【作者】 杨霜；

【导师】 麦立强；

【作者基本信息】 武汉理工大学 ， 材料学， 2011， 硕士

【摘要】 硫属化合物因为其独特的光电性能,尤其是硒化物,得到了很多的关注,一直以来都成为研究的热点。但对于FeSe2,特别是FeSe2电化学方面性质的研究还比较少,FeSe2半导体材料因具有较窄的禁带宽度、高的电子电导率、较高的比容量等优势从而在纳米锂电池材料方面具有很重要的研究意义,但是需要进一步研究以克服FeSe2存在容量衰减快、循环稳定较性差等缺点,本文采用水热法制得FeSe2纳米材料,并采用两种改性技术对FeSe2纳米材料的电化学性能进行改性,主要内容和结果如下：采用水热法制得FeSe2纳米材料,通过引入适当浓度的聚乙烯醇溶液制备出结晶度较高,纯相的FeSe2纳米材料,利用XRD、FESEM对其结构进行表征,将制得的FeSe2纳米材料做为正极材料组装成纽扣电池测试其电化学性能,FeSe2纳米材料的首次放电容量为362mAh/g,通过计算得到循环50次后的容量衰减率为2.39%。采用水热法制备得到锂化后的FeSe2纳米材料,用XRD、SEM等手段对其结构进行表征其锂化前后结构的变化,并且测试其电化学性能,锂化后的FeSe2纳米材料的电化学性能测试研究表明与未锂化的FeSe2纳米正极材料相比,循环50次后容量衰减率为1.23%,循环稳定性得到了提高,探讨锂化前后的FeSe2纳米材料的结构变化与性能之间的联系。以葡萄糖为碳源采用水热法制得了不同摩尔比的FeSe2/C纳米复合材料,并对制得的复合材料在500℃下进行热处理,利用XRD、FESEM、拉曼光谱对热处理前后的不同摩尔比的FeSe2/C复合材料进行结构表征,热处理前FeSe2/C纳米复合材料的电化学性能测试表明：随着葡萄糖摩尔量的增加,首次放电容量略有下降,热处理前不同摩尔比的FeSe2/C纳米复合材料的容量衰减率有了小幅度的减小,与未复合的FeSe2纳米正极材料相比,循环稳定性有了一定的提高。热处理后的不同摩尔比的FeSe2/C纳米复合材料的容量衰减率有了显著的减小,循环稳定性得到了显著的提高。更多还原

【Abstract】 Due to special photoelectric properties of chalcogenide, especially for selenide, they have gained increasing attention recently, become a hotspot for study. For FeSe2, there is few research focuing on electrochemical researches of FeSe2. FeSe2 semiconductor materials have import significance to research on lithium ion batteries, which have several advantages such as narrow bandgap, high electronic conductivity, high specific capacity and so on. However, the research results show that it need some research to overcome disadvantages such as quickly capacity fading, cycle stability and so on. FeSe2 nanomaterials was synthesized via hydrothermal reaction, moreover, FeSe2 nanomaterials were modified through two methods for improvement of electrochemical properties. The content of the article reads as follows:Under a appropriate concentration of polyvinyl alcohol solution, FeSe2 nanomaterials was synthesized via hydrothermal reaction with high crystallinity and pure phase. The structures of the FeSe2 nanomaterials were characterized via XRD, FESEM, and FeSe2 nanomaterials using as cathode materials were assembled fastener cell to measure electrochemical properties. First discharge capacity of FeSe2 nanomaterials is 362 mAh/g, fraction loss per cycle reaches 2.39% of by calculation after 50 cycles.Directly lithiated FeSe2 nanomaterials were synthesized by a hydrothermal reaction, the change of structures of the directly lithiated FeSe2 nanomaterials were characterized via XRD, FESEM, and measure electrochemical properties. The results of electrochemical properties tests of directly lithiated FeSe2 nanomaterials show that fraction loss per cycle after 50 cycles is 1.23%, cycle stability have been improved comparing with FeSe2 nanomaterials, then study the connection between properties and the change of the structure of before and after lithiation.Using glucose as carbon source, different mole ratio FeSe2/C composite nanomaterials were synthesized via hydrothermal reaction. And the as-prepared composite nanomaterials were heating under 500℃. The structures of the FeSe2/C composite nanomaterials were characterized via XRD, FESEM, Raman spectra. Before heat treatment, The results of electrochemical properties tests of FeSe2/C composite nanomaterials show that first discharge capacity decreasing as the amount of glucose increasing, fraction loss per cycle after 50 cycles minor reduce, comparing with FeSe2 nanomaterials, cycle stability have been improved a certain degree. After heat treatment, fraction loss per cycle after 50 cycles of FeSe2/C composite nanomaterials obviously reduce, cycle stability has been notable improved.更多还原