【作者】 耿良梅；

【导师】 朱先军；

【作者基本信息】 华中师范大学 ， 物理化学， 2008， 硕士

【摘要】 锂离子二次电池是应用和开发前景较好的一种电源，改善和提高锂离子电池的电化学性能关键是选取充放电性能良好的负极材料。现在国内外商业化锂离子电池中的碳类负极材料已无法满足人们对高容量的需求，于是大量的研究工作主要集中在寻找更高容量的新型负极材料上。本论文在详细评述锂离子电池负极材料研究进展的基础上，以Zn₂SnO₄和Mg-Sn复合氧化物负极材料为研究对象，运用差热及热重分析（TG／DTA）、X-射线电子衍射（XRD）、扫描电子显微镜（SEM）等测试手段对材料进行了表征。最终将其应用于锂离子电池负极材料上，研究了它们的电化学性能特点。主要工作如下：1．采用水热法合成了反尖晶石型的Zn₂SnO₄晶体，研究了碱的浓度和水热反应温度对样品纯度和结晶度的影响，并重点分析了在不同碱的浓度下所得样品电化学性能的差异以及在最优的条件下合成的Zn₂SnO₄样品的充放电机理。结果表明：水热反应温度为220℃、反应时间为24h、碱的浓度为0．2M时所得Zn₂SnO₄样品的电化学性能最好。2．采用共沉淀法合成了球形Zn₂SnO₄颗粒，并研究了煅烧温度对合成样品的纯度、颗粒大小以及电化学性能的影响。得到结论：煅烧温度为750℃合成的Zn₂SnO₄颗粒，首次放电容量为1811．7mAh／g，充电容量为1031．0mAh／g，循环20周后放电容量仍为593．3mAh／g，表现出相对较好的电化学性能。3．采用水热法和共沉淀法合成Mg-Sn复合氧化物的前驱体，并将其分别在不同温度下煅烧4h，得到一系列Mg-Sn复合氧化物。通过TG-DTA、XRD、SEM表征得出：前驱体的不同合成条件对产物的组成、形貌有明显的影响。水热合成的前驱体具有立方结构，且煅烧后的产品还保持了这种形状；而共沉淀法所得的产品形状不规则。两种条件下所得产品的电化学性能差异也较大，水热条件下样品的充放电性能比共沉淀条件下的要好。更多还原

【Abstract】 Rechargeable lithium-ion battery has the better applying prospect in the battery market. The property of battery is greatly depended on choosing the optimal anode materials. Now the commercial carbon anode material can’t meet the needs of the consumers for large capacity, so a lot of researches have focused on finding new large capacity anode material candidates.On the basis of systematically reviewing the developments of anode materials of lithium ion battery in this paper, with Zn₂SnO₄ and Mg-Sn composite oxides anode materials as objects of the research, they were characterized by thermo-gravimetric and differential thermal analysis（TG/DTA）, X-ray diffraction（XRD）, scanning electron microscopy（SEM）. In the end, they were used as the anode materials of the lithium-ion battery, and their electrochemical performance were studied in detail. Our work was shown as the following:1. Inverse spinel Zn₂SnO₄ particles were successfully prepared via a hydrothermal method. The effect on the product purity and crystallinity were studied with respect to the hydrothermal reaction temperature and alkaline concentration. The difference of electrochemical performance on the as-prepared product at various alkaline concentrations and electrochemical mechanism of charging-discharging at the best conditions were specially analyzed. It showed that the optimized product, which was prepared with 0.2M of NaOH solution at 220℃for 24h, exhibited a relatively good electrochemical performance.2. The Zn₂SnO₄ round particles were derived by co-precipitation synthesis and the influenced on purity, particle size and electrochemical performance of as-prepared product were obtained by firing the precursor under different temperature. The results showed that the product of Zn₂SnO₄ had better electrochemical performance, which was synthesized at 750℃. The first specific discharge and charge capacity was 1811.7mAh/g and 1031.0mAh/g, respectively. The discharge capacity remained 593.3mAh/g after 20 cycles.3. Mg-Sn composite oxide precursors were synthesized by the hydrothermal and co-precipitation methods. A series of products could be obtained by the decomposition of precursor at different temperatures for 4h. The samples were investigated by thermo-gravimetric and differential thermal analysis, X-ray diffraction and scanning electron microscopy. It is showed that the precursor with the cubic shape was prepared via a hydrothermal reaction and the shape was retained after calcinations and co-precipitation method used in the experiment resulted in the composite oxide particle with irregular shape, demonstrating that the reaction condition of precursors were the key parameter influencing the composition and morphology of resulting particles. Larger difference of electrochemical properties was obtained under two kinds of conditions. The sample possessed relatively better electrochemical properties through hydrothermal reaction.更多还原