The Research of Organic Electrolyte Solutions for Li-Ion Batteries

本文分析了影响有机电解液电导率的主要因素 ;总结了有机电解液的一般特点 ,从有机溶剂和电解质锂盐两个方面介绍了有机电解液的化学和电化学 ;概述了各常用有机溶剂的性质和近年来的研究状况 ;综述了有机电解液在电解质锂盐、有机溶剂和添加剂三个方面的研究进展 .文章最后对有机电解液研究的现状作了简要的评论The characteristics of organic electrolyte solutions and its influences on the ion conductivity are summarized. The chemistry and electrochemistry of organic electrolyte solutions and characteristics of ordinary organic solvents are introduced. Progresses in studies of organic electrolyte solutions such as electrolyte salts, organic solvents, additives in recent years are reviewed, current situation of the studies of organic electrolyte solutions were also discussed.作者联系地址：西北核技术研究所,西北核技术研究所,西北核技术研究所,西北核技术研究所 陕西西安710024 ,陕西西安710024 ,陕西西安710024 ,陕西西安710024Author's Address: Northwest Institute of Nuclear Technology, Xi′an 710024,Chin

An Electrochemical Impedance Spectroscopic Study of CuF2/MoO3/C Cathode Composites

采用球磨方法制备了CuF2/MoO3/C复合材料电极，利用X射线衍射（XRD）、扫描电镜（SEM）、透射电镜（TEM）、恒流充放电、循环伏安（CV）和电化学阻抗谱（EIS）等方法表征与观察复合材料的结构与形貌，测试了电极的电化学性能. 结果表明，球磨CuF2和MoO3晶粒的尺寸为200 ～ 300 nm. CuF2/MoO3/C复合电极10 mA?g-1电流密度首次放电容量为647 mAh.g-1，但随之复合材料循环寿命迅速衰减.循环伏安曲线首次放电，2.2 V左右出现了一个还原峰，第2、3周期该还原峰电位升至3.2 V左右. CuF2/MoO3/C复合电极的Nyquist图由高、中频区两个半圆串接和一条斜线组成. 放电过程，高频区半圆相应于锂离子扩散多层SEI膜，还与电极材料与集流体的接触有关. 中频区半圆与CuF2和MoO3及C的肖特基接触有关. 低频区斜线反映扩散传递过程. CuF2/MoO3/C电极电荷传递阻力较大，这可能也是CuF2/MoO3/C电极容量较快衰减的原因.Composite electrode of CuF2/MoO3/C was fabricated through high energy mechanical milling. The properties of CuF2/MoO3/C were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (TEM), galvanostatic charge-discharge measurements, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results showed that the grain sizes of CuF2 and MoO3 after milling were 200 ~ 300 nm, and the initial discharge capacity of CuF2/MoO3/C was 647 mAh?g-1 at room temperature and at a current density of 10 mA.g-1. However, the capacity decayed rapidly in the next cycles. CV curves showed one reduction peak at 2.2 V in the first cycle and another one at 3.2 V in the following cycles. The Nyquist diagram of CuF2/MoO3/C electrode consisted of two semicircles and one line. During the discharge process, the high frequency semicircle (HFS) may be associated with not only the Li+ migration through the SEI film, but also contact resistance between the CuF2/MoO3/C composites and the current collector. The middle frequency semicircle (MFS) should be related to the Schottky contact between CuF2 and conductive agents, which may be the important feature of such composites materials with big band gap. Besides the low frequency line may be related to the diffusion step. A very large value of charge transfer resistance for the CuF2/MoO3/C electrode may induce the rapid decay in capacity.2012年中国矿业大学高水平论文专项基金（No. 2012LWB13）资助作者联系地址：中国矿业大学材料科学与工程学院锂离子电池实验室，江苏 徐州 221116Author's Address: School of Materials Science and Engineering, China University of Mining & Technology, Xuzhou 221166, Jiangsu, China通讯作者E-mail：[email protected]