【作者】 陈前火；

【导师】 连锦明；

【作者基本信息】 福建师范大学 ， 物理化学， 2003， 硕士

【摘要】 为解决尖晶石锂锰氧化物在进行深度充放电时的Jahn-Teller效应问题，提高电池的比能量和电池寿命以及降低电池成本等问题，本文用液相法合成出一系列用锂、镍、钛掺杂的尖晶石锂锰氧化物。用原子吸收分光度法和能谱确定样品的组成。扫描电子显示镜(SEM)和透射电子显微镜(TEM)分析了样品的表面形貌及粒径特征。X射线粉末衍射仪(XRD)和傅立叶变换红外光谱仪(FT-IR)确定了不同掺杂比样品的结构，X射线光电子能谱(XPS)确定样品的价态。并探讨了其在水电解液和有机电解液中的电化学性能。 SEM和TEM研究表明在尖晶石中同时掺入少量钛和镍后的样品为雪花状的纳米颗粒，具有较大的表面积。样品在有机电解液的初始电容量(155.8mAh/g)大于理论1F电子放电容量(148mAh/g)，通过充放电前后XRD衍射图显示，放电前后晶胞体积变化仅为0.233％，样品循环性能好。在纯尖晶石中掺入的镍量较大时(锂锰的摩尔比为1.4:0.6)，样品的放电区间移到4.5V左右，得到适合做5V锂离子电池的正极材料。 在水溶液中不锈钢网可以作为电极的集流体，在0.5-4.0mV/s的扫描速度范围内，锂离子在尖晶石锂锰氧化物的嵌入和脱嵌的电化学反应在动力学上是受锂离子在固相中的扩散所控制，充放电实验显示样品S13在水电解液中经过40个循环后达到77mAh/g的放电容量，具有很好的循环稳定性。更多还原

【Abstract】 For resolve the Jahn-Teller effect, improve the capacities and cycle performance and decrease the cell price, a series of spinel lithium manganese oxides doped by lithium, nickel and titanium were prepared by liquid method. Energy spectrometer and atomic absorption spectrum (AAS) were used to determine their compositions, and Scanning electron microscope (SEM) , Transmission electron microscopic (TEM) were used to analysis the appearance of the samples. X-ray powder diffractometer (XRD), Forier transform infrared spectroscopy (FT-IR) and crystalline parameters were used to determine the structure of the samples, X-ray photoelectron spectra (XPS) were employed to determine the oxide state of elements in the samples. In the meantime, electrochemical properties of the materials in the organic electrolyte and aqueous electrolyte were researched.SEM and TEM analysis show that the sample co-doped by nickel and titanium has nano-pellets with morpha like snow and great surface, Which theinitial discharge capacities in organic electrolyte reached 155.8mAh/g and whichwere more than theoretic one Farad electron discharge capacities (148mAh/g). Duringthe charging and discharging cycle, the change rate of the crystal volume was only 0.233% and the sample showed long cycle life. When there are more nickel atom doped in spinel (the mole ratio of Mn and Ni was 1.4:0.6), the discharging platform jumped to 4.5V from original 3.8V. The materials showed to suit for positive materials in 5V lithium ion batteries.After finished the cyclic voltammetry experiments, the results showed that iron steel grid can act as good current collector in the aqueous electrolyte. While the scan rate was fall in the range of 0.5-4.0mV/s, electrochemical reaction of the lithium insertion/extraction in the solid phase was kinetically limited by the diffusion of lithium ions . After 40 cycles in aqueous electrolyte the discharge capacities of sample of S13 reached 77mAh/g, and showed good cycle performance.更多还原