Linear coupling of alignment with transport in a polymer electrolyte membrane

Polymer electrolyte membranes (PEMs) selectively transport ions and polar molecules in a robust yet formable solid support. Tailored PEMs allow for devices such as solid-state batteries,'artificial muscle' actuators and reverse-osmosis water purifiers. Understanding how PEM structure and morphology relate to mobile species transport presents a challenge for designing next-generation materials. Material length scales from subnanometre to 1 μm influence bulk properties such as ion conductivity and water transport. Here we employ multi-axis pulsed-field-gradient NMR to measure diffusion anisotropy, and (2)H NMR spectroscopy and synchrotron small-angle X-ray scattering to probe orientational order as a function of water content and of membrane stretching. Strikingly, transport anisotropy linearly depends on the degree of alignment, signifying that membrane stretching affects neither the nanometre-scale channel dimensions nor the defect structure,causing only domain reorientation. The observed reorientation of anisotropic domains without perturbation of the inherent nematic-like domain character parallels the behaviour of nematic elastomers, promises tailored membrane conduction and potentially allows understanding of tunable shape-memory effects in PEM materials. This quantitative understanding will drive PEM design efforts towards optimal membrane transport, thus enabling more efficient polymeric batteries, fuel cells, mechanical actuators and water purification.     

Carbonized Polymer Dots Assemble in Proton-Conducting Channels to Enhance the Conductivity and Selectivity Simultaneously for High-Performance Fuel Cells

Fabricating polymer electrolyte membranes (PEMs) simultaneously with high ion conductivity and selectivity has always been an ultimate goal in many membrane-integrated systems for energy conversion and storage. Constructing broader ion-conducting channels usually enables high-efficient ion conductivity while often bringing increased crossover of other ions or molecules simultaneously, resulting in decreased selectivity. Here, the ultra-small carbon dots (CDs) with the selective barriers are self-assembled within proton-conducting channels of PEMs through electrostatic interaction to enhance the proton conductivity and selectivity simultaneously. The functional CDs regulate the nanophase separation of PEMs and optimize the hydration proton network enabling higher-efficient proton transport. Meanwhile, the CDs within proton-conducting channels prevent fuel from permeating selectively due to their repelling and spatial hindrance against fuel molecules, resulting in highly enhanced selectivity. Benefiting from the improved conductivity and selectivity, the open-circuit voltage and maximum power density of the direct methanol fuel cell (DMFC) equipped with the hybrid membranes raised by 23% and 93%, respectively. This work brings new insight to optimize polymer membranes for efficient and selective transport of ions or small molecules, solving the trade-off of conductivity and selectivity.     

Preparation of PV dF-based electrospun membranes and their application as separators

A one-step method preparing of poly(vinylidene fluoride)-based electrospun membranes (PEMs) containing TiO₂ has been developed. The effect of TiO₂ on the morphology, degree of crystallization and electrochemical behavior of PEMs was investigated by scanning electron microscopy (SEM), atomic force microscopy (AFM), differential scanning calorimetry (DSC) and electrochemical measurements. The PEMs containing TiO₂ show improved ionic conductivity and cycling performance compared with pure PEMs.     

Preparation of PVdF-based electrospun membranes and their application as separators

Abstract

A one-step method preparing of poly(vinylidene fluoride)-based electrospun membranes (PEMs) containing TiO₂ has been developed. The effect of TiO₂ on the morphology, degree of crystallization and electrochemical behavior of PEMs was investigated by scanning electron microscopy (SEM), atomic force microscopy (AFM), differential scanning calorimetry (DSC) and electrochemical measurements. The PEMs containing TiO₂ show improved ionic conductivity and cycling performance compared with pure PEMs.     

Investigation of ionic conductivity and long-term stability of a LiI and KI coupled diphenylamine quasi-solid-state dye-sensitized solar cell

In this work, enhancement of ionic conductivity and long-term stability through the addition of diphenylamine (DPA) in poly(ethylene oxide) (PEO) is demonstrated. Potassium iodide (KI) is adopted as the crystal growth inhibitor, and DPA is used as a charge transport enhancer in the electrolyte. The modified electrolyte is used with titanium dioxide (TiO2) nanoparticles, which is systematically tuned to obtain high surface area. The dye-sensitized solar cell (DSSC) showed a photocurrent of 14 mAcm2 with a total conversion efficiency of 5.8% under one sun irradiation. DPA enhances the interaction of the TiO2 nanoparticle film and the I-/I3- electrolyte leading to high ionic conductivity (3.5 × 10-3 Scm-1), without compromising on the electrochemical and mechanical stability. Electrochemical impedance spectroscopy (EIS) studies show that electron transport and electron lifetime are enhanced in the DPA added electrolyte due to reduced sublimation of iodine. The most promising feature of the electrolyte is increased device stability with 89% of the overall efficiency preserved even after 40 days.     

