【作者】 杨鹏；

【导师】 廖小珍；

【作者基本信息】 上海交通大学 ， 化学工程， 2013， 硕士

【摘要】 锂离子电池的构成主要包含正极、负极、隔膜和电解液四个主要部分。锂离子电池的容量主要取决于正、负极活性材料的质量和配比。影响锂离子电池循环寿命的因素很多，如正、负极活性材料与电解液的匹配性，活性材料的制备工艺和组成，正、负电极的结构特性，电解液的纯度和组成，隔膜的热稳定性和化学稳定性等等。为了研究锂离子电池寿命衰减的机理，提高锂离子电池的使用寿命，本文以方型铝壳锂离子电池作为研究对象，采用恒流-恒压充放电、交流阻抗图谱等电化学测试技术对电池的循环性能、倍率特性、电极阻抗等电化学性能进行了分析，并采用压汞仪测试技术对电极的结构特性进行了表征。研究发现，采用恒流充放电方法，研究了循环过程中，不同倍率下，容量衰减曲线，倍率越大，衰减速率越快；采用压汞仪测试技术研究了循环过程中，极片多孔电极参数的变化趋势，主要为孔隙率、孔面积、最频孔径、曲折度；孔隙率反映锂离子的液相传导；孔面积反映锂离子的电化学反应面积；最频孔径和曲折度反映锂离子的扩散通道；交流阻抗测试结果显示，欧姆阻抗、SEI膜阻抗、电化学反应阻抗、扩散阻抗等随着循环的进行均呈增大趋势。更多还原

【Abstract】 Lithium-ion battery mainly consists of positive electrode, negativeelectrode, separator and electrolyte. The capacity of lithium-ion batterydepends on the positive and negative electrode active material and the ratioof the mass. Lithium-ion battery cycle life affected by many factors, suchas the active material matching with the electrolyte, the active material andpreparation process, the electrode structural properties, the purity andcomposition of the electrolyte, the thermal stability and chemical stabilityof the separator.In order to study the mechanism of capacity fading and improve thecyclic life of lithium-ion batteries, the paper employed prismatic battery todetermine the properties of porous electrode by using mercury instrumentand electrochemical performance through CC-CV charging anddischarging and AC impedance.The results showed that the higher current rate, the faster capacityfading. Via mercury instrument, the porosity, pore area, pore size andtortuosity were detected during the cycles; porosity reflects the masstransference of Li+; pore area reflects electrochemical reaction area; poresize and tortuosity reflect diffusion path. The value of ohmic resistance,SEI resistance, charge transfer resistance and diffusion resistance increasedduring the cycles by AC impedance test.更多还原