New approaches to developing lithium polymer batteries

The electrochemical and physical-chemical properties of two families of lithium ion conducting membranes, i.e., the blends between high molecular weight poly(ethylene oxide) with a lithium salt commonly named "polymer electrolytes" and the gels of liquid solutions in a polymer matrix commonly named "gel electrolytes," are repoted and discussed. Particular attention is devoted to the newly developed approach of dispersing ceramic powders at the nanoscale particle dimension into the two types of membranes. This leads "nanocomposite" membranes having unique features, such as improved transport and interfacial properties in the case of the polymer electrolytes and enhanced liquid retention capability in the case of the gel electrolytes. Finally, the use of the gel electrolytes for the development of new-design, plastic-like, lithium-ion batteries is illustrated.     

Investigation of Nanocomposite Polymer Electrolytes for Lithium Ion Batteries

Composite polymer electrolytes based on polyvinyl alcohol: polyvinylidine fluoride: lithium triflate doped with different concentration of nanosilica have been prepared by the solution casting technique. The prepared films are transparent and mechanically stable. Interaction of SiO₂ nanoparticles with the host polymer in the composite polymer electrolyte has been confirmed using X-ray diffraction, Fourier transform infrared spectroscopy, and photoluminescence spectra. Dispersion of nanofiller in the polymer matrix help to increase the free volume of the system and thus increases amorphous nature. The optimal composition of composite polymer electrolytes was found possessing high conductivity, thermal, mechanical and electrochemical stability, which will be well suited for lithium ion battery applications.     

高锂离子电导的有机-无机复合电解质的渗流结构设计

固态聚合物电解质被认为是解决传统液态锂金属电池安全隐患和循环性能的关键材料,但仍然存在离子电导率低,界面兼容性差等问题。近年来,基于无机填料与聚合物电解质的高锂离子电导的有机-无机复合电解质备受关注。根据渗流理论,有机-无机界面被认为是复合电解质离子电导率改善的主要原因。因此,设计与优化有机-无机渗流界面对提高复合电解质离子电导率具有重要意义。本文从渗流结构的设计出发,综述了不同维度结构的无机填料用于高锂离子电导的有机-无机复合电解质的研究进展,并对比分析了不同渗流结构的优缺点。基于上述评述,展望了有机-无机复合电解质的未来发展趋势和方向。     

Enhancing the ionic conductivity in a composite polymer electrolyte with ceramic nanoparticles anchored to charged polymer brushes

Polymer electrolytes a re essential for next-gene ration lithium batteries because of their excellent safety record.However,low ionic conductivity is the main obstacle restricting their commercial application.Composites with nanoparticles are a promising route to overcome this obstacle.In this work,lithium polystyrene sulfonate brushes(LiPSS)is anchored to silicon dioxide nanoparticles with chemical bonding using atom transfer radial polymerization(SI-ATRP).The composite polymer electrolytes are made by mixing vinylene carbonate and nanoparticles via a facile in situ polymerization process.The ionic conductivity of composite polymer electrolytes is improved to 7.2×10^-4 S/cm at room temperature,which is attributed to the low degree of crystallinity of polymer electrolyte and the fast ion transport on the surfaces of polymer brush layers that act as a conductive network.The composite polymer electrolytes show a wide electrochemical window of approximately 4.5 V vs.Li^+/Li and excellent cycling performance retention of approximately 95%after 100 cycles at ambient temperature.The results also prove that surface groups of ceramic na noparticles are an important way to increase the electrochemical properties of composite polymer electrolytes.     

Synthesis and characterization of mixing soft-segmented waterborne polyurethane polymer electrolyte with room temperature ionic liquid

Composite polymer electrolytes based on mixing soft-segment waterborne polyurethane(WPU)and 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide(BMImTFSI)have been prepared and characterized.The addition of BMImTFSI results in an increase of the ionic conductivity.At high BMImTFSI concentration(BMImTFSI/WPU=3 in weight ratio),the ionic conductivity reaches 4.27×10~(-3)S/cm at 30℃.These composite polymer electrolytes exhibit good thermal and electrochemical stability,which are high enough to be...     

Synthesis and characterization of a new hybrid TiO<Subscript>2</Subscript>/SiO<Subscript>2</Subscript> filler for lithium conducting gel electrolytes

This paper describes the synthesis and properties of a new type of ceramic fillers for composite polymer gel electrolytes. Hybrid TiO₂-SiO₂ ceramic powders have been obtained by co-precipitation from titanium(IV) sulfate solution using sodium silicate as the precipitating agent. The resulting submicron-size powders have been applied as fillers for composite polymer gel electrolytes for Li-ion batteries based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF/HFP) copolymeric membranes. The powders, dry membranes and gel electrolytes have been examined structurally and electrochemically, showing favorable properties in terms of electrolyte uptake and electrochemical characteristics in Li-ion cells.     

