| Lithium ion batteries(LIBs) are gaining considerable att ention as a new generation of energy supply equipment, primarily due to their characteristics of portable, environmental and long cycle life. However, graphite-based electrodes with limited theoretical specific capacity are not sufficient to meet the increasing demand of LIBs with higher energy rate density. To this end, metal oxides have been actively investigated as potential anode materials, as they are expected to offer high specific lithium storage capacity. Nevertheless, the practical application of m etal oxides anodes is hindered by their poor cycling stability arising from the large volume change and severe particle aggregation during charge-discharge cycles.In this thesis, Zn2 Sn O4 nanoparticles were synthesized using graphene-based carbon nanomaterials as conductive matrix, aming to improve their electronic conductivity and cycling performance as the anode materials of LIBs. The main contents are presented as follows:(1) Upon oxidation and cutting of multiwall carbon nanotubes(MWCNTs), highly dispersive graphene oxide nanoribbons(GONRs) were obtained, the final r GONRs/Zn2 Sn O4 composite was further prepared through facile in situ chemical co-reduction process. Successful unzipping of MWCNTs was confirmed by SEM and TEM image of r GONRs, and the width of r GONRs were about 150 nm. From SEM and TEM, it also can be seen that almost all the Zn 2Sn O4 particles are homogeneous anchoring on the surface of r GONRs without forming free Zn2 Sn O4 particles. Compared to pure Zn2 Sn O4 particles, r GONRs/Zn2 Sn O4 composite exhibits better cycling performance. At the current density of 100 m A g-1, after 30 cycles, the charge capacity of Zn2 Sn O4 nanoparticles drops to 612.5 m Ah g-1, for r GONRs/Zn2 Sn O4 composite, a charge capacity of 794.5 m Ah g-1 can still be retained. Moreover, the results of EIS indicate a lower charge transfer resistance, greater facilitation of electronic transportation and electrolyte penetration during the electrochemical reactions of r GONRs/Zn2 Sn O4 composite electrode.(2) r GO/Zn2 Sn O4 composite was fabricated by a hydrothermal method. The as-obtained r GO/Zn2 Sn O4 composite was characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM) and thermogravimetric analysis(TGA). Electrochemical performances are evaluated using cyclic voltamme try(CV) and galvanostatic charge-discharge measurements. The TGA result demonstrates that the amount of r GO in the r GO/Zn2 Sn O4 composite is about 18%. At the current density of 200 m A g-1, r GO/Zn2 Sn O4 composite delivers a capacity of 1325.3 m Ah g-1 for the first discharge and a reversible capacity of 659.6 m Ah g-1. After 30 cycles, a charge capacity of 512.2 m Ah g-1, corresponding to a capacity retention of 90.1%.(3) r GONRs were used to reduce the restacking of r GO in r GO/ Zn2 Sn O4 composite, thus r GO/r GONRs/Zn2 Sn O4 composite with a distinctive structure were fabricated. SEM images show uniform Zn2 Sn O4 nanoparticles on the 3D network provided by r GO-r GONRs. r GONRs in the unique hybrid nanostructure not only prevent the restacking of r GO to increase the basal spacing between graphene sheets but also provides an additional electron-transport path. When tested as anode in LIBs, r GO/r GONRs/Zn2 Sn O4 composite delivers ighly reversible capacity, excellent cyclic performance, and good rate capacity. After 50 cycles, the composite keeps the charge capacity of 779.8 m Ah g-1 at the current density of 200 m A g-1. |
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