【作者】 费新坤；

【导师】 李学良；

【作者基本信息】 合肥工业大学 ， 应用化学， 2005， 硕士

【摘要】 锂离子电池具有电压高、比能量大、循环寿命长、环境污染小等优势,逐步取代了一些传统的化学电源。锰具有资源丰富和环境友好等特点,正极材料LiMn₂O₄研究成为锂离子电池研究的重点。针对LiMn₂O₄材料存在着容量衰减等缺陷,本文选用过渡和稀土金属化合物为添加物,开展LiMn₂O₄材料制备、掺杂和性能研究。 在大量的实验基础上,结合掺杂化合物的性质,选择材料制备的温度和工艺条件;采用高温固相法合成了LiMn₂O₄和掺杂尖晶石材料;采用XRD、SEM、CV和EIS方法对所得材料进行了表征和性能测试。 铬掺杂材料的EIS测试表明,LiMn_2-xCr_xO₄电极体系的总电阻比LiMn₂O₄体系的小;掺Cr使锂离子的嵌-脱会变得更加容易,提高了材料的电化学性能。 钴掺杂材料的CV测试表明,扫描速度对LiMn_2-xCo_xO₄材料的循环伏安曲线有明显影响;对LiMn_2-xCo_xO₄多次重复循环测试表明,掺Co增加了反应的可逆性。 稀土掺杂结果表明,La的掺杂量对材料结构和循环伏安曲线有明显影响;反应温度和Nd的掺杂量对材料结构有影响;不同电势下材料的掺Nd材料的交流阻抗图谱表明,随着电势的升高,体系的电阻减小。 掺杂离子稳定了材料的结构,有利于材料的性能的稳定和提高。结合电极等效电路,文中对电极过程也作了分析和探讨。更多还原

【Abstract】 Lithium-ion battery has gradually replaced the tradition batteries as the power source, duing to the excellent advantages.for example high voltage, high capacity, long using lifetime and no pollution. Being no toxicity and abundance of Mn, the spinel LiMn₂O₄ has been a highlight extensively among electrode materials in the battery. In order to resolve the defect of large capacity fade on cycling, the transition and thulium metal were choosed as additives to synthesize LiMn₂O₄, dope and study the performance in the paper.The synthesis temperature and the technology were got, based on experiment; The spinel lithium manganese oxides LiMn₂O₄ and its dopant materials were prepared by solid-state method. Their structures, performance and the electrode process of the active material were investigated by means of XRD, SEM, CV, EIS and the equivalent circuit,It showed that LiMn_2-xCr_xO₄ system has less resistance than that of the LiMn₂O₄ by EIS, So doped Cr ion help Li⁺ intercalate and unintercalate freely and increased the electrochemical performance of the material.The obvious effects of the scan rate on the CV curves were studied in LiMn_2-xCo_xO₄ system; The CV curves were compared with LiMn₂O₄ after cyclics, which showed that doped Co ion increased reversibility of the reaction.It showed that the La stoichiometric number X has obvious impact on the structure and the CV curves; the structure was attected by the synthesis temperature and Nd stoichiometric number X; By the EIS curves of the different potential, it showed that the resistance decreased with the increase of the potential in the doping thulium elements Nd experiment.It showed that doped ion stabilized the structure and help to increase the performance of the material. By the equivalent circuit, the electrode process was analysed and sthdied.更多还原