PEO/LiClO_4纳米SiO_2复合聚合物电解质的电化学研究

将实验室制备的纳米二氧化硅和市售纳米二氧化硅粉末与PEO LiClO4复合 ,制得了复合PEO电解质 .它们的室温离子电导率可比未复合的PEO电解质提高 1～ 2个数量级 ,最高可以达到 1 2 4× 10 - 5S cm .离子电导率的提高有两方面的原因 :一是无机二氧化硅粉末的加入抑制了PEO的结晶 ,是二氧化硅粉末和聚合物电解质之间形成的界面对电导率的提高也有一定的作用 .在进一步加入PC EC(碳酸丙烯酯 碳酸乙烯酯 )混合增塑剂后制得的复合凝胶PEO电解质 ,可使室温离子电导率再提高 2个数量 ,达到 2× 10 - 3 S cm .用这种复合凝胶PEO电解质组装了Li|compositegelelectrolyte|Li半电池 ,并测量了该半电池的交流阻抗谱图随组装后保持时间的变化 ,实验观察到在保持时间为 144h以内钝化膜的交流阻抗迅速增大 ,但在随后的时间内逐渐趋于平稳 ,表明二氧化硅粉末的加入可以有效地抑制钝化膜的生长     

The network gel polymer electrolyte based on poly(acrylate-co-imide) and its transport properties in lithium ion batteries

Poly (acrylate-co-imide)-based gel polymer electrolytes are synthesized by in situ free radical polymerization. Infrared spectroscopy confirms the complete polymerization of gel polymer electrolytes. The ionic conductivity of gel polymer electrolytes are measured as a function of different repeating EO units of polyacrylates. An optimal ionic conductivity of the poly (PEGMEMA₁₁₀₀-BMI) gel polymer electrolyte is determined to be 4.8 × 10^–3 S/cm at 25 °C. The lithium transference number is found to be 0.29. The cyclic voltammogram shows that the wide electrochemical stability window of the gel polymer electrolyte varies from −0.5 to 4.20 V (vs. Li/Li⁺). Furthermore, we found the transport properties of novel gel polymer electrolytes are dependent on the EO design and are also related to the rate capability and the cycling ability of lithium polymer batteries. The relationship between polymer electrolyte design, lithium transport properties and battery performance are investigated in this research.     

复合型聚合物电解质的研究进展

综述了通过物理改性的方法制成的复合型聚合物电解质（ＣＰＥ）的研究进展,并介绍了ＣＰＥ薄膜的制备工艺,以及ＣＰＥ应用在聚合物二次锂电池中的最新成果。     

单分散SiO2纳米颗粒复合凝胶电解质的应用

以单分散程度较高的SiO₂纳米颗粒(约130 nm)作为填料,聚偏氟乙烯-六氟丙烯(PVDF-HFP)作为聚合物基质,采用简便的物理共混法制备出了一种单分散SiO₂纳米颗粒复合凝胶聚合物电解质(MCGPEs)并将其应用于锂电池中。扫描电镜结果表明,SiO₂纳米颗粒在聚合物基体中分散均匀。与传统凝胶聚合物电解质(GPEs)和商业SiO₂颗粒复合凝胶电解质(CGPEs)相比,MCGPEs有着更高的电解液吸液能力和离子电导率,并且具备更强的锂离子迁移能力。此外,使用MCGPEs作为电解质的锂电池,在1.0C下历经300次循环后仍然保持了121.1 mAh·g^-1的较高比容量,表现出了优异的循环性能。同时,其倍率性能也十分优异,在10C倍率下获得了135 mAh·g^-1的比容量,远高于GPEs锂电池(76.2 mAh·g^-1)。     

Properties of composite solid polymer electrolyte using hyperbranched polymer with ether-linkage

The cross-linked composite solid polymer electrolytes composed of poly(ethylene oxide), lithium salt (LiN(SO₂CF₃)₂), and a hyperbranched polymer whose repeating units were connected by ether-linkage (hyperbranched polymer (HBP)-2) were prepared, and their ionic conductivity, thermal properties, electrochemical stability, mechanical property, and chemical stability were investigated in comparison with the non-cross-linked or cross-linked composite solid polymer electrolytes using hyperbranched polymers whose repeating units were connected by ester-linkage (HBP-1a, 1b). The cross-linked composite solid polymer electrolyte using HBP-2 exhibited higher ionic conductivity than the non-cross-linked and cross-linked composite solid polymer electrolytes using HBP-1a and HBP-1b, respectively. The structure of the hyperbranched polymer did not have a significant effect on the thermal properties and electrochemical stability of the composite solid polymer electrolytes. The tensile strength of the cross-linked composite solid polymer electrolyte using HBP-2 was lower than that of the cross-linked composite solid polymer electrolyte using HBP-1b, but higher than that of the non-cross-linked composite solid polymer electrolyte using HBP-1a. The HBP-2 with ether-linkage showed higher chemical stability against alkaline hydrolysis compared with HBP-1a with ester-linkage.     

