关键词： 聚合物电解质   气相二氧化硅   纤维聚合物电解质   静电纺丝   交联反应  

摘要： 目前,锂电池己经在人们的日常生活中得到了广泛地应用。但所采用的可燃性有机电解液导致了锂电池在反复使用和储存过程中存在安全问题,所以不含有机溶剂的固态聚合物电解质被研究人员所提出,高安全性全固态锂电池也是未来重要发展方向。聚氧化乙烯（PEO）是目前研究最为广泛的固态聚合物电解质的基体材料,然而,PEO基聚合物电解质的在室温下低的电化学性能,导致其难以发展。本文旨于开发高电化性能的全固态锂电池。引入一种表面富含基团的无机纳米颗粒作为固态聚合物电解质的无机填料,系统研究了其含量对固态聚合物电解质的物化性能和电化学性能的影响规律,并测试分析了全固态锂电池的循环和倍率性能;开发了一种具备双重网络结构的纤维聚合物电解质,以提高聚合物电解质的拉伸强度、电化学性能和界面相容性,以及纤维聚合物电解质全固态锂电池的循环和倍率特性。本文主要研究内容分为以下两部分:（1）PEO-Li Cl O4-Fumed Si O2聚合物电解质的制备及性能研究将表面富含Si-OH基团的气相二氧化硅（fumed Si O2,FS）纳米颗粒作为PEO基聚合物电解质的无机纳米填料,采用超声波细胞粉碎技术将不同质量的气相二氧化硅颗粒均匀分散,并利用溶液延流法成功制备了PEO-Li Cl O4-Fumed Si O2聚合物电解质。通过场发射扫描电子显微镜（FE-SEM）和差示扫描量热法（DSC）表征方法证明,加入少量或过量的气相二氧化硅都不能起到扰乱了PEO中聚合物分子链段的有序性的作用。当气相二氧化硅的添加量为6.85 wt.%时,PEO-Li Cl O4-Fumed Si O2聚合物电解质的结晶度达到了最低（25.83%）。通过傅里叶变换红外光谱（FTIR）测试证明,气相二氧化硅表面的Si-OH基团促进了锂盐的解离,且气相二氧化硅的添加量低于（包括）6.85 wt%时锂盐的解离度与气相二氧化硅的添加量呈正相关关系。拉伸测试表明,PEO-Li Cl O4-Fumed Si O2（6.85 wt.%）聚合物电解质的拉伸强度为1.9 MPa,断后伸长率为639%,拉伸强度比PEO-Li Cl O4聚合物电解质提高了211%。PEO-Li Cl O4-Fumed Si O2聚合物电解质的离子电导率、锂离子转移活化和锂离子迁移数为2.95×10-4 S×cm-1、98.22 k J·mol-1和0.40。PEO-Li Cl O4-Fumed Si O2聚合物电解质优异的拉伸强度对于抑制锂金属表面锂枝晶生长起到至关重要的作用,其Li/Li对称电池的电压可以稳定至380 h,展示了优异的界面稳定性。（2）PEO-PETA-Li Cl O4纤维聚合物电解质的制备及性能研究采用静电纺丝的方法成功制备了具有3-D网络结构的PEO-Li Cl O4纤维聚合物电解质,并与无结构PEO-Li Cl O4聚合物电解质进行性能对比。在此基础上引入PETA,使之与PEO交联形成网状分子链,制备具有双重网络结构的PEO-PETA-Li Cl O4纤维聚合物电解质。与采用溶液延流法制备的无结构PEO-Li Cl O4聚合物电解质相比,具备3-D网络结构的PEO-Li Cl O4纤维聚合物电解质结晶度从30.03%降为28.21%,拉伸强度（3.7MPa）提高了约4.1倍。结晶度的降低使得PEO-Li Cl O4纤维聚合物电解质的锂离子迁移能力得到了提高。纤维聚合物电解质Li/Li对称电池电压可以稳定至388 h,而无结构PEO-Li Cl O4聚合物电解质的对称电池的电压仅能稳定到226 h,说明纤维聚合物电解质的网络结构具备可以抑制锂金属表面锂枝晶的生长。通过FTIR测试验证了PEO-PETA-Li Cl O4纤维聚合物电解质中的PEO与PETA交联反应地成功。交联后,PEO线型分子链转变为网状分子链,使电解质结晶度进一步降低至25.03%,并且双重网络结构将纤维聚合物电解质的拉伸强度提高至4.0 MPa。PEO-PETA网状分子链段的运动能力提高,使得锂离子迁移能力进一步提高。电化学稳定窗口则达到5.7 V（***/Li+）,是由于PEO-PETA-Li Cl O4纤维聚合物电解质与电极之间优异的固/固界面相容性可以防止了电解质的氧化。PEO-PETA-Li Cl O4纤维聚合物电解质Li/Li对称电池的电压测试至735 h没有变化,说明了双重网络结构可以有效地抑制锂金属表面的锂枝晶生长,提高了与电极之间的界面相容性。

