Study on The High-Voltage Electrolytes and Interfacial Electrochemistry of Li-ion Battery

开发高电压高比容量正极材料是发展高能量密度锂离子电池的重要途径。然而，材料结构变化、过渡金属离子的溶出以及常规碳酸酯电解液在高电压下的持续氧化，电极/电解液界面的不稳定性等将导致材料循环性能的快速衰退。同时，电解液分解产生大量气体和热量可能引发安全问题亦严重制约着锂离子电池的发展。因此，开发新型高电压电解液以拓宽电解液的电化学稳定窗口及高电压条件下稳定正极/电解液界面的研究迫在眉睫。 本文从发展高电压溶剂和功能型添加剂两种实现电解液高电压化的有效途径出发，以腈类化合物和新型膦腈类化合物为研究对象，进行电解液组成优化，进而调控正极/电解液界面膜结构、组分及其稳定性，旨在提高锂离子电池正极材料的...Exploration of high voltage and high specific capacity cathode materials is a general approach to increase the energy density of lithium-ion batteries. However, the structure change, the transition metal ions dissolution, the oxidation decomposition of electrolyte and instability of the electrode/electrolyte interphase and so on, can lead to a dramatic deterioration of capacity retention. What’s w...学位：理学博士院系专业：化学化工学院_物理化学学号：2052012015350

FEC基电解液对高压正极材料Li2CoPO4F电化学性能的影响

本文研究了以氟代碳酸乙烯酯FEC（fluoroethylene carbonate）为共溶剂的电解液对高压正极材料Li2CoPO4F电化学性能的影响,与碳酸酯基电解液1 mol·L-1LiPF6EC/DMC=1:1（m:m）相比,1 mol·L-1LiPF6FEC/DMC=1:1（m:m）可显著提高Li2CoPO4F的循环稳定性.通过线性扫描伏安法（LSV）、扫描电镜（SEM）、X射线光电子能谱（XPS）、X射线衍射（XRD）结合电化学阻抗（EIS）对FEC改善Li2CoPO4F材料循环稳定性的机理进行了探索,结果表明与传统碳酸酯基电解液相比,FEC基电解液在高压下有着优异的抗氧化性,能够有效抑制电解液的氧化分解.同时,FEC基电解液中形成的表面膜具有更高的稳定性,能够抑制电极/电解液界面副反应的发生,提高循环过程中电极材料结构稳定性,从而有益于提高Li2CoPO4F材料的电化学性能.福建省自然科学基金项目(No.2014J05019);;国家自然科学基金项目(No.21233004,No.21303147);;厦门大学校长基金(No.20720150090)资

Study of Fluoroethylene Carbonate (FEC) and Methylene Methanedisulfonate (MMDS) as Electrolyte Additives

锂离子电池是近年来电化学能源领域的研究热点，锂离子电池电解液提供锂离子穿梭于正负极之间，是锂离子电池获得高电压、高比能量以及高比功率的重要前提条件，也对电池的其他性能（如高低温及其安全性能）等起着关键作用，因此研发功能电解液是开发高性能锂离子电池时需要考虑的重要课题。功能电解液主要包括基础电解液（基础溶剂及其电解质）与添加剂两种组分，添加剂由于其只要在基础电解液中进行少量的添加就能做为功能电解液进而有效改善锂离子电池电化学性能，且不需要改变锂离子电池的结构和工艺的特点，成为功能电解液研究的热点之一。 本论文选择了两种电解液添加剂氟代碳酸乙烯酯（FEC）和甲基二磺酸亚甲酯（MMDS）来分别研究...Lithium ion batteries have been a top topic of green energy recent years. Electrolyte is an essential element to transport lithium ions between anode and cathode so that batteries can get high voltage, high energy density and high power, it also involves in improvements of other performances as high-low temperature and safety. These characteristics make electrolyte a best way to develop lithium io...学位：工程硕士院系专业：化学化工学院_工程硕士(化学工程)学号：X201119200