Molecular Design of the Solid Copolymer Electrolyte- Poly(styrene-b-ethylene oxide) for Lithium Ion Batteries

Poly(ethylene oxide) (PEO) is a commonly used electrolytic polymer in lithium ion batteries because of its high viscosity which allows fabricating thin layers. However, its inherent low ionic conductivity must be enhanced by the addition of highly conductive salt additives. Also its weak mechanical strength needs a complementary block, such as poly(styrene) (PS), to strengthen the electrolytic membrane during charging/discharging processes. PS is a strong material to complement the PEO and to create a reinforced copolymer electrolyte termed as the poly(styrene-b-ethylene oxide) (PS-PEO). In this work, molecular dynamics simulations are employed to study the effects of doping the PS constituents into the PEO based copolymer electrolyte. The results reveal that strengthening the mechanical strength increases the intra conjugation forces which penalize the ionic conductivity. Hence both ionic conductivity and mechanical strength of the copolymer have to be compromised. This paper designs the optimized molecular structure through the atomistic analysis instead of try-and-error experiments.     

Electrochemical properties of composite electrolytes based on poly(ethylene oxide)/poly(ethylene imine) containing the inorganic silica fillers

In this study, poly(ethylene oxide) (PEO) and poly(ethylene imine) (PEI) polymer blends containing inorganic silica fillers were studied in order to enhance the ion conductivity and interfacial properties. Lithium perchlorate (LiCIO4) as a salt, and silica (SiO2) as the inorganic filler were introduced in the polymer electrolyte composites and were examined to evaluate their use to improve the ionic conductivity. The addition of inorganic fillers in polymer electrolytes has resulted in high ionic conductivity at a room temperature. The structure and morphology of the solid polymer electrolytes were evaluated using X-ray diffraction (XRD) and scanning electron microscope (SEM). The ionic conductivity was measured by an AC impedance method. The enhanced conductivity was dependent on the decreased crystallinity and more heterogeneous morphologies.     

新型电解质材料[BMIM]ClO3离子液体的合成及其物化性能

以N-甲基咪唑为原料合成了室温离子液体1-丁基-3-甲基咪唑氯酸盐([BMIM]ClO3),用IR、NMR、DSC-TGA等手段对产物进行了表征,测定了相关物化性能,如密度、表面张力、黏度、电导率和电化学窗口等,并考察了该离子液体的溶剂性能。结果表明,该离子液体作为新型的电解质材料,具有低黏度、高电导率,密度、表面张力、黏度均随温度升高而减小,电导率随温度升高而增大,与温度符合Arrhenius方程。该离子液体与多数常规溶剂互溶,并对某些金属氧化物具有较高的溶解度,为离子液体在选矿、电解金属氧化物等方面的应用奠定了基础。     

Graphene‐Analogues Boron Nitride Nanosheets Confining Ionic Liquids: A High‐Performance Quasi‐Liquid Solid Electrolyte

Solid electrolytes are one of the most promising electrolyte systems for safe lithium batteries, but the low ionic conductivity of these electrolytes seriously hinders the development of efficient lithium batteries. Here, a novel class of graphene‐analogues boron nitride (g‐BN) nanosheets confining an ultrahigh concentration of ionic liquids (ILs) in an interlayer and out‐of‐layer chamber to give rise to a quasi‐liquid solid electrolyte (QLSE) is reported. The electron‐insulated g‐BN nanosheet host with a large specific surface area can confine ILs as much as 10 times of the host's weight to afford high ionic conductivity (3.85 × 10^?3 S cm^?1 at 25 °C, even 2.32 × 10^?4 S cm^?1 at ?20 °C), which is close to that of the corresponding bulk IL electrolytes. The high ionic conductivity of QLSE is attributed to the enormous absorption for ILs and the confining effect of g‐BN to form the ordered lithium ion transport channels in an interlayer and out‐of‐layer of g‐BN. Furthermore, the electrolyte displays outstanding electrochemical properties and battery performance. In principle, this work enables a wider tunability, further opening up a new field for the fabrication of the next‐generation QLSE based on layered nanomaterials in energy conversion devices.     

P(MMA-VAc-LiAA)聚合物电解质的制备及表征

以甲基丙烯酸甲酯(MMA)、醋酸乙烯酯(VAc)和丙烯酸锂(LiAA)为单体,采用种子乳液聚合法制备了(P(MMA-VAc-LiAA)三元共聚物.利用红外光谱(FTIR),核磁共振(~1HNMR),差示扫描量热(DSC) /热重分析(TG),X射线衍射(XRD),扫描电镜(SEM)等方法对聚合物的结构进行了表征.将P(MMA-VAc-LiAA)与LiClO_4共混,采用流延法制备了聚合物电解质膜,用交流阻抗方法测试了电解质膜的电导率,结果表明,该聚合物电解质室温离子电导率可以达到10~(-3)S/cm.而且离子电导率随着温度的升高而迅速增加,电导率-温度曲线符合Arrhenius方程.机械性能测试结果表明,在P(MMA-VAc)的基础上,引入第三单体LiAA可以改善膜的收缩性与力学性能.     

