.Moreover,the possible mechanism of the PAAB-Li functional layer promoting fast and uniform Li+transport is discussed in this paper.

Poly(N,N-dimethylaminoethyl methacrylate) Grafted Poly(vinyl chloride)s Synthesized via ATRP Process and Their Membranes for Dye Separation

To functionalize poly（vinyl chloride）（PVC） for various applications, monomers containing tertiary amine group are incorporated into PVC via atom transfer radical polymerization（ATRP） initiated by the labile chlorines in their backbones. The kinetics of synthesis was carefully investigated, and it is proven that the grafting polymerization process can be effectively controlled by regulating the reaction time. The membranes are fabricated using PVC and copolymers by non-solvent induced phase separation（NIPS） process. The hydrophilicity and pore structure of copolymer membranes were enhanced as well, these membranes are endowed with positive charge. When PDMA%（i.e., the PDMA weight percentage in copolymer） is 31.1%, the flux and Victoria blue B rejection are 26.0 L·m·^-2·h^-1（0.5 MPa） and 91.2%, respectively. Thus, the newly synthesized polymer is proven to be a promising material for dye separation with positive charges.

IMPROVING THE PROPERTIES OF HDPE BASED SEPARATORS FOR LITHIUM ION BATTERIES BY BLENDING BLOCK WITH COPOLYMER PE-b-PEG

To improve the performances of HDPE-based separators, polyether chains were incorporated into HDPE membranes by blending with poly（ethylene-block-ethylene glycol） （PE-b-PEG） via thermally induced phase separation （TIPS） process. By measuring the composition, morphology, crystallinity, ion conductivity, etc, the influence of PE-b-PEG on structures and properties of the blend separator were investigated. It was found that the incorporated PEG chains yielded higher surface energy for HDPE separator and improved affinity to liquid electrolyte. Thus, the stability of liquid electrolyte trapped in separator was increased while the interfacial resistance between separator and electrode was reduced effectively. The ionic conductivity of liquid electrolyte soaked separator could reach 1.28 ×10^-3 S.cm^-1 at 25℃, and the electrochemical stability window was up to 4.5 V （versus Li^＋/Li）. These results revealed that blending PE-b-PEG into porous HDPE membranes could efficiently improve the performances of PE separators for lithium batteries.

中空纤维膜脱氧过程中Dean涡强化传质研究（英文）

目的:在螺旋中空纤维膜脱氧过程中引入了Dean涡,与线型中空纤维膜脱氧过程相比传质速率显著提升。本文旨在建立新的螺旋中空纤维膜脱氧过程传质模型,探讨管程流体雷诺数、中空纤维膜结构参数、壳程真空度和操作温度对Dean涡强化传质效果的影响,并优化螺旋中空纤维膜脱氧过程操作参数。创新点:1.建立新的螺旋中空纤维膜脱氧过程传质模型;2.该传质模型可以应用于任何螺旋中空纤维膜气-液过程的传质行为描述。方法:1.实验研究管程流体雷诺数、中空纤维膜结构参数、壳程真空度和操作温度对Dean涡强化传质效果的影响,并与线型中空纤维膜传质进行对比。2.利用螺旋坐标系下的质量连续性方程以及Dean涡的摄动解描述管程溶质的传质行为;利用改进的尘气模型描述膜孔道内多组份气体的扩散行为;耦合建立新的螺旋中空纤维膜脱氧过程传质模型,并与实验结果进行比较。3.模拟脱氧过程的氧、氮、水三种组分的浓度分布,优化螺旋中空纤维膜脱氧过程的膜结构参数和操作参数。结论:1.实验和模拟结果均证实Dean涡可以有效提升脱氧传质速率,最大传质增强因子为2.2。2. Dean涡主要受到管程雷诺数和中空纤维膜曲率的影响;当管程雷诺数较大时,中空纤维膜即使存在很小的曲率,传质的速率也有显著的提升。