石墨烯硅碳复合负极材料的制备及其储锂性能研究材料工程专业论文.docxVIP

北京化工大学硕士学位论文1050 北京化工大学硕士学位论文 1050 mAh g-1，库仑效率达到61．71％，经过30次循环后电极容量仍高达 1029 mAh g一，容量保持率为98％，库仑效率稳定在95％以上，表现出 远高于原料硅的容量和循环稳定性。 在碳／sioJ纳米硅复合材料基础上制备得到石墨烯／硅／碳复合材料， 该材料呈现明显的三维多孔结构。加入石墨烯后虽然材料首次库仑效率 有所降低，但倍率性能明显提升。这是由于石墨烯良好的导电性和独特 的褶皱结构，缩短了离子传输路径，为离子和电子提供了更多的传输通 道。 关键词：碳材料，纳米硅，二氧化硅，锂离子电池，石墨烯，负极材料 II 万方数据 ABSTRACTFABRICATION ABSTRACT FABRICATION AND LITHIUM SToRAGE PRoPERTIES oF GRAPHENE／SILICON，CARBON COMPoSITE AS ANoDEMATERIALS ABSTRACT Silicon has been regarded as one of the most promising next-generation lithium．ion batteries anode materials due to its ultrahigh theoretical specific capacity and low discharge potential．However,the large volume changes in silicon upon insertion and extraction of lithium—ions destroy the electrode materials，which to rapid capacity fading．Meanwhile silicon has poor electrical conductivity, which limits its commercial application． Nanostructured silicon or silicon combine with carbon materials Can significantly reduce the volume effect of silicon—based materials．By taking advantages of good mechanical properties of Si02 and good electrical conductivity of carbon materials，silicon／carbon anode materials with novel structure，controllable shape and good cycle performance were prepared through different methods． Nano-silicon particles coated a l Onm layer of Si02 was prepared through the hydrolysis of tetraethyl orthosilicate，with different sized particles of III 万方数据 万方数据 万方数据 北京化工大学硕士学位论文narlo—silicon 北京化工大学硕士学位论文 narlo—silicon as raw materials．Based Oll the prepared Si02／Si materials， carbon／SiOJSi composites were prepared with sucrose and RF resin as carbon sources respectively．It indicated that Si02 and carbon double coated Oll silicon particles．Si02 layer with strong mechanical properties limited the expansion degree of silicon during the lithiating process．Carbon layer can also provide the transmission channel for ions and electrons by its excellent conductivity,as well as a protective layer．The cycle stability of materials has