非晶LiSiON薄膜电解质的全固态薄膜锂电池性能

全固态薄膜锂电池(TFLB)是理想的微电子系统电源.目前报道的固态非晶电解质存在离子电导率偏低的问题,限制了TFLB性能的提升.本工作采用磁控溅射法制备了一种新型非晶锂硅氧氮(LiSiON)薄膜用作TFLB的固态电解质.结果表明,优化制备条件后的LiSiON薄膜具有6.3×10–6 S·cm–1的高离子电导率以及超过5...     

锂离子电解液/环氧乙烯基酯树脂固态电解质的制备与性能

将具备优良化学稳定性及高电导率的双三氟甲烷磺酰亚胺锂（LiTFSI）溶于1-乙基-3-甲基咪唑双三氟甲磺酰亚胺盐（EMIM-TFSI）离子液体中制成LiTFSI-EMIM-TFSI电解液,加入环氧乙烯基酯树脂（VER）中对其进行改性。结果表明,添加了上述电解液后的锂离子电解液/环氧乙烯基酯树脂（LiTFSI-EMIM-TFSI/VER）体系可通过FTIR检测到离子液体的特征吸收峰。随着电解液含量的增加,LiTFSI-EMIM-TFSI/VER体系的孔隙率逐渐增大,沟壑与片层结构逐渐增多。这一变化有利于锂离子的传导,提高体系的电学性能,同时可在一定程度上改善树脂的塑性和韧性,提高LiTFSI-EMIM-TFSI/VER体系的力学性能。在本实验中,当电解液含量为40wt%时,LiTFSI-EMIM-TFSI/VER体系多功能性得以最好地实现。     

离子液体及其在双电层电容器领域的新应用

离子液体作为一种新型绿色溶剂,在双电层电容器领域的应用受到极大关注。本文讨论了影响EDLC比电容的电极材料和电解液两大因素,着重对离子液体这一新兴的绿色溶剂进行探讨,并介绍了以碳纳米管为电极材料、离子液体为电解液制造EDLC的研究开发现状及发展趋势。     

Sulfide‐Based Solid‐State Electrolytes: Synthesis,Stability, and Potential for All‐Solid‐State Batteries

Due to their high ionic conductivity and adeciduate mechanical features for lamination, sulfide composites have received increasing attention as solid electrolyte in all‐solid‐state batteries. Their smaller electronegativity and binding energy to Li ions and bigger atomic radius provide high ionic conductivity and make them attractive for practical applications. In recent years, noticeable efforts have been made to develop high‐performance sulfide solid‐state electrolytes. However, sulfide solid‐state electrolytes still face numerous challenges including: 1) the need for a higher stability voltage window, 2) a better electrode–electrolyte interface and air stability, and 3) a cost‐effective approach for large‐scale manufacturing. Herein, a comprehensive update on the properties (structural and chemical), synthesis of sulfide solid‐state electrolytes, and the development of sulfide‐based all‐solid‐state batteries is provided, including electrochemical and chemical stability, interface stabilization, and their applications in high performance and safe energy storage.     

锂盐对交联PPCMA聚合物电解质性能的影响

以二氧化碳(CO2)、环氧丙烷(PO)和马来酸酐(MA)三元共聚反应合成聚甲基乙撑碳酸酯马来酸酐(PPCMA),再经交联和浸渍电解液活化,制备了性能优良的PPCMA凝胶聚合物电解质。研究发现,随着交联剂过氧化二异丙苯(DCP)的增加,交联PPCMA的玻璃化转变温度升高,热稳定性增强,PPCMA凝胶聚合物电解质的离子电导率先增加后减小,当DCP用量为1.2%、LiClO4浓度为1.1mol/dm3、LiBOB质量分数为1.3%时,PPCMA凝胶聚合物电解质的室温离子电导率达到最大值1.47×10-2S/cm。Li/PPCMAGPE/LiNi1/3Co1/3Mn1/3O2聚合物锂离子电池的首次放电容量为115.3mAh/g。     

Effect of ZnO nanoparticles on the structure and ionic relaxation of poly(ethylene oxide)-LiI polymer electrolyte nanocomposites

The effect of ZnO nanoparticles on the structure and ionic relaxation of LiI salt doped poly(ethylene oxide) (PEO) polymer electrolytes has been investigated. X-ray diffraction, high resolution transmission electron microscopy and field emission scanning electron microscopy show that ZnO nanoparticles dispersed in the PEO-LiI polymer electrolyte reduce the crystallinity of PEO and increase relative smoothness of the surface morphology of the nanocomposite electrolyte. The electrical conductivity of the nanocomposites is found to increase due to incorporation of ZnO nanoparticles. We have shown that the structural modification due to insertion of ZnO nanoparticles results in the enhancement of the mobility i.e., the hopping rate of mobile Li+ ions and hence the ionic conductivity of PEO-LiI-ZnO nanocomposite electrolyte.     

