He Dafang, Li Lixian, Bai Fengjuan, Zha Chenyang, Shen Liming, Kung Harold H, Bao Ningzhong
State Key Laboratory of Material-Oriented Chemical Engineering, College of Chemistry and Chemical Engineering, Nanjing Tech University (Former Name: Nanjing University of Technology), Nanjing, Jiangsu, 210009, P. R. China.
Jiangnan Graphene Research Institute, Changzhou, Jiangsu, 213149, P. R. China.
Chemistry. 2016 Mar 18;22(13):4454-9. doi: 10.1002/chem.201504429. Epub 2016 Feb 16.
A unique hierarchically nanostructured composite of iron oxide/carbon (Fe3O4/C) nanospheres-doped three-dimensional (3D) graphene aerogel has been fabricated by a one-pot hydrothermal strategy. In this novel nanostructured composite aerogel, uniform Fe3O4 nanocrystals (5-10 nm) are individually embedded in carbon nanospheres (ca. 50 nm) forming a pomegranate-like structure. The carbon matrix suppresses the aggregation of Fe3O4 nanocrystals, avoids direct exposure of the encapsulated Fe3O4 to the electrolyte, and buffers the volume expansion. Meanwhile, the interconnected 3D graphene aerogel further serves to reinforce the structure of the Fe3O4/C nanospheres and enhances the electrical conductivity of the overall electrode. Therefore, the carbon matrix and the interconnected graphene network entrap the Fe3O4 nanocrystals such that their electrochemical function is retained even after fracture. This novel hierarchical aerogel structure delivers a long-term stability of 634 mA h g(-1) over 1000 cycles at a high current density of 6 A g(-1) (7 C), and an excellent rate capability of 413 mA h g(-1) at 10 A g(-1) (11 C), thus exhibiting great potential as an anode composite structure for durable high-rate lithium-ion batteries.
通过一锅水热法制备了一种独特的具有分级纳米结构的氧化铁/碳（Fe3O4/C）纳米球掺杂三维（3D）石墨烯气凝胶复合材料。在这种新型的纳米结构复合气凝胶中，均匀的Fe3O4纳米晶体（5 - 10纳米）分别嵌入碳纳米球（约50纳米）中，形成石榴状结构。碳基体抑制了Fe3O4纳米晶体的聚集，避免了被包裹的Fe3O4直接暴露于电解质，并缓冲了体积膨胀。同时，相互连接的3D石墨烯气凝胶进一步增强了Fe3O4/C纳米球的结构，并提高了整个电极的电导率。因此，碳基体和相互连接的石墨烯网络包裹着Fe3O4纳米晶体，使得即使在断裂后它们的电化学功能仍得以保留。这种新型的分级气凝胶结构在6 A g(-1)（7 C）的高电流密度下经过1000次循环后仍具有634 mA h g(-1)的长期稳定性，在10 A g(-1)（11 C）时具有413 mA h g(-1)的优异倍率性能，因此作为耐用高倍率锂离子电池的负极复合结构展现出巨大潜力。
