【作者】 李雅琳；

【导师】 李奇；

【作者基本信息】 湖南大学 ， 材料科学与工程， 2007， 硕士

【摘要】 本论文主要研究了SnO₂纳米颗粒状负极材料,利用X射线衍射法,扫描电镜,透射电镜,循环伏安法,交流阻抗及恒电流充放电测试等,研究了材料的结构和电化学性能。并使用了中间相碳微球（CMS）负极材料对扣式电池的工艺方面的影响因素做了探讨。电镜图样表明SnO₂纳米颗粒粒径大约30nm,分散均匀。以SnO₂纳米颗粒为活性物质,采用溶液浇注法制备锂离子电池负极。通过组装模拟半电池（锂片|隔膜（有机电解液）| SnO₂）,研究了不同粘结剂和导电剂的质量分数对负极首次充、放电容量、首次库仑效率、首次充放电后电池的界面阻抗等对电性能的影响及规律,并对电性能的差异进行分析讨论。研究表明,在SnO₂电极中加入乙炔黑能够减小电极的内阻,增强其导电性,提高了半电池的首次可逆容量。将水性粘合剂（乳胶）应用于SnO₂负极,半电池的性能优良,其能够替代PVDF在负极中使用,且当它的质量含量为5%时,SnO₂负极的综合性能最佳。优化配方后,对Li/SnO₂半电池的充放电电压范围、循环伏安、不同电流密度、首次充放电容量及效率、20次循环后的容量保持率、不同荷电状态下的交流阻抗图谱、高低温性能进行了测试,此种SnO₂纳米颗粒尺寸较小,具有较高的首次充电比容量,为909mAh/g,首次充放电效率为65.4%。循环伏安测试表明,此种材料的嵌脱锂电位分别为0.35V和0.5V。比较不同的充放电电压范围,在0.01～1.0V的范围内,20次循环后电池的容量保持率为83.3%。随着充放电电流的增大,充放电容量值减小。当充放电电压范围为0.01～1.0V,充放电电流为0.5C时,纳米SnO₂电极的循环性能最好。交流阻抗图谱分析了在不同荷电状态下对应不同的电化学过程。与CMS负极材料相比,SnO₂纳米颗粒有3倍于CMS的首次充电容量,但是其循环性能较差,衰减比较厉害,这是氧化锡基材料在应用中面临的主要问题。更多还原

【Abstract】 The structure and electrochemical performances of Nano Tin oxide fine particles used as the anode materials of lithium-ion batteries were studied in this paper by X-ray Diffraction （XRD） , Scanning Electron Microscope（SEM） , Transmission Electron Microscope（TEM）, Cyclic Voltammetry（CV）, Electrochemical Impedance Spectra（EIS） and Constant Current（CC）. The influential factors of the fabrication technique of coin cells were also investigated using CMS as the anode materials.The SEM and TEM shows the dimension of granule was 30nm and uniformly dispersed.Using SnO₂ nano particals as active material, prepared the anode of lithium-ion batteries by casting. The impact of different kinds of binders and conductive additives were investigated by testing the performances of half-cells （Li metal | membrane （organic electrolyte） | SnO₂ anode）. The first discharge-charge capacity,coulomb efficiency in the first cycle and interface impedance in different conditions were compared at different mass ratio, and the electric properties were also discussed.The results showed that adding acetylene black can reduce the inner resistance, ameliorate the conductivity, improve the reversible capacity in the first cycle of the half-cells.Applying aqueous binder in SnO₂ anode can get a good performance in half-cells, when the content reaches 5%, best integrate properties can be got, and Aqueous binder （latex） could be a good substitution of PVDF.Testing under different currents, After optimizing the formulation, testing the integrative electrochemical properties.The the SnO₂ nano particals with minor granule dimension and high specific surface area had high specific capacity of 909 mAh/g which was twice higher than CMS and high coulomb efficiency of 65.4% in the first cycle, The CV testing showed, the insert and disengage potential of SnO₂ is 0.35V and 0.5V, respectively.When the charge-discharge voltage range is 0.01～1.0V, the cells’capacity holding ability can keep 83.3% after 20 cycles. As the increasing of charge-discharge current, the charge-discharge capacity decrease.The SnO₂ nano particals had the best cycling performance at 0.01～1.0V voltage range and 0.5C rate charge-discharge current.The electron processes under different charge conditions were analysised by EIS.But the SnO₂ nano particals had poor performance in cycling,which affected the application in lithium-ion batteries.更多还原