A Theoretical Study of Reactions between Polysulfides and Organic Carbonates and Raman Spectra in Lithium-Sulfur Battery

锂硫电池具有更高能量密度比，近年来锂硫电池研究备受关注。作为电池主要构成的一部分，电解液会显著影响电池的电化学行为。在锂硫电池工作中，如果可溶的多硫阴离子与电解液发生化学反应，将严重影响电池的循环性能。 有机碳酸酯类材料中的碳酸乙烯酯(EC)和碳酸丙烯酯(PC)常作为电解液用于电池。然而，其作为锂离子电池电解液时具有优良的循环性能，但在作为锂硫电池电解液时却使电池循环性能变差。不同的研究者对此现象的认识存在较大的分歧，其主要的分歧在于多硫阴离子(Sn2-)与碳酸酯类电解液反应时进攻碳酸酯类分子的羰基碳还是烷基碳。随着谱学电化学技术的不断发展，电化学工作者已有望获得界面电化学反应的分子水平信息...The rechargeable lithium-sulfur battery is receiving a great deal of interest at the present time because, theoretically, it can store 3-5 times more energy than current lithium-ion batteries. Conventional Li-S cells consist of a lithium metal anode, an organic electrolyte,and a sulfur composite cathode.The known problems include low volumn ratio, low efficiency of sulfur and low short cycle life....学位：理学硕士院系专业：化学化工学院_物理化学学号：2052012115154

The Application of Sulfone-based Electrolyte and Study of Functional Additive for Lithium-ion Batteries

电解质体系是任何一种电化学储能与转换系统不可或缺的关键组成部分。电解质体系自身的性质以及其与电极材料构成的界面实际上决定着电池的性能。目前锂离子电池体系广泛使用的基于碳酸酯类的电解液仍有许多问题亟待解决，尤其是安全性问题。本文主要开展基于砜类溶剂的电解质溶液研究，以期改善电解液的热稳定性、高电压电化学性能等；同时，研究了一种新型功能添加剂用于碳酸酯电解液来提高电池的安全性问题。取得的主要结果如下： 1.系统考察了砜类-线性碳酸酯类溶剂混合电解液（SDE和EDE）及其与正负极材料的热稳定性，与碳酸酯类电解液（ET）比较，发现SDE和EDE电解液在300oC之内没有明显放热反应，表现出与离子液体...Electrolyte is an indispensable part of any energy storage and transformation device. For lithium ion batteries (LIBs), the nature of electrolyte and interface of electrode-electrolyte affect the electrochemical property and electrochemical window as well as the safety of a battery to a great extent. The electrolytes based on carbonate ester solvents are widely used in the commercial LIBs, however...学位：理学博士院系专业：化学化工学院_物理化学学号：2052010015368

Research Progress and Perspectives on High Voltage, Flame Retardant Electrolytes for Lithium-Ion Batteries

© 2017 Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences. The electrolyte is an indispensable constituent in lithium ion batteries, and its role conducts electricity by means of the transportation of charge carries between the pair of electrodes. Its properties directly affect the energy density, cycle life and safety of the battery. However, there are two major challenges to using carbonate-based electrolytes in recent lithium ion batteries (LIBs) to further increase the energy density of the devices without compromising the safety. One is that carbonate- based electrolytes are not sufficiently stable at the positive electrode, and the other is their relatively high flammability. Therefore, developing high voltage and flame retardant electrolytes for LIBs is highly desired. Herein, we review the recent progress and challenges in new electrolytes, focusing on high-voltage electrolytes, flame retardant electrolytes and highly concentrated electrolytes. Among the reported electrolytes, highly concentrated electrolytes are worth a special attention, showing various unusual functionalities, for example, high oxidative stability, low volatility, high reductive stability, and non-corrosive to Al. These special properties are totally different from that of the conventional 1 mol•L-1 LiPF6/EC-based electrolytes, which are result from solution structures. A discussion is also provided in this review on the prospects of further development of new electrolytes for LIBs

