We report a facile and efficient approach to prepare graphene and FeCl3-intercalated few-layer graphene (FeCl3-FLG) with stage 1 FeCl3-graphite intercalation compounds (GICs) as a precursor by a non-oxidation process. The enlarged interlayer spacing by the intercalation of FeCl3 greatly weakens the interaction among graphite sheets and thus facilitates the exfoliation of FeCl3-GICs. By ultrasonic treatment, FeCl3-GICs are well exfoliated to graphene sheets (<2 nm) with a high yield of 100%, while the ultrasonication of pristine graphite is less efficient with a low yield (about 32%) of graphene sheets. By simply controlling the sonication time, FeCl3-FLG consisting of graphene sheets and sandwiched FeCl3 is also prepared, which exhibits a high capacity of 989 mA h g−1 after 50 cycles, fairly higher than that of the sonicated graphite (503 mA h g−1) and the theoretical value of graphite (372 mA h g−1). Furthermore, FeCl3-FLG still retains a reversible capacity as high as 539 mA h g−1 even at a current density of 1000 mA g−1. Therefore, the high reversible capacity, remarkable cycling stability and superior capability make FeCl3-FLG promising as anode materials for large-scale and high-capacity lithium ion batteries.
Peng-an Zong,Zhengdong Mao,Yixiang Ou,Taifeng Shi,Zhiweng Wang,Qihao Zhang,Peng Zhang,Chunlei Wan
Filling the icosahedral lattice holes of the cage-compound CoSb 3 with alkali, alkaline-earth and rare-earth metal atoms can endow CoSb 3 with the transport characteristic of "phonon-glass-electron-crystal". However, the filler atoms greatly increase the cost in raw material as well as fabrication complexity. In this work, we embedded FeCl 3 -intercalated graphene nanolayers into polycrystalline CoSb 3 by a solution-dispersion method combined with spark plasma sintering technology. The graphene nanosheets were mainly distributed in grain boundaries. Due to the increased carrier concentration and mobility, the electrical conductivity was improved. Meanwhile, due to the enhanced interfacial phonon scattering, the lattice thermal conductivity was effectively suppressed. The thermoelectric figure of merit of the nanocomposite reached 0.6 at a mass content of 0.2 % FeCl 3 -intercalated graphene nanolayers, outperforming all reported values of binary CoSb 3 based nanocomposites, and even comparable to that of commercially used filled p-type Fe 3 CoSb 12 . This work provides a promising strategy for low-cost fabrication of p-type skutterudites.
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