【作者】 李正楠；

【导师】 徐洪峰；

【作者基本信息】 大连交通大学 ， 环境科学， 2011， 硕士

【摘要】 锂离子电池作为一种新型的高能电池在性能提高方面仍有很大的空间,而负极材料性能的提高是其中的关键。碳基复合材料用于锂离子电池负极材料方面的研究已经取得了一定的进展,包括碳的金属或金属氧化物复合材料、碳表面镀聚合物及改性纳米碳管等。本文以砂糖为原料,将砂精加热离心制成纤维状,经低温焙烧碳化,高温焙烧碳化,采用高能球磨法制备炭纳米纤维(CNF),再以CNF作为载体制备MnO2/C锂离子电池负极材料。并对MnO2/C进行物理和电化学表征,与未载入MnO2的CNF电极材料性能进行比较。再以砂糖作为碳源,采用简单、低成本方法一次合成了碳包覆SnO2的SnO2/C复合负极材料。通过SEM、TEM和XRD测试可以看出,通过离心拉丝的方法制备的CNF样品颗粒小于砂糖样品。CNF的形貌更加均匀,比表面积也大于砂糖样品。载体CNF上MnO2颗粒的粒径在30nm左右,分布比较均匀,SnO2粒径约10-20nm。循环伏安测试也表明由于砂糖纤维制备的碳具有较高的比表面积,所以显现出更大的电容。MnO2/C负极材料采用循环伏安法研究,电容明显大于未添加MnO2的碳纤维。说明此方法可以使碳较均匀包裹金属氧化物,并可以同时提高两者的比表面积,减小粒径,显现出良好的电化学性能。将SnO2/C复合材料作为负极材料组装模拟电池进行了电化学性能测试。测试表明碳包覆纳米SnO2作为负极材料使电池的电化学性能有明显改善,可以有效抑制充放电循环中锡的体积膨胀,从而提高循环稳定性和比容量,表现出较高的库伦效率和循环稳定性。本文利用价格低廉,无污染的砂糖作为前驱体,把碳同储锂量高的金属氧化物制备成碳复合电极材料,并对其进行物理表征和电化学测试。结果表明碳包覆金属氧化物复合材料应用于锂离子电池负极达到高充放电效率,高循环性能,同时满足了低成本的要求。更多还原

【Abstract】 Lithium-ion batteries are most promising high power secondary batteries. The development of negative material plays an important role in the further development of Lithium-ion batteries. In recent years, many efforts have been devoted to C-based composite materials, and great progresses have been made.Nanosized SnO2/C composite and MnO2/C composite have been prepared using CNF as supports. The composite materials were characterized by X-ray diffraction (XRD) and transmission eletron microscopy (TEM). The Carbon in composite materials was amorphous. TEM results revealed that the SnO2 particles with the average crystallite size of about 10nm and MnO2 particles with the average crystallite size of 20-30nm were homogenously dispersed in the carbon matrix. The electrochemical properties of the nanosized SnO2/C and MnO2/C composites as negative materials for lithium ion batteries were also studied. Cyclic voltammetry and AC impedance (EIS) measurements show that the high discharge capacity and excellent cycling performance were obtained.In this paper, we used cheaper and no-pollution cane sugars as the precursors, and prepared the metal oxides/C composite electrode materials, which were characterized by physical and electrochemical tests. High discharge capacity and excellent cycling performance were achieved.更多还原