关键词： Composite solid electrolytes (CSEs)   L1.5Al0.5Ti1.5(PO4)(3) (LATP)   PEO polymer   All-solid-state lithium rechargeable batteries  

摘要： Traditional liquid batteries have been plagued by safety, and highly stable all-solid-state battery is one of the main methods to solve this problem. Solid electrolytes have been accelerating development as a core component of all-solid-state batteries. A composite solid electrolytes (CSEs) composed of an organic polymer and an inorganic solid ceramic has been widely concerned, which can take into consideration the advantages of both and avoid disadvantages. Here, we report CSEs composed of LATP ceramic particles and PEO polymer matrix. The structure, morphology and electrochemical properties of LATP and CSEs are systematically studied. When the LATP complex is 15%, the ion conductivity reaches 1.00 x 10(-4) ***(-1) at 30 degrees C, the lithium ion transference number is 0.37, and the electrochemical window is as high as 5.2 V. The all-solid-state lithium batteries has a reversible capacity of 136.0 mA h g(-1) after 100 cycles, and has excellent rate performance.

关键词： Composite solid polymer electrolyte   High ionic conductivity   In-situ thermal study   Thermal safety   Solid-state lithium battery  

摘要： The low room-temperature ionic conductivity, narrow voltage window, and poor thermal stability of solid polymer electrolyte hinder the application of high energy density, safer solid-state lithium batteries (SLBs). Hence, we developed a novel composite solid polymer electrolyte (CSPE) with high room-temperature ionic conductivity (2.4 x 10(-4) S cm(-1)), wide voltage window (similar to 4.8 V), and excellent thermal stability (similar to 330 degrees C) by combining Li64La3Zr1.4Ta0.6O12 ceramic filler with poly(vinylidene fluoride) (PVDF) polymer and bis(trifluoromethane)sulfonimide lithium (LiTFSI) salt. Free-standing, scalable, and mechanically robust CSPE separately coupled with LiFePO4 and high-voltage LiNi1/3Co1/3Mn1/3O2 cathodes vs lithium anode demonstrated stable cycling. More importantly, we in-situ measured the thermal stable window (177 degrees C) with a small heat release (189 J g(-1)) during the thermal runaway of the entire CSPE coin cell. In contrast, the liquid electrolyte cell delivered a depressing thermal stable window (157 degrees C) and release a significant amount of heat (812 J g(-1)). The superior thermal safety of CSPE cell can be ascribed to the solid-state property and outstanding thermal stability of the CSPE. Most notably, this work not only proposes a promising CSPE but also highlights a reference for in-situ quantitative study on the thermal safety of entire SLBs.

