【作者】 左相青；

【导师】 李怀祥；

【作者基本信息】 山东师范大学 ， 物理化学， 2007， 硕士

【摘要】 锂离子电池是20世纪90年代发展起来的新型二次电池。尖晶石锰酸锂LiMn₂O₄是一种嵌锂化合物,锂离子因化学或电化学作用可以嵌入或脱出。因其嵌锂电位高、容量大、锰资源丰富、对环境无污染等优点,LiMn₂O₄被认为是最有希望的锂离子电池正极材料。然而,由于锰的溶解及其造成的材料结构变化,钝化膜的形成造成的电极极化增大,Jahn-Teller扭曲效应造成的的材料破坏和电解液分解造成的欧姆极化增大等原因导致LiMn₂O₄存在严重的容量衰减问题。为了解决这一问题,本文采用溶胶-凝胶法合成尖晶石LiMn₂O₄,并且采用溶胶-凝胶法对其进行掺杂,包覆改性研究。主要内容如下:1.掺杂是改进尖晶石LiMn₂O₄材料电化学性质的有效的方法,针对目前大量采用Al、Co、Ni、Zn等对其进行改性的研究,本文用溶胶-凝胶法合成了尖晶石LiMn₂O₄及掺杂Ni、Co、Al、Zn的样品,通过XRD、SEM、IR分析测试,考察了掺杂不同离子对尖晶石LiMn₂O₄材料晶粒生长的影响,并且计算了掺杂不同离子所得到的样品的活化能。2.包覆是改进尖晶石LiMn₂O₄材料电化学性质的途径之一。本文选用导电性较好的Sn和Sb的溶胶及Zn和Al的溶胶,通过溶胶-凝胶法对自制的尖晶石LiMn₂O₄材料表面改性,在其表面均匀包覆了一层SnO2: Sb及ZnO: Al复合氧化物,抑制了电极材料和电解液的直接接触,提高了其充放电容量。更多还原

【Abstract】 Lithium-ion battery is a new type of secondary batteries developed during 1990’s. Spinel manganese oxide （LiMn₂O₄） has caused much attention for the application in electric vehicles, since its low cost and smaller impact on environment. However, its capacity fades slowly, and this prevents its wide commercial use. This fading is mainly due to the following three factors: dissolution of Mn3+,Jahn-Teller effect and dedcomposition of the organic solvents. To improve the electrochemical performance of LiMn₂O₄, a sol-gel method, adulteration （doping） and surface modification were used in this thesis. The main work of the research was as follows:1. The active cathode materials, Li1+yMxMn2-yO4 （M = Al、Co、Ni、Zn） powders were synthesized by sol-gel method. The influence of different doping elements on the structural properties of the as-prepared samples was investigated by XRD, IR and SEM.2. Using the conductive sol SnO2: Sb, ZnO: Al as the raw materials, SnO2: Sb or ZnO: Al was homogeneously coated on LiMn₂O₄ by sol-gel method. In this way, the oxide effectively prohibited the direct contact LiMn₂O₄ with the electrolyte. The results showed the coated LiMn₂O₄ could give good electrochemical performances.更多还原