硫化物固态电解质Li6PS5Cl的球磨-固相烧结制备与性能

硫银锗矿结构的硫化物固态电解质Li₆PS₅Cl（LPSC）具有离子电导率高（>3×10^-3 S·cm^-1）和对锂稳定性良好等特点,是构建全固态锂离子电池的理想电解质材料之一,具有良好的发展前景。本工作采用高能球磨和惰性气氛固相烧结相结合的方法制备硫银锗矿型固态电解质LPSC,并采用粉末X射线衍射（XRD）、拉曼光谱（Raman spectra）和扫描电子显微镜（SEM）等对其进行表征,探究制备工艺对LPSC结构、成分和电学性质等的影响。结果表明：高能球磨会破坏原料的晶粒,降低晶粒尺寸,延长球磨时间有利于LPSC前驱体粉末的非晶化和后续烧结,提高烧结温度将促进制备的LPSC电解质的物相变纯和离子电导率升高,但烧结温度过高会导致LPSC的分解。综合考虑球磨时间和烧结温度对材料离子电导率和电子电导率的影响,经8 h球磨和500℃烧结制备的LPSC在室温下具有最高的离/电子电导率比（2.091×10⁵）,其离子电导率高达4.049×10^-3 S·cm^-1,而电子电导率仅为1.936×10^-8 S·cm^-1。利用该电解质制备的712 NCM/LPSC/In-Li全固态电池在0.1 C的充放电倍率下首周放电比容量高达151.3 mAh·g^-1,且具有优良的循环稳定性。     

锂磷氧氮电解质在无机薄膜锂电池中的应用

锂磷氧氮(LiPON,lithium phosphorous oxynitride)薄膜具有较高的离子电导率,极低的电子电导率,很宽的电化学稳定窗口等优点而成为全固态无机薄膜锂电池首选的电解质材料.简要介绍了LiPON薄膜的特性与制备方法,综述了国内外LiPON薄膜为电解质的薄膜锂电池的研究情况,并简要评述了目前薄膜锂电池制备中遇到的困难和今后的研究方向.     

Studies on electrical double layer capacitor with a low-viscosity ionic liquid 1-ethyl-3-methylimidazolium tetracyanoborate as electrolyte

The performance of an electrical double layer capacitor (EDLC) composed of high surface area activated carbon electrodes and a new ionic liquid, 1-ethyl-3-methylimidazolium tetracyanoborate, [EMIm]TCB, as the electrolyte has been investigated by impedance spectroscopy, cyclic voltammetry and galvanostatic charge–discharge studies. The high ionic conductivity (~1·3 × 10^???2 S cm^???1 at 20 °C) and low viscosity (~22 cP) of the ionic liquid, [EMIm]TCB, make it attractive as electrolyte for its use in EDLCs. The optimum capacitance value of 195·5 F g^???1 of activated carbon has been achieved with stable cyclic performance.     

RETRACTED ARTICLE: Determination of dopant of ceria system by density functional theory

Oxides with the cubic fluorite structure, e.g., ceria (CeO₂), are known to be good solid electrolytes when they are doped with cations of lower valence than the host cations. The high ionic conductivity of doped ceria makes it an attractive electrolyte for solid oxide fuel cells, whose prospects as an environmentally friendly power source are very promising. In these electrolytes, the current is carried by oxygen ions that are transported by oxygen vacancies, present to compensate for the lower charge of the dopant cations. Ionic conductivity in ceria is closely related to oxygen-vacancy formation and migration properties. A clear physical picture of the connection between the choice of a dopant and the improvement of ionic conductivity in ceria is still lacking. Here we present quantum-mechanical first-principles study of the influence of different trivalent impurities on these properties. Our results reveal a remarkable correspondence between vacancy properties at the atomic level and the macroscopic ionic conductivity. The key parameters comprise migration barriers for bulk diffusion and vacancy–dopant interactions, represented by association (binding) energies of vacancy–dopant clusters. The interactions can be divided into repulsive elastic and attractive electronic parts. In the optimal electrolyte, these parts should balance. This finding offers a simple and clear way to narrow the search for superior dopants and combinations of dopants. The ideal dopant should have an effective atomic number between 61 (Pm) and 62 (Sm), and we elaborate that combinations of Nd/Sm and Pr/Gd show enhanced ionic conductivity, as compared with that for each element separately. An erratum to this article can be found at