关键词： Upper-Division Undergraduate   Polymer Chemistry   Hands-On Learning/Manipulatives   Interdisciplinary/Multidisciplinary   Materials Science   Electrochemistry   Laboratory Instruction   Electrolytic/Galvanic Cells/Potentials   Solid State Chemistry   Analytical Chemistry  

摘要： All-solid-state polymer electrolytes (SPEs) have been regarded as an advisible alternative for simultaneously overcoming the safety issues and high energy density demands presented in traditional lithium batteries, and they represent the development orientation of energy storage devices. This course describes the preparation of a cross-linked and helical polyurethane modified poly(ethylene oxide) (PEO@HPU) and its utilization as the SPE in lithium batteries, which can be used to teach upper-division undergraduates the principle of energy storage devices and the role of liquid-free electrolytes. Fourier transform infrared (FTIR) and H-1 nuclear magnetic resonance (NMR) spectroscopies are used to determine the structure of the polymers. The ionic conductivity, lithium ion transference number, and electrochemical window of PEO@HPU are measured through an electrochemical workstation. The lithium batteries assembled by students are evaluated via a battery testing system. The modification by the special helical polymer obviously improves the electrochemical and battery performance of the PEO-based SPE. Upon completion of the experiment, students will understand the structure-activity relationship in materials science and propose new suggestions for designing advanced SPEs. This experiment requires well-prepared laboratory chemicals as well as long-term processes, so it is suitable to be considered as a project. Meanwhile, it can be also used for senior projects and interdisciplinary projects between engineering and science.

关键词： 安全性   固态聚合物锂电池   热失控   电池量热仪  

摘要： 锂离子电池安全性至关重要,本次研究利用BTC-130电池量热仪对扣式固态聚合物锂电池、扣式液态锂金属负极电池和18650型锂离子电池进行热失控行为研究。结果表明:18650型锂离子电池热失控起始温度为150℃且热失控放热剧烈,各副反应随热失控同步发生,自放热反应被掩盖无法在温度-时间(T-t)曲线中单独体现。而扣式电池活性物质少、自放热较少,热失控起始温度滞后,温度-时间(T-t)曲线中可以清晰地展现电池升温过程中各个自放热副反应。固态聚合物电池在150℃时无隔膜熔融导致内短路现象,180℃时无碳酸酯溶剂大量气化致电池壳破裂现象,其热失控触发机制是正极材料高温释氧,再与聚合物和熔融锂发生氧化还原反应,聚合物固态电池的安全性优于相应的液态电解质电池。

关键词： Poly(ε-caprolactone)   Polymer membrane   Solid polymer electrolyte   All-solid-state battery   Poly(ether imide)  

摘要： Solid polymer electrolytes composed of poly(ε-caprolactone) (PCL) and lithium bis(trifluoromethane) sulfonylimide (LiTFSI) salt were prepared for investigating their electrochemical properties. The optimized solid polymer electrolyte showed ionic conductivities of 2.5 × 10⁻⁵ and 1.6 × 10⁻⁴ S cm⁻¹ at room temperature and 55 °C, respectively. Dimensional stability was improved by infiltrating PCL-based solid polymer electrolyte into the porous polymer membranes prepared from poly(ether imide) (PEI), polyacrylonitrile (PAN) and non-woven polypropylene (PP) membranes. Due to the highly porous nature and good compatibility of the PEI membrane toward the PCL-based solid polymer electrolyte, a solid-state Li/LiNi_0.6Co_0.2Mn_0.2O₂ cell assembled with a solid polymer electrolyte employing a PEI membrane exhibited the best cycling performance. Based on our results, this highly porous PEI membrane is proposed as a promising supporting membrane for enhancing the mechanical stability of amorphous solid polymer electrolytes for applications in all-solid-state lithium batteries.

关键词： all-solid-state batteries   solid composite polymer electrolytes   ionic conductivity   poly-caprolaclone diol   trimethyl phosphate  

摘要： Solid polymer electrolytes (SPEs) with the advantages of high safety, low volatility, and the ability to suppress Li dendrites are highly desirable to be used in next generation high-safety and high-energy lithium-ion batteries. The exploration of SPEs with superior comprehensive properties has received extensive attention for high-performance all-solid-state batteries (ASSBs). Herein, a sandwich-like nanofibrous membrane-reinforced poly-caprolaclone diol and trimethyl phosphate (TMP) composite polymer electrolyte (CPE) has been designed by a facile "solvent-free" solution-casting method. Specifically, the flame-retardant TMP is employed as a plasticizer, which can improve the ionic conductivity effectively. The as-prepared solid electrolyte exhibits superior comprehensive performance in terms of high ionic conductivity, wide electrochemical window, good compatibility with lithium metal, and superior thermal stability. Furthermore, the assembled Li//LiFePO4 ASSBs with this solid CPE show outstanding cycling stability and high average discharge capacity at room temperature (30 degrees C). Undoubtedly, our study provides a new facile method and a qualified solid electrolyte material for next generation high-performance ASSBs.