锂离子电池低温性能改善研究进展

锂离子电池因其能量密度高,循环寿命长等优点已成为新型动力电池领域的研究热点,但其温度特性尤其是低温性能较差制约着锂离子电池的进一步使用.本文综述了锂离子电池低温性能的研究进展,系统地分析了锂离子电池低温性能的主要限制因素.从正极、电解液、负极三个方面讨论了近年来研究者们提高电池低温性能的改性方法.并对提高锂离子电池低温性能的发展方向进行了展望.国家重点研发计划(No.2018YFB010400);;福建省高校产学合作项目(No.2018H6020)资

Study on Electrochemical Performance of Copper Sulfides used as Anode Material in the Conventional Nonaqueous Electrolytes

目前商用的石墨负极材料本身振实密度较低，过充状态下容易产生锂枝晶，会刺破隔膜造成短路，导致电池安全性问题；并且在电化学过程中常常伴随较大的体积变化和结构塌陷，导致该材料的循环性能变差。故而开发新型负极材料一直成为锂离子电极材料研究的热点。 硫化亚铜材料以其优异循环性能，倍率性能，高的电子导电性（104S·cm-1），有且仅有一个平坦的放电平台，成为具有发展潜力的新型锂离子电池负极材料。文献报道纳米棒状的硫化亚铜材料在醚类电解液中，可在3200mA·g-1的大电流充放电下获得260mAh·g-1的可逆容量，其高倍率充放电性能，为材料在动力电池上的应用提供了可能。本论文主要研究商用微米级无特定形...Presently, the graphite is widely used as the commercial anode materials because of its good cycling performance, low voltage plateau and mature processing technic. However, the practical application of graphite is seriously hindered by the low tap density, the huge volume changes and the lithium dendrites which grow quickly during the overcharge process. Therefore, searching for new anode materia...学位：理学硕士院系专业：化学化工学院_物理化学学号：2052012115155

Nitrile-Modified 2,5-Di-tert-butyl-hydroquinones as Redox Shuttle Overcharge Additives for Lithium-Ion Batteries

Nitrile-modifled 2,5-di-tert-butyl-hydroquinones were synthesized and investigated as redox shuttle overcharge additives for LiFePO4/Li cells. The cyanoethylation reaction was utilized to synthesize the target molecules 2,5-di-tert-butyl-l,4-di（β-cyanoet

Study the Influence of Fluorinated Solvents on the Electrochemical Performance of High Voltage Cobalt-based Cathode

随着电动汽车市场的不断发展，对锂离子电池能量密度的要求提出了更大的挑战，因此发展和研究高比能量电池是市场的需求也是研究人员不断追求的目标。通常提高锂离子能量密度有两个方面，提高电池的放电比容量或者提高放电电压平台。以锂-硫和锂-空为代表的电池体系虽然有很高的比容量，但仍是处于实验室的研发阶段。近来，锂离子正极材料如Li2CoPO4F和LiCoPO4因其有较高的工作电压平台而受到广泛关注，但令人遗憾的是，目前常用的碳酸酯类电解液体系并没有与之相匹配的电化学稳定窗口。因此，对于新型高压电解液的研究就显得非常必要和紧迫。本文选择锂离子新型高电压氟代溶剂氟化碳酸乙烯酯(FEC)和1，1，2，2-四氟乙...With the increase demand of high energy density in electric vehicles (EVs) and hybrid electric vehicles (HEVs) market, huge challenge falls on lithium-ion batteries. So the development and research of high energy density battery is the market demand and also the goal that researchers continue to pursue. Usually the energy density of Li-ion batteries can be improved from two aspects, to improve the...学位：工学硕士院系专业：能源学院_能源化工学号：3242014115223