School of Chemical Engineering and Technology, Harbin Institute of Technology , Harbin 150001, China.
ACS Appl Mater Interfaces. 2013 Sep 11;5(17):8607-14. doi: 10.1021/am402124r. Epub 2013 Aug 28.
We report an rGO/Fe2O3/SnO2 ternary nanocomposite synthesized via homogeneous precipitation of Fe2O3 nanoparticles onto graphene oxide (GO) followed by reduction of GO with SnCl2. The reduction mechanism of GO with SnCl2 and the effects of reduction temperature and time were examined. Accompanying the reduction of GO, particles of SnO2 were deposited on the GO surface. In the graphene nanocomposite, Fe2O3 nanoparticles with a size of ∼20 nm were uniformly dispersed surrounded by SnO2 nanoparticles, as demonstrated by transmission electron microscopy analysis. Due to the different lithium insertion/extraction potentials, the major role of SnO2 nanoparticles is to prevent aggregation of Fe2O3 during the cycling. Graphene can serve as a matrix for Li+ and electron transport and is capable of relieving the stress that would otherwise accumulate in the Fe2O3 nanoparticles during Li uptake/release. In turn, the dispersion of nanoparticles on graphene can mitigate the restacking of graphene sheets. As a result, the electrochemical performance of rGO/Fe2O3/SnO2 ternary nanocomposite as an anode in Li ion batteries is significantly improved, showing high initial discharge and charge capacities of 1179 and 746 mAhg(-1), respectively. Importantly, nearly 100% discharge-charge efficiency is maintained during the subsequent 100 cycles with a specific capacity above 700 mAhg(-1).
我们报告了一种通过均匀沉淀法将 Fe2O3 纳米颗粒沉积在氧化石墨烯 (GO) 上，然后用 SnCl2 还原 GO 合成的 rGO/Fe2O3/SnO2 三元纳米复合材料。研究了 GO 与 SnCl2 的还原机制以及还原温度和时间的影响。在 GO 的还原过程中，SnO2 颗粒沉积在 GO 表面上。在石墨烯纳米复合材料中，Fe2O3 纳米颗粒的尺寸约为 20nm，被均匀分散在 SnO2 纳米颗粒周围，这可以通过透射电子显微镜分析得到证实。由于不同的锂离子插入/提取电位，SnO2 纳米颗粒的主要作用是防止 Fe2O3 在循环过程中聚集。石墨烯可以作为 Li+和电子传输的基质，并能够缓解在 Li 吸收/释放过程中 otherwise 会在 Fe2O3 纳米颗粒中积累的应力。反过来，纳米颗粒在石墨烯上的分散可以减轻石墨烯片的堆积。因此，作为锂离子电池阳极的 rGO/Fe2O3/SnO2 三元纳米复合材料的电化学性能得到了显著改善，初始放电和充电容量分别高达 1179 和 746mAhg(-1)。重要的是，在随后的 100 次循环中，保持了近 100%的放电-充电效率，比容量高于 700mAhg(-1)。
