【作者】 李凡群；

【导师】 赖延清； 张治安；

【作者基本信息】 中南大学 ， 有色金属冶金， 2009， 硕士

【摘要】 超级电容电池是一种兼具锂离子二次电池高能量密度和超级电容器高功率密度优点的新型储能器件,在交通运输、移动通讯、信息技术等方面具有极其重要的应用前景,其技术的成功突破将掀起储能器件领域的一场新的革命。电解液作为其核心组成之一,对超级电容电池的容量、内阻、寿命、温度特性、电极—电解液的界面性能等有着重要影响。本论文探索研究了新型导电锂盐LiODFB基电解液体系与LiFePO₄-AC/AG-AC型超级电容电池电极材料的相容性。论文以LiBF₄和H₂C₂O₄为前驱体,SiCl₄为助剂,采用一步合成法结合溶析结晶提纯工艺制备了结晶态锂盐LiODFB。经测算,其产率为80%,杂质含量为0.0371wt%,水含量为1.01ppm,满足电池级导电锂盐对杂质及水分含量的要求,结合FTIR谱图与核磁共振的结果表明合成了品质优良的LiODFB样品。采用热重-差热分析其热稳定性,发现其热分解温度达278.9℃,优于商业化应用最为广泛的LiPF₆。针对LiFePO₄-AC/AG-AC超级电容电池的电极材料,对LiODFB盐进行溶剂优化研究。选择5种物化性能优良的溶剂配置成九种电解液,采用电导率测试确定LiODFB最佳浓度为1.0M;通过恒流充放电、循环伏安、交流阻抗等电化学测试,研究了不同溶剂体系电解液与LiFePO₄、AG和AC材料的相容性,结果表明EC-PC-DMC溶剂体系与上述电极材料都有着较好的相容性,为九种复合溶剂中综合性能最为优良的溶剂体系。确定溶剂体系后,将LiODFB与LiX复合进行电解质盐的优化研究。将不同比例的LiODFB与LiX配置成四组不同电解液,研究了其与LiFePO₄、AG和AC材料的相容性。实验表明LiODFB中加入一定浓度的LiX不仅提高了LiFePO₄和AG材料的电池特性,同时也提高了AC材料的电容特性。当LiODFB和LiX的浓度分别为0.8M和0.2M时,电解液与LiFePO₄-AC/AG-AC电池电极材料有着较为优良的相容性。采用相同溶剂体系,将LiODFB与性能优良的双电层电容器用电解质盐铵盐进行复合盐的优化探索研究。综合不同电极材料的电化学性能,发现在LiODFB中加入不同浓度的铵盐后,AC材料的电容特性虽然显著提高,但是加入铵盐却对AG电极材料的成膜影响较大,不利于LiFePO₄/AG电池的电池特性发挥。通过上述研究,获得了一种既适合锂离子电池又适合双电层电容器的“双功能”电解液;同时,也初步为LiFePO₄-AC/AG-AC超级电容电池提供了一种与其电极材料相容性相对优良的电解液;其配方为LiODFB-LiX/EC-PC-DMC,其中锂离子浓度为1mol/L。更多还原

【Abstract】 Super-capacitor battery is a new kind of energy storage device possessing high energy density of lithium ion battery as well as high power density of super-capacitor.It has great application aspects in fields of transportation,mobile communication and information technology,etc. The success of its technological breakthroughs will raise a new revolution in the field of energy storage devices.As one of the core material of super-capacitor battery,electrolyte has an extremely impact on capacity, resistance,and temperature properties,etc.In this paper,the compatibility between LiODFB-based electrolytes with the electrode materials of LiFePO₄-AC/AG-AC battery was studied.LiBF₄ and H₂C₂O₄ was dissolved in solvent as the precursor,SiCl₄ was added to the solution as the catalyzer,combined with solventing-out crystallization,LiODFB was synthesized in one step.The test results of the product rate,the qualities of impurity and the water content were 80%, 0.0371%,and 1.01 PPm,respectively.These targets satisfied the request of lithium ion batteries.The result of FTIR and NMP show that the synthetic product LiODFB shows high qualities.The TG-DTA curves show the onset of the endothermic dissociation of LiODFB is at about 278.9℃.That is to say LiODFB has high temperature stability than the most widely used LiPF₆ obviously.Study on the solvent optimize of LiODFB salt for LiFePO₄-AC/AG-AC battery electrode materials.Five kinds of solvent system with excellent physical and chemical properties were employed and mixed into nine different electrolyte systems.The optimal concentration of LiODFB salt was determined by conductivity tests.The compatibility between different solvent electrolyte systems and LiFePO₄, AG,AC electrodes was studied through constant current charge-discharge, CV,EIS,etc.The result shows that the EC-PC-DMC system takes fine compatibility with LiFePO₄-AC/AG-AC electrodes.This system is proved to be the best solvent. After the solvent system was determined as EC-PC-DMC,the optimization of LiODFB-LiX blend salt electrolyte was studied in this system.Four different electrolytes were prepared with changing the proportion of LiODFB and LiX.The compatibility with LiFePO₄-AC/AG-AC electrodes was studied using the same methods as solvent optimize.The characteristics of LiFePO₄/AG battery as well as AC/AC super-capacitor performances were improved by adding some LiX to LiODFB based electrolytes.When the concentrations of LiODFB and LiX were respectively 0.8 M and 0.2 M,electrolyte plays the optimal compatibility with LiFePO₄-AC/AG-AC super-capacitor battery.In the same solvent system,ammonium salt which is the excellent electrolyte salt of super capacitor was added into LiODFB based electrolytes to optimize blend salt electrolytes.The electrochemical performances of different electrode-materials were considered generally, and the results indicate that capacitance characteristics were improved significantly by adding ammonium salt to 1.0 M LiODFB based electrolyte.However,high concentrations of ammonium salt A affect the properties of SEI film in AG electrode,that go against to improve the charge-discharge performances of LiFePO₄/AG cell.To sum up,we point out that the most applicable electrolyte to LiFePO₄-AC/AG-AC super-lithium capacitor is LiODFB-LiX/ EC-PC-DMC,and the concentration of lithium salt is 1 mol/L.更多还原