Recent progress of composite solid polymer electrolytes for all-solid-state lithium metal batteries

In comparison with lithium-ion batteries (LIBs) with liquid electrolytes, all-solid-state lithium batteries (ASSLBs) have been considered as promising systems for future energy storage due to their safety and high energy density. As the pivotal component used in ASSLBs, composite solid polymer electrolytes (CSPEs), derived from the incorporation of inorganic fillers into solid polymer electrolytes (SPEs), exhibit higher ionic conductivity, better mechanical strength, and superior thermal/electrochemical stability compared to the single-component SPEs, which can significantly promote the electrochemical performance of ASSLBs. Herein, the recent advances of CSPEs applied in ASSLBs are presented. The effects of the category, morphology and concentration of inorganic fillers on the ionic conductivity, mechanical strength, electrochemical window, interfacial stability and possible Li⁺ transfer mechanism of CSPEs will be systematically discussed. Finally, the challenges and perspectives are proposed for the future development of high-performance CSPEs and ASSLBs.     

Conductive networked polymer gel electrolytes composed of poly(meth)acrylate,lithium salt,and ionic liquid

Self‐standing films of (meth)acrylate‐based polymer gel electrolytes with high ionic liquid content (80 wt %) were prepared by in situ thermally or photo induced radical copolymerization of mono‐functional and di‐functional (meth)acrylates in an ionic liquid in the presence/absence of a lithium salt. Their ionic conductivity, thermal property, mechanical property, and flammability were examined. 1‐Ethyl‐3‐methylimidazolium bis(trifluoromethanesulfonyl)imide (EMImTFSI) or 1‐ethyl‐3‐methylimidazolium bis(fluorosulfonyl)imide (EMImFSI) was used as the ionic liquid, and lithium bis(trifluoromethanesulfonyl)imide LiTFSI was used as the lithium salt. The obtained films were semitransparent and flexible with good to moderate thermal stability and mechanical strength with high ionic conductivity. The EMImFSI‐containing gel electrolytes showed higher ionic conductivity than the corresponding EMImTFSI‐containing gel electrolytes. The ionic conductivity in the acrylate‐based gel electrolytes was slightly increased by addition of lithium salt, while that in the corresponding methacrylate‐based electrolytes was decreased significantly. The flame test showed the ionic liquid containing networked polymer gel electrolytes to have low if any flammability and was therefore confirmed to be highly safe. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis and electrochemistry of polymer based electrolytes for lithium batteries

An overview is presented on the development of improved polymer based electrolytes during the past years. The emphasis lies on new approaches regarding chemical concepts that achieve a higher total conductivity and lithium transference number as well as an increased electrochemical, mechanical and thermal stability. With respect to the polymer chemistry, the focus is laid on siloxane and phosphazene derived systems. Topics are the chemical modification of the polymeric, cyclic and low molecular derivates of these systems, the formation of stable membranes from these by suitable cross-linking strategies and an extensive electrochemical characterization in corresponding lithium cells. Recent trends towards composite and hybrid materials are illustrated with examples and newly developed hybrid electrolytes. A particular chance for improvements comes from the design and use of stable small molecular additives in combination with optimized and electrochemically stable polymer networks. Special compounds are introduced which may act themselves as novel solvents with increased electrochemical stabilities. The relevance of chosen lithium salts for polymer electrolytes is discussed, too, and a new family of pyrazolide anions is introduced. In all cases, the electrochemical performance has been characterized by standard experimental techniques.     

Room temperature cross-linkable gel polymer electrolytes for lithium ion batteries by in situ cationic polymerization of divinyl ether

We demonstrated room temperature cross-linkable gel polymer electrolytes (GPE) prepared by in situ cationic polymerization of tri(ethylene glycol) divinyl ether (TEGDVE) with LIBF₄ that yields protonic acid and Lewis acid as an acidic initiating system by the reaction with water as an impurity in the liquid electrolyte. FTIR analysis reveals that TEGDVE in the liquid electrolyte is successfully polymerized into gel polymer electrolyte. The resulting gel polymer electrolyte showed promising electrochemical properties including ionic conductivity, wide range in working potential and stable cycle performance as a lithium ion conducting medium.     