关键词： Lithium thin film batteries   Flexible batteries   Excimer laser annealing   Microbatteries   LiNi0.5Mn1.5O4  

摘要： Recently, all-solid-state lithium batteries have attracted great attention due to their safe operation without risk of explosion under high operating voltage. However, integrating all solid layers on flexible polymer substrate has been hampered by conflicts between the high crystallization temperature and the endurable temperature of the polymer substrate. In this work, we present a simple fabrication method for all-solid-state flexible lithium batteries that are directly integrated on a polymer substrate. Using excimer laser annealing technique, we are able to selectively crystalize the amorphous cathode layer grown on top of the polymer platform without any damage to the substrate. Our flexible battery is bendable up to a curvature radius of 9 mm without mechanical breakdown, and has an initial capacity of 20 mu A h mu m(-1) cm(-2) at a 0.2 C-rate. Our approach using laser annealing provides new opportunities for integrating all-solid-state lithium thin film batteries on a broader range of platforms.

关键词： 全固态聚合物电解质   离子电导率   聚合物锂电池  

摘要： 随着储能电源和电子产品以及电动汽车的迅速发展,开发高能量密度的锂离子电池已经成为现阶段研究的重点方向之一。目前,较广泛使用的液态锂离子电池,由于容易发生有机液态电解质的泄漏、燃烧、爆炸和短路等问题,存在非常大的安全隐患。因此,迫切需要开发能量密度更高,安全性更加好的锂离子电池。与现有的有机液态电解质相比,全固态聚合物电解质(All-solid-state polymer electrolyte,ASPE)具有理论比容量更高、结构可设计性强、易于大规模生产制造、排除了泄漏液体等体系安全性能好的优点,是一类具有广泛应用前景的电解质。ASPEs在锂离子电池中起到了主导作用,研究者们对其进行了大量的科研工作。本文结合并比较了典型的ASPEs(聚醚、聚酯、聚氨酯、聚硅氧烷)的最新科研进展以及本课题组的工作,回顾了这几种固态聚合物的发展,对高性能锂电池全固态电解质的制备设计、新型锂电池、界面调控和制备工艺成型等方面作了阐述,并对其未来的研究做出展望。

关键词： Solid state battery   Polymer electrolyte   Nickel phosphate   High ionic conductivity   Interface stability  

摘要： Solid-state electrolytes with high ionic conductivity, large electrochemical window, and excellent stability with lithium electrode are needed for high-energy solid-state lithium batteries. In this work, a novel polyethylene oxide (PEO)-Lithium bis(trifluoromethylsulphonyl)imide (LiTFSI)-nanocomposite-based polymer electrolyte was prepared by using nickel phosphate (VSB-5) nanorods as the filler. The ionic conductivity of the obtained PEO-LiTFSI-3%VSB-5 solid polymer electrolyte was found to be as high as 4.83 x 10(-5) ***(-1) at 30 degrees C and electrochemically stable up to about 4.13 V versus Li/Li*. The enhanced ionic conductivity was attributed to the reduced crystallinity of the PEO and the interaction between VSB and 5 and PEO-LiTFSI. In addition, the solid polymer electrolyte exhibited improved compatibility to the lithium metal anode with excellent suppression of lithium dendrites. The assembled LiFePO4/Li battery with the PEO-LiTFSI-3%VSB-5 solid polymer electrolyte showed better rate performance and higher cyclic stability than the PEO-LiTFSI electrolyte. It is demonstrated that this new solid polymer hybrid should be a promising electrolyte applied in solid state batteries with lithium metal electrode. (C) 2020 Elsevier Inc. All rights reserved.