Effect of solvents on properties of polymer gel-electrolyte based on polyester diacrylate

New polymer gel electrolytes based on polyester diacrylates and LiClO₄ salt solutions in organic solvents are developed for lithium ion and lithium polymer batteries with a high ionic conductivity up to 2.7 × 10^?3 Ohm^?1cm^?1 at the room temperature. To choose the optimum liquid electrolyte composition, the dependence is studied of physico-chemical parameters of new gel electrolytes on the composition of the mixture of aprotic organic solvents: ethylene carbonate, propylene carbonate, and λ-butyrolacton. The bulk conductivity of gel electrolytes and exchange currents at the gel electrolyte/Li interface are studied using the electrochemical impedance method in symmetrical cells with two Li electrodes. The glass transition temperature and gel homogeneity are determined using the method of differential scanning calorimetry. It is found that the optimum mixture is that of propylene carbonate and λ-butyrolacton, in which a homogeneous polymer gel is formed in a wide temperature range of ?150 to +50°C.     

聚碳酸酯基固态聚合物电解质的研究进展

液态锂离子电池由于采用易泄露、易挥发、易燃烧的碳酸酯有机溶剂,在高温或极端条件下使用时,存在极大的安全隐患.使用固态电解质替代液态电解液,可以从根本上避免此类安全问题的发生,与此同时还可以大幅度提升固态锂电池的能量密度.固态电解质又分为无机固态电解质和聚合物固态电解质2大类.无机固态电解质能够在宽的温度范围内保持化学稳定性,并且电化学窗口较宽,机械强度更高,室温离子电导率较高,但脆性较大,柔韧性差,制备工艺复杂,成本较高.聚合物固态电解质,室温离子电导率偏低,难以满足室温锂离子电池的应用,但其加工成型容易,形状可变.比较而言,固态聚合物电解质,更适宜大规模生产,离产业化相对更近.固态聚合物电解质中研究较多的是聚醚基固态聚合物电解质(如聚环氧乙烷和聚环氧丙烷),但其缺点是室温离子电导率低,需要对其改性或进一步开发综合性能更加优异的其他固态聚合物电解质.聚碳酸酯基固态聚合物电解质由于其特殊的分子结构(含有强极性碳酸酯基团)以及高介电常数,可以有效减弱阴阳离子间的相互作用,提高载流子数量,从而提高离子电导率,因此被认为是一类非常有前途的固态聚合物电解质体系.基于此,本文重点综述了最近研究热点的聚碳酸酯基固态聚合物电解质,包括聚(三亚甲基碳酸酯)体系、聚(碳酸丙烯酯)体系、聚(碳酸乙烯酯)体系和聚(碳酸亚乙烯酯)体系等,并详细阐述了上述每种聚碳酸酯基固态聚合物电解质的制备、电化学性能、优缺点及改性手段,归纳出其离子配位-解配位过程和离子扩散机制,还对聚碳酸酯基固态聚合物电解质的未来发展方向和研究趋势望进行了预测和展望.     

高陶瓷含量复合固态电解质

全固态锂二次电池兼具高能量密度和高安全性特点.高陶瓷含量的陶瓷-聚合物复合固态电解质综合了聚合物电解质的柔韧性和陶瓷电解质的高机械强度与高锂离子迁移数等优点,有望优先其他形式固态电解质应用于全固态锂二次电池.本文在简要介绍固态复合电解质后,重点从复合电解质膜的性能特点与制备方法、陶瓷-聚合物界面相互作用以及由此导致的新...     

PEO基纳米复合聚合物电解质电化学性质的研究

以PEO8 LiClO4作母体,纳米SiO2为填料,制成PEO8 LiClO4 SiO2(x%)系列复合聚合物电解质,测定这该电解质的电导率、锂离子迁移数和电化学稳定窗口,并对其晶态结构作差热分析表征.结果表明,纳米SiO2的引入,显著提高了电解质的电导率,在22℃时达到4.3×10-5S·cm-1.此外,还探讨了填料对复合聚合物电解质电导率提高的影响机理.     

A Gel Polymer Electrolyte with 2D Filler-reinforced for Dendrite Suppression Li-Ion Batteries

Gel polymer electrolytes (GPEs) incorporate both the high ionic conductivity of organic liquid electrolyte and the high safety performance of all-solid-state electrolytes (ASSEs), greatly improving the electrochemical performance of solid polymer electrolytes (SPEs). However, the practical application of GPEs is still limited by inferior interface compatibility, lithium dendrites, etc. Herein, we prepared GPEs based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) further co-blended the two-dimensional sheet inorganic filler hectorite and poly(methyl methacrylate) (PMMA) to improve the mechanical and electrochemical properties of the GPEs. When the content of PMMA and hectorite is optimal, this GPEs have an ionic conductivity of 1.06×10⁻³ S cm⁻¹ and outstanding lithium symmetric cells cycle time of more than 3000 h, indicating that the introduction of filler effectively inhibits the growth of lithium dendrites at room temperature. Moreover, the GPEs adopt a relatively simple solution casting method to provide a fresh idea for the synthesis of high-performance GPEs.